Vehicle control device

Abstract

To suppress generation of condensed water in an internal combustion engine.SOLUTION: A vehicle includes an internal combustion engine, a motor generator, a cooling water circulation device, an oil circulation device, a water temperature sensor, and a heat exchanger. The internal combustion engine uses hydrogen as the fuel and functions as a drive source. The motor generator functions as a drive source. The cooling water circulation device can recover cooling water discharged from the internal combustion engine and supply the cooling water to the internal combustion engine again. The oil circulation device can recover oil discharged from the motor generator and supply the oil to the motor generator again. The heat exchanger exchanges heat between the cooling water and the oil. The water temperature sensor detects temperature of the cooling water discharged from the internal combustion engine. A vehicle control device stops the internal combustion engine on condition that the temperature of the cooling water detected by the water temperature sensor is equal to or higher than a predetermined specified temperature and runs the vehicle with drive power of the motor generator.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] The vehicle disclosed in Patent Document 1 includes an internal combustion engine that uses hydrogen as fuel and a control device that controls the internal combustion engine. The internal combustion engine functions as a drive source for the vehicle. The internal combustion engine also has a water temperature sensor that detects the temperature of the coolant flowing through the internal combustion engine. The control device sets the target air-fuel ratio of the internal combustion engine to an air-fuel ratio that is higher than the stoichiometric air-fuel ratio, i.e., an air-fuel ratio where the fuel is lean, on the condition that the coolant temperature detected by the water temperature sensor is equal to or lower than a predetermined specified water temperature. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-047282 Summary of the Invention [Problem to be solved by the invention]

[0004] In a vehicle such as that described in Patent Document 1, when the coolant temperature detected by the water temperature sensor is below a predetermined specified water temperature, i.e., when the temperature of the internal combustion engine is relatively low, the amount of hydrogen available for combustion decreases. When the amount of hydrogen available for combustion decreases, the amount of heat generated by hydrogen combustion also decreases, so it takes time to warm up the internal combustion engine. Furthermore, until the internal combustion engine has fully warmed up, the water vapor contained in the exhaust gas is cooled inside the exhaust pipe and easily turns into condensed water. In other words, in a vehicle such as that described in Patent Document 1, there is a risk that the generation of condensed water may not be sufficiently suppressed. [Means for solving the problem]

[0005] A vehicle control device for solving the above problem is a control device that controls a vehicle having an internal combustion engine that uses hydrogen as fuel and functions as a power source, a motor generator that also functions as a power source, a first refrigerant circulation device that supplies a first refrigerant to the internal combustion engine and recovers the first refrigerant discharged from the internal combustion engine and is capable of supplying it again to the internal combustion engine, a second refrigerant circulation device that supplies a second refrigerant to the motor generator and recovers the second refrigerant discharged from the motor generator and is capable of supplying it again to the motor generator, a temperature sensor that detects the temperature of the first refrigerant discharged from the internal combustion engine, and a heat exchanger that exchanges heat between the first refrigerant and the second refrigerant discharged from the motor generator, and when the temperature of the first refrigerant detected by the temperature sensor is below a predetermined specified temperature, the control device stops the internal combustion engine and runs the vehicle using the driving force of the motor generator.

[0006] According to the above configuration, when the temperature of the internal combustion engine is low, the motor generator is driven, causing the temperature of the second refrigerant discharged from the motor generator to rise. As the temperature of the second refrigerant rises, heat is transferred from the second refrigerant to the first refrigerant in the heat exchanger, causing the temperature of the first refrigerant supplied to the internal combustion engine, and ultimately the temperature of the internal combustion engine, to rise. In this way, the above configuration prevents the temperature of the internal combustion engine from dropping too low. Preventing the temperature of the internal combustion engine from dropping too low allows the internal combustion engine to be quickly warmed up when it is subsequently driven, thereby suppressing the generation of condensed water. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic configuration diagram of a vehicle. [Figure 2] 1 is a schematic diagram of an internal combustion engine. [Figure 3] 10 is a flowchart showing a driving switching 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 schematic configuration of a vehicle 100 will be described.

[0009] As shown in Fig. 1, the vehicle 100 includes an internal combustion engine 10 and a motor generator 30. The internal combustion engine 10 functions as a drive source for the vehicle 100. The internal combustion engine 10 is an internal combustion engine that 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] As shown in FIG. 2, the internal combustion engine 10 includes a plurality of cylinders 11, an intake passage 12, and an exhaust passage 13. The internal combustion 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. Each cylinder 11 is a space for burning a mixture of fuel and intake air. In this embodiment, the internal combustion engine 10 includes four cylinders 11. Note that FIG. 2 shows only one representative cylinder 11.

[0011] Piston 16 is located inside cylinder 11. Piston 16 is connected to crankshaft 18 via connecting rod 17. Piston 16 reciprocates inside cylinder 11 as a mixture of fuel and intake air burns in cylinder 11. The reciprocating motion of piston 16 causes crankshaft 18 to rotate.

[0012] The intake passage 12 is connected to the cylinders 11. The intake passage 12 introduces intake air from outside the internal combustion engine 10 into each cylinder 11. The exhaust passage 13 is connected to the cylinders 11. The exhaust passage 13 discharges exhaust gas from each cylinder 11 to outside the internal combustion 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).

[0013] The internal combustion engine 10 includes a throttle valve 23, a plurality of ignition devices 24, a plurality of port injection valves 26, a plurality of in-cylinder injection valves 27, and a plurality of 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.

[0014] 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 internal combustion engine 10 is equipped with four port injection valves 26 corresponding to the four cylinders 11.

[0015] 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 internal combustion engine 10 is provided with four in-cylinder injection valves 27 corresponding to the four cylinders 11.

[0016] 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 internal combustion engine 10 is provided with four ignition devices 24 corresponding to the four cylinders 11.

[0017] 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 introduced from the intake passage 12 into the cylinder 11. The internal combustion engine 10 is equipped with four water injectors 29 corresponding to the four cylinders 11.

[0018] The internal combustion 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. The water jacket 15 forms part of a cooling water circulation passage 66, which will be described later.

[0019] 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 houses the motor generator 30, the damper 42, the connecting shaft 43, the clutch 44, the torque converter 45, and the automatic transmission 46. 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.

[0020] A first end of the connecting shaft 43 is connected to the crankshaft 18 of the internal combustion 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.

[0021] The torque converter 45 includes a pump wheel 45A, a turbine wheel 45B, and a lock-up clutch 45C. The pump wheel 45A is connected to the rotor 31 of the motor-generator 30. Therefore, the pump wheel 45A rotates as the rotor 31 rotates. When the pump wheel 45A rotates, a driving force is transmitted to the turbine wheel 45B via the fluid, causing the turbine wheel 45B to rotate. The turbine wheel 45B is connected to the automatic transmission 46. The lock-up clutch 45C connects the rotor 31 of the motor-generator 30 to the automatic transmission 46, bypassing the pump wheel 45A and the turbine wheel 45B. The engagement state of the lock-up clutch 45C is switched between an engaged state and a disengaged state depending on the pressure of the oil supplied to the lock-up clutch 45C.

[0022] The automatic transmission 46 includes an input shaft 46A and an output shaft 46B. The input shaft 46A is connected to a turbine wheel 45B of the torque converter 45. The input shaft 46A is also connected to a lock-up clutch 45C of the torque converter 45. Therefore, in the automatic transmission 46, driving force is transmitted from the turbine wheel 45B and the lock-up clutch 45C of the torque converter 45 to the input shaft 46A. The input shaft 46A is connected to the output shaft 46B via a clutch and gears (not shown). The automatic transmission 46 has a variable gear ratio. Here, the gear ratio indicates the number of times the input shaft 46A rotates for each 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 .

[0023] 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.

[0024] 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.

[0025] <Circulation device peripheral configuration> As shown in FIG. 1, the vehicle 100 includes a cooling water circulation system 60, an oil circulation system 70, and a heat exchanger 75.

[0026] The coolant circulation device 60 includes a coolant pump 61, a thermostat 62, a radiator 63, a coolant circulation passage 66, and a bypass passage 68. The coolant pump 61 pumps coolant taken in through an intake port and pumps it out from a discharge port. An example of the coolant pump 61 is a so-called mechanical pump that is driven by the rotation of the crankshaft 18 of the internal combustion engine 10.

[0027] The upstream end of the cooling water circulation passage 66 is connected to the discharge port of the cooling water pump 61. The downstream end of the cooling water circulation passage 66 is connected to the suction port of the cooling water pump 61. In other words, the cooling water circulation passage 66 is a circular flow path that extends from the cooling water pump 61 and returns to the cooling water pump 61.

[0028] The radiator 63 is located downstream of the cooling water pump 61 in the cooling water circulation passage 66. The cooling water passage in the radiator 63 forms part of the cooling water circulation passage 66. The radiator 63 cools the cooling water circulating within the radiator 63 by heat exchange with the air. The water jacket 15 of the internal combustion engine 10 is located downstream of the radiator 63 in the cooling water circulation passage 66 and upstream of the cooling water pump 61. In this way, the cooling water circulation device 60 supplies cooling water to the water jacket 15 of the internal combustion engine 10, and is able to recover cooling water discharged from the water jacket 15 of the internal combustion engine 10 and supply it again to the water jacket 15 of the internal combustion engine 10.

[0029] The upstream end of the bypass passage 68 is connected to a portion of the cooling water circulation passage 66 that is downstream when viewed from the cooling water pump 61 and upstream when viewed from the radiator 63. The downstream end of the bypass passage 68 is connected to a portion of the cooling water circulation passage 66 that is downstream when viewed from the radiator 63 and upstream when viewed from the water jacket 15.

[0030] The thermostat 62 is located at the connection between the upstream end of the bypass passage 68 and the coolant circulation passage 66. The thermostat 62 switches the flow of coolant by opening and closing according to the temperature of the coolant. Specifically, when the temperature of the coolant discharged by the coolant pump 61 is below a predetermined temperature A, the thermostat 62 opens the bypass passage 68 and closes the passage of the coolant circulation passage 66 on the radiator 63 side. As a result, the coolant that reaches the thermostat 62 flows through the bypass passage 68. In other words, when the temperature of the coolant discharged by the coolant pump 61 is below the predetermined temperature A, the coolant circulates without passing through the radiator 63. On the other hand, when the temperature of the coolant discharged by the coolant pump 61 is equal to or higher than the predetermined temperature A, the thermostat 62 closes the bypass passage 68 and opens the passage of the coolant circulation passage 66 on the radiator 63 side. As a result, the coolant that reaches the thermostat 62 flows toward the radiator 63. That is, when the temperature of the coolant discharged by the coolant pump 61 is equal to or higher than a predetermined temperature A, the coolant circulates through the radiator 63. An example of the predetermined temperature A is several tens of degrees Celsius.

[0031] The oil circulation device 70 includes an oil pump 71 and an oil circulation passage 72. The oil pump 71 pumps oil through an intake port and pumps it out of a discharge port. An example of the oil pump 71 is a so-called mechanical pump that is driven by the rotation of the pump impeller 45A of the torque converter 45.

[0032] The upstream end of the oil circulation passage 72 is connected to the discharge port of the oil pump 71. The downstream end of the oil circulation passage 72 is connected to the suction port of the oil pump 71. In other words, the oil circulation passage 72 is a circular flow path that extends from the oil pump 71 and returns to the oil pump 71.

[0033] The power transmission device 40 described above is located downstream of the oil pump 71 in the oil circulation passage 72. The oil flow path within the case 41 of the power transmission device 40 forms part of the oil circulation passage 72. The oil that reaches the inside of the case 41 of the power transmission device 40 circulates via the components housed in the case 41 and the hydraulic device 55. In other words, the oil discharged from the case 41 of the power transmission device 40 is oil discharged from the motor generator 30 and the like. In this way, the oil circulation device 70 can supply oil to the motor generator 30, and collect oil discharged from the motor generator 30 and supply it again to the motor generator 30.

[0034] The heat exchanger 75 is located in the coolant circulation passage 66 downstream from the water jacket 15 of the internal combustion engine 10 and upstream from the coolant pump 61. The heat exchanger 75 is also located in the oil circulation passage 72 downstream from the oil pump 71 and upstream from the case 41 of the power transmission device 40. The coolant passage in the heat exchanger 75 forms part of the coolant circulation passage 66. The oil passage in the heat exchanger 75 forms part of the oil circulation passage 72. The heat exchanger 75 exchanges heat between the coolant flowing through the heat exchanger 75 and the oil.

[0035] In this embodiment, the cooling water is an example of a first refrigerant. The cooling water circulation device 60 is an example of a first refrigerant circulation device. The oil is an example of a second refrigerant. The oil circulation device 70 is an example of a second refrigerant circulation device.

[0036] <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 water temperature sensor 84. The vehicle 100 also is equipped with a current sensor 86, a voltage sensor 87, and a battery temperature sensor 88.

[0037] 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 water temperature sensor 84 detects the water temperature TW, which is the temperature of the coolant discharged from the internal combustion engine 10. Specifically, the water temperature sensor 84 detects the temperature of the downstream end of the water jacket 15 as the water temperature TW. The water temperature sensor 84 is an example of a temperature sensor that detects the temperature of the first refrigerant. The current sensor 86 detects the current IB, which is the current input / output to / from the battery 57. The voltage sensor 87 detects the voltage VB, which is the voltage between the terminals of the battery 57. The battery temperature sensor 88 detects the battery temperature TB, which is the temperature of the battery 57.

[0038] As shown in FIG. 1, vehicle 100 is equipped with a control device 90. Control device 90 obtains a signal indicating accelerator operation amount ACC from accelerator operation amount sensor 81. Control device 90 obtains a signal indicating vehicle speed SP from vehicle speed sensor 82. Control device 90 obtains a signal indicating crank angle SC from crank angle sensor 83. Control device 90 obtains a signal indicating water temperature TW from water temperature sensor 84. Control device 90 obtains a signal indicating current IB from current sensor 86. Control device 90 obtains a signal indicating voltage VB from voltage sensor 87. Control device 90 obtains a signal indicating battery temperature TB from battery temperature sensor 88. Control device 90 calculates engine speed NE, which is the rotational speed of crankshaft 18, based on crank angle SC.

[0039] 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 internal combustion engine 10 and the motor generator 30 based on the vehicle's required driving force. The control device 90 controls the output of the internal combustion engine 10 and the power running and regeneration of the motor generator 30 based on the torque distribution between the internal combustion engine 10 and the motor generator 30.

[0040] The control device 90 controls the internal combustion engine 10 by outputting control signals to the internal combustion engine 10. Specifically, it executes various controls 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 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.

[0041] The control device 90 controls the engagement state of the clutch 44 via the hydraulic device 55 by outputting a control signal to the hydraulic device 55. The control device 90 controls the engagement state of the lock-up clutch 45C of the torque converter 45 via the hydraulic device 55 by outputting a control signal to the hydraulic device 55. The control device 90 controls the gear ratio of the automatic transmission 46 via the hydraulic device 55 by outputting a control signal to the hydraulic device 55.

[0042] The control device 90 calculates the charging rate SOC of the battery 57 based on the current IB, the voltage VB, and the battery temperature TB. Specifically, the control device 90 calculates the charging rate SOC based on the following equation.

[0043] Formula (1): Charging rate SOC [%] = remaining capacity of battery 57 [Ah] / full charge capacity of battery 57 [Ah] × 100 [%] In the above formula (1), the full charge capacity is calculated based on, for example, the voltage VB and the battery temperature TB of the battery 57. The remaining capacity is calculated based on, for example, the voltage VB and the current IB of the battery 57.

[0044] The control device 90 controls the charging of the battery 57. This charging control controls the state of charge SOC of the battery 57 to be in a range between an upper limit SOCH and a lower limit SOCL. An example of the upper limit SOCH is 60 to 80%. An example of the lower limit SOCL is 20 to 30%.

[0045] 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 internal combustion 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 vehicle 100 is traveled by driving the internal combustion engine 10 in addition to the motor generator 30. Therefore, in the HV mode, the vehicle 100 is traveled by the driving force of the internal combustion engine 10 in addition to the driving force of the motor generator 30.

[0046] 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.

[0047] 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.

[0048] <Drive switching control> Next, a description will be given of the driving switching control executed by the control device 90. The control device 90 repeatedly executes the driving switching control when the vehicle 100 is driven.

[0049] As shown in FIG. 3, when the control device 90 starts running switching control, it executes the processing of step S11. In step S11, the control device 90 determines whether the water temperature TW is higher than a predetermined specified temperature B. Here, the specified temperature B is determined, for example, as follows. First, an upper limit value of the water temperature TW at which it is determined that warming up is necessary in the internal combustion engine 10 is obtained through experiments or the like. Then, the obtained upper limit value of the water temperature TW is set as the specified temperature B. Note that in this embodiment, the specified temperature B is a value that is lower by a certain temperature than the predetermined temperature A of the thermostat 62 described above. An example of the specified temperature B is several degrees Celsius to several tens of degrees Celsius. In step S11, if the control device 90 determines that the water temperature TW is higher than the specified temperature B (S11: YES), the control device 90 proceeds to the processing of step S21.

[0050] In step S21, the control device 90 executes normal driving processing. In this normal driving processing, the control device 90 selects either the EV mode or the HV mode as the driving mode of the vehicle 100 depending on the state of charge (SOC) of the battery 57. When the HV mode is selected, the control device 90 controls the internal combustion engine 10 by referring to a predetermined driving control map. The driving control map indicates a combination of the engine rotation speed NE and the torque of the internal combustion engine 10 that minimizes fuel consumption when the output of the internal combustion engine 10 is a certain output. The driving control map is created by previously determining the combination of the engine rotation speed NE and the torque of the internal combustion engine 10 through experiments or the like. The control device 90 stores the created driving control map in advance. After step S21, the control device 90 ends the current driving switching control. The control device 90 then proceeds to step S11 again.

[0051] On the other hand, in step S11, if the control device 90 determines that the water temperature TW is equal to or lower than the specified temperature B (S11: NO), the control device 90 proceeds to step S12. That is, the control device 90 proceeds with the processing from step S12 onwards, on the condition that the water temperature TW is equal to or lower than the specified temperature B.

[0052] In step S12, the control device 90 reduces the charging rate lower limit SOCL by a fixed value relative to its initial value. An example of the charging rate lower limit SOCL after the processing of step S12 is 10 to 20%. Note that if the charging rate lower limit SOCL has been reduced in the previous processing of step S12, the control device 90 maintains that charging rate lower limit SOCL. Furthermore, if the determination in the processing of step S11 after the processing of step S12 is affirmative, the control device 90 returns the charging rate lower limit SOCL to its initial value. After step S12, the control device 90 proceeds to the processing of step S13.

[0053] In step S13, the control device 90 determines whether the storage rate SOC is equal to or greater than the storage rate lower limit SOCL. If the control device 90 determines in step S13 that the storage rate SOC is equal to or greater than the storage rate lower limit SOCL (S13: YES), the process proceeds to step S31.

[0054] In step S31, the control device 90 selects the EV mode as the driving mode of the vehicle 100. In other words, the control device 90 stops the internal combustion engine 10 and causes the vehicle 100 to travel using the driving force of the motor generator 30. Thereafter, the control device 90 proceeds to step S32.

[0055] In step S32, the control device 90 controls the lock-up clutch 45C of the torque converter 45 to be in a disengaged state. Thereafter, the control device 90 advances the process to step S33.

[0056] In step S33, the control device 90 controls the automatic transmission 46 so that the gear ratio of the automatic transmission 46 increases by a predetermined constant gear ratio. If the gear ratio of the automatic transmission 46 has been increased in the previous step S33, the control device 90 maintains that gear ratio of the automatic transmission 46. Thereafter, the control device 90 proceeds to step S34.

[0057] In step S34, the control device 90 controls the clutch 44 to be in a released state. After that, the control device 90 ends the current running switching control. Then, the control device 90 advances the process to step S11 again.

[0058] On the other hand, in step S13, when the control device 90 determines that the storage rate SOC is less than the storage rate lower limit SOCL (S13: NO), the control device 90 advances the process to step S41.

[0059] In step S41, the control device 90 selects the HV mode as the driving mode of the vehicle 100. Thereafter, the control device 90 advances the process to step S42. In step S42, the control device 90 sets the target air-fuel ratio of the internal combustion engine 10 to an air-fuel ratio that is higher than the stoichiometric air-fuel ratio, i.e., an air-fuel ratio where the fuel is lean. The control device 90 controls the motor generator 30 so as to compensate for the driving force of the vehicle 100 that is reduced due to the increase in the target air-fuel ratio of the internal combustion engine 10. Thereafter, the control device 90 ends the current running switching control. Then, the control device 90 advances the processing to step S11 again.

[0060] <Operation of this embodiment> As shown in FIG. 3 , the vehicle 100 selects the EV mode as its driving mode when the water temperature TW is equal to or lower than the specified temperature B and the state of charge SOC is equal to or higher than the state of charge lower limit SOCL. In other words, the internal combustion engine 10 is stopped and the vehicle 100 is driven by the driving force of the motor-generator 30, provided that the water temperature TW is equal to or lower than the specified temperature B. When the motor-generator 30 is driven in this manner, the temperature of the oil circulating near the motor-generator 30 increases due to heat generated by the motor-generator 30. This increases the temperature of the oil discharged from the case 41 of the power transmission device 40 in the oil circulation passage 72. As a result, the temperature of the coolant in the coolant circulation passage 66 is likely to increase due to heat exchange between the coolant and the oil in the heat exchanger 75. Transferring the heat of the coolant to the internal combustion engine 10 prevents the temperature of the internal combustion engine 10 from becoming excessively low when the internal combustion engine 10 is stopped.

[0061] <Effects of this embodiment> (1) If the temperature of the internal combustion engine 10 can be prevented from dropping excessively as described above, the time required to warm up the internal combustion engine 10 when the internal combustion engine 10 is subsequently driven is likely to be shortened. As a result, the internal combustion engine 10 can be warmed up quickly, and the generation of condensed water in the exhaust passage 13 of the internal combustion engine 10, etc. can be prevented.

[0062] (2) In the vehicle 100, when the water temperature TW is equal to or lower than the specified temperature B and the EV mode is selected as the driving mode of the vehicle 100, the lock-up clutch 45C of the torque converter 45 is controlled to be disengaged. This reduces the transmission efficiency of the driving force transmitted from the rotor 31 of the motor generator 30 to the automatic transmission 46 via the torque converter 45. Therefore, for the same driving force actually obtained as the driving force for the vehicle 100, the driving force required by the motor generator 30 is greater than when, for example, the lock-up clutch 45C of the torque converter 45 is engaged. This tends to increase the amount of heat generated by the motor generator 30. As a result, the temperature of the oil discharged from the case 41 of the power transmission device 40 can be increased.

[0063] (3) In the vehicle 100, when the water temperature TW is equal to or lower than the specified temperature B and the EV mode is selected as the driving mode of the vehicle 100, the automatic transmission 46 is controlled to increase the gear ratio of the automatic transmission 46. Therefore, the speed at which the input shaft 46A rotates increases relative to the output shaft 46B. As a result, if the rotational speed of the output shaft 46B, in other words, the vehicle speed SP, remains the same, the rotational speed of the rotor 31 of the motor generator 30 connected to the input shaft 46A increases. This increases the amount of heat generated by the motor generator 30. As a result, the temperature of the oil discharged from the case 41 of the power transmission device 40 can be increased.

[0064] (4) Suppose that when the EV mode is selected as the driving mode of the vehicle 100, the clutch 44 is controlled to be in an engaged state. In this case, even when the internal combustion engine 10 is stopped, the crankshaft 18 rotates due to the driving force transmitted from the rotor 31 of the motor-generator 30 to the crankshaft 18 via the clutch 44. The rotation of the crankshaft 18 causes the pistons 16 to reciprocate, causing each cylinder 11 to repeat an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke. As a result, air flows through the intake passage 12, the cylinders 11, and the exhaust passage 13 in that order. As a result, the cylinders 11 and the like are easily cooled by heat exchange with the air.

[0065] In this regard, in the vehicle 100, when the water temperature TW is equal to or lower than the specified temperature B and the EV mode is selected as the driving mode of the vehicle 100, the clutch 44 is controlled to be in a disengaged state. Therefore, the crankshaft 18 is not rotated by the driving force from the rotor 31 of the motor generator 30. As a result, cooling of the cylinders 11 and the like due to heat exchange with the air can be suppressed.

[0066] (5) In the vehicle 100, when the water temperature TW is equal to or lower than the specified temperature B, the storage rate lower limit SOCL is reduced by a certain value relative to the initial value of the storage rate lower limit SOCL. This makes it easier to determine that the storage rate SOC is equal to or higher than the storage rate lower limit SOCL. This increases the number of opportunities to execute the processes of steps S31 to S34. In other words, when the water temperature TW is equal to or lower than the specified temperature B, the EV mode is more likely to be selected as the driving mode of the vehicle 100.

[0067] (6) In the vehicle 100, when the water temperature TW is equal to or lower than the specified temperature B and the state of charge SOC is lower than the state of charge lower limit SOCL, the HV mode is selected as the driving mode of the vehicle 100. At this time, the control device 90 sets the target air-fuel ratio of the internal combustion engine 10 to an air-fuel ratio that is higher than the stoichiometric air-fuel ratio, i.e., an air-fuel ratio that is lean. This reduces the amount of fuel burned in the cylinders 11 of the internal combustion engine 10, thereby suppressing the amount of water vapor generated in the cylinders 11. As a result, even if a situation arises in which the internal combustion engine 10 is driven when the water temperature TW is equal to or lower than the specified temperature B, the amount of condensed water generated in the exhaust passage 13 of the internal combustion engine 10 can be suppressed.

[0068] (7) In the vehicle 100, when the water temperature TW is equal to or lower than the specified temperature B, the process proceeds to step S12 and subsequent steps. Here, the specified temperature B is a value that is lower than the predetermined temperature A of the thermostat 62 by a certain temperature. Therefore, when the water temperature TW is equal to or lower than the specified temperature B, the thermostat 62 opens the bypass passage 68, and the coolant circulates in the coolant circulation device 60 without passing through the radiator 63. As a result, when the water temperature TW is equal to or lower than the specified temperature B, the coolant can be prevented from being further cooled in the radiator 63.

[0069] <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.

[0070] In the above embodiment, the driving switching control may be changed. For example, in step S32, the control device 90 may control the connection state of the lock-up clutch 45C of the torque converter 45 to an engaged state. As a specific example, when the driving force of the motor generator 30 is sufficiently large, the influence of controlling the connection state of the lock-up clutch 45C of the torque converter 45 as described above is small.

[0071] For example, in step S33, the control device 90 may not change the gear ratio of the automatic transmission 46. As a specific example, if the rotation speed of the rotor 31 of the motor generator 30 is sufficiently high, the impact of not changing the gear ratio of the automatic transmission 46 is small.

[0072] For example, in step S34, the clutch 44 may be controlled to be in an engaged state. As a specific example, if the temperature of the air outside the vehicle 100 is relatively high, it is acceptable for air to flow into the cylinders 11, etc., as the crankshaft 18 rotates.

[0073] For example, in step S42, the control device 90 may set the target air-fuel ratio of the internal combustion engine 10 to the stoichiometric air-fuel ratio, or to an air-fuel ratio that is lower than the stoichiometric air-fuel ratio. Even in this configuration, if there is a period in which the water temperature TW is equal to or lower than the specified temperature B and the state of charge SOC is equal to or higher than the state of charge lower limit SOCL, the temperature of the internal combustion engine 10 may be increased during that period.

[0074] For example, the process of step S12 may be omitted. For example, if the determination in step S11 is negative, the process in step S31 may be executed. In other words, the processes in steps S12 and S13 may be omitted. First, in the vehicle 100, it is unlikely that the state of charge SOC is less than the state of charge lower limit SOCL, and the difference between the state of charge SOC and the state of charge lower limit SOCL will be excessively large. Therefore, even if the state of charge SOC is less than the state of charge lower limit SOCL, the motor generator 30 may be driven by electric power from the battery 57, if only temporarily. Therefore, if the determination in step S11 is negative, the control device 90 may execute the processes from step S31 onwards.

[0075] For example, the specified temperature B in step S11 may be set regardless of the predetermined temperature A of the thermostat 62. In this configuration, when the processing from step S31 onwards is executed, the coolant pump 61 is stopped as the internal combustion engine 10 is stopped. Therefore, when the processing from step S31 onwards is executed, the coolant does not circulate in the coolant circulation device 60, and therefore even if the thermostat 62 opens the coolant circulation passage 66 on the radiator 63 side, the effect is small.

[0076] In the above embodiment, the configuration of the vehicle 100 may be changed. For example, the position of the water temperature sensor 84 may be changed. As a specific example, the water temperature sensor 84 may be located in a portion of the coolant circulation passage 66 other than the water jacket 15. Furthermore, the water temperature sensor 84 may be located in the bypass passage 68.

[0077] For example, the cooling water pump 61 may be a so-called electric pump driven by an electric motor. In this case, the control device 90 may drive the cooling water pump 61 when executing the processes from step S31 onwards. This may increase the temperature of not only the cooling water in the cooling water circulation passage 66 near the heat exchanger 75 but also the circulating cooling water due to heat exchange between the cooling water and the oil in the heat exchanger 75. Also, for example, the oil pump 71 may be a so-called electric pump driven by an electric motor.

[0078] In the above embodiment, the first refrigerant is not limited to coolant, but oil or the like may also be used. Even in this case, if the first refrigerant circulation device allows oil or the like to circulate through the internal combustion engine 10, it is possible to prevent the temperature of the internal combustion engine 10 from being excessively low due to heat exchange with the oil or the like. Note that, like the first refrigerant, other refrigerants may also be used as the second refrigerant. [Explanation of symbols]

[0079] 10...Internal combustion engine 11...cylinder 12...Intake passage 13...Exhaust passage 15...Water jacket 18...Crankshaft 30...Motor generator 40...Power transmission device 41...Case 45...Torque converter 46...Automatic transmission 51...Differential 52...Drive wheel 55...Hydraulic system 60…Cooling water circulation device 61...Cooling water pump 62...Thermostat 63...Radiator 66…Cooling water circulation passage 68...Bypass passage 70...Oil circulation device 71...Oil pump 72...Oil circulation passage 75...Heat exchanger 84...Water temperature sensor 90...Control device 100...Vehicle

Claims

[Claim 1] an internal combustion engine that uses hydrogen as fuel and functions as a driving source; a motor generator that functions as a drive source; a torque converter including a lock-up clutch capable of transmitting driving force from the motor generator to driving wheels; a first refrigerant circulation device that supplies a first refrigerant to the internal combustion engine, recovers the first refrigerant discharged from the internal combustion engine, and supplies the first refrigerant to the internal combustion engine again; a second refrigerant circulation device that supplies a second refrigerant to the motor generator, recovers the second refrigerant discharged from the motor generator, and supplies the second refrigerant to the motor generator again; a temperature sensor for detecting the temperature of the first refrigerant discharged from the internal combustion engine; a heat exchanger that exchanges heat between the first refrigerant and the second refrigerant discharged from the motor generator; A control device for controlling a vehicle comprising: On the condition that the temperature of the first refrigerant detected by the temperature sensor is equal to or lower than a predetermined specified temperature, the lock-up clutch is controlled to a disengaged state, the internal combustion engine is stopped, and the vehicle is driven by the driving force of the motor generator. Vehicle control device.

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