Cooling system

Abstract

To improve cooling performance of a radiator while a vehicle is stopped.SOLUTION: In the cooling system 10, a water pump 22 and radiators 24 are provided in a circulation path through which cooling water circulates to cool heat sources of vehicles including a PCU12 and a MG14. A water temperature sensor 28 detects the temperature of the cooling water, and a vehicle speed sensor 34 and an accelerator opening sensor 36 detect whether or not the vehicle is stopped. When the vehicle speed sensor 34 and the accelerator opening sensor 36 detect that the vehicle is stopped and the temperature of the cooling water detected by the water temperature sensor 28 is within a predetermined range, the control unit 54 drives the motor of the water pump 22 so that the amount of the cooling water is smaller than the maximum value of the amount of the cooling water when the vehicle is traveling.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to cooling systems. [Background technology]

[0002] Patent Document 1 discloses a configuration in which, since the radiator for a hybrid electric vehicle (HEV) is not exposed to wind when the vehicle is stopped, a radiator fan positioned opposite the HEV radiator is driven to perform heat exchange between the air blown from outside the vehicle and the coolant flowing through the HEV radiator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-008843 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology described in Patent Document 1 has the problem that the radiator fan operates at a high rate while the vehicle is stopped, causing the motor that rotates the radiator fan to deteriorate quickly and increasing noise and vibration while the vehicle is stopped.

[0005] The present disclosure has been made in consideration of the above circumstances, and an object of the present disclosure is to provide a cooling system that can improve the cooling performance of a radiator while a vehicle is stopped. [Means for solving the problem]

[0006] The cooling system of the first aspect includes a water pump and a radiator provided in a circulation path through which coolant circulates to cool the heat sources of the vehicle, including a power control unit and a motor generator; a temperature detection unit that detects the temperature of the coolant; a stop detection unit that detects whether the vehicle is stopped or not; and a control unit that, when the stop detection unit detects that the vehicle is stopped and the temperature of the coolant detected by the temperature detection unit is within a predetermined range, drives the water pump so that the circulating amount of the coolant is less than the maximum amount of the circulating amount of the coolant when the vehicle is running.

[0007] In a first aspect, when the vehicle is detected as being stopped and the coolant temperature is within a predetermined range, the water pump is driven to reduce the circulating coolant flow rate below the maximum circulating coolant flow rate when the vehicle is moving. This reduces the thermal mass of the coolant receiving heat from the vehicle's heat source, thereby increasing the coolant temperature on the outlet side from the vehicle's heat source (the inlet side to the radiator). Furthermore, as the coolant temperature on the inlet side to the radiator increases, the air-water temperature difference ΔT, which is the difference between the temperature of the air passing through the radiator and the temperature of the coolant flowing through the radiator, increases. Because the cooling performance of the radiator is proportional to the air-water temperature difference ΔT, reducing the circulating coolant flow rate can improve the radiator's cooling performance while the vehicle is stopped, thereby lowering the coolant temperature on the outlet side from the radiator (the inlet side to the heat source).

[0008] A second aspect is the first aspect, further including a radiator fan that ventilates the radiator, wherein the temperature detection unit detects the temperature of the coolant on the inlet side of the circulation path to the heat source, and the control unit controls the operation of the radiator fan based on the temperature of the coolant detected by the temperature detection unit.

[0009] In the second aspect, a radiator fan is provided to ventilate the radiator, and operation of the radiator fan is controlled based on the temperature of the coolant on the inlet side to the heat source. According to the first aspect described above, the cooling performance of the radiator can be improved while the vehicle is stopped, and the temperature of the coolant on the outlet side from the radiator (the inlet side to the heat source) can be lowered. This reduces the operating rate of the radiator fan while the vehicle is stopped, extending the life of the motor that rotates the radiator fan and reducing noise and vibration while the vehicle is stopped.

[0010] In a third aspect, in the first aspect, the control unit drives the water pump at a constant duty ratio when the vehicle stop detection unit detects that the vehicle is stopped and the coolant temperature detected by the temperature detection unit is within a predetermined range.

[0011] In the third aspect, when the vehicle is detected as stopped and the coolant temperature is within a predetermined range, the water pump is driven at a constant duty ratio. Therefore, although the amount of circulating water will fluctuate slightly if the viscosity of the coolant changes due to changes in the coolant temperature, the water pump can be driven with simpler control than when the amount of circulating water is controlled to be constant.

[0012] In a fourth aspect, in the first aspect, when the vehicle stop detection unit detects that the vehicle is moving, the control unit drives the water pump so that the amount of circulating coolant increases or decreases according to the temperature of the coolant detected by the temperature detection unit.

[0013] According to the fourth aspect, even when the vehicle is running, the heat source can be cooled by an appropriate amount of circulating cooling water. [Effects of the Invention]

[0014] The present disclosure has an effect of improving the cooling performance of a radiator while a vehicle is stopped. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic configuration diagram of a cooling system according to an embodiment. [Figure 2] FIG. 2 is a perspective view showing the appearance of a radiator and other components of the cooling system. [Figure 3] 1A is a flowchart of the radiator fan control process, and FIG. 1B is a diagram showing an outline of the radiator fan control process. [Figure 4] 10A is a flowchart showing a water pump control process, FIG. 10B is a flowchart showing a water pump normal control process, and FIG. 10C is a flowchart showing a water pump control process during charging while the vehicle is stationary. [Figure 5] 10A is a diagram showing an outline of the determination of vehicle speed, FIG. 10B is a diagram showing an outline of the determination of accelerator opening, and FIG. 10C is a diagram showing an outline of the determination of PCU inlet water temperature in the water pump control process. [Figure 6] 10 is a diagram showing the relationship between the PCU inlet water temperature and the coolant amount during normal control and when charging while the vehicle is stationary. FIG. [Figure 7] (A) is a coolant amount map, and (B) is a duty ratio map. [Figure 8] FIG. 4 is a diagram showing the heat dissipation performance of a radiator. [Figure 9] FIG. 10 is a schematic diagram showing the results of a simulation calculation carried out by the inventors of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0016] An example of an embodiment of the present disclosure will be described in detail below with reference to the drawings. Fig. 1 shows a cooling system 10 according to this embodiment. The cooling system 10 is a system provided in a hybrid vehicle (HEV) to cool a PCU (Power Control Unit) 12 including an inverter, and two motor generators 14, MG1 and MG2 (hereinafter referred to as MG14), which are mounted on the hybrid vehicle. The PCU 12 and MG14 are examples of heat sources in the present disclosure.

[0017] The PCU 12 is provided with a flow passage through which cooling water flows, and the cooling water cools the PCU 12 by receiving heat from the PCU 12 including the inverter while flowing through the flow passage provided in the PCU 12. One end of a pipe 18 is connected to the cooling water outlet side of the flow passage provided in the PCU 12.

[0018] An oil flow passage is provided in MG 14 for oil to flow through, and an oil cooler 16 is provided in the middle of an oil circulation path including this oil flow passage. The oil receives heat from MG 14 as it flows through the flow passage provided in MG 14. A flow passage is provided in oil cooler 16 for cooling water to flow through, and the cooling water receives heat from the oil as it flows through the flow passage provided in oil cooler 16, thereby cooling the oil and, ultimately, MG 14. The flow passage provided in oil cooler 16 has the other end of pipe 18 connected to its cooling water inlet side and one end of pipe 20 connected to its cooling water outlet side.

[0019] The other end of pipe 20 is connected to the coolant inlet side of a flow passage provided in PCU 12, and a coolant circulation path is formed by the flow passage provided in PCU 12, pipe 18, the flow passage provided in oil cooler 16, and pipe 20. A water pump 22 and a radiator 24 (see also FIG. 2) are provided in this order along pipe 20.

[0020] The water pump 22 has a motor electrically connected to a drive circuit 30, and the motor is driven to rotate by the drive circuit 30, thereby circulating the coolant through the circulation path. The radiator 24 is disposed in a position where it receives the wind while the vehicle is running, and the coolant dissipates heat as it flows through the radiator 24 while the vehicle is running or when a radiator fan 26, which will be described next, is operating.

[0021] A radiator fan 26 (see also FIG. 2 ) is disposed near the radiator 24. The radiator fan 26 is disposed adjacent to the radiator 24 on the vehicle rear side of the radiator 24 so as to ventilate the radiator 24 when in operation. The radiator fan 26 has a motor electrically connected to a drive circuit 32, and is operated when the motor is rotationally driven by the drive circuit 32. In this embodiment, a low-cost brush motor is used as the motor for the radiator fan 26. However, the present disclosure is not limited to this, and a brushless motor may also be used as the motor for the radiator fan 26.

[0022] A water temperature sensor 28 is provided in the coolant circulation path near the coolant inlet side of the PCU 12. The water temperature sensor 28 is connected to the cooling control ECU 40, detects the water temperature T of the coolant on the coolant inlet side of the PCU 12 (hereinafter referred to as the "PCU inlet water temperature"), and outputs the detection result to the cooling control ECU 40. The water temperature sensor 28 is an example of a temperature detection unit in the present disclosure.

[0023] The cooling control ECU 40 includes a CPU (Central Processing Unit) 42, a memory 44 such as a ROM (Read Only Memory) or a RAM (Random Access Memory), a storage 46 such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive), and an input / output I / F (Interface) 48, which are interconnected via a bus 50 so as to be able to communicate with each other. A cooling control program 52 is stored in the storage 46.

[0024] The input / output I / F 48 is connected to the water temperature sensor 28, the vehicle speed sensor 34, the accelerator pedal position sensor 36, and the drive circuits 30 and 32. The vehicle speed sensor 34 and the accelerator pedal position sensor 36 are examples of a vehicle stop detection unit in the present disclosure, but instead of the vehicle speed sensor 34, a rotation speed sensor that detects the rotation speed of the drive shaft of the drive motor (MG2), or a wheel speed sensor that detects the rotation speed of the wheels, may be used.

[0025] In the cooling control ECU 40, the cooling control program 52 is read from the storage 46 and expanded into the memory 44, and the cooling control program 52 expanded into the memory 44 is executed by the CPU 42, so that the CPU 42 functions as the control unit 54 and performs the radiator fan control processing and water pump control processing described below.

[0026] Next, as an operation of this embodiment, first, a radiator fan control process executed by the cooling control ECU 40 (control unit 54) while the ignition switch is on will be described with reference to FIG. 3(A).

[0027] In step 70 of the radiator fan control process, the control unit 54 stops operation of the radiator fan 26 via the drive circuit 32. In step 72, the control unit 54 acquires the PCU inlet water temperature T from the water temperature sensor 28 and determines whether the acquired PCU inlet water temperature T is equal to or higher than a fifth predetermined temperature T5. An example of the fifth predetermined temperature T5 is 57°C. If the determination in step 72 is negative, the process returns to step 70. Therefore, the radiator fan 26 remains in a stopped state while the PCU inlet water temperature T is lower than the fifth predetermined temperature T5.

[0028] If the determination in step 72 is affirmative, the process proceeds to step 74. In step 74, the control unit 54 operates the radiator fan 26 by driving the motor of the radiator fan 26 via the drive circuit 32 to rotate. This causes the coolant to be ventilated through the radiator 24, thereby cooling the coolant flowing through the radiator 24. In this embodiment, the motor of the radiator fan 26 is driven to rotate so that the air speed of the radiator fan 26 (airflow rate to the radiator 24) is, for example, slightly above 1 (m / s).

[0029] In the next step 76, the control unit 54 acquires the PCU inlet water temperature T from the water temperature sensor 28 and determines whether the acquired PCU inlet water temperature T is equal to or higher than a sixth predetermined temperature T6. Note that the sixth predetermined temperature T6 is lower than the fifth predetermined temperature T5 (see FIG. 3(B)), and an example of the sixth predetermined temperature T6 is 55°C. If the determination in step 76 is positive, the process returns to step 74. Therefore, after the radiator fan 26 is operated once, the radiator fan 26 is maintained in an operating state as long as the PCU inlet water temperature T is equal to or higher than the sixth predetermined temperature T5.

[0030] If the determination in step 76 is negative, the process returns to step 70. In this case, the operation of the radiator fan 26 is stopped. In this way, in the radiator fan control process, hysteresis is applied to the operation determination of the radiator fan 26, which prevents the operation of the radiator fan 26 from being frequently turned on and off.

[0031] The above-described radiator fan control process is executed while the ignition switch is on, but while the vehicle is running, the coolant can be sufficiently cooled by the wind blown into the radiator 24. For this reason, the PCU inlet water temperature T becomes equal to or higher than the fifth predetermined temperature T5 and the radiator fan 26 is actually operated when the vehicle is stopped and the MG 14 (more specifically, MG1) is generating electricity (the inverter of the PCU 12 is also operating) for reasons such as the air conditioning being operated, for example, when the vehicle is being charged while stopped.

[0032] Next, with reference to Fig. 4(A), a description will be given of the water pump control process executed by the cooling control ECU 40 (control unit 54) while the ignition switch is on. In step 80 of the water pump control process, the control unit 54 performs a water pump normal control process. This water pump normal control process will be described later.

[0033] In the next step 82, the control unit 54 acquires the vehicle speed V from the vehicle speed sensor 34 and determines whether the acquired vehicle speed V is equal to or less than a first predetermined vehicle speed V1. An example of the first predetermined vehicle speed V1 is 0 (km / h). If the determination in step 82 is affirmative, the process proceeds to step 84. In step 84, the control unit 54 acquires the accelerator opening A from the accelerator opening sensor 36 and determines whether the acquired accelerator opening A is equal to or less than a first predetermined opening A1. An example of the first predetermined opening A1 is 0 (°). In steps 82 and 84, it is determined whether the vehicle is stopped. If the vehicle is moving, the determination in step 82 or step 84 is negative, and the process returns to step 80, where the normal water pump control process is performed.

[0034] If the determination in step 84 is affirmative, the process proceeds to step 86. In step 86, the control unit 54 acquires the PCU inlet water temperature T from the water temperature sensor 28 and determines whether the acquired PCU inlet water temperature T is equal to or greater than the second predetermined temperature T2 and equal to or less than the third predetermined temperature T3. Note that the second predetermined temperature T2 is smaller than the third predetermined temperature T3 (see also FIG. 5C), and an example of the second predetermined temperature T2 is 40° C., and an example of the third predetermined temperature T3 is 65° C. Even if the vehicle is stopped, if the PCU inlet water temperature T is less than the second predetermined temperature T2 or greater than the third predetermined temperature T3, the determination in step 86 is negative and the process returns to step 80, where the normal water pump control process is performed.

[0035] 4(B), the normal water pump control process will be described. In step 100 of the normal water pump control process, the control unit 54 acquires the PCU inlet water temperature T from the water temperature sensor 28. In this embodiment, in the normal water pump control process, the relationship between the PCU inlet water temperature T and the coolant amount (circulating water amount) F is determined so that the coolant amount (circulating water amount) F changes in response to changes in the PCU inlet water temperature T as shown by "normal control" in FIG.

[0036] That is, the relationship between the PCU inlet water temperature T and the coolant flow rate F in the normal water pump control process is determined so that the coolant flow rate F is constant at Fmin when the PCU inlet water temperature T is 30°C or less, the slope of the change in the coolant flow rate F relative to changes in the PCU inlet water temperature T gradually increases when the PCU inlet water temperature T is between 30 and 57°C, and the coolant flow rate F is constant at Fmax when the PCU inlet water temperature T exceeds 57°C. In this embodiment, the relationship between the PCU inlet water temperature T and the coolant flow rate F in the normal water pump control process is stored in advance in the storage 46 as a coolant flow rate map, for example, as shown in FIG. 7A. In step 102, the control unit 54 obtains the coolant flow rate F corresponding to the PCU inlet water temperature T obtained in step 100 from the coolant flow rate map shown in FIG. 7A.

[0037] In this embodiment, a duty ratio map (see FIG. 7B) that defines the duty ratio of the motor drive of the water pump 22 for each value of the PCU inlet water temperature T and the coolant amount F is pre-stored in the storage 46. Note that in the duty ratio map shown in FIG. 7B, multiple duty ratios for a certain value of the coolant amount F are defined for each value of the PCU inlet water temperature T because the coolant amount F fluctuates due to changes in the viscosity of the coolant that occur as the temperature of the coolant changes.

[0038] In step 104, the control unit 54 obtains, from the duty ratio map, a duty ratio d for driving the motor of the water pump 22 that corresponds to the PCU inlet water temperature T obtained in step 100 and the coolant amount F obtained in step 102. In step 106, the control unit 54 controls the drive of the motor of the water pump 22 via the drive circuit 30 so that the motor of the water pump 22 is driven at the duty ratio d obtained in step 104, and then ends the water pump normal control process. In this way, in the water pump normal control process, the coolant amount F is increased or decreased depending on the PCU inlet water temperature T detected by the water temperature sensor 28.

[0039] The normal water pump control process is repeated as long as the determination at any one of steps 82, 84, and 86 is negative. However, if the determinations at steps 82, 84, and 86 are all positive, the process proceeds to step 88. In step 88, the control unit 54 performs a water pump control process during stationary charging. The water pump control process during stationary charging will be described below with reference to FIG. 4(C).

[0040] In this embodiment, in the water pump stationary charging control process, the relationship between the PCU inlet water temperature T and the coolant volume F is determined so that the coolant volume F remains constant, regardless of changes in the PCU inlet water temperature T, as shown under "stationary charging" in FIG. 6 . Specifically, the relationship between the PCU inlet water temperature T and the coolant volume F in the water pump stationary charging control process is determined so that the coolant volume F remains constant at F1 when the PCU inlet water temperature T is 40°C or higher. An example of the coolant volume F1 is 4 L / min. In this embodiment, the duty ratio dx of the motor drive of the water pump 22 is determined so that the coolant volume F remains approximately equal to F1 in the water pump stationary charging control process. Thus, in step 110 of the water pump stationary charging control process, the control unit 54 drives the motor of the water pump 22 at the duty ratio dx predetermined for stationary charging.

[0041] As described above, in the water pump stationary charging control process, the coolant flow rate F is set to be smaller than the coolant flow rate F during normal control, thereby making it possible to lower the PCU inlet water temperature T. That is, Fig. 8 shows the relationship between the airflow speed of the radiator fan 26 and the heat dissipation performance of the radiator 24 for coolant flow rates F of 12 (L / min), 20 (L / min), and 25 (L / min). In this embodiment, the airflow speed of the radiator fan 26 during stationary charging is slightly above 1 (m / sec), and in this range of airflow speed, the heat dissipation performance of the radiator 24 does not change even if the coolant flow rate F changes.

[0042] Furthermore, the motor of water pump 22 is driven so that the coolant flow rate F during stationary charging is smaller than the maximum coolant flow rate Fmax when the vehicle is running (during normal control). As a result, the thermal mass of the coolant receiving heat from PCU 12 and MG 14 (oil cooler 16) is reduced, and the coolant temperature on the oil cooler outlet side (the inflow side to radiator 24) is higher than during normal control.

[0043] Furthermore, when the temperature of the coolant on the inflow side to the radiator 24 rises, the air-water temperature difference ΔT (the difference between the temperature of the air passing through the radiator 24 and the temperature of the coolant flowing through the radiator 24) increases. Since the cooling performance of the radiator 24 is proportional to the air-water temperature difference ΔT, reducing the amount of coolant F can improve the cooling performance of the radiator 24 when charging while the vehicle is stationary.

[0044] Therefore, by making the coolant flow rate F during charging while the vehicle is stationary smaller than the coolant flow rate F during normal control, it is possible to lower the PCU inlet water temperature T, as will be apparent from the examples described below. This makes it possible to reduce the operating rate of the radiator fan 26 during charging while the vehicle is stationary, thereby extending the life of the brushes of the brush motor that drives the radiator fan 26 and reducing noise and vibration while the vehicle is stationary.

[0045] In the water pump control process shown in FIG. 4(A), after the water pump stationary charging control process is started in step 88, the process proceeds to step 90. In step 90, the control unit 54 acquires the vehicle speed V from the vehicle speed sensor 34 and determines whether the acquired vehicle speed V is equal to or less than a second predetermined vehicle speed V2. Note that the first predetermined vehicle speed V1 is less than the second predetermined vehicle speed V2 (see also FIG. 5(A)), and an example of the second predetermined vehicle speed V2 is 2 (km / h). If the determination in step 90 is affirmative, the process proceeds to step 92.

[0046] In step 92, the control unit 54 acquires the accelerator opening degree A from the accelerator opening degree sensor 36 and determines whether the acquired accelerator opening degree A is equal to or less than a second predetermined opening degree A2. Note that the first predetermined opening degree A1 is smaller than the second predetermined opening degree A2 (see also FIG. 5(B)), and an example of the second predetermined opening degree A2 is 1°.

[0047] If the determination in step 92 is affirmative, the process proceeds to step 94. In step 94, the control unit 54 acquires the PCU inlet water temperature T from the water temperature sensor 28, and determines whether the acquired PCU inlet water temperature T is equal to or higher than a first predetermined temperature T1 and equal to or lower than a fourth predetermined temperature T4. Note that the first predetermined temperature T1<second predetermined temperature T2<third predetermined temperature T3<fourth predetermined temperature T4 (see also FIG. 5(C)), and an example of the first predetermined temperature T1 is 38°C, and an example of the fourth predetermined temperature T4 is 67°C.

[0048] If the determination in step 94 is positive, the process returns to step 88, where the water pump stationary charging control process continues. If the determination in any of steps 90, 92, or 94 is negative, the process returns to step 80, where the water pump normal control process is performed. In this way, in the water pump control process shown in FIG. 4(A), hysteresis is applied to the determination of vehicle speed V, accelerator opening A, and PCU inlet water temperature T (see also FIGS. 5(A) to 5(C)), which prevents frequent switching between the water pump normal control process and the water pump stationary charging control process.

[0049] As described above, the cooling system 10 according to this embodiment includes the water pump 22 and the radiator 24 in a circulation path through which coolant circulates to cool the vehicle's heat sources, including the PCU 12 and the MG 14. The water temperature sensor 28 detects the temperature of the coolant, and the vehicle speed sensor 34 and the accelerator pedal position sensor 36 detect whether the vehicle is stopped. When the vehicle speed sensor 34 and the accelerator pedal position sensor 36 detect that the vehicle is stopped and the coolant temperature detected by the water temperature sensor 28 is within a predetermined range, the control unit 54 drives the motor of the water pump 22 so that the amount of coolant is less than the maximum amount of coolant that would occur if the vehicle were moving. This improves the cooling performance of the radiator 24 while the vehicle is stopped, and reduces the temperature of the coolant on the outlet side (inlet side to the heat source) of the radiator 24.

[0050] This embodiment also includes a radiator fan 26 that ventilates the radiator 24, a water temperature sensor 28 that detects the temperature of the coolant on the inlet side of the coolant circulation path to the heat source (PCU inlet side water temperature T), and a control unit 54 controls the operation of the radiator fan 26 based on the coolant temperature detected by the water temperature sensor 28. This makes it possible to reduce the operating rate of the radiator fan 26 while the vehicle is stopped, thereby extending the life of the motor that rotates the radiator fan 26 and reducing noise and vibration while the vehicle is stopped.

[0051] Furthermore, in this embodiment, when the vehicle speed sensor 34 and the accelerator position sensor 36 detect that the vehicle is stopped and the coolant temperature detected by the water temperature sensor 28 is within a predetermined range, the control unit 54 drives the water pump 22 at a constant duty ratio. This allows the water pump 22 to be driven with simpler control than when, for example, the amount of circulating water is controlled to be constant.

[0052] Furthermore, in this embodiment, when the vehicle speed sensor 34 and the accelerator position sensor 36 detect that the vehicle is moving, the control unit 54 drives the motor of the water pump 22 so that the amount of circulating coolant increases or decreases according to the coolant temperature detected by the water temperature sensor 28. This allows the heat source to be cooled by an appropriate amount of circulating coolant even when the vehicle is moving.

[0053] In the above embodiment, the PCU 12 and the MG 14 are used as examples of heat sources in the present disclosure. However, the heat sources to be cooled by the cooling system according to the present disclosure are not limited to the above, and may also include, for example, a battery.

[0054] In addition, in the above embodiment, when the vehicle is stopped and the PCU inlet water temperature T is within a predetermined range, it is determined that the vehicle is in the stopped state of charging, and the water pump stop-charge control processing is performed. However, the water temperature used to determine whether the vehicle is in the stopped state of charging may be the oil cooler outlet water temperature, for example.

[0055] In the above embodiment, the motor of water pump 22 is driven at a predetermined duty ratio dx during charging while the vehicle is stationary. However, the present disclosure is not limited to this. The duty ratio d for driving the motor of water pump 22 may be increased or decreased in response to changes in PCU inlet water temperature T so that the coolant amount F remains constant during charging while the vehicle is stationary. [Example]

[0056] Next, with reference to FIG. 9, the results of simulation calculations performed by the inventors of the present application to confirm the effects of the present disclosure will be described.

[0057] In this simulation, the cooling system 10 described in the embodiment was assumed to have an ambient temperature of 45°C in front of the radiator 24, a heat dissipation rate of approximately 1 kW, and a wind speed of the radiator fan 26 slightly exceeding 1 m / sec. The radiator inlet water temperature and the PCU inlet water temperature T were calculated for the case where the coolant flow rate F was set to 12 L / min (FIG. 9A) and the case where the coolant flow rate F was set to 4 L / min (FIG. 9B).

[0058] As a result, when the cooling water flow rate F was set to 12 (L / min), the radiator inlet water temperature was 57.5 (°C) and the PCU inlet water temperature T was 56.1 (°C), whereas when the cooling water flow rate F was set to 4 (L / min), the radiator inlet water temperature was 58.2 (°C) and the PCU inlet water temperature T was 54.1 (°C).It was confirmed that limiting the cooling water flow rate F to 4 (L / min) resulted in a PCU inlet water temperature T that was 2 (°C) lower. [Explanation of symbols]

[0059] 10 Cooling System 12 PCU (heat source) 14 Motor generator (heat source) 22 Water pump 24 Radiator 26 Radiator fan 28 Water temperature sensor 34 Vehicle speed sensor (stop detection section) 36 Accelerator opening sensor (vehicle stop detection section) 40 Cooling control ECU 54 Control Unit

Claims

1. a water pump and a radiator provided in a circulation path through which coolant circulates to cool a heat source of the vehicle including the power control unit and the motor generator; a temperature detection unit that detects the temperature of the cooling water; a vehicle stop detection unit that detects whether the vehicle is stopped; a control unit that, when the vehicle stop detection unit detects that the vehicle is stopped and the coolant temperature detected by the temperature detection unit is within a predetermined range, drives the water pump so that the circulating water volume of the coolant becomes smaller than the maximum circulating water volume of the coolant when the vehicle is running; Cooling system including:

2. The system further includes a radiator fan for blowing air through the radiator, the temperature detection unit detects the temperature of the cooling water at an inlet side of the circulation path to the heat source, The cooling system according to claim 1 , wherein the control unit controls the operation of the radiator fan based on the temperature of the cooling water detected by the temperature detection unit.

3. 2. The cooling system according to claim 1, wherein the control unit drives the water pump at a constant duty ratio when the vehicle stop detection unit detects that the vehicle is stopped and the coolant temperature detected by the temperature detection unit is within a predetermined range.

4. 2. The cooling system according to claim 1, wherein when the vehicle stop detection unit detects that the vehicle is moving, the control unit drives the water pump so that the amount of circulating coolant increases or decreases depending on the temperature of the coolant detected by the temperature detection unit.

Images