Battery stack

Abstract

To provide a battery stack capable of suppressing stacking displacement of battery cells even when impact is applied to a restraining member.SOLUTION: A battery stack includes a plurality of battery cells stacked in a predetermined direction and a restraining member that applies a restraining force to each battery cell such that the reaction force from each battery cell is in a predetermined direction. Each battery cell has a main surface whose normal direction is in the predetermined direction and to which the restraining force acts, and a side surface that is perpendicular to the main surface and faces a first direction. The restraining member extends in the predetermined direction along each side surface. The restraining member has first and second portions that are spaced apart from each other in the predetermined direction, and a third portion that extends in the predetermined direction and is connected to the first and second portions. The third portion is pulled in the predetermined direction by the first and second portions. When an external force acts in a second direction opposite to the first direction, the third portion is displaced in the second direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a battery stack. [Background technology]

[0002] Conventionally, battery stacks including multiple battery cells stacked in a predetermined direction are known. International Publication No. 2020 / 027120 (Patent Document 1) discloses, as an example of such a battery stack, a battery module including an assembly of multiple batteries (battery cells), a pair of end plates, and a pair of restraining members. The restraining member has a rectangular planar portion extending parallel to the short side of the battery. The planar portion is provided with an opening that exposes the short side of the battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 027120 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, when an impact (side impact load) is applied to the flat surface of the restraining member, the flat surface deforms toward the battery, which may cause stacking misalignment of the batteries.

[0005] The present disclosure provides a battery stack that can suppress stacking displacement of battery cells even when an impact is applied to a restraining member. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, a battery stack includes a plurality of battery cells stacked in a predetermined direction and a restraining member that applies a restraining force to each battery cell so that a reaction force from each battery cell is directed in a predetermined direction. Each battery cell has a main surface whose normal direction is in a predetermined direction and to which the restraining force acts, and a side surface that is perpendicular to the main surface and faces a first direction. The restraining member extends in the predetermined direction along each side surface. The restraining member has first and second portions spaced apart from each other in the predetermined direction, and a third portion that extends in the predetermined direction and is connected to the first and second portions. The third portion is pulled in the predetermined direction by the first and second portions. When an external force acts in a second direction opposite to the first direction, the third portion is displaced in the second direction.

[0007] According to the above configuration, when an external force due to an impact is applied to the third portion in the second direction, the third portion is displaced in the second direction. Because the second direction is perpendicular to the predetermined direction, when the third portion is displaced in the second direction, the length of the third portion along the predetermined direction is shortened. Therefore, a force based on the displacement of the third portion in the second direction acts on the first portion in a direction toward the second portion. Similarly, a force based on the displacement of the third portion in the second direction acts on the second portion in a direction toward the first portion. Therefore, when an external force is applied to the third portion in the second direction, the restraining force increases. Therefore, even when an impact is applied to the restraining member, stacking misalignment of the battery cells can be suppressed.

[0008] The third part is a wire or a movable plate. According to the above configuration, when an external force due to an impact is applied to the third portion in the second direction, the third portion can be displaced in the second direction. [Effects of the Invention]

[0009] According to the present disclosure, even if an impact is applied to the restraining member, it is possible to prevent stacking displacement of the battery cells. [Brief explanation of the drawings]

[0010] [Figure 1] 3A and 3B are diagrams for explaining the arrangement and configuration of a battery stack. [Figure 2] FIG. 2 is a diagram showing state transitions from FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. The names and functions of the components are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0012] The battery stack described below is mounted on electric vehicles such as hybrid vehicles that can run using at least one of the power of a motor and an engine, and electric vehicles that run using driving force obtained from electrical energy.

[0013] In the following, the vehicle longitudinal direction will also be referred to as the "DL direction," and the vehicle width direction will also be referred to as the "DW direction." The direction from rear to front in the vehicle longitudinal direction will also be referred to as the "Fr direction," the direction from front to rear will also be referred to as the "Re direction," the direction from left to right in the vehicle width direction will also be referred to as the "RH direction," and the direction from right to left will also be referred to as the "LH direction." The front, rear, right, and left sides will also be referred to as the "Fr side," "Re side," "RH side," and "LH side," respectively.

[0014] Fig. 1 is a diagram illustrating the arrangement and configuration of a battery stack. As shown in Fig. 1, the battery stack 1 is provided between a pair of cross members (400A, 400B) in the DL direction. The cross members 400A, 400B can improve the rigidity and strength of the vehicle (more specifically, the vehicle body).

[0015] The cross member 400A is located on the Fr side of the battery stack 1. The cross member 400B is located on the Re side of the battery stack 1. The cross member 400A has a protrusion 401A that protrudes toward the battery stack 1. The cross member 400B has a protrusion 401B that protrudes toward the battery stack 1. In this example, the protrusions 401A and 401B are ribs.

[0016] The battery stack 1 includes a cell stack 10, a pair of restraining members (20A, 20B), and a pair of end plates (30A, 30B). In this example, the pair of restraining members (20A, 20B) are also referred to as restraining bands.

[0017] The cell stack 10 has a plurality of battery cells 100 stacked in the DW direction. Each battery cell 100 has main surfaces 111 and 112 and side surfaces 113, 114, and 115. Each side surface 113, 114, and 115 is perpendicular to the main surface 111 and the main surface 112.

[0018] The main surface 111 is the surface on the RH side. The main surface 111 faces in the RH direction. The main surface 112 is the surface opposite to the main surface 111. The main surface 112 is the surface on the LH side. The main surface 112 faces in the LH direction. Of two consecutive battery cells 100, one main surface 111 is in contact with the other main surface 112. The normal direction of the main surfaces 111, 112 is the DW direction.

[0019] Side surface 113 is the surface on the Fr side. Side surface 113 faces in the Fr direction. Side surface 114 is the surface opposite side surface 113. Side surface 114 is the surface on the Re side. Side surface 114 faces in the Re direction. Side surface 115 is the surface on the upper side of the vehicle. Each battery cell 100 further has a side surface (not shown) opposite side surface 115 (surface on the lower side of the vehicle).

[0020] In this example, the side surfaces 113 and 114 are short side surfaces of the battery cell 100. The side surface 115 and the surface opposite to the side surface 115 are long side surfaces of the battery cell 100. The normal direction to the side surfaces 113 and 114 is the DL direction. The normal direction to the side surface 115 and the surface opposite to the side surface 115 is the vertical direction.

[0021] Each of the restraining members 20A, 20B is an elongated member with the DW direction as its longitudinal direction. The restraining members 20A and 20B are arranged to face each other in the DL direction. The restraining member 20A extends in the DW direction along multiple side surfaces 113. The restraining member 20B extends in the DW direction along multiple side surfaces 114. The pair of restraining members (20A, 20B) applies a restraining force to each battery cell 100 in the DW direction. More specifically, each of the restraining members 20A, 20B applies a restraining force to the main surfaces 111, 112 of each battery cell 100. Each of the restraining members 20A, 20B has end portions 210, 220 spaced apart in the DW direction.

[0022] The end plate 30A is in contact with the battery cell 100 closest to the left side among the multiple battery cells 100. The end plate 30B is in contact with the battery cell 100 closest to the right side among the multiple battery cells 100. Each end plate 30A, 30B is connected to each restraining member 20A, 20B by a connecting member such as a screw or a bolt. More specifically, each end plate 30A, 30B is connected to each end 210, 220 of each restraining member 20A, 20B.

[0023] Each battery cell 100 is sandwiched and fixed in position between end plates 30A and 30B in the DW direction. A constraining force 601 in the RH direction and a constraining force 602 in the LH direction act on the cell stack 10 by the pair of constraining members (20A, 20B) and the pair of end plates (30A, 30B). More specifically, the constraining forces 601, 602 act on each battery cell 100 such that a reaction force 700 from each battery cell 100 is in the DW direction. Each battery cell 100 is located between the constraining member 20A and the constraining member 20B in the DL direction.

[0024] The restraining member 20A and the restraining member 20B have the same configuration, except that the orientation (posture) of the restraining member 20A and the restraining member 20B is different.

[0025] Each of the restraining members 20A, 20B has a first plate portion 21 and a second plate portion 22 spaced apart from each other in the DW direction. The first plate portion 21 and the second plate portion 22 extend in the DW direction. Each of the restraining members 20A, 20B further has a wire 23 that extends in the DW direction and is connected to the first plate portion 21 and the second plate portion 22. In this example, the wire 23 is made of metal.

[0026] Specifically, each of the restraining members 20A, 20B has, in the RH direction, a first plate portion 21, a wire 23, and a second plate portion 22, in this order. The first plate portion 21 includes an end portion 210. The second plate portion 22 includes an end portion 220.

[0027] The wire 23 is pulled in the DW direction by the first plate portion 21 and the second plate portion 22. Tension is applied to the wire 23. More specifically, the above-mentioned reaction force 700 applies to the wire 23 a pulling force in the LH direction and a pulling force in the RH direction.

[0028] With tension applied in the DW direction, one end of the wire 23 in the DW direction is connected to the first plate portion 21, and the other end of the wire 23 in the DW direction is connected to the second plate portion 22. Specifically, each wire 23 is fixed to the first plate portion 21 and the second plate portion 22 so that the distance in the DL direction between the wire 23 of the restraining member 20A and the wire 23 of the restraining member 20B is minimized.

[0029] When an external force acts in the direction of Re, wire 23 of restraint member 20A is displaced in the direction of Re. Specifically, when an external force acts in the direction of Re between first plate portion 21 and second plate portion 22, wire 23 of restraint member 20A is displaced in the direction of Re.

[0030] Similarly, when an external force acts in the Fr direction, wire 23 of restraint member 20B is displaced in the Fr direction. More specifically, when an external force acts in the Fr direction between first plate portion 21 and second plate portion 22, wire 23 of restraint member 20B is displaced in the Fr direction.

[0031] The number of wires 23 in each of restraining members 20A and 20B may be one or more. In the case of a plurality of wires 23, the wires 23 may be installed in parallel at positions spaced apart from each other in the vertical direction, for example, at equal intervals.

[0032] The first plate portion 21 is an example of a "first portion" in the present disclosure. The second plate portion 22 is an example of a "second portion" in the present disclosure. The wire 23 is an example of a "third portion" in the present disclosure.

[0033] In this example, the convex portion 401A of the cross member 400A is in contact with the wire 23 of the restraint member 20A. Specifically, the convex portion 401A is in contact with the center of the wire 23 in the DW direction. More specifically, the tip surface of the convex portion 401A is in contact with the wire 23 to an extent that the wire 23 does not bend in the Re direction. The convex portion 401B of the cross member 400B is in contact with the wire 23 of the restraint member 20B. Specifically, the convex portion 401B is in contact with the center of the wire 23 in the DW direction. More specifically, the tip surface of the convex portion 401B is in contact with the wire 23 to an extent that the wire 23 does not bend in the Fr direction.

[0034] Note that the present invention is not limited to the above, and convex portion 401A may be in contact with wire 23 of restraint member 20A so that the amount of bending of wire 23 is a predetermined amount or less. Similarly, convex portion 401B may be in contact with wire 23 of restraint member 20B so that the amount of bending of wire 23 is a predetermined amount or less. Alternatively, convex portion 401A may be spaced apart from wire 23 of restraint member 20A in the DL direction. That is, there may be a gap between the tip surface of convex portion 401A and wire 23 of restraint member 20A. Similarly, convex portion 401B may be spaced apart from wire 23 of restraint member 20B in the DL direction. That is, there may be a gap between the tip surface of convex portion 401B and wire 23 of restraint member 20B.

[0035] FIG. 2 is a diagram showing the state transition from FIG. 1. More specifically, FIG. 2 shows a case where an impact is applied to the vehicle in the longitudinal direction due to a collision. In this case, as shown in FIG. 2, an impact force 801 is applied to cross member 400A in the direction Re, and an impact force 802 is applied to cross member 400B in the direction Fr. Forces 801 and 802 represent impact stresses.

[0036] When force 801 is applied to cross member 400A, convex portion 401A is displaced in the direction of Re. In this example, force 801 is applied to a portion of cross member 400A facing wire 23 (more specifically, near convex portion 401A). When convex portion 401A is displaced in the direction of Re, convex portion 401A pushes wire 23 of restraint member 20A in the direction of Re. When wire 23 of restraint member 20A is pushed in the direction of Re, wire 23 of restraint member 20A is displaced in the direction of Re. The central portion of wire 23 that is in contact with convex portion 401A is displaced the most.

[0037] Because the direction of Re is perpendicular to the DW direction, when the wire 23 of the restraint member 20A is displaced in the direction of Re, the length of the wire 23 of the restraint member 20A along the DW direction becomes shorter. Therefore, when the wire 23 of the restraint member 20A is displaced in the direction of Re, the wire 23 of the restraint member 20A applies a force to the first plate portion 21 of the restraint member 20A in the direction of arrow 911 (toward the second plate portion 22), and also applies a force to the second plate portion 22 of the restraint member 20A in the direction of arrow 912 (toward the first plate portion 21). As a result, the first plate portion 21 of the restraint member 20A and the second plate portion 22 of the restraint member 20A move slightly closer to each other.

[0038] When force 802 is applied to cross member 400B, convex portion 401B is displaced in the Fr direction. In this example, force 802 is applied to a portion of cross member 400B facing wire 23 (more specifically, near convex portion 401B). When convex portion 401B is displaced in the Fr direction, convex portion 401B pushes wire 23 of restraint member 20B in the Fr direction. When wire 23 of restraint member 20B is pushed in the Fr direction, wire 23 of restraint member 20B is displaced in the Fr direction. The central portion of wire 23 that is in contact with convex portion 401B is displaced the most.

[0039] Because the direction of Fr is perpendicular to the DW direction, when the wire 23 of the restraint member 20B is displaced in the direction of Fr, the length of the wire 23 of the restraint member 20B along the DW direction becomes shorter. Therefore, when the wire 23 of the restraint member 20B is displaced in the direction of Fr, the wire 23 of the restraint member 20B applies a force to the first plate portion 21 of the restraint member 20B in the direction of arrow 921 (toward the second plate portion 22), and also applies a force to the second plate portion 22 of the restraint member 20B in the direction of arrow 922 (toward the first plate portion 21). As a result, the first plate portion 21 of the restraint member 20B and the second plate portion 22 of the restraint member 20B move slightly closer to each other.

[0040] The forces in the directions of the arrows 911 and 912 resulting from the displacement of one wire 23 in the Re direction and the forces in the directions of the marks 921 and 922 resulting from the displacement of the other wire 23 in the Fr direction increase the force pulling the end plate 30A in the RH direction and also increase the force pulling the end plate 30B in the LH direction. This increases the restraining force in the DW direction on the cell stack 10. Specifically, the restraining forces 601 and 602 of each battery cell 100 increase.

[0041] In this way, when an impact is applied to the vehicle in the longitudinal direction, the battery stack 1 increases the restraining force applied to each battery cell 100 due to the displacement of the wire 23 described above, thereby suppressing stacking misalignment (positional misalignment in the DL direction) of each battery cell 100 within the battery stack 1.

[0042] Furthermore, even if an impact is applied to the vehicle in the longitudinal direction, by configuring the restraint members 20A, 20B so that each wire 23 does not come into contact with the side surfaces 113, 114 of the battery cells 100, damage caused by the protrusions 401A, 401B and the wires 23 to the cell stack 10 (each battery cell 100) can be eliminated.

[0043] <Modification> (1) In the above, wire 23 is used as the part (third part) that is displaced when an impact is applied, but this is not limiting. As another example of the third part, a movable plate that is deformed in the same way as wire 23 due to the above-described displacement of convex portions 401A, 401B when the above-described impact is applied to the vehicle may be used.

[0044] Such a movable plate may be, for example, a plate that is deflected and deformed in the DL direction, but the movable plate is not limited to this and does not necessarily have to return to its original shape after deformation.

[0045] The movable plate does not necessarily have to deform. For example, the movable plate may be configured such that connecting members (e.g., wires) for connecting the first plate portion 21 and the second plate portion 22 are provided at both ends of the movable plate, and the convex portions 401A and 401B come into contact with the main surface of the movable plate when the above-mentioned impact is applied. In this case, the entire movable plate moves in the DL direction.

[0046] (2) The third section may be, for example, a member consisting of a plurality of element members (plate members, link members) connected in the DW direction and a connecting member (pin, etc.) connecting adjacent element members and extending in the vertical direction. The third section may also be a chain-like member.

[0047] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the scope of the claims, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0048] 1 battery stack, 10 cell laminate, 20A, 20B restraint member, 21 first plate portion, 22 second plate portion, 23 wire, 30A, 30B end plate, 100 battery cell, 111, 112 main surface, 113, 114, 115 side, 210, 220 end, 400A, 400B cross member, 401A, 401B convex portion.

Claims

1. a plurality of battery cells stacked in a predetermined direction; a restraining member that applies a restraining force to each of the battery cells so that a reaction force from each of the battery cells is in the predetermined direction; Each of the battery cells is a main surface whose normal direction is the predetermined direction and on which the binding force acts; a side surface perpendicular to the main surface and facing in a first direction; The restraining member is extending in the predetermined direction along each of the sides; a first portion and a second portion spaced apart from each other in the predetermined direction, and a third portion extending in the predetermined direction and connected to the first portion and the second portion; the third portion is pulled in the predetermined direction by the first portion and the second portion, The battery stack, wherein the third portion is displaced in the second direction when an external force acts in the second direction opposite to the first direction.

2. The battery stack according to claim 1 , wherein the third portion is a wire or a movable plate.

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