JPH0323423Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to frame structures for vehicles and the like.

[Prior Art] Conventionally, the cross-sectional shape of an elongated frame of a vehicle or the like is usually a hollow rectangular cylinder, but there are cases where it is necessary to change the cross-sectional shape to a groove-shaped cross-section in the middle of the elongated frame in order to improve vibration etc. be. In this way, when the cross-sectional shape of the elongated frame changes from a hollow rectangular cylinder cross-sectional shape to a groove-shaped cross-sectional shape, the structure described below has been adopted in order to avoid stress concentration due to sudden changes in torsional rigidity.

As shown in FIG. 5, the elongated frame transitions from a hollow rectangular cylindrical member to a groove-shaped member midway in the longitudinal direction, and a reinforcing member 4a is provided at the transitional portion. This reinforcing member 4a has a flat plate-like inclined portion 4b.
, and each flange portion 6 of the inclined portion 4b
a, 6b, and 6c are fixed to both side walls 2a, 3a and bottom wall 1a of the groove section, respectively.

[Problems to be solved by the invention] In the conventional frame structure described above, the inclined part of the reinforcing member provided at the transition part from the hollow rectangular cylindrical member to the groove member is simply a flat plate. There is a problem in that stress concentration due to sudden changes in torsional rigidity still remains near the beginning of the shaped cross section, and stress concentration is not sufficiently alleviated.

The present invention has been made in view of the problems of the above-mentioned conventional techniques, and it is an object of the present invention to provide a frame structure that can sufficiently alleviate stress concentration near the start of a groove-shaped cross section.

[Means for Solving the Problems] In order to achieve the above object, the frame structure of the present invention has the frame structure in which the elongated frame transitions from a hollow rectangular cylindrical member to a groove member midway in the longitudinal direction. In the transition portion, a curved plate-shaped reinforcing member is provided in the groove of the groove shape member in a longitudinal direction inclined from the groove top to the groove bottom, and the vertical cross-sectional shape of the curved plate-shaped reinforcing member is as described above. The transition portion of the elongated frame is characterized in that the cross-sectional torsional rigidity of the transition portion is curved along a predetermined quadratic curve that linearly decreases.

[Function] In the present invention, the torsional rigidity of the transition portion from the hollow rectangular cylindrical member to the groove member is linearized by a curved plate-like reinforcing member whose vertical cross-sectional shape is curved along a predetermined quadratic curve. This prevents sudden changes in torsional rigidity.

[Example] Next, an example of the present invention will be described with reference to the drawings.

Fig. 1 is a schematic longitudinal cross-sectional view of a main part of an embodiment of the frame structure of the present invention, and Fig. 2 a, b, and c are cross sections A-A, B-B, and C-C in Fig. 1, respectively. It is a diagram.

As shown in FIG. 1, the elongated frame transitions from a hollow rectangular cylindrical member to a groove-shaped member midway in the longitudinal direction, and a curved plate-shaped reinforcing member 4 is provided at the transitional portion. This curved plate-shaped reinforcing member 4 is fixed to both side walls 2 (one side wall is not shown) of the groove section, and is provided inside the groove section at an angle from the top of the groove to the bottom of the groove. ing. As will be described in detail below, the longitudinal cross-sectional shape of the curved plate-shaped reinforcing member 4 is a shape that curves along a predetermined quadratic curve in which the cross-sectional torsional rigidity of the transitional portion of the elongated frame linearly decreases. It's summery.

That is, in FIG. 2a, the elongated frame has a perfect hollow rectangular cylindrical cross-sectional shape composed of both side walls 2, 3, a bottom wall 1, and a curved plate-shaped reinforcing member 4 serving as an upper wall. The curved plate-shaped reinforcing member 4 slopes toward the inner surface of the bottom wall 1 in a curved shape as it moves in the C-C cross-sectional direction, and in the B-B cross section, it is shown in FIG.
The cross-sectional shape shown in FIG.

Now, assuming that the distance between the A-A cross section and the C-C cross section in FIG. Let y be y, and in order to reduce the cross-sectional torsional stiffness of the elongated frame linearly with respect to the distance x,
Equation (1) must hold true.

(Torsional stiffness at distance x) = {(Torsional stiffness of A-A cross section) - (Torsional stiffness of C-C cross section)}・(-x/l
) + (Torsional stiffness of A-A cross section)...(1) Now, calculate the torsional stiffness values of A-A cross section, C-C cross section, and cross section at distance x from A-A cross section, respectively.
If JA, Jc, and Jx are used, the above equation (1) can be transformed into the following equation (2).

JX=(JA−Jc)・(−x/l)+JA (JA−Jc)・x=(JA−Jx)・l X=(JA−Jx)/(JA−Jc)・l……(2) Here, as shown in FIG. 2, the lengths of each side of the cross section are h ₁ , h ₂ , h ₃ , and h ₄ , and the wall thicknesses are t ₁ , t ₂ , t ₃ , and t ₄ , respectively. By substituting the values of the torsional stiffness of the cross section into the above equation (2) with h ₁ = h ₃ and h ₂ = h ₄ , the following equation (3) is obtained.

By substituting specific numerical values for h ₁ to h ₄ , t ₁ to t ₄ and l in the above equation (3), a quadratic curve is obtained. That is, the longitudinal cross-sectional shape of the curved plate-shaped reinforcing member 4 is obtained as a shape curved along the quadratic curve, thereby forming a hollow rectangular cylindrical cross section.
Since the torsional rigidity decreases linearly from the A cross section to the C-C cross section forming the groove-shaped cross section, stress concentration due to sudden changes in the torsional rigidity can be avoided.

Figure 3 is a vertical sectional view of the main parts when the frame structure of this example is actually manufactured by welding, Figure 4a,
b and c are cross-sectional views of FIG. 3, respectively. In each figure, flanges 5 and 6 are provided on the upper and lower surfaces of the curved plate-shaped reinforcing member 4, facing inward and outward, respectively, and one flange 5 is welded to both side walls 2 and 3 by welding parts 7. , the other flange 6 is welded at a welding portion 8. Due to the welding structure in which the flanges 5 and 6 are provided in opposite directions, the elongated frame transitions from a hollow rectangular cylindrical cross section to a groove cross section while maintaining a strong structure, making it easier to weld frames with such a structure. and become certain.

[Effects of the invention] As explained above, the present invention provides a frame structure that transitions from a hollow rectangular cylindrical cross-section to a groove-shaped cross-section, and is provided with a curved plate-shaped reinforcing member that linearly reduces the torsional rigidity of the transitional portion. Thereby, it is possible to prevent a sudden change in the torsional rigidity of the transition portion, and it is possible to avoid sudden stress concentration.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal cross-sectional view of a main part of an embodiment of the frame structure of the present invention, and FIG. Fig. 3 is a detailed longitudinal sectional view of the main parts of this embodiment, Fig. 4 a, b,
c is a cross-sectional view taken along lines A-A, B-B, and C-C in FIG. 3, respectively, and FIG. 5 is a perspective view of a main part of the conventional example. 1... Bottom wall, 2, 3... Side wall, 4... Curved plate-shaped reinforcing member, 5... Flange, 6... Flange, 7,
8...Welding part.

Claims (1)

[Claims for Utility Model Registration] In a frame structure in which the elongated frame transitions from a hollow rectangular cylindrical member to a groove-shaped member midway in the longitudinal direction, the transition portion includes a curved plate in the groove of the groove-shaped member. A reinforcing member in the shape of a curved plate is connected and inclined in the longitudinal direction from the top of the groove to the bottom of the groove, and the longitudinal cross-sectional shape of the curved plate-like reinforcing member is such that the cross-sectional torsional rigidity of the transition portion of the elongated frame linearly decreases. A frame structure characterized by having a shape curved along a predetermined quadratic curve.