Vehicle control device

Abstract

To suppress generation of a shock in a driving system of a vehicle at starting of an engine.SOLUTION: A control device 100 executes throttle opening valve control for increasing an opening of a throttle valve before stopping of rotation of a crankshaft when operation of an internal combustion engine 10 is stopped. When the throttle opening valve control is executed, the control device 100 executes start prohibition processing for prohibiting start of the internal combustion engine 10 before elapse of a predetermined time after stopping of the internal combustion engine 10.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control device for a vehicle.

Background Art

[0002] For example, when stopping the operation of an internal combustion engine, the control device provided in the vehicle described in Patent Document 1 executes throttle opening valve control to increase the opening degree of a throttle valve before the rotation of a crankshaft stops.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when throttle opening valve control is performed at the time of engine stop, the amount of air in the cylinder increases. If engine starting is started with a large amount of air in the cylinder, the output torque of the internal combustion engine generated by the combustion of the air-fuel mixture becomes excessive, and there is a risk of shock occurring in the drive system of the vehicle.

Means for Solving the Problems

[0005] A control device for a vehicle that solves the above problems is a control device for a vehicle including an internal combustion engine and an electric motor that cranks the internal combustion engine when there is a starting request for the internal combustion engine. When stopping the operation of the internal combustion engine, this control device executes throttle opening valve control to increase the opening degree of a throttle valve provided in an intake passage before the rotation of the crankshaft of the internal combustion engine stops. Then, when this control device executes the throttle opening valve control, it executes a starting prohibition process for prohibiting starting of the internal combustion engine before a predetermined time elapses after the internal combustion engine stops.

[0006] The amount of air in the cylinder that increases by performing throttle valve opening control when the engine stops decreases with the passage of time after the engine stops. Therefore, in the same configuration, when throttle valve opening control is executed, a starting prohibition process is executed to prohibit starting the internal combustion engine before a predetermined time has elapsed since the internal combustion engine stopped. Accordingly, since starting the engine is suppressed when the amount of air in the cylinder is large, it is possible to suppress the generation of excessive torque from the internal combustion engine during engine starting. Therefore, it is possible to suppress the occurrence of a shock in the drive system of the vehicle during engine starting.

[0007] When the above starting prohibition process is executed, it is preferable to permit starting the internal combustion engine after the predetermined time has elapsed. Further, in the above control device, the starting prohibition process may be executed when the vehicle required torque necessary for running the vehicle can be satisfied by the output torque of the electric motor.

[0008] When it is impossible to satisfy the above vehicle required torque with the output torque of the electric motor, it is preferable to compensate for the insufficient torque with the output torque of the internal combustion engine. Here, when the above starting prohibition process is executed, torque compensation by the internal combustion engine becomes impossible. Therefore, in the same configuration, the starting prohibition process is executed when the vehicle required torque can be satisfied by the output torque of the electric motor. That is, the starting prohibition process is executed when torque compensation by the internal combustion engine is not required to secure the vehicle required torque. Accordingly, it is possible to suppress the occurrence of the inconvenience that torque compensation by the internal combustion engine becomes impossible due to the execution of the starting prohibition process.

[0009] Further, in the above control device, the vehicle includes a clutch mechanism that adjusts the torque transmission amount between the crankshaft of the internal combustion engine and the output shaft of the electric motor, and a transmission torque reduction process that reduces the torque transmission amount when the rate of increase in the engine rotational speed exceeds a predetermined value when starting the internal combustion engine may be executed.

[0010] When the above clutch mechanism is provided, by executing the above transmission torque reduction process, it is possible to suppress the occurrence of shock in the vehicle drive system at the time of engine startup. However, when the engine is started with a large amount of air in the cylinder, since the torque generated by the internal combustion engine is large, the rate of increase in the engine rotational speed becomes high. When the rate of increase in the engine rotational speed becomes high, there is a possibility that the reduction in the torque transmission amount due to the transmission torque reduction process may not be in time due to delays in arithmetic processing or response delays in the clutch mechanism. In this regard, in the same configuration, since the above startup prohibition process is executed, the generation of excessive torque from the internal combustion engine at the time of engine startup is suppressed, and the rate of increase in the engine rotational speed becomes gentle. When the rate of increase in the engine rotational speed becomes gentle, even if there are delays in arithmetic processing or response delays in the clutch mechanism, the reduction in the torque transmission amount due to the transmission torque reduction process can be in time. Therefore, by executing the transmission torque reduction process, it is possible to suppress the occurrence of shock in the vehicle drive system at the time of engine startup.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0012] Hereinafter, an embodiment of a control device for an internal combustion engine will be described with reference to FIGS. 1 to 4. <Configuration of the vehicle> As shown in FIG. 1, the vehicle 500 is a hybrid vehicle equipped with two prime movers such as an internal combustion engine 10 and an electric motor 30. The internal combustion engine 10 is provided with a fuel injection valve 12 that supplies fuel to the cylinders. Note that the fuel injection valve 12 of the present embodiment is a fuel injection valve for in-cylinder injection that directly injects fuel into the cylinder, but in addition, a fuel injection valve for port injection that injects fuel into the intake port of the internal combustion engine may also be used.

[0013] The internal combustion engine 10 is provided with an intake passage 13. An electric throttle valve 14 for adjusting the intake air amount is provided in the intake passage 13. The internal combustion engine 10 is provided with an exhaust passage 16. A catalyst 17 for purifying the exhaust is provided in the exhaust passage 16. In the combustion chamber of the internal combustion engine 10, an engine output is obtained by burning a mixture of the inhaled air and the fuel injected from the fuel injection valve 12.

[0014] An electric starter motor 85 that is driven by receiving power supply from the low-voltage battery 310 is provided on the crankshaft 18 that is the output shaft of the internal combustion engine 10. This starter motor 85 is an electric motor that cranks the internal combustion engine 10 at the start of the internal combustion engine 10.

[0015] Further, the crankshaft 18 is connected to the output shaft 41 of the electric motor 30 via a hydraulic clutch mechanism 20. This electric motor 30 is also an electric motor that cranks the internal combustion engine 10 at the start of the internal combustion engine 10. Whether to use the starter motor 85 or the electric motor 30 for cranking at the start of the engine depends on the starting conditions as described later.

[0016] The clutch mechanism 20 is a mechanism for adjusting the torque transmission amount between the crankshaft 18 and the output shaft 41 of the electric motor 30. A mechanical oil pump (hereinafter referred to as MOP) 50 that is driven by the electric motor 30 is provided on the output shaft 41 of the electric motor 30. In addition, an electric oil pump (hereinafter referred to as EOP) 80 is also provided in the vehicle 500.

[0017] When the clutch mechanism 20 is in the engaged state, the crankshaft 18 and the output shaft 41 of the electric motor 30 are connected, while when in the released state, the connection between the crankshaft 18 and the output shaft 41 of the electric motor 30 is released.

[0018] The electric motor 30 exchanges electric power with the high-voltage battery 300 for driving via a PCU (Power Control Unit) 200. The PCU 200 includes a boost converter 210, an inverter 220, a DC-DC converter 230, etc. The boost converter 210 boosts and outputs the DC voltage input from the high-voltage battery 300. The inverter 220 converts the DC voltage boosted by the boost converter 210 into an AC voltage and outputs it to the electric motor 30. The DC-DC converter 230 steps down the DC voltage of the high-voltage battery 300 to a voltage for auxiliary machine drive.

[0019] The vehicle 500 is provided with the above-mentioned low-voltage battery 310 that stores the electric power stepped down by the DC-DC converter 230. Also, the PCU 200 detects the state of charge SOC (SOC = remaining capacity of the battery [Ah] / fully charged capacity of the battery [Ah] × 100%) of the high-voltage battery 300 and the state of charge SOC of the low-voltage battery 310.

[0020] The output shaft 41 of the electric motor 30 is connected to the input shaft of a torque converter 42 having a lock-up clutch 45. The output shaft of the torque converter 42 is connected to the input shaft of an automatic transmission 48. The output shaft of the automatic transmission 48 is connected to a differential gear 60. The drive wheels 65 of the vehicle 500 are connected to the output shaft of the differential gear 60.

[0021] The vehicle 500 is provided with a hydraulic pressure adjustment mechanism 90 that uses the MOP 50 and the EOP 80 as hydraulic pressure sources. Connected to the hydraulic pressure adjustment mechanism 90 as destinations for the supply of hydraulic pressure are the automatic transmission 48, the lock-up clutch 45, the clutch mechanism 20, and the like. By controlling the hydraulic pressure supplied from the hydraulic pressure adjustment mechanism 90, operations such as the shifting operation by the automatic transmission 48, the operation of the lock-up clutch 45, and the operation of the clutch mechanism 20 are controlled.

[0022] Various controls such as the control of the internal combustion engine 10, the control of the electric motor 30, and the control of the hydraulic pressure adjustment mechanism 90 are executed by a control device 100 mounted on the vehicle 500. The control device 100 includes a central processing unit (hereinafter referred to as the CPU) 110 and a memory 120 in which control programs and data are stored. By the CPU 110 executing the programs stored in the memory 120, various controls are executed. Although not shown in the figure, the control device 100 is composed of a plurality of control units such as a control unit for the internal combustion engine and a control unit for the PCU.

[0023] The control device 100 is connected with a crank angle sensor 70 for detecting the rotation angle of the crankshaft 18 and a rotation speed sensor 71 for detecting the motor rotation speed Nm which is the rotation speed of the electric motor 30. The control device 100 is connected with an air flow meter 72 for detecting the intake air amount GA of the internal combustion engine 10 and a water temperature sensor 73 for detecting the cooling water temperature THW which is the temperature of the cooling water of the internal combustion engine 10. The control device 100 is connected with a throttle sensor 74 for detecting the throttle opening TA which is the opening degree of the throttle valve 14 and an accelerator position sensor 75 for detecting the accelerator operation amount ACCP which is the operation amount of the accelerator pedal. The control device 100 is connected with a vehicle speed sensor 76 for detecting the vehicle speed SP of the vehicle 500. Further, the control device 100 is also connected with a power switch 77 for the driver of the vehicle 500 to start and stop the system of the vehicle 500. The control device 100 grasps the start request of the system of the vehicle 500 based on the input signal from the power switch 77. Note that the control device 100 calculates the engine rotation speed Ne based on the output signal Scr of the crank angle sensor 70. Also, the control device 100 calculates the engine load factor KL based on the engine rotation speed Ne and the intake air amount GA.

[0024] The above-mentioned PCU200 is connected to the control device 100, and the control device 100 controls the electric motor 30 through the control of the PCU200. <Regarding the processing performed by the control device> The control device 100 calculates the vehicle required torque which is the required value of the driving force of the vehicle 500 from the accelerator operation amount ACCP and the vehicle speed SP. Further, the control device 100 calculates the engine required torque which is the required value of the output torque of the internal combustion engine 10 and the motor required torque which is the required value of the power running torque of the electric motor 30 respectively based on the vehicle required torque, the charge rate SOC, etc. Then, the control device 100 performs the output control of the internal combustion engine 10 according to the engine required torque and performs the torque control of the electric motor 30 according to the motor required torque, thereby performing the torque control required for the running of the vehicle 500.

[0025] When the control device 100 uses the internal combustion engine 10 as the prime mover of the vehicle 500, it engages the clutch mechanism 20 to transmit the output torque of the internal combustion engine 10 to the automatic transmission 48. In some cases, the motor 30 is also made to perform a power running operation, so that not only the output torque of the internal combustion engine 10 but also the power running torque of the motor 30 is transmitted to the automatic transmission 48. On the other hand, when the control device 100 uses only the motor 30 as the prime mover of the vehicle 500, it disengages the clutch mechanism 20 to cut off the torque transmission between the internal combustion engine 10 and the automatic transmission 48. Then, by making the motor 30 perform a power running operation, the power running torque of the motor 30 is transmitted to the automatic transmission 48. In this way, when only the motor 30 is used as the prime mover of the vehicle 500, the operation of the internal combustion engine 10 is stopped. Thus, during the operation of the vehicle 500, intermittent operation and intermittent stop in which the operation and the stop of the internal combustion engine 10 are repeated are performed.

[0026] When the control device 100 is performing coasting (coasting) when the accelerator is off (the state where the accelerator operation amount ACCP is "0") or braking by depressing the brake pedal, it performs regenerative control. This regenerative control is control that uses the kinetic energy transmitted from the drive wheels 65 to rotate the motor 30 so that the motor 30 functions as a generator, and stores the generated electric power in the high-voltage battery 300. When performing regenerative control, the control device 100 engages the lock-up clutch 45 and basically disengages the clutch mechanism 20 to reduce the rotational resistance.

[0027] The control device 100 controls the torque capacity of the clutch mechanism 20 so as to obtain the required torque transmission amount. The control of the torque capacity is performed by controlling the hydraulic pressure supplied to the clutch mechanism 20. The control device 100 calculates a hydraulic pressure command value Pt based on the required torque capacity. Then, the control device 100 controls the hydraulic pressure adjustment mechanism 90 so that the hydraulic pressure corresponding to the hydraulic pressure command value Pt is supplied to the clutch mechanism 20.

[0028] Further, when there is a stop request for the internal combustion engine 10, the control device 100 reduces the hydraulic command value Pt to release the clutch mechanism 20. Then, when the predetermined stop condition is satisfied, fuel cut is performed to stop the fuel supply to the fuel injection valve 12 and stop the operation of the internal combustion engine 10.

[0029] Further, after performing fuel cut in accordance with a stop request, if there is a start request for the internal combustion engine 10 before the rotation of the crankshaft 18 stops, the control device 100 performs self-restoration. More specifically, when the engine rotational speed Ne at the time the start request occurs is equal to or higher than the predetermined recoverable speed Ne2 and engine start is possible without assist torque from the electric motor 30 or the like, fuel injection and ignition are started to start the engine.

[0030] On the other hand, when the engine rotational speed Ne at the time the start request occurs is lower than the recoverable speed Ne2 and self-restoration is impossible, fuel injection and ignition are started while using the assist torque of the electric motor 30 to start the engine.

[0031] Further, when the rate of increase in the engine rotational speed exceeds a predetermined value when starting the internal combustion engine 10, the control device 100 executes transmission torque reduction processing to reduce the torque transmission amount of the clutch mechanism 20. When reducing the torque transmission amount, processing such as completely releasing the clutch mechanism 20 or increasing the slip ratio of the clutch mechanism 20 is executed.

[0032] Further, after the control device 100 performs fuel cut in response to a stop request, when the engine speed Ne becomes equal to or lower than a threshold value Ne1 set to a value lower than the above-returnable speed Ne2, the control device 100 executes throttle valve opening control to increase the opening degree of the throttle valve 14. This throttle valve opening control is control to set the opening degree of the throttle valve 14 to a predetermined opening degree TA1 for a certain period. The opening degree TA1 is a value larger than the idle opening degree set when the internal combustion engine 10 is in the idle operation state. When the throttle valve opening control is thus performed before the rotation of the crankshaft 18 stops, the amount of air in the cylinder increases. When the amount of air in the cylinder increases, the piston reciprocating in the cylinder of the internal combustion engine 10 is likely to stop at a predetermined position when the rotation of the crankshaft 18 stops.

[0033] In a state where the amount of air in the cylinder has increased due to the execution of such throttle valve opening control, the in-cylinder pressure is high. Therefore, when starting the engine, the torque required to rotate the crankshaft 18 beyond top dead center of compression increases. Therefore, when starting the engine in a state where the amount of air in the cylinder is large, the control device 100 increases the output torque of the electric motor 30 in order to increase the assist torque applied from the electric motor 30 to the crankshaft 18. Further, in order to increase the torque transmission amount of the clutch mechanism 20 in accordance with such an increase in output torque, the control device 100 executes a process of increasing the torque capacity.

[0034] Further, when the control device 100 needs assist torque when starting the internal combustion engine 10 in accordance with a start request of the internal combustion engine 10, the control device 100 selects one of a plurality of engine start modes described later and starts cranking the internal combustion engine 10. Then, fuel injection and ignition are started to start the engine.

[0035] Note that the start requests for the internal combustion engine 10 include a first start request and an intermittent start request. The first start request is the first start request after the power switch 77 is turned on. At the time when the first start request occurs, the electric motor 30 is not yet rotating.

[0036] The intermittent start request is a start request by the above-described intermittent operation. At the time when the intermittent start request occurs, the electric motor 30 is in a rotating state. Examples of when an intermittent start request occurs include, for example, when a vehicle drive torque that cannot be compensated only by the torque of the electric motor 30 is required while the operation of the internal combustion engine 10 is stopped. Further, examples of when an intermittent start request occurs include, for example, when a charging request for the high-voltage battery 300 occurs, when a charging request for the low-voltage battery 310 occurs, and the like.

[0037] <Regarding the engine start mode> FIG. 2 shows a first mode, a second mode, a third mode, and a fourth mode, which are a plurality of engine start modes implemented by the control device 100.

[0038] The first mode and the second mode are engine start modes selected at the first start implemented due to the occurrence of the first start request. The first mode is a mode selected when the coolant water temperature THW is equal to or higher than a predetermined temperature. In the first mode, when the first start request occurs, the clutch mechanism 20 is engaged. Then, when the engagement of the clutch mechanism 20 is completed, the electric motor 30 is driven, so that both the engine rotation speed Ne and the motor rotation speed Nm increase, and cranking of the internal combustion engine 10 is performed. Then, when the engine rotation speed Ne reaches a predetermined rotation speed, fuel injection and ignition are started, and the internal combustion engine 10 starts. In this first mode, an engagement shock of the clutch mechanism 20 is unlikely to occur. Further, since fuel injection and ignition are started after the engine rotation speed Ne has increased to a certain extent, the mixing of the air-fuel mixture progresses easily, and thereby the exhaust emission is improved.

[0039] The second mode is a mode selected when the cooling water temperature THW is less than the above-mentioned preset temperature. In the second mode, when a first start request occurs, the clutch mechanism 20 is released. If the clutch mechanism 20 is in the released state when the first start request occurs, the released state is maintained. Then, when the starter motor 85 is driven, the cranking of the internal combustion engine 10 is started. When the crank angle of the crankshaft 18 is determined, fuel injection and ignition are started, and the internal combustion engine 10 starts. In this second mode, cranking is performed using the starter motor 85. This is because in a low-temperature environment, the torque of the electric motor 30 decreases, making it difficult to increase the engine rotation speed Ne to the above-mentioned preset rotation speed. Thus, the second mode is a mode for low-temperature starting.

[0040] The first mode described above is a control in which fuel injection and ignition are started in a state where the engine rotation speed is higher compared to the second mode. The first mode is high-speed start control, and the second mode is low-speed start control.

[0041] The third mode and the fourth mode are engine start modes selected during intermittent starting implemented due to an intermittent start request occurring. The third mode is a mode selected during an intermittent start request without urgency, for example, when a charging request for the high-voltage battery 300 occurs or when a charging request for the low-voltage battery 310 occurs. In the third mode, when an intermittent start request occurs, the clutch mechanism 20 in the released state is put into a slip state. When the clutch mechanism 20 is in the slip state, torque is transmitted from the electric motor 30 to the internal combustion engine 10, and cranking of the internal combustion engine 10 is performed, so that the engine rotation speed Ne increases. When the engine rotation speed Ne reaches the motor rotation speed Nm and their rotation speeds are synchronized, the state of the clutch mechanism 20 is changed from the slip state to the engaged state, and fuel injection and ignition are started, and the internal combustion engine 10 starts. In this third mode, synchronization of the clutch mechanism 20 is easy and shock is less likely to occur during starting.

[0042] The fourth mode is a mode selected when an urgent intermittent start request occurs, for example, when the vehicle drive torque cannot be compensated only by the torque of the electric motor 30 when the operation of the internal combustion engine 10 has stopped. In the fourth mode, when an intermittent start request occurs, the clutch mechanism 20 that was in the released state is put into a slip state. When the clutch mechanism 20 is in the slip state, torque transmission from the electric motor 30 to the internal combustion engine 10 is performed and cranking of the internal combustion engine 10 is started. Then, when the crank angle of the crankshaft 18 is determined, fuel injection and ignition are started, and the internal combustion engine 10 is started. Although this fourth mode is difficult to synchronize the clutch mechanism 20 and is likely to cause a shock at startup, it has the characteristic that the time from when the start request occurs until the actual engine start is completed is short, that is, the so-called starting response is good.

[0043] The above third mode is a control in which fuel injection and ignition are started in a state where the engine rotation speed is higher compared to the above fourth mode. The third mode is high-speed start control, and the fourth mode is low-speed start control.

[0044] High-speed start control has the characteristic that, for example, the shock at engine start is small compared to low-speed start control. Also, low-speed start control has the characteristic that, for example, the time from when the start request occurs until the actual engine start is completed is short, that is, the so-called starting response is good, compared to high-speed start control.

[0045] <Regarding the start prohibition process> By the way, when the throttle valve opening control described above is performed, the amount of air in the cylinder increases. If engine start is started in a state where the amount of air in the cylinder is large, the output torque of the internal combustion engine generated by the combustion of the air-fuel mixture becomes excessive, and there is a risk of generating a shock in the drive system of the vehicle 500.

[0046] Further, as described above, when starting the engine with a large amount of air in the cylinder, the control device 100 increases the assist torque applied from the electric motor 30 to the crankshaft 18. When the assist torque is increased in this way, the engine rotation speed rapidly increases, which may also cause a shock to the drive system of the vehicle 500.

[0047] Incidentally, the occurrence of a drive system shock caused by such a rapid increase in the engine rotation speed is basically suppressed by the above-described transmission torque reduction process. However, when the engine start is initiated with a large amount of air in the cylinder, the rate of increase in the engine rotation speed becomes higher than normal. When the rate of increase in the engine rotation speed becomes high in this way, there is also a possibility that the reduction in the torque transmission amount by the transmission torque reduction process may not be in time due to a delay in arithmetic processing or a response delay of the clutch mechanism 20.

[0048] Therefore, when the control device 100 executes the throttle valve opening control, it executes a start prohibition process for prohibiting the start of the internal combustion engine 10 before the elapse of a predetermined time Tw after the rotation of the crankshaft 18 stops. In the present embodiment, the start prohibition process is executed when starting the engine in the fourth mode described above. However, the same start prohibition process may be executed when starting the engine in other modes.

[0049] FIG. 3 shows the processing procedure of the start prohibition process executed by the control device 100. The control device 100 repeatedly executes this process at every predetermined calculation cycle. Note that the control device 100 ends the execution of this process when, for example, the engine start is completed. Also, hereinafter, step numbers are represented by numbers with "S" attached at the beginning.

[0050] When starting the process shown in FIG. 3, the control device 100 determines whether there is a start request (S100). And when it is determined that there is a start request (S100: YES), the control device 100 then determines whether the vehicle required torque can be satisfied by the motor output torque (S110). In the process of S110, when the value obtained by subtracting the assist torque required for cranking from the maximum output torque of the electric motor 30 is greater than or equal to the vehicle required torque, the control device 100 makes an affirmative determination.

[0051] And when an affirmative determination is made in the process of S110, next, the control device 100 determines whether self-restoration is possible (S120). In the process of S120, the control device 100 determines that self-restoration is possible when the current engine rotational speed Ne is greater than or equal to the above-mentioned restoration possible speed Ne2. On the other hand, the control device 100 determines that self-restoration is impossible when the current engine rotational speed Ne is less than the above-mentioned restoration possible speed Ne2.

[0052] And when it is determined in the process of S120 that self-restoration is impossible (S120: NO), the control device 100 determines whether the internal combustion engine 10 has completely stopped (S130). This determination of whether it has completely stopped is implemented, for example, as follows. That is, the control device 100 measures the elapsed time TL from the time when the rotation angle change of the crankshaft 18 by the crank angle sensor 70 is no longer detected. And in the process of S130, the control device 100 determines that the internal combustion engine 10 has completely stopped when the current elapsed time TL is greater than or equal to the predetermined time Tw. On the other hand, the control device 100 determines that the internal combustion engine 10 has not completely stopped when the current elapsed time TL is less than the predetermined time Tw. As the predetermined time Tw, the time required for the amount of air in the cylinder increased by the implementation of the throttle valve control to become less than or equal to the predetermined air amount SA1 after the engine stops is preset. Also, as the predetermined air amount SA1, the air amount that can make the output torque of the internal combustion engine 10 to an output torque level that can suppress the occurrence of shock in the drive system of the vehicle 500 is preset.

[0053] And, in the process of S130, when it is determined that the internal combustion engine 10 has not completely stopped (S130: NO), the control device 100 executes a starting prohibition process for prohibiting the starting of the internal combustion engine 10 (S140). When this starting prohibition process is executed, even if there is a starting request, the starting of the internal combustion engine 10 is prohibited until the elapsed time TL becomes equal to or longer than the preset time Tw. Then, when the elapsed time TL becomes equal to or longer than the preset time Tw, the starting of the internal combustion engine 10 is permitted and the starting is started. That is, the engine starting by the fourth mode is started. Note that, even during the execution of the starting prohibition process, when an emergency starting request occurs, the control device 100 interrupts the prohibition of starting and immediately starts the engine starting.

[0054] When the control device 100 makes a negative determination in each process of S100 and S110, or makes an affirmative determination in each process of S120 and S130, the control device 100 permits the starting of the internal combustion engine 10 (S150).

[0055] Then, when the process of S140 or the process of S150 is executed, the control device 100 ends the execution of this process in the current operation cycle. <Function> The function of the present embodiment will be described.

[0056] FIG. 4 shows the transition of each value when the intermittent starting of the internal combustion engine 10 is performed during the running of the vehicle 500. FIG. 4(A) shows the presence or absence of a starting request, FIG. 4(B) shows the throttle opening TA, FIG. 4(C) shows the execution state of fuel cut, FIG. 4(D) shows the motor rotation speed Nm and the engine rotation speed Ne, FIG. 4(E) shows the hydraulic pressure command value Pt of the clutch mechanism 20, and FIG. 4(F) shows the amount of air in the cylinder. Also, before the time t1, a stop request has been made and the clutch mechanism 20 is in the released state. Also, fuel cut is being executed.

[0057] Due to the execution of fuel cut, the engine rotation speed Ne decreases. Then, when the engine rotation speed Ne falls below the recoverable speed Ne2, self-recovery becomes impossible. Thereafter, when the engine rotational speed Ne becomes equal to or lower than the threshold value Ne1 at time t2, throttle valve opening control is carried out. This throttle valve opening control is carried out after the internal combustion engine 10 has reached a state where self - recovery is impossible and before the internal combustion engine 10 comes to a complete stop. When the throttle valve opening control is carried out, the throttle valve opening TA is temporarily increased. Due to this increase in the throttle valve opening TA, the amount of air in the cylinder increases. Then, when the throttle valve opening control ends at time t4, the throttle valve opening TA is decreased. Here, since the increased air in the cylinder leaks from the gaps in the cylinder (for example, the gap between the piston ring and the cylinder wall surface), the amount of air in the cylinder gradually decreases after time t4.

[0058] A start request occurs at time t3 after the throttle valve opening control has been carried out. At time t3, the internal combustion engine 10 has already reached a state where self - recovery is impossible and has not come to a complete stop. Therefore, engine starting is prohibited until it is determined that the engine has come to a complete stop. That is, engine starting is prohibited until the change in the rotation angle of the crankshaft 18 is no longer detected at time t5 and it is determined that the above - mentioned predetermined time Tw has elapsed at time t6. When it is determined that the predetermined time Tw has elapsed (time t6), engine starting is permitted, and engine starting based on the start request is started.

[0059] More specifically, engine starting according to the above - described fourth mode is started. When the starting according to the fourth mode is started, the hydraulic pressure command value Pt of the clutch mechanism 20 is increased, so that the clutch mechanism 20 that was in the released state enters the slip state. When the clutch mechanism 20 enters the slip state, torque transmission from the electric motor 30 to the internal combustion engine 10 is carried out and cranking of the internal combustion engine 10 is started (time t7). Then, when the crank angle of the crankshaft 18 is determined, fuel injection and ignition are started, and the internal combustion engine 10 starts. When the air - fuel mixture burns and the internal combustion engine 10 starts, the engine rotational speed Ne increases.

[0060] When the rate of increase in the engine speed Ne exceeds a predetermined value at time t8, a transmission torque reduction process is executed from time t8 to time t9, causing the hydraulic pressure command value Pt of the clutch mechanism 20 to temporarily decrease.

[0061] Then, when the transmission torque reduction process ends, thereafter, the hydraulic pressure command value Pt gradually increases. And when the engine speed Ne and the motor speed Nm are synchronized at time t10, the hydraulic pressure command value Pt is increased to the hydraulic pressure required to fully engage the clutch mechanism 20. The start request is turned off, for example, when the clutch mechanism 20 is fully engaged.

[0062] <Effect> The effects of this embodiment will be described. (1) The amount of air in the cylinder that increases by performing throttle valve opening control when the engine stops decreases with the passage of time after the engine stops. Therefore, in this embodiment, when throttle valve opening control is executed, a start prohibition process is executed to prohibit starting the internal combustion engine 10 before a predetermined time Tw elapses after the internal combustion engine 10 stops. Accordingly, since starting the engine in a state where the amount of air in the cylinder is large is suppressed, it is possible to suppress the generation of excessive torque from the internal combustion engine 10 at the time of engine start. Therefore, it is possible to suppress the occurrence of a shock in the drive system of the vehicle 500 at the time of engine start.

[0063] (2) When it is impossible to satisfy the vehicle required torque with the output torque of the electric motor 30, it is preferable to compensate for the insufficient torque with the output torque of the internal combustion engine 10. Here, when the above-described start prohibition process is executed, torque compensation by the internal combustion engine 10 becomes impossible. Therefore, in this embodiment, the start prohibition process is executed when it is possible to satisfy the vehicle required torque with the output torque of the electric motor 30. That is, the start prohibition process is executed when torque compensation by the internal combustion engine 10 is not required to secure the vehicle required torque. Accordingly, it is possible to suppress the occurrence of the inconvenience that torque compensation by the internal combustion engine 10 becomes impossible due to the execution of the start prohibition process.

[0064] (3) By executing the above-described transmission torque reduction process, it is possible to suppress the occurrence of shock in the drive system of the vehicle 500 at the time of engine start. However, when the engine is started with a large amount of air in the cylinder, since the torque generated by the internal combustion engine 10 is large, the rate of increase in the engine rotational speed becomes high. When the rate of increase in the engine rotational speed becomes high, there is a possibility that the reduction in the torque transmission amount due to the transmission torque reduction process may not be in time due to a delay in arithmetic processing or a response delay of the clutch mechanism 20. In this regard, in the present embodiment, since the above-described start prohibition process is executed, excessive torque is suppressed from being generated from the internal combustion engine 10 at the time of engine start, and the rate of increase in the engine rotational speed becomes gentle. When the rate of increase in the engine rotational speed becomes gentle, even if there is a delay in arithmetic processing or a response delay of the clutch mechanism 20, the reduction in the torque transmission amount due to the transmission torque reduction process can be in time. Therefore, by executing the transmission torque reduction process, it becomes possible to suppress the occurrence of shock in the drive system of the vehicle 500 at the time of engine start.

[0065] <Modification example> Note that the above embodiment can be implemented with the following modifications. The above embodiment and the following modification examples can be implemented in combination with each other within a range where there is no technical contradiction.

[0066] · The process of S110 shown in FIG. 3 may be omitted. Even in this case, the effects other than the above (2) can be obtained. · When the in-cylinder pressure in the cylinder is sufficiently high in a state where the rotation of the crankshaft 18 has completely stopped due to engine stop, there may be a case where the engine can be started by performing fuel injection and ignition without assist torque from the electric motor. Therefore, in this case, self-regeneration may be performed, and the above-described start prohibition process may not be performed when performing the self-regeneration.

[0067] · In an internal combustion engine that does not perform the above-described self-return, the above-described starting prohibition process may be executed. In this case, for example, in the process of S120 shown in FIG. 3, it is determined whether or not throttle valve opening control has been executed. And when it is determined that the throttle valve opening control has been executed, the processes after S130 are executed. On the other hand, when it is determined that the throttle valve opening control has not been executed, the process of S150 may be executed.

[0068] · The hybrid system of the vehicle 500 is not limited to that shown in FIG. 1, and other hybrid systems may also be used. For example, a so-called series-parallel hybrid system that does not have the clutch mechanism 20 and in which the crankshaft 18 and the electric motor 30 are connected via a power split mechanism may be used. Even in such a series-parallel hybrid system, when the above-described throttle valve opening control is executed, engine starting may be performed with a large amount of air in the cylinder, and there is a possibility that a shock may occur in the drive system of the vehicle 500. Therefore, even in a vehicle equipped with such a series-parallel hybrid system, by executing the above-described starting prohibition process, the effect described in the above (1) can be obtained.

[0069] · The vehicle 500 is not limited to a vehicle equipped with an internal combustion engine and an electric motor as prime movers. For example, a vehicle that has an internal combustion engine but does not have an electric motor may be used. Even in such a vehicle, for example, when idle stop control is executed, the intermittent operation of the internal combustion engine 10 is performed, and cranking is performed with the output torque of the starter motor as an assist torque at engine starting. And when the above-described throttle valve opening control is executed, engine starting may be performed with a large amount of air in the cylinder, and there is a possibility that a shock may occur in the drive system of the vehicle. Therefore, even in a vehicle equipped with only an internal combustion engine as a prime mover, by executing the above-described starting prohibition process, the effect described in the above (1) can be obtained.

[0070] · The control device 100 includes a CPU 110 and a memory 120, and is not limited to executing software processing. For example, it may include a dedicated hardware circuit (such as an ASIC, etc.) that processes at least a part of the software processing executed in the above embodiment. That is, the control device 100 may have any of the following configurations (a) to (c). (a) It includes a processing device that executes all of the above processing according to a program, and a program storage device such as a memory that stores the program. (b) It includes a processing device and a program storage device that execute a part of the above processing according to a program, and a dedicated hardware circuit that executes the remaining processing. (c) It includes a dedicated hardware circuit that executes all of the above processing. Here, there may be a plurality of software processing circuits and dedicated hardware circuits including a processing device and a program storage device. That is, the above processing may be executed by a processing circuit including at least one of one or more software processing circuits and one or more dedicated hardware circuits.

Explanation of Signs

[0071] 10…Internal combustion engine 12…Fuel injection valve 13…Intake passage 14…Throttle valve 16…Exhaust passage 17…Catalyst 18…Crankshaft 20…Clutch mechanism 30…Electric motor 42…Torque converter 45…Lock-up clutch 48…Automatic transmission 50…Mechanical oil pump 60…Differential gear 65…Drive wheel 80…Electric oil pump 85…Starter motor 90…Hydraulic adjustment mechanism 100…Control device 110…Central processing unit 120…Memory 200…PCU 500… vehicle

Claims

1. A control device for a vehicle, comprising: an internal combustion engine; and an electric motor configured to crank the internal combustion engine when a start request for the internal combustion engine is issued, when the internal combustion engine is stopped, throttle valve opening control is executed to increase the opening degree of a throttle valve provided in an intake passage before rotation of a crankshaft of the internal combustion engine stops, and when the throttle valve opening control is executed and it is possible to satisfy a vehicle required torque necessary for running of the vehicle with an output torque of the electric motor, a start prohibition process is executed to prohibit starting of the internal combustion engine before a predetermined time elapses after the internal combustion engine stops A control device for a vehicle.

2. A control device for a vehicle, comprising: an internal combustion engine; an electric motor configured to crank the internal combustion engine when a start request for the internal combustion engine is issued; and a clutch mechanism configured to adjust a torque transmission amount between a crankshaft of the internal combustion engine and an output shaft of the electric motor, when a rising rate of an engine rotational speed exceeds a predetermined value during starting of the internal combustion engine, a transmission torque reduction process is executed to reduce the torque transmission amount, when the internal combustion engine is stopped, throttle valve opening control is executed to increase the opening degree of a throttle valve provided in an intake passage before rotation of a crankshaft of the internal combustion engine stops, and when the throttle valve opening control is executed, a start prohibition process is executed to prohibit starting of the internal combustion engine before a predetermined time elapses after the internal combustion engine stops A control device for a vehicle.

3. When the start prohibition process is executed, starting of the internal combustion engine is permitted after the predetermined time elapses The control device for a vehicle according to claim 1 or 2.

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