Welding jig and method for manufacturing battery pack

Abstract

This welding jig is provided with a fixed tool having: passage holes through which intermediate parts of each of a first electrode tab and a second electrode tab are inserted; and supporting surfaces which extend along tip end portions that extend from each intermediate part to support the tip end portions. The welding jig is provided with a pressing tool in which a bus bar is set, the pressing tool including: a first opening portion for welding a first end portion; a second opening portion for welding a second end portion; a recessed portion capable of accommodating a tolerance portion; a first projecting portion that protrudes toward the first end portion; and a second projecting portion that protrudes toward the second end portion. The welding jig is provided with a pressure application mechanism that applies pressure in a direction in which the pressing tool and the fixed tool approach one another in a state in which the first end portion and the second end portion of the bus bar set in the pressing tool are aligned with the tip end portion of the first electrode tab and the tip end portion of the second electrode tab set on the fixed tool.

Description

Welding jig and battery assembly manufacturing method

[0001] The present invention relates to a welding jig and a method for manufacturing a battery pack.

[0002] JP2020-524380A discloses a welding jig.

[0003] The welding jig is used when welding two electrode leads extending from a secondary battery in a state where they are overlapped with a bus bar provided on an ICB assembly.

[0004] This welding jig could not be used to weld bus bars, which allow relative movement between the electrode leads of one secondary battery and the electrode leads of the other secondary battery due to expansion and contraction during charging and discharging, for example.

[0005] The present invention has been made in view of the above problems, and has an object to provide a welding jig and a method for manufacturing a battery pack that enable connection using a bus bar that allows relative movement of electrodes.

[0006] According to one aspect of the present invention, a welding jig is used to connect a first electrode tab extending from one secondary battery to a second electrode tab extending from another secondary battery using a bus bar having an allowance portion that connects the first end and the second end while allowing relative movement between them, and to weld the first end to the first electrode tab and the second end to the second electrode tab. The welding jig includes a fixture having a through hole through which intermediate portions of the first electrode tab and the second electrode tab are inserted, and a support surface that extends along and supports the tip ends extending from the intermediate portions. The welding jig includes a clamp on which the bus bar is set, the clamp having a first opening for welding the first end, a second opening for welding the second end, a recess capable of accommodating the allowance portion, a first protrusion protruding toward the first end, and a second protrusion protruding toward the second end. The welding jig is equipped with a pressure applying mechanism that applies pressure in directions in which the clamp and the fixture approach each other while aligning the first end and second end of the bus bar set in the clamp with the tip end of the first electrode tab and the tip end of the second electrode tab set in the fixture.

[0007] FIG. 1 is a side view of a main portion of a battery pack manufactured using a welding jig according to this embodiment. FIG. 2 is a perspective view showing the main portion of the battery pack. FIG. 3 is a perspective view showing a welding jig according to this embodiment. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. FIG. 5 is a perspective view showing a fixing tool. FIG. 6 is a perspective view showing a pressing tool. FIG. 7 is a perspective view showing the back surface of the pressing tool. FIG. 8 is a flowchart showing each step of a method for manufacturing a battery pack according to this embodiment. FIG. 9 is a view showing an electrode tab setting step. FIG. 10 is a view showing a busbar setting step. FIG. 11 is a view showing a pressure applying step. FIG. 12 is a view showing a welding step. FIG. 13 is a cross-sectional view showing the main portion of a welding jig according to a first modified example. FIG. 14 is a cross-sectional view showing the main portion of a welding jig according to a second modified example.

[0008] <Embodiments> Hereinafter, embodiments of the present invention will be described with reference to the drawings, etc. First, a battery pack manufactured using a welding jig according to the present invention will be described.

[0009] Fig. 1 is a side view of a main portion of a battery pack 20 manufactured using a welding jig 10 (see Fig. 3) according to this embodiment. Fig. 1 shows one end of each of secondary batteries 22A, 22B that make up the battery pack 20. Fig. 2 is a perspective view showing the main portion of the battery pack 20, with the main bodies of each of the secondary batteries 22A, 22B omitted.

[0010] The battery pack 20 shown in FIGS. 1 and 2 is mounted on an electric vehicle and supplies power to a driving motor provided in the vehicle.

[0011] The battery pack 20 is formed by connecting the same type of cells in series or parallel. Examples of the cells include secondary batteries (22A, 22B). Examples of the secondary batteries (22A, 22B) include lithium ion batteries and all-solid-state batteries. Each of the secondary batteries 22A, 22B in this embodiment is an all-solid-state battery that uses a solid electrolyte as the electrolyte layer. Each of the secondary batteries 22A, 22B is a pouch-type battery whose exterior casing 24 is made of a thin film.

[0012] In each of the secondary batteries 22A and 22B, lithium metal is deposited on the negative electrode side during charging. Therefore, in each of the secondary batteries 22A and 22B, a change occurs in the thickness of the exterior packaging material 24 during charging and discharging. Note that a change in the thickness of the exterior packaging material 24 can also occur in other secondary batteries.

[0013] 1 shows adjacent secondary batteries 22A and 22B. A first electrode tab 30 constituting the positive electrode extends from one end of the adjacent secondary battery 22A, and a second electrode tab 32 constituting the negative electrode extends from one end of the other secondary battery 22B.

[0014] The first electrode tab 30 has a bent tip end, and a first tip portion 30A constituting the tip end of the first electrode tab 30 extends in the arrangement direction 36 of the secondary batteries 22A, 22B. The second electrode tab 32 has a bent tip end, and a second tip portion 32A constituting the tip end of the second electrode tab 32 extends in the arrangement direction 36.

[0015] The first electrode tab 30 of one secondary battery 22A and the second electrode tab 32 of the other secondary battery 22B are connected by a bus bar 40. As a result, the one secondary battery 22A and the other secondary battery 22B are connected in series.

[0016] The bus bar 40 is made of a conductive metal plate, and the spring constant of the metal plate that makes up the bus bar 40 is set to be equal to or greater than 1 N / mm and equal to or less than 20 N / mm.

[0017] The bus bar 40 has a first end 40A connected to the first electrode tab 30, a second end 40B connected to the second electrode tab 32, and an allowance portion 40C that connects the first end 40A and the second end 40B and allows relative movement between the first end 40A and the second end 40B.

[0018] The tolerance portion 40C is configured by a busbar convex portion 44 as a convex portion that protrudes to one side of an imaginary straight line K that connects the first end 40A and the second end 40B. The busbar convex portion 44 has a first extending portion 44A extending to one side from the first end 40A, a second extending portion 44B extending to one side from the second end 40B, and a connecting portion 44C connecting the tip of the first extending portion 44A and the tip of the second extending portion 44B. As a result, the tolerance portion 40C elastically deforms, causing the extending portions 44A, 44B to move closer to or farther away from each other, thereby allowing relative movement between the first end 40A and the second end 40B.

[0019] The distance between the first end 40A and the second end 40B is configured to be slightly wider on the side of each end 40A, 40B than on the side of the connecting portion 44C. As a result, the tolerance portion 40C is accommodated in a recess 68 of the presser 60 (described later) in a state in which it is elastically deformed so that the distance between the first end 40A and the second end 40B is reduced (see FIG. 4). The bus bar 40 is held by the presser 60 by the force of the tolerance portion 40C in the recess 68 attempting to return to its original shape.

[0020] (Welding Jig) Next, the welding jig 10 according to the present invention will be described.

[0021] Fig. 3 is a perspective view showing the welding jig 10 according to this embodiment, and shows how the electrode tabs 30, 32 are welded using the welding jig 10. Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 3. Fig. 5 is a perspective view showing the fixture 50. Fig. 6 is a perspective view showing the presser 60. Fig. 7 is a perspective view showing the back surface of the presser 60.

[0022] The welding jig 10 shown in Figures 3 and 4 is a jig used when welding the first end 40A of the bus bar 40 to the first electrode tab 30 of one secondary battery 22A and when welding the second end 40B of the bus bar 40 to the second electrode tab 32 of the other secondary battery 22B.

[0023] The welding jig 10 includes a fixture 50 on which the electrode tabs 30, 32 of the secondary batteries 22A, 22B are set, a presser 60 on which the bus bar 40 is set, and a pressure applying mechanism 70.

[0024] 4 and 5, the fixture 50 is made of a rectangular metal plate. The fixture 50 has through-holes 52 through which the intermediate portions 30B, 32B of the first electrode tab 30 and the second electrode tab 32 are inserted. The fixture 50 also has support surfaces 54A, 54B that extend along the distal ends 30A, 32A extending from the intermediate portions 30B, 32B and support the distal ends 30A, 32A from below.

[0025] The passage hole 52 includes a first slit 52A and a second slit 52B that are spaced apart in the short-side direction of the fixture 50. The first electrode tab 30 is inserted into the first slit 52A, and the second electrode tab 32 is inserted into the second slit 52B.

[0026] The first slit 52A and the second slit 52B extend in the longitudinal direction of the fastener 50. The first slit 52A and the second slit 52B reach one side surface 50A (see FIG. 5) that constitutes a short side of the fastener 50. The ends of the first slit 52A and the second slit 52B open to one side surface 50A (see FIG. 5) that constitutes a short side of the fastener 50.

[0027] This allows each electrode tab 30, 32 to be inserted into each slit 52A, 52B opened in one side 50A of the fixture 50 by sliding the fixture 50 from the side of each electrode tab 30, 32 extending from each secondary battery 22A, 22B.

[0028] With the first intermediate portion 30B, which serves as an intermediate portion of the first electrode tab 30, inserted into the first slit 52A, the first tip portion 30A of the first electrode tab 30 is supported by a first support surface 54A, which serves as a support surface between the first slit 52A and the second slit 52B. With the second intermediate portion 32B, which serves as an intermediate portion of the second electrode tab 32, inserted into the second slit 52B, the second tip portion 32A of the second electrode tab 32 is supported by a second support surface 54B, which serves as a support surface between the second slit 52B and the long side of the fixture 50.

[0029] Semicircular protruding first stoppers 56A are formed in two locations on the edge of the first support surface 54A on the second slit 52B side, and the first electrode tab 30 inserted through the first slit 52A is positioned with its first tip 30A abutting against the arc-shaped portions of the first stoppers 56A. Semicircular protruding second stoppers 56B are formed in two locations on the edge of the long side of the second support surface 54B, and the second electrode tab 32 inserted through the second slit 52B is positioned with its second tip 32A abutting against the arc-shaped portions of the second stoppers 56B.

[0030] First screw holes 58A are formed on one and the other longitudinal sides of the first support surface 54A, and second screw holes 58B are formed on one and the other longitudinal sides of the second support surface 54B.

[0031] 4, 6, and 7, the presser 60 includes a first presser 60A and a second presser 60B arranged adjacent to each other. The first presser 60A and the second presser 60B are each formed in a rectangular parallelepiped shape.

[0032] The first retainer 60A has a first circular hole 62A formed at each end in the longitudinal direction. Each first circular hole 62A communicates with a corresponding first screw hole 58A when the first retainer 60A is set in the fixture 50.

[0033] First openings 64A1, 64A2 for welding the first end portion 40A are formed between the pair of first circular holes 62A. Each of the first openings 64A1, 64A2 has a rectangular shape extending in the longitudinal direction of the first presser 60A, and each of the first openings 64A1, 64A2 is formed in an elongated shape.

[0034] First protrusions 66A1 and 66A2 are formed on the back surface of the first presser 60A (see FIG. 7 ). Each of the first protrusions 66A1 and 66A2 protrudes toward the first end 40A of the bus bar 40 when the bus bar 40 is set in the presser 60A.

[0035] The first protrusion 66A1 extends linearly along the edge of the first opening 64A1. The first protrusion 66A2 extends linearly along the edge of the first opening 64A2. Each of the first protrusions 66A1, 66A2 has a triangular cross section that tapers toward the tip.

[0036] As a result, the first protrusions 66A1, 66A2 are configured so that the tip of each of the first protrusions 66A1, 66A2 comes into line contact with the contact object.

[0037] The second retainer 60B has a through second circular hole 62B formed at each end in the longitudinal direction. Each second circular hole 62B communicates with a corresponding second screw hole 58B when the second retainer 60B is set in the fixture 50.

[0038] Second openings 64B1, 64B2 for welding the second end portion 40B are formed between the pair of second circular holes 62B. Each of the second openings 64B1, 64B2 has a rectangular shape extending in the longitudinal direction of the second presser 60B, and each of the second openings 64B1, 64B2 is formed in an elongated shape.

[0039] Second protrusions 66B1 and 66B2 are formed on the back surface of the second presser 60B. Each of the second protrusions 66B1 and 66B2 protrudes toward the second end 40B of the bus bar 40 when the bus bar 40 is set in the presser 60 (see FIG. 7).

[0040] The second protrusion 66B1 extends linearly along the edge of the second opening 64B1. The other second protrusion 66B2 extends linearly along the edge of the second opening 64B2. Each of the second protrusions 66B1, 66B2 has a triangular cross section that tapers toward the tip.

[0041] As a result, the second protrusions 66B1, 66B2 are configured so that the tip of each of the second protrusions 66B1, 66B2 comes into line contact with the contact object.

[0042] The presser 60 has a recess 68 that can accommodate the allowable portion 40C of the bus bar 40 when the first presser 60A and the second presser 60B are arranged adjacent to each other. The recess 68 has approximately the same length as the allowable portion 40C of the bus bar 40. The recess 68 has approximately the same width as the allowable portion 40C of the bus bar 40. The recess 68 is configured as a groove that can accommodate the allowable portion 40C of the bus bar 40 in a clamped state.

[0043] Specifically, the recess 68 is composed of a first step 68A formed on the back surface of the first clamping tool 60A and a second step 68B formed on the back surface of the second clamping tool 60B. The first step 68A of the first clamping tool 60A opens to a first opposing surface 60A1 facing the second clamping tool 60B. The second step 68B of the second clamping tool 60B opens to a second opposing surface 60B1 facing the first clamping tool 60A. A portion of the recess 68 communicates with the first openings 64A1 and 64A2. A portion of the recess 68 also communicates with the second openings 64B1 and 64B2.

[0044] (Pressure application mechanism) The pressure application mechanism 70 applies pressure in the direction in which the pressing tool 60 and the fixing tool 50 move closer to each other while aligning the first end 40A and the second end 40B of the bus bar 40 set in the pressing tool 60 with the first tip 30A of the first electrode tab 30 and the second tip 32A of the second electrode tab 32 set in the fixing tool 50.

[0045] Specifically, the pressure application mechanism 70 is composed of the screw holes 58A, 58B (see Figure 5) provided in the fixing device 50 and an operating screw 72 having a screw portion 72A (see Figure 3) that is inserted through the circular holes 62A, 62B of the pressing device 60 and screwed into the screw holes 58A, 58B.

[0046] The pressure applying mechanism 70 positions the presser 60 relative to the fixing device 50 in a state in which the threaded portion 72A of the operating screw 72 is inserted into the circular holes 62A, 62B (see FIG. 6 ) of the presser 60 and threaded into the screw holes 58A, 58B (see FIG. 5 ) of the fixing device 50. In this positioned state, the first end 40A and the second end 40B of the bus bar 40 set in the presser 60 are positioned with the first tip 30A of the first electrode tab 30 and the second tip 32A of the second electrode tab 32 set in the fixing device 50.

[0047] In addition, the pressure application mechanism 70 can adjust the pressure applied from the pressure applying device 60 to the fixing device 50 by rotating the head 72B of the operating screw 72 to adjust the amount of threading of the screw portion 72A into the screw holes 58A, 58B.

[0048] In this embodiment, the pressure applying mechanism 70 is configured by the screw holes 58A, 58B of the fixture 50 and the operating screw 72, but the pressure applying mechanism 70 is not limited to this configuration. The pressure applying mechanism 70 may be configured by, for example, a clamper that clamps the presser 60 and the fixture 50 together with a predetermined pressure.

[0049] (Method for Manufacturing Battery Pack) Next, a method for manufacturing the battery pack 20 according to the present invention will be described.

[0050] Fig. 8 is a flowchart showing each step of the manufacturing method of the battery pack 20 according to this embodiment. Fig. 9 is a diagram showing the electrode tab setting step (step S10). Fig. 10 is a diagram showing the bus bar setting step (step S12). Fig. 11 is a diagram showing the pressure applying step (step S14). Fig. 12 is a diagram showing the welding step (step S16).

[0051] As shown in FIG. 8 , the method for manufacturing the battery pack 20 using the welding jig 10 includes an electrode tab setting step (step S10), a bus bar setting step (step S12), a pressure application step (step S14), and a welding step (step S16).

[0052] In this embodiment, the case where the bus bar setting step (step S12) is performed after the electrode tab setting step (step S10) is described as an example, but the manufacturing method of the battery pack 20 is not limited to this order. In this embodiment, for example, the electrode tab setting step (step S10) may be performed after the bus bar setting step (step S12).

[0053] (Electrode Tab Setting Step) As shown in FIGS. 8 and 9, in the electrode tab setting step (step S10), the worker sets the electrode tabs 30, 32 extending from the secondary batteries 22A, 22B in the fixture 50.

[0054] Specifically, the worker inserts a first intermediate portion 30B, which is a intermediate portion of the first electrode tab 30 extending from one secondary battery 22A, from one side surface 50A of the fixture 50 into a first slit 52A that forms the passage hole 52. Then, the worker positions a first tip portion 30A, which is a tip portion extending from the first intermediate portion 30B of the first electrode tab 30, along a first support surface 54A, which is a support surface. In this state, the worker positions the first electrode tab 30 in the fixture 50 with the tip of the first tip portion 30A abutting against a first stopper 56A.

[0055] The worker also inserts the second intermediate portion 32B, which is the intermediate portion of the second electrode tab 32 extending from the other secondary battery 22B, from one side surface 50A of the fixture 50 into the second slit 52B that forms the passage hole 52. The worker then positions the second tip portion 32A, which is the tip portion extending from the second intermediate portion 32B of the second electrode tab 32, along the second support surface 54B, which is the support surface. In this state, the worker positions the second electrode tab 32 in the fixture 50 with the tip of the second tip portion 32A abutting against the second stopper 56B provided on the fixture 50.

[0056] As a result, the first electrode tab 30 and the second electrode tab 32 are set in the fixture 50 .

[0057] (Busbar Setting Step) As shown in FIGS. 8 and 10 , in the busbar setting step (step S12 ), an operator sets the busbar 40 in the presser 60 .

[0058] Specifically, the worker places the tolerance portion 40C of the bus bar 40 between, for example, the first step 68A (see FIG. 7) of the first pressing tool 60A and the second step 68B of the second pressing tool 60B (see FIG. 7). In this state, the worker brings the first opposing surface 60A1 of the first pressing tool 60A into contact with the second opposing surface 60B1 of the second pressing tool 60B.

[0059] As a result, the busbar 40 elastically deforms so that the distance between the first extending portion 44A and the second extending portion 44B of the busbar protrusion 44 (see FIG. 1 ) that constitutes the tolerance portion 40C decreases. In its elastically deformed state, the tolerance portion 40C is accommodated in a recess 68 formed by a first step 68A of the first presser 60A and a second step 68B of the second presser 60B (see FIGS. 7 and 8 ). In this state, a restoring force is generated in the tolerance portion 40C within the recess 68, causing the tolerance portion 40C to return to its original shape. This restoring force holds the busbar 40 in the presser 60.

[0060] With the tolerance portion 40C accommodated in the recess 68 of the presser 60, the first end 40A of the bus bar 40 is aligned with the first protrusions 66A1 and 66A2 of the presser 60 (see FIG. 4). Also, the second end 40B of the bus bar 40 is aligned with the second protrusions 66B1 and 66B2 of the presser 60 (see FIG. 4).

[0061] As a result, the bus bar 40 is set in the retainer 60 .

[0062] (Pressure Application Step) As shown in FIGS. 8 and 11, in the pressure application step (step S14), the worker applies pressure in directions in which the presser tool 60 and the fixing tool 50 approach each other.

[0063] Specifically, the worker aligns the first end 40A of the bus bar 40 set in the presser 60 with the first tip 30A of the first electrode tab 30 set in the fixture 50. At this time, the worker aligns the second end 40B of the bus bar 40 with the second tip 32A of the second electrode tab 32. Then, the worker positions the presser 60 in the fixture 50 with the first end 40A and the second end 40B aligned with the first tip 30A of the first electrode tab 30 and the second tip 32A of the second electrode tab 32.

[0064] In this state, the operator inserts the threaded portion 72A of the operating screw 72 into each of the circular holes 62A, 62B of the presser 60 and screws it into the screw holes 58A, 58B of the fixing device 50 (see FIGS. 5 and 6 ). This sets the presser 60 to the fixing device 50. Furthermore, in this set state, the first end 40A and the second end 40B of the bus bar 40 set in the presser 60 are maintained in a state of being positioned with the first tip 30A of the first electrode tab 30 and the second tip 32A of the second electrode tab 32 set in the fixing device 50.

[0065] Next, the operator rotates the heads 72B of the operating screws 72 to adjust the amount of screwing of the screw portions 72A into the screw holes 58A, 58B, and adjusts the pressure applied from the presser 60 to the fixing device 50.

[0066] As a result, pressure is applied to the presser 60 and the fixing device 50 in directions that bring them closer to each other.

[0067] In this case, the presser 60 includes a first presser 60A having first protrusions 66A1 and 66A2 that press the first end 40A of the bus bar 40 and the first tip 30A of the first electrode tab 30 against the first support surface 54A (see FIG. 7 ). The presser 60 also includes a second presser 60B having second protrusions 66B1 and 66B2 that press the second end 40B of the bus bar 40 and the second tip 32A of the second electrode tab 32 against the second support surface 54B.

[0068] The amount of insertion of the operating screw 72 that presses the first presser 60A and the amount of insertion of the operating screw 72 that presses the second presser 60B can be adjusted separately. Therefore, even if the thickness of the first end 40A and the first tip portion 30A differs from the thickness of the second end 40B and the second tip portion 32A, it is possible to set the pressure applied by the first presser 60A and the second presser 60B to be approximately the same.

[0069] (Welding Step) As shown in FIGS. 8 and 12, in the welding step (step S16), a worker welds each end 40A, 40B of the bus bar 40 to the corresponding electrode tabs 30, 32 of each secondary battery 22A, 22B.

[0070] Specifically, the worker irradiates laser light 82 from laser head 80 through each of first openings 64A1, 64A2 of presser 60 onto first end 40A of bus bar 40 set in presser 60. In this way, the worker welds first end 40A of bus bar 40 to first tip 30A of first electrode tab 30 of one secondary battery 22A set in fixture 50. At this time, the worker irradiates laser light 82 along the edge of each of first openings 64A1, 64A2 located on the side of each of first convex portions 66A1, 66A2, for example, at a position close to the edge.

[0071] The worker also irradiates laser light 82 from laser head 80 through each of second openings 64B1, 64B2 of presser 60 onto second end 40B of bus bar 40 set in presser 60. In this way, the worker welds second end 40B to second tip 32A of second electrode tab 32 of the other secondary battery 22B set in fixture 50. At this time, the worker irradiates laser light 82 along the edge of each of second openings 64B1, 64B2 located on the second convex portions 66B1, 66AB side, for example, at a position close to the edge.

[0072] As a result, the first end 40A of the bus bar 40 is welded to the first electrode tab 30 and the second end 40B is welded to the second electrode tab 32.

[0073] Modifications of the above-described embodiment will be described below. In each modification, the same or equivalent parts as those in the above-described embodiment will be designated by the same reference numerals and will not be described again. Only the parts that differ from the above-described embodiment will be described. All modifications fall within the scope of the present invention, just like the above-described embodiment.

[0074] 13 is a cross-sectional view showing a main part of a welding jig 10 according to a first modification. The welding jig 10 according to the first modification differs from the embodiment described above in the formation of the protrusions 66A1, 66A2, 66B1, and 66B2.

[0075] 13, the first convex portions 66A1 (66A2) and the second convex portions 66B1 (66B2) formed on the first pressing tool 60A and the second pressing tool 60B of the pressing tool 60 have semicircular cross-sectional shapes. As a result, the first convex portions 66A1 (66A2) and the second convex portions 66B1 (66B2) have cross-sectional shapes that bulge in an arc shape from the first pressing tool 60A and the second pressing tool 60B.

[0076] Each of the first convex portions 66A1, 66A2 and each of the second convex portions 66B1, 66B2 has an arc-shaped cross section, which increases rigidity compared to when the cross section has a tapered shape.

[0077] 14 is a cross-sectional view showing a main part of a welding jig 10 according to a second modification. The welding jig 10 according to the second modification differs from the embodiment described above in the formation of the protrusions 66A1, 66A2, 66B1, and 66B2.

[0078] 14 , the first convex portions 66A1 (66A2) and the second convex portions 66B1 (66B2) formed on the first pressing tool 60A and the second pressing tool 60B of the pressing tool 60 are each frustum-shaped with the tip end at the top. A plurality of the first convex portions 66A1 (66A2) and the second convex portions 66B1 (66B2) are arranged along the first openings 64A1 (64A2) and the second openings 64B1 (64B2).

[0079] Each of the first convex portions 66A1, 66A2 and each of the second convex portions 66B1, 66B2 has a truncated quadrangular pyramid shape, and therefore has higher rigidity than when the cross section has a tapered shape.

[0080] (Operations and Effects) As described above, the welding jig 10 of the present embodiment is a jig used when connecting a first electrode tab 30 extending from one secondary battery 22A to a second electrode tab 32 extending from the other secondary battery 22B using a bus bar 40 having an allowance portion 40C that connects the first end 40A and the second end 40B while allowing relative movement between them, and when welding the first end 40A to the first electrode tab 30 and the second end 40B to the second electrode tab 32. The welding jig 10 includes a fixture 50 having a passage hole 52 through which the intermediate portions 30B, 32B of the first electrode tab 30 and the second electrode tab 32 are inserted, and support surfaces 54A, 54B that extend along the tip ends 30A, 32A extending from the intermediate portions 30B, 32B and support the tip ends 30A, 32A. The welding jig 10 includes a presser 60 on which the bus bar 40 is set, the presser 60 having first openings 64A1 and 64A2 for welding the first end 40A, second openings 64B1 and 64B2 for welding the second end 40B, a recess 68 capable of accommodating the tolerance portion 40C, first convex portions 66A1 and 66A2 protruding toward the first end 40A, and second convex portions 66B1 and 66B2 protruding toward the second end 40B. The welding jig 10 includes a pressure applying mechanism 70 that applies pressure to the presser 60 and the fixture 50 in directions toward each other when the first end 40A and the second end 40B of the bus bar 40 set in the presser 60 are aligned with the first tip portion 30A of the first electrode tab 30 and the second tip portion 32A of the second electrode tab 32 set in the fixture 50.

[0081] The welding jig 10 is capable of setting the bus bar 40, which has an allowance portion 40C that allows relative movement between the first end 40A and the second end 40B, on the presser 60. The first end 40A and the first electrode tab 30 of the bus bar 40 are pressed against the first support surface 54A of the fixture 50 by the first protrusions 66A1, 66A2 of the presser 60, thereby increasing the degree of contact between the first end 40A and the first electrode tab 30. The second end 40B and the second electrode tab 32 of the bus bar 40 are pressed against the second support surface 54B of the fixture 50 by the second protrusions 66B1, 66B2 of the presser 60, thereby increasing the degree of contact between the second end 40B and the second electrode tab 32.

[0082] In this way, the welding jig 10 can connect the first electrode tab 30 of one secondary battery 22A to the second electrode tab 32 of the other secondary battery 22B using a bus bar 40 that allows relative movement of the connected electrodes.

[0083] Furthermore, by using this welding jig 10, welding can be performed with increased adhesion between each end 40A, 40B of the bus bar 40 and each electrode tab 30, 32, thereby improving welding quality.

[0084] In the welding jig 10 of this embodiment, the allowable portion 40C of the busbar 40 is configured as a busbar convex portion 44 that protrudes to one side of an imaginary straight line K that connects the first end 40A and the second end 40B. The busbar convex portion 44 has a first extending portion 44A that extends to one side from the first end 40A, a second extending portion 44B that extends to one side from the second end 40B, and a connecting portion 44C that connects the tip of the first extending portion 44A to the tip of the second extending portion 44B. The recess 68 of the presser 60 is configured as a groove that can accommodate the allowable portion 40C of the busbar 40 in a clamped state.

[0085] Such a welding jig 10 can hold the busbar 40 in a state where the allowable portion 40C is clamped by the groove formed by the recess 68 of the clamping tool 60, even if the busbar 40 has an allowable portion 40C formed by the busbar convex portion 44.

[0086] In the welding jig 10 of this embodiment, the passage hole 52 of the fixture 50 includes a first slit 52A into which the first electrode tab 30 is inserted and a second slit 52B into which the second electrode tab 32 is inserted. Ends of the first slit 52A and the second slit 52B open to one side surface 50A of the fixture 50.

[0087] In such a welding jig 10, each electrode tab 30, 32 of each secondary battery 22A, 22B can be easily set in the fixture 50 by inserting it from one side 50A of the fixture 50 into each slit 52A, 52B that forms the passage hole 52.

[0088] Therefore, compared to the case where each electrode tab 30, 32 must be inserted into the passage hole 52 formed in the fixture 50 and then set in the fixture 50, it is possible to improve the workability when setting each electrode tab 30, 32 in the fixture 50.

[0089] In the welding jig 10 of this embodiment, the first openings 64A1, 64A2 and the second openings 34B1, 34B2 are formed in an elongated shape. The first convex portions 66A1, 66A2 and the second convex portions 66B1, 66B2 extend along the first openings 34A1, 34A2 and the second openings 64B1, 64B2.

[0090] In this welding jig 10, the protrusions 66A1, 66A2, 66B1, and 66B2 that press the ends 40A, 40B of the bus bar 40 and the electrode tabs 30, 32 against the support surfaces 54A, 54B extend along the openings 64A1, 64A2, 64B1, and 64B2. Therefore, when the laser beam 82 is irradiated along the openings 64A1, 64A2, 64B1, and 64B2, the protrusions 66A1, 66A2, 66B1, and 66B2 can press the ends 40A, 40B and the electrode tabs 30, 32 along the irradiation position of the laser beam 82.

[0091] Therefore, the welding jig 10 can weld with increased adhesion between each end 40A, 40B of the bus bar 40 and each electrode tab 30, 32 along the entire length of the welding point, thereby improving welding quality.

[0092] In the welding jig 10 of this embodiment, the first convex portions 66A1, 66A2 and the second convex portions 66B1, 66B2 have a cross-sectional shape that tapers toward the tip end.

[0093] In this welding jig 10, the protrusions 66A1, 66A2, 66B1, and 66B2 can concentrate the pressure at their tapered tips when pressing the ends 40A, 40B and the electrode tabs 30, 32 against the support surfaces 54A, 54B. This allows the welding jig 10 to increase the pressure applied to the ends 40A, 40B and the electrode tabs 30, 32. Furthermore, the welding jig 10 can reduce variations in pressure that can occur at each contact point compared to when the ends 40A, 40B and the electrode tabs 30, 32 are pressed against the support surfaces 54A, 54B using a flat surface. Therefore, the welding jig 10 can further improve welding quality.

[0094] In the welding jig 10 of this embodiment, the first convex portions 66A1, 66A2 and the second convex portions 66B1, 66B2 each have a cross-sectional shape that bulges in an arc shape (see FIG. 13).

[0095] In this welding jig 10, the protrusions 66A1, 66A2, 66B1, and 66B2 can concentrate the pressure applied to the ends 40A, 40B and the electrode tabs 30, 32 against the support surfaces 54A, 54B at the tips of their arc-shaped cross-sections. Therefore, the protrusions 66A1, 66A2, 66B1, and 66B2 can increase the pressure applied to the ends 40A, 40B and the electrode tabs 30, 32 compared to when the tips are flat. Furthermore, the welding jig 10 can reduce variations in pressure that can occur at each contact point compared to when the ends 40A, 40B and the electrode tabs 30, 32 are pressed against the support surfaces 54A, 54B using a flat surface. Therefore, the welding jig 10 can further improve welding quality.

[0096] Furthermore, since each of the convex portions 66A1, 66A2, 66B1, and 66B2 has a cross-sectional shape that bulges out in an arc, durability can be improved compared to when each of the convex portions 66A1, 66A2, 66B1, and 66B2 has a tapered cross-sectional shape.

[0097] In the welding jig 10 of this embodiment, the first convex portions 66A1, 66A2 and the second convex portions 66B1, 66B2 have a truncated quadrangular pyramid shape with the tip end as the upper base (see FIG. 14).

[0098] In such a welding jig 10, each of the protrusions 66A1, 66A2, 66B1, 66B2 has a quadrangular pyramid shape with the tip side as the upper base, so that the rectangular upper base can press each of the end portions 40A, 40B and each of the electrode tabs 30, 32 against each of the support surfaces 54A, 54B. Furthermore, each of the protrusions 66A1, 66A2, 66B1, 66B2 can increase the pressure applied to each of the end portions 40A, 40B and each of the electrode tabs 30, 32 compared to when they are formed in an elongated shape, which can contribute to improving welding quality.

[0099] The manufacturing method of the battery pack 20 of this embodiment is a manufacturing method using the above-described welding jig 10. The manufacturing method of the battery pack 20 includes an electrode tab setting process (step S10) of inserting the intermediate portions 30B, 32B of the first electrode tab 30 and the second electrode tab 32 into the passage hole 52 of the fixture 50 and setting the first electrode tab 30 and the second electrode tab 32 in the fixture 50 in a state in which the leading ends 30A, 32A extending from the intermediate portions 30B, 32B are arranged along the support surfaces 54A, 54B. The manufacturing method of the battery pack 20 includes a busbar setting step (step S12) of aligning the first end 40A of the busbar 40 with the first protrusions 66A1 and 66A2 of the pressing tool 60 and aligning the second end 40B of the busbar 40 with the second protrusions 66B1 and 66B2 of the pressing tool 60, with the allowable portions 40C of the busbar 40 accommodated in the recesses 68 of the pressing tool 60. The manufacturing method of the battery pack 20 also includes a pressure applying step (step S14) of applying pressure to the pressing tool 60 and the fixing tool 50 in directions toward each other, with the first end 40A of the busbar 40 set in the pressing tool 60 aligned with the first tip 30A as the tip of the first electrode tab 30 set in the fixing tool 50 and the second end 40B of the busbar 40 aligned with the second tip 32A as the tip of the second electrode tab 32. The manufacturing method of the battery pack 20 includes a welding process (step S16) in which laser light 82 is irradiated from each of the first openings 64A1, 64A2 and second openings 64B1, 64B2 of the clamp 60 toward the first end 40A and the second end 40B, thereby welding the first end 40A to the first electrode tab 30 and welding the second end 40B to the second electrode tab 32.

[0100] Even with this method of manufacturing the battery pack 20, it is possible to achieve the same effects as those described above.

[0101] In the method for manufacturing the battery pack 20 of this embodiment, each of the secondary batteries 22A, 22B is a pouch type.

[0102] In this manufacturing method of the battery pack 20, the target secondary batteries 22A, 22B are pouch-type batteries, and compared to metal can-type secondary batteries, expansion and contraction during charging and discharging, for example, are more likely to affect the extension positions of the electrode tabs 30, 32. However, this manufacturing method of the battery pack 20 makes it possible to manufacture the battery pack 20 using a bus bar 40 that allows the electrode tabs 30, 32 to move relative to each other.

[0103] Therefore, the manufactured battery pack 20 can maintain the connection state of the secondary batteries 22A, 22B even if the extending positions of the electrode tabs 30, 32 are displaced during use.

[0104] The above describes the embodiments and modifications of the present invention, but the above embodiments and modifications merely illustrate some of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments and modifications.

[0105] Although the allowable portion 40C of the bus bar 40 accommodated in the recess 68 of the welding jig 10 in the above-described embodiment and each modified example has the first extending portion 44A, the second extending portion 44B, and the connecting portion 44C, the allowable portion 40C is not limited to this shape. For example, the connecting portion 44C may have a bellows shape, a wave shape, or an arc shape. Furthermore, the bus bar 40 may have a bellows shape, a wave shape, or an arc shape between the first extending portion 44A and the second extending portion 44B, protruding to one side of the imaginary line K, to form the allowable portion 40C.

[0106] Although the battery pack 20 of the present embodiment and each of the modified examples has been described above as being used in an electric vehicle, the present invention is not limited to this. For example, the battery pack 20 may be installed in a series hybrid vehicle in which a motor is driven by electric power generated by an engine.

[0107] Furthermore, the battery pack 20 is not limited to being used in automobiles, but may also be used for other purposes.

Claims

1. When connecting a first electrode tab extending from one secondary battery and a second electrode tab extending from another secondary battery using a bus bar having an allowance portion that connects the first end and the second end while allowing relative movement between them, a welding jig used when welding the first end to the first electrode tab and the second end to the second electrode tab, the welding jig comprising: a fixture having a through hole for inserting intermediate portions of the first electrode tab and the second electrode tab and a support surface that extends along and supports the tip ends extending from the intermediate portions; and a presser on which the bus bar is set, the presser having a first opening for welding the first end, a second opening for welding the second end, a recess capable of accommodating the allowance portion, a first protrusion protruding toward the first end, and a second protrusion protruding toward the second end. a pressure applying mechanism that applies pressure in directions in which the presser tool and the fastener tool approach each other while aligning the first end and the second end of the bus bar set in the presser tool with the tip end of the first electrode tab and the tip end of the second electrode tab set in the fastener tool.

2. A welding jig as claimed in claim 1, wherein the allowable portion of the bus bar is formed by a convex portion protruding to one side of an imaginary straight line connecting the first end and the second end, and the convex portion has a first extending portion extending from the first end to the one side, a second extending portion extending from the second end to the one side, and a connecting portion connecting the tip of the first extending portion to the tip of the second extending portion, and the recess of the clamp is formed as a groove that can accommodate the allowable portion of the bus bar in a clamped state.

3. A welding jig as claimed in claim 1, wherein the passage hole of the fixture is configured to include a first slit into which the first electrode tab is inserted and a second slit into which the second electrode tab is inserted, and ends of the first slit and the second slit open to the side surface of the fixture.

4. A welding jig as claimed in claim 1, wherein the first opening and the second opening are formed in an elongated shape, and the first convex portion and the second convex portion extend along the first opening and the second opening.

5. A welding jig according to claim 4, wherein the first convex portion and the second convex portion have a cross-sectional shape that tapers toward the tip side.

6. A welding jig according to claim 4, wherein the first convex portion and the second convex portion have a cross-sectional shape that bulges in an arc shape.

7. A welding jig as set forth in claim 1, wherein the first convex portion and the second convex portion are in the shape of a quadrangular pyramid with the tip side as the upper base.

8. A method for manufacturing a battery pack using a welding jig according to any one of claims 1 to 7, comprising: an electrode tab setting step of setting the first electrode tab and the second electrode tab on the fixing device with the intermediate portions of the first electrode tab and the second electrode tab inserted into the through holes of the fixing device and the tip portions extending from the intermediate portions positioned along the support surface; a bus bar setting step of setting the bus bar on the pressing device by aligning the first end of the bus bar with the first convex portion of the pressing device and the second end of the bus bar with the second convex portion of the pressing device, with the allowable portion of the bus bar housed in the recess of the pressing device; and a pressure application step of applying pressure in a direction that brings the pressing device and the fixing device closer together with the first end of the bus bar set on the pressing device aligned with the tip portion of the first electrode tab set on the fixing device and the second end of the bus bar aligned with the tip portion of the second electrode tab, a welding step of irradiating a laser beam from the first opening and the second opening of the pressing tool toward the first end and the second end to weld the first end to the first electrode tab and weld the second end to the second electrode tab.

9. A method for manufacturing a battery pack according to claim 8, wherein the secondary battery is a pouch type.

Images