Title of Invention	FUEL INJECTION CONTROL APPARATUS FOR ENGINES
Abstract	[Object] To prevent an ignition plug from becoming wet with unburned fuel due to lack of enough rotating power when the engine is started by a kick. [Solving Means] A crankshaft reference position detector 25 determines whether a crankshaft pulser signal corresponds to the top dead center of an intake stroke, then a crankshaft angular valocity detector 26 detects a crankshaft angular velocity. The crankshaft angular velocity is represented by the time of a stage. The time of the stage is input to a comparator 27, which copares it with a reference time Tref. If the crankshaft angular valocity is larger than a preddetermined value, then a duty cycle for a fuel injectror is calculated. If crankshafrt angular velocity is smaller than the predetermined value, then a duty cycle indicative of a fuel injection quantity is set to zero. [Selected Drawing] Fig.1

Title of Invention

FUEL INJECTION CONTROL APPARATUS FOR ENGINES

Abstract

[Object] To prevent an ignition plug from becoming wet with unburned fuel due to lack of enough rotating power when the engine is started by a kick. [Solving Means] A crankshaft reference position detector 25 determines whether a crankshaft pulser signal corresponds to the top dead center of an intake stroke, then a crankshaft angular valocity detector 26 detects a crankshaft angular velocity. The crankshaft angular velocity is represented by the time of a stage. The time of the stage is input to a comparator 27, which copares it with a reference time Tref. If the crankshaft angular valocity is larger than a preddetermined value, then a duty cycle for a fuel injectror is calculated. If crankshafrt angular velocity is smaller than the predetermined value, then a duty cycle indicative of a fuel injection quantity is set to zero. [Selected Drawing] Fig.1

Full Text	FORM 2 THE PATENTS ACT 1970 [39 OF 1970] COMPLETE SPECIFICATION [See Section 10, rule 13] "FUEL INJECTION CONTROL APPARATUS FOR ENGINES" HONDA MOTOR CO., LTD., a corporation of Japan, of 1-1, Minamiaoyama 2-chome, Minato-ku, Tokyo 107-0062, Japan, The following specification particularly describes the nature of the invention and the manner in which it is to be performed:- [Detailed Description of the InvePtion] [0001] [Technical field to which the ipvention] The present invention relates to a fuel injection control apparatus for an engine,and more particularly to a fuel injection control apparatus for an engine which is started by manual power. [0002] [Prior art] FIG. 7 is a block diagram showing an arrangement of main components of a fuel supply system for a motorcycle. Fuel supplied from a fuel tank 12 through a filter 13 and pressurized by a fuel PumP 14 is delivered 2 through a filter 15 to a fuel injector 8. A pressure regulator 16 is provided for keeping constant a fuel pressure in an intake manifold 24. To keep the fuel pressure constant, an excess of fuel that is discharged from the fuel pump 14 is returned through the pressure regulator 16 to the fuel tank 12. [0003] The fuel that is supplied to the intake manifold 24 is mixed with air introduced through an air cleaner 17 and a throttle valve 18. The fuel-air mixture is then drawn into a combustion chamber 2 0 of the engine when an intake valve 19 is opened. When a piston 21 moves beyond a compression top dead center, an ignition plug 22 is igneted to combust the fuel-air mixture. [0004] As the fuel-air mixture is combusted, the piston 21 is reciprocally moved, rotating a crankshaft (not shown). The fuel pump 14 is supplied with a power supply voltage from a battery (not shown) through an ECU 23. A fuel injection quantity to be injected by the injector 8 is determined by the ECU 23 based on various parameters including an engine rotational speed, a throttle opening, etc. [0005] 3 Some fuel injection apparatus for motorcycles having a kick starter inject fuel before a crankshaft reference position is established, in order to improve the ease with which to start the engine. For example, fuel is injected once when a predetermined number of crank pulses each generated per precietermined crankshaft angle are counted, and subsequently fuel is injected at a preset position with respect to a crankshaft reference position. There is known an engine starter wherein before the engine is started, a kick pedal is pressed to actuate a fuel pump for increasing a fuel pressure to inject fuel (Japanese patent laid-open No. Hei 3-18659). [0006] [Problems to be Solved by the Invention] With the kick starter, if a kicking force is small or an initial piston position is far from the compression top dead center, then the piston is unable to move beyond the top dead center in a compression stroke during which the piston undergoes large frictional forces Since fuel injection from the injector is performed in the intake stroke, if the piston does not move beyond compression top dead center, the in:jected fuel remains unburned in the cylinder. Therefore, the ignition plug tends to become wet with the fuel, impairing the ease with which to start the engine. [0007] It is an object of the present invention to provide a fuel injection control apparatus for engines which solves the above problems of the prior art and prevents the ease with which to start the engine from being impaired in a next engine starting process even when the piston is unable to move beyond a compression top dead center due to a kicking failure or the like. [0008] [Means for Solving the Problems] To achieve the above object, there is provided in accordance with a first feature of the present invention a fuel injection control apparatus for an engine which is started by manual power, characterized by means for setting a reference angular velocity for a crankshaft to allow a piston to move beyond a compression top dead center, and control means for effecting fuel injection if a crankshaft angular velocity is equal to or greater than the reference angular velocity in an intake stroke after the start of a cranking process, and disabling fuel injection if the crankshaft angular velocity is lower than the reference angular velocity. [0009] 5 According to a second feature of the present invention, there is also provided a fuel injection control apparatus for an engine which is started by manual power, characterized by a crank pulse sensor for detecting the top dead center of a piston, means for determining whether the detected top dead center is a top dead center in an intake stroke or not, means for detecting a crankshaft angular velocity based on the rotational time of a predetermined crankshaft angle, means for setting a reference angular velocity for a crankshaft to allow the piston to move beyond a compression top dead center, angular velocity determining means for determining whether or not the crankshaft angular velocity is equal to or greater than the reference angular velocity when the detected top dead center is the top dead center in the intake stroke, and control means for effecting fuel injection if the crankshaft angular velocity is equal to or greater than the reference angular velocity as determined by the angular velocity determining means, and disabling fuel injection if the crankshaft angular velocity is lower than the reference angular velocity as determined by the angular velocity determining means. [0010] According to the first and second features, when the engine is cranked by manual power, i.e., when the engine is started by a kick, no fuel is injected unless the crankshaft angular velocity exceeds the reference angular velocity which allows the piston to move beyond the compression top dead center. Therefore, no wasteful fuel is injected upon a kicking failure or the like, and an ignition plug is prevented from becoming wet with unburned fuel. [0011] According to a third feature of the present invention, the control means includes fuel injection quantity calculating means and actuating means for actuating fuel injecting means with a duty cycle depending on a fuel injection quantity calculated by the fuel injection quantity calculating means, the arrangement being such that the duty cycle is set to zero to substantially disable fuel injection if the crankshaft angular velocity is lower than the reference angular velocity as determined by the angular velocity determining means. [0012] According to the third feature, an actuator for a fuel injector is controlled in the same manner if the 7 crankshaft angular velocity is equal to or greater than the reference angular velocity or if the crankshaft angular velocity is smaller than the reference angular velocity. Fuel injection is substantially disabled simply by setting the fuel injection quantity to zero. [0013] According to a fourth feature of the present invention, the fuel injection control apparatus is provided for use in an engine having a fuel injector and a fuel supply pump which are actuatable by a common power supply. [0014] According to the fourth feature, the electric power that would be consumed for wasteful fuel injection can be saved, and the saved electric power can be employed to actuate the fuel pump. Even if the engine fails to be started by a first cranking process, sufficient electric power can be supplied to the fuel pump to achieve a high fuel pressure in a next cranking process. [0015] [Mode for Carrying out the Invention] A preferred embodiment of the present invention will be described in detail below with reference to the 8 [Brief Description of the Drawings] [FIG. 1] FiG. 1 iS a block diagram showing main functions of a fuel injection control apparatus according to an embodiment of the present invention; [FIG. 2J FIG. 2 is a diagram of an essential arrangement of a motorcycle including the fuel injection control apparatus according to the embodiment of the present invention; [FIG. 3] FIG. 3 is a timing chart (1) of a fuel injection control pxocess of the fuel injection control apparatus according to the embodiment of the present invention; [FIG. 4] FIG. 4 is a timing chart (2) of the fuel injection control process of the fuel injection control apparatus according to the embodiment of the present invention; [FIG-. 5)- FIG. 5 is a flowchart of a fuel injection determining process; [FIG., 6] FIG. 6 is a flowchart of a fuel injection process; and [FIG. 7] FIG. 7 is a diagram showing a fuel supply system for an engine by way of example. FIG. 2 is a block diagram of an essential arrangement of a motorcycle with a kick starter including a fuel injection control apparatus according to an embodiment of the present invention. Although not shown in FIG. 2, the motorcycle includes a fuel supply system having the same hardware arrangement as the one shown in FIG. 7. [0016] A pedal {kick pedal) 2 for starting an engine with a kick is coupled to a crankshaft 1 of the engine by a kick gear and a ratchet {both not shown). A disk 3 having a number of teeth {reluctor tabs) on its outer circumferential edge is connected to the crankshaft 1. The reluctor tabs are disposed at predetermined angular intervals {e.g., 30 degrees). [0017] A rotational speed sensor 4 comprises a photointerruptor, for example, and detects the reluctor tabs and outputs a crankshaft angle signal 5 to a Fi-ECU (fuel injection control apparatus) 6. The crankshaft angle signal 5 is a signal representing a predetermined crankshaft angle depending on the angular intervals between the reluctor tabs. Based on the crankshaft angle signal 5, the Fi-ECU 6 calculates the rotational speed of 10 the engine. [0018] A magnet is mounted on (e.g,, embedded in) the diek 3 at a predetermined circumferential position coirresponding to the top dead center. A crankshaft pulser sensor 7 which comprises a magnetic pickup sensor detects the magnet, and outputs a crankshaft pulser signal 9 to the Fi-ECU 6. An injector 8 is actuated according to a drive signal 10 that represents an open-valve duty cycle depending on a fuel injection quantity that is determined by the Fi-ECU 6. Operation of the Fi-ECU 6 will be described in further detail below. [0019] FIGS. 3 and 4 are timing charts of a fuel injection control process. In the fuel injection control process, a crankshaft angle of 30 degrees is defined as one stage, and one engine revolution is defined as 360 degrees in 12 stages. Therefore, one engine cycle which comprises intake, compression, combustion, and exhaust strokes is defined as 720 degrees in 24 stages. The number of pulses of the crankshaft angle signal 5 represents a stage number. One crankshaft pulser signal 9 is output each time the engine makes one revolution. [0020] 11 In FIG. 3, when a kick is started using a kick pedal 2 at timing tl, a generator coupled to the crankshaft 1 generates electric energy, increasing the power supply voltage for the Fi-ECU 6. At timing t2, the Fi-ECU 6 starts being reset and initialized. When the resetting and initialization of the Fi-ECU 6 is completed at timing t3, the fuel pump (PEP) 14 is actuated. A crankshaft pulser signal 9 is detected at timing t4, and the pulse duration (time) of a state immediately thereafter, i.e., a 17th stage, is detected. At timing t5, it is determined whether fuel injection is to be effected or not based on the pulse duration of the 17th stage. If it is determined that fuel injection is to be effected, then a fuel injection quantity is calculated, and the injector (INJ) 8 is actuated at timing t6. If it is determined that fuel injection is not to be effected, then a fuel injection quantity is not calculated, and fuel is not injected. [0021] FIG. 5 is a flowchart of a fuel injection determining process. The fuel injection determining process is performed each time a crankshaft pulser signal is detected. In step SI, it is determined whether a crankshaft reference position is determined or not, i.e., 12 whether a crankshaft pulser signal 9 in the intake stroke, among crankshaft pulser signals 9 in the combustion and intake strokes, is detected or not, based on, for example, an intake pipe negative pressure Pb at the time the crankshaft pulser signal 9 is detected. In step S2, it is determined whether the present stage is an 18th stage or not. If the crankshaft reference position is determined, then since a stage immediately thereafter is determined to be the 17th stage, the stage next to that stage is the 18th stage. [0022] If the answer to step S2 is affirmative, then it is determined in step S3 whether the pulse duration (time) T17 of the crankshaft angle signal corresponding to the 17th stage is longer than a reference time Tref for determining a fuel supply cutoff or not. The reference time Tref represents a reference value for determining whether the crankshaft is rotating at a speed sufficient for the piston to move beyond the compression top dead center or not. [0023] If the pulse duration T17 of the crankshaft angle signal is longer than the reference time Tref, then it is determined that the crankshaft angular velocity is small 13 (the engine rotational speed is low), and control goes to step S4. If the pulse duration T17 of the crankshaft angle signal is shorter than the reference time Tref, then it is determined that the crankshaft angular velocity is large (the engine rotational speed is high), and that the piston can move beyond the compression top dead center, and control goes to step S5. In step S4, a fuel injection disabling flag Ffc is set (= 1). In step S5; the fuel injection disabling flag Ffc is cleared {= 0). In step S6, a fuel injection routine for calculating a fuel injection quantity and effecting fuel injection based on the calculated fuel injection quantity is performed. [0024] FIG. 6 is a detailed flowchart of the fuel injection routine (step S6). In step S61, the fuel injection disabling flag Ffc is determined. If the fuel injection disabling flag Ffc is "0", then control goes to step S62 to calculate a fuel injection quantity. The fuel injection quantity is calculated base on engine parameters including a throttle opening, an engine rotational speed, an engine coolant temperature, etc., and is expressed by an open-valve duty cycle for the injector 8. In step S63, the injector 8 is actuated 14 according to the calculated fuel injection quantity, injecting fuel. If the fuel injection disabling flag Ffc is "1", then control goes to step S64. In step S6, the open-valve duty cycle for the injector 8 is set to "0", after which control goes to step S63. [0025] FIG. 1 is a block diagram showing main functions of the Fi-ECU 6. A crankshaft reference position detector 25 determines an engine stroke in response to a crankshaft pulser signal. An engine stroke can be determined based on whether the intake pipe negative pressure Pb corresponds to a negative pressure in the intake stroke, for example, because the intake pipe negative pressure Pb in the intake stroke is greater than in the other engine strokes. If a crankshaft pulser signal is detected in the intake stroke, then a crankshaft angular velocity detector 26 detects a crankshaft angular velocity based on the crankshaft angle signal. The crankshaft angular velocity is represented by the pulse duration of the crankshaft angle signal, i.e., the time of one stage immediately after the crankshaft reference position has been determined. If the crankshaft angular velocity is large, then the time of one stage is short. The time T17 of one stage 15 representing the crankshaft angular velocity is input to a comparator 27, which compares the time T17 with the reference time Tref. The compared result is input to a fuel injection quantity calculator 28. If it is determined that the crankshaft angular velocity is larger than a predetermined value, then a fuel injection quantity, or specifically an open-valve duty cycle, is calculated according to the engine parameters. If it is determined that the crankshaft angular velocity is smaller than the predetermined value, then a fuel injection quantity (duty cycle) is set to zero. The fuel injection quantity or open-valve duty cycle which is calculated or set to zero is input to an inj ector actuator 29. The injector actuator 29 actuates the injector 8 according to the input open-valve duty cycle. [0026] In the above embodiment, the fuel injection quantity is set to zero to disable fuel injection. However, the fuel injection quantity may not be set to zero in its entirety, but may be reduced to a value which essentially disables fuel injection. [0027] The embodiment in which the present invention is applied to the fuel injection control apparatus for 16 motorcycles has been described above. However, the present invention is not limited to the above embodiment, but is also applicable to an engine-driven generator associated with an engine other than those for motorcycles, e.g., an engine that is started by manual power. [0028] [Effects of the Invention] With the invention according to claims 1 through 4, when it is determined that a crankshaft angular velocity sufficient to allow a piston to move beyond the compression top dead center is not achieved by manual cranking, fuel injection is disabled. Therefore, an ignition plug is prevented from becoming wet with fuel, and the ease with which to start the engine is increased. [0029] With the invention according to claim 3, in particular, since the fuel injector can be controlled by the same control function if the fuel supply is performed or if the fuel supply is disabled, the control process is simple. [0030] With the invention according to claim 4, wasteful electric energy which would be consumed to inject fuel is 17 saved, and in an engine starting cycle next to an engine starting failure, a sufficient fuel pressure is produced for starting the engine reliably. [Description of reference Numerals] 1...crankshaft, 2...kick pedal, 4...rotational speed sensor, 5...crankshaft angle signal, 6...Fi-ECU, 7...crankshaft pulser sensor, 8...injector, 9...crankshaft pulser signal, 10...injector drive signal, 12...fuel tank, 14... fuel pump, 25...crankshaft reference position, 26...crankshaft angular velocity detector, 27...comparator, 28...fuel injection quantity calculator, 29...injector actuator. i8 [What is Claimed is] [Claim 1] A fuel injection control apparatus for an engine which is started by manual power, characterized by: means for setting a reference angular velocity for a crankshaft to allow a piston to move beyond a compression top dead center; and control means for effecting fuel injection if a crankshaft angular velocity is equal to or greater than said reference angular velocity in an intake stroke after the start of a cranking process, and disabling fuel injection if said crankshaft angular velocity is lower than said reference angular velocity. [Claim 2] A fuel injection control apparatus for an engine which is started by manual power, characterized by: a crank pulse sensor for detecting the top dead center of a piston; means for determining whether the detected top dead center is a top dead center in an intake stroke or not; 19 means for detecting a crankshaft angular velocity based on the rotational time of a predetermined crankshaft angle; means for setting a reference angular velocity for a crankshaft to allow the piston to move beyond a compression top dead center; angular velocity determining means for determining whether or not said crankshaft angular velocity is equal to or greater than said reference a.ngular velocity when said, detected top dead center is the top dead center in the intake stroke; and control means for effecting fuel injection if said crankshaft angular velocity is equal to or greater than said reference angular velocity as determined by said angular velocity determining means, and disabling fuel injection if said crankshaft angular velocity is lower than said reference angular velocity as determined by said angular velocity determining means. [Claim 3] A fuel injection control apparatus according to claim 1 or 2, characterized in that: said control means comprises fuel injection quantity calculating means and actuating means for actuating fuel injecting means with a duty cycle depending on a fuel injection quantity calculated by said 20 fuel injection quantity calculating means; the arrangement being such that said duty cycle is set to zero to substantially disable fuel injection if said crankshaft angular velocity is lower than said reference angular velocity as determined by said angular velocity determining means. (claims 4) A fuel injection control apparatus according to any one of claims 1 through 3 for use in an engine having a fuel injector and a fuel supply pump which are actuatable by a common power supply. 21 22 5. A fuel injection control apparatus for an engine substantially as hereiribefore described with reference to the accompanying drawings. Dated this 8th day of October, 2003. (B. KOMBI) OF REMFRY & SAGAR ATTORNEY FOR THE APPLICANTS.

Full Text

FORM 2 THE PATENTS ACT 1970 [39 OF 1970]
COMPLETE SPECIFICATION
[See Section 10, rule 13]
"FUEL INJECTION CONTROL APPARATUS FOR ENGINES"
HONDA MOTOR CO., LTD., a corporation of Japan, of 1-1, Minamiaoyama 2-chome, Minato-ku, Tokyo 107-0062, Japan,
The following specification particularly describes the nature of the invention and the manner in which it is to be performed:-

[Detailed Description of the InvePtion] [0001] [Technical field to which the ipvention]
The present invention relates to a fuel injection control apparatus for an engine,and more particularly to a fuel injection control apparatus for an engine which is started by manual power. [0002] [Prior art]
FIG. 7 is a block diagram showing an arrangement of main components of a fuel supply system for a motorcycle. Fuel supplied from a fuel tank 12 through a filter 13 and pressurized by a fuel PumP 14 is delivered
2

through a filter 15 to a fuel injector 8. A pressure regulator 16 is provided for keeping constant a fuel pressure in an intake manifold 24. To keep the fuel pressure constant, an excess of fuel that is discharged from the fuel pump 14 is returned through the pressure regulator 16 to the fuel tank 12.
[0003]
The fuel that is supplied to the intake manifold 24 is mixed with air introduced through an air cleaner 17 and a throttle valve 18. The fuel-air mixture is then drawn into a combustion chamber 2 0 of the engine when an intake valve 19 is opened. When a piston 21 moves beyond a compression top dead center, an ignition plug 22 is igneted to combust the fuel-air mixture.
[0004]
As the fuel-air mixture is combusted, the piston 21 is reciprocally moved, rotating a crankshaft (not shown). The fuel pump 14 is supplied with a power supply voltage from a battery (not shown) through an ECU 23. A fuel injection quantity to be injected by the injector 8 is determined by the ECU 23 based on various parameters including an engine rotational speed, a throttle opening, etc.
[0005]
3

Some fuel injection apparatus for motorcycles having a kick starter inject fuel before a crankshaft reference position is established, in order to improve the ease with which to start the engine. For example, fuel is injected once when a predetermined number of crank pulses each generated per precietermined crankshaft angle are counted, and subsequently fuel is injected at a preset position with respect to a crankshaft reference position. There is known an engine starter wherein before the engine is started, a kick pedal is pressed to actuate a fuel pump for increasing a fuel pressure to inject fuel (Japanese patent laid-open No. Hei 3-18659).
[0006]
[Problems to be Solved by the Invention]
With the kick starter, if a kicking force is small or an initial piston position is far from the compression top dead center, then the piston is unable to move beyond the top dead center in a compression stroke during which the piston undergoes large frictional forces Since fuel injection from the injector is performed in the intake stroke, if the piston does not move beyond compression top dead center, the in:jected fuel remains unburned in the cylinder. Therefore, the ignition plug tends to become wet with the fuel, impairing the ease

with which to start the engine. [0007]
It is an object of the present invention to provide a fuel injection control apparatus for engines which solves the above problems of the prior art and prevents the ease with which to start the engine from being impaired in a next engine starting process even when the piston is unable to move beyond a compression top dead center due to a kicking failure or the like.
[0008]
[Means for Solving the Problems]
To achieve the above object, there is provided in accordance with a first feature of the present invention a fuel injection control apparatus for an engine which is started by manual power, characterized by means for setting a reference angular velocity for a crankshaft to allow a piston to move beyond a compression top dead center, and control means for effecting fuel injection if a crankshaft angular velocity is equal to or greater than the reference angular velocity in an intake stroke after the start of a cranking process, and disabling fuel injection if the crankshaft angular velocity is lower than the reference angular velocity. [0009]
5

According to a second feature of the present invention, there is also provided a fuel injection control apparatus for an engine which is started by manual power, characterized by a crank pulse sensor for detecting the top dead center of a piston, means for determining whether the detected top dead center is a top dead center in an intake stroke or not, means for detecting a crankshaft angular velocity based on the rotational time of a predetermined crankshaft angle, means for setting a reference angular velocity for a crankshaft to allow the piston to move beyond a compression top dead center, angular velocity determining means for determining whether or not the crankshaft angular velocity is equal to or greater than the reference angular velocity when the detected top dead center is the top dead center in the intake stroke, and control means for effecting fuel injection if the crankshaft angular velocity is equal to or greater than the reference angular velocity as determined by the angular velocity determining means, and disabling fuel injection if the crankshaft angular velocity is lower than the reference angular velocity as determined by the angular velocity determining means. [0010]

According to the first and second features, when the engine is cranked by manual power, i.e., when the engine is started by a kick, no fuel is injected unless the crankshaft angular velocity exceeds the reference angular velocity which allows the piston to move beyond the compression top dead center. Therefore, no wasteful fuel is injected upon a kicking failure or the like, and an ignition plug is prevented from becoming wet with unburned fuel.
[0011]
According to a third feature of the present invention, the control means includes fuel injection quantity calculating means and actuating means for actuating fuel injecting means with a duty cycle depending on a fuel injection quantity calculated by the fuel injection quantity calculating means, the arrangement being such that the duty cycle is set to zero to substantially disable fuel injection if the crankshaft angular velocity is lower than the reference angular velocity as determined by the angular velocity determining means.
[0012]
According to the third feature, an actuator for a fuel injector is controlled in the same manner if the

7

crankshaft angular velocity is equal to or greater than the reference angular velocity or if the crankshaft angular velocity is smaller than the reference angular velocity. Fuel injection is substantially disabled simply by setting the fuel injection quantity to zero. [0013]
According to a fourth feature of the present invention, the fuel injection control apparatus is provided for use in an engine having a fuel injector and a fuel supply pump which are actuatable by a common power supply. [0014]
According to the fourth feature, the electric power that would be consumed for wasteful fuel injection can be saved, and the saved electric power can be employed to actuate the fuel pump. Even if the engine fails to be started by a first cranking process, sufficient electric power can be supplied to the fuel pump to achieve a high fuel pressure in a next cranking process. [0015] [Mode for Carrying out the Invention]
A preferred embodiment of the present invention will be described in detail below with reference to the
8

[Brief Description of the Drawings] [FIG. 1]
FiG. 1 iS a block diagram showing main functions of a fuel injection control apparatus according to an embodiment of the present invention; [FIG. 2J
FIG. 2 is a diagram of an essential arrangement of a motorcycle including the fuel injection control apparatus according to the embodiment of the present invention; [FIG. 3]
FIG. 3 is a timing chart (1) of a fuel injection control pxocess of the fuel injection control apparatus according to the embodiment of the present invention; [FIG. 4]
FIG. 4 is a timing chart (2) of the fuel injection control process of the fuel injection control apparatus according to the embodiment of the present invention; [FIG-. 5)-
FIG. 5 is a flowchart of a fuel injection determining process;
[FIG., 6]
FIG. 6 is a flowchart of a fuel injection
process; and
[FIG. 7]
FIG. 7 is a diagram showing a fuel supply system
for an engine by way of example.

FIG. 2 is a block diagram of an essential arrangement of a motorcycle with a kick starter including a fuel injection control apparatus according to an embodiment of the present invention. Although not shown in FIG. 2, the motorcycle includes a fuel supply system having the same hardware arrangement as the one shown in FIG. 7.
[0016]
A pedal {kick pedal) 2 for starting an engine with a kick is coupled to a crankshaft 1 of the engine by a kick gear and a ratchet {both not shown). A disk 3 having a number of teeth {reluctor tabs) on its outer circumferential edge is connected to the crankshaft 1. The reluctor tabs are disposed at predetermined angular intervals {e.g., 30 degrees).
[0017]
A rotational speed sensor 4 comprises a photointerruptor, for example, and detects the reluctor tabs and outputs a crankshaft angle signal 5 to a Fi-ECU (fuel injection control apparatus) 6. The crankshaft angle signal 5 is a signal representing a predetermined crankshaft angle depending on the angular intervals between the reluctor tabs. Based on the crankshaft angle signal 5, the Fi-ECU 6 calculates the rotational speed of
10

the engine. [0018]
A magnet is mounted on (e.g,, embedded in) the diek 3 at a predetermined circumferential position coirresponding to the top dead center. A crankshaft pulser sensor 7 which comprises a magnetic pickup sensor detects the magnet, and outputs a crankshaft pulser signal 9 to the Fi-ECU 6. An injector 8 is actuated according to a drive signal 10 that represents an open-valve duty cycle depending on a fuel injection quantity that is determined by the Fi-ECU 6. Operation of the Fi-ECU 6 will be described in further detail below. [0019]
FIGS. 3 and 4 are timing charts of a fuel injection control process. In the fuel injection control process, a crankshaft angle of 30 degrees is defined as one stage, and one engine revolution is defined as 360 degrees in 12 stages. Therefore, one engine cycle which comprises intake, compression, combustion, and exhaust strokes is defined as 720 degrees in 24 stages. The number of pulses of the crankshaft angle signal 5 represents a stage number. One crankshaft pulser signal 9 is output each time the engine makes one revolution. [0020]
11

In FIG. 3, when a kick is started using a kick pedal 2 at timing tl, a generator coupled to the crankshaft 1 generates electric energy, increasing the power supply voltage for the Fi-ECU 6. At timing t2, the Fi-ECU 6 starts being reset and initialized. When the resetting and initialization of the Fi-ECU 6 is completed at timing t3, the fuel pump (PEP) 14 is actuated. A crankshaft pulser signal 9 is detected at timing t4, and the pulse duration (time) of a state immediately thereafter, i.e., a 17th stage, is detected. At timing t5, it is determined whether fuel injection is to be effected or not based on the pulse duration of the 17th stage. If it is determined that fuel injection is to be effected, then a fuel injection quantity is calculated, and the injector (INJ) 8 is actuated at timing t6. If it is determined that fuel injection is not to be effected, then a fuel injection quantity is not calculated, and fuel is not injected. [0021]
FIG. 5 is a flowchart of a fuel injection determining process. The fuel injection determining process is performed each time a crankshaft pulser signal is detected. In step SI, it is determined whether a crankshaft reference position is determined or not, i.e.,
12

whether a crankshaft pulser signal 9 in the intake stroke, among crankshaft pulser signals 9 in the combustion and intake strokes, is detected or not, based on, for example, an intake pipe negative pressure Pb at the time the crankshaft pulser signal 9 is detected. In step S2, it is determined whether the present stage is an 18th stage or not. If the crankshaft reference position is determined, then since a stage immediately thereafter is determined to be the 17th stage, the stage next to that stage is the 18th stage.
[0022]
If the answer to step S2 is affirmative, then it is determined in step S3 whether the pulse duration (time) T17 of the crankshaft angle signal corresponding to the 17th stage is longer than a reference time Tref for determining a fuel supply cutoff or not. The reference time Tref represents a reference value for determining whether the crankshaft is rotating at a speed sufficient for the piston to move beyond the compression top dead center or not.
[0023]
If the pulse duration T17 of the crankshaft angle signal is longer than the reference time Tref, then it is determined that the crankshaft angular velocity is small
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(the engine rotational speed is low), and control goes to step S4. If the pulse duration T17 of the crankshaft angle signal is shorter than the reference time Tref, then it is determined that the crankshaft angular velocity is large (the engine rotational speed is high), and that the piston can move beyond the compression top dead center, and control goes to step S5. In step S4, a fuel injection disabling flag Ffc is set (= 1). In step S5; the fuel injection disabling flag Ffc is cleared {= 0). In step S6, a fuel injection routine for calculating a fuel injection quantity and effecting fuel injection based on the calculated fuel injection quantity is performed. [0024]
FIG. 6 is a detailed flowchart of the fuel injection routine (step S6). In step S61, the fuel injection disabling flag Ffc is determined. If the fuel injection disabling flag Ffc is "0", then control goes to step S62 to calculate a fuel injection quantity. The fuel injection quantity is calculated base on engine parameters including a throttle opening, an engine rotational speed, an engine coolant temperature, etc., and is expressed by an open-valve duty cycle for the injector 8. In step S63, the injector 8 is actuated
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according to the calculated fuel injection quantity, injecting fuel. If the fuel injection disabling flag Ffc is "1", then control goes to step S64. In step S6, the open-valve duty cycle for the injector 8 is set to "0", after which control goes to step S63. [0025]
FIG. 1 is a block diagram showing main functions of the Fi-ECU 6. A crankshaft reference position detector 25 determines an engine stroke in response to a crankshaft pulser signal. An engine stroke can be determined based on whether the intake pipe negative pressure Pb corresponds to a negative pressure in the intake stroke, for example, because the intake pipe negative pressure Pb in the intake stroke is greater than in the other engine strokes. If a crankshaft pulser signal is detected in the intake stroke, then a crankshaft angular velocity detector 26 detects a crankshaft angular velocity based on the crankshaft angle signal. The crankshaft angular velocity is represented by the pulse duration of the crankshaft angle signal, i.e., the time of one stage immediately after the crankshaft reference position has been determined. If the crankshaft angular velocity is large, then the time of one stage is short. The time T17 of one stage
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representing the crankshaft angular velocity is input to a comparator 27, which compares the time T17 with the reference time Tref. The compared result is input to a fuel injection quantity calculator 28. If it is determined that the crankshaft angular velocity is larger than a predetermined value, then a fuel injection quantity, or specifically an open-valve duty cycle, is calculated according to the engine parameters. If it is determined that the crankshaft angular velocity is smaller than the predetermined value, then a fuel injection quantity (duty cycle) is set to zero. The fuel injection quantity or open-valve duty cycle which is calculated or set to zero is input to an inj ector actuator 29. The injector actuator 29 actuates the injector 8 according to the input open-valve duty cycle. [0026]
In the above embodiment, the fuel injection quantity is set to zero to disable fuel injection. However, the fuel injection quantity may not be set to zero in its entirety, but may be reduced to a value which essentially disables fuel injection.
[0027]
The embodiment in which the present invention is applied to the fuel injection control apparatus for
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motorcycles has been described above. However, the present invention is not limited to the above embodiment, but is also applicable to an engine-driven generator associated with an engine other than those for motorcycles, e.g., an engine that is started by manual power.
[0028]
[Effects of the Invention]
With the invention according to claims 1 through 4, when it is determined that a crankshaft angular velocity sufficient to allow a piston to move beyond the compression top dead center is not achieved by manual cranking, fuel injection is disabled. Therefore, an ignition plug is prevented from becoming wet with fuel, and the ease with which to start the engine is increased.
[0029]
With the invention according to claim 3, in particular, since the fuel injector can be controlled by the same control function if the fuel supply is performed or if the fuel supply is disabled, the control process is simple.
[0030]
With the invention according to claim 4, wasteful electric energy which would be consumed to inject fuel is
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saved, and in an engine starting cycle next to an engine starting failure, a sufficient fuel pressure is produced for starting the engine reliably.
[Description of reference Numerals]
1...crankshaft, 2...kick pedal, 4...rotational speed sensor, 5...crankshaft angle signal, 6...Fi-ECU, 7...crankshaft pulser sensor, 8...injector, 9...crankshaft pulser signal, 10...injector drive signal, 12...fuel tank, 14... fuel pump, 25...crankshaft reference position, 26...crankshaft angular velocity detector, 27...comparator, 28...fuel injection quantity calculator, 29...injector actuator.
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[What is Claimed is]
[Claim 1] A fuel injection control apparatus for an engine which is started by manual power, characterized by:
means for setting a reference angular velocity for a crankshaft to allow a piston to move beyond a compression top dead center; and
control means for effecting fuel injection if a crankshaft angular velocity is equal to or greater than said reference angular velocity in an intake stroke after the start of a cranking process, and disabling fuel injection if said crankshaft angular velocity is lower than said reference angular velocity.
[Claim 2] A fuel injection control apparatus for an engine which is started by manual power, characterized
by:
a crank pulse sensor for detecting the top dead
center of a piston;
means for determining whether the detected top dead center is a top dead center in an intake stroke or not;
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means for detecting a crankshaft angular velocity based on the rotational time of a predetermined crankshaft angle;
means for setting a reference angular velocity for a crankshaft to allow the piston to move beyond a compression top dead center;
angular velocity determining means for determining whether or not said crankshaft angular velocity is equal to or greater than said reference a.ngular velocity when said, detected top dead center is the top dead center in the intake stroke; and
control means for effecting fuel injection if said crankshaft angular velocity is equal to or greater than said reference angular velocity as determined by said angular velocity determining means, and disabling fuel injection if said crankshaft angular velocity is lower than said reference angular velocity as determined by said angular velocity determining means.
[Claim 3] A fuel injection control apparatus according to claim 1 or 2, characterized in that:
said control means comprises fuel injection quantity calculating means and actuating means for actuating fuel injecting means with a duty cycle depending on a fuel injection quantity calculated by said
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fuel injection quantity calculating means;
the arrangement being such that said duty cycle is set to zero to substantially disable fuel injection if said crankshaft angular velocity is lower than said reference angular velocity as determined by said angular velocity determining means.
(claims 4) A fuel injection control apparatus according to any one of claims 1 through 3 for use in an engine having a fuel injector and a fuel supply pump which are actuatable by a common power supply.
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5. A fuel injection control apparatus for an engine substantially as hereiribefore described with reference to the accompanying drawings.
Dated this 8th day of October, 2003.

(B. KOMBI)
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANTS.

FUEL INJECTION CONTROL APPARATUS FOR ENGINES

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