JP2016199209A - Torsion beam, torsion beam assembly, and torsion beam type suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torsion beam which can effectively suppress the progress of metal fatigue, a torsion beam assembly, and torsion beam type suspension device.SOLUTION: A torsion beam 10 which is formed into a substantially-V shape at a closed cross section comprises: a first wall part 110 which forms a recess-side external face in the closed cross section; a second wall part 120 which forms a protrusion-side external face in the closed cross section; and a folded wall part 130 which is formed between a first wall side folded point 131 at which a protrusion at which the first wall part 110 progresses to the inside at the closed cross section, and a protrusion at which the first wall part progresses to the outside are connected to each other, and a second wall part side folded point 132 which corresponds to the first wall part side folded point 131 at the second wall part 120. The torsion beam also comprises a fatigue alleviation heavy-thickness shape part 140 which is formed into a heavy thickness heavier than the first wall part 110 and the second wall part 120 at the folded wall part 130 at a front side of a vehicle body, and at the folded wall part 130 at a rear side of the vehicle body.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a torsion beam, a torsion beam assembly, and a torsion beam suspension device that can be applied to a torsion beam suspension device of an automobile and can suppress metal fatigue.

As is well known, a torsion beam suspension device is widely used as one form of a suspension system for automobiles.
The torsion beam type suspension device includes a torsion beam assembly in which a pair of left and right arms that rotatably support left and right wheels are connected by a torsion beam, and a pair of left and right spring receiving portions are joined in the vicinity of the left and right ends of the torsion beam; The torsion beam is connected so as to be able to swing with the vehicle body via a pivot shaft extending from the left and right sides of the vehicle body toward the center side.

  The torsion beam has a fixed shape part and a mounting part connected to the left and right trailing arms, and when the vehicle body receives external force from the road surface, the torsion beam mainly secures the roll rigidity of the vehicle body by the torsional rigidity. It is configured.

  For example, a torsion beam is formed by plastic processing of a pipe along the axial direction thereof, and a closed cross section perpendicular to the longitudinal direction of the torsion beam has a substantially V shape or a substantially U shape from a mounting portion with a trailing arm toward a fixed shape portion. It is formed in the closed cross section of a shape (for example, refer patent document 1).

On the other hand, even if the torsion beam has sufficient roll rigidity, the torsion beam receives various external forces from the road surface via the wheels and arms, and thus a complicated stress distribution is generated due to such external forces.
For this reason, even when various external forces are applied from the road surface, it is necessary to suppress the progress of metal fatigue, and various techniques have been developed to suppress such metal fatigue (for example, Patent Documents 2 and 3). reference.).

JP 2011-635 A JP 2008-169455 A JP 2013-091433 A

  However, it is not always easy to suppress metal fatigue using the techniques described in Patent Documents 2 and 3, and a technique for efficiently suppressing the progress of metal fatigue generated in a torsion beam is desired. .

  The present invention has been made in consideration of such circumstances, and a torsion beam and a torsion beam assembly that can efficiently suppress the progress of metal fatigue with respect to a torsion beam applied to a torsion beam type suspension device for automobiles. It is another object of the present invention to provide a torsion beam suspension device.

As a result of earnest research on the technology for suppressing metal fatigue in a torsion beam used in a torsion beam suspension device of an automobile, the inventors protruded in either the up-down direction or in a substantially V-shaped or U-shaped closed section. Stress concentration is likely to occur in the folded wall portion where the first wall portion forming the concave outer surface and the second wall portion forming the convex outer surface are connected, and by reducing this stress concentration, the progress of metal fatigue generated in the torsion beam The knowledge that it was controlled efficiently was obtained.
And, in order to alleviate the stress concentration generated in the folded wall portion, it is effective to form a thick-walled portion that is thicker than the plate thickness of the first wall portion and the second wall portion in the folded wall portion. I found out.

In order to solve the above problems, the present invention proposes the following means.
According to the first aspect of the present invention, in the torsion beam type suspension device, a pair of left and right arms in the vehicle body width direction are connected to both ends in the longitudinal direction, and a cross section perpendicular to the longitudinal direction is a front end and a rear end in the vehicle longitudinal direction. A torsion beam having a substantially V-shaped or U-shaped closed cross section projecting upward or downward between the two, wherein the substantially V-shaped or U-shaped closed cross section is recessed in the closed cross section. A first wall portion forming a side outer surface, a second wall portion forming a convex outer surface in the closed cross section, and both ends of the first wall portion and the second wall portion, and the first wall portion is the closed cross section. A first wall side folding point where the inward projection and the outward projection are connected to each other, and a second wall side folding point corresponding to the first wall side folding point in the second wall portion, A folded wall formed between The fatigue-relieving thick wall shape formed thicker than the first wall portion and the second wall portion on at least one of the folded wall portion on the front side of the vehicle body and the folded wall portion on the rear side of the vehicle body. It has the part.

  The invention described in claim 12 is a torsion beam Assy, comprising the torsion beam described in any one of claims 1 to 11.

  A thirteenth aspect of the present invention is a torsion beam suspension device, characterized in that the torsion beam Assy according to the twelfth aspect is provided.

According to the torsion beam, the torsion beam assembly and the torsion beam type suspension device according to the present invention, the first wall portion in which the substantially V-shaped or substantially U-shaped closed section forms the concave outer surface and the second wall which forms the convex outer surface. A first wall portion turn-back point that is formed on both ends of the first wall portion and the second wall portion and is connected to the inward protrusion and the outward protrusion of the closed cross section in the first wall portion. A folding wall portion formed between the first wall portion side folding point and the corresponding second wall portion side folding point in the two wall portions, the folding wall portion on the front side of the vehicle body and the folding side wall on the rear side of the vehicle body Since at least one of the wall portions is provided with a fatigue-relieving thick-walled portion formed thicker than the first wall portion and the second wall portion, the stress concentration generated in the torsion beam is relieved and the metal fatigue of the torsion beam is reduced. Progress is suppressed.
In addition, by providing a thickened fatigue-reducing thick-walled portion on the folded wall portion, roll rigidity is increased compared to a torsion beam with a uniform plate thickness, but by setting the circumference of the torsion beam to be small, The progress of fatigue can be suppressed and the roll rigidity can be adjusted.
As a result, desired suspension performance can be ensured while effectively suppressing the progress of metal fatigue generated in the torsion beam.

  In this specification, the thicker than the first wall and the second wall means that the first wall (the second wall) when the thickness of the first wall is equal to the thickness of the second wall. ) Is thicker than both the first wall and the second wall when the thickness of the first wall differs from the thickness of the second wall. It means that there is.

  In this specification, the thickness of the first wall portion (second wall portion) is the thickness (steady wall thickness) of the portion where the thickness is constant in the first wall portion (second wall portion). Say. In addition, when the steady wall thickness cannot be specified in the first wall (or the second wall), the left and right folded walls along the closed section from the top of the first wall (corresponding to the bottom of the concave outer surface) The average thickness in the range of 1/2 to reach the part.

  Further, in this specification, the folded wall portion includes both ends of the first wall portion and the second wall portion, and bulges outward from the inside in a substantially V-shaped or substantially U-shaped closed section. The wall portion is located between the first wall portion side folding point and the second wall portion side folding point.

  Further, in this specification, “the second wall side folding point corresponding to the first wall side folding point in the second wall part” means that the second wall part is a substantially V-shaped or U-shaped closing point. In the case where a concave portion directed from the outside to the inside is formed in the cross section, the point (part) on the side located closest to the center of the second wall portion of the concave portion is referred to as the concave portion on the second wall portion. Is not formed, the second wall portion is a point (part) that faces the first wall portion side folding point and is closest to the first wall portion side folding point.

  Invention of Claim 2 is the torsion beam of Claim 1, Comprising: The said fatigue | exhaustion relaxation thick-walled shape part is a said 1st wall part and the said 1st as it approaches both ends from the center side of the said longitudinal direction. The distance between the two wall portions is formed over the entire length of the longitudinal shape changing portion where the distance gradually increases.

  According to the torsion beam according to the present invention, as the fatigue-reducing thick-walled shape portion approaches the both end portions from the center side in the longitudinal direction, the distance between the first wall portion and the second wall portion gradually increases. Since it is formed over the entire length, the stress concentration generated on both ends of the torsion beam can be efficiently relaxed. As a result, progress in the torsion beam can be efficiently suppressed.

  A third aspect of the present invention is the torsion beam according to the first aspect, wherein the fatigue-relieving thick-walled portion has a closed wall portion on the front end side corresponding to the front direction of the vehicle body in the closed cross section and the closed portion. It is characterized in that it is formed over the entire length of at least one of the folded-back wall portions on the rear end side corresponding to the rear direction of the vehicle body in the cross section.

According to the torsion beam according to the present invention, at least one of the folding wall portion on the front end side corresponding to the front direction of the vehicle body in the closed section and the folding wall portion on the rear end side corresponding to the rear direction of the vehicle body in the closed section. Since the fatigue-relieving thick wall portion is formed over the entire length of the wall portion, the folded wall portion in which the fatigue relaxation thick wall portion is formed over the entire length has no boundary to which the portions having different plate thicknesses are connected in the longitudinal direction. Therefore, the stress concentration in the folded wall portion can be efficiently relaxed.
As a result, the stress concentration in the torsion beam can be relaxed and the progress of metal fatigue can be efficiently suppressed.

  A fourth aspect of the present invention is the torsion beam according to the first aspect, wherein the fatigue-relieving thick-walled portion has a closed wall portion on the front end side corresponding to the front direction of the vehicle body in the closed section and the closed portion. It is characterized by being formed over the entire length of the folded wall portion on the rear end side corresponding to the rear direction of the vehicle body in the cross section.

According to the torsion beam of the present invention, the fatigue-relieving thick wall portion is formed over the entire length of the folded wall portion on the front end side and the folded wall portion on the rear end side, and the folded wall portion on the front end side and the folded wall portion on the rear end side are formed. In the longitudinal direction, there is no boundary to which the portions having different plate thicknesses are connected, so that the stress concentration in the folded wall portion can be efficiently reduced.
As a result, stress concentration can be relaxed over the entire length of the torsion beam, and the progress of metal fatigue can be suppressed.

  The invention according to claim 5 is the torsion beam according to any one of claims 1 to 4, wherein the thickness of the first wall portion is t1, and the thickness of the second wall portion is t2. The fatigue-relieving thick wall portion is formed from the folded wall portion to the first wall portion side to a range of (2 × t1), and from the folded wall portion to the second wall portion side. It is formed up to a range of (2 × t2).

  According to the torsion beam according to the present invention, when the thickness of the first wall portion is t1 and the thickness of the second wall portion is t2, the fatigue relaxation thick-walled shape portion is formed on the first wall portion side from the folded wall portion. (2 × t1) and is formed from the folded wall portion to the second wall portion side (2 × t2), so that the first wall portion side and the second wall of the folded wall portion are formed. The stress concentration on the part side can be sufficiently dispersed.

  A sixth aspect of the present invention is the torsion beam according to the fifth aspect, wherein the fatigue-relieving thick-walled shape portion has a thickness t1 of the first wall portion and a thickness t2 of the second wall portion. Thus, it is characterized by being formed thick in the range of 5% to 50%.

  According to the torsion beam according to the present invention, the fatigue-relieving thick wall portion is thick in the range of 5% to 50% with respect to the wall thickness t1 of the first wall portion and the wall thickness t2 of the second wall portion. Because the thickness difference between the thickness of the fatigue alleviating thick part, the thickness of the first wall part, and the thickness of the second wall part is large, the fatigue alleviating thick part and the first part Metal fatigue can be stably suppressed by suppressing the occurrence of concentrated stress at the connection portion between the first wall portion and the second wall portion. Further, an increase in the weight of the torsion beam can be suppressed.

  A seventh aspect of the present invention is the torsion beam according to any one of the first to sixth aspects, wherein the width of the fatigue-reducing thick-walled shape portion is increased from both ends in the longitudinal direction toward the center side. Is characterized by being gradually shortened.

  According to the torsion beam according to the present invention, the width of the fatigue-reducing thick-walled shape portion is formed so as to gradually become smaller from both ends in the longitudinal direction toward the center side. Can be efficiently performed.

  The invention according to claim 8 is the torsion beam according to any one of claims 1 to 7, wherein the metal material tube in which the fatigue-relieving thick wall portion is formed by an extrusion process or a drawing process. It is manufactured by plastic working.

  According to the torsion beam according to the present invention, since the metal material tube having the fatigue-relieving thick wall formed by the extrusion process or the drawing process is manufactured by plastic working, the fatigue relieving thick wall is formed. The produced metal material tube can be efficiently manufactured. As a result, the progress of metal fatigue can be suppressed and a torsion beam having a desired roll rigidity can be efficiently manufactured.

  A ninth aspect of the present invention is the torsion beam according to any one of the first to seventh aspects, wherein the metal material forms a fatigue-relieving thick shape corresponding portion corresponding to the fatigue relieving thick shape portion. A piece of metal material forming a first wall portion corresponding portion corresponding to the first wall portion and a metal material piece forming a second wall corresponding portion corresponding to the second wall portion are arranged in a plane direction. It is manufactured by rounding a metal material plate formed by connecting the boundaries of metal pieces by welding and plastic working a metal material tube having both end portions connected by connection portions.

  According to the torsion beam according to the present invention, the metal material piece forming the fatigue relaxation thick wall corresponding portion corresponding to the fatigue relaxation thick wall shape portion, the metal material piece forming the first wall corresponding portion corresponding to the first wall portion, and Metal material pieces forming the second wall portion corresponding to the second wall portion are arranged in the plane direction and the metal material plates formed by welding the boundaries of these metal pieces by welding are rounded to connect both end portions. Since the metal material tube connected by the part is manufactured by plastic working, it is possible to efficiently form a torsion beam in which a fatigue-reducing thick part having various configurations (width, thickness, etc.) is formed. it can. In addition, a fatigue-relieving thick-walled portion made of a plurality of different metals can be formed.

  A tenth aspect of the present invention is the torsion beam according to any one of the first to ninth aspects, wherein the fatigue relieving thick shape corresponding portion corresponding to the fatigue relieving thick shape portion is the fatigue light. It is manufactured by plastic working a metal material tube formed by connecting the metal material pieces corresponding to the relaxed thick wall shape corresponding parts by welding in the thickness direction.

  The torsion beam according to the present invention is formed by connecting in the thickness direction a metal material tube formed by welding the fatigue-reducing thick-walled portion and the corresponding metal material piece in the thickness direction. Since the metal material tube is manufactured by plastic working, it is possible to efficiently form a torsion beam in which a fatigue-relieving thick wall portion having various configurations (width, thickness, etc.) is formed. In addition, a fatigue-relieving thick-walled portion made of a plurality of different metals can be formed.

  The invention according to claim 11 is the torsion beam according to any one of claims 1 to 10, wherein the connection portion is the second portion when the connection portion is formed in the longitudinal direction. It is formed in the wall part, It is characterized by the above-mentioned.

  According to the torsion beam according to the present invention, since the connecting portion is formed in the second wall portion along the longitudinal direction, it is possible to efficiently process the first wall portion.

According to the torsion beam, the torsion beam assembly, and the torsion beam suspension device according to the present invention, the stress concentration generated in the torsion beam is alleviated and the progress of metal fatigue is suppressed.
As a result, desired suspension performance can be ensured while effectively reducing metal fatigue generated in the torsion beam.

1 is a perspective view illustrating a schematic configuration of a torsion beam type rear suspension device according to a first embodiment of the present invention. It is a perspective view explaining schematic structure of the torsion beam Assy concerning a 1st embodiment of the present invention. It is a perspective view explaining schematic structure of the torsion beam concerning a 1st embodiment of the present invention. It is a perspective view explaining the outline of the longitudinal direction shape change part of the torsion beam concerning a 1st embodiment of the present invention. It is sectional drawing which shows schematic structure of the torsion beam which concerns on the 1st Embodiment of this invention, (A), (B), (C) is arrow VA-VA, VB-VB, VC-VC in FIG. It is a figure which shows the closed cross section shown by. It is a figure which shows the detail of the fatigue relaxation thick part in the folding | turning wall part of the torsion beam which concerns on the 1st Embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining an example of schematic structure in the manufacturing process of the torsion beam concerning the 1st Embodiment of this invention, (A) is a schematic structure of the material steel plate used in order to form the welded tube used as the material of a torsion beam. (B) is the figure which looked at the welding pipe before shape | molding to a torsion beam along the axial direction, (C) is the figure which shows the closed cross section which looked at the torsion beam along the longitudinal direction. It is a figure explaining the folding | turning wall part of the torsion beam which concerns on the modification of the 1st Embodiment of this invention, and a fatigue relaxation thick-walled shape part. It is a figure explaining an example of schematic structure in a manufacturing process of a torsion beam concerning a 2nd embodiment of the present invention, and (A) shows a schematic structure of a material steel plate used in order to form a welding pipe used as a material of a torsion beam. (B) is the figure which looked at the welding pipe before shape | molding to a torsion beam along the axial direction, (C) is the figure which shows the closed cross section which looked at the torsion beam along the longitudinal direction. It is a figure explaining an example of schematic structure in a manufacturing process of a torsion beam concerning a 3rd embodiment of the present invention, and (A) shows a schematic structure of a material steel plate used in order to form a welding pipe used as a material of a torsion beam. (B) is the figure which looked at the welding pipe before shape | molding to a torsion beam along the axial direction, (C) is the figure which shows the closed cross section which looked at the torsion beam along the longitudinal direction. It is a figure explaining an example of schematic structure in a manufacturing process of a torsion beam concerning a 4th embodiment of the present invention, and (A) is a schematic structure of a material steel plate used in order to form a welding pipe used as a material of a torsion beam. (B) is the figure which looked at the welding pipe before shape | molding to a torsion beam along the axial direction, (C) is the figure which shows the closed cross section which looked at the torsion beam along the longitudinal direction. It is a figure explaining the schematic structure of the Example for confirming the effect of this invention.

<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a diagram showing an outline of a torsion beam type rear suspension device (torsion beam type suspension device) according to a first embodiment of the present invention. Reference numeral 1 denotes a torsion beam type rear suspension device, reference numeral 2 denotes a torsion beam assembly. Reference numeral 10 denotes a torsion beam. In addition, the code | symbol F shown in the figure has shown the front of the vehicle, and the code | symbol R has shown back.

  As shown in FIG. 1, the torsion beam type rear suspension device 1 includes, for example, a torsion beam Assy 2, a spring 3 that connects the torsion beam Assy 2 and a vehicle body (not shown), and an absorber 4.

  The torsion beam Assy 2 supports the left and right wheels WL and WR by a pair of left and right trailing arms 5 and is connected to the vehicle body via pivot shafts JL and JR extending from the left and right sides of the vehicle body toward the front middle side of the vehicle body. ing. And it is comprised so that rocking | fluctuation with respect to a vehicle body is possible.

As shown in FIG. 2, the torsion beam Assy 2 includes, for example, a pair of left and right trailing arms (arms) 5, a torsion beam 10 that connects the left and right trailing arms 5, and a pair of left and right spring receiving portions 3 A that support the spring 3. And. Moreover, one end side of the absorber which is a buffer device is connected to a buffer receiving portion (not shown).
In the first embodiment, as shown in FIGS. 1 and 2, the torsion beam 10 has a substantially V-shaped closed cross section that is convex downward.

  As shown in FIG. 2, the trailing arm 5 includes, for example, a trailing arm main body 5A, a pivot mounting member 5F connected to the front side end of the trailing arm main body 5A and supported by the vehicle body via a pivot shaft J. And a wheel mounting member 5R connected to the rear side end and supporting the wheel.

  The spring receiving portion 3A is formed on the opposite side of the pivot mounting member 5F with the torsion beam 10 interposed therebetween, and one end side of the spring 3 is arranged, and the load received from the road surface is applied to the wheels WL, WR, and the trailing arm 5. The load is transmitted to the vehicle via the spring 3.

Hereinafter, the torsion beam 10 according to the first embodiment will be described with reference to FIGS.
FIG. 3 is a perspective view illustrating a schematic configuration of the torsion beam 10 according to the first embodiment, and FIG. 4 is a perspective view illustrating an outline of a longitudinal shape changing portion of the torsion beam 10. FIG. 5 is a cross-sectional view showing a schematic configuration of the torsion beam 10, and FIG. 6 is a view showing details of the fatigue-relieving thick wall portion in the folded wall portion of the torsion beam 10.
In addition, the dashed-two dotted line in FIGS. 5-7 shows the thickness difference of a fatigue relaxation thick part, a 1st wall part, and a 2nd wall part.

The torsion beam 10 is manufactured by, for example, plastic working a material pipe along its axial direction.
Further, as shown in FIG. 3, the torsion beam 10 includes a constant shape closed cross section 11 having a substantially V-shaped closed cross section on the center side in the longitudinal direction, a longitudinal shape change section 12, and a mounting closed cross section. And a mounting portion 14 for mounting the trailing arm 5 having a substantially elliptical closed cross section formed at both ends in the longitudinal direction.
Moreover, the fixed shape closed cross-section part 11, the longitudinal direction shape change part 12, the attachment closed cross-section part 13, and the attachment part 14 are formed in this order from the longitudinal direction center side of the torsion beam 10 toward both ends.

As shown in FIG. 3, the fixed-shaped closed cross-section portion 11 is located on the center side in the longitudinal direction of the torsion beam 10.
The cross section perpendicular to the longitudinal direction of the torsion beam 10 is, for example, a substantially V-shaped closed cross section as shown in FIG.
The closed cross section shown in FIG. 5 (A) is a closed cross section indicated by an arrow VA in FIG. 4, and the fixed cross section 11 having the fixed cross section 11 and the longitudinal shape changing section 12 connected to each other. It is a closed cross section in the both ends and the edge part of the longitudinal direction center side of the longitudinal direction shape change part 12. FIG.

Further, as shown in FIG. 5A, the fixed-shaped closed cross-section portion 11 includes a first wall portion 110A (110) that forms a concave outer surface in the substantially V-shaped closed cross section, and a convex outer surface in the closed cross-section. A second wall 120A (120) formed; a folded wall 130A (130) that bulges outward in a closed cross section, forming both ends of the first wall 110A (110) and the second wall 120A (120); And a fatigue-relieving thick wall portion 140A (140).
Moreover, the fixed shape closed cross-section part 11 is formed symmetrically in the longitudinal direction of the vehicle body, for example.

  As shown in FIGS. 5A and 6, the folded wall portion 130A (130) includes both ends of the first wall portion 110A (110) and the second wall portion 120A (120), and is on the first wall portion side. It is formed between the turning point 131A (131) and the second wall side turning point 132A (132).

  The first wall portion side turn-back point 131A (131) is a connection point where the first wall portion 110A (110) is connected to the inward protrusion and the outward protrusion in the closed cross section.

  Further, in this embodiment, the second wall portion side turning point 132A (132) is a concave portion that is partially formed on the second wall portion 120A (120) and protrudes from the outside to the inside in the closed section. Of these, the point (part) is located closest to the center of the second wall 120A (120).

  In this embodiment, the fatigue relieving thick wall portion 140A (140) is formed over the entire length (full width) in the direction along the closed cross section of the two folded wall portions 130A (130), for example, and the first wall portion side folding point is formed. The first wall portion 110A (110) extends from 131A (131) toward the center of the first wall portion 110A (110) to a position twice as long as the plate thickness t1 of the first wall portion 110A (110). The second wall side folding point 132A (132) extends from the center of the second wall 120A (120) to a position twice as long as the plate thickness t2 of the second wall 120A (120). Yes.

  Further, the plate thickness t3 (mm) of the fatigue relaxation thick wall portion 140A (140) is the plate thickness t1 (for example, 1.0 mm to 5.0 mm) of the first wall portion 110A (110), and the second wall portion 120A. For example, it is formed to be 5% to 50% thick with respect to the plate thickness t2 (for example, 1.0 mm to 5.0 mm) of (120), and the range is approximately 1.05 mm to 7.50 mm. Yes.

As shown in FIGS. 3 and 4, the longitudinal direction shape changing portion 12 is formed on both ends of the constant shape closed cross-section portion 11 in the torsion beam 10, for example.
The cross section perpendicular to the longitudinal direction of the torsion beam 10 is a substantially V-shaped closed cross section. For example, as shown in FIGS. 5 (A), 5 (B), and 5 (C), Spaces L10A, L10B, L10C (L10) between the first wall portions 110A, 110B, 110C (110) and the second wall portions 120A, 120B, 120C (120) are fixed closed cross-section portions 13 from the fixed-shape closed cross-section portion 11 side. It is comprised so that it may spread gradually as it approaches.
The closed cross sections shown in FIGS. 5B and 5C are closed cross sections shown by arrow VB and arrow VC in FIG.

Further, as shown in FIGS. 5A, 5B, and 5C, the longitudinal shape changing portion 12 includes a first wall portion 110A that forms a concave outer surface in a substantially V-shaped closed cross section. 110B, 110C (110), second wall portions 120A, 120B, 120C (120) forming a convex outer surface in the closed cross section, first wall portions 110A, 110B, 110C (110) and second wall portion 120A, Folding wall portions 130A, 130B, and 130C (130) that form both ends of 120B and 120C (120) and bulge outward in a closed section, and fatigue-relieving thick-walled shape portions 140A, 140B, and 140C (140) I have.
Moreover, the longitudinal direction shape change part 12 is formed symmetrically in the longitudinal direction of the vehicle body, for example.

  As shown in FIGS. 5A, 5B, 5C, and 6, the folded wall portions 130A, 130B, and 130C (130) are provided with the first wall portions 110A, 110B, and 110C (110). And the second wall portion 120A, 120B, 120C (120), between the first wall side folding point 131A, 131B, 131C (131) and the second wall side folding point 132A, 132B, 132C (132). Is formed.

  The first wall side turn-back points 131A, 131B, and 131C (131) are connections in which the first wall portions 110A, 110B, and 110C (110) are connected to the inward protrusion and the outward protrusion in the closed section. It is a point.

  Further, in this embodiment, the second wall portion side turning points 132A, 132B, 132C (132) are partially formed on the second wall portions 120A, 120B, 120C (120) from the outside in the closed cross section. It is a point (part) located on the center side of the second wall portions 120A, 120B, 120C (120) most of the concave portion protruding inward.

  In this embodiment, the fatigue-relieving thick wall-shaped portions 140A, 140B, 140C (140) are formed over the entire length (full width) in the direction along the closed section of the two folded wall portions 130A, 130B, 130C (130), for example. First wall portion first wall portions 110A, 110B, and 110C (first wall portion side folding points 131A, 131B, and 131C (131) toward the center side of the first wall portions 110A, 110B, and 110C (110), respectively). 110) and the center of the second wall portion 120A, 120B, 120C (120) from the second wall side folding point 132A, 132B, 132C (132). The second wall portions 120A, 120B, and 120C (120) extend toward the side to a position that is twice as long as the plate thickness t2.

  In addition, the plate thickness t3 (mm) of the fatigue relief thick wall portions 140A, 140B, 140C (140) is the plate thickness t1 of the first wall portions 110A, 110B, 110C (110) (for example, 1.0 mm to 5. mm). 0 mm) and the thickness t2 (for example, 1.0 mm to 5.0 mm) of the second wall portions 120A, 120B, and 120C (120), for example, 5% to 50% thick, and the range is Approximately 1.05 mm to 7.50 mm.

The mounting closed cross-section portion 13 is formed between the longitudinal shape changing portion 12 and the mounting portion 14 and has a substantially elliptical closed cross section similar to the mounting portion 14.
The attached closed cross-section portion 13 is formed with a fatigue relieving thick shape portion 140 that is continuous from the longitudinal direction shape changing portion 12.

In this embodiment, the fatigue relaxation thick wall portion 140 is formed over the entire length of the torsion beam 10, and the length (width) in the direction along the closed cross section of the fatigue relaxation thick wall portion 140 is the longitudinal direction. It is comprised so that it may become gradually wide gradually toward the both ends from the center side.
Further, the plate thickness t1 of the first wall portion 110, the plate thickness t2 of the second wall portion 120, and the plate thickness t3 of the fatigue relaxation thick-walled shape portion 140 are the same over the entire length.

Next, an example of a schematic configuration in the manufacturing process of the torsion beam 10 according to the first embodiment will be described with reference to FIG.
FIG. 7 is a diagram for explaining an example of a schematic configuration in the manufacturing process of the torsion beam 10. FIG. 7A is a schematic configuration of a material steel plate for forming a welded pipe (material pipe) used as a material of the torsion beam 10. 7 (B) is a view of the welded tube before being formed into the torsion beam 10 along the axial direction, and FIG. 7 (C) is a closed view of the torsion beam 10 viewed along the longitudinal direction. It is a figure which shows a cross section.
7A shows the material steel plate viewed in the thickness direction, and the lower diagram shows the material steel plate viewed along the direction corresponding to the longitudinal direction of the torsion beam 10. It is.
Moreover, in FIG. 7, the code | symbol M10 has shown the material steel plate, and the code | symbol P10 has shown the welded pipe (metal material pipe | tube).

  The torsion beam 10 is formed, for example, by forming a welded pipe P10 from a material steel plate M10 and plastic processing the welded pipe P10 along its longitudinal direction.

  As shown in FIG. 7A, the material steel plate (metal material plate) M10 corresponds to, for example, a first wall portion corresponding portion (metal material) M110 corresponding to the first wall portion 110 and a second wall portion 120. Corresponding to the second wall portion corresponding portion (metal material) M120 and the fatigue reducing thick portion 140 and formed between the first wall portion corresponding portion M110 and the second wall portion corresponding portion M120, respectively. And a shape-corresponding portion (metal material) M140.

In 1st Embodiment, the 1st wall part corresponding | compatible part M110 is arrange | positioned at the both sides of the steel plate M10.
The fatigue relaxation thick wall corresponding part M140 is formed over the entire length in the longitudinal direction of the material steel plate M10A, and the width of the fatigue relaxation thick wall corresponding part M140 (the length in the direction perpendicular to the length direction of the torsion beam 10) is determined by the torsion beam. It is formed to be gradually shorter (narrower) toward the longitudinal center side corresponding to the length direction of 10.

The fatigue relaxation thick wall corresponding part M140 in the material steel plate M10 can be formed by the following method, for example.
(1) When rolling a steel sheet, the thick fatigue relaxation thick wall corresponding part M140 is formed by using a rolling roll in which a recess corresponding to the fatigue relaxation thick wall corresponding part M140 is formed.
(2) A strip (metal material piece) having a shape corresponding to the first wall portion corresponding portion (metal material) M110, the second wall portion corresponding portion (metal material) M120, and the fatigue relieving thick shape corresponding portion (metal material) M140. Is formed in advance. And the fatigue relaxation thickness between the strip (metal material piece) corresponding to the first wall portion corresponding portion (metal material) M110 and the strip (metal material piece) corresponding to the second wall portion corresponding portion (metal material) M120. A strip (metal material piece) corresponding to the meat shape corresponding part (metal material) M140 is arranged, and the boundary between the first wall corresponding part M110 and the fatigue relieving thick shape corresponding part M140 and the second wall corresponding part M120, The boundary of the fatigue relaxation thick wall shape corresponding part M140 is welded and connected along the surface direction (longitudinal direction). (TWB (Tailored Blank Method))
(3) A plate (metal material) for forming the fatigue relieving thick shape corresponding portion M140 on the steel plate (metal material) corresponding to the first wall portion corresponding portion M110 and the second wall portion corresponding portion M120 is in the plate thickness direction. Weld on top of each other.

The first wall portion corresponding portion M110 has a plate thickness t1 (for example, 1.0 mm to 5.0 mm), the second wall portion corresponding portion M120 has a plate thickness t2 (for example, 1.0 mm to 5.0 mm), and a fatigue relieving thickness. The shape corresponding part M140 is formed to have a plate thickness t3 (for example, 1.05 mm to 7.50 mm).
In this embodiment, the plate thickness t1 of the first wall portion corresponding portion M110 and the plate thickness t2 of the second wall portion corresponding portion M120 are the same plate thickness.
The plate thickness t3 is formed, for example, as plate thickness t3 = (plate thickness t1 (t2)) × (1.05-1.50).

  In addition, a plate thickness changing portion that gradually increases from the plate thickness t1 to the plate thickness t3 is formed on the fatigue relaxation thick wall shape corresponding portion M140 side of the first wall corresponding portion M110, and the fatigue of the second wall corresponding portion M120 is increased. A plate thickness changing region that gradually increases from the plate thickness t2 to the plate thickness t3 is formed on the moderate thick shape corresponding portion M140 side.

The welded pipe P10 is formed, for example, by rounding the material steel plate M10 in a direction perpendicular to the longitudinal direction of the torsion beam 10 as indicated by an arrow T in FIG.
In manufacturing the welded pipe P10, for example, it is possible to roll it by applying press molding or roll forming.

In the first embodiment, as shown in FIG. 7B, the second tube wall portion P120 corresponding to the second wall portion 120 in the closed cross section of the torsion beam 10 is formed by rolling the material steel plate M10. A seam portion (connecting portion) P10S is formed on the first tube wall portion P110 corresponding to the first wall portion 110 in the closed cross section based on welding when forming the welded tube P10.
For example, laser welding can be applied to the connection at the seam portion (connection portion) P10S.
Further, when the material steel plate M10 is rolled to form the seam portion P10S, a well-known metal tube manufacturing technique such as an electric resistance welded tube manufacturing process may be applied.

The torsion beam 10 is formed by plastic working the welded pipe P10 along its longitudinal direction, and is formed by applying, for example, press molding, hydraulic press molding, hydroforming, or the like.
As a result, as shown in FIG. 7C, a torsion beam 10 having a closed cross section formed in a substantially V shape and having a seam portion 10S formed on the first wall portion 110 is formed.

<First Embodiment (Modification)>
Next, a modified example of the first embodiment will be described with reference to FIG.
FIG. 8 is a diagram for explaining a schematic configuration of the folded wall portion and the fatigue-reducing thick wall portion according to the modification of the first embodiment. In FIG. 8, reference numeral 125 denotes the second wall portion, and reference numeral 135 denotes the folding. Reference numeral 145 denotes a wall portion, and a fatigue-relieving thick wall portion. In addition, a two-dot chain line in FIG. 8 indicates a thickness difference between the fatigue relaxation thick wall portion 145 and the first wall portion 110 and the second wall portion 125.

  In the modification of the first embodiment, as shown in FIG. 8, the second wall 125 has a portion (second wall side folding point 132) protruding inward in the closed section shown in FIG. 6. Since it is not formed, the “second wall portion side turning point 137 corresponding to the first wall portion side turning point 131 in the second wall portion 125” applied when specifying the turning wall portion 135 is the first implementation. It is set as the structure different from the 2nd wall part side folding | turning point 132 in a form.

Specifically, the second wall portion side turning point 137 faces the first wall portion side turning point 131 in the second wall portion 125, and the distance L130A from the first wall portion side turning point 131 is the smallest. It is considered as a part.
The folding wall part 135 is formed between the first wall part side folding point 131 and the second wall part side folding point 137.

  The fatigue-relieving thick-walled portion 145 extends along the closed section from the folded wall 135 to the first wall 110 side (2 × t1) or more and to the second wall 125 side (2 × t2). It is formed to the range of the above range. Since others are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted.

According to the torsion beam 10, the torsion beam Assy2, and the torsion beam type rear suspension device 1 according to the first embodiment, the stress concentration generated in the torsion beam 10 is alleviated, so that the progress of metal fatigue can be suppressed.
As a result, desired suspension performance can be ensured as the torsion beam type rear suspension device 1 while effectively reducing metal fatigue generated in the torsion beam 10.

  According to the torsion beam 10, the torsion beam Assy 2 and the torsion beam type rear suspension device 1 according to the first embodiment, over the entire length of the folded wall portion 130 on both the front end side and the rear end side of the closed section formed in a substantially V shape. Since the fatigue relaxation thick wall portion 140 is formed, the fatigue relaxation thick wall portion 140 is formed over the entire length of the folded wall portion 130 on the front end side and the folded wall portion 130 on the rear end side, and the folded wall portion on the front end side. In the longitudinal direction of 130 and the folded wall 130 on the rear end side, there is no boundary where the portions having different plate thicknesses are connected, so that the stress concentration can be efficiently reduced.

  According to the torsion beam 10, the torsion beam Assy 2 and the torsion beam type rear suspension device 1 according to the first embodiment, the fatigue-relieving thick wall portion 140 is (2 × t1) or more from the folded wall portion 130 to the first wall portion 110 side. Since it is formed to the range and is formed to the range of (2 × t2) or more from the folded wall portion 130 to the second wall portion 120 side, the first wall portion 110 side and the second wall portion 120 of the folded wall portion 130 are formed. The stress concentration on the side can be sufficiently dispersed.

  According to the torsion beam 10, the torsion beam Assy 2, and the torsion beam type rear suspension device 1 according to the first embodiment, the thickness (thickness) t 3 of the fatigue reducing thick wall portion 140 is equal to the thickness (thickness) of the first wall portion 110. Since the thickness is about 5 to 50% thicker than the thickness t1 and the plate thickness (thickness) t2 of the second wall portion 120, the torsion beam 10 is prevented from becoming heavy while suppressing metal fatigue. be able to.

  According to the torsion beam 10, the torsion beam Assy 2 and the torsion beam type rear suspension device 1 according to the first embodiment, the width of the fatigue reducing thick wall portion 140 is gradually reduced from both ends in the longitudinal direction toward the center side. Therefore, the weight of the torsion beam 10 can be efficiently reduced while suppressing metal fatigue.

  According to the torsion beam 10, the torsion beam Assy 2, and the torsion beam type rear suspension device 1 according to the first embodiment, the first wall part corresponding part (metal material) M 110 corresponding to the first wall part 110, the second wall part 120, Fatigue relaxation thicknesses formed between the corresponding first wall portion corresponding portion M110 and the second wall portion corresponding portion M120 corresponding to the corresponding second wall portion corresponding portion (metal material) M120 and the fatigue reducing thick wall shape portion 140, respectively. Since the welded pipe P10 formed by molding the material steel plate M10 in which the wall shape corresponding portion (metal material plate) M140 is connected in the plane direction is formed by plastic working, the fatigue relief thick wall shape portion 140 in the longitudinal direction is formed. Even when the width changes, it can be manufactured efficiently.

<Second Embodiment>
Next, a torsion beam 10A according to the second embodiment will be described with reference to FIG. In FIG. 9, a two-dot chain line indicates a thickness difference between the fatigue-relieving thick wall portion, the first wall portion, and the second wall portion.

FIG. 9 is a diagram for explaining an example of a schematic configuration in the manufacturing process of the torsion beam 10A. FIG. 9A is a schematic configuration of a material steel plate for forming a welded pipe (material pipe) used as a material of the torsion beam 10A. FIG. 9B is a view of the welded tube before being formed into the torsion beam 10A along the axial direction. FIG. 9C is a closed view of the torsion beam 10A viewed along the longitudinal direction. It is a figure which shows a cross section.
In addition, the upper figure shown to FIG. 9 (A) is the figure which looked at the material steel plate in the thickness direction, and the lower figure is the figure which looked at the material steel plate along the direction corresponding to the longitudinal direction of 10 A of torsion beams. It is.
Moreover, in FIG. 9, the code | symbol M10A has shown the material steel plate, and the code | symbol P10A has shown the welded pipe (metal material pipe | tube).

  The torsion beam 10A is formed, for example, by forming a welded pipe P10A from a material steel plate M10A and plastic processing the welded pipe P10A along its longitudinal direction.

  As shown in FIG. 9A, the material steel plate (metal material plate) M10A corresponds to the first wall portion corresponding to the first wall portion 110A (metal material) M110A and the second wall portion 120, for example. Corresponding to the second wall portion corresponding portion (metal material) M120A and the fatigue reducing thick portion 140A and formed between the first wall portion corresponding portion M110A and the second wall portion corresponding portion M120A, respectively. And a shape corresponding part (metal material) M140A.

In 2nd Embodiment, the 1st wall part corresponding | compatible part M110A is arrange | positioned at the both sides of material steel plate M10A.
The fatigue relaxation thick wall corresponding part M140 is formed over the entire length in the longitudinal direction of the material steel plate M10, and the width (length in the direction along the closed cross section of the torsion beam 10A) of the fatigue relaxation thick wall corresponding part M140A is made of the material steel plate M10A. The same width is formed over the entire length.

The torsion beam 10A is formed by plastic processing the welded pipe P10A along the longitudinal direction by applying, for example, press molding, hydraulic press molding, hydroforming, or the like.
As a result, as shown in FIG. 9C, a torsion beam 10 having a closed cross section formed in a substantially V shape and having a seam portion (connection portion) 10S formed on the first wall portion 110 is formed. .
Since others are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted.

According to the torsion beam 10, the torsion beam Assy 2 and the torsion beam type rear suspension device 1 according to the second embodiment, the width of the fatigue reducing thick wall portion 140 is formed to be the same width in the longitudinal direction of the torsion beam 10. In addition to the embodiment, the material steel pipe (metal material pipe) having a developed shape as shown in FIG. 9A is directly formed by drawing or extrusion without forming the material steel plate (metal material board) M10A. It may be formed.
By directly forming a material steel pipe (metal material pipe) corresponding to the welded pipe P10A by pultrusion molding or extrusion molding, the torsion beam 10A can be manufactured efficiently and at low cost.

<Third Embodiment>
Next, an example of a schematic configuration in the manufacturing process of the torsion beam 10B according to the third embodiment will be described with reference to FIG. In FIG. 10, an alternate long and two short dashes line indicates a thickness difference between the fatigue relieving thick wall portion, the first wall portion, and the second wall portion.

FIG. 10 is a diagram for explaining an example of a schematic configuration in the manufacturing process of the torsion beam 10B. FIG. 10A is a schematic configuration of a material steel plate for forming a welded pipe (material pipe) used as a material of the torsion beam 10B. FIG. 10B is a view of the welded tube before being formed into the torsion beam 10B, viewed along the axial direction, and FIG. 10C is a closed view of the torsion beam 10B viewed along the longitudinal direction. It is a figure which shows a cross section.
In addition, the upper figure shown to FIG. 10 (A) is the figure which looked at the material steel plate in the thickness direction, and the lower figure is the figure which looked at the material steel plate along the direction corresponding to the longitudinal direction of 10 A of torsion beams. It is.
Moreover, in FIG. 10, the code | symbol M10B has shown the material steel plate, and the code | symbol P10B has shown the welded pipe (metal material pipe | tube).

  The torsion beam 10B is formed, for example, by forming a welded pipe P10B from a material steel plate M10B and plastic processing the welded pipe P10B along its longitudinal direction.

  As shown in FIG. 10A, the material steel plate (metal material plate) M10 corresponds to, for example, a first wall portion corresponding to the first wall portion 110B (metal material) M110B and a second wall portion 120B. Corresponding to the second wall portion corresponding portion (metal material) M120B and the fatigue reducing thick portion 140B and formed between the first wall portion corresponding portion M110B and the second wall portion corresponding portion M120B, respectively. And a shape corresponding part (metal material) M140B.

In 3rd Embodiment, the 1st wall part corresponding | compatible part M120B is arrange | positioned at the both sides of material steel plate M10B.
The fatigue relaxation thick wall corresponding part M140B is formed over the entire length in the longitudinal direction of the material steel plate M10B, and the width of the fatigue relaxation thick wall corresponding part M140B (the length in the direction along the closed cross section of the torsion beam 10B) is It is formed so as to be gradually shorter (narrower) toward the center in the longitudinal direction corresponding to the length direction.

The welded pipe P10B is formed, for example, by rolling the material steel plate M10B in a direction perpendicular to the longitudinal direction of the torsion beam 10B as indicated by an arrow T in FIG.
The welded pipe P10B can be manufactured by applying press molding or roll forming, for example.

  In the third embodiment, as shown in FIG. 10B, the first tube wall portion P110B corresponding to the first wall portion 110B in the closed cross section of the torsion beam 10B is formed by rounding the material steel plate M10B. A seam portion (connecting portion) P10S is formed on the second pipe wall portion P120B corresponding to the second wall portion 120B in the closed cross section based on welding when forming the welded tube P10B.

The torsion beam 10B is formed by plastic processing of the welded pipe P10B along its longitudinal direction, and is formed by applying, for example, press molding, hydraulic press molding, hydroforming, or the like.
As a result, as shown in FIG. 10C, a torsion beam 10B having a closed cross section formed in a substantially V shape and having a seam portion (connection portion) 10S formed on the second wall portion 120B is formed. .

  According to the torsion beam 10 according to the third embodiment, since the seam portion 10S is formed along the longitudinal direction of the second wall portion 120, the processing on the first wall portion 110 can be performed efficiently.

<Fourth Embodiment>
Next, an example of a schematic configuration in the manufacturing process of the torsion beam 10C according to the fourth embodiment will be described with reference to FIG. In FIG. 11, the alternate long and two short dashes line indicates the thickness difference between the fatigue-relieving thick wall portion, the first wall portion, and the second wall portion.

FIG. 11 is a view for explaining an example of a schematic configuration in the manufacturing process of the torsion beam 10C. FIG. 11A is a schematic configuration of a material steel plate for forming a welded pipe (material pipe) used as a material of the torsion beam 10C. FIG. 11 (B) is a view of the welded tube before being formed into the torsion beam 10C along the axial direction, and FIG. 11 (C) is a closed view of the torsion beam 10C as viewed along the longitudinal direction. It is a figure which shows a cross section.
In addition, the upper figure shown to FIG. 11 (A) is the figure which looked at the material steel plate in the thickness direction, and the lower figure is the figure which looked at the material steel plate along the direction corresponding to the longitudinal direction of 10 A of torsion beams. It is.
Moreover, in FIG. 11, the code | symbol M10C has shown the material steel plate, and the code | symbol P10C has shown the welded pipe (metal material pipe | tube).

  The torsion beam 10C is formed, for example, by forming a welded pipe P10C from a material steel plate M10C and plastic processing the welded pipe P10C along its longitudinal direction.

  As shown in FIG. 11A, the material steel plate (metal material plate) M10C corresponds to, for example, a first wall portion corresponding portion (metal material) M110C corresponding to the first wall portion 110C and a second wall portion 120C. Corresponding to the second wall portion corresponding portion (metal material) M120C and the fatigue relieving thick wall shape portion (metal material) 140C and formed between the first wall portion corresponding portion M110C and the second wall portion corresponding portion M120C, respectively. And a fatigue relieving thick shape corresponding portion (metal material) M140C.

In 4th Embodiment, the 1st wall part corresponding | compatible part M120C is arrange | positioned at the both sides of material steel plate M10C.
Further, the fatigue relaxation thick wall corresponding portion M140C is formed over the entire length in the longitudinal direction of the material steel plate M10, and the width of the fatigue relaxation thick wall shape corresponding portion M140C (the length in the direction along the closed cross section of the torsion beam 10C) is the material steel plate M10C. The same width is formed over the entire length.

The welded pipe P10C is formed, for example, by rounding a material steel plate M10C in a direction perpendicular to the longitudinal direction of the torsion beam 10C as indicated by an arrow T in FIG.
The welded pipe P10C can be manufactured by applying press molding or roll forming, for example.

  In the fourth embodiment, as shown in FIG. 11B, the first tube wall portion P110C corresponding to the first wall portion 110C in the closed cross section of the torsion beam 10C is formed by rolling the material steel plate M10C, and the torsion beam 10C. A seam portion P10S is formed on the second pipe wall portion P120C corresponding to the second wall portion 120C in the closed cross section based on welding when forming the welded tube P10C.

The torsion beam 10C is formed by plastic processing of the welded pipe P10C along its longitudinal direction, and is formed by applying, for example, press molding, hydraulic press molding, hydroforming, or the like.
As a result, as shown in FIG. 11C, a torsion beam 10C having a closed cross section formed in a substantially V shape and having a seam portion 10S formed on the second wall portion 120C is formed.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention.

  For example, in the above-described embodiment, the case where the torsion beam 10 is formed in a substantially V-shape projecting downward when mounted on the vehicle body has been described. You may apply and it is good also as a structure which protrudes upwards with respect to a vehicle body.

  In the above embodiment, the case where the fatigue-relieving thick wall portions 140 are formed on the folded wall portions 130 on both the front side and the rear side of the vehicle body in the torsion beam 10 has been described. It is good also as a structure by which the fatigue | exhaustion relaxation thick part 140 was formed in the folding | turning wall part 130 of either side.

  Moreover, in the said embodiment, although the fatigue relaxation thick shape part 140 was demonstrated covering the full length of the fixed shape closed cross-section part 11, the longitudinal direction shape change part 12, and the attachment closed cross-section part 13, although it demonstrated. The fatigue-relieving thick wall portion 140 may be formed in an arbitrary range in the longitudinal direction of the torsion beam 10.

Moreover, in the said embodiment, in the direction along a closed cross section, the fatigue relaxation thick-walled shape part 140 is (2 * t1) from the folding | returning wall part 130 to the 1st wall part 110 side, and the 2nd wall part 120 side. Although the case where it is formed over the range of (2 × t2) has been described, the formation range in the direction along the closed cross section of the fatigue relaxation thick wall portion 140 is from the folded wall portion 130 toward the first wall portion 110 ( 2 × t1) and not limited to the range of (2 × t2) on the second wall 120 side, but can be arbitrarily set.
Further, the fatigue relieving thick wall portion 140 may be formed in a range smaller than the folded wall portion 130 in the direction along the closed cross section.

  In the above embodiment, the case where the width of the fatigue-reducing thick-walled portion 140 is appropriately deformed in the direction along the closed cross section and the case where the width is formed to the same width have been described. About the width | variety and shape of the fatigue relaxation thick wall shape part 140 in the direction in alignment with a cross section, it can set arbitrarily.

Moreover, in the said embodiment, plate | board thickness t3 of the fatigue relaxation thick part 140 is 5%-50% with respect to plate | board thickness t1 of the 1st wall part 110, and plate | board thickness t2 of the 2nd wall part 120. Although the case where the plate thickness is within the range has been described, the plate thickness t3 of the fatigue relaxation thick wall portion 140 can be arbitrarily set.
Further, in the above embodiment, the case where the plate thickness t1 of the first wall portion 110 and the plate thickness t2 of the second wall portion 120 are made uniform and the plate thickness t1 and the plate thickness t2 are equal is described. The plate thickness t1 of the first wall portion 110 may be different from the plate thickness t2 of the second wall portion 120, and either or both of the plate thickness t1 and the plate thickness t2 may not be uniform. Is also possible.

  Moreover, in the said embodiment, the metal tube used when forming the torsion beam 10 press-molds or roll-forms the steel plate (metal material board) M10 in which the fatigue | exhaustion relaxation thick-wall corresponding | compatible part M140 was formed, for example. Although the case where the formed welded pipe P10 is plastically processed has been described, the present invention can also be applied to a metal pipe formed by extrusion molding or pultrusion molding.

  Moreover, in the said embodiment, although the case where the metal tube used for manufacture of the torsion beam 10 was steel was demonstrated, you may apply to metals other than steel.

Hereinafter, the effect of the torsion beam according to the present invention will be described.
The effect was confirmed by conducting a torsional fatigue test on the torsion beams according to the present invention examples and comparative examples shown below.

<Invention Example>
The torsion beam according to the example of the present invention has a tensile strength of about 700 MPa, a length of 1460 mm, and a fatigue-relieving thick wall portion along the longitudinal direction. The maximum curvature of the fatigue-relieving thick wall shape portion is about 0.3 (1 / mm) in the constant shape closed cross-section portion and about 0.14 (1 / mm) in the longitudinal center portion of the longitudinal shape change portion.
(1) First, a material steel plate as shown in FIG. 12A is made of a high-strength steel having a tensile strength of 700 MPa corresponding to the material steel plate, a strip having a thickness of 3.4 mm and a strip having a thickness of 4.3 mm. (Shaded portions) were arranged and joined by laser welding.
(2) Next, this material steel plate is rolled by press forming and both side portions are joined by laser welding, and a differential thickness of a length of 1460 mm and an outer diameter of φ95.5 mm having a closed cross section as shown in FIG. A steel pipe was formed.
(3) Next, this differential steel pipe was press-molded to produce a torsion beam having a closed cross section as shown in FIG.

<Comparative example>
The torsion beam according to the comparative example has a constant tensile strength of about 700 MPa, a length of 1460 mm, and a plate thickness of 3.4 mm.
(1) First, a steel plate made of high tensile steel with a tensile strength of 700 MPa and having a thickness of 3.4 mm is rolled by press forming and both sides thereof are joined by laser welding to have a length of 1460 mm and an outer diameter of φ101.6. A steel pipe was formed.
The steel pipe used in the comparative example has an outer diameter of φ101.6 in order to match the roll rigidity with the inventive example, and the torsional rigidity of the comparative example is 7.08 × 10 ⁴ (Nmm / °), and the torsion of the inventive example. The rigidity is 7.12 × 10 ⁴ (Nmm / °).
(2) Next, this steel pipe was press-molded to produce a torsion beam.

In the torsional fatigue test, ± 20 ° displacement was repeatedly applied between both ends of the torsion beam to evaluate the maximum stress generated in the folded wall portion of the longitudinal shape change portion and the life due to metal fatigue.
The life due to metal fatigue was determined to have occurred when the reaction torque during the torsional fatigue test reached 80% or less of the torque at the start of the test.

As a result, it was confirmed that the maximum value of the stress generated in the folded wall portion of the torsion beam was 531 MPa for the inventive example and 616 MPa for the comparative example, and 14% lower for the inventive example.
Moreover, the life of the torsional fatigue test was 40000 times in the inventive example, and 20000 times in the comparative example, confirming that the life was doubled.

  According to the present invention, since the progress of metal fatigue can be suppressed by relaxing the stress concentration generated in the torsion beam, it is industrially applicable.

L10, L10A, L10B, L10C Distance between first wall and second wall L130A Distance between first wall side folding point M10, M10A, M10B, M10C Material steel plate (metal material plate)
P10, P10A, P10B, P10C Welded pipe (metal material pipe)
1 Torsion beam type rear suspension system (torsion beam type suspension system)
2 Torsion Beam Assy
5 Trailing arm (arm)
10, 10A, 10B, 10C Torsion beam 10S Seam part (connection part)
11 Constant shape closed cross section 12 Longitudinal shape change section 13 Mounting closed cross section 14 Mounting section 110, 110A, 110B, 110C First wall section 120, 120A, 120B, 120C Second wall section 130, 130A, 130B, 130C, 135 Folding wall 131, 131A, 131B, 131C First wall side folding point 132, 132A, 132B, 132C, 137 Second wall side folding point M110, M110A, M110B, M110C First wall corresponding part (metal material) )
M110, M110A, M110B, M110C Second wall corresponding part (metal material)
M140, M140A, M140B, M140C Fatigue mitigating thick-walled part (metal material)
M140, M140A, M140B, M140C Fatigue alleviation thick part 140, 140A, 140B, 140C Fatigue alleviation thick part

Claims (13)

In the torsion beam type suspension device, a pair of left and right arms in the vehicle body width direction are connected to both ends in the longitudinal direction, and a cross section perpendicular to the longitudinal direction projects upward or downward between the front end and the rear end in the longitudinal direction of the vehicle body A torsion beam having a substantially V-shaped or U-shaped closed cross section,
The substantially V-shaped or substantially U-shaped closed cross section is:
A first wall portion forming a concave outer surface in the closed cross section, a second wall portion forming a convex outer surface in the closed cross section, and both ends of the first wall portion and the second wall portion, and the first wall. A second wall corresponding to the first wall portion side turning point in the second wall portion and a first wall portion side turning point at which the portion is connected to the inward protrusion and the outward protrusion in the closed section A folding wall formed between the part side folding point and
A fatigue-relieving thick wall portion formed thicker than the first wall portion and the second wall portion on at least one of the folded wall portion on the front side of the vehicle body and the folded wall portion on the rear side of the vehicle body. A torsion beam characterized by comprising. The torsion beam according to claim 1,
The fatigue relieving thick wall portion is
A torsion beam characterized in that the torsion beam is formed over the entire length of the longitudinal shape changing portion in which the distance between the first wall portion and the second wall portion gradually increases as it approaches both ends from the center side in the longitudinal direction. The torsion beam according to claim 1,
The fatigue relieving thick wall portion is
The total length of the folded wall portion at least one of the folded wall portion on the front end side corresponding to the front direction of the vehicle body in the closed section and the folded wall portion on the rear end side corresponding to the rear direction of the vehicle body in the closed section. A torsion beam characterized by being formed over. The torsion beam according to claim 1,
The fatigue relieving thick wall portion is
It is formed over the entire length of the folded wall portion on the front end side corresponding to the front direction of the vehicle body in the closed section and the folded wall portion on the rear end side corresponding to the rear direction of the vehicle body in the closed section. Torsion beam. The torsion beam according to any one of claims 1 to 4,
When the thickness of the first wall portion is t1, and the thickness of the second wall portion is t2,
The fatigue relieving thick wall portion is
It is formed from the folded wall portion to the first wall portion side to a range of (2 × t1), and from the folded wall portion to the second wall portion side to a range of (2 × t2). Characteristic torsion beam. The torsion beam according to claim 5,
The fatigue relieving thick wall portion is
A torsion beam having a thickness of 5 to 50% with respect to a thickness t1 of the first wall portion and a thickness t2 of the second wall portion. The torsion beam according to any one of claims 1 to 6,
A torsion beam, wherein a width of the fatigue-relieving thick wall portion is gradually shortened from both ends in the longitudinal direction toward the center. The torsion beam according to any one of claims 1 to 7,
A torsion beam manufactured by plastic working a metal material tube in which the fatigue-relieving thick wall portion is formed by an extrusion process or a drawing process. The torsion beam according to any one of claims 1 to 7,
Corresponding to the metal material piece forming the fatigue relaxation thick wall shape corresponding part corresponding to the fatigue relaxation thick wall shape part, the metal material piece forming the first wall corresponding part corresponding to the first wall part, and the second wall part The metal material which forms the metal material piece which makes the 2nd wall part corresponding | compatible part to the surface direction, connects the boundary of these metal pieces by welding, rounds the metal material board, and connected the both ends by the connection part. A torsion beam manufactured by plastic processing of a tube. A torsion beam according to any one of claims 1 to 9,
The metal material formed by connecting the fatigue relaxation thick wall shape corresponding portion to the fatigue relaxation thick wall shape portion by welding the metal material pieces corresponding to the fatigue relaxation thick wall shape corresponding portion in the thickness direction. A torsion beam manufactured by plastic processing of a tube. The torsion beam according to any one of claims 1 to 10,
The torsion beam according to claim 1, wherein when the connecting portion is formed in the longitudinal direction, the connecting portion is formed on the second wall portion.   A torsion beam assembly comprising the torsion beam according to any one of claims 1 to 11.   A torsion beam type suspension device comprising the torsion beam assembly according to claim 12.

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