Patent Publication Number: US-2022234422-A1

Title: Vehicle cooling system

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2021-010222 filed on Jan. 26, 2021, which is incorporated herein by reference in its entirety including the specification, claims, drawings, and abstract. 
     TECHNICAL FIELD 
     The present disclosure relates to a vehicle cooling system for cooling a running battery, a power control unit, and the air inside a vehicle cabin. 
     BACKGROUND 
     For example, JP 2013-199251A discloses a vehicle cooling system known as a system for cooling a running battery (hereinafter referred to as a battery) and the air inside a vehicle cabin with an air conditioning system (an air conditioning operation) in a vehicle. Specifically, upon detection of a high battery cooling load, the vehicle cooling system decreases the cooling capability of the air conditioning system to thereby enhance cooling capability to cool the running battery. 
     Another known example of vehicle cooling systems is a system for cooling, for example, a battery and a power control unit (hereinafter abbreviated as PCU) and also for cooling the air inside a vehicle cabin with an air conditioning system. In this vehicle cooling system, a refrigeration cycle device circulates refrigerant to cool the battery and the air inside the vehicle cabin, while a cooling device circulates coolant to cool the PCU. 
     In the above-described vehicle cooling system, the radiator of the cooling device is disposed downstream, with respect to an airflow, from the condenser of the refrigeration cycle device to cool the radiator of the cooling device with the airflow having passed through the condenser of the refrigeration cycle device. With this disposition, for example, in the case where a compressor is driven at a high rotation speed to cool the battery with priority, the condensation temperature of the condenser becomes high, which leads to high temperature of the air having passed through the condenser. This decreases the cooling capability to cool the PCU. 
     In the above-described vehicle cooling system, an evaporating unit for cooling the battery and an evaporating unit for cooling the air inside the vehicle cabin are disposed parallel to each other, and a flow regulating valve adjusts the ratio in amount between the refrigerants passing through the respective evaporating units. Accordingly, increasing the amount of refrigerant circulating to cool the battery in order to cool the battery with priority leads to a decrease in the amount of refrigerant circulating to cool the vehicle cabin. This decreases the cooling capability to cool the vehicle cabin. 
     SUMMARY 
     In other words, as cooling the battery, cooling the PCU, and cooling the air inside the vehicle cabin have a trade-off relationship in the above-described vehicle cooling system, it is desired to cool the battery, the PCU, and the air inside the vehicle cabin with favorable balance, depending on the situation. 
     In view of the above, an object of the present disclosure is to provide a vehicle cooling system that determines the level of priority in cooling a battery, a PCU, and the air inside a vehicle cabin, depending on the situation, to thereby cool the battery, the PCU, and the air inside the vehicle cabin with favorable balance. 
     According to one aspect of the present disclosure, there is provided a vehicle cooling system including a refrigeration cycle device having a first evaporating unit for cooling the running battery of a vehicle, a second evaporating unit connected parallel to the first evaporating unit, the second evaporating unit being for cooling the air inside a vehicle cabin, a regulating valve for adjusting the ratio in amount between the refrigerant passing through the first evaporating unit and the refrigerant passing through the second evaporating unit, and a condenser for being cooled with airflow; a cooling device for cooling the power control unit of the vehicle with coolant, the cooling device having a heat exchanger disposed downstream, with respect to the airflow, from the condenser, the heat exchanger being for cooling the coolant with the airflow; and a power control unit temperature estimation unit for estimating the temperature of the power control unit, wherein in the case where the temperature of the battery is equal to or higher a predetermined temperature, the battery is cooled with priority, in the case where the temperature of the power control unit, estimated by the power control unit temperature estimation unit, is equal to or higher than another predetermined temperature, the power control unit is cooled with priority, and in the case where the temperature of the battery is lower than the predetermined temperature, and the temperature of the power control unit, estimated by the power control unit temperature estimation unit, is less than the other predetermined temperature, the air inside the vehicle cabin is cooled with priority. 
     In the vehicle cooling system according to the present disclosure, in the case where the battery is cooled with priority, the amount of refrigerant circulating through the refrigeration cycle device may be increased, and the amount of refrigerant passing through the first evaporating unit may be increased with the regulating valve. 
     In the vehicle cooling system according to the present disclosure, in the case where the power control unit is cooled with priority, the amount of refrigerant passing through the condenser may be decreased to lower the temperature of the airflow having passed through the condenser. 
     In the vehicle cooling system according to the present disclosure, in the case where the air inside the vehicle cabin is cooled with priority, the amount of refrigerant circulating through the refrigeration cycle device may be increased and the amount of refrigerant passing through the second evaporating unit may be increased with the regulating valve. 
     According to a vehicle cooling system disclosed in the present disclosure, the level of priority in cooling the battery, the PCU, and the air inside the vehicle cabin is determined based on the temperature of the battery and the temperature of the coolant to cool the PCU. This arrangement makes it possible to prevent deceleration in the speed of the vehicle due to increased temperature of the battery and/or a decrease in the running capability of the vehicle due to restricted output attributed to excessive heating of the PCU, and so forth. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiment(s) of the present disclosure will be described based on the following figures, wherein: 
         FIG. 1  is a schematic view of an exemplary vehicle cooling system according to an embodiment; 
         FIG. 2  is a block diagram illustrating the structure of a control device; 
         FIG. 3  is a table indicating which of cooling a battery, cooling a PCU, and an air conditioning operation should be conducted with priority, depending on the temperature of a battery and the temperature of coolant to cool the PCU; 
         FIG. 4  is a table indicating a maximum rotation speed of a compressor in accordance with the temperature of the battery and the temperature of the coolant to cool the PCU; 
         FIG. 5  is a table indicating a maximum amount of an airflow from an air conditioning system in accordance with the temperature of the battery and the temperature of the coolant to cool the PCU; 
         FIG. 6  is a table indicating the state of operation of an inside-outside switching door of an air conditioning system in accordance with the temperature of the battery and the temperature of the coolant to cool the PCU; and 
         FIG. 7  is a table indicating a ratio in amount between refrigerants circulating to cool the battery and to conduct an air-conditioning operation, respectively, in accordance with the temperature of the battery and the temperature of the coolant to cool the PCU. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     One example of an embodiment of the present disclosure will now be described in detail. Note that specific shapes, materials, directions, numeric values, and so forth to be mentioned in the description below are only for illustration of examples to facilitate understanding of the present disclosure, and thus can be desirably modified depending on usage, purpose, specifications, and so forth. 
     Referring to  FIG. 1  and  FIG. 2 , a vehicle cooling system  10  according to an example of this embodiment will be described.  FIG. 1  is a schematic view of the vehicle cooling system  10 .  FIG. 2  is a block diagram of a control device  60 . 
     The vehicle cooling system  10  is mounted on a vehicle and cools a running battery (hereinafter referred to as a battery)  13  and a running power control unit (hereinafter abbreviated as PCU)  14 . The vehicle cooling system  10  also cools the air inside a vehicle cabin in communication with an air path  31  of an air conditioning system (an air conditioning operation). 
     The vehicle cooling system  10  determines the level of priority in cooling the battery  13 , the PCU  14 , and the air inside the vehicle cabin, based on the temperature of the battery  13  and the temperature of coolant to cool the PCU  14 , as to be described later in detail. This makes it possible to prevent deceleration in the speed of the vehicle due to increased temperature of the battery  13  and to prevent a decrease in the running capability of the vehicle due to restricted output attributed to excessive heating of the PCU  14 , or the like. 
     Although an electric vehicle that charges the battery  13  to run with a motor as a driving force is assumed in this example, this is not an exclusive example. For example, a vehicle that runs with an engine as a power source for running or a hybrid vehicle is applicable. 
     The vehicle cooling system  10  includes a refrigeration cycle device  20  and a cooling device  40  as illustrated in  FIG. 1 , and a control device, such as an electronic control unit, or ECU,  60 , illustrated in  FIG. 2 . Specifically, the refrigeration cycle device  20  circulates refrigerant to cool the battery  13  and the air inside the vehicle cabin. The cooling device  40  circulates coolant to cool the PCU  14 . 
     As illustrated in  FIG. 1  and  FIG. 2 , the control device  60  includes an operation unit  50 , a battery temperature sensor  51 , a coolant temperature sensor  52 , and an interior temperature sensor  53 . Specifically, the operation unit  50  can adjust at least the temperature set for the interior of the vehicle cabin. The battery temperature sensor  51  determines the temperature of the battery  13 . The coolant temperature sensor  52  functions as a power control unit temperature estimation unit for determining the temperature of the coolant to cool the PCU  14 . The interior temperature sensor  53  determines the temperature inside the vehicle cabin. Note that the power control unit temperature estimation unit may estimate the temperature of the PCU  14 , based on the state of processing by the PCU  14  or an instructed amount given to the PCU  14 . 
     As illustrated in  FIG. 1 , the refrigeration cycle device  20  includes a vapor compression refrigeration cycle circuit. Specifically, the refrigeration cycle device  20  evaporates refrigerant in a battery heat exchanger  25  provided as a first evaporating unit to cool the battery  13  with a battery cooling unit  29 . In addition, the refrigeration cycle device  20  evaporates refrigerant in an evaporator  26  provided as a second evaporating unit disposed parallel to the battery heat exchanger  25  to cool the air passing through the air path  31  of an air conditioning system to be described later to thereby cool the interior of the vehicle cabin. 
     The refrigeration cycle device  20  includes a compressor  21 , a condenser  22 , a fan  23 , an expansion valve  24 , the battery heat exchanger  25 , the evaporator  26 , and a flow regulating valve  27 . Specifically, the compressor  21  compresses refrigerant gas. The condenser  22  condenses the refrigerant gas into liquid refrigerant. The fan  23  supplies air to the condenser  22  and a radiator  43  to be described later. The expansion valve  24  expands the liquid refrigerant. The battery heat exchanger  25  cools the battery  13  with coolant. The evaporator  26  cools the air inside the air path  31  of the air conditioning system to be described later. The flow regulating valve  27  regulates the amount of refrigerant passing through the evaporator  26 . 
     The compressor  21  is driven with a rotary motor, and can change the amount of refrigerant gas to be discharged (outputted) by changing the rotation speed of the rotary motor. 
     The condenser  22  is a heat exchanger to be cooled with air outside the vehicle, supplied from the fan  23 , and condenses refrigerant gas into liquid refrigerant. Downstream, with respect to the airflow, from the fan  23  relative to the condenser  22 , the radiator  43  of the cooling device  40  to be described later is disposed. 
     The battery heat exchanger  25  is connected to a battery cooling circuit  28  that circulates coolant to cool the battery  13 . The battery cooling circuit  28  includes the battery cooling unit  29 , a coolant pump  30 , and the battery heat exchanger  25 , and is disposed close to the battery  13 . Specifically, the battery cooling unit  29  cools the battery with coolant. The coolant pump  30  circulates the coolant. The battery heat exchanger  25  cools the coolant. 
     The evaporator  26  is a heat exchanger that constitutes a part of an air conditioning system (not illustrated) in a vehicle cabin. The evaporator  26  is connected parallel to the battery heat exchanger  25 . The flow regulating valve  27  is disposed upstream of the evaporator  26 . 
     The air conditioning system includes the air path  31 , an inside-outside switching door, the evaporator  26 , a heater core, an air mix door, and a blower. Specifically, the air path  31  is used to introduce air cooled or heated into the interior of the vehicle cabin. The inside-outside switching door is used to introduce outside air into the air path  31 . The evaporator  26  is disposed on the air path  31  to cool the air passing through the air path  31 . The heater core is disposed on the air path  31  to heat the air passing through the air path  31 . The air mix door switches between supplying air to the heater core and supplying air to the evaporator  26 . The blower generates an airflow toward the inside of the vehicle cabin. 
     The flow regulating valve  27  regulates the amount of refrigerant passing through the evaporator  26 . Specifically, the flow regulating valve  27  can adjust the ratio in amount between refrigerants passing through the evaporator  26  and the battery heat exchanger  25 , respectively, in the refrigeration cycle device  20 . 
     The cooling device  40  includes a coolant circuit, and circulates coolant to cool the PCU  14 , as described above. The cooling device  40  includes a PCU cooling unit  41  for cooling the PCU  14 , a coolant pump  42  for circulating coolant, and the radiator  43  for cooling the coolant, and is disposed close to the PCU  14 . 
     With respect to an airflow from the fan, the radiator  43  is disposed downstream from the condenser  22  constituting a part of the refrigeration cycle device  20 , as described above. In other words, the radiator  43  is cooled with air having been supplied from the fan  23  and cooled the condenser  22 . 
     The operation unit  50  is provided inside the vehicle cabin to allow an occupant to conduct at least selection of either a cooling mode or a heating mode of the vehicle cooling system  10 , input of a temperature to be set in the vehicle cabin, selection of a defroster mode, and so forth. Information inputted or selected via the operation unit  50  is sent to the control device  60 . 
     The battery temperature sensor  51  is disposed close to the battery  13 , and determines the temperature of the battery  13 . A detection signal from the battery temperature sensor  51  is sent to the control device  60 . 
     The coolant temperature sensor  52  functioning as a power control unit temperature estimation unit is disposed on a pipe or the like near the PCU cooling unit  41  of the cooling device  40 , and determines the temperature of the coolant of the cooling device  40 . A detection signal from the coolant temperature sensor  52  is sent to the control device  60 . Note that the power control unit temperature estimation unit may estimate the temperature of the PCU  14 , based on the state of processing by the PCU  14  or an instructed amount given to the PCU  14 , as described above. 
     The interior temperature sensor  53  is provided inside the vehicle cabin, and determines the temperature inside the vehicle cabin. A detection signal from the interior temperature sensor  53  is sent to the control device  60 . 
     In the vehicle cooling system  10  in this example, for example, enhancement of the cooling capability to cool the battery  13  requires an increase in the amount of refrigerant passing through the battery heat exchanger  25 . In this case, the amount of refrigerant passing through the evaporator  26  decreases, so that the cooling capability of the air conditioning system decreases. 
     Similarly, enhancement of the cooling capability to cool the battery  13  requires an increase in the amount of refrigerant circulating through the entire refrigeration cycle device  20 . In this case, the condensation temperature of the condenser  22  increases, and so does the temperature of the air having passed through the condenser  22 . This decreases the cooling capability to cool the radiator  43 , so that the cooling capability to cool the PCU  14  decreases. 
     In the vehicle cooling system  10  in this example, enhancement of the cooling capability to cool the PCU  14  requires a decrease in the temperature of the air having passed through the condenser  22  of the refrigeration cycle device  20 , in order to enhance the cooling capability to cool the radiator  43 . This in turn requires a decrease in the amount of refrigerant circulating through the refrigeration cycle device  20 , in order to lower the condensation temperature of the condenser  22 . In this case, the cooling capability of the refrigeration cycle device  20  decreases, so that the cooling capability to cool the battery  13  and the cooling capability of the air conditioning system decrease. 
     In the vehicle cooling system  10  in this example, for example, enhancement of the cooling capability of the air conditioning system requires an increase in the amount of refrigerant passing through the evaporator  26 . In this case, the amount of refrigerant passing through the battery heat exchanger  25  decreases, so that the cooling capability to cool the battery  13  decreases. 
     Similarly, enhancement of the cooling capability of the air conditioning system requires an increase in the amount of refrigerant circulating through the entire refrigeration cycle device  20 . In this case, the condensation temperature of the condenser  22  increases, which increases the temperature of the air having passed through the condenser  22 . Accordingly, the cooling capability to cool the radiator  43  decreases, so that the cooling capability to cool the PCU  14  decreases. 
     In view of the above, the vehicle cooling system  10  in this example determines which of cooling the battery  13 , cooling the PCU  14 , and the air conditioning operation of an air conditioning system should be conducted with priority, based on the temperature of the battery  13  and the temperature of the coolant to cool the PCU  14 , and controls the refrigeration cycle device  20  and the cooling device  40  to thereby enhance cooling capability relevant to the determined operation to be conducted with priority, as to be described later in detail. 
     Referring to  FIG. 2  and  FIG. 3 , the structure of the control device  60  will now be described.  FIG. 3  is a table indicating which of cooling the battery  13 , cooling the PCU  14 , and the air conditioning operation of the air conditioning system should be conducted with priority, depending on the temperature of the battery  13  and the temperature of the coolant to cool the PCU  14 . 
     The control device  60  includes an operation unit, such as a Central Processing Unit (CPU); and a memory unit, such as a Random Access Memory (RAM), a Read Only Memory (ROM), or the like, and executes signal processing according to a program stored beforehand in the ROM, using the temporary storage function of the RAM. 
     The control device  60  is connected to the operation unit  50 , the battery temperature sensor  51 , the coolant temperature sensor  52 , and the interior temperature sensor  53 , or the like, to receive signals sent from these units. In addition, the control device  60  is connected to the compressor  21 , fan  23 , expansion valve  24 , and flow regulating valve  27  of the refrigeration cycle device  20 , the coolant pump  30  of the battery cooling circuit  28 , and a circuit of the coolant pump  42  of the cooling device  40 , or the like, to send signals to these respective units. 
     The control device  60  includes a battery priority cooling unit  61 , a PCU priority cooling unit  62 , a battery and PCU priority cooling unit  63 , and an air conditioning operation priority unit  64 . Specifically, the battery priority cooling unit  61  cools the battery  13  with priority. The PCU priority cooling unit  62  cools the PCU  14  with priority. The battery and PCU priority cooling unit  63  cools the battery  13  and the PCU  14  with priority. The air conditioning operation priority unit  64  conducts the air conditioning operation of the air conditioning system with priority. 
     As illustrated in  FIG. 3 , the battery priority cooling unit  61  has a function of increasing the amount of refrigerant passing through the battery heat exchanger  25  to thereby enhance the cooling capability to cool the battery  13  with priority when the temperature of the battery  13  is equal to or higher than a first predetermined temperature Tb 1  (for example, 51° C.) and the temperature of the coolant is less than a first predetermined temperature Tr 1  (for example, 61° C.). 
     Specifically, for example, the battery priority cooling unit  61  applies control, for example, by increasing the rotation speed of the compressor  21  of the refrigeration cycle device  20  or increasing the amount of refrigerant passing through the battery heat exchanger  25  through adjustment with the flow regulating valve  27  of the refrigeration cycle device  20 , and so forth. 
     This control enables enhancement of the cooling capability to cool the battery  13 , thus preventing deceleration of the running speed of the vehicle due to increased temperature of the battery  13 . 
     As illustrated in  FIG. 3 , the PCU priority cooling unit  62  has a function of decreasing the amount of refrigerant circulating through the refrigeration cycle device  20  to thereby enhance the cooling capability to cool the PCU  14  with priority when the temperature of the battery  13  is less than the first predetermined temperature Tb 1  and the temperature of the coolant is equal to or higher than the first predetermined temperature Tr 1 . 
     Specifically, for example, the PCU priority cooling unit  62  applies control, for example, by decreasing the rotation speed of the compressor  21  of the refrigeration cycle device  20 , by decreasing the rotation speed of the blower of the air conditioning system for introducing air into the vehicle cabin to thereby decrease the amount of air to be introduced into the vehicle cabin, or by fully closing the inside-outside switching door of the air conditioning system upon detection of high outside temperature to thereby decrease a cooling load in cooling the vehicle cabin, or the like. 
     Such control enables enhancement of the cooling capability to cool the PCU  14 . Consequently, it is possible to prevent a decrease in the running capability of the vehicle due to restricted output from a drive motor or the like attributed to excessive heating of the PCU  14 . Further, as it is possible to enhance the cooling capability to cool the PCU  14  without changing the capacities of the PCU cooling unit  41  and the radiator  43  of the cooling device  40 , the radiator  43  in this embodiment can have a smaller capacity than that of a currently available typical radiator. 
     As illustrated in  FIG. 3 , the battery and PCU priority cooling unit  63  has a function of adjusting an output from the refrigeration cycle device  20  in such a manner that enables cooling of both the battery  13  and the PCU  14  when the temperature of the battery  13  is equal to or higher than the first predetermined temperature Tb 1  and the temperature of the coolant is equal to or higher than the first predetermined temperature Tr 1 . 
     As illustrated in  FIG. 3 , the air conditioning operation priority unit  64  has a function of increasing the amount of refrigerant passing through the evaporator  26  to thereby enhance the cooling capability of the air conditioning system with priority when the temperature of the battery  13  is less than the first predetermined temperature Tb 1  and the temperature of the coolant is less than the first predetermined temperature Tr 1 . 
     Specifically, for example, the air conditioning operation priority unit  64  applies control, for example, by increasing the rotation speed of the compressor  21  of the refrigeration cycle device  20  or by increasing the amount of refrigerant passing through the evaporator  26  through adjustment with the flow regulating valve  27  of the refrigeration cycle device  20 , or the like. 
     Such control enables enhancement of the cooling capability to cool the air inside the vehicle cabin. In other words, it is possible to satisfy comfortability of an occupant when there is no need to enhance the cooling capability to cool the battery  13  or the PCU  14 . 
     Referring to  FIG. 4 , cooling control according to one example of this embodiment will be described.  FIG. 4  is a table indicating a maximum rotation speed of the compressor  21  of the refrigeration cycle device  20  in accordance with the temperature of the battery  13  and the temperature of the coolant to cool the PCU  14 . 
     In this example, which of cooling the battery  13 , cooling the PCU  14 , and the air conditioning operation should be conducted with priority is determined, based on the temperature of the battery  13  and the temperature of the coolant, and the maximum rotation speed of the compressor  21  of the refrigeration cycle device  20  is then changed so as to enhance cooling capability relevant to the determined operation to be conducted with priority. Assume below that the maximum rotation speed Nmax (for example, 8000 rpm) of the compressor  21  in a normal operation is set. 
     As illustrated in  FIG. 4 , in the case where the temperature of the battery  13  is equal to or higher than the first predetermined temperature Tb 1  (for example, 51° C.), the maximum rotation speed Nmax of the compressor  21  is maintained in order to enhance the cooling capability to cool the battery  13  with priority. With this arrangement, the amount of refrigerant circulating through the entire refrigeration cycle device  20  is tolerated up to the maximum amount for circulation at the maximum rotation speed Nmax of the compressor  21 . Accordingly, the amount of refrigerant passing through the battery heat exchanger  25  increases, to thereby enhance the cooling capability to cool the battery  13 . 
     In the above, in the case where the temperature of the coolant is equal to or higher than a second predetermined temperature Tr 2  (for example, 64° C.), the maximum rotation speed of the compressor  21  is decreased by an amount N 1  (for example, 2000 rpm) as the PCU  14  as well needs to be cooled, although cooling the battery  13  is still prioritized. In other words, in the case where the temperature of the battery  13  is equal to or higher than the first predetermined temperature Tb 1 , and the temperature of the coolant is equal to or higher than the second predetermined temperature Tr 2 , the maximum rotation speed of the compressor  21  is set to Nmax-N 1  or greater in order to cool both the battery  13  and the PCU  14 . 
     In the case where the temperature of the battery  13  is less than the first predetermined temperature Tb 1  and the temperature of the coolant is equal to or higher than the second predetermined temperature Tr 2 , the maximum rotation speed of the compressor  21  is set to a speed slower by an amount N 2  (for example, 3000 rpm) in order to enhance the cooling capability to cool the PCU  14  with priority. 
     With this arrangement, the amount of refrigerant circulating through the refrigeration cycle device  20  decreases to a predetermined amount or less for circulation that is less than the maximum amount of the circulating refrigerant. Accordingly, the condensation temperature of the condenser  22  lowers, and so does the temperature of the air having passed through the condenser  22 . This enhances the cooling capability to cool the radiator  43 , thereby enhancing the cooling capability of the cooling device  40 , which in turn enhances the cooling capability to cool the PCU  14 . 
     In the case where the temperature of the battery  13  is less than the first predetermined temperature Tb 1 , and the temperature of the coolant is less than the first predetermined temperature Tr 1 , the maximum rotation speed Nmax of the compressor  21  is maintained in order to enhance the cooling capability of the air conditioning system with priority. With this arrangement, the amount of refrigerant circulating through the entire refrigeration cycle device  20  is tolerated up to the maximum amount for circulation at the maximum rotation speed Nmax of the compressor  21 . Accordingly, the amount of refrigerant passing through the evaporator  26  increases, thereby enhancing the cooling capability to cool the air inside the vehicle cabin. 
     Referring to  FIG. 5 , cooling control according to another example of the embodiment will now be described.  FIG. 5  is a table indicating a maximum amount of air to be introduced into the vehicle cabin from the blower of the air conditioning system in accordance with the temperature of the battery  13  and the temperature of the coolant to cool the PCU  14 . 
     In this example, which of cooling the battery  13 , cooling the PCU  14 , and the air conditioning operation should be conducted with priority is determined, based on the temperature of the battery  13  and the temperature of the coolant to cool the PCU  14 , and the maximum amount of air to be supplied from the blower of the air conditioning system is changed to thereby enhance the cooling capability relevant to the determined operation to be conducted with priority. Assume below that the maximum amount Φmax (for example, 460 m 3 /h) of air to be supplied from the blower in the air conditioning operation of the air conditioning system is set. 
     As illustrated in  FIG. 5 , in the case where the temperature of the battery  13  is equal to or higher than the first predetermined temperature Tb 1  (for example, 51° C.), the amount of air to be supplied from the blower is set to an amount less than the maximum amount Φmax by an amount Φ 1  (for example, 30 m 3 /h) in order to enhance the cooling capability to cool the battery  13  with priority. Similarly, in the case where the temperature of the battery  13  is equal to or higher than a second predetermined temperature Tb 2  (for example, 54° C.), the amount of air to be supplied from the blower is set to an amount less than the maximum amount Φmax by an amount Φ 2  (for example, 60 m 3 /h). 
     With this arrangement, the amount of refrigerant passing through the evaporator  26  decreases to a predetermined amount or less for circulation that is less than the amount of refrigerant passing through the evaporator  26  at the time when the maximum amount Φmax of air is supplied from the blower. This increases the amount of refrigerant passing through the battery heat exchanger  25 , thereby enhancing the cooling capability to cool the battery  13 . 
     In the case where the temperature of the battery  13  is less than the first predetermined temperature Tb 1  and the temperature of the coolant of the PCU  14  is equal to or higher than the second predetermined temperature Tr 2  (for example, 64° C.), the amount of air to be supplied from the blower is set to an amount less than the maximum amount Φmax by an amount Φ 2  in order to enhance the cooling capability to cool the PCU  14  with priority over the battery  13  and the air inside the vehicle cabin. 
     With this arrangement, the amount of refrigerant circulating through the refrigeration cycle device  20  decreases to a predetermined amount or less for circulation that is less than the amount of refrigerant circulating through the refrigeration cycle device  20  at the time when the maximum amount Φmax of air is supplied from the blower. This decreases the condensation temperature of the condenser  22  and thus the temperature of the air having passed through the condenser  22 . This enhances the cooling capability to cool the radiator  43 , to thereby enhance the cooling capability of the cooling device  40 , and in turn enhancing the cooling capability to cool the PCU  14 . 
     In the case where the temperature of the battery  13  is less than the first predetermined temperature Tb 1  and the temperature of the coolant is less than the second predetermined temperature Tr 2 , the maximum amount Φmax of air from the blower is maintained in order to enhance the cooling capability of the air conditioning system with priority. With this arrangement, the amount of refrigerant passing through the evaporator  26  is tolerated up to a predetermined amount for circulation, so that the cooling capability to cool the air inside the vehicle cabin is enhanced. 
     Referring to  FIG. 6 , cooling control according to another example of an embodiment will be described.  FIG. 6  is a table indicating the state of operation of the inside-outside switching door of the air path  31  of the air conditioning system in accordance with the temperature of the battery  13  and the temperature of the coolant to cool the PCU  14 . 
     In this example, which of cooling the battery  13 , cooling the PCU  14 , and the air conditioning operation should be conducted with priority is determined, based on the temperature of the battery  13  and the temperature of the coolant to cool the PCU  14 , and the degree of opening of the inside-outside switching door of the air path  31  of the air conditioning system is then controlled so as to enhance the cooling capability relevant to the determined operation to be conducted with priority. This embodiment is effective when the temperature of the air outside the vehicle is higher than that of the air inside the vehicle cabin. 
     As illustrated in  FIG. 6 , in the case where the temperature of the battery  13  is equal to or higher than the first predetermined temperature Tb 1  (for example, 51° C.) or in the case where the temperature of the coolant is equal to or higher than the first predetermined temperature Tr 1  (for example, 61° C.), the inside-outside switching door is fully closed to shut off introduction of the outside air into the vehicle cabin. 
     With this arrangement, a cooling load in cooling the air inside the vehicle cabin decreases. Accordingly, the amount of refrigerant passing through the evaporator  26  decreases, while the amount of refrigerant passing through the battery heat exchanger  25  increases. This enhances cooling capability to cool the battery  13 . Meanwhile, the amount of refrigerant circulating through the entire refrigeration cycle device  20  decreases, which decreases the condensation temperature of the condenser  22 . Accordingly, the temperature of the air having passed through the condenser  22  lowers, thereby enhancing the cooling capability to cool the radiator  43 . Hence, the cooling capability to cool the cooling device  40  is enhanced, thereby enhancing the cooling capability to cool the PCU  14 . 
     In the case where the temperature of the battery  13  is less than the first predetermined temperature Tb 1 , and the temperature of the coolant is less than the first predetermined temperature Tr 1 , the degree of opening of the inside-outside switching door is normally adjustable. 
     Referring to  FIG. 7 , cooling control according to another example of the embodiment will now be described.  FIG. 7  is a table indicating a ratio in amount between refrigerants passing through the evaporator  26  and the battery heat exchanger  25 , respectively, based on the temperature of the battery  13  and the temperature of the coolant to cool the PCU  14 . Note that the ratio is adjusted with the flow regulating valve  27 . 
     In this example, which of cooling the battery  13 , cooling the PCU  14 , and the air conditioning operation should be conducted with priority is determined, based on the temperature of the battery  13  and the temperature of the coolant to cool the PCU  14 , and the flow regulating valve  27  is then controlled so as to enhance the cooling capability relevant to the determined operation to be conducted with priority. 
     As illustrated in  FIG. 7 , in the case where the temperature of the battery  13  is equal to or higher than the second predetermined temperature Tb 2  (for example, 51° C.), the flow regulating valve  27  is adjusted such that the ratio in amount between the refrigerants passing through the evaporator  26  and the battery heat exchanger  25 , respectively, is set to 4:6; in other words, such that a larger amount of refrigerant passes through the battery heat exchanger  25  than through the evaporator  26 . This arrangement increases the amount of refrigerant passing through the battery heat exchanger  25 , thereby enhancing the cooling capability to cool the battery  13 . 
     As illustrated in  FIG. 7 , in the case where the temperature of the battery  13  is less than the second predetermined temperature Tb 2  (for example, 51° C.) and equal to or higher than the first predetermined temperature Tb 1  (for example, 47° C.), the flow regulating valve  27  is adjusted such that the ratio in amount between the refrigerants passing through the evaporator  26  and the battery heat exchanger  25 , respectively, is set to 5:5; in other words, such that the same amount of refrigerants pass through the battery heat exchanger  25  and the evaporator  26 , respectively. This arrangement enables cooling of both the battery  13  and the air inside the vehicle cabin. 
     As illustrated in  FIG. 7 , in the case where the temperature of the battery  13  is less than the first predetermined temperature Tb 1  (for example, 47° C.), the flow regulating valve  27  is adjusted such that the ratio in amount between refrigerants passing through the evaporator  26  and the battery heat exchanger  25 , respectively, is set to 9:1; in other words, such that a larger amount of refrigerant passes through the evaporator  26  than through the battery heat exchanger  25 . This arrangement increases the amount of refrigerant passing through the evaporator  26 , thereby enhancing the cooling capability to cool the air inside the vehicle cabin. 
     Note that the present disclosure is not limited to the above-described embodiment and its modified examples, and may be adapted to various modifications and improvements without departing from the scope defined in the following claims. 
     For example, the radiator  43  in this embodiment may be replaced with an air-cooling oil cooler or an intercooler of an inlet pipe, which may be disposed downstream, with respect to the airflow, from the condenser  22  of the refrigeration cycle device  20  to thereby implement the above-described cooling control.