JP2021172175A - Vehicle undercarriage - Google Patents

Abstract

To provide a vehicle substructure capable of inhibiting concentration of a stress at an outer edge of a fastening part between a battery bracket and frame member even when an installed battery unit vibrates vertically.SOLUTION: A fastening position 50 at which a bottom wall 24 of a cross member lower piece 20 is fastened to a body-side lock part 36A of a battery bracket 36 is set to a position deflected to one side from a middle in a width direction 18W when seen from the bottom of a vehicle. A front wall 26 of the cross member lower piece 20 is extended upward in the vehicle from an end closer to the fastening position 50 out of the ends in the width direction 18W of the bottom wall 24. In contrast, a reinforcement member 40 has a first reinforcement part 42 jointly fastened to the battery bracket 36 and the bottom wall 24 of the cross member lower piece 20, and a second reinforcement part 44 bent upward in the vehicle from the front end of the first reinforcement part 42 and disposed along the front wall 26 of the cross member lower piece 20.SELECTED DRAWING: Figure 3

Description

The present invention relates to a vehicle lower structure.

Patent Document 1 below discloses a structure in which a battery module is housed in a battery container and the battery container is attached to a side frame (skeleton member) of a vehicle via a bracket. In this structure, the brackets are overlapped with respect to the side frame and fastened with screws.

Japanese Unexamined Patent Publication No. 2016-103491

By the way, in a vehicle having the above structure, when the battery module vibrates up and down, for example, when traveling on a rough road, a load in the vertical direction acts on the fastening portion between the side frame and the bracket. Here, in the above structure, the configuration of the fastener used for the fastening portion is not clear, but in the fastening portion, for example, when the outer peripheral position of the nut and the outer peripheral position of the washer on the head side of the bolt are aligned. In such cases, there is a concern that stress will be concentrated on the outer edge side of the fastening portion when the battery module vibrates vertically. That is, in such a configuration, when the fastening position of the fastening portion is set to a position closer to one side than the center in the width direction of the side frame, when the battery module vibrates vertically, of the outer edges of the fastening portion. A load to be bent and deformed acts on the portion located on the one side of the width direction.

However, the above-mentioned prior art does not disclose a technique for not concentrating stress on the outer edge side of the fastening portion when the battery module vibrates vertically, and there is room for improvement in this respect.

In consideration of the above facts, the present invention has a vehicle lower structure capable of suppressing stress concentration on the outer edge side of the fastening portion between the battery bracket and the skeleton member even if the mounted battery unit vibrates up and down. The purpose is to obtain.

The vehicle lower structure of the present invention according to claim 1 includes a battery unit mounted on the lower part of the vehicle, a battery bracket having a vehicle body side fixing portion fixed to the battery unit and fixed to the vehicle body side, and a vehicle body. It is provided at the lower part and is formed in a long shape having a longitudinal direction when viewed from the bottom surface of the vehicle. The fastening position of the bottom wall portion set at a position where the fastening position is closer to one side than the center in the width direction orthogonal to the longitudinal direction in the bottom view of the vehicle and both end portions in the width direction of the bottom wall portion. A skeleton member including a vertical wall portion extending from an end closer to the vehicle to the upper side of the vehicle, and a vehicle body-side fixing portion of the battery bracket which is superposed on the upper surface of the bottom wall portion of the skeleton member. A first reinforcing portion that is co-tightened to the bottom wall portion of the skeleton member by the fastener, and a vertical wall portion that is bent upward from the end portion of the first reinforcing portion on the vertical wall portion side to the vertical wall portion. It has a second reinforcing portion arranged along the same, and a reinforcing member including the second reinforcing member.

According to the above configuration, the battery bracket is fixed to the battery unit, and the vehicle body side fixing portion is overlapped with the lower surface of the bottom wall portion of the skeleton member and fastened to the bottom wall portion by a fastener. The bottom wall portion of the skeleton member is set at a position where the fastening position of the battery bracket with the vehicle body side fixing portion is closer to one side than the center in the width direction orthogonal to the longitudinal direction of the skeleton member when viewed from the bottom of the vehicle. Therefore, when the battery unit vibrates up and down, one side of the outer edge of the fastening range at the fastening portion between the bottom wall portion of the skeleton member and the vehicle body side fixing portion of the battery bracket (in other words, the side closer to the vertical wall portion of the skeleton member). ) Is affected by the load that is to be bent and deformed. On the other hand, in the reinforcing member, the first reinforcing portion is overlapped on the upper surface of the bottom wall portion of the skeleton member and is fastened together with the vehicle body side fixing portion of the battery bracket and the bottom wall portion of the skeleton member by fasteners. Includes a portion arranged on one side of the fastening range (in other words, the side closer to the vertical wall portion of the skeleton member). Therefore, when the above-mentioned load to be bent and deformed is applied, this load can be dispersed by the reinforcing member.

Further, the vertical wall portion of the skeleton member extends from the end portion of the bottom wall portion in the width direction closer to the fastening position to the upper side of the vehicle, and the second reinforcing portion of the reinforcing member is the second reinforcing portion. It is bent from the end of the reinforcing portion on the vertical wall side to the upper side of the vehicle and arranged along the vertical wall portion of the skeleton member. Therefore, when the battery unit bends and deforms to the lower side of the vehicle and a downward load is applied to the skeleton member via the battery bracket, the bottom wall portion of the skeleton member and the first reinforcing portion of the reinforcing member are on the vertical wall side. The end portion is tilted so as to be lower than the end portion on the opposite side, and the second reinforcing portion of the reinforcing member and the vertical wall portion of the skeleton member come into contact with each other to receive a load. As a result, the load acting on the fastening portion between the battery bracket and the skeleton member is distributed.

As described above, according to the vehicle lower structure of the present invention, even if the mounted battery unit vibrates up and down, stress is suppressed from being concentrated on the outer edge side of the fastening portion between the battery bracket and the skeleton member. Can be done.

It is a perspective view which shows the vehicle lower structure which concerns on one Embodiment of this invention in the state which was seen from the diagonally lower side of the vehicle. FIG. 1 (A) shows a state in which the battery unit is not deformed, and FIG. 1 (B) shows a state in which the battery unit is bent and deformed toward the lower side of the vehicle when traveling on a rough road. It is a perspective view which shows the cross member of FIG. 1A and the peripheral part thereof enlarged in the state before mounting the battery unit. It is an enlarged vertical cross-sectional view which shows the state of cutting along the 3-3 line of FIG. 1 (A) (the same cutting position as the 3L-3L line of FIG. 2).

The vehicle lower structure according to the embodiment of the present invention will be described with reference to FIGS. 1 to 3. In these figures, the arrow FR appropriately shown indicates the front side of the vehicle, the arrow UP indicates the upper side of the vehicle, and the arrow W indicates the width direction of the vehicle.

First, a schematic configuration of the vehicle lower structure according to the present embodiment will be described. FIG. 1 is a perspective view of the vehicle lower structure according to the present embodiment as viewed from an obliquely downward side of the vehicle. The battery unit 30 is mounted on the lower portion 10 of the vehicle, FIG. 1 (A) shows a state in which the battery unit 30 is not deformed, and FIG. 1 (B) shows the battery unit 30 in the vehicle when traveling on a rough road. It shows a state of bending and deforming downward. The battery unit 30 is a unit in which a battery (not shown) is housed in a battery case 30A.

As shown in FIG. 1A, rockers 12 are arranged on both sides of the lower portion 10A of the vehicle body in the vehicle width direction. The rocker 12 extends along the front-rear direction of the vehicle. The locker 12 is joined to the outer end portion of the floor panel 14 constituting the floor portion of the vehicle interior in the vehicle width direction. The floor panel 14 includes a front floor panel 14A, a center floor panel 14B, and a rear floor panel (not shown). The front floor panel 14A constitutes a portion of the floor panel 14 on the vehicle front side, and the center floor panel 14B is provided on the vehicle rear side of the front floor panel 14A and is arranged on the vehicle lower side of a rear seat (not shown). (Not shown) is provided on the rear side of the vehicle of the center floor panel 14B.

A floor side member 16 is arranged on the lower surface of the floor panel 14 at a portion outside in the vehicle width direction. The floor side member 16 extends along the front-rear direction of the vehicle. The rear portions of the pair of left and right floor side members 16 are connected in the vehicle width direction by a cross member 18 as a skeleton member. The cross member 18 is formed in a long shape having a longitudinal direction when viewed from the bottom of the vehicle.

On the other hand, the front portion of the battery unit 30 and the front portion of the floor side member 16 as an example are connected by a bracket 32. Further, a part of the rear portion of the battery unit 30 and a patch 33 fixed to the front floor panel 14A as an example (see FIG. 1B) are connected by a bracket 34. Further, the rear portion of the battery unit 30 and the cross member 18 are connected by a battery bracket 36. The battery bracket 36 includes a vehicle body side fixing portion 36A that is fixed to the battery unit 30 and is fixed to the vehicle body side. Further, a bolt insertion hole 36H (see FIG. 3) is formed through the vehicle body side fixing portion 36A of the battery bracket 36.

Next, the configuration of the cross member 18 and its peripheral portion will be described.

FIG. 2 is an enlarged perspective view of the cross member 18 and its peripheral portion in a state before mounting the battery unit 30 (see FIG. 1 (A)). FIG. 3 shows an enlarged vertical cross-sectional view of a state of being cut along the 3-3 line of FIG. 1 (A) (the same cutting position as the 3L-3L line of FIG. 2).

As shown in FIG. 3, the cross member 18 includes a cross member upper 19 and a cross member lower 20. The cross member upper 19 includes an upper wall portion 19C forming an intermediate portion in the front-rear direction of the vehicle, a front flange portion 19A forming a front end portion of the cross member upper 19 and arranged at a position lower than the upper wall portion 19C. It includes a rear flange portion 19E that constitutes the rear end portion of the cross member upper 19 and is arranged at a position lower than the upper wall portion 19C and higher than the front flange portion 19A. The rear end portion of the front flange portion 19A and the front end portion of the upper wall portion 19C are connected to each other by the front wall portion 19B in the substantially vertical direction of the vehicle. The front end portion of the rear flange portion 19E and the rear end portion of the upper wall portion 19C are connected to each other by the rear wall portion 19D in the substantially vertical direction of the vehicle.

On the other hand, the cross member lower 20 is formed in a shape in which the cross member upper 19 is rotated by 180 ° in a cross-sectional view on the vehicle side. The cross member lower 20 includes a front flange portion 22A that is overlapped with the front flange portion 19A of the cross member upper 19 from the lower side of the vehicle and joined by spot welding. The rear end portion of the front floor panel 14A is joined to the lower surface side of the front flange portion 22A by spot welding. Further, the cross member lower 20 has a rear flange portion 22B which is overlapped with respect to the rear flange portion 19E of the cross member upper 19 with the front end portion of the center floor panel 14B sandwiched from the lower side of the vehicle and joined by spot welding. I have. By joining the cross member lower 20 and the cross member upper 19 as described above, a closed cross-sectional structure extending in the vehicle width direction is formed.

The cross member lower 20 is provided with a bottom wall portion 24 on the rear lower side of the front flange portion 22A and on the front lower side of the rear flange portion 22B. A bolt insertion hole 24H is formed through the bottom wall portion 24. The vehicle body side fixing portion 36A of the battery bracket 36 is overlapped on the lower surface of the bottom wall portion 24, and is arranged so that the bolt insertion hole 36H of the battery bracket 36 overlaps the bolt insertion hole 24H of the cross member lower 20. .. The shaft portion 38A1 of the bolt 38A as a fastener is inserted into the bolt insertion holes 36H and 24H from the lower side of the vehicle, and the shaft portion 38A1 of the bolt 38A is screwed into a weld nut 38B as a fastener described later. ..

That is, the vehicle body side fixing portion 36A of the battery bracket 36 is overlapped from the lower surface side and fastened to the bottom wall portion 24 of the cross member lower 20 by fasteners (bolts 38A and weld nuts 38B). The bottom wall portion 24 of the cross member lower 20 has a fastening position 50 of the battery bracket 36 with the vehicle body side fixing portion 36A more than the center in the width direction 18W (width direction orthogonal to the longitudinal direction of the cross member 18) when viewed from the bottom of the vehicle. It is set at a position closer to one side (left side in FIG. 3).

The front end portion of the bottom wall portion 24 and the rear end portion of the front flange portion 22A are substantially connected in the vertical direction of the vehicle by the front wall portion 26 as a vertical wall portion. The front wall portion 26 extends upward from the end of the bottom wall portion 24 on the side closer to the fastening position 50 among both ends of 18 W in the width direction, and is slightly toward the front side of the vehicle toward the upper side of the vehicle. It is tilted. Further, the rear end portion of the bottom wall portion 24 and the front end portion of the rear flange portion 22B are connected to each other by the rear wall portion 28 in the substantially vertical direction of the vehicle. The rear wall portion 28 extends upward from the end of the bottom wall portion 24 on the side far from the fastening position 50 among both ends of 18 W in the width direction, and is slightly toward the rear side of the vehicle toward the upper side of the vehicle. It is tilted.

As shown in FIG. 2, the cross member lower 20 is configured by joining a plurality of panels 20A and 20B arranged in the vehicle width direction as an example.

As shown in FIGS. 2 and 3, a reinforcement 40 as a reinforcing member is arranged inside the cross member 18. The reinforce 40 is arranged with the vehicle width direction as the longitudinal direction, and as an example, one reinforce 40 is provided symmetrically on the left side of the vehicle and one on the right side of the vehicle.

As shown in FIG. 3, the reinforce 40 includes a first reinforcing portion 42 superimposed on the upper surface of the bottom wall portion 24 of the cross member lower 20. A bolt insertion hole 42H is formed through the first reinforcing portion 42 of the reinforcement 40 at a position corresponding to the bolt insertion hole 24H of the bottom wall portion 24 of the cross member lower 20. Further, a weld nut 38B is previously fixed to the outer peripheral portion of the bolt insertion hole 42H on the upper surface of the first reinforcing portion 42 of the reinforce 40.

The shaft portion 38A1 of the bolt 38A screwed into the weld nut 38B has a through hole (not shown) of the washer 38C and bolt insertion holes 36H, 24H, 42H of the battery bracket 36, the cross member lower 20 and the reinforcement 40. It penetrates from the lower side of the vehicle. Further, the head 38A2 of the bolt 38A is seated on the washer 38C, and the washer 38C is seated on the vehicle body side fixing portion 36A of the battery bracket 36. That is, the first reinforcing portion 42 of the reinforcement 40 is fastened together with the vehicle body side fixing portion 36A of the battery bracket 36 and the bottom wall portion 24 of the cross member lower 20 by bolts 38A and weld nuts 38B. In the present embodiment, the outer diameter of the washer 38C is set to be larger than the outer diameter of the weld nut 38B.

Further, the reinforce 40 includes a second reinforcing portion 44 that is bent and extends upward from the front end portion (the end portion on the front wall portion 26 side) of the first reinforcing portion 42 to the upper side of the vehicle. The second reinforcing portion 44 is arranged along the front wall portion 26 of the cross member lower 20 (more specifically, superimposed on the front wall portion 26). Further, the reinforce 40 includes a third reinforcing portion 46 that is bent and extends upward from the rear end portion (the end portion on the rear wall portion 28 side) of the first reinforcing portion 42 to the upper side of the vehicle. The third reinforcing portion 46 is arranged along the lower part of the rear wall portion 28 of the cross member lower 20. The amount of extension of the second reinforcing portion 44 from the front end portion of the first reinforcing portion 42 and the amount of extension of the third reinforcing portion 46 from the rear end portion of the first reinforcing portion 42 can be appropriately set.

Next, the operation and effect of this embodiment will be described.

In the present embodiment, when the battery unit 30 (see FIG. 1B) vibrates vertically, the outer edge of the fastening range is at the fastening portion between the bottom wall portion 24 of the cross member lower 20 and the vehicle body side fixing portion 36A of the battery bracket 36. A load that tries to break and deform acts on the part located on the front side of the vehicle. On the other hand, in the reinforce 40, the first reinforcing portion 42 is superposed on the upper surface of the bottom wall portion 24 of the cross member lower 20, and is fastened together with the vehicle body side fixing portion 36A of the battery bracket 36 and the bottom wall portion 24 of the cross member lower 20. The reinforce 40 includes a portion arranged on the front side of the vehicle with respect to the fastening range. Therefore, when the above-mentioned load to be bent and deformed acts, the load can be dispersed by the reinforce 40.

Further, the front wall portion 26 of the cross member lower 20 extends upward from the end of the bottom wall portion 24 on the side closer to the fastening position 50 among both ends of 18 W in the width direction, and is the second of the reinforce 40. The two reinforcing portions 44 are bent upward from the front end portion (the end portion of the cross member lower 20 on the front wall portion 26 side) of the first reinforcing portion 42 and arranged along the front wall portion 26 of the cross member lower 20. Has been done. Therefore, when the battery unit 30 (see FIG. 1B) bends and deforms downward of the vehicle and a downward load is applied to the cross member lower 20 via the battery bracket 36, the bottom wall portion 24 of the cross member lower 20 The first reinforcing portion 42 of the reinforce 40 is tilted so that the front end side (left side in the figure) is lower than the rear end side (right side in the figure), and the second reinforcing portion 44 of the reinforce 40 and the front wall of the cross member lower 20. It comes into contact with the portion 26 and receives a load. As a result, the load acting on the fastening portion between the battery bracket 36 and the cross member 18 is distributed.

As described above, according to the vehicle lower structure of the present embodiment, the battery bracket 36 and the cross member are cross-membered even if the mounted battery unit 30 (see FIGS. 1A and 1B) vibrates up and down. It is possible to suppress the concentration of stress on the outer edge side of the fastening portion with 18.

Although an example of the present invention has been described above, the present invention is not limited to the above, and it goes without saying that the present invention can be variously modified and implemented within a range not deviating from the gist thereof. .. For example, the "skeleton member" according to claim 1 may be a skeleton member other than the cross member 18, such as a floor side member (16 (see FIG. 1A)).

10 Lower part of vehicle 10A Lower part of vehicle body 18 Cross member (skeleton member)
18W width direction 24 bottom wall part 26 front wall part (vertical wall part)
30 Battery unit 36 Battery bracket 36A Body side fixing part 38A Bolt (fastener)
38B Weld nut (fastener)
40 Reinforce (reinforcing member)
42 1st reinforcement 44 2nd reinforcement 50 Fastening position

Claims (1)

The battery unit mounted on the bottom of the vehicle and
A battery bracket having a vehicle body side fixing portion fixed to the vehicle body side as well as being fixed to the battery unit,
It is provided in the lower part of the vehicle body and is formed in a long shape having a longitudinal direction when viewed from the bottom surface of the vehicle. The fastening position is set to a position closer to one side than the center in the width direction orthogonal to the longitudinal direction in the bottom view of the vehicle, and the fastening of both ends in the width direction of the bottom wall portion. A skeletal member comprising a vertical wall portion extending from an end closer to the position to the upper side of the vehicle.
A first reinforcing portion that is overlapped on the upper surface of the bottom wall portion of the skeleton member and fastened together with the vehicle body side fixing portion of the battery bracket and the bottom wall portion of the skeleton member by the fastener, and the first reinforcing portion. A reinforcing member including a second reinforcing portion bent upward from the vertical wall portion side of the reinforcing portion and arranged along the vertical wall portion.
Vehicle undercarriage with.

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