JP2014070616A - Engine starting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine starting device with further improved startability than conventional ones.SOLUTION: An engine starting device comprises a motor generator (24), and a decompression device (28). The motor generator is coupled with a crank shaft (22) in an engine (2) so that transmission of a rotary driving force cannot be shut down. The decompression device performs decompression for emitting air in a cylinder (20) during a compression stroke to outside of the cylinder. The decompression device performs decompression during an initial compression stroke, so that the air in the cylinder is emitted to such an extent that initial explosion is not possible, even if fuel is sucked in the cylinder experiencing the initial compression stroke. Also, the decompression device completes decompression during a target initial explosion compression stroke, so that the air in the cylinder is not emitted to such an extent that initial explosion is not possible.

Description

  The present invention relates to an engine starting device.

  Conventionally, various attempts have been made to improve engine startability. For example, the engine starting device disclosed in Japanese Patent Application Laid-Open No. 2002-332938 is configured to prepare for the next engine start by reversing the crankshaft to a predetermined position after the engine is stopped. In addition, this apparatus is configured to be able to execute decompression (forcing the exhaust valve to be opened at the time of engine start to suppress an increase in in-cylinder pressure during the compression stroke). According to such a configuration, good startability is ensured even when a small starter motor having a small maximum generated torque is employed.

JP 2002-332938 A

  In the conventional configuration described above, the reverse rotation torque applied to the crankshaft may be transmitted to the drive wheels during reverse rotation of the crankshaft (hereinafter referred to as “swing back”) prior to engine start. In this case, there is a concern that an occupant of the vehicle (especially a motorcycle) may feel uncomfortable.

  In recent years, so-called idling stops have been adopted in motorcycles. In a motorcycle that employs an idling stop system, a so-called ACG starter may be used in order to realize smooth engine start and start from an idling stop state. This ACG starter serves as both a starter motor and an AC generator (AC generator). In such a motorcycle equipped with an ACG starter, the torque required for the ACG starter at the start of the engine is possible in order to further improve fuel efficiency by reducing the vehicle weight and to apply to a larger displacement engine. There is a demand to reduce as much as possible.

  The present invention has been made in view of the circumstances exemplified above, and an object of the present invention is to provide an engine starter having further improved startability than the conventional one.

  The engine starter of the present invention is configured to start an engine (this engine is mounted on a vehicle and has at least one cylinder). The engine starter includes a motor generator and a decompression device.

  The motor generator is coupled to the crankshaft of the engine so that the transmission of the rotational driving force cannot be cut off. The motor generator functions as a generator by the rotational driving force generated at the crankshaft after the engine is started, and at the time of starting the engine, the crankshaft is rotated in the same direction as after the engine is started. By doing so, it is also configured to function as a starting motor.

  The decompression device is configured to perform decompression (releasing air in the cylinder during the compression stroke to the outside of the cylinder) when the engine is started.

  A feature of the present invention lies in that the decompression device is configured to operate as follows: In an initial compression stroke (a compression stroke that first occurs after starting the motor generator for starting the engine) Thus, the decompression is performed so that the air in the cylinder is released to the extent that the first explosion cannot be generated even if the fuel is sucked into the cylinder that reaches the initial compression stroke. On the other hand, during the target initial explosion compression stroke (the compression stroke that reaches a predetermined number of times after the initial compression stroke), the decompression is terminated so that the air in the cylinder is not released to the extent that the first explosion cannot be generated. To do. Here, the “first explosion” means that after the motor generator for starting the engine is started, an explosion (fuel combustion) that can form an effective expansion stroke is first performed in the cylinder. It means to occur.

  In this configuration, when starting the engine, the crankshaft in the engine is rotationally driven by the motor generator in the same direction as after the engine is started. Further, when the decompression is performed by the decompression device, air in the cylinder is released in the initial compression stroke, and an increase in the internal pressure of the cylinder is suppressed. At this time, the degree of suppression of the increase in internal pressure of the cylinder is such that even if fuel is sucked into the cylinder, the first explosion cannot be generated. Thereby, cranking torque decreases favorably. Therefore, it becomes possible for the piston to successfully overcome the initial compression stroke (that is, the compression top dead center that is first met at the time of starting).

  Thereafter, in the compression stroke that reaches a predetermined number of times after the initial compression stroke, the crankshaft is rotated to such an extent that the initial explosion can be reached in the compression stroke while overcoming the compression stroke without performing decompression. It is expected that the inertial force due to the above, that is, the angular speed (rotational speed) of the crankshaft is increased. Therefore, the decompression device reaches the target initial explosion compression stroke (the compression stroke that reaches a predetermined number of times after the initial compression stroke: in other words, the compression stroke that first attempts ignition combustion after the start of cranking by the motor generator). The decompression is terminated so that the air in the cylinder is not released to the extent that the first explosion cannot occur. Thereby, a quick start is realizable.

  As described above, according to the engine starter of the present invention having the above-described configuration, the startability of the engine is further improved as compared with the related art. Specifically, for example, the engine can be started satisfactorily regardless of the position of the piston at the start of cranking by the motor generator without performing the swing back as described above at the time of starting. Therefore, a smooth start without giving a sense of incongruity to a vehicle (especially a motorcycle) occupant can be realized.

1 is a schematic configuration diagram of a vehicle to which an embodiment of the present invention is applied. The figure which shows the internal structure of the engine shown by FIG. The schematic block diagram of the system for controlling the driving | operation of the engine shown by FIG. The graph which shows the mode of the decompression operation | movement by the decompression apparatus shown by FIG. FIG. 6 is a time chart when the engine is started in the system shown in FIG. 5. FIG. The schematic block diagram which shows the modification of the system shown by FIG.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. In addition, since a modification will prevent understanding of the description of a consistent embodiment if it is inserted during the description of the said embodiment, it is described collectively at the end.

<Configuration>
Referring to FIG. 1, a motorcycle 1 corresponding to the vehicle of the present invention is provided with a front wheel 1a and a rear wheel 1b which is a drive wheel. The motorcycle 1 includes an engine 2, a power transmission mechanism 3, and an engine control device 4. The engine control device 4 is provided under the seat 5.

  Referring to FIGS. 2 and 3, in this embodiment, the engine 2 is configured as a so-called “single cylinder engine” having one cylinder 20. A piston 21 is accommodated in the cylinder 20 so as to be capable of reciprocating along the central axis of the cylinder 20. The piston 21 is connected to the crankshaft 22 via a connecting rod 23.

  The motor generator 24 is a so-called ACG starter that serves as both a starter motor and an AC generator (alternator). The motor generator 24 is coupled to the crankshaft 22 so that the transmission of the rotational driving force cannot be cut off. That is, the rotor 24a of the motor generator 24 is directly connected to the crankshaft 22 (fixed to one end of the crankshaft 22 so that the rotational driving force is always transmitted between the motor generator 24 and the crankshaft 22. ) The motor generator 24 functions as a generator by the rotational driving force generated in the crankshaft 22 after the engine 2 is started, and rotates the crankshaft 22 in the same direction as after the engine 2 is started when the engine 2 is started. It is configured to function as a starting motor when driven. Specifically, in the present embodiment, the motor generator 24 has a three-phase brushless motor structure.

  Referring to FIG. 3, the intake system 25 is configured to supply a fuel mixture into the cylinder 20. Specifically, the intake pipe 25a is connected to the cylinder 20 via the intake port 25b. An air cleaner 25c is attached to the most upstream portion of the intake pipe 25a in the intake air flow direction. A throttle valve 25d is provided downstream of the air cleaner 25c in the intake air flow direction. The throttle valve 25d is configured to be able to adjust the passage cross-sectional area (flow passage area) in the intake pipe 25a according to the opening. The throttle valve 25d is connected to a throttle valve actuator (not shown) so that the opening degree is electrically controlled by the engine control device 4.

  An injector 25e is provided downstream of the throttle valve 25d in the intake air flow direction. The injector 25e is configured and arranged to inject fuel toward the intake port 25b by being electromagnetically driven. Further, the engine 2 is provided with an intake valve 25f for opening and closing an opening of the intake port 25b (a communication port with the cylinder 20). The intake valve 25f is controlled to be opened and closed by an intake valve mechanism 25g. The intake valve mechanism 25g includes an intake camshaft (not shown) and the like, and appropriately changes the opening and closing timing of the intake valve 25f and the valve opening lift amount according to the operating state of the engine 2. It is configured to be possible.

  The exhaust system 26 is configured to discharge the gas discharged from the cylinder 20 to the outside. Specifically, the exhaust pipe 26a is connected to the cylinder 20 via the exhaust port 26b. Further, the engine 2 is provided with an exhaust valve 26f for opening and closing an opening of the exhaust port 26b (a communication port with the cylinder 20). The exhaust valve 26f is opened and closed according to the rotational phase of the exhaust cam 26g. The exhaust cam 26g is fixed to the exhaust camshaft 26h. The exhaust valve 26f has an opening and closing timing and an opening lift amount of the engine 2 by an exhaust valve mechanism (including an exhaust cam 26g, an exhaust cam shaft 26h, and other members not shown). It is appropriately changed according to the operating state.

  A spark plug 27 is attached to the engine 2. An electrode part for generating spark discharge is formed at the tip of the spark plug 27. The spark plug 27 is provided in the combustion chamber (including the end portion on the top dead center side of the piston 21 in the cylinder 20) so that the above-described electrode portion is exposed. The spark plug 27 is electrically connected to an ignition device 27a including an ignition coil and the like. The ignition device 27a energizes the ignition plug 27 (applies a high voltage), thereby generating a spark discharge at the above-described electrode portion of the ignition plug 27.

  The engine 2 is provided with a decompression device 28. The decompression device 28 is configured to perform decompression when the engine 2 is started. Here, “decompression” in the present embodiment means that the exhaust valve 26f is opened during the compression stroke and the air in the cylinder 20 is released toward the exhaust port 26b and the exhaust pipe 26a. The increase in the in-cylinder pressure (pressure in the cylinder 20) is suppressed.

  Specifically, in the present embodiment, the decompression device 28 includes a decompression pin 28a and an actuator 28b. When the actuator 28b made of an electromagnetic solenoid is energized, the decompression pin 28a is located between the base end portion (tapet) of the exhaust valve 26f and the exhaust cam 26g at a position opposite to the cam lift portion of the exhaust cam 26g. By projecting so as to be interposed therebetween, the exhaust valve 26 f that should be originally closed can be forcibly opened (the basic configuration of such a decompression device 28 is (For example, see JP-A-2005-76620).

  In FIG. 4, the vertical axis represents cranking torque, and the horizontal axis represents crank angle. The solid line shows the cranking torque diagram during normal operation (when decompression is not performed), and the dotted line shows the cranking torque diagram when decompression is performed (the crank angle in the dotted line diagram is The range from about 120 degrees to about 620 degrees overlaps with the solid line (the “target stop position” in the figure will be described later). As shown by the dotted line in FIG. 4, in this embodiment, the fuel vapor is introduced into the cylinder 20 by the operation of the injector 25e, and the cylinder 20 is operated by the operation of the ignition plug 27 and the ignition device 27a. The increase in the in-cylinder pressure during the compression stroke is suppressed by the decompression to such an extent that the first explosion cannot be generated even if ignition combustion is attempted (specifically, the maximum in-cylinder pressure at the time of non-combustion is 20 at the time of non-decompression The amount of forced opening of the exhaust valve 26f by the decompression pin 28a is set so that the cranking torque is at least 40% or less of the normal time.

  Referring to FIG. 2 again, the power transmission mechanism 3 is configured to transmit the rotational driving force of the crankshaft 22 generated by the operation of the engine 2 to the rear wheel 1b (see FIG. 1). The power transmission mechanism 3 includes an output shaft 31 and a clutch 32. The output shaft 31 is connected to the crankshaft 22 via the clutch 32. The clutch 32 is configured to be able to switch between transmission and interruption of the rotational driving force between the crankshaft 22 and the output shaft 31. In the present embodiment, a one-way clutch mechanism is provided in the clutch 32.

  Referring to FIG. 3 again, various sensors are mounted on the engine 2 (including the intake system 25 and the exhaust system 26) in order to construct a system for controlling the operation of the engine 2. Specifically, the engine 2 is provided with an intake air temperature sensor 61, an intake air pressure sensor 62, a throttle opening sensor 63, a coolant temperature sensor 64, a crank angle sensor 65, a cam position sensor 66, a motor rotation angle sensor 67, and the like. It has been.

  The intake air temperature sensor 61 is attached to the air cleaner 25c. The intake air temperature sensor 61 is configured to generate an output corresponding to the temperature of intake air flowing through the air cleaner 25c. The intake pressure sensor 62 is configured and arranged to generate an output corresponding to the pressure in the intake pipe 25a on the downstream side of the throttle valve 25d. The throttle opening sensor 63 is configured and arranged to generate an output corresponding to the opening of the throttle valve 25d. The coolant temperature sensor 64 is attached to the cylinder block of the engine 2. The cooling water temperature sensor 64 is configured to generate an output corresponding to the cooling water temperature in the engine 2.

  The crank angle sensor 65 is disposed so as to face the crankshaft 22. The crank angle sensor 65 has a signal having a narrow pulse generated every time the crankshaft 22 rotates 10 degrees and a wide pulse generated every time the crankshaft 22 rotates 360 degrees (this signal is an engine control device). 4 is converted into an engine rotational speed NE). The cam position sensor 66 outputs a signal having a narrow pulse generated every time the intake camshaft rotates 5 degrees and a wide pulse generated every 360 degrees of the intake camshaft. Yes. The motor rotation angle sensor 67 includes Hall elements provided corresponding to the U phase, V phase, and W phase in the motor generator 24, respectively, and the rotation phase of the rotor 24a in the motor generator 24, that is, the rotation phase of the crankshaft 22 is determined. It is configured to be detectable.

  The engine control device 4 is a so-called microcomputer including a CPU, a ROM, a RAM, an interface, and the like. The engine control device 4 includes various operating units such as a motor generator 24, a throttle valve 25d, and an injector 25e, various sensors including the above-described intake air temperature sensor 61 to motor rotation angle sensor 67, and a driver (not shown). It is electrically connected to an operation unit (such as an ignition switch or a starter switch) via the above-described interface.

  The engine control device 4 is configured to control the operation of each part of the engine 2 in accordance with the output of various sensors including the intake air temperature sensor 61 and the like, and the operation state of the operation part. In particular, in the present embodiment, the engine control device 4 temporarily stops the engine 2 when the predetermined idling stop condition is satisfied (also controls the stop position of the piston 21 at this time), A so-called idling stop control is performed in which the engine 2 is restarted when a predetermined idling stop cancellation condition is satisfied.

  In the present embodiment, the engine control device 4 includes a valve control unit 401, a fuel injection control unit 402, an ignition control unit 403, a motor control unit 404, and other control units (not shown). . The valve control unit 401 controls the operation of a mechanism unit (including the intake valve mechanism 25g, the above-described exhaust valve mechanism, and the decompression device 28) for opening and closing the intake valve 25f and the exhaust valve 26f. It is like that. The fuel injection control unit 402 controls the operation of the injector 25e. The ignition control unit 403 controls the operation of the ignition device 27a. The motor control unit 404 controls the operation of the motor generator 24. In the present embodiment, the engine control device 4 is configured as an ASIC (Application Specific Integrated Circuit). That is, the valve operating control unit 401 and the like are mounted on the ASIC as a hardware circuit module separate from a CPU (not shown).

  In particular, the valve control unit 401 is the first time when the engine 2 is started (including the first start of the engine 2 after the ignition switch is turned on and the restart of the engine 2 under the idling stop control). The operation of the decompression device 28 (actuator 28b) is controlled so that the decompression is performed in the compression stroke while the decompression is not performed in the target initial explosion compression stroke. Here, the “first compression stroke” is a compression stroke that is first reached after the motor generator 24 for starting the engine 2 is started (after cranking is started by the motor generator 24). Further, the “target initial explosion compression stroke” is a compression stroke that is reached immediately after the initial compression stroke.

  The fuel injection control unit 402 is configured to control the operation of the injector 25e so that fuel injection is started from the target initial explosion intake stroke while fuel injection is not performed before the target initial explosion intake stroke. Here, the “target initial explosion intake stroke” is the intake stroke immediately before the target initial explosion compression stroke. In addition, the ignition control unit 403 starts generation of spark discharge by the spark plug 27 from the target initial explosion compression stroke, while preventing ignition from occurring before the target initial explosion compression stroke. That is, the operation of the spark plug 27 is controlled.

<Description of operation>
Hereinafter, the operation (action / effect) of the configuration of the present embodiment as described above will be described.

  In FIG. 5, the horizontal axis indicates the passage of time. “ACG” indicates the motor generator 24. Further, “NE” indicates the engine rotation speed. The parentheses indicate the operation state (ON / OFF) of the starter switch that is operated when the engine 2 is started for the first time after the ignition switch is turned on (therefore, this is under idling stop control). It is irrelevant in the case of restarting).

  Referring to FIG. 4, when the engine 2 is temporarily stopped under the idling stop control, the crank angle (the rotational phase of the crankshaft 22, that is, the position of the piston 21) becomes the “target stop position” shown in FIG. 4. Thus, stop control of the engine 2 is performed (see, for example, Japanese Patent Application Laid-Open No. 2007-231786). This target stop position is set in the vicinity immediately after the compression top dead center is exceeded so that the approaching rotation distance can be sufficiently obtained at the time of restart.

  When such stop control is performed, the crank angle is normally in the vicinity of the target stop position when cranking is started by the motor generator 24 for restarting the engine 2 under idling stop control. In this case, the crankshaft 22 is given sufficient rotational inertia force by cranking. For this reason, in this case, it is considered that the piston 21 can successfully overcome the initial compression stroke without performing decompression.

  However, unlike the case of restarting the engine 2 under idling stop control, when the engine 2 is started for the first time after the ignition switch is turned on after the engine 2 is completely stopped, the crank angle is not necessarily the target It is not always near the stop position. Therefore, in an extreme example, cranking may be started immediately before the compression top dead center as shown by a two-dot chain line in the figure. Further, even when the engine 2 is restarted under the idling stop control, the running rotation distance may not be sufficiently obtained due to an error in the stop position control. Furthermore, even if the cranking is from the vicinity of the target stop position, the inertia of the small and light motor generator 24 is sufficient to overcome the initial compression stroke due to the increase in inertia caused by the large displacement. It can be difficult.

  Therefore, in this embodiment, as shown in FIG. 5, the initial compression is performed after cranking is started by starting energization of the motor generator 24 (based on starter switch ON operation or establishment of a predetermined idling stop release condition). Until the stroke is over, decompression is performed so that the in-cylinder pressure is sufficiently lowered to the extent that the first explosion cannot be generated in the first compression stroke. As a result, the cranking torque is favorably reduced (see the dotted line in FIG. 4). Therefore, even if swingback is not performed, the initial compression stroke (compression top dead center) can be successfully overcome regardless of the crank angle at the start of cranking. Further, it is possible to reduce the torque required for the motor generator 24 at the start as much as possible, and thus it is possible to use a motor generator 24 having a lower rating (that is, smaller and lighter). Furthermore, it is possible to improve startability and apply an idling stop in the engine 2 having a larger displacement.

  By the way, in the configuration of the motorcycle 1 of the present embodiment, if the swingback is performed, the reverse rotation torque applied to the crankshaft 22 is rear wheel by the above-described one-way clutch mechanism provided in the clutch 32. It is transmitted to 1b. Therefore, in this case, there is a concern that the occupant may feel uncomfortable because the rear wheel 1b slightly rotates backward. In this respect, according to the present embodiment, since the swingback is not performed at the time of starting, a smooth (re-) starting that does not give the passenger an uncomfortable feeling is realized.

  Further, in the present embodiment, as shown in FIG. 5, after the initial compression stroke is successfully overcome, the angular speed of the crankshaft 22 is 800 revolutions per minute due to strong cranking by the motor generator 24. It rapidly rises to the extent corresponding to the number of revolutions. Thus, until reaching the next compression stroke, the inertial force due to the rotation of the crankshaft 22 rises to such an extent that the first explosion can be satisfactorily overcome the compression stroke even without decompression. Therefore, in the present embodiment, the decompression is completed during the target initial explosion compression stroke so that the air in the cylinder 20 is not released to the extent that the initial explosion cannot be generated. As a result, the initial explosion is successfully realized in the target initial explosion compression stroke, which is the next compression stroke of the first compression stroke, and thus the engine 2 can be quickly (re-) started (“Next” in FIG. 5). The ACG rotation speed after turning off the ACG energization in the “cycle” corresponds to the idling rotation speed of the engine 2).

  Further, in the present embodiment, the fuel injection is controlled by the engine control device 4 so that the fuel injection is started from the target initial explosion intake stroke while the fuel injection is not performed before the target initial explosion intake stroke. . Similarly, the spark discharge by the spark plug 27 starts from the target initial explosion compression stroke, while the engine control device 4 causes the ignition device 27a not to generate spark discharge before the target initial explosion compression stroke. That is, the energization of the spark plug 27 is controlled. Therefore, according to the configuration of the present embodiment, it is possible to satisfactorily prevent unburned fuel mixture from being blown into the exhaust pipe 26a and useless use of ignition power.

<Modification>
Hereinafter, some typical modifications will be exemplified. In the following description of the modified examples, the same reference numerals as those in the above embodiment can be used for portions having the same configurations and functions as those described in the above embodiment. And about description of this part, the description in the above-mentioned embodiment shall be used suitably in the range which is not technically consistent. Needless to say, the modifications are not limited to those listed below. In addition, all and some of the plurality of modified examples may be applied in a composite manner as appropriate within a technically consistent range.

  The target initial explosion compression stroke is not limited to the compression stroke that occurs immediately after the initial compression stroke. That is, for example, the target initial explosion compression stroke may be a compression stroke that reaches a predetermined minority number of times (two times, three times, etc.) from the initial compression stroke. In this case, the degree of air release (that is, the degree of suppression of the increase in the in-cylinder pressure) in a plurality of compression strokes in which decompression is performed is set to such an extent that the first explosion cannot occur. In particular, in the configuration of the above-described embodiment, the degree of air release is substantially constant in a plurality of compression strokes in which decompression is performed.

  The decompression device 28 is not limited to the configuration shown in the above-described embodiment. For example, as shown in FIG. 6, the exhaust valve 26 f may be driven by a hydraulic valve mechanism 29. The hydraulic valve mechanism 29 is configured such that the opening and closing timing of the exhaust valve 26f and the valve opening lift amount can be appropriately changed according to the hydraulic pressure supply state (see, for example, Japanese Patent Application Laid-Open No. 2007-71025). ). In such a configuration, a hydraulic pressure supply state for opening the exhaust valve 26f is realized in the compression stroke, so that the exhaust valve 26f is forcibly opened at the time of decompression. That is, in the configuration shown in FIG. 6, the hydraulic valve mechanism 29 corresponds to the decompression device 28 in FIG.

  In the configuration of FIG. 6, the cranking torque is reduced to the maximum by setting the valve opening amount (lift amount) of the exhaust valve 26f to the full lift amount in the exhaust stroke at the time of decompression. Alternatively, the lift amount may be variable according to the crank angle at the start of cranking. Specifically, the lift amount of the exhaust valve 26f at the time of decompression may be controlled so that the lift amount increases as the crank angle at the cranking start time becomes farther from the target stop position shown in FIG. .

  Further, the decompression device 28 is not limited to the one that is electrically controlled as described above. That is, for example, the decompression device 28 is set by stopping the rotation of the exhaust camshaft 26h and set to a decompression operation state (a state in which the exhaust valve 26f is forcibly opened), while the exhaust camshaft 26h is It may have a mechanical configuration that is reset after one rotation (or a small number of predetermined rotations) and set to a normal operation state (a state in which the decompression operation state is released) (such a mechanical configuration). The configuration can be realized relatively easily using the common general knowledge of those skilled in the art at the time of filing of the present application).

  The present invention is not limited to single cylinder engines. That is, the present invention can be suitably applied to a multi-cylinder engine including two cylinders. In this case, it is preferable that a decompression device 28 is provided for each of the cylinders 20. Further, it is assumed that the specific cylinder corresponding to the “target initial explosion intake stroke” reaches the “target initial explosion compression stroke”.

  In particular, in a multi-cylinder engine, even if a sufficient running rotation distance is obtained for one cylinder 20 by performing stop control in the idling stop control, a sufficient running rotation distance cannot be obtained for the other cylinders 20. There is a case. Even in such a case, according to the present invention, good startability is ensured.

  In the above embodiment, the valve operating control unit 401 and the like are realized by hardware, but may be realized by software as a functional block. That is, the valve control unit 401 or the like may be realized as a routine (program) that is read out and executed from a ROM or a rewritable nonvolatile memory by the operation of the CPU.

  The in-cylinder pressure in the compression stroke can also be reduced by delaying the closing timing of the intake valve 25f (see Japanese Patent Application Laid-Open No. 2000-34913, etc .: this can also be referred to as “decompression”. On the other hand, the “intake side decompression” is referred to as “exhaust side decompression”. In this regard, in the present invention, it is possible to use both intake-side decompression and exhaust-side decompression. However, in this case, the exhaust side decompression is not performed in the target initial explosion compression stroke, while the intake side decompression is optional (may or may not be performed) in the target initial explosion intake stroke. .)

  DESCRIPTION OF SYMBOLS 1 ... Motorcycle, 2 ... Engine, 20 ... Cylinder, 22 ... Crankshaft, 24 ... Motor generator, 28 ... Decompression device

Claims (8)

An engine starter configured to start an engine (2) mounted on a vehicle (1) and having at least one cylinder (20),
The rotation drive force is transmitted to the crankshaft (22) of the engine so that transmission of the rotation drive force cannot be interrupted, and functions as a generator by the rotation drive force generated at the crankshaft after the engine is started. A motor generator (24) configured to function as a starting motor by rotating the crankshaft in the same direction as after starting the engine at the time of
A decompression device (28) configured to perform decompression to release air in the cylinder during a compression stroke to the outside of the cylinder at the time of starting the engine;
With
The decompression device is
In the initial compression stroke, which is the first compression stroke after starting the motor generator for starting the engine, even if fuel is sucked into the cylinder that reaches the initial compression stroke, the first explosion occurs. While performing the decompression so that the air in the cylinder is released to an impossible level,
The decompression is terminated during the target initial explosion compression stroke, which is a compression stroke that reaches a predetermined number of times after the initial compression stroke, so that the air in the cylinder is not released to the extent that the first explosion cannot be generated. An engine starting device characterized in that the engine starting device is configured. The engine starter according to claim 1,
A control device (401) for controlling the operation of the decompression device;
The engine starting device according to claim 1, wherein the decompression device includes an actuator (28b) whose operation is controlled by the control device. The engine starting device according to claim 1 or 2,
Controlling fuel injection so that fuel injection is started from a target initial explosion intake stroke that is an intake stroke immediately before the target initial explosion compression stroke, while fuel injection is not performed before the target initial explosion intake stroke. An engine starter further comprising fuel injection control means (402). The engine starter according to any one of claims 1 to 3,
The decompression device is configured to vary the degree of air release in the decompression according to the position of the piston (21) in the engine when the motor generator is started to start the engine. An engine starting device. An engine starting device according to any one of claims 1 to 4,
The decompression device is
Even after the initial compression stroke and before the target initial explosion compression stroke, even if fuel is sucked into the cylinder that reaches the compression stroke, the first explosion is not caused to occur. An engine starter configured to perform the decompression so that air in a cylinder is discharged. An engine starting device according to claim 5,
The decompression device is
An engine starter configured to perform the decompression so that a degree of air emission is constant. An engine starting device according to any one of claims 1 to 4,
The engine start device according to claim 1, wherein the target initial explosion compression stroke is a compression stroke which is reached immediately after the initial compression stroke. The engine starting device according to any one of claims 1 to 7,
The engine starting device, wherein the engine is a single cylinder engine.

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