Vehicle undercarriage

Abstract

The objective is to obtain a vehicle understructure that can maintain good battery performance in a structure equipped with a cross member extending in the vehicle width direction. [Solution] The vehicle understructure includes a battery case 12 located at the bottom of the vehicle and housing a battery BT, a cross member 20 located above the battery case 12 and extending in the vehicle width direction, a bracket 40 provided between the battery case 12 and the cross member 20 and comprising a joint 40A joined to the upper surface of the battery case 12 and a fastening portion 40B having an insertion hole 41A, and a fastener 44 inserted through the insertion hole 41A to fix the cross member 20 and the bracket 40, wherein the lower end of the fastener is located above the vehicle above the upper surface of the battery case facing the fastener.

Description

TECHNICAL FIELD

[0001] The present invention relates to a vehicle lower structure. BACKGROUND ART

[0002] Patent Document 1 discloses a vehicle lower structure provided with a battery frame that encloses a battery. Further, in the vehicle lower structure described in Patent Document 1, a cover plate that covers the battery from above is provided, and this cover plate constitutes the floor surface of the vehicle compartment. PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0003] PATENT DOCUMENT 1 Specification of Chinese Patent Application Publication No. 114940214 SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

[0004] By the way, a structure provided with a cross member extending in the vehicle width direction to transmit collision load at the time of a side collision is common, but in a structure where the cover plate of the battery case also serves as the floor panel as in the structure described in the above-mentioned Patent Document 1, the cross member is fixed to the cover plate. However, if a hole is drilled in the cover plate to directly fix the cross member to the cover plate, there is a possibility that the performance of the battery may be affected.

[0005] An object of the present invention is to obtain a vehicle lower structure that can favorably maintain battery performance in a structure provided with a cross member extending in the vehicle width direction. MEANS FOR SOLVING THE PROBLEM

[0006] The vehicle understructure of the first embodiment includes a battery case disposed at the bottom of the vehicle and housing a battery; a cross member disposed above the battery case and extending in the vehicle width direction; a bracket provided between the battery case and the cross member and comprising a joint portion joined to the upper surface of the battery case and a fastening portion having an insertion hole; and a fastener inserted through the insertion hole to fix the cross member and the battery case.

[0007] In the first embodiment of the vehicle understructure, a battery case containing the battery is positioned at the bottom of the vehicle. A cross member extending in the vehicle width direction is positioned above the battery case. This allows the collision load applied during a side collision of the vehicle (hereinafter referred to as "side collision") to be transmitted to the non-collision side by the cross member.

[0008] Furthermore, a bracket is provided between the battery case and the cross member. The bracket consists of a joint portion joined to the upper surface of the battery case and a fastening portion with an insertion hole formed therein. In this way, by providing a fastening portion on the bracket and attaching a fastener to this fastening portion and inserting it into the cross member, it is not necessary to directly fasten the battery case and the cross member with a fastener.

[0009] In the second embodiment of the vehicle understructure, the fastening portion protrudes upward from the joint portion of the vehicle, and a part of the fastener is positioned in the space between the fastening portion and the upper surface of the battery case.

[0010] In the vehicle understructure according to the second embodiment, by providing a part of the fastener in the space between the fastening portion and the upper surface of the battery case, it is possible to prevent the fastener from coming off the bracket and to maintain a good fastening state of the cross member.

[0011] In the third embodiment of the vehicle understructure, the cross member is formed in a closed cross-sectional shape, and a recess is formed in the lower wall portion of the cross member at a position corresponding to the fastening portion.

[0012] In the vehicle understructure of the third embodiment, a recess is formed in the cross member, and the fastening portion is inserted into the recess, so that the portion of the cross member other than the recess can be bonded to the bracket on a surface.

[0013] In the fourth embodiment, the vehicle understructure, in the first embodiment, has sides extending downward from both ends of the upper surface in the vehicle width direction, the bracket extends in the vehicle width direction, and the outer side of the bracket in the vehicle width direction is bent along the sides.

[0014] In the vehicle understructure of the fourth embodiment, since both ends of the bracket in the vehicle width direction are bent along the side of the battery case, the side of the battery case can be reinforced by the bracket. Note that "bent along the side" as used here is not limited to a configuration in which the side of the battery case and the bracket extend parallel to each other, but broadly includes a concept that includes configurations in which the bending angle is different from the angle between the top surface and the side of the battery case.

[0015] In the fifth embodiment, the vehicle understructure, in the fourth embodiment, comprises a flange extending outward from the side in the vehicle width direction from the battery case, and the bracket is joined to the flange.

[0016] In the vehicle understructure of the fifth embodiment, the bracket extends to the flange of the battery case, thus providing reinforcement from the side of the battery case to the flange.

[0017] In the sixth embodiment of the vehicle understructure, a gap is provided between the bracket and the side surface in the fifth embodiment.

[0018] In the vehicle lower structure according to the sixth aspect, the bracket is deformed by the collision load input at the time of a side collision, and the gap between the side surface of the battery case and the bracket is crushed, so that at least a part of the collision load can be absorbed.

[0019] In the vehicle lower structure according to the seventh aspect, in the first aspect, the upper surface of the battery case constitutes a vehicle compartment floor portion.

[0020] In the vehicle lower structure according to the seventh aspect, since the upper surface of the battery case constitutes the vehicle compartment floor portion, there is no need to separately provide a floor panel. As a result, the number of parts and the assembly man-hours can be reduced as compared with a structure provided with a floor panel.

[0021] In the vehicle lower structure according to the eighth aspect, in the second aspect, the fastening portion is configured to include a convex bead extending in the vehicle width direction.

[0022] In the vehicle lower structure according to the eighth aspect, the rigidity of the fastening portion is increased by the convex bead, and buckling of the bracket at the time of a side collision can be suppressed.

[0023] In the vehicle lower structure according to the ninth aspect, in the second aspect, the fastener includes a head portion and a shaft portion which is a bolt, the head portion is disposed in the space between the fastening portion and the upper surface of the battery case, and the shaft portion is inserted through the bracket and the cross member.

[0024] In the vehicle lower structure according to the ninth aspect, by disposing the head portion of the bolt in the space between the fastening portion and the upper surface of the battery case, the bolt can be prevented from coming off. Further, since the shaft portion of the bolt is inserted through the bracket and the cross member, the bracket and the cross member can be held between the head portion of the bolt and the nut, and the bracket and the cross member can be firmly fixed.

[0025] A vehicle lower structure according to a tenth aspect is the vehicle lower structure according to the fourth aspect, comprising a pair of left and right battery side frames provided on both sides of the battery case in the vehicle width direction and extending in the vehicle front-rear direction along the side faces, wherein the cross member is installed spanning between the pair of left and right battery side frames.

[0026] In the vehicle lower structure according to the tenth aspect, since the cross member is installed spanning between the battery side frames, a side collision load is transmitted via the cross member to the battery side frame on the side opposite to the collision, so that the battery can be favorably protected.

[0027] A vehicle lower structure according to an eleventh aspect is the vehicle lower structure according to the tenth aspect, wherein the cross member is configured to allow a vehicle seat to be mounted thereon, and is configured to be detachable from the battery side frames.

[0028] In the vehicle lower structure according to the eleventh aspect, since the cross member is detachable from the battery side frames, the vehicle seat can be removed from the vehicle simply by detaching the cross member from the battery side frames.

[0029] A vehicle lower structure according to a twelfth aspect is the vehicle lower structure according to the first aspect, wherein a plurality of the brackets are arranged at intervals in the vehicle front-rear direction.

[0030] In the vehicle lower structure according to the twelfth aspect, a plurality of cross members can be attached to the battery case by the plurality of brackets.

[0031] A vehicle lower structure according to a thirteenth aspect is the vehicle lower structure according to the second aspect, wherein a vibration-proof member is disposed in the space between the fastening portion and the upper surface of the battery case.

[0032] In the vehicle lower structure according to the thirteenth aspect, by disposing the vibration-proof member in the space between the fastening portion and the upper surface of the battery case, it is possible to suppress vibrations from the vehicle seat from being input to the battery. Effects of the Invention

[0033] As described above, the vehicle understructure according to the present invention allows for good battery performance in a structure equipped with a cross member extending in the vehicle width direction. [Brief explanation of the drawing]

[0034] [Figure 1] This is an exploded perspective view showing the vehicle understructure according to the embodiment. [Figure 2] This is an enlarged cross-sectional view showing the state after cutting along line 2-2 in Figure 1. [Figure 3] This is an enlarged cross-sectional view showing the state after cutting along line 3-3 in Figure 1. [Figure 4] This is a plan view showing the main parts of the vehicle understructure according to the embodiment, and is a diagram showing the state before the cross member is attached. [Figure 5] This is an enlarged cross-sectional view corresponding to Figure 4, showing the vehicle understructure according to the first modified example. [Figure 6] This is an enlarged cross-sectional view corresponding to Figure 3, showing the vehicle understructure according to the second modified example. [Figure 7] This is an enlarged cross-sectional view corresponding to Figure 3, showing the vehicle understructure according to the third modified example. [Figure 8] This is an enlarged cross-sectional view corresponding to Figure 2, showing the vehicle understructure according to the fourth modified example. [Modes for carrying out the invention]

[0035] The vehicle understructure according to this embodiment will be described with reference to the drawings.

[0036] Figure 1 is a perspective view showing a part of the understructure of a vehicle according to an embodiment. Arrows FR, UP, RH, and LH in the figure indicate the front, top, right, and left directions of the vehicle, respectively. In the following description, unless otherwise specified, the directions front, back, up, and left refer to the front-rear, up-down, and left-right directions of the vehicle, respectively.

[0037] As shown in Figure 1, the vehicle understructure of this embodiment comprises a battery frame 10 and a battery case 12. The battery case 12 is located at the bottom of the vehicle to which the vehicle understructure is applied. Figure 2 is an enlarged cross-sectional view showing the state when cut along line 2-2 in Figure 1. As shown in Figure 2, a battery BT is housed inside the battery case 12. The battery BT may be formed in a roughly box shape by housing multiple cells, such as a battery module, or it may be a long rectangular blade battery.

[0038] The battery case 12 comprises an upper case 14 and a lower case 16, and has a top surface 12A, a bottom surface 12B, and side surfaces 12C. The upper case 14 is formed in a roughly hat-shaped cross-section with the lower side of the vehicle open, and the upper case 14 constitutes the top surface 12A of the battery case 12.

[0039] The lower case 16 is formed in a roughly hat-shaped cross-section with the upper side of the vehicle open, and the lower case 16 constitutes the lower surface 12B of the battery case 12. The side surface 12C of the battery case 12 is composed of portions extending downward from both ends of the upper surface 12A in the vehicle width direction and portions extending upward from both ends of the lower surface 12B in the vehicle width direction, and a flange 12D extends outward in the vehicle width direction from the side surface 12C.

[0040] The flange 12D is formed by overlapping and welding the upper case 14 and the lower case 16. A reinforcing panel 18 is provided below the flange 12D on the lower case 16. The reinforcing panel 18 is joined to the side surface 12C of the battery case 12 and the flange 12D. Note that in Figure 1, the battery case 12 is simplified and the flange 12D is not shown; however, in reality, the flange 12D is formed around the entire circumference of the battery case 12.

[0041] In this embodiment, as an example, the upper surface 12A of the battery case 12 constitutes the passenger compartment floor. That is, in the vehicle understructure of this embodiment, there is no floor panel to constitute the passenger compartment floor, and the upper case 14 also serves as the floor panel. For this reason, a carpet (not shown) or the like is placed on the upper surface of the upper case 14.

[0042] As shown in Figure 1, a cross member 20 is positioned above the battery case 12. The cross member 20 has a closed cross section and extends in the vehicle width direction, and is attached to the battery frame 10.

[0043] The battery frame 10 is formed in a substantially frame shape and includes a battery front frame 22, a battery rear frame 24, and a pair of left and right battery side frames 26. The battery front frame 22, battery rear frame 24, and battery side frames 26 may be integrally formed from metal, or they may be formed separately.

[0044] The battery front frame 22 is located at the front of the vehicle and extends in the vehicle width direction along the front end of the battery case 12. The front module 100, which constitutes the front of the vehicle, is joined to the battery front frame 22 (see Figure 4).

[0045] The battery rear frame 24 is located at the rear of the vehicle's understructure and extends in the vehicle width direction along the rear end of the battery case 12. The rear module 102, which constitutes the rear of the vehicle, is joined to the battery rear frame 24 (see Figure 4).

[0046] The right end of the battery front frame 22 and the right end of the battery rear frame 24 are connected in the front-to-rear direction of the vehicle by the right battery side frame 26. In addition, the left end of the battery front frame 22 and the left end of the battery rear frame 24 are connected in the front-to-rear direction of the vehicle by the left battery side frame 26.

[0047] A pair of left and right battery side frames 26 are provided on both sides of the battery case 12 in the vehicle width direction, and extend in the vehicle longitudinal direction along the side surface 12C of the battery case 12. As shown in Figure 2, the battery side frames 26 are formed in a closed cross-section, and the internal space of the battery side frames 26 is divided into multiple spaces by partition walls. Dividing the internal space of the battery side frames 26 with partition walls can enhance the energy absorption effect during a side collision, but partition walls are not required.

[0048] A cross member 20 is installed between a pair of left and right battery side frames 26. In this embodiment, as an example, two cross members 20 are arranged with a gap between them in the front-rear direction of the vehicle.

[0049] The front cross member 20 is positioned slightly forward of the vehicle from the center of the battery side frame 26 in the vehicle's longitudinal direction. The right end of the front cross member 20 abuts against the right battery side frame 26 and is connected to the battery side frame 26 by a right connecting member 28R. The left end of the cross member 20 abuts against the left battery side frame 26 and is connected to the battery side frame 26 by a left connecting member 28L.

[0050] As shown in Figure 2, the left connecting member 28L is a bracket that connects the cross member 20 and the battery side frame 26. In a cross-sectional view from the front-rear direction of the vehicle, the left connecting member 28L has a roughly crank-shaped portion that includes a portion that overlaps the upper surface of the cross member 20 and a portion that overlaps the upper surface of the battery side frame 26. The left connecting member 28L is joined to the cross member 20 and the battery side frame 26 by welding or other means. The right connecting member 28R has a shape that is symmetrical to the left connecting member 28L.

[0051] The rear cross member 20 is positioned in the center of the battery side frame 26 in the vehicle width direction. The right end of the rear cross member 20 abuts against the right battery side frame 26 and is connected to the battery side frame 26 by a right connecting member 28R. The left end of the cross member 20 abuts against the left battery side frame 26 and is connected to the battery side frame 26 by a left connecting member 28L.

[0052] Vehicle seats S are fixed to the front and rear cross members 20. Since the front and rear cross members 20 have the same configuration, the following explanation will only describe the front cross member 20, and the explanation of the rear cross member 20 will be omitted. do.

[0053] Figure 3 is an enlarged cross-sectional view showing the state when cut along line 3-3 in Figure 1. As shown in Figure 3, the cross member 20 is formed in a shape in which two closed cross sections are aligned in the longitudinal direction of the vehicle when viewed from the vehicle width direction. Specifically, the cross member 20 is composed of an upper wall portion 30 and a lower wall portion 32, which includes a front wall portion 34, a rear wall portion 36, and a partition wall portion 38.

[0054] The upper wall portion 30 extends in the longitudinal direction and the vehicle width direction, and is composed of a front upper wall portion 30A on the front side and a rear upper wall portion 30B on the rear side, flanking the bulkhead portion 38. The lower wall portion 32 also extends in the longitudinal direction and the vehicle width direction, and is composed of a front lower wall portion 32A on the front side and a rear lower wall portion 32B on the rear side, flanking the bulkhead portion 38.

[0055] The front wall portion 34 extends in the vehicle's vertical direction and vehicle width direction, and connects the front end of the front upper wall portion 30A and the front end of the front lower wall portion 32A vertically. The rear wall portion 36 extends in the vehicle's vertical direction and vehicle width direction, and connects the rear end of the rear upper wall portion 30B and the rear end of the rear lower wall portion 32B vertically.

[0056] The bulkhead section 38 extends in the vertical and horizontal directions of the vehicle, and connects the upper wall section 30 and the lower wall section 32 vertically. As a result, the bulkhead section 38 divides the internal space of the cross member 20 into front and rear sections.

[0057] In this embodiment, the cross member 20 is formed by pressing and bending a single rigid plate. Specifically, the cross member 20 is formed from a series of rigid plates in the following order: front lower wall portion 32A, front wall portion 34, front upper wall portion 30A, partition wall portion 38, rear lower wall portion 32B, rear wall portion 36, and rear upper wall portion 30B.

[0058] Furthermore, a recess 32C is formed in the front lower wall portion 32A of the cross member 20 at a position corresponding to the fastening portion 40B, which will be described later, and a recess 32D is formed in the rear lower wall portion 32B at a position corresponding to the fastening portion 40B, which will be described later. The recess 32C is formed in the central part of the front lower wall portion 32A in the vehicle's longitudinal direction, and the recess 32D is formed in the central part of the rear lower wall portion 32B in the vehicle's longitudinal direction.

[0059] As shown in Figures 1 and 3, a bracket 40 is provided between the battery case 12 and the cross member 20. Two brackets 40 are provided spaced apart in the vehicle width direction, and each is positioned corresponding to the cross member 20. The front bracket 40 and the rear bracket 40 have the same configuration, so in the following description, only the front bracket 40 will be described, and the description of the rear bracket 40 will be omitted.

[0060] The bracket 40 is formed in a substantially elongated plate shape with the vehicle width direction as its longitudinal direction. As shown in Figure 3, the bracket 40 is composed of a joint portion 40A joined to the upper surface of the battery case 12 and a fastening portion 40B to which a bolt 44, which is a fastener, is attached.

[0061] The joint portion 40A is formed in a substantially flat shape and is superimposed on the upper surface of the upper case 14, and is joined to the upper case 14 by spot welding or the like. The joint portion 40A is provided at three locations on the bracket 40: the front end, the rear end, and the center in the front-rear direction. A fastening portion 40B is formed between the front end and the center of the bracket 40. A fastening portion 40B is also formed between the rear end and the center of the bracket 40.

[0062] The fastening portion 40B is composed of a convex bead 41 that extends in the vehicle width direction. Therefore, a space is provided between the fastening portion 40B and the battery case 12. As shown in Figure 1, the convex bead 41 extends to the end of the upper surface of the upper case 14. In addition, both ends of the bracket 40 are bent along the side surface 12C of the battery case 12, with both ends in the vehicle width direction of the battery case 12 being bent along the side surface 12C of the battery case 12.

[0063] As shown in Figure 2, the vehicle-width end of the bracket 40 has a vertical wall portion 42 formed by bending along the side surface 12C of the battery case 12. Furthermore, the vehicle-width end of the bracket 40 is bent outward in the vehicle-width direction from the lower end of the vertical wall portion 42 along the flange 12D of the battery case 12, and is joined to the flange 12D by spot welding or the like.

[0064] Here, a gap is provided between the vertical wall portion 42 of the bracket 40 and the side surface 12C of the battery case 12. For this reason, in this embodiment, the bracket 40 is joined to the top surface and flange 12D of the battery case 12, but the bracket 40 is not joined to the side surface 12C of the battery case 12.

[0065] As shown in Figure 3, a bolt 44 is inserted through the fastening portion 40B of the bracket 40. The bolt 44 consists of a head 44A and a shaft portion 44B, with the head 44A of the bolt 44 located in the space between the fastening portion 40B of the bracket 40 and the upper surface 12A of the battery case 12.

[0066] In this embodiment, as an example, the head 44A of the bolt 44 is joined to the lower surface of the fastening portion 40B of the bracket 40 by welding or the like, and the thickness of the head 44A of the bolt 44 is thinner than the height dimension of the space between the fastening portion 40B of the bracket 40 and the upper surface 12A of the battery case 12. For this reason, the head 44A of the bolt 44 does not come into contact with the upper surface 12A of the battery case 12, and a small gap is provided between the head 44A and the upper surface 12A of the battery case 12.

[0067] The shaft portion 44B of the bolt 44 extends upward from the head portion 44A towards the vehicle. The shaft portion 44B is inserted through a through hole 41A formed in the convex bead 41 of the bracket 40 and through hole 32E formed in the lower wall portion 32 of the cross member 20. The tip of the shaft portion 44B of the bolt 44 is screwed onto a nut 46 within the cross section of the cross member 20, and the bracket 40 and the cross member 20 are fastened together by the bolt 44 and the nut 46. Working holes 30C and 30D are formed in the front upper wall portion 30A and the rear upper wall portion 30B of the cross member 20, respectively, and a tool is inserted into the cross section of the cross member 20 through working holes 30C and 30D to screw the nut 46 onto the bolt 44.

[0068] Figure 4 is a plan view showing the main parts of the vehicle understructure according to the embodiment, and is a diagram showing the state before the cross member 20 is attached. As shown in Figure 4, in this embodiment, as an example, six through holes 41A are formed in each bracket 40, and bolts 44 are attached to these through holes 41A.

[0069] In the front bracket 40, five through holes 41A are formed at intervals in the vehicle width direction relative to the front convex bead 41. In addition, one through hole 41A is formed in the center of the rear convex bead 41 in the vehicle width direction of the front bracket 40.

[0070] In the rear bracket 40, one through-hole 41A is formed in the center of the front convex bead 41 in the vehicle width direction. In addition, five through-holes 41A are formed in the rear convex bead 41 of the rear bracket 40, spaced apart in the vehicle width direction. The positions of these through-holes 41A are set so as not to overlap with the seat rails of the vehicle seat S in a plan view. It is established.

[0071] (action) Next, the operation of the vehicle understructure according to this embodiment will be explained.

[0072] As shown in Figure 1, in the vehicle understructure according to this embodiment, a battery case 12 containing a battery BT is positioned at the bottom of the vehicle, and a cross member 20 extending in the vehicle width direction is positioned above the battery case 12. This allows the collision load applied during a side collision of the vehicle to be transmitted to the non-collision side by the cross member 20.

[0073] Furthermore, a bracket 40 is provided between the battery case 12 and the cross member 20. The bracket 40 includes a joint portion 40A joined to the upper surface 12A of the battery case 12, and a fastening portion 40B to which a bolt 44 inserted into the cross member 20 is attached. In this way, by providing a fastening portion 40B on the bracket 40 and attaching the bolt 44 to this fastening portion 40B and inserting it into the cross member 20, it is not necessary to directly fasten the battery case 12 and the cross member 20 with a bolt 44. As a result, it is not necessary to drill holes in the battery case 12, and the performance of the battery BT can be maintained well.

[0074] In particular, in this embodiment, by providing the head 44A of the bolt 44 in the space between the fastening portion 40B and the upper surface of the battery case 12, it is possible to prevent the bolt 44 from coming off the bracket 40 and to maintain a good fastening state of the cross member 20. Furthermore, since the shaft portion 44B of the bolt 44 is inserted through the bracket 40 and the cross member 20, the bracket 40 and the cross member 20 can be sandwiched between the head 44A of the bolt 44 and the nut 46, thereby firmly fixing the bracket 40 and the cross member 20.

[0075] Furthermore, in this embodiment, recesses 32C and 32D are formed in the lower wall portion 32 of the cross member 20, and by inserting the fastening portion 40B into these recesses 32C and 32D, the portion of the cross member 20 other than the recesses 32C and 32D can be bonded to the bracket 40 on a surface.

[0076] Furthermore, in this embodiment, as shown in Figure 2, both ends of the bracket 40 in the vehicle width direction are bent along the side surface 12C of the battery case 12, so the bracket 40 can reinforce the side surface of the battery case 12.

[0077] In particular, in this embodiment, since the bracket 40 extends to the flange 12D of the battery case 12, reinforcement can be provided from the side of the battery case 12 to the flange 12D. Furthermore, by providing a gap between the side surface 12C of the battery case 12 and the bracket 40, the gap can be compressed by the impact load applied during a side collision, absorbing at least a portion of the impact load. As a result, the protective performance of the battery BT during a side collision is improved compared to a structure in which there is no gap between the side surface 12C of the battery case 12 and the bracket 40.

[0078] Furthermore, in this embodiment, since the upper surface of the battery case 12 constitutes the vehicle interior floor, there is no need to provide a separate floor panel. As a result, the number of parts and assembly man-hours can be reduced compared to a structure with a floor panel.

[0079] Furthermore, as shown in Figures 1 and 3, in this embodiment, a convex bead 41 is formed on the bracket 40. This increases the rigidity of the fastening portion 40B in the bracket 40, suppressing buckling of the bracket during a side impact. In addition, since the convex bead 41 provides a ridge line extending in the vehicle width direction, the vehicle impact load can be transmitted along the ridge line.

[0080] Furthermore, in this embodiment, the cross member 20 is spanned between the battery side frames 26. Because of this configuration, the side impact load is transmitted to the battery side frame 26 on the non-collision side via the cross member 20, thereby effectively protecting the battery BT. In particular, since multiple cross members 20 are attached to the battery case 12 by multiple brackets 40, the protective performance of the battery BT is improved.

[0081] (First variation) Next, a first modified example of the vehicle's understructure will be described with reference to Figure 5. As with the embodiment, the same reference numerals will be used for the components, and their descriptions will be omitted as appropriate.

[0082] Figure 5 is an enlarged cross-sectional view corresponding to Figure 4, showing the vehicle understructure according to the first modified example. As shown in Figure 5, in the first modified example of the vehicle understructure, the shape of the vertical wall portion 42 of the bracket 40 is different.

[0083] In this modified example, vertical wall portions 42 are formed on both sides of the bracket 40 in the vehicle width direction, and these vertical wall portions 42 are bent along the side surface 12C of the battery case 12, and the vertical wall portions 42 are in contact with the side surface 12C of the battery case 12. The lower end of the vertical wall portion 42 is located on the side surface of the battery case 12, and the vertical wall portion 42 and the side surface 12C of the battery case 12 are joined together.

[0084] In this modified example, since the bracket 40 does not extend to the flange 12D of the battery case 12, the flange 12D can be directly joined to the battery side frame 26. However, from the viewpoint of protecting the battery BT in the event of a side impact, it is preferable to leave a gap between the vertical wall portion 42 and the side surface 12C, as in the embodiment.

[0085] (Second variation) Next, a second modified example of the vehicle's understructure will be described with reference to Figure 6. As with the embodiment, the same reference numerals are used for the components, and their descriptions will be omitted as appropriate.

[0086] Figure 6 is an enlarged cross-sectional view corresponding to Figure 3, showing the vehicle understructure according to the second modified example. As shown in Figure 6, in the second modified example of the vehicle understructure, a vibration damping member 62 is provided in the space between the convex bead 41 and the upper surface 12A of the battery case 12.

[0087] The vibration-damping member 62 is formed in a roughly annular shape using, for example, rubber, and has a thickness approximately the same as the gap between the convex bead 41 and the upper case 14. The upper surface of the vibration-damping member 62 is in contact with the convex bead 41, and the lower surface of the vibration-damping member 62 is in contact with the upper case 14.

[0088] In this modified example, the vibration-damping member 62 can absorb at least a portion of the vibrations transmitted between the battery case 12 and the cross member 20.

[0089] (Third variation) Next, a third modified example of the vehicle's understructure will be described with reference to Figure 7. As with the embodiment, the same reference numerals are used for the components, and their descriptions will be omitted as appropriate.

[0090] Figure 7 is an enlarged cross-sectional view corresponding to Figure 3, showing the vehicle understructure according to the third modified example. As shown in Figure 7, in the third modified example of the vehicle understructure, a vibration damping member 62 is provided in the space between the convex bead 41 and the upper surface 12A of the battery case 12, similar to the second modified example.

[0091] Furthermore, in this modified example, the bolt 44, which serves as a fastener, penetrates the upper wall portion 30 of the cross member 20. Specifically, the shaft portion 44B of the bolt 44 is formed to be longer than in the embodiment. It penetrates the rear upper wall portion 30B of the cross member 20. Then, a nut 46 is screwed onto it from above.

[0092] In this modified example, it is not necessary to form a working hole 30D in the upper wall portion 30 of the cross member 20. Furthermore, since it is sufficient to form a hole large enough for the shaft portion 44B of the bolt 44 to pass through, a decrease in the rigidity of the cross member 20 can be suppressed.

[0093] (Fourth variation) Next, a fourth modified example of the vehicle's understructure will be described with reference to Figure 8. As with the embodiment, the same reference numerals are used for the components, and their descriptions will be omitted as appropriate.

[0094] Figure 8 is an enlarged cross-sectional view corresponding to Figure 2, showing the vehicle understructure according to the fourth modified example. As shown in Figure 8, in the fourth modified example of the vehicle understructure, the cross member 20 is detachably attached to the battery side frame 26.

[0095] Specifically, the left end of the cross member 20 abuts against the left battery side frame 26 and is connected to the battery side frame 26 by a left connecting member 28L. The left connecting member 28L is formed in the same shape as in the embodiment, and the left connecting member 28L and the upper surface of the battery side frame 26 are mechanically fastened together by bolts 64 and nuts 66.

[0096] Furthermore, the left connecting member 28L and the side of the battery side frame 26 are mechanically fastened together by bolts 68 and nuts 70. On the other hand, the left connecting member 28L and the cross member 20 are joined together by spot welding or the like. Although not shown in the diagram, the right connecting member 28R is similarly mechanically fastened to the cross member 20.

[0097] In this modified example, since the left connecting member 28L and the right connecting member 28R are mechanically fastened to the cross member 20, the cross member 20 can be detached from the battery side frame 26 by removing bolts 64, 68, etc. Here, since the vehicle seat S is attached to the cross member 20, the vehicle seat S can be removed along with the cross member 20 by detaching the cross member 20. Furthermore, by forming multiple bolt holes in the battery side frame 26 along the front-rear direction of the vehicle, the cross member 20 can be fastened to different positions, and the position of the vehicle seat S can be changed.

[0098] The vehicle understructure according to the present invention has been described above, but it goes without saying that it can be implemented in various forms without departing from the spirit of the present invention. For example, in the above embodiments and modifications, the fastening portion 40B is formed by including a convex bead 41 extending in the vehicle width direction, as shown in Figure 3, but it is not limited to this, and the fastening portion may be configured in other shapes. As an example, the fastening portion may be configured by including a portion that bulges out in a substantially circular shape in plan view. In this case, only the portion to which the bolt 44 is attached may be bulging.

[0099] Furthermore, although bolts 44 were used as fasteners in the above embodiments and modifications, the invention is not limited to bolts 44. Other fasteners that are mechanically fastened, such as rivets and clips, may also be used.

[0100] Furthermore, in the above embodiments and modifications, as shown in Figure 4, the bracket 40 is formed as a long plate that extends from the right end to the left end of the battery case 12, but it is not limited to this. For example, multiple brackets may be arranged at intervals in the vehicle width direction.

[0101] The following additional information is disclosed regarding the above embodiment.

[0102] (Note 1) Located at the bottom of the vehicle, the battery case houses the battery, A cross member positioned above the battery case and extending in the vehicle width direction, A bracket comprising a joint portion provided between the battery case and the cross member and joined to the upper surface of the battery case, and a fastening portion having an insertion hole formed therein, A fastener inserted through the aforementioned through hole to fix the cross member and the bracket, It has, The lower end of the fastener is positioned above the vehicle above the upper surface of the battery case that faces the fastener. Vehicle understructure. (Note 2) The fastening portion protrudes upward from the joint portion of the vehicle. The vehicle understructure as described in Appendix 1, wherein a part of the fastener is positioned in the space between the fastening portion and the upper surface of the battery case. (Note 3) The cross member is formed in a closed cross-sectional shape, The vehicle understructure as described in Appendix 2, wherein a recess is formed in the lower wall portion of the cross member at a position corresponding to the fastening portion. (Note 4) The battery case has sides that extend downward from both ends of the upper surface in the vehicle width direction toward the vehicle side, The vehicle understructure according to any one of Appendix 1 to Appendix 3, wherein the bracket extends in the vehicle width direction, and the outer side of the bracket in the vehicle width direction is bent along the side surface. (Note 5) The battery case is provided with a flange extending outward in the vehicle width direction from the side, The bracket is joined to the flange, and is part of the vehicle understructure as described in Appendix 4. (Note 6) A gap is provided between the bracket and the side surface, as described in Appendix 5, for the vehicle understructure. (Note 7) The upper surface of the battery case is a vehicle understructure as described in any one of the appendices 1 to 6, which constitutes the floor of the vehicle compartment. (Note 8) The fastening portion is configured to include a convex bead extending in the vehicle width direction, as described in any one of Appendix 1 to Appendix 7 of the vehicle understructure. (Note 9) The fastener is a bolt having a head and a shaft, The head is positioned in the space between the fastening portion and the upper surface of the battery case. The vehicle understructure as described in Appendix 2, wherein the shaft portion is inserted through the bracket and the cross member. (Note 10) The battery case is provided with a pair of left and right battery side frames on both sides in the vehicle width direction, extending along the sides in the vehicle front-rear direction, The cross member is connected to a pair of left and right battery side frames, in the vehicle understructure as described in Appendix 4. (Note 11) The vehicle understructure as described in Appendix 10, wherein the cross member is configured to allow the attachment of a vehicle seat and is detachably attached to the battery side frame. (Note 12) The aforementioned brackets are arranged in multiple quantities at intervals in the longitudinal direction of the vehicle, as described in any one of the vehicle understructures described in Appendix 1 to Appendix 11. (Note 13) The vehicle understructure as described in Appendix 2, wherein a vibration-damping member is arranged in the space between the fastening portion and the upper surface of the battery case. [Explanation of Symbols]

[0103] 12 Battery Cases 12A top 12C side 12D flange 18 Side Frames 20 Crossmember 26 Battery side frame 32 Lower wall part 32C, 32D recess 40 brackets 40A joint 40B Fastening part 41 Convex bead 44 bolts (fasteners) 44A Head 44B Shaft 62 Vibration Isolator BT Battery S Vehicle Seat

Claims

1. Located at the bottom of the vehicle, the battery case houses the battery, A cross member positioned above the battery case and extending in the vehicle width direction, A bracket comprising a joint portion provided between the battery case and the cross member and joined to the upper surface of the battery case, and a fastening portion having an insertion hole formed therein, A fastener inserted through the aforementioned through hole to fix the cross member and the bracket, It has, A vehicle understructure in which the lower end of the fastener is positioned above the upper surface of the battery case opposite to the fastener.

2. The fastening portion protrudes upward from the joint portion of the vehicle. The vehicle understructure according to claim 1, wherein a part of the fastener is arranged in the space between the fastening portion and the upper surface of the battery case.

3. The cross member is formed in a closed cross-sectional shape, The vehicle understructure according to claim 2, wherein a recess is formed in the lower wall portion of the cross member at a position corresponding to the fastening portion.

4. The battery case has sides that extend downward from both ends of the upper surface in the vehicle width direction toward the vehicle side, The vehicle understructure according to claim 1, wherein the bracket extends in the vehicle width direction, and the outer side of the bracket in the vehicle width direction is bent along the side surface.

5. The battery case is provided with a flange extending outward in the vehicle width direction from the side, The vehicle understructure according to claim 4, wherein the bracket is joined to the flange.

6. The vehicle understructure according to claim 5, wherein a gap is provided between the bracket and the side surface.

7. The vehicle understructure according to claim 1, wherein the upper surface of the battery case constitutes the floor of the vehicle compartment.

8. The vehicle understructure according to claim 2, wherein the fastening portion is configured to include a convex bead extending in the vehicle width direction.

9. The fastener is a bolt having a head and a shaft, The head is positioned in the space between the fastening portion and the upper surface of the battery case. The vehicle understructure according to claim 2, wherein the shaft portion is inserted through the bracket and the cross member.

10. The battery case is provided with a pair of left and right battery side frames on both sides in the vehicle width direction, extending along the sides in the vehicle front-rear direction, The vehicle understructure according to claim 4, wherein the cross member is connected to a pair of left and right battery side frames.

11. The vehicle understructure according to claim 10, wherein the cross member is configured to be able to mount a vehicle seat and is configured to be detachable from the battery side frame.

12. The brackets are arranged in multiples at intervals in the front-rear direction of the vehicle, as described in claim 1. The undercarriage structure of the vehicle.

13. The vehicle understructure according to claim 2, wherein a vibration-damping member is disposed in the space between the fastening portion and the upper surface of the battery case.

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