Battery cooling structure

Abstract

The objective is to obtain a battery cooling structure that can suppress the occurrence of temperature differences between the battery cells constituting the battery module during the cooling of the battery module. [Solution] In the battery pack 10, the cooling circuit section 36 extends from the front to the rear of the vehicle and includes an upstream flow path section 36A that allows refrigerant from the cooler 40 side to flow along the front-to-rear direction of the vehicle, and a downstream flow path section 36B that branches off from the upstream flow path section 36A and extends in the front-to-rear direction of the vehicle, allowing refrigerant to flow towards the cooler 40 side along the front-to-rear direction of the vehicle.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 listed below discloses an invention relating to a battery pack. In this battery pack, a cooler is arranged along the bottom portion of a battery case that supports battery cells, and the cooler cools the bottom portion of the battery case, thereby cooling the battery module stored in the battery case.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] Incidentally, in the above prior art, the cooler is provided with a flow path, and the battery module is cooled by the refrigerant flowing through this flow path. However, depending on the configuration of the flow path, it may be difficult to cool the battery module uniformly, and a temperature difference may occur between the battery cells constituting the battery module.

[0005] In view of the above facts, an object of the present disclosure is to obtain a battery cooling structure capable of suppressing the occurrence of a temperature difference between the battery cells constituting the battery module when the battery module is cooled.

Means for Solving the Problem

[0006] A battery cooling structure according to the first embodiment comprises a battery case for housing a battery module in which a plurality of battery cells are arranged, and a cooling circuit section arranged along the bottom of the battery case and capable of cooling the battery module, wherein the cooling circuit section comprises an upstream flow path section that extends in the direction of the arrangement of the battery cells and allows refrigerant from the cooler side to flow along the arrangement direction to cool the refrigerant flowing through the cooling circuit section, and a downstream flow path section that branches off from the upstream flow path section in a plurality of directions and extends in the direction of the arrangement and allows the refrigerant to flow towards the cooler side along the arrangement direction.

[0007] According to the battery cooling structure of the first embodiment, a battery module in which a plurality of battery cells are arranged is housed in a battery case, and a cooling circuit is arranged along the bottom of this battery case. Therefore, in this embodiment, the battery module can be cooled by flowing a coolant through the cooling circuit.

[0008] Incidentally, depending on the configuration of the cooling circuit, it may be difficult to cool the battery module evenly, potentially leading to temperature differences between the battery cells that make up the module.

[0009] In this embodiment, the cooling circuit extends in the direction of the arrangement of the battery cells (hereinafter referred to as the arrangement direction) and includes an upstream flow path that flows refrigerant from the cooler side along the arrangement direction to cool the refrigerant, and a downstream flow path that branches off from the upstream flow path and extends in the direction of the arrangement, and flows refrigerant towards the cooler side along the arrangement direction.

[0010] Therefore, in this embodiment, compared to a configuration in which the refrigerant is circulated back and forth through one forward and one return channel, the speed at which the refrigerant cooled by the cooler disperses in the direction of arrangement can be increased, thereby increasing the likelihood that the battery cells constituting the battery module are cooled uniformly.

[0011] The battery cooling structure according to the second embodiment is the battery cooling structure according to the first embodiment, wherein the downstream flow channel is arranged one on one side and one on the other side in an orthogonal direction perpendicular to the arrangement direction with respect to the upstream flow channel.

[0012] According to the battery cooling structure of the second embodiment, one downstream flow channel is arranged on one side and one on the other side in a direction perpendicular to the arrangement direction relative to the upstream flow channel. Therefore, in this embodiment, the flow velocity of the refrigerant flowing through the pair of downstream flow channels can be made to be approximately the same.

[0013] The third embodiment of the battery cooling structure is configured such that, in the first or second embodiment of the battery cooling structure, the upstream flow channel and the downstream flow channel are joined together by press-formed steel plates, and the shape of the pair of downstream flow channels is symmetrical with respect to the upstream flow channel.

[0014] According to the third embodiment of the battery cooling structure, the upstream channel section and the downstream channel section are constructed by joining pressed steel plates. The shape of the pair of downstream channel sections is symmetrical with respect to the upstream channel section.

[0015] Therefore, in this embodiment, the shape of the press mold used to form the downstream flow channel can be standardized, and the likelihood of the refrigerant flowing from the upstream flow channel being evenly distributed between one downstream flow channel and the other can be increased.

[0016] The fourth embodiment of the battery cooling structure further comprises a distribution channel that is continuous with the plurality of upstream channel sections and extends in an orthogonal direction perpendicular to the arrangement direction, in addition to the battery cooling structure according to any one of the first to third embodiments.

[0017] According to the fourth embodiment of the battery cooling structure, the cooling circuit section is equipped with a plurality of upstream flow channels, which are continuous with a distribution flow channel that extends in an orthogonal direction (hereinafter referred to as the orthogonal direction) perpendicular to the arrangement direction. Therefore, in this embodiment, a single distribution flow channel can distribute the refrigerant to a plurality of upstream flow channels.

[0018] The fifth embodiment of the battery cooling structure is such that, in the fourth embodiment of the battery cooling structure, the refrigerant from the cooler side can be supplied to the orthogonal central portion of the distribution channel.

[0019] According to the battery cooling structure according to the fifth aspect, since the refrigerant from the cooler side is supplied to the central portion in the orthogonal direction of the distribution flow passage portion, it is possible to increase the certainty that the refrigerant cooled by the cooler is evenly distributed to the plurality of upstream flow passage portions via the distribution flow passage portion.

[0020] The battery cooling structure according to the sixth aspect is the battery cooling structure according to any one of the first aspect to the fifth aspect, wherein the flow passage cross-sectional area of the upstream flow passage portion and the flow passage cross-sectional area of the downstream flow passage portion are set to the same area.

[0021] According to the battery cooling structure according to the sixth aspect, the flow passage cross-sectional area of the upstream flow passage portion and the flow passage cross-sectional area of each of the downstream flow passage portions that branch into a plurality from the upstream flow passage portion are set to the same area. For this reason, in the cooling circuit portion, the cross-sectional area on the downstream side through which the refrigerant that has absorbed heat from the battery module flows is larger than the cross-sectional area on the upstream side through which the refrigerant cooled by the cooler flows. As a result, in this aspect, the flow velocity of the refrigerant from the cooler side flowing upstream of the cooling circuit portion is increased to suppress the refrigerant from absorbing heat from sources other than the battery module, while the flow velocity of this refrigerant flowing downstream of the cooling circuit can be reduced to extend the time during which the refrigerant absorbs heat from the battery module. [Effects of the Invention]

[0022] As described above, the battery cooling structure according to the present disclosure has an excellent effect that it is possible to suppress the occurrence of a temperature difference between the battery cells constituting the battery module when the battery module is cooled. [Brief Description of the Drawings]

[0023] [Figure 1] It is a plan view schematically showing the configuration of a battery to which the battery cooling structure according to the present embodiment is applied. [Figure 2] It is a cross-sectional view schematically showing the configuration of a battery to which the battery cooling structure according to the present embodiment is applied. [Figure 3]This is a plan view schematically showing the configuration of a cooling flow path portion in a battery to which the battery cooling structure according to the present embodiment is applied. [Mode for Carrying Out the Invention]

[0024] Hereinafter, an example of the battery cooling structure according to the present disclosure will be described using FIG. 1 to FIG. 3. The battery pack 10 to which the battery cooling structure according to the present embodiment is applied can be mounted on vehicles such as hybrid cars, plug-in hybrid cars, and electric vehicles.

[0025] First, a schematic configuration of the vehicle 12 on which the battery pack 10 is mounted will be described. Note that the arrow FR appropriately shown in each drawing indicates the vehicle front side, the arrow UP indicates the vehicle upper side, and the arrow LH indicates the vehicle width direction left side.

[0026] As shown in FIG. 1, the vehicle body 14 of the vehicle 12 includes a front part (not shown) made of aluminum die-cast that constitutes the vehicle front portion, a center part 16 that constitutes the vehicle front-rear direction central portion and is provided with a center frame (not shown) that holds the battery pack 10 and is frame-shaped in plan view, and a rear part (not shown) made of aluminum die-cast that constitutes the vehicle rear portion. A power unit (not shown) including a motor and the like is mounted on the front part, and the power unit is driven by electric power supplied from the battery pack 10, whereby the vehicle travels.

[0027] The battery pack 10 is configured to include a battery case 18 that forms its outer shell, and a plurality of battery modules 20 housed in the battery case 18.

[0028] The main part of the battery case 18 is made of an aluminum alloy, and as also shown in FIG. 2, the battery case 18 includes an upper case 22 that constitutes the vehicle upper portion, and a lower case 24 that constitutes the vehicle lower portion.

[0029] Furthermore, inside the battery case 18, multiple battery modules 20 are arranged on the upper side of the bottom wall portion 24A, which serves as the bottom of the case lower 24, with the vehicle's longitudinal direction oriented in the vehicle's front-rear direction and at predetermined intervals from each other in the vehicle's width direction.

[0030] The battery module 20 is composed of a plurality of battery cells 26. Each battery cell 26 is composed of a cell case portion 28 that forms its outer shell and has a flattened rectangular parallelepiped shape, and an electrode body (not shown) that is arranged inside the cell case portion 28.

[0031] Furthermore, when viewed from the vehicle height direction, a smoke exhaust section (not shown) is provided in the center of the lower wall section 28A that constitutes the lower part of the cell case section 28 of the vehicle. This smoke exhaust section is a valve that opens when the internal pressure of the battery cell 26 exceeds a certain level, releasing the smoke-containing gas accumulated inside the battery cell 26 to the outside.

[0032] The battery cells 26 configured as described above are arranged in a series in the vehicle's longitudinal direction, with their thickness direction being the vehicle's longitudinal direction. In other words, in this embodiment, the arrangement direction of the battery cells 26 coincides with the longitudinal direction of the battery module 20.

[0033] On the other hand, the bottom wall portion 24A of the case lower 24 is convex toward the upper side of the vehicle and extends in the longitudinal direction of the vehicle, and is composed of a bulging portion 30 used to support the battery cell 26, a smoke exhaust passage portion 32, and an installation wall portion 34.

[0034] More specifically, the bulging portions 30 are arranged in pairs on each side of the underside of the vehicle in the width direction of the battery cell 26. These bulging portions 30 constitute the upper side of the vehicle and include a support wall portion 30A that supports the battery cell 26 from the underside of the vehicle, with its thickness direction being in the vehicle height direction. The cross-sectional shape, as viewed from the front-rear direction of the vehicle, is U-shaped, opening to the underside of the vehicle and widening from the upper side to the lower side of the vehicle.

[0035] Furthermore, a thermal conductive sheet 33 is interposed between the upper surface of the support wall 30A and the battery cell 26, and a portion of the cooling circuit 36 ​​is positioned on the lower surface of a portion of the support wall 30A, i.e., the bottom wall 24A, as will be described later.

[0036] The exhaust gas passage section 32 has a thickness direction in the direction of the vehicle height and includes a bottom section 32A that connects the pair of bulging sections 30, as well as a part of the bulging sections 30. When viewed from the front-rear direction of the vehicle, the cross-sectional shape is U-shaped, opening to the upper side of the vehicle and widening from the lower side to the upper side of the vehicle.

[0037] This exhaust gas passage section 32 extends in the longitudinal direction of the vehicle and is positioned to overlap with the exhaust gas section of the battery cell 26 when viewed from the vehicle height direction, i.e., the height direction of the battery cell 26, allowing gas (exhaust gas) from this exhaust gas section to flow into it.

[0038] Furthermore, a through-hole (not shown) is formed in the bottom portion 32A, and this through-hole is sealed with a molten sheet (not shown) that melts at a predetermined temperature. In other words, in this embodiment, when the gas discharged from the battery cell 26 is above a predetermined temperature, this molten sheet melts, and this gas is discharged to the outside of the battery case 18.

[0039] The mounting wall portion 34 connects adjacent bulging portions 30 in the vehicle width direction between adjacent battery modules 20 in the vehicle width direction, and extends in the vehicle front-rear direction with its thickness direction being the vehicle height direction. A front-rear member portion 38 is provided on the upper surface of the mounting wall portion 34.

[0040] The front-rear member portion 38 has a hat-like cross-sectional shape when viewed from the front-rear direction of the vehicle, with the underside of the vehicle open, and its pair of flange portions 38A are joined to the installation wall portion 34 by a joint (not shown) such as welding.

[0041] Furthermore, cell holding portions (not shown) are provided on one side and the other side in the vehicle width direction of the front-rear member portion 38, with a cross-section that is L-shaped when viewed from the front-rear direction of the vehicle, and the battery cells 26 are held in these cell holding portions.

[0042] On the other hand, as shown in Figures 1 and 3, the cooling circuit section 36 is configured to include multiple sets of upstream flow path sections 36A and a pair of downstream flow path sections 36B, as well as a distribution flow path section 36C that supplies refrigerant cooled by the cooler 40 to these sets.

[0043] More specifically, the upstream channel section 36A extends in the longitudinal direction of the vehicle and is positioned relative to the center of the support wall section 30A of the bulging section 30 in the vehicle width direction, and branches into a pair of downstream channel sections 36B on the rear side of the vehicle.

[0044] On the other hand, the downstream channel section 36B extends in the longitudinal direction of the vehicle and is positioned on one side and the other side of the upstream channel section 36A in the vehicle width direction. Furthermore, as shown in Figure 2, in the pair of downstream channel sections 36B, the cross-sectional shape of one downstream channel section 36B and the cross-sectional shape of the other downstream channel section 36B are symmetrical with respect to the upstream channel section 36A when viewed from the longitudinal direction of the vehicle. In addition, the cross-sectional area of ​​the channel in the upstream channel section 36A and the cross-sectional area of ​​the channel in the downstream channel section 36B are set to be the same area.

[0045] Furthermore, the refrigerant that flows through the downstream channel section 36B is directed to the cooler 40 side via a collection channel section and a refrigerant tank (not shown).

[0046] As shown in Figure 1, the distribution channel section 36C extends in the vehicle width direction, and multiple (for example, four) upstream channel sections 36A are connected at equal intervals in the vehicle width direction. In addition, a supply port section 36C1 is provided in the center of the distribution channel section 36 in the vehicle width direction to which refrigerant cooled by the cooler 40 is supplied.

[0047] Furthermore, as shown in Figure 2, the cooling circuit section 36 is constructed by joining an upper plate 42, which is made of pressed steel plate and constitutes the upper vehicle portion of the upstream flow section 36A and the downstream flow section 36B, and a lower plate 44, which is made of pressed steel plate and constitutes the lower vehicle portion of the upstream flow section 36A and the downstream flow section 36B, in a watertight manner by a joint (not shown) made by welding or the like.

[0048] The cooling circuit section 36, configured as described above, is capable of cooling the battery cells 26 by exchanging heat between the refrigerant flowing through the upstream channel section 36A and the downstream channel section 36B and the battery cells 26.

[0049] Furthermore, a thermal conductive sheet 46 is interposed between the lower surface of the support wall 30A and the upper surface of the cooling circuit 36.

[0050] (Operation and effects of this embodiment) Next, the operation and effects of this embodiment will be described.

[0051] In this embodiment, as shown in Figure 1, a battery module 20 in which a plurality of battery cells 26 are arranged is housed in a battery case 18, and a cooling circuit 36 ​​is arranged along the bottom wall 24A of the battery case 18. Therefore, in this embodiment, the battery module 20 can be cooled by flowing a coolant through the cooling circuit 36.

[0052] However, depending on the configuration of the cooling circuit section 36, it may become difficult to cool the battery module 20 evenly, potentially causing temperature differences among the battery cells 26 that make up the battery module 20.

[0053] In this embodiment, as also shown in Figure 3, the cooling circuit section 36 extends from the front to the rear of the vehicle and includes an upstream flow path section 36A that allows refrigerant from the cooler 40 side to flow along the front-to-rear direction of the vehicle, and a downstream flow path section 36B that branches off from the upstream flow path section 36A and extends in the front-to-rear direction of the vehicle, allowing refrigerant to flow towards the cooler 40 side along the front-to-rear direction of the vehicle.

[0054] Therefore, in this embodiment, compared to a configuration in which the refrigerant is circulated back and forth through one flow path each for the forward and return paths, the speed at which the refrigerant cooled by the cooler 40 is dispersed in the longitudinal direction of the vehicle can be increased, thereby increasing the likelihood that the battery cells 26 constituting the battery module 20 are cooled uniformly.

[0055] Furthermore, in this embodiment, one downstream flow channel 36B is arranged on one side and one on the other side in the vehicle width direction relative to the upstream flow channel 36A. Therefore, in this embodiment, the flow velocity of the refrigerant flowing through the pair of downstream flow channels 36B can be made to be approximately the same.

[0056] Furthermore, in this embodiment, as shown in Figure 2, the upstream channel section 36A and the downstream channel section 36B are constructed by joining press-formed steel plates. The shape of the pair of downstream channel sections 36B is symmetrical with respect to the upstream channel section 36A.

[0057] Therefore, in this embodiment, the shape of the press mold used to form the downstream flow channel 36B can be standardized, and the likelihood of the refrigerant flowing from the upstream flow channel 36A being evenly distributed between one downstream flow channel 36B and the other downstream flow channel 36B can be increased.

[0058] Returning to Figure 1, in this embodiment, the cooling circuit section 36 is equipped with multiple upstream flow channels 36A, which are continuous with a distribution flow channel section 36C that extends in the vehicle width direction. Therefore, in this embodiment, a single distribution flow channel section 36C can distribute refrigerant to multiple upstream flow channels 36A.

[0059] Furthermore, in this embodiment, since the cooler 40 is supplied to the center of the distribution channel section 36C in the vehicle width direction, the likelihood that the cooler 40 cooled by the cooler 40 will be evenly distributed to the multiple upstream channel sections 36A via the distribution channel section 36C can be increased.

[0060] In addition, in this embodiment, as shown in Figure 2, the cross-sectional area of ​​the upstream flow path section 36A and the cross-sectional area of ​​each of the downstream flow path sections 36B that branch off from the upstream flow path section 36A are set to be the same area. Therefore, in the cooling circuit section 36, the cross-sectional area of ​​the downstream side through which the refrigerant that has absorbed heat from the battery module 20 flows is larger than the cross-sectional area of ​​the upstream side through which the refrigerant cooled by the cooler 40 flows.

[0061] As a result, in this embodiment, the flow velocity of the refrigerant from the cooler 40 upstream of the cooling circuit 36 ​​is increased, suppressing the refrigerant from absorbing heat from sources other than the battery module 20, while the flow velocity of the refrigerant downstream of the cooling circuit 36 ​​is decreased, allowing the time for the refrigerant to absorb heat from the battery module 20 to be extended.

[0062] As described above, in this embodiment, it is possible to suppress the occurrence of temperature differences among the battery cells 26 that make up the battery module 20 when the battery module 20 is cooled.

[0063] <Supplementary explanation of the above embodiment> In the embodiment described above, the arrangement direction of the battery cells 26 was set to the vehicle's longitudinal direction. However, depending on the specifications of the battery pack 10, the arrangement direction of the battery cells 26 may be set to a direction other than the vehicle's longitudinal direction, such as the vehicle's width direction. [Explanation of Symbols]

[0064] 18 Battery Case 20 Battery Modules 24A Bottom wall (bottom) 26 battery cells 36 Cooling circuit section 36A Upstream channel section 36B Downstream channel section 36C Distribution channel section 40 Cooler

Claims

1. A battery case that houses a battery module in which multiple battery cells are arranged, A cooling circuit section is provided, which is positioned along the bottom of the battery case and capable of cooling the battery module. Equipped with, The aforementioned cooling circuit section is An upstream flow path extends in the direction of the arrangement of the battery cells and allows the refrigerant flowing through the cooling circuit to flow from the cooler side along the direction of the arrangement, A downstream flow path branching off from the upstream flow path and extending in the direction of the arrangement, which flows the refrigerant toward the cooler along the direction of the arrangement, A battery cooling structure equipped with this feature.

2. The downstream channel section is arranged with one channel on one side and one on the other side in a direction perpendicular to the arrangement direction relative to the upstream channel section. The battery cooling structure according to claim 1.

3. The upstream channel section and the downstream channel section are constructed by joining press-formed steel plates, and the shape of the pair of downstream channel sections is symmetrical with respect to the upstream channel section. The battery cooling structure according to claim 2.

4. The system further comprises a distribution channel section that is continuous with the multiple upstream channel sections and extends in an orthogonal direction perpendicular to the arrangement direction, The battery cooling structure according to claim 1.

5. The refrigerant from the cooler side can be supplied to the central part of the distribution channel in the orthogonal direction. The battery cooling structure is also described in claim 4.

6. The cross-sectional area of ​​the upstream channel and the cross-sectional area of ​​the downstream channel are set to be the same area. The battery cooling structure according to claim 1.

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