Battery pack

Abstract

To make it possible to reduce impact applied to a battery cell via a wall unit of a battery case from a surrounding member of the battery case.SOLUTION: A battery pack includes a cell laminate and a battery case. The cell laminate is configured by laminating a plurality of rectangular parallelepiped battery cells. The battery case is formed in a rectangular parallelepiped shape and stores the cell laminates. The battery case includes a first protrusion protruding from an external surface of the battery case to outside of the battery case at a position of a gap between adjacent battery cells in a lamination direction of the cell laminate.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a battery pack. [Background technology]

[0002] Patent Document 1 discloses a battery case that houses a plurality of cylindrical battery cells. Reinforcing ribs that protrude between adjacent battery cells are formed on the inner surface of the battery case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 09-086188 Summary of the Invention [Problem to be solved by the invention]

[0004] In a battery pack that includes a cell stack formed by stacking multiple battery cells each having a substantially rectangular parallelepiped shape and a battery case that houses the cell stack, there is a possibility that an impact may be applied to the battery cells from the surrounding members of the wall of the battery case that covers the cell stack through the wall. The battery pack is required to have a structure that can reduce such impacts applied to the battery cells.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a battery pack that can reduce impacts applied to battery cells from components surrounding the battery case through the wall of the battery case. [Means for solving the problem]

[0006] A battery pack according to the present disclosure includes a cell stack and a battery case. The cell stack is configured by stacking a plurality of battery cells each having a substantially rectangular parallelepiped shape. The battery case is also formed in a substantially rectangular parallelepiped shape and houses the cell stack. The battery case includes a first protrusion that protrudes from the outer surface of the battery case to the outside of the battery case at a position corresponding to a gap between adjacent battery cells in the stacking direction of the cell stack.

[0007] The battery case may include a pair of side walls extending in the stacking direction and facing the side surfaces of the cell stack, and the first protrusion may be formed on at least one of the pair of side walls.

[0008] The battery case may include a second protrusion that protrudes from the inner surface of the battery case inside the first protrusion so as to be interposed between adjacent battery cells.

[0009] The battery case may include a pair of side walls extending along the stacking direction and facing side surfaces of the cell stack. The first and second protrusions may be formed on at least one of the pair of side walls. The battery case may include a first rib formed on the outer surface of at least one of the pair of side walls on which the first and second protrusions are formed. The first rib may be formed to extend parallel to or obliquely from the stacking direction.

[0010] The first protrusions formed on at least one of the pair of side walls may be provided at each gap between adjacent battery cells in the cell stack and may be formed to extend along the gaps between the adjacent battery cells, and the first rib may be formed to bridge the gaps between the adjacent first protrusions.

[0011] The battery case may include an upper wall extending along the stacking direction and facing the upper surface of the cell stack, a third protrusion protruding from the inner surface of the upper wall so as to be interposed between adjacent battery cells, and a second rib formed on the outer surface of the upper wall, and the second rib may be formed to extend parallel to or oblique to the stacking direction.

[0012] The battery case may include a bottom wall extending along the stacking direction and facing the bottom surface of the cell stack, a third protrusion protruding from the inner surface of the bottom wall so as to be interposed between adjacent battery cells, and a second rib formed on the outer surface of the bottom wall, and the second rib may be formed to extend parallel to or oblique to the stacking direction. [Effects of the Invention]

[0013] According to the battery pack of the present disclosure, by utilizing a simple configuration of a first convex portion provided on the outer surface of the battery case, it is possible to reduce the impact applied to the battery cell from the surrounding components of the battery case through the wall portion of the battery case. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view illustrating an example of a configuration of a battery pack according to an embodiment. [Figure 2] FIG. 2 is a perspective view showing the overall configuration of the upper case shown in FIG. [Figure 3] 3 is a view of the upper case as seen from the direction of arrow A in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view taken along line CC in FIG. [Figure 5] FIG. 2 is a perspective view showing the internal structure of the upper case shown in FIG. [Figure 6] 2 is a side view of the upper case shown in FIG. 1 as seen from the side wall side. [Figure 7] FIG. 5 is an enlarged view of part D in FIG. 4. [Figure 8] FIG. 10 is a diagram for explaining an additional problem I1 according to the embodiment. [Figure 9] FIG. 10 is a diagram for explaining an additional problem I2 according to the embodiment. [Figure 10] 2 is a top view of the upper case shown in FIG. 1 as seen from the top wall side. [Figure 11] FIG. 10 is a bottom view of a lower case according to a modified example of the embodiment, as viewed from the bottom wall side. [Figure 12] 2 is a diagram for explaining the structure of the restraining member shown in FIG. 1. FIG. [Figure 13] FIG. 10 is a diagram for explaining an additional problem I3 according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Elements common to the drawings will be designated by the same reference numerals, and redundant explanations will be omitted or simplified.

[0016] 1. Overall structure of the battery pack Fig. 1 is a cross-sectional view for explaining an example of the configuration of a battery pack 1 according to an embodiment. Fig. 2 is a perspective view showing the overall configuration of an upper case 22 shown in Fig. 1. Fig. 3 is a view of the upper case 22 as viewed from the direction of arrow A in Fig. 2. More specifically, Fig. 1 is a cross-sectional view taken along line BB in Fig. 3.

[0017] The battery pack 1 includes a cell stack 10 and a battery case 20. The battery pack 1 is mounted on an electric vehicle such as a battery electric vehicle (BEV) and supplies power to the electric vehicle.

[0018] The cell stack 10 is formed by stacking a plurality of battery cells 12. Each battery cell 12 has a substantially rectangular parallelepiped shape (more specifically, for example, a substantially flattened rectangular parallelepiped shape). That is, each battery cell 12 has an outer shape in which the thickness t (length in the stacking direction D1) is smaller than the height h and width w (see FIG. 4 described below). The stacking direction D1 is the direction in which the battery cells 12 are stacked in the cell stack 10. Each battery cell 12 is, for example, a rectangular cell, but may also be, for example, a laminate type (pouch type).

[0019] More specifically, the cell stack 10 is configured by stacking multiple battery cells 12 and thin plate-shaped elastic bodies 14 alternately one by one in the stacking direction D1. That is, adjacent battery cells 12 are arranged with a gap g1 between them that corresponds to the thickness of the elastic body 14. More specifically, the elastic body 14 is, for example, an elastic heat insulating material.

[0020] The battery case 20 is formed in a substantially rectangular parallelepiped shape and houses the cell stack 10. The battery case 20 includes an upper case 22 and a lower case 24. The upper case 22 and the lower case 24 are made of, for example, resin. Alternatively, the upper case 22 may be made of, for example, metal. Similarly, the lower case 24 may also be made of, for example, metal. The battery pack 1 also includes a pair of restraining members 26 and 28.

[0021] The upper case 22 includes a top wall 30 and four side walls 32 to 38. The top wall 30 and the four side walls 32 to 38 are integrally formed. The top wall 30 faces the top surface 12a of each battery cell 12 that constitutes the cell stack 10. A pair of electrode terminals (positive and negative terminals) and a safety valve (not shown) are provided on the top surface 12a of each battery cell 12. The four side walls 32 to 38 are a pair of side walls 32 and 34 and a pair of end walls (side walls) 36 and 38. The pair of side walls 32 and 34 are formed to extend along the stacking direction D1. The pair of side walls 32 and 34 face the side surfaces 12b and 12c (see FIG. 4) of each battery cell 12 that constitutes the cell stack 10, respectively. The pair of end walls 36 and 38 are side walls located at the ends of the stacking direction D1. The pair of end walls 36 and 38 face the side surfaces 12d and 12e of the battery cells 12 located at each end of the cell stack 10, respectively.

[0022] The lower case 24 includes a bottom wall 40 that faces the bottom surface 12f of each battery cell 12 that makes up the cell stack 10, and a pair of end walls 42 and 44. The bottom wall 40 and the pair of end walls 42 and 44 are integrally formed. The pair of end walls 42 and 44 of the lower case 24 are located outward in the stacking direction D1 from the pair of end walls 36 and 38 of the upper case 22, respectively.

[0023] As shown in FIG. 1 , a restraining member 26 is press-fitted between the end wall 36 and the end wall 42. Similarly, a restraining member 28 is press-fitted between the end wall 38 and the end wall 44. The restraining members 26 and 28 are, for example, resin spacers. With this structure, a load that compresses the cell stack 10 in the stacking direction D1 (in other words, a load that restrains the multiple battery cells 12 that make up the cell stack 10) can be generated using the pair of end walls 42 and 44 of the lower case 24. In addition, with this structure, a frictional force based on the restraining load acts between the lower case 24 and the upper case 22, which is mounted on the lower case 24 and houses the cell stack 10, via the restraining members 26 and 28. This frictional force can then be used to hold the upper case 22 relative to the lower case 24.

[0024] Furthermore, the lower case 24 includes a pair of cross members 46 and 48 (see FIG. 4 ) that serve as reinforcing members. The cross member 46 covers a portion of the side wall 32 of the upper case 22 and is formed to bridge the gap between the end wall 42 and the end wall 44 of the lower case 24. Similarly, the cross member 48 covers a portion of the side wall 34 of the upper case 22 and is formed to bridge the gap between the end wall 42 and the end wall 44 of the lower case 24.

[0025] The above-described battery pack 1 includes one upper case 22 that houses one cell stack 10. Instead of this example, the "battery pack" according to the present disclosure may include multiple upper cases 22 that each house multiple cell stacks 10. For example, the multiple upper cases 22 may be mounted in parallel on the same lower case.

[0026] The top wall 30 of the upper case 22 described above also functions as a protective plate for the top surface 12a of each battery cell 12. Specifically, the top wall 30 can protect the top surface 12a of each battery cell 12 from direct contact by workers who manufacture the battery pack 1. Furthermore, when one battery cell 12 constituting the cell stack 10 generates abnormal heat, the top wall 30 can prevent high-temperature contents (heat source) that spray out of the safety valve of that battery cell 12 from adhering to surrounding battery cells 12 (i.e., suppressing chain smoke generation).

[0027] 2. First and second protrusions Fig. 4 is a cross-sectional view taken along line CC in Fig. 3. Fig. 5 is a perspective view showing the internal structure of upper case 22 shown in Fig. 1. Fig. 6 is a side view of upper case 22 shown in Fig. 1 as seen from the side of side wall 32.

[0028] The upper case 22 includes a first protrusion 50 and a second protrusion 52. The first protrusion 50 and the second protrusion 52 are integrally formed with the upper case 22. The first protrusion 50 and the second protrusion 52 are basically provided between each of the battery cells 12 in the plurality of battery cells 12 that make up the cell stack 10.

[0029] The second protrusions 52 are provided to position each battery cell 12 in the stacking direction D1. Specifically, the second protrusions 52 are formed on the inner surface of the upper case 22. In the example of the upper case 22, the second protrusions 52 are formed on the inner surfaces 32a and 34a of the pair of side walls 32 and 34, respectively. As shown in FIG. 4 , the second protrusions 52 protrude from each of the inner surfaces 32a and 34a so as to be interposed between adjacent battery cells 12 (gap g1). In other words, the second protrusions 52 overlap with the battery cells 12 in the width direction D2 of the battery cells 12.

[0030] The second protrusions 52 are formed to extend along the height direction D3 of the battery cells 12. More specifically, in the example of the upper case 22, the second protrusions 52 extend along the height direction D3 so as to cover the entire inner surfaces 32a and 34a. Alternatively, the second protrusions 52 may be provided only on a portion of each of the inner surfaces 32a and 34a in the height direction D3.

[0031] 7(A), which will be described later, a gap g2 (play) is provided between the second protrusion 52 and the battery cell 12 in the stacking direction D1. Therefore, the battery cell 12 is positioned by the second protrusion 52 while being allowed to move within the range of the gap g2. Also, a corner R, for example, is formed at the base of the second protrusion 52 relative to each of the inner surfaces 32a and 34a.

[0032] The first protrusions 50 are formed so as to protrude from the outer surface of the upper case 22 to the outside of the upper case 22 at the positions of the gaps g1 between adjacent battery cells 12 in the stacking direction D1. In the example of the upper case 22, the first protrusions 50 are formed on the outer surfaces 32b and 34b of the pair of side walls 32 and 34, respectively. As shown in FIG. 4, the first protrusions 50 protrude outward from each of the outer surfaces 32b and 34b. More specifically, as illustrated in FIG. 7(A), the width wp of the first protrusions 50 in the stacking direction D1 is, for example, equal to or less than the gap g1.

[0033] The first protrusions 50 are also formed to extend along the height direction D3 of the battery cells 12. More specifically, in the example of the upper case 22, the first protrusions 50 extend in the height direction D3 so as to cover the entire or substantially the entire outer surfaces 32b and 34b, respectively, as shown in Fig. 6. Alternatively, the first protrusions 50 may be provided only on a portion of each of the outer surfaces 32b and 34b in the height direction D3.

[0034] In the example of the upper case 22, a pair of first and second protrusions 50 and 52 are basically provided for the same gap g1 between adjacent battery cells 12. That is, the second protrusions 52 are formed on the side walls 32 and 34, respectively, inside the first protrusion 50. However, as with the second protrusion 521 (see FIG. 4) provided at the end in the stacking direction D1, the "first and second protrusions" according to the present disclosure do not necessarily have to be provided in combination. Also, instead of the example shown in FIG. 4, the first protrusion 50 may be formed on only one of the pair of side walls 32 and 34. Note that, as with the protrusion 56 (see FIG. 4) provided at the end in the stacking direction D1, a protrusion for positioning the battery cell 12 may be provided between the battery cell 12 and the case end wall (e.g., each of the end walls 36 and 38).

[0035] (effect) 7(A) and 7(B) are enlarged views of portion D in FIG. 4. FIG. 7(A) corresponds to a state in which no impact is applied to the sidewall 32 of the upper case 22 from a member surrounding the upper case 22. In contrast, FIG. 7(B) corresponds to an example in which an impact is applied to the sidewall 32 from a cross member 46, which is an example of a member surrounding the upper case 22. The load caused by the impact from the cross member 46 is transmitted to the battery cells 12 via the sidewall 32.

[0036] If the first protrusions 50 were not provided on the outer surfaces 32b of the side walls 32, the load caused by the impact from the cross members 46 would be input to the side surfaces 12b (flat surfaces) of each battery cell 12 via the side walls 32.

[0037] In contrast, in the upper case 22 according to this embodiment, the first protrusions 50 are provided on the outer surfaces 32b of the side walls 32. As a result, the cross member 46 first comes into contact with the first protrusions 50, as shown in FIG. 7B. As a result, the side walls 32 bend, and the corners 12g of the battery cells 12 come into contact with the side walls 32 before the side walls 12b. The corners 12g are geometrically more rigid than the side walls 12b. In other words, the provision of the first protrusions 50 allows the load from an impact from the cross members 46 to act on the relatively rigid corners 12g, rather than directly hitting the side walls 12b of the battery cells 12. Furthermore, as shown by the arrows labeled "load path" in FIG. 7B, the load input from the cross members 46 to the first protrusions 50 can be deflected by the side walls 32, which bend upon impact. In other words, the side walls 32, which are provided with the first protrusions 50, can absorb the load. This leads to a reduction in the load input to the battery cell 12.

[0038] As described above, the provision of the first protrusion 50 reduces the impact load applied to the battery cell 12 from surrounding components such as the cross member 46 via the side wall 32. As a result, the battery cell 12 can be protected from the impact. More specifically, damage to battery components (e.g., electrode body) inside the battery cell 12 can be reduced. The same applies to the first protrusion 50 provided on the other side wall 34.

[0039] Furthermore, according to this embodiment, the second protrusions 52 are provided on the inner surface 32a of the side wall 32. This allows the positioning of each battery cell 12 constituting the cell stack 10. As a result, it is possible to reliably ensure an insulating distance between adjacent battery cells 12. Furthermore, multiple bus bars are arranged on the top wall 30 of the upper case 22 to electrically connect the multiple battery cells 12 constituting the cell stack 10. Each of the multiple bus bars is connected to the electrode terminals of the battery cells 12 by a method such as welding. By appropriately positioning each battery cell 12 relative to the upper case 22 using the second protrusions 52, the position of the bus bars relative to each battery cell 12 is also easily determined. As a result, the weldability of the bus bars is improved. Furthermore, when the upper case 22 is made of resin, the following effect is obtained. That is, by providing the second protrusions 52, the fluidity of the resin can be improved when manufacturing the upper case 22 using an injection molding machine, compared to an example without the second protrusions 52. As a result, it is possible to suppress the occurrence of short shots while suppressing an increase in the tonnage of the injection molding machine. The same applies to the second protrusion 52 provided on the other side wall 34.

[0040] Additionally, in the upper case 22 according to this embodiment, the first protrusion 50 and the second protrusion 52 are basically provided in pairs for the same gap g1. This effectively increases the fluidity of the resin when the upper case 22 is made of resin, while achieving the above-mentioned effects (i.e., reducing the impact load on the battery cells 12 and positioning the battery cells 12).

[0041] 7(A), the width wp of the first protrusion 50 in the stacking direction D1 may be equal to or less than the gap g1 between adjacent battery cells 12. This makes it possible to make it less likely that the load caused by the impact received by the cross member 46 on the first protrusion 50 will be transmitted to the side surface 12b or 12c of the battery cell 12 (in other words, to make it easier for the load to be transmitted in a concentrated manner to the corner 12g) compared to when the width wp is greater than the gap g1.

[0042] 3. First Rib Fig. 8 is a diagram for explaining an additional problem I1 according to the embodiment. Fig. 8 is a cross-sectional view taken at the same position as Fig. 4. Here, the additional problem I1 will be explained using the side wall 32 as an example.

[0043] If the second protrusions 52 are provided on the side walls 32, a "waviness W1" may occur in the side walls 32, as shown in FIG. 8. Specifically, as will be described later with reference to FIG. 13, the upper case 22 is mounted on the lower case 24 while a restraint load is applied along the stacking direction D1 by a pair of jigs 102 to the upper case 22 housing the cell stack 10. When such a restraint load is applied, each of the second protrusions 52 receives a load in the stacking direction D1 from the surrounding battery cells 12, as shown in FIG. 8. As a result, the waviness W1 may occur. The waviness W1 then occurs along the stacking direction D1, as shown in FIG. 8. Note that if the upper case 22 is made of resin, the waviness W1 may occur not only due to the above factors but also due to warping of the side walls 32 that may occur during molding of the upper case 22.

[0044] When the above-described swell W1 occurs, the mountability of the upper case 22 to the lower case 24 decreases. In consideration of this additional problem I1, in this embodiment, the upper case 22 includes a first rib 60. The first rib 60 is formed integrally with the upper case 22. As shown in FIG. 6 , the first rib 60 is formed on the outer surface 32b of the side wall 32 on which the first protrusion 50 and the second protrusion 52 are formed. A plurality of first ribs 60 may be provided, for example.

[0045] 6, each of the first ribs 60 is formed to extend parallel to the stacking direction D1. Alternatively, each of the first ribs 60 may be formed to extend obliquely with respect to the stacking direction D1. That is, each of the first ribs 60 does not necessarily have to extend in a direction parallel to the stacking direction D1, but may also extend in a direction inclined with respect to the stacking direction D1.

[0046] More specifically, a first protrusion 50 is provided for each gap g1 between adjacent battery cells 12 in the cell stack 10, and is formed to extend along the gap g1 between the adjacent battery cells 12 (i.e., along the height direction D3). Figure 6 shows an example of three first protrusions 50 formed in this manner. In addition, each of the first ribs 60 is formed to bridge the gap between adjacent first protrusions 50.

[0047] The above-mentioned first rib 60 may be formed on the other side wall 34 in the same manner.

[0048] (effect) According to this embodiment, the first rib 60 is provided, thereby increasing the rigidity of the side wall 32 (and the side wall 34) against the swell W1. This makes it possible to effectively suppress the swell W1 that occurs in the side wall 32 (and the side wall 34) due to the presence of the second convex portion 52 described above.

[0049] 4. Third protrusion and second rib The upper case 22 further includes a third protrusion 62. The third protrusion 62 is integrally formed with the upper case 22. As shown in FIG. 1 , the third protrusion 62 is basically provided between each of the plurality of battery cells 12 that make up the cell stack 10.

[0050] Like the second protrusions 52, the third protrusions 62 are provided to position each battery cell 12 in the stacking direction D1. Specifically, the third protrusions 62 are formed on the inner surface of the upper case 22. In the example of the upper case 22, the third protrusions 62 are formed on the inner surface 30a of the top wall 30 of the upper case 22. As shown in FIG. 1 , the third protrusions 62 protrude from the inner surface 30a so as to be located between adjacent battery cells 12 (gap g1). In other words, the third protrusions 62 overlap the battery cells 12 in the height direction D3 of the battery cells 12.

[0051] The third protrusions 62 are formed to extend along the width direction D2 of the battery cell 12. More specifically, in the example of the upper case 22, the third protrusions 62 extend along the width direction D2 so as to cover the entire inner surface 30a. As can be seen from FIG. 5 , the third protrusions 62 are continuous with the second protrusions 52 formed on the inner surfaces 32a and 34a of the pair of side walls 32 and 34, respectively. However, instead of this example, the third protrusions 62 may be provided only on a portion of the inner surface 30a in the width direction D2.

[0052] Additionally, similar to the second protrusion 52, a gap g2 (play) is provided between the third protrusion 62 and the battery cell 12 in the stacking direction D1. Therefore, the battery cell 12 is positioned by the third protrusion 62 while being allowed to move within the range of the gap g2. Note that a protrusion for positioning the battery cell 12, such as the protrusion 64 (see FIG. 1) provided at the end in the stacking direction D1, may be provided between the battery cell 12 and the case end wall (for example, each of the end walls 36 and 38).

[0053] FIG. 9 is a diagram illustrating an additional problem I2 according to the embodiment. FIG. 9 is a cross-sectional view taken at the same position as FIG. 1. When the third protrusion 62 is provided on the upper wall 30, a "waviness W2" may occur in the upper wall 30, as shown in FIG. 9. Specifically, similar to the above-described waviness W1 that may occur in the side wall 32 (and 34), the waviness W2 may occur when the third protrusion 62 receives a load from the surrounding battery cells 12 when a restraint load along the stacking direction D1 acts on the upper case 22. The waviness W2 occurs along the stacking direction D1, as shown in FIG. 9. Note that when the upper case 22 is made of resin, the waviness W2 may occur not only due to the above-described factors but also due to warping of the upper wall 30 that may occur during molding of the upper case 22.

[0054] FIG. 10 is a top view of the upper case 22 shown in FIG. 1 as viewed from the top wall 30 side. When the above-described swell W2 occurs, the mountability of the upper case 22 to the lower case 24 decreases. In consideration of this additional problem I2, in this embodiment, the upper case 22 includes a second rib 66. The second rib 66 is formed integrally with the upper case 22. As shown in FIG. 10, the second rib 66 is formed on the outer surface 30b of the top wall 30. For example, a plurality of second ribs 66 may be provided.

[0055] Each of the second ribs 66 is formed to extend parallel to the stacking direction D1. Alternatively, each of the second ribs 66 may be formed to extend obliquely with respect to the stacking direction D1. That is, each of the second ribs 66 does not necessarily extend in a direction parallel to the stacking direction D1, but may extend in a direction inclined with respect to the stacking direction D1.

[0056] In addition, as described above, each of the second ribs 66 is formed to extend parallel or diagonally to the stacking direction D1, so that when the upper wall 30 is viewed from a direction perpendicular to the upper wall 30 (i.e., in Figure 10), each of the second ribs 66 extends so as to intersect with the third protrusion 62.

[0057] 10 , the upper wall 30 has a plurality of through holes 68 formed along the stacking direction D1 in the center of the battery cells 12 in the width direction D2. The plurality of through holes 68 are formed at positions corresponding to safety valves provided on the top surfaces 12a of the individual battery cells 12. The above-mentioned second ribs 66 are formed on both sides of the plurality of through holes 68 in the width direction D2. The upper wall 30 also has a plurality of through holes 69 formed to expose the electrode terminals of each battery cell 12 to the outside of the upper case 22.

[0058] (effect) According to this embodiment, the provision of the second rib 66 can increase the rigidity of the upper wall 30 against the swell W2, thereby effectively suppressing the swell W2 that occurs in the upper wall 30 due to the presence of the third protrusion 62 described above.

[0059] (Variation) 11 is a bottom view of a lower case 70 according to a modified embodiment, viewed from the side of the bottom wall 72. The battery pack according to this modified embodiment includes a cell stack 10 and a battery case. The battery case is formed in a substantially rectangular parallelepiped shape and houses the cell stack 10. The battery case includes the lower case 70 and an upper case (or upper cover) (not shown).

[0060] The lower case 70 includes a bottom wall 72 and four side walls. The bottom wall 72 faces the bottom surfaces 12f of each of the battery cells 12 that make up the cell stack 10. Although not shown here, the four side walls are configured in the same manner as the four side walls 32 to 38 described above. The bottom wall 72 and the four side walls are integrally formed. The upper case includes an upper wall that faces the top surfaces 12a of each of the battery cells 12 that make up the cell stack 10.

[0061] In the example shown in Fig. 10 described above, the third protrusion 62 and the second rib 66 are formed integrally with the top wall 30. In contrast, in the modified example shown in Fig. 11, the third protrusion 74 and the second rib 76 are formed integrally with the bottom wall 72. Specifically, the third protrusion 74 protrudes from the inner surface of the bottom wall 72 so as to be interposed between adjacent battery cells 12. The third protrusion 74 is basically provided between each of the multiple battery cells 12 that make up the cell stack 10. The second rib 76 is formed on the outer surface 72b of the bottom wall 72. For example, multiple second ribs 76 may be provided.

[0062] Each of the second ribs 76 is formed to extend parallel to the stacking direction D1. Alternatively, each of the second ribs 76 may be formed to extend obliquely with respect to the stacking direction D1. That is, each of the second ribs 76 does not necessarily have to extend parallel to the stacking direction D1, but may instead extend in a direction inclined with respect to the stacking direction D1. By forming each of the second ribs 76 to extend parallel or obliquely with respect to the stacking direction D1 in this way, when the bottom wall 72 is viewed from a direction perpendicular to the bottom wall 72 (i.e., in FIG. 11 ), each of the second ribs 76 extends so as to intersect with the third protrusion 74.

[0063] Even in the above-described modified example, by providing the second rib 76, it is possible to increase the rigidity of the bottom wall 72 against swells that may occur in the bottom wall 72, similar to the above-described swell W2. This makes it possible to effectively suppress swells that occur in the bottom wall 72 due to the presence of the above-described third convex portion 74.

[0064] 5. Other configurations and effects of the battery case 5-1. Busbar module mounting hooks A bus bar module 80 is mounted on the top wall 30 of the upper case 22. More specifically, two bus bar modules 80 are mounted. Each bus bar module 80 includes a plurality of bus bars that are connected by welding or the like to the electrode terminals of the plurality of battery cells 12 that make up the cell stack 10, and a resin bus bar case that supports the plurality of bus bars.

[0065] The upper wall 30 is provided with a plurality of claws 82 for attaching each bus bar module 80 to the upper wall 30. The plurality of claws 82 are formed integrally with the upper wall 30. Each battery cell 12 is positioned relative to the upper case 22 by the second protrusions 52 and the third protrusions 62 described above. Therefore, by attaching the bus bar module 80 to the upper wall 30 of the upper case 22 using the plurality of claws 82 described above, the plurality of bus bars in the bus bar module 80 are naturally placed in locations where they can be attached to the electrode terminals of the corresponding battery cells 12 (for example, locations where they can be welded).

[0066] As described above, the upper case 22 of this embodiment has the function of protecting the battery cells 12 by the first protrusions 50, the function of positioning the battery cells 12 by the second protrusions 52 and the third protrusions 62, and also the function of assisting in the attachment of the bus bars.

[0067] 5-2. Protecting battery cells using restraint members Fig. 12 is a diagram for explaining the structure of the restraining members 26 and 28 shown in Fig. 1. Here, the restraining member 26 will be used as an example for explanation, but the other restraining member 28 is also configured in the same way.

[0068] 12 shows an intruding object 100 approaching the battery pack 1 from above. The intruding object 100 is, for example, a structural member (e.g., a floor panel) of the electric vehicle that mounts the battery pack 1. When a collision load is input to the electric vehicle, the intruding object 100 may approach the battery pack 1 from above, as shown in FIG.

[0069] In order to protect the battery cells 12 against the above-described intrusion 100, the restraining member 26 is formed and arranged so that its upper surface 26a is higher than at least the battery cells 12. More specifically, in the example shown in Fig. 12, the upper surface 26a of the restraining member 26 is formed and arranged so that it is higher than the top wall 30 of the upper case 22. In addition, the upper surface 26a may be formed and arranged so that it is higher than mounted components of the upper case 22, such as the bus bar module 80 (see Fig. 3) mounted on the top wall 30.

[0070] With the restraining member 26 formed and arranged as described above, when an intruding object 100 approaches the battery pack 1, the restraining member 26 will be the first to come into contact with the intruding object 100. Then, as shown in FIG. 12 , the load input from the intruding object 100 to the restraining member 26 is diverted by the lower case 24, not the battery cells 12. In other words, it is possible to prevent the load from the intruding object 100 from being directly input to the battery cells 12. This makes it possible to protect the battery cells 12 from the intruding object 100.

[0071] 5-3.Case lifting claws Fig. 13 is a diagram for explaining an additional problem I3 according to the embodiment. Fig. 13 is a cross-sectional view taken at the same position as Fig. 1. The upper case 22 is mounted on the lower case 24 while a restraining load is applied to the upper case 22, which houses the cell stack 10, by a pair of jigs 102 along the stacking direction D1. The pair of jigs 102 and the restraining members 26 and 28 are formed so as to be able to hook onto each other.

[0072] When the upper case 22 is lifted while applying a restraining load using the pair of jigs 102, the upper case 22 is deformed by the weight of the cell stack 10. As a result, the cell stack 10 is "deflected," as indicated by the dashed line in Fig. 13. This leads to a decrease in workability during the manufacture of the battery pack 1 (additional problem I3).

[0073] In consideration of the above-mentioned additional problem I3, the top wall 30 of the upper case 22 is provided with a pair of claws (case lifting claws) 84 for lifting the upper case 22. The pair of claws 84 are formed integrally with the top wall 30 so as to hook onto a pair of auxiliary jigs 104 (see FIG. 3) for preventing the above-mentioned "warping." More specifically, with respect to the width direction D2 of the battery cell 12, as shown in FIG. 3, the pair of claws 84 are provided at each end of the top wall 30 in the width direction D2. Furthermore, although not shown, with respect to the stacking direction D1, the pair of claws 84 are provided in the center of the top wall 30 in the stacking direction D1 (in other words, the center of the cell stack 10).

[0074] By providing the above-mentioned pair of claws 84 integrally with the upper case 22, deformation of the upper case 22 when lifting the upper case 22 and the resulting "deflection" of the cell stack 10 can be suppressed without increasing the number of parts.

[0075] 5-4. Positioning of restraining members 1 and 3, the end wall 36 of the upper case 22 is provided with pins 90 for positioning the restraining member 26. As an example, the pins 90 are provided in two locations. Similarly, the other end wall 38 is also provided with pins 90 for positioning the restraining member 28. These pins 90 are formed integrally with the upper case 22. In addition, the restraining members 26 and 28 are formed with recesses 26b and 28b, respectively, that engage with the pins 90.

[0076] Before lifting the upper case 22 using the pair of jigs 102, the upper case 22 and the restraining members 26 and 28 are stacked together as shown in Fig. 1. By providing the positioning pins 90, the restraining members 26 and 28 can be positioned relative to the upper case 22 during stacking without increasing the number of parts. Note that, in order to position the restraining members 26 and 28, pins may be provided on the sides of the restraining members 26 and 28, and recesses that engage with the pins may be provided on the sides of the end walls 36 and 38, as opposed to the above configuration example.

[0077] 6. Other examples of battery case configurations In the example of the battery case 20 described above, the first protrusions 50 are formed on the pair of side walls 32 and 34 of the upper case 22. Alternatively, the "first protrusions" may be formed on at least one of the top wall and bottom wall of the battery case.

[0078] In the example of the battery case 20, the second protrusion 52 is formed on the pair of side walls 32 and 34, and the third protrusion 62 is formed on the top wall 30. Alternatively, the battery case may include only one of the "second protrusion" and the "third protrusion."

[0079] In addition, in the example of the battery case 20, the first protrusion 50 and the second protrusion 52 are provided as a pair. Alternatively, the "first protrusion" may be provided singly. [Explanation of symbols]

[0080] 1 battery pack 10 Cell stack 12 battery cells 14 Elastic Body 20 Battery case 22 Upper Case 24, 70 lower case 26, 28 Restraining member 30 Upper Wall 32, 34 side wall 36, 38 End walls 40, 72 bottom wall 50 First convex part 52 Second convex part 60 First Rib 62, 74 Third convex part 66, 76 Second Rib 80 Busbar Module 82 Busbar module mounting hooks 84 Case lifting claws 90 pins 100 Intrusion 102, 104 Jig

Claims

1. a cell stack formed by stacking a plurality of battery cells each having a substantially rectangular parallelepiped shape; a battery case formed in a substantially rectangular parallelepiped shape and accommodating the cell stack; Equipped with The battery case includes a first protrusion that protrudes from an outer surface of the battery case to the outside of the battery case at a position corresponding to a gap between adjacent battery cells in the stacking direction of the cell stack. Battery pack.

2. the battery case includes a pair of side walls extending along the stacking direction and facing side surfaces of the cell stack, The first protrusion is formed on at least one of the pair of side walls. The battery pack according to claim 1 .

3. The battery case includes a second protrusion that protrudes from an inner surface of the battery case inside the first protrusion so as to be interposed between the adjacent battery cells. The battery pack according to claim 1 .

4. the battery case includes a pair of side walls extending along the stacking direction and facing side surfaces of the cell stack, the first protrusion and the second protrusion are formed on at least one of the pair of side walls, the battery case includes a first rib formed on an outer surface of at least one of the pair of side walls on which the first protrusion and the second protrusion are formed, The first rib is formed to extend parallel or obliquely with respect to the stacking direction. The battery pack according to claim 3 .

5. the first protrusions formed on at least one of the pair of side walls are provided for each gap between adjacent battery cells in the cell stack, and are formed to extend along the gaps between the adjacent battery cells; The first rib is formed so as to bridge the gap between the adjacent first protrusions. The battery pack according to claim 4.

6. The battery case is an upper wall extending along the stacking direction and facing an upper surface of the cell stack; a third protrusion protruding from the inner surface of the upper wall so as to be interposed between the adjacent battery cells; a second rib formed on the outer surface of the upper wall; Including, The second rib is formed to extend parallel or obliquely with respect to the stacking direction. The battery pack according to claim 1 .

7. The battery case is a bottom wall extending along the stacking direction and facing a bottom surface of the cell stack; a third protrusion protruding from the inner surface of the bottom wall so as to be interposed between the adjacent battery cells; a second rib formed on the outer surface of the bottom wall; Including, The second rib is formed to extend parallel or obliquely with respect to the stacking direction. The battery pack according to claim 1 .

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