Battery unit

Abstract

To inhibit a liquid from entering a battery unit from the outside.SOLUTION: A battery unit includes: a battery pack; a lower case which is open to the upper side, houses the battery pack, and has a first bottom wall covering the battery pack at the lower side of the battery pack and a first side wall covering the battery pack at the lateral side of the battery pack; a waterproof tray which is open to the upper side, houses the lower case, and has a second bottom wall covering the lower case at the lower side of the lower case and a second side wall extending from the second bottom wall to an area above the battery pack and covering the lower case at the lateral side of the lower case; a raising bracket fastened to the first side wall and extending upward from the first side wall; and a protection cover which is fastened to the raising bracket, covers the battery pack at the upper side of the battery pack, and extends to the outer side of the second side wall relative to the waterproof tray.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a battery unit for a vehicle. [Background technology]

[0002] Vehicles such as hybrid vehicles (HVs) and electric vehicles (EVs) are equipped with a battery unit that supplies electricity to the vehicle. The battery unit has a battery pack. Known vehicles of this type have a battery unit installed below the front seats inside the vehicle (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-280036 [Patent Document 2] International Publication No. 2017 / 110138 Summary of the Invention [Problem to be solved by the invention]

[0004] When a battery unit is mounted below the front seat, there is a possibility that water that has entered the vehicle interior or has spilled inside the vehicle interior may splash onto the battery pack. In other words, there is a risk of the battery pack becoming wet. To prevent this, a waterproof tray that opens upward and houses the battery unit may be set to the height of the predicted flood level. However, even with this configuration, because the waterproof tray opens upward, water falling from above the battery unit may enter the battery unit through the gap between the battery pack and the cover.

[0005] The present invention has been made in view of the above, and one of its objects is to prevent liquid from entering the battery unit from the outside. [Means for solving the problem]

[0006] The battery unit of the present invention is a battery unit mounted on a vehicle and includes: a battery pack that supplies electricity to the vehicle; a lower case that has: a first bottom wall that opens upward to accommodate the battery pack and covers the battery pack on a lower side of the battery pack; and a first side wall that covers the battery pack on a lateral side of the battery pack; a waterproof tray that has: a second bottom wall that opens upward to accommodate the lower case and covers the lower case on a lower side of the lower case; and a second side wall that extends from the second bottom wall to a position above the battery pack and covers the lower case on a lateral side of the lower case; a height-raising bracket that is fastened to the first side wall and extends upward from the first side wall; and a protective cover that is fastened to the height-raising bracket, covers the battery pack on an upper side of the battery pack, and extends outside the second side wall relative to the waterproof tray.

[0007] With this configuration, the protective cover that covers the battery pack above the battery pack is fastened to the elevation bracket and extends outside the second side wall relative to the waterproof tray, so that liquid that falls from above the battery pack flows over the protective cover and falls outside the waterproof tray, thereby preventing liquids such as water from entering the battery unit from the outside.

[0008] The battery unit includes, for example, a damper that is fastened to the elevation bracket and presses the battery pack downward.

[0009] This configuration can prevent the battery pack from moving within the battery unit. [Effects of the Invention]

[0010] The battery unit according to the present invention has an effect of suppressing the intrusion of liquid from the outside into the battery unit. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing the general shape of a vehicle equipped with a battery unit according to an embodiment. [Figure 2] FIG. 2 is a plan view showing a floor and a battery unit of a vehicle according to the embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a plan view showing the battery unit according to the embodiment, with a protective cover partially removed. [Figure 5] FIG. 5 is a perspective view showing a portion including a height-raising bracket in the battery unit according to the embodiment. [Figure 6] FIG. 6 is a perspective view showing a portion including a height-raising bracket in the battery unit according to the embodiment. [Figure 7] FIG. 7 is a cross-sectional view showing a fixing structure between the height-raising bracket and the frame according to the embodiment. [Figure 8] FIG. 8 is a perspective view showing a height-raising bracket according to the embodiment. [Figure 9] FIG. 9 is a plan view showing the height-raising bracket according to the embodiment. [Figure 10] FIG. 10 is a side view showing the height-raising bracket according to the embodiment. [Figure 11] FIG. 11 is a cross-sectional view showing a part of the damper according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] One embodiment will be described below. Note that the drawings are schematic, and the dimensional relationships and ratios of elements may differ from reality. Furthermore, the drawings may include portions with different dimensional relationships and ratios. Furthermore, in this specification, ordinal numbers are used only to distinguish between parts, members, portions, positions, directions, etc., and do not indicate order or priority.

[0013] FIG. 1 is a diagram showing the general shape of a vehicle 100 equipped with a battery unit 1 according to an embodiment. The vehicle is an electric vehicle such as a hybrid vehicle or an electric vehicle. The vehicle 100 has a front seat 103, a rear seat 104, and a battery unit 1 on a floor 102 of an interior 101. The battery unit 1 is installed under the front seat 103. The battery unit 1 is also referred to as a power supply unit.

[0014] Each drawing shows a three-dimensional coordinate system. In the three-dimensional coordinate system, the fore-and-aft direction of the vehicle 100 and the battery unit 1 is the X-axis direction, the width direction (left-right direction) is the Y-axis direction, and the up-and-down direction (height direction) is the Z-axis direction. The positive direction of the X-axis is the rear in the fore-and-aft direction, and the negative direction of the X-axis is the front in the fore-and-aft direction. The positive direction of the Y-axis is the right, and the negative direction of the Y-axis is the left. The positive direction of the axis is upward, and the negative direction of the Z-axis is downward. Furthermore, hereinafter, unless otherwise specified, the fore-and-aft direction is the fore-and-aft direction of the vehicle 100 and the battery unit 1, the width direction is the width direction of the vehicle 100 and the battery unit 1, and the up-and-down direction is the up-and-down direction of the vehicle 100 and the battery unit 1.

[0015] Fig. 2 is a plan view showing the floor 102 and battery unit 1 of the vehicle 100 according to the embodiment. As shown in Fig. 2, the floor 102 is part of the vehicle body and includes at least a left side member 5L, a right side member 5R, a front cross member 6F, and a rear cross member 6R. The floor 102 is also referred to as a floor panel.

[0016] The left side member 5L and the right side member 5R each extend in the front-to-rear direction and are arranged at a distance from each other in the width direction. The front cross member 6F and the rear cross member 6R each extend in the width direction and are arranged at a distance from each other in the front-to-rear direction. The front cross member 6F and the rear cross member 6R are provided across the left side member 5L and the right side member 5R, respectively. A plate-shaped panel portion is provided in the area of ​​the floor 102 surrounded by the left side member 5L, right side member 5R, front cross member 6F, and rear cross member 6R, and the battery unit 1 is disposed above this panel portion.

[0017] 3 is a cross-sectional view taken along line III-III in FIG. 2. As shown in FIGS. 2 and 3, the battery unit 1 includes a case 11, a battery pack 12, a blower 13, a control device 14, a waterproof tray 15, and height-raising brackets 51A and 51B. Hereinafter, the height-raising bracket 51 will be used as a general term for the height-raising brackets 51A and 51B. The case 11 houses the battery pack 12, the blower 13, and the control device 14. The battery pack 12, the blower 13, and the control device 14 are aligned in the width direction. The blower 13 is disposed on one side (for example, the right side) of the battery pack 12, and the control device 14 is disposed on the other side (for example, the left side) of the battery pack 12. The waterproof tray 15 houses the case 11, the battery pack 12, the blower 13, the control device 14, and the height-raising bracket 51.

[0018] The battery pack 12 is a secondary battery (battery) that supplies electricity to the motor of the vehicle 100, and is, for example, a lithium-ion battery. The battery pack 12 is charged by regenerative power or power from a charger. The blower 3 blows air onto the battery pack 12 inside the protective cover 2 to cool the battery pack 12. The control device 14 controls the battery pack 12 and the blower 13. The control device 14 is, for example, a battery management system, and has multiple electronic components. The multiple electronic components include high-voltage components to which a high voltage is applied.

[0019] Each part will be explained in detail below.

[0020] As shown in Fig. 3, the waterproof tray 15 is open upward and accommodates the lower case 21 of the case 11. The waterproof tray 15 is fixed to the floor 102 via an intervening member 81. The waterproof tray 15 has a second bottom wall 15a and a second side wall 15b. The second bottom wall 15a covers the lower case 21 on the lower side of the lower case 21. The second side wall 15b extends from the second bottom wall 15a above the battery pack 12 and covers the lower case 21 on the lateral side of the lower case 21.

[0021] As shown in FIGS. 2 and 3, the case 11 has a lower case 21 (FIG. 3) and a protective cover 22.

[0022] The lower case 21 is open upward and accommodates the battery pack 12, the blower 13, and the control device 14. The lower case 21 is fixed to the floor 102.

[0023] The lower case 21 has a first bottom wall 21a and a first side wall 21b. The first bottom wall 21a covers the battery pack 12 from below the battery pack 12. The first side wall 21b covers the battery pack 12 from the side of the battery pack 12. The first side wall 21b has a fixing portion 21c at its upper end. A female screw 7c is provided in the fixing portion 21c. A height-raising bracket 51 is fixed to the fixing portion 21c. Specifically, the height-raising bracket 51 is fastened to the fixing portion 21c by a bolt 71 coupled with the female screw 7c. The lower case 21 is made of, for example, a metal material. Note that the material of the lower case 21 is not limited to the above.

[0024] The raising bracket 51 is fastened to the first side wall 21b and extends upward from the first side wall 21b. The raising bracket 51 is made of, for example, a synthetic resin material. Note that the material of the raising bracket 51 is not limited to the above. Details of the raising bracket 51 will be described later.

[0025] 3, the protective cover 22 is provided above the lower case 21 and covers the opening of the lower case 21. The protective cover 22 is fastened to the first side wall 21b of the lower case 21 via a height-raising bracket 51. The protective cover 22 is provided above the battery pack 12, the blower 13, and the control device 14 and covers the battery pack 12, the blower 13, and the control device 14. The protective cover 22 also extends outside the second side wall 15b relative to the waterproof tray 15.

[0026] The protective cover 22 has a base wall 22a and a side wall 22b. The base wall 22a is provided above the battery pack 12, blower 13, and control device 14, and covers the battery pack 12, blower 13, and control device 14. The side wall 22b extends downward from the outer edge of the base wall 22a. The side wall 22b is located outside the upper end 15ba of the second side wall 15b with a gap relative to the waterproof tray 15.

[0027] The side wall 22b of the protective cover 22 and the upper end 15ba of the second side wall 15b of the waterproof tray 15 are overlapped in a direction perpendicular to the up-down direction. As an example, the side wall 22b of the protective cover 22 and the upper end 15ba of the second side wall 15b of the waterproof tray 15 are overlapped with a gap therebetween in a direction perpendicular to the up-down direction. Note that the side wall 22b of the protective cover 22 and the upper end 15ba of the second side wall 15b of the waterproof tray 15 may be in contact with each other.

[0028] The side wall 22b of the protective cover 22 and the upper end 15ba of the second side wall 15b of the waterproof tray 15 form a labyrinth structure 90. The labyrinth structure 90 prevents liquids such as water from entering the inside of the case 11 from between the side wall 22b of the protective cover 22 and the upper end 15ba of the second side wall 15b of the waterproof tray 15. The gap between the side wall 22b of the protective cover 22 and the upper end 15ba of the second side wall 15b of the waterproof tray 15 may be sealed with a sealing member.

[0029] The protective cover 22 is made up of a combination of multiple members. For example, as shown in Fig. 2, the protective cover 22 has a first cover member 23, a second cover member 24, a third cover member 25, and a frame 62 (Fig. 4). The protective cover 22 is fixed to the front cross member 6F and the rear cross member 6R by bolts 27-29, etc.

[0030] The first cover member 23 is positioned at least above the battery pack 12 and covers the battery pack 12. The second cover member 24 is positioned at least above the control device 14 and covers the control device 14. The third cover member 25 is positioned at least above the blower 13 and covers the blower 13. A frame 62 (FIG. 4) is fixed to the underside of the first cover member 23.

[0031] 2, a plurality of (for example, two) skeletal frames 26A, 26B are fixed to the protective cover 22. The skeletal frame 26A is fixed to the first cover member 23, and the skeletal frame 26B is fixed to the second cover member 24. Hereinafter, the skeletal frame 26 will be used as a general term for the plurality of skeletal frames 26A, 26B. Although the following describes an example in which one skeletal frame 26 is provided for each of the first cover member 23 and the second cover member 24, the number of skeletal frames 26 is not limited to this. For example, a plurality of skeletal frames 26 may be provided for each of the first cover member 23 and the second cover member 24.

[0032] Fig. 4 is a plan view showing the battery unit 1 according to the embodiment, with a portion of the protective cover 22 removed. Specifically, Fig. 4 shows the state in which the first cover member 23 and the second cover member 24 of the protective cover 22 are removed.

[0033] As shown in Fig. 4, the multiple skeletal frames 26 each extend in the front-to-rear direction and are arranged at intervals in the width direction. Each skeletal frame 26 is provided across the front cross member 6F and the rear cross member 6R and is fixed to the front cross member 6F and the rear cross member 6R. In other words, each skeletal frame 26 bridges the front cross member 6F and the rear cross member 6R.

[0034] The skeleton frame 26 is a plate member whose longitudinal direction is the front-to-rear direction. The skeleton frame 26 is made, for example, by processing a hat-shaped member, and at least a portion of the cross section has a hat-shaped cross section. The skeleton frame 26 is made, for example, from a metal material.

[0035] The skeletal frame 26 has a front end 26a, a rear end 26b opposite the front end 26a, a left end 26c, and a right end 26d opposite the left end 26c.

[0036] 2, the front end 26a and rear end 26b of the skeletal frame 26 are fastened to the front cross member 6F and the rear cross member 6R by bolts 27. The bolts 27 are coupled with nuts (not shown) to secure the skeletal frame 26 to the front cross member 6F and the rear cross member 6R.

[0037] As shown in FIG. 4 , the left end 26c and the right end 26d of the skeletal frame 26 have concave-convex portions 26e. The concave-convex portions 26e have a plurality of convex portions 26ea arranged at intervals in the front-rear direction. Each convex portion 26ea is fixed to the protective cover 22. Specifically, each convex portion 26ea is welded to the protective cover 22. More specifically, the convex portion 26ea of ​​the skeletal frame 26A is welded to the first cover member 23, and the convex portion 26ea of ​​the skeletal frame 26B is welded to the second cover member 24. The welding between the skeletal frame 26 and the protective cover 22 is, for example, spot welding, but is not limited to this. In FIG. 4 , welded points 26g on the skeletal frame 26 are indicated by black circles. Note that the welded points 26g between the skeletal frame 26 and the protective cover 22 are not limited to the above.

[0038] 4, the skeletal frame 26A is provided with a protrusion 26i. If the battery pack 12 moves upward toward the skeletal frame 26A for some reason, the protrusion 26i comes into contact with the upper part of the battery pack 12. In this state, the protrusion 26i restricts the upward movement of the battery pack 12.

[0039] As shown in FIG. 4, the skeletal frame 26A is provided with a fixing portion 26h. The blower 13 is fixed to the fixing portion 26h. In other words, the blower 13 is attached to the fixing portion 26h. The fixing portion 26h is also referred to as a blower attachment portion. A plurality of fixing portions 26h (for example, two) are provided at the right end portion 26d of the skeletal frame 26A. The fixing portions 26h are provided at intervals in the front-rear direction. The fixing portions 26h protrude rightward from the left end portion 26c, i.e., toward the opposite side from the battery pack 12. The fixing portions 26h are integrally formed with the skeletal frame 26A. Note that the fixing portions 26h may be provided as separate members from the skeletal frame 26A and fixed to the skeletal frame 26A by fastening or the like.

[0040] Next, the height-raising bracket 51 will be described in detail with reference to Figs. 3 to 10. Fig. 5 is a perspective view showing a portion including the height-raising bracket 51 in the battery unit 1 according to the embodiment. Fig. 6 is a perspective view showing a portion including the height-raising bracket 51 in the battery unit 1 according to the embodiment. Fig. 7 is a cross-sectional view showing the fixing structure between the height-raising bracket 51 and the frame 62 according to the embodiment. Fig. 8 is a perspective view showing the height-raising bracket 51 according to the embodiment. Fig. 9 is a plan view showing the height-raising bracket 51 according to the embodiment. Fig. 10 is a side view showing the height-raising bracket 51 according to the embodiment.

[0041] As shown in Fig. 4, two height-raising brackets 51 are provided spaced apart in the front-to-rear direction. As shown in Figs. 3 to 6, the lower end of each height-raising bracket 51 is fastened to the first side wall 21b of the lower case 21 by a bolt 71 and a female screw 7c. Also, as shown in Figs. 3 to 7, the upper end of each height-raising bracket 51 is fastened to the frame 62 of the protective cover 22 by a bolt 73 and a nut 74. As shown in Fig. 3, the vertical position of the upper end of each height-raising bracket 51 is substantially the same as the vertical position of the upper end of the waterproof tray 15.

[0042] 8 to 10, the height-raising bracket 51 has two lower fixing portions 51a, two inclined portions 51b, one upper fixing portion 51c, and overlapping portions 51e and 51d. The height-raising bracket 51 is formed as a whole in a concave shape that opens downward. The fixing portion 51c is an example of an upper fixing portion, and the fixing portion 51a is an example of a lower fixing portion.

[0043] The two fixing portions 51a are spaced apart in the width direction. The two fixing portions 51a are fastened to fixing portions 51c on the first side wall 21b of the lower case 21. The two inclined portions 51b extend upward from the two fixing portions 51c. The two inclined portions 51b are inclined relative to the up-down direction so as to approach each other as they extend upward. The fixing portion 51c is provided across the upper ends of the two inclined portions 51b. A bolt 73 is fixed to the fixing portion 51c, and the fixing portion 51c is fastened to the protective cover 22 by the bolt 73 and a nut 74. The overlapping portions 51d and 51e overlap in the front-rear direction and are joined to each other. The overlapping portion 51d extends from the fixing portion 51a, and the overlapping portion 51e extends from the inclined portion 51b. The overlapping portions 51d and 51e are provided between the fixing portion 51a and the inclined portion 51b. This reinforces the area between the fixed portion 51a and the inclined portion 51b.

[0044] FIG. 11 is a cross-sectional view showing a portion of a damper 61 according to an embodiment. As shown in FIGS. 4 and 11, the battery unit 1 further includes a damper 61. The damper 61 is fastened to the elevation bracket 51 and presses the battery pack 12 downward. Specifically, the damper 61 includes a frame 62 of the protective cover 22 and an elastic member 63. That is, the frame 62 is shared by the protective cover 22 and the damper 61. The elastic member 63 is fixed to the lower surface of the frame 62 and is in contact with the upper surfaces of the frame 62 and the battery pack 12. The elastic member 63 is interposed between the frame 62 and the battery pack 12 in a compressed state and presses the battery pack 12 downward by its elastic force (restoring force). The elastic member 63 is made of, for example, rubber or sponge. The frame 62 is also referred to as a cell damper frame.

[0045] The frame 62 is welded to the first cover member 23, for example. The welding between the frame 62 and the first cover member 23 is, for example, but not limited to, spot welding. In Fig. 4, welded points 62a on the frame 62 are indicated by black circles. Note that the welded points 62a between the frame 62 and the first cover member 23 are not limited to the above.

[0046] In a vehicle 100 equipped with the battery unit 1 configured as described above, if, for example, an occupant spills a liquid, such as a drink, inside the vehicle and the liquid falls from above the battery unit 1 onto the base wall 22a of the protective cover 22 of the battery unit 1, the liquid flows, for example, in the direction indicated by the bold arrow in FIG. 3 . That is, the liquid flows along the outer surface of the base wall 22a to the outer periphery of the base wall 22a and falls from the outer periphery of the base wall 22a. At this time, because the protective cover 22 covering the battery pack 12 above the battery pack 12 extends outside the second side wall 15b relative to the waterproof tray 15, the liquid falling from above the battery pack 12 flows over the protective cover 22 and falls to the outside of the waterproof tray 15. This prevents liquids, such as water, from entering the battery unit 1 from the outside. In addition, the side wall 22b of the protective cover 22 and the upper end 15ba of the second side wall 15b of the waterproof tray 15 form a labyrinth structure 90, which further prevents liquids such as water from entering the battery unit 1 from the outside.

[0047] As described above, the battery unit 1 of this embodiment is a battery unit 1 mounted on a vehicle 100. The battery unit 1 includes a battery pack 12, a lower case 21, a waterproof tray 15, a height-raising bracket 51, and a protective cover 22. The battery pack 12 supplies electricity to the vehicle 100. The lower case 21 is open upward and houses the battery pack 12. The lower case 21 has a first bottom wall 21a and a first side wall 21b. The first bottom wall 21a covers the battery pack 12 on its lower side. The first side wall 21b covers the battery pack 12 on its lateral side. The waterproof tray 15 is open upward and houses the lower case 21. The waterproof tray 15 has a second bottom wall 15a and a second side wall 15b. The second bottom wall 15a covers the lower case 21 on its lower side. The second side wall 15b extends from the second bottom wall 15a to above the battery pack 12 and covers the lower case 21 on the lateral side of the lower case 21. The height-raising bracket 51 is fastened to the first side wall 21b and extends upward from the first side wall 21b. The protective cover 22 is fastened to the height-raising bracket 51, covers the battery pack 12 above the battery pack 12, and extends outside the second side wall 15b relative to the waterproof tray 15.

[0048] With this configuration, the protective cover 22 that covers the battery pack 12 above the battery pack 12 is fastened to the elevation bracket 51 and extends outside the second side wall 15b relative to the waterproof tray 15, so that liquid that falls from above the battery pack 12 flows over the protective cover 22 and falls to the outside of the waterproof tray 15. This prevents liquids such as water from entering the battery unit 1 from the outside. In other words, the waterproofness of the battery unit 1 can be improved. This prevents liquids from splashing on the battery pack 12 and the control device 14. Furthermore, with the above configuration, the height of the lower case 21 does not need to be increased. This allows for a reduction in the weight and cost of the lower case 21.

[0049] The battery unit 1 also includes a damper 61. The damper 61 is fastened to the raising bracket 51 and presses the battery pack 12 downward.

[0050] This configuration can prevent the battery pack 12 from moving inside the battery unit 1. Furthermore, because the damper 61 is fastened to the elevation bracket 51, the damper 61 can be fixed to the elevation bracket 51 with a relatively small number of parts, thereby reducing costs.

[0051] Although the embodiments of the present invention have been described, the above embodiments are presented as examples and are not intended to limit the scope of the invention. The above embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention. The above embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions described in the claims and their equivalents. [Explanation of symbols]

[0052] 1... battery unit, 12... battery pack, 15... waterproof tray, 15a... second bottom wall, 15b... second side wall, 21... lower case, 21a... first bottom wall, 21b... first side wall, 22... protective cover, 51... height-raising bracket, 51a... Fixed part (lower fixed part), 51b... Inclined part, 51c... Fixed part (upper fixed part), 61...damper, 100...vehicle.

Claims

1. A battery unit mounted on a vehicle, a battery pack that supplies electricity to the vehicle; a lower case that is open upward and houses the battery pack, the lower case having a first bottom wall that covers the battery pack below the battery pack, and a first side wall that covers the battery pack on a lateral side of the battery pack; a waterproof tray having a second bottom wall that opens upward and accommodates the lower case and covers the lower case below the lower case, and a second side wall that extends from the second bottom wall to a position above the battery pack and covers the lower case on a lateral side of the lower case; a height-raising bracket fastened to the first side wall and extending upward from the first side wall; a protective cover fastened to the raising bracket, covering the battery pack from above, and extending outward from the second side wall relative to the waterproof tray; Equipped with The battery unit has an upper fixing portion, two lower fixing portions, and two inclined portions connecting the upper fixing portion and the two lower fixing portions, is formed in a concave shape that opens downward, and is fastened to the protective cover at the upper fixing portion and to the first side wall at the two lower fixing portions.

2. a damper fastened to the raising bracket and pressing the battery pack downward; The battery unit according to claim 1 .

3. The first side wall is formed lower than the upper end of the second side wall, The raising bracket is fastened to the first side wall and extends upward from an upper end of the second side wall. The battery unit according to claim 1 .

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