Battery pack

Abstract

To provide a battery pack that can improve the rigidity of the lid. [Solution] The battery pack 1 comprises a case body 10 on which a cell stack 40 is placed, and a lid 20 that covers the cell stack 40 and the cooling duct 30 and is fixed to the case body 10. The cooling duct 30 has a pair of legs 31 that support the lid 20 at both ends of the cooling duct 30, a part of the back surface of the lid 20 covers the opening 32b of the cooling duct 30, and the pair of legs 31 are fixed to the case body 10.

Description

Technical Field

[0001] The present invention relates to a battery pack that accommodates a cell stack. Background Art

[0002] There is known a battery pack case that accommodates a battery module, which consists of an upper case formed with a pair of refrigerant inlets and a lower case formed with a refrigerant outlet (see, for example, Patent Document 1). Prior Art Literature Patent Literature

[0003] Patent Document 1 Japanese Unexamined Patent Publication No. 2017-531286 Summary of the Invention Problem to be Solved by the Invention

[0004] In the above-mentioned battery pack case, the rigidity of the case is reduced by the refrigerant inlet formed in the upper case, so a large number of beads are formed to increase the case rigidity, but there is a problem that the plate thickness of the upper case serving as a lid increases by an amount corresponding to the beads.

[0005] A problem to be solved by the present invention is to provide a battery case capable of improving the rigidity of a lid portion while suppressing the thickness of the lid portion. Means for Solving the Problem

[0006] According to the present invention, the above problem is solved by providing a pair of leg portions that support the lid portion at both ends of a cooling duct, covering the opening of the cooling duct with a part of the back surface of the lid portion, and fixing the pair of leg portions to the case main body portion. Effect of the Invention

[0007] According to the present invention, the rigidity of the lid portion can be improved. Brief Description of the Drawings

[0008] [Figure 1] Figure 1 is a perspective view showing a battery pack in an embodiment of the present invention. [Figure 2] Figure 2 is a perspective view of the lid shown in Figure 1. [Figure 3] Figure 3 is a perspective view of the cooling duct shown in Figure 1. [Figure 4] Figure 4 is a perspective view of the cell stack shown in Figure 1. [Figure 5] Figure 5 is a perspective view of the case body shown in Figure 1. [Figure 6] Figure 6 is an exploded perspective view showing a battery pack in an embodiment of the present invention. [Figure 7] Figure 7 is a cross-sectional view of the battery pack cut along the line VII-VII in Figure 1. [Figure 8] Figure 8 is a cross-sectional view of the battery pack cut along the line VIII-VIII in Figure 1. [Figure 9] Figure 9 is a cross-sectional view of a battery pack used as a reference example. [Figure 10] Figure 10 is a cross-sectional view of a reference example battery pack. [Modes for carrying out the invention]

[0009] The embodiment will now be described based on the drawings. Figure 1 is an exploded perspective view of the battery pack 1 in this embodiment, showing it in an open state with the lid 20 not closed. Figures 2 to 5 are perspective views of the components that make up the battery pack; Figure 2 is a perspective view of the lid, Figure 3 is a perspective view of the cooling duct, Figure 4 is a perspective view of the cell stack, and Figure 5 is a perspective view of the case body. Figure 6 is an exploded perspective view of the battery pack 1.

[0010] In this embodiment, the battery pack 1 is mounted on a vehicle and houses a cell stack 40, which supplies high-voltage electricity to a motor (not shown), etc., within its case. The battery pack 1 comprises a case body 10, a lid 20, a cooling duct 30, and a cell stack 40. The case body 10 and the lid 20 form a battery case that houses the cell stack 40, with the case body 10 being the lower case (LWR case) and the lid 20 being the upper case (UPR case). The battery pack 1 is not limited to the case body 10, etc., and may also include external terminals, a harness for electrically connecting the external terminals to the cell stack 40, a junction box, a battery management system (BMS), etc., and these components may be arranged inside the case body 10.

[0011] The case body 10 is a box-shaped member that opens upwards. The lid 20 fits into the opening of the case body 10. The case body 10 has a bottom 11, four side parts 12, and a flange 13. Both the bottom 11 and the side parts 12 are made of metal plates or the like and are integrally formed with each other. The four side parts 12 are erected on the upper surface of the bottom 11. The bottom 11 is formed in a rectangular shape when viewed from the z direction. The flange 13 is a member that extends from the outer edge of the side parts 12 along the x and y planes and serves as a joint for fixing the lid 20. Screw holes 13a are provided in the flange 13 so as to match the positions of the screw holes 21a around the lid 20. Multiple cell stacks 40 are placed on the bottom 11 of the case body 10.

[0012] The lid portion 20 covers the cooling duct 30 and the cell stack 40 and is fixed to the case body portion 10. The lid portion 20 is not particularly limited, but is made of a single metal plate or the like. The lid portion 20a is formed in a rectangular shape when viewed from the z direction. In the example in Figure 2, the longitudinal direction of the lid portion 20 is the x direction, and the short direction is the y direction. Protrusions 21 are provided around the lid portion 20 that protrude along the plane (xy plane) of the lid portion 20, and screw holes 21a are provided in the protrusions 21 to match the positions of the screw holes 10a of the case body portion 10. A ventilation opening 22 is also formed in the lid portion 20. The ventilation opening 22 is formed on the center line along the plane (xy plane) of the lid portion 20. The dotted line P in Figure 2 corresponds to the center line along the plane of the lid portion 20. The center line is a line that passes through the center point of the lid portion 20 along the short direction of the lid portion 20. The vent 22 is located in the center of the longitudinal side of the lid 20. The shape of the vent 22 is not particularly limited, but it is formed in a rectangular shape. The vent is positioned so that the central part of the connecting portion 32 of the cooling duct 30 can be seen from the vent 22. The vent 22 serves as the outlet for the cooling passage.

[0013] The cooling duct 30 has a cooling passage for releasing heat generated in the cell stack 40 to the outside of the battery case, and a support structure for supporting the lid 20. The cooling duct 30 includes a pair of legs 31 that support the lid 20 at both ends of the cooling duct 30, a connecting part 32 that connects the pair of legs 31, a sealing member 33, and a support part 34 that supports the connecting part 32. The pair of legs 31 serve as legs that support the cooling duct 30 within the case. The pair of legs 31 support the lid 20 via the connecting part 32 and the sealing member 33. The pair of legs 31 also have a structure that extends along the short side of the lid 20.

[0014] The leg portion 31 is formed in the shape of a rectangular parallelepiped, with a pair of opposing faces opening up to form a cylindrical shape. The openings 31a and 31b are opposite to each other and are holes aligned with the yz plane. The cylindrical members other than the openings 31a and 31b are enclosed by four plates. When the cooling duct 30 and the multiple cell stacks 40 are attached to the case body portion 10, the openings 31a and 31b are closed by one face of the cell stack 40. One of the pair of leg portions 31 is sandwiched between two cell stacks 40, and the other leg portion 31 is sandwiched between two cell stacks 40. A column 31c is provided between the upper and lower surfaces of the leg portion 31, aligned with the z axis. The upper surface of the leg portion 31 also has a communication port 31d that communicates with the cooling passage in the connecting portion 32. The communication port 31d is a hole that is opened in part on the upper surface of the leg portion 31 and is aligned with the xy plane. The leg portion 31 also has a cylindrical screw hole 31e aligned with the z-axis. A screw is passed through the screw hole 31e, and the leg portion 31 is fixed to the bottom portion 11 of the case body portion 10 by the screw.

[0015] The connecting portion 32 is a member that connects one leg portion 31 to the other leg portion 31, and has a passage 32a with an open top surface. The top surface of the passage 32a becomes the opening 32b of the cooling duct 30. In other words, of the many surfaces that make up the passage 32a, the top surface is open, and the other surfaces are walls. The passage 32a extends along the x-axis. In other words, the passage 32a is a groove that extends along the x-axis. The opening 32b is provided on the top surface of the cooling duct 30. The central part of the passage 32a is wider than the parts other than the central part. The width of the passage 32a along the y-direction is greater in the central part of the passage 32a. By making the width of the passage 32a greater in the central part, the width (d1) of the central part of the opening 32b is greater than the width (d2) of the parts of the opening 32b other than the central part. Also, the opening area of ​​the central part of the opening 32b is larger than the opening area of ​​the ventilation opening 22 of the lid portion 20. The upper edge of the passage 32a has a sealing member 33. The sealing member 33 is made of resin.

[0016] When the cover portion 20 is attached to the case main body portion 10, the sealing member 33 is sandwiched between the passage 32a and the back surface of the cover portion 20, and a part of the back surface of the cover portion 20 covers the opening 32b of the cooling duct 30. Further, when the cooling duct 30 is attached to the case main body portion 10, the cooling duct 30 is arranged inside the case such that the position of the connecting portion 32 corresponds to the position of the vent 22 of the cover portion 20. Then, the vent 22 of the cover portion 20 and the central portion of the opening 32b are aligned. Therefore, the portion of the back surface of the cover portion 20 other than the vent 22 serves as a lid for the passage 32a, forming the cooling passage of the cooling duct 30. The cooling passage is formed over a part of the cover portion 20 in the longitudinal direction. The vent 22 of the cover portion 20 serves as a discharge outlet of the cooling duct 30. That is, the portion of the cover portion 20 that covers the opening 32b functions as a member that forms a part of the cooling passage of the cooling duct 30.

[0017] The support portion 34 is located at the center of the bottom surface of the case main body portion 10 and supports the connecting portion 32. The support portion 34 is a member that connects the central portion of the connecting portion 32 to the bottom portion 11 of the case main body portion 10. The support portion 34 includes an extending portion 34a extending from the central portion of the connecting portion 32 in the z-axis direction, and an abutting portion 34b having a surface along the surface of the bottom portion 11. The abutting portion 34b may be fixed to the bottom portion 11 of the case main body portion 10.

[0018] The cell stack 40 is a module including a plurality of battery cells stacked on each other. As shown in FIG. 4 or FIG. 6, the cell stack 40 is a laminate in which battery cells are stacked along the y-axis, and four cell stacks 40 are housed in the battery case. The four cell stacks 40 are fixed to the bottom portion 11 of the case main body portion 10.

[0019] FIG. 7 is a cross-sectional view of the battery pack 1 taken along line VII-VII in FIG. 1. FIG. 8 is a cross-sectional view of the battery pack 1 taken along line VIII-VIII in FIG. 1. Although FIG. 1 shows a state where the cover portion 20 is not closed, FIGS. 7 and 8 are cross-sectional views of the battery pack 1 in a state where the cover portion 20 is closed.

[0020] Figure 9 is a cross-sectional view of the reference example battery pack 1 cut at the same cross-section as Figure 7, and Figure 10 is a cross-sectional view of the reference example battery pack 1 cut at the same cross-section as Figure 8. The arrow Q shown in Figures 7 and 9 indicates the airflow, which corresponds to the flow when heat generated in the cell stack 40 is transferred.

[0021] In the battery pack 1 of the reference example, the upper surface of the cooling passage of the connecting portion 32 is not open and does not have an opening 32b. In the reference example, a duct upper portion 91 is provided on the upper surface of the cooling passage of the connecting portion 32. The duct upper portion 91 is the upper wall of the cooling passage of the connecting portion 32. A pipe 92 is also provided connecting the duct upper portion 91 and the vent 22 of the lid portion 20. The pipe 92 is a cylindrical member oriented along the z-axis.

[0022] As shown in Figures 7 and 8, in this embodiment, the height of the cooling passage in the connecting portion 32 (length along the Z-axis) is the distance (H1) between the bottom surface of the passage 32a and the back surface of the cover portion 20. In the reference example, the distance between the bottom surface of the passage 32a and the back surface of the cover portion 20 is H1, which is the same length as in this embodiment. However, in the reference example, a component clearance (H2) is required, which is the sum of the thickness of the duct top surface 91 and the length of the pipe 92. Therefore, the height of the cooling passage in the connecting portion 32 is the length obtained by subtracting the component clearance (H2) from the distance (H1) (H1-H2).

[0023] In other words, in this embodiment, the inter-component clearance (H2) as in the reference example is unnecessary, so the area of ​​the cross-sectional area (yz plane) of the cooling passage of the connecting portion 32 can be increased compared to the reference example. Therefore, in this embodiment, the airflow resistance is reduced and the cooling performance is improved.

[0024] As described above, the battery pack 1 according to this embodiment comprises a case body 10 on which the cell stack 40 is mounted, and a lid 20 that covers the cell stack 40 and the cooling duct 30 and is fixed to the case body 10. The cooling duct 30 has a pair of legs 31 that support the lid 20 at both ends of the cooling duct 30, a part of the back surface of the lid 20 covers the opening 32b of the cooling duct 30, and the pair of legs 31 are fixed to the case body 10. As a result, the lid 20 becomes a part of the cooling passage of the battery pack 1, and the rigidity of the lid 20 can be improved without increasing the thickness of the lid 20.

[0025] In this embodiment, the opening 32b is provided on the top surface of the cooling duct 30, and the portion of the cover 20 that covers the opening 32b becomes a part of the cooling passage of the cooling duct 30. Since a component clearance (H2) to avoid interference between the cooling duct 30 and the cover is not required, the cross-sectional area of ​​the cooling passage can be increased, reducing airflow resistance and improving cooling performance.

[0026] In this embodiment, the cooling duct 30 includes a connecting portion 32 that connects a pair of legs 31 and supports the lid 20. Since the lid 20 is supported by the fixing portion between the pair of legs 31 and the case body 10 via the connecting portion 32, the rigidity of the battery pack 1 can be increased.

[0027] In this embodiment, the lid 20 is provided with a vent 22 formed on the center line along the plane of the lid 20, and the connecting portion 32 is provided at a position corresponding to the vent 22. Since the portion of the vent 22, which has low rigidity, is supported by the connecting portion 32, the rigidity of the lid 20 can be increased. In addition, deformation of the battery case can be suppressed even if external stress is applied to the battery pack 1. Since the vent 22 functions as an outlet for the cooling passage, the ventilation resistance is reduced, and the cooling performance can be improved.

[0028] In this embodiment, the lid portion 20 has a ventilation opening 22 formed on the center line along the plane of the lid portion 20, and the cooling duct 30 is located in the center of the bottom surface of the case body portion 10 and includes a support portion 34 that supports the connecting portion 32. Since the ventilation opening 22, which serves as the outlet for the cooling duct 30, is positioned on the upper part of the support portion 34, deformation of the case when external stress is applied can be suppressed and the rigidity of the lid portion 20 can be improved.

[0029] Furthermore, in this embodiment, the pair of legs 31 have a structure that extends along the shorter direction of the lid 20. This increases the rigidity of the battery case.

[0030] Furthermore, in this embodiment, the cooling passage of the cooling duct 30 is formed over a portion of the longitudinal direction of the lid portion 20. As a result, the members constituting the cooling passage function like beams within the battery case, thereby increasing the rigidity of the battery case.

[0031] In this embodiment, the member that secures the case body 10 and the lid 20, and the structure that secures the cooling duct 30 and the case body 10 are not limited to structures using fastening members such as screws, but may also be structures such as crimping. [Explanation of Symbols]

[0032] 1 Battery Pack 10. Case body 11 Bottom 12 Side 13 Flange 20 Lid 21 Protrusion 22 Ventilation holes 30 Cooling ducts 31 Legs 32 Connecting part 33 sealing member 34 Support part 40-cell stack

Claims

1. A battery case that houses the cell stack, Equipped with a cooling duct, The aforementioned battery case is The case body on which the cell stack is placed, The case comprises a lid that covers the cell stack and the cooling duct and is fixed to the case body, The cooling duct is provided with a pair of legs that support the lid at both ends of the cooling duct. A portion of the underside of the lid covers the opening of the cooling duct. The aforementioned pair of legs are a battery pack fixed to the case body.

2. The opening is provided on the top surface of the cooling duct. The battery pack according to claim 1, wherein the portion of the lid that covers the opening becomes a component of a cooling passage of the cooling duct.

3. The battery pack according to claim 1 or 2, wherein the cooling duct comprises a connecting portion that connects the pair of legs and supports the lid.

4. The lid portion is provided with a ventilation opening formed on the center line along the plane of the lid portion, The battery pack according to claim 3, wherein the connecting portion is provided at a position corresponding to the ventilation opening.

5. The lid portion has a ventilation opening formed on the center line along the plane of the lid portion, The battery pack according to claim 3, wherein the cooling duct is located in the center of the bottom surface of the case body and includes a support portion that supports the connecting portion.

6. The lid is rectangular when viewed from one direction. The battery pack according to claim 1 or 2, wherein the pair of legs have a structure that extends along the short direction of the lid.

7. The lid is rectangular when viewed from one direction. The battery pack according to claim 2, wherein the cooling passage is formed over a portion of the lid in the longitudinal direction.

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