Battery pack

Abstract

To prevent a shim from displacing in a surface direction on a side face of a case 5, in a battery pack configured such that a battery stack 1a including a plurality of stacked battery cells 2 is pressed, together with the shim 6, by both side faces 5l, 5r of the case from both ends of each battery cell in a stacking direction thereby to hold the battery stack in the case.SOLUTION: There is provided a battery pack in which a battery stack including a plurality of stacked battery cells is pressed, through a shim body, by both side faces of a case from both ends of the battery cells in a stacking direction thereby to hold the battery stack between both side faces of the case. In the battery pack, the shim body has an opening 6a extending in a thickness direction thereof, and a protrusion 5a protruding into the opening of the shim body is formed on a side face abutting the shim body of the case.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a battery pack that houses a battery stack formed by stacking a plurality of battery cells. More specifically, the present invention relates to a structure of a battery pack configured to press both ends of the battery stack against the side surfaces of a case to maintain the stacked state of the plurality of battery cells.

Background Art

[0002] As structures of battery packs that accommodate battery stacks formed by stacking a plurality of battery cells, various configurations have been proposed. For example, in Patent Document 1, a battery array formed by stacking a plurality of cells is disposed in an attachment space inside a box-shaped case, and an adjustment shim group composed of a plurality of adjustment shims is interposed between an end of the battery array in the stacking direction of the cells and the side surface of the case, and a wedge member is inserted between an end of the battery array on the opposite side and the side surface of the case, and a configuration is described in which the battery array and the adjustment shim group are pressed. Further, in Patent Document 2, battery cells are disposed on the surface of a flat chassis having wall surfaces substantially perpendicular to three sides, and a holding plate is disposed via an adjustment plate on the surface of the battery cell opposite to the surface in contact with the chassis, and an edge thereof is connected to the wall surface of the chassis, and a configuration is disclosed in which the holding plate presses the battery cells against the surface of the chassis and fixes them.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] As one of the configurations of a battery pack in which a battery stack is housed in a housing (case), a configuration has been proposed in which the battery stack is held in a state of being sandwiched while being pressed from both ends in the stacking direction of a plurality of battery cells between both side surfaces of the housing. In the case of such a configuration, more specifically, as shown in Fig. 4(A), first, a plurality of battery cells 2 are stacked in the thickness direction with a resin frame 2a interposed therebetween, and resin plates 3 and 4 are arranged at both ends thereof. By sandwiching the plurality of cells 2 while pressing with the plates 3 and 4, as shown in Fig. 4(B), the cells 2 are brought into close contact via the resin frame 2a and a stack 1a is formed. Then, as shown in Fig. 4(C), the stack 1a is incorporated into the inside of the case 5 together with a shim 6 (a plurality of shims may be stacked) (arrows S, T). At this time, the surface of the plate 4 of the stack 1a abuts against one side surface 5r of the case 5, and the plate 3 of the stack 1a faces the other side surface 5l of the case 5 via the shim 6. By applying a compressive force in the stacking direction of the battery cells 2 to the stack 1a and the shim 6 from one side surfaces 5r, 5f of the case 5, the stack 1a is stably held in the case 5. Thereafter, a bus bar module 7 for electrically connecting the plurality of battery cells 2 and a buffer material 8 for protecting the stack 1a while pressing it from above are arranged.

[0005] As described above, in the configuration in which the stack 1a and the shim 6 are pressed and held from both side surfaces of the case 5, the shim 6 is adhered with a double-sided tape or the like so as not to shift in the plane direction of the side surface of the case 5 (when a plurality of shims are stacked, the shims are also adhered with a double-sided tape). Since the shim 6 is only sandwiched between the side surface 5l of the case 5 and the plate 3, as schematically shown in Fig. 5, when an inclination occurs in the stack 1a and a component in the direction along the surface is generated in the pressing force acting on the stack 1a, slippage occurs at the interface of the double-sided tape adhering the shim 6, and the shim 6 is displaced along the plane direction from the case 5 as shown by the arrow z, and a phenomenon may occur in which the shim 6 and the stack 1a float up from the case 5.

[0006] In view of the above circumstances, the main problem of the present invention is to press a battery stack formed by stacking a plurality of battery cells together with a shim from both ends in the stacking direction of the battery cells by both side surfaces of a case, and hold the battery stack in the case. In a battery pack having such a configuration, it is to prevent the shim from displacing in the plane direction at the side surface of the case.

Means for Solving the Problem

[0007] According to the present invention, the above problem is solved by a battery pack in which a battery stack formed by stacking a plurality of battery cells is pressed from both ends in the stacking direction of the battery cells through a shim body by both side surfaces of a case, and the battery stack is held between both side surfaces of the case. The shim body has an opening extending in its thickness direction, and a convex portion protruding into the opening of the shim body is formed on the side surface of the case that abuts against the shim body.

[0008] In the above configuration, the “battery pack” is a device in which a battery is housed inside a case and is mounted on an electric vehicle or other mechanical device for driving or operating purposes. The “battery cell” may be any battery cell used in this field. Typically, as described in relation to FIGS. 4(A) to 4(C), a plurality of battery cells may be stacked with a resin frame interposed therebetween, and plates, which may be made of resin, may be attached to both ends in the stacking direction to form a battery stack. The “shim body” may be a flat plate member made of any material (resin or metal) used in this field for adjusting the position by being sandwiched between members. In the present invention, the shim body may be a single flat plate member, but as described in the column of the following embodiments, it may be a stack of shims that are a plurality of flat plate members. Thus, by adjusting the number of stacked sheets, the thickness of the shim body can be appropriately changed. The “case” may be a member having a shape in which side surfaces stand upright on a flat plate formed of any material (resin or metal) used as a housing in this field. The case may be a die-cast case (a case formed by die-casting), but is not limited thereto.

[0009] In the above configuration, the shim body sandwiched between the battery stack and the side surface of the case has an opening extending in the thickness direction thereof, and a convex portion protruding into the opening is formed on the side surface of the case. As a result, the displacement of the shim body along the surface direction of the side surface of the case is restricted. Accordingly, even if a force component in the surface direction of the side surface of the case is generated in the shim body due to the inclination of the battery stack or the like, the displacement of the shim body in the surface direction of the side surface of the case is prevented, and the battery stack is held more stably.

[0010] As one aspect of the configuration of the present invention described above, the opening of the shim body may penetrate the shim body in the thickness direction, and the convex portion on the side surface of the case that abuts against the shim body may extend through the opening of the shim body to a concave portion formed on the surface of the shim body that abuts against the battery stack. According to such a configuration, the displacement of the battery stack in the surface direction of the side surface of the case is also restricted, and the battery stack together with the shim body is held more stably with respect to the side surface of the case in the surface direction thereof. Further, at this time, the protruding length of the convex portion on the side surface of the case that abuts against the shim body may be formed to be longer than the thickness of the shim body and shorter than the sum of the thickness of the shim body and the depth of the concave portion in the battery stack. Thereby, the pressing force from the side surface of the case surely acts on the shim body toward the battery stack, and the battery stack is held more stably.

[0011] Note that the battery stack may not have a concave portion formed therein. In this case, the convex portion on the side surface of the case is formed such that its length is equal to or less than the thickness of the shim body.

Effect of the Invention

[0012] Thus, according to the configuration of the present invention, in a battery pack configured to hold a battery stack formed by stacking a plurality of battery cells together with a shim by pressing from both side surfaces of the case at both ends in the stacking direction of the battery cells, the floating of the shim is prevented, and the battery stack is held more stably in the case. The battery pack of the present invention may be used in various electric vehicles and other mechanical devices operated using the power of a battery.

[0013] Other objects and advantages of the present invention will become apparent from the following description of the preferred embodiments of the present invention.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Description of the Reference Numerals

[0015] 1... Battery pack, 1a... Battery stack, 2... Battery cell, 2a... Resin frame, 3... Plate, 3a... Plate recess, 4... Plate, 5... Case, 5a... Case projection, 6... Shim, 6a... Shim opening, 7... Bus bar module, 8... Buffer material

Best Mode for Carrying Out the Invention

[0016] While referring to the attached drawings below, the present invention will be described in detail with respect to several preferred embodiments. In the drawings, the same reference numerals indicate the same parts.

[0017] Configuration of the battery pack Referring to FIGS. 1(A) and (B), in the battery pack 1 according to the present embodiment, similar to the form exemplified in FIGS. 4(A) to 4(C), a battery stack 1a in which a plurality of battery cells 2 are laminated in the thickness direction with a resin frame 2a interposed therebetween is disposed between both side surfaces 5l and 5r of a case 5 together with a shim 6 disposed at at least one end, and is held in a state of being pressed from both side surfaces thereof. The battery cell 2 may be any battery cell used in this field, and the resin frame 2a may be one commonly used as a resin member interposed between the battery cells 2. Further, plates 3 and 4, which may typically be made of an insulating resin material, are attached to both ends of the battery stack. The case 5 may typically be a metal case cast by die-casting technology, and specifically, as shown in the drawings, it may be a housing formed with side surfaces standing upright on four sides of a flat plate-like member. The shim 6 may typically be formed by laminating a plurality of flat plate-like members made of resin or metal, and the number thereof may be adjusted according to the size of the interval into which the shim 6 is sandwiched (the shim 6 may also be a single body, and in that case, it also belongs to the scope of the present embodiment). Further, when the shim 6 is formed by laminating a plurality of flat plate-like members, double-sided tapes may be applied and adhered between them.

[0018] Configuration for restricting displacement of the shim in the case side surface direction In the configuration of the above-described battery pack 1, in the case of this embodiment, as can be understood from FIGS. 2(A) and (B) as well, an opening 6a is formed in the shim 6 in its thickness direction, and with the shim 6 disposed between the side surface 5l of the case and the plate 3 of the battery stack 1a, a convex portion 5a is formed on the side surface 5l of the case so as to align with the opening 6a of the shim 6, and it is configured to be inserted into the opening 6a of the shim 6. Thereby, displacement of the shim 6 along the plane direction of the case side surface 5l is restricted, and thus, even if the battery stack 1a has some inclination and a component of the force along the plane direction of the case side surface 5l is generated, the position of the shim is maintained, and a state where the battery stack is more stably held in the case is maintained.

[0019] As described above, in the configuration of forming the opening 6a in the shim 6 and forming the convex portion 5a that is inserted into the opening 6a on the case side surface 5l, in one aspect, as shown in FIGS. 1(A) and (B), the opening 6a of the shim 6 penetrates the shim 6 in the thickness direction, and while aligning with the opening 6a, a concave portion 3a is formed on the plate 3 of the battery stack. The convex portion 5a of the case side surface 5l may be formed to penetrate the opening 6a of the shim 6 and extend to the concave portion 3a of the plate 3 of the battery stack. Thereby, displacement of the concave portion 3a of the plate 3 in the plane direction of the case side surface 5l is also restricted, the plate 3 abuts against and adheres to the surface of the shim 6, and it is more stably held with respect to the case side surface 5l. Also, in that case, as schematically shown in FIG. 3(A), when the shim 6 is disposed on the case side surface 5l and further the plate 3 is disposed thereon (arrow x), the tip of the convex portion 5a of the case side surface 5l passes through the opening 6a of the shim 6 and reaches the concave portion 3a of the plate 3. As shown in FIG. 3(B), it is preferable that the convex portion 5a is formed such that the protruding length a thereof is smaller than the sum of the thickness c of the shim 6 × N (number of sheets) and the depth b of the concave portion (a < c × N + b). With such a configuration, the pressing force from the case side surface 5l toward the plate 3 is transmitted through the shim 6, and the pressing force surely acts on the shim 6 from both sides thereof. Thus, the battery stack and the shim 6 are more stably held so as not to be displaced with respect to the case side surface 5l.

[0020] In another aspect, when the concave portion is not formed on the plate 3, the convex portion 5a of the case side surface 5l is formed such that the protruding length a thereof is equal to or less than the thickness c of the shim 6 multiplied by N. Also in this case, the displacement of the shim 6 in the surface direction of the case side surface 5l is blocked, and it is possible to prevent the phenomenon that the shim 6 floats up from between the case side surface 5l and the plate 3.

[0021] Thus, in the configuration of the present embodiment described above, in the case of a battery pack configured to hold a battery stack formed by stacking a plurality of battery cells together with a shim between both side surfaces of the case from both ends in the stacking direction of the battery cells, the floating of the shim is prevented, and the battery stack is more stably held in the case. In this regard, in the case of the battery pack targeted by the present embodiment, in order to ensure performances such as holding of the wound body of the battery cell and prevention of resistance increase, it is necessary to apply a certain load to the battery cell. Such a load is determined from the spring constant of the case and the distance between the side surfaces. However, since there is a certain degree of variation in the dimensions of the battery stack sandwiched between the side surfaces of the case, the shim is sandwiched between the case side surface and the battery stack so that the load applied to the battery cell is adjusted. According to the present embodiment, it is advantageous in that the displacement of the shim can be prevented without impairing the function of the shim. The electric pack of the present embodiment is advantageously used for driving a driving device of an electric vehicle or other mechanical appliances or for actuation.

[0022] The above description has been made in relation to the embodiments of the present invention. However, many modifications and changes are easily possible for those skilled in the art, and it is obvious that the present invention is not limited to only the embodiments illustrated above, but can be applied to various devices without departing from the concept of the present invention.

Claims

1. A battery pack in which a battery stack formed by stacking a plurality of battery cells is pressed by both side surfaces of a case via shim bodies from both ends in the stacking direction of the battery cells, and the battery stack is held between both side surfaces of the case, wherein the shim body has an opening extending in its thickness direction, and a convex portion protruding into the opening of the shim body is formed on the side surface of the case that abuts the shim body.

2. The battery pack according to Claim 1, wherein the opening of the shim body penetrates the shim body in its thickness direction, and the convex portion on the side surface of the case that abuts the shim body extends through the opening of the shim body to a recess formed on the surface of the battery stack that abuts the shim body.

3. The battery pack according to Claim 2, wherein the protruding length of the convex portion on the side surface of the case that abuts the shim body is longer than the thickness of the shim body and shorter than the sum of the thickness of the shim body and the depth of the recess in the battery stack.

4. The battery pack according to Claim 1, wherein the shim body is a laminate of a plurality of shims, each of the plurality of shims has an opening, and they are aligned to form the opening of the shim body.

5. The battery pack according to Claim 1, wherein the case is a die-cast case.

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