JP2020205139A - Battery pack - Google Patents

Abstract

To provide a battery pack capable of receiving a battery cell in a case by using the space in the case effectively, while improving endurance.SOLUTION: Multiple cylindrical battery cells 12 received in the case 20 of a battery pack 10 have axial directions extending, respectively, in the same direction and extending in a direction orthogonal to the bottom face of the case 20. The multiple cylindrical battery cells 12 form a battery cell layer 38 where the terminal surfaces 36 are arranged side-by-side along the same plane. In the axial direction view of the battery cell layer 38, the battery cells 12 are arranged in zigzag, and a convex polygonal is formed by connecting the centers of the terminal surfaces 36 of the battery cells 12 placed in the periphery. In the zigzag arrangement, the battery cell 12 is not placed on the farther inside than the battery cell 12 in the periphery, and a cell non-arrangement region 12a for disposing a shank 14 is provided. At least one of both ends of the shank 14, in the extension direction along the axial direction, is supported by the case 20.SELECTED DRAWING: Figure 3

Description

The present invention relates to a removable battery pack in which a plurality of battery cells are housed in a case.

For example, as a detachable battery pack that is detachably mounted on an electric vehicle or the like, the one described in Patent Document 1 is known. In this battery pack, a plurality of columnar battery cells are housed in a case. Specifically, a plurality of battery cells are arranged in the case so that their respective axial directions are along the bottom surface of the case, and the battery cells are held by the cell holder in a state of being stacked (bale-stacked) in the radial direction. ing. At this time, by stacking the plurality of battery cells so as to be zigzag with respect to the bottom surface of the case, it is possible to prevent the battery cells from being crushed by a load in the radial direction and to protect the battery cells. ing.

Japanese Patent No. 4761726

In the above battery pack, it is difficult to effectively utilize the space in the case to accommodate the battery cells because a gap is formed between the plurality of battery cells stacked in a zigzag pattern and the case. .. Further, in order to maintain good performance in a state where a plurality of battery cells are stacked in the radial direction as described above, a cell holder having high strength and high rigidity is required, so that the durability against the drop impact of the battery pack is improved. It is not easy to increase.

Therefore, an object of the present invention is to provide a battery pack capable of effectively utilizing the space in the case to accommodate the battery cells in the case and to improve the durability.

One aspect of the present invention is a detachable battery pack in which a plurality of battery cells which are columnar and have terminal surfaces provided at both ends in the axial direction are housed in a case, and each of the plurality of battery cells. The axial direction is along the same direction and along the direction orthogonal to the bottom surface of the case, and the plurality of battery cells form a battery cell layer in which the terminal surfaces of each other are arranged along the same plane. However, in the axial view of the battery cell layer, the shape in which the battery cells are staggered and formed by connecting the centers of the terminal surfaces of the battery cells arranged on the outer peripheral portion is a convex polygonal shape. In the staggered arrangement, a cell non-arrangement region in which the battery cell is not arranged is provided inside the battery cell in the outer peripheral portion, a shaft portion is arranged in the cell non-arrangement region, and the shaft portion is formed. At least one of both ends in the extending direction along the axial direction is supported by the case.

In this battery pack, the axial directions of the plurality of battery cells are along the same direction and along the orthogonal direction with respect to the bottom surface of the case. Further, in the axial view of the battery cell layer, the shape in which the battery cells are staggered and formed by connecting the centers of the terminal surfaces of the battery cells arranged on the outer peripheral portion is a convex polygon. By arranging a plurality of battery cells as described above, it is possible to prevent the formation of extra space between the battery cells or between the battery cells and the case, so that the space inside the case can be effectively used. Then, the battery cell can be housed in the case.

Moreover, in this battery pack, since the axial directions of the plurality of battery cells are arranged along the orthogonal direction with respect to the bottom surface of the case, for example, a cell holder for holding the battery cells in a radialally stacked state in the case is unnecessary. Can be. Further, in the staggered arrangement of the battery cells, a cell non-arrangement region in which the battery cells are not arranged is provided inside the battery cells on the outer peripheral portion, and the shaft portion is arranged in the cell non-arrangement region. This shaft portion extends along the axial direction of the battery cell, and at least one of both ends in the extending direction is supported by the case. As a result, the strength and rigidity of the battery pack can be increased, and in particular, the strength and rigidity in the direction orthogonal to the bottom surface of the case can be effectively improved. Therefore, the durability against drop impact, vibration, etc. applied from the bottom of the battery pack can be improved.

It is the schematic perspective view explaining the appearance of the battery pack which concerns on embodiment of this invention. FIG. 5 is a cross-sectional view taken along the line II-II of the battery pack of FIG. It is an exploded perspective view of the battery pack of FIG. FIG. 4A is an explanatory diagram illustrating the relationship between the positive electrode group on the axially upper end surface of the battery cell layer, the negative electrode group, and the lead plate, and FIG. 4B is a positive electrode on the axially lower end surface of the battery cell layer. It is explanatory drawing explaining the relationship between a group, a negative electrode group, and a lead plate. It is an exploded perspective view of the battery pack which concerns on the modification.

A suitable embodiment of the battery pack according to the present invention will be described in detail with reference to the accompanying drawings. In the following figures, components having the same or similar functions and effects may be designated by the same reference numerals, and repeated description may be omitted.

The battery pack 10 shown in FIG. 1 is, for example, detachable (portable) which is detachably mounted on a mounting body which is an electric vehicle such as an electric assisted bicycle, an electric motorcycle, or an electric vehicle, although none of them is shown. It can be suitably applied as a power source for driving. Therefore, an example in which the battery pack 10 is mounted on the electric vehicle will be described below. However, the battery pack 10 is not particularly limited to this, and can be applied to various devices that require electric power.

Further, in the following description, the vertical direction of the battery pack 10 will be described with reference to the vertical direction (arrow X direction in FIG. 1) when the battery pack 10 is mounted on the electric vehicle. As shown in FIGS. 2 and 3, in the battery pack 10, a plurality of battery cells 12, a shaft portion 14, a holding member 16 for holding the battery cells 12, and a battery management device (BMU) 18 are provided in a case 20. A connector 22 is provided so as to be housed and partially exposed from the case 20.

The case 20 constitutes the exterior of the battery pack 10, and includes an outer shell case 24, a bottom case 26, and a top case 28. The outer shell case 24 has a bottomed tubular shape that forms a side surface of the case 20, the upper end (arrow X1 side end) is closed by the closing portion 30, and the lower end (arrow X2 side end) is open. The outer shell case 24 can be formed by, for example, extrusion molding or impact molding. A through hole 30a is formed in the closed portion 30 of the outer shell case 24, and the shaft portion 14 is inserted into the through hole 30a.

The bottom case 26 is fitted into the opening at the lower end of the outer shell case 24, for example, to close the opening and form the bottom surface of the case 20. The terminal portion 22a of the connector 22 is exposed to the outside of the case 20 through the notch 26a provided in the bottom case 26. The bottom case 26 and the outer shell case 24 are sealed by a sealing member 32.

The top case 28 is provided with a handle 34 on the upper end side thereof, which can be gripped by, for example, a user of the battery pack 10. Further, the lower end surface of the top case 28 faces the closing portion 30 of the outer shell case 24, and the upper end side of the shaft portion 14 inserted into the through hole 30a of the closing portion 30 is fixed. The details of the relationship between the shaft portion 14 and the case 20 will be described later.

Each battery cell 12 is columnar and is provided with terminal surfaces 36 (FIGS. 4A and 4B) having different positive and negative signs at both ends in the axial direction. Hereinafter, the axial direction of the battery cell 12 is also simply referred to as an axial direction. The plurality of battery cells 12 in the case 20 are arranged so that their respective axial directions are along the same direction and these axial directions are orthogonal to the bottom surface of the case 20, that is, along the vertical direction (arrow X direction). ing. A lithium ion secondary battery can be mentioned as a preferable type of the battery cell 12, but the battery cell 12 is not particularly limited to this, and for example, a secondary battery such as a nickel hydrogen battery or a nickel cadmium battery may be used. ..

The plurality of battery cells 12 form a battery cell layer 38 in which the terminal surfaces 36 of each other are arranged so as to be arranged along the same plane. In the present embodiment, as shown in FIG. 4A, one battery cell layer 38 is formed from the 36 battery cells 12. Further, as shown in FIGS. 2 and 3, three battery cell layers 38a are contained in the case 20 from the lower end side (arrow X2 side) in the vertical direction (axial direction) toward the upper end side (arrow X1 side). , 38b, 38c are stacked and housed in this order. That is, a total of 108 battery cells 12 are housed in the case 20. In the following, when the three battery cell layers 38a, 38b, and 38c are not particularly distinguished, they are also collectively referred to as the battery cell layer 38.

As shown in FIGS. 4A and 4B, in the axial view of the battery cell layer 38, the battery cells 12 are staggered and formed by connecting the centers of the terminal surfaces 36 of the battery cells 12 arranged on the outer peripheral portion. The shape is a convex polygon. Further, in the staggered arrangement, a cell non-arrangement region 12a in which the battery cell 12 is not arranged is provided inside the battery cell 12 in the outer peripheral portion, and the shaft portion 14 is arranged in the cell non-arrangement region 12a. In other words, in the staggered arrangement, the shaft portion 14 is arranged instead of the battery cell 12 in the portion where the battery cell 12 is arranged except the portion where the battery cell 12 is arranged on the outer peripheral portion.

In the present embodiment, the convex polygon formed by connecting the centers of the terminal surfaces 36 of the battery cells 12 arranged on the outer peripheral portion as described above is the extending direction (axial direction, arrow X direction) of the shaft portion 14. It is assumed that it is a regular hexagon having a rotationally symmetric shape with the axis of rotation as the axis of rotation. That is, in the axial direction, the shaft portion 14 is arranged at the center, which is the point where the diagonal lines of the regular hexagons intersect. The convex polygon formed by connecting the centers of the terminal surfaces 36 of the battery cells 12 arranged on the outer peripheral portion is not limited to a regular hexagon, but may be various polygons having an internal angle smaller than 180 °. be able to. Further, the shaft portion 14 may be arranged at a portion other than the center of the convex polygon.

In the staggered arrangement of the present embodiment, for example, as shown in FIG. 4A, a row L is formed from a plurality of battery cells 12 arranged along the extending direction (arrow Y direction) of one side of the regular hexagon. As a result, the centers of the terminal surfaces 36 are arranged so as to be offset in the arrow Y direction between the rows L adjacent to each other in the direction orthogonal to the extending direction of the side (arrow Z direction).

In the battery cell layer 38, in the axial view thereof, from the positive electrode group 36a composed of the plurality of positive electrode side terminal surfaces 36 arranged adjacent to each other and the plurality of negative electrode side terminal surfaces 36 arranged adjacent to each other. The negative electrode groups 36b are alternately arranged in the circumferential direction (hereinafter, also simply referred to as the circumferential direction) of the convex polygon (regular hexagon) centered on the shaft portion 14. In the present embodiment, each of the positive electrode group 36a and the negative electrode group 36b is composed of six terminal surfaces 36. Further, each of the battery cell layers 38 is provided with three positive electrode groups 36a and three negative electrode groups 36b.

At both ends of the battery cell layer 38 in the axial direction, terminal surfaces 36 having the same poles are connected in parallel to an electrode group pair 40 formed of a positive electrode group 36a and a negative electrode group 36b adjacent to each other in the circumferential direction. In addition, a lead plate 42 for connecting the terminal surfaces 36 of different electrodes in series is provided. Each terminal surface 36 and the lead plate 42 are electrically connected by welding or the like.

For example, as shown in FIG. 4A, two lead plates 42 and two output plates 44a and 44b are provided on the upper end surface 39a of each battery cell layer 38. Each of the lead plates 42 connects the terminal surfaces 36 of the positive electrode group 36a in parallel, connects the terminal surfaces 36 of the negative electrode group 36b in parallel, and connects the terminal surfaces 36 of the electrode group pair 40 including the positive electrode group 36a and the negative electrode group 36b. Connect them in series.

One output plate 44a connects the terminal surfaces 36 of the remaining positive electrode group 36a in parallel. The other output plate 44b connects the terminal surfaces 36 of the remaining negative electrode group 36b in parallel. Each of the lead plate 42 and the output plates 44a and 44b is insulated by, for example, providing an insulating member (not shown) between them or arranging them at intervals from each other.

As shown in FIG. 4B, three lead plates 42 are provided on the lower end surface 49b of each battery cell layer 38. Each lead plate 42 is arranged so as to be displaced in the circumferential direction from the lead plate 42 provided on the upper end surface 39a side of the battery cell layer 38 shown in FIG. 4A. That is, on the lower end surface 39b side of the battery cell layer 38 shown in FIG. 4B, the electrode group from the battery cell 12 different from the battery cell 12 forming the electrode group pair 40 on the upper end surface 39a side of the battery cell layer 38 shown in FIG. 4A. Pair 40 is formed. Each of these lead plates 42 is insulated by, for example, providing an insulating member (not shown) between them or arranging them at intervals from each other. The battery cell layer 38 is provided with two lead plates 42 and two output plates 44a and 44b on the lower end surface 39b instead of the upper end surface 39a, and three on the upper end surface 39a instead of the lower end surface 39b. Lead plate 42 may be provided.

Of the three battery cell layers 38 stacked in the axial direction, one of the output plates 44a and 44b provided on the battery cell layer 38c arranged at the upper end and the battery cell layer 38a arranged at the lower end. One of the output plates 44a and 44b can be electrically connected to the external BMU18 and the like of the three battery cell layers 38 via, for example, wiring (not shown).

The other of the output plates 44a and 44b provided on the battery cell layer 38c arranged at the upper end is the other of the output plates 44a and 44b of the adjacent battery cell layer 38b via, for example, wiring (not shown). It is electrically connected. The other of the output plates 44a and 44b of the battery cell layer 38b and the other output plates 44a and 44b of the battery cell layer 38a arranged at the lower end can be electrically connected to each other via wiring (not shown). That is, the positive electrode group 36a and the negative electrode group 36b of the three battery cell layers 38 are all connected in series via the lead plate 42 and the output plates 44a and 44b.

As shown in FIGS. 2 and 3, each battery cell layer 38 is held in the case 20 by a set of holding members 16 that sandwich the battery cell layer 38 from both ends in the axial direction. That is, the lead plate 42 and the output plates 44a and 44b are interposed between the battery cell layer 38 and the holding member 16. The holding member 16 is a convex polygon (regular hexagon) formed along the outer circumference of the battery cell layer 38 in the axial direction, and the shaft portion 14 is inserted into the center which is the intersection of the diagonal lines. The hole 16a is formed. In the present embodiment, the shape of the case 20 in the axial direction is also a convex polygon formed along the outer circumference of the battery cell layer 38.

Further, on the outer peripheral portion of the holding member 16 and the peripheral edge portion of the insertion hole 16a, for example, the above wiring electrically connected to the lead plate 42 and the output plates 44a and 44b, the voltage detection line and the temperature of the battery cell 12 A notch 16b is formed in which a detection line or the like (not shown) is arranged inside. By arranging the above wiring or the like inside the notch 16b, the space inside the case 20 can be effectively used, and even when an external force is applied to the battery pack 10, the above wiring or the like can be used. Can be well protected.

As shown in FIGS. 2 and 3, the BMU 18 is arranged, for example, at the lower end portion in the case 20. Although not shown, the BMU 18 includes a control unit that controls charging and discharging of a plurality of battery cells 12, a communication unit that communicates with an electric vehicle and a charging device, a temperature and voltage of the battery cells 12, and the like. It has a storage unit for storing. The shape of the BMU 18 in the axial direction is not particularly limited, but in the present embodiment, it is a convex polygon having a similar relationship with the convex polygon of the holding member 16 and having a smaller area than the holding member 16. ing. In the axial direction, a through hole 18a is provided in the center of the BMU 18, and a flange portion 50a provided at the lower end of the shaft portion 14 and an upper end portion 22b of the connector 22 are arranged inside the through hole 18a. ..

The shaft portion 14 is configured by connecting a first shaft member 50 extending upward from the lower end side in the case 20 and a second shaft member 52 extending downward from the upper end in the case 20. The first shaft member 50 has a rod-shaped portion 50b having an outer diameter substantially the same as the outer diameter of the battery cell 12, and a flange portion 50a provided at the lower end of the rod-shaped portion 50b. The outer diameter of the flange portion 50a is set to be larger than the diameter of the insertion hole 16a of the holding member 16, and the upper end surface of the flange portion 50a is the insertion hole 16a of the holding member 16 provided on the lower end surface side of the battery cell layer 38a. Contact the peripheral edge of the. A female screw 50c is provided at the upper end of the rod-shaped portion 50b.

The second shaft member 52 has a rod-shaped portion 52a having an outer diameter substantially the same as the outer diameter of the battery cell 12, and a flange portion 52b provided at the upper end of the rod-shaped portion 52a. At the lower end of the rod-shaped portion 52a of the second shaft member 52, a male screw 52c screwed with the female screw 50c provided at the upper end of the rod-shaped portion 50b of the first shaft member 50 is provided. Further, a female screw 52d (see FIG. 2) into which the bolt 54 is screwed is provided at the upper end of the rod-shaped portion 52a of the second shaft member 52. The outer diameter of the flange portion 52b is set to be larger than the diameter of the through hole 30a of the closing portion 30, and the lower end surface of the flange portion 52b abuts on the peripheral edge portion of the through hole 30a on the upper end surface of the closing portion 30. The lower end surface of the flange portion 52b and the upper end surface of the closing portion 30 are sealed by a sealing member 56.

As shown in FIG. 2, the top case 28 is provided with a through hole 28a through which the bolt 54 is inserted in a portion of the second shaft member 52 facing the female screw 52d, and the head of the bolt 54 is provided above the through hole 28a. A counterbore portion 28b for accommodating the portion is provided. Further, on the lower end side of the top case 28, a recess 28c that is recessed upward is provided in a portion of the closing portion 30 that faces the through hole 30a. The depth of the recess 28c is set to be substantially the same as the thickness of the flange portion 52b of the second shaft member 52.

As a result, the flange portion 52b is sandwiched between the inner bottom surface of the recess 28c of the top case 28 and the upper end surface of the closing portion 30 by the screwing of the bolt 54 and the female screw 52d of the second shaft member 52. That is, the upper end of the shaft portion 14 is connected to the case 20. The lower end portion may be connected to the bottom case 26 or the like of the case 20 instead of the upper end portion of the shaft portion 14, or both the upper end portion and the lower end portion of the shaft portion 14 may be connected to the case 20. ..

Further, by providing the shaft portion 14 as described above, the holding member 16 and the closing portion 30 are interposed between the flange portion 50a of the first shaft member 50 and the flange portion 52b of the second shaft member 52. The three battery cell layers 38 are sandwiched in a state of being stacked in the axial direction. In other words, the three battery cell layers 38 are fixed by the shaft portion 14 and the holding member 16 in a state where the relative movement with respect to the case 20 is restricted.

As shown in FIGS. 2 and 3, the connector 22 is provided at a position where at least a part overlaps the shaft portion 14 in the extending direction view of the shaft portion 14, and a plurality of battery cells 12 are electrically connected to the outside of the case 20. Can be connected. Specifically, the connector 22 has an upper end portion 22b having a larger area than the notch 26a of the bottom case 26 and a terminal portion 22a protruding downward from the upper end portion 22b in the axial direction.

The upper end portion 22b is sandwiched between the lower end surface of the flange portion 50a of the first shaft member 50 and the peripheral edge portion of the notch 26a of the bottom case 26, so that the terminal portion 22a is sandwiched between the notch 26a and the case 20. Exposed to the outside of. The upper end portion 22b and the bottom case 26 are sealed by a sealing member 58. By providing the connector 22 in this way, the lower end portion of the shaft portion 14 is supported by the bottom case 26 via the connector 22. As described above, the upper end portion of the shaft portion 14 is supported by the outer shell case 24 and the top case 28 via the bolt 54. That is, in the present embodiment, both ends of the shaft portion 14 in the extending direction are supported by the case 20.

In the battery pack 10 according to the present embodiment, which is basically configured as described above, the battery pack 10 can be carried by the user, for example, by gripping the handle 34. By carrying the battery pack 10 in this way, the battery pack 10 can be attached to and detached from the electric vehicle and the charging device, although none of them are shown.

That is, by connecting the terminal portion 22a of the connector 22 of the battery pack 10 to the battery connection port (not shown) of the electric vehicle, a plurality of battery cells 12 can be electrically connected to the electric vehicle via the BMU 18. .. As a result, the plurality of battery cells 12 are discharged. On the other hand, by connecting the terminal portion 22a of the connector 22 to the battery connection port (not shown) of the charging device, a plurality of battery cells 12 can be electrically connected to the charging device via the BMU 18. As a result, the plurality of battery cells 12 are charged.

From the above, in the battery pack 10, the axial directions of the plurality of battery cells 12 are along the same direction and along the orthogonal direction with respect to the bottom surface of the case 20. Further, in the axial view of the battery cell layer 38, the shape in which the battery cells 12 are staggered and formed by connecting the centers of the terminal surfaces 36 of the battery cells 12 arranged on the outer peripheral portion is a convex polygon. By arranging the plurality of battery cells 12 as described above, it is possible to prevent the formation of extra space between the battery cells 12 or between the battery cells 12 and the case 20, and thus it is possible to prevent the formation of extra space in the case 20. The battery cell 12 can be housed in the case 20 by effectively utilizing the space.

Moreover, in this battery pack 10, since the axial directions of the plurality of battery cells 12 are arranged along the orthogonal directions with respect to the bottom surface of the case 20, for example, the battery cells 12 are held in a state of being stacked in the radial direction in the case 20. It is possible to eliminate the need for a cell holder or the like (not shown). Further, in the staggered arrangement of the battery cells 12, a cell non-arrangement region 12a in which the battery cells 12 are not arranged is provided inside the battery cells 12 on the outer peripheral portion, and the shaft portion 14 is arranged in the cell non-arrangement region 12a. Will be done. The shaft portion 14 extends along the axial direction of the battery cell 12, and both ends in the extending direction are supported by the case 20.

As a result, the strength and rigidity of the battery pack 10 can be increased, and in particular, the strength and rigidity in the direction orthogonal to the bottom surface of the case 20 can be effectively improved. Therefore, for example, even if the battery pack 10 holding the handle 34 is dropped while being carried and collides with the ground from the bottom case 26 side, the durability against the drop impact applied from the bottom of the battery pack 10 can be improved. it can. Similarly, for example, even if the electric vehicle equipped with the battery pack 10 vibrates in the vertical direction, the durability of the battery pack 10 against the vibration can be improved.

As a result, according to the battery pack 10 according to the present embodiment, it is possible to effectively utilize the space in the case 20 to accommodate the battery cell 12 in the case 20 and to improve the durability.

In the battery pack 10 according to the above embodiment, a plurality of battery cells 12 can be electrically connected to the outside of the case 20 at a position where at least a part of the shaft portion 14 overlaps with the shaft portion 14 in the extending direction view. The connector 22 to be used is arranged. In this case, the connector 22 can be provided in the portion of the battery pack 10 where the shaft portion 14 has increased the rigidity and strength in the axial direction. Therefore, when the terminal portion 22a of the connector 22 is axially inserted and removed from the battery connection port of the electric vehicle or the charging device, an axial load is repeatedly applied to the battery pack 10 via the connector 22. Even if this is done, it is possible to prevent damage to the portion of the battery pack 10 that supports the connector 22 and the like. Thereby, the durability of the battery pack 10 can be improved better.

In the battery pack 10 according to the above embodiment, the convex polygon is a rotationally symmetric shape having the extending direction of the shaft portion 14 as the rotation axis. In this case, for example, even if the battery pack 10 is rotated about the extending direction of the shaft portion 14, the position of the connector 22 provided at the lower end of the shaft portion 14 does not change significantly with respect to the bottom portion of the battery pack 10. .. Therefore, it becomes easy to relax the restriction on the direction in which the battery pack 10 is attached / detached to / from the accommodating portion of the electric vehicle or the charging device, and it is possible to facilitate the attachment / detachment work of the battery pack 10.

In the battery pack 10 according to the above embodiment, in the axial view of the battery cell layer 38, the positive electrode group 36a composed of a plurality of terminal surfaces 36 on the positive electrode side arranged adjacent to each other is arranged adjacent to each other. Negative electrode groups 36b composed of a plurality of terminal surfaces 36 on the negative electrode side are alternately arranged in the circumferential direction of a convex polygon centered on the shaft portion 14, and at each of both ends in the axial direction of the battery cell layer 38, The terminal surfaces 36 of the same electrode are connected in parallel to the electrode group pair 40 formed of the positive electrode group 36a and the negative electrode group 36b adjacent to each other in the circumferential direction of the convex polygon, and the terminal surfaces 36 of different electrodes are connected in series. It was decided that a lead plate 42 to be connected was provided. In this case, the plurality of battery cells 12 housed in the case 20 can be connected in parallel or in series with a simple configuration using the lead plate 42, and the electric power of these battery cells 12 can be effectively obtained. It will be possible. However, the method of connecting the plurality of battery cells 12 housed in the case 20 is not particularly limited to the above.

In the battery pack 10 according to the above embodiment, the shape of the case 20 in the axial direction is a convex polygon formed along the outer circumference of the battery cell layer 38. In this case, it is possible to prevent the formation of an extra space between the side surface of the case 20 and the side surface of the battery cell 12 in the case 20 as much as possible. Therefore, the space in the case 20 can be used more effectively, and the battery pack 10 can be effectively miniaturized.

The shape of the case 20 in the axial direction is not limited to the above-mentioned convex polygon. For example, as in the case 20 shown in FIG. 5, the shape of the case 20 in the axial direction may be a circle surrounding the outer periphery of the battery cell layer 38. In this case, the heat of the battery cell layer 38 can be transferred to the case 20 side in the space formed between the inner peripheral surface of the case 20 (outer shell case 24) and the outer surface of the battery cell layer 38. It is preferable that the heat member 60 is provided. The heat transfer member 60 is made of, for example, an elastic material such as a silicon resin that can promote heat dissipation of the battery cell 12.

In this embodiment, heat transfer members 60 are provided so as to fill the space between the inner peripheral surface of the outer shell case 24 and all the outer surfaces of the three battery cell layers 38. However, the number, shape, arrangement location, etc. of the heat transfer members 60 are not particularly limited.

By making the shape of the case 20 in the axial direction circular in this way, it is possible to further relax the restriction on the direction in which the battery pack 10 is attached to and detached from the accommodating portion of the electric vehicle or the charging device. Further, the heat transfer member 60 can be arranged in the space formed between the inner peripheral surface of the case 20 and the outer surface of the battery cell layer 38, whereby the battery cell 12 rises due to charging and discharging. Even when heated, the heat of the battery cell 12 can be efficiently conducted to the case 20 via the heat transfer member 60 to dissipate heat. Further, since the heat transfer member 60 is elastically deformed and the like, it becomes possible to absorb the impact load applied to the battery pack 10, so that a plurality of battery cells 12 can be protected and the durability of the battery pack 10 is further improved. It becomes possible to improve effectively.

In the battery pack 10 according to the above embodiment, a plurality of battery cell layers 38 stacked in the axial direction are housed in the case 20, and each of the battery cell layers 38 has both ends of the battery cell layer 38 in the axial direction. It was decided to be held by a set of holding members 16 sandwiched between the two. By accommodating the plurality of battery cell layers 38 in the case 20, the output of the battery pack 10 can be increased while effectively utilizing the space in the case 20. Further, by holding the battery cell layer 38 by the holding member 16, the plurality of battery cells 12 can be fixed in a state where the relative movement with respect to the case 20 is effectively regulated, so that the durability of the battery pack 10 is maintained. Can be improved. The number of battery cell layers 38 housed in the case 20 is not particularly limited, and one battery cell layer 38 or a plurality of battery cell layers 38 other than three are housed in the case 20. May be done. Further, the number of battery cells 12 housed in the case 20 and the number of battery cells 12 constituting each battery cell layer 38 are not particularly limited.

In the battery pack 10 according to the above embodiment, both ends of the shaft portion 14 in the extending direction along the axial direction are supported by the case 20. In this case, since the battery cell layer 38 or the like arranged in the case 20 can be effectively suppressed from rattling with respect to the case 20, the durability of the battery pack 10 can be further improved. However, the durability of the battery pack 10 can be sufficiently improved if at least one of both ends of the shaft portion 14 in the extending direction is supported by the case 20 without particular limitation.

The present invention is not particularly limited to the above-described embodiment, and various modifications can be made without departing from the gist thereof.

10 ... Battery pack 12 ... Battery cell 14 ... Shaft 16 ... Holding member 20 ... Case 22 ... Connector 36 ... Terminal surface 36a ... Positive electrode group 36b ... Negative electrode group 38, 38a, 38b, 38c ... Battery cell layer 40 ... Electrode group pair 42 ... Lead plate 60 ... Heat transfer member

Claims (8)

It is a removable battery pack that houses a plurality of battery cells that are columnar and have terminal surfaces at both ends in the axial direction in a case.
The axial direction of each of the plurality of battery cells is along the same direction and along the direction orthogonal to the bottom surface of the case.
The plurality of battery cells form a battery cell layer in which the terminal surfaces of the plurality of battery cells are arranged so as to be arranged along the same plane.
In the axial view of the battery cell layer, the shape in which the battery cells are staggered and formed by connecting the centers of the terminal surfaces of the battery cells arranged on the outer peripheral portion is a convex polygon.
In the staggered arrangement, a cell non-arrangement region in which the battery cell is not arranged is provided inside the battery cell in the outer peripheral portion, and a shaft portion is arranged in the cell non-arrangement region.
The shaft portion is a battery pack in which at least one of both ends in the extending direction along the axial direction is supported by the case. In the battery pack according to claim 1,
A battery pack in which a connector for electrically connecting the plurality of battery cells to the outside of the case is provided at a position where at least a part of the shaft portion overlaps with the shaft portion in the extending direction. .. In the battery pack according to claim 1 or 2.
The convex polygon is a battery pack that is a rotationally symmetric shape having the extending direction of the shaft portion as a rotation axis. In the battery pack according to claim 3,
In the axial view of the battery cell layer, a positive electrode group composed of a plurality of positive electrode side terminal surfaces arranged adjacent to each other and a negative electrode composed of a plurality of negative electrode side terminal surfaces arranged adjacent to each other. The groups are alternately arranged in the circumferential direction of the convex polygon centered on the shaft portion.
At both ends of the battery cell layer in the axial direction, the terminals having the same electrode with respect to the electrode group pair formed from the positive electrode group and the negative electrode group adjacent to the convex polygon in the circumferential direction. A battery pack provided with a lead plate that connects the surfaces in parallel and connects the terminal surfaces of different electrodes in series. In the battery pack according to any one of claims 1 to 4.
The shape of the case in the axial direction is a convex polygon formed along the outer circumference of the battery cell layer, the battery pack. In the battery pack according to any one of claims 1 to 4.
The shape of the case in the axial direction is a circle surrounding the outer periphery of the battery cell layer.
A battery pack in which a heat transfer member capable of conducting heat of the battery cell layer to the case side is provided in a space formed between the inner peripheral surface of the case and the outer surface of the battery cell layer. In the battery pack according to any one of claims 1 to 6.
A plurality of the battery cell layers laminated in the axial direction are housed in the case.
A battery pack in which each of the battery cell layers is held by a set of holding members that sandwich the battery cell layer from both ends in the axial direction. In the battery pack according to any one of claims 1 to 7.
The shaft portion is a battery pack in which both ends in the extending direction along the axial direction are supported by the case.

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