Battery pack

Abstract

To prevent air from leaking out from between an air-flow path provided in the bottom surface of a case and a cell stack.SOLUTION: A battery pack includes: a cell stack in which rectangular cells and resin frames that hold the cells are alternately stacked; a case that houses the cell stack and includes, in a bottom surface thereof, an air-flow path extending in a longitudinal direction of the cell stack; and a pair of seal members extending along both edges of the air-flow path on the bottom surface of the case, and sealing a gap between the air-flow path and the cell stack. The resin frame includes: a partition plate participating adjacent cells; and a rib dividing air introduced from the air-flow path. formed on a surface of the partition plate. Both ends of a bottom portion of the resin frame are provided with: a pair of first protrusions that protrudes downward so as to press the pair of seal members from above and engages with each other in the adjacent resin frames; and a pair of second protrusions that protrudes downward on an outer side of the pair of seal members and engages with each other in the adjacent resin frames.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a battery pack in which a cell stack, in which rectangular cells and resin frames that hold the cells are alternately stacked, is housed in a case. An air flow path extending in the longitudinal direction of the cell stack is provided on the bottom surface of the case. The resin frame has partition plates that separate adjacent cells, and ribs are formed on the surface of the partition plates that branch the air introduced from the air flow path. The cells are cooled by air flowing along the ribs formed on the resin frame. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-091665 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors have found the following problems in the development of a battery pack in which a cell stack, in which cells and resin frames are alternately stacked, is housed in a case having an air flow path on the bottom surface. In this battery pack, a pair of sealing members extend from both edges of the air flow path provided on the bottom surface of the case to seal between the air flow path and the cell stack. The resin frame presses the sealing members from above, and the lower part of the resin frame comes into contact with the sealing members, thereby sealing between the air flow path and the cell stack.

[0005] However, because a compressive force acts on the cell stack from both longitudinal ends toward the center, the cell stack may bend and bulge upward. In such cases, the resin frame at the longitudinal center of the cell stack may lift off the sealing member, causing air to leak between the air flow path and the cell stack.

[0006] The present disclosure has been made in consideration of the above circumstances, and provides a battery pack that can suppress air leakage between an air flow path provided on the bottom surface of the case and the cell stack. [Means for solving the problem]

[0007] A battery pack according to one embodiment of the present disclosure includes: a cell stack in which rectangular cells and resin frames for holding the cells are alternately stacked; a case that houses the cell stack and has an air flow path on its bottom surface that extends in the longitudinal direction of the cell stack; a pair of sealing members extending along both edges of the air flow path on the bottom surface of the case, sealing between the air flow path and the cell stack; the resin frame has a partition plate that separates the adjacent cells, and a rib that branches air introduced from the air flow path is formed on a surface of the partition plate, At both ends of the bottom of the resin frame, a pair of first protrusions that protrude downward so as to press the pair of seal members from above and that engage with each other on adjacent ones of the resin frames; A pair of second protrusions are provided which protrude downward outside the pair of seal members and engage with each other on adjacent resin frames.

[0008] In a battery pack according to one embodiment of the present disclosure, a pair of second protrusions are provided on both ends of the bottom of the resin frame, protruding downward outside the pair of sealing members and engaging with each other on adjacent resin frames. Therefore, at the portion where the first protrusion is lifted from the seal member, the seal member is pressed by the air and comes into contact with the second protrusion, thereby preventing air from leaking out from between the air flow path and the cell stack.

[0009] A pair of relief grooves may be formed on the bottom surface of the case at positions facing the pair of second protrusions. This configuration makes it possible to prevent contact between the bottom surface of the case and the second protrusions of the resin frame.

[0010] A pair of convex portions facing the pair of second protrusions may be formed on the case outside the pair of second protrusions. With this configuration, when the first protrusions of the resin frame rise up from the seal member and the seal member is pushed by air and deforms outward to abut against the second protrusions, the convex portions can push the second protrusions inward from the outside. This can further suppress air leakage from between the air flow path and the cell stack.

[0011] The pair of seal members may be made of foamed resin. With this configuration, when the first protrusion of the resin frame rises from the seal members, the seal members are easily pushed by air and deformed outward. [Effects of the Invention]

[0012] The present disclosure makes it possible to provide a battery pack that can prevent air from leaking between the cell stack and an air flow path provided on the bottom surface of the case. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing a battery pack according to a first embodiment. [Figure 2] FIG. 2 is a longitudinal sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is a side view showing the configuration of the cell stack CS. [Figure 4] 10 is a diagram showing the positional relationship between inner protrusion 24 and outer protrusion 25 provided on the negative x-axis side, as viewed from below. [Figure 5] FIG. 6 is a cross-sectional view showing a battery pack according to a second embodiment. [Figure 6] FIG. 10 is a cross-sectional view showing a battery pack according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, specific embodiments of the present disclosure will be described in detail with reference to the drawings. However, the present disclosure is not limited to the following embodiments. In addition, the following description and drawings have been simplified appropriately for clarity of explanation.

[0015] (First embodiment) <Battery pack configuration> First, a battery pack according to a first embodiment will be described with reference to FIGS. Fig. 1 is a cross-sectional view showing a battery pack according to a first embodiment, and Fig. 2 is a vertical cross-sectional view taken along line II-II in Fig. 1. Naturally, the right-handed xyz Cartesian coordinate system shown in Figures 1, 2, and other drawings is for the convenience of explaining the positional relationships of the components. In Figures 1, 2, etc., the positive direction of the z axis is normally vertically upward, and the xy plane is the horizontal plane, which is common among the drawings. In FIG. 2, the cell stack CS is shown in a simplified form.

[0016] As shown in FIGS. 1 and 2, the battery pack according to this embodiment includes a cell stack CS, a case 30, and a sealing member 40. The battery pack according to the present embodiment is, for example, an in-vehicle battery pack. The vehicle in which the battery pack according to the present embodiment is mounted is not particularly limited, but may be, for example, an electric vehicle, a hybrid vehicle, a fuel cell vehicle, or the like that can be driven by power supplied from the battery pack.

[0017] As shown in FIG. 1, the cell stack CS includes a cell 10 and a resin frame 20 that holds the cell 10. A cell 10 indicated by a two-dot chain line in FIG. 1 is a prismatic cell that is rectangular in the xz plane view, and is a secondary battery such as a lithium ion battery or a nickel-metal hydride battery. The resin frame 20 is a resin molded product that holds the cells 10, and is also called a spacer. As shown in FIG. 1, the resin frame 20 includes a partition plate 21, ribs 22, a frame portion 23, inner protrusions 24, and outer protrusions 25.

[0018] Here, Figure 3 is a side view showing the configuration of the cell stack CS. The left side of Figure 3 is an exploded view, and the right side is an assembled view. As shown in Figure 3, the cell stack CS is constructed by stacking cells 10 and resin frames 20 alternately in the y-axis direction. In other words, the cell stack CS is constructed by stacking cells 10 held in resin frames 20 in the y-axis direction. Adjacent resin frames 20 engage with and are connected to each other.

[0019] 1 is a plate-like member that separates adjacent cells 10. As shown in Fig. 1, a rib 22 that branches air introduced from an air flow path 31a provided in a bottom surface 31 of a case 30 is formed on the main surface of the partition plate 21 on the y-axis negative side.

[0020] That is, branch flow paths for branching air are formed by ribs 22 that protrude in the negative y-axis direction from the main surface on the negative y-axis side of partition plate 21. Here, cells 10 abut against ribs 22, and cells 10 are cooled by air flowing through the branch flow paths formed by ribs 22 (i.e., gaps between partition plate 21 and cells 10).

[0021] Here, we will explain the flow of air introduced from the bottom side of resin frame 20 shown in Fig. 1. Air introduced from the negative x-axis side of the widthwise (x-axis direction) center of partition plate 21 flows in the negative x-axis direction while branching by ribs 22 and is discharged from the negative x-axis side end of partition plate 21. On the other hand, air introduced from the positive x-axis side of the widthwise center of partition plate 21 flows in the positive x-axis direction while branching by ribs 22 and is discharged from the positive x-axis side end of partition plate 21. The ribs 22 may also be provided on the main surface of the partition plate 21 on the y-axis positive side.

[0022] 1, the frame portions 23 are formed on the periphery of the partition plate 21 to support the cells 10. In the example shown in Fig. 1, a pair of frame portions 23 having an L-shape in the xz plane are formed from both ends in the width direction (x-axis direction) of the partition plate 21 to the bottom. That is, the frame portions 23 support both end faces of the cells 10 in the width direction (x-axis direction) from both ends in the width direction of the partition plate 21, and also support the bottom surface of the cells 10 from the underside of the partition plate 21.

[0023] Here, frame portions 23 extend in the z-axis direction across the entire vertical direction at both widthwise ends of partition plate 21. On the other hand, at the bottom of partition plate 21, frame portions 23 are formed only at both widthwise ends in order to introduce air from below, and frame portion 23 is not formed in the widthwise center portion.

[0024] 3, the frame portions 23 extending in the vertical direction at both widthwise ends of the partition plate 21 include a main body portion 23a protruding from the partition plate 21 in the negative y-axis direction and an insertion portion 23b protruding in the positive y-axis direction. Here, the insertion portion 23b is inserted into the main body portion 23a of the frame portion 23 of the adjacent resin frame 20. Specifically, the insertion portion 23b shown in FIG. 3 is fitted into the gap between the cell 10 and the frame portion 23 (main body portion 23a) shown in FIG. 1, and supports the cell 10 together with the main body portion 23a of the frame portion 23 of the adjacent resin frame 20.

[0025] 1, inner protrusions (first protrusions) 24 are provided on both ends of the bottom of resin frame 20, and protrude downward so as to press seal member 40 from above. Specifically, inner protrusions 24 protrude downward from frame portion 23 provided on the bottom of partition plate 21.

[0026] Here, the sealing members 40 extend along both edges of the air flow path 31a provided on the bottom surface 31 of the case 30 to seal between the air flow path 31a and the cell stack CS. The inner protrusions 24 come into contact with the sealing members 40, thereby sealing between the air flow path 31a provided on the bottom surface 31 of the case 30 and the cell stack CS. As will be described in detail later, the inner protrusions 24 of adjacent resin frames 20 are engaged so as to come into contact with each other so that air does not leak out from gaps between the inner protrusions 24.

[0027] 1, the outer protrusions (second protrusions) 25 are provided on both ends of the bottom of the resin frame 20, and protrude downward outward from the sealing members 40 (i.e., the inner protrusions 24). In the example shown in FIG. 1, the outer protrusions 25 protrude downward continuously from the frame portions 23 provided on both ends of the partition plate 21 in the width direction.

[0028] 3, the outer protrusion 25 includes a main body portion 25a that protrudes downward from the main body portion 23a of the frame portion 23, and an insertion portion 25b that protrudes from the main body portion 25a in the positive y-axis direction. Here, the insertion portion 25b is inserted into the main body portion 25a of the outer protrusion 25 of the adjacent resin frame 20.

[0029] 4 is a diagram showing the positional relationship between the inner protrusion 24 and the outer protrusion 25 provided on the negative x-axis side, as viewed from below. Fig. 4 corresponds to Fig. 3, with the left side being an exploded view and the right side being an assembled view. As shown in Figure 4, like the outer protrusion 25, the inner protrusion 24 also has a main body portion 24a that protrudes downward from the frame portion 23, and an insertion portion 24b that protrudes from the main body portion 24a in the positive y-axis direction.

[0030] As shown in Fig. 4, the main body 24a of the inner protrusion 24 is a plate-like member that is L-shaped when viewed in the xy plane, and the insertion portion 24b of the inner protrusion 24 is a plate-like member that is trapezoidal when viewed in the xy plane. As shown on the right side of Fig. 4, the insertion portion 24b is inserted into the main body 24a of the inner protrusion 24 of the adjacent resin frame 20. In other words, the inner protrusions 24 of the adjacent resin frames 20 are engaged so as to come into contact with each other.

[0031] Similarly, as shown in Fig. 4, the main body 25a of the outer protrusion 25 is a plate-like member that is L-shaped when viewed in the xy plane, and the insertion portion 25b of the outer protrusion 25 is a plate-like member that is trapezoidal when viewed in the xy plane. As shown on the right side of Fig. 4, the insertion portion 25b is inserted into the main body 25a of the outer protrusion 25 of the adjacent resin frame 20. In other words, the outer protrusions 25 of the adjacent resin frames 20 are engaged so as to come into contact with each other.

[0032] 1 and 2, the case 30 is a box-shaped housing without a lid that houses the cell stack CS. The case 30 is made of, for example, a metal material, such as an aluminum alloy casting. As shown in FIGS. 1 and 2, the case 30 has a bottom surface 31, side surfaces 32, and end surfaces 33.

[0033] 1 and 2, a groove-shaped air flow path 31a extending over the entire longitudinal direction of the cell stack CS is formed in the bottom surface 31 of the case 30. The cell stack CS is placed on the bottom surface 31 of the case 30 so as to cover the entire air flow path 31a. Furthermore, as shown in Fig. 2, the end surfaces 33 of the case 30 press both ends of the cell stack CS in the longitudinal direction (y-axis direction) to hold the cell stack CS. End plates (not shown) are provided at both ends of the cell stack CS in the longitudinal direction.

[0034] 1 and 2, the sealing members 40 extend along the longitudinal direction of the cell stack CS at both edges in the width direction (x-axis direction) of the air flow path 31a provided on the bottom surface 31 of the case 30. The sealing members 40 are made of, for example, foamed resin. When the sealing members 40 are made of foamed resin, they are prone to deformation. As described above, the inner protrusions 24 of the resin frame 20 come into contact with the seal member 40, thereby sealing the gap between the air flow path 31a and the cell stack CS.

[0035] Here, as shown in Fig. 2, both longitudinal ends of the cell stack CS are pressed by the end faces 33 of the case 30. In other words, a compressive force acts on the cell stack CS from both longitudinal ends toward the center. Therefore, as shown by the two-dot chain line in Fig. 2, the cell stack CS may bend and protrude upward within the case 30. In this case, the inner protrusion 24 of the resin frame 20 rises from the seal member 40 at the longitudinal center of the cell stack CS, causing air to leak outward from the air flow path 31a.

[0036] In the battery pack according to this embodiment, outer protrusions 25 are provided on both ends of the bottom of the resin frame 20, protruding downward and further outward than the sealing member 40 (i.e., the inner protrusions 24). Therefore, when the inner protrusions 24 of the resin frame 20 rise above the sealing member 40 and air leaks from the air flow path 31a, the sealing member 40 is pushed by the air and deforms outward, coming into contact with the outer protrusions 25. For example, as shown by the dashed line in FIG. 1, when the sealing member 40, which has a rectangular xz cross section, is pushed by air from the inside, it deforms outward.

[0037] Thus, in the battery pack according to this embodiment, the sealing member 40 abuts against the outer protrusion 25 at the portion where the inner protrusion 24 of the resin frame 20 is raised above the sealing member 40. This mechanism makes it possible to prevent air from leaking between the air flow path 31a and the cell stack CS.

[0038] (Second embodiment) Next, a battery pack according to a second embodiment will be described with reference to Fig. 5. Fig. 5 is a cross-sectional view showing a battery pack according to the second embodiment. Fig. 5 corresponds to Fig. 1 of the first embodiment.

[0039] 5, in the battery pack according to this embodiment, a clearance groove 31b is formed in the bottom surface 31 of the case 30 at a position facing the outer protrusion 25 of the resin frame 20. Here, the clearance groove 31b is formed over the entire longitudinal direction of the cell stack CS.

[0040] As described above, in the battery pack according to this embodiment, the relief groove 31b is formed on the bottom surface 31 of the case 30 at a position facing the outer protrusion 25 of the resin frame 20. This makes it possible to prevent contact between the bottom surface 31 of the case 30 and the outer protrusion 25 of the resin frame 20. As a result, it is possible to prevent noise and damage to the outer protrusion 25 that may otherwise be caused by contact between the bottom surface 31 and the outer protrusion 25. Furthermore, because the height (length in the z-axis direction) of the outer protrusion 25 can be ensured, it is possible to further prevent air from leaking from between the air flow path 31a and the cell stack CS. The other configurations are the same as those in the first embodiment, and therefore the description will be omitted.

[0041] (Third embodiment) Next, a battery pack according to a third embodiment will be described with reference to Fig. 6. Fig. 6 is a cross-sectional view showing a battery pack according to the third embodiment. Fig. 6 corresponds to Fig. 1 of the first embodiment and Fig. 5 of the second embodiment.

[0042] 6, in the battery pack according to this embodiment, as compared to FIG. 5, a protrusion 31c that faces the outer protrusion 25 is formed on the case 30 outside the outer protrusion 25. Here, the protrusion 31c is formed over the entire longitudinal direction of the cell stack CS.

[0043] 6, the protrusion 31c is provided at a corner between the bottom surface 31 and the side surface 32 of the case 30. However, the protrusion 31c may be provided so as to be spaced apart from the side surface 32 and protrude upward from the bottom surface 31, as long as the protrusion 31c is disposed outward of the outer protrusion 25 and faces the outer protrusion 25. The protrusion 31c may also be provided so as to be spaced apart from the bottom surface 31 and protrude from the side surface 32 in the x-axis direction toward the outer protrusion 25.

[0044] As described above, in the battery pack according to this embodiment, the case 30 has a protrusion 31c formed outside the outer protrusion 25, facing the outer protrusion 25. Therefore, when the inner protrusion 24 of the resin frame 20 rises up from the seal member 40 and the seal member 40 is pushed by air and deforms outward, coming into contact with the outer protrusion 25, the protrusion 31c can push the outer protrusion 25 back inward from the outside. This further reduces air leakage between the air flow path 31a and the cell stack CS. The other configurations are the same as those of the second embodiment, and therefore the description will be omitted. Note that in Fig. 6, the relief groove 31b does not necessarily have to be formed.

[0045] The present disclosure is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the present disclosure. [Explanation of symbols]

[0046] 10 cells 20 Resin frame 21 Divider 22 Ribs 23 frame portion, 23a main body portion, 23b insertion portion 24 inner protrusion, 24a main body portion, 24b insertion portion 25 Outer protrusion, 25a Main body, 25b Insertion part 30 case, 31 bottom, 32 side, 33 end 31a Air flow path 31b Relief groove 31c Convex part 40 sealing material CS Cell Stack

Claims

1. a cell stack in which rectangular cells and resin frames for holding the cells are alternately stacked; a case that houses the cell stack and has an air flow path on its bottom surface that extends in the longitudinal direction of the cell stack; a pair of sealing members extending along both edges of the air flow path on the bottom surface of the case, sealing between the air flow path and the cell stack; the resin frame has a partition plate that separates the adjacent cells, and a rib that branches air introduced from the air flow path is formed on a surface of the partition plate, At both ends of the bottom of the resin frame, a pair of first protrusions that protrude downward so as to press the pair of seal members from above and that engage with each other on adjacent ones of the resin frames; a pair of second protrusions that protrude downward outside the pair of seal members and engage with each other on adjacent resin frames; Battery pack.

2. a pair of relief grooves are formed on the bottom surface of the case at positions facing the pair of second protrusions; The battery pack according to claim 1 .

3. a pair of protrusions facing the pair of second protrusions are formed on the case outside the pair of second protrusions; The battery pack according to claim 1 or 2.

4. The pair of sealing members are made of foamed resin. The battery pack according to claim 1 or 2.

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