Vehicle skeleton member

Abstract

To inhibit stress concentration on a welding portion between an outer shell member and a reinforcement member disposed in the outer shell member at an elongated member having a closed cross sectional structure.SOLUTION: A welding opening 40 is formed at an outer shell member 18 for welding to a reinforcement member 20. In the welding opening 40, at both ends in its longitudinal direction, a curvature radius of an inner curve edge 46 which extends from an end point 44, curving to the side of a center wall part 34 of the reinforcement member 20 is larger than a curvature radius of an outer curve edge 48 which extends curving to the opposite side. Increasing the curvature radius of the edge at the center wall part 34 side of the reinforcement member where stress becomes high inhibits stress concentration.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a skeletal member of a vehicle, and particularly to the reinforcement of the skeletal member.

Background Art

[0002] Vehicle skeletal members often have a closed cross-section structure in order to ensure strength and rigidity. Further, for the purpose of maintaining the cross-sectional shape of the skeletal member, a partition-like reinforcing member may be provided inside. Patent Document 1 below shows a skeletal member of a vehicle in which a rear side frame (1) having a substantially hat-shaped cross-sectional shape and a floor panel (2) arranged so as to cover the opening portion of the rear side frame (1) form a closed cross-section structure. A bulkhead (3) is arranged inside the substantially hat-shaped rear side frame (1) and is welded to the rear side frame (1). The bulkhead (3) is arranged so as to partition the inner space of the rear side frame (1) in the longitudinal direction of the rear side frame (1), and reinforces the skeletal member having a closed cross-section structure formed by the rear side frame (1) and the floor panel (2). Note that the reference numerals in the above ( ) are the reference numerals used in Patent Document 1 below, and are not related to the reference numerals used in the description of the embodiments of the present application.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a load is applied to the skeletal member, stress may concentrate on the welding portion that joins the outer shell member forming the closed cross-section structure and the reinforcing member disposed inside this outer shell member.

[0005] An object of the present invention is to suppress stress concentration on the welding portion that joins the outer shell member and the reinforcing member.

Means for Solving the Problem

[0006] The skeletal member of the vehicle according to the present invention includes an outer shell member which is a long member having a closed cross-section, and a reinforcing member disposed inside the outer shell member. The reinforcing member has a central wall portion and two side wall portions respectively connected to opposite edges of the central wall portion, and the central wall portion and the side wall portions are arranged so as to form a U-shape. The reinforcing member is arranged such that the central wall portion intersects the longitudinal direction of the outer shell member, and the two side wall portions are respectively arranged along the two side walls of the outer shell member. A welding opening is formed in a portion of one side wall of the outer shell member that faces the side wall portion of the reinforcing member, and the edge of the welding opening is used for welding the outer shell member and the reinforcing member. At both ends in the longitudinal direction of the welding opening, the radius of curvature of the edge that curves and extends toward the central wall portion of the reinforcing member from the end point is larger than the radius of curvature of the edge that curves and extends toward the opposite side.

[0007] By increasing the radius of curvature of the edge on the central wall portion side at both ends where the stress of the welding opening becomes high, stress concentration can be suppressed.

[0008] The skeletal member of the vehicle described above, the edge on the central wall portion side of the reinforcing member from the end points on both sides of the welding opening can be in a shape where the central portion is linear and both ends are curved. By arranging a linear portion between the curved portions, the radius of curvature of the curved portions and the length of the welding opening can be determined independently.

[0009] The skeletal member of the vehicle described above may be a cross member extending in the left-right direction of the vehicle that supports the final reduction gear of the ladder frame. The strength and rigidity of the cross member that supports heavy objects can be increased.

Advantages of the Invention

[0010] By suppressing stress concentration at the edge of the welding opening, the fatigue strength of the welded portion can be increased.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, unless otherwise specified, terms indicating relative positions and directions such as front, rear, left, right, up, and down represent relative positions and directions with respect to the vehicle. In each figure, the direction of arrow FR is forward, the direction of arrow UP is upward, and the direction of arrow LH is leftward.

[0013] FIG. 1 is a perspective view showing the frame 10 of a vehicle. A vehicle body (not shown) is placed on the frame 10, a suspension (not shown) is attached, and an engine (not shown) is mounted, thereby constituting a so-called frame vehicle. The frame 10 includes a pair of side rails 12 extending in the front-rear direction along the left and right of the vehicle, and a plurality of cross members 14 extending in the left-right direction connecting the left and right side rails 12. In FIG. 1, some of the plurality of cross members are labeled 14. As shown in the figure, the side rails 12 and the cross members 14 are arranged in a ladder shape to form a ladder frame. Further, the side rails 12 and the cross members 14 are skeletal members constituting the skeleton of the vehicle. Furthermore, the side rail 12 is a long member having a closed cross-sectional structure, and the cross member 14 is also a long member having a closed cross-sectional structure as required.

[0014] FIG. 2 is a perspective view showing the rear end portion of the frame 10. The rearmost cross member 14B has a closed cross-section structure. The cross member 14B is provided with a differential support bracket 16 that supports a final reduction gear (not shown) at the center.

[0015] FIG. 3 is a view showing the rearmost cross member 14B in the vicinity of the differential support bracket 16. Further, FIG. 4 is a view showing a cross-section orthogonal to the longitudinal direction of the cross member 14B as viewed from the right. The cross member 14B has an outer shell member 18 that defines a closed cross-section and a reinforcing member 20 disposed inside the outer shell member 18.

[0016] As shown in FIG. 4, the outer shell member 18 is configured by opposing a front member 22 and a rear member 24 each having a U-shaped cross-section. The edge portions corresponding to both ends of the U-shape of the front member 22 and the rear member 24 are overlapped and welded here, whereby the outer shell member 18 is formed as a hollow long member having a rectangular cross-section. The outer shell member 18 has a front wall 26 that is a side wall located on the front side corresponding to each of the four sides of the rectangle, a rear wall 28 that is a side wall located on the rear side, an upper wall 30, and a lower wall 32. The upper wall 30 and the lower wall 32 are formed by welding the surfaces corresponding to the horizontal strokes of the U-shapes of the front member 22 and the rear member 24. The reinforcing member 20 is disposed so as to partition the space inside the cross member 14B left and right and is welded to the opposing walls of the outer shell member 18. Reinforcing members are also disposed symmetrically with respect to the left and right of the reinforcing member 20 shown in FIG. 3 on the right side of the differential support bracket 16. By disposing the reinforcing member 20 in the vicinity of the differential support bracket 16 that supports the heavy final reduction gear, the strength and rigidity of the cross member 14B are ensured.

[0017] FIG. 5 is a perspective view showing the reinforcing member 20 alone. The reinforcing member 20 has a central wall portion 34 and two side wall portions 36 and 38 respectively connected to the opposite edges of the central wall portion 34. In a state where the reinforcing member 20 is incorporated into the frame 10, particularly into the cross member 14B (see FIG. 3), the side wall portion 36 located on the front side is referred to as the front wall portion 36, and the side wall portion 38 located on the rear side is referred to as the rear wall portion 38. The central wall portion 34 is arranged so as to intersect, particularly orthogonally, with the extending direction of the cross member 14B, and divides the internal space defined by the outer shell member 18 of the cross member 14B into left and right. The front wall portion 36 is arranged along the front side wall 26 of the outer shell member 18, and the rear wall portion 38 is arranged along the rear side wall 28 of the outer shell member 18. The front wall portion 36 and the rear wall portion 38 of the reinforcing member 20 are welded to the front side wall 26 and the rear side wall 28 of the outer shell member 18 respectively, so that the reinforcing member 20 is integrated with the outer shell member 18.

[0018] In order to fix the reinforcing member 20 by welding inside the outer shell member 18 which is a long member with a closed cross section, it is necessary to weld from the outside of the outer shell member 18 at least on one surface. For this purpose, a welding opening 40 is formed in the rear side wall 28 of the outer shell member 18. Before the front side member 22 and the rear side member 24 of the outer shell member 18 are welded, the reinforcing member 20 is welded to the front side member 22, particularly to the front side wall 26 of the outer shell member 18. Specifically, it is welded along the edge 42 of the front wall portion 36 of the reinforcing member 20, and the reinforcing member 20 is fixed to the front side wall 26 of the outer shell member 18. The edge 42 of the front wall portion 36 is the edge on the side opposite to the edge connected to the central wall portion 34. The rear side member 24 is placed over the front side member 22 to which the reinforcing member 20 is fixed, and the edge of the rear side member 24 is welded to the front side member 22 to integrate the outer shell member 18. At the same time as this, or before or after this, the entire circumference is welded along the edge of the welding opening 40 from the outside of the outer shell member 18 to fix the reinforcing member 20 to the rear side member 24. In this way, a long member having a welded and fixed reinforcing member inside can be formed.

[0019] FIG. 6 is a view showing details of the shape of the welding opening 40 formed in the outer shell member 18. A part of the rear wall portion 38 of the reinforcing member 20 is exposed by the welding opening 40. The welding opening 40 has a long hole shape or a slit shape extending in the vertical direction. In the direction in which the welding opening 40 extends (hereinafter referred to as the longitudinal direction), the edges of the welding opening 40 are curved at both ends, and the shape is formed by connecting these curved edges with a straight line. The curved edges have different radii of curvature with respect to the end points 44 on both sides of the welding opening 40, and the radius of curvature of the edge 46 on the central wall portion 34 side (hereinafter referred to as the inner curved edge 46) is larger than the radius of curvature of the opposite edge 48 (hereinafter referred to as the outer curved edge 48). The inner curved edge 46 and the outer curved edge 48 are smoothly connected at the end point 44, avoiding stress concentration here. The inner curved edge 46 and the outer curved edge 48 may each be formed by an arc of a single radius.

[0020] A straight edge 50 (hereinafter referred to as the inner straight edge 50) is arranged so as to connect the inner curved edges 46 at both ends, and a straight edge 52 (hereinafter referred to as the outer straight edge 52) is arranged so as to connect the outer curved edges 48 at both ends. The inner curved edge 46 and the inner straight edge 50 are smoothly connected at these connection points, and the outer curved edge 48 and the outer straight edge 52 are also smoothly connected at these connection points. Also, the inner curved edges 46 at both ends may be directly connected without the inner straight edge 50 intervening therebetween. In this case, the inner curved edges 46 are smoothly connected to each other.

[0021] The stress applied to the welded portion of the edge of the welding opening 40 tends to be high at the edge near the central wall portion 34 of the end portion and the reinforcing member 20, that is, at the inner curved edge 46. By increasing the radius of curvature of the inner curved edge 46, stress concentration can be suppressed. When the dimension in the width direction of the welding opening 40, that is, the direction orthogonal to the longitudinal direction, is increased, it may lead to an increase in the dimension of the rear wall portion 38 of the reinforcing member 20 facing the welding opening 40 and an increase in weight. It is desirable to make the width of the welding opening 40 narrow enough to enable welding. By making the radius of curvature of the inner curved edge 46 larger than the radius of curvature of the outer edge 48, even if the width dimension of the welding opening 40 is the same, compared with the mode in which the radii of curvature of both are equal, stress concentration at the edge near the central wall portion 34 (inner curved edge 46) can be suppressed.

[0022] In the above embodiment, the welding opening is provided on one side surface of the skeleton member having a closed cross-sectional structure, but it may be provided on both side surfaces. Further, although long members such as side rails and cross members that constitute the frame are exemplified as the vehicle skeleton structure, the welding opening for welding the internal reinforcing member can also be applied to the skeleton member that forms a closed cross-section in the monocoque structure.

Explanation of reference numerals

[0023] 10 Frame, 14 Cross member, 16 Differential support bracket, 18 Outer shell member, 20 Reinforcing member, 22 Front side member, 24 Rear side member, 26 Front side wall (side wall), 28 Rear side wall (side wall), 34 Central wall portion, 36 Front wall portion (side wall portion), 38 Rear wall portion (side wall portion), 40 Welding opening, 42 Edge of the front wall portion, 44 End point, 46 Inner curved edge, 48 Outer curved edge, 50 Inner straight edge, 52 Outer straight edge.

Claims

1. An outer shell member which is a long member having a closed cross-section, A reinforcing member disposed inside the outer shell member, having a central wall portion and two side wall portions respectively connected to opposite edges of the central wall portion, and the central wall portion and the side wall portion are arranged to form a U-shape, the reinforcing member, A vehicle skeletal member having, The reinforcing member is arranged such that the central wall portion intersects the longitudinal direction of the outer shell member, and the two side wall portions are respectively arranged along the two side walls of the outer shell member, A welding opening is formed in a portion of one of the side walls of the outer shell member that faces the side wall portion of the reinforcing member, and the edge of the welding opening is used for welding the outer shell member and the reinforcing member, At both ends in the longitudinal direction of the welding opening, the radius of curvature of the edge that curves and extends toward the central wall portion of the reinforcing member from the end point is larger than the radius of curvature of the edge that curves and extends in the opposite direction, A vehicle skeletal member.

2. The vehicle skeletal member according to Claim 1, wherein the edges on the central wall portion side of the reinforcing member from the end points on both sides of the welding opening are linear at the central portion and curved at both ends, the vehicle skeletal member.

3. The vehicle skeletal member according to Claim 1 or 2, wherein the skeletal member is a cross member extending in the vehicle left-right direction that supports the final reduction gear of a ladder frame, the vehicle skeletal member.

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