Vehicle control device

Abstract

To suppress preignition.SOLUTION: A vehicle includes an engine and a fluid coupling, the engine using hydrogen as fuel, the fluid coupling having a lock-up clutch, the fluid coupling serving for transmitting the driving force of the engine via the lock-up clutch to driving wheels. A control device for the vehicle transmits the driving force of the engine via the fluid coupling to the driving wheels, and executes reduction processing when the lock-up clutch is not put in a completely engaging state, if executing conditions as conditions that preignition can occur in a combustion chamber of the engine are satisfied. In the reduction processing, the slip ratio of the lock-up clutch is further reduced than when the executing conditions are not satisfied.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] The engine system of Patent Document 1 includes an engine and a control device. The engine uses hydrogen as fuel. The control device performs control to lower the temperature of the combustion chamber when pre-ignition occurs in the combustion chamber of the engine. Specifically, the control device performs control to lower the temperature of the combustion chamber by reducing the injection amount from the engine's fuel injection valve or by increasing the amount of exhaust gas recirculated from the engine's exhaust passage to the intake passage. Pre-ignition is a phenomenon in which the mixture of fuel and intake air in the combustion chamber ignites before the mixture is ignited by an ignition device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-130473 Summary of the Invention [Problem to be solved by the invention]

[0004] In an engine such as that described in Patent Document 1, when the rotation speed of the crankshaft increases, the period during which fuel and intake air mix in the combustion chamber becomes shorter. And when the period during which fuel and intake air mix becomes shorter, pre-ignition becomes more likely to occur in the combustion chamber. Therefore, there is a risk that pre-ignition cannot be fully suppressed by simply performing control to lower the temperature of the combustion chamber as described in Patent Document 1. Therefore, there is a demand for technology that can suppress pre-ignition, separate from control to lower the temperature of the combustion chamber as described in Patent Document 1. [Means for solving the problem]

[0005] A vehicle control device for solving the above problem is a control device that controls a vehicle equipped with a hydrogen-fueled engine and a fluid coupling having a lock-up clutch that transmits the driving force of the engine to the drive wheels via the lock-up clutch, and when the driving force of the engine is transmitted to the drive wheels via the fluid coupling and the lock-up clutch is not fully engaged, if an execution condition is met that is a condition under which pre-ignition may occur in the combustion chamber of the engine, then a reduction process is executed to reduce the slip ratio of the lock-up clutch compared to when the execution condition is not met.

[0006] In the above configuration, when the driving force of the engine is transmitted to the drive wheels via the fluid coupling and the lock-up clutch is not fully engaged, the rotational speed of the input shaft of the fluid coupling is higher than the rotational speed of the output shaft of the fluid coupling. According to the above configuration, when the execution condition is met, the slip ratio of the lock-up clutch decreases, thereby reducing the difference in rotational speed between the input shaft and the output shaft of the fluid coupling. This reduces the rotational speed of the engine crankshaft. As a result, the period during which fuel and intake air are mixed is extended, thereby suppressing pre-ignition. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic configuration diagram of a vehicle. [Figure 2] FIG. 1 is a schematic configuration diagram of an engine. [Figure 3] 10 is a flowchart showing slip ratio change control. DETAILED DESCRIPTION OF THE INVENTION

[0008] <Vehicle Overview> An embodiment of the present invention will now be described with reference to Figures 1 to 3. First, a general configuration of a vehicle 100 will be described.

[0009] As shown in Fig. 1, the vehicle 100 includes an engine 10 and a motor generator 30. The engine 10 functions as a drive source for the vehicle 100. The engine 10 uses hydrogen as fuel. The motor generator 30 functions as a drive source for the vehicle 100. Therefore, the vehicle 100 is a so-called hybrid vehicle.

[0010] 2, the engine 10 includes a plurality of cylinders 11, an intake passage 12, and an exhaust passage 13. The engine 10 also includes a plurality of pistons 16, a plurality of connecting rods 17, a crankshaft 18, a plurality of intake valves 21, and a plurality of exhaust valves 22.

[0011] Each cylinder 11 houses a piston 16. The cylinder 11, together with the piston 16, defines a combustion chamber 10A. The combustion chamber 10A is a space for burning a mixture of fuel and intake air. In this embodiment, the engine 10 has four cylinders 11. Note that FIG. 2 shows only one representative cylinder 11.

[0012] The piston 16 is connected to a crankshaft 18 via a connecting rod 17. The piston 16 reciprocates within the cylinder 11 as a mixture of fuel and intake air burns in the cylinder 11. The reciprocating motion of the piston 16 causes the crankshaft 18 to rotate.

[0013] The intake passage 12 is connected to the cylinders 11. The intake passage 12 supplies intake air to each cylinder 11 from outside the engine 10. The exhaust passage 13 is connected to the cylinders 11. The exhaust passage 13 discharges exhaust gas from each cylinder 11 to outside the engine 10. The intake valve 21 is located at the downstream end of the intake passage 12. The intake valve 21 opens and closes the downstream end of the intake passage 12 by a driving force from a valve mechanism (not shown). The exhaust valve 22 is located at the upstream end of the exhaust passage 13. The exhaust valve 22 opens and closes the upstream end of the exhaust passage 13 by a driving force from a valve mechanism (not shown).

[0014] The engine 10 includes a throttle valve 23, multiple ignition devices 24, a catalyst 25, multiple port injection valves 26, multiple in-cylinder injection valves 27, and multiple water injection valves 29. The throttle valve 23 is located midway through the intake passage 12. The throttle valve 23 adjusts the amount of intake air flowing through the intake passage 12.

[0015] The tip of the port injection valve 26 is located in the intake passage 12 near the cylinder 11. The port injection valve 26 injects hydrogen as fuel into the intake passage 12, thereby supplying fuel into the cylinder 11 via the intake passage 12. The engine 10 is equipped with four port injection valves 26 corresponding to the four cylinders 11.

[0016] The tip of the in-cylinder injection valve 27 is located inside the cylinder 11. The in-cylinder injection valve 27 supplies fuel to the cylinder 11 by injecting hydrogen as fuel into the cylinder 11. The engine 10 is equipped with four in-cylinder injection valves 27 corresponding to the four cylinders 11.

[0017] The tip of the ignition device 24 is located inside the cylinder 11. The ignition device 24 ignites a mixture of fuel and intake air by spark discharge. The engine 10 is equipped with four ignition devices 24 corresponding to the four cylinders 11. The catalyst 25 is located midway in the exhaust passage 13. The catalyst 25 purifies the exhaust gas flowing through the exhaust passage 13.

[0018] The tip of the water injector 29 is located in the intake passage 12 near the cylinder 11. Water is supplied to the water injector 29 from a water tank (not shown). The water injector 29 injects water into the intake passage 12. When the injected water evaporates, the intake passage 12 is cooled, thereby cooling the intake air supplied from the intake passage 12 to the cylinder 11. The engine 10 is equipped with four water injectors 29 corresponding to the four cylinders 11.

[0019] The engine 10 is equipped with a water jacket 15. The water jacket 15 is a space for circulating cooling water. The water jacket 15 surrounds the cylinders 11. Cooling water flows through the water jacket 15. The cylinders 11 are cooled by heat exchange with the cooling water in the water jacket 15.

[0020] As shown in FIG. 1, the vehicle 100 includes a power transmission device 40, a differential 51, and a plurality of drive wheels 52. The power transmission device 40 includes a case 41, a damper 42, a connecting shaft 43, a clutch 44, a torque converter 45, and an automatic transmission 46. The case 41 accommodates the damper 42, the connecting shaft 43, the clutch 44, the torque converter 45, and the automatic transmission 46 in addition to the motor generator 30 described above. The motor generator 30 includes a rotor 31 and a stator 32. The stator 32 is fixed to the case 41. The rotor 31 is rotatable relative to the stator 32.

[0021] A first end of the connecting shaft 43 is connected to the crankshaft 18 of the engine 10 via a damper 42. The damper 42 transmits the driving force from the crankshaft 18 to the connecting shaft 43 while suppressing fluctuations in the torque of the crankshaft 18. A second end of the connecting shaft 43 is connected to the rotor 31 of the motor generator 30 via a clutch 44. The connection state of the clutch 44 is switched between an engaged state and a released state depending on the pressure of the oil supplied to the clutch 44.

[0022] The torque converter 45 includes an input shaft 45A, an output shaft 45B, a lock-up clutch 45C, a pump wheel 45D, and a turbine wheel 45E. The input shaft 45A is connected to the rotor 31 of the motor-generator 30. The pump wheel 45D is connected to the input shaft 45A. Therefore, the pump wheel 45D rotates when the input shaft 45A rotates. When the pump wheel 45D rotates, a driving force is transmitted to the turbine wheel 45E via a fluid, causing the turbine wheel 45E to rotate. The turbine wheel 45E is connected to the output shaft 45B. The lock-up clutch 45C can connect the input shaft 45A and the output shaft 45B. The output shaft 45B is connected to the automatic transmission 46. In this embodiment, the torque converter 45 can transmit the driving force of the engine 10 to the drive wheels 52 via the automatic transmission 46 or the like. The torque converter 45 is an example of a fluid coupling.

[0023] The engagement state of the lockup clutch 45C is switched between a fully engaged state, a disengaged state, and a partially engaged state depending on the pressure of the oil supplied to the lockup clutch 45C. The fully engaged state refers to a state in which torque can be transmitted between the input shaft 45A and the output shaft 45B via the lockup clutch 45C, and the input shaft 45A and the output shaft 45B rotate integrally. The disengaged state refers to a state in which torque cannot be transmitted between the input shaft 45A and the output shaft 45B via the lockup clutch 45C. The partially engaged state refers to a state in which torque can be transmitted between the input shaft 45A and the output shaft 45B via the lockup clutch 45C, and a difference in rotational speed between the input shaft 45A and the output shaft 45B is permitted. In the partially engaged state, the slip ratio Z can be controlled. The slip ratio Z will be described later.

[0024] The automatic transmission 46 includes an input shaft 46A and an output shaft 46B. The input shaft 46A is connected to the output shaft 45B of the torque converter 45. The input shaft 46A is connected to the output shaft 46B via a clutch and a gear (not shown). The automatic transmission 46 is capable of changing its gear ratio. Here, the gear ratio is a ratio indicating the number of times the input shaft 46A rotates for one rotation of the output shaft 46B. Therefore, the larger the gear ratio, the faster the input shaft 46A rotates relative to the output shaft 46B. An example of the automatic transmission 46 is a stepped automatic transmission. The output shaft 46B is connected to drive wheels 52 via a differential 51. The differential 51 allows a difference in rotational speed to occur between the left and right drive wheels 52.

[0025] As shown in Fig. 1, vehicle 100 is equipped with a hydraulic device 55. Hydraulic device 55 controls the gear ratio of automatic transmission 46 by adjusting the pressure of oil supplied to automatic transmission 46. Hydraulic device 55 also controls the engagement state of lock-up clutch 45C of torque converter 45 by adjusting the pressure of oil supplied to torque converter 45. Hydraulic device 55 also controls the engagement state of clutch 44 by adjusting the pressure of oil supplied to clutch 44.

[0026] 1, the vehicle 100 includes an inverter 56 and a battery 57. The battery 57 is a secondary battery. The inverter 56 adjusts the amount of electric power exchanged between the motor generator 30 and the battery 57.

[0027] <Vehicle electrical configuration> 1, the vehicle 100 is equipped with an accelerator operation amount sensor 81, a vehicle speed sensor 82, a crank angle sensor 83, and a rotor angle sensor 84. The vehicle 100 also is equipped with an intake pressure sensor 85, an air flow meter 86, a fuel temperature sensor 87, and a water temperature sensor 88.

[0028] The accelerator operation amount sensor 81 detects the accelerator operation amount ACC, which is the amount of operation of an accelerator pedal (not shown) operated by the driver. The vehicle speed sensor 82 detects the vehicle speed SP, which is the speed of the vehicle 100. The crank angle sensor 83 detects the crank angle SC, which is the angular position of the crankshaft 18. The rotor angle sensor 84 detects the rotor angle SR, which is the angular position of the rotor 31. The intake pressure sensor 85 detects the intake pressure PI, which is the pressure of the intake air flowing through the intake passage 12. In this embodiment, the intake pressure sensor 85 detects the intake pressure PI, which is the pressure of the intake air in a portion of the intake passage 12 upstream of the throttle valve 23. The air flow meter 86 detects the intake air amount GA, which is the amount of intake air flowing through the intake passage 12 per unit time. The fuel temperature sensor 87 detects the fuel temperature TF, which is the temperature of the fuel flowing through a fuel supply passage connected to the port injection valve 26 and the direct injection valve 27. In other words, the fuel temperature sensor 87 detects the temperature of the fuel supplied to the combustion chamber 10A as the fuel temperature TF. The water temperature sensor 88 detects the water temperature TW, which is the temperature of the cooling water flowing through the water jacket 15. In this embodiment, the water temperature sensor 88 detects the temperature of the cooling water at the downstream end of the water jacket 15 as the water temperature TW.

[0029] As shown in FIG. 1 , vehicle 100 includes a control device 90. The control device 90 acquires a signal indicating accelerator operation amount ACC from accelerator operation amount sensor 81. The control device 90 acquires a signal indicating vehicle speed SP from vehicle speed sensor 82. The control device 90 acquires a signal indicating crank angle SC from crank angle sensor 83. The control device 90 acquires a signal indicating rotor angle SR from rotor angle sensor 84. The control device 90 acquires a signal indicating intake pressure PI from intake pressure sensor 85. The control device 90 acquires a signal indicating intake air amount GA from air flow meter 86. The control device 90 acquires a signal indicating fuel temperature TF from fuel temperature sensor 87. The control device 90 acquires a signal indicating water temperature TW from water temperature sensor 88. Based on the crank angle SC, the control device 90 calculates engine rotation speed NE, which is the rotation speed of crankshaft 18. Based on the rotor angle SR, the control device 90 calculates motor rotation speed NM, which is the rotation speed of rotor 31.

[0030] The control device 90 calculates the vehicle's required driving force, which is a required value of the driving force necessary for the vehicle 100 to travel, based on the accelerator operation amount ACC and the vehicle speed SP. The control device 90 determines the torque distribution between the engine 10 and the motor generator 30 based on the vehicle's required driving force. The control device 90 controls the output of the engine 10 and the power running and regeneration of the motor generator 30 based on the torque distribution between the engine 10 and the motor generator 30.

[0031] The control device 90 controls the engine 10 by outputting control signals to the engine 10. Specifically, it executes various types of control, such as adjusting the opening of the throttle valve 23, adjusting the ignition timing of the ignition device 24, adjusting the amount of fuel injected from the port injection valve 26, adjusting the amount of fuel injected from the direct injection valve 27, and adjusting the amount of water injected from the water injection valve 29. In addition, the control device 90 outputs a control signal to the inverter 56 in order to control the motor generator 30. The control device 90 then controls the motor generator 30 by adjusting the amount of power exchanged between the motor generator 30 and the battery 57 via the inverter 56.

[0032] The control device 90 outputs a control signal to the hydraulic device 55 to control the engagement state of the clutch 44 via the hydraulic device 55. The control device 90 also outputs a control signal to the hydraulic device 55 to control the engagement state of the lock-up clutch 45C of the torque converter 45 via the hydraulic device 55. The control device 90 outputs a control signal to the hydraulic device 55 to control the gear ratio of the automatic transmission 46 via the hydraulic device 55.

[0033] The control device 90 calculates the combustion chamber temperature TC, which is the temperature of the combustion chamber 10A that is currently undergoing the compression stroke, based on the operating state of the engine 10. For example, the control device 90 calculates the combustion chamber temperature TC based on the fuel injection amount supplied to the cylinder 11 from the port injection valve 26 and the in-cylinder injection valve 27, the engine rotation speed NE, the water temperature TW, etc. Specifically, the control device 90 calculates a higher combustion chamber temperature TC the greater the fuel injection amount supplied to the cylinder 11 from the port injection valve 26 and the in-cylinder injection valve 27, the higher the engine rotation speed NE, and the higher the water temperature TW. In this embodiment, the control device 90 repeatedly calculates the combustion chamber temperature TC at a predetermined cycle.

[0034] Based on the operating state of the engine 10, the control device 90 calculates the combustion chamber pressure PC, which is the pressure in the combustion chamber 10A at the compression top dead center during the compression stroke for the combustion chamber 10A currently undergoing the compression stroke. For example, the control device 90 calculates the combustion chamber pressure PC based on the intake pressure PI, the intake air amount GA, the opening of the throttle valve 23, and the like. Specifically, the control device 90 calculates a higher combustion chamber pressure PC the higher the intake pressure PI, the larger the intake air amount GA, and the larger the opening of the throttle valve 23. In this embodiment, the control device 90 repeatedly calculates the combustion chamber pressure PC at a predetermined cycle. The compression top dead center during the compression stroke described above is an example of a predetermined specific point in time during the compression stroke.

[0035] When the vehicle 100 is traveling, the control device 90 selects either the EV mode or the HV mode as the traveling mode of the vehicle 100. Here, the EV mode is a traveling mode in which the engine 10 is stopped while the motor generator 30 is driven to travel the vehicle 100. Therefore, in the EV mode, the vehicle 100 is traveled by the driving force of the motor generator 30. On the other hand, the HV mode is a traveling mode in which the engine 10 is driven in addition to the motor generator 30 to travel the vehicle 100. Therefore, in the HV mode, the vehicle 100 is traveled by the driving force of the engine 10 in addition to the driving force of the motor generator 30.

[0036] The control device 90 selects the EV mode, for example, when the state of charge (SOC) of the battery 57 has a sufficient margin and the required vehicle driving force is small. Examples of when the required vehicle driving force is small include when the vehicle 100 starts moving and when the vehicle 100 is running under a light load with low acceleration. On the other hand, the control device 90 selects the HV mode, for example, when the state of charge (SOC) of the battery 57 does not have a sufficient margin.

[0037] The control device 90 may be configured as a circuit including one or more processors that execute various processes according to a computer program (software). The control device 90 may also be configured as a circuit including one or more dedicated hardware circuits, such as an application-specific integrated circuit (ASIC), that execute at least some of the various processes, or a combination thereof. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to execute processes. The memory, i.e., computer-readable medium, includes any medium that can be accessed by a general-purpose or dedicated computer.

[0038] <Slip ratio change control> Next, the slip ratio change control executed by the control device 90 will be described. In this embodiment, the control device 90 repeatedly executes the slip ratio change control when the vehicle 100 is traveling. This slip ratio change control is control for changing the slip ratio Z of the lockup clutch 45C of the torque converter 45. Here, the slip ratio Z is a value related to the magnitude of torque that can be transmitted between the input shaft 45A and the output shaft 45B via the lockup clutch 45C. Note that the lower the slip ratio Z, the greater the force with which the lockup clutch 45C engages. Therefore, when the lockup clutch 45C is fully engaged, the slip ratio Z is the minimum value of "0." On the other hand, when the lockup clutch 45C is released, the slip ratio Z is the maximum value of "100." On the other hand, when the lockup clutch 45C is partially engaged, the slip ratio Z is a value greater than "0" and less than "100."

[0039] 3, when the control device 90 starts slip ratio change control, it executes the process of step S11. In step S11, the control device 90 determines whether or not the EV mode has been selected as the driving mode of the vehicle 100. If the control device 90 determines in step S11 that the HV mode has been selected as the driving mode of the vehicle 100 (S11: NO), the control device 90 proceeds to step S21. In other words, the control device 90 proceeds to step S21 when the driving force of the engine 10 is being transmitted to the drive wheels 52 via the torque converter 45.

[0040] In step S21, the control device 90 determines whether the combustion chamber temperature TC is equal to or higher than a predetermined specified room temperature A. Here, the specified room temperature A is determined, for example, as follows: First, as a premise, in the engine 10, pre-ignition tends to begin to occur in the combustion chamber 10A when the combustion chamber temperature TC reaches or exceeds a certain temperature. Therefore, the combustion chamber temperature TC at which pre-ignition begins to occur in the combustion chamber 10A is determined through experiments, simulations, etc. Then, the determined combustion chamber temperature TC is determined as the specified room temperature A. In step S21, if the control device 90 determines that the combustion chamber temperature TC is equal to or higher than the specified room temperature A (S21: YES), the control device 90 proceeds to step S22.

[0041] In step S22, the control device 90 determines whether the combustion chamber pressure PC is equal to or greater than a predetermined specified chamber pressure B. Here, the specified chamber pressure B is determined, for example, as follows: First, as a premise, in the engine 10, pre-ignition tends to begin to occur in the combustion chamber 10A when the combustion chamber pressure PC reaches a certain pressure or greater. Therefore, the combustion chamber pressure PC at which pre-ignition begins to occur in the combustion chamber 10A is determined through experiments, simulations, etc. Then, the determined combustion chamber pressure PC is determined as the specified chamber pressure B. In step S22, if the control device 90 determines that the combustion chamber pressure PC is equal to or greater than the specified chamber pressure B (S22: YES), the control device 90 proceeds to step S23.

[0042] In step S23, the control device 90 determines whether the fuel temperature TF is equal to or higher than a predetermined specified fuel temperature C. Here, the specified fuel temperature C is determined, for example, as follows. First, as a premise, in the engine 10, fuel is supplied to the combustion chamber 10A from the port injection valve 26 and the in-cylinder injection valve 27, and the combustion chamber 10A is cooled by the fuel supplied to the combustion chamber 10A. The lower the fuel temperature TF, the more likely the combustion chamber temperature TC is to decrease. Therefore, the higher the fuel temperature TF, the more likely pre-ignition tends to occur in the combustion chamber 10A. Therefore, the specified fuel temperature C is determined through experiments, simulations, etc. as a threshold value for performing the processing from step S41 onwards, which will be described later.

[0043] If the control device 90 determines in step S23 that the fuel temperature TF is less than the specified fuel temperature C (S23: NO), the control device 90 proceeds to step S31. Furthermore, if the control device 90 determines in the above-mentioned step S11 that the EV mode has been selected as the driving mode of the vehicle 100 (S11: YES), the control device 90 proceeds to step S31. Furthermore, if the control device 90 determines in the above-mentioned step S21 that the combustion chamber temperature TC is less than the specified room temperature A (S21: NO), the control device 90 proceeds to step S31. Furthermore, if the control device 90 determines in the above-mentioned step S22 that the combustion chamber pressure PC is less than the specified chamber pressure B (S22: NO), the control device 90 proceeds to step S31.

[0044] In step S31, the control device 90 calculates a base value of the slip ratio Z based on the running state of the vehicle 100. As a specific example, the control device 90 acquires the engine rotation speed NE, the motor rotation speed NM, the gear ratio of the automatic transmission 46, and the like as the running state of the vehicle 100. The control device 90 then calculates the base value of the slip ratio Z by comparing the engine rotation speed NE, the motor rotation speed NM, the gear ratio of the automatic transmission 46, and the like with a predetermined map. Note that, for example, when the vehicle 100 starts moving, the base value of the slip ratio Z can be a numerical value between a minimum value and a maximum value. Thereafter, the control device 90 proceeds to step S32.

[0045] In step S32, the control device 90 sets the base value of the slip ratio Z calculated in step S31 as the final slip ratio Z. Then, the control device 90 controls the torque converter 45 based on the final slip ratio Z. Thereafter, the control device 90 ends the current slip ratio change control.

[0046] On the other hand, if the control device 90 determines in step S23 that the fuel temperature TF is equal to or higher than the specified fuel temperature C (S23: YES), the control device 90 proceeds to step S41. That is, in this embodiment, the execution condition under which pre-ignition can occur is that the combustion chamber temperature TC is equal to or higher than the specified room temperature A, the combustion chamber pressure PC is equal to or higher than the specified chamber pressure B, and the fuel temperature TF is equal to or higher than the specified fuel temperature C.

[0047] In step S41, the control device 90 calculates a base value of the slip ratio Z based on the running state of the vehicle 100. The process of step S41 is the same as the process of step S31 described above. Thereafter, the control device 90 proceeds to step S42.

[0048] In step S42, the control device 90 calculates the coefficient K based on the combustion chamber temperature TC, the combustion chamber pressure PC, and the fuel temperature TF. Specifically, the control device 90 decreases the coefficient K the higher the combustion chamber temperature TC at the time of starting the processing of step S42, the higher the combustion chamber pressure PC at the time of starting the processing of step S42, and the higher the fuel temperature TF at the time of starting the processing of step S42. Here, the coefficient K is a value greater than 0 and less than 1. The control device 90 then multiplies the base value of the slip ratio Z by the coefficient K, and sets the value obtained as the corrected slip ratio Z.

[0049] Due to the above-described method of calculating coefficient K, in the process of step S42, the higher the combustion chamber temperature TC, the greater the decrease in slip ratio Z. Also, in the process of step S42, the higher the combustion chamber pressure PC, the greater the decrease in slip ratio Z. In the process of step S42, the higher the fuel temperature TF, the greater the decrease in slip ratio Z. In this embodiment, the process of step S42 is a reduction process that reduces the slip ratio Z of lock-up clutch 45C compared to when the execution conditions are not satisfied under the same circumstances. After step S42, control device 90 proceeds to step S43.

[0050] In step S43, the control device 90 sets the slip ratio Z after correction in step S42 as the final slip ratio Z. The control device 90 then controls the torque converter 45 based on the final slip ratio Z. Therefore, if the lockup clutch 45C is not fully engaged at the time the processing of step S42 is started, the slip ratio Z of the lockup clutch 45C is reduced by the reduction processing. Note that if the base value of the slip ratio Z is calculated as "0," the value does not change even if it is multiplied by the coefficient K. In other words, even if the processing of step S42 is performed, the lockup clutch 45C remains fully engaged. Thereafter, the control device 90 ends the current slip ratio change control.

[0051] <Operation of this embodiment> As shown in FIG. 3, in the slip ratio change control, when the HV mode is selected as the driving mode of the vehicle 100, the determination process of steps S21 to S23 is executed. When all of the determination processes of steps S21 to S23 are affirmative, that is, when an execution condition for pre-ignition in the combustion chamber 10A is satisfied, the process of step S41 and subsequent steps is executed. Then, in step S42, a reduction process is executed to reduce the slip ratio Z of the lockup clutch 45C. Here, when the driving force of the engine 10 is transmitted to the driving wheels 52 via the torque converter 45 and the lockup clutch 45C is not fully engaged, the rotation speed of the input shaft 45A of the torque converter 45 is higher than the rotation speed of the output shaft 45B. Therefore, when the torque that can be transmitted between the input shaft 45A and the output shaft 45B via the lockup clutch 45C increases due to the reduction process, the difference in rotation speed between the input shaft 45A and the output shaft 45B decreases. As a result, the rotation speed of the input shaft 45A of the torque converter 45 decreases.

[0052] <Effects of this embodiment> (1) As described above, when the rotational speed of the input shaft 45A of the torque converter 45 is reduced by the reduction process, the rotational speed of the crankshaft 18 connected to the input shaft 45A, i.e., the engine rotational speed NE, is reduced. This lengthens the period during which the fuel and intake air mix in the combustion chamber 10A. As a result, the occurrence of pre-ignition due to the shortened period during which the fuel and intake air mix can be suppressed.

[0053] (2) In the engine 10, pre-ignition tends to begin to occur in the combustion chamber 10A when the combustion chamber temperature TC reaches or exceeds a certain temperature. Therefore, the execution conditions in this embodiment include the combustion chamber temperature TC being equal to or higher than a predetermined specified room temperature A. In other words, the condition under which pre-ignition can occur is that the combustion chamber temperature TC, which has a strong correlation with pre-ignition, is equal to or higher than the specified room temperature A. As a result, the execution of the reduction process can be prevented even when the combustion chamber temperature TC is low and pre-ignition is unlikely to occur.

[0054] (3) In the engine 10, pre-ignition tends to begin to occur in the combustion chamber 10A when the combustion chamber pressure PC reaches a certain pressure or higher. Therefore, the execution conditions in this embodiment include the combustion chamber pressure PC being equal to or higher than a predetermined specified chamber pressure B. In other words, the condition under which pre-ignition can occur is that the combustion chamber pressure PC, which has a strong correlation with pre-ignition, is equal to or higher than the specified chamber pressure B. As a result, the execution of the reduction process can be prevented even when the combustion chamber pressure PC is low and pre-ignition is unlikely to occur.

[0055] (4) In the engine 10, fuel is supplied to the combustion chamber 10A from the port injection valve 26 and the in-cylinder injection valve 27, and the combustion chamber 10A is cooled by the fuel supplied to the combustion chamber 10A. The lower the fuel temperature TF, the more likely the combustion chamber temperature TC is to decrease. Therefore, in the engine 10, the higher the fuel temperature TF, the more likely pre-ignition tends to occur in the combustion chamber 10A. Therefore, the execution condition in this embodiment includes the fuel temperature TF being equal to or higher than a predetermined specified fuel temperature C. In other words, the condition under which pre-ignition can occur is that the fuel temperature TF, which has a strong correlation with pre-ignition, is equal to or higher than the specified fuel temperature C. As a result, the execution of the reduction process can be prevented even when pre-ignition is unlikely to occur due to the low fuel temperature TF.

[0056] (5) When the combustion chamber temperature TC is equal to or higher than a predetermined specified room temperature A, the higher the combustion chamber temperature TC, the more likely pre-ignition occurs in the combustion chamber 10A. In contrast, in the reduction process, the higher the combustion chamber temperature TC, the greater the reduction amount of the slip ratio Z. Therefore, when the combustion chamber temperature TC is high, that is, when pre-ignition is likely to occur in the combustion chamber 10A, the reduction amount of the slip ratio Z is greater than when pre-ignition is unlikely to occur. Furthermore, as the reduction amount of the slip ratio Z increases, the engine speed NE also decreases significantly. As a result, the time for fuel and intake air to mix becomes longer, making pre-ignition less likely to occur even when the combustion chamber temperature TC is high.

[0057] (6) When the combustion chamber pressure PC is equal to or higher than a predetermined specified chamber pressure B, the higher the combustion chamber pressure PC, the more likely pre-ignition occurs in the combustion chamber 10A. In contrast, in the reduction process, the higher the combustion chamber pressure PC, the greater the reduction amount of the slip ratio Z. Therefore, when the combustion chamber pressure PC is high, i.e., when pre-ignition is likely to occur in the combustion chamber 10A, the amount of reduction of the slip ratio Z can be made greater than when pre-ignition is unlikely to occur.

[0058] (7) As described above, in the engine 10, the higher the fuel temperature TF, the more likely pre-ignition tends to occur in the combustion chamber 10A. In contrast, in the reduction process, the higher the fuel temperature TF, the greater the reduction amount of the slip ratio Z. Therefore, when the fuel temperature TF is high, that is, when pre-ignition is likely to occur in the combustion chamber 10A, the amount of reduction of the slip ratio Z can be made greater than when pre-ignition is unlikely to occur.

[0059] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0060] In the above embodiment, the execution conditions under which pre-ignition may occur may be changed. For example, any one or two of steps S21 to S23 may be omitted. Furthermore, other conditions may be adopted in place of or in addition to steps S21 to S23, as long as it is possible to determine that pre-ignition may occur.

[0061] In the above embodiment, the reduction process in the slip ratio change control may be changed. For example, in step S42, the control device 90 may calculate the coefficient K regardless of the combustion chamber temperature TC. In this case, the amount of decrease in the slip ratio Z is determined regardless of the combustion chamber temperature TC. Similarly, the control device 90 may calculate the coefficient K regardless of the combustion chamber pressure PC. Furthermore, the control device 90 may calculate the coefficient K regardless of the fuel temperature TF. Note that, for example, the coefficient K may be a fixed value.

[0062] For example, in step S42, the slip ratio Z may be corrected without using the coefficient K. As a specific example, in step S42, the control device 90 may set the corrected slip ratio Z to a value obtained by subtracting a predetermined correction value from the base value of the slip ratio Z. The correction value in this case may be a variable value determined by the combustion chamber temperature TC or the like, or may be a fixed value. In other words, in the processing of step S42, it is sufficient that the corrected slip ratio Z is set to a value that is at least smaller than the base value of the slip ratio Z calculated in the processing of step S41.

[0063] In the above embodiment, the configuration of the vehicle 100 may be changed. For example, the motor generator 30, which is the drive source of the vehicle 100, may be omitted. In other words, the present technology can be applied to any vehicle 100 that is equipped with at least the engine 10. [Explanation of symbols]

[0064] PC...Combustion chamber pressure, TC...Combustion chamber temperature, TF...Fuel temperature, Z...Slip ratio, 10...Engine, 10A...Combustion chamber, 11...Cylinder, 12...Intake passage, 13...Exhaust passage, 16...Piston, 17...Connecting rod, 18...Crankshaft, 23...Throttle valve, 24...Ignition device, 26...Port injection valve, 27...In-cylinder injection valve, 29...Water injection valve, 30...Motor generator, 40...Power transmission device, 41...Case, 42...Damper, 43...Connecting shaft, 44...Clutch, 45...Torque converter motor, 45A...input shaft, 45B...output shaft, 45C...lock-up clutch, 45D...pump impeller, 45E...turbine impeller, 46...automatic transmission, 46A...input shaft, 46B...output shaft, 51...differential, 52...drive wheels, 55...hydraulic device, 81...accelerator operation amount sensor, 82...vehicle speed sensor, 83...crank angle sensor, 84...rotor angle sensor, 85...intake pressure sensor, 86...air flow meter, 87...fuel temperature sensor, 88...water temperature sensor, 90...control device, 100...vehicle.

Claims

1. A hydrogen-fueled engine; a fluid coupling having a lock-up clutch and transmitting the driving force of the engine to the drive wheels via the lock-up clutch; A control device for controlling a vehicle equipped with When the driving force of the engine is transmitted to the drive wheels via the fluid coupling and the lock-up clutch is not in a fully engaged state, if an execution condition is satisfied that is a condition under which pre-ignition may occur in the combustion chamber of the engine, a reduction process is executed to reduce the slip ratio of the lock-up clutch compared to when the execution condition is not satisfied. Vehicle control device.

2. The execution condition includes that the temperature of the combustion chamber is equal to or higher than a predetermined specified room temperature. The vehicle control device according to claim 1 .

3. The execution condition includes that the pressure in the combustion chamber at a predetermined specific time point in the compression stroke is equal to or greater than a predetermined specified chamber pressure. The vehicle control device according to claim 1 or 2.

4. The execution condition includes that the temperature of the fuel supplied to the combustion chamber is equal to or higher than a predetermined specified fuel temperature. The vehicle control device according to claim 1 or 2.

5. In the reduction process, when the temperature of the combustion chamber is high, the amount of reduction of the slip ratio is made larger than when the temperature of the combustion chamber is low. The vehicle control device according to claim 2.

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