JP4325477B2 - Engine starter - Google Patents

Description

  In the present invention, for example, in an eight-cylinder four-cycle engine in which a crank angle phase difference between cylinders is set to 90 ° CA and a plurality of cylinders have the same stroke, a predetermined automatic stop condition is established in an idle operation state of the engine or the like. The present invention relates to an engine starter configured to automatically stop an engine from time to time and then automatically restart when a predetermined restart condition is satisfied.

In recent years, in order to reduce fuel consumption and reduce CO ₂ emissions, a restart condition has been established such that the engine is automatically stopped temporarily during idling and the vehicle is then started by the driver. At the time, a technology for automatic engine stop control (so-called idle stop control) that automatically restarts the engine has been developed. The restart at the time of the idle stop control requires a quickness to immediately start the engine in accordance with the vehicle starting operation or the like. According to the method of restarting the engine through cranking for driving the shaft, there is a problem that it takes a considerable time to complete the starting.

  Therefore, it is desirable to immediately start the engine with the combustion energy by injecting fuel into the expansion stroke cylinder which is in a stopped state in the expansion stroke, and igniting and burning the fuel. However, when the engine is stopped, the in-cylinder pressure becomes approximately atmospheric pressure in a short time, so that sufficient output for restarting can be obtained even if fuel is supplied to the cylinder that is at approximately atmospheric pressure and burned. It may not be possible.

  As countermeasures, for example, engine starting devices as shown in Patent Document 1 and Patent Document 2 are known. In the engine starting device disclosed in Patent Document 1, when starting the engine, first, fuel is injected into the compression stroke cylinder that is stopped in the compression stroke to perform combustion, and after the engine is once rotated in the reverse direction, Combustion is performed in the expansion stroke cylinder so that the engine is rotated in the normal direction and started. Similarly, in the engine starter disclosed in Patent Document 2, when starting the engine, first, fuel is injected into the compression stroke cylinder that is stopped in the compression stroke to cause combustion, and the engine is once rotated in reverse. Let Then, the piston of the compression stroke cylinder is stopped before the bottom dead center, and then the combustion is performed in the expansion stroke cylinder so that the engine is rotated in the normal direction and started.

In any of these engine starters, the piston of the expansion stroke cylinder is raised by rotating the engine once in the reverse direction, and the compression pressure is increased, and then combustion is performed in the cylinder. In addition to turning in the direction, a sufficiently high output is obtained for the subsequent continuous operation.
WO 01/38726 A1 WO 01/81759 A1

  According to the engine starting device disclosed in Patent Document 1 and Patent Document 2, the output obtained by the first combustion of the expansion stroke cylinder at the time of starting is increased. It is desirable that the output from the first combustion be high in order to continue the subsequent operation smoothly. In order to increase the output obtained by the initial combustion of the expansion stroke cylinder, it is necessary to strongly compress a large amount of air introduced into the cylinder according to the reverse operation of the engine.

  However, if the amount of air in the expansion stroke cylinder is excessively increased, it becomes difficult to sufficiently compress the in-cylinder air. Further, since the expansion stroke cylinder and the compression stroke cylinder are operated in opposite directions, if the piston position at the time of stopping is brought close to bottom dead center and the amount of air in the expansion stroke cylinder is increased, the compression stroke cylinder The amount of air inside will decrease. Therefore, if the amount of air in the expansion stroke cylinder is increased too much, the amount of air in the compression stroke cylinder decreases and the reverse energy due to the first combustion decreases, and the gas (mixture) in the expansion stroke cylinder is sufficiently increased. There is a problem that it cannot be compressed.

  Further, if the combustion energy for reverse rotation in the compression stroke cylinder is excessively increased to strongly compress the air in the expansion stroke cylinder, the reverse rotation amount of the engine (crankshaft) may be excessive. When the reverse rotation amount of the engine becomes excessive and the piston of the compression stroke cylinder exceeds the bottom dead center, the compression stroke cylinder returns to the intake stroke, and the expansion stroke cylinder returns to the compression stroke. Cannot be restarted. Therefore, it is necessary to appropriately adjust the combustion energy for reverse rotation in the compression stroke cylinder, which causes a problem that the compression pressure of air in the expansion stroke cylinder is limited.

  In particular, in an 8-cylinder 4-cycle engine in which the crank angle phase difference between cylinders is set to 90 ° CA and the plurality of cylinders have the same stroke, for example, there are a plurality of cylinders that have been in the compression stroke when the engine is stopped. In addition, the amount of air in the expansion stroke cylinder and the combustion energy for reverse rotation tend to be excessive.

  In the present invention, in view of the above circumstances, for example, in a multi-cylinder four-cycle engine in which a crank angle phase difference between cylinders is set to 90 ° CA and a plurality of cylinders have the same stroke, It is an object of the present invention to provide an engine starter capable of appropriately controlling combustion energy and improving engine startability.

In the invention according to claim 1, in a multi-cylinder four-cycle engine in which a crank angle phase difference between cylinders is set to 90 ° CA and a plurality of cylinders have the same stroke, fuel is supplied when a predetermined automatic stop condition is satisfied. The engine is stopped by stopping the engine, and when a predetermined restart condition is satisfied, the engine is automatically restarted by supplying fuel to at least the cylinder in the expansion stroke at the time of engine stop and causing combustion. An engine starter for causing the engine to temporarily operate in the reverse direction by causing a first combustion to be performed in a cylinder that has been in the compression stroke first among a plurality of cylinders that are in the compression stroke at the time of engine stop. with the engine by causing at least one in the second combustion of the plurality of cylinders in the expansion stroke at the end of this reverse operation in the forward direction After moving, which is constituted so as to start the engine to perform the third round of combustion in other cylinders in the compression stroke at the stop time of the engine.

The invention according to claim 2 is the engine starting system according to the claim 1, after completion of the reverse rotation of the engine, but to perform the second round of the combustion in the cylinder in the expansion stroke from the stop time of the engine is there.

According to a third aspect of the present invention, in the engine starter according to the first or second aspect, the second combustion is performed in all the cylinders in the expansion stroke after the reverse rotation operation of the engine is completed.

According to a fourth aspect of the present invention, in the engine starting device according to any one of the first to third aspects, after the engine is operated in the forward rotation direction, the engine is in a compression stroke when the engine is stopped. When the third combustion is performed in the cylinder, the ignition timing is delayed from the normal time.

The invention according to claim 5 is the engine starting system according to any one of the preceding claims 1-4, in all the cylinders were the expansion stroke when the engine is stopped, the piston stroke first three minutes of the If it is outside 1, the starter motor is operated from the start of engine restart.

The invention according to claim 6 is the engine starter according to any one of claims 1 to 4 , wherein the pistons of the cylinders in the expansion stroke when the engine is stopped are the first half of the stroke. When the engine is outside, the engine is operated in the forward rotation direction by causing the first combustion to be performed in the cylinder in the expansion stroke from the stop point of the engine without operating the engine in the reverse rotation direction when the engine is restarted. Is.

According to a seventh aspect of the present invention, in the engine starter according to any one of the first to sixth aspects of the present invention, the restart timing of the engine is determined based on the intake valve closing timing of the cylinder that first becomes the compression stroke when the engine is stopped. It changes to the early closing state by the time.

  According to the first aspect of the present invention, when the engine is stopped, the first combustion is performed in the cylinder on the side where the compression stroke first occurs and the stroke becomes large during the reverse rotation of the engine, and the engine is reversely rotated by a predetermined amount. Since the piston of the cylinder in the expansion stroke is raised at the end of the reverse operation, combustion is performed in the cylinder with the compression pressure sufficiently increased. The drive torque at the engine is sufficiently generated, and then combustion is performed in another cylinder that was in the compression stroke when the engine was stopped, effectively increasing the engine speed and restarting the engine properly. Can be made.

  According to the invention of claim 2, by causing the first combustion to be performed in at least one of the cylinders in the compression stroke when the engine is stopped, the engine is reversely rotated so that any cylinder exceeds the compression top dead center. At the end of the reverse rotation operation, the piston of the cylinder in the expansion stroke is raised, and the combustion is performed in the cylinder with the compression pressure sufficiently increased. The driving torque in the direction can be secured and the engine can be restarted properly.

  According to the invention of claim 3, among the plurality of cylinders in the expansion stroke after completion of the reverse rotation operation at the time of restarting the engine, the gas in the cylinder in the expansion stroke from the engine stop time is the reverse rotation of the engine. Combustion is performed in a sufficiently compressed state according to the operation, so that there is an advantage that combustion energy necessary for normal rotation and restart of the engine can be effectively obtained.

  According to the fourth aspect of the present invention, when the engine is configured to perform combustion in all the cylinders in the expansion stroke when the reverse rotation operation of the engine is completed, the normal rotation operation of the engine is changed from the initial position when the engine is stopped. Accordingly, the engine can be restarted properly by sufficiently securing the combustion energy at the time when the second compression top dead center is reached.

  According to the fifth aspect of the present invention, when the engine is operated in the forward rotation direction and then combustion is performed in another cylinder in the compression stroke when the engine is stopped, the ignition timing is delayed from the normal time. Therefore, it is possible to prevent the occurrence of reverse torque due to ignition performed before compression top dead center at a very low engine speed immediately after the start of forward rotation of the engine. Therefore, it is possible to effectively improve the engine startability by suppressing the amount of energy consumed by the piston of the cylinder in the compression stroke when the engine is stopped exceeding the compression top dead center.

  According to the invention of claim 6, when all the cylinders that were in the expansion stroke when the engine is stopped are outside the first half of the stroke (0 ° to 60 ° CA after top dead center), the combustion energy is insufficient. Since the engine speed tends not to be sufficiently increased, the engine can be reliably restarted by operating the starter motor from the start of engine restart and performing the start assist.

  According to the seventh aspect of the present invention, when all the cylinders in the expansion stroke when the engine is stopped are outside the first half of the stroke (0 ° to 60 ° CA after top dead center), these cylinders Since the air quantity of the engine is sufficiently secured, the engine is made to perform fuel first in each of the cylinders in the expansion stroke from the engine stop time without performing the reverse rotation of the engine when the engine is restarted. By operating in the forward rotation direction, the engine can be restarted properly.

  According to the invention of claim 8, by changing the intake valve closing timing of the cylinder that has first reached the compression stroke when the engine is stopped to the early closing state from the engine stop time to the engine restart start time, There is an advantage that when the first combustion is performed in the cylinder at the time of restart and the engine is operated in the reverse direction, the intake valve is opened and combustion gas can be reliably prevented from flowing out to the intake passage side. is there.

  1 and 2 show a schematic configuration of a four-cycle spark ignition engine having an engine starter according to the present invention. The engine includes an engine main body 1 having a cylinder head 10 and a cylinder block 11 and an ECU 2 for engine control. The engine body 1 includes a first cylinder row having a first cylinder 12A, a third cylinder 12C, a fifth cylinder 12E and a seventh cylinder 12G, a second cylinder 12B, a fourth cylinder 12D, a sixth cylinder 12F and an eighth cylinder. This is a V-type engine in which a second cylinder row having cylinders 12H is arranged side by side. Inside each cylinder 12A to 12H, a piston 13 connected to the crankshaft 3 is fitted and burned upward. A chamber 14 is formed.

  A spark plug 15 is installed at the top of the combustion chamber 14 of each of the cylinders 12 </ b> A to 12 </ b> H so that the plug tip faces the combustion chamber 14. The ignition plug 15 is provided with an ignition device 27 for generating an electric spark. A fuel injection valve 16 that directly injects fuel into the combustion chamber 14 is provided on the side of the combustion chamber 14. The fuel injection valve 16 incorporates a needle valve and a solenoid (not shown), and is driven for a time corresponding to the pulse width of the pulse signal input from the fuel injection control unit 41 of the ECU 2 to open the valve. An amount of fuel corresponding to the time is injected toward the vicinity of the electrode of the spark plug 15.

  In addition, an intake port 17 and an exhaust port 18 that open toward the combustion chamber 14 are provided above the combustion chambers 14 of the cylinders 12A to 12H, and an intake valve 19 and an exhaust gas are connected to these ports 17 and 18, respectively. Each valve 20 is equipped. The intake valve 19 and the exhaust valve 20 are driven by a valve operating mechanism having a camshaft (not shown), so that each cylinder 12A to 12H performs a combustion cycle with a predetermined phase difference. The opening / closing timing of the 12H intake / exhaust valves 19, 20 is set.

  An intake passage 21 and an exhaust passage 22 are connected to the intake port 17 and the exhaust port 18. The downstream side of the intake passage 21 close to the intake port 17 is an independent branch intake passage 21a corresponding to each cylinder 12A to 12H, and the upstream end of each branch intake passage 21a communicates with the surge tank 21b. Yes. A common intake passage 21c is provided upstream of the surge tank 21b, and a throttle valve 23 driven by an actuator 24 is provided in the common intake passage 21c. An air flow sensor 25 for detecting the intake air flow rate and an intake air temperature sensor 29 for detecting the intake air temperature are provided upstream of the throttle valve 23, and an intake air pressure (negative pressure) is detected downstream of the throttle valve 23. An intake pressure sensor 26 is provided.

  On the other hand, a catalyst 37 for purifying the exhaust is disposed downstream of the collection portion of the exhaust passage 22 where exhaust from each of the cylinders 12A to 12H collects. This catalyst 37 is, for example, a so-called three-way catalyst in which the purification rate of HC, CO and NOx is extremely high when the air-fuel ratio state of the exhaust is in the vicinity of the theoretical air-fuel ratio, and this is a relatively high oxygen concentration in the exhaust. It has an oxygen storage capacity for storing it in a high oxygen excess atmosphere. When the oxygen concentration is relatively low, the stored oxygen is released and reacted with HC, CO and the like. Note that the catalyst 37 is not limited to a three-way catalyst, and may be any catalyst that has the above-described oxygen storage ability. For example, the catalyst 37 may be a so-called lean NOx catalyst that can purify NOx even in an oxygen-excess atmosphere.

  The engine body 1 is provided with an alternator 28 connected to the crankshaft 3 by a timing belt or the like. The alternator 28 includes a regulator circuit 28a that adjusts the amount of power generation by controlling the current of a field coil (not shown) and adjusting the output voltage, and a control signal from the ECU 2 that is input to the regulator circuit 28a. Based on the above, control of the amount of power generation corresponding to the electric load of the vehicle, the voltage of the on-vehicle battery, and the like is executed.

  Further, the engine is provided with two crank angle sensors 30 and 31 for detecting the rotation angle of the crankshaft 3, and the rotation speed of the engine is detected based on a detection signal output from one crank angle sensor 30. In addition, as will be described later, the rotation direction and the rotation angle of the crankshaft 3 are detected based on detection signals out of phase output from the crank angle sensors 30 and 31.

  The engine body 1 is provided with a cam angle sensor 32 for detecting a specific rotational position for cylinder identification provided on the camshaft and a water temperature sensor 33 for detecting the coolant temperature of the engine. Is provided with an accelerator opening sensor 34 for detecting the accelerator opening corresponding to the accelerator operation amount of the driver.

  The ECU 2 is a control unit that comprehensively controls the operation of the engine, and stops fuel injection to each of the cylinders 12A to 12H at a predetermined timing when a preset engine automatic stop condition is satisfied (fuel cut). The engine is automatically stopped, and then the engine is automatically restarted (idle stop control) when the restart condition is satisfied, for example, when the driver performs an accelerator operation. Has been.

  The ECU 2 receives detection signals from an air flow sensor 25, an intake pressure sensor 26, an intake air temperature sensor 29, crank angle sensors 30, 31, a cam angle sensor 32, a water temperature sensor 33, and an accelerator opening sensor 34. The fuel injection valve 16, the actuator 24 of the throttle valve 23, the ignition device 27, the fuel injection control unit 41 that outputs each drive signal to the regulator circuit 28 a of the alternator 28, the ignition control unit 42, the intake flow rate control unit 43, power generation An amount control unit 44, a piston position detection unit 45, and an in-cylinder temperature estimation unit 46 are provided.

  The fuel injection control unit 41 sets a fuel injection timing and a fuel injection amount, and outputs a signal to the fuel injection valve 16. The ignition control unit 42 is configured to set an appropriate ignition timing for each of the cylinders 12 </ b> A to 12 </ b> H and output an ignition signal to each ignition device 27.

  The intake flow rate control unit 43 is configured to set an appropriate intake flow rate for each of the cylinders 12 </ b> A to 12 </ b> H and output an opening degree signal of the throttle valve 23 corresponding to the intake flow rate to the actuator 24. In particular, in this embodiment, when the engine is automatically stopped, by adjusting the opening of the throttle valve 23, the intake flow rate is controlled so that the piston 13 is stopped in an appropriate stop range suitable for restarting. As will be described in detail later, among the two cylinders that are adjacent to each other in the ignition order and that are in the compression stroke when the engine is stopped, the intake air flow rate of the cylinder that is in the compression stroke later than the cylinder that is in the compression stroke first Therefore, a difference is made in the flow rate of the intake air.

  The power generation amount control unit 44 is configured to set an appropriate power generation amount of the alternator 28 and output the drive signal to the regulator circuit 28a. In particular, in the present embodiment, when the engine is automatically stopped, the engine speed is controlled to decrease along a preset reference line by adjusting the engine load by the power generation of the alternator 28, and when the engine is restarted, The power generation amount control unit 44 performs control to increase the engine load by performing more power generation than usual and to prevent the engine speed from rising, that is, the engine speed from increasing more rapidly than necessary. It is configured as follows.

  The piston position detector 45 detects the piston position based on the detection signals of the crank angle sensors 30 and 31. The piston position and the crank angle (° CA) have a one-to-one correspondence, and the piston position is represented by the crank angle in this specification as is generally done. In this embodiment, as will be described later, the in-cylinder air amount is calculated based on the piston positions during the automatic stop of the expansion stroke cylinder and the compression stroke cylinder, and the combustion control of each cylinder at the time of restart is accordingly performed. Is going.

  The in-cylinder temperature estimation unit 46 uses the maps previously obtained through experiments and the like based on the engine water temperature detected by the water temperature sensor 33, the intake air temperature detected by the intake air temperature sensor 29, and the like. The air temperature in each cylinder is estimated. In particular, in this embodiment, as will be described later, in-cylinder temperature estimation is performed in consideration of the engine stop time when the engine is restarted, and combustion control is performed based on the estimated value.

  As described above, in the multi-cylinder (8-cylinder) four-cycle engine in which the crank angle phase difference of each of the cylinders 12A to 12H is set to 90 CA ° and the plurality of cylinders have the same stroke, When the engine is restarted, combustion is performed in the cylinder that is in the compression stroke first among the pair of cylinders that are in the compression stroke when the engine is stopped, and the piston 13 is pushed down to temporarily operate the crankshaft 3 in the reverse rotation direction. In addition, the engine is operated in the forward rotation direction by performing combustion with at least one of the plurality of cylinders in the expansion stroke at the end of the reverse rotation operation, and then in the compression stroke when the engine is stopped. By causing combustion in other cylinders, control is performed to restart the engine without using a restart motor or the like. It has become the jar.

  That is, as shown in FIG. 8, the crank angle phase difference of each cylinder 12A-12H is set to 90CA, and each cylinder 12A-12H includes the first cylinder 12A, the eighth cylinder 12H, the fifth cylinder 12E, In an eight-cylinder four-cycle engine configured to be ignited in the order of the four cylinders 12D, the seventh cylinder 12G, the sixth cylinder 12F, the third cylinder 12C, and the second cylinder 12B, at an engine stop time ta, for example, The combustion cycle is set so that the pair of cylinders have the same stroke so that the fourth cylinder 12D and the seventh cylinder 12G stop in the compression stroke, and the eighth cylinder 12H and the fifth cylinder 12E stop in the expansion stroke. Has been.

  Of the pair of cylinders 12D and 12G in the compression stroke at the time of stopping the engine, the fourth cylinder 12D first in the compression stroke has the piston 13 at the top dead center as compared with the other seventh cylinder 12G. Since the fuel is stopped at a close position, the first combustion (1) is performed in the fourth cylinder 12D, so that the piston 13 can be sufficiently stroked to effectively reverse the crankshaft 3. Moreover, since the amount of air in the fourth cylinder 12D is smaller than that of the other seventh cylinder 12G, it is prevented that the combustion energy during the reverse operation is excessively increased, and according to the reverse operation of the engine. It is possible to prevent other cylinders from exceeding the compression top dead center after the fifth cylinder 12E that first reaches compression top dead center exceeds the compression top dead center.

  In addition, after the engine is reversed by performing combustion (1) in the fourth cylinder 12D that is initially in the compression stroke when the engine is stopped, the above-mentioned reverse rotation is performed with the eighth cylinder 12H that is in the expansion stroke from the time when the engine is stopped. Combustion (2a) and (2b) are performed in both the first cylinder 12A that has shifted from the exhaust stroke to the expansion stroke by operation, and the engine is driven in the forward rotation direction. Sufficient combustion energy is obtained for the seventh cylinder 12G to reach the compression top dead center.

  In order to obtain a high start success rate by such start control, it is required to stop the piston within a predetermined appropriate range described later when the engine is stopped. Therefore, when the engine is automatically stopped, the ECU 2 performs control as shown in FIGS. 3 to 5 in order to increase the probability that the piston stop position is within a predetermined appropriate range. FIG. 3 is a time chart when the engine is automatically stopped by this control, and shows the rotational speed Ne of the engine, the opening degree K of the throttle valve 23, and the stroke of each cylinder. 4 and 5 are flowcharts showing the control when the engine is automatically stopped.

  The control operation at the time of automatic stop shown in FIGS. 4 and 5 will be described with reference to FIG. These flowcharts are flowcharts of engine automatic stop control from uniform combustion in which the air-fuel ratio in the cylinder is set to the stoichiometric air-fuel ratio or near the stoichiometric air-fuel ratio. When this control operation starts, it is first determined whether or not an automatic engine stop condition is satisfied based on detection signals output from various sensors (step S1). Specifically, the brake switch remains on for a predetermined time, the remaining battery level is equal to or higher than a preset reference value, and the vehicle speed is equal to or lower than a predetermined value (for example, 10 km / h). Is confirmed, it is determined that the engine automatic stop condition is satisfied. If any of the above requirements is not satisfied, it is determined that the engine automatic stop condition is not satisfied.

  If it is determined YES in step S1 and it is confirmed that the engine automatic stop condition is satisfied, the shift range of the automatic transmission is set to neutral to make it unloaded (step S2) and EGR. The EGR valve (not shown) provided in the passage is closed to stop the exhaust gas recirculation (step S3), and the target value (target speed) of the engine speed Ne is higher than the normal idle speed. N1 (for example, about 850 rpm) is set (step S4). Further, the opening K of the throttle valve 23 is adjusted (the throttle valve 23 is operated in the valve opening direction) so that the boost pressure Bt becomes the target pressure P1 set to, for example, about −400 mmHg (step S5), and the engine The retard amount of the ignition timing is calculated so that the rotational speed Ne becomes the target predetermined speed N1 (step S6). Thereby, the throttle opening K is fed back in order to set the boost pressure Bt to the target pressure P1, and the retard amount of the ignition timing is fed back in order to set the engine rotation speed Ne to the predetermined speed N1 (engine rotation). Speed feedback control is executed).

  In step S1, the determination of the automatic engine stop condition is executed when the vehicle speed is reduced to 10 km / h or less. Therefore, the idle rotation speed (predetermined speed N1 when the automatic engine stop condition is satisfied) is determined. ) Can be set to a value (850 rpm) higher than the normal idle rotation speed when the engine is not automatically stopped (for example, 650 rpm in the D range state of the automatic transmission), and the engine rotation speed is set to the normal idle rotation speed (650 rpm). The above steps S2 to S6 can be executed before the decrease. Therefore, there is no need to increase the engine rotational speed once reduced to the normal idle rotational speed to the target rotational speed N1 (850 rpm), and the driver will not be uncomfortable with the increased engine rotational speed. .

  Next, whether or not a fuel injection stop condition (fuel cut condition) is satisfied, specifically, whether or not the engine rotational speed Ne has reached the target predetermined speed N1 and the boost pressure Bt has reached the target pressure P1. Is determined (step S7), and if the determination is NO, the process returns to step S5 and the above control operation is repeated. Then, at the time when YES is determined in step S7 (time t1 in FIG. 3), the throttle valve 23 is opened to a relatively large opening (about 30%) (step S8), and the amount of power generated by the alternator 28 is increased. Is set to 0 to stop power generation (step S9), and fuel injection is stopped (step S10). The reason why the throttle valve 23 is opened in step S8 is to promote scavenging of each cylinder by increasing the intake flow rate.

  Thereafter, after the fuel injection stop time t1, whether or not the engine rotational speed Ne has become equal to or lower than a predetermined speed N2 set to about 760 rpm in order to determine that the engine rotational speed Ne has started to decrease. Is determined (step S11). Then, the throttle valve 23 is closed when it is determined as YES in step S11 (time t2 in FIG. 3) (step S12). As a result, the boost pressure Bt that opens the throttle valve 23 in step S8 so as to approach the atmospheric pressure starts to decrease with a predetermined time difference according to the closing operation of the throttle valve 23.

  Note that, instead of the above-described embodiment in which the throttle valve 23 is closed at the time t2 when it is determined in step S11 that the engine rotational speed Ne has become equal to or lower than the predetermined speed N2, the piston 13 is compression dead. The throttle valve 23 may be closed when it is determined that the engine speed when passing the point, that is, the engine top dead center speed ne is equal to or lower than the predetermined speed N2.

  Next, it is determined whether or not the engine top dead center rotational speed ne is equal to or lower than a predetermined speed N2 set to a preset value of about 760 rpm (step S13). If it determines with YES here, it will control from now on so that the rotational speed Ne of an engine may fall along the preset reference line. In this embodiment, the power generation amount of the alternator 28 is adjusted so that the top dead center rotational speed ne at the time of each compression top dead center that passes sequentially is within the appropriate rotational speed range (step S14). Specifically, when the top dead center rotational speed ne is high, the power generation amount is increased to increase the rotational resistance of the crankshaft 3, and the lowering speed of the engine rotational speed Ne is increased to increase the next top dead center rotational speed ne. Approaches the preset reference line. Conversely, when the top dead center rotational speed ne is low, the power generation amount is decreased.

  Then, each time each cylinder sequentially passes through the compression top dead center, it is determined whether or not the engine top dead center rotational speed ne is equal to or lower than a predetermined value N3 (step S15). This predetermined value N3 is 90 ° CA from the last piston top dead center (time point t5 in FIG. 3) immediately before the engine is stopped in the process in which the engine rotational speed Ne decreases along the preset reference line. This corresponds to the engine speed at a time earlier (time t3 in FIG. 3) earlier than the time just before (time t4 in FIG. 3) by the response delay time of the intake flow rate control. In this case, the relationship between the passage of time and the change in the rotational speed is uniquely determined under the condition that the rotational speed Ne of the engine is controlled to decrease along the preset reference line. The engine rotation speed at can be obtained experimentally in advance, and the engine rotation speed is set to the predetermined value N3.

  While the determination in step S15 is NO, the process returns to step S14 and the control is repeated. If the determination in step S15 is YES, the throttle valve 23 is opened to a predetermined large opening (for example, 40%). . Thereafter, as the engine speed Ne further decreases, it is determined whether or not the engine has been stopped (step S17), and when determined to be YES (time t6 in FIG. 3), as will be described later. After executing the control for detecting the stop position of the piston 13 based on the detection signals of the crank angle sensors 30 and 31, the control operation is terminated.

  According to the above automatic stop control, the probability that the piston stop position falls within a predetermined appropriate range is increased. That is, as shown in FIG. 3, the throttle valve 23 is opened for scavenging at the initial stage of the automatic engine stop operation. Then, the throttle valve 23 is once closed to reduce the flow rate of the intake air, and thereafter When the throttle valve 23 is opened at a time t3 that is earlier by the response delay time of the intake air flow rate control than the last piston top dead center just before the engine stop by 90 ° CA, the last piston top dead center is reached. The intake flow rate is less before and 90 ° CA before (the second top dead center of the piston from the end), and the intake flow rate is higher after that. That is, as shown in FIG. 3, the intake air flow rate is small in the intake stroke of the cylinder (fourth cylinder 12D in the example of FIG. 3) that becomes the compression stroke first among the two cylinders that become the compression stroke when the engine is stopped. In the intake stroke of the cylinder (the seventh cylinder 12G in the example of FIG. 3) that will be in the compression stroke later, the intake flow rate increases in the latter half. Therefore, the fourth cylinder 12D has a relatively low compression resistance, and the seventh cylinder 12G has a high compression resistance.

  As a result, the piston stops at a position near the bottom dead center of the seventh cylinder 12G cylinder (see FIG. 8). Therefore, in one of the cylinders that are in the expansion stroke when the engine is stopped (the fifth cylinder 12E in the example of FIG. 8), the piston stops at a position near the top dead center, and the piston stop position divides the expansion stroke into three equal parts. Often, this is the first half of the year, and in particular, it often stops near ATDC 40 ° CA. By stopping at such a position, as will be described in detail later, startability is improved when the engine is restarted.

  FIG. 6 is a flowchart showing a piston stop position detection control operation executed in the piston position detector 45 of the ECU 2 in accordance with the detection signals of the crank angle sensors 30 and 31 during the engine stop operation. When this detection control is started, based on the first crank angle signal CA1 (signal from the crank angle sensor 30) and the second crank angle signal CA2 (signal from the crank angle sensor 31), when the first crank angle signal CA1 rises. It is determined whether or not the second crank angle signal CA2 is low, or whether or not the second crank angle signal CA2 is high when the first crank angle signal CA1 falls (step S21). Accordingly, it is determined whether the phase relationship between the signals CA1 and CA2 during the engine stop operation is as shown in FIG. 7A or 7B, and the engine is rotated forward. Whether it is in a state or a reverse state is determined.

  That is, at the time of forward rotation of the engine, as shown in FIG. 7A, the second crank angle signal CA2 is generated with a phase delay of about a half pulse width with respect to the first crank angle signal CA1, thereby the first crank angle signal. The second crank angle signal CA2 becomes Low when CA1 rises, and the second crank angle signal CA2 becomes High when the first crank angle signal CA1 falls. On the other hand, during reverse rotation of the engine, as shown in FIG. 7B, the second crank angle signal CA2 is generated with a phase advance of about a half pulse width with respect to the first crank angle signal CA1, so On the contrary, the second crank angle signal CA2 becomes High when the first crank angle signal CA1 rises, and the second crank angle signal CA2 becomes Low when the first crank angle signal CA1 falls.

  Therefore, if the determination in step S41 is YES, the CA counter for measuring the crank angle change in the forward rotation direction of the engine is increased (step S22). If the determination in step S41 is NO, the CA counter is increased. Down (step S23). Then, after stopping the engine, the piston stop position is obtained by examining the measured value of the CA counter (step S24).

  The control operation when the engine is restarted will be described based on the flowcharts shown in FIGS. When this control operation is started, first, whether a predetermined engine restart condition (e.g., when the accelerator is operated for starting from a stopped state, when the battery voltage decreases, or when the air conditioner is activated) is established. If it is determined NO (NO in step S101) and it is confirmed that the engine restart condition is not satisfied, the process stands by as it is. If it is determined YES in step S101 and it is confirmed that the engine restart condition is satisfied, the in-cylinder position is determined based on detected values such as engine water temperature, stop time (elapsed time from automatic stop), and intake air temperature. The temperature is predicted by the in-cylinder temperature estimation unit 46 (step S102).

  Then, based on the stop position of the piston 13 detected by the piston position detection unit 45, the fourth cylinder 12D that first enters the compression stroke when the engine is stopped and the eighth cylinder 12H that has been in the expansion stroke from the time when the engine stopped. Is calculated (step S103). That is, the combustion chamber volumes of the fourth cylinder 12D and the eighth cylinder 12H are obtained from the stop position of the piston 13, and when the engine is stopped, the engine stops several times after the fuel injection is stopped. The fourth cylinder 12D is also filled with fresh air, and the interior of the fifth cylinder 12E and the eighth cylinder 12H is substantially atmospheric pressure while the engine is stopped. Will be required.

  Next, the fuel injection amount is calculated so that λ (excess air ratio) ≦ 1 with respect to the air amount of the fourth cylinder 12D calculated in step S103, and fuel injection is performed (step S104). The air-fuel ratio is obtained from the first air-fuel ratio map M1 for the compression stroke cylinder that is preset according to the stop position of the piston, and is set to λ ≦ 1, that is, the stoichiometric air-fuel ratio or richer than that, Even when the amount of air in the fourth cylinder 12 is relatively small, a sufficient amount of combustion energy for reverse operation is secured.

  Further, after the time set in consideration of the vaporization time of the fuel injected into the fourth cylinder 12D has elapsed, the cylinder 12D is ignited (step S105), and then the crank angle sensors 30, 31 are set. It is determined whether or not the piston 13 has moved (step S106) depending on whether or not the edge of the crank angle signal (rising or falling edge of the crank angle signal) has been detected (NO in step S106). If confirmed, reignition is repeatedly performed on the fourth cylinder 12D (step S107).

  If it is determined YES in step S107 and it is confirmed that the piston 13 has moved according to the detection signals of the crank angle sensors 30 and 31, the eighth cylinder 12H calculated in step S103, that is, the engine After calculating the fuel injection amount so that λ ≦ 1 with respect to the air amount of the cylinder in the expansion stroke from the stop point (step S108), the fuel injection is performed on the eighth cylinder 12H (step S109). .

  Next, λ (excess air ratio) with respect to the amount of air in the first cylinder 12A in the exhaust stroke when the engine is stopped and in the expansion stroke in accordance with the reverse rotation operation of the engine due to the combustion energy of the fourth cylinder 12D After calculating the fuel injection amount so that ≦ 1 (step S110), the fuel is injected into the first cylinder 12A (step S111).

  Further, ignition is performed when a predetermined delay time has elapsed after the fuel injection to the first cylinder 12A and the eighth cylinder 12H (step S112). The delay time is obtained from an ignition delay map M2 set in advance according to the stop position of the piston 13. By the initial combustion in the eighth and first cylinders 12H and 12A due to this ignition, the engine shifts from the reverse rotation state to the normal rotation state, and another cylinder that is in the compression stroke at the time of engine stop, that is, later when the engine is stopped. The piston 13 of the fifth cylinder 12E in the compression stroke moves to the top dead center side, and the internal air begins to be compressed.

  Next, taking into account the vaporization time of the fuel injected into the other cylinders in the expansion stroke when the engine is stopped, that is, the fifth cylinder 12E which has been in the expansion stroke after the engine is stopped, the fifth cylinder 12E After the fuel is injected (step S113), ignition is performed when the cylinder 12E exceeds the compression top dead center (step S114). The fuel injection amount in step S113 is obtained from the second air-fuel ratio map M3 for the compression stroke cylinder set in advance according to the stop position of the piston 13. Since the compression pressure near the compression top dead center of the fifth cylinder 12E is reduced by the latent heat of vaporization of the injected fuel, the compression top dead center can be easily exceeded.

  In step S115, the in-cylinder air density is estimated, and from the estimated value, the amount of air in the seventh cylinder 12G that has been in the compression stroke later when the engine is stopped is calculated. Next, an air-fuel ratio A / F correction value for preventing self-ignition in the seventh cylinder 12G is calculated based on the in-cylinder temperature estimated in step S102 (step S116). That is, when self-ignition occurs in the seventh cylinder 12G, a force (reverse torque) that pushes the piston 13 back to the bottom dead center before the compression top dead center is generated by the combustion, thereby exceeding the compression top dead center. This is undesirable because it consumes a lot of energy. Therefore, the air-fuel ratio is corrected to the lean side in order to suppress the reverse torque, and the air-fuel ratio A / F correction value is calculated in order to prevent compression self-ignition.

  Next, the fuel injection amount for the seventh cylinder 12G is calculated based on the air amount of the seventh cylinder 12G calculated in step S115 and the air-fuel ratio considering the air-fuel ratio A / F correction value calculated in step S116. (Step S117). Then, fuel is injected into the seventh cylinder 12G. In this fuel injection, the latter stage of the compression stroke is performed so as to reduce the energy required for exceeding the compression top dead center by reducing the compression pressure by the latent heat of vaporization. (Step S118), and the amount of delay is calculated based on the engine automatic stop period, the intake air temperature, the engine water temperature, and the like.

  Next, the ignition timing for the seventh cylinder 12G is delayed after the compression top dead center and ignited (step S119). With the above control, in the seventh cylinder 12G, the compression pressure is reduced to easily exceed the top dead center until the compression top dead center, and when the compression top dead center is passed, the torque in the forward direction is generated by the combustion energy. It is controlled to let you.

Thereafter, power generation of the alternator 28 is started in order to suppress the occurrence of the reverse torque (step S120). The target current value of the alternator 28 is set to be higher than normal by the power generation amount control unit 44 of the ECU 2, by increasing the load of the crank shaft 3 (engine load) by a generator of the alternator 28, rising racing of the engine rotational speed It is set to suppress. The engine speed increase referred to here means that the engine speed rapidly increases more than necessary immediately after the engine is started, which is undesirable because an acceleration shock may occur or the driver may feel uncomfortable. The increase in the engine speed is caused by the fact that the combustion energy in each cylinder immediately after starting is normal idle operation because the intake pressure (pressure downstream of the throttle valve 23) during the automatic stop period is substantially atmospheric pressure. It is caused by temporarily becoming larger than the combustion energy at the time.

  Next, it is determined whether or not the intake pressure detected by the intake pressure sensor 26 is higher than the intake pressure during normal idling when the idling stop is not performed (step S121). When it is confirmed that the engine is in a state in which it is likely to be blown up, the throttle valve 23 is driven to reduce the opening thereof compared with that during normal idling operation (step S122), thereby generating combustion energy. Suppress.

  Thereafter, it is determined whether or not the temperature of the catalyst 37 provided in the exhaust passage 22 is equal to or lower than the activation temperature (step S123). When the determination is YES, the target air-fuel ratio is set to a rich air-fuel ratio (λ ≦ 1). (Step S124) and by delaying the ignition timing after top dead center (step S125), the temperature increase of the catalyst 37 is promoted and the amount of combustion energy generated is suppressed.

  If it is determined NO in step S123 and it is confirmed that the temperature of the catalyst 37 is equal to or higher than the activation temperature, the target air-fuel ratio is set to a lean air-fuel ratio (λ> 1) (step S126). The process returns to step S121. By performing the lean air-fuel ratio combustion, it is possible to suppress the amount of combustion energy generated while suppressing fuel consumption. Then, when it is determined NO in step S121 and it is confirmed that there is no possibility that the engine speed will increase, the routine proceeds to normal control (step S129).

By executing the restart control, as shown in FIG. 8, first, fuel is supplied to the fourth cylinder 12D that has been in the compression stroke first among the plurality of cylinders 12D and 12G in the compression stroke when the engine is stopped. There first round of combustion by Rukoto be ignited is injected (in FIG. 8 (1)) is performed. In response to the combustion pressure of the first combustion (1), the piston 13 of the seventh cylinder 12G, which has been in the compression stroke after the engine is stopped, is pushed down to the bottom dead center side, whereby the engine is driven in the reverse direction. The Further, the piston 13 of the eighth cylinder 12H that is in the expansion stroke when the engine is stopped rises in accordance with the reverse rotation operation of the engine and the internal gas (air mixture) is compressed, and the exhaust stroke is later performed when the engine is stopped. The piston of the first cylinder 12A that has become exceeds the top dead center and shifts to the expansion stroke.

  Then, fuel is injected and ignited to the first cylinder 2A that has shifted from the exhaust stroke to the expansion stroke in accordance with the reverse rotation operation of the engine and to the eighth cylinder 12H that has been in the expansion stroke from the stop point of the engine. Second combustion ((2a), (2b) in FIG. 8) is performed. After the engine is driven in the forward rotation direction in accordance with the combustion pressure due to the second combustion (2a) and (2b), fuel is injected into the fifth cylinder 12E that has been in the expansion stroke later when the engine is stopped. When the engine is ignited, the third combustion ((3) in FIG. 8) is performed, and fuel is injected and ignited to the seventh cylinder 12G that has been in the compression stroke later when the engine is stopped. Thus, the fourth combustion ((4) in FIG. 8) is performed.

  In the multi-cylinder four-cycle engine in which the crank angle phase difference between the cylinders is set to 90 ° CA as described above and the plurality of cylinders have the same stroke, the fourth cylinder on the side that first comes to the compression stroke when the engine is stopped The first combustion (1) is performed at 12D, the engine is reversely rotated by a predetermined amount, and the pistons 13 of the first and eighth cylinders 12A and 12H in the expansion stroke are raised at this time, thereby compressing them. Since the second combustion (2a) and (2b) are performed in the cylinders 12A and 12H in a state where the pressure is sufficiently increased, the driving torque in the forward rotation direction of the engine is sufficiently generated. By performing the fourth combustion (4) in the other cylinder that was in the compression stroke when the engine was stopped, that is, the seventh cylinder 12G that was in the compression stroke after the engine was stopped, Gradually increasing engine rotational speed can be properly restarted the engine.

  That is, in the 8-cylinder 4-cycle engine as shown in the above embodiment, the crank angle phase difference between the cylinders is set to 90 ° CA so that the pair of cylinders have the same stroke. The cylinders 12D and 12G are stopped in the compression stroke. Of these cylinders 12D and 12G, the fourth cylinder 12D that has previously undergone the compression stroke has a smaller amount of air in the cylinder than the seventh cylinder 12G that has undergone the compression stroke later, and the reverse rotation operation of the engine. Sometimes the stroke tends to be large. Accordingly, the first combustion (1) is performed in the fourth cylinder 12D on the side where the stroke becomes large during the reverse rotation operation of the engine, so that the engine is reversely rotated by a predetermined amount, that is, any cylinder according to the reverse rotation operation. When the engine is reversely driven to the extent that the compression top dead center is exceeded, the pistons 13 of the first cylinder 12A and the eighth cylinder 12H in the expansion stroke are raised at this time, and the compression pressure is sufficiently increased. Thus, the second combustion (2a) and (2b) in the first cylinder 12A and the eighth cylinder 12H can be performed.

  The seventh cylinder 12G, which has been in the compression stroke later when the engine is stopped, has a larger amount of air in the cylinder than the fourth cylinder 12D, so the fourth combustion (4) in the seventh cylinder 12G. By performing the above, the combustion energy at the time tc when the second compression top dead center is reached in accordance with the forward rotation operation from the initial position when the engine is stopped (the time when the seventh cylinder 12G reaches the compression top dead center) tc. It can be secured sufficiently. Therefore, it is possible to effectively prevent the engine from being stopped due to the shortage of combustion energy at the time point t2, and to properly restart the engine.

  In particular, in the above embodiment, the engine between the second combustion (2a) and (2b) in the first and eighth cylinders 12A and 12H and the fourth combustion (4) in the seventh cylinder 12G is used. Since the third combustion (3) is performed in the fifth cylinder 12E that has been in the expansion stroke later when the engine is stopped, the engine is smoothly generated by generating combustion energy continuously in the normal rotation direction of the engine. Can be started.

  Note that when the engine is stopped, the fourth cylinder 12D on the side that is in the compression stroke first performs the first combustion (1) instead of the above-described embodiment, and is in the compression stroke when the engine is stopped. By causing combustion in at least one of the plurality of cylinders 12D and 12G, the engine is once operated in the reverse direction so that any cylinder exceeds the compression top dead center, and at the end of the reverse operation, the expansion stroke is performed. The engine may be driven in the forward rotation direction to start the engine by performing combustion in at least one of the plurality of cylinders 12A and 12H.

  In the above embodiment, the combustion is performed in all the cylinders in the expansion stroke at the time tb when the reverse rotation operation of the engine is completed, that is, the first cylinder 12A and the eighth cylinder 12H. Combustion energy at the time tc when the second compression top dead center is reached according to the forward rotation operation from the initial position can be sufficiently secured.

  Of the cylinders 12A and 12H, only the eighth cylinder 12H in the expansion stroke from the engine stop time ta may be burned after the reverse rotation of the engine is completed. In this case, combustion is performed in a state where the gas in the eighth cylinder 12H is sufficiently compressed in accordance with the reverse rotation operation of the engine. Therefore, the second cylinder 12H is in the expansion stroke at the time tb when the reverse rotation operation of the engine is completed. Combustion energy necessary for driving the engine in the forward direction can be obtained by burning only the eight cylinders 12.

  An experiment was conducted to examine the relationship between the stop position of the piston 13 of the cylinders 12H and 12E in the expansion stroke at the engine stop time ta and the engine rotation speed that increases in accordance with the combustion energy of the cylinders 12H and 12E. The data was obtained as shown in FIG. From this data, when the cylinders 12H and 12E are within the first third of the stroke (0 ° to 60 ° CA after the top dead center), the engine speed can be sufficiently increased. Can be restarted properly.

  However, when both the cylinders 12H and 12E are outside the first half of the stroke (0 ° to 60 ° CA after top dead center), that is, the pistons 13 of both cylinders 12H and 12E are respectively top dead center. When the engine is stopped in the range of 60 ° to 180 ° CA, the engine speed cannot be sufficiently increased, and it is difficult to restart the engine properly. This is because the position of the piston of the fourth cylinder 12D, which was previously in the compression stroke when the engine was stopped, is very close to the bottom dead center, and the first combustion (1) is performed in the fourth cylinder 12D to reverse the engine. This is because the stroke of the piston 13 at the time of driving is extremely small, the air in the first cylinder 12A and the eighth cylinder 12H in the expansion stroke cannot be sufficiently compressed, and the combustion energy cannot be sufficiently obtained. It is believed that there is.

  Therefore, if both of the cylinders 12H and 12E in the expansion stroke when the engine is stopped are outside the first half of the stroke (0 ° to 60 ° CA after top dead center), the engine is restarted. It is desirable to perform start assist by operating the starter motor from the start time.

  In addition, when the pistons 13 of the cylinders 12H and 12E in the expansion stroke at the engine stop time ta are outside the first third of the stroke, the air amount in the cylinders 12H and 12E is sufficiently secured. Therefore, when the engine is restarted, the fourth cylinder 12D stops the reverse rotation of the engine by causing the first combustion (1) to be performed, and the two cylinders that are in the expansion stroke from the time when the engine is stopped The engine may be restarted by first performing fuel at 12H and 12E and operating the engine in the forward rotation direction.

  As shown in the above embodiment, when the combustion is performed in another cylinder that is in the compression stroke at the engine stop time ta, that is, the fifth cylinder 12E that has been in the compression stroke after the engine is stopped, the ignition timing is set. If the engine is set after the compression top dead center and is delayed from the normal time, the engine 13 is ignited before the compression top dead center with the engine speed being very low immediately after the start of forward rotation of the engine. It is possible to prevent the occurrence of reverse torque that pushes back to the bottom dead center side, and to effectively prevent starting failure due to wasted energy for exceeding the compression top dead center.

  Further, in the above embodiment, when combustion is performed in the seventh cylinder 12G that has been in the compression stroke later when the engine is stopped, the ignition timing is delayed after the compression top dead center, so that ignition is performed. In the seventh cylinder 12G in which combustion is performed following the fifth cylinder 12E, the compression pressure can be reduced to easily exceed the top dead center until the compression top dead center, and the compression top dead center is passed. By generating the torque in the forward rotation direction by the combustion energy at this time, there is an advantage that the starting failure due to the waste of energy for exceeding the compression top dead center can be prevented more effectively.

  It should be noted that the intake valve closing timing of the fourth cylinder 12D that first became the compression stroke when the engine stopped was set after the bottom dead center, and was set near the bottom dead center as shown by the broken line in FIG. It is preferable to provide a valve timing adjusting mechanism for changing to the early closing state, and to change the intake valve closing timing of the fourth cylinder 12D to the early closing state from the time when the engine is stopped to the time when the engine is restarted. . According to this configuration, when the engine is operated in the reverse direction by performing the first combustion (1) in the fourth cylinder 12D when the engine is restarted, the intake valve is opened and the combustion gas leaks out. There is an advantage that can be surely prevented.

1 is a schematic cross-sectional view of an engine provided with a starter according to the present invention. It is explanatory drawing which shows the state which looked at the engine from the plane. It is a time chart which shows the change state etc. of the engine speed at the time of an engine stop. It is a flowchart which shows the first half part of control operation at the time of an engine stop. It is a flowchart which shows the latter half part of the control action at the time of an engine stop. It is a flowchart which shows detection control operation | movement of a piston stop position. It is explanatory drawing which shows the output signal of a crank angle sensor. It is a time chart which shows the combustion operation etc. at the time of engine restart. It is a flowchart which shows the first half of the control action at the time of engine restart. It is a flowchart which shows the middle part of the control action at the time of engine restart. It is a flowchart which shows the latter half part of the control action at the time of engine restart. It is a graph which shows the correspondence of a piston stop position and the rotational speed at the time of engine restart.

Explanation of symbols

12A-12H Cylinder 13 Piston 16 Fuel injection valve 41 Fuel injection control part (fuel injection control means)
45 Piston position detector (piston position detector)
46 In-cylinder temperature estimation unit (in-cylinder temperature estimation means)

Claims (7)

In a multi-cylinder four-cycle engine in which a crank angle phase difference between cylinders is set to 90 ° CA and a plurality of cylinders have the same stroke, when a predetermined automatic stop condition is satisfied, the fuel supply is stopped and the engine is stopped. And an engine starter that automatically restarts the engine by supplying fuel to at least the cylinder in the expansion stroke when the engine is stopped when the predetermined restart condition is satisfied. The engine is temporarily operated in the reverse direction by performing the first combustion in the cylinder that has been in the compression stroke first among the plurality of cylinders in the compression stroke when the engine is stopped, and the end point of the reverse operation in after actuation of the engine in the forward direction by causing at least one in the second combustion of the plurality of cylinders in the expansion stroke, the engine Engine starting system which is characterized in that by performing the third round of combustion in other cylinders in the compression stroke at the stop point and configured to start the engine. 2. The engine starter according to claim 1, wherein after the engine reverse rotation operation is finished, the second combustion is performed in the cylinder that is in an expansion stroke from the stop point of the engine. 3. The engine starter according to claim 1, wherein after the reverse rotation operation of the engine is finished, the second combustion is performed in all the cylinders in the expansion stroke . After the engine is operated in the forward rotation direction, when the third combustion is performed in another cylinder that is in the compression stroke when the engine is stopped, the ignition timing is delayed from the normal time. The engine starting device according to any one of claims 1 to 3 . 2. The starter motor is operated from the start of engine restart when all the cylinders in the expansion stroke when the engine is stopped have their pistons outside the first third of the stroke. The engine starter according to any one of -4. If all the cylinders that were in the expansion stroke when the engine was stopped and the pistons were outside the first third of the stroke , the engine would not be operated in the reverse direction when the engine was restarted. The engine starting device according to any one of claims 1 to 4 , wherein the engine is operated in a normal rotation direction by causing the first combustion in a cylinder in an expansion stroke . The intake valve closing timing of the cylinder became the first in the compression stroke when the engine is stopped, according to any one of claim 1 to 6, characterized in that to change the early closing state between restart beginning of the engine Engine starter.

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