Title of Invention	ENGINE LOAD DETECTOR AND ENGINE LOAD DETECTING METHOD
Abstract	To provide an engine load detector that can reduce an effect of the dimensional tolerance of a pulser rotor in consideration of the variation of engine speed and can detect a more precise loaded condition of an engine. [Solution] A detection interval for detecting an average engine speed NeA is set to a length for two rotations of a crankshaft starting from a starting point G3 of the passage of a second reluctor 12. The detection interval is divided into four intervals including a first reluctor interval and a second reluctor interval respectively corresponding to a position in which the second reluctor 12 passes a pickup 20, and a first interval and a second interval respectively corresponding to a position in which the second reluctor 12 does not pass. A first average H1 which is an average of first revolution speed ω4 (n - 1) and second revolution speed ω4 (n) is calculated and a second average H2 which is an average of first reluctor revolution speed ωtdc1 and second reluctor revolution speed ωtdc2 is calculated. NeA is calculated by multiplying a value acquired by dividing the first average H1 by the first revolution speed ω4 (n -1) by the second average H2.

Title of Invention

ENGINE LOAD DETECTOR AND ENGINE LOAD DETECTING METHOD

Abstract

To provide an engine load detector that can reduce an effect of the dimensional tolerance of a pulser rotor in consideration of the variation of engine speed and can detect a more precise loaded condition of an engine. [Solution] A detection interval for detecting an average engine speed NeA is set to a length for two rotations of a crankshaft starting from a starting point G3 of the passage of a second reluctor 12. The detection interval is divided into four intervals including a first reluctor interval and a second reluctor interval respectively corresponding to a position in which the second reluctor 12 passes a pickup 20, and a first interval and a second interval respectively corresponding to a position in which the second reluctor 12 does not pass. A first average H1 which is an average of first revolution speed ω4 (n - 1) and second revolution speed ω4 (n) is calculated and a second average H2 which is an average of first reluctor revolution speed ωtdc1 and second reluctor revolution speed ωtdc2 is calculated. NeA is calculated by multiplying a value acquired by dividing the first average H1 by the first revolution speed ω4 (n -1) by the second average H2.

Full Text	[Document Name] Specification [Title of the Invention] ENGINE LOAD DETECTOR AND ENGINE LOAD DETECTING METHOD [Technical Field] [0001] The present invention relates to an engine load detector and an engine load detecting method, particularly relates to an engine load detector that detects a loaded condition of an engine based upon an output signal from a pulser rotor rotated in synchronization with a crankshaft and an engine load detecting method. [Background Art] [0002] Heretofore, an engine load detector which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine and a pickup coil that detects a state in which a reluctor provided to the pulser rotor passes and which detects a loaded condition of the engine based upon a pulse signal output from the pickup coil is known. [0003] In a patent document 1, technique for providing a reluctor of a pulser rotor in the vicinity of a position corresponding to a top dead center of an engine, calculating the ratio of time in which the pulser rotor is rotated once and time in which the reluctor passes per one turn or per two turns and detecting a loaded condition of the engine based upon a degree of the variation of the ratio is disclosed. [CitationList] [Patent Literature] [0004] [Patent Literature 1] JP-A No. 2002-115598 [Summary of Invention] [Technical Problem] [0005] However, the technique disclosed in the patent literature 1 is technique for detecting the passing time of the reluctor with time in which the crankshaft is rotated once as a reference and it has not been considered to detect a more suitable loaded condition by setting a longer interval, for example, time in which the crankshaft is rotated twice as the reference. Further it has not been examined that the engine speed varies according to four strokes (an intake stroke, a compression stroke, a combustion and expansion stroke and an exhaust stroke) of a four-cycle engine while the crankshaft is rotated once. [0006] When the length in a circumferential direction of the reluctor has a dimensional error by dimensional tolerance, an effect of the dimensional tolerance is also left in calculated ratio as it is and a loaded condition of the engine may be unable to be precisely detected because the technique disclosed in the patent literature 1 is technique for detecting the passing time of the reluctor with time in which the crankshaft is rotated once as the reference. It is known that the rotational speed (the angular velocity) of the crankshaft is apt to be influenced by a torque transmitting system from the crankshaft to a rear wheel and accordingly, configuration that enables calculating a load also in consideration of such a situation is desired. [0007] An object of the present invention is to address the problem of the related art and to provide a load detector that reduces an effect of dimensional tolerance of a pulser rotor in consideration of the variation of revolution generated according to four strokes of a four-cycle engine and can more precisely detect a loaded condition of the engine and a load detecting method. [Solution to Problem] [0008] To achieve the object, the present invention is based upon an engine load detector which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, and has a first characteristic that a unit that calculates an interval engine speed per interval acquired by dividing a predetermined interval for detecting an average engine speed into plural intervals based upon each output signal from the pickup, a weighting unit that applies different weighting processing to the plural interval engine speeds and a loaded condition calculating unit that calculates average engine speed based upon an average of the plural weighted interval engine speeds and operates a loaded condition of the engine using the average engine speed. [0009] The present invention has a second characteristic that in the weighting processing, a weighting ratio for the interval including a combustion and expansion stroke out of the plural divided intervals is set to be larger than another interval. [0010] The present invention has a third characteristic that the predetermined interval is detected based upon the output signal from the pulser rotor. [0011] The present invention has a fourth characteristic that the predetermined interval is set so that a length for two rotations of the crankshaft is divided into two, i.e. a first interval and a second interval, the first interval includes an intake stroke, and the second interval includes a combustion and expansion stroke. [0012] The present invention has a fifth characteristic that a loaded condition of the engine is a load factor calculated by dividing a revolution speed while the reluctor passes the pickup by the average engine speed. [0013] The present invention has a sixth characteristic that the reluctor is arranged in a position immediately before the top dead center of the engine and the load factor is calculated using a revolution speed while the reluctor passes the pickup immediately before a top dead center on a compressive side. [0014] The present invention has a seventh characteristic that feedback control over at least an ignition timing of the engine is made according to the calculated load factor. [0015] The present invention is based upon an engine load detecting method of a device which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, and has an eighth characteristic that the engine load detecting method includes a procedure for dividing a predetermined interval for detecting an average engine speed into plural intervals when the average engine speed used to detect the loaded condition of the engine is calculated, a procedure for calculating an interval engine speed per divided interval, a procedure for applying different weighting processing to the plural interval engine speeds and a procedure for calculating the average engine speed by calculating an average of the plural weighted interval engine speeds. [0016] The present invention is based upon an engine load detector which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, and has a ninth characteristic that a detection interval for detecting an average engine speed is set to a length for two rotations of the crankshaft starting from a starting point of the passage of the reluctor, the detection interval is divided into four intervals including a first reluctor interval and a second reluctor interval respectively corresponding to a position in which the reluctor passes the pickup per rotation out of the two rotations of the crankshaft, and a first interval and a second interval respectively corresponding to a position in which the reluctor does not pass the pickup and the engine load detector is provided with a unit that calculates a first average which is an average of a first revolution speed detected in the first interval and a second revolution speed detected in the second interval, a unit that calculates a second average which is an average of a first reluctor revolution speed detected in the first reluctor interval and a second reluctor revolution speed detected in the second reluctor interval, a unit that calculates the average engine speed by multiplying a value acquired by dividing the first average by the first revolution speed by the second average and a loaded condition calculating unit that calculates a loaded condition of the engine using the average engine speed. [0017] The present invention has a tenth characteristic that the unit that calculates the average engine speed calculates the average engine speed NeA by the following expression: [0018] [Mathematical expression 1] where the first revolution speed is 0)4 (n - 1), the second revolution speed is u4 (n) , the first reluctor revolution speed is cotdcl, the second reluctor revolution speed is cotdc2 and the weighting factor in the weighting processing is a. [0019] The present invention has an eleventh characteristic that the first interval includes an intake stroke, the second interval includes a combustion and expansion stroke and the weighting factor a used in different weighting processing between the first revolution speed and the second revolution speed when the first average is calculated is set to 0.5 or larger. [0020] The present invention has a twelfth characteristic that the reluctor is arranged in a position immediately before a top dead center of the engine and a loaded condition of the engine is a load factor calculated by dividing the second reluctor revolution speed by the average engine speed. [0021] The present invention has a thirteenth characteristic that feedback control over at least an ignition timing of the engine is made according to the load factor. [0022] Further, the present invention is based upon an engine load detecting method of an engine load detector which is provided with a pulsar rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, and has a fourteenth characteristic that the engine load detecting method includes a procedure for setting a detection interval for detecting an average engine speed to a length for two rotations of the crankshaft starting from a starting point of the passage of the reluctor, a procedure for dividing the detection interval into four intervals including a first reluctor interval and a second reluctor interval respectively corresponding to a position in which the reluctor passes the pickup,per rotation out of the two rotations of the crankshaft, and a first interval and a second interval respectively corresponding to a position in which the reluctor does not pass the pickup, a procedure for calculating a first average which is an average of a first revolution speed detected in the first interval and a second revolution speed detected in the second interval, a procedure for calculating a second average which is an average of a first reluctor revolution speed detected in the first reluctor interval and a second reluctor revolution speed detected in the second reluctor interval and a procedure for calculating the average engine speed by multiplying a value acquired by dividing the first average by the first revolution speed by the second average. [0023] The present invention is based upon an engine load detector which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, and has a fifteenth characteristic that a transmission gear ratio detecting unit that detects the gear ratio of a transmission is provided, a loaded condition of the engine can be grasped with a load factor calculated by dividing the rotational speed while the reluctor passes the pickup by average engine speed and the rotational speed while the reluctor passes the pickup is corrected based upon the transmission gear ratio. [0024] The present invention has a sixteenth characteristic that the transmission gear ratio detecting unit is a gear position sensor that detects the speed stage of a stepped transmission. [0025] The present invention has a seventeenth characteristic that the correction of rotational speed while the reluctor passes the pickup is executed by multiplying the rotational speed by a correction factor and the correction factor is set so that the smaller the number of gear stages of the stepped transmission is, the larger the correction factor is. [0026] Further, the present invention has an eighteenth characteristic that the transmission gear ratio detecting unit calculates transmission gear ratio based upon vehicle speed and engine speed. [Advantageous Effects of Invention] [0027] According to the first characteristic, since the predetermined interval for detecting the engine speed is divided into plural intervals when the average engine speed used for operating the loaded condition of the engine is calculated, an interval engine speed per divided interval is calculated, different weighting processing is applied to the plural interval engine speeds and further, the average engine speed is calculated by calculating the average of the plural weighted interval engine speeds, suitable average engine speed can be calculated by weighting in consideration of the variation of the rotation even if the rotation greatly varies in the predetermined interval differently from that in a steady driving mode. Hereby, even if engine speed greatly varies in the predetermined interval in acceleration and in running on an irregular road, an engine loaded condition corresponding to this situation can be acquired by operation. [0028] According to the second characteristic, since the ratio of the weighting of the interval including the combustion and expansion stroke out of the plural divided intervals is set to be larger than another interval in the weighting processing, a load of the engine corresponding to this can also be acquired by operation in acceleration and in running on an irregular road, particularly when a degree of the rise of engine speed increases at the combustion and expansion stroke. [0029] According to the third characteristic, as the predetermined interval is detected based upon an output signal from the pulser rotor, the predetermined interval for detecting the average engine speed can be set using the pulser rotor that detects timing for driving an igniter and a fuel injection system of the engine. Hereby, the engine loaded condition can be acquired by operation without providing a new sensor and the like. [0030] According to the fourth characteristic, since the predetermined interval is set so that the length for two rotations of the crankshaft is divided into two, i.e. the first interval and the second interval, the first interval includes the intake stroke and the second interval includes the combustion and expansion stroke, the predetermined interval can be divided by a simple method. As the weight of the second interval including the combustion and expansion stroke is set to be large, a loaded condition in consideration of the variation of engine speed at the combustion and expansion stroke can be acquired by operation. As the predetermined interval is divided in a minimum number, the effect of weighting processing can be acquired while inhibiting the increase of a load on operation. [0031] According to the fifth characteristic, as the loaded condition of the engine is the load factor calculated by dividing a revolution speed while the reluctor passes the pickup by the average engine speed, the loaded condition of the engine can be acquired by a simple arithmetic expression. [0032] According to the sixth characteristic, since the reluctor is arranged in the position immediately before the top dead center of the engine and the load factor is calculated using a revolution speed while the reluctor passes the pickup immediately before the top dead center on the compressive side, the large variation of engine speed from the end of the compression stroke to the combustion and expansion stroke is suitably detected and the load factor of the engine in consideration of the variation of engine speed can be acquired. [0033] According to the seventh characteristic, since the feedback control over at least the ignition timing of the engine is made according to the calculated load factor, correction control over at least the ignition timing is enabled using only the output signal from the pulser rotor without providing a new sensor and the like. [0034] According to the eighth characteristic, since the engine load detecting method includes the procedure for dividing the predetermined interval for detecting the average engine speed into the plural intervals, the procedure for calculating interval engine speed per divided interval, the procedure for applying different weighting if processing to the plural interval engine speeds, the procedure for calculating average engine speed by calculating the average of the plural weighted interval engine speeds and the procedure for operating the engine loaded condition using the average engine speed, suitable average engine speed is calculated by executing weighting in consideration of the variation of engine speed even if large variation different from variation in the steady driving mode occurs in engine speed in the predetermined interval, and the engine loaded condition can be operated based upon the suitable average engine speed. [0035] According to the ninth characteristic, since the detection interval for detecting the average engine speed is set to the length for two rotations of the crankshaft starting from the starting point of the passage of the reluctor, the detection interval is divided into the four intervals including the first reluctor interval and the second reluctor interval respectively corresponding to the position in which the reluctor passes the pickup per rotation out of the two rotations of the crankshaft, and the first interval and the second interval respectively corresponding to the position in which the reluctor does not pass the pickup and the engine load detector is provided with the unit that calculates the first average which is the average of the first revolution speed detected in the first interval and the second revolution speed detected in the second interval, the unit that calculates the second average which is the average of the first reluctor revolution speed detected in the first reluctor interval and the second reluctor revolution speed detected in the second reluctor interval, the unit that calculates an average engine speed by multiplying the value acquired by dividing the first average by the first revolution speed by the second average and the loaded condition calculating unit that calculates the loaded condition of the engine using the average engine speed, the relation of dividing the revolution speed of the reluctor part by the revolution speed of the same reluctor part can be included in an arithmetic expression for calculating the average engine speed. Hereby, even if the length in the circumferential direction of the reluctor has dimensional tolerance, the effect of the dimensional tolerance in the arithmetic expression can be reduced and more suitable average engine speed can be calculated. The detection interval for detecting average engine speed can be set using the pulser rotor for detecting timing for driving the igniter and the fuel injection system of the engine. [0036] According to the tenth characteristic, the effect which the dimensional tolerance of the reluctor has the calculated value of the average engine speed can be reduced in the arithmetic expression of the average engine speed. [0037] According to the eleventh characteristic, since the first interval includes the intake stroke, the second interval includes the combustion and expansion stroke and the weighting factor a for executing different weighting processing between the first revolution speed and the second revolution speed when the first average is calculated is set to 0.5 or larger, the average engine speed in consideration of the degree of the rise of engine speed at the combustion and expansion stroke can be calculated even if the large variation different from variation in the steady driving mode occurs in engine speed in the detection interval. Hereby, even if the variation of engine speed increases in acceleration and according to a situation of a road, the more suitable load on the engine can be calculated. [0038] According to the twelfth characteristic, since the reluctor is arranged in the position immediately before the top dead center of the engine and the loaded condition of the engine is the load factor calculated by dividing the second reluctor revolution speed by the average engine speed, a load on the engine can be detected by a simple arithmetic expression. Besides, the variation of engine speed from the latter half of the compression stroke to the combustion and expansion stroke is suitably detected and the load factor of the engine can be acquired. [0039] According to the thirteenth characteristic, since the feedback control over at least the ignition timing of the engine is made according to the load factor, the load factor of the engine is calculated using only the output signal from the pulser rotor and the correction control over at least the ignition timing of the engine can be made based upon the load factor. Hereby, the suitable ignition timing control can be executed without providing a sensor that detects the loaded condition of the engine and the 11 ke. [0040] According to the fourteenth characteristic, since the engine load detecting method includes the procedure for setting the detection interval for detecting the average engine speed to the length for two rotations of the crankshaft starting from the starting point of the passage of the reluctor, the procedure for dividing the detection interval to the four intervals including the first reluctor interval and the second reluctor interval respectively corresponding to the position in which the reluctor passes the pickup per rotation out of the two rotations of the crankshaft, and the first interval and the second interval respectively corresponding to the position in which the reluctor does not pass the pickup, the procedure for calculating the first average which is the average of the first revolution speed detected in the first interval and the second revolution speed detected in the second interval, the procedure for calculating the second average value which is the average of the first reluctor revolution speed detected in the first reluctor interval and the second reluctor revolution speed detected in the second reluctor interval and the procedure for calculating an average engine speed by multiplying the value acquired by dividing the first average by the first revolution speed by the second average, the effect of the dimensional tolerance of the reluctor can be reduced in an arithmetic expression even if the length in the circumferential direction of the reluctor has the dimensional tolerance and a more precise average engine speed can be calculated. Hereby, the suitable load on the engine can be calculated. [0041] According to the fifteenth characteristic, as the transmission gear ratio detecting unit that detects the gear ratio of the transmission is provided, the loaded condition of the engine can be grasped with a load factor calculated by dividing the rotational speed while the reluctor passes the pickup by average engine speed and the rotational speed while the reluctor passes the pickup is corrected based upon transmission gear ratio, the loaded condition of the engine can be calculated also in consideration of the effect of the torque transmitting system from the crankshaft to the rear wheel. Concretely, a phenomenon that the larger the gear ratio of the transmission is, the smaller the rotational speed while the reluctor passes the pickup is can be coped with and hereby, the loaded condition of the engine can be more precisely calculated. [0042] According to the sixteenth characteristic, as the transmission gear ratio detecting unit is the gear position sensor that detects the speed stage of the stepped transmission, the gear ratio of the stepped transmission is detected with simple configuration and the rotational speed while the reluctor passes the pickup can be corrected. [0043] According to the seventeenth characteristic, as the correction of the rotational speed while the reluctor passes the pickup is executed by multiplying the rotational speed by a correction factor and the correction factor is set so that the smaller the number of gear stages of the stepped transmission is, the larger the correction factor is, there can be made suitable correction in accordance with a tendency that the following increase of the transmission gear ratio is apt to have an effect upon the torque transmitting system from the crankshaft to the rear wheel increases as the gear ratio of the transmission increases, in other words, a tendency that the rotational speed while the reluctor passes the pickup decreases as the gear ratio increases even if an actual loaded condition of the engine is the same. [0044] According to the eighteenth characteristic, as the transmission gear ratio detecting unit calculates the transmission gear ratio based upon vehicle speed and engine speed, a position sensor for detecting the speed stage of the gear is not reguired and the reduction of the cost can be expected. [Brief Description of Drawings] [0045] [Fig. 1] Fig. 1 is a block diagram showing an engine to which an engine load detector equivalent to one embodiment of the present invention is applied. [Fig. 2] Fig. 2 is a block diagram showing the details of a load factor calculating unit provided to the ECU. [Fig. 3] Fig. 3 is an enlarged front view showing a pulser rotor. [Figs. 4] Figs. 4 are graphs showing relation among a crank pulse signal, engine speed Ne and angular velocity CD . [Fig. 5] Fig. 5 is a graph showing relation between a crank pulse signal for one cycle and angular velocity co. [Fig. 6] Fig. 6 is an enlarged view showing a part of Fig. 5. [Figs. 7] Figs. 7 are graphs showing the variation of angular velocity oa in a steady driving mode and in a transient condition. [Fig. 8] Fig. 8 is a graph showing relation between angular velocity co in the transient state and a detection interval. [Fig. 9] Fig. 9 shows a concept of weighting processing. [Fig. 10] Fig. 10 is a graph showing a method of deriving a weighting factor a. [Fig. 11] Fig. 11 is an explanatory drawing showing relation between a detection interval when a method of canceling reluctor tolerance is applied and an Nel interval and an Ne2 interval. [Fig. 12] Fig. 12 is a graph showing relation between angular velocity co in the transient state and the detection interval. [Fig. 13] Fig. 13 is an explanatory drawing showing an arithmetic expression for calculating Aco. [Fig. 14] Fig. 14 is a block diagram showing a procedure for calculating average engine speed NeA. [Fig. 16] Fig. 15 is a graph showing relation between engine speed Ne and a calculated value of Aco (Aco = Ne - ffitdc). [Fig. 16] Fig. 16 is a correction factor map showing relation among engine speed Ne, speeds of the gear and a correction factor K. [Fig. 17] Fig. 17 is a flowchart showing a procedure for correction control over Aco using the correction factor K. [Description of Embodiments] [0046] Referring to the drawings, a preferred embodiment of the present invention will be described in detail below. Fig, 1 is a block diagram showing the configuration of an engine 1 to which an engine load detector equivalent to one embodiment of the present invention is applied. The engine 1 is a 4-cycle single-cylinder internal combustion engine and has configuration that a piston 7 reciprocated inside a cylinder 8 is coupled to a crankshaft 9 via a connecting rod. An intake pipe 2 and an exhaust pipe 4, an intake valve 3 and an exhaust valve 5 respectively opened or closed in synchronization with the rotation of the crankshaft 9 are provided in an upper part of the cylinder 8. An ignition plug 6 as an ignition device is attached at an upper end of the cylinder 8. [0047] A pulser rotor 10 rotated in synchronization with the crankshaft 9 is attached to the crankshaft 9. A reluctor protruded outside in a radial direction by predetermined quantity is provided on a periphery of the pulser rotor 10. In the vicinity of the pulser rotor 10, a magnetic pickup 20 fixed to a crankcase and others of the engine 1 is arranged, reacts to the passage of the reluctor according to the rotation of the pulser rotor 10, and outputs a crank pulse signal. [0048] An ECU 30 as an engine control unit includes a crank pulse detector 40 that detects a pulse signal from the magnetic pickup 20, a load factor calculator 50 as loaded condition detecting unit of the engine 1, a control correction quantity calculator 60 that calculates the correction quantity of ignition timing according to a loaded condition of the engine, an ignition controller 70 that controls the ignition of the ignition plug 6 and an ignition map 80 for determining ignition timing at least based upon the information of a throttle angle and engine speed Ne. The ECU 30 in this embodiment obtains a loaded condition (a load factor F) of the engine 1 based upon a pulse signal input to the crank pulse detector 40 and can control so that the ignition timing of the ignition plug 6 is corrected according to the loaded condition. [0049] In this case, the load factor F of the engine 1 denotes the magnitude of a load represented in a numeric value to use the magnitude of the load for correction control because a condition of a load applied to the engine 1 is different in a case that a vehicle is driven on a flat road at fixed speed and in a case that the vehicle is accelerated on an ascending slope even if the engine speed is the same. The ignition controller 70 can acquire suitable ignition timing according to a loaded condition such as corrects ignition timing to be slightly lagged and prevents knocking when the load factor F is large, that is, a load applied to the engine is large. The details of a method of operating the load factor F will be described later. [0050] In this embodiment, only the correction control of ignition timing is executed using the load factor F, however, the ECU 30 may also control, a fuel injection system (not shown) that supplies fuel to the engine 1 and may also execute fuel injection control according to the load factor F, [0051] Fig. 2 is a block diagram showing the details of the load factor calculator 50 provided to the ECU 30. The load factor caiculator 50 calculates the load fact of F of the engine 1 based upon a crank pulse signal input from the crank pulse detector 40 and time measured by a timer 51. The load factor calculator 50 includes an Ne calculating unit 52, a Aco calculating unit 53, an cotdc calculating unit 54, a reluctor electrical angle determining unit 55 and a load factor calculating unit 56 in addition to the timer 51 [0052] The Ne calculating unit 52 calculates engine speed Ne (average engine speed NeA) at a detection interval. The reluctor electrical angle determining unit 55 detects an angle in a circumferential direction electrically detected of the reluctor based upon a pulse signal when the reluctor passes the magnetic pickup 20. The ©tdc calculating unit 54 calculates the revolution speed (the angular velocity) of the pulsar rotor 10 while the reluctor passes the magnetic pickup 20, that is, the angular velocity cotdc (rad/s) of only the reluctor part. [0053] The Aco calculating unit 53 calculates the variation A(o of crank angular velocity by subtracting the angular velocity cotdc of the reluctor part calculated by the cotdc calculating unit from engine speed Ne calculated by the Ne calculating unit 52 (Aco = Ne - cotdc) . The subtraction by the Aco calculating unit 53 is executed by converting engine speed Ne (rpm) to engine revolution speed (rad/s). The load factor calculating unit 56 calculates the engine load factor F according to an arithmetic expression, Aco / Ne >« 100 (%) using the variation Ao of the angular velocity calculated by the A© calculating unit 53 and the engine speed Ne calculated by the Ne calculating unit 52. The larger a load of the engine is, the larger numeric value the load factor F is. [0054] Fig. 3 is an enlarged front view showing the pulser rotor 10. A first reluctor 11 and a second reluctor 12 are provided to the pulser rotor 10 in this embodiment. In Fig 3, the pulser rotor 10 is rotated counterclockwise and a crank pulse signal from the magnetic pickup 20 is sequerit ially output at a starting point GI of the first reluctor 11, at an end point G2 of the first reluctor 11, at a starting point G3 of the second reluctor 12 and at an end point G4 of the second reluctor 12. [0055] The second reluctor 12 has length in the circumferential direction for a first angle 91 from a position apart by a fourth angle 94 from a top dead center (TDC) of the engine. The first reluctor 11 has length in the circumferential direction for a third angle 93 and a second angle 62 is angle between the starting point Gl of the first reluctor 11 and the starting point G3 of the second reluctor 12. In this embodiment, the first angle 91 is set to 45 degrees, the second angle 92 is set to 22.5 degrees, the third angle 93 is set to 11.25 degrees, and the fourth angle 94 is set to 15 degrees. In Fig. 3, the pulser rotor 10 and the magnetic pickup 20 are shown in an apart condition; however, an interval between the periphery of each reluctor 11, 12 and the magnetic pickup 20 is set to 0.5 mm for example. [0056] Fig. 4 is graphs showing relation among a crank pulse signal output from the magnetic pickup 20, average engine speed NeA per rotation of the crankshaft and the angular velocity © of the crankshaft. An interval between A and B in Fig. 4 shows a time interval for one rotation of the crankshaft including an intake stroke. The graph (a) shows a steady driving mode in which a vehicle is driven on a flat road at fixed engine speed Ne and the graph (b) shows a transient state while engine speed Ne rises in acceleration and by the operation of a throttle. The graph (c) shows only the variation of angular velocity co in driving on a wavy (irregular) road. [0057] These graphs tell that though engine speed is fixed or increased, crank angular velocity co repeats periodical variation according to one cycle of the engine. The observation for a long term of the variation of angular velocity co on a wavy road tells that a gentle wavy motion is generated as a whole because force for accelerating/decelerating a driving wheel or driving wheels acts because of an irregular road. However, it remains unchanged that periodical variation according to one cycle of the engine is also repeated on the wavy road in units of one rotation of the crankshaft. It can be verified that on any driving condition, angular velocity © linearly varies in the interval including the intake stroke between A and B A linear locus of angular velocity to in the interval between A and B greatly falls rightward in the steady driving mode shown in (a) and an angle of the rightward fall greatly decreases in the transient state shown in (b). [0058] Fig. 5 is a graph showing relation in one cycle between a crank pulse signal and angular velocity co. The same reference numeral as the above-mentioned one denotes the same or the similar part. As described above, angular velocity co periodically varies according to each stroke of four cycles. A decrease in an interval Dl from a latter half of a compression stroke to a combustion and expansion stroke is caused by resistance to compression due to a rise of pressure inside the cylinder. An increase in an interval D2 at the combustion and expansion stroke is caused by the generation of crank rotating energy due to a rise of pressure inside the cylinder by combustion. [0059] A decrease in an interval D3 until an intake stroke is finished after the interval D2 is finished is caused by the generation of the mechanical frictional resistance of the engine 1 and the generation of resistance to the exhaust of combustion gas after combustion is finished and crank angular velocity co reaches its peak. An interval D4 shows a time interval for one rotation of the crank with the starting point G3 of the second reluctor 12 as a starting point: . [00060] In Fig. 5, when engine speed (revolution speed) Ne is the same, crank angular velocity a in the steady driving mode is shown by a full line and crank angular velocity © when a large load is applied is shown by a broken line. As shown in Fig. 5, when a large load is applied, the variation of angular velocity co becomes large. This reason is that even if engine speed Ne is the same, a peak of angular velocity co becomes larger as output torque increases and the more the quantity of taken air is, the larger the quantity of a fall after that is. [0061] The variation of crank angular velocity co becomes larger in an area of less rotation in which the inertia force of the crankshaft decreases and in an engine having cylinders of a small number and having a large interval of explosion such as the single-cylinder engine 1 in this embodiment, the variation has a tendency toward being further larger. [0062] Fig. 6 is an enlarged view showing a part of Fig. 5. As described above, a loaded condition of the engine 1 is detected by the load factor F of the engine. The load factor F denotes a numeric value showing a degree of the decrease of angular velocity o) for engine speed Ne in the interval Dl including a compression top dead center, in other words, the magnitude of resistance to compression at the compression stroke. In this embodiment, the second reluctor 12 is located in the interval Dl and a differential value between angular velocity totdc when the second reluctor 12 passes the magnetic pickup 20 and engine speed Ne is calculated as the variation A© of angular velocity CD . An cotdc interval in Fig. 6 corresponds to the time of transit from the starting point G3 of the second reluctor 12 to the end point G4. [0063] Referring to Figs. 7, 8 and 9, weightinq processing for precisely detecting the load factor F in the transient state will be described below. The weighting processing means a method of dividing a detection interval into plural pieces when engine speed Ne in the detection interval is calculated, calculating interval engine speed per divided interval, an increasing the weight of a certain specific divided interval when plural interval engine speeds are averaged and adjusting NeA to a proper value. [0064] Fig. 7 is graphs showing the variation of angular velocity co in the steady driving mode and in the transient state. "T" in Fig. 7 denotes a top dead center (TDC). Angular velocity co in the steady driving mode shown in (a) varies between the same upper limit and the same lower limit in each cycle. Therefore, it can be said that the detection interval for calculating engine speed Ne used for calculating Aco is sufficient if only the detection interval is set to an interval for one cycle. In an example shown in Fig, 1, an interval while the crankshaft is rotated twice from the starting point Gl of the first reluctor 11, that is, for one cycle is also set to the detection interval. [0065] However, though angular velocity co in the transient state shown in (b) substantially similarly varies per cycle (has the substantially same waveform), compared with that in the steady driving mode shown in (a) , the angular velocity o continuously rises toward the next peak after it slightly falls after it reaches a peak. Hereby, a waveform of the angular velocity (D in the transient state is in a stepped shape rising rightward. At this time, when the operation of the engine load factor F is executed for both in a case that engine speed is the same in the steady driving mode and in the transient state for example, the load factor F in the transient state is calculated to be smaller than that in the steady driving mode and a phenomenon that the load factor does not correspond to a loaded condition actually caused in the engine occurs. Though l:he details are described later, this reason is that the variation Au in the transient state is calculated to be smallish, compared with the actual engine loaded condition. [0066] To cope with this, in this embodiment, for a prerequisite, the detection interval is divided into an Nel interval until the crankshaft is rotated once from the starting point Gl of the first reluctor 11 and an Ne2 interval until the crankshaft is rotated once more from an end point of the Nel interval, and average engine speed Ne (hereinafter called NeA) of the whole detection interval is calculated by averaging interval engine speed Nel (hereinafter called Nel) of the Nel interval and interval engine speed Ne2 (hereinafter called Ne2) of the Ne2 interval. This calculation process is executed by the Ne calculating unit 52. [0067] Fig. 8 is a graph showing relation between angular velocity co in the transient state and the detection interval. The same reference numeral as the above-mentioned one denotes the same or the similar part. As described above, in the transient state, the decrement of angular velocity co in an interval from the intake stroke to a former half of the compression stroke, that is, in the Nel interval decreases and in an example shown in Fig. 8, the angular velocity proceeds substantially horizontally. In the meantime, in the latter half of the compression stroke, after the angular velocity co greatly decreases, it greatly increases in the combustion and expansion stroke and reaches a peak. [0068] In this case, as described above, the engine load factor F is calculated based upon how the crank angular velocity co in the latter half of the compression stroke decreases for engine speed Ne. In this calculating method, however, when engine speed Ne is the same in the steady driving mode and in the transient state, variation Aw (Aco = Ne - o)tdc) which is difference between engin--' speed Ne and otdc has a tendency that the variation in the transient state is calculated to be smaller than that in the steady driving mode. [0069] This reason is that Ne2 of the Ne2 interval in which the cotdc interval is included is very high, compared with interval engine speed in the steady driving mode, which is an element to be regarded as important when the load factor F is calculated, is offset by calculating an average value of Nel and Ne2. Hereby, the load factor F calculated in the transient state is calculated to be smaller, compared with an actual engine loaded condition. [0070] Therefore, in the transient state, when average engine speed NeA is calculated, it is desirable that the magnitude of engine speed Ne2 is reflected. Hereby, in the example shown in Fig. 8, when NeA is calculated, different weighting processing is executed between Nel and Ne2. In the example shown in Fig. 8, the weight of Ne2 is made bigger than the weight of Nel by setting an arithmetic expression of average engine speed NeA in one cycle to "NeA = Nel X (1 - a) + Ne2 x a" and setting a weighting factor a to 0.5 or larger, and NeA is increased. A weighting unit that executes weighting processing is included in the Ne calculating unit 52 (see Fig. 2) in the load factor calculator 50. [0071] Next, a conceptual diagram showing weighting processing shown irt Fig. 9 will be referred. In an example shown in Fig. 9, an average engine speed when no weighting processing is executed is shown by NeAO (a broken line) and an average engine speed when weighting processing is executed (for example, a = 0.55) is shown by NeA (a full line). At this time, the variation of crank angular velocity co is calculated as AcoO when no weigliting processincj is executed, while when weighting processing is executed, the variation increases up to Aw (see Fig. 8). Hereby, a calculated value of the engine load factor F also increases and in the transient state, a load factor F corresponding to an actual engine loaded condition is calculated. [0072] In the steady driving mode, since the difference between Nel and Ne2 is small even if the above-mentioned weighting processing is executed, an effect upon a load factor F is small. Therefore, a method of operating a load factor F is not required to be changed between a steady-state value and a transient state and a load of operation is never increased. [0073] Fig. 10 is a graph showing a method of deriving the weighting factor a. As described above, in the steady driving mode, even if the weighting factor a is varied, a value of Aco hardly varies. In the meantime, in the transient state, as the weighting factor a is increased, Aco increases. At this time, when the weighting factor a is set to a point at which Aco in the transient state is equal to Aco in the steady driving mode, the load factors F in the steady driving mode and in the transient state can be equalized in a case that cotdc is equal. [0074] As described above, according to the engine load detector according to the invention, since the predetermined interval for detecting NeA is set to one cycle when average engine speed NeA used for calculating the load factor F (F = Aco / NeA x loo) is calculated, the predetermined interval is divided into the Nel interval including the intake stroke and the Ne2 interval including the combustion and expansion stroke in two, respective interval engine speed Nel, Ne2 are calculated, weighting processing is executed so that weight for Ne2 is larger than weight for Nel and an average of both values is calculated, the magnitude of the interval engine speed Ne2 of the Ne2 interval to be regarded as important when the load factor F is calculated is reflected on a calculated value of the load factor F and a suitable engine load can be calculated. Hereby, even if the variation of engine speed increases in acceleration and in running on an irregular road, a load of the engine corresponding to this can be acquired by operation. [0075] The configuration of the engine and the pulser rotor, the dimension and the number of the reluctors, the positions of the reluctors on the pulser rotor, the positions of the reluctors for the position of TDC, the value of the weighting factor a, the setting of the predetermined interval for detecting average engine speed NeA and others are not limited to the above-mentioned embodiment and various changes are allowed. The engine load detector according to the invention can be applied to various general purpose engines in addition to an engine of a vehicle such as a motorcycle. [0076] Next, a method of canceling reluctor tolerance applied to the engine load detector according to the invention will be described. The method of canceling reluctor tolerance reduces an effect of the dimensional tolerance of the reluctors in the arithmetic expression for calculating average engine speed NeA by utilizing the above-mentioned weighting processing and the linear transition (see Fig. 4) of the crank angular velocity © in the interval including the intake stroke. That is, the effect of the dimensional tolerance on a finally calculated load factor F can be reduced. Referring to Figs. 10 to 13, a concrete method will be described. [0077] Fig. 11 is an explanatory drawing showing relation between a detection interval when the method of canceling reluctor tolerance is applied and the Nel interval and the Ne2 interval. In this embodiment, an interval from the iitarting point G3 of the second reluctor until the crank is turne'i once is set to the interval D4 and average engine speed NeA during the interval D4 is calculated. The interval D4 is an interval displaced backward by the third angle 93 (22.5 degrees in this embodiment) based upon the Nel interval and the Ne2 interval. In this embodiment, the interval D4 is further divided into an cotdc interval (45 degrees) and an 0)4 interval (315 degrees). The setting of the intervals is executed by the Ne calculating unit 52. [0078] Fig. 12 is a graph showing relation between angular velocity co in the transient state and a detection interval. The same reference numeral as the above-mentioned one denotes the same or the similar part. In Fig. 12, the interval D4 including the combustion and expansion stroke is set to an interval D4 (n) and an interval before one turn of the crank is set to an interval D4 (n - 1) . That is, the detection interval for calculating average engine speed NeA includes the interval D4 (n - 1) and the interval D4 (n) . In the meantime, the ca4 interval includes an co4 (n) interval as a second interval and an co4 (n - 1) interval as a first interval. Further, the cotdc interval includes an 0itdc2 interval as a second reluctor interval and an otdcl interval as a first reluctor interval. [0079] Next, a method of calculating average engine speed NeA in the detection interval in the above-mentioned setting of the intervals will be examined. As described above, in the weighting processing in the transient state, it is desirable that the setting of intervals on which a characteristic that crank angular velocity co shifts linearly and without substantially decreasing from the intake stroke to a former half of the compression stroke and rapidly rises at the combustion and expansion stroke is suitably reflected is performed. Hereby, average engine speed NeA is calculated based upon an average of interval engine speed 0)4 (n - 1) of the 0)4 (n - 1) interval and interval engine speed co4 (n) of the ci)4 (n) iriterval. [00801 As a result, an arithmetic expression of NeA in which weighting is considered is "NeA = (1 - a) xco4 (n - 1) + a X034 (n)". In this embodiment, the NeA is defined not as finally calculated average engine speed NeA but as a first average HI. A value of the weighting factor a can be arbitrarily set. In the steady driving mode, however, even if the weighting factor a is varied, a value of ACD is substantially unchanged. In the meantime, in the transient state, as the weighting factor a is increased, ACD increases At this time, when the weighting factor a is set to a point at which Aco in the transient state is equal to Aco in the steady driving mode, the load factor F can be equalized in a case that cotdc is equal. [0081] Next, Fig. 13 showing an arithmetic expression for calculating Am will be also referred. As described above, as Aco = Ne - cotdc. A© is equal to NeA - 0)tdc2 when this is applied to the example shown in Fig. 12. Dimensional tolerance (for example, ±1%) is allowed for a mechanical part and a dimensional error by dimensional tolerance also occurs in a dimension in a circumferential direction of the second reluctor 12. An effect which the dimensional error in the circumferential direction has on a calculated value of Am will be described below. [0082] When the length in the circumferential direction of the second reluctor 12 shifts, a calculated value of NeA also shifts. In this case, however, it is supposed that no effect of dimensional tolerance is included in NeA. When NeA is 2000 (rpm) and utdc2 is 1800 (rpm) on the above-mentioned condition, Ao) in a case that the dimension in the circumferential direction of the second reluctor 12 is a reference value is 200 (rpm) acquired by subtracting 1800 from 2000. In the meantime, when the dimension in the circumferential direction of the second reluctor 12 is longer by 1?- than the reference value and hereby, wtdc2 is smaller by 1%, Aco is 218 (rpm) acquired by subtracting 1782 from 2000. That is, the error of 1% of the circumferential dimension of the second reluctor 12 is amplified to large difference of 10% in a calculated value of Aco. [0083] To avoid the above-mentioned amplification of dimensional tolerance, it is desirable that NeA can be represented as revolution speed calculated in the same interval of 45 degrees as Qtdc2. When this is realized, a calculated value of Aco is never off the reference value by 1% or more because the arithmetic expression of Aco is the subtraction of revolution speeds calculated in relation to the same intervals of 45 degrees. Then, in this embodiment, the arithmetic expression of NeA is transformed to make it compatible to enhance the accuracy of NeA by possibly extending the detection interval for calculating NeA, to adjust NeA to a suitable value by weighting processing and to reduce the effect of the dimensional tolerance of the second reluctor 12 on Aci). [0084] Concretely, the average (the first average HI) of Ne of the co4 (n - 1) interval in which weighting is considered and the co4 (n) interval is multiplied by a value to be '1' at all times. The value is acquired by dividing an approximate value K of the revolution speed of the co4 (n -1) interval by actually measured revolution speed co4 (n -1) in the co4 (n - 1) interval. [0085] The approximate value K is calculated utilizing a characteristic that crank angular velocity co linearly shifts at the intake stroke. That is, the approximate value K is acquired by representing the revolution speed of the oo4 (n - 1) interval which is the interval of 315 degrees by an average of the first reluctor revolution speed cotdcl calculated in relation to the cotdcl interval (the interval of 45 degrees) and the second reluctor revolution speed catdc2 calculated in relation to the utdc2 j.nterval (the interval of 45 degrees) using revolution speed calculaterl in relation to the interval of 45 degrees. In this embodiment, the approximate value K is defined as a second average H2. [0086] A result of dividing the approximate value K (The second average H2) by the first revolution speed 0)4 (n - 1) calculated in relation to the 0)4 (n - 1) interval is naturally '1'. That is, NeA in a frame in the drawing is acquired by multiplying the first average HI by a value to be '1•. [0087] When NeA is operated, co4 included in the first average HI is divided by 0)4 in a denominator and is canceled. That is, dimensional tolerance related to the interval of 315 degrees is canceled from the inside of the frame. Hereby, in NeA, only dimensional tolerance related to the interval of 45 degrees is left; however, since the dimensional tolerance is related to the same interval of 45 degrees as o)tdc2 outside the frame, an arithmetic expression, Ao) = NeA - a)tdc2 is the subtraction of the same intervals of 45 degrees. Therefore, an effect of the dimensional tolerance is never amplified by subtraction and as a result, Aco and the load factor F respectively hardly having an effect of dimensional tolerance can be calculated [0088] The above-mentioned method of operating Aw can be also similarly applied to the steady driving mode without being limited to the transient state. In the operation of Aco and the load factor F, the first reluctor 11 (see Fig. 3) of the pulser rotor 10 is not necessarily required. [0089] As described above, according to the engine load detector according to the present invention, since revolution speed related to the interval of 315 degrees is converted to revolution speed related to the interval of 45 degrees by multiplying the revolution speed i elated to the interval of 315 degrees by a value to be '1' at all times in the arithmetic expression for calculating NeA and dimensional tolerance related to the interval of 315 degrees is canceled by the division in the conversion even if the reluctor of the pulser rotor has the dimensional tolerance in the circumferential length, an effect of the dimensional tolerance when Aco (Aco = NeA - (Dtdc2) is calculated can be prevented from being amplified. Hereby, it can be minimally inhibited that the dimensional tolerance of the reluctor has an effect on a calculated value of the load factor F of the engine. [0090] Concretely, first, when the average engine speed NeA used for calculating the load factor F (F = Aco / NeA x 100) is calculated, the detection interval for calculating NeA is set to length for two rotations of the crankshaft starting from the starting point G3 of the passage of the second reluctor 12. Next, the detection interval is divided into the four intervals including the .first reluctor interval (the otdcl interval) and the second reluctor interval (the utdc2 interval) respectively corresponding to a position in which the second reluctor 12 passes the magnetic pickup 20, and the first interval (the ©4 (n - 1) interval) and the second interval (the CD4 (n) interval) respectively corresponding to a position in which the second reluctor 12 does not pass the magnetic pickup 20 [0091] Next, Fig. 14 will be referred. Fig. 14 is a block diagram showing a procedure for calculating the average engine speed NeA. In a first average calculating unit 104, the first average HI which is the average of the first revolution speed 0)4 (n - 1) detected in a first revolution speed detecting unit 100 and the second revolution speed ©4 (n) detected in a second,revolution speed detecting unit 101 is calculated. In the meantime, in a second average calculating unit 105, the second average H2 (the approximate value K) which is the average of tlie first reluctor revolution speed cotdcl detected in a first reluctor revolution speed detecting unit 102 and the second reluctor revolution speed cotdc2 detected in a second reluctor revolution speed detecting unit 103 is calculated. In an average engine speed calculating unit 106, the average engine speed NeA is calculated using the first average HI calculated in the first average calculating unit 104, the second average H2 calculated in the second average calculating unit 105 and the first revolution speed a4 (n -1) . Hereby, the dimensional tolerance related to the interval of 315 degrees is canceled in the arithmetic expression of NeA and when Au is calculated (Aco = NeA -(:otdc2), the dimensional tolerance can be prevented from being amplified. [0092] It is clarified by experiments that the variation of crank angular velocity is apt to be influenced by the torque transmitting system from the crankshaft to the rear wheel. Accordingly, to more precisely calculate a load factor of the engine, it is desirable to consider the effect of the torque transmitting system. A method of calculating (correcting) a load factor of the engine considering that the variation of crank angular velocity is particularly influenced by the gear ratio of the transmission will be described below. [0093] Fig. 15 is a graph showing relation between engine speed Ne and a calculated value of Aco (Aw = Ne - otdc) . The graph is based upon actually measured values in a test using an engine provided with a four-speed transmission. As described above, the variation Aco of crank angular velocity increases as engine speed Ne decreases, that is, in a low torque region in which the inertia force of the crankshaft decreases. Particularly in the vicinity of the low torque region, an effect by difference in transmission gear ratio has a tendency to increase. In an example shown in the graph, as transmission gear ratio increases from a fourth speed gear (a full line) the gear ratio of which is the smallest to a first speed gear (an alternate long and two short dashes line) via a third speed gear (an alternate long and short dash line) and a second speed gear (a broken line), a calculated value of A© becomes small. This shows that even if engine speed Ne is the same and a loaded condition of the actual engine is the same, Aco has a tendency to have a small value as transmission gear ratio increases. Accordingly, when the gear ratio of the transmission is large and engine speed Ne is low, a problem that a load factor of the engine is calculated in a smaller value than an actual loaded condition occurs. [0094] Then, this embodiment has a characteristic that to reduce the effect which the difference in gear ratio has upon A©, a value of Aco is corrected according to the gear ratio of the transmission. In this embodiment, currently selected gear ratio (speed stage) is detected by the gear position sensor as the transmission gear ratio detecting unit and correction is executed by applying a correction factor according to the gear ratio to ©tdc used in calculating Aco. More concretely, correction is executed (Aa = Ne - K X cotdc) by multiplying ©tdc included in an expression for calculating Aco (Aca = Ne - cotdc) by the correction factor K. [0095] Fig. 16 is a correction factor map showing relation among engine speed Ne, current speed (a gear position) and the correction factor K. In this embodiment, when the fourth speed gear the gear ratio of which is the smallest is selected, the correction of cotdc is not made and independent of a value of engine speed Ne, the correction factor K is set to 1.0. In the meantime, it is set that as gear ratio increases from the third speed gear to the first speed gear, a value of the correction factor K also becomes large. [0096] As shown in Fig. 15, the effect which the difference in gear ratio has upon Am decreases according to the increase of engine speed Ne. Hereby, a value of the correction factor K is set to also become small according to the increase of engine speed Ne. The correction factor map is stored in the load factor calculator 50 (see Fig. 2) in ECU 30 after the map is verified by experiments and others beforehand. [0097] Fig. 17 is a flowchart showing a procedure for the correction control of Aco using the correction factor K. In a step S200, a gear position GP is detected by the gear position sensor. In the next step S201, engine speed Ne is detected. In a step S202, a correction factor K is derived from the correction factor map (see Fig. 16) using the gear position GP and the engine speed Ne. In a step S203, the derived correction factor K is applied to -the expression for calculating A© (ACD = Ne - K X cotdc) and hereby, a corrected value of ACD is calculated. According to the above-mentioned correction control of Aco, the more precise forecast of an engine load according to the gear ratio of the transmission is enabled, ignition timing control and others can be more accurately and precisely made, and fuel economy and hazardous exhaust gas can be reduced. [0098] In the above-mentioned embodiment, the speed stage of the stepped transmission is detected by the gear position sensor and the correction factor K is derived, however, for example, in the case of a continuously variable transmission depending upon a belt converter, transmission gear ratio is detected based upon an amount of the movement of a pulley driven to vary gear ratio and the correction factor K may be also derived according to the gear ratio. [0099] Transmission gear ratio is calculated based upon vehicle speed and engine speed and the correction factor K may be also derived according to the gear ratio. According to this method, the position sensor for detecting the speed stage is not required and the reduction of the cost can be expected. [0100] The configuration of the engine and the pulser rotor, the dimension and the number of the reluctors, the positions of the reluctors on the pulser rotor, the positions of the reluctors in the position of TDC, the value of the weighting factor a and the setting of the detection interval for detecting the average engine speed NeA are not limited to the above-mentioned embodiment, and various changes are allowed. The reluctor tolerance canceling method applied to the engine load detector according to the present invention can be applied to an engine for a vehicle such as a motorcycle and various general purpose engines. [Reference Signs List] [0101] I Engine, 6 Ignition device, 7 Piston, 8 Cylinder, 9 Crankshaft, 10 Pulser rotor, II First reluctor, 12 Second reluctor, 20 Magnetic picl 30 ECU, 40 Crank pulse detector, 50 Load factor calculator, 51 Timer, 52 Ne calculating unit. 53 Aco calculating unit, 54 (otdc calculating unit, 56 Load factor calculating unit, 60 Control correction quantity calculator, 70 Ignition controller, 100 First revolution speed detecting unit, 101 Second revolution speed detecting unit, 102 First reluctor revolution speed detecting unit, 103 Second reluctor revolution speed detecting unit, 104 First average calculating unit, 105 Second average calculating unit, 106 Average engine speed calculating unit, F Load factor, Gl Starting point of first reluctor, G2 End point of first reluctor, G3 Starting point of second reluctor, G4 End point of second reluctor, HI First average, H2 Second average (Approximate value K), a Weighting factor, CO Crank angular velocity, cotdc Crank angular velocity when reluctor passes, Nel Interval engine speed of Nel interval, Ne2 Interval engine speed of Ne2 interval, NeA Average engine speed in predetermined interval, Aco Variation of angular velocity, co4 (n - 1) First revolution speed, (D4 (n) Second revolution speed. ©tdcl First reluctor revolution speed, cotdc2 Second reluctor revolution speed, NeA Average engine speed in detection interval, [Document Name] Scope of Claims [Claim 1] An engine load detector which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, the engine load detector comprising: a unit that calculates an interval engine speed per interval acquired by dividing a predetermined interval for detecting an average engine speed into plural intervals based upon each output signal from the pickup; a weighting unit that applies different weighting processing to the plural interval engine speeds; and a loaded condition calculating unit that calculates the average engine speed based upon an average of the plural weighted interval engine speeds and operates a loaded condition of the engine using the average engine speed. [Claim 2] The engine load detector according to Claim 1, wherein, in the weighting processing, a weighting ratio of the interval including a combustion and expansion stroke out of the plural divided intervals is set to be larger than another interval, [Claim 3] The engine load detector according to Claim 1 or 2, wherein the predetermined interval is detected based upon an output signal from the pulser rotor. [Claim 4] The engine load detector according to any of Claims 1 to 3, wherein the predetermined interval is set as follows: a length for two rotations of the crankshaft is divided into two, i.e. a first interval and a second interval; the first interval includes an intake stroke; and the second interval includes a combustion and expansion stroke. [Claim 5] The engine load detector according to any of Claims 1 to 4, wherein a loaded condition of the engine is a load factor calculated by dividing a revolution speed while the reluctor passes the pickup by the average engine speed. [Claim 6] The engine load detector according to Claim 5, wherein: the reluctor is arranged in a position immediately before the top dead center of the engine; and the load factor is calculated using a revolution speed while the reluctor passes the pickup immediately before the top dead center on a compressive side. [Claim 7] The engine load detector according to Claim 5 or 6, wherein feedback control over at least the ignition timing of the engine is made according to the calculated load factor. [Claim 8] An engine load detecting method of a device which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, the engine load detecting method comprising: a procedure for dividing a predetermined interval for detecting an average engine speed into plural intervals; a procedure for calculating an interval engine speed per divided interval; a procedure for applying different weighting processing to the plural interval engine speeds; a procedure for calculating the average engine speed by calculating an average of the plural weighted interval engine speeds; and a procedure for operating a loaded condition of the engine using the average engine speed. [Claim 9] An engine load detector which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, wherein: a detection interval for detecting an average engine speed is set to a length for two rotations of the crankshaft starting from a starting point of the passage of the reluctor; the detection interval is divided into four intervals including a first reluctor interval and a second reluctor interval respectively corresponding to a position in which the reluctor passes the pickup per rotation out of the two rotations of the crankshaft, and a first interval and a second interval respectively corresponding to a position in which the reluctor does not pass the pickup; and the engine load detector comprises: a unit that calculates a first average which is an average of a first revolution speed detected in the first interval and a second revolution speed detected in the second interval; a unit that calculates a second average which is an average of a first reluctor revolution speed detected in the first reluctor interval and a second reluctor revolution speed detected in the second reluctor interval; a unit that calculates the average engine speed by multiplying a value acquired by dividing the first average by the first revolution speed by the second average; and a loaded condition calculating unit that calculates a loaded condition of the engine using the average engine speed. [Claim 10] The engine load detector according to Claim 9, wherein the unit that calculates the average engine speed calculates the average engine speed NeA by the following expression: [Mathematical expression 1] where the first revolution speed is u4 (n - 1), the second revolution speed is u4 (n), the first reluctor revolution speed is cotdcl, the second reluctor revolution speed is a)tdc2 and a weighting factor is a. [Claim 11] The engine load detector according to Claim 10, wherein: the first interval includes an intake stroke and the second interval includes a combustion and expansion stroke; and the weighting factor a for applying different weighting processing between the first revolution speed and the second revolution speed when the first average is calculated is set to 0,5 or larger. [Claim 12] The engine load detector according to any of Claims 9 to 11, wherein: the reluctor is arranged in a position immediately before a top dead center of the engine; and a loaded condition of the engine is a load factor calculated by dividing the second reluctor revolution speed by the average engine speed. [Claim 13] The engine load detector according to Claim 12, wherein feedback control over at least an ignition timing of the engine is made according to the load factor. [Claim 14] An engine load detecting method of an engine load detector which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, the engine load detecting method comprising: a procedure for setting a detection interval for detecting an average engine speed to a length for two rotations of the crankshaft starting from a starting point of the passage of the reluctor; a procedure for dividing the detection interval into four intervals including a first reluctor interval and a second reluctor interval respectively corresponding to a position in which the reluctor passes the pickup per rotation out of the two rotations of the crankshaft, and a first interval and a second interval respectively corresponding to a position in which the reluctor does not pass the pickup; a procedure for calculating a first average which is an average of a first revolution speed detected in the first interval and a second revolution speed detected in the second interval; a procedure for calculating a second average which is an average of a first reluctor revolution speed detected in the first reluctor interval and a second reluctor revolution speed detected in the second reluctor interval; and a procedure for calculating the average engine speed by multiplying a value acquired by dividing the first average by the first revolution speed by the second average [Claim 15] An engine load detector which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, the engine load detector comprising: transmission gear ratio detecting unit that detects the gear ratio of a transmission, wherein: the loaded condition of the engine is represented as a load factor calculated by dividing revolution speed while the reluctor passes the pickup by average engine speed; and the revolution speed while the reluctor passes the pickup is corrected based upon the gear ratio. [Claim 16] The engine load detector according to Claim 15, wherein the transmission gear ratio detecting unit is a gear position sensor that detects the speed stage of a stepped transmission. [Claim 17] The engine load detector according to Claim 16, wherein: the correction of revolution speed while the reluctor passes the pickup is executed by multiplying the revolution speed by a correction factor; and the correction factor is set to be larger as the number of gear stages of the stepped transmission decreases. [Claim 18] The engine load detector according to Claim 15, wherein: the transmission gear ratio detecting unit calculates transmission gear ratio based upon vehicle speed and engine speed.

Full Text

[Document Name] Specification
[Title of the Invention] ENGINE LOAD DETECTOR AND ENGINE
LOAD DETECTING METHOD
[Technical Field]
[0001]
The present invention relates to an engine load detector and an engine load detecting method, particularly relates to an engine load detector that detects a loaded condition of an engine based upon an output signal from a pulser rotor rotated in synchronization with a crankshaft and an engine load detecting method. [Background Art] [0002]
Heretofore, an engine load detector which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine and a pickup coil that detects a state in which a reluctor provided to the pulser rotor passes and which detects a loaded condition of the engine based upon a pulse signal output from the pickup coil is known. [0003]
In a patent document 1, technique for providing a reluctor of a pulser rotor in the vicinity of a position corresponding to a top dead center of an engine, calculating the ratio of time in which the pulser rotor is rotated once and time in which the reluctor passes per one turn or per two turns and detecting a loaded condition of

the engine based upon a degree of the variation of the
ratio is disclosed.
[CitationList]
[Patent Literature]
[0004]
[Patent Literature 1] JP-A No. 2002-115598
[Summary of Invention]
[Technical Problem]
[0005]
However, the technique disclosed in the patent literature 1 is technique for detecting the passing time of the reluctor with time in which the crankshaft is rotated once as a reference and it has not been considered to detect a more suitable loaded condition by setting a longer interval, for example, time in which the crankshaft is rotated twice as the reference. Further it has not been examined that the engine speed varies according to four strokes (an intake stroke, a compression stroke, a combustion and expansion stroke and an exhaust stroke) of a four-cycle engine while the crankshaft is rotated once. [0006]
When the length in a circumferential direction of the reluctor has a dimensional error by dimensional tolerance, an effect of the dimensional tolerance is also left in calculated ratio as it is and a loaded condition of the engine may be unable to be precisely detected because the technique disclosed in the patent literature 1 is technique for detecting the passing time of the reluctor with time in

which the crankshaft is rotated once as the reference. It is known that the rotational speed (the angular velocity) of the crankshaft is apt to be influenced by a torque transmitting system from the crankshaft to a rear wheel and accordingly, configuration that enables calculating a load also in consideration of such a situation is desired. [0007]
An object of the present invention is to address the problem of the related art and to provide a load detector that reduces an effect of dimensional tolerance of a pulser rotor in consideration of the variation of revolution generated according to four strokes of a four-cycle engine and can more precisely detect a loaded condition of the engine and a load detecting method. [Solution to Problem] [0008]
To achieve the object, the present invention is based upon an engine load detector which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, and has a first characteristic that a unit that calculates an interval engine speed per interval acquired by dividing a predetermined interval for detecting an average engine speed into plural intervals based upon each

output signal from the pickup, a weighting unit that applies different weighting processing to the plural interval engine speeds and a loaded condition calculating unit that calculates average engine speed based upon an average of the plural weighted interval engine speeds and operates a loaded condition of the engine using the average engine speed. [0009]
The present invention has a second characteristic that in the weighting processing, a weighting ratio for the interval including a combustion and expansion stroke out of the plural divided intervals is set to be larger than another interval. [0010]
The present invention has a third characteristic that the predetermined interval is detected based upon the output signal from the pulser rotor. [0011]
The present invention has a fourth characteristic that the predetermined interval is set so that a length for two rotations of the crankshaft is divided into two, i.e. a first interval and a second interval, the first interval includes an intake stroke, and the second interval includes a combustion and expansion stroke. [0012]
The present invention has a fifth characteristic that a loaded condition of the engine is a load factor

calculated by dividing a revolution speed while the reluctor passes the pickup by the average engine speed. [0013]
The present invention has a sixth characteristic that the reluctor is arranged in a position immediately before the top dead center of the engine and the load factor is calculated using a revolution speed while the reluctor passes the pickup immediately before a top dead center on a compressive side. [0014]
The present invention has a seventh characteristic that feedback control over at least an ignition timing of the engine is made according to the calculated load factor. [0015]
The present invention is based upon an engine load detecting method of a device which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, and has an eighth characteristic that the engine load detecting method includes a procedure for dividing a predetermined interval for detecting an average engine speed into plural intervals when the average engine speed used to detect the loaded condition of the engine is calculated, a procedure for calculating an interval engine

speed per divided interval, a procedure for applying different weighting processing to the plural interval engine speeds and a procedure for calculating the average engine speed by calculating an average of the plural weighted interval engine speeds. [0016]
The present invention is based upon an engine load detector which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, and has a ninth characteristic that a detection interval for detecting an average engine speed is set to a length for two rotations of the crankshaft starting from a starting point of the passage of the reluctor, the detection interval is divided into four intervals including a first reluctor interval and a second reluctor interval respectively corresponding to a position in which the reluctor passes the pickup per rotation out of the two rotations of the crankshaft, and a first interval and a second interval respectively corresponding to a position in which the reluctor does not pass the pickup and the engine load detector is provided with a unit that calculates a first average which is an average of a first revolution speed detected in the first interval and a second

revolution speed detected in the second interval, a unit that calculates a second average which is an average of a first reluctor revolution speed detected in the first reluctor interval and a second reluctor revolution speed detected in the second reluctor interval, a unit that calculates the average engine speed by multiplying a value acquired by dividing the first average by the first revolution speed by the second average and a loaded condition calculating unit that calculates a loaded condition of the engine using the average engine speed. [0017]
The present invention has a tenth characteristic that the unit that calculates the average engine speed calculates the average engine speed NeA by the following expression: [0018] [Mathematical expression 1]

where the first revolution speed is 0)4 (n - 1), the second revolution speed is u4 (n) , the first reluctor revolution speed is cotdcl, the second reluctor revolution speed is cotdc2 and the weighting factor in the weighting processing is a. [0019]
The present invention has an eleventh characteristic that the first interval includes an intake stroke, the second interval includes a combustion and expansion stroke

and the weighting factor a used in different weighting processing between the first revolution speed and the second revolution speed when the first average is calculated is set to 0.5 or larger. [0020]
The present invention has a twelfth characteristic that the reluctor is arranged in a position immediately before a top dead center of the engine and a loaded condition of the engine is a load factor calculated by dividing the second reluctor revolution speed by the average engine speed. [0021]
The present invention has a thirteenth characteristic that feedback control over at least an ignition timing of the engine is made according to the load factor. [0022]
Further, the present invention is based upon an engine load detecting method of an engine load detector which is provided with a pulsar rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, and has a fourteenth characteristic that the engine load detecting method includes a procedure for setting a detection interval for detecting an average engine speed to a length

for two rotations of the crankshaft starting from a starting point of the passage of the reluctor, a procedure for dividing the detection interval into four intervals including a first reluctor interval and a second reluctor interval respectively corresponding to a position in which the reluctor passes the pickup,per rotation out of the two rotations of the crankshaft, and a first interval and a second interval respectively corresponding to a position in which the reluctor does not pass the pickup, a procedure for calculating a first average which is an average of a first revolution speed detected in the first interval and a second revolution speed detected in the second interval, a procedure for calculating a second average which is an average of a first reluctor revolution speed detected in the first reluctor interval and a second reluctor revolution speed detected in the second reluctor interval and a procedure for calculating the average engine speed by multiplying a value acquired by dividing the first average by the first revolution speed by the second average. [0023]
The present invention is based upon an engine load detector which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, and has a

fifteenth characteristic that a transmission gear ratio detecting unit that detects the gear ratio of a transmission is provided, a loaded condition of the engine can be grasped with a load factor calculated by dividing the rotational speed while the reluctor passes the pickup by average engine speed and the rotational speed while the reluctor passes the pickup is corrected based upon the transmission gear ratio. [0024]
The present invention has a sixteenth characteristic that the transmission gear ratio detecting unit is a gear position sensor that detects the speed stage of a stepped transmission. [0025]
The present invention has a seventeenth characteristic that the correction of rotational speed while the reluctor passes the pickup is executed by multiplying the rotational speed by a correction factor and the correction factor is set so that the smaller the number of gear stages of the stepped transmission is, the larger the correction factor is. [0026]
Further, the present invention has an eighteenth characteristic that the transmission gear ratio detecting unit calculates transmission gear ratio based upon vehicle speed and engine speed. [Advantageous Effects of Invention] [0027]

According to the first characteristic, since the predetermined interval for detecting the engine speed is divided into plural intervals when the average engine speed used for operating the loaded condition of the engine is calculated, an interval engine speed per divided interval is calculated, different weighting processing is applied to the plural interval engine speeds and further, the average engine speed is calculated by calculating the average of the plural weighted interval engine speeds, suitable average engine speed can be calculated by weighting in consideration of the variation of the rotation even if the rotation greatly varies in the predetermined interval differently from that in a steady driving mode. Hereby, even if engine speed greatly varies in the predetermined interval in acceleration and in running on an irregular road, an engine loaded condition corresponding to this situation can be acquired by operation. [0028]
According to the second characteristic, since the ratio of the weighting of the interval including the combustion and expansion stroke out of the plural divided intervals is set to be larger than another interval in the weighting processing, a load of the engine corresponding to this can also be acquired by operation in acceleration and in running on an irregular road, particularly when a degree of the rise of engine speed increases at the combustion and expansion stroke. [0029]

According to the third characteristic, as the predetermined interval is detected based upon an output signal from the pulser rotor, the predetermined interval for detecting the average engine speed can be set using the pulser rotor that detects timing for driving an igniter and a fuel injection system of the engine. Hereby, the engine loaded condition can be acquired by operation without providing a new sensor and the like. [0030]
According to the fourth characteristic, since the predetermined interval is set so that the length for two rotations of the crankshaft is divided into two, i.e. the first interval and the second interval, the first interval includes the intake stroke and the second interval includes the combustion and expansion stroke, the predetermined interval can be divided by a simple method. As the weight of the second interval including the combustion and expansion stroke is set to be large, a loaded condition in consideration of the variation of engine speed at the combustion and expansion stroke can be acquired by operation. As the predetermined interval is divided in a minimum number, the effect of weighting processing can be acquired while inhibiting the increase of a load on operation. [0031]
According to the fifth characteristic, as the loaded condition of the engine is the load factor calculated by dividing a revolution speed while the reluctor passes the

pickup by the average engine speed, the loaded condition of the engine can be acquired by a simple arithmetic expression. [0032]
According to the sixth characteristic, since the reluctor is arranged in the position immediately before the top dead center of the engine and the load factor is calculated using a revolution speed while the reluctor passes the pickup immediately before the top dead center on the compressive side, the large variation of engine speed from the end of the compression stroke to the combustion and expansion stroke is suitably detected and the load factor of the engine in consideration of the variation of engine speed can be acquired. [0033]
According to the seventh characteristic, since the feedback control over at least the ignition timing of the engine is made according to the calculated load factor, correction control over at least the ignition timing is enabled using only the output signal from the pulser rotor without providing a new sensor and the like. [0034]
According to the eighth characteristic, since the engine load detecting method includes the procedure for dividing the predetermined interval for detecting the average engine speed into the plural intervals, the procedure for calculating interval engine speed per divided interval, the procedure for applying different weighting
if

processing to the plural interval engine speeds, the procedure for calculating average engine speed by calculating the average of the plural weighted interval engine speeds and the procedure for operating the engine loaded condition using the average engine speed, suitable average engine speed is calculated by executing weighting in consideration of the variation of engine speed even if large variation different from variation in the steady driving mode occurs in engine speed in the predetermined interval, and the engine loaded condition can be operated based upon the suitable average engine speed. [0035]
According to the ninth characteristic, since the detection interval for detecting the average engine speed is set to the length for two rotations of the crankshaft starting from the starting point of the passage of the reluctor, the detection interval is divided into the four intervals including the first reluctor interval and the second reluctor interval respectively corresponding to the position in which the reluctor passes the pickup per rotation out of the two rotations of the crankshaft, and the first interval and the second interval respectively corresponding to the position in which the reluctor does not pass the pickup and the engine load detector is provided with the unit that calculates the first average which is the average of the first revolution speed detected in the first interval and the second revolution speed detected in the second interval, the unit that calculates

the second average which is the average of the first reluctor revolution speed detected in the first reluctor interval and the second reluctor revolution speed detected in the second reluctor interval, the unit that calculates an average engine speed by multiplying the value acquired by dividing the first average by the first revolution speed by the second average and the loaded condition calculating unit that calculates the loaded condition of the engine using the average engine speed, the relation of dividing the revolution speed of the reluctor part by the revolution speed of the same reluctor part can be included in an arithmetic expression for calculating the average engine speed. Hereby, even if the length in the circumferential direction of the reluctor has dimensional tolerance, the effect of the dimensional tolerance in the arithmetic expression can be reduced and more suitable average engine speed can be calculated. The detection interval for detecting average engine speed can be set using the pulser rotor for detecting timing for driving the igniter and the fuel injection system of the engine. [0036]
According to the tenth characteristic, the effect which the dimensional tolerance of the reluctor has the calculated value of the average engine speed can be reduced in the arithmetic expression of the average engine speed. [0037]
According to the eleventh characteristic, since the first interval includes the intake stroke, the second

interval includes the combustion and expansion stroke and the weighting factor a for executing different weighting processing between the first revolution speed and the second revolution speed when the first average is calculated is set to 0.5 or larger, the average engine speed in consideration of the degree of the rise of engine speed at the combustion and expansion stroke can be calculated even if the large variation different from variation in the steady driving mode occurs in engine speed in the detection interval. Hereby, even if the variation of engine speed increases in acceleration and according to a situation of a road, the more suitable load on the engine can be calculated. [0038]
According to the twelfth characteristic, since the reluctor is arranged in the position immediately before the top dead center of the engine and the loaded condition of the engine is the load factor calculated by dividing the second reluctor revolution speed by the average engine speed, a load on the engine can be detected by a simple arithmetic expression. Besides, the variation of engine speed from the latter half of the compression stroke to the combustion and expansion stroke is suitably detected and the load factor of the engine can be acquired. [0039]
According to the thirteenth characteristic, since the feedback control over at least the ignition timing of the engine is made according to the load factor, the load

factor of the engine is calculated using only the output signal from the pulser rotor and the correction control over at least the ignition timing of the engine can be made based upon the load factor. Hereby, the suitable ignition timing control can be executed without providing a sensor that detects the loaded condition of the engine and the 11 ke. [0040]
According to the fourteenth characteristic, since the engine load detecting method includes the procedure for setting the detection interval for detecting the average engine speed to the length for two rotations of the crankshaft starting from the starting point of the passage of the reluctor, the procedure for dividing the detection interval to the four intervals including the first reluctor interval and the second reluctor interval respectively corresponding to the position in which the reluctor passes the pickup per rotation out of the two rotations of the crankshaft, and the first interval and the second interval respectively corresponding to the position in which the reluctor does not pass the pickup, the procedure for calculating the first average which is the average of the first revolution speed detected in the first interval and the second revolution speed detected in the second interval, the procedure for calculating the second average value which is the average of the first reluctor revolution speed detected in the first reluctor interval and the second reluctor revolution speed detected in the second reluctor

interval and the procedure for calculating an average engine speed by multiplying the value acquired by dividing the first average by the first revolution speed by the second average, the effect of the dimensional tolerance of the reluctor can be reduced in an arithmetic expression even if the length in the circumferential direction of the reluctor has the dimensional tolerance and a more precise average engine speed can be calculated. Hereby, the suitable load on the engine can be calculated. [0041]
According to the fifteenth characteristic, as the transmission gear ratio detecting unit that detects the gear ratio of the transmission is provided, the loaded condition of the engine can be grasped with a load factor calculated by dividing the rotational speed while the reluctor passes the pickup by average engine speed and the rotational speed while the reluctor passes the pickup is corrected based upon transmission gear ratio, the loaded condition of the engine can be calculated also in consideration of the effect of the torque transmitting system from the crankshaft to the rear wheel. Concretely, a phenomenon that the larger the gear ratio of the transmission is, the smaller the rotational speed while the reluctor passes the pickup is can be coped with and hereby, the loaded condition of the engine can be more precisely calculated. [0042]

According to the sixteenth characteristic, as the transmission gear ratio detecting unit is the gear position sensor that detects the speed stage of the stepped transmission, the gear ratio of the stepped transmission is detected with simple configuration and the rotational speed while the reluctor passes the pickup can be corrected. [0043]
According to the seventeenth characteristic, as the correction of the rotational speed while the reluctor passes the pickup is executed by multiplying the rotational speed by a correction factor and the correction factor is set so that the smaller the number of gear stages of the stepped transmission is, the larger the correction factor is, there can be made suitable correction in accordance with a tendency that the following increase of the transmission gear ratio is apt to have an effect upon the torque transmitting system from the crankshaft to the rear wheel increases as the gear ratio of the transmission increases, in other words, a tendency that the rotational speed while the reluctor passes the pickup decreases as the gear ratio increases even if an actual loaded condition of the engine is the same. [0044]
According to the eighteenth characteristic, as the transmission gear ratio detecting unit calculates the transmission gear ratio based upon vehicle speed and engine speed, a position sensor for detecting the speed stage of

the gear is not reguired and the reduction of the cost can be expected.
[Brief Description of Drawings] [0045]
[Fig. 1] Fig. 1 is a block diagram showing an engine to which an engine load detector equivalent to one embodiment of the present invention is applied.
[Fig. 2] Fig. 2 is a block diagram showing the details of a load factor calculating unit provided to the ECU. [Fig. 3] Fig. 3 is an enlarged front view showing a pulser rotor. [Figs. 4] Figs. 4 are graphs showing relation among a crank
pulse signal, engine speed Ne and angular velocity CD . [Fig. 5] Fig. 5 is a graph showing relation between a crank pulse signal for one cycle and angular velocity co. [Fig. 6] Fig. 6 is an enlarged view showing a part of Fig. 5.
[Figs. 7] Figs. 7 are graphs showing the variation of angular velocity oa in a steady driving mode and in a transient condition. [Fig. 8] Fig. 8 is a graph showing relation between angular
velocity co in the transient state and a detection interval. [Fig. 9] Fig. 9 shows a concept of weighting processing. [Fig. 10] Fig. 10 is a graph showing a method of deriving a weighting factor a.
[Fig. 11] Fig. 11 is an explanatory drawing showing relation between a detection interval when a method of

canceling reluctor tolerance is applied and an Nel interval
and an Ne2 interval.
[Fig. 12] Fig. 12 is a graph showing relation between
angular velocity co in the transient state and the detection
interval.
[Fig. 13] Fig. 13 is an explanatory drawing showing an
arithmetic expression for calculating Aco.
[Fig. 14] Fig. 14 is a block diagram showing a procedure
for calculating average engine speed NeA.
[Fig. 16] Fig. 15 is a graph showing relation between
engine speed Ne and a calculated value of Aco (Aco = Ne -
ffitdc).
[Fig. 16] Fig. 16 is a correction factor map showing
relation among engine speed Ne, speeds of the gear and a
correction factor K.
[Fig. 17] Fig. 17 is a flowchart showing a procedure for
correction control over Aco using the correction factor K.
[Description of Embodiments]
[0046]
Referring to the drawings, a preferred embodiment of the present invention will be described in detail below. Fig, 1 is a block diagram showing the configuration of an engine 1 to which an engine load detector equivalent to one embodiment of the present invention is applied. The engine 1 is a 4-cycle single-cylinder internal combustion engine and has configuration that a piston 7 reciprocated inside a cylinder 8 is coupled to a crankshaft 9 via a connecting rod. An intake pipe 2 and an exhaust pipe 4, an intake

valve 3 and an exhaust valve 5 respectively opened or closed in synchronization with the rotation of the crankshaft 9 are provided in an upper part of the cylinder 8. An ignition plug 6 as an ignition device is attached at an upper end of the cylinder 8. [0047]
A pulser rotor 10 rotated in synchronization with the crankshaft 9 is attached to the crankshaft 9. A reluctor protruded outside in a radial direction by predetermined quantity is provided on a periphery of the pulser rotor 10. In the vicinity of the pulser rotor 10, a magnetic pickup 20 fixed to a crankcase and others of the engine 1 is arranged, reacts to the passage of the reluctor according to the rotation of the pulser rotor 10, and outputs a crank pulse signal. [0048]
An ECU 30 as an engine control unit includes a crank pulse detector 40 that detects a pulse signal from the magnetic pickup 20, a load factor calculator 50 as loaded condition detecting unit of the engine 1, a control correction quantity calculator 60 that calculates the correction quantity of ignition timing according to a loaded condition of the engine, an ignition controller 70 that controls the ignition of the ignition plug 6 and an ignition map 80 for determining ignition timing at least based upon the information of a throttle angle and engine speed Ne. The ECU 30 in this embodiment obtains a loaded condition (a load factor F) of the engine 1 based upon a

pulse signal input to the crank pulse detector 40 and can control so that the ignition timing of the ignition plug 6 is corrected according to the loaded condition. [0049]
In this case, the load factor F of the engine 1 denotes the magnitude of a load represented in a numeric value to use the magnitude of the load for correction control because a condition of a load applied to the engine 1 is different in a case that a vehicle is driven on a flat road at fixed speed and in a case that the vehicle is accelerated on an ascending slope even if the engine speed is the same. The ignition controller 70 can acquire suitable ignition timing according to a loaded condition such as corrects ignition timing to be slightly lagged and prevents knocking when the load factor F is large, that is, a load applied to the engine is large. The details of a method of operating the load factor F will be described later. [0050]
In this embodiment, only the correction control of ignition timing is executed using the load factor F, however, the ECU 30 may also control, a fuel injection system (not shown) that supplies fuel to the engine 1 and may also execute fuel injection control according to the load factor F, [0051]
Fig. 2 is a block diagram showing the details of the load factor calculator 50 provided to the ECU 30. The load

factor caiculator 50 calculates the load fact of F of the engine 1 based upon a crank pulse signal input from the crank pulse detector 40 and time measured by a timer 51. The load factor calculator 50 includes an Ne calculating
unit 52, a Aco calculating unit 53, an cotdc calculating unit 54, a reluctor electrical angle determining unit 55 and a load factor calculating unit 56 in addition to the timer 51 [0052]
The Ne calculating unit 52 calculates engine speed Ne (average engine speed NeA) at a detection interval. The reluctor electrical angle determining unit 55 detects an angle in a circumferential direction electrically detected of the reluctor based upon a pulse signal when the reluctor
passes the magnetic pickup 20. The ©tdc calculating unit 54 calculates the revolution speed (the angular velocity) of the pulsar rotor 10 while the reluctor passes the
magnetic pickup 20, that is, the angular velocity cotdc (rad/s) of only the reluctor part. [0053]
The Aco calculating unit 53 calculates the variation A(o of crank angular velocity by subtracting the angular velocity cotdc of the reluctor part calculated by the cotdc calculating unit from engine speed Ne calculated by the Ne
calculating unit 52 (Aco = Ne - cotdc) . The subtraction by the Aco calculating unit 53 is executed by converting engine speed Ne (rpm) to engine revolution speed (rad/s). The load factor calculating unit 56 calculates the engine load factor F according to an arithmetic expression, Aco / Ne >«

100 (%) using the variation Ao of the angular velocity calculated by the A© calculating unit 53 and the engine speed Ne calculated by the Ne calculating unit 52. The larger a load of the engine is, the larger numeric value the load factor F is. [0054]
Fig. 3 is an enlarged front view showing the pulser rotor 10. A first reluctor 11 and a second reluctor 12 are provided to the pulser rotor 10 in this embodiment. In Fig 3, the pulser rotor 10 is rotated counterclockwise and a crank pulse signal from the magnetic pickup 20 is sequerit ially output at a starting point GI of the first reluctor 11, at an end point G2 of the first reluctor 11, at a starting point G3 of the second reluctor 12 and at an end point G4 of the second reluctor 12. [0055]
The second reluctor 12 has length in the circumferential direction for a first angle 91 from a position apart by a fourth angle 94 from a top dead center (TDC) of the engine. The first reluctor 11 has length in the circumferential direction for a third angle 93 and a second angle 62 is angle between the starting point Gl of the first reluctor 11 and the starting point G3 of the second reluctor 12. In this embodiment, the first angle 91 is set to 45 degrees, the second angle 92 is set to 22.5 degrees, the third angle 93 is set to 11.25 degrees, and the fourth angle 94 is set to 15 degrees. In Fig. 3, the pulser rotor 10 and the magnetic pickup 20 are shown in an

apart condition; however, an interval between the periphery of each reluctor 11, 12 and the magnetic pickup 20 is set to 0.5 mm for example. [0056]
Fig. 4 is graphs showing relation among a crank pulse signal output from the magnetic pickup 20, average engine speed NeA per rotation of the crankshaft and the angular velocity © of the crankshaft. An interval between A and B in Fig. 4 shows a time interval for one rotation of the crankshaft including an intake stroke. The graph (a) shows a steady driving mode in which a vehicle is driven on a flat road at fixed engine speed Ne and the graph (b) shows a transient state while engine speed Ne rises in acceleration and by the operation of a throttle. The graph
(c) shows only the variation of angular velocity co in
driving on a wavy (irregular) road.
[0057]
These graphs tell that though engine speed is fixed
or increased, crank angular velocity co repeats periodical variation according to one cycle of the engine. The observation for a long term of the variation of angular
velocity co on a wavy road tells that a gentle wavy motion is generated as a whole because force for
accelerating/decelerating a driving wheel or driving wheels acts because of an irregular road. However, it remains unchanged that periodical variation according to one cycle of the engine is also repeated on the wavy road in units of one rotation of the crankshaft. It can be verified that on

any driving condition, angular velocity © linearly varies in the interval including the intake stroke between A and B A linear locus of angular velocity to in the interval between A and B greatly falls rightward in the steady driving mode shown in (a) and an angle of the rightward fall greatly decreases in the transient state shown in (b). [0058]
Fig. 5 is a graph showing relation in one cycle
between a crank pulse signal and angular velocity co. The same reference numeral as the above-mentioned one denotes the same or the similar part. As described above, angular
velocity co periodically varies according to each stroke of four cycles. A decrease in an interval Dl from a latter half of a compression stroke to a combustion and expansion stroke is caused by resistance to compression due to a rise of pressure inside the cylinder. An increase in an interval D2 at the combustion and expansion stroke is caused by the generation of crank rotating energy due to a rise of pressure inside the cylinder by combustion. [0059]
A decrease in an interval D3 until an intake stroke is finished after the interval D2 is finished is caused by the generation of the mechanical frictional resistance of the engine 1 and the generation of resistance to the exhaust of combustion gas after combustion is finished and
crank angular velocity co reaches its peak. An interval D4 shows a time interval for one rotation of the crank with

the starting point G3 of the second reluctor 12 as a starting point: . [00060]
In Fig. 5, when engine speed (revolution speed) Ne is the same, crank angular velocity a in the steady driving mode is shown by a full line and crank angular velocity © when a large load is applied is shown by a broken line. As shown in Fig. 5, when a large load is applied, the
variation of angular velocity co becomes large. This reason is that even if engine speed Ne is the same, a peak of
angular velocity co becomes larger as output torque increases and the more the quantity of taken air is, the larger the quantity of a fall after that is. [0061]
The variation of crank angular velocity co becomes larger in an area of less rotation in which the inertia force of the crankshaft decreases and in an engine having cylinders of a small number and having a large interval of explosion such as the single-cylinder engine 1 in this embodiment, the variation has a tendency toward being further larger. [0062]
Fig. 6 is an enlarged view showing a part of Fig. 5. As described above, a loaded condition of the engine 1 is detected by the load factor F of the engine. The load factor F denotes a numeric value showing a degree of the
decrease of angular velocity o) for engine speed Ne in the interval Dl including a compression top dead center, in

other words, the magnitude of resistance to compression at the compression stroke. In this embodiment, the second reluctor 12 is located in the interval Dl and a
differential value between angular velocity totdc when the second reluctor 12 passes the magnetic pickup 20 and engine
speed Ne is calculated as the variation A© of angular velocity CD . An cotdc interval in Fig. 6 corresponds to the time of transit from the starting point G3 of the second reluctor 12 to the end point G4. [0063]
Referring to Figs. 7, 8 and 9, weightinq processing for precisely detecting the load factor F in the transient state will be described below. The weighting processing means a method of dividing a detection interval into plural pieces when engine speed Ne in the detection interval is calculated, calculating interval engine speed per divided interval, an increasing the weight of a certain specific divided interval when plural interval engine speeds are averaged and adjusting NeA to a proper value. [0064]
Fig. 7 is graphs showing the variation of angular
velocity co in the steady driving mode and in the transient state. "T" in Fig. 7 denotes a top dead center (TDC).
Angular velocity co in the steady driving mode shown in (a) varies between the same upper limit and the same lower limit in each cycle. Therefore, it can be said that the detection interval for calculating engine speed Ne used for calculating Aco is sufficient if only the detection interval

is set to an interval for one cycle. In an example shown in Fig, 1, an interval while the crankshaft is rotated twice from the starting point Gl of the first reluctor 11, that is, for one cycle is also set to the detection interval. [0065]
However, though angular velocity co in the transient state shown in (b) substantially similarly varies per cycle (has the substantially same waveform), compared with that in the steady driving mode shown in (a) , the angular velocity o continuously rises toward the next peak after it slightly falls after it reaches a peak. Hereby, a waveform of the angular velocity (D in the transient state is in a stepped shape rising rightward. At this time, when the operation of the engine load factor F is executed for both in a case that engine speed is the same in the steady driving mode and in the transient state for example, the load factor F in the transient state is calculated to be smaller than that in the steady driving mode and a phenomenon that the load factor does not correspond to a loaded condition actually caused in the engine occurs. Though l:he details are described later, this reason is that
the variation Au in the transient state is calculated to be smallish, compared with the actual engine loaded condition. [0066]
To cope with this, in this embodiment, for a prerequisite, the detection interval is divided into an Nel interval until the crankshaft is rotated once from the

starting point Gl of the first reluctor 11 and an Ne2 interval until the crankshaft is rotated once more from an end point of the Nel interval, and average engine speed Ne (hereinafter called NeA) of the whole detection interval is calculated by averaging interval engine speed Nel (hereinafter called Nel) of the Nel interval and interval engine speed Ne2 (hereinafter called Ne2) of the Ne2 interval. This calculation process is executed by the Ne calculating unit 52. [0067]
Fig. 8 is a graph showing relation between angular velocity co in the transient state and the detection interval. The same reference numeral as the above-mentioned one denotes the same or the similar part. As described above, in the transient state, the decrement of
angular velocity co in an interval from the intake stroke to a former half of the compression stroke, that is, in the Nel interval decreases and in an example shown in Fig. 8, the angular velocity proceeds substantially horizontally. In the meantime, in the latter half of the compression
stroke, after the angular velocity co greatly decreases, it greatly increases in the combustion and expansion stroke and reaches a peak. [0068]
In this case, as described above, the engine load factor F is calculated based upon how the crank angular velocity co in the latter half of the compression stroke decreases for engine speed Ne. In this calculating method,

however, when engine speed Ne is the same in the steady driving mode and in the transient state, variation Aw (Aco = Ne - o)tdc) which is difference between engin--' speed Ne and otdc has a tendency that the variation in the transient state is calculated to be smaller than that in the steady driving mode. [0069]
This reason is that Ne2 of the Ne2 interval in which
the cotdc interval is included is very high, compared with interval engine speed in the steady driving mode, which is an element to be regarded as important when the load factor F is calculated, is offset by calculating an average value of Nel and Ne2. Hereby, the load factor F calculated in the transient state is calculated to be smaller, compared with an actual engine loaded condition. [0070]
Therefore, in the transient state, when average engine speed NeA is calculated, it is desirable that the magnitude of engine speed Ne2 is reflected. Hereby, in the example shown in Fig. 8, when NeA is calculated, different weighting processing is executed between Nel and Ne2. In the example shown in Fig. 8, the weight of Ne2 is made bigger than the weight of Nel by setting an arithmetic expression of average engine speed NeA in one cycle to "NeA = Nel X (1 - a) + Ne2 x a" and setting a weighting factor a to 0.5 or larger, and NeA is increased. A weighting unit that executes weighting processing is included in the Ne

calculating unit 52 (see Fig. 2) in the load factor
calculator 50.
[0071]
Next, a conceptual diagram showing weighting processing shown irt Fig. 9 will be referred. In an example shown in Fig. 9, an average engine speed when no weighting processing is executed is shown by NeAO (a broken line) and an average engine speed when weighting processing is executed (for example, a = 0.55) is shown by NeA (a full line). At this time, the variation of crank angular velocity co is calculated as AcoO when no weigliting processincj is executed, while when weighting processing is
executed, the variation increases up to Aw (see Fig. 8). Hereby, a calculated value of the engine load factor F also increases and in the transient state, a load factor F corresponding to an actual engine loaded condition is calculated. [0072]
In the steady driving mode, since the difference between Nel and Ne2 is small even if the above-mentioned weighting processing is executed, an effect upon a load factor F is small. Therefore, a method of operating a load factor F is not required to be changed between a steady-state value and a transient state and a load of operation is never increased. [0073]
Fig. 10 is a graph showing a method of deriving the weighting factor a. As described above, in the steady

driving mode, even if the weighting factor a is varied, a value of Aco hardly varies. In the meantime, in the transient state, as the weighting factor a is increased, Aco increases. At this time, when the weighting factor a is
set to a point at which Aco in the transient state is equal to Aco in the steady driving mode, the load factors F in the steady driving mode and in the transient state can be
equalized in a case that cotdc is equal. [0074]
As described above, according to the engine load detector according to the invention, since the predetermined interval for detecting NeA is set to one cycle when average engine speed NeA used for calculating
the load factor F (F = Aco / NeA x loo) is calculated, the predetermined interval is divided into the Nel interval including the intake stroke and the Ne2 interval including the combustion and expansion stroke in two, respective interval engine speed Nel, Ne2 are calculated, weighting processing is executed so that weight for Ne2 is larger than weight for Nel and an average of both values is calculated, the magnitude of the interval engine speed Ne2 of the Ne2 interval to be regarded as important when the load factor F is calculated is reflected on a calculated value of the load factor F and a suitable engine load can be calculated. Hereby, even if the variation of engine speed increases in acceleration and in running on an irregular road, a load of the engine corresponding to this can be acquired by operation.

[0075]
The configuration of the engine and the pulser rotor, the dimension and the number of the reluctors, the positions of the reluctors on the pulser rotor, the positions of the reluctors for the position of TDC, the value of the weighting factor a, the setting of the predetermined interval for detecting average engine speed NeA and others are not limited to the above-mentioned embodiment and various changes are allowed. The engine load detector according to the invention can be applied to various general purpose engines in addition to an engine of a vehicle such as a motorcycle.
[0076]
Next, a method of canceling reluctor tolerance applied to the engine load detector according to the invention will be described. The method of canceling reluctor tolerance reduces an effect of the dimensional tolerance of the reluctors in the arithmetic expression for calculating average engine speed NeA by utilizing the above-mentioned weighting processing and the linear
transition (see Fig. 4) of the crank angular velocity © in the interval including the intake stroke. That is, the effect of the dimensional tolerance on a finally calculated load factor F can be reduced. Referring to Figs. 10 to 13, a concrete method will be described. [0077]
Fig. 11 is an explanatory drawing showing relation between a detection interval when the method of canceling

reluctor tolerance is applied and the Nel interval and the Ne2 interval. In this embodiment, an interval from the iitarting point G3 of the second reluctor until the crank is turne'i once is set to the interval D4 and average engine speed NeA during the interval D4 is calculated. The interval D4 is an interval displaced backward by the third angle 93 (22.5 degrees in this embodiment) based upon the Nel interval and the Ne2 interval. In this embodiment, the
interval D4 is further divided into an cotdc interval (45 degrees) and an 0)4 interval (315 degrees). The setting of the intervals is executed by the Ne calculating unit 52. [0078]
Fig. 12 is a graph showing relation between angular
velocity co in the transient state and a detection interval. The same reference numeral as the above-mentioned one denotes the same or the similar part. In Fig. 12, the interval D4 including the combustion and expansion stroke is set to an interval D4 (n) and an interval before one turn of the crank is set to an interval D4 (n - 1) . That is, the detection interval for calculating average engine speed NeA includes the interval D4 (n - 1) and the interval D4 (n) . In the meantime, the ca4 interval includes an co4 (n) interval as a second interval and an co4 (n - 1) interval as a first interval. Further, the cotdc interval includes an 0itdc2 interval as a second reluctor interval and an otdcl interval as a first reluctor interval. [0079]

Next, a method of calculating average engine speed NeA in the detection interval in the above-mentioned setting of the intervals will be examined. As described above, in the weighting processing in the transient state, it is desirable that the setting of intervals on which a
characteristic that crank angular velocity co shifts linearly and without substantially decreasing from the intake stroke to a former half of the compression stroke and rapidly rises at the combustion and expansion stroke is suitably reflected is performed. Hereby, average engine speed NeA is calculated based upon an average of interval engine speed 0)4 (n - 1) of the 0)4 (n - 1) interval and interval engine speed co4 (n) of the ci)4 (n) iriterval. [00801
As a result, an arithmetic expression of NeA in which weighting is considered is "NeA = (1 - a) xco4 (n - 1) + a X034 (n)". In this embodiment, the NeA is defined not as finally calculated average engine speed NeA but as a first average HI. A value of the weighting factor a can be arbitrarily set. In the steady driving mode, however, even if the weighting factor a is varied, a value of ACD is substantially unchanged. In the meantime, in the transient state, as the weighting factor a is increased, ACD increases At this time, when the weighting factor a is set to a point
at which Aco in the transient state is equal to Aco in the steady driving mode, the load factor F can be equalized in
a case that cotdc is equal. [0081]

Next, Fig. 13 showing an arithmetic expression for calculating Am will be also referred. As described above, as Aco = Ne - cotdc. A© is equal to NeA - 0)tdc2 when this is applied to the example shown in Fig. 12. Dimensional tolerance (for example, ±1%) is allowed for a mechanical part and a dimensional error by dimensional tolerance also occurs in a dimension in a circumferential direction of the second reluctor 12. An effect which the dimensional error in the circumferential direction has on a calculated value
of Am will be described below. [0082]
When the length in the circumferential direction of the second reluctor 12 shifts, a calculated value of NeA also shifts. In this case, however, it is supposed that no effect of dimensional tolerance is included in NeA. When NeA is 2000 (rpm) and utdc2 is 1800 (rpm) on the above-mentioned condition, Ao) in a case that the dimension in the circumferential direction of the second reluctor 12 is a reference value is 200 (rpm) acquired by subtracting 1800 from 2000. In the meantime, when the dimension in the circumferential direction of the second reluctor 12 is longer by 1?- than the reference value and hereby, wtdc2 is smaller by 1%, Aco is 218 (rpm) acquired by subtracting 1782 from 2000. That is, the error of 1% of the circumferential dimension of the second reluctor 12 is amplified to large
difference of 10% in a calculated value of Aco. [0083]

To avoid the above-mentioned amplification of dimensional tolerance, it is desirable that NeA can be represented as revolution speed calculated in the same interval of 45 degrees as Qtdc2. When this is realized, a calculated value of Aco is never off the reference value by 1% or more because the arithmetic expression of Aco is the subtraction of revolution speeds calculated in relation to the same intervals of 45 degrees. Then, in this embodiment, the arithmetic expression of NeA is transformed to make it compatible to enhance the accuracy of NeA by possibly extending the detection interval for calculating NeA, to adjust NeA to a suitable value by weighting processing and to reduce the effect of the dimensional tolerance of the
second reluctor 12 on Aci). [0084]
Concretely, the average (the first average HI) of Ne of the co4 (n - 1) interval in which weighting is considered and the co4 (n) interval is multiplied by a value to be '1' at all times. The value is acquired by dividing an
approximate value K of the revolution speed of the co4 (n -1) interval by actually measured revolution speed co4 (n -1) in the co4 (n - 1) interval. [0085]
The approximate value K is calculated utilizing a characteristic that crank angular velocity co linearly shifts at the intake stroke. That is, the approximate value K is acquired by representing the revolution speed of the oo4 (n - 1) interval which is the interval of 315

degrees by an average of the first reluctor revolution
speed cotdcl calculated in relation to the cotdcl interval (the interval of 45 degrees) and the second reluctor
revolution speed catdc2 calculated in relation to the utdc2 j.nterval (the interval of 45 degrees) using revolution speed calculaterl in relation to the interval of 45 degrees. In this embodiment, the approximate value K is defined as a second average H2. [0086]
A result of dividing the approximate value K (The second average H2) by the first revolution speed 0)4 (n - 1) calculated in relation to the 0)4 (n - 1) interval is naturally '1'. That is, NeA in a frame in the drawing is acquired by multiplying the first average HI by a value to be '1•. [0087]
When NeA is operated, co4 included in the first
average HI is divided by 0)4 in a denominator and is canceled. That is, dimensional tolerance related to the interval of 315 degrees is canceled from the inside of the frame. Hereby, in NeA, only dimensional tolerance related to the interval of 45 degrees is left; however, since the dimensional tolerance is related to the same interval of 45 degrees as o)tdc2 outside the frame, an arithmetic expression, Ao) = NeA - a)tdc2 is the subtraction of the same intervals of 45 degrees. Therefore, an effect of the dimensional tolerance is never amplified by subtraction and

as a result, Aco and the load factor F respectively hardly having an effect of dimensional tolerance can be calculated [0088]
The above-mentioned method of operating Aw can be also similarly applied to the steady driving mode without being limited to the transient state. In the operation of
Aco and the load factor F, the first reluctor 11 (see Fig. 3) of the pulser rotor 10 is not necessarily required. [0089]
As described above, according to the engine load detector according to the present invention, since revolution speed related to the interval of 315 degrees is converted to revolution speed related to the interval of 45 degrees by multiplying the revolution speed i elated to the interval of 315 degrees by a value to be '1' at all times in the arithmetic expression for calculating NeA and dimensional tolerance related to the interval of 315 degrees is canceled by the division in the conversion even if the reluctor of the pulser rotor has the dimensional tolerance in the circumferential length, an effect of the dimensional tolerance when Aco (Aco = NeA - (Dtdc2) is calculated can be prevented from being amplified. Hereby, it can be minimally inhibited that the dimensional tolerance of the reluctor has an effect on a calculated value of the load factor F of the engine. [0090]
Concretely, first, when the average engine speed NeA used for calculating the load factor F (F = Aco / NeA x 100)

is calculated, the detection interval for calculating NeA is set to length for two rotations of the crankshaft starting from the starting point G3 of the passage of the second reluctor 12. Next, the detection interval is divided into the four intervals including the .first reluctor interval (the otdcl interval) and the second reluctor interval (the utdc2 interval) respectively corresponding to a position in which the second reluctor 12 passes the magnetic pickup 20, and the first interval (the
©4 (n - 1) interval) and the second interval (the CD4 (n) interval) respectively corresponding to a position in which the second reluctor 12 does not pass the magnetic pickup 20 [0091]
Next, Fig. 14 will be referred. Fig. 14 is a block diagram showing a procedure for calculating the average engine speed NeA. In a first average calculating unit 104, the first average HI which is the average of the first revolution speed 0)4 (n - 1) detected in a first revolution speed detecting unit 100 and the second revolution speed ©4 (n) detected in a second,revolution speed detecting unit 101 is calculated. In the meantime, in a second average calculating unit 105, the second average H2 (the approximate value K) which is the average of tlie first reluctor revolution speed cotdcl detected in a first reluctor revolution speed detecting unit 102 and the second reluctor revolution speed cotdc2 detected in a second reluctor revolution speed detecting unit 103 is calculated. In an average engine speed calculating unit 106, the

average engine speed NeA is calculated using the first average HI calculated in the first average calculating unit 104, the second average H2 calculated in the second average calculating unit 105 and the first revolution speed a4 (n -1) . Hereby, the dimensional tolerance related to the interval of 315 degrees is canceled in the arithmetic expression of NeA and when Au is calculated (Aco = NeA -(:otdc2), the dimensional tolerance can be prevented from being amplified. [0092]
It is clarified by experiments that the variation of crank angular velocity is apt to be influenced by the torque transmitting system from the crankshaft to the rear wheel. Accordingly, to more precisely calculate a load factor of the engine, it is desirable to consider the effect of the torque transmitting system. A method of calculating (correcting) a load factor of the engine considering that the variation of crank angular velocity is particularly influenced by the gear ratio of the transmission will be described below. [0093]
Fig. 15 is a graph showing relation between engine speed Ne and a calculated value of Aco (Aw = Ne - otdc) . The graph is based upon actually measured values in a test using an engine provided with a four-speed transmission. As described above, the variation Aco of crank angular velocity increases as engine speed Ne decreases, that is, in a low torque region in which the inertia force of the

crankshaft decreases. Particularly in the vicinity of the low torque region, an effect by difference in transmission gear ratio has a tendency to increase. In an example shown in the graph, as transmission gear ratio increases from a fourth speed gear (a full line) the gear ratio of which is the smallest to a first speed gear (an alternate long and two short dashes line) via a third speed gear (an alternate long and short dash line) and a second speed gear (a broken
line), a calculated value of A© becomes small. This shows that even if engine speed Ne is the same and a loaded
condition of the actual engine is the same, Aco has a tendency to have a small value as transmission gear ratio increases. Accordingly, when the gear ratio of the transmission is large and engine speed Ne is low, a problem that a load factor of the engine is calculated in a smaller value than an actual loaded condition occurs. [0094]
Then, this embodiment has a characteristic that to reduce the effect which the difference in gear ratio has upon A©, a value of Aco is corrected according to the gear ratio of the transmission. In this embodiment, currently selected gear ratio (speed stage) is detected by the gear position sensor as the transmission gear ratio detecting unit and correction is executed by applying a correction factor according to the gear ratio to ©tdc used in calculating Aco. More concretely, correction is executed (Aa = Ne - K X cotdc) by multiplying ©tdc included in an

expression for calculating Aco (Aca = Ne - cotdc) by the
correction factor K.
[0095]
Fig. 16 is a correction factor map showing relation among engine speed Ne, current speed (a gear position) and the correction factor K. In this embodiment, when the fourth speed gear the gear ratio of which is the smallest
is selected, the correction of cotdc is not made and independent of a value of engine speed Ne, the correction factor K is set to 1.0. In the meantime, it is set that as gear ratio increases from the third speed gear to the first speed gear, a value of the correction factor K also becomes large. [0096]
As shown in Fig. 15, the effect which the difference
in gear ratio has upon Am decreases according to the increase of engine speed Ne. Hereby, a value of the correction factor K is set to also become small according to the increase of engine speed Ne. The correction factor map is stored in the load factor calculator 50 (see Fig. 2) in ECU 30 after the map is verified by experiments and others beforehand. [0097]
Fig. 17 is a flowchart showing a procedure for the
correction control of Aco using the correction factor K. In a step S200, a gear position GP is detected by the gear position sensor. In the next step S201, engine speed Ne is detected. In a step S202, a correction factor K is derived

from the correction factor map (see Fig. 16) using the gear position GP and the engine speed Ne. In a step S203, the derived correction factor K is applied to -the expression for calculating A© (ACD = Ne - K X cotdc) and hereby, a corrected value of ACD is calculated. According to the above-mentioned correction control of Aco, the more precise forecast of an engine load according to the gear ratio of the transmission is enabled, ignition timing control and others can be more accurately and precisely made, and fuel economy and hazardous exhaust gas can be reduced. [0098]
In the above-mentioned embodiment, the speed stage of the stepped transmission is detected by the gear position sensor and the correction factor K is derived, however, for example, in the case of a continuously variable transmission depending upon a belt converter, transmission gear ratio is detected based upon an amount of the movement of a pulley driven to vary gear ratio and the correction factor K may be also derived according to the gear ratio. [0099]
Transmission gear ratio is calculated based upon vehicle speed and engine speed and the correction factor K may be also derived according to the gear ratio. According to this method, the position sensor for detecting the speed stage is not required and the reduction of the cost can be expected. [0100]

The configuration of the engine and the pulser rotor, the dimension and the number of the reluctors, the positions of the reluctors on the pulser rotor, the positions of the reluctors in the position of TDC, the value of the weighting factor a and the setting of the detection interval for detecting the average engine speed NeA are not limited to the above-mentioned embodiment, and various changes are allowed. The reluctor tolerance canceling method applied to the engine load detector according to the present invention can be applied to an engine for a vehicle such as a motorcycle and various general purpose engines. [Reference Signs List] [0101]
I Engine,
6 Ignition device,
7 Piston,

8 Cylinder,
9 Crankshaft,
10 Pulser rotor,
II First reluctor,
12 Second reluctor,
20 Magnetic picl 30 ECU,
40 Crank pulse detector,
50 Load factor calculator,
51 Timer,
52 Ne calculating unit.

53 Aco calculating unit,
54 (otdc calculating unit,
56 Load factor calculating unit,
60 Control correction quantity calculator,
70 Ignition controller,
100 First revolution speed detecting unit,
101 Second revolution speed detecting unit,
102 First reluctor revolution speed detecting unit,
103 Second reluctor revolution speed detecting unit,
104 First average calculating unit,
105 Second average calculating unit,
106 Average engine speed calculating unit,
F Load factor,
Gl Starting point of first reluctor,
G2 End point of first reluctor,
G3 Starting point of second reluctor,
G4 End point of second reluctor,
HI First average,
H2 Second average (Approximate value K),
a Weighting factor,
CO Crank angular velocity,
cotdc Crank angular velocity when reluctor passes,
Nel Interval engine speed of Nel interval,
Ne2 Interval engine speed of Ne2 interval,
NeA Average engine speed in predetermined interval,
Aco Variation of angular velocity,
co4 (n - 1) First revolution speed,
(D4 (n) Second revolution speed.

©tdcl First reluctor revolution speed,
cotdc2 Second reluctor revolution speed,
NeA Average engine speed in detection interval,

[Document Name] Scope of Claims [Claim 1]
An engine load detector which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, the engine load detector comprising:
a unit that calculates an interval engine speed per interval acquired by dividing a predetermined interval for detecting an average engine speed into plural intervals based upon each output signal from the pickup;
a weighting unit that applies different weighting processing to the plural interval engine speeds; and
a loaded condition calculating unit that calculates the average engine speed based upon an average of the plural weighted interval engine speeds and operates a loaded condition of the engine using the average engine speed. [Claim 2]
The engine load detector according to Claim 1, wherein, in the weighting processing, a weighting ratio of the interval including a combustion and expansion stroke out of the plural divided intervals is set to be larger than another interval, [Claim 3]

The engine load detector according to Claim 1 or 2, wherein the predetermined interval is detected based upon an output signal from the pulser rotor. [Claim 4]
The engine load detector according to any of Claims 1 to 3,
wherein the predetermined interval is set as follows:
a length for two rotations of the crankshaft is divided into two, i.e. a first interval and a second interval;
the first interval includes an intake stroke; and
the second interval includes a combustion and expansion stroke. [Claim 5]
The engine load detector according to any of Claims 1 to 4, wherein a loaded condition of the engine is a load factor calculated by dividing a revolution speed while the reluctor passes the pickup by the average engine speed. [Claim 6]
The engine load detector according to Claim 5,
wherein: the reluctor is arranged in a position immediately before the top dead center of the engine; and
the load factor is calculated using a revolution speed while the reluctor passes the pickup immediately before the top dead center on a compressive side. [Claim 7]
The engine load detector according to Claim 5 or 6, wherein feedback control over at least the ignition timing

of the engine is made according to the calculated load
factor.
[Claim 8]
An engine load detecting method of a device which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, the engine load detecting method comprising:
a procedure for dividing a predetermined interval for detecting an average engine speed into plural intervals;
a procedure for calculating an interval engine speed per divided interval;
a procedure for applying different weighting processing to the plural interval engine speeds;
a procedure for calculating the average engine speed by calculating an average of the plural weighted interval engine speeds; and
a procedure for operating a loaded condition of the engine using the average engine speed. [Claim 9]
An engine load detector which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a

top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup,
wherein: a detection interval for detecting an average engine speed is set to a length for two rotations of the crankshaft starting from a starting point of the passage of the reluctor;
the detection interval is divided into four intervals including a first reluctor interval and a second reluctor interval respectively corresponding to a position in which the reluctor passes the pickup per rotation out of the two rotations of the crankshaft, and a first interval and a second interval respectively corresponding to a position in which the reluctor does not pass the pickup; and the engine load detector comprises:
a unit that calculates a first average which is an average of a first revolution speed detected in the first interval and a second revolution speed detected in the second interval;
a unit that calculates a second average which is an average of a first reluctor revolution speed detected in the first reluctor interval and a second reluctor revolution speed detected in the second reluctor interval;
a unit that calculates the average engine speed by multiplying a value acquired by dividing the first average by the first revolution speed by the second average; and

a loaded condition calculating unit that calculates a loaded condition of the engine using the average engine speed. [Claim 10]
The engine load detector according to Claim 9, wherein the unit that calculates the average engine speed calculates the average engine speed NeA by the following expression: [Mathematical expression 1]

where the first revolution speed is u4 (n - 1), the second revolution speed is u4 (n), the first reluctor revolution speed is cotdcl, the second reluctor revolution speed is a)tdc2 and a weighting factor is a. [Claim 11]
The engine load detector according to Claim 10,
wherein: the first interval includes an intake stroke and the second interval includes a combustion and expansion stroke; and
the weighting factor a for applying different weighting processing between the first revolution speed and the second revolution speed when the first average is calculated is set to 0,5 or larger. [Claim 12]
The engine load detector according to any of Claims 9 to 11,
wherein: the reluctor is arranged in a position

immediately before a top dead center of the engine; and
a loaded condition of the engine is a load factor calculated by dividing the second reluctor revolution speed by the average engine speed. [Claim 13]
The engine load detector according to Claim 12, wherein feedback control over at least an ignition timing of the engine is made according to the load factor. [Claim 14]
An engine load detecting method of an engine load detector which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, the engine load detecting method comprising:
a procedure for setting a detection interval for detecting an average engine speed to a length for two rotations of the crankshaft starting from a starting point of the passage of the reluctor;
a procedure for dividing the detection interval into four intervals including a first reluctor interval and a second reluctor interval respectively corresponding to a position in which the reluctor passes the pickup per rotation out of the two rotations of the crankshaft, and a first interval and a second interval respectively

corresponding to a position in which the reluctor does not pass the pickup;
a procedure for calculating a first average which is an average of a first revolution speed detected in the first interval and a second revolution speed detected in the second interval;
a procedure for calculating a second average which is an average of a first reluctor revolution speed detected in the first reluctor interval and a second reluctor revolution speed detected in the second reluctor interval; and
a procedure for calculating the average engine speed by multiplying a value acquired by dividing the first average by the first revolution speed by the second average [Claim 15]
An engine load detector which is provided with a pulser rotor rotated in synchronization with a crankshaft of an engine, a reluctor provided to the pulser rotor and located at a crank angle corresponding to the vicinity of a top dead center of the engine and a pickup that detects the passage of the reluctor and which detects a loaded condition of the engine based upon an output signal from the pickup, the engine load detector comprising:
transmission gear ratio detecting unit that detects the gear ratio of a transmission,
wherein: the loaded condition of the engine is represented as a load factor calculated by dividing revolution speed while the reluctor passes the pickup by

average engine speed; and
the revolution speed while the reluctor passes the pickup is corrected based upon the gear ratio. [Claim 16]
The engine load detector according to Claim 15, wherein the transmission gear ratio detecting unit is a gear position sensor that detects the speed stage of a stepped transmission. [Claim 17]
The engine load detector according to Claim 16,
wherein: the correction of revolution speed while the reluctor passes the pickup is executed by multiplying the revolution speed by a correction factor; and
the correction factor is set to be larger as the number of gear stages of the stepped transmission decreases. [Claim 18]
The engine load detector according to Claim 15, wherein:
the transmission gear ratio detecting unit calculates transmission gear ratio based upon vehicle speed and engine speed.

Documents:

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Patent Number

269556

Indian Patent Application Number

3117/CHE/2009

PG Journal Number

44/2015

Publication Date

30-Oct-2015

Grant Date

27-Oct-2015

Date of Filing

16-Dec-2009

Name of Patentee

HONDA MOTOR CO., LTD.

Applicant Address

1-1, MINAMI-AOYAMA 2-CHOME, MINATO-KU, TOKYO 107-8556

Inventors:

#	Inventor's Name	Inventor's Address
1	KOKUBU, SHIRO	C/O HONDA R&D CO., LTD., 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193
2	IBATA, RYOSUKE	C/O HONDA R&D CO., LTD., 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193
3	OKAWADA, NAOHISA	C/O HONDA R&D CO., LTD., 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193
4	NISHIDA, KENJI	C/O HONDA R&D CO., LTD., 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193
5	TAKAHASHI, YOICHI	C/O HONDA R&D CO., LTD., 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193

PCT International Classification Number

F02D 45/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2009/194366	2009-08-25	Japan
2	2008-331108	2008-12-25	Japan