Welding structure of member and welding method of member and assembled battery and manufacturing method of assembled battery

Abstract

To provide a structure and a method for welding a member which achieve high quality of a welding part, and to provide an assembled battery and a manufacturing method of the assembled battery.SOLUTION: A welding structure of a member includes: a first member having a first surface; a second member having a second surface which faces the first surface of the first member and a through hole which reaches the second surface; and a welding part provided between the first surface of the first member and the second surface of the second member and configured to join the first member and the second member to each other. The through hole is provided at a position which overlaps with the welding part in a first direction and is located adjacent to the welding part in a second direction orthogonal to the first direction. The first surface facing the through hole is formed in a flat form.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present technology relates to a welded structure of members, a welding method of members, a battery pack, and a manufacturing method thereof. [Background technology]

[0002] Japanese Patent Application Laid-Open No. 2019-160727 (Patent Document 1) discloses detecting the height of the top surfaces of positive and negative electrode terminals exposed from recesses using a height measurement laser. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-160727 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to improve the quality of welds in the welded structure of components, it is necessary to more accurately grasp the quantitative effects of warping, foreign matter, etc. However, there is still room for improvement in conventional welded structures and welding methods.

[0005] An object of the present technology is to provide a welded structure of members with high-quality welds, a welding method for members, a battery pack, and a manufacturing method thereof. [Means for solving the problem]

[0006] The present technology provides the following welded structure and welding method for members, as well as a battery pack and a manufacturing method thereof.

[0007] [1] A welded structure of a member comprising: a first member having a first surface; a second member having a second surface opposing the first surface of the first member and a through hole reaching the second surface; and a weld portion provided between the first surface of the first member and the second surface of the second member, joining the first member and the second member; the through hole being provided at a position overlapping the weld portion in a first direction and adjacent to the weld portion in a second direction perpendicular to the first direction; and the first surface facing the through hole being formed flat.

[0008] [2] The welded structure of the member described in [1], wherein the welded portion is formed by laser welding.

[0009] [3] A welded structure of a member described in [1] or [2], wherein the thickness of the second member in a third direction perpendicular to the first direction and the second direction is 0.2 mm or more and 3.5 mm or less.

[0010] [4] The welding structure of members according to any one of [1] to [3], wherein the first member is a bus bar of a battery, and the second member is a terminal connected to wiring.

[0011] [5] The second member includes an extension portion extending on the opposite side of the through hole from the weld portion in the second direction, and a recess portion capable of engaging with another member on the opposite side of the extension portion from the weld portion in the second direction, a welding structure of a member described in any one of [1] to [4].

[0012] [6] A method for welding members, comprising the steps of: preparing a first member having a first surface; preparing a second member having a second surface and a through hole reaching the second surface; arranging the first member and the second member so that the first surface of the first member faces the second surface of the second member; measuring the distance between the first surface and the second surface at a portion where the through hole is located; and forming a weld that joins the first member and the second member at a position that overlaps with the through hole in a first direction and is adjacent to the through hole in a second direction perpendicular to the first direction, wherein the first surface facing the through hole is formed flat.

[0013] [7] The method for welding members according to [6], wherein the welded portion is formed by laser welding.

[0014] [8] The method for welding members according to [6] or [7], wherein the thickness of the second member in the first direction is 0.2 mm or more and 3.5 mm or less.

[0015] [9] The method for welding members according to any one of [6] to [8], wherein the first member is a bus bar of a battery, and the second member is a terminal connected to wiring.

[0016]

[10] A method for welding members described in any one of [6] to [9], wherein the second member includes an extension portion extending on the opposite side of the through hole from the weld portion in the second direction, and a recess portion capable of engaging with another member on the opposite side of the extension portion from the weld portion in the second direction.

[0017]

[11] A battery pack including a plurality of battery cells arranged in the first direction and the welded structure of components described in any one of [1] to [5].

[0018]

[12] A method for manufacturing a battery pack, comprising the method for welding members according to any one of [6] to

[10] . [Effects of the Invention]

[0019] According to this technology, by providing a through hole at a position overlapping the weld in a first direction and adjacent to the weld in a second direction perpendicular to the first direction, it is possible to accurately measure the gap between the first surface and the second surface through the through hole and quantitatively grasp the influence of warpage, foreign matter, etc. As a result, the quality of the weld can be improved. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a diagram showing a basic configuration of a battery module. [Figure 2] FIG. 2 is a perspective view showing a battery cell. [Figure 3] FIG. 10 is a perspective view showing a state in which a wiring module is provided on a battery module. [Figure 4] FIG. 2 is a diagram showing the arrangement of bus bars in a battery pack. [Figure 5] FIG. 2 is a perspective view showing an example of a welded structure of members. [Figure 6] 6 is a cross-sectional view taken along the line VI-VI in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present technology will be described. Note that the same or corresponding parts are denoted by the same reference characters, and description thereof may not be repeated.

[0022] In the embodiments described below, when numbers, amounts, etc. are mentioned, the scope of the present technology is not necessarily limited to those numbers, amounts, etc., unless otherwise specified. Furthermore, in the following embodiments, each component is not necessarily essential to the present technology, unless otherwise specified. Furthermore, the present technology is not necessarily limited to those that achieve all of the effects and advantages mentioned in the present embodiments.

[0023] In this specification, the terms "comprise," "include," and "have" are open-ended. That is, when a certain feature is included, other features may or may not be included.

[0024] Furthermore, when geometric terms and terms expressing positional and directional relationships are used in this specification, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along," these terms allow for manufacturing errors and slight variations. When terms expressing relative positional relationships, such as "upper side" and "lower side," are used in this specification, these terms are used to indicate relative positional relationships in a single state, and the relative positional relationships can be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

[0025] In this specification, the term "battery" is not limited to lithium-ion batteries, but may include other batteries such as nickel-metal hydride batteries and sodium-ion batteries. In this specification, the term "electrode" may collectively refer to positive and negative electrodes. Furthermore, the term "electrode plate" may collectively refer to positive and negative plates.

[0026] In this specification, "battery cells" are not necessarily limited to prismatic ones, but may also include cells of other shapes, such as cylindrical, pouch, and blade types. Furthermore, "batteries" can be installed in hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs). However, the use of "batteries" is not limited to in-vehicle use.

[0027] 1 is a diagram showing the basic configuration of a battery pack 1. As shown in FIG. 1, the battery pack 1 includes battery cells 100, end plates 200, and restraining members 300.

[0028] The multiple battery cells 100 are arranged in a line in the Y-axis direction. This forms a stack of the battery cells 100. The battery cells 100 include electrode terminals 110. Separators (not shown) are interposed between the multiple battery cells 100. The multiple battery cells 100 sandwiched between the two end plates 200 are pressed by the end plates 200 and are constrained between the two end plates 200.

[0029] The end plates 200 are arranged on both ends of the battery pack 1 in the Y-axis direction. The end plates 200 are fixed to a base such as a case that houses the battery pack 1. The restraining members 300 connect the two end plates 200 to each other.

[0030] By fixing the restraining members 300 to the end plates 200 while a compressive force in the Y-axis direction is applied to the stack of multiple battery cells 100 and end plates 200, and then releasing the compressive force, a tensile force acts on the restraining members 300 connecting the two end plates 200. In reaction to this, the restraining members 300 press the two end plates 200 in a direction that brings them closer to each other.

[0031] Fig. 2 is a perspective view showing the battery cell 100. As shown in Fig. 2, the battery cell 100 has a rectangular shape. The battery cell 100 has electrode terminals 110 and a housing 120 (external can). In other words, the battery cell 100 is a rectangular secondary battery cell.

[0032] The electrode terminal 110 is formed on the housing 120. The electrode terminal 110 has a positive electrode terminal 111 and a negative electrode terminal 112 that are aligned along the X-axis direction that is perpendicular to the Y-axis direction. The positive electrode terminal 111 and the negative electrode terminal 112 are spaced apart from each other in the X-axis direction.

[0033] The housing 120 has a rectangular parallelepiped shape and forms the exterior of the battery cell 100. The housing 120 includes a case body 120A that houses an electrode assembly and an electrolyte (not shown), and a sealing plate 120B that seals the opening of the case body 120A. The sealing plate 120B is joined to the case body 120A by welding.

[0034] The housing 120 has an upper surface 121, a lower surface 122, a first side surface 123, a second side surface 124, and two third side surfaces 125. The housing 120 is provided with a gas exhaust valve 126.

[0035] The upper surface 121 is a plane perpendicular to the Z-axis direction, which is perpendicular to the Y-axis direction and the X-axis direction. The electrode terminals 110 are disposed on the upper surface 121. The lower surface 122 faces the upper surface 121 along the Z-axis direction.

[0036] Each of the first side surface 123 and the second side surface 124 is made of a plane perpendicular to the Y-axis direction. Each of the first side surface 123 and the second side surface 124 has the largest area among the multiple side surfaces of the housing 120. Each of the first side surface 123 and the second side surface 124 has a rectangular shape when viewed in the Y-axis direction. Each of the first side surface 123 and the second side surface 124 has a rectangular shape when viewed in the Y-axis direction, with the X-axis direction being the longitudinal direction and the Z-axis direction being the lateral direction.

[0037] The multiple battery cells 100 are stacked such that the first side surfaces 123 and the second side surfaces 124 of the battery cells 100 adjacent to each other in the Y-axis direction face each other. As a result, the positive electrode terminals 111 and the negative electrode terminals 112 are arranged alternately in the Y-axis direction in which the multiple battery cells 100 are stacked.

[0038] Gas exhaust valve 126 is provided on top surface 121. When the temperature of battery cell 100 rises (thermal runaway) and the internal pressure of housing 120 exceeds a predetermined value due to gas generated inside housing 120, gas exhaust valve 126 exhausts the gas to the outside of housing 120.

[0039] Fig. 3 is a perspective view showing a state in which a wiring module is provided on the battery pack 1. As shown in Fig. 3, a plate member 400 is placed on the battery pack 1, and a wiring member 500 is provided on the plate member 400. The wiring member 500 can be electrically connected to an external device via a connector 600. A cover member 700 is provided on the plate member 400 so as to cover the wiring member 500.

[0040] Fig. 4 is a diagram showing the arrangement of bus bars 800 in the battery pack 1. In the example of Fig. 4, the positive electrode terminals 111 and negative electrode terminals 112 of adjacent battery cells 100 are electrically connected by the bus bars 800, and the plurality of battery cells 100 are electrically connected in series.

[0041] That is, the battery pack 1 includes a plurality of battery cells 100, each having an electrode terminal 110, arranged along a predetermined direction (Y-axis direction), and a bus bar 800 (first member) that connects the electrode terminals 110 of the plurality of battery cells 100 together.

[0042] Fig. 5 is a perspective view showing an example of a welding structure of members. As shown in Fig. 5, a wiring member 500 includes a flexible printed circuit board 510 and a terminal member 520 (second member).

[0043] The flexible printed circuit board 510 has a structure in which a flexible thin-film insulating film and a conductive foil are bonded together using an adhesive, and can be repeatedly deformed with a weak force. In the flexible printed circuit board 510, the insulating film is made of, for example, polyimide, and the conductive foil is made of, for example, copper foil. The conductive foil of the flexible printed circuit board 510 forms the wiring in the wiring member 500.

[0044] Terminal member 520 may be configured as a plate-like member made of a conductive material such as metal (more specifically, aluminum). One end of terminal member 520 is disposed so as to overlap flexible printed circuit board 510. The other end of terminal member 520 is welded and connected to bus bar 800 at welded portion 1000. Welded portion 1000 may be formed by laser welding, for example.

[0045] The thickness of terminal member 520 can be, for example, about 0.2 mm to 3.5 mm (preferably about 0.2 mm to 1.0 mm, and more preferably about 0.5 mm to 0.8 mm), but the material and thickness of terminal member 520 are not limited to the above ranges.

[0046] Terminal member 520 has through-hole 520A. Through-hole 520A has a substantially circular shape. The diameter of through-hole 520A (if through-hole 520A is not circular, its width in the Y-axis direction) is approximately 0.1 mm or more and approximately 10.0 mm or less (more preferably, approximately 1.6 mm or more and 7.0 mm or less). However, the shape or width of through-hole 520A is not limited to the above range.

[0047] Through hole 520A is provided at a position overlapping with welded portion 1000 in the Y-axis direction (first direction) and adjacent to welded portion 1000 in the X-axis direction (second direction) perpendicular to the Y-axis direction.

[0048] In other words, the welding portion 1000 joining the bus bar 800 and the terminal member 520 is provided at a position overlapping with the through hole 520A in the Y-axis direction (first direction) and adjacent to the through hole 520A in the X-axis direction (second direction) perpendicular to the Y-axis direction.

[0049] Note that "adjacent" here is not limited to the case where through hole 520A and welded portion 1000 are directly adjacent to each other in the X-axis direction, but also includes the case where through hole 520A and welded portion 1000 are located near each other in the X-axis direction (for example, the separation distance between them is approximately 0.0 mm or more and 10.0 mm or less). However, the separation distance between them is not limited to the above range.

[0050] Because through hole 520A is provided near welded portion 1000, it is possible to detect the position of through hole 520A and determine the position of welded portion 1000 based on the detected position. As a result, the process of forming welded portion 1000 is made more efficient.

[0051] The wiring provided inside flexible printed circuit board 510 is electrically connected to terminal member 520 via solder joint. By joining terminal member 520 and bus bar 800, wiring member 500 and bus bar 800 are electrically connected.

[0052] In the example shown in FIG. 5, an end of the flexible printed circuit board 510 extending in the Y-axis direction and an end of the terminal member 520 extending in the X-axis direction are overlapped and joined to each other.

[0053] The terminal member 520 includes a recess 521, a wide portion 522, and an extending portion 523. The welding portion 1000 is provided in the wide portion 522.

[0054] Recess 521 is provided on the opposite side of welded portion 1000 from extension portion 523 in the X-axis direction. Recess 521 can engage with rib 910 provided on wall portion 900 (another member) that defines the accommodation portion of bus bar 800. This makes it possible to position terminal member 520 relative to bus bar 800. Through hole 520A is provided between two recesses 521 aligned in the Y-axis direction.

[0055] Wide portion 522 is provided at a position adjacent to recess 521 in the X-axis direction. Wide portion 522 is formed to be wider than recess 521 in the Y-axis direction, which makes it easy to ensure an area for forming weld 1000 extending in a strip or line in the Y-axis direction.

[0056] Extension portion 523 extends in the X-axis direction on the opposite side of through hole 520A from welded portion 1000. Since extension portion 523 extends in the X-axis direction, terminal member 520 can press bus bar 800 in the Z-axis direction (third direction).

[0057] However, the shapes and arrangements of the flexible printed circuit board 510 and the terminal members 520 are not limited to those shown in FIG.

[0058] 5, bus bar 800 has a substantially U-shape. However, the shape of bus bar 800 is not limited to that shown in FIG.

[0059] Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 5. As shown in Fig. 6, bus bar 800 has a first surface 810, and terminal member 520 has a second surface 524 facing first surface 810. Through hole 520A passes through terminal member 520 in the Z-axis direction and reaches second surface 524. First surface 810 facing through hole 520A is formed flat (so as to have no large protruding portions that would enter through hole 520A).

[0060] 6, for example, the size of the gap (H2-H1 in FIG. 6) in the Z-axis direction between first surface 810 of bus bar 800 and second surface 524 of terminal member 520 can vary depending on the degree of warping of bus bar 800. Even if bus bar 800 is not warped, the gap may become larger due to the intrusion of foreign matter between first surface 810 and second surface 524.

[0061] Since the first surface 810 facing the through hole 520A is flat, the above-mentioned gap (H2-H1) can be measured, for example, by irradiating laser light 10A from the sensor 10 onto each surface of the terminal member 520 and the bus bar 800.

[0062] 6, the warpage of bus bar 800 is exaggerated. For example, when the width of terminal member 520 in the Y-axis direction is approximately 5 mm, the increase in the gap due to the warpage of bus bar 800 is approximately 0.01 mm or more and 0.1 mm or less. However, the amount of change in the gap is not limited to the above range.

[0063] As described above, by measuring the size of the gap (H2-H1 in FIG. 6) in the Z-axis direction between the first surface 810 of the bus bar 800 and the second surface 524 of the terminal member 520, it is possible to determine whether the product is good or bad before forming the welded portion 1000. As a result, the quality of the welded structure can be improved.

[0064] Here, since the gap is measured through the through hole 520A located near the welded joint 1000, the condition of the welded joint 1000 can be grasped more accurately compared to when measuring at a position away from the welded joint 1000.

[0065] Furthermore, since the size of the gap can be determined by measuring only one location where the gap is likely to be relatively large, such as the center of through-hole 520A, it is also possible to reduce the number of steps required for measurement.

[0066] In the present embodiment, the welding structure between terminal member 520 and bus bar 800 has been described; however, the scope of application of the present technology is not limited to the above example, and may also be applied to welding structures of other members in battery pack 1. Furthermore, the scope of application of the present technology is not limited to battery pack 1, and may also be applied to welding structures of any members in electrical and electronic devices other than batteries.

[0067] Although the embodiments of the present technology have been described above, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present technology is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0068] 1 battery pack, 10 sensor, 10A laser light, 100 battery cell, 110 electrode terminal, 111 positive terminal, 112 negative terminal, 120 housing, 120A case body, 120B sealing plate, 121 upper surface, 122 lower surface, 123 first side surface, 124 second side surface, 125 third side surface, 126 gas release valve, 200 end plate, 300 restraining member, 400 plate member, 500 wiring member, 510 flexible printed circuit board, 520 terminal member, 520A through hole, 521 recess, 522 wide portion, 523 extension portion, 524 second surface, 600 connector, 700 cover member, 800 bus bar, 810 first surface, 900 wall portion, 910 rib, 1000 welded portion.

Claims

1. a first member having a first surface; a second member having a second surface facing the first surface of the first member and a through hole reaching the second surface; a weld portion provided between the first surface of the first member and the second surface of the second member, and joining the first member and the second member, the through hole is provided at a position overlapping the welded portion in a first direction and adjacent to the welded portion in a second direction perpendicular to the first direction, A welded structure of a member, wherein the first surface facing the through hole is formed flat.

2. The welded structure of members according to claim 1 , wherein the welded portion is formed by laser welding.

3. 3. The welded structure of members according to claim 1, wherein a thickness of the second member in a third direction perpendicular to the first direction and the second direction is 0.2 mm or more and 3.5 mm or less.

4. 3. The welded structure of members according to claim 1, wherein the first member is a bus bar of a battery, and the second member is a terminal connected to a wiring.

5. The second member is an extension portion extending on the opposite side of the through hole with respect to the weld portion in the second direction; The welded structure of members according to claim 1 or 2, further comprising a recess engageable with another member on the opposite side of the welded portion from the extension portion in the second direction.

6. Providing a first member having a first surface; providing a second member having a second surface and a through hole reaching the second surface; arranging the first member and the second member so that the first surface of the first member faces the second surface of the second member; measuring the distance between the first surface and the second surface at a portion where the through hole is located; forming a weld that joins the first member and the second member at a position that overlaps with the through hole in a first direction and is adjacent to the through hole in a second direction that is perpendicular to the first direction, A method for welding members, wherein the first surface facing the through hole is formed flat.

7. The method for welding members according to claim 6 , wherein the weld is formed by laser welding.

8. 8. The method for welding members according to claim 6 or 7, wherein the thickness of the second member in the first direction is 0.2 mm or more and 3.5 mm or less.

9. 8. The method for welding members according to claim 6, wherein the first member is a bus bar of a battery, and the second member is a terminal connected to a wiring.

10. The second member is an extension portion extending on the opposite side of the through hole with respect to the weld portion in the second direction; The method for welding members according to claim 6 or 7, further comprising a recess engageable with another member on the opposite side of the extension portion with respect to the weld portion in the second direction.

11. a plurality of battery cells arranged in the first direction; A battery pack comprising the welded structure of members according to claim 1 or 2.

12. A method for manufacturing a battery assembly, comprising the method for welding members according to claim 6 or 7.

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