Cooling system control method and cooling system control device

Abstract

To provide a cooling system that enables cooling of both an internal combustion engine and an inverter.SOLUTION: During an operation of an internal combustion engine 2, when a temperature of cooling water in a first passage 3 detected by a first water temperature sensor 10 is higher than a first passage side first threshold value and a temperature of cooling water in a second passage 5 detected by a second water temperature sensor 18 is equal to or lower than a second passage side first threshold value, a cooling system 31 controls a first control valve 4 so that the cooling water in the first passage 3 that has exchanged heat with the internal combustion engine 2 flows into the second passage 5. Thus the cooling system 31 can increase a temperature of a battery 16 by using the cooling water that has received heat from the internal combustion engine 2 while suppressing deterioration of friction of the internal combustion engine 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for controlling a cooling system and a control device for a cooling system. [Background technology]

[0002] For example, Patent Document 1 discloses a cooling circuit in a hybrid vehicle having two drive sources, an engine and a motor, in which the engine and an inverter that converts direct current to alternating current and supplies it to the motor are circulated by a common water pump and cooled by coolant cooled by a common radiator.

[0003] In the hybrid vehicle of Patent Document 1, the engine and inverter are cooled under the same conditions (common coolant), so ultra-low viscosity oil is used as the engine lubricant, ensuring sufficient lubrication and allowing the warm-up to be completed at a lower engine water temperature than in a typical engine.

[0004] This is because in Patent Document 1, the engine water temperature during driving is set lower than that of a normal engine, thereby bringing the cooling water temperature closer to the optimum temperature for the inverter and integrating the engine cooling circuit and the inverter cooling circuit. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-85024 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in Patent Document 1, in order to suppress deterioration of engine friction, it is necessary to use a special oil that has a lower viscosity at low temperatures than general engine oil, which may increase maintenance costs.

[0007] That is, there is room for further improvement in integrating the cooling circuits for the engine (internal combustion engine) and the inverter to cool the engine (internal combustion engine) and the inverter. [Means for solving the problem]

[0008] The cooling system of the present invention includes a first passage through which a refrigerant that has exchanged heat with an internal combustion engine can circulate, a second passage connected to the first passage and in which a generator, a drive motor, and a battery are arranged, and a control valve capable of controlling the flow of the refrigerant so that the refrigerant that has exchanged heat with the internal combustion engine does not flow into the second passage, and when, during operation of the internal combustion engine, the temperature of the refrigerant in the first passage is higher than a predetermined first threshold value on the first passage side and the temperature of the refrigerant in the second passage is equal to or lower than a predetermined first threshold value on the second passage side, the control valve is controlled so that the refrigerant that has exchanged heat with the internal combustion engine flows into the second passage. [Effects of the Invention]

[0009] In the cooling system of the present invention, when predetermined conditions are met (refrigerant temperature in the first passage > first passage side first threshold value, and refrigerant temperature in the second passage ≦ second passage side first threshold value), the refrigerant circulating in the first passage flows into the second passage, thereby making it possible to heat the battery with the refrigerant heated by the internal combustion engine while suppressing deterioration of friction in the internal combustion engine. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an explanatory diagram showing a schematic overview of a cooling system according to a first embodiment of the present invention; [Figure 2] 10 is a flowchart showing the flow of control relating to cooling water in the cooling system of the second embodiment. [Figure 3] 10 is a flowchart showing the flow of control related to lubricating oil in the cooling system of the second embodiment. [Figure 4] FIG. 10 is an explanatory diagram showing a schematic overview of a cooling system according to a second embodiment of the present invention. [Figure 5]10 is a flowchart showing the flow of control relating to cooling water in the cooling system of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described in detail with reference to the accompanying drawings. Figure 1 is an explanatory diagram showing a schematic overview of a cooling system 1 according to a first embodiment of the present invention.

[0012] The cooling system 1 is applied to a hybrid vehicle, and is capable of cooling an internal combustion engine 2, a drive motor (not shown) that drives drive wheels (not shown), and the like, with cooling water as a refrigerant.

[0013] The cooling system 1 has a first passage 3 through which cooling water that has exchanged heat with the internal combustion engine 2 can circulate, a second passage 5 connected to the first passage 3 via a first control valve 4, a third passage 6 connected to the first passage 3 in parallel with the second passage 5, and an oil passage 7 through which lubricating oil (oil) for the internal combustion engine 2 flows.

[0014] The first passage 3 includes a water jacket 8 of the internal combustion engine 2. A first water pump 9 that pumps coolant, a first water temperature sensor 10 that detects the temperature of the coolant, and a first radiator 11 that can exchange heat (cool) between the outside air and the coolant are arranged in the first passage 3. The first passage 3 is a continuous annular flow path for the coolant, and allows the coolant discharged from the first water pump 9 to circulate.

[0015] The first water pump 9 is a mechanical pump that is driven by rotation of the crankshaft (not shown) of the internal combustion engine 2. Note that the first water pump 9 may also be an electric pump that is driven by commands from a control unit 12, which will be described later, for example.

[0016] The first water temperature sensor 10 detects the temperature of the coolant after flowing through the water jacket 8 formed in the cylinder block or cylinder head of the internal combustion engine 2, and is disposed on the internal combustion engine outlet side of the first passage 3. In other words, the first water temperature sensor 10 detects the coolant temperature (internal combustion engine outlet water temperature) on the internal combustion engine outlet side (after heat exchange with the internal combustion engine 2). The first water temperature sensor 10 is located downstream of the internal combustion engine 2 and upstream of the first radiator 11. A detection signal from the first water temperature sensor 10 is input to a control unit 12 serving as a control section.

[0017] Here, the terms "downstream side" and "upstream side" in this specification are based on the flow direction of the cooling water or lubricating oil (described later). In Figure 1, the cooling water in the first passage 3 flows counterclockwise (leftward) as shown by the arrow.

[0018] The first radiator 11 can be prevented from receiving coolant by a first bypass valve 13. A first bypass passage 14 that bypasses the first radiator 11 is connected to the first passage 3 via the first bypass valve 13. The first bypass passage 14 has one downstream end connected to the first passage 3 via the first bypass valve 13 at a position downstream of the first radiator 11, and the other upstream end connected to the first passage 3 at a position upstream of the first radiator 11. Note that the first bypass passage 14 may also have the other upstream end connected to the first passage 3 via the first bypass valve 13 at a position upstream of the first radiator 11, and one downstream end connected to the first passage 3 at a position downstream of the first radiator 11.

[0019] The first bypass valve 13 is, for example, a three-way electromagnetic valve, and is controlled by commands from the control unit 12. Note that the first bypass valve 13 may not be a three-way valve, but may be a solenoid valve that opens and closes one end or the other end of the first bypass passage 14.

[0020] By controlling the first bypass valve 13, the cooling system 1 is able to allow the coolant to flow through the first bypass passage 14 and prevent it from flowing into the first radiator 11. That is, the first bypass valve 13 is able to open the first passage 3 at a connection portion between one end of the first bypass passage 14 and the first passage 3 so that the coolant that has passed through the first radiator 11 flows downstream, and close the first bypass passage 14 so that the coolant that has passed through the first bypass passage 14 does not flow downstream. Furthermore, the first bypass valve 13 is able to close the first passage 3 at a connection portion between one end of the first bypass passage 14 and the first passage 3 so that the coolant that has passed through the first radiator 11 does not flow downstream, and open the first bypass passage 14 so that the coolant that has passed through the first bypass passage 14 flows downstream.

[0021] A powertrain 15 of the hybrid vehicle, a battery 16, a heater core 17 that uses the coolant as a heat source, and a second water temperature sensor 18 that detects the temperature of the coolant are arranged in the second passage 5. One downstream end of the second passage 5 is connected to the first passage 3 via the first control valve 4 at a position downstream of the first water temperature sensor 10 and upstream of the first radiator 11. The other upstream end of the second passage 5 is connected to the first passage 3 at a position downstream of the first water temperature sensor 10 and upstream of the first radiator 11. In FIG. 1, the coolant in the second passage 5 flows counterclockwise (leftward) as shown by the arrow.

[0022] The powertrain 15 has a generator (not shown) driven by the internal combustion engine 2, the drive motor that drives the drive wheels, and an inverter that supplies power from the battery 16 and power generated by the generator to the drive motor.

[0023] The generator is, for example, a synchronous motor using a permanent magnet in the rotor. The generator converts the rotational energy generated in the internal combustion engine 2 into electrical energy and supplies it to the battery 16 and the drive motor via the inverter. The generator may also be used as a starter motor when starting the internal combustion engine 2.

[0024] The drive motor is, for example, a synchronous motor with a permanent magnet in the rotor. The drive motor is the drive source for the hybrid vehicle and is driven by AC power from the inverter. The drive motor also functions as a generator when the hybrid vehicle decelerates. In other words, the drive motor can charge battery 16 via the inverter with regenerative energy generated during vehicle deceleration.

[0025] The inverter is a power conversion circuit that converts the power generated by the generator and the drive motor into DC power and supplies it to the battery 16. The inverter is also a power conversion circuit that converts the DC power output from the battery 16 into AC power and supplies it to the drive motor. The inverter supplies the power generated by the generator and the power from the battery 16 to the drive motor.

[0026] The battery 16 is a secondary battery that can be charged with electric power generated by the generator and the drive motor as DC power. The battery 16 supplies the charged electric power to the drive motor via the inverter. The battery 16 is disposed in series with the powertrain 15 on the upstream side of the powertrain 15 in the second passage 5.

[0027] The heater core 17 is disposed in parallel with the battery 16 and the power train 15 in the second passage 5. Coolant branched from the upstream side of the battery 16 flows into the heater core 17. The coolant that has passed through the heater core 17 merges with the coolant that has passed through the power train 15.

[0028] The second water temperature sensor 18 detects the temperature of the coolant after flowing through the powertrain 15, and is disposed on the powertrain outlet side of the second passage 5. In other words, the second water temperature sensor 18 detects the coolant temperature (powertrain outlet water temperature) on the powertrain outlet side (after heat exchange with the battery 16 and powertrain 15). The second water temperature sensor 18 is located downstream of the powertrain 15, upstream of the position where the coolant that has passed through the heater core 17 joins. A detection signal from the second water temperature sensor 18 is input to the control unit 12.

[0029] The cooling system 1 is capable of causing the coolant to flow from the first passage 3 to the second passage 5 by controlling the first control valve 4. That is, the first control valve 4 is capable of opening one end of the second passage 5 at a connection portion between the first passage 3 and a downstream end of the second passage 5 so that the coolant that has passed through the second passage 5 flows into the first passage 3, and opening the first passage 3 so as not to obstruct the flow in the first passage 3. Furthermore, the first control valve 4 is capable of closing one end of the second passage 5 at a connection portion between the first passage 3 and a downstream end of the second passage 5 so that the coolant that has passed through the second passage 5 does not flow into the first passage 3, and opening the first passage 3 so as not to obstruct the flow in the first passage 3.

[0030] The first control valve 4 corresponds to a control valve and is controlled by commands from the control unit 12. The first control valve 4 is, for example, a three-way electromagnetic valve. Note that the first control valve 4 may not be a three-way valve, but may be a solenoid valve that opens and closes the downstream end of the second passage 5, or the like.

[0031] An oil cooler 19 that exchanges heat with the oil passage 7 through which lubricating oil (oil) of the internal combustion engine 2 flows is disposed in the third passage 6, and a second bypass valve 20 that controls the inflow of cooling water to the oil cooler 19. In Fig. 1, the cooling water in the third passage 6 flows clockwise (to the right) as shown by the arrow.

[0032] The third passage 6 has one downstream end connected to the first passage 3 at a position downstream of the first bypass valve 13 and upstream of the first water pump 9. The third passage 6 has the other upstream end connected to the first passage 3 at a position downstream of the first water temperature sensor 10 and upstream of the first control valve 4.

[0033] The oil cooler 19 performs heat exchange (for example, cooling) between the cooling water flowing through the third passage 6 and the lubricating oil in the oil passage .

[0034] The second bypass valve 20 is disposed upstream of the oil cooler 19. The second bypass valve 20 is a solenoid valve, and is controlled by commands from the control unit 12. The second bypass valve 20 may also be disposed downstream of the oil cooler 19.

[0035] In the cooling system 1, by closing the second bypass valve 20, the cooling water can be prevented from flowing into the third passage 6, and the cooling water can be prevented from flowing into the oil cooler 19.

[0036] In the cooling system 1 of the first embodiment, the first water pump 9 disposed in the first passage 3 circulates the cooling water in the second passage 5 and the cooling water in the third passage 6 .

[0037] The oil passage 7 is a passage independent from the first passage 3, the second passage 5, and the third passage 6. The oil passage 7 is formed near the cylinder 3a of the internal combustion engine 2 and includes an oil jacket 21. The oil passage 7 is provided with the above-mentioned oil cooler 19, an oil pump 22 that pumps lubricating oil, and an oil temperature sensor 23 that detects the temperature of the lubricating oil. In FIG. 1, the lubricating oil in the oil passage 7 flows clockwise (to the right) as shown by the arrow.

[0038] The oil jacket 21 is a passage through which lubricating oil supplied to each part of the internal combustion engine 2 flows, and is formed, for example, in a cylinder block (not shown) of the internal combustion engine 2. The oil jacket 21 is located on the outer periphery of the cylinder 2a of the internal combustion engine 2, and is formed so that heat exchange (heat reception) can occur between the combustion gas (burned gas) in the cylinder 2a and the lubricating oil flowing inside via the metal on the outer periphery of the cylinder bore. More specifically, the oil jacket 21 is formed so as to be located closer to the cylinder head of the internal combustion engine 2 than the bottom dead center position of the piston 24 of the internal combustion engine 2. In other words, the oil passage 7 is formed to have a portion (oil jacket 21) where heat exchange (heat reception) can occur between the combustion gas (burned gas) in the cylinder 2a and the lubricating oil flowing inside via the metal on the outer periphery of the cylinder bore.

[0039] Therefore, the cooling system 1 can maintain the lubricating oil in the oil passage 7 at a high temperature even when the temperature of the coolant in the first passage 3 is kept low. Also, the cooling system 1 can accelerate the temperature rise of the lubricating oil in the internal combustion engine 2, thereby accelerating the reduction in friction in the internal combustion engine 2.

[0040] The oil pump 22 is a mechanical pump that is driven by rotation of a crankshaft (not shown) of the internal combustion engine 2. Note that the oil pump 22 may be an electric pump that is driven by a command from the control unit 12, for example.

[0041] The oil temperature sensor 23 detects the temperature of the lubricating oil after it has flowed through the oil jacket 21, and is disposed on the oil jacket outlet side of the third passage 6. In other words, the oil temperature sensor 23 detects the oil temperature on the oil jacket outlet side (oil temperature on the oil jacket outlet side). The oil temperature sensor 23 is located downstream of the oil jacket 21 and upstream of the oil cooler 19. A detection signal from the oil temperature sensor 23 is input to the control unit 12.

[0042] In the cooling system 1 of the first embodiment described above, by controlling the first control valve 4, it is possible to cause the cooling water circulating in the first passage 3 to flow into the second passage 5. That is, the cooling system 1 can circulate the cooling water in the first passage 3 while not circulating the cooling water in the second passage 5. Furthermore, the cooling system 1 can circulate the cooling water in the first passage 3 while not circulating the cooling water in the second passage 5.

[0043] Specifically, during operation of the internal combustion engine 2, when the temperature of the coolant in the first passage 3 detected by the first water temperature sensor 10 is higher than a preset first threshold value on the first passage side (e.g., 60°C) and the temperature of the coolant detected by the second water temperature sensor 18 is equal to or lower than a preset first threshold value on the second passage side (e.g., 30°C), the cooling system 1 controls the first control valve 4 so that the coolant in the first passage 3 that has exchanged heat with the internal combustion engine 2 flows into the second passage 5. At this time, the first control valve 4 is controlled to open one end of the second passage 5 at a connection portion between the first passage 3 and a downstream end that is one end of the second passage 5 so that the coolant that has passed through the second passage 5 flows into the first passage 3, and to open the first passage 3 so as not to obstruct the flow in the first passage 3. At this time, the first bypass valve 13 is controlled so that the coolant flows into, for example, the first radiator 11.

[0044] The first passage-side first threshold value is, for example, the lower limit of the coolant temperature required to minimize the effect on particulate matter in the exhaust and combustion, and is, for example, 60°C.

[0045] The second passage-side first threshold value is, for example, the lower limit of the coolant temperature required to ensure a desired battery output characteristic, and is, for example, 30°C.

[0046] In the cooling system 1, when predetermined conditions are met (the cooling water temperature in the first passage 3 > the first threshold value on the first passage side, and the cooling water temperature in the second passage ≦ the first threshold value on the second passage side), the cooling water circulating in the first passage 3 flows into the second passage 5, so that the battery 16 can be heated by the cooling water heated by the internal combustion engine 2 while suppressing deterioration of friction in the internal combustion engine 2.

[0047] Furthermore, when the temperature of the battery 16 is low, the cooling system 1 can use the heat of the internal combustion engine 2 to raise the temperature of the battery 16. Therefore, the battery 16 can suppress a decrease in output due to a drop in temperature.

[0048] Furthermore, when the temperature of the coolant in the first passage 3 detected by the first water temperature sensor 10 is equal to or lower than a first-passage-side first threshold value (e.g., 60°C) and the temperature of the coolant in the second passage 5 detected by the second water temperature sensor 18 is equal to or lower than a second-passage-side first threshold value (e.g., 30°C), the cooling system 1 controls the first control valve 4 so that the coolant in the first passage 3 that has exchanged heat with the internal combustion engine 2 does not flow into the second passage 5. At this time, the first control valve 4 is controlled at a connection portion between the first passage 3 and a downstream end, which is one end of the second passage 5, so as to close one end of the second passage 5 so as to prevent the coolant that has passed through the second passage 5 from flowing into the first passage 3, and to open the first passage 3 so as not to obstruct the flow in the first passage 3. At this time, the first bypass valve 13 is controlled so as not to allow the coolant to flow into, for example, the first radiator 11.

[0049] When predetermined conditions (coolant temperature in the first passage 3≦first passage side first threshold value and coolant temperature in the second passage 5≦second passage side first threshold value) are met, the cooling system 1 prevents the coolant circulating in the first passage 3 from flowing into the second passage 5, thereby enabling the internal combustion engine 2 to be warmed up early.

[0050] Furthermore, when the temperature of the coolant in the second passage 5 detected by the second water temperature sensor 18 is higher than a predetermined second-passage-side second threshold value (e.g., 60°C) that is higher than a second-passage-side first threshold value (e.g., 30°C), the cooling system 1 controls the first control valve 4 so that the coolant in the first passage 3 that has exchanged heat with the internal combustion engine 2 flows into the second passage 5. At this time, the first control valve 4 is controlled to open one end of the second passage 5 at a connection portion between the first passage 3 and a downstream end that is one end of the second passage 5 so that the coolant that has passed through the second passage 5 flows into the first passage 3, and to open the first passage 3 so as not to obstruct the flow in the first passage 3. At this time, the first bypass valve 13 is controlled so that the coolant flows into, for example, the first radiator 11.

[0051] The second passage-side second threshold value is, for example, an upper limit value of the temperature of the battery 16 (coolant) required to suppress deterioration of the battery 16.

[0052] The cooling system 1 is capable of circulating coolant to cool the battery 16 when the battery 16 is at a high temperature, thereby suppressing thermal degradation of the battery 16.

[0053] Furthermore, when the temperature of the coolant in the second passage 5 detected by the second water temperature sensor 18 is higher than a first second-passage-side threshold value (e.g., 30°C) and is equal to or lower than a second second-passage-side threshold value (e.g., 60°C) during operation of the internal combustion engine 2, the cooling system 1 controls the first control valve 4 so that the coolant in the first passage 3 that has exchanged heat with the internal combustion engine 2 does not flow into the second passage 5. At this time, the first control valve 4 is controlled to close one end of the second passage 5 at a connection portion between the first passage 3 and a downstream end that is one end of the second passage 5 so that the coolant that has passed through the second passage 5 does not flow into the first passage 3, and to open the first passage 3 so as not to obstruct the flow in the first passage 3. At this time, the first bypass valve 13 is controlled so that the coolant flows into, for example, the first radiator 11.

[0054] When the battery 16 is not at a high temperature, the cooling system 1 can circulate the coolant in the first passage 3 to cool the internal combustion engine 2. Therefore, the cooling system 1 can set the temperature of the coolant in the first passage 3 to a temperature suitable for the internal combustion engine 2 by controlling the first bypass valve 13, for example, and can efficiently maintain the temperature of the internal combustion engine 2 at an appropriate level.

[0055] During operation of the internal combustion engine 2, when the temperature of the coolant in the first passage 3 detected by the first water temperature sensor 10 is higher than the first-passage-side first threshold value and the temperature of the coolant in the second passage 5 detected by the second water temperature sensor 18 is equal to or lower than the second-passage-side first threshold value, the cooling system 1 controls the first control valve 4 so that the coolant that has exchanged heat with the internal combustion engine 2 flows into the heater core 17. At this time, the first control valve 4 is controlled to open one end of the second passage 5 at a connection portion between the first passage 3 and a downstream end of the second passage 5 so that the coolant that has passed through the second passage 5 flows into the first passage 3, and to open the first passage 3 so as not to obstruct the flow in the first passage 3. At this time, the first bypass valve 13 is controlled so as not to allow the coolant to flow into the first radiator 11, for example.

[0056] This allows the cooling system 1 to reduce power consumption for heating the vehicle interior.

[0057] When the temperature of the lubricating oil (oil) in the oil passage 7 detected by the oil temperature sensor 23 becomes higher than a preset oil temperature threshold, the cooling system 1 cools the lubricating oil in the oil passage 7 using the oil cooler 19. At this time, the second bypass valve 20 is controlled (opened) so that the cooling water flows from the first passage 3 into the oil cooler 19.

[0058] This enables the cooling system 1 to control the temperature of the lubricating oil to an appropriate temperature.

[0059] FIG. 2 is a flowchart showing the flow of control relating to the cooling water in the cooling system 1 of the first embodiment.

[0060] In step S1, it is determined whether the coolant temperature on the internal combustion engine outlet side of the first passage 3 (after heat exchange with the internal combustion engine 2) is higher than the first passage-side first threshold value. In step S1, if the internal combustion engine outlet water temperature is higher than the first passage-side first threshold value, the process proceeds to step S2. In step S1, if the internal combustion engine outlet water temperature is equal to or lower than the first passage-side first threshold value, the process proceeds to step S10.

[0061] In step S2, it is determined whether the coolant temperature on the powertrain outlet side of the second passage 5 (after heat exchange with the battery 16 and the powertrain 15) is higher than the second passage first threshold value. In step S2, if the powertrain outlet water temperature is higher than the second passage first threshold value, the process proceeds to step S3. In step S2, if the powertrain outlet water temperature is equal to or lower than the second passage first threshold value, the process proceeds to step S8.

[0062] In step S3, it is determined whether the coolant temperature on the powertrain outlet side of the second passage 5 (after heat exchange with the battery 16 and the powertrain 15) is higher than the second passage-side second threshold value. In step S3, if the powertrain outlet water temperature is higher than the second passage-side second threshold value, the process proceeds to step S4. In step S3, if the powertrain outlet water temperature is equal to or lower than the second passage-side second threshold value, the process proceeds to step S6.

[0063] In step S4, the first control valve 4 is controlled so that the cooling water in the first passage 3 that has exchanged heat with the internal combustion engine 2 flows into the second passage 5. That is, in step S4, the first control valve 4 is set so that the cooling water circulates through the first passage 3 and the second passage 5.

[0064] In step S5, the first bypass valve 13 is controlled so as to circulate the coolant cooled by the first radiator 11. That is, in step S5, the first bypass valve 13 is set so that the coolant flows into the first radiator 11.

[0065] In step S6, the first control valve 4 is controlled so that the cooling water in the first passage 3 that has exchanged heat with the internal combustion engine 2 does not flow into the second passage 5. That is, in step S6, the first control valve 4 is set so that the cooling water circulates through the first passage 3.

[0066] In step S7, the first bypass valve 13 is controlled so as to circulate the coolant cooled in the first radiator 11. That is, in step S7, the first bypass valve 13 is set so that the coolant flows into the first radiator 11.

[0067] In step S8, the first control valve 4 is controlled so that the cooling water in the first passage 3 that has exchanged heat with the internal combustion engine 2 flows into the second passage 5. That is, in step S8, the first control valve 4 is set so that the cooling water circulates through the first passage 3 and the second passage 5.

[0068] In step S9, the first bypass valve 13 is controlled so as to circulate the coolant cooled by the first radiator 11. That is, in step S9, the first bypass valve 13 is set so that the coolant flows into the first radiator 11.

[0069] In step S10, it is determined whether the coolant temperature on the powertrain outlet side of the second passage 5 (after heat exchange with the battery 16 and the powertrain 15) is higher than the second passage first threshold value. In step S10, if the powertrain outlet water temperature is higher than the second passage first threshold value, the process proceeds to step S11. In step S10, if the powertrain outlet water temperature is equal to or lower than the second passage first threshold value, the process proceeds to step S16.

[0070] In a hybrid vehicle, if the battery 16 has a power reserve and the internal combustion engine 2 is stopped while the vehicle is running, the water temperature at the outlet of the internal combustion engine drops and the water temperature at the outlet of the power train rises. This case is assumed when proceeding from step S1 to step S10.

[0071] In step S11, it is determined whether the coolant temperature on the powertrain outlet side of the second passage 5 (after heat exchange with the battery 16 and the powertrain 15) is higher than the second passage-side second threshold value. In step S11, if the powertrain outlet water temperature is higher than the second passage-side second threshold value, the process proceeds to step S12. In step S11, if the powertrain outlet water temperature is equal to or lower than the second passage-side second threshold value, the process proceeds to step S14.

[0072] In step S12, the first control valve 4 is controlled so that the cooling water in the first passage 3 that has exchanged heat with the internal combustion engine 2 flows into the second passage 5. That is, in step S12, the first control valve 4 is set so that the cooling water circulates through the first passage 3 and the second passage 5.

[0073] In step S13, the first bypass valve 13 is controlled so as to circulate the coolant cooled by the first radiator 11. That is, in step S13, the first bypass valve 13 is set so that the coolant flows into the first radiator 11.

[0074] In steps S14 and S16, the first control valve 4 is controlled so that the cooling water in the first passage 3 that has exchanged heat with the internal combustion engine 2 does not flow into the second passage 5. That is, in steps S14 and S16, the first control valve 4 is set so that the cooling water circulates through the first passage 3.

[0075] In steps S15 and S17, the first bypass valve 13 is controlled so as not to circulate the coolant cooled by the first radiator 11. That is, in steps S15 and S17, the first bypass valve 13 is set so as not to allow the coolant to flow into the first radiator 11.

[0076] FIG. 3 is a flowchart showing the flow of control relating to the lubricating oil in the cooling system 1 of the first embodiment.

[0077] In step S21, it is determined whether the temperature of the lubricating oil (oil) in the oil passage 7 is higher than the oil temperature threshold. In step S21, if the temperature of the lubricating oil is higher than the oil temperature threshold, the process proceeds to step S22. In step S21, if the temperature of the lubricating oil is equal to or lower than the oil temperature threshold, the process proceeds to step S23.

[0078] In step S22, the second bypass valve 20 is opened, and in step S23, the second bypass valve 20 is closed.

[0079] Another embodiment of the present invention will be described below, in which the same components as those in the above-described embodiment are designated by the same reference numerals and redundant description will be omitted.

[0080] A second embodiment of the present invention will be described with reference to Figures 4 and 5. Figure 4 is an explanatory diagram that schematically shows an overview of a cooling system 31 of the second embodiment to which the present invention is applied. The cooling system 31 of the second embodiment has substantially the same configuration as the cooling system 1 of the first embodiment described above, but as shown in Figure 4, a second water pump 32 and a second radiator 33 are arranged in a second passage 5, the other end of the second passage 5 is connected to the first passage 3 via a second control valve 34, and a second bypass passage 35 and a third bypass passage 36 are connected to the second passage 5.

[0081] In Fig. 4, the cooling water in the first passage 3 flows counterclockwise (left-handed) as shown by the arrows. In Fig. 4, the cooling water in the second passage 5 flows counterclockwise (left-handed) as shown by the arrows. In Fig. 4, the cooling water in the third passage 6 flows clockwise (right-handed) as shown by the arrows. In Fig. 4, the lubricating oil in the oil passage 7 flows clockwise (right-handed) as shown by the arrows.

[0082] The second water pump 32 is a mechanical pump that is driven by rotation of the crankshaft (not shown) of the internal combustion engine 2. The second water pump 32 may be an electric pump that is driven by a command from the control unit 12.

[0083] The second water pump 32 is located upstream of the power train 15 and the heater core 17 and downstream of the second control valve 34 .

[0084] The second radiator 33 can be prevented from receiving coolant by a third bypass valve 37. A second bypass passage 35 that bypasses the second radiator 33 is connected to the second passage 5 via the third bypass valve 37. The second bypass passage 35 has an upstream end (the other end) connected to the second passage 5 via the third bypass valve 37 at a position upstream of the second radiator 33, and a downstream end (one end) connected to the second passage 5 at a position downstream of the second radiator 33. Note that the second bypass passage 35 may have a downstream end (one end) connected to the second passage 5 via the third bypass valve 37 at a position downstream of the first radiator 11, and an upstream end (the other end) connected to the second passage 5 at a position upstream of the second radiator 33.

[0085] The third bypass valve 37 is, for example, a three-way electromagnetic valve, and is controlled by a command from the control unit 12. Note that the third bypass valve 37 may not be a three-way valve, but may be a solenoid valve that opens and closes one end or the other end of the second bypass passage 35.

[0086] The cooling system 31 is capable of controlling the third bypass valve 37 to allow the coolant to flow through the second bypass passage 35 and prevent it from flowing into the second radiator 33. That is, the third bypass valve 37 is capable of opening the second passage 5 at the connection portion between the other end of the second bypass passage 35 and the second passage 5 so that the coolant flows into the second radiator 33, and closing the second bypass passage 35 so that the coolant that has passed through the second bypass passage 35 does not flow downstream. Furthermore, the third bypass valve 37 is capable of closing the second passage 5 at the connection portion between one end of the second bypass passage 35 and the second passage 5 so that the coolant does not flow into the second radiator 33, and opening the second bypass passage 35 so that the coolant that has passed through the second bypass passage 35 flows downstream.

[0087] The second control valve 34 corresponds to a control valve, is disposed upstream of the second water pump 32, and is controlled by commands from the control unit 12. The second control valve 34 is a solenoid valve that opens and closes the upstream end of the second passage 5.

[0088] The third bypass passage 36 has one upstream end connected to the second passage 5 at a position downstream of the powertrain 15, heater core 17, and second radiator 33 and upstream of the first control valve 4, and the other downstream end connected to the second passage 5 at a position downstream of the second control valve 34 and upstream of the second water pump 32.

[0089] The cooling system 31 is capable of circulating the cooling water in the second passage 5 by controlling the second control valve .

[0090] That is, the cooling system 31 closes the second control valve 34 and controls the first control valve 4 so that cooling water does not flow from the second passage 5 into the first passage 3, thereby making it possible to make the circulation of cooling water in the first passage 3 and the circulation of cooling water in the second passage 5 independent (separate).

[0091] In other words, the cooling system 31 is capable of causing cooling water to flow from the first passage 3 into the second passage 5, or of circulating cooling water within the second passage 5 without causing cooling water to flow from the first passage 3 into the second passage 5.

[0092] In more detail, the cooling system 31 opens one end of the second passage 5 so that the cooling water that has passed through the second passage 5 flows into the first passage 3, controls the first control valve 4 so as to open the first passage 3 without impeding the flow in the first passage 3, and further opens the second control valve 34, thereby making it possible for the cooling water that has flowed in from the first passage 3 to flow into the second passage 5.

[0093] Furthermore, the cooling system 31 closes one end of the second passage 5 so that the cooling water that has passed through the second passage 5 does not flow into the first passage 3, controls the first control valve 4 so as to open the first passage 3 so as not to obstruct the flow of water through the first passage 3, and closes the second control valve 34, thereby enabling the cooling water in the second passage 5 to circulate through the second passage 5 using the third bypass passage 36.

[0094] The second control valve 34 may be disposed at the connection between the upstream end of the second passage 5 and the first passage 3 as a three-way valve.

[0095] The optimum cooling conditions for the internal combustion engine 2 are not necessarily the same as the optimum cooling conditions for the battery 16 and the powertrain 15.

[0096] However, the cooling system 31 of the second embodiment can separately manage the coolant temperature in the first passage 3 and the coolant temperature in the second passage 5. Therefore, the cooling system 31 can cool the internal combustion engine 2 under more suitable cooling conditions, and can also cool the battery 16, the powertrain 15, etc. under more suitable cooling conditions.

[0097] Specifically, when the temperature of the coolant in the first passage 3 detected by the first water temperature sensor 10 is higher than a first threshold value on the first passage side (e.g., 60°C) and the temperature of the coolant in the second passage 5 detected by the second water temperature sensor 18 is higher than a first threshold value on the second passage side (e.g., 30°C), the cooling system 31 controls the first control valve 4 and the second control valve 34 to prevent the coolant in the first passage 3 that has exchanged heat with the internal combustion engine 2 from flowing into the second passage 5, and circulates the coolant in the first passage 3 by the first water pump 9 and the coolant in the second passage 5 by the second water pump 32.

[0098] At this time, the first control valve 4 is controlled at a connection portion between the first passage 3 and one downstream end of the second passage 5 to close one end of the second passage 5 so that the coolant that has passed through the second passage 5 does not flow into the first passage 3, and to open the first passage 3 so as not to obstruct the flow in the first passage 3. The second control valve 34 is controlled to close. At this time, the first bypass valve 13 is controlled to allow the coolant to flow into the first radiator 11 if the temperature of the coolant in the first passage 3 detected by the first water temperature sensor 10 is higher than a first passage-side threshold value (e.g., 90°C), and is controlled to prevent the coolant from flowing into the first radiator 11 if the temperature of the coolant in the first passage 3 detected by the first water temperature sensor 10 is equal to or lower than the first passage-side threshold value (e.g., 90°C). The third bypass valve 37 is controlled, for example, to allow the coolant to flow into the second radiator 33.

[0099] The cooling system 31 is capable of controlling the coolant temperature in the first passage 3 and the coolant temperature in the second passage 5 to different temperatures, making it possible to cool (warm up) the internal combustion engine 2 and the battery 16 under the desired cooling conditions (warm up conditions).

[0100] Furthermore, when the temperature of the coolant in the first passage 3 detected by the first water temperature sensor 10 is equal to or lower than a first threshold value on the first passage side (e.g., 60°C) and the temperature of the coolant in the second passage 5 detected by the second water temperature sensor 18 is higher than a first threshold value on the second passage side (e.g., 30°C), the cooling system 31 controls the first control valve 4 and the second control valve 34 to prevent the coolant in the first passage 3 that has exchanged heat with the internal combustion engine 2 from flowing into the second passage 5, and circulates the coolant in the first passage 3 by the first water pump 9 and the coolant in the second passage 5 by the second water pump 32.

[0101] At this time, the first control valve 4 is controlled at a connection portion between the first passage 3 and one downstream end of the second passage 5 to close one end of the second passage 5 so as to prevent the coolant that has passed through the second passage 5 from flowing into the first passage 3, and to open the first passage 3 so as not to obstruct the flow in the first passage 3. The second control valve 34 is controlled to close. Also, at this time, the first bypass valve 13 is controlled, for example, to prevent the coolant from flowing into the first radiator 11. The third bypass valve 37 is controlled, for example, to allow the coolant to flow into the second radiator 33.

[0102] The cooling system 31 is capable of controlling the coolant temperature in the first passage 3 and the coolant temperature in the second passage 5 to different temperatures, making it possible to cool (warm up) the internal combustion engine 2 and the battery 16 under the desired cooling conditions (warm up conditions).

[0103] During operation of the internal combustion engine 2, when the temperature of the coolant in the first passage 3 detected by the first water temperature sensor 10 is higher than a predetermined first threshold value on the first passage side (e.g., 60°C) and the temperature of the coolant detected by the second water temperature sensor 18 is equal to or lower than a predetermined first threshold value on the second passage side (e.g., 30°C), the cooling system 31 controls the first control valve 4 and the second control valve 34 so that the coolant in the first passage 3 that has exchanged heat with the internal combustion engine 2 flows into the second passage 5.

[0104] At this time, the first control valve 4 is controlled to open one end of the second passage 5 at a connection portion between the first passage 3 and a downstream end thereof so that the coolant that has passed through the second passage 5 flows into the first passage 3, and to open the first passage 3 so as not to obstruct the flow in the first passage 3. Also, at this time, the first bypass valve 13 is controlled, for example, so that the coolant flows into the first radiator 11. The third bypass valve 37 is controlled, for example, so that the coolant does not flow into the second radiator 33.

[0105] In the cooling system 31, when predetermined conditions are met (coolant temperature in the first passage 3 > first passage side first threshold value and coolant temperature in the second passage ≦ second passage side first threshold value), the coolant circulating in the first passage 3 flows into the second passage 5, so that the battery 16 can be heated by the coolant heated by the internal combustion engine 2 while suppressing deterioration of friction in the internal combustion engine 2.

[0106] Furthermore, when the temperature of the battery 16 is low, the cooling system 31 can use the heat of the internal combustion engine 2 to raise the temperature of the battery 16. Therefore, the battery 16 can suppress a decrease in output due to a decrease in temperature.

[0107] Furthermore, when the temperature of the cooling water in the first passage 3 detected by the first water temperature sensor 10 is equal to or lower than a first threshold value on the first passage side (e.g., 60°C) and when the temperature of the cooling water in the second passage 5 detected by the second water temperature sensor 18 is equal to or lower than a first threshold value on the second passage side (e.g., 30°C), the cooling system 31 controls the first control valve 4 and the second control valve 34 so that the cooling water in the first passage 3 that has exchanged heat with the internal combustion engine 2 does not flow into the second passage 5.

[0108] At this time, the first control valve 4 is controlled at a connection portion between the first passage 3 and one downstream end of the second passage 5 to close one end of the second passage 5 so as to prevent the coolant that has passed through the second passage 5 from flowing into the first passage 3, and to open the first passage 3 so as not to impede the flow in the first passage 3. The second control valve 34 is controlled to close. Also, at this time, the first bypass valve 13 is controlled to prevent the coolant from flowing into, for example, the first radiator 11. The third bypass valve 37 is controlled to prevent the coolant from flowing into, for example, the second radiator 33.

[0109] When predetermined conditions (coolant temperature in the first passage 3≦first passage side first threshold value and coolant temperature in the second passage 5≦second passage side first threshold value) are met, the cooling system 31 prevents the coolant circulating in the first passage 3 from flowing into the second passage 5, thereby enabling the internal combustion engine 2 to be warmed up early.

[0110] FIG. 5 is a flowchart showing the flow of control relating to the cooling water in the cooling system 31 of the second embodiment.

[0111] In step S31, it is determined whether the coolant temperature on the internal combustion engine outlet side of the first passage 3 (after heat exchange with the internal combustion engine 2) is higher than the first passage-side first threshold value. In step S31, if the internal combustion engine outlet water temperature is higher than the first passage-side first threshold value, the process proceeds to step S32. In step S31, if the internal combustion engine outlet water temperature is equal to or lower than the first passage-side first threshold value, the process proceeds to step S43.

[0112] In step S32, it is determined whether the coolant temperature on the powertrain outlet side of the second passage 5 (after heat exchange with the battery 16 and the powertrain 15) is higher than the second passage first threshold value. In step S32, if the powertrain outlet water temperature is higher than the second passage first threshold value, the process proceeds to step S33. In step S32, if the powertrain outlet water temperature is equal to or lower than the second passage first threshold value, the process proceeds to step S39.

[0113] In step S33, the first control valve 4 is controlled so that the cooling water in the first passage 3 that has exchanged heat with the internal combustion engine 2 does not flow into the second passage 5. That is, in step S33, the first control valve 4 is set so that the cooling water in the first passage 3 circulates through the first passage 3.

[0114] In step S34, the second control valve 34 is closed.

[0115] In step S35, the third bypass valve 37 is controlled so as to circulate the coolant cooled in the second radiator 33. That is, in step S35, the third bypass valve 37 is set so that the coolant flows into the second radiator 33.

[0116] In step S36, it is determined whether the coolant temperature on the internal combustion engine outlet side of the first passage 3 (after heat exchange with the internal combustion engine 2) is higher than the first passage-side third threshold value. In step S36, if the internal combustion engine outlet water temperature is higher than the first passage-side third threshold value, the process proceeds to step S37. In step S36, if the internal combustion engine outlet water temperature is equal to or lower than the first passage-side third threshold value, the process proceeds to step S38.

[0117] In step S37, the first bypass valve 13 is controlled so as to circulate the coolant cooled by the first radiator 11. That is, in step S37, the first bypass valve 13 is set so that the coolant flows into the first radiator 11.

[0118] In step S38, the first bypass valve 13 is controlled so as not to circulate the coolant cooled in the first radiator 11. That is, in step S38, the first bypass valve 13 is set so as not to allow the coolant to flow into the first radiator 11.

[0119] In step S39, the first control valve 4 is controlled so that the cooling water in the first passage 3 that has exchanged heat with the internal combustion engine 2 flows into the second passage 5. That is, in step S39, the first control valve 4 is set so that the cooling water circulates through the first passage 3 and the second passage 5.

[0120] In step S40, the second control valve 34 is opened.

[0121] In step S41, the third bypass valve 37 is controlled so as not to circulate the coolant cooled in the second radiator 33. That is, in step S41, the third bypass valve 37 is set so as not to allow the coolant to flow into the second radiator 33.

[0122] In step S42, the first bypass valve 13 is controlled so as to circulate the coolant cooled in the first radiator 11. That is, in step S42, the first bypass valve 13 is set so that the coolant flows into the first radiator 11.

[0123] In step S43, it is determined whether the coolant temperature on the powertrain outlet side of the second passage 5 (after heat exchange with the battery 16 and the powertrain 15) is higher than the second passage first threshold value. In step S43, if the powertrain outlet water temperature is higher than the second passage first threshold value, the process proceeds to step S44. In step S43, if the powertrain outlet water temperature is equal to or lower than the second passage first threshold value, the process proceeds to step S48.

[0124] In a hybrid vehicle, if the battery 16 has a power reserve and the internal combustion engine 2 is stopped while the vehicle is running, the water temperature at the outlet of the internal combustion engine drops and the water temperature at the outlet of the power train rises. This case is assumed when the process proceeds from step S31 to step S43.

[0125] In step S44, the first control valve 4 is controlled so that the cooling water in the first passage 3 that has exchanged heat with the internal combustion engine 2 does not flow into the second passage 5. That is, in step S44, the first control valve 4 is set so that the cooling water in the first passage 3 circulates through the first passage 3.

[0126] In step S45, the second control valve 34 is closed.

[0127] In step S46, the third bypass valve 37 is controlled so as to circulate the coolant cooled in the second radiator 33. That is, in step S46, the third bypass valve 37 is set so that the coolant flows into the second radiator 33.

[0128] In step S47, the first bypass valve 13 is controlled so as not to circulate the coolant cooled by the first radiator 11. That is, in step S47, the first bypass valve 13 is set so as not to allow the coolant to flow into the first radiator 11.

[0129] In step S48, the first control valve 4 is controlled so that the cooling water in the first passage 3 that has exchanged heat with the internal combustion engine 2 does not flow into the second passage 5. That is, in step S48, the first control valve 4 is set so that the cooling water in the first passage 3 circulates through the first passage 3.

[0130] In step S49, the second control valve 34 is closed.

[0131] In step S50, the third bypass valve 37 is controlled so as not to circulate the coolant cooled in the second radiator 33. That is, in step S50, the third bypass valve 37 is set so as not to allow the coolant to flow into the second radiator 33.

[0132] In step S51, the first bypass valve 13 is controlled so as not to circulate the coolant cooled by the first radiator 11. That is, in step S51, the first bypass valve 13 is set so as not to allow the coolant to flow into the first radiator 11.

[0133] The control flow regarding the lubricating oil in the cooling system 31 of the second embodiment is the same as the control flow regarding the lubricating oil in the cooling system 1 of the first embodiment described above.

[0134] Although specific embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention.

[0135] For example, in the cooling system 31 of the second embodiment, if the second water pump 32 is an electric pump, the first control valve 4 may be controlled so that the cooling water in the first passage 3 that has exchanged heat with the internal combustion engine 2 flows into the second passage 5, and the second water pump 32 may be stopped when the second control valve 34 is controlled to open.

[0136] The above-described embodiments relate to a control method for the cooling system 1, 31 and a control device for the cooling system 1, 31. [Explanation of symbols]

[0137] 1. Cooling system 2...Internal combustion engine 3…1st aisle 4...First control valve 5…Second aisle 6…3rd aisle 7...Oil passage 8...Water jacket 9...First water pump 10...First water temperature sensor 11...First radiator 12...Control unit 13...First bypass valve 14...First bypass passage 15...Powertrain 16...Battery 17...Heater core 18...Second water temperature sensor 19...Oil cooler 20...Second bypass valve 21...Oil jacket 22...Oil pump 23...Oil temperature sensor

Claims

1. A generator mounted on the vehicle; an internal combustion engine that drives the generator; a drive motor that drives the drive wheels of the vehicle; a battery capable of being charged with the electric power generated by the generator and capable of supplying electric power to the drive motor; a first passage through which the refrigerant that has exchanged heat with the internal combustion engine can circulate; a second passage connected to the first passage and in which the generator, the drive motor, and the battery are disposed; a control valve capable of controlling the flow of the refrigerant so that the refrigerant that has exchanged heat with the internal combustion engine does not flow into the second passage, a control method for a cooling system, characterized in that, during operation of the internal combustion engine, when the temperature of the refrigerant in the first passage is higher than a predetermined first threshold value on the first passage side and the temperature of the refrigerant in the second passage is equal to or lower than a predetermined first threshold value on the second passage side, the control valve is controlled so that the refrigerant that has exchanged heat with the internal combustion engine flows into the second passage.

2. A heater core is disposed in the second passage, 2. The control method for a cooling system according to claim 1, wherein, during operation of the internal combustion engine, when the temperature of the refrigerant in the first passage is higher than the first threshold value on the first passage side and the temperature of the refrigerant in the second passage is equal to or lower than the first threshold value on the second passage side, the control valve is controlled so that the refrigerant that has exchanged heat with the internal combustion engine flows into the heater core.

3. an oil passage through which lubricating oil for the internal combustion engine flows; 3. The method for controlling a cooling system according to claim 1, wherein the oil passage is formed so as to pass near a cylinder of the internal combustion engine.

4. 4. The method for controlling a cooling system according to claim 3, wherein the oil passage is formed so as to pass along an outer periphery of a cylinder of the internal combustion engine.

5. a third passage connected to the first passage and allowing the refrigerant in the first passage to circulate; an oil cooler for performing heat exchange between the refrigerant in the third passage and the lubricating oil in the oil passage, 4. The method for controlling a cooling system according to claim 3, wherein when the temperature of the lubricating oil in the oil passage becomes higher than a preset oil temperature threshold, the lubricating oil in the oil passage is cooled by the oil cooler.

6. 2. The control method for a cooling system according to claim 1, wherein, during operation of the internal combustion engine, when the temperature of the refrigerant in the first passage is equal to or lower than a first threshold value on the first passage side and the temperature of the refrigerant in the second passage is equal to or lower than a first threshold value on the second passage side, the control valve is controlled so that the refrigerant that has exchanged heat with the internal combustion engine does not flow into the second passage.

7. 2. The control method for a cooling system according to claim 1, wherein when the temperature of the refrigerant in the second passage is higher than a predetermined second-passage-side second threshold value that is higher than the second-passage-side first threshold value, the control valve is controlled so that the refrigerant that has exchanged heat with the internal combustion engine flows into the second passage.

8. 8. The control method for a cooling system according to claim 7, wherein when the temperature of the refrigerant in the second passage is greater than the first threshold value on the second passage side and is equal to or less than the second threshold value on the second passage side, the control valve is controlled so that the refrigerant that has exchanged heat with the internal combustion engine does not flow into the second passage.

9. a first water pump disposed in the first passage for pumping refrigerant; a second water pump disposed in the second passage for pumping the refrigerant; When the temperature of the refrigerant in the first passage is higher than the first passage-side first threshold value and the temperature of the refrigerant in the second passage is higher than the second passage-side first threshold value during operation of the internal combustion engine, the control valve is controlled so that the refrigerant that has exchanged heat with the internal combustion engine does not flow into the second passage; 2. The method for controlling a cooling system according to claim 1, wherein the refrigerant in the first passage is circulated by the first water pump, and the refrigerant in the second passage is circulated by the second water pump.

10. during operation of the internal combustion engine, when the temperature of the refrigerant in the first passage is equal to or lower than the first passage-side first threshold value and the temperature of the refrigerant in the second passage is higher than the second passage-side first threshold value, the control valve is controlled so that the refrigerant that has exchanged heat with the internal combustion engine does not flow into the second passage; 10. The method for controlling a cooling system according to claim 9, wherein the refrigerant in the first passage is circulated by the first water pump, and the refrigerant in the second passage is circulated by the second water pump.

11. A generator mounted on the vehicle; an internal combustion engine that drives the generator; a drive motor that drives the drive wheels of the vehicle; a battery capable of being charged with the electric power generated by the generator and capable of supplying electric power to the drive motor; a first passage through which the refrigerant that has exchanged heat with the internal combustion engine can circulate; a second passage connected to the first passage and in which the generator, the drive motor, and the battery are disposed; a control valve capable of controlling the flow of the refrigerant so that the refrigerant that has exchanged heat with the internal combustion engine does not flow into the second passage; and a control unit that controls the control valve so that refrigerant that has exchanged heat with the internal combustion engine flows into the second passage when, during operation of the internal combustion engine, the temperature of the refrigerant in the first passage is higher than a predetermined first threshold value on the first passage side and the temperature of the refrigerant in the second passage is equal to or lower than a predetermined first threshold value on the second passage side.

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