Manufacturing method of battery pack

Abstract

To appropriately bind a lamination body.SOLUTION: A manufacturing method of a battery pack 1, includes: a compression step of compressing a battery stack 5 in which battery cells 10 are laminated in a lamination direction D; a position deviation measurement step of measuring a position deviation amount H from a regulation position of the battery stack 5 generated by compression; a bolt length selection step of selecting a bolt length on the basis of the position deviation amount H; and a depression step of bringing one end surface of the battery stack 5 in the lamination direction D into direct contact with a case 40, and depressing the other end surface of the battery stack 5 in the lamination direction D to the lamination direction D by using a bolt 60 of the selected bolt length.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a battery pack. [Background technology]

[0002] 2. Description of the Related Art There is known a battery pack in which a laminate is compressed in the lamination direction and housed in a case (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a battery pack in which the tip of a pressure bolt attached to one end side wall of a storage case abuts against one end of a battery stack, and the battery stack is sandwiched between the other end side wall of the storage case and the tip of the pressure bolt.

[0004] In the battery pack, it is preferable to appropriately restrain the laminate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-102331 A Summary of the Invention [Problem to be solved by the invention]

[0006] In consideration of the above, an object of the present invention is to appropriately restrain a laminate. [Means for solving the problem]

[0007] A manufacturing method for a battery pack of a first aspect of the present invention includes a compression step of compressing a stack of stacked battery cells in a stacking direction; a misalignment measurement step of measuring an amount of misalignment of the stack from a specified position caused by compression; a bolt length selection step of selecting a bolt length based on the amount of misalignment; and a pressing step of directly or indirectly contacting one end face of the stack in the stacking direction with a case and using a bolt of the selected bolt length to press the other end face of the stack in the stacking direction.

[0008] In a battery pack manufacturing method of a second aspect of the present invention, in the battery pack manufacturing method of the first aspect of the present invention, in the bolt length selection step, a bolt having a longer bolt length than the bolts fastened on the opposite side to the misalignment direction caused by compression is selected from among the multiple bolts as the bolt to be fastened on the side of the misalignment direction from a specified position of the stacked body caused by compression.

[0009] A third aspect of the present invention is a method for manufacturing a battery pack according to the first or second aspect of the present invention, and the greater the amount of misalignment, the greater the difference between the bolt length of the bolt fastened on the side of the misalignment direction and the bolt length of the bolt fastened on the side opposite to the misalignment direction is made.

[0010] A fourth aspect of the present invention is a method for manufacturing a battery pack according to any one of the first to third aspects of the present invention, wherein a side panel attached to the case is arranged on the other end face in the stacking direction of the stack, and in the pressing process, the bolt held by the case presses the other end face in the stacking direction of the stack through the side panel. Effect of the Invention

[0011] In the battery pack manufacturing method of the first aspect of the present invention, one end face of the stack in the stacking direction is brought into direct or indirect contact with the case, and the other end face of the stack in the stacking direction is pressed in the stacking direction using a bolt of a selected bolt length, so that the stack is restrained by the bolt of a bolt length corresponding to the length of the stack in the stacking direction. Therefore, the stack can be appropriately restrained.

[0012] In the battery pack manufacturing method according to the second aspect of the present invention, a bolt having a longer bolt length than a bolt fastened on the side opposite to the misalignment direction of the stack caused by compression is selected from among the bolts, so that the bolt having the longer bolt length is fastened on the side where the stack has been misaligned. Therefore, the restraint load of the stack on the side where the misalignment has occurred is made stronger than the restraint load of the stack on the side opposite to the side where the misalignment has occurred. As a result, an appropriate restraint load can be applied to the stack to correct the misalignment.

[0013] In the manufacturing method of the battery pack according to the third aspect of the present invention, the greater the amount of misalignment, the greater the difference between the length of the bolt fastened on the side of the misalignment and the length of the bolt fastened on the opposite side to the misalignment, thereby selecting a bolt having a length appropriate to the amount of misalignment. Therefore, an appropriate restraining load can be applied to the stack so as to correct the misalignment.

[0014] In the battery pack manufacturing method according to the fourth aspect of the present invention, the bolts held by the case press the other end face of the stack in the stacking direction through the side panel, changing the posture of the side panel pressing the stack, so that an appropriate restraining load can be applied to the stack by the wide surface of the side panel. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is an exploded perspective view showing the battery pack according to the embodiment. [Diagram 2] FIG. 2 is an exploded perspective view showing a laminate according to an embodiment. [Diagram 3] FIG. 2 is a cross-sectional view showing a schematic view of the battery pack according to the embodiment, showing the cross section taken along line AA in FIG. [Figure 4] 4 is a flow diagram showing a manufacturing method of a battery pack according to an embodiment. [Diagram 5] 2 is a cross-sectional view showing a schematic diagram of a method for manufacturing a battery pack according to the embodiment, showing a cross section taken along line AA in FIG. [Figure 6] 2 is a cross-sectional view showing a schematic diagram of a method for manufacturing a battery pack according to the embodiment, showing a cross section taken along line AA in FIG. [Figure 7] 2 is a cross-sectional view showing a schematic diagram of a method for manufacturing a battery pack according to the embodiment, showing a cross section taken along line BB in FIG. [Figure 8] 2 is a cross-sectional view showing a schematic diagram of a method for manufacturing a battery pack according to the embodiment, showing a cross section taken along line BB in FIG. [Figure 9] 11 is a table showing the relationship between the amount of misalignment of the battery stack and the bolt length according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, a battery pack according to an embodiment will be described with reference to the drawings. The battery pack according to the embodiment will be described as an example of a lithium ion secondary battery used as an in-vehicle power source for an electric vehicle, a hybrid vehicle, or the like. In each drawing, the arrow UP indicates the upper side in the vertical direction of the battery pack, the arrow FR indicates the front side in the front-rear direction of the battery pack, the arrow LH indicates the left side in the left-right direction of the battery pack, and the arrow D indicates the stacking direction D of the battery stack. In the embodiment, the stacking direction D of the battery stack coincides with the front-rear direction of the battery pack.

[0017] [Battery pack 1 configuration] As shown in FIG. 1, the battery pack 1 includes a battery stack 5 as a laminate, a case 40 that houses the battery stack 5, a side panel 30 that is disposed in the case 40, and a bolt 60 that presses the side panel 30.

[0018] (Battery stack 5) 1 and 2, the battery stack 5 includes a plurality of battery cells (single cells) 10, a plurality of intermediate members 20 arranged in contact with the wide faces of the battery cells 10, a pressed plate 24 arranged on the rear end side of the battery cells 10 in the stacking direction D, and a bus bar 15 that electrically connects the battery cells 10. In the battery stack 5, the battery cells 10 and the intermediate members 20 are arranged alternately in the stacking direction D.

[0019] <Battery cell 10> 2, the battery cell 10 is formed in a rectangular plate shape with the plate thickness direction being the front-rear direction. The battery cell 10 has two electrode terminals 12 on its top surface 10A. One of the two electrode terminals 12 is a positive terminal and the other is a negative terminal. Note that the battery cell 10 may have multiple pole groups arranged therein.

[0020] The battery case of the battery cell 10 is made of, for example, aluminum, and contains a wound body and an electrolyte therein.

[0021] <Intermediate member 20> The intermediate member 20 is made of, for example, insulating resin. This suppresses heat transfer between the battery cells 10 and insulates the battery cells 10 from each other. The intermediate member 20 may be formed with comb-like ribs for forming air passages between the intermediate member 20 and the battery cells 10.

[0022] As shown in FIG. 1, the intermediate member 20 includes a spacer 21 and an end plate 22.

[0023] The spacers 21 are disposed between the battery cells 10 in the stacking direction D. The spacers 21 are formed in the shape of a rectangular plate with the plate thickness direction extending in the front-rear direction.

[0024] 1, the end plates 22 are disposed at both ends of the battery stack 5 in the stacking direction D. The end plates 22 are formed in a rectangular plate shape with the plate thickness direction extending in the front-rear direction.

[0025] <Pressure plate 24> 1 and 2, the pressed plate 24 is formed in a rectangular plate shape with the plate thickness direction being in the front-rear direction. The pressed plate 24 is attached to the wide surface of the end plate 22 on the rear end side of the battery stack 5. The pressed plate 24 is made of, for example, metal, and has a strength sufficient to withstand pressure applied by a pressing jig 90 (see FIG. 6), which will be described later, when compressing the battery stack 5.

[0026] <Busbar 15> 2, the busbar 15 is formed, for example, in a rectangular plate shape with its plate thickness direction extending in the up-down direction in the stacking direction D. The busbar 15 electrically connects the electrode terminals 12 of adjacent battery cells 10.

[0027] (Case 40) 1, the case 40 is formed by, for example, aluminum die casting. The case 40 is formed by a bottom plate 41, side plates 42, and a front plate 43 in the shape of a rectangular box whose top and rear are open.

[0028] A pair of rear plates 44 are formed at the rear end of the case 40, extending from the rear ends of the side plates 42 toward the inside of the case 40. The rear plates 44 are formed in a plate shape with the plate thickness direction being the front-to-rear direction. The pair of rear plates 44 are arranged with a gap that allows the insertion of a pressing jig 90 (see FIG. 6) used in the compression process described later.

[0029] Two through holes 44A are formed in the rear plate 44 penetrating in the front-rear direction. The through holes 44A are arranged next to each other at an interval in the up-down direction. A bolt 60 serving as a fastener, which will be described later, is attached to the through hole 44A. The through hole 44A may be formed by embedding an insert nut into the rear plate 44 that fits with the bolt 60.

[0030] The side panel 30 is arranged in front of the rear plate 44 in the front-rear direction. The space surrounded by the bottom plate 41, the side plate 42, the front plate 43, and the side panel 30 forms an accommodation space S in which the battery stack 5 is accommodated.

[0031] (Side Panel 30) 1, the side panel 30 is adapted to come into contact with a rear end, in the stacking direction D, of the battery stack 5 arranged in the accommodation space S in a state compressed in the stacking direction D. The side panel 30 is detachably provided on the case 40. The side panel 30 is formed with a first portion 31 and a second portion 32 so as to have an L-shaped cross section.

[0032] The first portion 31 is formed in a rectangular plate shape with the plate thickness direction being the front-rear direction. A notch portion 31A that is open downward is formed in the first portion 31. The notch portion 31A is formed in a portion that is pressed by a pressing jig 90 (see FIG. 6) described later.

[0033] The second portion 32 is formed in a rectangular plate shape with its thickness direction in the up-down direction. The second portion 32 is a portion that is pressed or gripped when attaching or detaching the side panel 30 to the case 40.

[0034] 3, the battery stack 5 is housed in the case 40 in a state compressed in the stacking direction D. The battery stack 5 is housed in the case 40 in a state compressed in the stacking direction D by the front panel 43 and the side panel 30.

[0035] The side panel 30 is disposed at a position where the battery stack 5 is compressed in the stacking direction D by the side panel 30 and the front plate 43 of the case 40 .

[0036] (Bolt 60) The bolt 60 is detachably attached to a through hole 44A formed in the rear plate 44. The bolt 60 is configured to be detachably attached to the rear plate 44 in the stacking direction D. The tip of the bolt 60 has a length such that the tip of the bolt 60 protrudes from the rear plate 44 when the bolt is tightened.

[0037] The bolts 60 include a first bolt 61 arranged at a position corresponding to the upper side of the battery stack 5 , and a second bolt 62 arranged at a position corresponding to the lower side of the battery stack 5 .

[0038] Thereby, when the bolt 60 is tightened, the tip of the bolt 60 presses the side panel 30 in the stacking direction D. The side panel 30 is gradually pressed in the stacking direction D by the bolt 60.

[0039] [Manufacturing method of battery pack 1] As shown in FIG. 4, the battery pack 1 is manufactured through a stacking process (step S1), a compression process (step S2), a positional deviation measuring process (step S3), a bolt length selection process (step S4), a side panel arrangement process (step S5), and a pressing process (step S6).

[0040] (Lamination process) 5 , in the stacking process of step S1, battery cells 10 and intermediate members 20 are arranged alternately in stacking direction D to form a battery stack 5. In addition, a pressed plate 24 is arranged on the rear end side of the battery cells 10 in the stacking direction D. Then, the battery stack 5 is arranged in a case 40.

[0041] (Compression process) In the compression process of step S2, as shown in Fig. 6, a pressing tool 90 presses the pressed plate 24 in the stacking direction D to compress the battery stack 5 in the stacking direction D. When the battery stack 5 is compressed in the stacking direction D, the battery cells 10 and intermediate members 20 constituting the battery stack 5 may be displaced in the vertical or horizontal direction from their specified positions. Here, a case where the battery stack 5 is displaced due to undulation will be described.

[0042] (Positional deviation measurement process) In the misalignment measurement process of step S3, the misalignment amount H of the battery stack 5 from a specified position caused by compression is measured. Specifically, for example, as shown in Fig. 6, a misalignment detector (not shown) measures the distance between the top surface of the intermediate member 20 at the rear end in the stacking direction D and the top surface of the component part of the battery stack 5 that protrudes most upward as the misalignment amount H.

[0043] The positional deviation detector may be an image sensor that detects the amount of positional deviation based on a camera image, a distance sensor, or the like.

[0044] (Bolt length selection process) In a bolt length selection process in step S4, the bolt length of the bolt 60 is selected based on the positional misalignment amount H. The bolt length of the bolt 60 is defined as the length by which the tip of the bolt 60 protrudes from the rear plate 44 when the bolt 60 is tightened.

[0045] Here, in the embodiment, the components of the battery stack 5 are displaced upward from a specified position. In this case, the first bolt 61 is fastened to the upper side of the battery stack 5, which is the side in the direction of displacement of the battery stack 5 from the specified position. The second bolt 62 is fastened to the lower side of the battery stack 5, which is the side opposite to the direction of displacement of the battery stack 5 from the specified position.

[0046] The first bolt 61 fastened to the battery stack 5 on the side of the misalignment direction is selected to have a longer bolt length than the second bolt 62 fastened to the battery stack 5 on the side opposite to the misalignment direction.

[0047] 9, the larger the misalignment amount H, the larger the difference between the bolt length of the first bolt 61 fastened to the battery stack 5 on the side of the misalignment direction and the bolt length of the second bolt 62 fastened to the battery stack 5 on the side opposite the misalignment direction is selected. When the misalignment amount H is zero, the difference between the bolt length of the first bolt 61 and the bolt length of the second bolt 62 is selected to be zero.

[0048] The bolt length of the bolt 60 can be adjusted by changing the length of the bolt 60 under the neck or by changing the thickness of the washer sandwiched between the head of the bolt 60 and the rear plate 44.

[0049] (Side panel placement process) 7, in the side panel arrangement process of step S5, the side panel 30 is moved from above downward and inserted between the rear plate 44 of the case 40 and the other end face of the battery stack 5 in the stacking direction D, and arranged in the case 40. That is, the side panel 30 is arranged on the rear end side of the battery stack 5. Then, the pressure applied to the battery stack 5 by the pressing jig 90 is released.

[0050] (Pressing process) 8, in the pressing process of step S6, the first bolt 61 and the second bolt 62 having the bolt length selected in the bolt length selection process are inserted into the through hole 44A of the rear plate 44 and tightened. As a result, the tip of the first bolt 61 and the tip of the second bolt 62 press the rear end surface of the battery stack 5 in the stacking direction D through the side panel 30.

[0051] Here, the pressing force of the first bolt 61, which has a longer bolt length, is greater than the pressing force of the second bolt 62, which has a shorter bolt length. Therefore, the side panel 30 is tilted forward with the lower end as a fulcrum. As a result, the components of the battery stack 5 that had protruded upward are moved downward. Thus, the battery pack 1 in which the positional displacement of the battery stack 5 is suppressed is manufactured.

[0052] [Effect] Incidentally, the shape of the battery stack 5 may vary due to variations in the shapes of the components. Here, if the battery stack 5 is pressed in the stacking direction D by fastening it with bolts 60 of the same length, there is a problem in that the restraining load of the battery stack 5 varies, making it impossible to properly restrain the battery stack 5.

[0053] The manufacturing method of the battery pack 1 of the embodiment includes a compression process of compressing the battery stack 5, in which the battery cells 10 are stacked, in a stacking direction D, a positional deviation measurement process of measuring a positional deviation H from a specified position of the battery stack 5 caused by the compression, a bolt length selection process of selecting a bolt length based on the positional deviation H, and a pressing process of directly contacting one end face of the battery stack 5 in the stacking direction D with the case 40 and pressing the other end face of the battery stack 5 in the stacking direction D in the stacking direction D using a bolt 60 of the selected bolt length (see FIG. 3 ).

[0054] One end face of the battery stack 5 in the stacking direction D is brought into direct contact with the case 40, and the other end face of the battery stack 5 in the stacking direction D is pressed in the stacking direction D using a bolt 60 with a selected bolt length, whereby the battery stack 5 is restrained by the bolt 60 with a bolt length according to the length of the battery stack 5 in the stacking direction D. Therefore, the battery stack 5 can be appropriately restrained.

[0055] In the manufacturing method of the battery pack 1 of the embodiment, in the bolt length selection process, a first bolt 61 is selected from among the multiple bolts 60, which is fastened on the side of the positional deviation from a specified position of the battery stack 5 caused by compression, and has a longer bolt length than a second bolt 62 which is fastened on the side opposite the positional deviation (see Figure 6).

[0056] Among the multiple bolts 60, the first bolt 61 fastened on the side of the displacement of the battery stack 5 from the specified position caused by compression is selected to have a longer bolt length than the second bolt 62 fastened on the side opposite to the displacement direction, so that the first bolt 61 with the longer bolt length is fastened to the side of the battery stack 5 where the displacement has occurred. Therefore, the restraint load of the battery stack 5 on the side where the displacement has occurred is made stronger than the restraint load of the battery stack 5 on the side opposite to the side where the displacement has occurred. As a result, an appropriate restraint load can be applied to the battery stack 5 so as to correct the displacement.

[0057] In the manufacturing method of the battery pack 1 of the embodiment, the larger the amount of misalignment H, the greater the difference between the bolt length of the first bolt 61, which is fastened on the side of the misalignment direction, and the bolt length of the second bolt 62, which is fastened on the side opposite the misalignment direction, of the multiple bolts 60 (see Figure 9).

[0058] As the amount of misalignment H increases, the difference between the bolt length of the first bolt 61 fastened on the side of the misalignment direction and the bolt length of the second bolt 62 fastened on the side opposite to the direction of misalignment is increased, thereby selecting a bolt 60 having a bolt length according to the amount of misalignment H. Therefore, an appropriate restraining load can be applied to the battery stack 5 to correct the misalignment.

[0059] In the manufacturing method of the battery pack 1 of the embodiment, a side panel 30 attached to the case 40 is arranged on the other end surface of the battery stack 5 in the stacking direction D, and in the pressing process, a bolt 60 held in the case 40 presses the other end surface of the battery stack 5 in the stacking direction D through the side panel 30 (see FIG. 3).

[0060] The bolts 60 held by the case 40 press the other end face of the battery stack 5 in the stacking direction D through the side panel 30, changing the posture of the side panel 30 pressing against the battery stack 5. Therefore, an appropriate restraining load can be applied to the battery stack 5 by the wide surface of the side panel 30.

[0061] The manufacturing method of the battery pack of the present invention has been described above based on the embodiment. However, the specific configuration is not limited to this embodiment, and design changes and the like are permitted as long as they do not deviate from the gist of the invention according to each claim of the claims.

[0062] In the embodiment, an example is shown in which the components of the battery stack 5 are displaced upward from their specified positions. However, the present invention can also be applied to a case in which the components of the battery stack 5 are displaced rightward or leftward from their specified positions.

[0063] In the embodiment, an example has been shown in which the bolt length is adjusted by changing the length of the bolt 60. However, the bolt length may also be adjusted by using or not using a washer, changing the thickness of the washer, or the like.

[0064] In the embodiment, an example has been shown in which, when the bolt 60 is tightened, the tip of the bolt 60 presses the battery stack 5 via the side panel 30. However, when the bolt 60 is tightened, the tip of the bolt 60 may directly press the pressed plate 24 or the end plate 22.

[0065] In the embodiment, an example in which two bolts 60 are provided in the positional deviation direction has been shown, but the number of bolts is not limited to this embodiment, and may be one, or three or more.

[0066] In the embodiment, an example has been shown in which one battery stack 5 is housed in the case 40. However, the case may house two battery stacks 5 with an intermediate plate therebetween.

[0067] In the embodiment, an example has been shown in which the front end face of the battery stack 5 in the stacking direction D is in direct contact with the front plate 43 and the battery stack 5 is housed in the case 40 in a state compressed in the stacking direction D. However, the front end face of the battery stack 5 in the stacking direction D may be in indirect contact with the front plate 43 and the battery stack 5 may be housed in the case 40 in a state compressed in the stacking direction D.

[0068] In the embodiment, an example has been shown in which the side panel 30 is disposed on the rear end side of the battery stack 5, and the bolt 60 is inserted into the through hole 44A of the rear plate 44 and fastened after the pressure on the battery stack 5 by the pressing jig 90 is released. However, the bolt 60 may be inserted into the through hole 44A of the rear plate 44 and fastened before the pressure on the battery stack 5 by the pressing jig 90 is released.

[0069] In the embodiment, the battery pack manufacturing method is an example of a lithium ion secondary battery manufacturing method, but the battery pack manufacturing method can be applied to a battery pack in which a battery stack is compressed in the stacking direction D and housed in a case. [Explanation of symbols]

[0070] 1 Battery pack 5 Battery stack (an example of a laminate) 30 Side Panel 40 cases 60 Volts 61 First Bolt 62 Second Bolt D Stacking direction H Position deviation amount

Claims

1. a compression step of compressing the stack in which the battery cells are stacked in a stacking direction; a positional displacement measuring step of measuring a positional displacement amount from a specified position of the laminate caused by compression; a bolt length selection step of selecting a bolt length based on the positional misalignment amount; a pressing step of directly or indirectly contacting one end surface of the stack in the stacking direction with a case, and pressing the other end surface of the stack in the stacking direction with a bolt having the selected bolt length; A method for manufacturing a battery pack comprising:

2. In the bolt length selection step, a bolt having a longer bolt length than the bolts fastened on the side opposite to the positional deviation direction of the stack caused by compression is selected as the bolt fastened on the side of the stack caused by compression in the positional deviation direction from the specified position of the stack. A method for manufacturing the battery pack according to claim 1 .

3. The greater the amount of misalignment, the greater the difference between the bolt length of the bolt fastened in the direction of the misalignment and the bolt length of the bolt fastened on the opposite side to the direction of the misalignment. The method for manufacturing the battery pack according to claim 2 .

4. a side panel attached to the case is disposed on the other end surface of the stack in the stacking direction; In the pressing step, the bolt held by the case presses the other end surface of the stack in the stacking direction through the side panel. A method for manufacturing the battery pack according to claim 1 .

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