JP2019087446A - Battery pack - Google Patents

Abstract

To provide a battery pack in which end plates and side plates are securely fastened even if loads are applied to the end plates from a battery stack.SOLUTION: A battery pack 100 includes: a battery stack 20 in which multiple electric cells 10 are arranged in an X direction; end plates 30A, 30B disposed at both end parts of the battery stack 20; side plates 40A, 40B connecting the end plates 30A, 30B; and fastening members 50 which fasten the end plates 30A, 30B to the side plates 40A, 40B and apply restraint loads to a space between the end plates 30A, 30B. The multiple fastening members 50 which fasten the end plate 30A to the side plate 40A include: multiple first fastening members 51 arranged in a Y direction; and multiple second fastening members 52 which are arranged in the Y direction, disposed closer to the battery stack 20 side than the first fastening members 51, and offset relative to the first fastening members 51 in the Y direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a battery assembly including a battery stack in which a plurality of chargeable and dischargeable single batteries are electrically connected.

  In recent years, secondary batteries such as lithium ion secondary batteries are used as portable power sources such as personal computers and portable terminals, and power sources for driving vehicles such as electric vehicles (EV), hybrid vehicles (HV) and plug-in hybrid vehicles (PHV) Are preferably used.

  In a vehicle drive power source application, a secondary battery is generally used in the form of an assembled battery formed by connecting a plurality of single cells (battery cells) in order to achieve high output. In the assembled battery, a restraint load is applied in a direction perpendicular to the electrode surface in the unit cell in order to prevent positional deviation of the unit cell due to vibration, impact, etc. during traveling of the vehicle, battery characteristics, battery life, etc. There is a need to. For example, in Patent Document 1, a battery stack in which a plurality of unit cells are arranged in a predetermined direction, a pair of end plates disposed at both ends of the battery stack, and a pair of side plates connecting the pair of end plates And a plurality of fastening members for fastening the end plates and the side plates to apply a restraining load between the pair of end plates.

JP, 2011-175743, A

  By the way, in each unit cell of a battery stack, a unit cell may expand in the arrangement direction at the time of charge and discharge. This applies a load to the end plate from the battery stack. Here, the pair of end plates is fastened to the pair of side plates by a plurality of fastening members. When a load is applied to the end plate from the battery stack, a bending stress is generated in the fastening member in addition to the tensile stress. The bending stress may reduce the fastening force between the pair of end plates and the pair of side plates. Even when a load is applied from the battery stack to the end plates, it is necessary to securely fasten the pair of end plates and the side plates by the fastening members and apply a constraint load to the battery stack by the pair of end plates.

  This invention is made in view of this point, The objective is to provide the assembled battery by which the end plate and the side plate were firmly fastened, even if load is added to an end plate from a battery stack. I assume.

  A battery pack according to the present invention is a battery stack in which a plurality of chargeable / dischargeable unit cells are electrically connected and arranged in a predetermined direction, and a pair of battery stacks disposed at both ends in the predetermined direction. End plate, the battery stack is disposed between the pair of side plates connecting the pair of end plates, the end plate and the side plate are fastened, and a restraining load is placed between the pair of end plates And a plurality of fastening members for applying one of the end plates of the pair of end plates and one of the side plates of the pair of side plates. A plurality of first fastening members aligned in one direction, and a plurality of first fastening members arranged in the first direction and closer to the battery stack than the plurality of first fastening members; And a plurality of second fastening member relative to the first fastening member is offset in the first direction.

  According to the battery assembly of the present invention, one end plate and one side plate are mutually fastened by the plurality of first fastening members and the plurality of second fastening members. Here, the first fastening member is arranged in the first direction, the second fastening member is arranged in the first direction, and is disposed closer to the battery stack than the first fastening member, and the first direction with respect to the first fastening member Biased. As a result, compared with the case where all the fastening members are aligned in the first direction, fastening between the end plate and the side plate is performed in a wider range, and the fastening portion bending between the end plate and the side plate Stiffness can be improved. ADVANTAGE OF THE INVENTION According to the assembled battery which concerns on this invention, the fastening part bending rigidity of an end plate and a side plate can be improved, without increasing the number of fastening members.

It is a perspective view which shows the assembled battery which concerns on one Embodiment typically. It is a graph which shows the relationship between a restraint load and the bolt maximum stress. It is a perspective view which shows the assembled battery which concerns on other one Embodiment typically.

  Hereinafter, preferred embodiments of the present invention will be described. The matters other than the matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be understood as the design matters of those skilled in the art based on the prior art in the relevant field. The present invention can be implemented based on the contents disclosed in the present specification and common technical knowledge in the field. In addition, each drawing is drawn schematically and does not necessarily reflect an actual thing. Further, each drawing only shows an example, and each drawing does not limit the present invention unless otherwise stated.

First Embodiment
FIG. 1 is a perspective view schematically showing a structure of a battery assembly 100 according to the present embodiment. As shown in FIG. 1, the battery assembly 100 includes a battery stack 20 having a plurality of single cells 10, a pair of end plates 30A and 30B, a pair of side plates 40A and 40B, and a plurality of fastening members 50. ing.

  The battery stack 20 is configured by being disposed in a predetermined direction (the arrow X direction in FIG. 1) in a state where the plurality of chargeable / dischargeable unit cells 10 are electrically connected. The cells 10 are electrically connected in series or in parallel. Between the plurality of unit cells 10, a member (for example, a cooling plate or the like) other than the unit cells 10 may be interposed.

  The unit cell 10 is preferably an all solid battery, and more preferably an all solid lithium secondary battery. All-solid-state batteries typically comprise a positive electrode, a negative electrode, and a solid electrolyte. When the unit cell 10 is an all solid battery, the stacking direction of the positive electrode, the negative electrode, and the solid electrolyte is the same as the predetermined direction X. The unit cell 10 may be a non-aqueous electrolyte secondary battery. The non-aqueous electrolyte secondary battery includes a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte. When the unit cell 10 is a non-aqueous electrolyte secondary battery, the stacking direction of the positive electrode, the negative electrode, and the separator is the same as the predetermined direction X. Therefore, a restraint load is applied in the direction perpendicular to the electrode surface in the unit cell 10. Also, the unit cell 10 may be a fuel cell, a nickel hydrogen battery or other secondary battery.

  In the present specification, the term "secondary battery" refers to a storage device in general that can be repeatedly charged and discharged, and is a term including storage devices such as so-called storage batteries and electric double layer capacitors.

  The pair of end plates 30A, 30B is disposed at both ends of the battery stack 20 in the predetermined direction X. That is, the end plate 30A is disposed at one end of the battery stack 20 in one direction X, and the end plate 30B is disposed at the other end of the battery stack 20 in the predetermined direction X. End plates 30A and 30B receive the fastening force of fastening member 50 and the reaction force (load) from battery stack 20. Accordingly, the end plates 30A and 30B adopt materials and shapes that can withstand these forces. The end plates 30A, 30B may be made of metal or resin, and may be made of carbon steel, for example. The end plates 30A, 30B are formed in a plate shape. Note that the battery stack 20 and the pair of end plates 30A, 30B may be in direct contact with each other, or another member may be disposed between them for indirect contact.

  The battery stack 20 is disposed between the pair of side plates 40A and 40B. The side plates 40A, 40B are separated from the battery stack 20. The side plate 40A and the side plate 40B face each other via the battery stack 20. The side plates 40A and 40B connect the pair of end plates 30A and 30B, respectively. That is, the side plate 40A couples the end 30AK on one side of the end plate 30A in the direction of arrow Z in FIG. 1 with the end 30BK on one side of the end plate 30B in the direction of arrow Z in FIG. The side plate 40B couples the end 30AL on the other side of the end plate 30A in the direction of arrow Z in FIG. 1 with the end 30BL on the other side of the end plate 30B in the direction of arrow Z in FIG. The side plate 40A is connected to a first portion 40AX formed in a plate shape and one end of the first portion 40AX in the direction of the arrow X in FIG. 1 and has a thickness greater than that of the first portion 40AX. A second portion 40AY connected to 30A, and the other end of the first portion 40AX in the direction of the arrow X in FIG. 1, which is thicker than the first portion 40AX and connected to the end plate 30B And 3 parts 40 AZ. The side plate 40B is connected to a plate-like first portion 40BX and an end of the first portion 40BX on one side in the direction of the arrow X in FIG. 1 and has a thickness greater than that of the first portion 40BX. A second portion 40BY connected to 30A and the other end of the first portion 40BX in the direction of the arrow X in FIG. 1 have a thickness greater than that of the first portion 40BX and are connected to the end plate 30B And 3 parts 40BZ. The side plates 40A, 40B are formed of the same material as the end plates 30A, 30B, but may be formed of different materials.

  The fastening member 50 connects the end plate 30A and the side plate 40A, the end plate 30A and the side plate 40B, the end plate 30B and the side plate 40A, the end plate 30B and the side plate 40B, respectively. In the example shown in FIG. 1, the end plate 30B and the side plate 40A, and the fastening member 50 connecting the end plate 30B and the side plate 40B are not shown. The fastening member 50 applies a restraining load between the pair of end plates 30A and 30B.

  The fastening member 50 includes a plurality of first fastening members 51 and a plurality of second fastening members 52. End plate 30A and side plate 40A, end plate 30A and side plate 40B, end plate 30B and side plate 40A, end plate 30B and side plate 40B are connected by the first fastening member 51 and the second fastening member 52, respectively. . The first fastening members 51 are arranged in the direction of the arrow Y in FIG. The second fastening members 52 are arranged in the direction of the arrow Y in FIG. The second fastening member 52 is disposed closer to the battery stack 20 than the first fastening member 51. In the present embodiment, the second fastening member 52 is arranged to overlap with a part of the first fastening member 51 in the arrow Z direction. The second fastening member 52 may be disposed at a position not overlapping the first fastening member 51 in the arrow Z direction. The second fastening member 52 is biased with respect to the first fastening member 51. That is, the second fastening member 52 is disposed at a position not overlapping the first fastening member 51 in the arrow Y direction. In the present embodiment, the second fastening member 52, the first fastening member 51, the second fastening member 52, the first fastening member 51, the second fastening member 52, the second fastening are provided from one side to the other side in the Y direction. The member 52, the first fastening member 51, the second fastening member 52, the first fastening member 51, and the second fastening member 52 are disposed in this order. Arrangement of the first fastening member 51 and the second fastening member 52 connecting the end plate 30A and the side plate 40A, and arrangement of the first fastening member 51 and the second fastening member 52 connecting the end plate 30A and the side plate 40B. And are symmetrical with respect to the arrow Z direction. In the present embodiment, the number of first fastening members 51 used when fastening the end plate 30A and the side plate 40A is four, and the number of second fastening members 52 is six, but is not limited thereto.

  As described above, according to the battery assembly 100 of the present embodiment, the pair of end plates 30A and 30B and the pair of side plates 40A and 40B are mutually formed by the plurality of first fastening members 51 and the plurality of second fastening members 52. It is concluded. Here, the first fastening members 51 are arranged in the direction of the arrow Y, and the second fastening members 52 are arranged in the direction of the arrow Y and arranged closer to the battery stack 20 than the first fastening members 51 and are arrowed with respect to the first fastening members 51. It is biased in the Y direction. Thereby, the fastening between the end plates 30A, 30B and the side plates 40A, 40B is performed in a wider range as compared with the case where all the fastening members 50 are aligned on the same straight line in the arrow Y direction, It is possible to improve the bending rigidity of the fastening portion of the end plates 30A, 30B and the side plates 40A, 40B. That is, in the battery assembly 100, it is possible to increase the bending rigidity of the fastening portions between the end plates 30A, 30B and the side plates 40A, 40B without increasing the number of fastening members 50.

  FIG. 2 is a graph showing the relationship between the maximum stress applied to the fastening member 50 and the restraint load applied to the battery stack 20. As shown in FIG. When a load is applied to the end plates 30A, 30B from the battery stack 20 by the expansion of the unit cell 10, a force is applied in a direction to separate the end plates 30A, 30B and the side plates 40A, 40B. That is, a relatively large load is applied to the fastening member 50. When a predetermined load or more is applied to the fastening member 50, the end plates 30A, 30B and the side plates 40A, 40B are separated, and the load applied to the fastening member 50 is increased. For this reason, it may be disadvantageous for securing the strength of the fastening member 50. In the example shown in FIG. 2, the point at which the inclination has changed represents the restraint load at which the release of the end plates 30A, 30B and the side plates 40A, 40B has started. As shown in FIG. 2, when the fastening members 50 are arranged in a line, the release of the end plates 30A, 30B and the side plates 40A, 40B starts at the position of the point P in FIG. On the other hand, when the fastening members 50 are arranged in a staggered manner as in the present embodiment, the end plates 30A, 30B and the side plates 40A, 40B begin to be released at the position of point Q in FIG. As described above, when the fastening members 50 are arranged in a zigzag manner, the liberation of the end plates 30A, 30B and the side plates 40A, 40B can be suppressed to a higher restraint load.

Second Embodiment
FIG. 3 is a perspective view schematically showing the structure of the battery assembly 100 according to the present embodiment. In the present embodiment, the second fastening member 52, the first fastening member 51, the first fastening member 51, the first fastening member 51, the second fastening member 52, the second fastening are provided from one side to the other side in the Y direction. The member 52, the first fastening member 51, the first fastening member 51, the first fastening member 51, and the second fastening member 52 are arranged in this order. In the present embodiment, the number of first fastening members 51 used when fastening the end plate 30A and the side plate 40A is six, and the number of second fastening members 52 is four, but is not limited thereto.

  The battery assembly 100 of the present embodiment is suitable for use as a drive power supply for vehicles such as hybrid vehicles and electric vehicles.

  Although the present invention has been described in detail above, the above embodiments and examples are merely examples, and the invention disclosed herein includes various modifications and alterations of the specific example described above.

DESCRIPTION OF SYMBOLS 10 single battery 20 battery stack 30A, 30B end plate 40A, 40B side plate 50 fastening member 51 1st fastening member 52 2nd fastening member 100 assembled battery

Claims (1)

A battery stack in which a plurality of chargeable and dischargeable cells are electrically connected and arranged in a predetermined direction;
A pair of end plates disposed at both ends of the battery stack in the predetermined direction;
A pair of side plates between which the battery stack is disposed and which connects the pair of end plates, respectively;
And a plurality of fastening members for fastening the end plate and the side plate and applying a restraining load between the pair of end plates,
The plurality of fastening members for fastening one end plate of the pair of end plates and one side plate of the pair of side plates are a plurality of first fastening members arranged in a first direction, and A plurality of second fastenings arranged in the first direction and disposed closer to the battery stack than the plurality of first fastening members and biased in the first direction with respect to the plurality of first fastening members A battery assembly including:

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