Patent Publication Number: US-2020290427-A1

Title: Control device of vehicle cooling device

Description:
This application claims priority from Japanese Patent Application No. 2019-046501 filed on Mar. 13, 2019, the disclosure of which is herein incorporated by reference in its entirety. 
     FIELD OF THE INVENTION 
     The present invention relates to a vehicle cooling device cooling a drive unit and a storage battery and relates to a technique of suitably improving a cooling performance for the storage battery when the storage battery is in a charging state. 
     DESCRIPTION OF THE RELATED ART 
     A vehicle cooling device cooling both a drive unit and a storage battery is known. For example, this corresponds to a vehicle cooling device described in Patent Document 1. The vehicle cooling device described in Patent Document 1 includes a cooling circuit cooling both a drive unit including a drive motor and a drive circuit, for example, and a storage battery with a flowing coolant, a heat exchanger cooling the coolant returning from the cooling circuit, and an electric pump sending out the coolant cooled by the heat exchanger to the cooling circuit. Patent Document 1 describes that when the storage battery is in a charging state, a flow rate of the coolant sent out to the cooling circuit by the electric pump is changed depending on a temperature of the coolant flowing through the cooling circuit. 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: Japanese Laid-Open Patent Publication No. 2015-21406 
     SUMMARY OF THE INVENTION 
     Technical Problem 
     However, since the vehicle cooling device as described in Patent Document 1 cools both the drive unit and the storage battery with the coolant flowing through the cooling circuit, the vehicle cooling device has a problem that when the storage battery is in a charging state and the storage battery is desirably preferentially cooled, a cooling performance for cooling the storage battery is deteriorated by a heat transferred from the drive unit to the coolant. This may cause a charging failure in the storage battery, such as limitation of charge amount and extension of charging time. 
     The present invention was conceived in view of the situations and it is therefore an object of the present invention to provide a control device of a vehicle cooling device configured to suitably improve a cooling performance of a storage battery when the storage battery is in a charging state. 
     Solution to Problem 
     To achieve the above object, a first aspect of the present invention provides a control device of a vehicle cooling device including (a) a drive-unit-cooling circuit cooling a drive unit with a flowing coolant, a storage-battery-cooling circuit cooling a storage battery with a flowing coolant, and a heat exchanger cooling the coolant returning from the drive-unit-cooling circuit and the coolant returning from the storage-battery-cooling circuit, the vehicle cooling device sending out the coolant cooled by the heat exchanger to the drive-unit-cooling circuit and the storage-battery-cooling circuit, wherein (b) when the storage battery is in a charging state, a flow of the coolant flowing through the drive-unit-cooling circuit is stopped. 
     A second aspect of the present invention provides the control device of the vehicle cooling device recited in the first aspect of the invention, wherein when the storage battery is in a non-charging state and a state of charge of the storage battery is equal to or less than a first value set in advance, the flow of the coolant flowing through the drive-unit-cooling circuit is stopped. 
     A third aspect of the present invention provides the control device of the vehicle cooling device recited in the second aspect of the invention, wherein when the storage battery is in the non-charging state and the state of charge of the storage battery is greater than the first value and equal to or less than a second value set in advance to be greater than the first value, the coolant is circulated in the drive-unit-cooling circuit. 
     A fourth aspect of the present invention provides the control device of the vehicle cooling device recited in any one of the first to third aspects of the invention, wherein when the storage battery is in the non-charging state and the temperature of the storage battery is equal to or greater than a predetermined temperature set in advance, the flow of the coolant flowing through the drive-unit-cooling circuit is stopped. 
     A fifth aspect of the present invention provides the control device of the vehicle cooling device recited in any one of the first to fourth aspects of the invention, wherein the coolant is a cooling water. 
     A sixth aspect of the present invention provides the control device of the vehicle cooling device recited in any one of the first to fifth aspects of the invention, wherein (a) the vehicle cooling device includes a first pump sending out the coolant cooled by the heat exchanger into the drive-unit-cooling circuit and a second pump sending out the coolant cooled by the heat exchanger into the storage-battery-cooling circuit, and wherein (b) when the storage battery is in the charging state, the first pump is stopped to stop the flow of the coolant in the drive-unit-cooling circuit. 
     A seventh aspect of the present invention provides the control device of the vehicle cooling device recited in the sixth aspect of the invention, wherein when the storage battery is in the non-charging state and the state of charge of the storage battery is greater than a first value set in advance and equal to or less than a second value set in advance to be greater than the first value, the first pump is driven to circulate the coolant in the drive-unit-cooling circuit. 
     Advantageous Effects of Invention 
     According to the control device of the vehicle cooling device recited in the first aspect of the invention, when the storage battery is in the charging state, the flow of the coolant flowing through the drive-unit-cooling circuit is stopped. Therefore, when the storage battery is in the charging state, the coolant having heat transferred from the drive unit does not return from the drive-unit-cooling circuit to the heat exchanger, so that the cooling performance for the storage battery can suitably be improved when the storage battery is in the charging state. 
     According to the control device of the vehicle cooling device recited in the second aspect of the invention, when the storage battery is in the non-charging state, and the state of charge of the storage battery is equal to or less than the first value, the flow of the coolant flowing through the drive-unit-cooling circuit is stopped. Therefore, even though the storage battery is in the non-charging state, when the state of charge of the storage battery is equal to or less than the first value so that the storage battery is predicted to be charged in the relatively near future, the cooling performance for the storage battery can be improved before start of charging of the storage battery. 
     According to the control device of the vehicle cooling device recited in the third aspect of the invention, when the storage battery is in the non-charging state, and the state of charge of the storage battery is greater than the first value and equal to or less than the second value, the coolant is circulated in the drive-unit-cooling circuit. Therefore, when the state of charge of the storage battery is greater than the first value and equal to or less than the second value and it is predicted that the storage battery is not charged in the relatively near future, the drive unit can be cooled, and therefore, both the cooling performance for the storage battery and the cooling performance for the drive unit can be improved when the storage battery is in the charging state. 
     According to the control device of the vehicle cooling device recited in the fourth aspect of the invention, when the storage battery is in the non-charging state, and the temperature of the storage battery is equal to or greater than the predetermined temperature, the flow of the coolant flowing through the drive-unit-cooling circuit is stopped. Therefore, when the temperature of the storage battery is equal to or greater than the predetermined temperature, the cooling performance for the storage battery can be improved before charging of the storage battery, and the storage battery can suitably be cooled. 
     According to the control device of the vehicle cooling device recited in the fifth aspect of the invention, the coolant is the cooling water, so that both the drive unit and the storage battery can suitably be cooled. 
     According to the control device of the vehicle cooling device recited in the sixth aspect of the invention, (a) the vehicle cooling device includes the first pump circulating the coolant cooled by the heat exchanger into the drive-unit-cooling circuit, and the second pump circulating the coolant cooled by the heat exchanger into the storage-battery-cooling circuit, and (b) when the storage battery is in the charging state, the first pump is stopped to stop the flow of the coolant in the drive-unit-cooling circuit. In other words, by stopping the first pump, the flow of the coolant in the drive-unit-cooling circuit can suitably be stopped when the storage battery is in the charging state. As a result, the coolant having heat transferred from the drive unit does not return to the heat exchanger from the drive-unit-cooling circuit, so that the cooling performance for the storage battery can suitably be improved when the storage battery is in the charging state. 
     According to the control device of the vehicle cooling device recited in the seventh aspect of the invention, when the storage battery is in the non-charging state, and the state of charge of the storage battery is greater than the first value and equal to or less than the second value, the first pump is driven to circulate the coolant into the drive-unit-cooling circuit. In other words, by driving the first pump, the coolant can suitably be circulated into the drive-unit-cooling circuit when it is predicted that the storage battery is not charged in the relatively near future. As a result, the drive unit can be cooled, so that both the cooling performance for the storage battery and the cooling performance for the drive unit can be improved when the storage battery is in the charging state. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram for explaining a general configuration of an electric automobile to which the present invention is preferably applied. 
         FIG. 2  is a diagram for explaining a configuration of a power train unit disposed in the electric automobile of  FIG. 1 . 
         FIG. 3  is a functional block diagram for explaining main portions of a control function included in an electronic control device of the electric automobile. 
         FIG. 4  is a flowchart for explaining an example of a control operation of a switching control of switching a drive state of a PTU cooling device in the electronic control device of  FIG. 3  during parking, for example. 
         FIG. 5  is a figure showing another example of the present invention and is a flowchart for explaining another example of the control operation of the switching control of switching the drive state of the PTU cooling device during parking. 
         FIG. 6  is a flowchart for explaining another example of the control operation of the switching control of switching a drive state of the PTU cooling device during parking. 
         FIG. 7  is a flowchart for explaining another example of the control operation of the switching control of switching a drive state of the PTU cooling device during parking. 
         FIG. 8  is a diagram for explaining another configuration of a power train unit disposed in a hybrid vehicle. 
     
    
    
     MODES FOR CARRYING OUT THE INVENTION 
     An example of the present invention will now be described in detail with reference to the drawings. 
     EXAMPLE 1 
       FIG. 1  is a diagram for explaining a general configuration of an electric automobile  10  to which the present invention is applied.  FIG. 2  is a diagram for explaining a general configuration of a power train unit (drive unit) PTU disposed in the electric automobile  10  of  FIG. 1 . The power train unit PTU is a drive unit driving a pair of left and right drive wheels not shown. 
     As shown in  FIG. 2 , the power train unit PTU includes an electric motor  12 , a power transmission mechanism  14 , and a housing case  16 . The electric motor  12  is a drive force source for running. The power transmission mechanism  14  transmits a drive force generated by the electric motor  12  to the pair of left and right drive wheels. The housing case  16  houses the electric motor  12 , the power transmission mechanism  14 , etc. The power transmission mechanism  14  includes a gear mechanism  18 , a differential gear device  20 , and a pair of left and right drive shafts  22 L,  22 R. The gear mechanism  18  is coupled to the electric motor  12  in a power transmittable manner. The differential device  20  is coupled to the gear mechanism  18  in a power transmittable manner. The drive shafts  22 L,  22 R are integrally fixed to the drive wheels and coupled to the differential device  20  in a power transmittable manner. 
     The electric motor  12  is a so-called motor generator having a function of a motor generating a mechanical power from an electric energy (electric power) and a function of a generator generating an electric energy from a mechanical power. As shown in  FIG. 2 , the electric motor  12  generates the drive force for running from an electric power supplied from a storage battery  26  via an inverter  24 . The electric motor  12  converts a driven force input from the drive wheel side through regeneration into an electric power and charges the storage battery  26  with the electric power via the inverter  24 . The storage battery  26  is a secondary battery, for example, a nickel-metal hydride battery or a lithium-ion battery. The power train unit PTU includes the inverter  24 . 
     As shown in  FIG. 1 , the electric automobile  10  includes the power train unit PTU, the storage battery  26 , a cooling device (vehicle cooling device)  28 , a battery control device  30 , a PTU control device  32 , etc. The cooling device  28  includes a PTU cooling device  34 , a battery cooling device  36 , and a heat exchanger  38 . 
     As shown in  FIG. 1 , the PTU cooling device  34  includes a PTU cooling circuit (drive-unit-cooling circuit)  40  cooling the power train unit PTU with flowing cooling water (coolant) W therein, and a first cooling water circulation pump (first pump)  42  sending out the cooling water W cooled by the heat exchanger  38  to the PTU cooling circuit  40 . Arrows Awl of solid lines of  FIG. 1  are arrows indicative of a flow of the cooling water W flowing in the PTU cooling circuit  40 . The PTU control device  32  is an electronic control device controlling, for example, the first cooling water circulation pump  42  and the power train unit PTU, for example, the electric motor  12 . The first cooling water circulation pump  42  is an electric pump driven by a first drive current (command signal) I 1  (see  FIG. 3 ) supplied from the PTU control device  32 . The cooling water W is, for example, long-life coolant or antifreeze. Therefore, in the PTU cooling device  34 , the cooling water W flows in the PTU cooling circuit  40  when the first cooling water circulation pump  42  is driven by the first drive current I 1  from the PTU control device  32 . As a result, heat of the power train unit PTU, for example, the electric motor  12  and the inverter  24 , is reduced by the cooling water W, and the power train unit PTU is cooled. 
     As shown in  FIG. 1 , the battery cooling device  36  includes a storage-battery-cooling circuit  44  cooling the storage battery  26  with the flowing cooling water W, and a second cooling water circulation pump (second pump)  46  sending out the cooling water W cooled by the heat exchanger  38  to the storage-battery-cooling circuit  44 . Arrows Aw 2  of solid lines of  FIG. 1  are arrows indicative of a flow of the cooling water W flowing in the storage-battery-cooling circuit  44 . The battery control device  30  is an electronic control device controlling, for example, the drive of the second cooling water circulation pump  46  and discharge or charge etc. of the storage battery  26 . The second cooling water circulation pump  46  is an electric pump driven by a second drive current (command signal)  12  (see  FIG. 3 ) supplied from the battery control device  30 . Therefore, in the battery cooling device  36 , the cooling water W flows in the storage-battery-cooling circuit  44  when the second cooling water circulation pump  46  is driven by the second drive current I 2  from the battery control device  30 . As a result, the heat of the storage battery  26  is reduced by the cooling water W, and the storage battery  26  is cooled. 
     As shown in  FIG. 1 , the heat exchanger  38  cools the cooling water W returning from the PTU cooling circuit  40  and the cooling water W returning from the storage-battery-cooling circuit  44 . The heat exchanger  38  allows air flowing from the outside of the electric automobile  10  and the cooling water W to exchange heat and thereby cools the cooling water W. Specifically, the heat exchanger  38  causes the cooling water W returning from the PTU cooling circuit  40  and the cooling water W returning from the storage-battery-cooling circuit  44  to pass through a common radiator in a mixed state so that the water is cooled by air. The heat exchanger  38  is provided with a cooling fan  38   a  for promoting cooling of the cooling water W. For example, when at least one of the PTU cooling device  34  and the battery cooling device  36  is driven, the cooling fan  38   a  is rotationally driven by an electronic control device (control device)  100  (see  FIG. 3 ). 
     A battery charging device  48  shown in  FIG. 1  is a quick charger or a normal charger disposed in a place where a vehicle is parked, for example. The quick charger is a device converting AC power supplied from an external AC power source of, for example, three-phase AC 200 V, into DC power and supplying the converted DC power, for example, at up to 500V, via a DC charging cable not shown to the storage battery  26 . The quick charger complies with the “CHAdeMO (registered trademark)” standard (hereinafter referred to as “CHAdeMO standard”). The CHAdeMO standard is an international standard for DC quick charging. The normal charger is a device supplying, for example, 200 V AC power supplied from an external AC power source of, for example, single-phase AC 200 V, via an AC charging cable not shown and the inverter  24  to the storage battery  26 . An arrow Aep of a broken line of  FIG. 1  is an arrow indicative of a flow of electric power supplied from the battery charging device  48 . Arrows As of dashed-dotted lines of  FIG. 1  are arrows indicative of a flow of a command signal in the electric automobile  10  and a flow of a command signal between the electric automobile  10  and the battery charging device  48 . 
     As shown in  FIG. 3 , the electronic control device  100  is configured to include a so-called microcomputer including a CPU, a RAM, a ROM, and an I/O interface, for example, and the CPU executes signal processes in accordance with a program stored in advance in the ROM, while utilizing a temporary storage function of the RAM, to provide various controls of the electric automobile  10 . The electronic control device  100  includes the battery control device  30  and the PTU control device  32 . The electronic control device  100  is supplied with various input signals detected by sensors disposed in the electric automobile  10 . For example, the signals input to the electronic control device  100  include: a signal indicative of a temperature Tm [° C.] of the power train unit PTU, for example, the temperature Tm [° C.] of the electric motor  12 , detected from a temperature sensor  102 ; signals indicative of a battery temperature That [° C], a battery input/output current Ibat [A], a battery voltage Vbat [V], etc. of the storage battery  26  detected by a battery sensor  104 ; a signal indicative of a shift operation position Psh of a shift lever (not shown) detected from a shift position sensor  106 ; and an ignition-on (IGON) signal for powering on the electric automobile  10  and an ignition-off (IGOFF) signal for powering off the electric automobile  10  detected from an ignition switch  108 . 
     The electronic control device  100  supplies various output signals to devices disposed in the electric automobile  10 . For example, the signals supplied from the electronic control device  100  to the portions include: the first drive current I 1  [A] supplied to the first cooling water circulation pump  42  for driving the PTU cooling device  34 , i.e., the first cooling water circulation pump  42 ; the second drive current I 2  [A] supplied to the second cooling water circulation pump  46  for driving the battery cooling device  36 , i.e., the second cooling water circulation pump  46 ; and a third drive current I 3  [A] supplied to an actuator  38   b  (see  FIG. 3 ) disposed in the cooling fan  38   a  for rotationally driving the cooling fan  38   a  of the heat exchanger  38 . 
     As shown in  FIG. 3 , the electronic control device  100  includes a battery cooling device control portion  110 , a PTU cooling device control portion  112 , and a battery charging determining portion  114 . The battery cooling device control portion  110  switches a drive state of the battery cooling device  36  in accordance with the battery temperature That [° C.] of the storage battery  26 . For example, when the battery temperature Tbat [° C.] is equal to or greater than a first predetermined temperature Tbat 1  [° C.] set in advance, the battery cooling device control portion  110  supplies the second drive current I 2  [A] to the second cooling water circulation pump  46  of the battery cooling device  36  and supplies the third drive current I 3  [A] to the actuator  38   b  of the cooling fan  38   a . As a result, both the second cooling water circulation pump  46  and the cooling fan  38   a  are driven, and the cooling water W cooled by the heat exchanger  38  flows through the storage-battery-cooling circuit  44  so that the storage battery  26  is cooled. For example, when the battery temperature Tbat [° C.] of the storage battery  26  detected from the battery sensor  104  is equal to or less than a second predetermined temperature Tbat 2  [° C.] set in advance, the battery cooling device control portion  110  stops supply of the second drive current I 2  [A] supplied to the second cooling water circulation pump  46  and stops supply of the third drive current I 3  [A] supplied to the actuator  38   b  of the cooling fan  38   a . This stops the second cooling water circulation pump  46  and stops the flow of the cooling water W flowing through the storage-battery-cooling circuit  44 . The second predetermined temperature Tbat 2  [° C.] is a temperature lower than the first predetermined temperature Tbat 1  [° C]. 
     The PTU cooling device control portion  112  switches a drive state of the PTU cooling device  34  in accordance with the temperature Tm [° C.] of the power train unit PTU, for example, the temperature Tm [° C.] of the electric motor  12 . For example, when the temperature Tm [° C.] is equal to or greater than a first predetermined temperature Tm 1  [° C.] set in advance, the PTU cooling device control portion  112  supplies the first drive current I 1  [A] to the first cooling water circulation pump  42  of the PTU cooling device  34  and supplies the third drive current I 3  [A] to the actuator  38   b  of the cooling fan  38   a . As a result, both the first cooling water circulation pump  42  and the cooling fan  38   a  are driven, and the cooling water W cooled by the heat exchanger  38  flows through the PTU cooling circuit  40  so that the power train unit PTU is cooled. For example, when the temperature Tm [° C.] of the electric motor  12  detected from the temperature sensor  102  is equal to or less than a second predetermined temperature Tm 2  [° C.] set in advance, the PTU cooling device control portion  112  stops supply of the first drive current I 1  [A] supplied to the first cooling water circulation pump  42  and stops supply of the third drive current I 3  [A] supplied to the actuator  38   b  of the cooling fan  38   a . This stops the first cooling water circulation pump  42  and stops the flow of the cooling water W flowing through the PTU cooling circuit  40 . The second predetermined temperature Tm 2  [° C.] is a temperature lower than the first predetermined temperature Tml [° C]. In the battery cooling device control portion  110  and the PTU cooling device control portion  112 , when at least one of the first drive current I 1  [A] and the second drive current I 2  [A] is supplied, the third drive current I 3  [A] is supplied, and when the supplies of both of the first drive current I 1  [A] and the second drive current I 2  [A] are stopped, the supply of the third drive current I 3  [A] is stopped. 
     The battery charging determining portion  114  determines whether the storage battery  26  is in a charging state or the storage battery  26  is in a non-charging state. In other words, the battery charging determining portion  114  determines whether the storage battery  26  is being charged or not. For example, in the case that the shift operation position Psh is a parking position P, that the electric automobile  10  is powered off by the ignition switch  108 , and that a connector disposed at an end portion of the DC charging cable of the quick charger is connected to a quick charging connector disposed on the electric automobile  10  so that DC power is supplied from the quick charger to the storage battery  26 , the battery charging determining portion  114  determines that the storage battery  26  is in the charging state. The charging state is a state in which the storage battery  26  is charged with an electric power supplied to the storage battery  26  from the battery charging device  48 , for example, the quick charger, regardless of an amount of electric power discharged from the storage battery  26 . The non-charging state is a state in which no electric power is supplied to the storage battery  26  from the battery charging device  48 , for example, the quick charger, so that the storage battery  26  is not charged, regardless of an amount of electric power discharged from the storage battery  26 . When the shift lever is operated to the parking position P, a parking lock mechanically preventing rotation of the drive wheels is activated by a parking mechanism (not shown) disposed in the electric automobile  10 . 
     The PTU cooling device control portion  112  includes a forced stop determining portion  112   a  and a forced drive determining portion  112   b . The forced stop determining portion  112   a  determines whether the PTU cooling device  34  needs to be forcibly stopped for improving a cooling performance of the battery cooling device  36  for the storage battery  26 . For example, when the battery charging determining portion  114  determines that the storage battery  26  is in the charging state, the forced stop determining portion  112   a  determines that the PTU cooling device  34  needs to be forcibly stopped. Additionally, when the battery charging determining portion  114  determines that the storage battery  26  is in the non-charging state and it is determined that a state of charge SOC [%] of the storage battery  26  at the time of determination of the storage battery  26  being in the non-charging state by the battery charging determining portion  114  is equal to or less than a first value SOC 1  [%] set in advance, the forced stop determining portion  112   a  determines that the PTU cooling device  34  needs to be forcibly stopped. The first value SOC 1  [%] is a value of the state of charge SOC [%] at which it is predicted that the storage battery  26  is highly likely to be charged in a relatively near future. The state of charge SOC [%] of the storage battery  26  is calculated from the battery temperature Tbat [° C], the battery input/output current That [A], and the battery voltage Vhat [V] of the storage battery  26  detected from the battery sensor  104  at the time of determination of the storage battery  26  being in the non-charging state by the battery charging determining portion  114 . Additionally, when the battery charging determining portion  114  determines that the storage battery  26  is in the non-charging state and it is determined that the battery temperature Tbat [° C.] of the storage battery  26  at the time of determination of the storage battery  26  being in the non-charging state by the battery charging determining portion  114  is equal to or greater than a third predetermined temperature (predetermined temperature) Tbat 3  [° C.] set in advance, the forced stop determining portion  112   a  determines that the PTU cooling device  34  needs to he forcibly stopped. The third predetermined temperature Tbat 3  [° C.] is a temperature higher than the first predetermined temperature Tbat 1  [° C]. 
     The forced drive determining portion  112   b  determines whether the PTU cooling device  34  needs to be forcibly driven so as to improve a cooling performance of the PTU cooling device  34  for the power train unit PTU while the cooling performance of the battery cooling device  36  for the storage battery  26  is kept being improved. For example, when the battery charging determining portion  114  determines that the storage battery  26  is in the non-charging state and it is determined that the state of charge SOC [%] of the storage battery  26  at the time of determination of the storage battery  26  being in the non-charging state by the battery charging determining portion  114  is greater than the first SOC 1  [%] and equal to or less than a second value SOC 2  [%] set in advance, the forced drive determining portion  112   b  determines that the PTU cooling device  34  needs to be forcibly driven. The second value SOC 2  [%] is a value of the state of charge SOC [%] larger than the first value SOC 1  [%], and the second value SOC 2  [%] is the state of charge SOC [%] at which it is predicted that the storage battery  26  is less likely to be charged in a relatively near future. 
     When the forced stop determining portion  112   a  determines that the PTU cooling device  34  needs to be forcibly stopped, the PTU cooling device control portion  112  stops the supply of the first drive current I 1  [A] to the PTU cooling device  34  (the first cooling water circulation pump  42 ) regardless of whether the first drive current I 1  [A] is being supplied-to the PTU cooling device  34 . This stops the first cooling water circulation pump  42  and stops the flow of the cooling water W flowing through the PTU cooling circuit  40 . 
     When the forced drive determining portion  112   b  determines that the PTU cooling device  34  needs to be forcibly driven, the PTU cooling device control portion  112  supplies the first drive current I 1  [A] to the PTU cooling device  34  regardless of whether the first drive current I 1  [A] is being supplied to the PTU cooling device  34 . As a result, the first cooling water circulation pump  42  is driven, and the cooling water W flows in the PTU cooling circuit  40 . When the forced drive determining portion  112   b  determines that the PTU cooling device  34  needs to be forcibly driven and the temperature Tm [° C.] of the electric motor  12  detected from the temperature sensor  102  is equal to or less than a third predetermined temperature Tm 3  [° C.] set in advance, the PTU cooling device control portion  112  stops the supply of the first drive current I 1  [A] to the PTU cooling device  34 . The third predetermined temperature Tm 3  [° C.] is a temperature lower than the second predetermined temperature Tm 2  [° C]. 
       FIG. 4  is a flowchart for explaining an example of a control operation in the electronic control device  100  of a switching control of the drive states of the PTU cooling device  34  during parking, for example. 
     First, at step (hereinafter, step will be omitted) S 1  corresponding to functions of the battery charging determining portion  114  and the forced stop determining portion  112   a , it is determined whether the storage battery  26  is being charged, i.e., whether the storage battery  26  is in the charging state. In other words, at S 1 , it is determined whether the PTU cooling device  34  needs to be forcibly stopped. If the determination of S 1  is affirmative, i.e., if the storage battery  26  is in the charging state, S 2  corresponding to the function of the PTU cooling device control portion  112  is executed. If the determination of S 1  is negative, i.e., if the storage battery  26  is in the non-charging state, S 3  corresponding to the function of the forced stop determining portion  112   a  is executed. 
     At S 3 , it is determined whether the battery temperature Tbat [° C.] of the storage battery  26  is equal to or greater than the third predetermined temperature Tbat 3  [° C]. In other words, at S 3 , it is determined whether the PTU cooling device  34  needs to be forcibly stopped. If the determination of S 3  is affirmative, i.e., if the battery temperature Tbat [° C.] of the storage battery  26  is equal to or greater than the third predetermined temperature Tbat 3  [° C], S 2  is executed. If the determination of S 3  is negative, i.e., if the battery temperature Tbat [° C.] of the storage battery  26  is lower than the third predetermined temperature Tbat 3  [° C], S 4  corresponding to the function of the forced stop determining portion  112   a  is executed. 
     At S 4 , it is determined whether the state of charge SOC [%] of the storage battery  26  is equal to or less than the first value SOC 1  [%]. In other words, at S 4 , it is determined whether the PTU cooling device  34  needs to be forcibly stopped. If the determination of S 4  is affirmative, i.e., if the state of charge SOC [%] of the storage battery  26  is equal to or less than the first value SOC 1  [%], S 2  is executed. If the determination of S 4  is negative, i.e., if the state of charge SOC [%] of the storage battery  26  is greater than the first value SOC 1  [%], S 5  corresponding to function of the forced drive determining portion  112   b  is executed. 
     At S 5 , it is determined whether the state of charge SOC [%] of the storage battery  26  is equal to or less than the second value SOC 2  [%]. In other words, at S 5 , it is determined whether the PTU cooling device  34  needs to be forcibly driven. If the determination of S 5  is affirmative, i.e., if the state of charge SOC [%] of the storage battery  26  is equal to or less than the second value SOC 2  [%], S 6  corresponding to the function of the PTU cooling device control portion  112  is executed. If the determination of S 5  is negative, i.e., if the state of charge SOC [%] of the storage battery  26  is greater than the second value SOC 2  [%], this routine is terminated. 
     At S 2 , the supply of the first drive current I 1  [A] to the PTU cooling device  34  is stopped regardless of whether the first drive current I 1  [A] is supplied to the PTU cooling device  34 . In other words, at S 2 , the PTU cooling device  34  is forcibly stopped. At S 6 , the first drive current I 1  [A] is supplied to the PTU cooling device  34  regardless of whether the first drive current I 1  [A] is supplied to the PTU cooling device  34 . In other words, at S 6 , the PTU cooling device  34  is forcibly driven. 
     As described above, according to the electronic control device  100  of the cooling device  28  of this example, when the storage battery  26  is in the charging state, the flow of the cooling water W flowing through the PTU cooling circuit  40  is stopped. Therefore, when the storage battery  26  is in the charging state, the cooling water W having heat transferred from the power train unit PTU does not return from the PTU cooling circuit  40  to the heat exchanger  38 , so that the cooling performance for the storage battery  26  can suitably be improved. 
     According to the electronic control device  100  of the cooling device  28  of this example, when the storage battery  26  is in the non-charging state, and the state of charge SOC [%] of the storage battery  26  is equal to or less than the first value SOC 1  [%] set in advance, the flow of the cooling water W flowing through the PTU cooling circuit  40  is stopped. Therefore, even though the storage battery  26  is in the non-charging state, when the state of charge SOC [%] of the storage battery  26  is equal to or less than the first value SOC 1  [%] so that the storage battery  26  is predicted to be charged in the relatively near future, the cooling performance for the storage battery  26  can be improved before start of charging of the storage battery  26 . 
     According to the electronic control device  100  of the cooling device  28  of this example, when the storage battery  26  is in the non-charging state, and the state of charge SOC [%] of the storage battery  26  is greater than the first value SOC 1  [%] and equal to or less than the second value SOC 2  [%], the cooling water W is circulated in the PTU cooling circuit  40 . Therefore, when the state of charge SOC [%] of the storage battery  26  is greater than the first value SOC 1  [%] and equal to or less than the second value SOC 2  [%] and it is predicted that the storage battery  26  is not charged in the relatively near future, the power train unit PTU can be cooled, and therefore, both the cooling performance for the storage battery  26  and the cooling performance for the power train unit PTU can be improved when the storage battery  26  is in the charging state. 
     According to the electronic control device  100  of the cooling device  28  of this example, when the storage battery  26  is in the non-charging state, and the battery temperature Tbat [° C.] of the storage battery  26  is equal to or greater than the third predetermined temperature Tbat 3  [° C.] set in advance, the flow of the cooling water W flowing through the PTU cooling circuit  40  is stopped. Therefore, when the battery temperature Tbat [° C.] of the storage battery  26  is equal to or greater than the third predetermined temperature Tbat 3  [° C], the cooling performance for the storage battery  26  can be improved before charging of the storage battery  26 , and the storage battery  26  can suitably be cooled. 
     According to the electronic control device  100  of the cooling device  28  of this example, the coolant flowing through the PTU cooling circuit  40  and the storage-battery-cooling circuit  44  is the cooling water W, so that both the power train unit PTU and the storage battery  26  can suitably be cooled. 
     According to the electronic control device  100  of the cooling device  28  of this example, the cooling device  28  includes the first cooling water circulation pump  42  circulating the cooling water W cooled by the heat exchanger  38  into the PTU cooling circuit  40 , and the second cooling water circulation pump  46  circulating the cooling water W cooled by the heat exchanger  38  into the storage-battery-cooling circuit  44 , and when the storage battery  26  is in the charging state, the first cooling water circulation pump  42  is stopped to stop the flow of the cooling water W through the PTU cooling circuit  40 . In other words, by stopping the first cooling water circulation pump  42 , the flow of the cooling water W in the PTU cooling circuit  40  can suitably be stopped when the storage battery  26  is charged. As a result, the cooling water W having heat transferred from the power train unit PTU does not return to the heat exchanger  38  from the PTU cooling circuit  40 , so that the cooling performance for the storage battery  26  can suitably be improved when the storage battery  26  is in the charging state. 
     According to the electronic control device  100  of the cooling device  28  of this example, when the storage battery  26  is in the non-charging state, and the state of charge SOC [%] of the storage battery  26  is greater than the first value SOC 1  [%] and equal to or less than the second value SOC 2  [%], the first cooling water circulation pump  42  is driven to circulate the cooling water W into the PTU cooling circuit  40 . In other words, by driving the first cooling water circulation pump  42 , the cooling water W can suitably be circulated into the PTU cooling circuit  40  when it is predicted that the storage battery  26  is not charged in the relatively near future. As a result, the power train unit PTU can be cooled, so that both the cooling performance for the storage battery  26  and the cooling performance for the power train unit PTU can be improved when the storage battery  26  is in the charging state. 
     Other examples of the present invention will then be described in detail with reference to the drawings. In the following description, the portions common to the examples are denoted by the same reference numerals and will not be described. 
     EXAMPLE 2 
     The electronic control device according to this example is substantially the same as the electronic control device  100  of Example 1 except that one condition is deleted in the forced stop determining portion  112   a  out of the determination conditions for determining the PTU cooling device  34  needing to be forcibly stopped. Specifically, even when the battery charging determining portion  114  determines that the storage battery  26  is in the non-charging state and the battery temperature Tbat [° C.] of the storage battery  26  is equal to or greater than the third predetermined temperature Tbat 3  [° C], the forced stop determining portion  112   a  determines that the PTU cooling device  34  does not need to be forcibly stopped. 
       FIG. 5  is a flowchart for explaining an example of the control operation of the switching control of switching the drive state of the PTU cooling device  34  in the electronic control device of this example during parking, for example. S 1 , S 2 , S 6  shown in  FIG. 5  have the same contents as S 1 , S 2 , S 6  shown in  FIG. 4 . Therefore, S 1 , S 2 , S 6  of  FIG. 5  will not be described. 
     At S 13  corresponding to the function of the forced stop determining portion  112   a , it is determined whether the state of charge SOC [%] of the storage battery  26  is equal to or less than the first value SOC 1  [%]. In other words, at S 13 , it is determined whether the PTU cooling device  34  needs to be forcibly stopped. If the determination of S 13  is affirmative, i.e., if the state of charge SOC [%] of the storage battery  26  is equal to or less than the first value SOC 1  [%], S 2  is executed. When the determination of S 13  is negative, i.e., when the state of charge SOC [%] of the storage battery  26  is greater than the first value SOC 1  [%], S 14  corresponding to the function of the forced drive determining portion  112   b  is executed. 
     At S 14 , it is determined whether the state of charge SOC [%] of the storage battery  26  is equal to or less than the second value SOC 2  [%]. In other words, at S 14 , it is determined whether the PTU cooling device  34  needs to be forcibly driven. If the determination of S 14  is affirmative, i.e., if the state of charge SOC [%] of the storage battery  26  is equal to or less than the second value SOC 2  [%], S 6  is executed. If the determination of S 14  is negative, i.e., if the state of charge SOC [%] of the storage battery  26  is greater than the second value SOC 2  [%], this routine is terminated. 
     EXAMPLE 3 
     The electronic control device of this example is substantially the same as the electronic control device of Example 2 except that the forced drive determining portion  112   b  is deleted. 
       FIG. 6  is a flowchart for explaining an example of the control operation of the switching control of switching the drive state of the PTU cooling device  34  in the electronic control device of this example during parking, for example. S 1 , S 2  shown in  FIG. 6  have the same contents as S 1 , S 2  shown in  FIG. 5 . Therefore, S 1 , S 2  of  FIG. 6  will not be described. 
     At S 23  corresponding to the function of the forced stop determining portion  112   a , it is determined whether the state of charge SOC [%] of the storage battery  26  is equal to or less than the first value SOC 1  [%]. In other words, at S 23 , it is determined whether the PTU cooling device  34  needs to be forcibly stopped. If the determination of S 23  is affirmative, i.e., if the state of charge SOC [%] of the storage battery  26  is equal to or less than the first value SOC 1  [%], S 2  is executed. When the determination of S 23  is negative, i.e., when the state of charge SOC [%] of the storage battery  26  is greater than the first value SOC 1  [%], this routine is terminated. 
     EXAMPLE 4 
     The electronic control device according to this example is substantially the same as the electronic control device of Example 3 except that one condition is deleted in the forced stop determining portion  112   a  out of the determination conditions for determining the PTU cooling device  34  needing to be forcibly stopped. Specifically, even when the battery charging determining portion  114  determines that the storage battery  26  is in the non-charging state and it is determined that the state of charge SOC [%] of the storage battery  26  at the time of determination of the storage battery  26  being in the non-charging state by the battery charging determining portion  114  is equal to or less than the first value SOC 1  [%], the forced stop determining portion  112   a  determines that the PTU cooling device  34  does not need to be forcibly stopped. 
       FIG. 7  is a flowchart for explaining an example of the control operation of the switching control of switching the drive state of the PTU cooling device  34  in the electronic control device of this example during parking, for example. S 2  shown in  FIG. 7  has the same content as S 2  shown in  FIG. 6 . Therefore, S 2  of  FIG. 7  will not be described. 
     At S 31  corresponding to the functions of the battery charging determining portion  114  and the forced stop determining portion  112   a , it is determined whether the storage battery  26  is in the charging state. In other words, at S 31 , it is determined whether the PTU cooling device  34  needs to be forcibly stopped. If the determination of S 31  is affirmative, i.e., if the the storage battery  26  is in the charging state, S 2  is executed. If the determination of S 31  is negative, i.e., if the storage battery  26  is in the non-charging state, this routine is terminated. 
     EXAMPLE 5 
       FIG. 8  is a diagram for explaining another example (Example 5) of the present invention and is a diagram for explaining a configuration of a power train unit (drive unit) PTU 1  disposed in a hybrid vehicle which is used instead of the power train unit PTU in the previous examples. The hybrid vehicle includes a cooling device (vehicle cooling device). The cooling device is substantially the same as the cooling device  28  of Example 1 except that the power train unit (drive unit) PTU 1  is cooled with the cooling water W flowing through the PTU cooling circuit  40 , i.e., for example, an engine  120 , a first electric motor  122 , a second electric motor  124 , and the inverter  24  are cooled with the cooling water W flowing through the PTU cooling circuit  40 . 
     Although the examples of the present invention have been described in detail with reference to the drawings, the present invention is also applied in other forms. 
     For example, in Example 1, the PTU cooling device control portion  112  switches the drive state of the PTU cooling device  34  in accordance with the temperature Tm [° C.] of the electric motor  12 . For example, a temperature sensor detecting temperature of the inverter  24  may be disposed in the electric automobile  10 , and the drive state of the PTU cooling device  34  may be switched in accordance with the temperature of the inverter  24 . In other words, the drive state of the PTU cooling device  34  may be switched in accordance with a temperature of a device constituting the power train unit PTU. 
     In Example 1, the first cooling water circulation pump  42  is an electric pump driven by the first drive current I 1 . [A] supplied from the electronic control device  100 . For example, the first cooling water circulation pump  42  may be a mechanical pump driven by the rotational drive of the electric motor  12 . Specifically, the electric automobile  10  may include an electromagnetic valve configured to supply the cooling water W discharged from the mechanical pump to flow into the PTU cooling circuit  40  and a clutch device disconnecting or connecting a power transmission path between the electric motor  12  and the drive wheels and, for example, when the cooling water W is caused to flow through the PTU cooling circuit  40  during parking, the electronic control device  100  may control the electromagnetic valve and the clutch device and rotationally drive the electric motor  12 . 
     Although the cooling water W is used to flow in the PTU cooling circuit  40  and the storage-battery-cooling circuit  44  in Example 1, a fluid such as oil may be allowed to flow instead of the cooling water W as the coolant, for example. 
     In Example 1, the battery charging determining portion  114  determines that the storage battery  26  is in the charging state when DC power is supplied from the quick charger to the storage battery  26 . However, for example, the battery charging determining portion  114  may determine that the storage battery  26  is in the charging state when DC power is supplied from the normal charger via the inverter  24  to the storage battery  26 . 
     The above description is merely an embodiment and the present invention can be implemented in variously modified and improved forms based on the knowledge of those skilled in the art. 
     REFERENCE SIGNS LIST 
       26 : storage battery 
       28 : cooling device (vehicle cooling device) 
       38 : heat exchanger 
       40 : PTU cooling circuit (drive-unit-cooling circuit) 
       42 : first cooling water circulation pump (first pump) 
       44 : storage-battery-cooling circuit 
       46 : second cooling water circulation pump (second pump) 
       100 : electronic control device (control device) 
       110 : battery cooling device control portion 
       112 : PTU cooling device control portion 
       112   a : forced stop determining portion 
       112   b : forced drive determining portion 
       114 : battery charging determining portion 
     PTU, PTU 1 : power train unit (drive unit) 
     SOC: state of charge 
     SOC 1 : first value 
     SOC 2 : second value 
     Tbat: battery temperature (temperature) 
     Tbat 3 : third predetermined temperature (predetermined temperature) 
     W: cooling water (coolant)