JP7441680B2 - Torsion beam suspension - Google Patents

Description

The present invention relates to a torsion beam suspension, and particularly to a torsion beam suspension mounted on a vehicle such as a four-wheeled vehicle.

In recent years, torsion beam suspensions, which have a small number of parts, a relatively simple structure, and are highly space efficient, have been increasingly adopted for suspension systems for vehicles such as four-wheeled vehicles, mainly in small-displacement vehicles. There is.

Therefore, such torsion beam suspensions are required to further increase their strength and rigidity while improving their productivity.

Under such circumstances, Patent Document 1 relates to a torsion beam suspension in which a welding hole is provided in at least one of the torsion beam and the reinforcing member for the purpose of reducing the stress generated at the joint between the torsion beam and the reinforcing member, This disclosure discloses a configuration in which an annular welded portion is formed around the entire circumference of the welding hole as the inner joint portion that is the jointed portion with the torsion beam.

International Publication 2016/121989

However, according to the study of the present inventor, in the configuration of the torsion beam suspension of Patent Document 1, for example, large loads of opposite phases in different vertical directions are applied to each wheel support portion of the left and right trailing arms. When the torsion beam is repeatedly applied, the degree of stress concentration on the annular welded portion of the torsion beam, which is repeatedly subjected to large torsional deformation, increases, and there is room for improvement in the strength and durability of the torsion beam.

The present invention was made after the above studies, and while ensuring good productivity and high strength, it reduces stress concentration at the welded part between the torsion beam and the trailing arm, and improves the strength and durability of the torsion beam. The purpose of the present invention is to provide a torsion beam type suspension that can improve performance.

In order to achieve the above object, in a first aspect of the present invention, the vehicle body extends in the longitudinal direction of the vehicle body on the left side in the width direction of the vehicle body, and is supported by the vehicle body at the front end side in the longitudinal direction, and the a left trailing arm that supports the left wheel on the rear end side in the longitudinal direction; and a left trailing arm that extends in the longitudinal direction on the right side in the width direction and is supported by the vehicle body on the front end side in the longitudinal direction, and It has a right trailing arm that supports the right wheel on the rear end side, a pair of walls that extend in the width direction and face each other in the longitudinal direction, and a communication wall that communicates between the pair of walls. , a torsion beam connecting the left trailing arm and the right trailing arm; and an internal area extending in the width direction on the left side and surrounded by the pair of walls of the torsion beam and the connecting wall. The torsion beam has a left inner attachment part attached to the torsion beam, a left outer attachment part attached to the left trailing arm, and a left intermediate connection part that communicates between the left inner attachment part and the left outer attachment part. and a left stiffener connecting the left trailing arm; a right inner mounting portion extending in the width direction on the right side and attached to the inner wall surface of the torsion beam in the inner region of the torsion beam; and the right trailing arm. and a right stiffener that connects the torsion beam and the right trailing arm, the right stiffener having a right outer mounting part that is attached to an outer wall surface of the frame, and a right intermediate communication part that communicates between the right inner mounting part and the right outer mounting part, and a right stiffener that connects the torsion beam and the right trailing arm. , one of the connecting wall part and the left inner mounting part has a left welding hole in which a welding part for welding them is provided, and one of the connecting wall part and the right inner mounting part has a right weld hole in which a welding portion for welding them is provided, and the connecting wall portion is juxtaposed on the right side with respect to the left weld hole so that the left stiffener and the torsion beam are welded together. a first juxtaposition hole in which a welding part is not provided, and a second juxtaposition hole in which a welding part, which is juxtaposed on the left side of the right welding hole and in which the right stiffener and the torsion beam are welded, is not provided; and the hole shape of the first juxtaposition hole is a shape that tapers toward the rightward direction, and the hole shape of the second juxtaposition hole is a shape that tapers toward the leftward direction. be .

In addition to the first aspect, the present invention provides that each hole shape in the juxtaposed portion of the left weld hole and the first juxtaposed hole is defined by a curve convex to the right in the width direction. The second aspect is that each hole shape in the juxtaposed portion of the right weld hole and the second juxtaposed hole has a shape defined by a curve convex to the left in the width direction. .

In addition to the first or second aspect, the present invention further provides a welding method in which the connecting wall portion is juxtaposed on the left side with respect to the left welding hole, and the left stiffener is welded to the connecting wall portion. a third juxtaposition hole in which no welding part is provided, and a fourth juxtaposition hole in which no welding part is provided, which is juxtaposed on the right side of the right welding hole and is welded to the connecting wall part. This is the third aspect.

In addition to the third aspect, the present invention provides that the area of the first juxtaposition hole is larger than the area of the third juxtaposition hole, and the area of the second juxtaposition hole is larger than the area of the fourth juxtaposition hole. The fourth aspect is that it is larger than .

In addition to the third or fourth aspect, the present invention provides that the shape of the third juxtaposition hole is tapered toward the left direction, and the shape of the fourth juxtaposition hole is as follows: The fifth aspect is that the shape is tapered toward the right.

According to the configuration in the first aspect of the present invention, one of the connecting wall part of the torsion beam and the left inner mounting part of the left stiffener has a left welding hole in which a welding part for welding them is provided, One of the connecting wall portion and the right stiffener of the torsion beam has a right welding hole in which a welding portion for welding them is provided, and the connecting wall portion is juxtaposed on the right side with respect to the left welding hole and is connected to the left stiffener. A first juxtaposed hole is not provided with a welding portion where the right stiffener and the torsion beam are welded, and a first juxtaposed hole is juxtaposed on the left side with respect to the right welding hole and is not provided with a welded portion where the right stiffener and the torsion beam are welded. By having two parallel holes, it is possible to maintain good productivity, high strength, etc., balance the stress on the weld between the torsion beam and the stiffener, reduce stress concentration in the weld, and improve the torsion beam. The durability of the suspension can be improved. In addition, since the shape of the first juxtaposed hole is tapered toward the right, and the shape of the second juxtaposed hole is tapered toward the left, the shape of the first juxtaposed hole is tapered toward the right. It is also possible to reduce stress concentration on the second juxtaposition hole and improve durability.

Further, according to the configuration according to the second aspect of the present invention, each hole shape in the juxtaposed portion of the left weld hole and the first juxtaposed hole has a shape defined by a curve convex to the right in the width direction. However, each hole shape in the juxtaposed portion of the right weld hole and the second juxtaposed hole has a shape defined by a curve convex to the left in the width direction, so that the gap between the torsion beam and the stiffener can be more reliably maintained. It is possible to reduce stress concentration in the welded area.

Further, according to the configuration according to the third aspect of the present invention, the connecting wall portion is further provided with a welding portion that is juxtaposed on the left side with respect to the left welding hole and where the left stiffener is welded to the connecting wall portion. By having a third juxtaposed hole that does not have a welding part and a fourth juxtaposed hole that is juxtaposed on the right side with respect to the right welding hole and does not have a welded part to be welded to the connecting wall part, the torsion beam has a higher degree of freedom. It is possible to balance the stress on the welded portion between the stiffener and the stiffener, especially the welded portion on the left and right juxtaposed portion sides.

Further, according to the configuration according to the fourth aspect of the present invention, the area of the first juxtaposition hole is larger than the area of the third juxtaposition hole, and the area of the second juxtaposition hole is larger than the area of the fourth juxtaposition hole. By doing so, it is possible to more reliably balance the stress on the welded portion between the torsion beam and the stiffener, particularly on the welded portion on the left and right juxtaposed portion sides.

Further, according to the configuration according to the fifth aspect of the present invention, the shape of the third juxtaposed hole is tapered toward the left, and the shape of the fourth juxtaposed hole is tapered toward the right. The tapered shape makes it possible to more reliably reduce stress concentration at the weld between the torsion beam and the stiffener, particularly at the weld at the left and right juxtaposed portions.

FIG. 1 is a partial plan view of a torsion beam suspension according to an embodiment of the present invention. It is a partial bottom view of the torsion beam type suspension in this embodiment. FIG. 3 is a partial rear view of the torsion beam suspension according to the present embodiment. FIG. 2 is an enlarged sectional view taken along the line AA in FIG. 1; FIG. 2 is an enlarged sectional view taken along the line BB in FIG. 1; FIG. 2 is an enlarged sectional view taken along the line CC in FIG. 1; FIG. 2 is an enlarged sectional view taken along the line DD in FIG. 1; The partially enlarged position of the torsion beam suspension in the modified example of this embodiment corresponds to FIG.

Hereinafter, the torsion beam suspension according to the embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5 as appropriate. Note that in the figure, the x-axis, y-axis, and z-axis form a three-axis orthogonal coordinate system. Further, the positive direction of the x-axis is the front direction of the vehicle body, the positive direction of the y-axis is the left direction of the vehicle body, and the positive direction of the z-axis is the upward direction of the vehicle body. Further, the x-axis direction is sometimes called the longitudinal direction, the y-axis direction is sometimes called the width direction, and the z-axis direction is sometimes called the up-down direction.

FIG. 1 is a partial plan view of the torsion beam suspension in this embodiment. FIG. 2 is a partial bottom view of the torsion beam suspension in this embodiment. FIG. 3 is a partial rear view of the torsion beam suspension in this embodiment. Further, FIGS. 4 to 7 are an enlarged sectional view taken along the line AA, enlarged sectional view taken along the line BB, enlarged sectional view taken along the line CC, and enlarged sectional view taken taken along the line DD in FIG. Note that although FIGS. 1 to 7 mainly show the components on the left side of the torsion beam suspension, the components on the right side of the torsion beam suspension have a configuration that is symmetrical with respect to the configuration on the left side. Further, in FIGS. 1 to 7, for convenience of explanation, typical components on the right side of the torsion beam suspension are indicated by parenthesized symbols.

First, the overall configuration of the torsion beam suspension 1 in this embodiment will be described in detail with reference to FIGS. 1 to 7.

The torsion beam suspension 1 is attached to a vehicle body such as a rear side frame of an automobile (not shown), and supports a suspension spring (hereinafter referred to as a spring), a suspension damper (hereinafter referred to as a damper), wheels, etc. .

Specifically, the torsion beam suspension 1 mainly includes a torsion beam 10, a pair of left and right trailing arms 20, 120, and a pair of left and right stiffeners 30, 130. Further, the torsion beam suspension 1 may include a pair of left and right spring seats 80 and 180, and a pair of left and right damper brackets 90 and 190.

The torsion beam 10 is typically a plate member made of a metal plate such as a steel plate that is formed into an upwardly convex shape by press forming or the like, and extends in the width direction, and has a pair of left and right trays at both ends thereof. The ring arms 20 and 120 are connected.

Specifically, in a longitudinal section cut along a plane parallel to the xz plane, the torsion beam 10 includes a front vertical wall section 11 and a rear vertical wall section 12 that face each other in the longitudinal direction, and a front vertical wall section 11 and a rear vertical wall section. It is provided with an upper wall part (connecting wall part) 13 that connects the upper end parts of each of the parts 12 in the longitudinal direction, and has an open cross-sectional shape that opens downward. Note that, if necessary, the torsion beam 10 may have an open cross-sectional shape that opens in a direction other than downward.

Here, the torsion beam suspension 1 typically has a shape that is basically symmetrical with respect to a central plane that is parallel to the xz plane and passes through the center in the width direction. Therefore, the torsion beam 10 has a shape that is bilaterally symmetrical with respect to the central plane. In other words, the left trailing arm 20 and the right trailing arm 120, the left stiffener 30 and the right stiffener 130, the left spring seat 80 and the right spring seat 180, and the left damper bracket 90 and right damper bracket 190 are respectively arranged in such a central plane. On the other hand, they have bilaterally symmetrical shapes and are arranged at bilaterally symmetrical positions. For convenience of explanation, the left trailing arm 20, 120, the left and right stiffeners 30, 130, the left and right spring seats 80, 180, and the left and right damper brackets 90, 190 will be described below. The left stiffener 30, the left spring seat 80, and the left damper bracket 90 will be representatively explained as examples.

The left trailing arm 20 is typically a tubular plate member made of a metal plate such as a steel plate with a closed cross-sectional shape, and extends in the longitudinal direction.

Specifically, in the left trailing arm 20, a collar member 100, typically made of a rolled metal plate such as a steel plate, is welded to the front end of the left trailing arm 20 by arc welding or the like to be supported by the vehicle body. A wheel support member 110 typically made of metal such as steel for supporting the wheel is welded by arc welding or the like with a portion thereof inserted. Note that, if necessary, the left trailing arm 20 may be constructed by preparing two components formed by forming a flat plate member made of a metal plate such as a steel plate into a substantially U-shaped longitudinal section, and facing each other in the width direction. It may be integrally welded by arc welding or the like, or it may be composed of a single pipe member made of metal such as a steel pipe. Further, the wheel support member 110 may be simply butted against the rear end portion of the left trailing arm 20 and welded by arc welding or the like.

The left stiffener 30 is typically a plate member made of a metal plate such as a steel plate formed by press forming or the like, and is arranged to extend in the width direction between the torsion beam 10 and the left trailing arm 20. At the same time, the left and right ends are welded to the torsion beam 10 and the left trailing arm 20 by arc welding or the like, thereby reinforcing and connecting them to each other.

Specifically, the left stiffener 30 includes a bottom wall portion 31 which is its main body, a front flange 32 erected upward from the front end of the bottom wall 31, and a front flange 32 erected upward from the rear end of the bottom wall 31. The front flange 32 and the rear flange 33 each extend in the width direction together with the bottom wall portion 31.

The left stiffener 30 further includes an outer attachment portion 40 that is a left end portion that is welded to the outer wall surface of the left trailing arm 20 outside the left end of the torsion beam 10. The outer mounting portion 40 has left end portions of each of a bottom wall portion 31, a front flange 32, and a rear flange 33, which are shaped to follow the outer contour shape of the left trailing arm 20. is welded to the outer wall surface of the left trailing arm 20 by arc welding or the like in a manner that it is in contact with the outer wall surface of the left trailing arm 20.

The left stiffener 30 further includes an inner attachment portion 50 at the right end that is internally welded to the torsion beam 10 . The inner mounting portion 50 is formed at the right end of the bottom wall portion 31 that is shaped to follow the shape of the inner wall surface of the upper wall portion 13 of the torsion beam 10, and the inner mounting portion 50 is formed to follow the shape of the inner wall surface of the front vertical wall 11 of the torsion beam 10. The right end portion of the front flange 32 is formed to have a shape, and the right end portion of the rear flange 33 is formed to follow the shape of the inner wall surface of the rear vertical wall 12 of the torsion beam 10.

In the left stiffener 30, the right end of the bottom wall 31, the right end of the front flange 32, and the right end of the rear flange 33 are closed cross-section parts S that cooperate with the inner wall surface of the torsion beam 10 to improve the strength and rigidity of the torsion beam 10. It is preferable to configure. Further, the right end portion of the front flange 32 and the right end portion of the rear flange 33 may have their vertical lengths reduced from the viewpoint of improving the formability of the left stiffener 30, and the strength of the left stiffener 30 and the bottom wall thereof may be reduced. If the welding strength of the portion 31 to the inner wall surface of the torsion beam 10 can be ensured, the vertical lengths of the right end of the front flange 32 and the right end of the rear flange 33 are set to zero, and the front flange 32 and the rear flange I don't care if 33 disappears.

Further, the left stiffener 30 further includes an intermediate communication portion 60 that connects the outer attachment portion 40 and the inner attachment portion 50. The intermediate connecting portion 60 is a diagonal portion that extends in the width direction while gradually rising from the outer attachment portion 40 toward the inner attachment portion 50. By having the intermediate connecting portion 60 take the form of such a diagonal portion, a sudden change in the vertical cross-sectional shape in the width direction of the torsion beam 10 can be suppressed, and stress concentration in the portion where the shape of the torsion beam 10 has changed can be reduced. It can be relaxed. Note that from the viewpoint of improving the strength and rigidity of the torsion beam 10 as well as improving the joint strength between the torsion beam 10 and the left trailing arm 20, the closed cross section defined by the torsion beam 10 and the left stiffener 30 in cooperation with each other. S may be set to extend from the inner attachment part 50 to the outer attachment part 40 via the intermediate communication part 60. In addition, in order for the left end edge of the torsion beam 10 and the left end edge of the left stiffener 30 to be welded to the left trailing arm 20 without creating unnecessary gaps, these left end edges must also work together to form a closed cross section. It is more preferable that the shape is maintained.

Here, as an example of the conditions for inputting a predetermined load to the torsion beam 10, the left trailing arm 20 and the right trailing arm 120 are each pivoted on the vehicle body, and the left trailing arm 20 and the right trailing arm 120 are There is an example in which reverse-phase vertical loads having different vertical directions are applied once or multiple times to each wheel support member 110 portion of the right trailing arm 120, and in such a case, the torsion beam 10 and the left stiffener The degree of stress concentration is the highest at the welded part where 30 is welded. From the viewpoint of reducing stress concentration in the welded portion, weld holes 34 (left stiffener 30 In the case of the right stiffener 130, a left weld hole is provided, and in the right stiffener 130, a right weld hole is provided. The welding hole 34 is typically arranged in the center of the bottom wall portion 31 in the longitudinal direction, and is a round hole having a circular hole shape when viewed from above. The welding hole is opened in such a manner that the upper wall surface of the portion of the bottom wall portion 31 that reaches the periphery of the welding hole 34 and surrounds the welding hole 34 is in contact with the inner wall surface (lower wall surface) of the upper wall portion 13 of the torsion beam 10. 34, the bottom wall portion 31 and the upper wall portion 13 exposed to the welding hole 34 are welded by arc welding or the like to form a welded portion (not shown). are doing. From the viewpoint of reducing stress concentration in the welded portion, a concave portion may be further provided in the portion of the upper wall portion 13 facing the weld hole 34, which is recessed downward. In this case, from the viewpoint of water drainage, etc., it is preferable that an intermediate hole 14 be provided vertically passing through the center of the concave portion. In addition, as the welding hole 34, not only a circular hole but also an elongated hole such as an ellipse having a long axis in a direction parallel to the longitudinal direction, width direction, or a direction crossing these may be used. . Further, the welded portion of the weld hole 34 may be formed by plug welding so that not only the periphery of the hole but also the entire hole is closed. Further, if necessary, the right end of the bottom wall 31 of the left stiffener 30, the right end of the front flange 32, and the right end of the rear flange 33 may be connected to the inner wall surface of the upper wall 13 and the front vertical wall of the corresponding torsion beam 10, respectively. 11 and the rear vertical wall 12, and may be welded thereto by arc welding or the like.

Furthermore, from the viewpoint of reducing stress concentration at the weld hole 34 by maintaining stress balance with the weld portion provided for the weld hole 34, the upper wall portion 13 of the torsion beam 10 is The inner hole 15 (left stiffener) is arranged on the right side and is formed by perforating the upper wall portion 13 in the vertical direction. It is preferable to have a first juxtaposed hole for the 30 weld holes and a second juxtaposed hole for the weld hole of the right stiffener 130. The inner hole 15 typically has a centroid C2 on a straight line L1 extending in the width direction through the centroid C1 of the welding hole 34 when viewed from above, and has a hole shape that is symmetrical about the straight line L1. have Specifically, from the viewpoint of ensuring the degree of freedom for stress balance and reliably reducing stress concentration at the welded part provided for the welding hole 34, each of the areas where the welding hole 34 and the inner hole 15 are juxtaposed is In other words, the hole shape of the right side portion of the welding hole 34 and the hole shape of the left side portion (outer shape portion) 15a of the inner hole 15 intersect with the straight line L1 while following each other when viewed from above. It is preferable that each of the grooves has a portion defined by a curved line that extends to the right in the width direction and is convex to the right in the width direction. From the viewpoint of simplifying the setting of each hole shape in the juxtaposed portion of the weld hole 34 and the inner hole 15, the hole shape of the weld hole 34 is set to a circular hole, and the weld hole 34 It has a curvature equal to the curvature of the circular hole shape, that is, it is a curve concentric with the circular hole shape of the welding hole 34, and the outer shape portion 15a in the juxtaposed part of the inner hole 15 juxtaposed with the welding hole 34. The hole shape may be defined. In addition, depending on the need for stress reduction, etc., the outer shape portion 15a in the juxtaposed portion of the inner hole 15 juxtaposed with the weld hole 34 may be curved with a curve having a smaller curvature than the curvature of the circular hole shape of the weld hole 34. The hole shape may be defined.

In addition, from the viewpoint of reliably reducing stress concentration at the welded portion provided for the weld hole 34, the inner shape of the inner hole 15 on the right side opposite to the juxtaposed portion of the weld hole 34 and the inner hole 15 is The hole shape of the portion 15b is flattened in the longitudinal direction and tapered toward the right (a shape in which the distance between two points on the circumference of the hole facing each other in the longitudinal direction gradually decreases). preferable. With respect to the inner hole 15, it is preferable that the right end portion of the left stiffener 30 is disposed within the inner hole 15 from the viewpoint of water drainage, etc. A gap G exists between the inner shape portion 15b of the inner hole 15 and the inner shape portion 15b of the inner hole 15. Note that the left stiffener 30 may be provided with a through hole 35 that corresponds to the inner hole 15 and can be used for positioning or the like.

Furthermore, from the viewpoint of reducing stress concentration at the weld hole 34 by maintaining stress balance between the inner hole 15 and the welded portion provided for the weld hole 34, the upper wall portion 13 of the torsion beam 10 is arranged on the left side of the welding hole 34 and is formed by perforating the upper wall part 13 in the vertical direction, and is provided with a welding part where the left stiffener 30 is welded to the torsion beam 10. It is preferable to have an outer hole 16 (a third juxtaposition hole for the weld hole of the left stiffener 30 and a fourth juxtaposition hole for the weld hole of the right stiffener 130) without having an outside hole 16 (a third juxtaposition hole for the weld hole of the left stiffener 30 and a fourth juxtaposition hole for the weld hole of the right stiffener 130). The outer hole 16 typically has a centroid C3 on the straight line L1 when viewed from above, and has a hole shape that is symmetrical about the straight line L1. Specifically, from the viewpoint of ensuring the degree of freedom for stress balance and reliably reducing stress concentration at the welded part provided for the weld hole 34, the juxtaposed portion of the weld hole 34 and the outer hole 16 is The hole shape of the outer shape portion 16a of the outer hole 16 on the left side on the opposite side is flattened in the longitudinal direction and tapered toward the left (the distance between two points on the hole periphery facing each other in the longitudinal direction is It is preferable that the shape is gradually reduced. Note that the hole shape of the inner shape portion 16b on the right side of the outer hole 16 in the juxtaposed portion with the weld hole 34 is a straight line extending in the longitudinal direction, taking into consideration the hole shape of the weld hole 34 and the hole shape of the inner hole 15. Alternatively, it is preferable to have a portion defined by a curved line convex to the left in the width direction. Further, when the welding hole 34 is circular in top view, the hole shape of the inner shape portion 16b may be defined by a curve having a curvature equal to or larger than the curvature of the hole shape.

Further, for convenience in maintaining stress balance between the welding hole 34 and the welded portion, the area of the inner hole 15 is preferably set larger than the area of the outer hole 16 when viewed from above. . Furthermore, from the viewpoint of securing the required welding area while maintaining stress balance between the welding part provided for the welding hole 34 in this way, the area of the welding hole 34 is smaller than the inner side when viewed from above. It is preferable to set the area smaller than the area of the hole 15 and larger than the area of the outer hole 16.

The left spring seat 80 is typically a plate member made of a metal plate such as a steel plate formed by press forming or the like, and is welded to the torsion beam 10 and the left trailing arm 20 by arc welding or the like. The lower end of the can be supported freely.

Specifically, the left spring seat 80 includes a bottom wall portion 81 that is parallel to the xy plane, a convex portion 82 that is convex upward from the center of the bottom wall portion 81, and passes through the convex portion 82 in the vertical direction. A through hole 83 is provided. Further, the bottom wall portion 81 may have one or more attachment holes 84 provided by boring the bottom wall portion 81 in the vertical direction.

The left spring seat 80 further includes an inclined wall section 85 that stands upright from the front right end of the bottom wall section 81 while tilting upward, and an inclined wall section 85 that stands upright from the rear end of the bottom wall section 81 and is flat. A curved rear wall portion 86 is provided that is convex rearward when viewed.

In the left spring seat 80, the front end of the inclined wall portion 85 is shaped to follow the shape of the outer wall surface of the rear vertical wall 12 of the torsion beam 10. The thus formed portion is welded by arc welding or the like while it is in contact with the outer wall surface of the rear vertical wall 12. This inclined wall portion 85 improves the rigidity of the rear vertical wall portion 12 of the torsion beam 10, and from the viewpoint of improving the supporting strength of the left stiffener 30 and the left spring seat 80, respectively. It is preferable that the left stiffener 30 be placed in parallel with the left stiffener 30 with 12 in between. Further, the left end portion of the rear wall portion 86 is shaped to follow the shape of the outer wall surface of the left trailing arm 20. The thus formed portion is welded by arc welding or the like while it is in contact with the outer wall surface of the left trailing arm 20.

Further, the left spring seat 80 further includes a flange 87 extending over the inclined wall portion 85 and the rear wall portion 86 and having the upper end thereof bent outward. The flange 87 can be omitted if the left spring seat 80 has sufficient strength, such as because it is thick.

The damper bracket 90 is typically a plate member made of a metal plate such as a steel plate formed by press forming or the like, and is welded to the rear wall portion 86 of the left spring seat 80 by arc welding or the like. , which supports the lower end of the damper.

Specifically, the damper bracket 90 includes a bottom wall portion 91 parallel to the xy plane, a left side wall portion 92 erected upward from both ends of the bottom wall portion 91 in the width direction, and a right side wall portion 92 facing each other in the width direction. A wall portion 93 is provided.

In the damper bracket 90, the left side wall part 92 and the right side wall part 93 extend below the lower surface of the bottom wall part 81 of the left spring seat 80 and are welded thereto by arc welding or the like. Although not shown, the left side wall part 92 and the right side wall part 93 are capable of accommodating and supporting the lower end of the damper therebetween, and are formed by perforating them in the width direction. It has a corresponding left through hole and a right through hole that oppose each other. Note that a nut member (not shown) may be provided in one of these through holes.

The damper bracket 90 further includes a flange 94 in which the upper end of the left side wall 92 is bent to the left, and a flange 95 in which the upper end of the right side wall 93 is bent to the right. The left end of the flange 94 is welded by arc welding or the like so as to be in contact with the outer wall surface of the left trailing arm 20, and the front end of the flange 94 is in contact with the rear wall 86 of the left spring seat 80. It is welded by arc welding or the like. Further, the front end portion of the flange 95 is welded by arc welding or the like so as to be in contact with the rear wall portion 86 of the left spring seat 80.

In the torsion beam suspension 1 having the above configuration, a vehicle body attachment part B1 is set as a part to be attached to the vehicle body, and a wheel side attachment part to which wheel side members are attached is provided as an attachment part for attaching various external force applying parts. A spring attachment portion S1 to which a spring is attached, and a damper attachment portion D1 to which a damper is attached are set.

Specifically, the vehicle body attachment portion B1 is arranged to correspond to the collar member 100 provided at the front end of the left trailing arm 20. In the vehicle body mounting portion A1, the front end of the left trailing arm 20 is fastened with a fastening member (not shown), typically a bolt, via a bushing member (not shown) press-fitted into the collar member 100. By doing so, it is attached to the vehicle body while being pivotally supported.

The wheel-side attachment portion W1 is arranged to correspond to the wheel support member 110 provided at the rear end portion of the left trailing arm 20. Typically, a bearing member (not shown) is attached to the wheel-side attachment portion W1 by being fastened to the wheel support member 110 using a fastening member such as a bolt.

The spring mounting portion S1 is arranged corresponding to the bottom wall portion 81 of the left spring seat 80. In the spring mounting portion S1, a spring (not shown) is mounted by being placed on the top of the bottom wall portion 81 of the left spring seat 80. In addition, in order to reduce the friction noise of the spring, etc., a disk-shaped elastic member may be placed in the plurality of attachment holes 84 provided in the bottom wall portion 81, and the spring may be placed on top of the disk-shaped elastic member.

The damper mounting portion D1 is arranged corresponding to the left side wall portion 92 and the right side wall portion 93 of the damper bracket 90. In the damper mounting portion D1, the lower end portion of the damper (not shown) is inserted through the left through hole and the right through hole provided in the left side wall portion 92 and the right side wall portion 93, respectively. Generally, it is attached by being fastened with a fastening member such as a bolt.

In the torsion beam 10 that has been described so far, welding holes 34 are provided in the bottom wall portion 31 of each of the left stiffener 30 and the right stiffener 130, and an intermediate hole 14 is provided in the top wall portion 13 of the torsion beam 10. As shown in FIG. 8, a welding hole 14' is provided in the upper wall 13 of the torsion beam 10, and the welding hole 14' is welded from the bottom wall 31 of each of the left stiffener 30 and the right stiffener 130. A configuration may be adopted in which an intermediate hole 34' is provided in and welding is performed from the upper wall portion 13 side.

In the configuration of this embodiment described above, one of the connecting wall portion 13 of the torsion beam 10 and the left inner mounting portion 50 of the left stiffener 30 has a left welding hole 34 in which a welding portion for welding them is provided. , one of the connecting wall part 13 and the right stiffener 130 of the torsion beam 10 has a right welding hole 34 in which a welding part for welding them is provided, and the connecting wall part 13 is connected to the left welding hole 34. A first juxtaposition hole 15 is juxtaposed on the right side and does not have a welding part where the left stiffener 30 and the torsion beam 10 are welded, and a first juxtaposition hole 15 is juxtaposed on the left side with respect to the right weld hole and the right stiffener 130 and the torsion beam 10 are welded together. By having the second juxtaposition hole 15 in which no welded part is provided, the welded part between the torsion beam 10 and the stiffeners 30 and 130 is secured while ensuring good productivity and high strength. By maintaining stress balance, it is possible to reduce stress concentration at the welded portion and improve the durability of the torsion beam suspension 1.

Further, in the configuration of this embodiment, the connecting wall portion 13 of the torsion beam 10 is further provided with a welding portion that is juxtaposed on the left side with respect to the left welding hole 34 and where the left stiffener 30 is welded to the connecting wall portion 13. A third juxtaposition hole 16 that is never disposed, and a fourth juxtaposition hole 16 that is juxtaposed on the right side with respect to the right welding hole 34 and where a welding part where the right stiffener 130 is welded to the connecting wall part 13 is not provided. By having a higher degree of freedom, it is possible to balance the stress on the welded portion between the torsion beam 10 and the stiffeners 30 and 130, particularly on the left and right juxtaposed portions.

The present invention is not limited to the types, shapes, arrangements, numbers, etc. of the members, and the gist of the invention may be modified by appropriately replacing the constituent elements with those having equivalent effects. Of course, changes can be made as appropriate without departing from the above.

As described above, the present invention reduces stress concentration at the weld between the torsion beam and the trailing arm while ensuring good productivity and high strength, thereby improving the strength and durability of the torsion beam. Since the present invention can provide a torsion beam type suspension that can perform various functions, it is expected that it can be widely applied to the field of torsion beam type suspensions of moving bodies such as vehicles due to its versatile and universal characteristics.

1... Torsion beam type suspension 10... Torsion beam 11... Front vertical wall part 12... Rear vertical wall part 13... Upper wall part 14, 34'... Intermediate hole 15... Inner hole 15a... Outer shape part 15b... Inner shape part 16... Outer hole 16a...Outer shape part 16b...Inner shape part 20, 120...Trailing arm 30, 130...Stiffener 31...Bottom wall part 32...Front flange 33...Rear flange 34, 14'...Welding hole 35...Through hole 40...External mounting Part 50...Inner attachment part 60...Intermediate communication part 80, 180...Spring seat 81...Bottom wall part 82...Convex part 83...Through hole 84...Attachment hole 85...Slope wall part 86...Rear wall part 87...Flange 90, 190 …Damper bracket 91…Bottom wall portion 92…Left wall portion 93…Right side wall portion 94…Flange 95…Flange 100…Collar member 110…Wheel support member S…Closed section G…Gap portion B1…Vehicle body attachment portion S1…Spring Mounting part D1...Damper mounting part W1...Wheel side mounting part

Claims (5)

a left trailing arm that extends in the longitudinal direction of the vehicle body on the left side in the width direction of the vehicle body, is supported by the vehicle body on the front end side in the longitudinal direction, and supports a left wheel on the rear end side in the longitudinal direction;
a right trailing arm that extends in the longitudinal direction on the right side in the width direction, is supported by the vehicle body on the front end side in the longitudinal direction, and supports a right wheel on the rear end side in the longitudinal direction;
A pair of walls extending in the width direction and facing each other in the longitudinal direction, and a communication wall connecting the pair of walls, and connecting the left trailing arm and the right trailing arm. torsion beam and
a left inner mounting part that extends in the width direction on the left side and is attached to the torsion beam in an internal area surrounded by the pair of walls of the torsion beam and the communication wall; and a left inner attachment part that is attached to the left trailing arm. a left stiffener that connects the torsion beam and the left trailing arm by having a left outer mounting part, and a left intermediate communication part that communicates between the left inner mounting part and the left outer mounting part;
a right inner attachment part extending in the width direction on the right side and attached to the inner wall surface of the torsion beam in the inner region of the torsion beam; a right outer attachment part attached to the outer wall surface of the right trailing arm; a right stiffener that connects the torsion beam and the right trailing arm, having a right intermediate connecting portion that communicates between the right inner attachment portion and the right outer attachment portion;
Equipped with
One of the connecting wall part and the left inner mounting part has a left welding hole in which a welding part for welding them is provided,
One of the connecting wall part and the right inner mounting part has a right welding hole in which a welding part for welding them is provided,
The communication wall portion includes a first juxtaposition hole that is juxtaposed on the right side with respect to the left weld hole and is not provided with a welding portion where the left stiffener and the torsion beam are welded, and a first juxtaposition hole that is juxtaposed on the right side with respect to the left weld hole, and a first juxtaposition hole that is not provided with a welding part where the left stiffener and the torsion beam are welded, and a second juxtaposition hole that is juxtaposed on the left side and is not provided with a welding part where the right stiffener and the torsion beam are welded ;
The first juxtaposition hole has a shape that tapers toward the right, and the second juxtaposition hole has a shape that tapers toward the left. Each hole shape in the juxtaposed portion of the left weld hole and the first juxtaposed hole has a shape defined by a curve convex to the right in the width direction,
2. The torsion beam suspension according to claim 1, wherein each hole shape in the juxtaposed portion of the right weld hole and the second juxtaposition hole has a shape defined by a curve convex to the left in the width direction. The connecting wall further includes a third juxtaposition hole that is juxtaposed on the left side with respect to the left welding hole and is not provided with a welding part where the left stiffener is welded to the connecting wall, and the right welding hole. 3. The torsion beam type suspension according to claim 1 , further comprising a fourth juxtaposed hole juxtaposed on the right side of the fourth juxtaposition hole in which no welding part is welded to the connecting wall part. 4. The torsion beam suspension according to claim 3 , wherein the area of the first juxtaposed hole is larger than the area of the third juxtaposed hole, and the area of the second juxtaposed hole is larger than the area of the fourth juxtaposed hole. The hole shape of the third juxtaposition hole is a shape that tapers toward the left direction,
5. The torsion beam suspension according to claim 3 , wherein the fourth parallel hole has a shape that tapers toward the right.

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