Vehicle cooling system

Abstract

To provide a vehicular cooling system which can properly cool a transmission having a built-in electric motor.SOLUTION: A vehicular cooling system includes: a cooling circuit switch part 40 which switches a supply state of a coolant to an oil cooler 4A which cools a transmission oil of a transmission 3; and a control unit 10 which controls the cooling circuit switch part 40 based on a travel mode. The control unit 10 controls the cooling circuit switch part 40 based on the travel mode, an oil temperature of the transmission oil, and a water temperature of an engine. The cooling circuit switch part 40 can be switched to one of a first state in which the coolant in a low temperature coolant circulation circuit 23 is supplied to the oil cooler 4A, a second state in which the coolant in a high temperature coolant circulation circuit 22 and the coolant in the low temperature coolant circulation circuit 23 are not supplied to the oil cooler 4A, and a third state in which the coolant in the high temperature coolant circulation circuit 22 is supplied to the oil cooler 4A.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vehicle cooling system.

Background Art

[0002] Patent Document 1 describes a vehicle cooling device including a first cooling system, a second cooling system that circulates cooling water to a second cooling target having a lower temperature than the first cooling target, a first heat exchanger that performs heat exchange between the oil of a transmission and the cooling water of the first cooling system, and a second heat exchanger that performs heat exchange between the oil and the cooling water of the second cooling system. When the oil temperature is below a predetermined oil temperature, this vehicle cooling device does not perform heat exchange. When the oil temperature is higher than the predetermined oil temperature and the cooling water temperature of the second cooling system is higher than a predetermined water temperature, heat exchange is performed by the first heat exchanger. When the oil temperature is higher than the predetermined oil temperature and the cooling water temperature of the second cooling system is below the predetermined water temperature, heat exchange is performed by both heat exchangers.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, a hybrid vehicle equipped with an engine and an electric motor switches between at least an engine running mode in which the vehicle runs using at least the engine as a driving force source and an EV running mode in which the vehicle runs using the electric motor as a driving force source without using the engine as a driving force source.

[0005] However, when applying the technology described in Patent Document 1 to a hybrid vehicle in which an electric motor is built into a transmission, there is a problem that the transmission incorporating the electric motor cannot be appropriately cooled. That is, when the inverter for the electric motor and the transmission are cooled by a common low-temperature cooling system, the transmission may be cooled to a temperature lower than the appropriate temperature due to the influence of the control temperature of the inverter, or the heat dissipation amount of the radiator may be insufficient when the transmission is at a high temperature. Further, when the transmission is cooled by a high-temperature cooling system, cooling water cannot be supplied to the transmission when the water pump of the high-temperature cooling system is stopped.

[0006] The present invention has been made paying attention to the above problems, and an object thereof is to provide a vehicle cooling system capable of appropriately cooling a transmission incorporating an electric motor.

Means for Solving the Problems

[0007] The present invention is mounted on a hybrid vehicle having a transmission incorporating an electric motor, and having at least an engine running mode in which the vehicle runs using the engine as a driving force source and an EV running mode in which the vehicle runs using the electric motor as a driving force source without using the engine as a driving force source. The hybrid vehicle includes a first water pump that operates using the engine as a driving force source, and a high-temperature cooling water circulation circuit through which cooling water that cools at least the engine circulates. The hybrid vehicle also includes a second water pump that operates electrically, and a low-temperature cooling water circulation circuit through which cooling water that is lower in temperature than the cooling water circulating through the high-temperature cooling water circulation circuit circulates, and the low-temperature cooling water circulation circuit cools at least an inverter electrically connected to the electric motor. The vehicle cooling system is characterized by including a cooling circuit switching unit that switches the supply state of the cooling water to an oil cooler that cools the transmission oil of the transmission, and a control unit that controls the cooling circuit switching unit based on the running mode.

Effects of the Invention

[0008] According to the present invention as described above, a vehicle cooling system capable of appropriately cooling a transmission incorporating an electric motor can be provided.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0010] A vehicle cooling system according to an embodiment of the present invention includes a transmission incorporating an electric motor, and has a running mode including an engine running mode in which the vehicle runs using at least an engine as a driving force source, and an EV running mode in which the vehicle runs using an electric motor as a driving force source without using the engine as a driving force source. The vehicle cooling system is mounted on a hybrid vehicle, and includes a first water pump that operates using the engine as a driving force source, and a high-temperature cooling water circulation circuit through which cooling water that at least cools the engine circulates; and a second water pump that operates electrically, and a low-temperature cooling water circulation circuit through which cooling water that is cooler than the cooling water circulating through the high-temperature cooling water circulation circuit circulates, and that at least cools an inverter electrically connected to the electric motor. The vehicle cooling system includes a cooling circuit switching unit that switches the supply state of the cooling water to an oil cooler that cools the transmission oil of the transmission, and a control unit that controls the cooling circuit switching unit based on the running mode. Thus, the vehicle cooling system according to an embodiment of the present invention can appropriately cool a transmission incorporating an electric motor.

Example

[0011] Hereinafter, a vehicle cooling system according to an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 to 7 are diagrams showing a vehicle cooling system according to an embodiment of the present invention.

[0012] First, the configuration will be described. In FIG. 1, a vehicle 1 includes an engine (denoted as ENG in the figure) 2, a transmission (denoted as T / M in the figure) 3, and an electric motor (denoted as MGU in the figure) 4.

[0013] The engine 2 is an internal combustion engine type engine that uses gasoline or diesel fuel, and generates a driving force (engine torque) for running. Inside the engine 2, a water jacket (not shown) through which cooling water flows is provided.

[0014] The transmission 3 is connected to the engine 2, and the driving force (engine torque) generated by the engine 2 is transmitted. The transmission 3 is provided with a speed change mechanism (not shown), and the rotation transmitted from the engine 2 is changed in speed by the speed change mechanism and transmitted to drive wheels (not shown).

[0015] The electric motor 4 is electrically connected to a battery (not shown) via an inverter 5. The electric motor 4 is built into a part downstream of the speed change mechanism in the transmission 3. The driving force for traveling (motor torque) generated by the electric motor 4 is transmitted to the drive wheels without passing through the speed change mechanism of the transmission 3.

[0016] An oil cooler (denoted as O / C in the figure) 4A is provided for the electric motor 4, and the oil cooler 4A cools the transmission oil flowing inside the electric motor 4 by heat exchange with cooling water.

[0017] The vehicle 1 is provided with one radiator 50. The radiator 50 cools the cooling water by heat exchange with the traveling wind. The radiator 50 includes a high-temperature part 50H that cools the relatively high-temperature cooling water taken in from the engine 2 and a low-temperature part 50L that cools the relatively low-temperature cooling water taken in from the oil cooler 4A.

[0018] The vehicle 1 is provided with an engine cooling water circulation circuit 21. The engine cooling water circulation circuit 21 connects the engine 2 and the radiator 50 and circulates the cooling water between the engine 2 and the radiator 50. The radiator 50 cools the cooling water circulating in the engine cooling water circulation circuit 21.

[0019] The engine cooling water circulation circuit 21 includes a feed passage 21A that sends the cooling water from the engine 2 to the radiator 50, and the feed passage 21A is connected to the radiator 50.

[0020] The engine cooling water circulation circuit 21 includes a return passage 21B that returns the cooling water cooled by the radiator 50 to the engine 2, and the return passage 21B is connected to the radiator 50.

[0021] Vehicle 1 is equipped with a mechanical water pump (denoted as WP in the figure) 32 that operates with the engine 2 as the power source. A pulley (not shown) of the water pump 32 is connected to a crank pulley (not shown) of the engine 2 via a fan belt (not shown), and the water pump 32 forcibly circulates the cooling water by the power obtained from the rotation of the engine 2. The water pump 32 constitutes the first water pump in the present invention. The water pump 32 is provided at the end of the return passage 21B on the engine 2 side, and by being driven by the engine 2, it sends the cooling water sucked from the return passage 21B to the engine 2.

[0022] A thermostat 33 is provided between the engine 2 and the feed passage 21A. The thermostat 33 closes its valve when the temperature of the cooling water is lower than a predetermined temperature, preventing the circulation of the cooling water in the engine cooling water circulation circuit 21. The thermostat 33 opens its valve when the temperature of the cooling water becomes higher than the predetermined temperature, allowing the circulation of the cooling water in the engine cooling water circulation circuit 21. That is, when the thermostat 33 is open, the cooling water sent to the engine 2 by the water pump 32 is discharged from the engine 2 after cooling the engine 2. Then, the cooling water is introduced into the radiator 50 through the feed passage 21A, cooled in the radiator 50, and then returned to the water pump 32 through the return passage 21B.

[0023] Vehicle 1 is equipped with a high-temperature cooling water circulation circuit 22. In the high-temperature cooling water circulation circuit 22, the cooling water that at least cools the engine 2 circulates. The heater core 31 and the EGR cooler 30 are connected to the engine 2 via the high-temperature cooling water circulation circuit 22. The heater core 31 heats a passenger compartment (not shown) by heat exchange with the high-temperature cooling water introduced from the engine 2. The EGR cooler 30 cools the exhaust gas discharged from the engine 2 by heat exchange with the cooling water. The exhaust gas cooled by the EGR cooler 30 is sent to the intake path of the engine 2.

[0024] The high-temperature cooling water circulation circuit 22 has a feed passage 22A for sending cooling water from the engine 2 to the heater core 31, a feed passage 22B for sending cooling water from the engine 2 to the EGR cooler 30, and a return passage 22C for returning the cooling water from the heater core 31 and the EGR cooler 30 to the engine 2.

[0025] The return passage 22C converges so as to merge the cooling water from the heater core 31 and the cooling water from the EGR cooler 30. The upstream ends of the feed passages 22A and 22B are connected to the engine 2 without passing through the thermostat 33. The downstream end of the return passage 22C is connected to the suction side of the water pump 32. Therefore, during the operation of the engine 2, the cooling water always circulates through the high-temperature cooling water circulation circuit 22 regardless of whether the thermostat 33 is closed or open.

[0026] The vehicle 1 is provided with a low-temperature cooling water circulation circuit 23. In the low-temperature cooling water circulation circuit 23, cooling water having a lower temperature than the cooling water circulating through the high-temperature cooling water circulation circuit 22 circulates. The oil cooler 4A is connected to the radiator 50 via the low-temperature cooling water circulation circuit 23. The radiator 50 cools the cooling water circulating through the low-temperature cooling water circulation circuit 23.

[0027] The low-temperature cooling water circulation circuit 23 has a feed passage 23A for sending cooling water from the oil cooler 4A to the radiator 50 and a return passage 23B for returning the cooling water from the radiator 50 to the oil cooler 4A. An electrically operated water pump (denoted as EWP in the figure) 37 and an inverter (denoted as INV in the figure) 5 are provided in the return passage 23B. The electric water pump 37 constitutes the second water pump in the present invention. The cooling water circulating through the low-temperature cooling water circulation circuit 23 cools the oil of the oil cooler 4A and the inverter 5.

[0028] Therefore, the cooling water circulates between the oil cooler 4A and the inverter 5 and the radiator 50 in the low-temperature cooling water circulation circuit 23. The cooling water circulating through the low-temperature cooling water circulation circuit 23 has a lower temperature than the cooling water circulating through the high-temperature cooling water circulation circuit 22.

[0029] The radiator 50 is formed with an inlet 51A to the radiator 50 of the engine cooling water circulation circuit 21 and an inlet 51B to the radiator 50 of the low-temperature cooling water circulation circuit 23.

[0030] The radiator 50 is formed with an outlet 52A of the radiator 50 for the engine cooling water circulation circuit 21 and an outlet 52B of the radiator 50 for the low-temperature cooling water circulation circuit 23.

[0031] The vehicle 1 is provided with a control unit 10. The control unit 10 is configured as an ECU (Electronic Control Unit) composed of a computer unit including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data and the like, an input port, and an output port.

[0032] In the ROM of the control unit 10, a program for causing the computer unit to function as the control unit 10 is stored together with various constants, various maps, and the like. The control unit 10 achieves the target operation by the CPU executing the program stored in the ROM with the RAM as the working area.

[0033] The control unit 10 switches the driving mode to at least either an engine driving mode in which the vehicle travels using the engine 2 as a driving power source or an EV driving mode in which the vehicle travels using the electric motor 4 as a driving power source without using the engine 2 as a driving power source. The engine driving mode includes a state in which the vehicle travels using the engine 2 as a driving power source and a state in which the vehicle travels using both the engine 2 and the electric motor 4 as driving power sources.

[0034] The vehicle 1 is provided with a cooling circuit switching unit 40. The cooling circuit switching unit 40 switches the supply state of the cooling water to the oil cooler 4A under the control of the control unit 10. The cooling circuit switching unit 40 is provided between the oil cooler 4A and the low-temperature cooling water circulation circuit 23.

[0035] The cooling circuit switching unit 40 is connected to the supply passage 22A to the heater core 31 of the high-temperature cooling water circulation circuit 22 through the communication passage 24A. The cooling circuit switching unit 40 is connected to the return passage 22C from the heater core 31 of the high-temperature cooling water circulation circuit 22 through the communication passage 24B.

[0036] Specifically, the cooling circuit switching unit 40 is provided with valves 41 and 42 for switching the path of the cooling water, and passages 43, 44, and 45 through which the cooling water passes. The passage 43 connects the cooling water outlet of the oil cooler 4A and the valve 42. The passage 44 connects the inverter 5 and the valves 41 and 42 via the return passage 23B. The passage 45 connects the cooling water inlet of the oil cooler 4A and the valve 41.

[0037] The cooling circuit switching unit 40 has a first state in which the cooling water of the low-temperature cooling water circulation circuit 23 is supplied to the oil cooler 4A, a second state in which the cooling water of the high-temperature cooling water circulation circuit 22 and the cooling water of the low-temperature cooling water circulation circuit 23 are not supplied to the oil cooler 4A, and a third state in which the cooling water of the high-temperature cooling water circulation circuit 22 is supplied to the oil cooler 4A.

[0038] In addition, the cooling circuit switching unit 40 has a fourth state in which the cooling water of the low-temperature cooling water circulation circuit 23 is supplied to the oil cooler 4A and the heater core 31. The cooling circuit switching unit 40 can be switched to any one of the supply states of the first state, the second state, the third state, or the fourth state.

[0039] In this way, the cooling circuit switching unit 40 has the first state, the third state, and the fourth state in a state where the cooling water is supplied to the oil cooler 4A from at least one of the high-temperature cooling water circulation circuit 22 or the low-temperature cooling water circulation circuit 23. The cooling circuit switching unit 40 has the second state in a state where the cooling water is not supplied to the oil cooler 4A.

[0040] As shown in FIG. 2, when the cooling circuit switching unit 40 is in the first state, the feed passage 23A and the return passage 23B of the low-temperature cooling water circulation circuit 23 communicate with the oil cooler 4A via the cooling circuit switching unit 40. Therefore, in the first state, the cooling water of the low-temperature cooling water circulation circuit 23 is supplied to the side of the oil cooler 4A.

[0041] As shown in FIG. 3, when the cooling circuit switching unit 40 is in the second state, the cooling circuit switching unit 40 disconnects the oil cooler 4A from the low-temperature cooling water circulation circuit 23. In the second state, the low-temperature cooling water circulation circuit 23 circulates through the inverter 5, the electric water pump 37, and the low-temperature part 50L of the radiator 50.

[0042] Therefore, in the second state, the cooling water of the low-temperature cooling water circulation circuit 23 is not supplied to the oil cooler 4A. Also, in the second state, since the communication passages 24A and 24B are closed by the valves 41 and 42, the cooling water of the high-temperature cooling water circulation circuit 22 is not supplied to the oil cooler 4A.

[0043] As shown in FIG. 4, when the cooling circuit switching unit 40 is in the third state, the cooling circuit switching unit 40 disconnects the oil cooler 4A from the low-temperature cooling water circulation circuit 23. In the third state, the low-temperature cooling water circulation circuit 23 circulates through the inverter 5, the electric water pump 37, and the low-temperature part 50L of the radiator 50.

[0044] Therefore, in the third state, the cooling water of the low-temperature cooling water circulation circuit 23 is not supplied to the oil cooler 4A. Also, in the third state, the passage 45 of the cooling circuit switching unit 40 and the feed passage 22A of the high-temperature cooling water circulation circuit 22 communicate with each other via the communication passage 24A, and the passage 43 of the cooling circuit switching unit 40 and the return passage 22C of the high-temperature cooling water circulation circuit 22 communicate with each other via the communication passage 24B. Therefore, the cooling water of the high-temperature cooling water circulation circuit 22 is supplied to the oil cooler 4A.

[0045] As shown in FIG. 6, when the cooling circuit switching unit 40 is in the fourth state, the feed passage 23A and the return passage 23B of the low-temperature cooling water circulation circuit 23 communicate with the oil cooler 4A via the cooling circuit switching unit 40.

[0046] Therefore, in the fourth state, the cooling water of the low-temperature cooling water circulation circuit 23 is supplied to the side of the oil cooler 4A. Also, in this fourth state, the cooling water of the low-temperature cooling water circulation circuit 23 is supplied to the heater core 31 through the communication passage 24A and returned from the heater core 31 through the communication passage 24B. For this reason, the cooling water of the low-temperature cooling water circulation circuit 23 is supplied to the oil cooler 4A and the heater core 31.

[0047] Here, the water pump 32 cannot circulate the cooling water when the engine 2 is stopped. Therefore, in the EV driving mode, since the engine 2 is stopped and the cooling water does not circulate in the high-temperature cooling water circulation circuit 22, the transmission oil cannot be cooled by the cooling water in the high-temperature cooling water circulation circuit 22. On the other hand, since the electric water pump 37 operates by electric power, it can be driven even in the EV driving mode. That is, even in the EV driving mode, it is possible to cool the transmission oil using the cooling water circulating in the low-temperature cooling water circulation circuit 23.

[0048] The control unit 10 controls the cooling circuit switching unit 40 based on the driving mode. Specifically, the control unit 10 controls the cooling circuit switching unit 40 based on the driving mode, the oil temperature of the transmission oil (hereinafter also referred to as oil temperature), and the water temperature of the engine.

[0049] FIG. 5 and FIG. 7 show the control states of the cooling circuit switching unit 40 with respect to the temperature state and the driving mode. FIG. 5 shows the control state when there is no heating requirement, and FIG. 7 shows the control state when there is a heating requirement. The heating requirement is a requirement to heat the passenger compartment with warm water passing through the heater core 31.

[0050] In FIGS. 5 and 7, TWc is a threshold value related to the engine water temperature, and is the lower limit water temperature at which the waste heat of engine 2 may be used for warming up transmission 3. TOc1 is a temperature allowable for cooling of motor 4, and is the upper limit oil temperature when attempting to further increase the oil temperature of transmission 3. TOc2 is the lower limit oil temperature of the oil temperature of transmission 3 when the temperature difference from the temperature of the cooling water in the low-temperature cooling water circulation circuit 23 is not allowable.

[0051] Based on FIG. 5, first, the case where the engine water temperature < TWc will be described. When the oil temperature of the transmission oil (denoted as transmission oil temperature in the figure) < TOc1, the second state is selected in both the engine running mode and the EV running mode. When the oil temperature ≥ TOc1 and the oil temperature < TOc2, the third state is selected in the engine running mode, and the first state is selected in the EV running mode. When the oil temperature ≥ TOc2, the third state is selected in the engine running mode, and it is selected to shift to the engine running mode and set to the third state in the EV running mode.

[0052] Next, the parts different from the case where the engine water temperature < TWc will be described for the case where the engine water temperature ≥ TWc. When the oil temperature < TOc1, the third state is selected in the engine running mode. In other cases, it is the same as the case where the engine water temperature < TWc in FIG. 5.

[0053] Based on FIG. 7, first, the case where the engine water temperature < TWc will be described. When the oil temperature of the transmission oil (denoted as transmission oil temperature in the figure) < TOc1, the second state is selected in both the engine running mode and the EV running mode. When the oil temperature ≥ TOc1 and the oil temperature < TOc2, the third state is selected in the engine running mode, and the fourth state is selected in the EV running mode. When the oil temperature ≥ TOc2, the third state is selected in the engine running mode, and it is selected to shift to the engine running mode and set to the third state in the EV running mode.

[0054] Next, for the case where the engine coolant temperature ≧ TWc, the parts different from the case where the engine coolant temperature < TWc will be described. When the oil temperature < TOc1, the third state is selected in the engine running mode. In other cases, it is the same as the case where the engine coolant temperature < TWc in FIG. 7.

[0055] Here, when the heat dissipation performance of the low-temperature part 50L of the radiator 50, which is the radiator of the low-temperature coolant circulation circuit 23, is reduced, and when the oil temperature of the transmission oil is TOc2 or higher, cooling the transmission oil in the low-temperature coolant circulation circuit 23 will exceed the management temperature of the inverter 5. The allowable temperature of the high-temperature coolant circulation circuit 22 is higher than the allowable temperature of the low-temperature coolant circulation circuit 23. Therefore, when the oil temperature of the transmission oil is TOc2 or higher, it is desirable to be able to cool the transmission oil by the high-temperature coolant circulation circuit 22.

[0056] Therefore, when the current running mode is the EV running mode and the oil temperature of the transmission oil is TOc2 or higher as the first threshold value, the control unit 10 controls the cooling circuit switching unit 40 to shift to the engine running mode and switch to the third state.

[0057] When there is a heating request, the current running mode is the EV running mode, the oil temperature is less than TOc2, and the oil temperature is TOc1 or higher as the second threshold value lower than TOc2, the control unit 10 controls the cooling circuit switching unit 40 to switch to the fourth state.

[0058] As described above, the vehicle cooling system of this embodiment includes a cooling circuit switching unit 40 that switches the supply state of the cooling water to the oil cooler 4A that cools the transmission oil of the transmission 3, and a control unit 10 that controls the cooling circuit switching unit 40 based on the running mode.

[0059] As a result, since the cooling circuit switching unit 40 is controlled based on the driving mode, cooling water can be supplied from at least one of the low-temperature cooling water circulation circuit 23 or the high-temperature cooling water circulation circuit 22 to the oil cooler 4A according to the driving mode. Therefore, the transmission 3 incorporating the electric motor 4 can be appropriately cooled.

[0060] Also, in the vehicle cooling system of the present embodiment, the control unit 10 controls the cooling circuit switching unit 40 based on the driving mode, the oil temperature of the transmission oil, and the water temperature of the engine.

[0061] Thereby, in order to control the cooling circuit switching unit 40 that switches the cooling circuit for cooling the transmission oil based on the driving mode, the oil temperature of the transmission oil, and the engine water temperature, the transmission 3 incorporating the electric motor can be appropriately cooled.

[0062] Also, in the vehicle cooling system of the present embodiment, the cooling circuit switching unit 40 can be switched to any one of a first state in which the cooling water of the low-temperature cooling water circulation circuit 23 is supplied to the oil cooler 4A, a second state in which the cooling water of the high-temperature cooling water circulation circuit 22 and the cooling water of the low-temperature cooling water circulation circuit 23 are not supplied to the oil cooler 4A, and a third state in which the cooling water of the high-temperature cooling water circulation circuit 22 is supplied to the oil cooler 4A.

[0063] As a result, when the temperature of the transmission oil is low in the EV driving mode, the cooling circuit switching unit 40 is set to the second state, and the supply of the cooling water for cooling the transmission oil from the low-temperature cooling water circulation circuit 23 is stopped, so that the influence of the management temperature of the inverter 5 can be avoided and the transmission 3 can be prevented from being excessively cooled. Therefore, the deterioration of the transmission efficiency of the transmission 3 can be suppressed.

[0064] Also, even when the water temperature of the engine 2 is low and the oil temperature of the transmission oil is low in the engine running mode, the cooling circuit switching unit 40 is set to the second state, and the supply of the cooling water for cooling the transmission oil from the low-temperature cooling water circulation circuit 23 is stopped, so that the transmission 3 can be prevented from being cooled. Therefore, it is possible to suppress the deterioration of the transmission efficiency of the transmission 3.

[0065] Further, in the vehicle cooling system of the present embodiment, when the current running mode is the EV running mode and the oil temperature of the transmission oil is equal to or higher than TOc2 as the first threshold value, the control unit 10 controls the cooling circuit switching unit 40 to shift to the engine running mode and switch to the third state.

[0066] Thereby, even when the heat dissipation performance of the low-temperature part 50L of the radiator 50, which is the radiator of the low-temperature cooling water circulation circuit 23, is reduced, the management temperature of the inverter when the oil temperature of the transmission oil is high can be satisfied.

[0067] Further, in the vehicle cooling system of the present embodiment, the high-temperature cooling water circulation circuit 22 includes a heater core 31 that heats the vehicle interior by heat exchange with the cooling water. The cooling circuit switching unit 40 has a fourth state in which the cooling water of the low-temperature cooling water circulation circuit 23 is supplied to the oil cooler 4A and the heater core 31. When there is a heating request, the current running mode is the EV running mode, the oil temperature is lower than TOc2 as the first threshold value, and equal to or higher than TOc1 as the second threshold value lower than TOc2, the control unit 10 controls the cooling circuit switching unit 40 to switch to the fourth state.

[0068] As a result, even in the EV driving mode where the engine 2 cannot be used as a heat source, warm water heated by the oil cooler 4A can be supplied to the heater core 31 to heat the passenger compartment on condition that the oil temperature is lower than TOc2 as the first threshold value and equal to or higher than TOc1 as the second threshold value lower than TOc2. For this reason, it is not necessary to provide an electric heater such as a PTC heater or to operate the engine 2 for heating the passenger compartment, so that the fuel efficiency can be improved.

[0069] Although embodiments of the present invention have been disclosed, it is obvious that changes can be made by those skilled in the art without departing from the scope of the present invention. It is intended that all such modifications and equivalents be included in the following claims.

Explanation of Signs

[0070] 1...Vehicle 2...Engine 3...Transmission 4...Electric motor 4A...Oil cooler 5...Inverter 10...Control unit 22...High-temperature cooling water circulation circuit 23...Low-temperature cooling water circulation circuit 31...Heater core 32...Water pump (first water pump) 37...Electric water pump (second water pump) 40...Cooling circuit switching unit TOc1...Second threshold value TOc2...First threshold value

Claims

1. Comprising a transmission with a built-in electric motor, Mounted on a hybrid vehicle having at least an engine running mode in which the vehicle runs using the engine as a driving force source and an EV running mode in which the vehicle runs using the electric motor as a driving force source without using the engine as a driving force source, Comprising a first water pump that operates with the engine as a driving force source, and a high-temperature cooling water circulation circuit through which cooling water that at least cools the engine circulates, Comprising a second water pump that operates electrically, and a low-temperature cooling water circulation circuit through which cooling water that is lower in temperature than the cooling water circulating through the high-temperature cooling water circulation circuit circulates, and that at least cools an inverter electrically connected to the electric motor, A vehicle cooling system comprising a cooling circuit switching unit that switches the supply state of cooling water to an oil cooler that cools the transmission oil of the transmission, And a control unit that controls the cooling circuit switching unit based on the running mode,

2. The vehicle cooling system according to claim 1, wherein the control unit controls the cooling circuit switching unit based on the running mode, the oil temperature of the transmission oil, and the water temperature of the engine.

3. The cooling circuit switching unit is In a first state in which the cooling water of the low-temperature cooling water circulation circuit is supplied to the oil cooler, In a second state in which the cooling water of the high-temperature cooling water circulation circuit and the cooling water of the low-temperature cooling water circulation circuit are not supplied to the oil cooler, The vehicle cooling system according to claim 2, characterized in that it can be switched to any one of a third state in which the cooling water of the high-temperature cooling water circulation circuit is supplied to the oil cooler.

4. When the current running mode is the EV running mode and the oil temperature of the transmission oil is equal to or higher than a first threshold value, the control unit shifts to the engine running mode and controls the cooling circuit switching unit to switch to the third state, according to the vehicle cooling system of claim 3.

5. The high-temperature cooling water circulation circuit comprises a heater core that heats the vehicle interior by heat exchange with the cooling water, The cooling circuit switching unit has a fourth state in which the cooling water of the low-temperature cooling water circulation circuit is supplied to the oil cooler and the heater core, The control unit controls the cooling circuit switching unit to switch to the fourth state when there is a heating demand, the current driving mode is the EV driving mode, the oil temperature is lower than the first threshold value and is equal to or higher than a second threshold value lower than the first threshold value, according to the vehicle cooling system of claim 4.

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