Battery case side wall

Abstract

To improve a waterproof structure of a case side wall of a battery case of an on-vehicle battery.SOLUTION: A case side wall 28 and upper cover 24 are sealed together at an upper wall 44. The case side wall 28 and lower cover 26 are sealed together at an inner flange 40. A first member of the case side wall 28, consisting of a single steel plate, forms a portion of the upper wall 44 that is sealed and coupled to the upper cover 24, the inner flange 40, and an inner wall 48 together seamlessly and without holes. The inner wall 48 serves as a waterproof wall, preventing water from entering a battery housing space 51 of the battery case even if water enters a tubular portion 38 of the case side wall 28.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a battery case for housing an in-vehicle battery, and particularly to the structure of the case side wall.

Background Art

[0002] Vehicles equipped with an electric motor as a driving prime mover and a battery for supplying power to this electric motor are known. The battery is housed in a battery case having waterproof properties. Patent Document 1 below shows a battery case (battery case 100) in which a bathtub-shaped tray (120) is arranged inside a square frame-shaped frame (110), and a battery (battery 30) is housed in the recessed portion of the tray (120). A top cover (130) is arranged so as to cover the upper surface of the tray (120), and the inside of the tray (120) is sealed to ensure waterproof properties. Note that the member names and reference numerals within the above parentheses are those used in Patent Document 1 below, and are not related to the member names and reference numerals used in the description of the embodiments of the present application.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1 above, the peripheral wall of the tray and the frame are arranged around the battery housed in the battery case, and a plurality of members are arranged overlappingly. Therefore, there is a lot of waste in materials, and the space for mounting the battery becomes small.

[0005] An object of the present invention is to ensure waterproof properties while reducing the members constituting the battery case.

Means for Solving the Problems

[0006] The case side wall of the battery case for the vehicle battery of the present invention has a tubular portion with a closed cross-sectional structure formed by an upper wall, an inner wall, an outer wall, and a lower wall, and an inner flange that is arranged along the longitudinal direction of the tubular portion and erected on the inner wall, and is sealed and coupled to the lower cover of the battery case. The case side wall includes a first member made of a single steel plate that integrally forms the portion of the upper wall that is sealed and coupled to the upper cover of the battery case, the inner flange, and the portion of the inner wall from the upper edge to the erected portion of the inner flange, without any seams or holes. The case side wall is arranged along the longitudinal direction of the tubular portion and further has an outer flange erected between the upper and lower edges of the outer wall, which is coupled to a structure located to the side of the battery case, and the first member further forms the outer flange and the portion of the outer wall from the upper edge to the erected portion of the outer flange, and the case side wall further includes a second member made of steel plate that forms the portion of the outer wall from the erected portion of the outer flange to the lower edge and the lower wall, and the second member partially overlaps with the first member to form the outer flange together with the first member.

[0007] The case side wall is formed from a single steel plate, seamlessly and without holes between the portion that is sealed and bonded to the upper cover and the inner portion that is sealed and bonded to the lower cover, thereby preventing water from entering from the outside. Furthermore, the case sidewall can be formed using two components made of steel plates.

[0010] In the battery case described above, the inner flange may be erected on the lower edge of the inner wall of the case side wall. This allows for an increase in the height of the internal space of the battery case. [Effects of the Invention]

[0011] The side walls of the battery case themselves act as a waterproof barrier, preventing water from entering the inside of the case walls without requiring any additional waterproofing components inside the side walls. [Brief explanation of the drawing]

[0012] [Figure 1] This diagram shows the schematic configuration of an electric vehicle equipped with a battery. [Figure 2] This diagram shows the general configuration of the battery pack, with the top cover removed to reveal the internal components. [Figure 3] This figure shows a cross-section of the case side wall and its surrounding structure. [Figure 4] This figure shows the manner in which the first and second members forming the side wall of the case are joined. [Figure 5] This figure shows another aspect of the case side wall. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described below with reference to the drawings. In the following description, unless otherwise specified, terms expressing relative positions and orientations such as front, rear, left, right, up, and down refer to relative positions and orientations with respect to the vehicle. In addition, in the left-right direction (width direction) of the vehicle, the side closer to the centerline extending in the front-rear direction of the vehicle is referred to as the inner side in the vehicle width direction, and the side further away is referred to as the outer side in the vehicle width direction. In each figure, the direction of arrow FR is forward, the direction of arrow UP is upward, the direction of arrow LH is left, and the direction of arrow OUT is outward in the vehicle width direction.

[0014] Figure 1 shows a schematic configuration of the electric vehicle 10. The electric vehicle 10 may be a battery electric vehicle having only an electric motor as the prime mover for driving the vehicle, or it may be a hybrid electric vehicle having both an electric motor and an engine as the prime mover for driving the vehicle. The electric vehicle 10 has a battery pack 16 equipped with a battery that supplies power to the electric motor for driving the vehicle, located under the floor 14 of the passenger compartment 12.

[0015] Figure 2 is a perspective view showing the schematic configuration of the battery pack 16 with its interior visible. The battery pack 16 includes a battery stack 18 made of stacked battery cells and a battery case 20 that houses the battery stack 18. Only one battery stack 18 is shown in Figure 2. The battery case 20 includes a rectangular frame 22 and an upper cover 24 and a lower cover 26 that are positioned to sandwich the frame 22 from above and below. The upper cover 24 and the lower cover 26 are sealed and bonded to the frame 22 at their periphery, sealing the battery case 20. The frame 22, the upper cover 24 and the lower cover 26 define the space that houses the battery stack 18.

[0016] The frame 22 has left and right case side walls 28 extending in the front-rear direction and front and rear case end walls 30 extending in the left-right direction. The front ends of the left and right case side walls 28 are joined to both ends of the front case end wall 30, and the rear ends of the left and right case side walls 28 are joined to both ends of the rear case end wall 30, forming a rectangular frame shape. Between the left and right case side walls 28, an inner cross member 32 is positioned, extending in the left-right direction and with both ends joined to the case side walls 28. In the illustrated battery pack 16, there are four inner cross members 32. Battery stacks 18 are positioned between adjacent inner cross members 32 and between the rearmost inner cross member 32 and the rear case end wall 30. Thus, the battery case 20 houses four battery stacks 18.

[0017] An impact absorber 34 is positioned on the outer side of the frame 22 in the vehicle width direction. The impact absorber 34 is connected to the case side wall 28 by fasteners such as bolts and nuts. The impact absorber 34 is a structure that receives the impact load from the side when the electric vehicle 10 collides sideways. Furthermore, the impact absorber 34 deforms under the load it receives to absorb the impact energy and reduce the load applied to the battery pack 16. The impact absorber 34 is positioned extending along the longitudinal direction and has an outer shell with a closed cross-section that is roughly rectangular in cross-section perpendicular to the longitudinal direction, and at least one partition wall that divides the inner space of this outer shell in the left-right direction. The impact absorber 34 may be formed by extruding aluminum. The battery pack 16 is suspended and supported from the floor 14 via the impact absorber 34. The impact absorber 34 is fixed by bolts to rockers 36 (see Figure 3) located on the left and right side edges of the floor 14, and the battery pack 16 is fixed under the floor of the electric vehicle 10.

[0018] FIG. 3 is a cross-sectional view taken perpendicular to the longitudinal direction of the case side wall 28 of the battery pack 16 and its surrounding structure. The case side wall 28 has a tubular portion 38 having a generally quadrangular closed cross-sectional structure, an inner flange 40 extending inward in the vehicle width direction from the tubular portion 38, and an outer flange 42 extending outward in the vehicle width direction from the tubular portion 38. The outer flange 42 is formed by overlapping two steel plate members as will be described later. The tubular portion 38 has an upper wall 44 corresponding to the upper side of the quadrangular cross-sectional shape, a lower wall 46 corresponding to the lower side, an inner wall 48 corresponding to the side on the inner side in the vehicle width direction, and an outer wall 50 corresponding to the side on the outer side in the vehicle width direction. The inner wall 48 directly faces the space for accommodating the battery stack 18, that is, the battery accommodation space 51 of the battery case 20.

[0019] A reinforcing wall 52 is disposed in the internal space surrounded by the tubular portion 38. The reinforcing wall 52 extends along the longitudinal direction over the entire length of the case side wall 28. The reinforcing wall 52 may be disposed in a plane perpendicular to the vertical direction. The inner edge of the reinforcing wall 52 in the vehicle width direction reaches the inner wall 48, and the outer edge in the vehicle width direction reaches the outer wall 50. This battery case 20 includes two reinforcing walls 52. The upper reinforcing wall 52A is disposed at the same height position as the outer flange 42 formed by overlapping steel plates, that is, at the same position in the vertical direction. The lower reinforcing wall 52B is disposed approximately at the center between the upper reinforcing wall 52A and the lower wall 46. One reinforcing wall 52 may be disposed, or three or more reinforcing walls 52 may be disposed. The uppermost reinforcing wall 52 is disposed at the same height position as the outer flange 42.

[0020] The inner flange 40 stands on the inner wall 48 and extends in the vehicle longitudinal direction over the entire length of the case side wall 28. The inner flange 40 may be disposed at the lower edge of the tubular portion 38. The outer flange 42 stands on the outer wall 50 and extends in the vehicle longitudinal direction over the entire length of the case side wall 28. In particular, the outer flange 42 may be disposed at a position between the upper edge and the lower edge of the outer wall 50.

[0021] The inner flange 40 stands on the inner wall 48 and extends in the vehicle longitudinal direction over the entire length of the case side wall 28. The inner flange 40 may be disposed at the lower edge of the tubular portion 38. The outer flange 42 stands on the outer wall 50 and extends in the vehicle longitudinal direction over the entire length of the case side wall 28. In particular, the outer flange 42 may be disposed at a position between the upper edge and the lower edge of the outer wall 50. The outer flange 42 is fastened to the upper surface of the shock absorber 34 by bolts 54 and nuts 56. The portion of the case side wall 28 below the outer flange 42 faces the shock absorber 34. A circular tube-shaped collar 58 is further fixed to the shock absorber 34 by a method such as welding. The shock absorber 34 is fixed to the lower surface of a rocker 36, which is one of the skeletal members of the vehicle body, by a bolt 60 extending through the collar 58 and a nut (not shown). Thereby, the battery pack 16 is suspended and supported by the vehicle body.

[0022] The lower cover 26 is joined to the inner flange 40 by a method such as welding or adhesion, and the gap between them is sealed. The upper cover 24 is coupled to the case side wall 28, particularly the upper wall 44 of the tubular portion 38. The upper cover 24 is coupled to the upper wall 44 by rivets 62. Also, between the upper cover 24 and the upper wall 44, the space therebetween is sealed by a sealing member 64 such as an adhesive on the inner side in the vehicle width direction from the position where the upper cover 24 is coupled by the rivets 62. The sealing member 64 is arranged over the entire length of the case side wall 28.

[0023] The case side wall 28 is formed from two members, a first member 66 and a second member 68, each made of a roll-formed steel plate. The first member 66 and the second member 68 extend over the entire front-rear direction of the case side wall 28. The second member 68 may be divided into a plurality of parts in the front-rear direction. The first member 66 forms the inner flange 40, the inner wall 48, the upper wall 44, the portion of the outer wall 50 above the position where the outer flange 42 stands, and the outer flange 42. The first member 66 is formed by bending a single steel plate by rolling into the illustrated shape. The second member 68 forms the outer flange 42, the portion of the outer wall 50 below the position where the outer flange 42 stands, the lower wall 46, and the two reinforcing walls 52A, 52B. The second member 68 is also formed by bending a single steel plate by rolling into the illustrated shape. Hereinafter, the portion of the outer wall 50 above the outer flange 42 is referred to as "outer wall upper portion 50a", and the portion below as "outer wall lower portion 50b".

[0024] The second member 68 is joined to the first member 66 by overlapping a portion of it, and this overlapping portion together with the first member 66 forms the outer flange 42. Furthermore, the second member 68 is joined to the inner wall 48 by overlapping a portion of it in the portion between the portion forming the lower wall 46 and the portion forming the lower reinforcing wall 52B, and in the portion closer to the edge of the portion forming the upper reinforcing wall 52A. In addition, the second member 68 is joined to the portion between the portion forming the upper reinforcing wall 52A and the portion forming the lower reinforcing wall 52B by overlapping a portion that forms the lower outer wall portion 50b of itself.

[0025] By providing reinforcing walls 52 on the case side wall 28 at the same height as the outer flange 42 and below the outer flange 42, the strength of the portion of the case side wall 28 facing the impact absorber 34 is increased. When a load due to a lateral collision is applied to the case side wall 28 from the impact absorber 34, the collision load is received by the stronger portion, suppressing deformation of the case side wall 28. Furthermore, the thickness of the second member 68 forming the case side wall 28 may be thicker than the thickness of the first member. This makes it possible to increase the strength of the portion of the case side wall 28 facing the impact absorber 34.

[0026] Figure 4 is a schematic diagram showing an example of how the first member 66 and the second member 68 that form the case side wall 28 are joined. The × marks in the figure indicate the location of spot welding, the shaded oval areas indicate areas joined with adhesive, and the diagonally shaded semicircular areas indicate the Precure sticker areas.

[0027] The first member 66 and the second member 68 are joined by spot welding at the portion forming the outer flange 42. The joints 70 and 72 between the inner wall 48 and the second member 68 are joined by adhesive and spot welding. In addition, the second member 68 is overlapped with itself at the lower part 50b of the outer wall and joined by adhesive and spot welding (joint 74). Furthermore, the inner flange 40 of the first member 66 and the lower cover 26 are joined by adhesive and spot welding. The adhesive is applied along the entire length of the inner flange 40. In addition, Precure Sealer 76 is applied along the edge of the inner flange 40 and along the edge of the lower cover 26, along the entire length of the inner flange 40, and is cured in a later heating process to seal the space between the inner flange 40 and the lower cover 26.

[0028] The first member 66 of the case side wall 28 is seamlessly continuous with the portion of the upper wall 44 that is sealed and coupled with the upper cover 24, more specifically, the portion in contact with the sealing member 64, and extends through the inner wall 48 to the inner flange 40, and no holes are formed in this portion. Therefore, even if water enters the inside of the tubular portion 38 through holes formed in the upper wall 44 for passing the rivets 62, or through the gap between the first member 66 and the second member 68 of the outer flange 42, the first member 66 prevents it from entering, thus preventing the water from further entering the internal space of the battery case 20 that houses the battery stack 18.

[0029] Figure 5 shows another embodiment of the case side wall 80. The case side wall 80 differs from the case side wall 28 described above in the embodiment of the second member 82, which corresponds to the second member 68. The second member 82 of the case side wall 80 has the same overall shape as the second member 68, but is composed of two parts 82A and 82B formed from different steel plates. One part 82A forms the outer flange 42 and the lower outer wall portion 50b, while the other part 82B forms the lower wall 46 and the reinforcing wall 52. Both parts 82A and 82B may be formed by roll forming of steel plates. In yet another embodiment of the case side wall, one member may form the outer flange 42, the lower outer wall portion 50b and the lower wall 46, and the other member may form the reinforcing wall 52. [Explanation of symbols]

[0030] 10 Electric vehicle, 16 Battery pack, 18 Battery stack, 20 Battery case, 22 Frame, 24 Upper cover, 26 Lower cover, 28, 80 Case side wall, 30 Case end wall, 34 Shock absorber, 38 Tubular section, 40 Inner flange, 42 Outer flange, 44 Upper wall, 46 Lower wall, 48 Inner wall, 50 Outer wall, 50a Upper part of outer wall, 50b Lower part of outer wall, 52 Reinforcement wall, 62 Rivet, 64 Sealing member, 66 First member, 68, 82 Second member.

Claims

1. The side wall of the battery case of a vehicle battery, A tubular portion of a closed cross-sectional structure formed by an upper wall, an inner wall, an outer wall, and a lower wall, An inner flange positioned along the longitudinal direction of the tubular portion and erected on the inner wall, the inner flange being sealed and coupled to the lower cover of the battery case, It has, The case side wall includes a first member made of a single steel plate that integrally forms the portion of the upper wall that is sealed and coupled with the upper cover of the battery case, the inner flange, and the portion of the inner wall from the upper edge to the upright portion of the inner flange, without any seams or holes. The case side wall is arranged along the longitudinal direction of the tubular portion and has an outer flange erected between the upper and lower edges of the outer wall, which is coupled to a structure located to the side of the battery case. The first member further forms the outer flange and the portion of the outer wall from the upper edge to the upright portion of the outer flange. The side wall of the case is further, The outer wall includes a second member made of steel plate that forms the portion of the outer flange from the upright portion to the lower edge and the lower wall, The second member partially overlaps with the first member and together with the first member forms the outer flange. The side wall of the battery case.

2. A case side wall of a battery case according to claim 1, wherein the inner flange is erected on the lower edge of the inner wall.

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