JP7148326B2 - battery module - Google Patents

Description

The present invention relates to a battery module in which a plurality of stacked unit cells are sandwiched between a pair of end plates.

A battery module mounted on a hybrid car or an electric vehicle has a unit cell group composed of a plurality of stacked unit cells arranged between a pair of end plates, and a bind bar or the like provided across the end plates. The entire single battery cell group is sandwiched by the restraining member.

By the way, a single battery cell expands due to charge/discharge and deterioration. In order to suppress this expansion, a large initial load is applied to the unit cell group in a compressing direction along the stacking direction, and the entire unit cell group is forcibly pressed between the end plates. Therefore, when the unit cell group expands in the stacking direction due to an increase in the internal pressure of the unit cells due to expansion, a considerably large load is applied to the end plates.

In such a battery module, when the single cell expands, a greater load than the initial load is applied to the fixing point between the restraint member and the end plate. Therefore, it is necessary to reduce the load applied to the fixing point by separately providing a bending structure or a sliding structure at the fixing point between the restraint member and the end plate. Conventionally, an elastic member is arranged between a unit cell group and an end plate, and a rectangular plate-shaped low-elasticity rubber sponge absorbs additional load generated when the unit cell expands. is also known (see, for example, Patent Document 1). However, this battery module also applies a large initial load (restrained load) by compressing the unit cell group.

JP 2015-230764 A

In conventional battery modules, a large initial load is applied by compressing the unit cell group, so it is necessary to add a separate structure such as a flexible structure or a sliding structure at the fixed point, which makes the structure complicated. In addition, lamination equipment and a lamination process for applying an initial load are also required. In addition, the larger the number of laminated single cells, the greater the increase in the size of the single cell group when it expands due to expansion. Since the initial load is set in consideration of the increase in the size of the single cell group, if the number of single cell stacks is increased in order to cope with a large current, a large initial load corresponding to the increase in the number of stacks is applied. Must-have. However, since there is a limit to the initial load that can be applied due to the structure of the unit cell, there is also the problem that the number of stacked unit cells is restricted.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a battery module in which a plurality of unit cells can be stacked between end plates without applying a large initial load, and which can cope with load fluctuations applied to the end plates with a simple structure. for the purpose.

(1) A battery module (for example, a battery module 1 described later) according to the present invention is a unit cell group (for example, a A single battery cell group 2), a pair of end plates (for example, end plates 3 and 4 described later) respectively arranged at both ends of the single battery cell group in the stacking direction, the single battery cell group and the pair of end plates A spring member (for example, a spring member to be described later) that is provided between at least one of the plates (for example, an end plate 3 to be described later) and can apply a load in a direction that presses the single battery cell group 6), wherein the spring member includes a first spring (for example, a first spring 61 described later) arranged at a position corresponding to the central region of the unit cell, and arranged around the first spring and a second spring (eg, a second spring 62 described below), wherein the spring constant of the first spring is greater than the spring constant of the second spring.

According to the battery module described in (1) above, the second spring, which has a relatively smaller spring constant than the first spring, first comes into contact with the unit cell group between the pair of end plates, thereby Since the cell group is supported, the unit cell group can be stacked and arranged between the end plates without applying a large initial load. In addition, when the unit cell expands, the load from the unit cell group can be handled by the first spring having a relatively large spring constant, so the load fluctuations applied to the end plate can be handled with a simple structure. . Furthermore, the stacking facility and stacking process for applying an initial load are not required, and the number of stacks of single cells can be increased.

(2) In the battery module according to (1), the first spring acts on the unit cell group against a load acting on the end plate due to an increase in internal pressure during expansion of the unit cells. and the second spring may be a spring capable of applying a load corresponding to a load necessary for maintaining the initial stacked state to the unit cell group.

According to the battery module described in (2) above, an appropriate load can be applied to the single battery cell group by each of the first spring and the second spring.

(3) In the battery module according to (1) or (2), in the non-expanded state of the unit cells, the load applied by the second spring to the unit cell group is The load may be larger than the load applied to the unit cell group.

According to the battery module described in (3) above, when the unit cells do not expand, the second spring having a relatively small spring constant mainly applies a load to the unit cell group, so a large load is required. An unreasonable load is not applied to the single battery cell group in a non-expanded state without any pressure.

(4) In the battery module according to any one of (1) to (3), a holder member that is arranged between the end plate on which the spring member is provided and the unit cell group and holds the spring member (For example, a holder member 7 to be described later) is provided, and the holder member contacts along an inner side surface (for example, an inner side surface 3a to be described later) of the end plate, and is in contact with the unit cell group. A flat plate portion (for example, a flat plate portion 71 described later) that holds a spring, and a flat plate portion that is provided so as to protrude toward the single battery cell group, and the first spring is arranged between the end plate and the end plate. and a flexible concave portion (for example, a concave portion 72 to be described later) that accommodates and holds.

According to the battery module described in (4) above, the spring member having the first spring and the second spring can be easily arranged and held between the unit cell and the end plate. In addition, the first spring, which has a relatively large spring constant, is accommodated in the recess of the holder member from the end plate side and does not come into direct contact with the single cell. You can also avoid the risk of damage.

(5) In the battery module according to any one of (1) to (4), the first spring may be a disc spring, and the second spring may be a leaf spring.

According to the battery module described in (5) above, since the dimensions of the first spring and the second spring when compressed can be reduced, the spring member can be made compact as a whole, and an increase in the size of the battery module can be suppressed.

(6) In the battery module according to any one of (1) to (5), the battery module is arranged across the inner side surfaces of the pair of end plates facing each other to keep the gap between the pair of end plates constant. A spacing member (for example, a tie rod 5 described later) may be provided.

According to the battery module described in (6) above, since the minimum distance between the pair of end plates is regulated by the length of the distance retaining member, it is possible to prevent an excessive initial load from being applied to the unit cell group. . In addition, since the gap between the pair of end plates can be easily maintained at a constant gap, the assembly work of the battery module is facilitated.

ADVANTAGE OF THE INVENTION According to the present invention, a battery module is provided in which a plurality of unit cells can be stacked between end plates without applying a large initial load, and which can cope with load fluctuations applied to the end plates with a simple structure. be able to.

FIG. 4 is an exploded perspective view showing an exploded end plate of the battery module according to the present invention; 1 is an exploded perspective view of an end plate of a battery module according to the present invention, viewed from one direction; FIG. FIG. 5 is an exploded perspective view of the end plate of the battery module according to the present invention, viewed from another direction; FIG. 4 is a side view of a main part at one end of the battery module according to the present invention; 4 is a cross-sectional view along line AA in FIG. 3 in the battery module when the unit cells are not expanded; FIG. FIG. 4 is a cross-sectional view along the line BB in FIG. 3 in the battery module when the unit cells are not expanded; FIG. 4 is a cross-sectional view showing the battery module when the unit cells are inflated, cut along the same portion as line AA in FIG. 3; FIG. 4 is a cross-sectional view showing the battery module when the unit cells are inflated, cut along the same portion as the BB line in FIG. 3; It is a graph which shows the stroke of the 1st spring of an end plate, and a 2nd spring, and the relationship of a load.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an exploded perspective view showing an exploded end plate of a battery module according to the present invention. FIG. 2A is an exploded perspective view of the end plate of the battery module according to the present invention viewed from one direction. FIG. 2B is an exploded perspective view of the end plate of the battery module according to the present invention viewed from another direction. FIG. 3 is a side view of essential parts at one end of the battery module according to the present invention. FIG. 4 is a cross-sectional view along line AA in FIG. 3 of the battery module when the unit cells are not expanded. FIG. 5 is a cross-sectional view of the battery module taken along line BB in FIG. 3 when the unit cells are not expanded.

As shown in FIG. 1, the battery module 1 includes a single cell group 2, a pair of end plates 3 and 4 arranged at both ends of the single cell group 2 to sandwich the single cell group 2, and a pair of A plurality of tie rods 5 (four in this embodiment) extending between the end plates 3 and 4, a spring member 6 arranged between one end plate 3 and the single battery cell group 2, and a spring member 6 and a holder member 7 for holding.

In the directions indicated by the arrows in each figure of this specification, the direction along the D1 direction indicates the length direction of the battery module 1 . A direction along the D2 direction indicates the width direction of the battery module 1 . A direction along the D3 direction indicates the height direction of the battery module 1 . The D3 direction indicates "above" the battery module 1, and the opposite direction indicates "below" the battery module 1. FIG.

The unit cell group 2 is configured by stacking a plurality of rectangular parallelepiped unit cells 21 along the D1 direction. The unit cell 21 is configured by housing an electrode body (not shown) in a cell case made of aluminum, an aluminum alloy, or the like, and has a pair of positive and negative electrode terminals 22, 22 on the upper surface. In general, the electrode terminals 22, 22 of the unit cells 21, 21 adjacent in the stacking direction (D1 direction) are electrically connected by a bus bar (not shown). Thereby, all the single cells 21 of the single cell group 2 are electrically connected in series or in parallel. Insulating separators (not shown) are arranged between the unit cells 21 and 21 adjacent to each other in the stacking direction, and are sandwiched between the unit cells 21 and 21 .

The end plates 3 and 4 are formed of a metal material such as aluminum or an aluminum alloy, a resin material such as engineering plastic, or a laminate of a metal material and a resin material, and each end face of the single battery cell group 2 in the stacking direction. It consists of a plate-shaped member having a slightly large area. Bolt insertion holes 31 and 41 are provided at the four corners of the end plates 3 and 4, respectively. The end plates 3 and 4 are fixed by bolts 51 to the tie rods 5 arranged across the inner side surfaces 3a and 4a facing each other with the unit cell group 2 sandwiched therebetween.

The tie rods 5 are made of rod-shaped members that extend straight along the stacking direction of the unit cells 21 , and two tie rods 5 are arranged on both sides of the unit cell group 2 . The opposing inner side surfaces 3a, 4a of the end plates 3, 4 are in contact with both end surfaces of the tie rod 5, respectively. In this state, the bolts 51 are inserted through the bolt insertion holes 31, 41 from the outside of the end plates 3, 4, so that the end plates 3, 4 are fixed so as to sandwich the tie rod 5 from both sides. As a result, the end plates 3 and 4 are prevented from moving toward each other by the tie rod 5 . That is, the end plates 3 and 4 are arranged at both ends of the single battery cell group 2 while being held at a constant interval defined by the length L1 of the tie rod 5 .

By fixing the end plates 3 and 4 to the tie rod 5 in this way, the minimum distance between the end plates 3 and 4 is regulated by the length L1 of the tie rod 5 . Therefore, it is possible to prevent an excessive initial load from being applied to the unit cell group 2 when the end plates 3 and 4 are fixed. Moreover, since the gap between the pair of end plates 3 and 4 can be easily maintained at a constant gap, the assembly work of the battery module 1 is facilitated. This tie rod 5 corresponds to the spacing member in the present invention.

The length L1 of the tie rod 5 is longer than the length L2 of the unit cell group 2 in the initial stacking direction in the stacking direction. Specifically, as will be described later in detail, the length L1 of the tie rod 5 is the same as the length of the single cell group even when the single cell group 2 is most elongated in the stacking direction due to an increase in internal pressure due to expansion of the single cell 21 . 2 is set to a length that can be accommodated between the pair of end plates 3 and 4 . In other words, the distance between the pair of end plates 3 and 4 does not change even if the unit cell group 2 extends. In addition, the single battery cell group 2 shown in the present embodiment is arranged in close contact with the end plate 4 of the pair of end plates 3 and 4, with the inner surface 4a of the end plate 4 as a reference surface. Therefore, a gap S (see FIG. 3) corresponding to the difference between L1 and L2 exists between the end plate 3 fixed to the tie rod 5 and the unit cell group 2 in the initial stacked state.

Note that the initial stacking state of the unit cell group 2 is a state in which a plurality of unit cells 21, all of which are in a non-expanded state, are stacked in close contact with each other in the direction D1 with separators interposed therebetween. Say. At this time, the unit cell group 2 is not substantially subjected to a load greater than a load capable of maintaining a stacking state in which the adjacent unit cells 21, 21 are in close contact with each other. In other words, the unit cell group 2 in the initial stacking state is not subjected to a large initial load that compresses the unit cells 21 along the stacking direction, unlike the conventional case.

A spring member 6 is arranged in a gap S between the end plate 3 and the unit cell group 2 . Specifically, the spring member 6 is provided between the single cell 21 arranged at the end portion of the single cell group 2 on the end plate 3 side and the end plate 3 . The spring member 6 is composed of a spring that exerts an elastic repulsive force on the unit cell group 2 in the direction toward the other end plate 4 . Thereby, the spring member 6 can apply a load to the unit cell group 2 in the direction of pressing along the stacking direction of the unit cells 21 (the direction toward the other end plate 4). In this embodiment, the spring member 6 is not arranged on the other end plate 4 side.

The spring member 6 is composed of a first spring 61 and a second spring 62 . The first spring 61 and the second spring 62 are held on the end plate 3 by the holder member 7 .
The first spring 61 is arranged at a position corresponding to the central region of the end plate 3 . The central region of the end plate 3 corresponds to the central region of the unit cell 21 (the central region of the surface of the unit cell 21 facing the end plate 3). On the other hand, the second spring 62 is arranged around the first spring 61 . Also, the spring constant of the first spring 61 is greater than the spring constant of the second spring. Therefore, regarding the stroke when the first spring 61 and the second spring 62 are each compressed against the elastic repulsion force, the load exerted by the first spring 61 elastically rebounds is greater than that of the second spring 62. It is larger than the load exerted by

Specifically, the first spring 61 can apply a load to the single battery cell group 2 to counter the load acting on the end plate 3 due to the increase in internal pressure during expansion due to charging/discharging or deterioration of the single battery cell 21 . It can be a spring. Moreover, the second spring 62 can be a spring capable of applying a load corresponding to the load required for maintaining the initial stacked state to the unit cell group 2 . Thereby, the battery module 1 can apply an appropriate load to the unit cell group 2 by each of the first springs 61 and the second springs 62 .

The specific types of springs used for the first spring 61 and the second spring 62 are not particularly limited as long as they can apply the required load to the single battery cell group 2, respectively. In terms of form, the first spring 61 is configured by a disc spring formed in an annular shape, and the second spring 62 is configured by a leaf spring bent into a substantially U shape. All of these springs can be made smaller in size when compressed than coil springs or the like, so that the spring member 6 can be made compact as a whole. Therefore, the gap S between the end plate 3 and the unit cell group 2 can be made small, and the size increase of the battery module 1 can be suppressed accordingly.

In this embodiment, the first spring 61 is composed of two disk springs, and the second spring 62 is composed of four leaf springs. The number is appropriately set according to the load and the like, and is not limited to the number shown in this embodiment.

The holder member 7 is made of resin such as PP (polypropylene) or PE (polyethylene), and is arranged between the single cell 21 at the end of the single cell group 2 and the end plate 3 . The holder member 7 includes a flat plate portion 71 that contacts along the inner surface 3a of the end plate 3, and protrudes from the flat plate portion 71 toward the unit cell 21 (toward the direction opposite to the end plate 3). and a recess 72 for The concave portion 72 is recessed in a cocoon shape from the side surface facing the end plate 3 toward the single battery cell group 2 in the flat plate portion 71 of the holder member 7 . Although the entire holder member 7 is made of resin, at least the recess 72 has flexibility.

The flat plate portion 71 of the holder member 7 is formed to have substantially the same external shape as the inner side surface 3 a of the end plate 3 . Cutout portions 73 are provided at the four corners of the flat plate portion 71 to expose the bolt insertion holes 31 arranged at the four corners of the end plate 3 . Further, each of the outer peripheral edges of the four sides of the flat plate portion 71 excluding the notch portion 73 is formed so as to be bent toward the end plate 3 respectively. Accordingly, fitting ribs 74 that can be fitted along the outer peripheral edges of the four sides of the end plate 3 are provided on the outer peripheral edges of the four sides of the flat plate portion 71 . The holder member 7 can be held in contact with the inner surface 3 a of the end plate 3 by fitting the fitting rib 74 along the outer peripheral edge of the end plate 3 .

The two first springs 61 are housed side by side in the width direction (D2 direction) of the battery module 1 from the end plate 3 side in the recess 72 of the holder member 7 . Here, the inner surface 3a of the end plate 3 has a support projection 32 projecting in the same cocoon shape as the recess 72 toward the holder member 7 in the central region corresponding to the recess 72 of the holder member 7. . Therefore, when the holder member 7 comes into contact with the inner side surface 3 a of the end plate 3 , the support projection 32 of the end plate 3 enters into the recess 72 accommodating the first spring 61 , thereby supporting the first spring 61 . It is sandwiched and held between the bottom wall 72 a of the recess 72 . At this time, the first spring 61 inside the recess 72 is not compressed at all, as shown in FIG. 5, and does not generate any elastic repulsive force.

The four second springs 62 are attached to the side surface of the flat plate portion 71 of the holder member 7 on the single battery cell group 2 side. The flat plate portion 71 of the holder member 7 has spring holding portions 75 at positions adjacent to the four cutout portions 73 around the recess 72 . The spring holding portion 75 holds the base portion 621 of the second spring 62 . Thereby, the second spring 62 is held so as to protrude from the flat plate portion 71 of the holder member 7 toward the single battery cell group 2 . These four second springs 62 are arranged so as to exert elastic repulsive force toward positions corresponding to the four corners of the surface of the unit cell 21 facing the end plate 3 .

Here, the positional relationship between the first spring 61 and the second spring 62 is set as follows. That is, neither the first spring 61 nor the second spring 62 held by the end plate 3 by the holder member 7 is compressed (the end plate 3 is not yet in contact with the single battery cell group 2 and elastic rebound is not applied). In the state where no force is generated), the tip portion of the second spring 62 directed toward the unit cell group 2 is at a position that protrudes toward the unit cell group 2 more than the first spring 61 does. Therefore, when the end plate 3 is gradually brought closer to the unit cell group 2, the second spring 62 comes into contact with the unit cell group 2 before the first spring 61 and is compressed. An elastic repulsive force is applied to the

Next, an example of the procedure for configuring the battery module 1 will be described.
First, between a pair of end plates 3 and 4, a unit cell group 2 in which a plurality of unit cells 2 are stacked with separators interposed therebetween is placed on the end plate 4 side. Next, the end plate 3 holding the spring members 6 (two first springs 61 and four second springs 62) by the holder member 7 is brought into contact with the unit cell group 2, and bolts 51 The end plates 3, 4 are fixed to the tie rods 5.

At this time, the second spring 62 that comes into contact before the first spring 61 is slightly compressed to generate an elastic repulsive force and apply a predetermined initial load to the unit cell group 2 . The initial load at this time is a relatively small load that can maintain the stacked state of the unit cells 21, and does not apply a large initial load that strongly compresses the unit cell group 2 as in the conventional case.

The unit cell group 2 maintains the stacked state of the unit cells 21 due to the load applied by the second spring 62, and is brought into the initial stacked state. In this way, the second spring 62, which has a relatively smaller spring constant than the first spring 61, comes into contact with the single battery cell group 2 first to support the single battery cell group 2, so that the single battery cell group The single battery cell group 2 can be stacked between the end plates 3 and 4 without applying a large initial load to the single battery cell group 2 .

In this initial stacking state of the unit cell group 2 , the first spring 61 is not in contact with the bottom wall 72 a of the recess 72 , or even if it abuts, the unit cell group 2 is substantially loaded. not given. That is, in the initial stacking state of the unit cell group 2, as shown in FIG. 8, the first spring 61 is in the stroke area on the left side of the P1 position where the load starts to be applied, and the second spring 62 mainly acts on the unit cells. A load is applied to the cell group 2 . Therefore, the load applied by the first spring 61 to the unit cell group 2 at this time is 0 or close to 0. Therefore, an unreasonable load is not applied to the single battery cell group 2 in the non-expanded state, which does not require a large load.

Further, the second springs 62 shown in this embodiment are provided at the four corners of the surface facing the end plate 3 with respect to the unit cell 21 arranged at the end portion of the unit cell group 2 on the end plate 3 side. It abuts and applies a load to the unit cell group 2 via the unit cell 21 . Since the four corners of the unit cell 21 are relatively strong portions, the second springs 62 can press the relatively strong portions against the unit cell group 2 and have a small spring constant. Even the second springs 62 can stably support the cell group 2 .

Next, a case where the unit cell 21 expands due to charge/discharge or deterioration will be described with reference to FIGS. 6 and 7. FIG. FIG. 6 is a cross-sectional view showing the battery module when the unit cells are inflated, cut along the same portion as line AA in FIG. FIG. 7 is a cross-sectional view showing the battery module when the unit cells are not expanded, cut along the same portion as the BB line in FIG.
As shown in FIGS. 6 and 7, when the unit cell 21 expands, the unit cell group 2 expands along the stacking direction as the internal pressure of the unit cell 21 rises, as indicated by the white arrow in the figure. , a load is applied to the end plate 3 by increasing the internal pressure. The second spring 62 , which applies a load to maintain the initial stacking state of the unit cell group 2 , is gradually compressed by the load due to the increase in the internal pressure of the unit cell group 2 .

As the unit cell group 2 expands due to the expansion of the unit cells 21, the second spring 62 continues to be further compressed, gradually approaching the elastic limit. However, the first spring 61 is arranged so as to contact the unit cell group 2 and be pressed and compressed by the unit cell group 2 before the second spring 62 reaches its elastic limit. That is, the single battery cell group 2 abutting against the bottom wall 72a of the recess 72 of the holder member 7 bends the recess 72 as it further expands, and the first spring 61 accommodated in the recess 72 ends. Compress towards plate 3. As a result, the first spring 61 is compressed by the unit cell group 2 to generate an elastic repulsive force before the second spring 62 reaches its elastic limit, and the second spring 62 applies the elastic repulsive force to the unit cell group 2 . A load is started to be applied to the unit cell group 2 without interrupting the load applied (position P1 in FIG. 8).

When the single battery cell group 2 expands further, eventually the load applied to the single battery cell group 2 by the first spring 61 is greater than the load applied by the second spring 62 to the single battery cell group 2. above (P2 position in FIG. 8). As shown in FIG. 8, the load (elastic repulsive force) with respect to the stroke when the first spring 61 is compressed is larger than the load (elastic repulsive force) with respect to the stroke when the second spring 62 is compressed. The load that the spring 61 can apply to the single battery cell group 2 is larger than the load that the second spring 62 can apply to the single battery cell group 2 . This first spring 61 can apply a load capable of resisting the load acting on the end plate 3 due to the increase in the internal pressure of the unit cell 21 when it expands. Therefore, after the load applied to the single cell group 2 by the first spring 61 exceeds the load applied to the single cell group 2 by the second spring 62 (the right side of the P2 position in FIG. 8) stroke region), the first spring 61 applies a load to the unit cell group 2 to receive a large load due to the rise in the internal pressure of the unit cell 21, and the load counteracting the load is applied to the unit cell Assigned to the cell group 2.

At this time, the first spring 61 does not absorb the large load due to the increase in the internal pressure of the unit cell 21 as in the conventional case, but rather applies a load to the unit cell group 2 that opposes the load. This is to suppress the expansion of the single battery cell group 2 . For this reason, the spring member 6 is configured such that the first spring 61 and the second spring 62 having relatively different spring constants apply loads to the single battery cell group 2 , respectively, so that after the internal pressure rises from a relatively small initial load, can accommodate load fluctuations over a relatively large load of In addition, even if the single battery cell group 2 extends to the maximum extent, the single battery cell group 2 remains within the gap between the pair of end plates 3 and 4, and the gap between the end plates 3 and 4 is the same as that of the tie rod 5. The length L1 is maintained.

According to this battery module 1 , between the pair of end plates 3 and 4 , it is possible to easily cope with load fluctuations applied to the end plates 3 from the initial load to the load due to the increase in the internal pressure of the single cell 21 . Since a large compressive initial load is not applied to the unit cell group 2, a stacking facility and a stacking process for applying an initial load to the unit cell group 2 are not required. can also be increased.

In addition, the battery module 1 does not need to add a separate structure such as a bending structure or a sliding structure to the fixed points of the end plates 3 and 4, as long as it has the minimum strength capable of holding the unit cell group 2. Therefore, the structure can be simple.

Furthermore, the first spring 61 having a relatively large spring constant shown in this embodiment is accommodated in the recess 72 of the holder member 7 and applies a load to the single battery cell group 2 via the bottom wall 72a of the recess 72. Therefore, it does not come into direct contact with the unit cell 21 . Therefore, it is possible to avoid the possibility that the unit cell 21 is damaged by the load of the first spring 61 .

In this embodiment, the spring member 6 is arranged only on one end plate 3 side of the pair of end plates 3 and 4. may be placed. However, when the spring member 6 is arranged only on one end plate 3 side as shown in this embodiment, the single cell group 2 is supported by the inner surface 4a of the other end plate 4 which does not have the spring member. It can be used as a reference plane when Therefore, from the viewpoint of supporting the unit cell group 2 more stably, it is desirable to dispose the spring member 6 only on one of the pair of end plates 3 and 4 .

REFERENCE SIGNS LIST 1 battery module 2 unit cell group 21 unit cell 3, 4 end plate 3a inner surface (of end plate) 6 spring member 61 first spring 62 second spring 5 tie rod (interval holding member)
7 holder member 71 flat plate portion 72 recessed portion

Claims (6)

A unit cell group composed of a plurality of stacked unit cells;
a pair of end plates respectively arranged at both ends in the stacking direction of the unit cell group;
A spring member provided between the unit cell group and at least one of the pair of end plates and capable of applying a load in a direction to press the unit cell group,
The spring member includes a first spring arranged at a position corresponding to a central region of the unit cell and a second spring arranged around the first spring,
The first spring is a spring capable of applying a load to the unit cell group against a load acting on the end plate due to an increase in internal pressure during expansion of the unit cell,
The second spring is a spring capable of applying a load corresponding to a load required to maintain the initial stacked state to the unit cell group,
the spring constant of the first spring is greater than the spring constant of the second spring;
The battery module, wherein a load applied to the unit cell group by the second spring is larger than a load applied to the unit cell group by the first spring in a non-expanded state of the unit cells. . A unit cell group composed of a plurality of stacked unit cells;
a pair of end plates respectively arranged at both ends in the stacking direction of the unit cell group;
A spring member provided between the unit cell group and at least one of the pair of end plates and capable of applying a load in a direction to press the unit cell group,
The spring member includes a first spring arranged at a position corresponding to a central region of the unit cell and a second spring arranged around the first spring,
The first spring is a spring capable of applying a load to the unit cell group against a load acting on the end plate due to an increase in internal pressure during expansion of the unit cell,
The second spring is a spring capable of applying a load corresponding to a load required to maintain the initial stacked state to the unit cell group,
the spring constant of the first spring is greater than the spring constant of the second spring;
A holder member disposed between the end plate on which the spring member is provided and the unit cell group and holding the spring member,
The holder member includes a flat plate portion that contacts along the inner surface of the end plate and holds the second spring between the single battery cell group and a flat plate portion that faces the single battery cell group. a flexible recess that is provided to project from the end plate and that accommodates and holds the first spring between the end plate and the battery module. A unit cell group composed of a plurality of stacked unit cells;
a pair of end plates respectively arranged at both ends in the stacking direction of the unit cell group;
A spring member provided between the unit cell group and at least one of the pair of end plates and capable of applying a load in a direction to press the unit cell group,
The spring member includes a first spring arranged at a position corresponding to a central region of the unit cell and a second spring arranged around the first spring,
The first spring is a spring capable of applying a load to the unit cell group against a load acting on the end plate due to an increase in internal pressure during expansion of the unit cell,
The second spring is a spring capable of applying a load corresponding to a load required to maintain the initial stacked state to the unit cell group,
the spring constant of the first spring is greater than the spring constant of the second spring;
The first spring is composed of a disk spring,
The battery module, wherein the second spring is a leaf spring. A holder member disposed between the end plate on which the spring member is provided and the unit cell group and holding the spring member,
The holder member includes a flat plate portion that contacts along the inner surface of the end plate and holds the second spring between the single battery cell group and a flat plate portion that faces the single battery cell group. 4. The battery module according to claim 1, further comprising a flexible concave portion which is provided so as to protrude from the end plate and which accommodates and holds the first spring between the end plate and the concave portion. The first spring is composed of a disk spring,
3. The battery module according to claim 1, wherein said second spring is a leaf spring. 6. The apparatus according to any one of claims 1 to 5 , further comprising a gap holding member arranged across the opposing inner surfaces of the pair of end plates and holding the gap between the pair of end plates at a constant gap. battery module.

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