Safety device for electric vehicle battery

Abstract

To provide a safety device for an electric vehicle battery which can suppress fire risk caused by a cooling water for cooling a battery at the time of a short circuit of the battery.SOLUTION: A safety device 10 for an electric vehicle battery includes: a battery pack 20 in which a battery 24 is stored; and a cooling circuit 11 having a circulation flow path 12 in which a cooling water circulates and where a part of the circulation flow path 12 passes through the battery pack 20. The safety device 10 includes: a branch path 32 that branches from the circulation flow path 12 that passes inside the battery pack 20; and a path cut-off part 28 that cuts off the communication state between the circulation flow path 12 and the branch path 32. When the temperature of the cooling water is high exceeding the predefined value, the path cut-off part 28 enables a communication state between the circulation flow path 12 and the branch path 32 by being broken or in an open state.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a safety device for a battery for an electric vehicle, and more particularly to a safety device for a battery for an electric vehicle that is provided with a cooling circuit for cooling the battery. [Background technology]

[0002] Electric vehicles, such as electric cars and hybrid cars, are equipped with a battery pack that houses a battery that serves as the vehicle's driving source. If the temperature of the battery rises too much, it will lead to a decrease in performance and a shortened lifespan, so electric vehicles are equipped with a cooling circuit to cool the battery. In general, the cooling circuit is a circuit through which coolant circulates and includes a radiator that cools the coolant. A part of the cooling circuit passes through the battery pack, and the battery is cooled by the coolant flowing through this cooling circuit.

[0003] In an electric vehicle, when an impact is applied to the battery pack, the battery may short-circuit, which may lead to a fire. In recent years, expectations for vehicle safety have been increasing, and a technology has been developed for injecting a fire extinguishing agent into the battery pack in an electric vehicle equipped with a battery pack in the event of a fire from the battery.

[0004] For example, Patent Document 1 describes a fire extinguishing structure in which a cooling circuit for cooling a battery is connected to an extinguishing agent injection passage for injecting a fire extinguishing agent into a battery pack from outside the vehicle body. The extinguishing agent injection passage is connected to a portion of the cooling circuit outside the battery pack, and the cooling circuit in the battery pack is provided with a weak part that is broken by the pressure of the fire extinguishing agent supplied into the cooling circuit through the extinguishing agent injection passage. In this fire extinguishing structure, when a fire occurs in the battery, the battery can be immersed in the fire extinguishing agent by supplying the fire extinguishing agent through the extinguishing agent injection passage from outside the vehicle body, thereby extinguishing the fire. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-136266 A Summary of the Invention [Problem to be solved by the invention]

[0006] If a fire occurs inside the battery pack, the cooling circuit running through the battery pack may be damaged, causing the coolant to leak. If the leaked coolant is electrolyzed inside the battery pack, hydrogen is generated, and if the generated hydrogen ignites, the fire may become larger. Therefore, there is a need for the development of a safety device that can suppress fires caused by coolant.

[0007] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a safety device for an electric vehicle battery that can suppress a fire caused by cooling water used to cool the battery when the battery is short-circuited. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, one embodiment of the present invention is a safety device for an electric vehicle battery comprising a battery pack in which a battery is housed, and a cooling circuit having a circulation flow path through which coolant circulates, with a part of the circulation flow path passing through the battery pack, the safety device further comprising a branch passage branching off from the circulation flow path passing through the battery pack, and a passage blocking unit blocking communication between the circulation flow path and the branch passage, the passage blocking unit being broken or opened when the temperature of the coolant reaches a high temperature state exceeding a predetermined value, thereby connecting the circulation flow path and the branch passage. Effect of the Invention

[0009] The noise suppression structure of the present invention is capable of effectively absorbing high-frequency noise while maintaining cooling performance in a cooling system for electrical equipment, thereby suppressing increases in manufacturing costs and improving space efficiency when mounting components. [Brief description of the drawings]

[0010] [Figure 1] 1 is a plan view showing a schematic diagram of a safety device for an electric vehicle battery according to an embodiment of the present invention; [Diagram 2] 1 is a cross-sectional view that illustrates a schematic diagram of a safety device for a battery for an electric vehicle. [Diagram 3] 4 is an explanatory diagram showing a portion of a cooling circuit in the battery pack that is connected to a branch passage; FIG. [Figure 4] 4A and 4B are diagrams illustrating the operation of a safety device for an electric vehicle battery. [Diagram 5] 4A and 4B are diagrams illustrating the operation of a safety device for an electric vehicle battery. [Figure 6] 4A and 4B are diagrams illustrating the operation of a safety device for an electric vehicle battery. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Fig. 1 is a plan view that shows a schematic diagram of a safety device 10 for an electric vehicle battery according to one embodiment of the present invention, and Fig. 2 is a cross-sectional view that shows a schematic diagram of the safety device 10 for an electric vehicle battery. The safety device 10 for an electric vehicle battery (hereinafter also simply referred to as "safety device 10") is applied to an electric vehicle 1 such as an electric car or a hybrid car that is equipped with a battery 24 that serves as a drive source for the vehicle. The electric vehicle 1 is equipped with a battery pack 20 that houses the battery 24 that serves as a drive source. In Fig. 1, the left side is the front side of the vehicle 1, and the right side is the rear side of the vehicle 1.

[0012] The safety device 10 includes a cooling circuit 11 for cooling the battery 24, a battery pack 20 in which the battery 24 is housed, and an extinguishing agent introduction section 30 for introducing an extinguishing agent into the battery pack 20. The cooling circuit 11 has a circulation flow path 12 through which cooling water circulates, and the extinguishing agent introduction section 30 includes a branch passage 32 branched off from the circulation flow path 12.

[0013] The cooling circuit 11 includes a water pump 14 and a radiator 16, both of which are disposed on the circulation flow path 12. When the water pump 14 is driven, the cooling water in the circulation flow path 12 is pumped out by the pressure of the water pump 14 and circulates within the circulation flow path 12. A part of the circulation flow path 12 passes through the battery pack 20. When the cooling water passes through the radiator 16, heat is released and the temperature drops. The operation of the water pump 14 is controlled by a control device (not shown), and the water pump 14 is in an operating state in a normal state where it cools the battery 24, and is in an operating state in an abnormal state where the circuit of the battery 24 is shorted.

[0014] As shown in Fig. 2, the battery pack 20 has therein a battery 24 and a heater 26 for heating the battery 24, and a part of the circulation flow path 12 of the cooling circuit 11 is disposed within the battery pack 20. The battery 24 is configured as a battery module in which a plurality of battery cells are connected in series or parallel. In the example shown in Fig. 2, the heater 26 is disposed above the battery 24, and the circulation flow path 12 is disposed below the battery 24, but the arrangement of these in the battery pack 20 is not limited to this and can be changed as appropriate. For example, the circulation flow path 12 may be disposed above the battery 24 or between the battery cells.

[0015] The extinguishing agent introduction section 30 includes a branch passage branching off from the circulation passage 12 passing through the battery pack 20, and an extinguishing agent injection passage 40 connected in communication with the branch passage 32. One end of the branch passage 32, i.e., a downstream end in the flow direction of the cooling water described below, is connected in communication with the battery pack 20. A passage blocking section 28 that blocks communication between the circulation passage 12 and the branch passage 32 is provided at the connection between the circulation passage 12 and the branch passage 32.

[0016] When the temperature of the cooling water in the circulation flow path 12 becomes a high temperature state exceeding a predetermined value at the connection portion between the circulation flow path 12 and the branch passage 32, the passage blocking unit 28 breaks or opens, thereby connecting the circulation flow path 12 and the branch passage 32. In this embodiment, a thermostat is used as the passage blocking unit 28. When the temperature of the cooling water in the circulation flow path 12 is equal to or lower than a predetermined value, the thermostat is in a closed state, i.e., in a blocked state, to prevent the cooling water from flowing into the branch passage 32, and when the temperature of the cooling water exceeds the predetermined value, the thermostat is in an open state to allow the cooling water to flow out into the branch passage 32. As an example, the temperature of the cooling water when flowing through the circulation flow path 12 in the battery pack 20 is up to about 60°C, and the temperature of the cooling water (i.e., the predetermined value) for the passage blocking unit 28 to be connected can be 70°C to 80°C.

[0017] Note that the passage blocking portion 28 is not limited to a thermostat, and may be, for example, a fragile portion formed to break when the cooling water becomes hot and the pressure acting on the passage blocking portion 28 becomes high. Alternatively, the passage blocking portion 28 may be a control valve that is controlled to open and close by a control device (not shown). When the passage blocking portion 28 is a control valve, a temperature sensor detects the temperature of the cooling water in the circulation flow path 12 passing through the battery pack 20, and the control valve may be structured to be closed when the temperature detected by the temperature sensor is equal to or lower than a predetermined value, and open when the temperature detected by the temperature sensor exceeds the predetermined value.

[0018] The branch passage 32 includes a piston 34 disposed in the passage, a stopper member 35 for restricting the movement of the piston 34, a fire extinguishing agent 36 sealed in the passage, and a first check valve 38. The piston 34 is configured to be movable downstream in the branch passage 32 by the pressure of the cooling water flowing into the branch passage 32. Here, the downstream side of the branch passage 32 means the downstream side in the flow direction of the cooling water flowing from the circulation flow passage 12 into the branch passage 32, and means the end side of the branch passage 32 connected to the battery pack 20. A stopper member 35 for restricting the movement of the piston 34 is provided downstream of the piston 34.

[0019] The first check valve 38 is a valve body that permits flow from the branch passage 32 side to the battery pack 20 side and prohibits flow in the opposite direction, and is installed downstream of the stopper member 35 in the branch passage 32. In this embodiment, the first check valve 38 is disposed at the connection between the branch passage 32 and the battery pack 20.

[0020] The extinguishing agent 36 is sealed in the passage between the piston 34 and the first check valve 38. The extinguishing agent 36 may be in any suitable form, such as gas, liquid, or powder. When the extinguishing agent 36 is in liquid or powder form, a piston (not shown) may be provided downstream of the stopper member 35 to push the extinguishing agent 36 into the battery pack 20.

[0021] As shown in FIG. 2, the safety device 10 of this embodiment has a plurality of passage closing parts 28 in the circulation flow path 12 passing through the battery pack 20, and the upstream end of the branch passage 32 is connected to each passage closing part 28. The branch passage 32 is branched into a plurality of parts on the upstream side so as to be connected to the circulation flow path 12 at each passage blocking part 28, and is formed so that the passages merge on the downstream side. FIG. 3 is an explanatory diagram showing a part of the circulation flow path 12 in the battery pack 20 that is connected to the branch passage 32, that is, a part where the passage blocking part 28 is provided, and is a plan view of the battery 24 seen from the upper side of the vehicle body. In FIG. 3, the flow direction of the cooling water flowing through the circulation flow path 12 is indicated by an arrow. In this embodiment, the passage blocking part 28 is provided in the area surrounded by the symbol A in FIG. 3.

[0022] The extinguishing agent injection passage 40 constituting the extinguishing agent introduction section 30 is connected in communication with the passage between the stopper member 35 and the first check valve 38 in the branch passage 32. The extinguishing agent injection passage 40 is a passage through which the extinguishing agent can be injected from outside the vehicle body, and in this embodiment, as shown in FIG. 1, an extinguishing agent injection port 41 is provided on the side of the vehicle body 2. The extinguishing agent injection port 41 can be closed by a cover member (not shown). A second check valve 42 is provided at the connection between the extinguishing agent injection passage 40 and the branch passage 32. The second check valve 42 is a valve body that allows a flow from the extinguishing agent injection passage 40 side to the branch passage 32 side and prohibits a flow in the opposite direction.

[0023] Next, the operation of the safety device 10 will be described with reference to Figures 4, 5, and 6. In Figures 4 and 5, the cooling water in a high temperature state is indicated by reference symbol 18. In the electric vehicle 1, when the battery pack 20 is subjected to an impact due to a vehicle accident or the like, a short circuit occurs in the battery circuit, which may cause a fire in the battery 24. In the event of such an accident, the water pump 14 of the cooling circuit 11 is brought to a stopped state. As shown in Figure 4, when the temperature in the battery pack 20 rises due to a short circuit in the battery circuit, the cooling water in the circulation flow path 12 passing through the battery pack 20 becomes in a high temperature state.

[0024] As shown in FIG. 5, when the cooling water becomes in a high temperature state and the pressure in the circulation flow path 12 becomes high, the passage blocking portion 28 opens, and the cooling water in the cooling circuit 11 flows into the branch passage 32. In this way, the cooling water in the circulation flow path 12 flows into the branch passage 32 and flows out of the battery pack 20, so that the cooling water in the circulation flow path 12 can be prevented from leaking into the battery pack 20 in the event of a fire. This also makes it possible to prevent the cooling water in the cooling circuit 11 from leaking into the battery pack 20 and the leaked cooling water from being electrolyzed to generate hydrogen. If hydrogen is generated in the battery pack 20, the hydrogen that has become hot may ignite or explode. In the safety device 10 of this embodiment, the cooling water is caused to flow out into the branch passage 32, so that the leakage of the cooling water into the battery pack 20 is prevented, and a fire caused by the cooling water can be suppressed.

[0025] As shown in FIG. 6, when the cooling water flows out into the branch passage 32, the cooling water flowing into the branch passage 32 moves the piston 34 downstream. This movement of the piston 34 presses the fire extinguishing agent 36 sealed in the branch passage 32 to move downstream, i.e., toward the battery pack 20, and the moved fire extinguishing agent 36 passes through the first check valve 38 and is introduced into the battery pack 20. This introduction of the fire extinguishing agent 36 can suppress and extinguish a fire occurring in the battery pack 20. In this way, in the safety device 10 of the present embodiment, the fire extinguishing agent 36 sealed in the branch passage 32 can be automatically introduced into the battery pack 20 by using the cooling water that has entered the branch passage 32, and the generated fire can be quickly suppressed and extinguished.

[0026] 6, when additional extinguishing agent is injected into the battery pack 20 from outside the vehicle body through the extinguishing agent injection passage 40, the injected extinguishing agent passes through the second check valve 42 and is injected into the battery pack 20 through the branch passage 32. This allows the battery pack 20 to be filled with extinguishing agent to extinguish the fire.

[0027] In the safety device 10, if the passage blocking section 28 is a weak section, the high pressure inside the circulation passage 12 when the above-mentioned accident occurs will cause the weak section to break and the cooling water to flow into the branch passage 32. In the safety device 10 of the present embodiment, since the passage blocking section 28 is configured as a thermostat, if the cooling circuit 11 is not damaged after the cooling water in the circulation passage 12 flows out to the branch passage 32, the thermostat can be closed to reinject the cooling water into the circulation passage 12 of the cooling circuit 11, thereby reusing the cooling circuit 11.

[0028] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the invention.

[0029] For example, the safety device 10 for an electric vehicle battery according to the present invention may be configured to include, in addition to the battery pack 20 and the cooling circuit 11, at least a branch passage 32 that allows the cooling water to flow out of the cooling circuit 11 and the battery pack 20, and a passage blocking unit 28 that is disposed at a connection portion of the branch passage 32 with the circulation flow path 12. For example, the safety device 10 may be configured such that the piston 34 and the extinguishant 36 are not disposed in the branch passage 32, and the cooling water that has flowed into the branch passage 32 can be discharged out of the vehicle body 2. Furthermore, when the extinguishant introduction unit 30 does not have the extinguishant injection passage 40, the safety device 10 may not require the stopper member 35. [Explanation of symbols]

[0030] 1 Electric vehicles 2. Body 10 Safety devices for batteries in electric vehicles 11 Cooling circuit 12 Circulation flow path 14 Water Pump 16 Radiator 20 Battery pack 24 Battery 28 Passage Block 30 Extinguishing agent introduction section 32 Branch Passage 34 Piston 36 Fire extinguishing agents 38 First check valve 40 Extinguishing agent injection passage 42 Second check valve

Claims

1. A battery pack containing a battery; a cooling circuit having a circulation flow path through which cooling water circulates, a portion of the circulation flow path passing through the battery pack; A safety device for an electric vehicle battery comprising: a branch passage branching from the circulation flow path passing through the battery pack; a passage blocking portion that blocks communication between the circulation passage and the branch passage; Equipped with The safety device for an electric vehicle battery is characterized in that the passage blocking section opens or breaks when the temperature of the cooling water reaches a high temperature state exceeding a predetermined value, thereby connecting the circulation flow path and the branch passage.

2. a downstream end of the branch passage is connected to the battery pack; The branch passage is a piston that moves downstream within a passage due to the inflow of the cooling water; A check valve disposed downstream of the piston; a fire extinguishing agent sealed in a passage between the piston and the check valve and introduced into the battery pack through the check valve by movement of the piston; 2. The safety device for an electric vehicle battery according to claim 1, further comprising:

3. a stopper member that restricts movement of the piston; a fire extinguishing agent injection passage that is connected to a passage between the stopper member and the check valve and that allows an extinguishing agent to be injected from outside the vehicle body; a check valve provided at a connection between the extinguishing agent injection passage and the branch passage, the check valve allowing a flow from the extinguishing agent injection passage side to the branch passage side; 3. The safety device for an electric vehicle battery according to claim 2, further comprising:

4. 3. The safety device for a battery for an electric vehicle according to claim 1, wherein the passage blocking portion is constituted by a thermostat.

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