JP4661202B2 - Vehicle engine starting device - Google Patents

Description

  The present invention relates to an engine starting device that automatically stops an engine once at the time of deceleration of a vehicle and automatically starts the stopped engine.

In recent years, in order to reduce fuel consumption and reduce CO ₂ emissions, the engine is automatically stopped once at idle, and then the engine is automatically restarted when a restart condition such as a start operation is established. Such engine starting devices have been developed.

  In this type of engine starter, in order to further improve the fuel efficiency reduction effect, the fuel injection is cut while the vehicle is running (during deceleration), and the engine is directly shifted to the automatic stop state. (See Patent Document 1). In the device of Patent Literature 1, after the engine is automatically stopped, the automatic transmission mechanism is in a neutral state in order to cut off the influence of reverse driving from the wheel side.

On the other hand, after the engine is automatically stopped, the engine is restarted when it is changed from a non-driving position (corresponding to the neutral state in the present specification) to a driving position (corresponding to the driving state in the present specification). It is also known to execute a rapid pressure increase control that temporarily increases pressure for a predetermined time temporarily at the initial stage of oil supply to the clutch for establishment (see Patent Document 2).
JP-A-7-266932 JP-A-11-351371

  When the engine is automatically stopped during traveling (deceleration) as in Patent Document 1 and the automatic transmission is set to the neutral state, the engine is restarted when there is a request for re-acceleration such as depression of the accelerator. It is required that the transmission be immediately driven. In a normal automatic transmission, in order to switch from a neutral state to a drive state, it is necessary to supply hydraulic pressure to a friction element (such as a clutch) that is intermittently controlled by hydraulic control. Before this frictional element effectively transmits the driving force, at least the oil path (clutch circuit) from the oil pump to the frictional element is filled with oil, and the clutch piston is operated against the return spring to activate the clutch clearance. It is necessary to go through a process of setting the (gap between friction elements) to zero.

  Therefore, a certain time delay is unavoidable from the start of the control for switching from the neutral state to the drive state until the drive state is actually reached. For this reason, when restarting the engine with a reacceleration request, there is a problem that switching to the drive state is not in time, and sufficient acceleration response cannot be obtained.

  On the other hand, it is also conceivable to apply the rapid pressure increase control as shown in Patent Document 2. As a result, the delay can be expected to some extent, but the effect is limited. In particular, when it is necessary to select a gear position at which a plurality of clutches and the like are engaged, the delay time is further increased, which leaves a problem in reducing the time.

  The present invention has been made in view of the above-described circumstances, and has the effect of reverse driving from the wheel side by setting the automatic transmission to a neutral state while automatically stopping the engine while the vehicle is running to improve fuel efficiency. The present invention provides a vehicle engine starter capable of reliably suppressing the above-described problem and quickly switching to a drive state when the engine is automatically restarted in response to a reacceleration request.

  According to a first aspect of the present invention, there is provided a vehicle engine starter that stops fuel supply to an engine by stopping fuel supply to the engine when an automatic engine stop condition set to be satisfied even when the vehicle is running is satisfied. And an engine starter equipped with stop / restart control means for automatically igniting the supplied fuel and automatically restarting the engine when the restart condition of the engine in the automatic stop state is satisfied. In addition, there are a plurality of friction elements that are interrupted by fluid pressure control. By intermittently connecting these friction elements, the drive state in which the driving force can be transmitted to the wheel side and the transmission of the driving force to the wheel side are separated. And is configured to switch a predetermined fluid path connected to the friction element until a predetermined fluid pressure is reached. An automatic transmission mechanism that can be in a charged state; and a vehicle speed sensor that detects a vehicle speed, wherein the stop / restart control means moves the automatic transmission mechanism from the drive state to neutral when the automatic stop condition is satisfied while the vehicle is running. The engine is automatically stopped and the engine is automatically stopped. Further, when the vehicle deceleration is relatively small, the speed of the automatic transmission mechanism is sequentially shifted to the low speed side according to the vehicle speed after the engine is stopped. When the vehicle is suddenly decelerating with a relatively large deceleration, after the engine is stopped, the friction element to be engaged in order to establish each shift stage is set for a plurality of shift stages while the automatic transmission mechanism is in the neutral state. The precharge state is set.

  According to a second aspect of the present invention, in the engine starter for a vehicle according to the first aspect, the stop / restart control means is configured to perform the operation during an operation period in which the automatic stop condition is satisfied and the engine is automatically stopped while the vehicle is running. In the neutral state, regardless of the deceleration of the vehicle, the precharge state is set with respect to the friction element to be engaged in order to establish the shift stage for at least one shift stage.

  According to a third aspect of the present invention, in the vehicle engine starter according to the first or second aspect, the precharge state includes an initial precharge stage in which a predetermined fluid path connected to the friction element is filled with a working fluid. A late precharge stage in which the friction element is moved from the release position in the fastening direction via the initial precharge stage to bring it into a state immediately before fastening, and the automatic transmission mechanism is brought into the neutral state by the stop / restart control means. When it is done, it is in the precharge state in the late precharge stage.

  According to a fourth aspect of the present invention, in the vehicle engine starter according to any one of the first to third aspects of the present invention, the vehicle engine starter includes a brake sensor that detects a brake operation state, After the above automatic stop condition is satisfied and the engine is automatically stopped, the engine is automatically restarted when the brake is turned off at a predetermined vehicle speed or less before the vehicle stops.

  According to the first aspect of the present invention, the engine is automatically stopped even when the vehicle is running when a predetermined condition is satisfied. Therefore, the fuel consumption and the like can be improved more than those in which the engine is automatically stopped only when the vehicle is stopped. Can be planned. At that time, since the automatic transmission is set to the neutral state, the influence of reverse driving from the wheel side can be reliably suppressed. The time when the influence of the reverse drive from the wheel side should be most suppressed is a period from the start of the automatic stop operation to the complete stop. Because during this period, control is generally performed such that the piston is stopped at a predetermined position (for example, near the middle between top dead center and bottom dead center) in preparation for restart. This is because it is difficult to stop the piston at the target position when affected by reverse driving. Therefore, according to the present invention, since the automatic transmission mechanism is set to the neutral state at least until the engine stops, the influence of such reverse driving can be reliably suppressed.

  At the time of slow deceleration, after the engine is stopped, the shift stage of the automatic transmission mechanism is sequentially shifted to the low speed stage side according to the vehicle speed. Therefore, when the engine is restarted with a re-acceleration request, the driving force is instantaneously transmitted by the already-engaged friction elements, and the vehicle speed is not delayed without causing a delay in switching to the drive state due to hydraulic charging or the like. High re-acceleration responsiveness can be realized at an appropriate shift speed according to the above.

  By the way, when such control is applied even at the time of sudden deceleration, there is a possibility that the speed of decrease of the vehicle speed is too large and the shift to the low speed stage corresponding to the vehicle speed is relatively delayed. Therefore, according to the present invention, during such a sudden deceleration, the friction elements to be fastened in order to establish the respective shift stages are pre-set for a plurality of shift stages while the neutral state is not selected and a specific shift stage is not selected. Charge state. In other words, the oil passage leading to the friction element is filled with oil in advance until a predetermined hydraulic pressure is obtained. In this way, when the engine is automatically restarted during the sudden deceleration, a shift stage corresponding to the vehicle state at the time of restart can be selected from the plurality of shift stages to enter the drive state. it can. In this way, since the shift to the low speed is not performed sequentially following the decrease in the vehicle speed, there is no need to worry about the delay. When the driving state is set, an appropriate reacceleration according to the reacceleration request can be realized by selecting a gear position according to the vehicle state (vehicle speed, accelerator depression amount, etc.) at the time of restart. Moreover, no matter which gear stage is selected, the friction element for establishing that gear stage is in a precharged state, so there is no need to go through the process of refilling the oil path, etc. The driving force can be transmitted by increasing the pressure. That is, it can be quickly brought into a fastened state, and high reacceleration responsiveness can be obtained.

  According to the invention of claim 2, a high reacceleration responsiveness can be obtained by promptly engaging the friction element not only after the engine is completely stopped but also when a reacceleration request is made during the automatic engine stop period. it can.

  According to the invention of claim 3, by setting the precharge state to the precharge state in the late precharge stage (hereinafter referred to as the late precharge state), the engagement delay of the friction element can be shortened to the maximum. Note that in this late precharge state, the friction element may slightly slip due to variations in hydraulic pressure or the like, and if such a state is continued for a long time, there is a concern that the deterioration of the friction element over time may be accelerated. . However, in the present invention, at the time of slow deceleration, the precharge state is released by switching to a predetermined shift stage after the engine is automatically stopped, and at the time of sudden deceleration, the precharge is made after the sudden deceleration is finished (at the latest until the vehicle stops). Take state off. That is, in any case, since the precharge state is released at an early stage, the progress of the deterioration of the friction element with time is suppressed to a level that hardly requires concern.

  According to the invention of claim 4, by operating the engine when the brake is turned off and the vehicle speed becomes a predetermined vehicle speed or lower, it is possible to perform extremely low speed travel (so-called creep travel) without an accelerator operation. That is, it is possible to achieve both improvement in fuel consumption by automatically stopping the engine from a relatively high vehicle speed state and creep travel at a low vehicle speed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 and 2 show a schematic configuration of a four-cycle spark ignition engine according to an embodiment of the present invention. This engine includes an engine main body 1 having a cylinder head 10 and a cylinder block 11 and an ECU 2 (see FIG. 9) for engine control. The engine main body 1 includes a plurality of cylinders (four in the illustrated embodiment). Cylinders) 12A to 12D. A piston 13 connected to the crankshaft 3 via a connecting rod is fitted into each cylinder 12A to 12D, 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 cylinder 12 </ b> A to 12 </ b> D, and the tip of the plug 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 and opened for a time corresponding to the pulse width at the pulse input timing. 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 that fuel is injected toward the vicinity of the spark plug 15. The fuel injection valve 16 is supplied with fuel via a fuel supply passage or the like by a fuel pump (not shown), and can supply a fuel pressure higher than the pressure in the combustion chamber during the compression stroke. Is configured.

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

  Further, the engine is provided with a cam angle sensor 32 for detecting a specific rotational position of the camshaft and outputting it as a cylinder identification signal, and a water temperature sensor 33 for detecting the coolant temperature of the engine, as shown in FIG. Further, an accelerator sensor 34 that detects an accelerator opening corresponding to the accelerator operation amount of the driver, a brake sensor 35 that detects that the driver has operated the brake, and an oil temperature of an automatic transmission mechanism 50 that will be described later are detected. An oil temperature sensor 37, 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 are provided. Each detection signal output is input to the ECU 2.

  Further, as shown in FIG. 3, the engine is connected to an automatic transmission mechanism 50 through a crankshaft 3 as an output shaft thereof. 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 frictions included therein. By switching the elements intermittently, it is possible to switch between a neutral state in which the transmission of the driving force to the wheel side is cut off and a driving state in which the driving force can be transmitted to the wheel side.

  The torque converter 51 includes a pump cover 53 connected to the crankshaft 3, a pump impeller 54 formed integrally with the pump cover 53, and a turbine (turbine liner) 55 installed so as to face the pump impeller 54. In the meantime, a stator 58 attached to a case 57 via a one-way clutch 56 is provided. 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. The driving force is transmitted to and from the multi-stage transmission mechanism 52 via the turbine shaft 59 connected to the turbine 55.

  The case 57 is provided with a turbine rotation sensor 36 that detects the rotation speed of the turbine 55 in a state of facing an outer peripheral surface of a forward clutch 67 (described later) that rotates integrally with the turbine shaft 59. Yes. Specifically, the turbine rotation sensor 36 has a tip portion disposed opposite to the outer peripheral surface of the drum of the forward clutch 67, and a spline-like unevenness provided on the outer peripheral surface of the drum is displaced by the rotation of the drum. The rotational speed of the turbine 55 is detected through the rotational speed of the turbine shaft 59 by detecting a periodic change in the induced voltage generated.

  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 opposite to the engine body 1 side) of the shaft 60. In addition to the oil pump 61, an electric oil pump 62 (see FIG. 5) is provided in the case 57, and these oil pumps 61 and 62 are connected to a hydraulic control mechanism 63 described later. Then, the ECU 2 performs switching control between the oil pump 61 and the electric oil pump 62 and performs control such as switching of the oil path (fluid path) of the hydraulic control mechanism 63 and setting of the line pressure. Friction elements 67 to 71, which will be described later, are intermittently (fastened or released) by hydraulic control (pressure control of the working fluid).

  The reason why the electric oil pump 62 is provided separately from the oil pump 61 is that it is difficult to supply a desired line pressure depending on the oil pump 61 because the engine rotation speed is not sufficient when the engine is stopped or at the start of the engine. In this case, the line pressure is ensured, and the timing for switching between the oil pump 61 and the electric oil pump 62 is set from this viewpoint.

  The torque converter 51 is further provided with a lock-up clutch 64 that is interposed between the pump cover 53 and the turbine 55 and directly connects the crankshaft 3 and the turbine 55 via the cover 53. The lockup clutch 64 is connected to the oil pump 61 and the electric oil pump 62 via a hydraulic control mechanism 63, and on / off control of various solenoid valves provided in the hydraulic control mechanism 63 according to the vehicle speed. By doing so, the oil passage is switched, and the lockup clutch 64 is engaged / disengaged.

  On the other hand, the multi-stage speed change 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 is configured to switch forward speed, neutral state, and reverse speed by intermittently connecting these fastening elements 67 to 72 according to a shift range (D range, N range, R range, etc.). ing.

  The first and second planetary gear mechanisms 65 and 66 are respectively provided with sun gears 65a and 66a, and a plurality of (for example, three) planetary gears 65b and 66b that are disposed around and mesh with the sun gears 65a and 66a. A ring gear of the first planetary gear mechanism 65, which includes carriers 65c and 66c for supporting the planetary gears 65b and 66b, and ring gears 65d and 66d that are arranged so as to surround the planetary gears 65b and 66b. 65d and the carrier 66c of the second planetary gear mechanism 66 are coupled, and the carrier 65c of the first planetary gear mechanism 65 and the ring gear 66d of the second planetary gear mechanism 66 are coupled to each planetary gear mechanism 65, 66. Can be linked.

  The friction element includes a forward clutch 67 interposed between the turbine shaft 59 and the sun gear 65a of the first planetary gear mechanism 65, and a reverse clutch 68 interposed between the turbine shaft 59 and the sun gear 66a of the second planetary gear mechanism 66. A 3-4 clutch 69 interposed between the turbine shaft 59 and the carrier 66c of the second planetary gear mechanism 66, a 2-4 brake 70 for fixing the sun gear 66a of the second planetary gear mechanism 66, and these planets. A low reverse brake 71 or the like interposed in parallel between the gear mechanisms 65 and 66 and the case 57 is provided. The one-way clutch 72 only locks the carrier 65c and the ring gear 65d in one direction (the driving direction of the crankshaft 3) (unlocked) and prevents it from rotating in the opposite direction. These fastening elements 67 to 72 are intermittently connected, and 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, ◯ indicates a state in which the fastening elements 67 to 72 are fastened or locked, and no mark indicates a state in which they are released or unlocked. Accordingly, in the R range, the reverse clutch 68 and the low reverse brake 71 are engaged, and in the N range (neutral range), all the engagement elements 67 to 72 are released / unlocked. At the first speed of the D range (drive range), 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, At the third speed, the forward clutch 67 and the 3-4 clutch 69 are engaged, and at the fourth speed, the 3-4 clutch 69 and the 2-4 brake 70 are engaged.

  Similar to the lockup clutch 64, the friction elements 67 to 71 are connected to the oil pump 61 and the electric oil pump 62 via a hydraulic control mechanism 63 (see FIG. 5). The two-shift solenoid valves 83 and 84 and the first to third duty solenoid valves 85 to 87 are driven to switch and change the oil passages, hydraulic pressures, etc., and is intermittently performed.

  Specifically, the hydraulic control mechanism 63 includes a hydraulic control circuit as shown in FIG. 5, and this hydraulic control circuit is connected to the oil pump 61 and the electric oil pump 62 so that the original pressure is supplied from the pumps 61 and 62. Supplied. The hydraulic control mechanism 63 is arranged in the vicinity of the downstream side of the pumps 61 and 62 in the line 81 and the line 81 (oil passage) connected from the pumps 61 and 62 to the hydraulic chambers (not shown) of the friction elements 67 to 71. The first and second shift solenoid valves 83 and 84 (hereinafter simply referred to as “first and second SV”) for turning ON / OFF the regulator valve 82 provided for regulating the line pressure and the various valves for switching the 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 ECU 2. In addition, 1st and 2SV83,84 and 1st-3rd DSV85-87 are comprised as a three-way valve. Further, a switching valve 91 for switching 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, by operating various valves based on the vehicle speed, throttle opening, engine rotational speed, turbine rotational speed, and the like, the friction elements 67 to 71 are intermittently switched, so that the automatic transmission mechanism 50 is switched between a plurality of stages to correspond to the vehicle speed and the like. The ECU 2 is configured to perform control for selecting the gear according to the position of the shift lever or automatically. 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 of the respective solenoid valves 83 to 87 for the respective shift stages. In FIG. 7, the circles are ON for the first and second SVs 83 and 84, and are OFF for the first to third DSVs 85 to 87, both of which connect the upstream line to the downstream line. A state in which the original pressure is used as it is or as an operating pressure is supplied to the downstream side, and the x mark indicates that the first and second SVs 83 and 84 are OFF, and the first to third DSVs 85 to 87 are ON. Also shows a state in which the upstream line is blocked and 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, and the upstream line An operating pressure is generated using the pressure as an original pressure, and this operating pressure is supplied to the lock-up 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 the forward clutch pressure (operating pressure) is further supplied to the hydraulic chamber of the forward clutch 67 via the forward clutch line 81c. The forward clutch 67 is engaged.

  The time change of the operating pressure of the forward clutch 67 will be described together with the action of the forward clutch with reference to FIGS. First, by operating only the third DSV 87, hydraulic oil is supplied to the downstream line 81b and the forward clutch line 81c of the third DSV 87. At the time t1 when the lines 81b and 81c are filled with the hydraulic oil, the hydraulic pressures of the lines 81b and 81c, that is, the operating pressure of the forward clutch 67 increases. At the time t2 when the operating pressure reaches the predetermined value P1, the piston (not shown) of the forward clutch 67 in the released position starts to move in the fastening direction against the return spring (not shown). When the operating pressure reaches a predetermined value P2 and the forward clutch 67 moves to the contact position and the clearance (gap between the clutch plates) becomes zero (time point t3 in FIG. 8), the movement is restricted. As a result, the increase rate of the operating pressure increases, and the forward clutch 67 gradually shifts from the slipping state to the state where the transmission driving force is large. Then, at time t4 when the operating pressure reaches the predetermined operating pressure P3, the accumulator 90 is operated, whereby the rate of increase of the operating pressure is reduced, and the fastening proceeds while suppressing rapid torque fluctuation (shock). . The forward clutch 67 is completely engaged until time t5 when the capacity of the accumulator 90 is full. Furthermore, by raising the operating pressure, a sufficiently large fastening force that can cope with fluctuations in the transmission driving force accompanying sudden torque fluctuations is obtained. Even when a gear other than the first gear is selected, hydraulic control is performed on the friction elements 68 to 71 as in the forward clutch 67.

  Further, when the automatic transmission mechanism 50 is in a neutral state in which the hydraulic control mechanism 63 is controlled by the ECU 2 and the transmission of the driving force to the wheels is cut off, the friction elements 67 to 71 are immediately before the fastening as necessary. The state can be set to a so-called precharge state. That is, in general, in this type of automatic transmission mechanism, gear shifting or the like is performed by supplying the operating pressure generated by the hydraulic control circuit to the hydraulic chamber of the friction element at the time of shifting or engagement operation. Even when the operating pressure is generated and supplied to the hydraulic chamber of the friction element immediately after the start of the shifting operation, the hydraulic oil is drained from the hydraulic chambers of the hydraulic control circuit or the hydraulic chamber of the friction element, or the operating pressure decreases. In order to fill them with hydraulic oil during the shifting operation and move the friction element from the release position to the contact position, a time lag occurs for a predetermined time, and the fastening operation of the friction element is delayed. There was a problem.

  That is, in FIG. 8, since a certain time is required until the clutch is completely engaged after the time t3 when the clutch clearance disappears from the hydraulic oil supply start time t0, the hydraulic control mechanism 63 receives the switching signal of the automatic transmission mechanism 50. There was a problem in that the response from an acceleration request or the like was inferior due to a delay from the start to the complete fastening state.

  Therefore, in this embodiment, the ECU 2 is operated by the electric oil pump 62 when the automatic transmission mechanism 50 is in the neutral state and the friction elements 67 to 71 are in the released state at least during the automatic stop operation period of the engine. By supplying the pressure to increase the operating pressure for the friction elements 67 to 71 to the precharge pressure Pp, the friction elements 67 to 71 are moved in the fastening direction from the predetermined release positions, and the friction elements 67 to 71 are moved. The slip state (the state immediately before the fastening state) is not reached until the driving force is transmitted. As a result, the automatic transmission mechanism 50 is set in a precharged state in which the startup time of the operating pressure (period from time t0 to t2) and the movement time of the friction elements 67 to 71 (period from time t2 to time t3) are omitted. It is configured to be possible.

  For example, the precharge state of the forward clutch 67 will be described with reference to FIGS. When the forward clutch 67 is in the precharge state, the ECU 2 controls the third DSV 87 to adjust the operating pressure to the precharge pressure Pp. In the present embodiment, the precharge pressure Pp is slightly displaced in the release direction from the contact position P2 or the forward clutch 67 when the forward clutch 67 is moved to the substantially contact position and is in the slip state. In this case, the operating pressure is set to a value slightly lower than the operating pressure P2. Since the precharge pressure Pp changes depending on the oil temperature or the like, the precharge pressure Pp is set to a value slightly lower than the operating pressure P2 from the viewpoint of more reliably preventing the movement of the piston 13. preferable.

  Even when the friction elements other than the forward clutch 67 are in the precharged state, the operating pressure is adjusted to the precharge pressure by appropriately controlling the required DSV among the first DSV85, the second DSV86, and the third DSV87.

  Here, the precharge state is an initial precharge stage in which the line 81 connected to the friction elements 67 to 71 is filled with hydraulic oil, that is, in the example of the forward clutch 67, the line 81b is filled with hydraulic oil (0 <Pp ≦ P1) and a late precharge stage (P1 <Pp ≦ P2) in which the friction elements 67 to 71 are moved from the release position in the fastening direction via the initial precharge stage to be in a state immediately before fastening, that is, In the above example, the step includes the step of filling the line 81b with hydraulic oil and increasing the operating pressure to P2 (period t2 to t1 in FIG. 8). In the present embodiment, when the friction elements 67 to 71 are set in the precharge state, the precharge state (hereinafter also referred to as the late precharge state) in the late precharge stage similar to the forward clutch 67 is configured. Yes.

  The N range and D range described here do not indicate the shift operation position by the shift lever, but the substantial transmission state in which each solenoid valve is controlled. Therefore, the precharge state is automatically set to the N range (neutral state) while the shift operation position by the speed change lever remains at the D range position, and in this neutral state, the working fluid is supplied to the fluid path with a predetermined fluid. It is filled until the pressure is reached, and refers to the state just before the friction element is fastened.

  The ECU 2 includes a computer having a CPU, a ROM, a RAM, and the like. Specifically, various operations of the vehicle are performed by executing a program stored in the ROM (or RAM) in advance by the CPU. Be controlled. As shown in FIG. 9, the ECU 2 receives signals from the sensors 25, 26, 30 to 34 and outputs a signal for controlling the fuel injection amount and the injection timing to the fuel injection valve 16. An ignition timing control signal is output to the spark plug 15, a control signal for controlling the throttle opening is output to the actuator 24 of the throttle valve 23, and further to the regulator circuit 28 a of the alternator 28. A signal for controlling the amount of power generation is output. Further, the ECU 2 receives a signal from each of the sensors 25, 26, 30 to 39 and switches a switching signal for switching the source of the original pressure of the hydraulic control mechanism 63 between the oil pump 61 and the electric oil pump 62. A 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).

  The ECU 2 sets the predetermined engine stop condition so that it can be satisfied not only when the vehicle is idling but also when the vehicle is running. When the automatic engine stop condition is satisfied, the ECU 2 stops the fuel supply. The engine is automatically stopped and automatically during the automatic stop operation period of the engine or after the engine is automatically stopped, when a predetermined engine restart condition is established by an accelerator operation or the like by the occupant. The engine is automatically restarted. In this embodiment, a plurality of the above automatic stop conditions are set, and the engine is automatically stopped when all these conditions are satisfied. On the other hand, a plurality of restart conditions are set, and the engine is automatically restarted when one or more conditions are satisfied according to the contents of the conditions.

  This engine restart will be described in detail. In the following description, a cylinder that is in the compression stroke when the engine is stopped is referred to as a compression stroke cylinder (or a compression stroke cylinder at the time of stop). These are referred to as an expansion stroke cylinder (or an expansion stroke cylinder when stopped), an intake stroke cylinder (or an intake stroke cylinder when stopped), and an exhaust stroke cylinder (or an exhaust stroke cylinder when stopped). For convenience of explanation, it is assumed that the cylinder 12A is an expansion stroke cylinder, the cylinder 12B is an exhaust stroke cylinder, the cylinder 12C is a compression stroke cylinder, and the cylinder 12D is an intake stroke cylinder.

  First, the first-time combustion is performed on the compression stroke cylinder 12C at the time of stop, the piston 13 is pushed down, the in-cylinder pressure is increased by the reverse operation of raising the piston 13 of the stop-time expansion stroke cylinder 12A, and then the expansion stroke cylinder. The ECU 2 injects fuel into 12A to cause ignition and combustion, thereby increasing combustion energy in the expansion stroke cylinder 12A at the time of stop and restarting the engine by ensuring the stroke of the cylinder 12A. Is configured.

  Thus, in order to restart the engine only with the combustion energy, it becomes a problem how to maximize the combustion energy in the expansion stroke cylinder 12A at the time of stop. For this purpose, the piston 13 is stopped when the engine is stopped. Must be stopped within a predetermined range to appropriately secure the amount of air for combustion in the stop-time compression stroke cylinder 12C and the stop-time expansion stroke cylinder 12A. Therefore, with reference to the expansion stroke cylinder 12A at the time of stop, a predetermined range slightly beyond the center of the stroke, that is, the position at which the crank angle after compression top dead center is 90 ° CA slightly toward the bottom dead center, for example, after compression top dead center. If the piston 13 can be stopped within a range where the crank angle is 100 ° to 120 ° CA, a predetermined amount of air is secured in the compression stroke cylinder 12C at the time of stop, and the engine is slightly reversed by the initial combustion. In addition, sufficient energy can be ensured by combustion in the stop-stroke expansion stroke cylinder 12A.

  There are various specific methods for controlling the stop position of the piston 13 when the engine is automatically stopped. Here, the opening of the throttle valve 23 is controlled to control the expansion stroke cylinder 12A and the compression stroke cylinder 12C when the engine is stopped. The rotational speed of the engine is finely adjusted through the resistance of the crankshaft 3 by adjusting the compression reaction force caused by air and controlling the amount of power generated by the alternator 28 in the process of automatically stopping the engine. The rotational speed Ne is decreased along a reference line determined in advance by experiments or the like to control the stop position of the piston 13.

  Specifically, as shown in FIGS. 10 and 11, the ECU 2 releases the friction elements 67 to 71 at a time T0 when the engine automatic stop condition is satisfied, so that the automatic transmission mechanism 50 is driven ( Switching from the D range here to the neutral state (here, the N range in the precharge state). The neutral state in the automatic stop operation period of the engine (the period from when the automatic stop condition is satisfied until the engine is completely stopped) is the forward clutch 67, 3- The 4-clutch 69 and the 2-4 brake 70 are in a precharge state immediately before engagement. By switching the automatic transmission mechanism 50 to the neutral state in this way, the influence of the reverse driving force from the axle side can be eliminated. Note that, by setting the automatic transmission mechanism 50 to the neutral state of the precharged state, it is necessary to omit the period from time t0 to time t3 in FIG. 8 even when the restart condition is satisfied during the automatic engine stop operation period. Thus, the friction element can be quickly engaged to achieve a predetermined shift speed, and the reacceleration responsiveness can be improved.

  After the time T0, the ECU 2 further stabilizes the opening K of the throttle valve 23 at 15%, and at a time T1 when a predetermined time elapses, the engine speed Ne and the boost pressure Bt keep the piston 13 within a predetermined appropriate range. The fuel injection to each cylinder 12 is stopped when it is within a predetermined control appropriate range in which the control for stopping the engine properly can be executed. When the fuel injection is stopped at this time T1, the kinetic energy of the crankshaft 3 or the like is consumed due to mechanical loss due to frictional resistance or pumping work of each cylinder 12A to 12D, thereby causing the crankshaft 3 of the engine. The inertia is several revolutions, and in a 4-cylinder 4-cycle engine, it stops after reaching the compression top dead center of about 10 times.

  As described above, 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 influenced by the frictional resistance of the engine. It also changes depending on the rotational inertia of the engine at the time T4 when the compression top dead center is exceeded, 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 is automatically stopped, first, the compression reaction of the expansion stroke cylinder 12A and the compression stroke cylinder 12C. It is necessary to adjust the intake air flow rates for both cylinders 12A and 12C so that the force becomes sufficiently large and the compression reaction force of the expansion stroke cylinder 12A is larger than the compression reaction force of the compression stroke cylinder 12C by a predetermined value or more. .

  Therefore, in this embodiment, the expansion stroke cylinder 12A and the opening stroke cylinder 12A and the throttle opening 23 are set to a large value (for example, about 30% of the opening degree when fully opened) at the fuel injection stop time T1. After a predetermined amount of air is sucked into both the compression stroke cylinders 12C, at the time T2 when it is confirmed that the engine rotational speed Ne has dropped below a preset reference speed N1 (for example, about 790 rpm), the throttle The intake air amount is adjusted by closing the valve 23 and reducing the opening K thereof.

  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 in the sixth to second before is within a predetermined range as shown by hatching in FIG. 12, 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.

  Therefore, the ECU 2 sets the target generated current Ge 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 control for stopping the piston 13 within the appropriate range is possible. The engine is set to 0, and at the time T2 when the engine speed Ne drops below the reference speed N1, the control is performed to increase the target generated current Ge of the alternator 28 to a preset initial value, and then the engine is rotated at the top dead center. At the time T3 when the 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 outside of the engine By changing the load according to the degree of decrease in the engine speed Ne, the load is changed to the reference line set based on experiments conducted in advance. And it is configured to reduce the engine rotational speed Ne me.

  Summarizing the control of the ECU 2 at the time of the automatic engine stop, the ECU 2 controls the opening of the throttle valve 23 when the engine is automatically stopped, and the air in the expansion stroke cylinder 12A and the compression stroke cylinder 12C when the engine is stopped. While adjusting the compression reaction force and controlling the amount of power generated by the alternator 28 during the automatic engine stop process, the engine rotation speed is finely adjusted through the resistance of the crankshaft 3. Ne is decreased along a reference line determined in advance by experiments or the like, and control is performed to stop the piston 13 within a predetermined appropriate range.

  By the way, in this type of engine starter, when a predetermined restart condition is satisfied, it is desirable to quickly restart the engine and shift the vehicle to a state where it can be re-accelerated at an early stage. For this reason, after the engine is automatically stopped, regardless of whether the restart condition is satisfied or not, the automatic transmission mechanism 50 that is switched when the engine is automatically stopped is switched from the neutral state to the drive state to satisfy the restart condition. It is preferable to provide. However, when the automatic transmission mechanism 50 is switched to the drive state, when the vehicle is traveling, a reverse driving force is transmitted from the axles 78 and 79 to the turbine 55 via the multi-stage transmission mechanism 52, and this reverse driving force is generated. By acting on the pump impeller 54 via the hydraulic oil, it acts on the crankshaft 3, which may cause the piston 13 that has been stopped within a predetermined appropriate range of the folding angle to move.

  Therefore, in this embodiment, the influence of the reverse driving force is suppressed as follows. First, at the time of slow deceleration, for example, as shown in FIG. 11, when the vehicle is slowly decelerated like the vehicle speed V101 by coasting with the accelerator operation A101 turned off and the brake operation B101 turned off, the automatic transmission mechanism including the torque converter 51 50, if the rotational speed of the turbine 55 (hereinafter referred to as turbine rotational speed) does not reach a certain rotational speed Tri (hereinafter referred to as influence rotational speed), the engine crankshaft 3 is not rotated by the reverse driving force from the wheel side. By effectively utilizing this characteristic, control is performed to switch to the drive state after the engine is stopped (gear stage G101) within a range where the turbine rotational speed does not exceed the above-mentioned affected rotational speed Tri.

  Here, the ECU 2 calculates a predicted value of the turbine rotational speed (hereinafter referred to as a predicted turbine rotational speed Tre) when the automatic transmission mechanism 50 is switched to the drive state when the automatic transmission mechanism 50 is in the neutral state, and the crank angle sensor 30, 31. When it is determined that the engine is automatically stopped based on the detection result 31 and when it is determined that the predicted turbine rotational speed Tre is lower than the above-described affected rotational speed Tri, the automatic transmission mechanism 50 is moved from the neutral state to the predetermined gear position. It is controlled to switch to the drive state.

  Specifically, when the ECU 2 determines that the engine is stopped based on the detection results of the crank angle sensors 30 and 31, the ECU 2 uses the vehicle speed sensor 38 at predetermined intervals from the time when the engine stops until the restart condition is satisfied. Detect the vehicle speed. When the automatic transmission mechanism 50 is switched from the neutral state to the drive state, the turbine rotational speed Tre at the time when the switching is completed is predicted. Specifically, the predicted turbine rotation speed Tre is determined in the ECU 2 based on the vehicle speed detected by the vehicle speed sensor 38, and the gear position corresponding to the vehicle speed is determined based on the switching map of FIG. It is selected and calculated by applying to a predetermined mathematical formula based on the vehicle speed, deceleration, gear ratio of the selected gear, the tire diameter inputted in advance, the gear ratio of the differential mechanism 77, and the like. .

  On the other hand, the affected rotational speed Tri differs depending on the configuration of the automatic transmission mechanism 50, and is obtained in advance through experiments or the like and stored in the ECU 2. In the present embodiment, the affected rotational speed Tri is 1200 rpm which is higher than the idle rotational speed (650 rpm in the D range).

  Then, the ECU 2 waits for switching of the automatic transmission mechanism 50 until the predicted turbine rotational speed Tre falls below the affected rotational speed Tri, and the predicted turbine rotational speed Tre falls below the affected rotational speed Tri (predicted turbine rotational speed Tre <impact). The automatic transmission mechanism 50 is configured to switch from the neutral state to the drive state at the time of the rotational speed Tri). Here, even if the automatic transmission mechanism 50 is in the drive state, the turbine rotational speed at that time is lower than the influence rotational speed Tri, so that the reverse driving force does not affect the stop position of the piston 13.

  On the other hand, at the time of sudden deceleration, for example, when the accelerator operation A102 is turned off and the brake operation B102 is turned on (particularly strong) as shown in FIG. The precharge neutral state is continued even if the rotational speed is less than the affected rotational speed Tri (shift stage G102). Therefore, since the reverse driving force from the axle side is not transmitted to the crankshaft 3, the stop position of the piston 13 is not affected.

  Next, control during engine restart will be described. When the predetermined restart condition is satisfied for the engine that is in the automatic stop state as described above and the piston 13 of the stop expansion stroke cylinder 12A is within the predetermined appropriate range, the ECU 2 The in-cylinder pressure of the stop-time expansion stroke cylinder 12A is increased by executing the initial combustion in the stop-time compression stroke cylinder 12C to reversely operate the engine, and the stop-time expansion stroke in a state where the in-cylinder pressure is thus increased. Control is performed so that the engine is automatically restarted by injecting fuel into the cylinder 12A to cause ignition and combustion.

  However, when the restart condition is satisfied before the automatic transmission mechanism 50 is switched from the neutral state to the drive state, the ECU 2 executes the combustion in the stop-time compression stroke cylinder 12C regardless of the predicted turbine rotational speed Tre. Then, after the combustion of the expansion stroke cylinder 12A at the time of stop is executed, the automatic transmission mechanism 50 is configured to be switched from the neutral state to the drive state. Specifically, the initial combustion for engine restart is executed so that the automatic transmission mechanism 50 is completely switched to the drive state at a predetermined time after the reverse rotation operation of the engine is finished and the forward rotation operation is started. Thereafter, a switching signal is output to the automatic transmission mechanism 50 after a predetermined time (for example, 0.05 seconds) has elapsed. As described above, when the automatic transmission mechanism 50 is switched to the drive state after the combustion associated with the restart is performed in the stop expansion stroke cylinder 12A, when the predicted turbine rotational speed Tre exceeds the affected rotational speed Tri, The reverse driving force is applied to the crankshaft 3. Since the combustion in the stop compression stroke cylinder 12C and the stop expansion stroke cylinder 12A is executed before the reverse drive force is applied, the automatic transmission mechanism 50 It is possible to prevent deterioration of restartability due to the movement of the piston 13 due to the reverse driving force accompanying the switching of the engine, and restart until the piston 13 of the intake stroke cylinder 12D at the time of stop passes the compression top dead center at which it first meets. The reverse driving force acts on the crankshaft 3 during the unstable period, and this reverse driving force can be used as an assist when restarting the engine. Can be reliably restarted. Moreover, since the restart assist by the reverse driving force acts after the reverse rotation of the engine, the reverse pressure operation of the engine is not hindered, and the in-cylinder pressure of the expansion stroke cylinder 12A can be effectively increased. .

  As described above, even when the automatic transmission mechanism 50 is switched and before switching, the engine is restarted as follows. That is, when a predetermined restart condition is established after the engine is stopped, the ECU 2 performs control to automatically restart the engine. At this time, the stop position of the piston is a predetermined value in the vicinity of the stroke intermediate portion in the expansion stroke cylinder. If it is within the appropriate range, the engine is once reversely operated and then restarted.

  This engine restart control will be described based on the time charts of FIGS. 13 and 14. The engine restart control is not limited to this, and may be other known restart control.

  As shown in FIGS. 13 and 14, first, the first fuel injection J2 is performed in the compression stroke cylinder 12C (third cylinder), and combustion ((1) in FIG. 13) is performed by the ignition. With the combustion pressure (part a in FIG. 14) due to this combustion (1), the piston 13 of the 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 stroke cylinder 12A (first cylinder) starts to move in the direction of 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. 14).

  When the piston 13 of the 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. 13). The engine is driven in the forward rotation direction by the pressure (c portion in FIG. 14).

  Further, fuel (J3) richer than the combustible air-fuel ratio is injected into the compression stroke cylinder 12C at an appropriate timing ((3) in FIG. 13), but the compression stroke cylinder 12C does not burn. The compression pressure of the compression stroke cylinder 12C is reduced by the latent heat of vaporization caused by the fuel injection (part d in FIG. 13), and accordingly, the compression top dead center (the first compression top dead center from the start of the start) is exceeded. The initial combustion energy of the consumed expansion stroke cylinder 12A is reduced.

  Furthermore, the timing of fuel injection (J4) in the intake stroke cylinder 12D, which is the next combustion cylinder, is set to an appropriate timing ((4) in FIG. 13) for lowering the temperature in the cylinder and the compression pressure by the latent heat of vaporization of the fuel. As shown, for example, after the middle stage of the compression stroke), self-ignition before the compression top dead center is prevented in the compression stroke of the intake stroke cylinder 12D. Further, in combination with the ignition timing of the intake stroke cylinder 12D being set after the compression top dead center, combustion before the compression top dead center is prevented (part e in FIG. 14). That is, by reducing the compression pressure by the fuel injection (J4) and not performing the combustion before the compression top dead center, the energy of the first combustion in the expansion stroke cylinder 12A becomes the compression top dead center (the second compression from the start of the engine start). It is possible to suppress consumption to exceed the top dead center.

  In this way, the energy of the first combustion ((2) in FIG. 13) in the expansion stroke cylinder 12A causes the engine to have the first compression top dead center ((3) in FIG. 13) after the start of restart and the second The compression top dead center ((4) in FIG. 13) can be exceeded, smooth and reliable startability can be ensured, and thereafter, normal operation is started.

  Next, the control of the automatic transmission mechanism in the vicinity from the engine stop to the restart will be described separately for the slow deceleration and the sudden deceleration.

  At the time of slow deceleration after the engine is stopped, the automatic transmission mechanism 50 is switched from the neutral state to the drive state when the above (predicted turbine rotational speed Tre <influenced rotational speed Tri) is established. For example, in the example shown in FIG. 11, immediately after the time T5 when the engine rotation speed N100 becomes 0 and the engine is completely stopped, the above (predicted turbine rotation speed Tre <influenced rotation speed Tri) is established and the gear stage G101 is driven ( 4th speed). At this time, since the forward clutch 67, the 3-4 clutch 69, and the 2-4 brake 70 are precharged in the neutral state in advance, it is possible to quickly switch to the drive state. As shown in FIG. 4, since it is necessary to fasten the 3-4 clutch 69 and the 2-4 brake 70 at the fourth speed, the operating pressure of these friction elements is quickly increased from the precharged state and fastened in a short time. Can be made. Thereafter, as the vehicle speed V101 decreases, the vehicle is sequentially shifted to the third speed and the first speed based on the switching map of FIG.

  Then, the engine is restarted at the time T6 when the engine restart condition (in the example of FIG. 11, the brake operation B101 is OFF and the vehicle speed V is 10 km / h or less) is satisfied (engine speed N101). At this time, the gear stage G101 of the automatic transmission mechanism is shifted to the first speed according to the vehicle speed, and the driving force from the engine can be appropriately transmitted to the axles 78 and 79 without delay. If the driver continues the accelerator operation A101 and the brake operation B101 as it is, the vehicle will creep.

  On the other hand, at the time of sudden deceleration, the neutral state of the automatic transmission mechanism 50 is continued as it is even if the above (predicted turbine rotational speed Tre <influenced rotational speed Tri) is established (shift stage G102), and the neutral state is accompanied by the restart of the engine. It is configured to switch from the drive state to the drive state. In this case, the forward clutch 67, the 3-4 clutch 69 and the 2-4 brake 70 are set in the precharged state in the neutral state so that an appropriate response can be made at any timing (vehicle speed). Switch to the drive state at the optimum gear position according to the vehicle speed (accelerator opening may be taken into consideration).

  In the example of FIG. 11, at the time T11, the restart condition that the brake operation B102 is OFF and the vehicle speed V is 10 km / h or less is satisfied, and the engine is restarted (engine speed N102). Then, the gear stage G102 is switched to the first speed according to the vehicle speed at that time. As shown in FIG. 4, since it is necessary to fasten the forward clutch 67 at the first speed, the operating pressure can be quickly increased from the precharged state and fastened in a short time.

  In the example of FIG. 11, the accelerator operation A102 is turned ON at time T12 immediately after time T11. This means that the driver is requesting reacceleration. Even in such a case, since the forward clutch 67 is quickly engaged, the driving force is immediately transmitted at the first speed and re-accelerated (vehicle speed V102). That is, high reacceleration responsiveness is obtained.

  In both cases of slow deceleration and sudden deceleration, the precharge state is released as soon as possible after the engine stops (for example, the precharge state is continued until time T6 during slow deceleration). Therefore, the progress of the deterioration of the friction element over time due to the precharged state is suppressed to such a level that there is almost no need to worry about it.

  Next, the control operation when the ECU 2 automatically stops and restarts the engine will be described based on the flowcharts shown in FIGS.

  FIG. 15 shows a main flowchart of the automatic stop / 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 included in the engine automatic stop condition. In this embodiment, the FC condition is also used as a fuel injection stop condition during deceleration executed for a predetermined period during vehicle deceleration. Specifically, as the FC condition, it is determined whether or not the engine rotational speed Ne is larger than a predetermined reference value Nfc for stopping fuel injection set to about 1200 rpm that is set in advance, and the vehicle speed is set to a predetermined value ( For example, it is determined whether it is 10 km / h) or more and the accelerator sensor 34 is in an OFF state.

  If it is determined as YES in step S1, it is determined based on the vehicle speed detected by the vehicle speed sensor 38 whether or not the lockup clutch 64 of the torque converter 51 is in a non-lockup region. (Step S2). That is, the lock-up clutch 64 of the torque converter 51 is configured to be engaged / disengaged based on a signal output from the ECU 2 in accordance with the vehicle speed, and the vehicle is decelerated while the lock-up clutch 64 is engaged. Since the fuel consumption reduction effect can be obtained by stopping the fuel injection at the time of deceleration performed normally, the stop of the fuel injection at the time of deceleration is first used. Therefore, the stop of the fuel injection for the automatic engine stop is executed when the vehicle is stopped or when the vehicle is decelerating and the vehicle is out of the traveling state in which the fuel injection stop control at the time of deceleration can be controlled. When the fuel injection is stopped, when the vehicle goes out of the lockup region, the fuel injection stop at the time of deceleration is used as the fuel injection stop for the automatic stop. Therefore, the condition that the running state of the vehicle is in the non-lockup region is also included in the automatic stop condition.

  If the determination in step S2 is YES, the engine automatic stop and restart control shown in FIG. 16 is executed (step S3), and then the normal engine control is transferred when the engine is restarted (step S3). S4) Returned. The engine automatic stop and restart control will be described later.

  On the other hand, if it is determined NO in step S2 and it is determined that the lockup clutch 64 is in the engaged state, the fuel injection stop during deceleration that is normally performed over a predetermined period during vehicle deceleration (Fuel Cut during deceleration). ) Is stopped (step S5), and the process returns. Even when the deceleration fuel injection stop is executed and the return is performed, if the FC condition is satisfied and the lockup clutch 64 is released (YES in both steps S1 and S2). ) Using the stop of fuel injection at the time of deceleration, the engine automatic stop and restart control which will be described later is executed as it is, and the fuel efficiency improvement effect can be improved.

  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 fuel injection stop (FC) is executed (step S6). If it is determined NO in step S6, the process is returned as it is. On the other hand, if it is determined that the fuel injection is stopped (YES in step S6), the routine proceeds to normal control of the engine. Thus, the fuel injection to each cylinder 12 is restored (step S4).

  Here, the engine automatic stop and restart control executed in step S3 of the flowchart shown in FIG. 15 will be described based on the flowchart of FIG.

  When it is determined in steps S1 and S2 of the flowchart shown in FIG. 15 that a part of the automatic stop condition is satisfied, the engine automatic stop / restart control is started, and a time point T1 when the automatic stop condition is partially satisfied. Thus, the automatic transmission mechanism 50 is switched from the drive state to the neutral state (step S51). The neutral state in this automatic stop operation period is the above-described late-stage precharge state. Specifically, the oil pump is a pump that outputs signals from the ECU 2 to the switching valve 91, the electric oil pump 62, the solenoid valves 83 to 87 of the hydraulic control mechanism 63, etc., and supplies the original pressure to the hydraulic control mechanism 63. In addition to switching from 61 to the electric oil pump 62, the solenoid valves 83 to 87 are adjusted to bring the friction elements 67 to 71 into the open state (neutral state), and at least the forward clutch 67, the 3-4 clutch 69 and 2-4. The brake 70 is shifted to the precharge state. Therefore, in the neutral state of this precharge, the transmission of the driving force including the reverse driving force is disconnected between the crankshaft 3 and the axles 78 and 79 while ensuring a quick transition to the engaged state. Thus, it is possible to stop the piston 13 within a predetermined appropriate range without being influenced by the reverse driving force while improving the response to the establishment of the restart condition.

  Next, after adjusting the opening degree K of the throttle valve 23 to 15% (step S52) and stabilizing the boost pressure Bt, is the stop appropriate condition established to check whether the automatic stop can be properly performed? A determination of whether or not is made (step S53). The appropriate 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. One of them. Specifically, it is determined whether or not the engine rotation speed Ne detected by the crank angle sensors 30 and 31 is within a predetermined range (for example, a range of 790 to 1200 rpm) where the engine can be automatically stopped. It is determined whether or not the boost pressure Bt detected by the atmospheric pressure sensor 26 is within a predetermined range (for example, −450 to −300 mmHg) in which the engine can be automatically stopped. 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. However, either one, preferably only the engine speed Ne may be within a predetermined range. Even in this case, a certain degree of accuracy can be ensured.

  If it is determined as NO in step S53, it is difficult to stop the piston 13 of the expansion stroke cylinder 12A at the stop in a predetermined appropriate range. The mechanism 50 is switched from the neutral state to the drive state (step S54). In addition, there is a case where the process proceeds to step S54 in the next routine from the state in which the fuel injection during deceleration is stopped in step S5 of the flowchart shown in FIG. Thus, after the automatic transmission mechanism 50 is switched to the drive state, the process returns to step S4, and the fuel injection is restored by the normal engine control in step S4.

  On the other hand, if it is determined as YES in step S53, it is determined whether or not the fuel injection during deceleration executed when the vehicle is decelerated has already been performed in step S5 of the flowchart shown in FIG. S55) If the fuel injection is not stopped, the fuel injection for each cylinder 12 is stopped at a time T1 when a predetermined time has elapsed since the opening K of the throttle valve 23 is set to 15%. (Step S56), and if it is determined YES in step S55, step S56 is skipped. In addition, when the fuel injection is stopped including the step S5, the ignition by the spark plug 15 is stopped when a predetermined time set in advance thereafter.

  Then, based on the engine rotational speed Ne, the engine top dead center rotational speed ne, etc., the opening K of the throttle valve 23 is controlled (step S57), and 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 power generation amount of the alternator 28 during the engine automatic stop operation period (step S58), the engine rotational speed is finely adjusted through the resistance of the crankshaft 3, thereby the fuel injection. After the stop time T1, the engine rotational speed Ne is decreased along a reference line determined in advance through experiments or the like, and control is performed to stop the piston 13 within a predetermined appropriate range.

  An example of control of the opening degree K of the throttle valve 23 and control of the target generated current Ge of the alternator 28 will be specifically described. First, regarding the opening degree control of the throttle valve 23, at the fuel injection stop time T1, the throttle valve 23 is opened, and the opening degree K is larger than the adjusted opening degree (15% in the above example) (for example, 30%). Thereafter, it is determined whether or not the engine rotational speed Ne has become equal to or lower than a reference speed N1 set in advance to about 790 rpm, so that after the fuel injection stop time T1 shown in FIG. 10 and FIG. It is determined whether or not the speed Ne has started to decrease. At a time T2 when it is determined that the speed Ne 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 when the throttle valve 23 is opened starts to decrease with a predetermined time difference accompanying the movement from the throttle valve 23 to the cylinder 12 in accordance with the closing operation of the throttle valve 23. become.

  Next, regarding the target generated current control of the alternator 28, the power generation is stopped by setting the target generated current Ge of the alternator 28 to 0 at the fuel injection stop time T1. Then, at the time T2 when the engine speed Ne drops below the reference speed N1 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. The power generation control to be started is started. As a result, a predetermined rotational resistance acts on the crankshaft 3 of the engine. Subsequently, when the engine top dead center rotational speed ne falls within a predetermined control appropriate range, the target power generation 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 stored in advance in the ECU 2 and is determined based on a map showing the relationship between the top dead center rotational speed ne and the target generated current Ge. .

  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, a return condition for fuel injection such as the accelerator sensor 34 being turned on. Whether or not is established is determined (step S59). If YES is determined in this step S59, the fuel injection for each cylinder 12 is restored and returned, and the routine proceeds to normal engine control shown in step S4.

  On the other hand, if NO is determined in step S59, it is determined whether or not the engine is stopped (step S61), and steps S57 to S59 are repeatedly executed until the engine is stopped. . Then, when it is determined YES in step S61, engine restart control is executed (step S62), and the process returns to the flowchart shown in FIG.

  Next, engine restart control executed in step S62 of the flowchart shown in FIG. 16 will be described based on the flowchart of FIG.

  When it is confirmed in step S61 in FIG. 16 that the engine is completely stopped, the predicted turbine rotational speed Tre is calculated by the ECU 2 prior to the switching of the automatic transmission mechanism 50, and the predicted turbine rotational speed Tre is influenced by the affected rotation. It is determined whether or not the speed is lower than the speed Tri (step S101). If it is determined YES, the process proceeds to step S102 to perform switching control by deceleration (details will be described later with reference to FIG. 18). Do.

  If it is determined in step S101 that the predicted turbine rotational speed Tre is equal to or greater than the influence rotational speed Tri (NO in step S101), the friction impellers 67 to 71 are brought into the engaged state to cause the pump impeller from the turbine 55 of the torque converter 51. A reverse driving force acts on the piston 54 so that the piston 13 moves. Therefore, it is determined that the predetermined engine restart condition is satisfied in the neutral state (step S105), and the standby state is entered unless the restart condition is satisfied.

  If it is determined in step S105 that the engine restart condition is satisfied, for example, if an accelerator operation for acceleration is performed, if the battery voltage decreases, or if the air conditioner is activated, the engine Is restarted (step S106).

  Although the specific control for this restart is not specifically limited, For example, it can comprise as follows. That is, the amount of air in the stop-time compression stroke cylinder 12C is calculated, fuel injection is performed so that the air-fuel ratio becomes rich, and after a time set in consideration of the vaporization time of the injected fuel, Ignition is performed on the cylinder 12C. The ignition to the compression stroke cylinder 12C at the time of stop is repeatedly performed until the engine is rotated by detecting the rising or falling of the crank angle sensors 30, 31. As a result, the engine is operated in reverse to increase the in-cylinder pressure of the stop-time compression stroke cylinder 12C.

  Next, a predetermined air-fuel ratio with respect to the air amount in the stop expansion stroke cylinder 12A is determined by a predetermined map, fuel is injected so as to be the air-fuel ratio, and the in-cylinder pressure is increased by the reverse operation of the engine. The cylinder 12A is ignited. As a result, the engine starts to operate in the forward rotation direction.

  Then, an amount of fuel obtained from a map determined in advance for the compression stroke cylinder 12C is injected into the latter half of the compression stroke cylinder 12C, and the compression top dead center of the cylinder 12C is caused by the latent heat of vaporization of the injected fuel. By reducing the compression reaction force in the vicinity, the compression top dead center can be easily exceeded. After the second combustion of the stop-time compression stroke cylinder 12C, fuel injection is performed to the stop-time intake stroke cylinder 12D that reaches the compression top dead center so that, for example, the air-fuel ratio is in a lean state, and the reverse torque In order to suppress the occurrence of this, the ignition timing is delayed after the top dead center and ignited before the normal engine control shown in step S4 is performed.

  In this way, the engine is restarted in step S106, and the count of the timer built in the ECU 2 is started (tm = 0).

  The time measured by this timer waits for the elapse of a predetermined time (for example, 0.05 seconds) after executing the initial combustion in the stop-time compression stroke cylinder 12C for the reverse rotation operation of the engine (step S107), and the automatic shift By outputting a switching signal for switching from the neutral state to the driving state to the mechanism 50, the switching of the automatic transmission mechanism 50 is completed after the forward rotation of the engine (step S108), and the process returns. That is, the predetermined time is set in consideration of a time lag from when the automatic transmission mechanism 50 receives the switching signal until the driving state where the driving force is actually transmitted is completed. The timing is set so that it is after the forward rotation of the engine and until the compression top dead center at which the intake stroke cylinder 12D at the time of stop comes first after the restart. Therefore, the above-mentioned timer built in the ECU 2 restarts the piston 13 of the stop-time intake stroke cylinder 12D from the time when the piston 13 of the stop-time intake stroke cylinder 12D first passes through the compression top dead center when the engine is restarted. The automatic transmission mechanism 50 is switched within the unstable period. Thus, since the automatic transmission mechanism 50 is switched to the drive state after the reverse rotation operation of the engine is completed, the reverse rotation force of the axles 78 and 79 does not impede the reverse rotation operation of the engine, and the stop expansion stroke cylinder. The in-cylinder pressure of 12A can be sufficiently increased. In addition, the reverse driving force acts during forward rotation of the engine, thereby assisting the restart of the engine in the unstable restart period in which the stop-time intake stroke cylinder 12D first reaches the compression top dead center after the restart. Can be restarted more reliably.

  When the automatic transmission mechanism 50 is switched, the movement of the piston 13 may be detected based on the crank angle sensors 30 and 31. If it is determined that the piston 13 is moving, the engine is operated by a starter motor described later. It may be one that assists restarting.

  The shift speed selected in step S108 is determined based on the vehicle speed detected by the vehicle speed sensor 38 and the throttle opening based on the accelerator sensor 34 based on the switching map of FIG. Here, since the forward clutch 67, the 3-4 clutch 69 and the 2-4 brake 70 are precharged in advance, even if any of the first to fourth gears is selected, the drive state is quickly switched. It can be performed.

  Next, switching control by deceleration executed in step S102 of the flowchart shown in FIG. 17 will be described based on the flowchart of FIG.

  In this flow, the vehicle deceleration Ac is first compared with a predetermined threshold Ac1. The deceleration Ac and the threshold Ac1 are both absolute values (the same applies hereinafter). The deceleration Ac is obtained based on the degree of change in vehicle speed that is sequentially detected by the vehicle speed sensor 38. If YES in step S111 (Ac <Ac1), that is, if it is determined that the vehicle is in the slow deceleration state, the automatic transmission mechanism 50 is switched from the neutral state to the drive state as in step S108 in FIG. 17 (step S112).

  Then, a predetermined engine restart condition is satisfied (for example, when an accelerator operation for acceleration is performed, when the battery voltage is lowered, when the air conditioner is operated, or when the brake is OFF and the vehicle speed is 10 km / h or less. Or the like) (step S113). During this standby, the automatic transmission mechanism 50 sequentially shifts the gear position to the low speed side based on the switching map of FIG. 6 as the vehicle speed decreases.

  When the engine restart condition is satisfied (YES in step S113), the engine is restarted similarly to step S106 in FIG. At this time, since the automatic transmission mechanism 50 is already in the drive state of an appropriate shift stage according to the vehicle speed, the driving force generated by the engine restart is immediately transmitted to the wheel side, and the restart with good responsiveness is performed. Can be achieved.

  Going back to step S111, if NO (Ac ≧ Ac1), that is, if it is determined that the vehicle is in a sudden deceleration state, the precharge neutral state is maintained as it is (step S121). Then, a predetermined engine restart condition is satisfied (for example, when an accelerator operation for acceleration is performed, when the battery voltage is lowered, when the air conditioner is operated, or when the brake is OFF and the vehicle speed is 10 km / h or less. Or the like) (step S122). Thereafter, when the engine restart condition is satisfied (YES in step S122), the automatic transmission mechanism 50 is switched from the neutral state to the drive state in the same manner as in step S112 (step S123). Also at this time, since switching is performed from the precharge state, rapid switching can be realized. Therefore, even during sudden deceleration, it is possible to quickly obtain an appropriate shift speed according to the vehicle speed, and to improve reacceleration responsiveness. Then, the engine is restarted similarly to step S114 (step S124), and the process returns.

  As described above, the ECU 2 switches the automatic transmission mechanism 50 from the drive state to the neutral state and automatically stops the engine when the automatic stop condition is satisfied while the vehicle is running, and the vehicle deceleration Ac is greater than the threshold value Ac1. At the time of small slow deceleration, after the engine is stopped, the shift stage of the automatic transmission mechanism 50 is sequentially shifted to the low speed stage side according to the vehicle speed, while at the time of sudden deceleration when the vehicle deceleration Ac is equal to or greater than the threshold value Ac1, While the transmission mechanism 50 is in the neutral state, the friction elements to be engaged in order to establish the respective shift stages are set in the precharge state in the late precharge stage with respect to a plurality of shift stages. Influence of reverse drive from the wheel side with the automatic transmission 50 in the neutral state while automatically stopping to improve fuel economy Reliably suppressed, switching can be performed rapidly to the drive state at the time of automatically restart the engine in accordance with yet re-acceleration request.

  The engine starting device described above is an embodiment of the device to which the starting device according to the present invention is applied, and the specific configuration of the device is appropriately changed without departing from the gist of the present invention. This is possible, and modifications will be described below.

  (1) In the above embodiment, when the engine is restarted, the engine is once reversely rotated and then rotated forward, but may be restarted only by the forward rotation. However, once the engine is reversely operated, the combustion energy of the stop-stroke expansion stroke cylinder 12A increases, so that the engine can be restarted more reliably.

  (2) Although omitted in the above embodiment, when the engine is restarted and a predetermined condition is satisfied, for example, when the piston stop position is not within the predetermined proper range or within the proper range, the stop is performed. When the position is close to the boundary of the appropriate range, or when the engine rotation speed does not reach the predetermined value by the predetermined time after the start, and when the initial combustion of the engine is performed in the stop expansion stroke without further reverse rotation of the engine For example, control with assist by a starting motor or the like may be performed. Even in this case, the burden on the starter motor can be reduced by the energy generated by the combustion of the engine. However, in this case, the fuel injection valve 16 may inject the fuel in the intake stroke so that vaporization and atomization of the injected fuel and mixing with the air proceed sufficiently directly into each cylinder. preferable.

  FIG. 19 is a modified example of FIG. 17, in which the initial combustion of the engine is performed in the expansion stroke at the stop without performing the reverse rotation operation of the engine, the control with the assist by the starting motor is performed, and the starter and the alternator are The restart control suitable for the case where the control with the assist by the integrated motor (ISG: Integrated Starter Generator) is performed is shown.

  This control is NO in step S101, that is, when the turbine rotational speed is high to some extent, if YES in step S105, that is, if the restart condition is satisfied, the effect of reverse drive from the axles 78 and 79 side is determined as the engine restart operation. It is intended to be used for restarting the engine by actively receiving it from the beginning.

  In this flow, step S101 and step S105 are the same as those in FIG. 17, and step S102 is also the same as FIG. 17 except that the engine restart method is different (since the first reverse rotation operation is not performed), so the duplicated explanation is omitted. To do.

  If YES is determined in step S105, the automatic transmission mechanism 50 is switched from the precharge neutral state to the drive state (step S306) as described in step S108 of FIG. In addition, the timer built in the ECU 2 starts counting (tm = 0). Then, after a predetermined time (for example, 0.1 seconds) required for complete engagement of the friction element is elapsed (step S307), the engine is restarted (step S308). This restart of the engine does not perform the reverse rotation operation but rotates the engine in the normal rotation direction from the beginning.

  If it does in this way, reverse driving force will act on a crankshaft by switching to a drive state (Step S306), and it will try to rotate an engine in the direction of forward rotation. Since this acts as an engine restart assist in step S308, the assist force of the starter motor and the like can be reduced.

  (3) In the above embodiment, the automatic transmission mechanism 50 is switched from the neutral state to the drive state when the predicted turbine rotational speed Tre falls below the influence rotational speed Tri. The monitoring may be performed by the crank angle sensors 30, 31 and the like. When the piston 13 moves, it may be determined again whether or not the piston 13 is stopped within an appropriate range, and the starter motor may assist as necessary.

  (4) In the above embodiment, the automatic transmission mechanism 50 is in the late-stage precharge state during the engine automatic stop operation period, but it may be in the early-stage precharge state. Responsiveness after establishment of the engine restart condition can be improved as compared with the case where the charging state is not established.

  (5) In the above embodiment, the in-cylinder injection type is used as the fuel injection valve 16, but the present invention can also be applied to the case where a port injection type fuel injection valve is used.

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 relationship figure which shows the example of a relationship between the operating state of the friction element in the automatic transmission mechanism, and a gear stage. It is the schematic which shows an example of the hydraulic control circuit of the automatic transmission mechanism in the starting device which concerns on this invention. It is a switching map of the automatic transmission mechanism according to the vehicle speed and the throttle opening in the starting device. It is a relationship figure which shows the example of a relationship between the operating state of the solenoid valve in the automatic transmission mechanism, and a gear stage. It is explanatory drawing which shows the time change of the working pressure in the hydraulic control circuit of the automatic transmission mechanism. It is a block diagram in the starting device concerning the present invention. It is a time chart which shows the change state of the engine speed at the time of an engine stop, change states, such as a throttle opening and a target electric power generation current. 6 is a time chart showing an accelerator operation, a brake operation, a gear position, an engine speed and a vehicle speed corresponding to slow deceleration and rapid deceleration, respectively, when the engine is automatically stopped during deceleration. 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 time chart which shows the combustion operation etc. 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 the control operation of an engine. It is a flowchart which shows the control action at the time of an automatic stop and restart of an engine. It is a flowchart which shows engine restart control. It is a flowchart which shows the switching control by the deceleration of a vehicle. It is a flowchart which shows the modification of engine restart control.

Explanation of symbols

1 Engine body 2 ECU (stop / restart control means)
DESCRIPTION OF SYMBOLS 3 Crankshaft 35 Brake sensor 38 Vehicle speed sensor 50 Automatic transmission mechanism 63 Hydraulic control mechanism 67-71 Friction element Ac Vehicle deceleration Ac1 Vehicle deceleration threshold

Claims (4)

When the engine automatic stop condition that can be satisfied even when the vehicle is running is satisfied, the fuel supply to the engine is stopped to stop the engine, and the restart condition of the engine in the automatic stop state is satisfied An engine starter comprising stop / restart control means for igniting supplied fuel and automatically restarting the engine,
It has a plurality of friction elements that are interrupted by fluid pressure control. By intermittently connecting these friction elements, the drive state in which the driving force can be transmitted to the wheel side and the transmission of the driving force to the wheel side are separated. An automatic transmission mechanism configured to switch between a neutral state and a precharge state in which a predetermined fluid path connected to the friction element is filled with a working fluid until a predetermined fluid pressure is reached;
A vehicle speed sensor for detecting the vehicle speed,
The stop / restart control means switches the automatic transmission mechanism from the drive state to the neutral state and automatically stops the engine when the automatic stop condition is satisfied while the vehicle is running,
Further, when the vehicle deceleration is relatively small, the automatic transmission mechanism shifts the gear position of the automatic transmission mechanism to the low speed gear side sequentially according to the vehicle speed after the engine is stopped.
When the vehicle is decelerating with a relatively large deceleration, after the engine is stopped, the friction element to be engaged in order to establish each shift stage for a plurality of shift stages while the automatic transmission mechanism is in the neutral state. In the precharged state.   The stop / restart control means is configured for at least one shift stage regardless of the deceleration of the vehicle in the neutral state during the operation period in which the automatic stop condition is satisfied and the engine is automatically stopped while the vehicle is running. 2. The vehicle engine starting device according to claim 1, wherein the precharge state is set for the friction element to be engaged to establish the gear position.   The precharge state includes an initial precharge stage in which a predetermined fluid path connected to the friction element is filled with a working fluid, and the friction element is moved from the release position to the fastening direction via the initial precharge stage. And a late precharge stage that is in a state immediately before the engagement, and when the automatic transmission mechanism is in the neutral state by the stop / restart control means, the precharge state is in the late precharge stage. Item 3. The vehicle engine starter according to Item 1 or 2. It has a brake sensor that detects the operating state of the brake,
The stop / restart control means automatically restarts the engine when the brake is turned off at or below a predetermined vehicle speed before the vehicle stops after the automatic stop condition is satisfied and the engine is automatically stopped while the vehicle is running. The vehicle engine starting device according to any one of claims 1 to 3, wherein the vehicle engine starting device is started.

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