Title of Invention

"AN IGNITION CONTROL SYSTEM FOR A VEHICLE"

Abstract

[OBJECT] To secure, in a vehicle which includes a centrifugal clutch or a belt-type non-stage transmission, a smooth acceleration performance while preventing occurrence of knocking upon acceleration of an engine. [CONSTITUTION] When acceleration is to be performed from a low or medium speed rotation region of an engine, the ignition timing is made different before and after a centrifugal clutch is engaged or during slipping of a belt-type non-stage transmission and after elimination of the slipping. Prior to engagement of the centrifugal clutch or during a slip of the belt-type non-stage transmission, the load to the engine is low and knocking is not likely to occur, and consequently, the ignition timing is led to make a rise of the engine speed better. After engagement of the centrifugal clutch or after elimination of the slip of the belt-type non-stage transmission, the load to the engine is high and knocking is likely to occur, and consequently, the ignition timing is delayed to prevent occurrence of knocking thereby to allow smooth acceleration.

Full Text

[DETAILED DESCRIPTION OF THE INVENTION] [Technical Field to Which the Invention Belongs] This invention relates to an ignition control system for a vehicle wherein a driving force of an engine is transmitted to a driving wheel via a centrifugal clutch or belt-type non-stage transmission. [ Prior Art] Generally, the ignition timing of an engine for a vehicle such as a scooter is delayed in an idling region in order to raise the idling stability, but in a low or medium speed rotation region, the ignition timing is led in order to achieve promotion of the output power or reduction of the fuel consumption amount. The official gazette of Japanese Patent Laid-Open Application No. Heisei 7-243373 discloses that, if an engine is accelerated suddenly from a low or medium speed rotation region, then since sudden increase in load and leading of the ignition timing occur at a time, knocking sometimes occurs, and upon sudden acceleration from a low or medium speed rotation region, the ignition timing is delayed to prevent occurrence of knocking. [Subject to Be Solved by the Invention] By the way, in a vehicle which includes a centrifugal clutch or belt-type non-stage transmission, upon sudden acceleration of an engine, the centrifugal clutch is engaged first, and then the driving force of the engine is transmitted to a driving wheel. Consequently, a time lag which corresponds to a time in which the centrifugal clutch is engaged is sometimes produced in transmission of the driving force, or, by sudden acceleration, a slip is sometimes produced with a belt of the belt-type non-stage transmission and a time lag is produced before the driving force of the engine is transmitted to the driving wheel after acceleration. For a period after acceleration of the engine is started until the centrifugal clutch is engaged and the driving force of the engine is transmitted to the driving wheel, or for a period until the slip of the belt-type non-stage transmission is eliminated and the driving force of the engine is transmitted to the driving wheel, the load to the engine is so low that no knocking occurs. However, in the prior art described above, since the ignition timing is delayed even before the driving force is transmitted sufficiently to the driving wheel after acceleration of the engine, the rise of the speed of the engine is delayed as much and the acceleration feeling is sometimes deteriorated . The present invention has been made in view of such circumstances as described above, and it is an object of the present invention to secure a smooth acceleration performance while preventing occurrence of knocking upon acceleration of an engine. [Means to Solve the Subject] In the invention as set forth in claim 1, for a period until after the engine speed is increased by acceleration until engagement of the centrifugal clutch is completed or until after a momentary slip of the belt-type non-stage transmission caused by acceleration is eliminated and the power transmission system to the driving wheel is established, delaying of the ignition timing is not performed. Consequently, during the period, the engine speed increases rapidly, and driving force is transmitted in a moment after the acceleration. Besides, prior to engagement of the centrifugal clutch or during slipping of the belt, since the load is low, knocking seldom occurs even if delaying of the ignition timing is performed. Since delaying of the ignition timing is performed after engagement of the centrifugal clutch is completed or the slip of the belt is eliminated, even if the load is increased by transmission of power from the engine to the driving wheel, knocking does not occur and smooth acceleration can be achieved. Therefore, the present invention relates to An ignition control system for a vehicle comprising a centrifugal clutch (26) or belt-type non-stage transmission (20) wherein a driving force of an engine is transmitted to a driving wheel via said centrifugal clutch or belt-type non-stage transmission, characterized in that it comprises acceleration detection means for detecting an acceleration condition of said vehicle, ignition delaying means for delaying an ignition timing after acceleration is detected wherein the delaying of the ignition timing is performed after engagement of the centrifugal clutch is completed or the slip of belt is eliminated, and time delaying means for setting a time delay until after an ignition timing is delayed after acceleration is detected. [BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS] [FIG. 1] FIG. 1 is a vertical sectional view of a power unit of a motorcycle. [FIG. 2] FIG. 2 is a circuit diagram of an ignition system. [FIG. 3] FIG. 3 is a first partial view of a flow chart of a main routine. [FIG. 4] FIG. 4 is a second partial view of the flow chart of the main routine. [FIG. 5] FIG. 5 is a flow chart of an ignition timing calculation routine. [FIG. 6] FIG. 6 is a map for searching for an ignition timing. [FIG. 7] FIG. 7 is a graph illustrating operation. [Description of Reference Symbols] 20 belt-type non-stage transmission 26 centrifugal clutch 33 ignition timing control circuit E engine Ne engine speed U electronic control unit Wr rear wheel ignition timing [Form in Embodying the Invention] In the following, a form in embodying the present invention is described with reference to an embodiment of the present invention shown in the accompanying drawings. FIGS. 1 to 7 show an embodiment of the present invention, and FIG. 1 is a vertical sectional view of a power unit of a motorcycle, FIG. 2 is a circuit diagram of an ignition system, FIG. 3 is a first partial view of a flow chart of a main routine, FIG. 4 is a second partial view of the flow chart of the main routine, FIG. 5 is a flow chart of an ignition timing calculation routine, FIG. 6 is a map for searching for an ignition timing, and FIG. 7 is a graph illustrating operation. FIG. 1 shows a structure of a power unit P of a motorcycle. The power unit P includes a right case half 2 and a left case half 3 coupled integrally to each other by means of bolts 1, ..., and a right cover 5 is coupled to a right side face of the right case half 2 by means of bolts 4, ... while a left cover 6 is coupled to a left side face of the left case half 3 by means of bolts (not shown). Front portions of the right case half 2 and the left case half 3 define a crankcase 7 of an engine E, and a cylinder block 8 and a cylinder head 9 are coupled to a front portion of the crankcase 7. An ignition plug 10 is provided at an end of the cylinder head 9. A crankshaft 12 supported on the right case half 2 and the left case half 3 by means of a pair of ball bearings 11, 11 is connected via a connecting rod 14 to a piston 13 which is fitted for sliding movement in a cylinder formed in the cylinder block 8. A generator 15 is disposed at the right end of the crankshaft 12. The left case half 3 and the left cover 6 define a transmission case, in which a belt-type non-stage transmission 20 is accommodated. The belt-type non-stage transmission 20 includes a driving pulley 21 supported at the left end of the crankshaft 12 which serves as an input power shaft, a driven pulley 24 supported at the left end of an output power shaft 23 supported on the left case half 3 and the right case half 2 by a pair of ball bearings 22, 22, and an endless belt 25 extending around the driving pulley 21 and the driven pulley 24. A centrifugal clutch 26 for transmitting rotation of the driven pulley 24 to the output power shaft 23 is provided at the left end of the output power shaft 23. A reduction gear train 27 is provided in rear portions of the left case half 3 and the right case half 2, and the speed of rotation of the output power shaft 23 described above is reduced by the reduction gear train 27 to drive the driving wheel. Accordingly, if the engine speed increases from an idling speed, then the centrifugal clutch 26 is first engaged to allow the driving force of the engine E to be transmitted to the driving wheel, and if the engine speed further increases, then the groove width of the driving pulley 21 is narrowed while the groove width of the driven pulley 24 is widened so that the transmission ratio of the belt-type non-stage transmission 20 varies from the LOW side to the TOP side. As shown in FIG. 2, a vehicle V of the scooter type having a front wheel Wf as a driven wheel and a rear wheel Wr as a driving wheel includes a power unit P of the swing type which has the engine E mounted at a front portion thereof. The power unit P is different in type from that described with reference to FIG. 1, but includes a belt-type non-stage transmission 20 and a centrifugal clutch 26 similarly as in that of FIG. 1 and has no substantial difference in function. An ignition unit 31 for controlling the ignition timing of the ignition plug 10 of the engine E includes an ignition circuit 32 and an ignition timing control circuit 33. The ignition circuit 32 connected between a battery 34 and an ignition coil 35 for causing the ignition plug 10 to spark includes an oscillation circuit 36 for oscillating a battery voltage, a transformer 37 for supplying a high voltage to a capacitor 38 by oscillation thereof, the capacitor 38 for accumulating a high secondary voltage of the transformer 37, and a thyristor 39 for discharging energy accumulated in the capacitor 38 to supply discharged charge to the ignition coil 35. The ignition timing control circuit 33 includes a CPU (central operation processing unit) 40, a RAM (random access memory) 41, a ROM (read only memory) 42, a first map 43 stored in the ROM 42, and a second map 44 stored similarly in the RAM 41. The CPU 40 calculates a crank angle and an engine speed based on a signal from a pulse generator 45 provided in the proximity of the generator 15 described above supported on the crankshaft 12 and outputs an ignition permission signal to the thyristor 39 based on an ignition timing 9 ig stored in the first map 43 or the second map 44. If the thyristor 39 is turned on, then discharge current of the capacitor 38 flows through a primary coil of the ignition coil 35, whereupon a high voltage is induced in a secondary coil, and the ignition plug 10 sparks at a predetermined ignition timing. Power generated by the pulse generator 45 is used to charge the battery 34 via a regulator 46. In the following, operation of the embodiment of the present invention having the construction described above is described. First, an engine speed Ne is calculated in step SO of the flow charts of FIGS. 3 and 4. In the following step S1, since a second timer T2 which will be hereinafter described is initially T2 = 0, the processing advances to step S2, in which a variation amount Ne of the engine speed Ne is calculated. Then, if, in the following step S3, the engine speed Ne is within a low or medium speed rotation region defined by Nel ≤ Ne ≤ Ne2, then the processing advances to step S4. On the other hand, if the engine speed Ne is not in the region of Nel ≤ Ne ≤ Ne2 in step S3, then the processing advances to step S15, in which an ignition timing 6 θig is calculated based on a first map for ordinary operation (refer to (A) of FIG. 6). The region of Nel to Ne2 mentioned above is an engine speed region within which it is desired to obtain a smooth acceleration feeling of the vehicle, and Nel and Ne2 are set, for example, to Nel = 3,000 rpm and Ne2 = 6,000 rpm, respectively. However, it is a matter of course that the region may be some other region. Since, in step S4, a first timer T1 has an initial value of T1 = 0, the processing advances to step S5, in which counting of the first timer T1 is started. The processing advances to step S15 described above hereinabove until after the first timer T1 reaches a predetermined value (for example, 1 second), and after the predetermined value is reached, the first timer T1 is reset to T1 = 0 in step S7, whereafter the processing advances to step S8. Since acceleration of the vehicle from a predetermined fixed speed state can be detected by the time setting of the first timer T1, it is possible to perform delaying control of the ignition timing only in a predetermined acceleration condition following the predetermined fixed speed condition, and a system which is high in universality can be provided in accordance with a type of the vehicle. If it is discriminated in step S8 that the engine speed variation amount ANe is larger than Nel (for example, 1,000 rpm/0.5 seconds) and the vehicle is in an accelerated condition, then the processing advances to step S9, but if it is discriminated that the vehicle is not in an accelerated condition, then the processing advances to step S15. Since, in step S9, the second timer T2 has an initial value of T2 = 0, the processing advances to step S10, in which counting of the second timer T2 is started. It is to be noted that, after counting of the second timer T2 is started once, the processing directly advances from step S1 described above to step Sll. Consequently, if acceleration is detected once in step S8, then the ignition timing is delayed in accordance with the second map without fail after the second timer T2 counts up to a predetermined value. Until after the second timer T2 reaches a predetermined value (for example, 0.1 to 0.2 seconds, preferably 0.1 second) in step Sll, the processing advances to step S15 mentioned hereinabove, and after the predetermined value is reached, the processing advances to step S12. The time to be measured by the second timer T2 described above is set in accordance with a time in which, by acceleration from the low or medium speed engine speed region in which the ignition timing is set to a lead angle, the centrifugal clutch 26 is engaged with certainty after the acceleration or a time in which a slip of the endless belt 25 of the belt-type non-stage transmission 20 is eliminated. After the second timer T2 reaches the predetermined time and the accelerated condition of the engine E continues for the predetermined time in step Sll described above, the ignition timing θ ig is calculated based on a second map (refer to (B) of FIG. 6) for acceleration in step S14 until after a third timer T3 which has started in step S16 or S17 reaches a predetermined value (for example, 2 to 4 seconds, preferably 2 seconds) in step S12. Then, after the third timer T3 reaches the predetermined value in step S12 described above, the second timer T2 and the third timer T3 are set to T2 = 0 and T3 = 0 in step S13, respectively. In summary, when the engine speed Ne is within the low or medium speed rotation region for the predetermined time counted by the first timer T1 and the predetermined time counted by the second timer T2 elapses after acceleration of the engine E in the low or medium speed rotation region, calculation of the ignition timing θig based on the second map is executed for the predetermined time counted by the third timer T3. Then, except when calculation of the ignition timing θig based on the second map for acceleration, calculation of the ignition timing θig based on the first map for ordinary operation is executed . Subsequently, the subroutine in steps S14 and S15 described above is described with reference to the flow chart of FIG. 5. First in step S21, an ignition timing θig-map is searched for from the first map or the second map based on the engine speed Ne, and in step S22, an ignition timing ) of the last loop is read out. Then in step S23, the absolute value | θig-map - θig(n-1) I of a difference between the ignition timing θig-map and the ignition timing θig(n-i) is compared with a reference value θig. It is to be noted that the ignition timing θ ig is given by an angle (deg) prior to the top dead center of the piston. If a result of the comparison in step S23 reveals that the absolute value | θig-map - θig(n-i) │ of the difference is lower than the reference value θig, then the ignition timing θig-map searched out from the first map or the second map is adopted as the ignition timing θig(n) of the current loop. On the other hand, if the absolute value | θig-map - θig(n-i) │of the difference is equal to or larger than the reference value θig in step S23 described above, then the reference value θig is added to or subtracted from the ignition timing θig(n-1) of the last loop to determine the ignition timing θig(n) of the current loop thereby to prevent a sudden variation of the ignition timing θig The reference value θig mentioned above is set, for example, to 5 degrees/0.5 seconds. It is to be noted that, in step S25, when the angle is a lead angle obtained by adoption of the first map for ordinary operation, θig is added to the ignition timing θig(n-i) of the last loop, but when the angle is a delay angle obtained by adoption of the second map for acceleration, θig is subtracted from the ignition timing θig(n-1) of the last loop. As apparent from comparison between the first map for ordinary operation shown in (A) of FIG. 6 and the second map for acceleration shown in (B) of FIG. 6, the second map for acceleration exhibits, in a region of the engine speed Ne around 7,000 rpm, an angle delay comparing with the first map for ordinary operation. Accordingly, even if the load to the engine E is increased by the acceleration, occurrence of knocking by an excessive lead angle can be prevented thereby to smoothly accelerate the vehicle. Further, even when the centrifugal clutch 26 is not in an engaged state immediately after starting of acceleration, or even if the endless belt 25 of the belt-type non-stage transmission 20 slips as a result of sudden acceleration, since delaying of the angle is not performed, the engine speed Ne increases smoothly and reduction of the acceleration feeling is prevented. After counting of time by the third timer T3 is completed, since the map to be used is changed over from the second map for acceleration to the first map for ordinary operation, ordinary control can be restored after completion of acceleration. When a throttle opening θTH is increased as seen in (A) of FIG. 7 in order to accelerate the vehicle, the engine speed Ne varies in such a manner as seen in (B) and the speed of rotation of the driving wheel varies in such a manner as seen in (C). Here, each solid line corresponds to a case wherein control of the ignition timing is not performed, a chain line corresponds to the prior art wherein delaying of the ignition timing is performed simultaneously with the start of acceleration, and a broken line corresponds to the present invention wherein a time delay is set and delaying of the ignition timing is performed from the start of acceleration. In the system wherein control of the ignition timing is not performed as indicated by a solid line, the centrifugal clutch 26 is engaged after acceleration is started, and after a slip of the belt-type non-stage transmission 20 is eliminated, knocking occurs as the load to the engine E increases. Meanwhile, in the conventional system indicated by the chain line, since delaying of the ignition timing is performed simultaneously with the start of acceleration, occurrence of knocking is prevented. However, also within a period within which the centrifugal clutch 26 is not engaged as yet and the belt-type non-stage transmission 20 is slipping, that is, within a period within which the load to the engine E is low, the ignition timing is delayed, and consequently, increase of the engine speed Ne or the speed of rotation of the driving wheel is delayed and the acceleration feeling is deteriorated. On the other hand, in the system of the present invention indicated by a broken line, within a period within which the centrifugal clutch 26 is not engaged and the belt-type non-stage transmission 20 is slipping, delaying of the ignition angle is not performed, and after the load to the engine E increases since then, delaying of the ignition timing is performed. Consequently, the acceleration performance can be secured to the utmost while preventing occurrence of knocking. While the embodiment of the present invention is described above, the present invention can be modified in various manners without departing from the spirit thereof. For example, the present invention can be applied also to a vehicle with a multistage transmission wherein a centrifugal clutch is provided on a transmission input power shaft side. [Effects of the Invention] As described above, according to the present invention set forth in claim 1, since ignition control system comprises acceleration detection means for detecting an acceleration condition of a vehicle, ignition delaying means for delaying an ignition timing after acceleration is detected, and time delaying means for setting a time delay until after an ignition timing is delayed after acceleration is detected, prior to engagement of a centrifugal clutch or prior to elimination of a slip of a belt-type non-stage transmission when knocking is not likely to occur, delaying of the ignition timing is controlled to prevent a delay of acceleration, and after engagement of the centrifugal clutch or after elimination of a slip of the belt-type non-stage transmission, the ignition timing is delayed to prevent occurrence of knocking thereby to allow smooth acceleration. In the drawings: FIG. 2 36 ... OSCILLATION CIRCUIT FIG. 3 50 ... DETECT Ne S2 ... CALCULATE Ne 55 ... START T1 56 ... TI HIGHER THAN PREDETERMINED VALUE ? 57 ... RESET T1 FIG. 4 510 ... START T2 511 . . . T2 HIGHER THAN PREDETERMINED VALUE ? 512 ... T3 HIGHER THAN PREDETERMINED VALUE ? 51 4 ... CALCULATION OF θ ig FROM SECOND MAP S15 ... CALCULATION OF θig FROM FIRST MAP S17 ... START T3 FIG. 5 521 ... SEARCH FOR 522 ... READ OUT θig(n-i) FIG. 7(B), from left, from above DELAY PERIOD DETECTION OF ACCELERATION KNOCKING PRIOR ART DELAY PERIOD PRESENT INVENTION DELAY PERIOD NO IGNITION TIMING CONTROL PRIOR ART PRESENT INVENTION FIG. 7(C), from left, from above SPEED OF ROTATION OF REAR WHEEL (DRIVING FORCE) LOSS OF DRIVING FORCE NO IGNITION TIMING CONTROL PRIOR ART PRESENT INVENTION WE CLAIM: 1. An ignition control system for a vehicle comprising a centrifugal clutch (26) or belt-type non-stage transmission (20) wherein a driving force of an engine is transmitted to a driving wheel via said centrifugal clutch or belt-type non-stage transmission, characterized in that it comprises acceleration detection means for detecting an acceleration condition of said vehicle, ignition delaying means for delaying an ignition timing after acceleration is detected wherein the delaying of the ignition timing is performed after engagement of the centrifugal clutch is completed or the slip of belt is eliminated, and time delaying means for setting a time delay until after an ignition timing is delayed after acceleration is detected. 2. An ignition control system for a vehicle substantially as herein described with reference to the accompanying drawings.

Documents:

2434-del-1997-abstract.pdf

2434-del-1997-claims.pdf

2434-del-1997-correspondence-others.pdf

2434-del-1997-correspondence-po.pdf

2434-del-1997-description (complete).pdf

2434-del-1997-drawings.pdf

2434-del-1997-form-1.pdf

2434-del-1997-form-13.pdf

2434-del-1997-form-19.pdf

2434-del-1997-form-2.pdf

2434-del-1997-form-3.pdf

2434-del-1997-form-4.pdf

2434-del-1997-form-6.pdf

2434-del-1997-gpa.pdf

2434-del-1997-petition-137.pdf

2434-del-1997-petition-138.pdf

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