JP7412300B2 - battery cooling system - Google Patents

Description

The present invention relates to a battery cooling system that cools a battery mounted on a vehicle.

BACKGROUND ART Vehicles such as electric cars and hybrid cars are equipped with batteries as a driving source.
If the temperature of this battery increases too much, its performance or lifespan will be reduced, so vehicles such as electric cars are equipped with a battery cooling system that cools the battery.

This battery cooling system generally includes an air intake duct placed between a vehicle interior and a battery located outside the vehicle interior, and a cooling fan placed inside the intake duct. The battery is cooled by taking it into the intake duct and sending it to the battery side. In addition, sensors detect the battery temperature and the temperature of the air passing through the intake duct (i.e., the intake air temperature) to prevent the battery from being heated by air that is hotter than the battery. An intake air temperature check is performed to determine whether or not to start cooling the battery using a fan (for example, Patent Document 1).

In this type of battery cooling system, air remains in the intake duct when the cooling fan stops, so the battery is An intake air temperature check is performed to compare the temperature with the intake air temperature.

In the battery cooling system described in Patent Document 1, as an intake air temperature check control to check the intake air temperature, when the battery becomes high temperature, a cooling fan is continuously driven to send out air corresponding to the volume of the intake duct, and the volume is A method is adopted in which the intake air temperature in the intake duct and the battery temperature are obtained after each minute of air is sent out, and the intake air temperature is compared with the battery temperature.If the intake air temperature is lower than the battery temperature, The battery will begin to cool down.

In the battery cooling system described in Patent Document 1, the air in the intake duct is sent out at once to check the intake air temperature, thereby ending the intake air temperature check early and quickly starting cooling the battery. Can be done.

JP2018-95061A

FIG. 5 is a graph showing an example of intake air temperature check control in the battery cooling system described in Patent Document 1, where the vertical axis shows the intake air temperature and battery temperature, the solid line shows the change in battery temperature over time, and the broken line shows the change in the intake air temperature. It shows the change over time. As mentioned above, the battery cooling system of Patent Document 1 can end the intake air temperature check early, but if the vehicle is left in the scorching sun and the intake duct is at a high temperature, When the cooling fan is activated to check the intake air temperature and air is sent out at once by the volume of the intake duct, the high temperature air in the intake duct is sent to the battery side at once, causing the battery temperature to rise rapidly. There is a risk of overheating.

Furthermore, even if air is discharged by the volume of the intake duct, if the air inside the vehicle is heated by passing through the high-temperature intake duct and is higher than the vehicle interior temperature, the intake air The intake air temperature _XA detected by the temperature sensor may become higher than the battery temperature _XB detected by the battery temperature sensor. Note that in FIG. 5, ΔT _A indicates the difference obtained by subtracting the battery temperature X _B from the intake air temperature X _A. In this way, with conventional intake air temperature checks, even though the temperature of the air inside the vehicle is lower than the battery temperature, the cooling fan stops driving after checking the intake air temperature, and the battery may not be properly cooled. there were.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a battery cooling system that can start cooling the battery while suppressing heating of the battery.

In order to achieve the above object, a battery cooling system according to an embodiment of the present invention includes a cooling fan that takes air inside a vehicle interior into an intake passage communicating between the vehicle interior and the battery, and sends the air to the battery; a battery temperature sensor that detects the temperature of the battery; an intake air temperature sensor that is disposed in the intake passage and detects the temperature of the air passing through the intake passage; an intake air temperature determined by the intake air temperature sensor; and a battery temperature determined by the battery temperature sensor. a control unit that controls operation of the cooling fan based on the above, wherein the control unit operates the cooling fan to send air to the battery, and then controls the cooling fan to operate. A temperature check operation is performed to calculate a difference value by subtracting the battery temperature from the intake air temperature, and when the difference value is greater than zero, the temperature check operation is repeated, and the control unit In the temperature check operation, if the difference value of the current temperature check operation is smaller than the difference value of the previous temperature check operation, and the current difference value is larger than zero, the next temperature check operation is performed. It is characterized by performing the temperature check operation.

According to this configuration, when the difference value obtained by subtracting the battery temperature from the intake air temperature is larger than zero, the control unit repeats the temperature check operation and repeatedly starts and stops the cooling fan, thereby reducing the temperature of the passenger compartment. It is possible to avoid a situation where the battery is not cooled even though the air temperature is lower than the battery temperature. In addition, even if the difference value is greater than zero, if the air temperature in the passenger compartment is lower than the battery temperature, the difference value will gradually become smaller by continuing to blow air, so check the temperature from the second time onwards. During operation, if the calculated difference value is smaller than the previous temperature check operation, by performing the next temperature check operation, the difference value becomes zero or less while suppressing battery heating (i.e. This makes it possible to end the temperature check control early and start cooling the battery.

Further, in an embodiment of the present invention, in the battery cooling system, the control unit may, when the difference value of the current temperature check operation is smaller than the difference value of the previous temperature check operation, The present invention is characterized in that the amount of air sent to the battery in the next temperature check operation is increased more than the amount of air in the current temperature check operation.

According to this configuration, in the second and subsequent temperature check operations, if the difference value calculated in the current temperature check operation is smaller than the difference value in the previous temperature check operation, the air volume in the next temperature check operation is changed to the current value. By increasing the amount of air more than the air volume, it is possible to shorten the time until the cooling fan can cool the battery (that is, the time until the difference value calculated in the temperature check operation becomes zero or less). This makes it possible to end the temperature check control early and start cooling the battery.

Further, in an embodiment of the present invention, in the battery cooling system, the control unit increases the air volume in the next temperature check operation by increasing the driving time of the cooling fan. .

Further, in an embodiment of the present invention, in the battery cooling system, the control unit increases the air volume in the next temperature check operation by increasing the duty ratio of the cooling fan. .

According to this configuration, by increasing the duty ratio of the cooling fan or increasing the drive time of the cooling fan, the air volume in the next temperature check operation can be increased compared to the current air volume.

Further, in one embodiment of the present invention, in the battery cooling system, the control unit may be configured such that, in the second and subsequent temperature check operations, the difference value of the current temperature check operation is the same as that of the previous temperature check. It is characterized in that control of the temperature check operation is reset when the difference value of the operation is greater than or equal to the difference value.

According to this configuration, when the difference value of the current temperature check operation is greater than or equal to the previous temperature check operation, that is, when there is a possibility that the battery may be heated incorrectly by operating the cooling fan, the temperature By resetting the check control, it is possible to prevent the occurrence of erroneous heating.

According to the battery cooling system according to the present invention, battery cooling can be started while suppressing heating of the battery.

1 is a schematic explanatory diagram of a battery cooling system that is an embodiment of the present invention. FIG. 3 is an explanatory diagram of a control mechanism of the battery cooling system. FIG. 3 is a flowchart showing intake air temperature check control by a control unit. (A) is a graph showing temporal changes in battery temperature, intake air temperature, and cabin temperature; (B) is a graph showing temporal changes in cooling fan duty ratio. 7 is a graph showing changes over time in battery temperature and intake air temperature when checking intake air temperature in a conventional battery cooling system.

FIG. 1 is a schematic explanatory diagram of a battery cooling system that is an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a control mechanism of the battery cooling system. The battery cooling system 10 of the present invention is applied to a vehicle that uses a battery BT as a drive source, such as an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle.

The battery cooling system 10 includes a battery BT mounted on the vehicle, an intake duct 14 that forms an intake passage that communicates the vehicle interior and the battery BT, and a cooling system that takes air inside the vehicle interior into the intake duct 14 and sends it to the battery BT. It includes a fan 20 and an exhaust duct 16 for discharging the air sent to the battery BT to the outside of the vehicle. The battery cooling system 10 also includes an intake air temperature sensor 30 that detects the temperature of the air passing through the intake passage (hereinafter also referred to as intake air temperature), a battery temperature sensor 34 that detects the temperature of the battery BT, and an ECU that is a control unit. (electronic control unit) 40.

The battery BT is housed in a battery pack 12 formed outside the vehicle interior. The battery pack 12 can be placed, for example, under a luggage compartment at the rear of the vehicle. In this embodiment, the battery BT includes five battery stacks, namely, a first battery stack BS1, a second battery stack BS2, a third battery stack BS3, a fourth battery stack BS4, and a fifth battery stack BS5. Each battery stack BS1 to BS5 is configured by stacking battery cells that generate electricity.

The intake duct 14 communicates between the vehicle interior and the inside of the battery pack 12 in which the battery BT is housed. In this embodiment, the downstream side of the intake duct 14 branches into a plurality of pipes, and is configured to send air inside the vehicle compartment to each of the battery stacks BS1 to BS5. Specifically, two intake ducts 14A and 14B are provided between the vehicle compartment and the battery pack 12, and the first intake duct 14A branches into two branch pipes 15a and 15b on the downstream side, and the first intake duct 14A branches into two branch pipes 15a and 15b on the downstream side. One branch pipe 15a is connected to the first battery stack BS1, and the second branch pipe 15b is connected to the second battery stack BS2. Further, the second intake duct 14B branches into three branch pipes 15c, 15d, and 15e on the downstream side, the first branch pipe 15c is connected to the third battery stack BS3, and the second branch pipe 15d is connected to the third battery stack BS3. It is connected to the fourth battery stack BS4, and the third branch pipe 15d is connected to the fifth battery stack BS5.

The cooling fan 20 is driven by a fan motor 22 connected to the ECU 40, and supplies air inside the vehicle to the battery BT. The cooling fan 20 is provided in each intake duct 14, and in this embodiment, the first cooling fan 20A is arranged in the first intake duct 14A, and the second cooling fan is arranged in the second intake duct 14B. ing. The first cooling fan 20A and the second cooling fan 20B can be individually driven by the first fan motor 22A and the second fan motor 22B, respectively. In the illustrated example, the cooling fan 20 is installed on the intake duct 14 side to push the air inside the duct out of the vehicle, but the cooling fan 20 is installed on the exhaust duct 16 side to push the air inside the duct outside the vehicle. You can also pull it out.

The exhaust duct 16 forms an exhaust passage that discharges the air sent to the battery BT via the intake duct 14 to the outside of the vehicle. In this embodiment, the upstream end of the exhaust duct 16 is branched to be connected to each of the first to fifth battery stacks BS1 to BS5.

The intake air temperature sensor 30 is disposed in the intake passage and detects the temperature Ta of the air passing through the intake duct 14 (hereinafter also referred to as intake air temperature Ta). The intake air temperature sensor 30 is preferably provided in an area close to the battery pack 12 in the intake passage in consideration of temperature changes in the intake passage and the influence on the battery BT. In the battery cooling system 10 of this embodiment, the first intake air temperature sensor 30A is installed near the second battery stack BS2 in the first intake duct 14A, and the first intake air temperature sensor 30A is installed near the third battery stack BS3 in the second intake duct 14B. Two intake air temperature sensors 30 are provided, including a second intake air temperature sensor 30B.

The battery temperature sensor 34 detects the temperature Tb of the battery BT (hereinafter also referred to as battery temperature Tb), is attached within the battery pack 12 or on the surface of the battery pack 12, and measures the temperature of the battery BT directly or indirectly. Detect accurately. In this embodiment, in each of the intake ducts 14A and 14B, the first battery temperature sensor 34A and the second Each of the battery temperature sensors 34B is attached.

ECU 40 controls equipment mounted on the vehicle, including battery cooling system 10.
The ECU 40 includes, for example, information processing means such as a central processing unit (CPU) or an application specific integrated circuit (ASIC), storage means such as a RAM or ROM, an input/output interface, and the like. The ECU 40 of this embodiment controls the operation of the cooling fan 20 based on the temperatures detected by the intake air temperature sensor 30 and the battery temperature sensor 34, and connects each temperature sensor 30A, 30B, 34A, 34B and each fan motor 22A, 22B with electricity. connected.

The ECU 40 can control the cooling fans 20A and 20B simultaneously based on the maximum temperature of each intake air temperature sensor 30A and 30B and the maximum temperature of each battery temperature sensor 34A and 34B. . In addition, instead of these, each cooling fan 20A, 20B is controlled by each intake air temperature sensor 30A, 30B and each battery temperature sensor 34A, 34B provided in each air passage from each intake duct 14A, 14B to the exhaust duct 16. They may be controlled individually. In the following description, the control operation by the ECU 40 will be described assuming that the cooling fans 20A and 20B are simultaneously controlled using the maximum temperature of each temperature sensor.

The ECU 40 includes a storage unit 42 that stores predetermined information regarding intake air temperature check control and battery cooling control after the intake air temperature check control. Furthermore, the ECU 40 includes a calculation unit 44 that calculates a difference value ΔT _N by subtracting the battery temperature Tb from the intake air temperature Ta, and a calculation unit 44 that calculates a difference value ΔT N by subtracting the battery temperature Tb from the intake air temperature Ta, and based on the information in the storage unit 42, the detection results of each sensor, and the calculation results by the calculation unit 44, and a determination unit 46 that determines the operation of the controller. N in the difference value ΔT _N is a positive integer value (N=1, 2, . . . , m) that changes depending on the number of temperature check operations, which will be described later.

A battery cooling reference temperature Tb _th is set in the storage unit 42 as a reference for cooling the battery BT in the battery cooling system 10 . As an example, the battery cooling reference temperature Tb _th can be set to 36°C.

Furthermore, control values for controlling the rotation of the cooling fan 20 in the intake air temperature check control are preset in the storage unit 42 . As shown in Table 1, this control value is based on the duty ratio D _n (unit: %) of the PWM control (control that repeats on and off at a constant cycle) of the cooling fan 20, and the duty ratio D n (unit: %) of the cooling fan 20 at the duty ratio D _n . t _n (unit: sec). n is a positive integer value that changes depending on the number of temperature check operations, which will be described below, and is set so that as n increases, the duty ratio and time values increase. The rotation speed (unit: rpm) of the cooling fan 20 at each duty ratio may be constant, or may be set such that the rotation speed increases as the duty ratio becomes higher. Furthermore, the storage unit 42 stores the difference value ΔT _N calculated by the calculation unit 44.

In the intake air temperature check control, when the intake air temperature Ta is higher than the battery temperature Tb, the ECU 40 performs the following operation, that is, drives the cooling fan 20 at a predetermined duty ratio _Dn for a predetermined time _tn to control the battery BT. After sending the air, a series of operations are performed in which the cooling fan 20 is stopped for a predetermined time tx, the intake air temperature Ta and the battery temperature Tb are detected, and the difference value ΔT _N is calculated by subtracting the battery temperature from the intake air temperature Ta. In this specification, this series of operations is referred to as a "temperature check operation." In the battery cooling system 10 of this embodiment, in the second and subsequent temperature check operations, the current difference value ΔT _N is larger than zero, and the current temperature check value is greater than the difference value ΔT _N-1 of the previous temperature check operation. When the operation difference value ΔT _N is small, the amount of air sent to the battery BT is increased in the next (ie, third or later) temperature check operation compared to the current temperature check operation. The amount of air sent to the battery in the temperature check operation is preferably smaller than the volume of the air intake duct 14. In this embodiment, the air volume is set so that the air volume sent to the battery BT is smaller than the volume of the air intake duct 14 in at least the first to third temperature check operations. Note that the amount of air sent to the battery BT by the cooling fan 20 in each temperature check operation can be set as appropriate.For example, the amount of air sent to the battery BT by the cooling fan 20 can be set as appropriate. Alternatively, the air volume may be different each time.

Next, with reference to the flowchart of FIG. 3, the intake air temperature check control performed by the ECU 40 will be specifically described.

First, when the ECU 40 detects that the vehicle equipped with the battery cooling system 10 is in a state where it can run by the drive source, that is, the system is activated (step S10), the battery temperature Tb becomes It is determined whether the reference temperature Tb _th has been exceeded (step S12). The determination in step 12 is continuously and repeatedly performed when the battery temperature Tb is equal to or lower than the battery cooling reference temperature Tb _th (step S12: No).

If the battery temperature Tb exceeds the battery cooling reference temperature _Tbth (step S12: Yes), the parameter n, which is the control value of the cooling fan 20, and the parameter N of the difference value ΔT _N calculated by the calculation unit 44 are each set to 1. is set (n=N=1), and the process moves to the next process (step S14).

In the next process (step S16), the cooling fan 20 is driven at a predetermined duty ratio _D1 for a predetermined time _t1 based on the control value stored in the storage unit 42, and then the cooling fan 20 is stopped. After the cooling fan 20 is stopped and a predetermined time tX has elapsed, whether or not the intake air temperature Ta is lower than or equal to the battery temperature Tb (that is, whether the difference value obtained by subtracting the battery temperature Tb from the intake air temperature Ta is equal to or lower than zero). ) is determined (step S18). Here, the operations from step S16 to step S18 correspond to the first temperature check operation.

If the intake air temperature Ta is lower than or equal to the battery temperature Tb (step S18: Yes), the battery can be cooled, so the intake air temperature check control is ended (END), and the temperature set in advance in the storage unit 42 is Based on the control value of the battery cooling control, the cooling fan 20 is driven to start cooling the battery BT.

In step S18, if the intake air temperature Ta is higher than the battery temperature Tb (step S18: No), the difference value _ΔT1 obtained by subtracting the battery temperature Tb from the intake air temperature Ta is stored in the storage unit 42 (step S20). Next, the cooling fan 20 is driven again at a predetermined duty ratio _D1 for a predetermined time _t1 , and then the cooling fan 20 is stopped (step S22). After the cooling fan 20 is stopped and a predetermined time _tX has elapsed, it is determined whether the intake air temperature Ta is equal to or lower than the battery temperature Tb (step S24). Here, the operations from step S22 to step S24 correspond to the second temperature check operation.

If the intake air temperature Ta is equal to or lower than the battery temperature Tb (step S24: Yes), the intake air temperature check control is ended, and the cooling fan 20 is started based on the control value of the battery cooling control set in advance in the storage unit 42. and starts cooling the battery BT.

In step S24, if the intake air temperature Ta is higher than the battery temperature Tb (step S24: No), each of the parameter n, which is the control value of the cooling fan 20, and the parameter N of the difference value ΔT _N calculated by the calculation unit 44 is set to 1. (n=n+1, N=N+1) (step S26), and the difference value _ΔT2 obtained by subtracting the battery temperature Tb from the intake air temperature Ta is stored in the storage unit 42 (step S28), and the process moves to the next process.

In the next step S30, it is determined whether the difference value ΔT ₂ calculated this time is smaller than the difference value ΔT ₁ of the previous temperature check operation (here, the first temperature check operation).

If the current difference value ΔT ₂ is greater than or equal to the previous difference value ΔT ₁ (step S30: No), air with a higher temperature than the battery BT may be sent and the battery BT may be heated incorrectly. The intake air temperature check control that has been performed up to this point is reset, and the intake air temperature check control is restarted from step S12. After the reset, the parameters n and N are restarted from 1 in step S14.

On the other hand, if the current difference value ΔT ₂ is smaller than the previous difference value ΔT ₁ (step S30: Yes), the cooling fan 20 is operated at a predetermined value larger than the previous value in order to push out the warmed air in the intake duct 14. The cooling fan ₂₀ is driven at a duty ratio _D2 for a predetermined time t2, and then the cooling fan 20 is stopped (step S32). After the cooling fan 20 is stopped and a predetermined time _tX has elapsed, it is determined whether the intake air temperature Ta is equal to or lower than the battery temperature Tb (step S34). Here, the operations from step S32 to step S34 correspond to the third temperature check operation.

In step S34, if the intake air temperature Ta is equal to or lower than the battery temperature Tb (step S34: Yes), the intake air temperature check control is ended, and based on the control value of the battery cooling control preset in the storage unit 42, The cooling fan 20 is driven to start cooling the battery BT.

In step S34, if the intake air temperature Ta is higher than the battery temperature Tb (step S34: No), the process returns to step S26, and the parameter n, which is the control value of the cooling fan 20, and the difference value ΔT _N calculated by the calculation unit 44 are calculated. Add 1 to each of the parameters N (n=n+1, N=N+1). Here, the parameter n=N=3 is set by adding 1 to each parameter n=N=2. After that, the process moves to step S28, and the subsequent process continues. As shown in steps S26 to S34 of the flowchart in FIG. 3, when the battery temperature Tb is higher than the battery cooling reference temperature _Tbth , the intake air temperature check control is continued until the intake air temperature Ta becomes equal to or lower than the battery temperature Tb. Each time the number of temperature check operations increases, the parameters n and N are incremented by 1, and PWM control of the cooling fan 20 is performed based on these variables.

As described above, in the intake air temperature check control of the battery cooling system 10 of the present embodiment, in the third and subsequent temperature check operations, the air volume sent to the battery BT by the cooling fan 20 is increased compared to the previous temperature check operation. controlled as follows. That is, if this is the Nth temperature check operation, the operation of the cooling fan 20 is controlled so that the air volume is increased compared to the previous N-1st temperature check operation. In this embodiment, the ECU 40 increases the air volume during the temperature check operation by increasing the driving time t _n of the cooling fan 20 and increasing the duty ratio D _n of the cooling fan 20 .

FIG. 4 is a graph showing an example when the temperature check operation is performed four times in the intake air temperature check control, and FIG. FIG. 4B is a graph showing changes in the duty ratio of the cooling fan over time. Note that the cabin temperature can be detected by a cabin temperature sensor provided inside the cabin or at the end of the air intake duct 14 on the cabin side. In FIGS. 4A and 4B, the time axes (horizontal axes) are made to coincide.

For example, if the vehicle is left in the scorching sun and the intake duct 14 is at a high temperature, as shown in FIG. 4, even if the cabin temperature is lower than the battery temperature Tb due to air conditioning, The intake air temperature Ta passing through the intake duct 14 may become higher than the battery temperature Tb. In such a case, if the cooling fan 20 is rotated at a lower rotation speed than when cooling the battery due to the intake air temperature check control, the high temperature air stagnant in the intake duct 14 will be sent to the vicinity of the outlet of the intake duct 14. The intake air temperature measured by the intake air temperature sensor 30 disposed at increases. At this time, when the cooling fan 20 is continuously driven to exhaust the air equivalent to the volume of the intake duct 14 at once, as in the conventional intake air temperature check control shown in FIG. 5, the high temperature air is sent to the battery BT all at once. As a result, the battery temperature Tb increases rapidly, and there is a risk of overheating.

On the other hand, in the battery cooling system 10 of this embodiment, as shown in FIG. By repeating the driving and stopping of 20, even if high-temperature air remains in the intake passage, high-temperature air is sent to the battery BT at once and the battery temperature Tb can be prevented from rising rapidly. It can be suppressed.

Furthermore, in the battery cooling system 10 of this embodiment, as shown in FIG. 4, the difference value ΔT _N obtained by subtracting the battery temperature Tb from the intake air temperature Ta is greater than the difference value ΔT _N-1 of the previous time. If the duty ratio D _n of the cooling fan 20 is smaller than the previous duty ratio D _n-1 , and the driving time t _n of the cooling fan 20 is larger than the previous driving time t _n-1 . The operation of the cooling fan 20 is controlled. Even if the difference value ΔT _N is larger than zero, if the air temperature in the passenger compartment is lower than the battery temperature Tb, the difference value ΔT _N will gradually become smaller by continuing to blow air with the cooling fan 20. , in the second and subsequent temperature check operations, if the calculated difference value ΔT _N is smaller than the difference value ΔT _N-1 of the previous temperature check operation, the air volume in the next temperature check operation is increased from this time. Therefore, it is possible to shorten the time until the difference value becomes zero or less (that is, the intake air temperature Ta becomes equal to or less than the battery temperature Tb, and the battery BT can be cooled by the cooling fan 20). Thereby, the intake air temperature check control can be ended early, and when the vehicle interior temperature is lower than the battery temperature Tb, it is possible to quickly and reliably start cooling the battery BT. As shown in FIG. 4(A), the battery cooling control after the intake air temperature check control continuously detects the difference value ΔT, and detects the difference value ΔT at the timing (time t _Y ) when the difference value ΔT _N becomes equal to or less than zero. You may start.

In the battery cooling system 10 according to the present invention, the air volume by the cooling fan 20 when the temperature check operation is repeated a plurality of times can be increased by simply increasing the duty ratio D _n while keeping the drive time t _n constant; The duty ratio _Dn may be kept constant and only the drive time _tn may be increased, or the duty ratio _Dn and the drive time _tn may be kept constant and the rotation speed of the cooling fan 20 may be increased. As shown in the figure, by increasing the driving time _tn with the duty ratio Dn and increasing the air volume each time the _temperature check operation increases, the intake air temperature check control is ended early and the battery BT is cooled. can be started more quickly.

In addition, in the intake air temperature check control, if the difference value ΔT _N calculated in the second or later temperature check operation is greater than zero, and the difference value ΔT _N is greater than or equal to the difference value ΔT _N-1 of the previous temperature check operation. In this case, the air temperature in the vehicle interior is higher than the battery temperature Tb, and driving the cooling fan 20 may cause the battery BT to be erroneously heated. Therefore, in such a case, by resetting the intake air temperature check control and preventing the cooling fan 20 from cooling the battery BT (that is, continuously driving the cooling fan 20), the error of the battery BT can be prevented. Heating can be prevented.

Note that the present invention is not limited to the embodiments described above, and various changes can be made without departing from the spirit of the invention.

10 Battery cooling system 12 Battery pack 14 Intake duct 15a, 15b, 15c, 15d, 15e Branch pipe 16 Exhaust duct 20 Cooling fan 22 Fan motor 30 Intake air temperature sensor 34 Battery temperature sensor 40 ECU (control unit)

Claims (5)

a cooling fan that takes air from the vehicle interior into an intake passage communicating with the vehicle interior and the battery and sends it to the battery;
a battery temperature sensor that detects the temperature of the battery;
an intake air temperature sensor disposed in the intake passage to detect the temperature of air passing through the intake passage;
A battery cooling system comprising: a control unit that controls the operation of the cooling fan based on the intake air temperature measured by the intake air temperature sensor and the battery temperature measured by the battery temperature sensor,
The control unit operates the cooling fan to send air to the battery, and then stops the cooling fan and performs a temperature check operation of calculating a difference value by subtracting the battery temperature from the intake air temperature; repeating the temperature check operation when the difference value is greater than zero;
The control unit is configured such that in the second and subsequent temperature check operations, the difference value of the current temperature check operation is smaller than the difference value of the previous temperature check operation, and the current difference value is zero. A battery cooling system characterized in that the next temperature check operation is performed when the temperature is larger than . The control unit controls the amount of air to be sent to the battery in the next temperature check operation when the difference value of the current temperature check operation is smaller than the difference value of the previous temperature check operation. 2. The battery cooling system according to claim 1, wherein the air volume is increased more than the air volume of the current temperature check operation. The battery cooling system according to claim 2, wherein the control unit increases the air volume in the next temperature check operation by increasing the driving time of the cooling fan. 4. The battery cooling system according to claim 2, wherein the control unit increases the air volume in the next temperature check operation by increasing the duty ratio of the cooling fan. In the second and subsequent temperature check operations, if the difference value of the current temperature check operation is greater than or equal to the difference value of the previous temperature check operation, the control unit controls the temperature check operation. The battery cooling system according to any one of claims 1 to 4, characterized in that the control is reset.

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