Novel matching structure of square shell power battery shell and cover plate

Abstract

The invention provides a novel square-shell power battery shell and cover plate matching structure, and relates to the technical field of power battery shells, the structure specifically comprises a shell, a shell opening and a cover plate; the shell is divided into at least four wall thickness designs from the shell opening to the bottom, and the wall thickness design comprises the steps that the shell is divided into a plurality of sections from the shell opening to the bottom, and the wall thicknesses of the adjacent sections are sequentially alternated; the wall thickness of a first section, downward from a shell opening, of the shell is designed to be a thick-wall section, and the thickness value is set to be A; the vertical height H3 from the first section to a shell opening needs to be larger than the sum of the depth H1 of a laser welding pool and the height H2 of a shell welding heat affected area; the thickness value of a second section of the shell downward from the shell opening is set to be B, and B is smaller than the thickness value A of the first section; the cover plate is subjected to corresponding convex profiling design according to a matching structure with a corresponding size; the thickness value of the third section of the shell from the shell opening to the lower portion is set to be C, and C is larger than the thickness value B of the second section.

Description

Technical Field

[0001] The present invention relates to the technical field of power battery casings, and in particular to a novel matching structure between a square-shell power battery casing and a cover plate. Background Art

[0002] At present, the rapid development of new energy vehicles is booming, and the market demand for power batteries is in short supply. Common power batteries are divided into three categories according to their packaging and structure: soft-pack power batteries, square-shell power batteries and cylindrical power batteries. At present, the square-shell power batteries have the largest market share;

[0003] Square shell power battery usually consists of two parts: cover plate and shell, such as Figure 1 As shown, the cover plate 3 and the shell 2 are combined and packaged on the shell opening 1 by laser welding to achieve sealing inside the power battery;

[0004] The current mainstream structural design: the shell adopts a uniform wall thickness design in the length direction, and the assembly form of the cover and the shell is straight edge matching straight edge. After the shell and the cover are assembled, they are laser welded to achieve combined packaging. Figure 2 As shown;

[0005] Pain point 1: The cover and the shell are assembled straight, and there is no structural limit in the height direction, which usually makes it difficult to assemble the A and B benchmarks flat, and then makes it difficult to control the height of the battery cell pole, such as Figure 3 As shown:

[0006] Pain point 2: The cover and the shell are assembled on the straight edge. When laser welding is performed, the laser can easily pass through the assembly gap and penetrate into the battery cell, damaging the internal structure of the battery cell. Figure 4 As shown, once the damaged structure is the internal insulation and other performance parts, it is very easy to cause the internal short circuit of the battery cell to lose control, and then catch fire and explode;

[0007] Pain point 3: When the cover and the shell are assembled on the straight edge, the welding beads generated by the welding pool can easily flow from the assembly gap to the inside of the battery cell during laser welding. Figure 5 As shown, once such free, conductive metal beads exist inside the battery cell, it is very easy to cause a short circuit inside the battery cell, leading to a fire and explosion.

[0008] Pain point 4: When the cover and the shell are assembled on the straight edge, the heat-affected zone of the shell welding is prone to fatigue or brittle fracture during the subsequent use of the battery, causing the battery cell packaging to fail. Figure 6 shown. Summary of the invention

[0009] In view of the shortcomings of the prior art, the present invention provides a novel matching structure between a square shell power battery housing and a cover plate;

[0010] The technical solution of the present invention is:

[0011] A novel matching structure of a square shell power battery shell and a cover plate, specifically comprising: a shell, a shell opening and a cover plate;

[0012] The shell has at least four wall thickness designs from the shell opening downwards, and the wall thickness designs include: the shell is divided into several sections from the shell opening downwards, and the wall thicknesses of adjacent sections are alternately thin and thick;

[0013] The first section of the shell from the shell opening downward is designed to be a thick wall section, and the thickness value is set to A; the vertical height H3 of the first section from the shell opening needs to be greater than the sum of the laser welding molten pool depth H1 and the shell welding heat affected zone height H2;

[0014] The thickness value of the second section of the shell from the shell opening downward is set to B, and B is smaller than the thickness value A of the first section; the matching structure of the corresponding size of the cover plate is designed with a corresponding protruding profiling;

[0015] The thickness value of the third section of the shell from the shell opening downward is set to C, and C is greater than the thickness value B of the second section.

[0016] The beneficial effects of adopting the above technical solution are:

[0017] The present invention provides a novel matching structure between a square shell power battery casing and a cover plate, which improves the existing square shell power battery casing and solves the pain points 1-4 in the background technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of a traditional square shell power battery in the background technology of the present invention;

[0019] 1-shell opening, 2-shell, 3-cover plate;

[0020] Figure 2 This is a schematic diagram of the structure of a mainstream square shell power battery in the background technology of the present invention;

[0021] Figure 3 It is a structural schematic diagram of pain point 1 in the background technology of the present invention;

[0022] Figure 4 It is a structural schematic diagram of pain point 2 in the background technology of the present invention;

[0023] Figure 5 This is a schematic diagram of the structure of pain point 3 in the background technology of the present invention;

[0024] Figure 6 It is a structural schematic diagram of pain point 4 in the background technology of the present invention;

[0025] Figure 7 This is a schematic diagram of the structure of a segmented wall thickness shell of the present invention;

[0026] Figure 8 This is a schematic diagram of the wall thickness structure of the first section of the shell opening downwards according to the present invention;

[0027] Fig. 9 This is a schematic diagram of the wall thickness structure of the second section of the shell opening downwards according to the present invention;

[0028] Fig.10 This is a schematic diagram of the wall thickness structure of the third section downward from the shell opening of the present invention;

[0029] Fig.11 An exploded view of the housing and the cover plate of the present invention;

[0030] Fig.12 Detailed views of different wall thickness designs of the shell of the present invention;

[0031] Fig.13 Detailed view of the contoured structure design for matching the cover plate of the present invention with the different wall thicknesses of the housing. DETAILED DESCRIPTION

[0032] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0033] A novel matching structure of a square shell power battery shell and a cover plate, specifically comprising: a shell 2, a shell opening 1 and a cover plate 3;

[0034] The shell 2 has at least four wall thickness designs from the shell opening 1 downward. In this embodiment, the first thickness value of the shell from the shell opening downward is set to A, the second thickness value is set to B, the third thickness value is set to C, and the fourth thickness value is set to D, wherein the relationship between A, B, C, and D is: A>B, B<C, C>D; Figure 7 As shown;

[0035] The first section of the shell wall thickness from the shell opening downward is designed to be a thick wall section, and the vertical height H3 of the thick wall section from the shell opening needs to be greater than the sum of the laser welding molten pool depth H1 and the shell welding heat affected zone height H2; Figure 8 As shown, the wall thickness of the heat-affected zone of the shell welding is ensured to be thicker and the strength is higher, thereby improving the pain point 4 of the background technology;

[0036] The thickness value B of the second section of the shell from the shell opening downward is less than the thickness value A of the first section; the matching structure of the corresponding size of the cover plate 3 is designed with a corresponding protruding profile, such as Fig. 9As shown, this section has two functions. First, the protruding structure of the cover plate can block the laser from leaking from the gap between the shell and cover to the inside of the battery cell during laser welding. Second, this structure can block the molten beads from leaking from the gap between the shell and cover to the inside of the battery cell during laser welding, thereby improving pain points 2 and 3. The exploded diagram of the shell and the cover plate in this embodiment is shown in FIG. Fig.11 As shown;

[0037] The thickness value C of the third section of the shell from the shell opening downward is greater than the thickness value B of the second section, the purpose of which is to have a certain limit fit with the protrusion of the cover plate, such as Fig.10 As shown, the assembly accuracy of the cover plate and the housing is ensured, thereby improving pain point 1. The detailed view of the different wall thickness designs of the housing in this embodiment is as follows Fig.12 As shown, the detailed view of the contoured structure design made by matching the plate with the different wall thickness of the shell is as follows Fig.13 shown.

[0038] The above description is only a preferred embodiment of the present disclosure and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present disclosure is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the above-mentioned inventive concept. For example, the above-mentioned features are replaced with the technical features with similar functions disclosed in the embodiments of the present disclosure (but not limited to) to form a technical solution.

Claims

1. A novel matching structure between a square shell power battery housing and a cover plate, characterized in that: Specifically include: Shell, shell opening and cover plate; The shell is divided into at least 4 wall thickness designs from the shell opening downwards, and the wall thickness design includes: the shell is divided into several sections from the shell opening downwards, and the wall thicknesses of adjacent sections are alternating in sequence.

2. A novel matching structure of a square shell power battery housing and a cover plate according to claim 1, characterized in that: The first section of the shell wall from the shell opening downward is designed to be a thick wall section, and the thickness value is set to A; the vertical height H3 of the first section from the shell opening needs to be greater than the sum of the laser welding molten pool depth H1 and the shell welding heat affected zone height H2.

3. A novel matching structure of a square shell power battery housing and a cover plate according to claim 2, characterized in that: The thickness value of the second section of the shell from the shell opening downward is set to B, and B is smaller than the thickness value A of the first section; the matching structure of the corresponding size of the cover plate is designed with a corresponding protruding profile.

4. A novel matching structure of a square shell power battery housing and a cover plate according to claim 3, characterized in that: The thickness value of the third section of the shell from the shell opening downward is set to C, and C is greater than the thickness value B of the second section.

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