Electric-vehicle battery cooling apparatus

Abstract

To suppress accumulation of dust in an electric-vehicle battery cooling apparatus.SOLUTION: An apparatus includes: a case 3 for hosing a battery 2 of a travelling motor; a fan 6, equipped inside of the case 3, for forward-rotating so as to exhaust air from an air exhaust port 5 of the case 3, the air introduced from an air intake port 4 of the case 3; and a control part 7 for controlling rotating direction and speed of the fan 6. The control part 7 controls: the fan 6 so as to reverse-rotate at a given rotation speed on the basis of an inside cabin temperature T1, an outside cabin temperature T2 and a battery temperature T3 and so on; a first switch valve 10 to open-close a first duct 8 and a second duct 9 that are communicating with the air intake port 4; and a second switch valve 13 to open-close a third duct 11 and a fourth duct 12 that are communicating with the air exhaust port 5, thus exhausting air from the air intake port 4, the air introduced from the air exhaust port 5.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a battery cooling device for an electric vehicle that air-cools a battery mounted on an electric vehicle such as an electric car or a hybrid car. [Background technology]

[0002] Conventionally, electric vehicles, such as electric vehicles and hybrid vehicles, have been equipped with a battery that supplies power to the driving motor. This battery generates heat when charging and discharging, and if the battery is maintained at a high temperature due to the heat generated, it is prone to deterioration. For this reason, a device for cooling the battery has been proposed.

[0003] For example, a battery cooling device described in Patent Document 1 has an air passage that connects an air intake port and an air exhaust port, the air passage is connected midway to a cooling case that houses a battery, and a blower (fan) is provided in the air passage to flow air from the air intake port toward the air exhaust port, and the air passing through the cooling case air-cools the battery. The air intake port is switched between introducing inside air (air inside the vehicle cabin) and introducing outside air (air outside the vehicle) by an intake-side switching valve, and the air exhaust port is switched between discharging air inside the vehicle and discharging air outside the vehicle by an exhaust-side switching valve, and the switching of the intake-side switching valve and the exhaust-side switching valve is controlled by a controller.

[0004] Furthermore, for example, the battery cooling device described in Patent Document 2 has an insulating material placed between an inner case that houses multiple battery modules (batteries) and an outer case that houses the inner case, and an interior duct, a cooling / heating device duct, and an exterior exhaust duct are installed so as to pass through the inner case, the outer case, and the insulating material.

[0005] The interior duct communicates with the interior of the vehicle and houses a fan. The cooling / heating device duct is connected to the interior duct and houses a cooling / heating device. An air switching flap is provided at the connection between the interior duct and the cooling / heating device duct. When the fan operates, air passing through the cooling / heating device duct from inside the inner case and cooled / heated by the cooling / heating device, or air passing through the interior duct from the vehicle compartment, is introduced from the interior duct into the inner case by switching the air switching flap. The air introduced into the inner case cools the battery, and the air inside the case is discharged to the outside of the vehicle through the exterior exhaust duct. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-194384 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-075390 Summary of the Invention [Problem to be solved by the invention]

[0007] In the battery cooling device of Patent Document 1, when inside air or outside air is introduced into the cooling case through the air intake port, dust in the vehicle cabin or outside air enters the cooling case along with the air, causing the dust to accumulate.

[0008] In the battery cooling device of Patent Document 2, when air from the vehicle interior is introduced into the inner case through the vehicle interior duct, dust from the vehicle interior enters the inner case along with the air, causing dust to accumulate, similar to the battery cooling device of Patent Document 1.

[0009] Therefore, an object of the present invention is to suppress the accumulation of dust in a battery cooling device for an electric vehicle. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention can employ the following configurations 1 to 7. [Configuration 1] a case that houses a battery that supplies power to a driving motor; an air intake provided in the case and connected to the interior of the vehicle cabin and an air exhaust provided in the case and connected to the exterior of the vehicle cabin; a fan that rotates in a forward direction so that air is taken in through the air intake and discharged through the air discharge port; a control unit that controls the rotation direction and rotation speed of the fan, A battery cooling device for an electric vehicle, wherein when a predetermined condition is met, the control unit controls the fan to rotate in reverse to take in air from the air outlet and discharge it from the air intake.

[0011] [Configuration 2] A first filter is provided at the air intake, and the predetermined condition is met when the fan is driven in forward rotation for a predetermined time, and when the fan is driven in forward rotation for the predetermined time, the control unit controls the fan to rotate in reverse.

[0012] [Configuration 3] The battery cooling device for an electric vehicle according to configuration 1 or 2, further comprising an occupant detection means for detecting whether or not an occupant is present in the vehicle compartment, wherein the predetermined condition is met when there is no occupant in the vehicle compartment, and when there is no occupant in the vehicle compartment, the control unit controls the fan to rotate in the reverse direction.

[0013] [Configuration 4] The vehicle temperature sensor measures the temperature inside the vehicle, the temperature outside the vehicle, and the battery temperature sensor measures the temperature of the battery. The battery cooling device for an electric vehicle according to any one of configurations 1 to 3, wherein the predetermined conditions are conditions related to a temperature inside the vehicle cabin, a temperature outside the vehicle cabin, and a battery temperature, and the control unit controls the fan to rotate in a reverse direction in response to the establishment of the predetermined conditions.

[0014] [Configuration 5] a first duct communicating with the air intake and connected to the interior of the vehicle cabin; a second duct branching from the first duct and connected to the exterior of the vehicle cabin; and a first switching valve switching between an open state and an closed state of the first duct and the second duct, 5. The battery cooling device for an electric vehicle according to any one of configurations 1 to 4, wherein the control unit controls the first switching valve to switch between open and closed states of the first duct and the second duct based on an air conditioning setting in the vehicle cabin when the fan is rotated in reverse.

[0015] [Configuration 6] The battery cooling device for an electric vehicle according to any one of configurations 1 to 5, wherein the predetermined condition is satisfied when battery cooling performance drops below a predetermined level while the fan is rotating in the forward direction at a constant rotation speed, and when the predetermined condition is satisfied, the control unit controls the fan to rotate in the reverse direction and switches the first switching valve to close the first duct and open the second duct.

[0016] [Configuration 7] a third duct communicating with the air discharge port and connected to the outside of the vehicle cabin; a fourth duct branching from the third duct and connected to the inside of the vehicle cabin; and a second switching valve switching between an open state and an closed state of the third duct and the fourth duct, The battery cooling device for an electric vehicle according to any one of configurations 4 to 6, wherein the control unit, when rotating the fan in reverse, controls the second switching valve to close the third duct and open the fourth duct if the temperature outside the vehicle cabin is higher than the temperature inside the vehicle cabin, and to close the fourth duct and open the third duct if the temperature outside the vehicle cabin is lower than the temperature inside the vehicle cabin. [Effects of the Invention]

[0017] According to this invention, when a predetermined condition is met, the control unit controls the fan to rotate in reverse, so that air is taken in through the air outlet and expelled through the air intake.This blows away dust that has accumulated during forward rotation, suppressing dust accumulation and preventing a decrease in the battery's cooling performance due to dust accumulation. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is an explanatory diagram showing a state in which control is performed to rotate a fan in a forward direction in a battery cooling device for an electric vehicle according to a first embodiment of the present invention; [Figure 2] FIG. 10 is an explanatory diagram showing a state in which the fan in the battery cooling device for an electric vehicle is rotated in reverse to control the air taken in from the air outlet to be discharged from the case through the air intake. [Figure 3] FIG. 10 is an explanatory diagram showing a state in which control is performed to rotate the fan in the forward direction in the battery cooling device for an electric vehicle according to a second embodiment of the present invention; [Figure 4] An explanatory diagram showing a state in which the fan in the battery cooling device of an electric vehicle is rotated in reverse to control the air taken in from outside the vehicle cabin and discharged from inside the case to outside the vehicle cabin. [Figure 5] An explanatory diagram showing a state in which the fan in the battery cooling device of an electric vehicle is rotated in reverse to control the air taken in from the vehicle interior and discharged from the case to the outside of the vehicle interior. [Figure 6] An explanatory diagram showing a state in which the fan in the battery cooling device of an electric vehicle is rotated in reverse to control the air taken in from the vehicle interior and discharged from the case into the vehicle interior. [Figure 7] Block diagram showing a battery cooling device for an electric vehicle [Figure 8] Diagram showing the control of a battery cooling device for an electric vehicle [Figure 9] FIG. 1 is a schematic diagram showing an electric vehicle equipped with a battery cooling device for an electric vehicle according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0019] A battery cooling device according to a first embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 9, the battery cooling device 1 of this embodiment is applied to an electric vehicle 20 such as an electric automobile or a hybrid automobile, which includes a battery 2 that supplies power to a motor M for driving.

[0020] The electric vehicle 20 is a cab-over type electric vehicle that includes a motor M as a driving source for traveling, a battery 2 that supplies power to the motor M, a battery cooling device 1 that is arranged above a floor panel 21, and front wheels 22 and rear wheels 23 that are driven by the motor M. The electric vehicle 20 has an interior temperature sensor 24 that detects an interior temperature T1, an exterior temperature sensor 25 that detects an exterior temperature T2, and an occupant detection means 26 that detects information (occupant information) as to whether or not an occupant is present in the vehicle.

[0021] 1, the battery cooling device 1 includes a case 3 that houses a battery 2, an air intake 4 and an air exhaust 5 provided in the case 3, a fan 6, and a control unit 7 that controls the rotation direction and rotation speed of the fan 6 (see FIG. 7). In this embodiment, the battery cooling device 1 is disposed above a floor panel 21 and below the rear seat.

[0022] The battery 2 is composed of a module 2b having a plurality of battery cells 2a that supply power to the motor M.

[0023] The case 3 has a flat box shape, houses one or more modules 2b, and is provided with a battery temperature sensor 27 that acquires the temperature of the battery 2. In this embodiment, the battery temperature sensor 27 detects the temperature of the module 2b. The case 3 is also provided with an air intake 4 and an air exhaust 5, for example, facing each other in the front-to-rear direction. A first filter 4a is provided in the air intake 4 so as to cover the air intake 4. The first filter 4a is a dust-collecting filter that captures dust and foreign matter entering from inside or outside the vehicle cabin. A first duct 8 that is connected to the interior of the vehicle cabin is provided in the air intake 4.

[0024] A second filter 5a is installed at the air outlet 5 so as to cover the air outlet 5. Like the first filter 4a, the second filter 5a is a dust-collecting filter that captures dust and foreign matter entering from inside and outside the vehicle cabin. A third duct 11 connected to the outside of the vehicle cabin is installed at the air outlet 5.

[0025] The fan 6 is disposed inside the case 3, closer to the inside of the case 3 than the first filter 4a on the air intake 4 side. The fan 6 faces the air intake 4. The rotation direction and rotation speed of the fan 6 are controlled by the control unit 7.

[0026] Occupant information detected by a human presence sensor serving as occupant detection means 26, information on the vehicle interior temperature T1 acquired by the vehicle interior temperature sensor 24, information on the vehicle exterior temperature T2 acquired by the vehicle exterior temperature sensor 25, information on the battery temperature T3 acquired by the battery temperature sensor 27, and information on the operation time of the fan 6 are sent to the control unit 7. The control unit 7 controls the fan 6 based on the occupant information, the vehicle interior temperature T1, the vehicle exterior temperature T2, the battery temperature T3, and the operation time of the fan 6.

[0027] For example, when battery temperature T3 is within a first temperature range (e.g., 15 to 30°C) that is an optimum temperature for fully utilizing the battery performance of battery 2, control unit 7 controls fan 6 to rotate in the forward direction at a predetermined rotation speed. With this control, as shown in FIG. 1, air is taken from the vehicle interior through air intake 4 and first duct 8 into case 3, and battery 2 is cooled by the air passing through case 3. The air inside case 3 is discharged to the outside of the vehicle interior through air outlet 5 and third duct 11. At this time, first filter 4a of air intake 4 captures dust and foreign matter passing through first duct 8 from the vehicle interior. This control is called normal control.

[0028] When a predetermined condition is met during normal control, the control unit 7 causes the fan 6 to rotate in the reverse direction. This control is referred to as reverse rotation control. The predetermined condition is, for example, the following condition. (a) When the battery temperature is lower than the lower limit of the first temperature range and the temperature outside the vehicle is higher than the temperature inside the vehicle (b) When the battery temperature is higher than the upper limit of the first temperature range and the temperature outside the vehicle is lower than the temperature inside the vehicle. (c) When the cumulative driving time of the fan 6 reaches the first predetermined time under normal control. (d) When the continuous driving time of the fan 6 reaches the second predetermined time under normal control. (e) When the cooling performance of battery 2 becomes low in response to the operation of fan 6 under normal control. (a) and (b) are conditions related to temperature, and (c) to (e) are conditions related to the first filter 4a.

[0029] During normal control, when condition (a) is met, the control unit 7 performs reverse rotation control to introduce warmer outside air from the air exhaust port 5 into the case 3, thereby warming the battery 2. Furthermore, during the above normal control, when condition (b) is met, the control unit 7 performs reverse rotation control to introduce cooler outside air from the air exhaust port 5 into the case 3, thereby cooling the battery 2.

[0030] Furthermore, during normal control, large dust particles or debris may adhere to or accumulate on the first filter 4a, causing the first filter 4a to become clogged. In this case, the amount of air introduced into the case 3 through the air intake 4 decreases, causing the battery cooling performance to drop below a predetermined level (condition (e) is met). When condition (e) is met, the control unit 7 performs reverse rotation control. This reverse rotation control allows air from outside the vehicle cabin to be introduced into the case 3 through the air outlet 5, blowing away dust and debris accumulated on the first filter 4a at the air intake 4 and discharging the dust and debris into the vehicle cabin through the first duct 8. The battery cooling performance refers to the rate at which the battery temperature T3 decreases per unit time when the fan 6 is rotated forward at a constant speed.

[0031] Furthermore, when the control unit 7 is performing normal control and battery cooling is performed intermittently during daily driving or continuously during long-distance driving, dust may have accumulated on the first filter 4a. In this case, regular maintenance must be performed to remove dust from the first filter 4a.

[0032] As part of this periodic maintenance, the control unit 7 performs reverse rotation control when condition (c) or condition (d) is met. By this reverse rotation control, air outside the vehicle cabin is guided into the case 3 through the third duct 11 and discharged into the vehicle cabin through the air intake 4. The air discharged from the air intake 4 blows away dust accumulated on the first filter 4a, thereby removing the dust from the first filter 4a.

[0033] When reverse rotation control is performed due to the satisfaction of the above-mentioned predetermined conditions, the air discharged from the air intake 4 blows away dust accumulated on the first filter 4a, which may become airborne in the vehicle cabin through the first duct 8. For this reason, when the control unit 7 acquires occupant information from the human presence sensor 26 indicating that no one is in the vehicle cabin, it performs the above-mentioned periodic maintenance control. This control can prevent the occupants from inhaling dust that may become airborne in the vehicle cabin and thereby affecting the occupants.

[0034] In this embodiment, when the above-described predetermined conditions (a) to (e) are met, the control unit 7 performs reverse rotation control. This reverse rotation control allows the air outside the vehicle cabin to blow away dust accumulated on the first filter 4a of the air intake 4, making it possible to suppress the accumulation of dust and prevent a decrease in the cooling performance of the battery due to the accumulation of dust.

[0035] A battery cooling device 1 according to a second embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 3, the second embodiment differs from the first embodiment in that the air intake 4 is provided with a second duct 9 branching from the first duct 8 and connected to the outside of the vehicle cabin, and a first switching valve 10 that switches the open / closed states of the first duct 8 and the second duct 9, and the air exhaust port 5 is provided with a fourth duct 12 branching from the third duct 11 and connected to the inside of the vehicle cabin, and a second switching valve 13 that switches the open / closed states of the third duct 11 and the fourth duct 12. Other structures that are the same as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and descriptions thereof will be omitted.

[0036] 7 , in this embodiment, occupant information detected by a human presence sensor serving as occupant detection means 26, information on vehicle interior temperature T1 acquired by vehicle interior temperature sensor 24, information on exterior temperature T2 acquired by exterior temperature sensor 25, information on battery temperature T3 acquired by battery temperature sensor 27, and information on the operation time of fan 6 are sent to control unit 7. Based on the occupant information, vehicle interior temperature T1, exterior temperature T2, battery temperature T3, and operation time of fan 6, control unit 7 controls fan 6 and first and second selector valves 10 and 13.

[0037] An example of control of the battery cooling device 1 of this embodiment is shown in FIG.

[0038] For example, when the battery temperature T3 is within a first temperature range (e.g., 15 to 30°C) that is an optimum temperature for fully utilizing the battery performance of the battery 2 (Condition 0), the control unit 7 controls the first selector valve 10 to open the first duct 8 and close the second duct 9, controls the second selector valve 13 to open the third duct 11 and close the fourth duct 12, and controls the fan 6 to rotate forward at a predetermined rotation speed. As a result of this control, as shown in FIG. 3 , air is taken from the vehicle interior through the air intake 4 and the first duct 8 into the case 3, and the air passing through the case 3 cools the battery 2. The air inside the case 3 is discharged from the air outlet 5 to the outside of the vehicle interior through the third duct 11. At this time, the first filter 4a of the air intake 4 captures dust and foreign matter passing through the first duct 8 from the vehicle interior. The control performed when Condition 0 is met is normal control. Furthermore, when the predetermined condition is met during normal control, the control unit 7 performs reverse rotation control to rotate the fan 6 in the reverse direction.

[0039] During reverse rotation control, the control unit 7 controls the first switching valve 10 and the second switching valve 13 in accordance with temperature conditions related to the vehicle interior temperature T1, the vehicle exterior temperature T2, and the battery temperature T3. The temperature conditions are, for example, conditions 1 to 6 shown in Fig. 8, and the control unit 7 controls the first switching valve 10 and the second switching valve 13 as shown in Fig. 8.

[0040] That is, when battery temperature T3 is lower than the lower limit of the first temperature range, the battery performance of battery 2 deteriorates, and therefore it is desirable to increase battery temperature T3. In this case, when vehicle interior temperature T1 is lower than vehicle exterior temperature T2 (condition 1), as shown in FIG. 4 , control unit 7 controls first selector valve 10 to close first duct 8 and open second duct 9, controls second selector valve 13 to open third duct 11 and close fourth duct 12, and performs reverse rotation control. Through this control, outside air, which is warmer than the inside of the vehicle interior, is guided from third duct 11 into case 3 to warm battery 2. At this time, dust accumulated on first filter 4a of air intake 4 is discharged to the outside of the vehicle interior through second duct 9, preventing dust from affecting occupants even if they are present in the vehicle interior.

[0041] Furthermore, when battery temperature T3 is lower than the lower limit of the first temperature range and vehicle interior temperature T1 is higher than vehicle exterior temperature T2 (condition 2), the control unit 7 performs control to close the first duct 8 and open the second duct 9 by switching the first selector valve 10, control to close the third duct 11 and open the fourth duct 12 by switching the second selector valve 13, and reverse rotation control, as shown in Fig. 5. Through this control, air inside the vehicle interior that is warmer than the air outside the vehicle interior is guided into the case 3 through the fourth duct 12 to warm the battery 2. At this time, dust accumulated on the first filter 4a of the air intake 4 is blown away and can be discharged to the outside of the vehicle interior through the second duct 9.

[0042] When battery temperature T3 is higher than the upper limit of the first temperature range and within a second temperature range (e.g., 31 to 40°C) that does not affect the battery performance of battery 2, it is desirable to cool battery 2 to ensure its performance. In this case, when vehicle interior temperature T1 is lower than vehicle exterior temperature T2 (condition 3), the control unit 7 controls the first selector valve 10 to close the first duct 8 and open the second duct 9, the second selector valve 13 to close the third duct 11 and open the fourth duct 12, and reverse rotation, as shown in FIG. 5 . This control allows air from inside the vehicle cabin, which is cooler than the air outside the vehicle cabin, to be introduced into the case 3 through the fourth duct 12 to cool the battery 2. At this time, dust accumulated on the first filter 4a of the air intake 4 is blown off and can be discharged to the outside of the vehicle cabin through the second duct 9.

[0043] Furthermore, when the battery temperature T3 is within the second temperature range and the vehicle interior temperature T1 is higher than the vehicle exterior temperature T2 (condition 4), the control unit 7 performs control to close the first duct 8 and open the second duct 9 by switching the first selector valve 10, control to open the third duct 11 and close the fourth duct 12 by switching the second selector valve 13, and reverse rotation control, as shown in Fig. 4. Through this control, air outside the vehicle cabin, which is cooler than the air inside the vehicle cabin, is guided into the case 3 through the third duct 11 to cool the battery 2. At this time, dust accumulated on the first filter 4a of the air intake 4 is blown off and can be discharged to the outside of the vehicle cabin through the second duct 9.

[0044] If the battery temperature T3 is equal to or higher than the upper limit of the second temperature range, there is a risk of failure of the battery 2, and therefore it is necessary to immediately cool the battery 2. In this case, when the vehicle interior temperature T1 is lower than the vehicle exterior temperature T2 (condition 5), the control unit 7 performs the same control as in the case of the above condition 3 (see FIG. 5).

[0045] Furthermore, when the battery temperature T3 is equal to or higher than the upper limit of the second temperature range and the vehicle interior temperature T1 is higher than the vehicle exterior temperature T2 (condition 6), the control unit 7 performs the same control as in the case of condition 4 above (see Figure 4).

[0046] When the control unit 7 performs reverse rotation control, the control unit 7 controls the first switching valve 10 to close the first duct 8 and open the second duct 9, thereby discharging dust to the outside of the vehicle cabin. Although it is preferable to discharge dust to the outside of the vehicle cabin, users of the electric vehicle 20 may wish to increase the heating and cooling capacity by setting the air conditioning in the vehicle cabin to internal air circulation.

[0047] To meet this demand, in this embodiment, the control unit 7 may control the switching of the first switching valve 10 based on the air conditioning setting in the vehicle cabin. Specifically, when performing reverse rotation control, if the air conditioning setting in the vehicle cabin is internal air circulation, the control unit 7 may control the switching of the first switching valve 10 to open the first duct 8 and close the second duct 9 (see FIG. 6). Note that internal air circulation is an air conditioning method that circulates air in the vehicle cabin without introducing air from outside the electric vehicle 20 into the vehicle cabin.

[0048] In this embodiment, when performing reverse rotation control, the control unit 7 rotates the filter in the reverse direction at a predetermined rotation speed, but may also rotate the filter in the reverse direction at a rotation speed greater than the rotation speed during forward rotation, for example. This allows dust accumulated on the first filter 4a to be effectively blown away, and also allows a larger amount of accumulated dust to be blown away from the first filter 4a.

[0049] In this embodiment, the configuration of the present invention has been described assuming an electric vehicle 20 (EV) equipped with only a motor M as a driving source for traveling, but the present invention can also be applied to a hybrid vehicle (HV) equipped with a motor M and an engine as a driving source for traveling, in particular a plug-in hybrid vehicle (PHEV) in which the battery 2 can be charged (externally charged) using a plug from an external charging facility or a household outlet, etc. [Explanation of symbols]

[0050] 1 Battery cooling device 2 Battery 3 cases 4 Air intake 4a First filter 5 Air exhaust port 5a Second filter 6 Fans 7 Control Unit 8 First Duct 9 Second Duct 10 First switching valve 11 Third Duct 12 4th Duct 13 Second switching valve 20 Electric Vehicles 21 Floor Panel 22 front wheel 23 rear wheel 24 Vehicle interior temperature sensor 25 Outside vehicle temperature sensor 26 Occupant detection means (human sensor) 27 Battery Temperature Sensor Medium motor

Claims

1. a case that houses a battery that supplies power to a driving motor; an air intake port connected to the inside of the vehicle cabin and an air exhaust port connected to the outside of the vehicle cabin, the air intake port being provided in the case; a fan that rotates forward so that air is taken in through the air intake and discharged through the air discharge port; a control unit that controls the rotation direction and rotation speed of the fan, A battery cooling device for an electric vehicle, wherein when a predetermined condition is met, the control unit controls the fan to rotate in reverse to take in air from the air outlet and discharge it from the air intake.

2. 2. The battery cooling device for an electric vehicle according to claim 1, wherein a first filter is provided at the air intake, the predetermined condition is met when the fan is driven in forward rotation for a predetermined time, and when the fan is driven in forward rotation for the predetermined time, the control unit controls the fan to rotate in reverse.

3. 3. The battery cooling device for an electric vehicle according to claim 1, further comprising an occupant detection means for detecting whether or not an occupant is present in the vehicle compartment, wherein the predetermined condition is met when there is no occupant in the vehicle compartment, and when there is no occupant in the vehicle compartment, the control unit controls the fan to rotate in reverse.

4. The vehicle temperature sensor measures the temperature inside the vehicle, the temperature outside the vehicle, and the battery temperature sensor measures the temperature of the battery.

2. The battery cooling device for an electric vehicle according to claim 1, wherein the predetermined conditions are conditions related to a temperature inside the vehicle cabin, a temperature outside the vehicle cabin, and a battery temperature, and the control unit controls the fan to rotate in reverse in response to the establishment of the predetermined conditions.

5. a first duct communicating with the air intake and connected to an interior of a vehicle cabin; a second duct branching from the first duct and connected to an exterior of the vehicle cabin; and a first switching valve switching between an open state and an closed state of the first duct and the second duct, 2. The battery cooling device for an electric vehicle according to claim 1, wherein, when the fan is rotated in the reverse direction, the control unit controls the first switching valve to switch the open / closed states of the first duct and the second duct based on an air conditioning setting in the vehicle cabin.

6. 2. The battery cooling device for an electric vehicle according to claim 1, wherein the predetermined condition is met when battery cooling performance drops below a predetermined level while the fan is rotating forward at a constant rotation speed, and when the predetermined condition is met, the control unit controls the fan to rotate in the reverse direction and switches the first changeover valve so as to close the first duct and open the second duct.

7. a third duct communicating with the air discharge port and connected to the outside of the vehicle cabin; a fourth duct branching from the third duct and connected to the inside of the vehicle cabin; and a second switching valve switching between an open state and an closed state of the third duct and the fourth duct, 7. The battery cooling device for an electric vehicle according to claim 4, wherein, when the fan is rotated in reverse, the control unit controls the second switching valve to close the third duct and open the fourth duct if the temperature outside the vehicle compartment is higher than the temperature inside the vehicle compartment, and to close the fourth duct and open the third duct if the temperature outside the vehicle compartment is lower than the temperature inside the vehicle compartment.

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