Vehicle lower part structure

Abstract

To provide a vehicle lower part structure that is able to satisfactorily maintain the performance of a battery, in a structure having a cross member extending in a vehicle width direction.SOLUTION: A vehicle lower part structure includes: a battery case 12 disposed in a lower part of a vehicle and housing a battery BT; a cross member 20 disposed on a vehicle upper side of the battery case 12 and extending in a vehicle width direction; a bracket 40 provided between the battery case 12 and the cross member 20, the bracket including a joint portion 40A joined to an 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 battery case 12 to each other.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle undercarriage. [Background technology]

[0002] Patent Document 1 discloses a vehicle underbody structure equipped with a battery frame that surrounds a battery. The vehicle underbody structure described in Patent Document 1 is also provided with a cover plate that covers the battery from above, and this cover plate forms the floor of the vehicle compartment. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Chinese Patent Application Publication No. 114940214 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, a structure that includes a cross member extending in the vehicle width direction to transmit collision loads during a side collision is common, but in a structure in which the cover plate of the battery case also serves as a floor panel, such as the structure described in Patent Document 1, the cross member is fixed to the cover plate. However, drilling holes in the cover plate to directly fix the cross member to the cover plate could affect battery performance.

[0005] An object of the present invention is to provide a vehicle underbody structure that can maintain good battery performance in a structure that includes a cross member extending in the vehicle width direction. [Means for solving the problem]

[0006] The first embodiment of the vehicle undercarriage structure comprises a battery case arranged under the vehicle and housing a battery, a cross member arranged above the battery case and extending in the vehicle width direction, a bracket arranged between the battery case and the cross member and including a joint joined to the upper surface of the battery case and a fastening portion having an insertion hole formed therein, and a fastener inserted into the insertion hole to secure the cross member and the battery case.

[0007] In the vehicle undercarriage structure of the first aspect, a battery case containing a battery is disposed under the vehicle. Also, a cross member extending in the vehicle width direction is disposed above the battery case. This allows the cross member to transmit the collision load input during a side collision of the vehicle (hereinafter referred to as "side collision") to the side opposite the collision.

[0008] A bracket is provided between the battery case and the cross member. The bracket includes a joint portion joined to the top surface of the battery case and a fastening portion with an insertion hole. By providing the fastening portion on the bracket and attaching a fastener to the fastening portion and inserting it into the cross member, it is not necessary to fasten the battery case and cross member directly with a fastener.

[0009] The second aspect of the vehicle undercarriage structure is the first aspect, in which the fastening portion protrudes from the joint portion toward the top of the vehicle, and a portion of the fastener is arranged in the space between the fastening portion and the top surface of the battery case.The fastening portion protrudes from the joint portion toward the top of the vehicle, and a portion of the fastener is arranged in the space between the fastening portion and the top surface of the battery case.

[0010] In the vehicle undercarriage structure of the second aspect, by locating part of the fastener in the space between the fastening portion and the upper surface of the battery case, the fastener can be prevented from coming off the bracket, and the fastening state of the cross member can be maintained in good condition.

[0011] A third aspect of the vehicle undercarriage structure is the second aspect, wherein the cross member is formed in a closed cross-section, 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 underbody structure of the third aspect, 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 by surface bonding.

[0013] In the fourth aspect of the vehicle undercarriage structure, in the first aspect, the battery case has side surfaces extending from both vehicle width direction end portions of the upper surface toward the lower side of the vehicle, and 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 surfaces.

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

[0015] The vehicle underbody structure of a fifth aspect is the fourth aspect, wherein the battery case includes a flange extending outward in a vehicle width direction from the side surface, and the bracket is joined to the flange.

[0016] In the vehicle underbody structure of the fifth aspect, the bracket extends up to the flange of the battery case, so that the battery case can be reinforced from the side surface to the flange.

[0017] The vehicle underbody structure of a sixth aspect is the fifth aspect, wherein a gap is provided between the bracket and the side surface.

[0018] In the vehicle underbody structure of the sixth aspect, the bracket is deformed by the collision load input during a side collision, and the gap between the side surface of the battery case and the bracket is collapsed, thereby making it possible to absorb at least a portion of the collision load.

[0019] A seventh aspect of the vehicle underbody structure is the first aspect, wherein the upper surface of the battery case forms a vehicle compartment floor.

[0020] In the seventh aspect of the vehicle undercarriage structure, the upper surface of the battery case forms the vehicle interior floor, eliminating the need for a separate floor panel. As a result, the number of parts and assembly steps can be reduced compared to a structure that includes a floor panel.

[0021] The vehicle underbody structure of an eighth aspect is the second aspect, wherein the fastening portion includes a convex bead extending in the vehicle width direction.

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

[0023] A ninth aspect of the vehicle undercarriage structure is the second aspect, in which the fastener is a bolt having a head and a shaft, the head being positioned in the space between the fastening portion and the top surface of the battery case, and the shaft being inserted through the bracket and the cross member.

[0024] In the vehicle undercarriage structure of the ninth aspect, the bolt head is positioned in the space between the fastening portion and the upper surface of the battery case, thereby preventing the bolt from coming loose. Also, because the bolt shank is inserted through the bracket and the cross member, the bracket and cross member can be clamped between the bolt head and the nut, firmly securing the bracket and cross member.

[0025] The vehicle undercarriage structure of the 10th aspect is the 4th aspect, which comprises 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 fore-and-aft direction of the vehicle along the side surfaces, and the cross member is installed between the pair of left and right battery side frames.

[0026] In the vehicle underbody structure of the tenth aspect, the cross member is installed between the battery side frames, so that the side collision load is transmitted via the cross member to the battery side frame on the opposite side to the collision, thereby providing good protection for the battery.

[0027] An eleventh aspect of the vehicle underbody structure is the tenth aspect, wherein the cross member is configured to allow a vehicle seat to be attached thereto and is configured to be detachable from the battery side frame.

[0028] In the vehicle underbody structure of the eleventh aspect, the cross member is detachable from the battery side frame, so that the vehicle seat can be removed from the vehicle simply by removing the cross member from the battery side frame.

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

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

[0031] The vehicle underbody structure of a thirteenth aspect is the second aspect, wherein a vibration-isolating member is disposed in the space between the fastening portion and the upper surface of the battery case.

[0032] In the vehicle underbody structure of the thirteenth aspect, vibrations from the vehicle seat can be prevented from being input to the battery by disposing a vibration-isolating member in the space between the fastening portion and the upper surface of the battery case. [Effects of the Invention]

[0033] As described above, the vehicle underbody structure according to the present invention can maintain good battery performance in a structure that includes a cross member extending in the vehicle width direction. [Brief explanation of the drawings]

[0034] [Figure 1] 1 is an exploded perspective view showing a vehicle undercarriage structure according to an embodiment; [Figure 2] FIG. 2 is an enlarged cross-sectional view showing a state cut along line 2-2 in FIG. [Figure 3] 3 is an enlarged cross-sectional view showing a state cut along line 3-3 in FIG. 1. FIG. [Figure 4] 1 is a plan view showing a main part of a vehicle undercarriage structure according to an embodiment, illustrating a state before a cross member is attached. FIG. [Figure 5] 5 is an enlarged cross-sectional view corresponding to FIG. 4, showing a vehicle underbody structure according to a first modified example. FIG. [Figure 6] FIG. 4 is an enlarged cross-sectional view corresponding to FIG. 3, showing a vehicle underbody structure according to a second modified example. [Figure 7] FIG. 4 is an enlarged cross-sectional view corresponding to FIG. 3, showing a vehicle underbody structure according to a third modified example. [Figure 8] 10 is an enlarged cross-sectional view corresponding to FIG. 2, showing a vehicle underbody structure according to a fourth modified example. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0035] A vehicle underbody structure according to an embodiment will be described with reference to the drawings.

[0036] 1 is a perspective view showing a part of a vehicle undercarriage according to an embodiment. Note that the arrows FR, UP, RH, and LH in the figure indicate the vehicle forward direction, vehicle upward direction, vehicle rightward direction, and vehicle leftward direction, respectively. In the following description, when the directions of front / rear, up / down, and left / right are used unless otherwise specified, they refer to front / rear in the vehicle front / rear direction, up / down in the vehicle up / down direction, and left / right in the vehicle left / right direction (width direction), respectively.

[0037] As shown in FIG. 1, the vehicle underbody structure of this embodiment includes a battery frame 10 and a battery case 12. The battery case 12 is disposed under a vehicle to which the vehicle underbody structure is applied. FIG. 2 is an enlarged cross-sectional view showing a state cut along line 2-2 in FIG. 1. As shown in FIG. 2, a battery BT is housed inside the battery case 12. The battery BT may be formed in a generally box-like shape, like a battery module, housing a plurality of cells, or may be a long rectangular blade battery.

[0038] The battery case 12 is configured to include an upper case 14 and a lower case 16, and has an upper surface 12A, a lower surface 12B, and side surfaces 12C. The upper case 14 is formed with a generally hat-shaped cross section that is open toward the lower side of the vehicle, and the upper case 14 forms the upper surface 12A of the battery case 12.

[0039] The lower case 16 has a generally hat-shaped cross section that is open on the vehicle upper side, and the lower case 16 forms the lower surface 12B of the battery case 12. The side surface 12C of the battery case 12 includes a portion extending downward from both ends of the upper surface 12A in the vehicle width direction and a portion 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 on the lower case 16 below the flange 12D. The reinforcing panel 18 is joined to the side surface 12C of the battery case 12 and the flange 12D. Note that, although the battery case 12 is illustrated in a simplified manner in FIG. 1 and the flange 12D is not shown, in reality the flange 12D is formed around the entire periphery of the battery case 12.

[0041] In this embodiment, as an example, the upper surface 12A of the battery case 12 forms the floor of the vehicle compartment. That is, in the vehicle undercarriage structure of this embodiment, a floor panel for forming the floor surface of the vehicle compartment is not provided, and the upper case 14 also serves as the floor panel. For this reason, a carpet (not shown) or the like is provided on the upper surface of the upper case 14.

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

[0043] The battery frame 10 is formed in a generally frame-like 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, the battery rear frame 24, and the battery side frames 26 may be integrally formed from metal, or 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. A front module 100 that constitutes the front of the vehicle is joined to the battery front frame 22 (see FIG. 4).

[0045] The battery rear frame 24 is located at the rear of the vehicle undercarriage and extends in the vehicle width direction along the rear end of the battery case 12. A rear module 102 that constitutes the rear of the vehicle is joined to the battery rear frame 24 (see FIG. 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 front-rear direction along the side surface 12C of the battery case 12. As shown in Fig. 2, the battery side frames 26 are formed with a closed cross section, and the internal space of the battery side frames 26 is divided into multiple spaces by partition walls. Note that dividing the internal space of the battery side frames 26 with partition walls can improve the energy absorption effect in the event of a side collision, but partition walls do not necessarily have to be provided.

[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 spaced apart in the front-rear direction of the vehicle.

[0049] The front cross member 20 is disposed slightly forward of the vehicle longitudinal center of the battery side frame 26. 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] 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 seen from the vehicle front-rear direction, the left connecting member 28L has a generally 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 both the cross member 20 and the battery side frame 26 by welding or the like. The right connecting member 28R has a shape that is bilaterally symmetrical to the left connecting member 28L.

[0051] The rear cross member 20 is disposed 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] A vehicle seat S is fixed to the front and rear cross members 20. Since the front cross member 20 and the rear cross member 20 have the same configuration, the following description will only cover the front cross member 20, and the description of the rear cross member 20 will be omitted.

[0053] Figure 3 is an enlarged cross-sectional view taken 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 in the vehicle width direction. Specifically, the cross member 20 is configured to include an upper wall portion 30, a lower wall portion 32, a front wall portion 34, a rear wall portion 36, and a partition portion 38.

[0054] The upper wall portion 30 extends in the vehicle longitudinal direction and the vehicle width direction, and is configured to include a front upper wall portion 30A on the front side and a rear upper wall portion 30B on the rear side, with the partition wall portion 38 sandwiched between them. The lower wall portion 32 extends in the vehicle longitudinal direction and the vehicle width direction, and is configured to include a front lower wall portion 32A on the front side and a rear lower wall portion 32B on the rear side, with the partition wall portion 38 sandwiched between them.

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

[0056] The partition wall portion 38 extends in the vehicle vertical direction and the vehicle width direction, and vertically connects the upper wall portion 30 and the lower wall portion 32. Therefore, the partition wall portion 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 of a continuous rigid plate that includes the front lower wall portion 32A, the front wall portion 34, the front upper wall portion 30A, the partition wall portion 38, the rear lower wall portion 32B, the rear wall portion 36, and the rear upper wall portion 30B in this order.

[0058] Furthermore, a recess 32C is formed in the front lower wall portion 32A of the cross member 20 at a position corresponding to a fastening portion 40B (described later), and a recess 32D is formed in the rear lower wall portion 32B at a position corresponding to a fastening portion 40B (described later). Recess 32C is formed in the center portion of the front lower wall portion 32A in the vehicle's fore-and-aft direction, and recess 32D is formed in the center portion of the rear lower wall portion 32B in the vehicle's fore-and-aft direction.

[0059] 1 and 3, brackets 40 are 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 bracket is provided at a position corresponding to the cross member 20. The front bracket 40 and the rear bracket 40 have the same configuration, so the following description will focus on the front bracket 40 and omit the description of the rear bracket 40.

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

[0061] The joint portion 40A is formed in a substantially flat plate shape and is superimposed on the top surface of the upper case 14, and is joined to the upper case 14 by spot welding or the like. The joint portions 40A are provided at three locations on the bracket 40: the front end, the rear end, and the center in the front-to-rear direction, and 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 configured to include a convex bead 41 extending in the vehicle width direction. Therefore, a space is provided between the fastening portion 40B and the battery case 12. As shown in FIG. 1 , the convex bead 41 extends to the end of the top surface of the upper case 14. In addition, both ends of the bracket 40 in the vehicle width direction of the battery case 12 are bent along the side surface 12C of the battery case 12.

[0063] 2, a vertical wall portion 42 is formed at the vehicle width direction end of the bracket 40 and is bent along the side surface 12C of the battery case 12. The vehicle width direction end of the bracket 40 is also bent from the lower end of the vertical wall portion 42 outward in the vehicle width direction along the flange 12D of the battery case 12 and 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 upper surface of the battery case 12 and the flange 12D, and is not joined to the side surface 12C of the battery case 12.

[0065] 3, a bolt 44 is inserted into the fastening portion 40B of the bracket 40. The bolt 44 includes a head portion 44A and a shaft portion 44B, and the head portion 44A of the bolt 44 is 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 by welding or the like to the underside of the fastening portion 40B of the bracket 40, 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. Therefore, the head 44A of the bolt 44 does not contact 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 shank 44B of the bolt 44 extends from the head 44A toward the upper side of the vehicle. The shank 44B is inserted through an insertion hole 41A formed in the convex bead 41 of the bracket 40 and an insertion hole 32E formed in the lower wall portion 32 of the cross member 20. The tip of the shank 44B of the bolt 44 is threadedly engaged with 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. The front upper wall portion 30A and the rear upper wall portion 30B of the cross member 20 are formed with work holes 30C and 30D, respectively, and a tool is inserted into the cross section of the cross member 20 through the work holes 30C and 30D to thread the nut 46 onto the bolt 44.

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

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

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

[0071] (action) Next, the operation of the vehicle underbody structure according to this embodiment will be described.

[0072] 1, in the vehicle undercarriage structure according to this embodiment, a battery case 12 accommodating a battery BT is disposed under the vehicle, and a cross member 20 extending in the vehicle width direction is disposed above the battery case 12. This allows the cross member 20 to transmit a collision load input during a side collision of the vehicle to the side opposite the collision.

[0073] A bracket 40 is provided between the battery case 12 and the cross member 20, and the bracket 40 includes a joining portion 40A joined to the upper surface 12A of the battery case 12 and a fastening portion 40B to which a bolt 44 is attached that is inserted into the cross member 20. In this way, by providing the 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 the 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 at a good level.

[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 maintain a good fastened state of the cross member 20. Furthermore, because the shank 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 clamped between the head 44A of the bolt 44 and the nut 46, and the bracket 40 and the cross member 20 can be firmly fixed together.

[0075] Furthermore, in this embodiment, recesses 32C and 32D are formed in the lower wall portion 32 of the cross member 20, and the fastening portion 40B is inserted into these recesses 32C and 32D, so that the portions of the cross member 20 other than the recesses 32C and 32D can be surface-bonded to the bracket 40.

[0076] Furthermore, in this embodiment, as shown in FIG. 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 that the side surface of the battery case 12 can be reinforced by the bracket 40.

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

[0078] In addition, in this embodiment, the upper surface of the battery case 12 forms the floor of the vehicle interior, eliminating the need for a separate floor panel. As a result, the number of parts and assembly steps can be reduced compared to a structure that includes a floor panel.

[0079] 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 of the bracket 40, making it possible to prevent the bracket from buckling during a side collision. Also, the convex bead 41 provides a ridgeline extending in the vehicle width direction, allowing the vehicle collision load to be transmitted along the ridgeline.

[0080] Furthermore, in this embodiment, since the cross member 20 is installed between the battery side frames 26, the side collision load is transmitted to the battery side frame 26 on the opposite side to the collision via the cross member 20, thereby providing excellent protection for the battery BT. In particular, since multiple cross members 20 are attached to the battery case 12 by multiple brackets 40, the protection performance for the battery BT is improved.

[0081] (First Modification) Next, a first modified example of the vehicle underbody structure will be described with reference to Fig. 5. Note that the same components as those in the embodiment will be denoted by the same reference numerals, and the description will be omitted where appropriate.

[0082] Fig. 5 is an enlarged cross-sectional view showing a vehicle underbody structure according to a first modified example, and corresponds to Fig. 4. As shown in Fig. 5, in the first modified example of the vehicle underbody structure, the shape of the vertical wall portion 42 of the bracket 40 is different.

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

[0084] In this modified example, the bracket 40 does not extend to the flange 12D of the battery case 12, so the flange 12D can be directly joined to the battery side frame 26. From the perspective of protecting the battery BT in a side collision, it is preferable to provide a gap between the vertical wall portion 42 and the side surface 12C as in the embodiment.

[0085] (Second Modification) Next, a second modified example of the vehicle underbody structure will be described with reference to Fig. 6. Note that the same components as those in the embodiment will be denoted by the same reference numerals, and the description will be omitted where appropriate.

[0086] Fig. 6 is an enlarged cross-sectional view showing a vehicle underbody structure according to a second modified example, corresponding to Fig. 3. As shown in Fig. 6, in the second modified example of the vehicle underbody structure, a vibration-isolating 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-isolating member 62 is formed into a substantially circular ring shape using, for example, rubber, and is formed to a thickness approximately equal to the gap between the convex bead 41 and the upper case 14. The upper surface of the vibration-isolating member 62 contacts the convex bead 41, and the lower surface of the vibration-isolating member 62 contacts the upper case 14.

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

[0089] (Third Modification) Next, a third modified example of the vehicle underbody structure will be described with reference to Fig. 7. Note that the same components as those in the embodiment will be denoted by the same reference numerals, and the description will be omitted where appropriate.

[0090] Fig. 7 is an enlarged cross-sectional view showing a vehicle underbody structure according to a third modified example, corresponding to Fig. 3. As shown in Fig. 7, in the third modified example of the vehicle underbody structure, a vibration-isolating 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] In this modified example, a bolt 44 serving as a fastener passes through the upper wall portion 30 of the cross member 20. Specifically, a shaft portion 44B of the bolt 44 is formed longer than in the embodiment, and passes through the rear upper wall portion 30B of the cross member 20. A nut 46 is then screwed onto the bolt 44 from above.

[0092] In this modified example, there is no need to form a work hole 30D in the upper wall portion 30 of the cross member 20. Also, it is sufficient to form a hole large enough to insert the shank 44B of the bolt 44, which prevents the rigidity of the cross member 20 from decreasing.

[0093] (Fourth Modification) Next, a fourth modified example of the vehicle underbody structure will be described with reference to Fig. 8. Note that the same components as those in the embodiment will be denoted by the same reference numerals, and the description will be omitted where appropriate.

[0094] Fig. 8 is an enlarged cross-sectional view corresponding to Fig. 2, showing a vehicle underbody structure according to a fourth modified example. As shown in Fig. 8, in the fourth modified example of the vehicle underbody structure, the cross member 20 is detachable from 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 a bolt 64 and a nut 66.

[0096] The left connecting member 28L and the side surface of the battery side frame 26 are mechanically fastened together by bolts 68 and nuts 70. Meanwhile, the left connecting member 28L and the cross member 20 are joined together by spot welding or the like. Although not shown, the right connecting member 28R is also mechanically fastened to the cross member 20 in a similar manner.

[0097] In this modified example, the left connecting member 28L and the right connecting member 28R are each mechanically fastened to the cross member 20, so the cross member 20 can be detached from the battery side frame 26 by removing the bolts 64, 68, etc. Here, the vehicle seat S is attached to the cross member 20, so by detaching the cross member 20, the vehicle seat S can be removed together with the cross member 20. Also, by forming multiple bolt holes in the battery side frame 26 along the fore-and-aft 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 undercarriage structure according to the present invention has been described above, but it goes without saying that it can be embodied in various forms without departing from the spirit and scope of the present invention. For example, in the above-described embodiment and modified example, the fastening portion 40B is formed by including a convex bead 41 extending in the vehicle width direction as shown in FIG. 3, but this is not limited thereto, 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 a plan view. In this case, only the portion where the bolt 44 is attached may have a bulging shape.

[0099] Furthermore, in the above embodiment and modified examples, the bolts 44 are used as fasteners, but this is not limiting. For example, other fasteners that mechanically fasten the components, such as rivets and clips, may also be used.

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

[0101] The following notes are provided regarding the above embodiment.

[0102] (Appendix 1) a battery case disposed under the vehicle and accommodating 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, the bracket including a joint portion joined to an upper surface of the battery case and a fastening portion having an insertion hole formed therein; a fastener that is inserted into the insertion hole and fastens the cross member and the battery case; A vehicle undercarriage having: (Appendix 2) a fastener that is inserted into the insertion hole to fasten the cross member and the battery case; The fastening portion protrudes from the joint portion toward the upper side of the vehicle, 2. The vehicle undercarriage structure according to claim 1, wherein a portion of the fastener is provided in a space between the fastening portion and the upper surface of the battery case. (Appendix 3) The cross member is formed in a closed cross section, 3. The vehicle undercarriage structure according to claim 2, wherein a recess is formed in a lower wall portion of the cross member at a position corresponding to the fastening portion. (Appendix 4) the battery case has side surfaces extending from both ends of the upper surface in the vehicle width direction toward a vehicle lower side, 4. The vehicle underbody structure according to any one of claims 1 to 3, wherein the bracket extends in a vehicle width direction, and an outer side of the bracket in the vehicle width direction is bent along the side surface. (Appendix 5) The battery case includes a flange extending outward in the vehicle width direction from the side surface, 5. The vehicle undercarriage structure of claim 4, wherein the bracket is joined to the flange. (Appendix 6) 6. The vehicle undercarriage structure according to claim 5, wherein a gap is provided between the bracket and the side surface. (Appendix 7) 7. The vehicle underbody structure according to claim 1, wherein the upper surface of the battery case forms a vehicle compartment floor. (Appendix 8) 8. The vehicle underbody structure according to any one of claims 1 to 7, wherein the fastening portion includes a convex bead extending in the vehicle width direction. (Appendix 9) the fastener is a bolt having a head and a shank, the head is disposed in a space between the fastening portion and the upper surface of the battery case, 3. The vehicle undercarriage structure according to claim 2, wherein the shaft portion is inserted through the bracket and the cross member. (Appendix 10) 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 surfaces; 5. The vehicle undercarriage structure according to claim 4, wherein the cross member is connected to the pair of left and right battery side frames. (Appendix 11) 11. The vehicle undercarriage structure 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. (Appendix 12) 12. The vehicle underbody structure according to claim 1, wherein a plurality of the brackets are arranged at intervals in the vehicle longitudinal direction. (Appendix 13) 3. The vehicle undercarriage structure according to claim 2, wherein a vibration-isolating member is disposed in a space between the fastening portion and the upper surface of the battery case. [Explanation of symbols]

[0103] 12 Battery case 12A top 12C side 12D flange 18 Side frame 20 Cross member 26 Battery side frame 32 Lower wall part 32C, 32D recess 40 Bracket 40A joint 40B Fastening section 41 Convex bead 44 Bolts (fasteners) 44A Head 44B Shaft 62 Vibration-proof member 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.

Images