Vehicle underbody structure

Abstract

This vehicle body substructure comprises: a main frame; and a sub frame that is disposed adjacent, in the vehicle longitudinal direction, to a battery pack disposed below the main frame. The sub frame has a member that supports a power source, and a support bracket that connects the member and the main frame. The support bracket is formed in a substantially L shape including a vertical extension part, a longitudinal extension part, and a bent part. The longitudinal extension part extends in the vehicle longitudinal direction from the bent part toward the battery pack side, and is coupled to the main frame at a position separated from the bent part.

Description

Technical Field

[0001] This disclosure relates to a vehicle underbody structure.

Background Art

[0002] Conventionally, a vehicle structure in which a subframe is provided on a main frame is known (see, for example, Patent Document 1). Such a subframe supports a power plant (power source) such as an engine.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, electric vehicles or hybrid vehicles equipped with a motor to reduce carbon dioxide are becoming mainstream. Also, in recent years, in order to increase the running time by the motor, the battery pack that houses the battery that supplies power to the motor is becoming larger. For this reason, the gap between the battery pack and the power plant is becoming smaller.

[0005] An object of this disclosure is to provide a vehicle underbody structure that can suppress interference between the battery pack and the power source during a collision.

Means for Solving the Problems

[0006] The vehicle body understructure according to this disclosure comprises a main frame forming the skeleton of the vehicle, a battery pack disposed below the main frame, and a subframe disposed below the main frame adjacent to the battery pack in the vehicle longitudinal direction and supporting the vehicle's power source, wherein the subframe has a member that supports the power source and a support bracket at the end of the member on the battery pack side in the vehicle longitudinal direction that connects the member and the main frame, wherein the support bracket is formed in a substantially L-shape including an upper and lower extension portion whose lower end is connected to the member and extends in the vertical direction, a front and rear extension portion that extends along the main frame in the vehicle longitudinal direction and is connected to the main frame, and a curved portion that connects the upper end of the upper and lower extension portion to the end of the front and rear extension portion and curves from the upper and lower extension portion toward the front and rear extension portion, wherein the front and rear extension portion extends in the vehicle longitudinal direction toward the battery pack side from the curved portion and is connected to the main frame at a position spaced apart from the curved portion.

[0007] With this underbody structure, when the vehicle collides, the support bracket bends and the power source moves downward. This suppresses interference between the battery pack and the power source during a collision. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a vehicle underbody structure that can suppress interference between the battery pack and the power source during a collision. [Brief explanation of the drawing]

[0009] [Figure 1] A side view of the underbody structure of a vehicle according to one embodiment of the present disclosure. [Figure 2] A top view of the underbody structure of a vehicle according to one embodiment of the present disclosure. [Figure 3] A perspective view of a subframe according to one embodiment of the present disclosure. [Figure 4] A side view of a support bracket according to one embodiment of the present disclosure. [Figure 5] A side view of a mounting bracket according to one embodiment of the present disclosure. [Figure 6] A diagram showing the state during a vehicle collision according to one embodiment of the present disclosure. [Modes for carrying out the invention]

[0010] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the following specification and drawings, the right side of vehicle C in the direction of travel will be denoted as R, the left side as L, the front side as F, the rear side as B, the upper side as U, and the lower side as D.

[0011] As shown in Figures 1 and 2, the vehicle body understructure 1 comprises a main frame 2, a battery pack 4, and a subframe 6. The vehicle body understructure 1 in this embodiment is a vehicle front structure for positioning the power source 8 in front of the vehicle C. In this embodiment, the power source 8 is a motor that receives power from a battery housed in the battery pack 4.

[0012] The main frame 2 comprises a pair of side members 10 and a cross member 11, and constitutes the main body frame. The pair of side members 10 extend in the longitudinal direction of the vehicle and are spaced apart in the lateral direction of the vehicle. The cross member 11 extends in the lateral direction (vehicle width direction) and connects the pair of side members 10. As shown in Figure 1, the cross member 11 is positioned between the subframe 6 and the battery pack 4 in the longitudinal direction of the vehicle. The cross member 11 also has a first inclined surface 11a that slopes downward from the front F to the rear B.

[0013] The battery pack 4 is a case for housing a secondary battery such as a lithium-ion battery. The battery pack 4 is fixed to the side member 10 of the main frame 2.

[0014] As shown in Figure 2, the subframe 6 includes a member 20 that supports the power source 8, a pair of support brackets 21 that connect the member 20 to the main frame 2, and two mounting brackets 22 that connect the power source 8 to the member 20. The subframe 6 pivotably supports the front suspension arm 23 together with the power source 8. As shown in Figure 1, the subframe 6 is positioned below the main frame 2, adjacent to the battery pack 4 in the vehicle's longitudinal direction. The support brackets 21 are located at the end of the member 20 on the battery pack 4 side in the vehicle's longitudinal direction.

[0015] As shown in Figures 2 and 3, the member 20 is a structural member configured in a grid pattern. As shown in Figure 3, in this embodiment, the member 20 includes a pair of first members 20a extending in the front-rear direction, a second member 20b connecting the front F of the pair of first members 20a, and a third member 20c connecting the rear B of the pair of first members 20a.

[0016] The first member 20a is provided with front brackets 20h at both the left and right ends. Approximately in the left-right direction of the first member 20a, there is a through hole 20d through which a front mount bracket 24 (see Figures 1 and 2) that supports the front of the power source 8 is inserted. In this embodiment, the first member 20a is a cylindrical metal member with a rectangular cross-section.

[0017] Each of the pair of second members 20b is provided with a front arm carrier 20e that supports the front side F of the front suspension arm 23 (see Figure 2). In this embodiment, the second members 20b are cylindrical metal members.

[0018] The third member 20c is provided with rear arm carriers 20f that support the rear sides B of the front suspension arms 23 at both left and right ends. A support bracket 21 on the left side L is fixed to the left end of the left rear arm carrier 20f, and a support bracket 21 on the right side R is fixed to the right end of the right rear arm carrier 20f. On the upper part of the third member 20c, a pair of mount bracket stays 20g for fixing the mount bracket 22 are provided. In this embodiment, the third member 20c is formed by welding sheet metal members that constitute the rear arm carrier 20f and the mount bracket stays 20g to a metal member with a rectangular cross-section.

[0019] As shown in FIGS. 1 and 2, the rear side B of the sub-frame 6 is fixed to the side member 10 by the support bracket 21. The front side F of the sub-frame 6 is fixed via the front bracket 20h.

[0020] As shown in FIG. 4, the support bracket 21 includes a vertically extending portion 21a extending in the vertical direction, a longitudinally extending portion 21b extending in the vehicle longitudinal direction along the main frame 2 (see FIG. 1), a curved portion 21c connecting the vertically extending portion 21a and the longitudinally extending portion 21b and bending from the vertically extending portion 21a toward the longitudinally extending portion 21b. That is, the support bracket 21 is formed in a substantially L shape. The lower end of the vertically extending portion 21a is connected to the member 20. More specifically, the vertically extending portion 21a is welded and fixed to the third member 20c. The longitudinally extending portion 21b extends in the vehicle longitudinal direction from the curved portion 21c toward the battery pack 4 side and is connected to the main frame 2 at a position spaced apart from the curved portion 21c. More specifically, the longitudinally extending portion 21b includes a bolt hole 21e through which a bolt for fastening to the side member 10 is inserted and is connected to the main frame 2 by bolts.

[0021] The support bracket 21 has a deformation allowance portion that is formed to deform earlier than other portions when a load acts in the vehicle longitudinal direction on the sub-frame 6 at a portion in front of the connecting portion (the portion near the bolt hole 21e in this embodiment) that is connected to the main frame 2 of the front and rear extending portion 21b. In this embodiment, the thickness h1 of the front and rear extending portion 21b is formed thinner than the thickness h2 of the up and down extending portion 21a, so that the portion in front of the connecting portion is formed to be more easily bent than the up and down extending portion 21a. As a result, the portion in front of the connecting portion of the front and rear extending portion 21b functions as a deformation allowance portion.

[0022] The support bracket 21 is configured by combining a first member 21f having a U-shaped cross-section that opens toward one side in the vehicle longitudinal direction and a second member 21g having a U-shaped cross-section that opens toward the other side in the vehicle longitudinal direction, and the opening of the first member 21f and the opening of the second member 21g are combined in a state where they face each other. In this embodiment, the support bracket 21 has a monaka structure having a first member 21f with a U-shaped cross-section that opens toward the rear side B and a second member 21g with a U-shaped cross-section that opens toward the front side. The support bracket 21 can easily adjust the strength of the curved portion 21c by adjusting the hardness of the first member 21f and the second member 21g. However, the support bracket 21 may be constituted by only the first member 21f.

[0023] In this embodiment, the curved portion 21c includes a through hole 21d. The through hole 21d penetrates in the left-right direction of the curved portion 21c of the first member 21f. The rear side B of the through hole 21d is open.

[0024] As shown in Figure 2, the mount bracket 22 elastically supports the power source 8 to the member 20 on the rear side of the subframe 6. In this embodiment, one mount bracket 22 is arranged on each side, supporting the left and right sides of the power source 8. As shown in Figure 5, the mount bracket 22 has a mount 22a, a second inclined surface (an example of an inclined surface) 22b, and a plurality of bolt holes 22c. The mount bracket 22 is a bracket for fixing the power source 8 to the mount bracket stay 20g. The mount 22a includes a vibration-damping member 22f made of rubber or resin and bolt holes 22e, and is bolted to the mount bracket stay 20g. The power source 8 is fixed to the mount bracket 22 by bolts inserted through the bolt holes 22c. In this embodiment, there are three bolt holes 22c: upper U, lower D, and front F.

[0025] The second inclined surface 22b is positioned opposite the battery pack 4 in the vehicle's longitudinal direction and slopes downward as it approaches the rear B. As shown in Figure 1, the second inclined surface 22b of the mount bracket 22 is positioned opposite the first inclined surface 11a of the cross member 11.

[0026] As shown in Figure 6(a), when an object X enters the vehicle body understructure 1 configured in this way from the front, the side members 10 collapse and the subframe 6 retracts. When the subframe 6 retracts, the second inclined surface 22b of the mount bracket 22 comes into contact with the first inclined surface 11a of the cross member 11. This guides the mount bracket 22 downward D.

[0027] As shown in Figure 6(b), when the impacting object X further penetrates the rear side B, the subframe 6 retracts, and the lower end of the vertically extended portion 21a of the support bracket 21 is pushed towards the rear side B. When the vertically extended portion 21a is pushed towards the rear side B, the front and rear extended portion 21b of the support bracket 21 bends downward D at the deformation allowable portion. Specifically, the front and rear extended portion 21b bends downward D with the point just before the connecting portion that connects to the main frame 2 as the pivot point. When the support bracket 21 bends, the vertically extended portion 21a lowers. As a result, the load due to the collision is absorbed, and the rear side B of the subframe 6 lowers to the downward D, and the mount bracket 22 and power source 8 also move downward to the downward D. As a result, the mount bracket 22 and power source 8 tuck under the battery pack 4. Therefore, during a collision, the collision load is absorbed while interference between the battery pack 4 and power source 8 is suppressed.

[0028] As shown in Figure 6(c), when the impacting object X further penetrates the rear side B, the upper and lower extensions 21a bend counterclockwise with the through hole 21d as a fulcrum. This suppresses the load acting on the joint between the front and rear extensions 21b and the main frame 2, thereby preventing the subframe 6 from falling off.

[0029] As explained above, this disclosure provides a vehicle body understructure 1 that can absorb collision loads during a collision while suppressing interference between the battery pack 4 and the power source 8.

[0030] <Other Embodiments> Although embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. In particular, the various modifications described herein can be combined as needed.

[0031] (a) In the above embodiments, the subframe 6 was described as having a structure having a first member 20a, a second member 20b, and a third member 20c, but the disclosure is not limited thereto. The structure of the subframe 6 may be any structure to which the support bracket 21 and the mounting bracket 22 can be fixed.

[0032] (b) In the above embodiments, the power source 8 was described using a motor as an example, but the disclosure is not limited thereto. The power source 8 may be, for example, a combination of a motor and an internal combustion engine, or a fuel cell stack, etc.

[0033] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to these examples. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. Furthermore, the components of the above embodiments may be combined in any way without departing from the spirit of the invention.

[0034] This application is based on a Japanese patent application (Patent Application No. 2023-56908) filed on March 31, 2023, the contents of which are incorporated herein by reference. [Explanation of symbols]

[0035] 1: Underbody structure 2: Mainframe 4: Battery pack 6: Subframe 8:Power source 11a: 1st slope 20: Members 20a: First Member 20b: Second Member 20c: Third Member 21: Support bracket 21a: Vertical extension part 21b: Front and rear extension part 21c: Curved part 21d: Through hole 21f: First member 21g: Second component 22: Mounting bracket C: Vehicle

Claims

1. The main frame that forms the structure of the vehicle, A battery pack located below the main frame, The vehicle comprises a subframe positioned below the main frame, adjacent to the battery pack in the vehicle's longitudinal direction, and supporting the vehicle's power source, The subframe includes a member that supports the power source, and a support bracket that connects the member and the main frame to the battery pack end of the member in the vehicle's longitudinal direction. The support bracket is formed in a substantially L-shape, including a vertically extending portion whose lower end is connected to the member and extends vertically, a front-rear extending portion that extends along the main frame in the vehicle's front-rear direction and is connected to the main frame, and a curved portion that connects the upper end of the vertically extending portion to the end of the front-rear extending portion and curves from the vertically extending portion toward the front-rear extending portion. The aforementioned front and rear extensions extend in the vehicle's front-rear direction from the curved portion toward the battery pack, and are connected to the main frame at a position spaced apart from the curved portion. Underbody structure of the vehicle.

2. The support bracket has a deformation-tolerant portion in the portion forward of the connecting portion that connects the front and rear extensions to the main frame, which deforms before other portions when a load is applied to the subframe in the front-rear direction of the vehicle. The underbody structure of a vehicle according to claim 1.

3. The curved portion has a through hole that penetrates the vehicle in the left-right direction, The through hole includes an opening that opens toward the rear of the vehicle. The underbody structure of a vehicle according to claim 1.

4. The support bracket is constructed by combining a first member with a U-shaped cross-section that opens toward one side in the vehicle's longitudinal direction, and a second member with a U-shaped cross-section that opens toward the other side in the vehicle's longitudinal direction. The opening of the first member and the opening of the second member are combined with their openings facing each other. The underbody structure of a vehicle according to claim 1.

5. The rear side of the subframe has a mounting bracket that elastically supports the power source to the member, The mounting bracket is positioned opposite the battery pack in the vehicle's front-rear direction and has an inclined surface that slopes downward toward the battery pack. The underbody structure of a vehicle according to any one of claims 1 to 4.

6. The vehicle further comprises a cross member positioned between the subframe and the battery pack, extending in the vehicle width direction, When the subframe moves in the longitudinal direction of the vehicle, the inclined surface comes into contact with the cross member. The underbody structure of a vehicle according to claim 5.

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