Cross member structure

Abstract

A cross member structure according to the present disclosure is a structure of a cross member (4) attached to the front ends of a pair of side members (2) extending in a vehicle front-rear direction. This structure comprises a first cross member (4) having a substantially trapezoidal closed cross-sectional structure in which two corners (A, B) positioned at the front side are formed at an acute angle and two corners (C, D) positioned at the rear side are formed at an obtuse angle. Thus, the front corners (A, B) of the substantially trapezoidal closed cross-section are acute and the rear corners (C, D) thereof are obtuse, whereby load transmission can be improved using a simple structure.

Description

[Technical field]

[0001] This case relates to a cross member structure attached to the front end of a side member of a vehicle. [Background technology]

[0002] Conventionally, a vehicle body structure is known in which a cross member is provided at the front end of a vehicle's side members. This type of cross member is called, for example, a first cross member, or also a front-end cross member or a bumper beam. The first cross member has the function of transmitting the load during a collision to the side members, and also has the function of increasing the rigidity of the frame. It has also been proposed to improve the shock-absorbing performance by attaching an energy absorbing member or a shock-absorbing material to the front side of the first cross member (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-078563 A Summary of the Invention [Problem to be solved by the invention]

[0004] The cross-sectional shape of the first cross member described in Patent Document 1 is a vertically elongated rectangular closed cross-sectional shape. On the other hand, the vertical dimension of the side member connected to the rear of the first cross member is often smaller than the vertical dimension of the first cross member. This poses a problem in that it is difficult to improve the load transferability from the first cross member to the side member during a collision. In particular, the more the vertical dimension of the first cross member is extended in order to increase the pressure receiving area of ​​the collision load, the larger the step between the first cross member and the side member becomes, which may reduce the load transferability.

[0005] One of the objectives of the present invention, which was devised in light of the above-mentioned problems, is to provide a cross member structure that can improve load transmission with a simple configuration. However, in addition to this objective, another objective of the present invention is to achieve effects that cannot be obtained with conventional techniques, which are derived from the respective configurations shown in the "Description of the Preferred Embodiments" described later. [Means for solving the problem]

[0006] The disclosed cross member structure can be realized in the aspects or applications disclosed below, and solves at least some of the above problems. The disclosed cross member structure is a cross member structure that is attached to the front ends of a pair of side members extending in the fore-and-aft direction of the vehicle, and includes a first cross member having an approximately trapezoidal closed cross-sectional structure in which two corners located at the front are formed as acute angles and two corners located at the rear are formed as obtuse angles. Effect of the Invention

[0007] The disclosed cross member structure enables improved load transmission with a simple configuration. [Brief description of the drawings]

[0008] [Figure 1] A cross-sectional view of a first cross member to which the cross member structure is applied. [Diagram 2] FIG. [Diagram 3] (A) is a top view of the first cross member, (B) is its front view, (C) is its left side view, and (D) is its rear view. [Figure 4] FIG. 4 is a perspective view of a bracket attached to a first cross member. [Diagram 5] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An embodiment to which the disclosed cross member structure is applied will be described below. EXAMPLES

[0010] [1. Configuration] Fig. 1 is a cross-sectional view of a first cross member 4 to which a cross member structure as an embodiment is applied, and Fig. 2 is a perspective view of the first cross member 4. Fig. 3(A) is a top view of the first cross member, Fig. 3(B) is a front view thereof, Fig. 3(C) is a left side view thereof, and Fig. 3(D) is a rear view thereof. Fig. 4 is a perspective view of a bracket 7 attached to the first cross member 4. Fig. 5 is a side view of the first cross member 4.

[0011] The first cross member 4 is provided at the front end of the frame 1 of the vehicle and attached to the front end of the side member 2. The frame 1 here includes not only the first cross member 4 but also the side member 2 and a suspension cross member and a floor cross member (not shown). The side members 2 extend in the front-to-rear direction of the vehicle and are provided in pair on the left and right with a gap in the vehicle width direction. Of the cross members connecting the left and right side members 2 in the vehicle width direction, the first cross member 4 is the cross member located furthest forward of the vehicle.

[0012] An end plate 3 having an insertion hole for a fastener 8 is fixed to the front end of each side member 2. The end plate 3 is a plate-like member fixed so as to close the front end of the side member 2, and is formed in a rectangular shape that is slightly larger than the cross-sectional outline of the side member 2. The first cross member 4 is fastened and fixed to the side member 2 via the end plate 3 and the fastener 8. An energy absorbing member or cushioning material (e.g., foamed PP material) (not shown) may be attached to the front side of the first cross member 4.

[0013] The first cross member 4 has a substantially trapezoidal closed cross-sectional structure. As shown in FIG. 1, in the cross-section when the first cross member 4 is cut so as to be divided in the vehicle width direction, the upper base (the shorter of the two parallel sides) is arranged at the rear of the vehicle, and the lower base (the longer of the two parallel sides) is arranged at the front of the vehicle. In the example shown in FIG. 1, each of the upper base and the lower base is substantially vertical (the direction of the normal line is substantially horizontal).

[0014] The first cross member 4 is formed by combining a first plate member 5 and a second plate member 6. The first plate member 5 is a member arranged on the front side of the first cross member 4. As shown in FIG. 1, the first plate member 5 has a substantially L-shaped cross-section. On the other hand, the second plate member 6 is a member arranged on the rear side of the first cross member 4 and is joined to the rear side of the first plate member 5. As shown in FIG. 1, the second plate member 6 has a substantially U-shaped cross-section. Each of the first plate member 5 and the second plate member 6 is manufactured by, for example, performing press working (bending working) on a steel plate. Preferably, the second plate member 6 is formed of a steel plate having a plate thickness thicker than that of the first plate member 5.

[0015] The first plate member 5 is provided with a front surface 11 and a first upper surface 12. The front surface 11 is a planar portion where the normal line (the normal line extending toward the outside of the first cross member 4 in the cross-section shown in FIG. 1) faces the front of the vehicle. The first upper surface 12 is a surface connected to the upper end side of the front surface 11, and is a planar portion where the normal line is inclined slightly rearward of the vehicle from the vertically upward direction, and is a portion forming a downward slope toward the rear of the vehicle. In the cross-section shown in FIG. 1, the angle A formed between the front surface 11 and the first upper surface 12 is formed as an acute angle (an angle less than 90 degrees).

[0016] The dimension F in the vehicle front-rear direction of the first upper surface 12 is set to be shorter than the dimension E in the vehicle front-rear direction of the first cross member 4. Preferably, the dimension F is set to be shorter than half of the dimension E (that is, F < E / 2). By setting the dimension F relatively short in this way, for example, when an external force acts from the front surface 11 of the first cross member 4 toward the rear of the vehicle, buckling of the first upper surface 12 can be suppressed.

[0017] Furthermore, when the second plate member 6 has a thickness greater than that of the first plate member 5, the first cross member 4 deforms in stages in response to an external force from the front surface 11 toward the rear of the vehicle. That is, upon receiving the external force, the first plate member 5 first deforms so as to be compressed in the fore-and-aft direction of the vehicle, and then the second plate member 6 is compressed in the fore-and-aft direction of the vehicle while transmitting the external force to the side member 2. This makes it easier for the external force input to the front surface 11 to be transmitted to the side member 2, improving load transmission.

[0018] The second plate member 6 is provided with a second upper surface 17, a rear surface 18, and a lower surface 19. The second upper surface 17, like the first upper surface 12, is a planar portion whose normal is slightly inclined toward the rear of the vehicle rather than vertically upward, and forms a downward gradient toward the rear of the vehicle. The second upper surface 17 is disposed parallel to the first upper surface 12. As shown in FIG. 1, the first upper surface 12 and the second upper surface 17 are joined by overlapping them. Examples of joining methods include lap welding and spot welding. The rear surface 18 is a surface connected to the rear end side of the second upper surface 17, and is a planar portion whose normal faces the rear of the vehicle. In the cross section shown in FIG. 1, the angle C between the second upper surface 17 and the rear surface 18 is formed as an obtuse angle (an angle exceeding 90 degrees). The sum of the angle A and the angle C is approximately 180 degrees.

[0019] The lower surface 19 is a surface connected to the lower end edge of the rear surface 18, and is a planar portion whose normal is slightly inclined toward the rear of the vehicle rather than vertically downward, forming a downward slope toward the front of the vehicle. In the cross section shown in FIG. 1, an angle D between the rear surface 18 and the lower surface 19 is formed as an obtuse angle (an angle exceeding 90 degrees). As shown in FIG. 1, the lower surface 19 is butted against the rear side of the front surface 11 and joined. Examples of joining methods include butt welding and fillet welding. Angle B between the lower surface 19 and the front surface 11 (the angle on the inside of the closed cross section) is formed as an acute angle (an angle less than 90 degrees). The sum of angle B and angle D is approximately 180 degrees.

[0020] The contact point of the lower surface 19 against the front surface 11 is set above the lower end 15 of the front surface 11. In other words, the lower end 15 of the front surface 11 protrudes downward from the position where the lower end 15 of the front surface 11 abuts against the lower surface 19. Also, as shown in FIG. 3(D), the dimension J of the first plate member 5 in the vehicle width direction is set to be larger than the dimension K of the second plate member 6 in the vehicle width direction. The first plate member 5 is formed in a shape that protrudes outward in the vehicle width direction (outward on both the left and right sides) beyond the second plate member 6. This increases the pressure-receiving area of ​​the front surface 11 during a collision, and the shock-absorbing performance of the vehicle can be improved.

[0021] As shown in FIG. 3(B), the lower end 15 of the front surface 11 is formed to have an uneven shape in a front view. This further increases the pressure-receiving area of ​​the front surface 11, and the cushioning performance of the vehicle can be further improved. In this embodiment, as shown in FIGS. 3(A) and (B), the rear end 16 of the first upper surface 12 is formed to have an uneven shape in a top view in correspondence with the uneven shape of the lower end 15. This reduces waste of steel plate and improves yield when cutting out a plurality of first plate members 5 from a single steel plate in the manufacturing process of the first plate member 5 by arranging the uneven shapes of adjacent first plate members 5 so as to correspond to each other.

[0022] As shown in FIG. 3(B), a front opening 13 is provided near the center of the front surface 11 in the vehicle width direction. Correspondingly, as shown in FIG. 3(D), a rear opening 20 is provided near the center of the rear surface 18 in the vehicle width direction. The front surface 11 also has a recess 14 formed in a shape in which the vertical center is recessed toward the rear of the vehicle. The depth of the recess 14 is not important. In the example shown in FIG. 1, the dimension G corresponding to the depth of the recess 14 is set smaller than the dimension F. The recess 14 is also formed over substantially the entire width of the front surface 11 from the left end to the right end, excluding the front opening 13. This increases the rigidity of the front surface 11, making it less likely to bend when an external force is applied. In addition, when a cushioning material (such as a foamed PP material) with a rectangular cross section is attached to the front side of the front surface 11, the cushioning material is caused to enter the inside of the recess 14 during a collision, thereby ensuring a deformation allowance, and therefore the cushioning performance of the vehicle can be improved.

[0023] As shown in Fig. 5, a bracket 7 for mounting a skid plate 26 to the vehicle is fixed to the lower part of the first cross member 4. A pair of brackets 7 are provided on the left and right with a gap in the vehicle width direction. The position of the bracket 7 in the vehicle width direction is set at a position that avoids the side members 2 when viewed from above. In the example shown in Figs. 3(A), (D), etc., the position of the bracket 7 is set on the inside of the pair of side members 2.

[0024] The bracket 7 of this embodiment is attached to the corner portion (the mountain fold portion connecting the rear surface 18 and the lower surface 19) of the second plate member 6, so as to function to prevent deformation that would increase the angle D due to an external force during a collision. The bracket 7 is formed in a shape that sandwiches the rear surface 18 and the lower surface 19 from the outside. The bracket 7 illustrated in FIG. 4 is provided with a pair of wall portions 21 and a bottom portion 23 that connects them. The wall portions 21 are planar portions that are disposed perpendicular to the rear surface 18 and the lower surface 19. The wall portions 21 are provided with fitting portions 22 that are recessed so as to fit into the corner portion formed by the rear surface 18 and the lower surface 19.

[0025] 1, bracket 7 is fixed to first cross member 4 with fitting portion 22 fitted into a mountain-folded portion where rear surface 18 and lower surface 19 of second plate member 6 are connected. In addition, bottom portion 23 is a flat portion that is disposed substantially horizontally when bracket 7 is attached to first cross member 4, and is connected to the lower end edges of the pair of wall portions 21. Mounting holes 24 for mounting a skid plate 26 are drilled in bottom portion 23.

[0026] [2. Actions and Effects] (1) The first cross member 4 has a substantially trapezoidal closed cross-sectional structure in which the two front corners A and B are acute angles and the two rear corners C and D are obtuse angles. With this configuration, the vertical step at the connection points between the first cross member 4 and the side members 2 can be reduced compared to when the first cross member 4 has a rectangular closed cross-sectional shape.

[0027] For example, the distance between the upper end at the rear end of the first cross member 4 and the upper end at the front end of the side member 2 (dimension L in FIG. 1) can be shortened. Similarly, the distance between the lower end at the rear end of the first cross member 4 and the lower end at the front end of the side member 2 (dimension M in FIG. 1) can also be shortened. This makes it possible to smooth the flow of load transmitted from the first cross member 4 to the side member 2. Therefore, the load transmission from the first cross member 4 to the side member 2 can be improved with a simple configuration.

[0028] Furthermore, the vertical dimension of the front surface 11 of the first cross member 4 can be made longer than in the case where the first cross member 4 has a rectangular closed cross section. This increases the pressure-receiving area of ​​the collision load, improving the shock-absorbing performance of the vehicle. Furthermore, the upper surface (first upper surface 12, second upper surface 17) of the first cross member 4 can be made to slope downward toward the rear of the vehicle, providing a first cross member 4 that is less likely to impede the flow of cooling air. In other words, the flow of cooling air passing near the first cross member 4 can be naturally guided diagonally downward toward the rear of the vehicle, as shown in FIG. 5. This makes it possible to smooth the flow of cooling air to the radiator 25 located behind the first cross member 4, improving the cooling performance of the radiator 25.

[0029] (2) The first cross member 4 includes a first plate member 5 disposed at the front and having a generally L-shaped cross section, and a second plate member 6 joined to the rear side of the first plate member 5 and having a generally U-shaped cross section. By combining these two members 5, 6, a generally trapezoidal closed cross-sectional structure can be easily realized, and the load transmission and cushioning performance can be improved while keeping manufacturing costs down.

[0030] Since the first plate member 5 is substantially L-shaped, it can be manufactured by bending one steel plate only once, which can save manufacturing labor, cost, time, etc. On the other hand, the second plate member 6 has two bent portions, but since both bending angles are obtuse angles, it can be manufactured with a single bending operation. That is, by simultaneously bending the second upper surface 17 and the lower surface 19 at a right angle with respect to the rear surface 18, the angles C and D become slightly larger than 90 degrees due to springback. Therefore, the second plate member 6 having the shape shown in FIG. 1 can be obtained by a single bending operation, which can save manufacturing labor, cost, time, etc.

[0031] (3) In the above-described first cross member 4, the first upper surface 12 of the first plate member 5 and the second upper surface 17 of the second plate member 6 are overlapped and joined, and the lower surface 19 of the second plate member 6 is abutted against and joined to the front surface 11 of the first plate member 5. With this configuration, the upper end of the front surface 11 of the first plate member 5 does not protrude above the first upper surface 12 and the second upper surface 17, so that the flow of cooling air to the radiator 25 can be made smoother, and the cooling performance of the radiator 25 can be improved.

[0032] Furthermore, with the above structure, when an external force acts from the front surface 11 of the first cross member 4 toward the rear of the vehicle, the butting portion between the underside 19 of the second plate member 6 and the front surface 11 of the first plate member 5 is unlikely to come loose. In other words, even if the first plate member 5 is deformed so as to be compressed in the fore-and-aft direction of the vehicle, the irregular quadrilateral closed cross-sectional structure is likely to be maintained. This makes it possible to suppress a decrease in rigidity of the first cross member 4 and the frame 1 during a collision.

[0033] (4) In the above-described first cross member 4, as shown in Fig. 1, the dimension F of the first upper surface 12 in the vehicle front-rear direction can be set to be shorter than half the dimension E. By setting it in this manner, buckling of the first upper surface 12 can be prevented, and the shape stability of the first cross member 4 can be improved.

[0034] (5) In the above-described first cross member 4, as shown in Fig. 1, the lower end 15 of the front surface 11 of the first plate member 5 protrudes downward from the abutting position with the second plate member 6. With this configuration, it is possible to increase the pressure-receiving area of ​​the front surface 11 during a collision, and to improve the shock-absorbing performance of the vehicle.

[0035] (6) In the above-described first cross member 4, the lower end 15 of the front surface 11 of the first plate member 5 is formed to have an uneven shape in a front view. With this configuration, it is possible to increase the pressure-receiving area of ​​the front surface 11 during a collision, and improve the cushioning performance of the vehicle. Note that, as shown in Figs. 3(A) and (B), the rear end 16 of the first upper surface 12 may be formed to have an uneven shape in a top view in correspondence with the uneven shape of the lower end 15. With this configuration, when cutting out a plurality of first plate members 5 from a single steel plate, the steel plate can be used without waste, and the yield can be improved.

[0036] (7) As shown in Fig. 3(D) , in the above-described first cross member 4, the first plate member 5 is formed in a shape that protrudes outward in the vehicle width direction further than the second plate member 6. With this configuration, it is possible to increase the pressure-receiving area of ​​the front surface 11 during a collision, and it is possible to improve the shock-absorbing performance of the vehicle.

[0037] (8) The second plate member 6 may be manufactured from a steel plate having a thickness greater than that of the first plate member 5. In this case, for example, when an external force toward the rear of the vehicle acts on the first cross member 4 during a collision, the first plate member 5 is first deformed so as to be compressed in the longitudinal direction of the vehicle. After that, the second plate member 6 is compressed in the longitudinal direction of the vehicle while transmitting the external force to the side member 2. In this way, by deforming the first cross member 4 in stages, the external force can be appropriately transmitted to the side member 2 while mitigating the impact, and the collision protection performance and load transmission can be improved. In addition, since the second plate member 6 is a thick plate, the efficiency of stress transmission to the side member 2 can be improved.

[0038] (9) As shown in FIG. 1, the front surface 11 of the first plate member 5 is provided with a recess 14 formed by recessing the vertical center of the front surface 11 toward the rear of the vehicle. This configuration can increase the rigidity of the front surface 11 and improve the shape stability of the first cross member 4. Furthermore, if a cushioning material with a rectangular cross section (such as a foamed PP material) is attached to the front side of the front surface 11, a deformation allowance can be secured by causing the cushioning material to enter the inside of the recess 14 during a collision. This can improve the cushioning performance of the vehicle.

[0039] (10) As shown in FIG. 4 , the first cross member 4 includes a bracket 7 on which a pair of walls 21 are formed. This bracket 7 is attached to the corner portion between the lower surface 19 and the rear surface 18 of the second plate member 6. In addition, the wall portions 21 are disposed perpendicular to the lower surface 19 and the rear surface 18 of the second plate member 6. This configuration makes it possible to prevent deformation that would increase the angle D due to an external force during a collision, and improves the shape stability of the first cross member 4.

[0040] [3.Other] The above embodiment is merely illustrative, and is not intended to exclude various modifications or application of techniques not explicitly stated in the embodiment. Each configuration of the embodiment can be modified in various ways without departing from the spirit of the embodiment. Furthermore, each configuration of the embodiment can be selected as necessary, or can be combined appropriately.

[0041] In the above embodiment, the first cross member 4 has the first plate member 5 and the second plate member 6, but a single first cross member 4 may be formed by bending a single steel plate multiple times. By forming a substantially trapezoidal closed cross section structure in which at least the two front corners are acute angles and the two rear corners are obtuse angles, it is possible to achieve the same effects as the above embodiment. [Industrial Applicability]

[0042] The present invention is applicable to the manufacturing industry of cross members attached to vehicles, and also to the manufacturing industry of vehicles having frames including cross members. [Explanation of symbols]

[0043] 1 Frame 2 Side members 3 End Plate 4 First cross member 5 First plate member 6 Second plate member 7 Bracket 8 Fasteners 11 Front 12 First top surface (top surface) 13 Front opening 14 Recess 15 Bottom edge 16 Rear end 17 Second top surface (top surface) 18 Rear 19 Bottom side 20 Rear opening 21 Wall 22 Fitting part 23 Bottom 24 Mounting holes 25 Radiator 26 Skid plate

Claims

1. A structure of a cross member attached to the front ends of a pair of side members extending in the longitudinal direction of a vehicle, comprising a first cross member having a substantially trapezoidal closed cross-section structure in which two corners located on the front side are formed as acute angles and two corners located on the rear side are formed as obtuse angles, wherein the first cross member includes a first plate member disposed on the front side and having a substantially L-shaped cross-section, and a second plate member joined to the rear side of the first plate member and having a substantially U-shaped cross-section. A cross member structure, characterized in that.

2. The upper surface of the first plate member and the upper surface of the second plate member are overlapped and joined, and the lower surface of the second plate member is abutted against and joined to the front surface of the first plate member. The cross member structure according to claim 1, characterized in that.

3. The overlapping position of the upper surface of the first plate member and the upper surface of the second plate member is located forward of the center in the longitudinal direction of the vehicle in the first cross member. The cross member structure according to claim 2, characterized in that.

4. The lower end of the front surface of the first plate member protrudes downward from the abutting position with the second plate member. The cross member structure according to claim 2 or 3, characterized in that.

5. The lower end of the front surface of the first plate member is formed so as to have an uneven shape in a front view. The cross member structure according to any one of claims 1 to 4, characterized in that.

6. The first plate member is formed in a shape protruding outward in the vehicle width direction from the second plate member. The cross member structure according to any one of claims 1 to 5, characterized in that.

7. The second plate member has a plate thickness thicker than that of the first plate member. The cross member structure according to any one of claims 1 to 6, characterized in that.

8. The front surface of the first plate member has a recess formed in a shape in which the central portion in the vertical direction is recessed rearward of the vehicle. The cross member structure according to any one of claims 1 to 7, characterized in that.

9. A bracket is provided, which is attached to the corner portion formed by the rear surface and the lower surface of the second plate member, and in which a pair of wall portions perpendicular to the lower surface and the rear surface are formed. The cross member structure according to any one of claims 1 to 8, characterized in that.

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