Battery pack

Abstract

To provide technology that, when an excessive rise of temperature occurs to one of battery cells in a battery pack, prevents a chain of excessive rises of temperature by a method that may not cause the entire width of the battery pack to expand.SOLUTION: The battery pack comprises a plurality of battery cells and an intermediate member. The plurality of battery cells are arranged along a prescribed direction of arrangement and are bound along the direction of arrangement. The intermediate member is located between at least one set of adjacent battery cells among the plurality of battery cells, and includes two plates facing each other and an elastic body that connects the two plates. The two plates facing each other is in contact with the one set of adjacent battery cells. The elastic body is formed from a thermosetting resin and causes an elastic force to occur along the direction of arrangement.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a battery pack mounted on a vehicle.

Background Art

[0002] Patent Document 1 discloses a battery pack capable of suppressing the progression of chain heat generation between battery cells.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] One of the problems related to batteries is overheating caused by abnormal heat generation of battery cells due to deterioration, short circuit, etc. Further, it is also a problem that an overheating chain in which the overheating is transmitted to surrounding cells occurs.

[0005] As a countermeasure against the overheating chain, for example, in Patent Document 1, a restraint plate made of a thermoplastic resin is provided between battery cells, and an elastic body is provided inside the restraint plate. When the temperature rises excessively, the restraint plate melts and the elastic body inside the restraint plate is exposed. By separating the battery cells from each other with the elastic force (repulsive force) of the exposed elastic body, the overheating chain is prevented.

[0006] However, in order to exhibit the above mechanism, the elastic force for separating the battery cells from each other must be greater than the restraint force for restraining the entire battery pack. Satisfying this condition means that the width of the entire battery pack also increases.

[0007] For example, when multiple assembled batteries described in Patent Document 1 are mounted on an electric vehicle, it is necessary to secure the space for the spread of the entire assembled battery as described above. If there is no such space, the assembled batteries will constrain each other during overheating, and the battery cells cannot be separated from each other. As a result, it is difficult to prevent the overheating chain reaction. Also, securing space means a reduction in the amount of batteries that can be mounted.

[0008] One object of the present disclosure is to provide a technique for preventing an overheating chain reaction in an assembled battery in such a way that when overheating occurs in one of the battery cells, the width of the entire assembled battery does not increase.

Means for Solving the Problem

[0009] Relates to an assembled battery mounted on a vehicle. The assembled battery includes a plurality of battery cells and an intermediate member. The plurality of battery cells are arranged along a predetermined arrangement direction and are constrained along the arrangement direction. The intermediate member is disposed between at least one set of adjacent battery cells among the plurality of battery cells, and includes two opposing plates and an elastic body connecting the two plates. The two opposing plates are in contact with one set of adjacent battery cells. The elastic body is made of a thermoplastic resin and generates an elastic force along the arrangement direction.

Effect of the Invention

[0010] The elastomer made of a thermoplastic resin is plasticized by the heat received from the plate heated to a high temperature due to overheating, and loses its load-bearing function. On the other hand, the assembled battery is constrained by a certain restraining force. Although the battery cells expand due to high temperature, the space between the two plates can be utilized to absorb the dimensional changes of the battery cells at high temperature. That is, the two opposing plates approach each other, but their contact is avoided or suppressed. Therefore, direct heat conduction from the battery cell at high temperature to the battery cell adjacent to the said battery cell can be suppressed, and the change in the overall width of the assembled battery can be avoided or suppressed. Accordingly, the battery loading capacity for the vehicle can be improved in a safe manner.

[0011] Furthermore, since the heat resistance of the elastomer only needs to be such that it plasticizes under overheating, it is not necessary to exhibit an elastic force equal to or greater than the restraining force even under overheating as in Patent Document 1. This will lower the criteria for material selection, leading to cost reduction.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0013] Embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0014] 1. Main Configuration of the Assembled Battery FIG. 1 is a perspective view of the assembled battery 1. In this figure, a plurality of battery cells 10 are arranged along the arrangement direction X. An intermediate member 20 is disposed between each of the battery cells 10A to 10F. Here, the intermediate member 20 is used as a means for solving the problems raised in the present disclosure. The detailed configuration of the intermediate member 20 will be described later. In this figure, the intermediate member 20 is used between the battery cell 10C and the battery cell 10D. Constraint plates 31 are respectively installed at both ends of the arrangement so as to be in contact with the battery cells 10A and 10F located at the ends of the arrangement. The constraint plates 31 are fastened together by a constraint band 32. The constraint plate 31 and the constraint band 32 are joined by mechanical joining with bolts or the like. That is, the assembled battery 1 has a configuration in which an array including a plurality of battery cells 10 and an intermediate member 20 is pressed along the arrangement direction X by the constraint plates 31 and the constraint band 32.

[0015] For example, by mounting a plurality of assembled batteries 1 on a vehicle with one assembled battery 1 as a unit, it is used as a power source for electric vehicles such as BEV, PEV, and HEV. The battery cell is a rechargeable secondary battery, for example, a lithium-ion secondary battery.

[0016] 2. Detailed Configuration and Effect of Intermediate Member FIG. 2 is a schematic diagram for explaining the detailed configuration and effect of the intermediate member 20. (A) in FIG. 2 is a state before the over-temperature of the battery cell 10 occurs. The intermediate member 20 includes two plates 21 and an elastic body 22. The plates 21 are made of metal and are arranged so as to be in contact with the battery cell 10 and face each other. The elastic body 22 is arranged such that its length direction is along the arrangement direction, and connects between the two plates 21. The material of the elastic body 22 is a thermoplastic resin. The shape of the elastic body 22 is, for example, spring-shaped.

[0017] The elastic body 22 acts to push the plate 21 outward, that is, toward the constraint plate 31 side. That is, the battery cell 10 is fixed by being pressed against the constraint plate 31 by the elastic body 22.

[0018] (B) in Fig. 2 shows the case where overheating occurs in battery cell 10A. The heat generated in battery cell 10A is transmitted to the adjacent battery cell 10B, further transmitted to battery cell 10C, and then transmitted to plate 21A. Also, as the temperature rises, battery cells 10A to 10C expand.

[0019] The elastic body 22 made of a thermoplastic resin is plasticized by the heat received from the heated plate 21A and loses its load-bearing function. On the other hand, the restraint plate 31 and the restraint band 32 are affected by high temperatures but have a certain restraint force. Therefore, the dimensional changes due to the expansion of battery cells 10A to 10C are mainly absorbed between plates 21A and 21B. Therefore, even after the temperature rises, it is easy to create a space between the plates 21, and direct heat conduction to the opposite battery cell 10D is less likely to occur. This leads to preventing the overheating chain of the battery pack 1 and contributes to improving the safety of the entire vehicle.

[0020] The fact that the dimensional changes due to the expansion of battery cells 10A to 10C are mainly absorbed between plates 21A and 21B means that the width of the entire battery pack 1 (the length along the arrangement direction X) is less likely to change. Therefore, even when a plurality of battery packs 1 are mounted on a vehicle, it is difficult for adjacent battery packs 1 to come into contact with each other, that is, heat is less likely to be transmitted. Therefore, it can be said that the battery mounting amount for the vehicle can be improved in a safe manner.

[0021] 3. Modification Fig. 3 is a schematic diagram showing a modification of the intermediate member 20. (A) in Fig. 3 shows the state of the battery pack 1 before overheating. In the battery pack 1 shown in the figure, the plate 21 has a convex portion 21a.

[0022] (B) in Fig. 3 shows the state of the assembled battery 1 after overheating. Similar to the examples described so far, the elastomer 22 is plasticized and the battery cells 10A to 10C expand. Here, consider the case where the amount of expansion of the battery cells 10A to 10C is larger than that in (B) of Fig. 2 and the opposing plates 21 come into contact with each other. As shown in the figure, when the plate 21 has the convex portions 21a, the convex portions 21a come into contact with each other, and the heat conduction path becomes a limited path through the convex portions 21a. On the other hand, if the plate 21 does not have the convex portions 21a, the plates 21 come into contact over the entire surface, heat conduction is likely to occur, and as a result, the risk of chain overheating is high. Therefore, by having the convex portions 21a, the heat conduction when the plates 21 come into contact with each other can be reduced, contributing to the prevention of overheating chain.

Description of reference numerals

[0023] 1: Assembled battery, 10: Battery cell, 20: Intermediate member, 21: Plate, 21a: Convex portion, 22: Elastomer, 31: Restraining plate, 32: Restraining band, X: Arrangement direction

Claims

【Claim 1】 A battery pack mounted on a vehicle, comprising: a plurality of battery cells; an intermediate member; The plurality of battery cells are arranged along a predetermined arrangement direction, constrained along the arrangement direction, The intermediate member is disposed between at least one set of adjacent battery cells among the plurality of battery cells, and includes two plates facing each other and an elastic body connecting the two plates, The two plates are in contact with the one set of adjacent battery cells, The elastic body is made of a thermoplastic resin and generates an elastic force along the arrangement direction. Battery pack ​ ​

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