JP2006160081A - Engine starter of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine starter of a vehicle for suitably restarting an engine when the restart condition is established during an automatic stop operation of the engine. <P>SOLUTION: When an automatic stop condition of the engine is established during travel of the vehicle, the control of putting an automatic transmission 50 into a neutral state and automatically stopping the engine is performed, and, when the restart condition of the engine is established in a final stage of the automatic stop control, it is determined whether the turbine rotation speed corresponding to the vehicle speed predicted by a turbine rotation speed prediction means 95 is higher than a preset reference speed. When it is determined to be higher, the control of shifting the automatic transmission 50 from the neutral state to the drive state, and then injecting fuel to restart the engine is performed by an automatic stop control means 93. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, when a preset engine automatic stop condition is satisfied, the fuel supply is stopped to automatically stop the engine, and the engine restart condition in the automatic stop state is satisfied. Further, the present invention relates to an engine starter for a vehicle that automatically restarts an engine by causing combustion in a cylinder that is automatically stopped in an expansion stroke.

Recently, in order to reduce fuel consumption and reduce CO ₂ emissions, the engine is automatically stopped during idle operation, and then automatically restarted when a restart condition such as a start operation is established. An engine starter configured to be developed has been developed. The present applicant has also proposed an engine starter that supplies fuel to a specific cylinder of an engine that is in an automatic stop state to ignite the engine, and instantly restarts the engine by the combustion energy (see, for example, Patent Document 1).

  In the above engine starter, the success or failure of the restart depends on the piston position when the engine is stopped. For example, as disclosed in Patent Document 1, the opening of the throttle valve is set during the engine stop operation period. By adjusting the piston position, the piston position is controlled within an appropriate range suitable for restarting the engine, that is, the engine is stopped within a predetermined crank angle range.

Further, in this type of engine starter, in order to further improve the fuel consumption reduction effect, so-called idle stop control is performed by cutting the fuel injection during the deceleration operation of the vehicle and shifting the engine to the automatic stop state as it is. Is known (see Patent Document 2).
JP 2004-124754 A JP-A-7-266932

  In the engine starting device described in Patent Document 1, in order to obtain a further improvement in fuel efficiency, the engine is automatically stopped from the decelerating running state of the vehicle and shifted to the idle stop state as in the device described in Patent Document 2. It is preferable to configure so that it can be made. However, in the engine starting device described in Patent Document 1, when the engine is shifted to the automatic stop state while the vehicle is traveling as described in Patent Document 2, the reverse driving force from the wheel side acts on the output shaft of the engine. Therefore, there is a problem that it is difficult to stop the piston within a predetermined appropriate range when the engine is stopped.

  In order to solve the above problems, an automatic transmission mechanism configured to be able to switch between a driving state in which the driving force of the engine is transmitted to the wheel side and a neutral state in which the transmission of the driving force is interrupted is provided during traveling of the vehicle. It is also possible to automatically stop the engine in a neutral state. However, the automatic transmission mechanism is configured to switch the power transmission state by intermittently (releasing and engaging) the friction element in accordance with hydraulic control, and when the friction element is in the released state, the automatic transmission mechanism is constant until it is engaged again. Therefore, when the engine restart condition is satisfied, for example, when the accelerator pedal is depressed during the automatic engine stop operation, the automatic transmission mechanism in the neutral state is quickly driven. This makes it difficult to switch to, and causes new problems such as deterioration in responsiveness during re-acceleration.

  In view of the above circumstances, the present invention is an improvement of a conventional engine starter, and further reduces fuel consumption while maintaining the characteristics of the starter, that is, the restartability of the engine. It is possible to provide an engine starter for a vehicle that can properly restart the engine when a restart condition is satisfied during the automatic engine stop operation.

  According to the first aspect of the present invention, when a preset automatic engine stop condition is satisfied, the fuel supply is stopped to automatically stop the engine, and the engine restart condition in the automatic stop state is An engine starter having an automatic stop control means for automatically restarting the engine by causing combustion in at least a cylinder that has been automatically stopped in the expansion stroke when it is established, and changing the speed according to the driving state of the vehicle An automatic transmission mechanism configured to automatically change the stage and switch the transmission state of power to the wheel side between a drive state and a neutral state, and a turbine rotation speed prediction means for predicting a turbine rotation speed corresponding to the vehicle speed; And the automatic stop control means sets the automatic transmission mechanism to a neutral position when an automatic engine stop condition is satisfied while the vehicle is running. When the engine restart condition is satisfied at the final stage of the automatic stop control, is the turbine rotation speed corresponding to the vehicle speed higher than a preset reference speed? If it is determined to be high, the automatic transmission mechanism is changed from the neutral state to the drive state, and after that, combustion is performed in the cylinder automatically stopped in the expansion stroke, and the engine is restarted. To do.

  According to a second aspect of the present invention, in the engine starter for a vehicle according to the first aspect, when the engine restart condition is satisfied at the final stage of the automatic stop control, the turbine rotation speed corresponding to the vehicle speed is predicted. When it is determined that the value is lower than the preset reference speed, the engine is restarted when it is confirmed that the engine has shifted from the reverse rotation state to the normal rotation state, and then automatically Control for changing the speed change mechanism from the neutral state to the drive state is executed by the automatic stop control means.

  According to a third aspect of the present invention, in the vehicle engine starter according to the second aspect, when the engine restart condition is satisfied at the final stage of the automatic stop control, the predicted value of the turbine rotational speed corresponding to the vehicle speed Is determined to be lower than a preset reference speed, the automatic stop control means executes control for injecting fuel for restart when it is confirmed that the engine has shifted to the reverse rotation state. It is configured.

  According to a fourth aspect of the present invention, in the engine starting device for a vehicle according to any one of the first to third aspects, the final stage of the automatic stop control is a final compression top dead at the time of the automatic engine stop. It is set in the period before the engine is stopped after the time point is exceeded.

  According to a fifth aspect of the present invention, in the vehicle engine starter according to any one of the first to fourth aspects, the automatic transmission mechanism is neutralized when an automatic engine stop condition is established while the vehicle is running. When the control for automatically stopping the engine is performed while the engine is in a state, the automatic stop control means executes the control to fill the flow passage connected to the friction element of the automatic transmission mechanism with the working fluid and to make the precharge state. It is.

  In the first aspect of the invention, when the automatic stop condition for the engine is satisfied, the automatic transmission mechanism is set to the neutral state so as to execute the control for automatically stopping the engine. Control that automatically stops the engine within a predetermined crank angle range suitable for restarting, for example, by stopping the supply at a predetermined timing, can be appropriately executed. Then, at the final stage of the automatic stop control in which the engine rotation speed has decreased due to the execution of the automatic stop control, the engine is restarted in a state where the turbine rotation speed predicted by the turbine rotation speed prediction means is higher than the reference speed. If the condition is satisfied, the automatic transmission mechanism is changed to the drive state, and then the fuel injection is restarted to restart the engine. Therefore, the reverse input from the turbine of the automatic transmission mechanism to the engine output shaft is performed. By using the driving force as the assist force, the restartability of the engine can be effectively improved.

  In the invention according to claim 2, in the final stage of the automatic stop control in which the engine rotation speed is reduced, the engine restart condition is established in a state where the turbine rotation speed predicted by the turbine rotation speed prediction means is lower than the reference speed. In such a case, since the engine is restarted after waiting for the engine to shift from the reverse rotation state to the normal rotation state, there is an advantage that the restartability can be effectively secured by utilizing the rotational inertia of the engine.

  In the invention according to claim 3, in the final stage of the automatic stop control in which the engine rotation speed has decreased, the engine restart condition is established with the turbine rotation speed predicted by the turbine rotation speed prediction means being lower than the reference speed. In this case, since the fuel for restarting is injected when the engine shifts to the reverse rotation state, the air-fuel mixture generated by this fuel injection is burned in a state where it is sufficiently compressed according to the reverse rotation operation of the engine. By doing so, there is an advantage that fuel energy for restarting the engine can be obtained effectively.

  According to the invention of claim 4, the prediction is made by the turbine rotational speed prediction means at the final stage of the automatic stop control set in the period before the engine stop after the time when the last compression top dead center is exceeded when the engine is automatically stopped. If the restart condition of the engine is satisfied when the turbine speed is higher than the reference speed, the fuel injection is restarted and the engine is restarted after the automatic transmission mechanism is changed to the drive state. Therefore, the reverse drive force input from the turbine makes it difficult to bring the stop position of the piston within an appropriate range and causes problems such as poor restartability. There is an advantage that the restartability of the engine can be effectively improved by using the reverse driving force input to the as an assisting force.

  According to the fifth aspect of the present invention, the engine is in the neutral state when the engine automatic stop condition is satisfied while the vehicle is running and the engine restart condition is satisfied during execution of the control for automatically stopping the engine. The switching time required for shifting the automatic transmission mechanism to the drive state can be shortened to effectively improve the switching response. Therefore, there is an advantage that the reacceleration responsiveness can be effectively improved when a reacceleration request is made during the execution of the control for automatically stopping the engine.

  1 and 2 show a schematic configuration of a four-cycle spark ignition engine according to an embodiment of the present invention. The engine includes an engine main body 1 having a cylinder head 10 and a cylinder block 11, and an engine control ECU 2 (see FIG. 9). The engine main body 1 includes a plurality of cylinders (four in the illustrated embodiment). Cylinders) 12A to 12D. Each of the cylinders 12A to 12D is fitted with a piston 13 connected to a crankshaft (output shaft) 3 via a connecting rod, and a combustion chamber 14 is formed above the piston 13.

  A spark plug 15 is provided at the top of the combustion chamber 14 of each of the cylinders 12 </ b> A to 12 </ b> D, and the plug tip faces the combustion chamber 14. Further, a fuel injection valve 16 that directly injects fuel into the combustion chamber 14 is provided at a side portion of the combustion chamber 14. The fuel injection valve 16 includes a needle valve and a solenoid (not shown). When a pulse signal is input, the fuel injection valve 16 is driven for a time corresponding to the pulse width at the pulse input timing to open the valve. It is comprised so that the quantity of fuel according to may be injected. The injection direction of the fuel injection valve 16 is set so as to inject fuel toward the vicinity of the spark plug 15. A fuel supply system is configured so that fuel is supplied to the fuel injection valve 16 via a fuel supply passage or the like by a fuel pump (not shown), and a fuel pressure higher than the pressure in the combustion chamber in the compression stroke can be applied. Has been.

  An intake port 17 and an exhaust port 18 are opened to the combustion chambers 14 of the cylinders 12A to 12D, and an intake valve 19 and an exhaust valve 20 are provided in these ports 17 and 18. The intake valve 19 and the exhaust valve 20 are driven by a valve operating mechanism including a camshaft and the like (not shown). As described later in detail, the opening / closing timings of the intake / exhaust valves 19 and 20 of the cylinders 12A to 12D are set so that the cylinders 12A to 12D perform a combustion cycle with a predetermined phase difference.

  An intake passage 21 and an exhaust passage 22 are connected to the intake port 17 and the exhaust port 18. As shown in FIG. 2, the downstream side of the intake passage 21 close to the intake port 17 is an independent branch intake passage 21a corresponding to each of the cylinders 12A to 12D. The upstream ends of the branch intake passages 21a are respectively It communicates with the surge tank 21b. A common intake passage 21c is provided upstream of the surge tank 21b, and an intake flow rate adjusting means including a throttle valve 23 driven by an actuator 24 is disposed in the common intake passage 21c. An air flow sensor 25 for detecting the intake flow rate and an intake pressure sensor 26 for detecting the intake pressure (negative pressure) are disposed on the upstream side and the downstream side of the throttle valve 23, respectively.

  The engine body 1 is also provided with an alternator (generator) 28 connected to the crankshaft 3 by a timing belt or the like. The alternator 28 is configured to be able to adjust the output voltage by controlling the current of the field coil (not shown), and based on the control signal from the ECU 2, the target corresponding to the electric load of the vehicle, the voltage of the vehicle battery, etc. The control of the generated current is executed.

  Further, the engine is provided with a cam angle sensor 32 that detects a specific rotational position of the camshaft and outputs it as a cylinder identification signal, and a water temperature sensor 33 that detects the coolant temperature of the engine. Input to the ECU 2 is made. Further, as shown in FIG. 9, the ECU 2 includes an accelerator sensor 34 that detects an accelerator opening corresponding to the accelerator operation amount of the driver, and a brake sensor 35 that detects that the driver has operated the brake. An oil temperature sensor 37 for detecting the oil temperature of the automatic transmission mechanism 50, which will be described later, a vehicle speed sensor 38 for detecting the vehicle speed, and an operating pressure sensor 39 for detecting an operating pressure corresponding to each friction element in the automatic transmission mechanism 50. Each detection signal to be output is input.

  Further, as shown in FIG. 3, the engine body 1 has a crankshaft 3 that is an output shaft thereof connected to an automatic transmission mechanism 50. The automatic transmission mechanism 50 includes a torque converter 51 connected to the crankshaft 3 and a multi-stage transmission mechanism 52 connected to a turbine shaft 59 that is an output shaft of the torque converter 51, and includes a plurality of speed change mechanisms 52 included therein. By switching the friction element intermittently, it is possible to switch between a driving state in which the driving force of the engine body 1 is transmitted to the wheel side and a neutral state in which the transmission of this driving force is interrupted.

  The torque converter 51 includes a pump cover 53 coupled to the crankshaft 3, a pump impeller 54 formed integrally with the pump cover 53, a turbine 55 installed so as to face the pump impeller 54, and a one-way clutch between them. And a stator 58 attached to the case 57 via 56. The space in the pump cover 53 is filled with oil (working oil) as a working fluid, and the driving force of the pump impeller 54 is transmitted to the turbine 55 through the working oil. A driving force is transmitted to and from the multi-stage transmission mechanism 52 via a turbine shaft 59 connected to the turbine 55.

  The case 57 is provided with a turbine rotation sensor 36 that detects the rotational speed of the turbine 55 in a state of facing the outer peripheral surface of the forward clutch 67 that rotates integrally with the turbine shaft 59. The turbine rotation sensor 36 has a tip portion opposed to the outer peripheral surface of the drum of the forward clutch 67, and periodically generates an induced voltage as the spline-like irregularities provided on the outer peripheral surface of the drum rotate. By detecting the change, the rotational speed of the turbine 55 corresponding to the rotational speed of the turbine shaft 59 is detected.

  A hollow rotary shaft 60 is connected to the pump impeller 54, and an oil pump 61 is attached to the rear end portion (the end portion on the opposite side of the engine main body 1 side) of the shaft 60. The automatic transmission mechanism 50 is provided with an electric oil pump 62 (see FIG. 5) different from the oil pump 61, and these oil pumps 61, 62 are connected to a hydraulic control mechanism 63 described later. Then, in a later-described shift control means 92 (see FIG. 9) provided in the ECU 2, switching control between the oil pump 61 and the electric oil pump 62 is performed, and an oil path (distribution) of the hydraulic control mechanism 63 is performed. The friction elements 67 to 71, which will be described later, are intermittently engaged (engaged and released) by performing switching control of the road), setting control of the line pressure, and the like.

  Here, the electric oil pump 62 that is separate from the oil pump 61 is provided because the oil pump 61 causes a desired line pressure because the engine rotation speed is not sufficient when the engine is stopped or at the start of the engine. This is to secure a desired line pressure when it is difficult to supply the oil. From this viewpoint, the switching timing between the oil pump 61 and the electric oil pump 62 is set.

  Between the pump cover 53 and the turbine 55, a lock-up clutch 64 that directly connects the crankshaft 3 and the turbine 55 via the pump cover 53 is provided. The lock-up clutch 64 is connected to the oil pump 61 and the electric oil pump 62 via a hydraulic control mechanism 63, and various solenoid valves provided in the hydraulic control mechanism 63 are controlled to be turned on / off, thereby causing an oil passage. Is switched so that the lock-up clutch 64 is engaged.

  On the other hand, the multi-stage transmission mechanism 52 includes first and second planetary gear mechanisms 65 and 66 and fastening elements (a plurality of friction elements 67 to 71 such as clutches and brakes) for switching a power transmission path including the planetary gear mechanisms 65 and 66. And a one-way clutch 72), and according to a shift range (D range, N range, R range, etc.), the fastening elements 67 to 71 are intermittently switched to a forward speed, a neutral state or a reverse speed, and the vehicle travels. The forward speed gear stage is automatically switched in accordance with the state.

  The first and second planetary gear mechanisms 65, 66 are sun gears 65a, 66a, a plurality of planet gears 65b, 66b arranged around and meshing with the sun gears 65a, 66a, and the planet gears, respectively. A carrier 65c, 66c for supporting 65b, 66b, and ring gears 65d, 66d arranged so as to surround the planet gears 65b, 66b and meshing with each other, and the ring gear 65d of the first planetary gear mechanism 65; The carrier 66c of the second planetary gear mechanism 66 is connected, and the carrier 65c of the first planetary gear mechanism 65 and the ring gear 66d of the second planetary gear mechanism 66 are connected to each planetary gear mechanism 65, 66 is configured to be interlocked.

  Specifically, the forward clutch 67 interposed between the turbine shaft 59 and the sun gear 65a of the first planetary gear mechanism 65 as the friction element, and between the turbine shaft 59 and the sun gear 66a of the second planetary gear mechanism 66 are used. The intervening reverse clutch 68, the 3-4 clutch 69 interposed between the turbine shaft 59 and the carrier 66c of the second planetary gear mechanism 66, and the sun gear 66a of the second planetary gear mechanism 66 are fixed 2-4. A brake 70 and a low reverse brake 71 or the like interposed in parallel between the planetary gear mechanisms 65 and 66 and the case 57 are provided. The one-way clutch 72 is configured to allow only rotation in one direction (the rotation direction of the crankshaft 3) of the carrier 65c and the ring gear 66d, and lock and prevent rotation in the reverse direction. . When these fastening elements 67 to 72 are intermittently connected, the power transmission path connected to the output gear 73 is changed or disconnected. As the output gear 73 rotates, the driving force is transmitted to the left and right axles 78 and 79 via the wheels, that is, through the transmission gears 74, 75 and 76 and the differential mechanism 77.

  The relationship between the intermittent state of these fastening elements 67-72 and a gear stage is shown in FIG. In FIG. 4, a circle indicates a state in which the respective fastening elements 67 to 72 are fastened, and a non-mark indicates a state in which they are released or unlocked. In the R range, the reverse clutch 68 and the low reverse brake 71 are fastened. In the N range (neutral state), all the fastening elements 67 to 72 are released or unlocked. At the first speed in the D range (drive state), the forward clutch 67 is engaged and the one-way clutch 72 is locked, and at the second speed, the forward clutch 67 and the 2-4 brake 70 are engaged. In the third speed, the forward clutch 67 and the 3-4 clutch 69 are engaged, and in the fourth speed, the 3-4 clutch 69 and the 2-4 brake 70 are engaged, respectively. ing.

  The friction elements 67 to 71 are connected to the oil pump 61 and the electric oil pump 62 through a hydraulic control mechanism 63 (see FIG. 5) similarly to the lock-up clutch 64. Then, the first and second shift solenoid valves 83 and 84, which will be described later, and the first to third duty solenoid valves 85 to 87 are driven to switch the oil passages, change the hydraulic pressure, etc. The control for intermittently connecting 71 is executed in a shift control means 92 provided in the ECU 2.

  That is, as shown in FIG. 5, a line 81 (oil passage) connected from the oil pump 61 to a hydraulic chamber (not shown) of the friction elements 67 to 71 and a downstream side of the pumps 61 and 62 in the line 81 are arranged in the vicinity. First and second shift solenoid valves 83 and 84 (hereinafter simply referred to as first and second SVs) for turning ON / OFF various regulator valves 82 for adjusting the line pressure provided and various valves for switching lines communicating with the pumps 61 and 62. ) And first to third duty solenoid valves 85 to 87 (hereinafter simply referred to as first to third DSVs) for adjusting the operating pressure based on the duty value output from the shift control means 92 of the ECU 2. A circuit is provided in the hydraulic control mechanism 63. In addition, 1st, 2nd SV83,84 and 1st-3rd DSV85-87 are comprised as a three-way valve. A switching valve 91 that selectively switches the oil supply source between the oil pump 61 and the electric oil pump 62 is provided on the oil passage connecting the pumps 61 and 62 and the line 81.

  Then, based on the vehicle speed, the throttle opening, the engine rotation speed, the turbine rotation speed, and the like, the above-mentioned various valves are operated to intermittently connect the friction elements 67 to 71, thereby switching the shift stage of the automatic transmission mechanism 50 to the vehicle speed or the like. Control for automatically selecting the corresponding gear is configured to be executed in the shift control means 92 of the ECU 2. FIG. 6 shows a switching map of the automatic transmission mechanism 50 according to the vehicle speed and the throttle opening. FIG. 7 shows combinations of operating states corresponding to the respective gear speeds of the solenoid valves 82 to 86. In FIG. 7, the circles indicate that the first and second SVs 82 and 83 are turned on and the first to third DSVs 84 to 86 are turned off, both of which connect the upstream line to the downstream line. The state where the pressure is supplied directly to the downstream side indicates that the first and second SVs 83 and 84 are turned off and the first to third DSVs 85 to 87 are turned on, both of which block the upstream line. Thus, the downstream line is drained.

  For example, the operation of the hydraulic control mechanism 63 when the first speed is selected for the multi-stage transmission mechanism 52 will be described. As shown in FIGS. 5 and 7, only the third DSV 87 is operated, so that the upstream side An operating pressure is generated using the line pressure as an original pressure, and this operating pressure is supplied to the lockup control valve 88 via the line 81b. At this point, the spool of the lock-up control valve 88 is positioned on the right side, so that forward clutch pressure (operating pressure) is further supplied to the hydraulic chamber of the forward clutch 67 via the forward clutch line 81c. Accordingly, forward clutch 67 is engaged.

  The time change of the operating pressure supplied to the forward clutch 67 will be described with reference to FIGS. 5 and 8. From the time point t0 when the third DSV 87 is in the operating state, the downstream line 81b and the forward clutch line 81c of the third DSV 87. The hydraulic oil of each line 81b, 81c, that is, the operating pressure of the forward clutch 67 increases at time t1 when the hydraulic oil is supplied to the line 81b, 81c. At the time t2 when the operating pressure reaches the predetermined value P1, the piston (not shown) of the forward clutch 67 in the disengaged position starts to move in the fastening direction against a return spring (not shown). Then, when the operating pressure reaches the predetermined value P2, the clutch plate of the forward clutch 67 moves to the contact position, and the movement of the forward clutch 67 is restricted at the time t3 when the gap between the clutch plates becomes zero. As a result, the increase rate of the operating pressure increases, and the state shifts from the state in which the forward clutch 67 is slipping to the state in which the transmission driving force gradually increases.

  Then, at the time t4 when the operating pressure reaches the predetermined pressure P3, the accumulator 90 is operated, so that the increase rate of the operating pressure is reduced and the rapid torque fluctuation (torque shock) is suppressed, and the fastening operation proceeds. To do. Further, until the time point t5 when the capacity of the accumulator 90 is full, the forward clutch 67 is in a completely engaged state, and further increases the operating pressure to cope with fluctuations in transmission driving force due to sudden torque fluctuations. A sufficient amount of fastening is possible. Even when a gear other than the first gear is selected, the operation is the same as that of the conventional automatic transmission mechanism.

  In the automatic transmission mechanism 50, when the hydraulic pressure control mechanism 63 is controlled by the transmission control means 92 and the neutral state in which the transmission of the driving force to the wheel side is cut off is established, the friction elements 67 to 71 are engaged as necessary. It is configured so that it can be set to the immediately preceding state, the so-called precharge state. That is, in this type of automatic transmission mechanism 50, a shift operation or the like is generally performed by supplying the hydraulic pressure generated by the hydraulic control circuit to the hydraulic chambers of the friction elements 67 to 71 during a shift or engagement operation. However, even if an operating pressure is immediately generated after the start of a shift operation or the like and supplied to the hydraulic chambers of the friction elements 67 to 71, each line of the hydraulic control circuit and the hydraulic chambers of the friction elements 67 to 71, etc. If the hydraulic oil is removed from the hydraulic pressure or the operating pressure is reduced, the lines and hydraulic chambers are filled with the hydraulic oil during the shifting operation and the friction elements 67 to 71 are moved from the released state to the engaged state. There is a problem that a predetermined time lag occurs and the fastening operation of the friction elements 67 to 71 is delayed.

  Therefore, in the present embodiment, the electric oil pump 62 is operated when each of the friction elements 67 to 71 is released and the automatic transmission mechanism 50 is in the neutral state at least during the automatic stop operation period of the engine described later. By filling the oil passage (flow passage) with the working oil (working fluid), until at least one of the friction elements 67 to 71 is moved from the predetermined release position in the fastening direction and the driving force is transmitted. The slip state (pre-charge state immediately before fastening) is not reached. As a result, the rising period of the operating pressure, that is, the movement time (t0 to t3) of the friction elements 67 to 71 is omitted, and the drive is started from the time when the control signal for shifting the automatic transmission mechanism 50 from the neutral state to the drive state is output. For example, the switching time until the switching to the state is completed is shortened from the period A (= t0 to t5) in FIG. 8 to the period B (= t3 to t5).

  For example, when the forward clutch 67 is in the precharged state, the control for adjusting the operating pressure to the precharged pressure by the third DSV 87 is executed by the shift control means 92 provided in the ECU 2. In the present embodiment, this precharge pressure is applied when the forward clutch 67 is moved to the substantially engaged position and is in the slip state, or when the forward clutch 67 is slightly displaced from the engaged position in the release direction. The operating pressure, that is, a value slightly lower than the operating pressure P2 is set.

  As shown in FIG. 9, the ECU 2 receives signals from the sensors 25, 26, 30 to 34, controls the fuel injection amount and injection timing for the fuel injection valve 16, and the ignition timing for the spark plug 15. And the throttle opening control for the actuator 24 of the throttle valve 23 are output, and further, a signal for controlling the amount of power generation is output to the regulator circuit 28a of the alternator 28 to control the operating state of the engine. It has a function to do. Further, the shift control means 92 provided in the ECU 2 receives signals from the sensors 25, 26, 30 to 39 and controls to switch the supply source of the hydraulic control mechanism 63 between the oil pump 61 and the electric pump 62. A signal is output to the switching valve 91 and a control signal for adjusting the operating pressure of each of the friction elements 67 to 71 is output to the hydraulic control mechanism 63 (specifically, a solenoid valve included therein). Yes.

  Then, the ECU 2 automatically stops the engine by stopping the supply of fuel when a predetermined engine stop condition is satisfied, for example, when idling in a state where the vehicle is stopped and during deceleration traveling of the vehicle. Thereafter, an automatic stop control means 93 is provided for executing control for automatically restarting the engine with energy generated by combustion of the engine when a predetermined engine restart condition is satisfied, for example, when an occupant performs an accelerator operation.

  Specifically, first, the cylinder 12 that is in the compression stroke when the engine is stopped (hereinafter referred to as the compression stroke cylinder 12 when the engine is stopped. The other cylinders 12 are also assumed to have the stroke when the engine is stopped). Combustion is performed, the piston 13 is pushed down, the piston 13 of the expansion stroke cylinder 12 at the time of stop is raised, and the engine is reversed to increase the in-cylinder pressure. Fuel is injected to ignite and burn. In this way, the automatic stop control means 93 is configured to execute the control for restarting the engine by increasing the combustion energy in the stop expansion stroke cylinder 12 and ensuring the stroke of the cylinder 12. ing.

  In order to restart the engine only with the combustion energy of the engine body 1 as described above, it becomes a problem how to maximize the combustion energy in the expansion stroke cylinder 12 at the time of stop. It is sometimes necessary to ensure an appropriate amount of air so that the piston 13 is stopped in a predetermined range and sufficient combustion energy is obtained in the stop-time compression stroke cylinder 12 and the stop-time expansion stroke cylinder 12. Therefore, with reference to the expansion stroke cylinder 12 at the time of stop, a predetermined range (for example, after the compression top dead center) that is slightly lower than the center of the stroke, that is, a position where the crank angle after compression top dead center is 90 ° CA. If the piston 13 can be stopped within a range in which the crank angle is 100 ° to 120 ° CA), a predetermined amount of air is secured in the compression stroke cylinder 12 at the time of stop, and the engine is slightly reversed by the initial combustion. This makes it possible to ensure sufficient combustion energy in the stop-time expansion stroke cylinder 12.

  There are various specific control methods for stopping the piston 13 at an appropriate position when the engine is automatically stopped. Here, the expansion stroke cylinder 12 and the compression stroke when the engine is stopped are controlled by controlling the opening of the throttle valve 17. While adjusting the compression reaction force due to the air in the cylinder 12 and controlling the power generation amount of the alternator 26 in the process of automatically stopping the engine, the rotational speed of the crankshaft 3 is used to adjust the rotational speed of the engine. Accordingly, after stopping the fuel injection, the engine speed is decreased along a reference line determined in advance through experiments or the like.

  Then, as shown in FIG. 10, the automatic stop control means 93 releases the friction elements 67 to 71 at the time T0 when the engine automatic stop condition is satisfied, thereby bringing the automatic transmission mechanism 50 into the drive state (D Range) to neutral state (N range). Further, when executing the control for automatically stopping the engine with the automatic transmission mechanism 50 in the neutral state, the friction elements 67 to 71 of the automatic transmission mechanism 50 are in the precharge state immediately before the engagement. In this way, by setting the automatic transmission mechanism 50 to the neutral state during the automatic stop operation period of the engine, the influence of the reverse driving force from the wheel side is eliminated and the stop position of the piston 13 is prevented from deviating from the proper range. In addition, by setting each of the friction elements 67 to 71 in a precharged state, even when the engine restart condition is satisfied during the execution of the control for automatically stopping the engine, the restart response can be improved. Can be done.

  Further, the automatic stop control means 93 stabilizes the opening K of the throttle valve 23 at, for example, 15% when executing the automatic stop control of the engine, and then at the time T1 when a predetermined time has elapsed, the engine speed Ne. When it is confirmed that the boost pressure Bt is within a predetermined control appropriate range, the fuel injection to each cylinder 12 is stopped. When the fuel injection is stopped at this time T1, the kinetic energy of the crankshaft 3 or the like is consumed by mechanical loss due to frictional resistance or pump work of each cylinder 12A to 12D, so that the crank of the engine body 1 The shaft 3 is inertial and makes several revolutions. In a 4-cylinder 4-cycle engine, the shaft 3 stops after reaching the compression top dead center of about 10 times.

  The stop position of the piston 13 is substantially determined by the balance of the compression reaction force in the stop-time compression stroke cylinder 12C and the stop-time expansion stroke cylinder 12A, and is affected by the frictional resistance of the engine, and the last compression top dead center. It also changes depending on the rotational inertia of the engine at the time T4 when it exceeds the value, that is, the level of the engine rotational speed Ne. Therefore, in order to stop the piston 13 of the expansion stroke cylinder 12A in the expansion stroke within the appropriate range suitable for restart when the engine automatically stops, first, the stop expansion stroke cylinder 12A and the stop compression stroke cylinder are used. The compression reaction force of 12C is sufficiently large, and the compression reaction force of the expansion stroke cylinder 12A at the stop time is larger than the compression reaction force of the compression stroke cylinder 12C at the stop time by a predetermined value or more. It is necessary to adjust the intake flow rate.

  For this reason, in this embodiment, the stop-time expansion stroke cylinder 12A is set by setting the opening K of the throttle valve 23 to a large value (for example, about 30% of the fully open position) at the fuel injection stop time T1. At a time T2 when it is confirmed that the engine speed Ne has decreased below a preset reference value after a predetermined amount of air has been sucked into both the stop compression stroke cylinder 12C, the throttle valve 23 is turned on. The intake air amount is adjusted by closing and reducing the opening K.

  By the way, the fuel injection is stopped at the time T1 when the rotational speed Ne of the engine reaches a predetermined speed, and the cylinders of the engine that rotate due to inertia are maintained so as to keep the throttle valve 23 open for a predetermined period thereafter. When the top dead center rotational speed ne when the piston 13 provided in 12A to 12D passes through the compression top dead center is measured and the piston position of the expansion stroke cylinder 12A at the time of engine stop is examined, the engine is stopped. If the top dead center rotational speed ne at the sixth to second before is within a predetermined range as shown by hatching in FIG. 11, the stop position of the piston 13 is in a range suitable for engine restart ( It was experimentally confirmed that it entered 100 ° to 120 ° CA after compression top dead center.

  Accordingly, the automatic stop control means 93 maintains the target rotational speed Ne of the alternator 28 at the fuel injection stop time T1 in order to maintain the engine rotational speed Ne at a speed at which the piston 13 can be controlled to stop at an appropriate position. Is set to 0, for example, and at the time T2 when the engine speed Ne drops below the reference value, control is performed to increase the target generated current Ge of the alternator 28 to a preset initial value, and then the engine is dead At time T3 when the point rotational speed ne falls within the predetermined range, the target power generation current Ge of the alternator 28 is decreased to a value corresponding to the decreased state of the engine rotational speed Ne to adjust the rotational resistance of the crankshaft 3, and the engine A reference set based on experiments conducted in advance by changing the external load of the engine in accordance with the degree of decrease in the engine speed Ne. It is configured to perform control to reduce the engine rotational speed Ne along in.

  Summarizing the control operation when the engine is automatically stopped, the automatic stop control means 93 controls the opening degree of the throttle valve 23 to automatically stop the expansion stroke cylinder 12A and the compression stroke when the engine is stopped. While adjusting the compression reaction force caused by the air in the cylinder 12C and controlling the amount of power generated by the alternator 26 during the automatic engine stop process, the rotational resistance Ne of the crankshaft 3 is changed to finely adjust the rotational speed Ne of the engine. Thus, the control for lowering the engine rotational speed Ne after the stop of the fuel injection along a predetermined reference line, that is, the control for stopping the piston 13 in a predetermined appropriate range is performed (see FIG. 10).

  In this type of engine starter, when a predetermined restart condition is satisfied during the execution of the automatic stop control, it is desired to quickly restart the engine to improve the re-acceleration response of the vehicle. It is preferable that the automatic stop control of the engine is stopped to restart the fuel injection, and the automatic transmission mechanism 50 is switched from the neutral state to the drive state so that reacceleration performance corresponding to the accelerator operation can be obtained. . When the vehicle speed is high to some extent when the restart condition is satisfied and the automatic transmission mechanism 50 is in an operating state in which the turbine rotation speed can be increased to a predetermined value or more by switching from the neutral state to the driving state. When the automatic transmission mechanism 50 is switched to the drive state at the time when the fuel injection is resumed, the crankshaft 3 is rotationally driven according to the reverse driving force input from the turbine 55 to restart the engine. As a result, sufficient assist power can be obtained.

  By the way, when the restart condition of the engine is satisfied when the vehicle speed is relatively low at the final stage of the automatic stop control, the automatic transmission mechanism 50 is switched from the neutral state to the drive state, and the gear position is changed to the vehicle speed. Even if set to a value corresponding to the above, it is not possible to input such a large reverse driving force from the turbine 55 to the crankshaft 3 of the engine body 1, and a sufficient assist force required to restart the engine can be obtained. There may not be. For this reason, in the present embodiment, when the engine is restarted at the final stage of the automatic stop control, the speed of the automatic transmission mechanism 50 is set to a value corresponding to the vehicle speed by setting the shift speed to a value corresponding to the vehicle speed. It is determined whether or not the rotational speed is higher than a preset reference speed. If it is determined that the rotational speed is low, the automatic transmission mechanism 50 is changed to the drive state and the gear position is set to a value that corresponds to the vehicle speed. By setting to a low gear, for example, the first gear, the fuel injection is resumed with the reverse driving force input from the turbine 55 to the crankshaft 3 of the engine body 1 acting as the assisting force for restarting. By doing so, the engine is restarted.

  When the vehicle speed is in a considerably low state at the final stage of the automatic stop control, the automatic transmission mechanism 50 is changed to the drive state, and the shift stage is set to a shift stage lower than a value corresponding to the vehicle speed. However, there is a possibility that sufficient assist force for restarting the engine cannot be obtained. For this reason, in this embodiment, when the engine is restarted in the final stage of the automatic stop control, the speed of the automatic transmission mechanism 50 is set to a speed lower than a value corresponding to the vehicle speed, thereby increasing the vehicle speed. It is determined whether or not the turbine rotation speed corresponding to the value is lower than the reference speed. It is configured to restart the engine when it is confirmed.

  On the other hand, when the engine restart condition is satisfied before the final stage of the automatic stop control during the execution of the control for automatically stopping the engine, that is, in the operation region where the engine speed is sufficiently high, the reverse driving force is Since the engine can be restarted without using the engine as an assist force, the automatic transmission mechanism 50 is switched from the neutral state to the drive state when the restart condition is confirmed, and the fuel is By restarting the injection, it is possible to restart the engine.

  Further, since the engine rotation speed increases after the engine restarts, the engine rotation speed when the automatic transmission mechanism 50 is switched from the neutral state to the drive state becomes relatively higher than the turbine rotation speed. In this case, a large drive torque is transmitted from the crankshaft 3 of the engine body 1 to the turbine shaft 59 via the torque converter 51, thereby generating a torque shock due to a sudden change in the speed of each part of the drive system. Will do. In particular, if a predetermined time is required from the time when the engine restart is started to the time when the operation of switching the automatic transmission mechanism 50 from the neutral state to the drive state is completed, the engine speed increases during that time, thereby increasing the speed. There is a tendency for torque shock to occur more easily.

  For this reason, in this embodiment, the engine speed prediction means 94 for predicting the engine speed at the time when the automatic transmission mechanism 50 is switched from the neutral state to the drive state, and the automatic transmission mechanism 50 are switched from the neutral state to the drive state. The ECU 2 is provided with a turbine rotational speed predicting means 95 for predicting the turbine rotational speed that changes depending on the situation, and the engine restart condition is established before the final stage of the automatic stop control during execution of the control for automatically stopping the engine. When it is determined that the restart condition is satisfied, the engine automatic stop control is stopped, the automatic transmission mechanism 50 is changed from the neutral state to the drive state, and the engine speed is increased. The predicted value of the engine speed predicted by the prediction means 94 is the target value. Whether or not it is relatively higher than the predicted value of the turbine rotational speed predicted by the engine rotational speed predicting means 95. By executing this at step 93, the occurrence of the torque shock is suppressed.

  The turbine rotational speed predicting means 95 uses the reverse driving force transmitted from the axles 78 and 79 when the operation of switching the automatic transmission mechanism 50 from the neutral state to the driving state is completed based on the detection signal of the vehicle speed sensor 38 or the like. It is configured to predict a turbine rotational speed that changes accordingly. Specifically, the turbine rotation speed prediction means 95 obtains a deceleration based on the vehicle speed detected by the vehicle speed sensor 38, and determines the gear position according to the vehicle speed based on the map of FIG. The automatic transmission mechanism 50 switches from the neutral state to the drive state from the start point of the restart when the vehicle speed, deceleration, gear ratio of the gear already input at the gear stage, tire diameter input in advance, gear ratio of the differential mechanism 77 The predicted value of the turbine rotation speed is calculated by applying a time (switching time) to a predetermined time point to a predetermined mathematical formula.

  Further, the turbine rotation speed prediction means 95 sets the automatic transmission mechanism 50 to neutral at this point when a restart condition is established at the final stage of the control for automatically stopping the engine based on a detection signal of the vehicle speed sensor 38 or the like. The turbine rotational speed that becomes a value corresponding to the vehicle body by switching from the state to the drive state, specifically, the first turbine rotational speed when the shift stage of the automatic transmission mechanism 50 is set to a value corresponding to the vehicle speed, and the automatic transmission It has a function of predicting the second turbine rotation speed when the gear position of the mechanism 50 is set to a gear position lower than the value corresponding to the vehicle speed.

  On the other hand, the engine speed prediction means 94 determines the current time based on the detection results of the crank angle sensors 30 and 31 when the restart condition is satisfied and the engine is restarted during execution of the control for automatically stopping the engine. The engine speed is detected, and the engine speed at the time when the automatic transmission mechanism 50 has completed the switching to the drive state is predicted based on the engine speed and the switching time of the automatic transmission mechanism 50. ing.

  A control operation when the engine is automatically stopped and restarted by the automatic stop control means 93 of the ECU 2 will be described based on the flowcharts shown in FIGS. FIG. 12 shows a main flowchart of the automatic stop and restart control of the engine. When this control operation starts, it is first determined whether or not a fuel injection stop condition (hereinafter referred to as FC condition) is satisfied (step S1). This FC condition is a condition for determining whether or not to stop the fuel injection at the time of deceleration, and specifically, a determination for stopping the fuel injection in which the engine rotation speed Ne is set to about 1200 rpm which is set in advance. When the vehicle speed is greater than the reference value, the vehicle speed is equal to or higher than a predetermined value (for example, 10 km / h), and the accelerator sensor 34 is in the OFF state, it is determined that the FC condition is satisfied.

  If YES is determined in step S1, it is determined whether or not the lockup clutch 64 of the torque converter 51 is in the released non-lockup region based on the vehicle speed detected by the vehicle speed sensor 38 ( Step S2). If it is determined NO in step S2, that is, when the vehicle in which the accelerator sensor 34 is in the OFF state is decelerated, the lockup clutch 64 may be engaged because the vehicle speed is, for example, 48 km / h or higher. If it is confirmed, in order to improve fuel efficiency, fuel injection to each cylinder 12 is stopped and FC control during deceleration is executed (step S5), and then the process returns.

  When it is determined YES in step S2 and it is confirmed that the lock-up clutch 64 of the torque converter 51 is in the released non-lock-up region, the engine idle stop control shown in FIG. In step S3), a normal engine control state is entered (step S4). In the execution state of the deceleration FC control in step S5, YES is determined in steps S1 and S2, the FC condition is satisfied, and the automatic transmission mechanism 50 has shifted from the lockup region to the non-lockup region. Is confirmed, engine idle stop control, which will be described later, is executed in the fuel injection stopped state.

  Next, returning to step S1, if it is determined NO in step 1, that is, if the FC condition is not satisfied, it is determined whether or not the deceleration-time FC control is currently being executed (step S1). S6) If NO is determined, the process directly returns. On the other hand, if it is determined as YES in step S6 and it is determined that the deceleration-time FC control is being executed, the routine proceeds to the normal control state of the engine and fuel injection is returned (step S4).

  Here, the engine idle stop control executed in step S3 of the flowchart shown in FIG. 12 will be described based on the flowchart of FIG. When this control operation starts, the automatic transmission mechanism 50 is first switched from the drive state (D range) to the neutral state (N range), and hydraulic oil is supplied to the oil passages connected to the friction elements 67 to 71 of the automatic transmission mechanism 50. Precharge control for filling is executed (step S51). In this way, the automatic transmission mechanism 50 is set to the neutral state, and the friction elements 67 to 71 are set to the precharged state, whereby the friction elements 67 to 71 are quickly fastened when a restart condition described later is satisfied. It is possible to prevent the driving force from being transmitted between the crankshaft 3 and the axles 78 and 79 during the automatic engine stop control, and to stop the piston 13 within a predetermined appropriate range. Become.

  Next, after the opening degree K of the throttle valve 23 is adjusted to 15% in order to stabilize the boost pressure Bt (step S52), an idle stop condition that can stop the piston 13 within a predetermined appropriate range is established. It is determined whether or not (step S53). This idle stop condition is a condition for finally confirming whether or not the automatic stop control of the engine for stopping the piston of the stop-time expansion stroke cylinder 12A within a predetermined appropriate range is possible. Specifically, the engine rotation speed Ne detected by the crank angle sensors 30 and 31 is in a predetermined range (for example, a range of 790 to 1200 rpm), and the boost pressure Bt detected by the intake pressure sensor 26 is a predetermined range. It is determined that the idle stop condition is satisfied when it is confirmed that the value is (for example, −450 to −300 mmHg). In this embodiment, in order to improve the accuracy of stopping the piston 13 within a predetermined appropriate range, the engine stop speed Ne and the boost pressure Bt are both within a predetermined range in this embodiment. However, it is possible to ensure a certain level of accuracy even if only the engine speed Ne is used.

  If it is determined NO in step S53 and it is confirmed that the idling stop condition for stopping the piston 13 of the expansion stroke cylinder 12A at the time of stoppage is not satisfied, a transition is made to the normal engine control state. In order to do this, the automatic transmission mechanism 50 is switched from the neutral state (N ren) to the drive state (D range) (step S54), and then the process returns. In the state where the deceleration-time FC control is being performed in step S5 of the flowchart shown in FIG. 12, when the process proceeds to step S54 in FIG. 13, the fuel is transferred when the process proceeds to step S4 in the flowchart shown in FIG. The injection will be restored.

  On the other hand, if it is determined as YES in step S53, it is determined whether or not the deceleration-time FC control is being executed in step S5 of the flowchart shown in FIG. 12 (step S55), and NO is determined. If it is detected, the fuel injection to each cylinder 12 is stopped (step S56). If it is determined as YES in step S55 and it is confirmed that the deceleration FC control is being executed, step S56 is skipped and the process proceeds to step S57.

  Then, by controlling the opening K of the throttle valve 23 based on the engine rotational speed Ne or the engine top dead center rotational speed ne (step S57), the expansion stroke cylinder 12A and the compression stroke cylinder 12C when the engine is stopped are controlled. While adjusting the compression reaction force by air and controlling the amount of power generated by the alternator 28 during the automatic engine stop operation period (step S58), the resistance of the crankshaft 3 is changed to finely adjust the rotational speed of the engine. As a result, after the fuel injection stop time T1, control for decreasing the engine rotational speed Ne along a reference line determined in advance through experiments or the like, that is, control for stopping the piston 13 within a predetermined appropriate range is executed.

  The control operation of the opening K of the throttle valve 23 and the control operation of the target generated current Ge of the alternator 28 will be specifically described. When the opening control of the throttle valve 23 is executed, the throttle valve 23 is first opened at the fuel injection stop time T1, so that the opening K is set to the adjusted opening (15% in the above example). A larger value (for example, 30%) is set. Thereafter, by determining whether or not the engine rotation speed Ne is equal to or lower than a reference value set in advance to about 790 rpm, the engine rotation speed Ne decreases after the fuel injection stop time T1 shown in FIG. It is determined whether or not it has started. At a time T2 when it is determined that the throttle valve 23 has started to decrease, the throttle valve 23 is closed and its opening degree K is set to 0%. As a result, the boost pressure Bt that has risen so as to approach the atmospheric pressure by opening the throttle valve 23 starts to decrease with a predetermined time difference.

  When starting the target generated current control of the alternator 28, first, the target generated current Ge of the alternator 28 is set to 0 at the fuel injection stop time T1 to stop the power generation. Then, at the time T2 when the engine speed Ne drops below the reference value set to about 790 rpm in advance, the target generated current Ge of the alternator 28 is set to the initial value set to about 60 A in advance and the alternator 28 is operated. Start power generation control. As a result, a predetermined rotational resistance acts on the crankshaft 3 of the engine body 1.

  Next, when the top dead center rotational speed ne of the engine falls within a predetermined appropriate control range, the target generated current Ge of the alternator 28 corresponding to the top dead center rotational speed ne at that time T3 is set. This appropriate control range is the fourth compression level before the engine is stopped, for example, in the process of decreasing the engine speed Ne along the reference line indicating the time change of the engine speed set in advance. The value is set based on the top dead center rotational speed ne at the time T3 when passing through the dead center, and specifically, is set within a range of 480 to 540 rpm. The target generated current Ge of the alternator 28 corresponding to the top dead center rotational speed ne is based on a map (not shown) showing the relationship between the top dead center rotational speed ne and the target generated current Ge stored in the ECU 2 in advance. It is determined.

  In parallel with the opening degree control of the throttle valve 23 and the target generated current control of the alternator 28 being executed in accordance with the engine speed Ne or the like, for example, it is determined whether or not the accelerator sensor 34 is turned on. Alternatively, it is determined whether or not a return condition (restart condition) for fuel injection is satisfied by determining whether or not the brake sensor 35 is turned off while the vehicle speed is 10 km / h (step S59). If it is determined as NO in step S59, it is determined whether or not the engine is stopped (step S60). YES is determined in step S60, or YES is determined in step S59. The control in steps S57 to S60 is repeatedly executed. If it is determined YES in step S60 and it is confirmed that the engine has been stopped, control for restarting the engine when the restart condition is established after the engine is automatically stopped, that is, normal Restart control is executed (step S61).

  That is, as shown in FIGS. 14 and 15, first, the first fuel injection J2 is performed in the stop-time compression stroke cylinder 12C (third cylinder), and combustion ((1) in FIG. 14) is performed by the ignition. Is called. With the combustion pressure (part a in FIG. 15) due to this combustion (1), the piston 13 of the stop-time compression stroke cylinder 12C is pushed down to the bottom dead center side, and the engine is driven in the reverse direction. With the reverse rotation of the engine, the piston 13 of the stop expansion cylinder 12A (first cylinder) starts to move in the direction of the top dead center. Then, when the piston 13 of the expansion stroke cylinder 12A moves to the top dead center side (preferably closer to the top dead center from the stroke center), the fuel injection J1 is performed when the air in the cylinder 12A is compressed. The compression pressure is reduced by the latent heat of vaporization of the injected fuel, and the piston 13 comes closer to the top dead center, so that the density of the compressed air (air mixture) increases (part b in FIG. 15).

  When the piston 13 of the stop expansion stroke cylinder 12A is sufficiently close to top dead center, the cylinder 12A is ignited and the injected fuel (J1) is combusted ((2) in FIG. 14). The engine is driven in the forward direction by the combustion pressure (c portion in FIG. 15).

  Further, by performing fuel injection (J3) richer than the combustible air-fuel ratio at an appropriate timing with respect to the stop-time compression stroke cylinder 12C ((3) in FIG. 14), this stop-time compression stroke cylinder 12C. Although the combustion is not performed, the compression pressure of the compression stroke cylinder 12C at the time of stop is reduced by the latent heat of vaporization caused by the fuel injection (part d in FIG. 15), and accordingly, the compression top dead center (the first compression increase from the start of the start) The amount of combustion energy consumed to exceed the dead point) will be reduced.

  Furthermore, the timing of the fuel injection (J4) in the stop-time intake stroke cylinder 12D, which is the next combustion cylinder, is set to an appropriate timing ((4 in FIG. 14) for reducing the temperature in the cylinder and the compression pressure by the latent heat of vaporization of the fuel. ), For example, after the middle stage of the compression stroke), it is possible to prevent self-ignition before the compression top dead center in the compression stroke of the intake stroke cylinder 12D when stopped. Further, in combination with the ignition timing of the intake stroke cylinder 12D at the time of stop being set after the compression top dead center, combustion before the compression top dead center is prevented (part e in FIG. 15). . In other words, the compression pressure due to the fuel injection (J4) is reduced and the combustion before the compression top dead center is not performed, so that the energy of the first combustion in the expansion stroke cylinder 12A at the time of stop is reduced to the compression top dead center (engine It is possible to suppress consumption to exceed the second compression top dead center) from the start of starting.

  Thus, the first compression top dead center ((3) in FIG. 14) after the start of restart and the second by the energy of the first combustion ((2) in FIG. 14) in the expansion stroke cylinder 12A at the time of stop. The compression top dead center ((4) in FIG. 14) can be exceeded, smooth and reliable startability can be ensured, and thereafter, a normal operating state is entered.

  On the other hand, when YES is determined in step S59 of FIG. 13 and the engine is stopped, that is, during execution of the automatic stop control, the accelerator sensor 34 is turned ON, etc. If it is confirmed that (condition) is satisfied, it is determined whether or not the engine speed Ne at this time is higher than a preset reference speed R (step S62). The reference speed R is a speed at which the engine can be restarted only by resuming fuel injection without requiring an assisting force corresponding to the reverse driving force input from the turbine 55. It is set to a value corresponding to the engine rotational speed Ne that can exceed the last compression top dead center in the process of decreasing the engine rotational speed Ne after being stopped, for example, about 260 rpm.

  When it is determined YES in step S62 and the fuel injection return condition is satisfied, the engine speed Ne is higher than the reference speed R, and the engine restart condition is satisfied before the final stage of the automatic stop control. If it is confirmed that this has been done, torque shock suppression control, which will be described later, is executed (step S63). On the other hand, when NO is determined in step S62 and the fuel injection return condition is satisfied, the engine speed Ne is equal to or lower than the reference speed R (for example, 260 rpm), that is, the fuel injection is resumed in this state. If it is confirmed that the final stage of the automatic stop control that cannot exceed the last compression top dead center is confirmed, the low-speed return control described later is executed (step S64).

  The torque shock suppression control executed in step S63 of FIG. 13 will be described based on the flowchart shown in FIG. When this control operation starts, the automatic transmission mechanism 50 is first shifted from the neutral state (N range) to the drive state (D range) (step S65), and then a control signal for returning the fuel injection is output to output the engine. Restarting is started (step S66). Whether or not the predicted value Ef of the engine rotational speed predicted by the engine rotational speed predicting means 94 is relatively higher than the predicted value Tf of the turbine rotational speed predicted by the turbine rotational speed predicting means 95, that is, automatically The predicted value Ef of the engine speed at the time when the operation of shifting the speed change mechanism 50 from the neutral state to the drive state is completed from the predicted value Tf of the turbine speed calculated based on the vehicle speed V, the deceleration, the gear position, and the like. Is determined to be higher (step S67), and if it is determined to be YES, control for decreasing the engine speed Ne is executed (step S68).

  Specifically, in step S68, control is performed to correct the throttle opening K in the direction of decreasing, and retard the ignition timing, thereby suppressing an increase in engine rotation speed. Next, it is determined whether or not the control for shifting the automatic transmission mechanism 50 from the neutral state to the drive state has been completed (step S69), and when the determination is YES, after shifting to the normal throttle opening control state ( Step S70) and return.

  On the other hand, the predicted value Ef of the engine rotation speed determined as NO in step S67 and predicted by the engine rotation speed prediction means 94 is more relative to the predicted value Tf of the turbine rotation speed predicted by the turbine rotation speed prediction means 95. If it is confirmed that the condition is not high, the process proceeds to step S70 and returns.

  Next, the low-speed return control executed in step S64 of FIG. 13 will be described based on the flowchart shown in FIG. When this control operation starts, first, the first turbine rotation speed predicted by the turbine rotation speed prediction means 95 at the time when the fuel return condition is satisfied, that is, the vehicle speed at the time when the fuel injection condition is satisfied, and the vehicle speed correspond to this vehicle speed. It is determined whether or not the turbine rotation speed Nt1 calculated based on the gear position of the automatic transmission mechanism 50 is higher than a preset reference speed Tr (step S71). The reference speed Tr is used to properly restart the engine by the reverse driving force input from the turbine 55 to the crankshaft 3 of the engine body 1 when the automatic transmission mechanism 50 is changed from the neutral state to the drive state. Is set to a turbine rotational speed (for example, about 1200 rpm) at which a sufficient assist force is obtained.

  In step S71, the determination is YES, and the automatic transmission mechanism 50 is changed to the drive state, and the gear stage is set to a value corresponding to the vehicle speed, so that it is input from the turbine 55 to the crankshaft 3 of the engine body 1. If it is confirmed that sufficient assisting force for properly restarting the engine according to the reverse driving force is obtained, the automatic transmission mechanism 50 is driven from the neutral state (N range) at this point. While outputting the control signal which changes to a state (D range) (step S72), and outputting the control signal which restarts fuel injection (step S73), it returns.

  If it is determined NO in step S71 and it is confirmed that the first turbine rotational speed Nt1 is lower than the reference speed Tr, the second turbine rotational speed Nt2 predicted by the turbine rotational speed predicting means 95, That is, the turbine rotational speed calculated based on the vehicle speed at the time when the fuel injection condition is satisfied and the shift speed when the automatic speed change mechanism 50 is set to a low speed such as the first speed is higher than the reference speed Tr. Is determined (step S74).

  If it is determined YES in step S74 and it is confirmed that the second turbine rotation speed Nt2 is higher than the reference speed Tr, the gear position of the automatic transmission mechanism 50 is set to a value corresponding to the vehicle speed at this time. A control signal for setting the low gear (for example, the first gear) to shift the automatic transmission mechanism 50 from the neutral state (N range) to the drive state (D range) is output (step S75), and fuel injection is resumed. The control signal is output (step S76), and when it is confirmed that the engine has been restarted, the automatic transmission mechanism 50 is set to a gear position corresponding to the vehicle speed (step S77), and the process returns.

  In addition, it is determined NO in Step S74, and the second turbine rotation speed Nt2 is set lower than the reference speed Tr, and the shift stage of the automatic transmission mechanism 50 is set to a shift stage lower than a value corresponding to the vehicle speed. However, if it is confirmed that sufficient assisting force to properly restart the engine is not obtained by the reverse driving force input from the turbine 55 to the crankshaft 3 of the engine body 1, the engine It is determined whether or not the engine has been reversed, that is, whether or not the engine has shifted to the reverse state after reaching the last compression top dead center at the final stage of the control operation for automatically stopping the engine (step S78). At that time, fuel is injected into the stop-time expansion stroke cylinder 12A (step S79).

  Next, it is determined whether or not the engine rotational speed Ne has become 0, that is, whether or not the engine has entered a state immediately before shifting from the reverse rotation state to the normal rotation state (step S80). Control for changing the automatic transmission mechanism 50 from the neutral state (N range) to the drive state (D range) after the engine is restarted by igniting the fuel injected into the expansion stroke cylinder 12A at the time of stop (step S81). After outputting the signal (step S82), the process returns.

  When the preset engine automatic stop condition is satisfied as described above, the fuel supply is stopped to automatically stop the engine, and the engine restart condition in the automatic stop state is satisfied. In the engine starter equipped with the automatic stop control means 93 that automatically restarts the engine by causing combustion in at least the cylinder 12A that has been automatically stopped in the expansion stroke, the shift speed is automatically set according to the driving state of the vehicle. And an automatic transmission mechanism 50 configured to be able to switch the transmission state of power to the wheel side between a drive state and a neutral state, and a turbine rotation speed prediction means 95 that predicts a turbine rotation speed corresponding to the vehicle speed. When the automatic engine stop condition is satisfied while the vehicle is running, the automatic transmission mechanism 50 is set to the neutral state and When the engine restart condition is satisfied at the final stage of the automatic stop control, the predicted value of the turbine rotational speed corresponding to the vehicle speed is higher than the preset reference speed. The automatic stop control means 93 executes the control for restarting the engine after the automatic transmission mechanism 50 is changed from the neutral state to the drive state when it is determined that the automatic transmission mechanism 50 is high. When it is possible to properly execute control for automatically stopping the engine within a predetermined crank angle range suitable for restarting, and when there is a request to re-accelerate the vehicle during execution of control for automatically stopping the engine, etc. In addition, the engine can be restarted properly while sufficiently ensuring the restart response of the vehicle.

  That is, when the automatic engine stop condition is satisfied, the automatic transmission mechanism 50 is set to the neutral state so that the engine is automatically stopped. Therefore, the automatic engine stop control is executed while the vehicle is running. Even in this case, it is possible to effectively prevent the occurrence of a situation in which the stop position of the piston 13 deviates from the appropriate range due to the reverse driving force on the wheel side being input to the crankshaft 3 of the engine body 1. By stopping the fuel supply to the engine at the time when the stop condition is satisfied, it is possible to appropriately execute control for automatically stopping the engine within a predetermined crank angle range suitable for restart.

  If the engine restart condition is satisfied at the final stage of the automatic stop control in which the engine speed Ne has decreased, even if the engine automatic stop control is stopped and fuel injection is restarted at this point, the fuel There is a possibility that the fuel-air mixture generated by the injection cannot be ignited in a sufficiently compressed state, and combustion energy for properly restarting the engine cannot be obtained. Therefore, in the present invention, when it is confirmed that the restart condition is satisfied at the final stage of the automatic stop control based on the engine speed at the time when the restart condition is satisfied, the turbine rotation speed prediction is performed. The first turbine rotational speed Nt1 predicted by the means 95, that is, the turbine rotational speed that becomes a value corresponding to the vehicle speed by changing the automatic transmission mechanism 50 from the neutral state to the driving state is higher than the preset reference speed Tr. If it is determined that the automatic transmission mechanism 50 is high, the automatic stop control means 93 executes control for restarting the engine after changing the automatic transmission mechanism 50 from the neutral state to the drive state. . Thus, the turbine rotational speed Nt is increased to a value corresponding to the vehicle speed in accordance with the reverse driving force input to the turbine 55 from the wheel side, and the reverse driving input to the crankshaft 3 of the engine body 1 from the turbine 55. It is possible to effectively use the force as an assist force for restart, and there is an advantage that the restartability of the engine can be effectively improved.

  In particular, in the above embodiment, the engine restart condition is satisfied when the first turbine rotational speed Nt1 predicted by the turbine rotational speed predicting means 95 is lower than the reference speed Tr in the final stage of the automatic stop control. In this case, the automatic stop control means 93 is configured to execute the control for restarting the engine by setting the gear position of the automatic transmission mechanism 50 to a gear position lower than the value corresponding to the vehicle speed, so that FIG. As indicated by the solid line, when the automatic transmission mechanism 50 is switched from the neutral state to the drive state, the turbine rotational speed Nt is increased to a reference speed Tr or higher set to about 1200 rpm, for example. As a result, even when the vehicle speed is relatively low, a sufficient assist force for restart is obtained in accordance with the reverse drive force input from the turbine 55 to the crankshaft 3 of the engine body 1, and the engine can be restarted quickly. Thus, there is an advantage that sufficient reacceleration response can be secured.

  In the above embodiment, as shown in FIG. 19, the engine is restarted when the second turbine rotation speed Nt2 predicted by the turbine rotation prediction detecting means 95 at the final stage of the automatic stop control is equal to or lower than the reference speed Tr. Even if the condition is satisfied, that is, even if the gear position of the automatic transmission mechanism 50 is set to a gear position (for example, the first gear) lower than the value corresponding to the vehicle speed, an input is made from the turbine 55 to the crankshaft 3 of the engine body 1. When the engine restart condition is satisfied in an operating state in which the turbine rotational speed Nt cannot be increased beyond the reference speed Tr at which sufficient assisting force for properly restarting the engine is obtained by the reverse driving force generated. Whether the engine has entered a state of shifting from the reverse rotation state to the normal rotation state, that is, the engine has shifted to the reverse rotation state upon reaching the last compression top dead center. After that, it is determined whether or not the engine rotation speed Ne becomes 0 and the state immediately before the forward rotation is reached. When the determination is YES, the combustion is restarted and the engine is restarted. Since the transition is made from the neutral state to the drive state, the engine can be restarted quickly and properly by effectively utilizing the rotational inertia of the crankshaft 3 and the reverse driving force input from the turbine 55.

  In particular, when the engine restart condition is satisfied when the second turbine rotational speed Nt2 detected by the turbine rotational speed predicting means 95 is equal to or lower than the reference speed Tr in the final stage of the control for automatically stopping the engine as described above. In addition, when it is confirmed that the engine has shifted to the reverse rotation state, according to the configuration in which fuel is injected into the expansion stroke cylinder 12A at the time of stop, the temperature of the cylinder is lowered by the latent heat of vaporization of the fuel. The piston 13 can be effectively raised to a position close to the compression top dead center, and the air-fuel mixture generated by the fuel injection can be burned in a sufficiently compressed state in accordance with the reverse operation of the engine. Therefore, there is an advantage that combustion energy for restarting the engine can be obtained effectively.

  In the above embodiment, when the restart condition is satisfied at the final stage of the automatic stop control based on the first and second turbine rotation speeds Nt1 and Nt2 predicted by the turbine rotation speed prediction means 95, the turbine 55 is configured to determine whether or not a sufficient assist force for restart is obtained in accordance with the reverse drive force input to the crankshaft 3 of the engine body 1 from 55. By determining whether or not the vehicle speed detected by the vehicle speed sensor 38 when the condition is satisfied is higher than the reference vehicle speed, the engine is restarted according to the reverse driving force input from the turbine 55 to the crankshaft 3 of the engine body 1. It is determined whether or not the assist force is sufficiently obtained, that is, whether or not the first and second turbine rotational speeds Nt1 and Nt2 are higher than the reference speed Tr. Sea urchin may be configured.

  Further, in the above embodiment, the final stage of the control for automatically stopping the engine is set to the period before the engine stop from the time when the last compression top dead center is exceeded when the engine is automatically stopped, and the final stage of the automatic stop control. , On the basis of the first and second turbine rotational speeds Nt1 and Nt2 predicted by the turbine rotational speed predicting means 95, the automatic transmission mechanism 50 is changed to the drive state when the engine restart condition is satisfied, and is necessary. Accordingly, since the control for restarting the engine is executed after setting the shift speed of the automatic transmission mechanism 50 to a lower speed than the value corresponding to the vehicle speed, unnecessary shift control is prevented from being executed. On the other hand, the reverse driving force input from the turbine 55 of the automatic transmission mechanism 50 to the crankshaft 3 of the engine body 1 is effectively used as the assisting force. It is thus possible to properly restart the engine.

  That is, when the engine restart condition is satisfied in a state where the engine speed Ne is sufficiently high, for example, higher than 260 rpm, before the time when the last compression top dead center is exceeded when the engine is automatically stopped, the automatic transmission mechanism Since the assisting force for restarting the engine can be sufficiently obtained without setting the 50 shift stages to a value lower than the normal shift stage, the shift stage of the automatic transmission mechanism 50 is set to a value corresponding to the vehicle speed. By doing so, it is preferable to restart the engine in a state in which the shift frequency of the automatic transmission mechanism 50 is prevented from increasing. Further, when the engine restart condition is satisfied immediately after the engine is stopped, when the automatic transmission mechanism 50 is shifted to the drive state at the time when the restart condition is satisfied, the reverse drive force input from the turbine 55 is changed. The crankshaft 3 is rotationally driven, and it may be difficult to keep the stop position of the piston 13 within an appropriate range, so that restartability may be reduced.

  On the other hand, at the final stage of the automatic stop control set after the time when the engine rotational speed Ne has become lower than the last compression top dead center when the engine is automatically stopped as described above, the engine restart condition is If established, the gear position of the automatic transmission mechanism 50 is set to a value lower than the normal gear position if necessary, and is input from the turbine 55 of the automatic transmission mechanism 50 to the crankshaft 3 of the engine body 1. By increasing the large reverse driving force, it is possible to properly restart the engine using the reverse driving force as an assist force while preventing unnecessary shift control from being executed. Further, before the engine is stopped, even if the automatic transmission mechanism 50 is shifted to the drive state at the time when the restart condition is satisfied, the restartability is caused by the fact that the stop position of the piston 13 is not within the proper range. Therefore, there is an advantage that the engine can be restarted promptly and appropriately by effectively using the reverse driving force as the assisting force.

  Furthermore, as shown in the above-described embodiment, the automatic transmission mechanism 50 is executed when the automatic engine stop condition is satisfied while the vehicle is running and the automatic transmission mechanism 50 is set to the neutral state and the control for automatically stopping the engine is executed. When the automatic stop control means 93 executes the precharge control for filling the fluid flow passage (oil passage) connected to the friction elements 67 to 71 with the working fluid (hydraulic oil), the vehicle When the automatic transmission mechanism 50 in the neutral state is shifted to the drive state when the engine restart condition is satisfied during execution of the control for automatically stopping the engine while the automatic engine stop condition is satisfied during the travel of the vehicle By shortening the required switching time from the period A to B shown in FIG. 8, the switching responsiveness can be effectively improved. Therefore, there is an advantage that the re-acceleration responsiveness can be effectively improved when a re-acceleration request is made during the execution of the control for automatically stopping the engine.

  Further, during the execution of the control for automatically stopping the engine as described above, the engine speed Ne can be restarted only by restarting the fuel injection without requiring an assist force corresponding to the reverse driving force input from the turbine 55. When the restart condition is satisfied in a state higher than a reference speed R (for example, 260 rpm) set in advance to a value that can be restarted, the automatic transmission mechanism 50 is set to neutral as shown by the broken line in FIG. From the predicted value Tf of the turbine rotational speed at which the predicted value Ef of the engine speed at the completion time Tb of the operation for switching from the state to the drive state changes to a value corresponding to the vehicle speed when the automatic transmission mechanism 50 is switched to the drive state. May be relatively high. In such a state, when the control for resuming fuel injection and igniting at a normal timing is performed when the restart condition is satisfied, the automatic transmission mechanism 50 is neutral as shown by the broken line in FIG. After the time Tb when the state (N range) is switched to the drive state (D range), the turbine rotation speed may increase significantly and a torque shock may occur.

  For this reason, in this embodiment, when the restart condition is satisfied when the engine speed Ne is higher than the reference speed R during execution of the control for automatically stopping the engine, the automatic transmission mechanism 50 enters the drive state. Is the predicted value Ef of the engine rotational speed at the time point Tb switched relatively higher than the predicted value Tf of the turbine rotational speed that changes to a value corresponding to the vehicle speed when the automatic transmission mechanism 50 is switched to the drive state? If the determination is high and the determination is high, the ignition timing retarding control is performed to retard the ignition timing from the time point Ta when the restart condition is satisfied to the time point Tb when the automatic transmission mechanism 50 is switched to the drive state. By executing the control, as shown by the solid line in FIG. 20, the control for reducing the engine speed is executed. As a result, the engine rotational speed Ne at the time Tb when the automatic transmission mechanism 50 is switched to the drive state is controlled to a value corresponding to the turbine rotational speed Nt taking into account the vehicle speed and the shift speed. Thus, there is an advantage that generation of torque shock caused by abrupt change in the speed of each part of the drive system can be effectively suppressed by preventing transmission of a large drive torque transmitted from 3 to the turbine 55.

  Further, as shown in the above embodiment, it is determined that the restart condition is satisfied during the execution of the automatic stop control, and the predicted value Ef of the engine rotational speed is relatively higher than the predicted value Tf of the turbine rotational speed. The automatic stop control means 93 executes control for lowering the engine rotational speed until the operation of changing the automatic transmission mechanism 50 from the neutral state to the drive state is completed. In this case, it is possible to effectively suppress the occurrence of a torque shock in which the speed of each part of the drive system changes rapidly according to the drive torque transmitted from the crankshaft 3 of the engine body 1 to the turbine 55. In addition, when the operation of switching the automatic transmission mechanism 50 to the drive state is completed, control for reducing the engine rotation speed is required by terminating the engine rotation speed increase control and shifting to the normal control state. There is an advantage that it is possible to effectively prevent a decrease in re-acceleration responsiveness due to the execution over the long period of time.

  In the above embodiment, when the engine is restarted, the crankshaft 3 is driven in the reverse direction and then forwardly driven to increase the combustion energy. However, the crankshaft 3 is restarted only by the forward rotation. It may be configured. In addition, if the piston position is not within the proper range when the engine is automatically stopped, or if the engine speed could not be increased sufficiently when the engine is restarted, the restart motor is operated. You may comprise so that engine restart may be assisted. Furthermore, the present invention is not limited to a direct injection engine that directly injects fuel into the combustion chamber 14, but can also be applied to a port injection type engine that injects fuel into an intake port.

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 structure of the intake system and exhaust system of an engine. It is the schematic which shows an example of the automatic transmission mechanism in the starter which concerns on this invention. It is a table | surface which shows the corresponding relationship between the operating state of the friction element provided in the automatic transmission mechanism, and a gear stage. It is a schematic explanatory drawing which shows an example of the hydraulic control circuit of an automatic transmission control mechanism. It is a switching map of the automatic transmission mechanism according to the vehicle speed and the throttle opening. It is a distribution map which shows the correlation with the engine speed at the time of an engine stop, and a piston stop position. It is a table | surface which shows the corresponding | compatible relationship between the operating state of the solenoid valve in an automatic transmission mechanism, and a gear stage. It is a table | surface which shows the corresponding | compatible relationship between the operation state with the provided friction, and a gear stage. It is a flowchart which shows the engine automatic stop control operation | movement. It is a time chart which shows the change state of the hydraulic fluid in a hydraulic control circuit. It is a flowchart which shows detection control operation | movement of a piston stop position. 1 is a block diagram showing an embodiment of an engine starter according to the present invention. It is a time chart which shows the change state etc. of the engine speed at the time of an automatic stop of an engine. It is a distribution map which shows the correspondence of engine rotation speed and piston position at the time of an engine automatic stop. It is a time chart which shows the change state of an engine speed, a turbine speed, etc. when there exists a restart request | requirement at the time of an engine automatic stop. It is a flowchart which shows the basic control operation | movement at the time of engine automatic start control. It is a flowchart which shows an idle stop control operation | movement of an engine. It is a time chart which shows the control action at the time of engine restart. It is a time chart which shows the change state etc. of the engine speed at the time of engine restart. It is a flowchart which shows torque shock suppression control operation | movement. It is a flowchart which shows low-speed return control operation. It is a time chart which shows the change state etc. of the engine speed in the case of stopping an engine automatic stop operation and restarting the engine. It is a time chart which shows the restart control operation in case a turbine rotational speed is low. It is a time chart which shows the restart control operation | movement in case an engine speed is high.

Explanation of symbols

1 Engine body 50 Automatic transmission mechanism 93 Automatic stop control means 94 Engine rotation speed prediction means 95 Turbine rotation speed prediction means

Claims (5)

  When the preset engine automatic stop condition is satisfied, the fuel supply is stopped and the engine is automatically stopped, and when the restart condition of the engine in the automatic stop state is satisfied, at least the expansion stroke An engine starter equipped with an automatic stop control means for automatically restarting the engine by causing combustion in the cylinder that has been automatically stopped in step 1, and automatically changing the gear position according to the driving state of the vehicle An automatic transmission mechanism configured to be able to switch a transmission state of power to the wheel side between a drive state and a neutral state, and a turbine rotation speed prediction means for predicting a turbine rotation speed corresponding to the vehicle speed, the automatic stop control means If the engine automatic stop condition is satisfied while the vehicle is running, the automatic transmission Whether the predicted value of the turbine rotation speed corresponding to the vehicle speed is higher than the preset reference speed when the engine restart condition is satisfied at the final stage of the automatic stop control while executing the control to stop. If the automatic transmission mechanism is changed from the neutral state to the drive state after the automatic transmission mechanism is determined to be high, combustion is performed in the cylinder automatically stopped in the expansion stroke, and the engine is restarted. An engine starter for a vehicle.   The automatic stop control means determines that the predicted value of the turbine rotational speed corresponding to the vehicle speed is lower than a preset reference speed when the engine restart condition is satisfied at the final stage of the automatic stop control. In this case, the engine is restarted when it is confirmed that the engine shifts from the reverse rotation state to the normal rotation state, and then the automatic transmission mechanism is changed from the neutral state to the drive state. The vehicle engine starter according to claim 1.   The automatic stop control means determines that the predicted value of the turbine rotational speed corresponding to the vehicle speed is lower than a preset reference speed when the engine restart condition is satisfied at the final stage of the automatic stop control. 3. The vehicle engine starter according to claim 2, wherein the fuel for restarting is injected when it is confirmed that the engine has shifted to the reverse rotation state.   The final stage of the automatic stop control is set to a period before the engine is stopped after the time when the last compression top dead center is exceeded when the engine is automatically stopped. The vehicle engine starter according to claim 1.   The automatic stop control means is connected to the friction element of the automatic transmission mechanism when the automatic stop condition of the engine is satisfied during the traveling of the vehicle and the control for automatically stopping the engine is performed while the automatic transmission mechanism is in the neutral state. The engine starting device for a vehicle according to any one of claims 1 to 4, wherein the fluid flow passage is in a precharged state in which a working fluid is filled.

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