Battery case

Abstract

To improve a strength of joint between case bodies.SOLUTION: A battery case attached to a vehicle comprises a casting first case body 41 and a second case body 42 which are jointed each other. Uneven engaging parts 71 and 72 are provided at a joint part 44 between the first case body 41 and the second case body 42. The joint part 44 includes an overlapped fillet welding part. The first case body 41 and the second case body 42 have the same shape, and have vehicle attachment parts 13 and 14 to be attached to the vehicle directly or via another member. The vehicle attachment parts 13 and 14 are provided with the uneven engaging parts 71 and 72. Along a direction orthogonal to an uneven direction of the uneven engaging parts 71 and 72, the first case body 41 and the second case body 42 are fastened with volts in the uneven engaging parts 71 and 72.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a battery case that is attached to a vehicle body. [Background technology]

[0002] The present applicant has already proposed a battery case such as that disclosed in Patent Document 1. In this battery case, a plurality of cast case bodies are joined together. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-191163 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to improve the bonding strength between case bodies. [Means for solving the problem]

[0005] The battery case of the present invention is a battery case that is attached to a vehicle body, and comprises a first case body and a second case body that are made of cast material and joined together, and a concave-convex engagement portion is provided at the joint between the first case body and the second case body.

[0006] With this configuration, the first and second case bodies are made by casting, making it easy to obtain a large battery case with great strength. Furthermore, the provision of concave-convex engaging portions at the joints improves joint strength.

[0007] In particular, it is preferable that the joint has a lap fillet weld, which can further improve the joint strength.

[0008] Preferably, the first case body and the second case body have the same shape, which allows the first case body and the second case body to be manufactured using a single mold.

[0009] Furthermore, it is preferable that the battery case has a vehicle body mounting portion for mounting to the vehicle body directly or via another member, and that the vehicle body mounting portion is provided with a concave-convex engaging portion. With this configuration, the battery case can be firmly mounted to the vehicle body.

[0010] It is also preferable that the first case body and the second case body are fastened together at the concave-convex engaging portions with bolts along a direction perpendicular to the concave-convex direction of the concave-convex engaging portions. With this configuration, the first case body and the second case body are fastened together at the concave-convex engaging portions with bolts along a direction perpendicular to the concave-convex direction of the concave-convex engaging portions, thereby further increasing the joining strength. [Effects of the Invention]

[0011] As described above, since the concave-convex engaging portion is provided at the joint portion, the joint strength between the case bodies can be improved. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a perspective view of a battery case according to an embodiment of the present invention, as viewed from the top side. [Figure 2] FIG. 4 is a perspective view of the battery case as viewed from the bottom side. [Figure 3] FIG. [Figure 4] Cross section AA of Figure 1. [Figure 5] Enlarged view of part C in Figure 4. [Figure 6] Cross section B-B of Figure 1. [Figure 7] FIG. 4 is a perspective view showing a first frame member used in the battery case. [Figure 8] FIG. 4 is a perspective view showing a second frame member used in the battery case. [Figure 9]FIG. 4 is a cross-sectional view of a joint portion of the battery case. [Figure 10] 10 is a cross-sectional view corresponding to FIG. 9, showing the battery case in a state before joining. DETAILED DESCRIPTION OF THE INVENTION

[0013] A battery case according to one embodiment of the present invention will be described below with reference to Figs. 1 to 10. Figs. 1 to 6 show the battery case according to this embodiment. The battery case is an in-vehicle battery case that is attached to a vehicle body (not shown). The battery case may be attached to the vehicle body in any manner, but as an example, in Fig. 1, the front-rear direction of the vehicle body (vehicle body front-rear direction) is indicated by arrow X, and the width direction of the vehicle body (vehicle body width direction) is indicated by arrow Y.

[0014] <Overall structure> The battery case is tray-shaped with an open top and a bottom, and includes a bottom portion 1 shown by a two-dot chain line in Fig. 2, a peripheral wall portion 2 rising upward from the periphery of the bottom portion 1, and partition portions that divide the storage space of the battery case into multiple sections. The shape of the battery case in a plan view is arbitrary, but in this embodiment it is rectangular in plan view, more specifically, a rectangular shape that is long in the fore-and-aft direction of the vehicle body. The four corners are chamfered.

[0015] The peripheral wall portion 2 has a front wall portion 3, a rear wall portion 4, a left wall portion 5, and a right wall portion 6. The front wall portion 3 and the rear wall portion 4 extend along the width direction of the vehicle body and face each other in the front-to-rear direction of the vehicle body. The left wall portion 5 and the right wall portion 6 extend along the front-to-rear direction of the vehicle body and face each other in the width direction of the vehicle body. The front wall portion 3 and the rear wall portion 4 have the same shape, and the left wall portion 5 and the right wall portion 6 have the same shape.

[0016] Reinforcing walls 7 are provided on the peripheral wall portion 2 so as to protrude laterally. The reinforcing walls 7 are preferably provided around the entire periphery. The reinforcing walls 7 are thin plates, and the thickness direction of the reinforcing walls 7 is the vertical direction. The reinforcing walls 7 extend horizontally over most of the entire periphery of the peripheral wall portion 2. The number of reinforcing walls 7 is arbitrary, but in this embodiment, a total of five reinforcing walls 7 are provided at regular intervals above and below.

[0017] Of the five reinforcing walls 7, the uppermost and lowermost reinforcing walls 7 extend like flanges from the upper and lower ends of the peripheral wall 2 toward the outside of the case without any steps. The upper surface of the uppermost reinforcing wall 7 forms a continuous upper surface of the case around the entire periphery. The lower surface of the lowest reinforcing wall 7 forms a continuous lower surface of the case around the entire periphery.

[0018] In addition, connecting walls 8 that connect the reinforcing walls 7 together vertically are provided at multiple locations spaced apart in the horizontal direction. It is preferable that the connecting walls 8 connect five reinforcing walls 7 in a vertical line. Two adjacent reinforcing walls 7 vertically and two adjacent connecting walls 8 horizontally form a number of chambers that open to the sides on the outer surface of the peripheral wall portion 2. In other words, a reinforcing portion having a number of chambers that open to the outside of the case is provided on the outer surface of the peripheral wall portion 2.

[0019] A wiring insertion hole 9 is provided in the center of each of the front wall portion 3 and the rear wall portion 4, penetrating in the longitudinal direction of the vehicle body. A cord (not shown) is inserted through the wiring insertion hole 9. The cord electrically connects a battery (not shown) and an external device (not shown). The wiring insertion hole 9 is preferably provided in the upper half region (upper portion) of the front wall portion 3 and the rear wall portion 4. A cylindrical wall 10 protrudes outward from the edge of the wiring insertion hole 9. The cylindrical wall 10 is connected to the reinforcing wall 7 and the connecting wall 8, and together with the reinforcing wall 7 and the connecting wall 8, the cylindrical wall 10 also forms a reinforcing portion that reinforces the peripheral wall portion 2.

[0020] <Vehicle body mounting part> The battery case has a vehicle body mounting portion for mounting the battery case to the vehicle body directly or via another member. The battery case is mounted to the vehicle body at the peripheral wall portion 2. That is, the vehicle body mounting portion is provided on the peripheral wall portion 2, and more specifically, on the reinforcing portion. The vehicle body mounting portion is provided on the left wall portion 5 and the right wall portion 6. The vehicle body mounting portion is provided at multiple locations spaced apart in the fore-and-aft direction of the vehicle body. The vehicle body mounting portion may have a variety of structures, but in this embodiment, it has a fastening structure that is fastened with bolts 100 (see Figure 9). The fastening direction is the vertical direction.

[0021] Six vehicle body mounting portions are arranged symmetrically on each of the left and right walls 5 and 6. The six vehicle body mounting portions on each of the left and right walls 5 and 6 are referred to as first to sixth vehicle body mounting portions 11, 12, 13, 14, 15, and 16, in order from the front wall 3 to the rear wall 4. The first to third vehicle body mounting portions 11, 12, and 13 are arranged symmetrically in the front-to-rear direction with the fourth to sixth vehicle body mounting portions 14, 15, and 16. The first to third vehicle body mounting portions 11, 12, and 13 are arranged at regular intervals. The fourth to sixth vehicle body mounting portions 14, 15, and 16 are also arranged at regular intervals. The third vehicle body mounting portion 13 and the fourth vehicle body mounting portion 14 are arranged adjacent to each other with no gap between them. The third vehicle body mounting portion 13 and the fourth vehicle body mounting portion 14 are located in the center of the vehicle in the fore-and-aft direction.

[0022] The first to sixth vehicle body mounting portions 11, 12, 13, 14, 15, and 16 each have a fastening through-hole 20. The fastening through-hole 20 passes vertically through the five reinforcing walls 7. A bolt 100 is inserted vertically into the fastening through-hole 20 as shown by the two-dot chain line in FIG. 9. For example, the bolt 100 is inserted from above, and a nut 101 is screwed onto the lower end of the bolt 100.

[0023] The first to sixth vehicle body mounting portions 11, 12, 13, 14, 15, and 16 each have a support surface 21 on the upper surface of the uppermost reinforcing wall 7 and on the lower surface of the lowermost reinforcing wall 7. The support surface 21 protrudes upward and downward from the upper surface of the uppermost reinforcing wall 7 and the lower surface of the lowermost reinforcing wall 7. The support surface 21 is island-shaped and may have any shape, such as a circle, but is rectangular in this embodiment.

[0024] Connecting walls 8 are provided on both sides of the fastening insertion hole 20 in the vehicle front-rear direction. Four fastening reinforcement box portions 22 lined up vertically are formed in each of the first to sixth vehicle body mounting portions 11, 12, 13, 14, 15, and 16 by the five reinforcing walls 7 and the connecting walls 8 on both sides of the fastening insertion hole 20, and the bolt 100 passes through the four box portions 22 vertically.

[0025] <Divider> The shape and arrangement of the partitions are arbitrary and may be provided in various ways depending on the number and arrangement of the batteries to be accommodated, but in this embodiment, vertical partitions 30 extending in the fore-and-aft direction of the vehicle body and horizontal partitions extending in the width direction of the vehicle body are provided. The vertical partitions 30 are provided in the center in the width direction of the vehicle body. The horizontal partitions are arranged at equal intervals in the fore-and-aft direction of the vehicle body.

[0026] A main horizontal partition 31 that connects the left wall 5 and the right wall 6 is provided in the center of the vehicle in the longitudinal direction. The main horizontal partition 31 divides the battery case into two sections. Vertical partitions 30 are provided between the front wall 3 and the main horizontal partition 31, and between the main horizontal partition 31 and the rear wall 4. The vertical partitions 30 connect the front wall 3 and the rear wall 4 to the main horizontal partition 31. Sub-horizontal partitions 32 are provided between the vertical partition 30 and the left wall 5, and between the vertical partition 30 and the right wall 6. The sub-horizontal partitions 32 connect the left wall 5 and the right wall 6 to the vertical partition 30. The sub-horizontal partitions 32 are arranged at equal intervals between the front wall 3 and the main horizontal partition 31, two on each side, for a total of four, and are also arranged at equal intervals between the rear wall 4 and the main horizontal partition 31, two on each side, for a total of four.

[0027] Vertical divider 30 is located below wiring insertion hole 9. The interior of vertical divider 30 is hollow as shown in FIG. 6. Clamp holes 33 for fixing cords are formed in the upper surface of vertical divider 30. Cords are inserted inside through wiring insertion hole 9 and wired along the upper surface of vertical divider 30. Clamps (not shown) are attached to the cord at intervals, and the cord can be fixed to the upper surface of vertical divider 30 by inserting the locking portions of the clamps into clamp holes 33. If there are multiple cords, they are bound together with clamps.

[0028] As shown in FIG. 4, the sub-horizontal partition 32 is formed in a Z-shape in cross section. A band-shaped lower flange 34 projects from the lower end of the sub-horizontal partition 32 in the fore-and-aft direction of the vehicle body. A band-shaped upper flange 35 projects from the upper end of the sub-horizontal partition 32 in the fore-and-aft direction of the vehicle body and in the opposite direction from the lower flange 34. The upper flange 35 has a smaller projection (width) than the lower flange 34. A lid support 36 projects upward from the upper end of the sub-horizontal partition 32, i.e., the upper flange 35. An optional top cover, described below, can be attached to this lid support 36. Furthermore, as shown in FIG. 2, a number of X-shaped ribs 37 are provided on the underside of the sub-horizontal partition 32.

[0029] The first and second vehicle body mounting portions 11, 12 and the fifth and sixth vehicle body mounting portions 15, 16 are located on the outside of the case corresponding to the sub-horizontal partition portion 32. The third and fourth vehicle body mounting portions 13, 14 are located on the outside of the case corresponding to the main horizontal partition portion 31.

[0030] <Battery storage section 38> The battery case is for housing multiple batteries. Batteries are inserted into the battery case through an opening on the top surface of the battery case. Any number of batteries can be housed, but in this embodiment, a total of 12 batteries are housed. The batteries are arranged flatly, without being stacked one on top of the other.

[0031] The battery case includes a plurality of battery storage sections 38 for individually storing a plurality of batteries. The plurality of battery storage sections 38 are separated by partitions. In this embodiment, a total of 12 battery storage sections 38 are provided by the vertical partitions 30, the main horizontal partitions 31, and the sub horizontal partitions 32. The battery storage sections 38 are arranged in two directions, the longitudinal direction of the vehicle body and the width direction of the vehicle body. However, for example, the battery storage sections 38 may be arranged in a straight line only in the longitudinal direction of the vehicle body, or in a straight line in the width direction of the vehicle body.

[0032] In this embodiment, the battery storage sections 38 are arranged in six rows (six batteries) in the longitudinal direction of the vehicle body and in two rows (two batteries) in the width direction of the vehicle body, for a total of 6 x 2 = 12 batteries. The batteries have a rectangular parallelepiped shape that is long in a predetermined direction, and are stored in the battery storage sections 38 with their longitudinal direction aligned with the width direction of the vehicle body. However, the orientation of the batteries can be changed as desired.

[0033] Each battery receptacle 38 is provided with a battery attachment section 39 for attaching a battery. The battery attachment sections 39 are arranged at the four corners of the battery receptacle 38.

[0034] <Battery case component configuration> The battery case includes a frame 40 with openings at the top and bottom, and a flat undercover 43 attached to the bottom of the frame 40. The undercover 43 is indicated by a two-dot chain line in FIG. 2 . The undercover 43 forms the bottom portion 1 of the battery case. The undercover 43 closes the bottom opening of the frame 40. The undercover 43 is preferably a metal plate. The undercover 43 is welded to the frame 40, for example, but may also be attached by screws or other methods. The undercover 43 may be one piece or multiple pieces, for example, two pieces. The frame 40 forms the peripheral wall portion 2 and the partition portion of the battery case. The frame 40 is made by casting, specifically die-casting. The battery case may include a top cover (not shown) that closes the top opening of the battery case. The top cover is preferably plate-shaped. The top cover may be one piece or multiple pieces.

[0035] <Frame 40> The frame 40 is composed of a plurality of frame members joined together. In this embodiment, the frame 40 includes a first frame member 41 as a first case body and a second frame member 42 as a second case body. The first frame member 41 and the second frame member 42 are joined together to form an integrated unit. The battery case may include other frame members in addition to the first frame member 41 and the second frame member 42, and the number of frame members is arbitrary. The above-mentioned under cover 43 may be attached to each of the first frame member 41 and the second frame member 42. Similarly, a top cover may be provided for each frame member.

[0036] The battery case can be attached to the vehicle body so that the first frame member 41 is located at the front of the vehicle body, and the second frame member 42 is located at the front of the vehicle body, and can be attached to the vehicle body regardless of the front-rear direction. Specifically, the first frame member 41 and the second frame member 42 are arranged side by side in the fore-and-aft direction of the vehicle body. A joint 44 where the first frame member 41 and the second frame member 42 are joined to each other extends along the width direction of the vehicle body. The joint 44 is located in the center of the battery case in the fore-and-aft direction of the vehicle body. The joint 44 is provided in the center of the main horizontal partition 31 and the left wall 5 and right wall 6 in the fore-and-aft direction of the vehicle body.

[0037] <First frame member 41 and second frame member 42> The first frame member 41 and the second frame member 42 are both made by casting, specifically die-casting. Figures 7 and 8 show the first frame member 41 and the second frame member 42, respectively, before joining. In this embodiment, the first frame member 41 and the second frame member 42 have the same shape. Therefore, the first frame member 41 and the second frame member 42 can be cast using a single mold. The second frame member 42 is obtained by flipping the first frame member 41 in the front-to-rear direction of the vehicle body. Therefore, the first frame member 41 and the second frame member 42 are half the size of the battery case. However, the first frame member 41 and the second frame member 42 may have different shapes, or may have symmetrical shapes in opposing directions, for example.

[0038] The thickness of the first frame member 41 and the second frame member 42 is substantially constant over most of their length and has a basic thickness. The first frame member 41 and the second frame member 42 are rectangular in plan view and have a frame shape that is open at the top and bottom. The first frame member 41 has a front wall 3, a first left wall 50 and a first right wall 51 that form one half of the left wall 5 and the right wall 6 in the longitudinal direction of the vehicle body, a first joint wall 52 that forms one half of the main horizontal partition 31 in the longitudinal direction of the vehicle body, one vertical partition 30, and four sub horizontal partitions 32. The second frame member 42 has a rear wall portion 4, a second left wall portion 60 and a second right wall portion 61 which form one half of the left wall portion 5 and the right wall portion 6 in the fore-and-aft direction of the vehicle body, a second joining wall portion 62 which forms one half of the main horizontal partition portion 31 in the fore-and-aft direction of the vehicle body, one vertical partition portion 30, and four sub horizontal partition portions 32.

[0039] The first frame member 41 and the second frame member 42 are joined so that the first joint wall portion 52 and the second joint wall portion 62 face each other in the fore-and-aft direction of the vehicle body. Joint portions 44 between the first frame member 41 and the second frame member 42 are formed between the first joint wall portion 52 and the second joint wall portion 62, as well as between an end portion of the first left wall portion 50 and an end portion of the second left wall portion 60, and between an end portion of the first right wall portion 51 and an end portion of the second right wall portion 61.

[0040] The first and second joint walls 52 and 62 are joined together to form the main horizontal partition 31. The outer surfaces of the first and second joint walls 52 and 62 are vertical and in surface contact with each other. A first joint piece 53 is provided on the upper surface of the first joint wall 52 in the shape of a flange, protruding away from the front wall 3, i.e., toward the second frame member 42. The first joint piece 53 is provided on either the left or right half of the overall length of the first joint wall 52 in the vehicle width direction. In this embodiment, the first joint piece 53 is provided on the left half, i.e., on the first left wall 50 side. Similarly, a second joint piece 63 is provided on the upper surface of the second joint wall 62 in the right half. The second joint piece 63 protrudes toward the first frame member 41.

[0041] When the first frame member 41 and the second frame member 42 are joined together, the first joint piece 53 overlaps the upper surface of the second joint wall portion 62, and the second joint piece 63 overlaps the upper surface of the first joint wall portion 52. The first joint wall portion 52 and the second joint wall portion 62 are welded on their upper and lower surfaces over their entire lengths in the vehicle width direction. On the upper surfaces of the first joint wall portion 52 and the second joint wall portion 62, lap fillet welding is performed at the protruding ends of the first joint piece 53 and the second joint piece 63, forming a lap fillet weld 45 along the protruding ends. In other words, the protruding end of the first joint piece 53 and the upper surface of the second joint wall portion 62 are lap fillet welded, and the protruding end of the second joint piece 63 and the upper surface of the first joint wall portion 52 are lap fillet welded. The first and second joining pieces 53 and 63 may be provided on the lower surfaces of the first and second joining wall portions 52 and 62, or on both the upper and lower surfaces. The first and second joining pieces 53 and 63 may be continuous with the support surface 21, or the upper surfaces of the first and second joining pieces 53 and 63 may be flush with the support surface 21.

[0042] <Concave / convex engaging part> A first concave-convex engaging portion 71 and a second concave-convex engaging portion 72 are provided at both ends of the first joining wall portion 52 and the second joining wall portion 62 in the vehicle width direction, respectively. As shown in FIGS. 7 and 10 , the end of the first left wall portion 50 is provided with a first concave engaging portion 80 recessed in the vehicle front-rear direction and a first convex engaging portion 81 protruding in the vehicle front-rear direction, i.e., protruding toward the second frame member 42. The first concave engaging portion 80 corresponds to one box portion 22 and has a structure in which one of the four box portions 22 arranged vertically is missing, i.e., a missing box portion. In this embodiment, the first concave engaging portion 80 is provided at the position of the second box portion 22 from the top. The first convex engaging portion 81 is located immediately below the first concave engaging portion 80 and adjacent to the third box portion 22 from the top in the vehicle front-rear direction. The first convex engagement portion 81 has a structure in which one box portion 22 is added to the second frame member 42 side, i.e., it is an added box portion. In this way, the first concave engagement portion 80 and the first convex engagement portion 81 are arranged one above the other. The first concave engagement portion 80 and the first convex engagement portion 81 form the first concave-convex engagement portion 71.

[0043] On the other hand, as shown in FIGS. 8 and 10 , a second concave-convex engaging portion 72 is provided at the end of the second left wall portion 60. The second convex engaging portion 72 has an inverse configuration to the first concave-convex engaging portion 71 and engages with the first concave-convex engaging portion 71 in the vehicle longitudinal direction. The end of the second left wall portion 60 is provided with a second convex engaging portion 90 that protrudes toward the first frame member 41 in the vehicle longitudinal direction, and a second concave engaging portion 91 that is recessed in the vehicle longitudinal direction. The second convex engaging portion 90 is an added box portion, and the second concave engaging portion 91 is a missing box portion. In this embodiment, the second convex engaging portion 90 is provided adjacent to the second box portion 22 from the top, and the second concave engaging portion 91 is located immediately below the second convex engaging portion 90, at the position of the third box portion 22 from the top. In this manner, the second convex engaging portion 90 and the second concave engaging portion 91 are arranged vertically side by side. The second convex engaging portion 90 and the second concave engaging portion 91 constitute the second concave-convex engaging portion 72 .

[0044] 9, 10 and 3, the second convex engagement portion 90 engages with the first concave engagement portion 80, and the first convex engagement portion 81 engages with the second concave engagement portion 91. The first convex engagement portion 81 becomes the third box portion 22 from the top on the fourth vehicle body mounting portion 14, and the second convex engagement portion 90 becomes the second box portion 22 from the top on the third vehicle body mounting portion 13.

[0045] Similarly, a second concave-convex engaging portion 72 is provided at an end of the first right wall portion 51, and a first concave-convex engaging portion 71 is provided at an end of the second right wall portion 61.

[0046] As shown in FIG. 9 , the bolt 100 is inserted into the fastening insertion hole 20 and the nut 101 is screwed in, thereby firmly fastening the first concave-convex engaging portion 71 and the second concave-convex engaging portion 72 in the vertical direction. The bolt 100 is inserted through the first concave-convex engaging portion 71 and the second concave-convex engaging portion 72 in the vertical direction, which is perpendicular to the concave-convex direction. Note that FIG. 9 shows an example of a mounting structure to a vehicle body or other member. A first mounting plate portion 102 and a second mounting plate portion 103 are disposed above and below the battery case. The battery case is mounted to the vehicle body so that it is sandwiched between the first mounting plate portion 102 and the second mounting plate portion 103. The first mounting plate portion 102 and the second mounting plate portion 103 abut against the support surface 21 of the battery case. The battery case is fastened to the first mounting plate portion 102 and the second mounting plate portion 103 by the bolt 100 and the nut 101. By attaching the battery case to the vehicle body in this manner, the first concave-convex engaging portion 71 and the second concave-convex engaging portion 72 are fastened together vertically.

[0047] As described above, the first concave-convex engaging portion 71 and the second concave-convex engaging portion 72 are provided at the joint 44 between the first frame member 41 and the second frame member 42, thereby improving the joint strength of the joint 44. In particular, the concave-convex engaging portion is formed on a box section 22-by-box section basis, thereby suppressing uneven thickness and achieving high joint strength. Furthermore, the bolt 100 is inserted vertically through the first concave-convex engaging portion 71 and the second concave-convex engaging portion 72, ensuring high joint strength.

[0048] In particular, the battery case can be firmly attached to the vehicle body because the third vehicle body mounting portion 13 and the fourth vehicle body mounting portion 14 are provided with the first concave-convex engaging portion 71 and the second concave-convex engaging portion 72. The third vehicle body mounting portion 13 and the fourth vehicle body mounting portion 14 are adjacent to each other at the joint 44, so that portion can be particularly firmly attached to the vehicle body.

[0049] Furthermore, high weld strength is achieved by providing lap fillet welds 45 at joints 44 on the top surface of main horizontal partition 31. In particular, because first joint piece 53 and second joint piece 63 protrude toward second frame member 42 and first frame member 41, respectively, lap fillet welding can be easily performed on the top surface of main horizontal partition 31, easily ensuring high joint strength.

[0050] In this embodiment, the first frame member 41 and the second frame member 42 are fastened together by bolts 100 for mounting to the vehicle body, but the first frame member 41 and the second frame member 42 may also be fastened together by bolts other than the bolts 100 for mounting to the vehicle body.

[0051] Furthermore, although the first frame member 41, the second frame member 42, and the undercover 43 are separate members in the above embodiment, the first frame member 41, the second frame member 42, and the undercover 43 may be integrally formed by casting. That is, at least one of the first case body and the second case body may have a bottom. [Explanation of symbols]

[0052] 1 Bottom part 2 Surrounding wall part 3 Front wall 4 Rear wall 5 Left wall 6 Right wall 7 Reinforced Wall 8 Connecting wall 9 Wiring insertion hole 10 Cylindrical wall 11 First body mounting part 12 Second body mounting part 13 Third body mounting part 14 Fourth body mounting part 15 5th body mounting part 16 6th body mounting part 20 Fastening hole 21 Support surface 22 Box section 30 Vertical partition 31 Main horizontal partition 32 Sub-horizontal partition 33 Clamp hole 34 Lower Tsuba 35 Upper tsuba 36 Lid support part 37 X-shaped rib 38 Battery compartment 39 Battery mounting part 40 frames 41 First frame member (first case body) 42 Second frame member (second case body) 43 Undercover 44 Joint 45 Lap fillet weld 50 First left wall 51 1st right wall section 52 1st joint wall part 53 1st joint piece 60 Second left wall 61 2nd right wall section 62 Second joint wall section 63 Second joint piece 71 First uneven engagement part 72 Second uneven engagement part 80 First concave engagement part 81 First convex engagement part 90 Second convex engagement part 91 Second concave engagement part 100 volts 101 Nut 102 First mounting plate portion 103 Second mounting plate part

Claims

1. A battery case having a bottom surface, a peripheral wall portion rising upward from the peripheral edge of the bottom surface, and a partition portion dividing the storage space into multiple sections, the battery case being attached to a vehicle body, The apparatus includes a first case body and a second case body that are joined together by casting, the first case body and the second case body are arranged side by side in a first vehicle body direction, which is one of the vehicle body longitudinal direction and the vehicle body width direction, and a joint between the first case body and the second case body is along a second vehicle body direction, which is the other of the vehicle body longitudinal direction and the vehicle body width direction; the first case body has a first joint wall portion, and the second case body has a second joint wall portion, the first joint wall portion and the second joint wall portion being joined to face each other in a first direction of the vehicle body to form a partition portion; a first concave-convex engaging portion is provided at each of both end portions of the first joining wall portion in the vehicle body second direction, and a second concave-convex engaging portion that concave-convexly engages with the first concave-convex engaging portion in the vehicle body first direction is provided at each of both end portions of the second joining wall portion in the vehicle body second direction, The first concave-convex engaging portion and the second concave-convex engaging portion constitute a part of the peripheral wall portion of the battery case.

2. The first concave-convex engaging portion has a first concave engaging portion recessed in a first direction of the vehicle body and a first convex engaging portion protruding in the first direction of the vehicle body, the first concave engaging portion and the first convex engaging portion being arranged side by side one above the other, the second concave-convex engagement portion has a second concave engagement portion recessed in the first vehicle body direction and a first convex engagement portion protruding in the first vehicle body direction, the second concave engagement portion and the second convex engagement portion being arranged side by side in the vertical direction; 2. A battery case as described in claim 1, wherein the first concave engaging portion of the first joining wall portion and the second convex engaging portion of the second joining wall portion are engaged in a concave-convex manner in the first direction of the vehicle body, and the first convex engaging portion of the first joining wall portion and the second concave engaging portion of the second joining wall portion are engaged in a concave-convex manner in the first direction of the vehicle body.

3. 3. A battery case as described in claim 1 or 2, wherein the first case body and the second case body have the same shape, and when the first case body is inverted in the first direction of the vehicle body in a plan view and turned in the opposite direction, it becomes the second case body.

4. A vehicle body mounting portion for mounting to a vehicle body is provided on the peripheral wall portion, 4. The battery case according to claim 1, wherein the first concave-convex engaging portion and the second concave-convex engaging portion are provided on the vehicle body mounting portion.

5. A battery case as described in any one of claims 1 to 4, wherein the first case body and the second case body are fastened together by the bolts at the first and second concave-convex engaging portions by inserting bolts in the vertical direction into the first and second concave-convex engaging portions.

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