Vehicular battery cooling system

Abstract

To drive a battery cooling fan so which drive sound of the battery cooling fan becomes smaller than the drive sound of a blower fan of an air-conditioner, without using a transmission signal from the air-conditioner.SOLUTION: A vehicular battery cooling system which supplies air in a vehicle interior to a battery room by a battery cooling fan to cool a battery comprises a first temperature sensor which detects a temperature of the battery, a second temperature sensor which detects a temperature of the vehicle interior, and a controller which controls driving of the battery cooling fan. The controller estimates an outside air temperature outside the vehicle, estimates an output of a blower fan of an air-conditioner of the vehicle on the basis of a difference between the temperature in the vehicle interior and the estimated outside air temperature, and controls an output of the battery cooling fan on the basis of the estimated output of the blower fan of the air-conditioner and the temperature of the battery.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a vehicle battery cooling system. [Background technology]

[0002] An electric vehicle or hybrid electric vehicle equipped with a drive motor as a drive power source is equipped with a battery that is the power source for the drive motor. It is known that the deterioration of a battery progresses due to heat generation caused by repeated charging and discharging and temperature rise caused by the influence of the ambient temperature. For this reason, the vehicle is equipped with a system for cooling the battery. One aspect of a vehicle battery cooling system is a system that cools the battery by supplying air from the vehicle cabin to the battery using a cooling fan.

[0003] Here, in the above-mentioned battery cooling system, a technique has been proposed to reduce the possibility that the driving sound of the cooling fan will be heard as noise by passengers. For example, Patent Documents 1 and 2 disclose a technique in which a control device controls the driving of the cooling fan so that the driving sound of the cooling fan is quieter than the driving sound of the blower fan of an air conditioner. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-193602 A [Patent Document 2] JP 2013-216173 A Summary of the Invention [Problem to be solved by the invention]

[0005] Here, the battery cooling system of the vehicle is required to be diagnosed by an on-board diagnostic device (OBD: On Board Diagnostics), and components such as sensors and control devices used to control the battery cooling system are subject to the diagnosis. The components subject to the diagnosis (hereinafter also referred to as "components subject to OBD requirements") are required to comply with the OBD requirements. In the technology described in Patent Documents 1 and 2 above, when a blower fan output signal is acquired from an air conditioner that is not included in the battery cooling system, the components that detect or calculate the output of the blower fan are also subject to the OBD requirements, and measures are required.

[0006] The present disclosure has been made in consideration of the above problems, and an object of the present disclosure is to provide a vehicle battery cooling system that can drive a battery cooling fan so that the driving noise of the battery cooling fan is quieter than the driving noise of the air conditioning system's blower fan, without using a transmission signal from the air conditioning system. [Means for solving the problem]

[0007] In order to solve the above problem, according to one aspect of the present disclosure, there is provided a vehicle battery cooling system that supplies air from within a vehicle cabin to a battery chamber in which a battery is housed by a battery cooling fan to cool the battery, the vehicle battery cooling system including a first temperature sensor that detects the temperature of the battery, a second temperature sensor that detects the temperature within the vehicle cabin, and a control device that controls driving of the battery cooling fan, wherein the control device executes an outside air temperature estimation process that estimates the outside air temperature outside the vehicle, an air conditioning blower fan output estimation process that estimates the output of a blower fan of an air conditioning device of the vehicle based on the difference between the temperature within the vehicle cabin and the estimated outside air temperature, and a battery cooling fan control process that controls the output of the battery cooling fan based on the estimated output of the blower fan of the air conditioning device and the temperature of the battery. Effect of the Invention

[0008] As described above, according to the present disclosure, the battery cooling fan can be driven so that the driving noise of the battery cooling fan is quieter than the driving noise of the air conditioner's blower fan, without using a transmission signal from the air conditioner. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating a configuration example of a vehicle battery cooling system according to an embodiment of the present disclosure. [Diagram 2] 2 is an explanatory diagram showing the configuration of a control mechanism of the battery cooling system according to the embodiment. FIG. [Diagram 3] 4 is a logic diagram for calculating a drive duty ratio of the battery cooling fan according to the embodiment. FIG. [Figure 4] 4 is a flowchart of a processing operation for controlling the driving of a battery cooling fan according to the embodiment. [Diagram 5] 4 is a flowchart of an outside air temperature estimation process according to the embodiment. [Figure 6] 13 is a flowchart of a reference temperature recording process according to the embodiment. [Figure 7] 4 is a schematic diagram shown for explaining a method of calculating an estimated outside air temperature according to the embodiment. FIG. [Figure 8] FIG. 4 is an explanatory diagram showing an example of a blower fan output estimation map according to the embodiment. [Figure 9] FIG. 4 is an explanatory diagram showing a change in indoor temperature after startup of the power system. [Figure 10] 13 is a flowchart of an indoor temperature acquisition definition process according to the embodiment. [Figure 11] 11 is a flowchart of a processing operation for controlling the driving of a battery cooling fan according to an application example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configurations are denoted by the same reference numerals, and redundant description will be omitted.

[0011] <1. Overall configuration of the battery cooling system> First, with reference to FIG. 1, an example of an overall configuration of a vehicle battery cooling system according to an embodiment of the present disclosure will be described.

[0012] 1 is an explanatory diagram showing a vehicle equipped with a vehicle battery cooling system according to the present embodiment. As shown in FIG 1, the vehicle 1 includes a battery 20, a battery cooling system 10, and an air conditioning system 40.

[0013] The battery 20 is a secondary battery that supplies power to a drive motor (not shown) provided as a drive power source for the vehicle 1. The battery 20 is configured to include a plurality of battery cells. The battery 20 may be, for example, a lithium ion battery rated at 200 V, but the type and rated output of the battery 20 are not particularly limited. The battery 20 is accommodated in a battery chamber 25.

[0014] The air conditioning system 40 conditions the air in the passenger compartment 30 by the air conditioner 26. The air conditioning system 40 includes an air conditioning duct 41, the air conditioner 26, and a blower fan 27. The air conditioning duct 41 is a passage for circulating air, and communicates between the outside of the vehicle 1 and the inside of the passenger compartment 30. The air conditioning duct 41 has a first inlet 41a communicating with the outside of the vehicle 1 and a second inlet 41b communicating with the inside of the passenger compartment 30. The air conditioning device 26 includes a switching damper 28 provided in the air conditioning duct 41, and a blower fan 27, which is a blowing means, arranged on the passenger compartment 30 side of the switching damper 28. The switching damper 28 switches between an open state and an closed state of the first inlet 41a and the second inlet 41b of the air conditioning duct 41. The blower fan 27 is driven by a blower motor (not shown).

[0015] When the blower fan 27 is driven, the switching damper 28 closes the first inlet 41a while opening the second inlet 41b, which results in an inside air circulation mode. In the inside air circulation mode, the inside air of the vehicle 1 is introduced into the air conditioner 26 from the second inlet 41b, and is blown out from the outlet of the air conditioner 26 into the passenger compartment 30. On the other hand, when the blower fan 27 is driven, the switching damper 28 opens the first inlet 41a while closing the second inlet 41b, which results in an outside air introduction mode. In the outside air introduction mode, the outside air is taken into the air conditioning duct 41 from the first inlet 41a, introduced into the air conditioner 26, and is blown out from the outlet of the air conditioner 26 into the passenger compartment 30.

[0016] The air conditioner 26 adjusts the temperature of air supplied to the vehicle interior 30 so that the interior temperature detected by a vehicle interior temperature sensor that detects the temperature inside the vehicle interior 30 becomes a set temperature. In this embodiment, the intake air temperature detected by a vehicle interior temperature sensor (corresponding to a second temperature sensor) that is a component of the battery cooling system 10 is used as the interior temperature detected by the vehicle interior temperature sensor. However, the vehicle interior temperature sensor that detects the interior temperature may be installed in the vehicle interior 30 separately from the vehicle interior temperature sensor of the battery cooling system 10.

[0017] The battery cooling system 10 supplies air from within the vehicle interior 30 to a battery compartment 25 in which the battery 20 is provided by a battery cooling fan 22, thereby cooling the battery 20. An occupant usually adjusts the set temperature of the air conditioner 26 so that the interior temperature of the vehicle interior 30 is approximately 20 to 30° C. The battery cooling system 10 cools the battery 20 by supplying the air from within the vehicle interior 30, the temperature of which is adjusted in this manner, to the battery compartment 25, thereby preventing the battery 20 from overheating.

[0018] The battery cooling system 10 includes a battery cooling fan 22, a cooling duct 42, and an exhaust duct 44. The cooling duct 42 connects the vehicle interior 30 and the battery chamber 25. The exhaust duct 44 constitutes an exhaust path connecting the battery chamber 25 and the outside of the vehicle. The exhaust duct 44 is provided with an air vent grill 49. The air vent grill 49 opens when the air pressure inside the vehicle becomes high, and exhausts air to the outside of the vehicle.

[0019] The battery chamber 25 is located between the passenger compartment 30 and the luggage compartment 32 at the rear of the vehicle, near the rear seat 19 disposed in the passenger compartment 30. In this embodiment, the battery chamber 25 is located below the rear seat 19. The battery cooling fan 22 is disposed in the cooling duct 42. The battery cooling fan 22 is driven by a fan motor (not shown), and supplies air from within the passenger compartment 30 to the battery chamber 25.

[0020] Fig. 2 is an explanatory diagram showing the configuration of a control mechanism of the battery cooling system 10. As shown in Fig. 2, the battery cooling system 10 includes a battery temperature sensor (first temperature sensor) 53, a vehicle interior temperature sensor (second temperature sensor) 54, a fan motor 56 that drives the cooling fan 22, and a control device (ECU: electronic control unit) 60.

[0021] The battery temperature sensor 53 detects the temperature T_bt of the battery 20 (hereinafter also referred to as battery temperature T_bt). The battery temperature sensor 53 is provided in the battery 20 or the battery chamber 25, and detects the temperature of the battery 20 directly or indirectly. The vehicle interior temperature sensor 54 detects the temperature T_ab inside the vehicle interior 30 (hereinafter also referred to as interior temperature T_ab). In this embodiment, the vehicle interior temperature sensor 54 is provided in the cooling duct 42. However, the vehicle interior temperature sensor 54 may be provided inside the vehicle interior 30, or may be provided on the vehicle interior 30 side of the battery 20 in the battery chamber 25.

[0022] The control device 60 includes a processing unit 61 having a processor such as a CPU (Central Processing Unit), a storage unit 63 having a RAM (Random Access Memory) or a ROM (Read Only Memory) communicatively connected to the processing unit 61, and an input / output interface (not shown). The control device 60 is communicatively connected to the battery temperature sensor 53, the vehicle interior temperature sensor 54, and the fan motor 56. The control device 60 controls the output of the battery cooling fan 22 and executes a process for cooling the battery 20.

[0023] <2. Configuration of the control device> Next, the control device 60 of the battery cooling system 10 will be specifically described. The control device 60 functions as a device that drives the fan motor 56 and executes a process of cooling the battery 20 by executing a computer program with one or more processors such as CPUs. The computer program is a computer program for causing the processor to execute operations to be performed by the control device 60, which will be described later. The computer program executed by the processor may be recorded on a recording medium that functions as a storage unit 63 provided in the control device 60, or may be recorded on a recording medium built into the control device 60 or any recording medium that can be externally attached to the control device 60.

[0024] Examples of recording media for recording computer programs include magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs (Compact Disk Read Only Memory), DVDs (Digital Versatile Disks), and Blu-ray (registered trademark); magneto-optical media such as floptical disks; memory elements such as RAMs (Random Access Memory) and ROMs (Read Only Memory); and flash memories such as USB (Universal Serial Bus) memories and SSDs (Solid State Drives), as well as other media capable of storing programs.

[0025] 2, the processing unit 61 of the control device 60 includes an outside air temperature estimation unit 71, an air conditioning blower fan output estimation unit 73, and a battery cooling fan control unit 75. The outside air temperature estimation unit 71, the air conditioning blower fan output estimation unit 73, and the battery cooling fan control unit 75 are functions realized by the execution of a program by a processor. However, part of the outside air temperature estimation unit 71, the air conditioning blower fan output estimation unit 73, and the battery cooling fan control unit 75 may be configured to include hardware such as an analog circuit.

[0026] The outside air temperature estimation unit 71 executes an outside air temperature estimation process to estimate the outside air temperature outside the vehicle. That is, the battery cooling system 10 has a configuration that can use information on the outside air temperature without increasing the number of OBD target components by estimating the outside air temperature through calculation, rather than acquiring a sensor signal from a temperature sensor that detects the outside air temperature and is provided in the vehicle 1.

[0027] The air conditioning blower fan output estimation unit 73 executes an air conditioning blower fan output estimation process to estimate the output of the blower fan 27 of the air conditioning device 26 based on the difference between the indoor temperature T_ab and an estimated outside air temperature (hereinafter also referred to as "estimated outside air temperature T_am"). In other words, the battery cooling system 10 has a configuration that can use the information on the output of the blower fan 27 without increasing the number of OBD target components by estimating the output of the blower fan 27 through calculations rather than acquiring information on the output of the blower fan 27 from the air conditioning device 26 of the air conditioning system 40.

[0028] The battery cooling fan control unit 75 executes a battery cooling fan control process to control the output of the battery cooling fan 22 based on the estimated output of the blower fan 27 and the battery temperature T_bt. This makes it possible to prevent the battery 20 from overheating and to prevent deterioration of the battery 20.

[0029] <3. Processing Operation> Next, the processing operation of the control device 60 for cooling the battery 20 will be described. 3 and 4 are explanatory diagrams showing the processing operation by the processing unit 61 of the control device 60. Fig. 3 shows a logic diagram for calculating the drive duty ratio D_bf of the battery cooling fan 22, and Fig. 4 shows a flowchart of the processing operation for controlling the drive of the battery cooling fan 22.

[0030] First, when the battery cooling system 10 is started (step S11), the outside air temperature estimator 71 of the processor 61 executes a process of estimating the outside air temperature (step S13). In this embodiment, the outside air temperature estimator 71 calculates an estimated outside air temperature T_am based on the battery temperature (reference temperature) T_bt_off detected at a predetermined time when the power system including the battery 20 is in a stopped state, the battery temperature (start-up temperature) T_bt_on when the power system is started, and the elapsed time from the predetermined time when the reference temperature T_bt_off is detected to the time when the start-up temperature T_bt_on is detected. The outside air temperature estimation process is a process of estimating the outside air temperature from the change in the battery temperature T_bt while the power system is stopped, and the outside air temperature estimator 71 calculates the estimated outside air temperature T_am using only the components of the battery cooling system 10.

[0031] FIG. 5 shows a flowchart of the outside air temperature estimation process. First, the outside air temperature estimator 71 reads out the reference temperature T_bt_off recorded in the memory unit 63 (step S31). The reference temperature T_bt_off is the battery temperature T_bt detected by the battery temperature sensor 53 during the period from when the power system was shut down last time until when the power system is started up this time, and is recorded in the memory unit 63 together with information on the time of detection. The reference temperature T_bt_off is detected at least once during the period from when the power system was shut down last time until when the power system is started up this time.

[0032] However, if the time from the time when the reference temperature T_bt_off is detected to the start-up of the power system becomes too long, the outside air temperature may repeatedly rise and fall during that time, which may reduce the accuracy of calculating the estimated outside air temperature T_am based on the battery temperature T_bt. For this reason, in this embodiment, the outside air temperature estimator 71 detects the battery temperature T_bt at predetermined time intervals from the time when the power system was last stopped until the time when the power system is currently started, and records the battery temperature T_bt together with the time of detection in the memory unit 63.

[0033] Fig. 6 shows a flowchart of the reference temperature recording process. The flowchart shown in Fig. 6 may be executed during operation of the power system including the battery 20, or may be started when it is determined that the battery cooling system 10 in the flowchart shown in Fig. 4 has stopped (step S23 / Yes).

[0034] First, the outside air temperature estimation unit 71 determines whether or not the power system including the battery 20 has stopped (step S41). Instead of determining whether or not the power system has stopped, the outside air temperature estimation unit 71 may determine whether or not the battery cooling system 10 has stopped. In this case, step S41 may be replaced with step S23 in the flowchart shown in FIG.

[0035] When the outside air temperature estimator 71 does not determine that the power system has stopped (S41 / No), it repeats the determination of step S41. On the other hand, when the outside air temperature estimator 71 determines that the power system has stopped (S41 / Yes), it obtains the battery temperature T_bt detected by the battery temperature sensor 53, and records it as the reference temperature T_bt_off together with the detection time in the memory unit 63 (step S43).

[0036] Next, the outside air temperature estimator 71 determines whether a predetermined time has elapsed since the time when the reference temperature T_bt_off was recorded immediately before in step S43 (step S45). The predetermined time is set to, for example, 4 hours, but may be set to any time. However, if the predetermined time is too long, when the time until the next startup of the power system becomes long, the battery temperature T_bt will repeatedly rise and fall due to the influence of the outside air temperature, making it difficult to calculate the estimated outside air temperature T_am based on the change in the battery temperature T_bt and the elapsed time. Therefore, the predetermined time is set to an appropriate time in consideration of the accuracy of the estimated outside air temperature T_am calculated based on the change in the battery temperature T_bt and the elapsed time.

[0037] When the outside air temperature estimation unit 71 does not determine that the predetermined time has elapsed since the time when the reference temperature T_bt_off was recorded (S45 / No), the outside air temperature estimation unit 71 proceeds to step S49. On the other hand, when the outside air temperature estimation unit 71 determines that the predetermined time has elapsed since the time when the reference temperature T_bt_off was recorded (S45 / Yes), it acquires the battery temperature T_bt detected by the battery temperature sensor 53, and updates the information recorded in the storage unit 63 as the reference temperature T_bt_off together with the detection time (step S47).

[0038] Next, the outside air temperature estimator 71 determines whether the power system has started up (step S49). If the outside air temperature estimator 71 does not determine that the power system has started up (S49 / No), the process returns to step S45 and repeats the determination of the passage of the predetermined time (step S45) and the update of the reference temperature T_bt_off. On the other hand, if the outside air temperature estimator 71 determines that the power system has started up (S49 / Yes), the process of recording the reference temperature ends.

[0039] 5, after reading the reference temperature T_bt_off in step S31, the outside air temperature estimator 71 acquires the battery temperature (start-up temperature) T_bt_on detected by the battery temperature sensor 53 when the power system was started up this time (step S33). Next, the outside air temperature estimator 71 calculates the elapsed time from the time when the reference temperature T_bt_off was detected to the time when the start-up temperature T_bt_on was detected (step S35).

[0040] Next, the outside air temperature estimator 71 calculates the estimated outside air temperature T_am based on the reference temperature T_bt_off, the start-up temperature T_bt_on, and the elapsed time (step S37). Specifically, the outside air temperature estimator 71 calculates the estimated outside air temperature T_am from an outside air temperature estimation map stored in advance in the storage unit 63 using the reference temperature T_bt_off, the start-up temperature T_bt_on, and the elapsed time as input information.

[0041] FIG. 7 is a schematic diagram shown for explaining a method of calculating the estimated outside air temperature T_am. When the outside air temperature is lower than the battery temperature T_bt, the battery temperature T_bt also gradually decreases while the vehicle 1 is stopped. The rate at which the battery temperature T_bt decreases (the amount of change in the battery temperature T_bt over time) depends on the battery temperature T_bt and the outside air temperature. In other words, if the battery temperature T_bt and the rate at which the battery temperature T_bt decreases thereafter are known, the outside air temperature can be estimated.

[0042] As shown in Fig. 7, when the time that has elapsed since the power system was stopped (SW-OFF) is short and the difference between the battery temperature T_bt and the outside air temperature is relatively large, the rate at which the battery temperature T_bt drops becomes relatively large. After that, as the time that has elapsed since the power system was stopped (SW-OFF) becomes longer, the difference between the battery temperature T_bt and the outside air temperature becomes smaller, and the rate at which the battery temperature T_bt drops becomes relatively slower.

[0043] During the operation of the power system, the battery temperature T_bt is cooled by the battery cooling system 10. Therefore, the battery temperature T_bt when the power system is stopped (SW-OFF) is maintained at a temperature lower than, for example, 35 to 40° C. Therefore, for battery temperatures T_bt lower than, for example, 35 to 40° C., the rate of decrease in the battery temperature T_bt corresponding to each outside air temperature can be measured in advance using an actual device or obtained by simulation, thereby creating an outside air temperature estimation map.

[0044] In this manner, the outside air temperature estimation unit 71 executes the outside air temperature estimation process in accordance with the flowchart shown in Fig. 5. As a result, the outside air temperature estimation unit 71 can calculate the estimated outside air temperature T_am using the components of the battery cooling system 10 without acquiring a signal indicating the outside air temperature from other sensors or systems such as an outside air temperature sensor.

[0045] 4, after the estimated outside air temperature T_am is calculated in step S13, the air conditioning blower fan output estimator 73 acquires information on the interior temperature T_ab detected by the vehicle interior temperature sensor 54 (step S15). In this embodiment, the air conditioning blower fan output estimator 73 acquires information on the temperature detected by the vehicle interior temperature sensor 54 provided in the cooling duct 42.

[0046] Next, the air conditioning blower fan output estimating unit 73 estimates the drive duty ratio D_br of the blower fan 27 of the air conditioning device 26 (step S17). The output of the blower fan 27 is controlled by adjusting the drive duty ratio D_br, which is the ratio of the energizing time per predetermined time period. The air conditioning device 26 adjusts the interior temperature T_ab to the set temperature by supplying temperature-adjusted air into the vehicle interior 30 with the blower fan 27. The output of the blower fan 27 is increased as the difference between the outside air temperature and the interior temperature T_ab increases so that the interior temperature T_ab reaches the set temperature as soon as possible. Therefore, the air conditioning blower fan output estimating unit 73 uses the estimated outside air temperature T_am and the interior temperature T_ab as input information to calculate the drive duty ratio D_br of the blower fan 27 from a blower fan output estimation map stored in advance in the storage unit 63.

[0047] FIG. 8 is an explanatory diagram showing an example of a blower fan output estimation map. The blower fan 27 to which the blower fan output estimation map illustrated in FIG. 8 is applied is driven with a drive duty ratio at a predetermined minimum value when the outdoor air temperature is on the minimum output temperature line L1 obtained by multiplying the indoor temperature by a predetermined coefficient (1.33 in the example of FIG. 8). When the outdoor air temperature is above the minimum output temperature line L1, the air conditioner 26 operates as a heating function, and the output of the blower fan 27 increases as the difference between the outdoor air temperature and the indoor temperature increases. On the other hand, when the outdoor air temperature is below the minimum output temperature line L1, the air conditioner 26 operates as a cooling function, and the output of the blower fan 27 increases as the difference between the outdoor air temperature and the indoor temperature increases. Therefore, the blower fan output estimation map can be created in advance based on information for setting the drive duty ratio D_br of the blower fan 27.

[0048] In this way, the air conditioning blower fan output estimation unit 73 can calculate the drive duty ratio D_br of the blower fan 27 using the components of the battery cooling system 10 without obtaining a signal indicating the output of the blower fan 27 from the air conditioning device 26.

[0049] Returning to FIG. 4, after estimating the drive duty ratio D_br of the blower fan of the air conditioner 26 in step S17, the battery cooling fan control unit 75 sets the drive duty ratio D_bf of the battery cooling fan 22 (step S19). The battery cooling fan control unit 75 sets the drive duty ratio D_bf of the battery cooling fan 22 based on the estimated drive duty ratio D_br of the blower fan 27 and the battery temperature T_bt so that the drive sound of the battery cooling fan 22 is not heard by the occupants as an abnormal sound. At this time, the battery cooling fan control unit 75 sets the maximum drive duty ratio D_bf within a range in which the drive sound of the battery cooling fan 22 is not heard by the occupants as an abnormal sound. The output of the battery cooling fan 22 is controlled by adjusting the drive duty ratio D_bf, which is the ratio of the energization time per predetermined time period.

[0050] In this embodiment, the driving of the battery cooling fan 22 is controlled so that the driving sound of the battery cooling fan 22 is less audible to the occupants, taking into consideration not only the driving sound of the blower fan 27 of the air conditioner 26 but also background noises such as the driving sound of the engine of the vehicle 1, wind noise accompanying the running of the vehicle 1, and road noise caused by friction between the tires and the road surface. Specifically, the battery cooling fan control unit 75 calculates the driving duty ratio D_bf of the battery cooling fan 22 from a cooling fan output setting map stored in advance in the storage unit 63, using as input information the battery temperature T_bt detected by the battery temperature sensor 53, the vehicle speed V detected by a vehicle speed sensor (not shown), the engine output torque or target torque Tq_EG, and the driving duty ratio D_br of the blower fan 27.

[0051] The higher the battery temperature T_bt is and the greater the difference between the battery temperature T_bt and a target battery temperature, the greater the need for cooling the battery 20, so the drive duty ratio D_bf of the battery cooling fan 22 is set to a larger value. The faster the vehicle speed V is, the greater the wind noise and road noise, and the greater the background noise, so the drive duty ratio D_bf of the battery cooling fan 22 can be set to a larger value. The greater the engine output torque or target torque Tq_EG is, the greater the engine drive sound, so the drive duty ratio D_bf of the battery cooling fan 22 can be set to a larger value.

[0052] The information on the vehicle speed V and the engine output torque or the target torque Tq_EG is included in the information acquired by the power system as information used for controlling charging and discharging by the power system including the battery 20. Therefore, the number of OBD target components is not newly increased when the battery cooling system 10 is constructed.

[0053] Furthermore, in order to take into account how easily background noise generated in the vehicle 1 as the vehicle 1 travels can be heard by passengers in the vehicle compartment 30, the cooling fan output setting map may further include, as input information, information on the opening and closing degree of the side windows. Furthermore, if the vehicle 1 is an electric vehicle that does not have an engine, the cooling fan output setting map may be a map that does not include information such as the output torque of the engine.

[0054] Next, the battery cooling fan control unit 75 controls the driving of the fan motor 56 of the battery cooling fan 22 based on the set driving duty ratio D_bf (step S21). Next, the battery cooling fan control unit 75 determines whether the battery cooling system 10 has stopped (step S23), and if it is not determined that the battery cooling system 10 has stopped (S23 / No), the process returns to step S13 and repeats the processing of each step described up to this point. On the other hand, if the battery cooling fan control unit 75 determines that the battery cooling system 10 has stopped (S23 / Yes), the process of cooling the battery 20 ends.

[0055] As described above, the battery cooling system 10 according to this embodiment controls the driving of the battery cooling fan 22 so that the driving sound of the battery cooling fan 22 heard by the occupants is smaller than the driving sound of the blower fan 27 of the air conditioner 26 without using a transmission signal from the air conditioner 26. Specifically, the control device 60 estimates the outside air temperature based on the time change of the battery temperature T_bt. In addition, the control device 60 estimates the driving duty ratio D_br of the blower fan 27 based on the estimated outside air temperature T_am and the room temperature T_ab. Therefore, the driving of the battery cooling fan 22 can be controlled without including the air conditioner 26, the outside air temperature sensor that detects the outside air temperature, or the solar radiation sensor as OBD target components that are targets of the fault diagnosis of the battery cooling system 10. This allows the number of OBD target components of the battery cooling system 10 to be reduced.

[0056] Furthermore, the battery cooling system 10 according to this embodiment updates the reference temperature T_bt_off of the battery 20, which is detected when the power system is stopped and is used to calculate the estimated outside air temperature T_am, at predetermined time intervals. This suppresses deterioration in the accuracy of the estimated outside air temperature T_am, which is estimated based on the reference temperature T_bt_off and the rate of decrease in the battery temperature T_bt, and reduces the risk that the driving sound of the battery cooling fan 22 will be heard as an abnormal sound by the occupants.

[0057] <4. Application Examples> Next, an application example of the above embodiment will be described. It takes a predetermined time for the temperature inside the passenger compartment 30 to stabilize after the occupant starts using the vehicle 1 and the air conditioning system 40 starts operating. If the battery cooling fan control process is executed before the indoor temperature T_ab is stabilized, the output of the blower fan 27 estimated using the indoor temperature T_ab may fluctuate up and down, resulting in hunting, which may cause the set output of the battery cooling fan 22 to hunt. For this reason, the battery cooling system of the application example does not start defining the indoor temperature T_ab used to estimate the output of the blower fan 27 until the indoor temperature T_ab stabilizes, and starts defining the indoor temperature T_ab after the indoor temperature T_ab stabilizes.

[0058] "Start definition of interior temperature T_ab" indicates that the interior temperature T_ab detected by the vehicle interior temperature sensor 54 is used in the process of estimating the output of the blower fan 27 of the air conditioner 26.

[0059] Fig. 9 and Fig. 10 are explanatory diagrams showing the indoor temperature definition start process by the battery cooling system of the application example. Fig. 9 is an explanatory diagram showing the change in the indoor temperature T_ab after the start-up (SW-ON) of the power system including the battery 20, and Fig. 10 shows a flowchart of the indoor temperature acquisition definition process.

[0060] When the power system is started (step S51), the air conditioning blower fan output estimating unit 73 acquires the indoor temperature T_ab detected by the vehicle interior temperature sensor 54 (step S53). The indoor temperature T_ab is acquired at a predetermined sampling period set in advance.

[0061] Next, the air conditioning blower fan output estimating unit 73 calculates the change rate dT_ab / dt of the indoor temperature T_ab based on the indoor temperature T_ab acquired in the previous sampling period, the indoor temperature T_ab acquired in the current sampling period, and the time interval dt of the sampling period (step S55). The air conditioning blower fan output estimating unit 73 calculates the change rate dT_ab / dt of the indoor temperature T_ab by dividing the difference dT_ab obtained by subtracting the indoor temperature T_ab acquired in the previous sampling period from the indoor temperature T_ab acquired in the current sampling period by the time interval dt.

[0062] Incidentally, when the indoor temperature T_ab is acquired for the first time after the power system is started, the air conditioning blower fan output estimation unit 73 returns to step S53, skipping step S55 and the next step S56, since it is not possible to calculate the rate of change dT_ab / dt of the indoor temperature T_ab.

[0063] Next, the air conditioning blower fan output estimating unit 73 judges whether the change rate dT_ab / dt of the room temperature T_ab has become less than a predetermined threshold value set in advance (step S57). The predetermined threshold value can be set to any appropriate value in order to judge whether the room temperature T_ab has stabilized. If the air conditioning blower fan output estimating unit 73 does not judge that the change rate dT_ab / dt of the room temperature T_ab has become less than the predetermined threshold value (S57 / No), the process returns to step S53 and the acquisition of the room temperature T_ab (step S53) and the judgment of the change rate dT_ab / dt of the room temperature T_ab (steps S55 to S57) are repeated (during the period when the room temperature definition is off in FIG. 5).

[0064] On the other hand, when the air conditioning blower fan output estimating unit 73 determines that the change rate dT_ab / dt of the indoor temperature T_ab is less than the predetermined threshold value (S57 / Yes), it starts to define the indoor temperature T_ab (step S59). As a result, the air conditioning blower fan output estimating unit 73 ends the indoor temperature definition start process. After that, it starts to estimate the output of the blower fan 27 of the air conditioner 26 using the information of the indoor temperature T_ab (period of starting the indoor temperature definition in FIG. 5).

[0065] FIG. 11 is a flowchart showing a processing operation for controlling the drive of the battery cooling fan 22 by the battery cooling system of the applied example. In the application example, after the estimated outside air temperature T_am is calculated in step S13, the air conditioner blower fan output estimating unit 73 determines whether the definition of the indoor temperature T_ab has started (step S61). If the air conditioner blower fan output estimating unit 73 determines that the definition of the indoor temperature T_ab has started (S61 / Yes), the process proceeds to step S15, and the processing unit 61 controls the drive of the battery cooling fan 22 according to the procedure described in the above embodiment.

[0066] On the other hand, when the air conditioning blower fan output estimating unit 73 does not determine that the definition of the indoor temperature T_ab has started (S61 / No), the process proceeds to step S19, where the driving duty ratio D_bf of the battery cooling fan 22 is set to a predetermined minimum value (step S19). Then, the battery cooling fan control unit 75 controls the driving of the battery cooling fan 22 at the minimum driving duty ratio D_bf (step S21).

[0067] In this manner, in the application example, after the battery cooling system 10 is started, the battery cooling fan 22 is controlled at the minimum drive duty ratio D_bf until the interior temperature T_ab detected by the vehicle interior temperature sensor 54 stabilizes. Therefore, it is possible to prevent hunting of the output of the battery cooling fan 22 caused by hunting of the output of the blower fan 27 of the air conditioner 26 estimated using the interior temperature T_ab.

[0068] Although the preferred embodiment of the present disclosure has been described in detail above with reference to the accompanying drawings, the present disclosure is not limited to such examples. It is clear that a person having ordinary knowledge in the technical field to which the present disclosure belongs can conceive of various modified or amended examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present disclosure. [Explanation of symbols]

[0069] 1: Vehicle 10: Battery cooling system 20: Battery 22: Battery cooling fan 25: Battery compartment 26:Air conditioner 27: Blower fan 30: Vehicle interior 32: Cargo compartment 40: Air conditioning system 53: Battery temperature sensor 54: Vehicle interior temperature sensor 56: Fan motor 60: Control device 61: Processing section 63: Storage section 71: Outside temperature estimation unit 73: Air conditioning blower fan output estimation unit 75: Battery cooling fan control unit

Claims

1. A vehicle battery cooling system that supplies air from within a vehicle cabin to a battery chamber housing a battery by a battery cooling fan to cool the battery, A first temperature sensor for detecting a temperature of the battery; A second temperature sensor for detecting a temperature inside the vehicle compartment; a control device that controls the driving of the battery cooling fan, The control device includes: An outside air temperature estimation process for estimating an outside air temperature outside the vehicle; an air conditioning blower fan output estimation process for estimating an output of a blower fan of an air conditioning device of a vehicle based on a difference between the temperature in the vehicle cabin and the estimated outside air temperature; a battery cooling fan control process for controlling an output of the battery cooling fan based on the estimated output of the blower fan of the air conditioner and the temperature of the battery; A vehicle battery cooling system.

2. The control device includes: The battery cooling system of claim 1 , wherein the outside air temperature is estimated based on a temperature of the battery.

3. The control device includes:

3. The battery cooling system of claim 2, wherein the outside air temperature is estimated based on a reference temperature, which is the temperature of the battery detected at a predetermined time when a power system including the battery is in a stopped state, a startup temperature, which is the temperature of the battery when the power system is started, and the elapsed time from the predetermined time when the reference temperature is detected to the time when the startup temperature is detected.

4. The control device includes:

4. The battery cooling system according to claim 3, wherein the temperature of the battery is detected at predetermined time intervals after the power system is stopped, the temperature of the battery is recorded as the reference temperature together with the time of detection, and used to estimate the outside air temperature.

5. The control device includes:

2. The battery cooling system according to claim 1, wherein after a power system including the battery is started, the battery cooling fan control process is started based on the estimated output of the blower fan of the air conditioner and the temperature of the battery after a rate of change of temperature in the vehicle cabin becomes less than a predetermined threshold.

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