Battery cooling device

Abstract

To provide a battery cooling device capable of efficiently cooling a battery cell in accordance with load.SOLUTION: A battery cooling device for cooling a battery module composed of a plurality of battery cells with cooling liquid includes: a first cooler cooling an electrode terminal of a battery cell and a bus bar connected to the electrode terminal with cooling liquid; a second cooler cooling the battery cell from a bottom surface side of the battery cell with the cooling liquid; and a distribution pipe dividing the cooling liquid into the first cooler and the second cooler for supply. The distribution pipe has: an upstream pipe in which the cooling liquid flows; a first supply pipe branched from the upstream pipe and communicating with the upstream pipe and the first cooler; and a second supply pipe branched from the upstream pipe and communicating with the upstream pipe and the second cooler. Inside the first supply pipe is installed a flow rate control valve for controlling flow rate of the cooling liquid supplied for the first cooler. The flow rate control valve opens / closes in accordance with a flow rate of the cooling liquid communicating with the upstream pipe and opens as the flow rate of the cooling liquid communicating with the upstream pipe increases.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a battery cooling device for cooling a battery module, in which a pressurized refrigerant is circulated in a case that houses a plurality of battery cells, and the entire battery cells are cooled by the refrigerant.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to suppress the shortening of the life of the battery cells due to heat generation, it is desirable to sufficiently cool the entire battery cells and avoid the local high-temperature state of the electrodes of the battery cells during high load. However, although the configuration described in Patent Document 1 can cool the entire battery cells by the refrigerant supplied into the case, it does not correspond to local heat generation of the electrodes.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a battery cooling device capable of efficiently cooling battery cells according to the load.

Means for Solving the Problems

[0006] The present invention relates to a battery cooling device for cooling a battery module composed of a plurality of battery cells with a coolant, comprising: a first cooler for cooling an electrode terminal of the battery cell and a bus bar connected to the electrode terminal with the coolant; a second cooler for cooling the battery cell with the coolant from the bottom surface side of the battery cell; and a distribution pipe for diverting and supplying the coolant to the first cooler and the second cooler. The distribution pipe has an upstream pipe into which the coolant flows, a first supply pipe branched from the upstream pipe and communicating the upstream pipe with the first cooler, and a second supply pipe branched from the upstream pipe and communicating the upstream pipe with the second cooler. A flow rate adjustment valve for adjusting the flow rate of the coolant supplied to the first cooler is provided inside the first supply pipe. The flow rate adjustment valve opens and closes according to the flow rate of the coolant flowing through the upstream pipe, and opens as the flow rate of the coolant flowing through the upstream pipe increases.

Effects of the Invention

[0007] In the present invention, when the load is high, the flow rate of the coolant increases as the temperature of the coolant rises. Therefore, the flow rate adjustment valve provided in the first supply pipe opens and closes according to the flow rate of the coolant, so that the battery cells can be efficiently cooled according to the load.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiment for Carrying Out the Invention

[0009] Hereinafter, the battery cooling device in the embodiment of the present invention will be specifically described. Note that the present invention is not limited to the embodiments described below.

[0010] FIG. 1 is a schematic diagram showing a battery cooling device in an embodiment. The battery cooling device 1 cools the battery module 2 with a coolant. The battery cooling device 1 includes a bus bar cooler 10, a bottom surface cooler 20, and a distribution pipe 30. In the battery module 2, as shown in FIG. 2, the battery cells 3 are cooled by the bus bar cooler 10 and the bottom surface cooler 20. The battery module 2 has a structure in which a plurality of battery cells 3 are stacked, and the terminals of the battery cells 3 are electrically connected by a bus bar. The bus bar cooler 10 is a first cooler, and the bottom surface cooler 20 is a second cooler.

[0011] The bus bar cooler 10 is a cooler that cools the bus bar and the electrode terminals of the battery cells 3. The bus bar cooler 10 is provided above the battery module 2 and has cooling pipes extending in the stacking direction of the battery cells 3. The cooling pipes of the bus bar cooler 10 are provided in accordance with the positions where the electrode terminals of each battery cell 3 are arranged and the positions where the bus bar is arranged. In the battery module 2 in which a plurality of battery cells 3 are stacked, each battery cell 3 is arranged such that the electrode terminal faces upward, and those electrode terminals are arranged side by side in the stacking direction. The cooling pipes of the bus bar cooler 10 extend in the stacking direction of the battery cells 3. The inside of the cooling pipes of the bus bar cooler 10 is a flow path through which the coolant flows.

[0012] As shown in FIG. 2, the bus bar cooler 10 is configured to receive heat from the electrode terminals of the battery cell 3. The battery cell 3 is a rectangular cell in which a case 5 for housing the electrode 4 is formed in a rectangular shape. A positive electrode terminal 6 and a negative electrode terminal 7 are provided on the upper surface 5a of the case 5. The positive electrode terminal 6 is electrically connected to the electrode 4 via a positive electrode tab 8. The negative electrode terminal 7 is electrically connected to the electrode 4 via a negative electrode tab 9. The bus bar cooler 10 receives heat from the positive electrode terminal 6, the negative electrode terminal 7, and the bus bar, and cools the battery cell 3 from the upper surface 5a side. A bottom surface cooler 20 is provided on the bottom surface 5b side of the case 5.

[0013] The bottom surface cooler 20 is a cooler that cools the battery cell 3 from the bottom surface 5b side of the battery cell 3. The bottom surface cooler 20 is provided below the battery module 2 and extends in the stacking direction of the battery cells 3 in accordance with the width of the battery cell 3. The inside of the bottom surface cooler 20 is a flow path through which a coolant flows in the stacking direction. As shown in FIG. 2, the bottom surface cooler 20 is connected to the bottom surface 5b of the battery cell 3 via a heat transfer member 40 so as to be heat transferable. The bottom surface cooler 20 receives heat from the bottom surface 5b of the case 5 of the battery cell 3 and cools the battery cell 3 from the bottom surface 5b side.

[0014] The distribution pipe 30 is a pipe that diverts the coolant to the bus bar cooler 10 and the bottom surface cooler 20. The distribution pipe 30 includes an upstream pipe 31, a first supply pipe 32 that supplies the coolant to the bus bar cooler 10, and a second supply pipe 33 that supplies the coolant to the bottom surface cooler 20. The distribution pipe 30 is formed in a structure in which the first supply pipe 32 and the second supply pipe 33 branch off from the upstream pipe 31.

[0015] The upstream pipe 31 forms a flow path through which the coolant for cooling the battery module 2 flows. The coolant that has flowed through the upstream pipe 31 is diverted to the first supply pipe 32 and the second supply pipe 33.

[0016] The first supply pipe 32 is a first branch pipe that branches off on the downstream side of the upstream pipe 31 and is connected to the inlet of the bus bar cooler 10. The first supply pipe 32 communicates the upstream pipe 31 and the bus bar cooler 10. The inside of the first supply pipe 32 forms a supply flow path through which the coolant supplied to the bus bar cooler 10 flows.

[0017] The second supply pipe 33 is a second branch pipe branched on the downstream side of the upstream pipe 31 and is connected to the inlet of the bottom cooler 20. The second supply pipe 33 communicates the upstream pipe 31 and the bottom cooler 20. The inside of the second supply pipe 33 forms a supply flow path through which the coolant supplied to the bottom cooler 20 flows.

[0018] The battery cooling device 1 configured as described above is applied to a battery pack mounted on an electric vehicle. In a battery pack for an electric vehicle, during high-load driving, due to the heat generation of the battery cells 3 and the heat generation of the bus bar connecting between the terminals of the battery cells 3, the root of the current collecting tab of the electrode 4 becomes locally high in temperature. During high load, the root P2 of the positive tab 8 and the root P3 of the negative tab 9 become in a high-temperature state, and the portion P1 of the electrode 4 becomes the highest temperature point. When the battery cell 3 is in a high-temperature state, there is a concern that its life will be shortened, and there is a possibility that high-load driving cannot be performed controllably. Therefore, during high load, it is necessary to cool the bus bar by the bus bar cooler 10 to suppress the generation of local high temperature in the battery cell 3. From low load to medium load, since it is necessary to sufficiently cool the entire battery cell 3, the bottom cooler 20 is provided on the bottom surface 5b side of the battery cell 3. However, if the bus bar is cooled by the bus bar cooler 10 also during low to medium load driving, the flow rate of the coolant supplied to the bottom cooler 20 will decrease due to the supply of the coolant to the bus bar cooler 10, and the effect of cooling the entire battery cell 3 will be reduced. Therefore, in the battery cooling device 1, a flow rate adjustment valve 50 that opens and closes according to the load is provided inside the first supply pipe 32 so that the bus bar is cooled only by the bus bar cooler 10 during high load.

[0019] As shown in FIG. 3, the flow rate adjustment valve 50 is provided inside the first supply pipe 32 and is a valve that varies the flow path cross-sectional area of the supply flow path of the first supply pipe 32. The flow rate adjustment valve 50 has a rotary structure that is opened by being pushed downstream by the coolant flowing from the upstream pipe 31 into the first supply pipe 32 within the flow path of the first supply pipe 32.

[0020] The flow rate adjustment valve 50 opens and closes according to the flow rate of the coolant flowing through the upstream pipe 31, and opens as the flow rate of the coolant flowing through the upstream pipe 31 increases. That is, the flow rate adjustment valve 50 functions as a pressure loss adjustment mechanism that operates by the pressure difference of the coolant in the distribution pipe 30, and opens and closes according to the load. As the load increases, the temperature of the coolant rises. As shown in FIG. 4, as the temperature of the coolant rises, the viscosity of the coolant decreases. As the viscosity of the coolant decreases, the flow velocity of the coolant increases, and the total flow rate of the coolant increases. In the battery cooling device 1, as the total flow rate of the coolant increases, the flow rate adjustment valve 50 is opened to send the coolant from the distribution pipe 30 to the bus bar cooler 10. That is, the flow rate adjustment valve 50 is configured to open as the flow rate of the upstream pipe 31 increases.

[0021] As shown in FIG. 5(a), when the total flow rate of the coolant is low, the flow rate adjustment valve 50 does not open, and no coolant flows through the bus bar cooler 10. As shown in FIG. 4, in the case of low to medium load, since the total flow rate of the coolant is low, the flow rate adjustment valve 50 closes. In this case, all of the coolant flowing through the upstream pipe 31 flows into the second supply pipe 33 and is supplied to the bottom cooler 20. Therefore, it is possible to suppress the supply of coolant to the bus bar cooler 10 during low to medium load, and the entire battery cell 3 can be cooled by the bottom cooler 20. Thereby, the battery cell 3 can be cooled by efficiently using the coolant.

[0022] As shown in FIG. 5(b), when the total flow rate of the coolant increases from the state shown in FIG. 5(a), the coolant pushes up the flow rate adjustment valve 50 to the downstream side, so the flow rate adjustment valve 50 opens. The state shown in FIG. 5(b) is a state in which a part of the first supply flow path is opened. Therefore, a part of the coolant flowing through the upstream pipe 31 is supplied to the bus bar cooler 10. In this case, the battery cell 3 is cooled mainly by the bottom cooler 20.

[0023] As shown in Fig. 5(c), when the total flow rate of the coolant further increases from the state shown in Fig. 5(b), the flow rate adjustment valve 50 fully opens. As shown in Fig. 4, when the load is high, the total flow rate of the coolant increases, and due to this increase in flow rate, the flow rate adjustment valve 50 opens, and the first supply flow rate, which is the flow rate of the coolant supplied to the bus bar cooler 10, increases. When the load becomes high and the flow rate adjustment valve 50 is in a fully open state, the first supply flow rate increases in response to the increase in the total flow rate of the coolant, and the second supply flow rate, which is the flow rate of the coolant supplied to the bottom surface cooler 20, becomes almost constant. Note that in the low-load to medium-load region where the flow rate adjustment valve 50 is closed, the second supply flow rate is the same as the total flow rate of the coolant.

[0024] When the flow rate adjustment valve 50 is open at high load, cooling performance corresponding to the first supply flow rate and the second supply flow rate can be exhibited using both the bus bar cooler 10 and the bottom surface cooler 20. As shown in Fig. 2, when the portion P1 of the electrode 4 is the highest temperature point, the heat of the portion P1 conducts upward through the electrode 4 and is transmitted to the bus bar cooler 10 from the positive electrode terminal 6 side via the base P2 of the positive electrode tab 8, and the heat of the portion P1 conducts upward through the electrode 4 and is transmitted to the bus bar cooler 10 from the negative electrode terminal 7 side via the base P3 of the negative electrode tab 9. In addition, the heat of the portion P1 conducts downward through the electrode 4 and is transmitted to the bottom surface cooler 20 via the bottom surface 5b. Thereby, at high load, local high temperature of the electrode 4 can be suppressed by cooling from the bus bar.

[0025] As described above, according to the embodiment, the diversion of the coolant can be switched according to the load by the distribution pipe 30 provided with the flow rate adjustment valve 50. Since the coolant is supplied from the distribution pipe 30 to the bus bar cooler 10 only at high load, at high load, the local high temperature of the electrode 4 can be suppressed by cooling the bus bar and the electrode terminals of the battery cell 3 by the bus bar cooler 10. In the low to medium load region where bus bar cooling is not required, although the coolant is supplied from the distribution pipe 30 to the bottom surface cooler 20, the supply flow rate from the distribution pipe 30 to the bus bar cooler 10 can be restricted, so that a decrease in the cooling efficiency of the entire battery cell 3 can be suppressed.

[0026] Note that the valve provided inside the first supply pipe 32 is not limited to a rotary structure such as the flow rate adjustment valve 50. For example, as shown in FIGS. 6(a) to 6(c), a lip seal type valve 60 may be provided inside the first supply pipe 32. As shown in FIG. 6(a), when the total flow rate of the coolant is small, the valve 60 is closed, and the bottom surface cooler 20 can cool the battery cell 3. As shown in FIG. 6(b), when the total flow rate of the coolant is medium, the valve 60 opens, and the battery cell 3 can be cooled with the bottom surface cooler 20 as the center. As shown in FIG. 6(c), when the total amount of the coolant is large, the valve 60 is fully opened, and the bus bar cooler 10 can cool the bus bar and the electrode terminals of the battery cell 3.

Explanation of Reference Numerals

[0027] 1 Battery cooling device 2 Battery module 10 Bus bar cooler (first cooler) 20 Bottom surface cooler (second cooler) 30 Distribution pipe 31 Upstream pipe 32 First supply pipe 33 Second supply pipe 50 Flow rate adjustment valve

Claims

1. A battery cooling device for cooling a battery module composed of a plurality of battery cells with a coolant, a first cooler for cooling an electrode terminal of the battery cell and a bus bar connected to the electrode terminal with the coolant, a second cooler for cooling the battery cell with the coolant from the bottom side of the battery cell, a distribution pipe for diverting and supplying the coolant to the first cooler and the second cooler, comprising: the distribution pipe, an upstream pipe into which the coolant flows, a first supply pipe branched from the upstream pipe and communicating the upstream pipe with the first cooler, and a second supply pipe branched from the upstream pipe and communicating the upstream pipe with the second cooler, a flow rate adjustment valve for adjusting the flow rate of the coolant supplied to the first cooler is provided inside the first supply pipe, the flow rate adjustment valve opens and closes according to the flow rate of the coolant flowing through the upstream pipe, and opens as the flow rate of the coolant flowing through the upstream pipe increases A battery cooling device characterized by the above.

2. The flow rate adjustment valve is an on-off valve that opens by operating so as to be pushed downstream in the flow path of the first supply pipe as the flow rate of the coolant flowing through the upstream pipe increases A battery cooling device according to claim 1, characterized by the above.

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