Cooling device for battery pack

Abstract

The present invention is provided with: a first communication path (38A) that communicates between a heat exchanger-side outlet (4804) of a heat exchanger (48) and an internal circulation path-side inlet (3202); a first discharge path (38B) that cuts off an interval between the heat exchanger-side outlet (4804) of the heat exchanger (48) and the internal circulation path-side inlet (3202) and discharges a cooling liquid in an internal circulation path (32) to the outside of a battery pack (12); and a first valve (38C) that can be switched to one of the first communication path (38A) and the first discharge path (38B). When it is detected that a cooling liquid leakage has occurred from the internal circulation path (32), the first valve (38C) is controlled to switch from the first communication path (38A) to the first discharge path (38B).

Description

Battery pack cooling device

[0001] The present invention relates to a cooling device for a battery pack.

[0002] Electric vehicles, such as electric vehicles and hybrid vehicles, are powered by a motor and include a battery pack that supplies power to the motor. The battery pack includes multiple battery modules, an electrical unit for controlling the battery modules, and a case that houses the battery modules and the electrical unit. The temperature of the battery modules increases as they are charged and discharged. To prevent deterioration of the battery modules due to this temperature increase, a water-cooled battery pack cooling device has been proposed (see Patent Document 1). This battery pack cooling device includes multiple heat sinks, each with a circulation path through which a coolant circulates, arranged on the underside of the battery modules inside the battery pack, and a heat exchanger and a coolant pump outside the battery pack. The coolant pump circulates the coolant between the circulation path of the heat sink and the heat exchanger.

[0003] Japanese Patent Application Publication No. 2019-169390

[0004] However, if a crack occurs in a connecting member that connects heat sinks within a battery pack and allows coolant to flow inside the battery pack, the coolant that accumulates inside the battery pack may cause deterioration of the battery modules and electrical components, and some kind of improvement is therefore required. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a battery pack cooling device that is advantageous in protecting the battery modules from coolant if coolant leaks inside the battery pack.

[0005] In order to achieve the above object, one embodiment of the present invention is a cooling device for a battery pack, comprising: an internal circulation path provided within a battery pack through which a coolant circulates to cool battery modules; and an external circulation path provided outside the battery pack and connected to the internal circulation path, wherein the external circulation path is provided with a heat exchanger that cools the coolant, and a coolant pump is provided at a portion connecting a heat exchanger-side outlet of the heat exchanger and an internal circulation path-side inlet of the internal circulation path, the cooling device comprising: a coolant leakage detection unit that detects the occurrence of a coolant leak from the internal circulation path; a first communication path that connects an outlet of the coolant pump with the internal circulation path-side inlet; a first discharge path that blocks communication between the discharge port and the internal circulation path-side inlet and discharges the coolant in the internal circulation path to the outside of the battery pack; a first switching unit having a first valve that can be switched to either the first communication path or the first discharge path; and a control unit that controls the first valve to switch from the first communication path to the first discharge path when a coolant leak is detected by the coolant leakage detection unit. In one embodiment of the present invention, the battery pack further includes a second communication passage that connects an internal circulation passage side outlet of the internal circulation passage and a heat exchanger side inlet of the heat exchanger, a second discharge passage that blocks communication between the internal circulation passage side outlet and the heat exchanger side inlet and discharges the coolant in the internal circulation passage to the outside of the battery pack, and a second switching unit having a second valve that can be switched to either the second communication passage or the second discharge passage, wherein the control unit controls the second valve to switch from the second communication passage to the second discharge passage when the coolant leak detection unit detects a coolant leak.In another embodiment of the present invention, the coolant leak detection unit is characterized in that the coolant leak detection unit is configured with a hydraulic pressure sensor that detects the hydraulic pressure of the coolant flowing through the internal circulation passage. In addition, one embodiment of the present invention is characterized in that the battery pack includes a case that houses the battery module, and a drainage valve that opens and closes a drainage outlet formed at the bottom of the case, and the drainage valve closes the drainage outlet by its own weight and opens the drainage outlet by buoyancy caused by the coolant accumulated in the case.In one embodiment of the present invention, when a portion of the first communication passage that communicates the discharge port of the coolant pump with the internal circulation passage inlet is defined as an external circulation passage first portion, the first discharge passage includes a first bypass passage that communicates an upstream location with a downstream location of the external circulation passage first portion, and a first branch passage that connects to the first valve provided at the upstream location communicated with the first bypass passage.In another embodiment of the present invention, when a portion of the second communication passage that communicates the internal circulation passage outlet with the heat exchanger inlet is defined as an external circulation passage second portion, the second discharge passage includes a second bypass passage that communicates an upstream location with a downstream location of the external circulation passage second portion, and a second branch passage that connects to the second valve provided at the downstream location communicated with the second bypass passage.

[0006] According to one embodiment of the present invention, a first switching unit is provided that includes a first communication passage, a first discharge passage, and a first valve, and when a coolant leak from the internal circulation passage is detected, the first valve is controlled to switch from the first communication passage to the first discharge passage. Therefore, by using the first switching unit to block the flow of coolant from the external circulation passage to the internal circulation passage inlet while discharging the coolant in the internal circulation passage to the outside of the battery pack, it is possible to prevent coolant from leaking and accumulating inside the battery pack, which is advantageous in protecting the battery modules and the like in the battery pack from the coolant. Furthermore, if a second switching unit is provided that includes a second communication passage, a second discharge passage, and a second valve, and the second valve is controlled to switch from the second communication passage to the second discharge passage when a coolant leak from the internal circulation passage is detected, the second switching unit can prevent the coolant from flowing from the external circulation passage to the internal circulation passage outlet while allowing the coolant in the internal circulation passage to be discharged outside the battery pack, thereby more reliably preventing the coolant from accumulating inside the battery pack and further advantageous in protecting the battery modules and the like in the battery pack from the coolant. Furthermore, if the coolant leak detection unit is configured with a hydraulic pressure sensor that detects the hydraulic pressure of the coolant flowing through the internal circulation passage, a change in the hydraulic pressure in the internal circulation passage caused by a crack or the like in the internal circulation passage can be detected early, allowing the coolant in the internal circulation passage to be quickly discharged outside the battery pack more quickly, further advantageous in protecting the battery modules and the like in the battery pack from the coolant. Furthermore, if a drain valve is provided that opens and closes the drain port formed in the bottom of the case, and the drain valve closes the drain port by its own weight and opens the drain port by the buoyancy of the coolant accumulated in the case, this extremely simple configuration using a drain valve is advantageous for protecting the battery modules and the like in the battery pack from the coolant. Furthermore, if the first drain path is configured with a first bypass path that connects the upstream and downstream locations of the first portion of the external circulation path, and a first branch path that connects to the first valve provided in the upstream location connected to the first bypass path, the first switching unit can be simplified, which is advantageous for reducing costs.Furthermore, if the second discharge path is configured with a second bypass path that connects the upstream location and downstream location of the second part of the external circulation path, and a second branch path that connects to the second valve provided at the downstream location to which the second bypass path is connected, the second switching unit can be simplified, which is advantageous in terms of reducing costs.

[0007] 4A and 4B are cross-sectional views of a drain valve of a battery pack cooling device according to an embodiment, with FIG. 4A showing a closed valve and FIG. 4B showing an open valve. A cross-sectional view of line X-X of FIG. 4A. An operational flowchart of a battery pack cooling device according to an embodiment.

[0008] The present invention will be described below with reference to the accompanying drawings, in which: a battery pack cooling device 10 according to the present embodiment is mounted on an electric vehicle using only a motor as a drive source, a hybrid vehicle, or a plug-in hybrid vehicle capable of external charging or external power supply, and is applied to a battery pack that supplies power to the motor.

[0009] As shown in FIG. 1 , the battery pack 12 includes a plurality of battery modules 14, an electrical unit 16 that controls the battery modules 14, a heat sink 18 that cools the battery modules 14 and the electrical unit 16, a tray 20 that houses the battery modules 14, the electrical unit 16, and the heat sink 18, and a case 24 that includes a cover 22 that covers the top of the tray 20. In this embodiment, the battery module 14 is composed of first, second, and third battery modules 14A, 14B, and 14C that are identical in shape and size. The first and second battery modules 14A and 14B are arranged side by side on the bottom wall 2002 of the tray 20 via mounting members (not shown). The third battery module 14C is arranged directly above the first battery module 14A at a distance via mounting members (not shown).

[0010] The heat sink 18 is composed of a lower heat sink 18A, rectangular in plan view, on which the bottom surfaces of the first and second battery modules 14A and 14B are placed, and an upper heat sink 18B, rectangular in plan view, on which the bottom surface of the third battery module 14C is placed. As shown in Fig. 2 , the lower heat sink 18A and the upper heat sink 18B are formed with circulation paths 26 and 28, respectively, through which a coolant circulates. For ease of explanation, Figs. 2 and 3 omit all components of the interior of the case 24 other than the lower heat sink 18A and the upper heat sink 18B, and illustrate the lower heat sink 18A and the upper heat sink 18B in plan view. The circulation path 26 of the lower heat sink 18A is composed of a lower first circulation path 26A and a lower second circulation path 26B. The lower first circulation path 26A extends linearly along one side of the lower heat sink 18A, with an inlet 2602 formed at one end for supplying the coolant and an outlet 2604 formed at the other end for discharging the coolant. The lower second circulation path 26B is formed in a serpentine shape over the entire portion of the lower heat sink 18A excluding the lower first circulation path 26A, with an inlet 2606 formed at one end for supplying the coolant and an outlet 2608 formed at the other end for discharging the coolant. Note that the shapes of the circulation paths of the lower heat sink 18A and the upper heat sink 18B described below are not limited to those shown in FIGS. 2 and 3 , and various conventionally known shapes can be used.

[0011] The circulation path 28 of the upper heat sink 18B is formed in a serpentine manner throughout the entire upper heat sink 18B, with an inlet 2802 formed at one end for supplying the coolant and an outlet 2804 formed at the other end for discharging the coolant. The outlet 2604 of the lower first circulation path 26A of the lower heat sink 18A is connected to the inlet 2802 of the circulation path 28 of the upper heat sink 18B by a first connecting member 30A, and the outlet 2804 of the circulation path 28 of the upper heat sink 18B is connected to the inlet 2606 of the lower second circulation path 26B of the lower heat sink 18A by a second connecting member 30B. The first and second connecting members 30A and 30B are formed, for example, from rubber or synthetic resin hoses. The coolant supplied to the inlet 2602 of the lower first circulation path 26A of the lower heat sink 18A flows through the lower first circulation path 26A and is then supplied from its outlet 2604 to the inlet 2802 of the circulation path 28 of the upper heat sink 18B via the first connecting member 30A. After flowing through this circulation path 28, the coolant is supplied again from the outlet 2804 to the inlet 2606 of the lower second circulation path 26B of the lower heat sink 18A via the second connecting member 30B, then flows through the lower second circulation path 26B and is eventually discharged from the outlet 2608 of the lower second circulation path 26B. Note that water or various conventionally known cooling liquids can be used as the coolant.

[0012] As shown in FIG. 1, the battery pack cooling device 10 of this embodiment is configured to include an internal circulation path 32, an external circulation path 34, a coolant leakage detection unit 36, a first switching unit 38, a second switching unit 40, a drain valve 42 (see FIGS. 4(A) and (B) and FIG. 5), and a control unit 44.

[0013] The internal circulation path 32 is provided in the battery pack 12, and coolant circulates through the internal circulation path 32 to cool the battery modules 14. In the present embodiment, the internal circulation path 32 is configured to include an inlet 3202 and an outlet 3204 of the internal circulation path 32 provided in the case 24. That is, as shown in FIG. 2 , the internal circulation path 32 includes a first circulation path 32A connecting the internal circulation path side inlet 3202 and the inlet 2602 of the lower first circulation path 26A of the lower heat sink 18A, a first connecting member 30A connecting the lower first circulation path 26A and the outlet 2604 of the lower first circulation path 26A and the inlet 2802 of the circulation path 28 of the upper heat sink 18B, a second connecting member 30B connecting the circulation path 28 of the upper heat sink 18B and the outlet 2804 of the circulation path 28 and the inlet 2606 of the lower second circulation path 26B of the lower heat sink 18A, and a second circulation path 32B connecting the lower second circulation path 26B and the outlet 2608 of the lower second circulation path 26B and the internal circulation path side outlet 3204.

[0014] The external circulation path 34 is provided outside the battery pack 12, and the external circulation path inlet 3402 is connected to the internal circulation path outlet 3204, and the external circulation path outlet 3404 is connected to the internal circulation path inlet 3202. In this embodiment, a backflow prevention valve 46, a heat exchanger 48, a coolant tank 50, and a coolant pump 52 are provided in this order in the external circulation path 34 along the upstream to downstream direction of the coolant flowing through the external circulation path 34. The backflow prevention valve 46 is provided between the internal circulation path outlet 3204 and the heat exchanger inlet 4802 of the heat exchanger 48 and prevents the coolant from flowing back from the heat exchanger inlet 4802 to the internal circulation path outlet 3204. The heat exchanger 48 cools the coolant by exchanging heat between the coolant and air.

[0015] The coolant pump 52 has an intake port 5202 connected to the heat exchanger-side outlet 4804 and an outlet port 5204 connected to the internal circulation path-side inlet 3202. When the coolant pump 52 is operated, the coolant is circulated between the external circulation path 34 and the internal circulation path 32.

[0016] The coolant tank 50 is connected between the heat exchanger side outlet 4804 and the intake port 5202 of the coolant pump 52, and stores the coolant. The coolant tank 50 replenishes the coolant to the internal circulation path 32 and the external circulation path 34 when the coolant level decreases, and is also used as a supply point for supplying coolant during maintenance work.

[0017] The coolant leakage detection unit 36 ​​detects the occurrence of a coolant leak from the internal circulation path 32. In this embodiment, the coolant leakage detection unit 36 ​​is configured as a hydraulic pressure sensor that detects the hydraulic pressure of the coolant flowing through the internal circulation path 32 and supplies a detection signal to the control unit 44, and is provided in the first circulation path 32A. In other words, the coolant leakage detection unit 36 ​​is provided between the internal circulation path inlet 3202 and the inlet 2602 of the lower first circulation path 26A of the lower heat sink 18A. The location where the hydraulic pressure sensor is provided is not limited to the internal circulation path 32, and it may be the external circulation path 34. Furthermore, the coolant leakage detection unit 36 ​​is not limited to a hydraulic pressure sensor, and may be configured as a flow rate sensor. Therefore, when coolant leaks due to a crack in the first connecting member 30A or the second connecting member 30B in the internal circulation path 32, for example, and the hydraulic pressure in the internal circulation path 32 drops below a certain value, the control unit 44 can determine that a coolant leak has occurred based on the detection signal supplied from the hydraulic pressure sensor.

[0018] 2, the first switching unit 38 has a first communication passage 38A that communicates between the discharge port 5204 of the coolant pump 52 and the internal circulation path inlet 3202, a first discharge passage 38B that blocks communication between the discharge port 5204 of the coolant pump 52 and the internal circulation path inlet 3202 and discharges the coolant in the internal circulation path 32 to the outside of the battery pack 12, as shown in FIG. 3, and a first valve 38C that can be switched to either the first communication passage 38A or the first discharge passage 38B. Therefore, when the first switching unit 38 switches the connection between the discharge port 5204 of the coolant pump 52 and the internal circulation path inlet 3202 to the first communication passage 38A, normal operation is performed in which the battery modules 14 are cooled by the coolant. In addition, when the first switching unit 38 switches the connection between the discharge port 5204 of the coolant pump 52 and the internal circulation path side inlet 3202 to the first discharge path 38B, the coolant in the internal circulation path 32 is discharged from the first discharge path 38B to the outside of the battery pack 12 while the flow of coolant W from the external circulation path 34 to the internal circulation path side inlet 3202 is blocked.

[0019] More specifically, when the portion of the first communication passage 38A of the external circulation passage 34 that communicates the discharge port 5204 of the coolant pump 52 and the internal circulation passage side inlet 3202 is defined as the external circulation passage first portion 34A, the first discharge passage 38B includes a first bypass passage 3802 that communicates an upstream location 3410 and a downstream location 3412 of the external circulation passage first portion 34A via a route separate from the external circulation passage 34, and a first branch passage 3804 that branches off from the upstream location 3410 with which the first bypass passage 3802 is communicated and discharges the coolant. The first valve 38C is provided at the upstream location 3410 with which the first bypass passage 3802 is communicated. 2, the first valve 38C is configured to be switchable between a normal position which allows the flow of coolant between the external circulation path first portion 34A and the internal circulation path side inlet 3202 and prohibits the flow of coolant from the first bypass path 3802 to the first branched path 3804, and a discharge position which prohibits the flow of coolant between the external circulation path first portion 34A and the internal circulation path side inlet 3202 and allows the flow of coolant from the first bypass path 3802 to the first branched path 3804, as shown in FIG. 3. In the normal position of the first valve 38C, the flow of coolant from the first bypass path 3802 to the first branched path 3804 is prohibited, and the coolant flows between the external circulation path first portion 34A and the internal circulation path side inlet 3202, thereby allowing the battery pack cooling device 10 to perform a normal cooling operation. When the first valve 38C is in the discharge position, the flow of coolant between the first part 34A of the external circulation path and the internal circulation path side inlet 3202 is prohibited, and the coolant flows from the first bypass path 3802 to the first branch path 3804, so that the coolant in the internal circulation path 32 is discharged from the first branch path 3804 to outside the battery pack 12.

[0020] As shown in Fig. 2, the second switching unit 40 has a second communication passage 40A that communicates between the internal circulation path outlet 3204 and the heat exchanger side inlet 4802, and as shown in Fig. 3, a second discharge passage 40B that blocks communication between the internal circulation path outlet 3204 and the heat exchanger side inlet 4802 and discharges the coolant in the internal circulation path 32 to the outside of the battery pack 12, and a second valve 40C that can be switched to either the second communication passage 40A or the second discharge passage 40B. Therefore, by switching the connection between the internal circulation path outlet 3204 and the heat exchanger side inlet 4802 to the second communication passage 40A by the second switching unit 40, normal operation in which the battery modules 14 are cooled by the coolant is performed. Furthermore, when the second switching unit 40 switches between the internal circulation path side outlet 3204 and the heat exchanger side inlet 4802 to the second discharge path 40B, the flow of the coolant W from the external circulation path 34 to the internal circulation path side outlet 3204 is blocked, and the coolant in the internal circulation path 32 is discharged from the second discharge path 40B to the outside of the battery pack 12.

[0021] More specifically, when the portion of the external circulation path 34 that connects the internal circulation path side outlet 3204 and the heat exchanger side inlet 4802 is defined as the external circulation path second portion 34B, the second discharge path 40B includes a second bypass path 4002 that connects an upstream location 3420 and a downstream location 3422 of the external circulation path second portion 34B via a path separate from the external circulation path 34, and a second branch path 4004 that branches off from the downstream location 3422 connected to the second bypass path 4002. The second valve 40C is provided at the downstream location 3422 connected to the second bypass path 4002. 2, the second valve 40C is configured to be switchable between a normal position which allows the flow of coolant between the internal circulation path side outlet 3204 and the external circulation path second portion 34B and prohibits the flow of coolant from the second bypass path 4002 to the second branch path 4004, and a discharge position which prohibits the flow of coolant between the internal circulation path side outlet 3204 and the external circulation path second portion 34B and allows the flow of coolant from the second bypass path 4002 to the second branch path 4004, as shown in FIG. 3. In the normal position of the second valve 40C, the flow of coolant from the second bypass path 4002 to the second branch path 4004 is prohibited, and the coolant flows between the internal circulation path side outlet 3204 and the external circulation path second portion 34B, thereby allowing the battery pack cooling device 10 to perform a normal cooling operation. When the second valve 40C is in the discharge position, the flow of coolant between the internal circulation path side outlet 3204 and the second part of the external circulation path 34B is prohibited, and the coolant flows from the second bypass path 4002 to the second branch path 4004, so that the coolant in the internal circulation path 32 is discharged from the second branch path 404 to the outside of the battery pack 12.

[0022] As shown in Figures 4(A) and (B), the drain valve 42 opens and closes a drain port 54 formed in the bottom wall 2002 of the tray 20, which is the lower part of the case 24. The drain valve 42 closes the drain port 54 by its own weight and opens the drain port 54 by the buoyancy of the cooling liquid W accumulated in the case 24. To explain in detail, as shown in Figure 4(A), the drain valve 42 is configured to include a cylindrical portion 56 provided with the drain port 54 and attached to the bottom wall 2002 of the tray 20, and a valve body 58, and a through hole in the cylindrical portion 56 is formed as the drain port 54. Valve element 58 includes a disk portion 5802 large enough to cover cylindrical portion 56, an outer cylindrical portion 5804 extending vertically from the outer periphery of disk portion 5802, an inner cylindrical portion 5806 extending vertically from the center of disk portion 5802, and a seal portion 5808 attached to the underside of disk portion 5802 between outer cylindrical portion 5804 and inner cylindrical portion 5806. As shown in Figures 4(A) and 5, an upper portion of inner cylindrical portion 5806 is provided with a plurality of communication holes 5810 that communicate between the outer peripheral surface and the inner peripheral surface of inner cylindrical portion 5806.

[0023] As shown in FIG. 4A , the drain valve 42 is configured so that the weight of the valve element 58 causes the seal portion 5808 to come into contact with the upper end surface 5602 of the tubular portion 56, thereby closing the discharge port 54. The valve element 58 is made of a material, such as synthetic resin, that has a lower specific gravity than the coolant W. As shown in FIG. 4B , when the coolant W accumulates on the bottom wall 2002, the valve element 58 floats up and communicates with the interior of the inner tubular portion 5806 via the inner circumferential surface of the outer tubular portion 5804 and the outer circumferential surface of the tubular portion 56, between the seal portion 5808 and the upper end surface 5602 of the tubular portion 56, and through a plurality of communication holes 5810, and the coolant W accumulated in the case 24 is discharged downward via the through-hole (discharge port 54) in the tubular portion 56.

[0024] When the coolant leakage detection unit 36 ​​detects a coolant leakage, in other words, when the control unit 44 determines that a coolant leakage has occurred based on the detection signal supplied from the coolant leakage detection unit 36, the control unit 44 stops the coolant pump 52, controls the first valve 38C to switch from the first communication passage 38A to the first discharge passage 38B, and controls the second valve 40C to switch from the second communication passage 40A to the second discharge passage 40B. In detail, the control unit 44 switches the first switching unit 38 from the first communication passage 38A to the first discharge passage 38B by switching the first valve 3806 from the normal position to the discharge position, and the control unit 44 switches the second switching unit 40 from the second communication passage 40A to the second discharge passage 40B by switching the second valve 40C from the normal position to the discharge position.

[0025] Next, the operation will be described with reference to the flowchart of FIG. 6 . It is assumed that the battery pack 12 is in operation, with power supplied from the battery pack 12 to the drive motor or the battery pack 12 being charged. First, the control unit 44 determines whether the coolant leak detection unit 36 ​​has detected a coolant leak (step S10). If the result of step S10 is negative, the process returns to step S10, and the battery pack cooling device 10 performs normal cooling operation. If the result of step S10 is positive, the control unit 44 stops the coolant pump 52 (step S12) and switches the first valve 3806 and the second valve 40C from their normal positions to their discharge positions (step S14). As a result, the coolant in the internal circulation path 32 is discharged to the outside of the battery pack 12 via the first discharge path 38B and the second discharge path 40B (step S16). At this time, the first switching unit 38 blocks the flow of the coolant W from the external circulation path 34 to the internal circulation path inlet 3202, and the second switching unit 40 blocks the flow of the coolant W from the external circulation path 34 to the internal circulation path outlet 3204. Therefore, even if a leak of the coolant W occurs due to a crack in the internal circulation path 32, the coolant in the internal circulation path 32 is discharged to the outside of the battery pack 12 via the first discharge path 38B and the second discharge path 40B, thereby preventing the coolant W accumulated in the battery pack 12 from deteriorating the first, second, and third battery modules 14A, 14B, and 14C and the electrical component 16. Furthermore, when the drain valve 42 opens the discharge port 54 due to the coolant W leaking from the internal circulation path 32 onto the tray 20, the coolant W is discharged from the discharge port 54 to the outside of the tray 20, thereby preventing deterioration of the first, second and third battery modules 14A, 14B and 14C and the electrical equipment 16 due to the coolant W accumulated in the tray 20.

[0026] According to this embodiment, a first switching unit 38 is provided which includes a first communication passage 38A that connects the discharge port 5204 of the coolant pump 52 and the internal circulation path side inlet 3202, a first discharge passage 38B that blocks the connection between the discharge port 5204 of the coolant pump 52 and the internal circulation path side inlet 3202 and discharges the coolant in the internal circulation path 32 to the outside of the battery pack 12, and a first valve 38C that can be switched to either the first communication passage 38A or the first discharge passage 38B, and when a coolant leak is detected from the internal circulation path 32, the first valve 38C is controlled to switch from the first communication passage 38A to the first discharge passage 38B. Therefore, by using the first switching unit 38 to prevent the flow of coolant W from the external circulation path 34 to the internal circulation path side inlet 3202 while discharging the coolant W in the internal circulation path 32 outside the battery pack 12, it is possible to prevent the coolant W from leaking and accumulating within the battery pack 12, which is advantageous in protecting the battery modules 14 and the like within the battery pack 12 from the coolant W.

[0027] In addition, in this embodiment, a second switching unit 40 is provided which includes a second communication passage 40A that connects the internal circulation path side outlet 3204 and the heat exchanger side inlet 4802, a second discharge passage 40B that blocks communication between the internal circulation path side outlet 3204 and the heat exchanger side inlet 4802 and discharges the coolant in the internal circulation path 32 to the outside of the battery pack 12, and a second valve 40C that can be switched to either the second communication passage 40A or the second discharge passage 40B, and when a coolant leak is detected from the internal circulation path 32, the second valve 40C is controlled to switch from the second communication passage 40A to the second discharge passage 40B. Therefore, the second switching unit 40 can prevent the flow of coolant W from the external circulation path 34 to the internal circulation path side outlet 3204 while discharging the coolant W in the internal circulation path 32 outside the battery pack 12, which more reliably prevents the coolant W from accumulating in the battery pack 12 and is even more advantageous in protecting the battery modules 14 and the like in the battery pack 12 from the coolant W.

[0028] The coolant leakage detection unit 36 ​​may be, for example, a liquid sensor provided on the bottom wall 2002 of the cover 22 to detect the presence or absence of liquid. However, if the coolant leakage detection unit 36 ​​is configured as a liquid pressure sensor that detects the liquid pressure of the coolant W flowing through the internal circulation path 32, as in the present embodiment, a change in the liquid pressure in the internal circulation path 32 caused by a crack or the like in the internal circulation path 32 can be detected early. This allows the first switching unit 38 and the second switching unit 40 to quickly drain the coolant W in the internal circulation path 32 to the outside of the battery pack 12 at an earlier stage, which is even more advantageous in protecting the battery modules 14 and the like in the battery pack 12 from the coolant W.

[0029] Furthermore, in this embodiment, a drain valve 42 is provided that opens and closes a drain port 54 formed in the bottom of the case 24, and the drain valve 42 closes the drain port 54 by its own weight and opens the drain port 54 by the buoyancy of the coolant W accumulated in the case 24. Therefore, the coolant W that has leaked from the internal circulation path 32 and accumulated in the case 24 can be quickly drained outside the battery pack 12 by the drain valve 42. Therefore, an extremely simple configuration using the drain valve 42 is advantageous in protecting the battery modules 14 and the like in the battery pack 12 from the coolant W without requiring control by the control unit 44.

[0030] Furthermore, in this embodiment, the first discharge path 38B is composed of the first bypass path 3802 that connects the upstream location 3410 and the downstream location 3412 of the first portion 34A of the external circulation path, and the first branch path 3804 that connects to the first valve 38C that is provided at the upstream location 3410 to which the first bypass path 3802 is connected. This simplifies the first switching unit 38, which is advantageous in reducing costs.

[0031] Furthermore, in this embodiment, the second discharge path 40B is composed of a second bypass path 4002 that connects the upstream location 3420 and the downstream location 3422 of the second portion 34B of the external circulation path, and a second branch path 4004 that connects to the second valve 40C provided at the downstream location 3422 to which the second bypass path 4002 is connected. This simplifies the second switching unit 40, which is advantageous in reducing costs.

[0032] In the embodiment, a case where a plurality of battery modules 14 are arranged one above the other has been described, but the present invention is also applicable to a configuration in which all of the battery modules 14 are arranged side by side on the bottom wall 2002 of the tray 20, and is applicable regardless of the arrangement structure of the plurality of battery modules 14. Furthermore, in the present embodiment, a case where the heat sink 18 is composed of a lower heat sink 18A and an upper heat sink 18B has been described, but the number and arrangement structure of the heat sinks 18 are not limited.

[0033] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0034] This application is based on a Japanese patent application (Patent Application No. 2023-188431) filed on November 2, 2023, the contents of which are incorporated herein by reference.

[0035] REFERENCE SIGNS LIST 10 Battery pack cooling device 12 Battery pack 14 Battery module 14A First battery module 14B Second battery module 14C Third battery module 16 Electrical component 18 Heat sink 18A Lower heat sink 18B Upper heat sink 20 Tray 2002 Bottom wall 22 Cover 24 Case 26 Circulation path of lower heat sink 26A Lower first circulation path 26B Lower second circulation path 2602 Inlet of lower first circulation path 2604 Outlet of lower first circulation path 2606 Inlet of lower second circulation path 2608 Outlet of lower second circulation path 28 Circulation path of upper heat sink 2802 Inlet 2804 Outlet 30A First connecting member 30B Second connecting member 32 Internal circulation path 3202 Internal circulation path inlet 3204 Internal circulation path outlet 32A First circulation path 32B Second circulation path 34 External circulation path 3402 External circulation path inlet 3404 External circulation path outlet 34A External circulation path first section 3410 Upstream location 3412 Downstream location 34B External circulation path second section 3420 Upstream location 3422 Downstream location 36 Coolant leak detection section 38 First switching section 38A First communication path 38B First discharge path 38C First valve 3802 First bypass path 3804 First branch path 40 Second switching section 40A Second communication path 40B Second discharge path 40C Second valve 4002 Second bypass path 4004 Second branch path 42 Drain valve 44 Control section 46 Backflow prevention valve 48 Heat exchanger 4802 Heat exchanger side inlet 4804 Heat exchanger side outlet 50 Coolant tank 52 Coolant pump 5202 Intake port 5204 Discharge port 54 Discharge port 56 Cylinder portion 5602 Upper end surface 58 Valve body 5802 Disk portion 5804 Outer cylinder portion 5806 Inner cylinder portion 5808 Seal portion 5810 Communication hole

Claims

1. A cooling device for a battery pack comprising: an internal circulation path provided within a battery pack through which a coolant circulates to cool a battery module; and an external circulation path provided outside the battery pack and connected to the internal circulation path, a heat exchanger for cooling the coolant provided in the external circulation path, and a coolant pump provided at a portion connecting a heat exchanger side outlet of the heat exchanger and an internal circulation path side inlet of the internal circulation path, the cooling device for a battery pack comprising: a coolant leakage detection unit for detecting occurrence of coolant leakage from the internal circulation path; a first communication path connecting an outlet of the coolant pump and an internal circulation path side inlet; a first discharge path for blocking communication between the discharge port and the internal circulation path side inlet and discharging the coolant in the internal circulation path to the outside of the battery pack; a first switching unit having a first valve that can be switched to either the first communication path or the first discharge path; and a control unit for controlling the first valve to switch from the first communication path to the first discharge path when a coolant leakage is detected by the coolant leakage detection unit.

2. A cooling device for a battery pack as described in claim 1, further comprising: a second communication passage that communicates between the internal circulation path side outlet of the internal circulation path and the heat exchanger side inlet of the heat exchanger; a second discharge passage that blocks the connection between the internal circulation path side outlet and the heat exchanger side inlet and discharges the cooling liquid in the internal circulation path to the outside of the battery pack; and a second switching unit having a second valve that can be switched to either the second communication passage or the second discharge passage, wherein when a cooling liquid leak is detected by the cooling liquid leak detection unit, the control unit controls the second valve to switch from the second communication passage to the second discharge passage.

3. The battery pack cooling device according to claim 1 or 2, characterized in that the coolant leakage detection unit is composed of a liquid pressure sensor that detects the liquid pressure of the coolant flowing through the internal circulation path.

4. A cooling device for a battery pack as claimed in claim 1 or 2, characterized in that the battery pack comprises a case that houses the battery modules, and a drainage valve is provided for opening and closing a drainage outlet formed in the lower part of the case, and the drainage valve closes the drainage outlet by its own weight and opens the drainage outlet by buoyancy caused by the cooling liquid accumulated in the case.

5. A cooling device for a battery pack as described in claim 1, characterized in that, when a portion of the external circulation path in the first communication passage that communicates the discharge port of the cooling liquid pump and the internal circulation path inlet is defined as an external circulation path first portion, the first discharge path comprises: a first bypass path that communicates an upstream location and a downstream location of the external circulation path first portion, and a first branch path that connects to the first valve provided at the upstream location to which the first bypass path is connected.

6. A cooling device for a battery pack as described in claim 2, characterized in that, when a portion of the external circulation path in the second communication passage that communicates the internal circulation path outlet and the heat exchanger side inlet is defined as an external circulation path second portion, the second discharge path comprises a second bypass path that communicates an upstream location and a downstream location of the external circulation path second portion, and a second branch path that connects to the second valve provided at the downstream location to which the second bypass path is connected.

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