COOLING CONTROL DEVICE, VEHICLE, COOLING CONTROL METHOD, AND NON-TRANSITORY STORAGE MEDIUM

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2024-198291, filed November 13, 2024, the entire contents of which are incorporated herein by reference.

FIELD

The present invention relates generally to a cooling control device, a vehicle, a cooling control method, and a non-transitory storage medium.

BACKGROUND

As a heat source generating heat, a motor, a battery, and the like are mounted on a vehicle such as an electric vehicle, etc. Such a vehicle on which a heat source is mounted has a flow path passing through the heat source and a radiator, and causes cooling water to circulate through the flow path by driving a pump. Heat generated by the heat source is discharged into the cooling water flowing through the flow path. The cooling water into which heat has been discharged flows in the flow path toward the radiator. Furthermore, in the radiator, the cooling water is cooled by air blown from a fan, so that the heat is radiated from the cooling water. In the flow path, the cooling water cooled (from which heat has been radiated) in the radiator flows toward the heat source (refer to Jpn. Pat. Appln. KOKAI Publication No. 2019-126132).

In a vehicle on which a heat source, a radiator, and the like are mounted, as described above, a cooling control device mounted on the vehicle performs control for keeping the temperature of the cooling water flowing through a flow path constant over time, for example, keeping the temperature of the cooling water constant over time at a portion where the cooling water flows out of the heat source. In the control for keeping the temperature of the cooling water constant, the cooling control device performs feedback control on the temperature of the cooling water by controlling, on the basis of, e.g., a temporal change in the temperature of the cooling water, the number of revolutions of a fan configured to blow air to the radiator and the flow amount of the cooling water in the flow path toward the radiator.

SUMMARY

According to an aspect of the present invention, a cooling control device includes a specifying unit and a control unit, and the specifying unit specifies, on a basis of an operation state of a heat source mounted on a vehicle, an amount of heat discharged from the heat source into cooling water flowing through a flow path. The control unit controls, on a basis of the amount of discharged heat specified by the specifying unit, at least one of a number of revolutions of a fan configured to blow air into a radiator and a flow rate of the cooling water into the radiator inside the flow path.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing an example of a vehicle according to an embodiment.

FIG. 2 is a flowchart schematically showing an example of processing relating to cooling of a heat source, which is performed by a processing execution unit of a cooling control device in the embodiment.

FIG. 3 is a flowchart schematically showing an example of processing of specifying the amount of discharged heat based on an operation state of the heat source.

FIG. 4 is a flowchart schematically showing an example of processing of specifying the amount of discharged heat based on the operation state of the heat source.

FIG. 5 is a flowchart schematically showing an example of processing of specifying the amount of discharged heat based on the operation state of the heat source.

FIG. 6 is a flowchart schematically showing an example of control based on the specified amount of discharged heat.

FIG. 7 is a flowchart schematically showing an example of control based on a temporal change in the temperature of the cooling water.

FIG. 8 is a block diagram schematically illustrating, by using functional blocks, an example of processing relating to cooling of the heat source, which is performed by the processing execution unit of the cooling control device in the embodiment.

FIG. 9 is a schematic diagram showing an example of temporal changes in the temperature of the cooling water and the amount of energy used in control in a state in which the control for keeping the temperature of the cooling water constant is performed in a comparative example.

FIG. 10 is a schematic diagram showing an example of temporal changes in the temperature of the cooling water and the amount of energy used in control in a state in which the control for keeping the temperature of the cooling water constant is performed in the embodiment.

DETAILED DESCRIPTION

Hereinafter, the embodiments will be described with reference to the accompanying drawings.

FIG. 1 is a schematic view showing an example of a vehicle 1 according to an embodiment. The vehicle 1 is, for example, an electric vehicle. As shown in FIG. 1, a motor 2 and a battery 3 are mounted on the vehicle 1. Each of the motor 2 and the battery 3 is a heat source that generates heat in an operating state. In the vehicle 1, the motor 2 is driven by an input of a current to the motor 2, thereby generating a driving force for causing the vehicle 1 to travel.

In the vehicle 1, for example, the motor 2 is driven by electric power discharged from the battery 3 being supplied to the motor 2. At this time, the electric power from the battery 3 is converted as appropriate into electric power corresponding to the motor 2 through DC/DC conversion, DC/AC conversion, or the like. Furthermore, according to an example, the motor 2 also functions as a regenerative brake, and the battery 3 is charged with electric power generated by the motor 2. In such a case, the electric power from the motor 2 is converted as appropriate into electric power corresponding to the battery 3 through DC/DC conversion, AC/DC conversion, or the like, thereby being supplied to the battery 3.

The vehicle 1 has a cooling mechanism 5A used for cooling the motor 2 and a cooling mechanism 5B used for cooling the battery 3. Each of the cooling mechanisms 5A and 5B includes a flow path 6, a radiator 7, a pump 8, and a fan 9. Hereinafter, a configuration for cooling the motor 2 in the cooling mechanism 5A will be described. Meanwhile, a configuration for cooling an object to be cooled in the cooling mechanism 5B is the same as that of the cooling mechanism 5A except that a heat source to be cooled is the battery 3. Therefore, a description of the configuration for cooling the battery 3 in the cooling mechanism 5B will be omitted.

The cooling mechanism 5A has the flow path 6 passing through the motor 2, which is the heat source, and the radiator 7. The flow path 6 is a circulation flow path that extents from the radiator 7, passes through the motor 2, and returns to the radiator 7. The pump 8 is a driving source that causes a cooling fluid filled in the flow path 6 to flow therethrough. For example, the pump 8 is an electric water pump. In the cooling mechanism 5A, cooling water, which is a cooling fluid, is caused to circulate in the flow path 6 by driving the pump 8. The cooling water discharged from the pump 8 flows into the radiator 7 through the motor 2. The cooling water then flows from the radiator 7 toward the pump 8.

In the cooling mechanism 5A, heat generated by the motor 2 is discharged into the cooling water flowing through the flow path 6. The cooling water into which heat has been discharged from the motor 2 flows inside the flow path 6 toward the radiator 7. In the cooling mechanism 5A, air is blown from the fan 9 toward the radiator 7 by driving the fan 9. Therefore, in the radiator 7, cooling water is cooled by air blown from the fan 9, so that heat is radiated from the cooling water. In the flow path 6, the cooling water cooled (from which heat has been radiated) in the radiator 7 flows toward the motor 2 via the pump 8. Accordingly, the cooling water cooled in the radiator 7 is supplied to the motor 2.

In FIG. 1, arrow F indicates a flow of cooling water in the flow path 6 in each of the cooling mechanisms 5A and 5B. Furthermore, the cooling mechanisms 5A and 5B are different from each other in terms of the temperature zone of cooling water flowing through the flow path 6. The flow path 6 of the cooling mechanism 5A does not communicate with the flow path 6 of the cooling mechanism 5B, and is independent of the flow path 6 of the cooling mechanism 5B. Furthermore, in the cooling mechanism 5A, the motor 2 can discharge heat only into the cooling water flowing through the flow path 6, and in the cooling mechanism 5B, the battery 3 can discharge heat only into the cooling water flowing through the flow path 6.

In the cooling mechanism 5A, the amount of air from the fan 9 to the radiator 7 changes in accordance with the number of revolutions of the fan 9, so that the blowing state of air to the radiator 7 changes. In the cooling mechanism 5A, the amount of heat radiated from the cooling water in the radiator 7 increases in accordance with the increase in the number of revolutions of the fan 9. Furthermore, in the cooling mechanism 5A, the flow rate of the cooling water in the flow path 6 changes in accordance with the operation of the pump 8, so that the flow rate of the cooling water into the radiator 7 changes. The change in the flow rate of the cooling water into the radiator 7 changes the time required for the cooling water to circulate one round in the flow path 6. Therefore, in the cooling mechanism 5A, the cooling state in the radiator 7 changes in accordance with the number of revolutions of the fan 9 and the flow rate of the cooling water into the radiator 7, so that the amount of heat radiated from the cooling water in the radiator 7 changes. The amount of heat radiated in the radiator 7 increases in accordance with the increase in the flow rate of the cooling water into the radiator 7.

In the flow path 6 of each of the cooling mechanisms 5A and 5B, a temperature sensor 11 that measures the temperature of the cooling water flowing through the flow path 6 is arranged. In one example, in the flow path 6 of the cooling mechanism 5A, the temperature of the cooling water is measured by the temperature sensor 11 at a portion (outlet portion) where the cooling water flows out of the motor 2 serving as a heat source. In the flow path 6 of the cooling mechanism 5B, the temperature of the cooling water is measured by the temperature sensor 11 at a portion (outlet portion) where the cooling water flows out of the battery 3 serving as a heat source.

The vehicle 1 further has a current meter 12, a revolution meter 13 such as a tachometer, and a torque sensor 15, as measuring instruments for measuring parameters relating to the operating state of the motor 2. The current meter 12 measures a current input to the motor 2. The revolution meter 13 measures the number of revolutions of the motor 2 which is being driven (rotationally driven). The torque sensor 15 measures a torque acting on the motor 2 which is being driven. The vehicle 1 further has a current meter 16 as a measuring instrument for measuring parameters relating to the operating state of the battery 3. The current meter 16 measures a current flowing through the battery 3. Therefore, the current meter 16 measures a current input to the battery 3 in a state in which the battery 3 is charged, and measures a current output from the battery 3 in a state in which the battery 3 is discharged.

The vehicle 1 further has a cooling control device 20. The cooling control device 20 includes a processing execution unit 21 and a storage unit 22, and the processing execution unit 21 includes a specifying unit 23 and a control unit 25. The storage unit 22 stores a program, etc., to be executed by the processing execution unit 21, and each of the specifying unit 23 and the control unit 25 executes at least a part of the processing to be executed by the processing execution unit 21. The processing execution unit 21 of the cooling control device 20 performs processing relating to cooling of the motor 2 and the battery 3 each serving as a heat source. For example, the processing execution unit 21 performs operation control of each of the cooling mechanisms 5A and 5B. At this time, the processing execution unit 21 performs processing by executing a cooling control program stored in the storage unit 22, etc. The processing execution unit 21 may download, via a network, programs to be executed, which include a cooling control program.

The cooling control device 20 is constituted by an in-vehicle computer such as an in-vehicle server mounted on the vehicle. The processing execution unit 21 is constituted by a processor, an integrated circuit, or the like of the in-vehicle computer, and the processor, etc., constituting the processing execution unit 21 includes any one of the electronic circuits such as an electronic control unit (ECU), a central processing unit (CPU), an application specific integrated circuit (ASIC), a microcomputer, a field programmable gate array (FPGA), a digital signal processor (DSP), etc. The processing execution unit 21 may be constituted by a single processor, etc., or may be constituted by a plurality of processors, etc. The storage unit 22 is constituted by a storage medium (non-transitory storage medium) and includes any one of a main storage medium including a memory and an auxiliary storage medium.

The processing execution unit 21 of the cooling control device 20 periodically acquires a measurement result by the temperature sensor 11 of each of the cooling mechanisms 5A and 5B. Therefore, the processing execution unit 21 acquires a temporal change (time history) of the temperature of the cooling water in each of the cooling mechanisms 5A and 5B. The processing execution unit 21 periodically acquires, as measurement results of parameters relating to the operation state of the motor 2, measurement results by the current meter 12, the revolution meter 13, and the torque sensor 15. The processing execution unit 21 periodically acquires, as measurement results of parameters relating to the operation state of the battery 3, measurement results by the current meter 16.

In processing relating to cooling of the motor 2, which is a heat source, the control unit 25 of the processing execution unit 21 controls the operation of each of the pump 8 and the fan 9 of the cooling mechanism 5A. Accordingly, in the cooling mechanism 5A, the number of revolutions of the fan 9 and the flow rate of the cooling water to the radiator 7 in the flow path 6 are controlled by the control unit 25, and the amount of heat radiated in the radiator 7 is adjusted by the control unit 25, etc. Furthermore, in processing relating to cooling of the battery 3, which is a heat source, the control unit 25 of the processing execution unit 21 controls the operation of each of the pump 8 and the fan 9 of the cooling mechanism 5B. Accordingly, in the cooling mechanism 5B, the number of revolutions of the fan 9 and the flow rate of the cooling water to the radiator 7 in the flow path 6 are controlled by the control unit 25, and the amount of heat radiated in the radiator 7 is adjusted by the control unit 25, etc.

FIG. 2 is a flowchart schematically showing an example of processing relating to cooling of a heat source, which is performed by the processing execution unit 21 of a cooling control device 20 in the embodiment. While the motor 2 is operating in the vehicle 1, the processing execution unit 21 repeatedly executes the processing of FIG. 2 as processing relating to cooling of the motor 2, which is a heat source. Furthermore, while the battery 3 is operating in the vehicle 1, the processing execution unit 21 repeatedly executes the processing of FIG. 2 as processing relating to cooling of the battery 3, which is a heat source. In a case where the processing of FIG. 2 is started, the specifying unit 23 of the processing execution unit 21 specifies, on the basis of the operation state of the heat source, the amount of heat discharged from the heat source into the cooling water flowing through the flow path 6 (S201). At this time, the processing relating to cooling of the motor 2 specifies the amount of heat discharged from the motor 2 into cooling water flowing through the flow path 6 of the cooling mechanism 5A. The processing relating to cooling of the battery 3 specifies the amount of heat discharged from the battery 3 into the cooling water flowing through the flow path 6 of the cooling mechanism 5B. The details of processing for specifying the amount of discharged heat will be described later; however, any one of the plurality of processes of the processing may be executed or two or more processes may be combined.

FIG. 3 is a flowchart schematically showing an example of processing of specifying the amount of discharged heat based on the operation state of the heat source shown in FIG. 2 (S201). FIG. 3 is a flowchart showing the processing of specifying the amount of heat discharged from the motor 2 into the cooling water in a case where the motor 2, which is a heat source, is driven to cause the vehicle 1 to travel. In a case where the specifying processing is started, the specifying unit 23 acquires a parameter indicating the operation state of the motor 2 (S301). The parameter indicating the operation state of the motor 2 is, for example, at least one of the plurality of parameters including the measurement results of a current (input current), the number of revolutions, and a torque of the motor 2. In the present embodiment, the specifying unit 23 acquires the current (input current), the number of revolutions, and the torque of the motor 2 from the current meter 12, the revolution meter 13, and the torque sensor 15, respectively.

The specifying unit 23 calculates input energy to the motor 2 on the basis of the measurement result of the current of the motor 2 (S302). The specifying unit 23 calculates, as electric energy, the input energy to the motor 2. Furthermore, the input energy to the motor 2 takes a greater value as the current of the motor 2 increases.

The specifying unit 23 calculates output energy from the motor 2 on the basis of the measurement results of the number of revolutions and the torque of the motor 2 (S303). The specifying unit 23 calculates, as kinetic energy, output energy from the motor 2. The output energy from the motor 2 takes a greater value as the number of revolutions of the motor 2 increases. The output energy from the motor 2 takes a greater value as the torque of the motor 2 increases.

The specifying unit 23 specifies the amount of heat discharged from the motor 2 into the cooling water on the basis of the input energy and the output energy (S304). Specifically, the specifying unit 23 specifies the amount of heat discharged from the motor 2 into the cooling water on the basis of a value obtained by subtracting the output energy from the input energy. That is, energy corresponding to a loss in conversion from the electric energy to the kinetic energy in the motor 2 is discharged as thermal energy from the motor 2 into the cooling water. The input energy to the motor 2, the output energy from the motor 2, and the amount of heat discharged from the motor 2 are each indicated by, for example, a unit W (watt). Furthermore, a value obtained by subtracting the output energy from the input energy may be set to the amount of discharged heat to be specified, or a value obtained by multiplying the value obtained by the subtraction by a coefficient representing a transfer rate to the cooling water may be set to the amount of discharged heat to be specified.

FIG. 4 is a flowchart schematically showing an example of processing of specifying the amount of discharged heat based on the operation state of the heat source (S201). FIG. 4 is a flowchart showing processing of specifying the amount of heat discharged from the motor 2 into the cooling water in a case where the motor 2, which is a heat source, performs a regenerative operation in the vehicle 1 to generate electric power. In a case where the specifying processing of FIG. 4 is started, the specifying unit 23 acquires measurement results of a current (output current), the number of revolutions, and a torque of the motor 2 from the current meter 12, the revolution meter 13, and the torque sensor 15, respectively (S401). The current, the number of revolutions, and the torque of the motor 2 are acquired as parameters indicating the operation state of the motor 2.

The specifying unit 23 calculates, on the basis of the measurement results of the number of revolutions and the torque of the motor 2, input energy (regenerative energy) to the motor 2 (S402). The specifying unit 23 calculates, as kinetic energy, the input energy to the motor 2. The input energy to the motor 2 takes a greater value as the number of revolutions of the motor 2 increases. The input energy to the motor 2 takes a greater value as the torque of the motor 2 increases.

The specifying unit 23 calculates output energy from the motor 2 on the basis of the measurement result of the current of the motor 2 (S403). As the output energy of the motor 2, electric energy is calculated. Furthermore, the output energy from the motor 2 takes a greater value as the current of the motor 2 increases.

The specifying unit 23 specifies the amount of heat discharged from the motor 2 into the cooling water on the basis of the input energy and the output energy (S404). Specifically, the specifying unit 23 specifies the amount of heat discharged from the motor 2 into the cooling water on the basis of a value obtained by subtracting the output energy from the input energy. That is, energy corresponding to a loss in a case of converting kinetic energy into electric energy by a regenerative operation of the motor 2 is discharged as thermal energy from the motor 2 into the cooling water. The input energy to the motor 2, the output energy from the motor 2, and the amount of heat discharged from the motor 2 are each indicated by, for example, a unit W (watt). Furthermore, lost energy obtained by subtracting the output energy from the input energy may be set to the amount of discharged heat to be specified, or a value obtained by multiplying the lost energy by a transfer rate to the cooling water as a coefficient may be set to the amount of discharged heat to be specified.

FIG. 5 is a flowchart schematically showing an example of processing of specifying the amount of discharged heat based on the operation state of the heat source shown in FIG. 2 (S201). FIG. 5 is a flowchart showing processing of specifying the amount of heat discharged from the battery 3 into the cooling water in a case where the battery 3, which is a thermal source, is operated by charging or discharging. In a case where the specifying processing of FIG. 5 is started, the specifying unit 23 acquires a measurement result of a current (input current or output current) of the battery 3 from the current meter 16 (S501). The current of the battery 3 is acquired as a parameter indicating the operation state of the battery 3.

The specifying unit 23 calculates the Joule heat generated in the battery 3, on the basis of the measurement result of the current of the battery 3 (S502). The storage unit 22 stores information on an internal resistance of the battery 3. In the processing of S502, the specifying unit 23 calculates the Joule heat in the battery 3, using the measurement result of the current of the battery 3 and the information on the internal resistance of the battery 3. The specifying unit 23 specifies the amount of heat discharged from the battery 3 into the cooling water, on the basis of a calculation result of the Joule heat (S503). That is, energy corresponding to the Joule heat is discharged as thermal energy from the battery 3 into the cooling water. The amount of heat discharged from the battery 3 is indicated by, for example, a unit W (watt). Furthermore, a value obtained as the Joule heat may be set to the amount of discharged heat to be specified, or a value obtained by multiplying the value obtained as the Joule heat by a coefficient representing a transfer rate to the cooling water may be set to the amount of discharged heat to be specified.

The description returns to the flowchart of FIG. 2. After the processing of S201, the control unit 25 executes cooling control processing of the heat source based on a result of specifying the amount of heat discharged from the heat source (S202). The processing relating to cooling of the motor 2 controls the operation of the cooling mechanism 5A on the basis of the amount of discharged heat specified for the motor 2 in step S202, and controls the pump 8 and the fan 9 of the cooling mechanism 5A. The processing relating to cooling of the battery 3 controls the operation of the cooling mechanism 5B on the basis of the amount of discharged heat specified for the battery 3 in step S202, and controls the pump 8 and the fan 9 of the cooling mechanism 5B.

FIG. 6 is a flowchart schematically showing an example of the cooling control processing (S202) based on a result of specifying the amount of discharged heat of FIG. 2. The cooling control processing shown in FIG. 6 is processing that controls the operation of the cooling mechanism 5A on the basis of a result of specifying the amount of heat discharged from the motor 2 serving as a heat source. The cooling control processing shown in FIG. 6 is also processing that controls the operation of the cooling mechanism 5B on the basis of a result of specifying the amount of heat discharged from the battery 3 serving as a heat source. In a case where the control shown in FIG. 6 is started, the control unit 25 acquires the specified amount of heat discharged (the result of specifying the discharged heat) from the heat source (motor 2 or battery 3) into the cooling water (S601).

The control unit 25 then determines the number of revolutions of the fan 9 and the flow rate of the cooling water such that the amount of heat discharge in the radiator 7 matches the result of specifying the amount of heat discharged from the heat source in the cooling mechanism (5A or 5B) (S602). The storage unit 22 stores, for each of the cooling mechanisms 5A and 5B, relationship data (correlation map) indicating a relationship between the amount of heat radiated in the radiator 7 and both the number of revolutions of the fan 9 and the flow rate of the cooling water. The control unit 25 determines, using the specified amount of discharged heat and the aforementioned relationship data, the number of revolutions of the fan 9 and the flow rate of the cooling water such that the amount of heat radiated in the radiator 7 matches the result of specifying the amount of discharged heat. The form of the correlation map is not limited to the one described above. For example, in the correlation map, the number of revolutions of the fan 9 and the flow rate of the cooling water may be set such that the amount of heat radiated in the radiator 7 matches the result of specifying the amount of heat discharged from the heat source, in regard to the amount of discharged heat under each of the plurality of conditions which are different from each other in either one of the temperature of the cooling water and the temperature of outside air blown to the radiator 7 by the fan 9. In such a case, the control unit 25 specifies the number of revolutions of the fan 9 and the flow rate of the cooling water on the basis of the result of specifying the amount of discharged heat, the temperature of the cooling water acquired from the temperature sensor 11, the temperature of outside air acquired from an outside air temperature sensor (not shown), and the aforementioned correlation map. In addition, the correlation map was described as an example; however, instead of the form of a map, a relationship expression of each parameter which is experimentally or theoretically determined in advance can also be used.

The control unit 25 then controls the fan 9 and the pump 8 so as to realize the determined number of revolutions of the fan 9 and the determined flow rate of the cooling water into the radiator 7 (S603). Through execution of the processing in FIG. 6, in the cooling mechanism (5A or 5B), at least one of the number of revolutions of the fan 9 and the flow rate of the cooling water is controlled such that a difference between the specified amount of discharged heat and the amount of heat radiated in the radiator 7 falls within a predetermined range, on the basis of the result of specifying the amount of heat discharged from the heat source and relationship data indicating a relationship of the amount of heat radiated in the radiator 7 and both the number of revolutions of the fan 9 and the flow rate of the cooling water. In one example, the control unit 25 controls the number of revolutions of the fan 9 and the flow rate of the cooling water into the radiator 7 such that the specified amount of discharged heat matches the amount of heat radiated in the radiator 7.

The description returns to the flow chart of FIG. 2. The control unit 25 determines whether or not the temperature of the cooling water in the cooling mechanism (5A or 5B) has changed (S203). While executing the cooling control processing, the control unit 25 acquires information indicating the temperature of the cooling water flowing through the flow path 6 in the cooling mechanism (5A or 5B) from the temperature sensor 11 of each cooling mechanism. In a state in which each of the cooling mechanisms 5A and 5B is adjusted to the number of revolutions of the fan 9 and the flow rate of the cooling water into the radiator 7, each determined on the basis of the result of specifying the amount of discharged heat, the control unit 25 sequentially acquires a measurement result of the temperature of cooling water from the temperature sensor 11 of the cooling mechanism (5A or 5B). Herein, the processing shown in FIG. 2 is periodically repeated in a state in which the heat source is operating. Therefore, the control unit 25 periodically acquires a measurement result of the temperature of the cooling water. The control unit 25 determines that the temperature of the cooling water has changed in a case where a measurement result of the temperature of the cooling water has changed from a measurement result acquired previously. As for the determination as to whether the temperature of the cooling water has changed, it may be determined that the temperature of the cooling water has changed in a case where a difference from the previous measurement result is equal to or greater than a predetermined value (for example, 1 ºC). Alternatively, it may be determined that the temperature of the cooling water has changed in a case where a rate of change in the time-averaged value of measurement results of the temperature of the cooling water during a predetermined period exceeds a predetermined threshold value.

In a case where the temperature of the cooling water has not changed (S203-No), the processing execution unit 21 ends the processing of FIG. 2 without performing the processing in S204. Meanwhile, in a state in which the heat source is operated, the processing of FIG. 2 is repeatedly performed. Therefore, as long as the heat source is operated, the processing of FIG. 2 is started again to perform the processing of specifying the amount of discharged heat based on the operation state of a heat source (S201). In a case where the temperature of the cooling water has not changed from the previous measurement result, the control unit 25 controls the fan 9 and the pump 8 so as to maintain the number of revolutions of the fan 9 and the flow rate of the cooling water of the radiator 7, each determined on the basis of the result of specifying the amount of discharged heat. At this time, in one example, the processing execution unit 21 determines that the actual amount of heat discharged from the heat source (motor 2 or battery 3) into the cooling water matches the amount of heat radiated in the radiator 7, and the result of specifying the amount of heat discharged into the cooling water in the heat source matches the actual amount of discharged heat.

On the other hand, in a case where the temperature of the cooling water has changed (S203-Yes), the control unit 25 executes control processing that controls the operation relating to cooling of the heat source on the basis of a temporal change of the temperature of the cooling water (S204). The processing relating to cooling of the motor 2 controls, in S204, the operation of the cooling mechanism 5A to control the pump 8 and the fan 9 of the cooling mechanism 5A on the basis of the temporal change in the temperature of the cooling water in the cooling mechanism 5A. The processing relating to cooling of the battery 3 controls, in S204, the operation of the cooling mechanism 5B to control the pump 8 and the fan 9 of the cooling mechanism 5B on the basis of the temporal change in the temperature of the cooling water in the cooling mechanism 5B.

FIG. 7 is a flowchart schematically showing an example of the control processing (S204) based on a temporal change in the temperature of the cooling water in FIG. 2. The processing in FIG. 7 is performed, for each of the cooling mechanisms 5A and 5B, as control of the operation based on a temporal change in the temperature of the cooling water. In a case where the control shown in FIG. 7 is started, the control unit 25 determines whether or not the temperature of the cooling water in the cooling mechanism (5A or 5B) has increased (S141). In the present embodiment, the control unit 25 determines that the temperature of the cooling water has increased in a case where the measurement result of the temperature of the cooling water has increased from the previous measurement result, and determines that the temperature of the cooling water has decreased in a case where the measurement result of the temperature of the cooling water has decreased from the previous measurement result.

In a case where the temperature of the cooling water has increased (S701-Yes), the control unit 25 controls the fan 9 and the pump 8 by increasing at least one parameter of the number of revolutions of the fan 9 and the flow rate of the cooling water into the radiator 7, each determined on the basis of the result of specifying the amount of discharged heat (S702). The control unit 25 determines the increase amount with respect to at least one of the number of revolutions of the fan 9 and the flow rate of the cooling water, in accordance with the rise amount of the temperature of the cooling water. For example, as the rise amount of the temperature of the cooling water with respect to the previous measurement result becomes greater, the increase amounts of the number of revolutions of the fan 9 and the flow rate of the cooling water, each determined on the basis of the result of specifying the amount of discharged heat, are increased. Furthermore, in one example, in a case where the temperature of the cooling water rises as compared to the previous measurement result, the processing execution unit 21 determines that the actual amount of heat discharged from the heat source (motor 2 or battery 3) into the cooling water is greater than the amount of heat radiated in the radiator 7 and the actual amount of discharged heat is greater than the result of specifying the amount of heat discharged into the cooling water in the heat source.

On the other hand, in a case where the temperature of the cooling water drops (S701-No), the control unit 25 decreases at least one parameter of the number of revolutions of the fan 9 and the flow rate of the cooling water into the radiator 7, each determined on the basis of the result of specifying the amount of discharged heat (S703). The control unit 25 determines the decrease amount with respect to at least one of the number of revolutions of the fan 9 and the flow rate of the cooling water, in accordance with the drop amount of the temperature of the cooling water. For example, as the drop amount of the temperature of the cooling water with respect to the previous measurement result becomes greater, the decrease amounts of the number of revolutions of the fan 9 and the flow rate of the cooling water, each determined on the basis of the result of specifying the amount of discharged heat, are increased. Furthermore, in one example, in a case where the temperature of the cooling water drops as compared to the previous measurement result, the processing execution unit 21 determines that the actual amount of heat discharged from the heat source into the cooling water is smaller than the amount of heat radiated in the radiator 7 and the actual amount of discharged heat is smaller than the result of specifying the amount of heat discharged into the cooling water in the heat source.

FIG. 8 is a block diagram schematically illustrating, by using functional blocks, an example of processing relating to cooling of the heat source, which is performed by the processing execution unit 21 of the cooling control device 20 in the embodiment. In the embodiment, the processing relating to cooling of the heat source is performed as described above, and as shown in FIG. 8, the amount of heat discharged from the heat source into the cooling water flowing through the flow path 6 is specified on the basis of the operation state of the heat source. The number of revolutions of the fan 9 that blows air into the radiator, and the flow rate of the cooling water into the radiator 7 inside the flow path 6 are then controlled on the basis of the result of specifying the amount of heat discharged from the heat source. The temperature of the cooling water is adjusted by controlling the number of revolutions of the fan 9 and the flow rate of the cooling water into the radiator 7.

In one example shown in FIG. 8, the temperature of the cooling water is measured. The number of revolutions of the fan 9 and the flow rate of the cooling water into the radiator 7 are then controlled on the basis of the measurement result of the temperature of the cooling water in addition to the specified amount of discharged heat. Therefore, the control unit 25 performs feedback control on the temperature of the cooling water in a state in which the number of revolutions of the fan 9 and the flow rate of the cooling water are controlled on the basis of the result of specifying the amount of heat discharged from the heat source. In a case where the temperature of the cooling water is changed in a state in which the number of revolutions of the fan 9 and the flow rate of the cooling water are controlled on the basis of a result of specifying the amount of heat discharged from the heat source, the control unit 25 controls the number of revolutions of the fan 9 and the flow rate of the cooling water on the basis of a temporal change in the temperature of the cooling water.

Herein, described as a comparative example is an example in which control for keeping the temperature of the cooling water constant is performed only through feedback control on the temperature of the cooling water without specifying the amount of heat discharged from the heat source into the cooling water and performing control based on a result of specifying the amount of heat from the heat source. The comparative example controls the number of revolutions of the fan 9 and the flow rate of the cooling water into the radiator 7 only on the basis of a temporal change in the temperature of the cooling water.

FIG. 9 is a schematic diagram showing an example of temporal changes in the temperature of the cooling water and the amount of energy used in control in a state in which the control for keeping the temperature of the cooling water constant is performed in the comparative example. FIG. 10 is a schematic diagram showing an example of temporal changes in the temperature of the cooling water and the amount of energy used in control in a state in which the control for keeping the temperature of the cooling water constant is performed in the embodiment. FIGS. 9 and 10 each show a graph in which an abscissa axis, an ordinate axis on the left side, and an ordinate axis on the right side indicate time, the temperature of the cooling water, and the amount of energy used in the control, respectively. In FIGS. 9 and 10, a temporal change in the temperature of the cooling water is indicated by a broken line, and a temporal change in the amount of energy used in the control is indicated by a solid line. Furthermore, the amount of energy used in the control includes energy consumed to rotate the fan 9, energy consumed by the pump 8 for circulating the cooling water, etc., and is indicated in, for example, W (watt).

As shown in FIG. 9, under control according to the comparative example, a sharp rise, a sharp decrease, and the like in the temperature of the cooling water are prone to occur. In a case of, e.g., performing control for keeping the temperature of the cooling water constant at a reference temperature, overshoot, in which the temperature of the cooling water greatly exceeds the reference temperature, undershoot, in which the temperature of the cooling water greatly falls below the reference temperature, and the like are prone to occur. Furthermore, under the control according to the comparative example, since a sharp rise and a sharp decrease in the temperature of the cooling water are prone to occur, the amount of energy used in the control tends to increase.

On the other hand, under the control according to the embodiment, the operation relating to cooling of the heat source is controlled on the basis of a result of specifying the amount of heat discharged from the heat source into the cooling water. Therefore, as shown in FIG. 10, a sharp rise, a sharp decrease, and the like in the temperature of the cooling water hardly occur. In a case of, e.g., performing the control for keeping the temperature of the cooling water constant at the reference temperature, the aforementioned overshoot, undershoot, and the like hardly occur. Furthermore, under the control according to the embodiment, since a sharp rise and a sharp decrease in the temperature of the cooling water hardly occur, the amount of energy used in the control decreases.

As described above, according to the embodiment, the amount of heat discharged from the heat source into the cooling water flowing through the flow path 6 is specified on the basis of the operation state of the heat source such as the motor 2, the battery 3, or the like, and at least one of the number of revolutions of the fan 9 that blows air into the radiator 7 and the flow rate of the cooling water into the radiator 7 inside the flow path 6 is controlled on the basis of the specified amount of discharged heat. Therefore, by performing the control for keeping the temperature of the cooling water constant on the basis of the result of specifying (the result of predicting) the amount of heat discharged from the heat source, the temperature of the cooling water can be kept constant or substantially constant over time without causing or almost without causing a sharp rise or decrease in the temperature of the cooling water. Under the control in which the temperature of the cooling water is kept constant on the basis of the specified amount of discharged heat, the amount of energy to be used can be appropriately reduced.

Furthermore, in the embodiment, at least one of the number of revolutions of the fan 9 and the flow rate of the cooling water is controlled such that a difference between the specified amount of discharged heat and the amount of heat radiated in the radiator 7 falls within a predetermined range, on the basis of the result of specifying the amount of heat discharged from the heat source and information indicating a relationship between the amount of heat radiated in the radiator 7 and both the number of revolutions of the fan 9 and the flow rate of the cooling water. Therefore, in the cooling mechanism (5A or 5B), the operation is appropriately controlled such that the amount of heat radiated having the same or substantially the same magnitude as a result of specifying the amount of heat discharged from the heat source is radiated in the radiator 7.

Furthermore, in one example of the embodiment, if, in a state in which at least one of the number of revolutions of the fan 9 and the flow rate of the cooling water into the radiator 7 is controlled on the basis of a result of specifying the amount of heat discharged from the heat source, the temperature of the cooling water changes, at least one of the number of revolutions of the fan 9 and the flow rate of the cooling water is controlled on the basis of a temporal change in the temperature of the cooling water. Therefore, even in a case where a result of specifying the amount of heat discharged into the cooling water in the heat source deviates from the actual amount of discharged heat, a change in temperature due to the deviation of the specifying amount from the actual amount of discharged heat is appropriately corrected. That is, control for keeping the temperature of the cooling water constant over time is appropriately performed in consideration of the influence of the deviation of the specifying amount of heat discharged from the actual amount of discharged heat.

Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.