JP2013256142A - Torsion beam joining structure of torsion beam type suspension - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torsion beam joining structure of a torsion beam type suspension capable of improving productivity and increasing the joining strength of a torsion beam.SOLUTION: Thick-walled sections 3a are formed on open edges of a torsion beam 3 as a joining structure to each trailing arm of the torsion beam 3 of a torsion beam type suspension having a pair of right and left trailing arms arranged on both sides of a vehicle in the longitudinal direction, and the torsion beam 3 having an open section shape which is arranged in the vehicle width direction to connect the trailing arms. The torsion beam 3 is formed of an extrusion of a light alloy or a casting of a light alloy. The trailing arms are formed of castings of a light alloy, and a fitting projecting part 2c to be fitted in a joining end of the torsion beam 3 is formed inside thereof.

Description

  The present invention relates to a structure for joining a torsion beam constituting a torsion beam suspension to a trailing arm.

  In recent years, there has been an increasing demand for weight reduction for vehicles in order to improve fuel efficiency. As a suspension, a torsion beam suspension is used which is advantageous in terms of space saving, cost reduction, weight reduction, etc. due to the small number of parts. The number of vehicles is increasing.

  Such a torsion beam suspension includes a pair of left and right trailing arms arranged in the front-rear direction on both sides of the vehicle, and a torsion beam having an open cross-sectional shape arranged in the vehicle width direction and connecting the trailing arms. The vertical displacement (reverse vertical movement) between the left and right wheels supported by each trailing arm is controlled by the torsional reaction force of the torsion beam.

  By the way, the left and right ends of the torsion beam are joined to the left and right trailing arms by welding, but the torsion beam moves to the trailing arm along with the movement of the trailing arm during movement of the vehicle (movement from the wheels). Stress concentrates at the joints. For this reason, a high joining strength is required for the trailing arm.

  In general, a torsion beam is formed in an U-shaped or V-shaped open cross-sectional shape. If this cross-sectional shape continues over the entire length in the longitudinal direction of the torsion beam, the circumferential length of welding at the left and right end portions thereof is It becomes shorter and the required bonding strength cannot be ensured.

  Therefore, in Patent Document 1, the cross-sectional shape of the central portion in the longitudinal direction of the torsion beam is U-shaped or V-shaped, the left and right joint end surfaces are annular cross-sectional shapes, and the center portion and the left and right joint end surfaces are between. The structure which makes a site | part the cross-sectional change part from which a cross-sectional shape changes continuously is proposed.

  On the other hand, a conventional steel plate torsion beam has a large plate thickness and a large weight so as to withstand twisting and bending deformation. As means for reducing the thickness by securing the torsional rigidity and bending rigidity necessary for the torsion beam, for example, Patent Documents 2 and 3 disclose an open end of a U-shaped or V-shaped torsion beam. There has been proposed a configuration in which a loop portion having an edge folded inward or outward is formed and the end edges of the loop portion are joined by welding.

JP 2011-046232 A JP-A-5-278424 JP 2005-029155 A

  However, as proposed in Patent Document 1, it is difficult to provide a plurality of portions having different cross-sectional shapes in the torsion beam, and there is a problem that the manufacturing cost increases.

  In the configurations proposed in Patent Documents 2 and 3, when joining the left and right ends of the torsion beam to each trailing arm, it is difficult to weld the loop portion of the torsion beam, so the welding is interrupted and stress concentration occurs. There is a problem that it becomes easy to do.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a torsion beam joining structure for a torsion beam suspension capable of improving productivity and joining strength of a torsion beam.

  In order to achieve the above object, the invention according to claim 1 is a cross-sectional shape that connects a pair of left and right trailing arms arranged in the front-rear direction on both sides of the vehicle and the trailing arms arranged in the vehicle width direction. A torsion beam suspension comprising a torsion beam is characterized in that a thick part is formed at the open end edge of the torsion beam as a joining structure of the torsion beam to each trailing arm.

  According to a second aspect of the present invention, in the first aspect of the present invention, the torsion beam is composed of a light alloy extruded material or a light alloy casting.

  According to a third aspect of the present invention, in the second aspect of the present invention, the trailing arm is formed of a light alloy casting, and a fitting convex portion is formed on the inner side of the trailing arm so as to be fitted into the joining end portion of the torsion beam. It is characterized by that.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the joining end portion of the torsion beam and the fitting convex portion of the trailing arm are joined by friction stir welding.

  According to the first aspect of the present invention, since the thick portion is formed on the open end edge of the torsion beam and the open end edge is reinforced by the thick portion, the open end edge of the torsion beam is connected to the trailing arm from the outside of the torsion beam. It can be joined by welding or the like, and the productivity of the torsion beam suspension is increased. And the rigidity of the torsion beam can be increased by the thick part of the torsion beam.

  In addition, since there is no unjoined portion at the joint between the torsion beam and the trailing arm, the joint strength between the two is increased, and the entire torsion beam can be used for torsion and bending. The weight can be reduced while increasing the rigidity and bending rigidity.

  According to the second aspect of the present invention, since the torsion beam is made of a light alloy extruded material or a light alloy casting, a thick portion can be easily formed on the open end edge of the torsion beam. Moreover, a thick part can be easily formed in places other than the open end edge of the torsion beam.

  According to the third aspect of the present invention, the torsion beam can be positioned by the fitting projection formed on the trailing arm, so that the productivity of the torsion beam type suspension is enhanced.

  Furthermore, the fitting strength between the torsion beam and the trailing arm is increased by fitting the fitting convex portion of the trailing arm into the joining end portion of the torsion beam. Since the torsion beam and the trailing arm are joined together by light alloys, they can be easily joined together, and the weight of the torsion beam suspension can be reduced.

  According to the fourth aspect of the present invention, it is possible to strongly bond even the thick part of the torsion beam by friction stir welding (FSW), and high-strength bonding with a deep penetration depth is possible. In addition, since the fitting convex part of the trailing arm is inserted into the back side (inside) of the torsion beam, the fitting convex part functions as a load receiver for friction stir welding, and the torsion beam and the trailing member are not provided separately. The arm can be joined by friction stir welding, and the productivity of the torsion beam suspension is enhanced.

It is a perspective view of a torsion beam type suspension provided with the junction structure concerning the present invention. FIG. 2 is a partial perspective view of a torsion beam corresponding to a cross section taken along line AA in FIG. 1. It is a cross-sectional view of a torsion beam. It is a perspective view of a trailing arm. It is the A section enlarged detail drawing of FIG. FIG. 2 is a cutaway perspective view showing a joint structure between a torsion beam and a trailing arm according to the present invention corresponding to a cross section taken along line BB in FIG. 1. It is a figure similar to FIG. 6 which shows the modification of this invention. It is a figure similar to FIG. 6 which shows the modification of this invention. It is a figure similar to FIG. 6 which shows the modification of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a perspective view of a torsion beam type suspension 1 having a joint structure according to the present invention. The torsion beam type suspension 1 shown in FIG. 1 includes a pair of left and right trailing arms 2 arranged in the longitudinal direction on both sides of a vehicle, And a torsion beam 3 having an open cross-sectional shape for connecting the trailing arm 2.

  In the present embodiment, the left and right trailing arms 2 are integrally formed in a T shape in plan view by casting using a light alloy such as an aluminum alloy. The trailing arm 2 is arranged so that its T-shaped horizontal bar is arranged along the vehicle front-rear direction, and at one end portion (front end portion) in the front-rear direction so as to penetrate in the vehicle width direction. A hole 4 is formed, and is supported by the vehicle body through a bush (not shown) fitted in the circular hole 4 so as to be swingable up and down.

  A circular hole 5 for attaching a wheel support member such as a spindle (not shown) is formed at the other end (rear end) in the front-rear direction of each trailing arm 2, and is attached to the circular hole 5. A wheel (not shown) is attached via a wheel support member. Furthermore, a channel-shaped attachment portion 2a for attaching a lower end of a shock absorber (not shown) and a spring receiver 2b for receiving a lower end of a coil spring (not shown) are formed at the other end portion (rear end portion) in the front-rear direction. Yes. Specifically, a shock absorber mounting portion 2a is formed on the vehicle rear side of the rear end portion of the trailing arm 2 from the circular hole 5 and in the vehicle width direction on the center side of the vehicle, and the shock absorber mounting portion 2a. A spring receiver 2b is formed on the vehicle front side and in the vehicle width direction on the center side of the vehicle.

  A tapered connecting portion 2A that protrudes horizontally toward the center side in the vehicle width direction is integrally formed on the inner side (center side of the vehicle in the vehicle width direction) of the left and right trailing arms 2. Has been. The front edge of the spring receiver 2b is connected to the rear edge of the connecting portion 2A. That is, the spring receiver 2b is connected to the side edge of the trailing end of the trailing arm 2 and the rear edge of the connecting portion 2A, and efficiently transmits a load from a coil spring (not shown) to the rear end and the connecting portion 2A. The rigidity of each trailing arm 2 is improved by connecting the side edge of the trailing end of the trailing arm 2 and the rear edge of the connecting portion 2A. Since the spring receiver 2b is not connected to the torsion beam 3 and does not affect the torsional rigidity of the torsion beam 3, adjustment of the torsional rigidity of the torsion beam 3 (adjustment of the rigidity of the suspension) is facilitated. . The left and right end portions of the torsion beam 3 are joined to the front end of each connecting portion 2A, and the left and right trailing arms 2 are connected by a torsion beam 3 arranged in the vehicle width direction.

  In the torsion beam type suspension 1 configured as described above, when the left and right wheels rotatably supported at one end (rear end) in the longitudinal direction of the trailing arm 2 move up and down while the vehicle is running, The behavior is absorbed by a coil spring (not shown), and the vertical movement of the wheel is attenuated by a shock absorber. The relative displacement in the vertical direction generated between the left and right wheels acts to twist the torsion beam 3 and acts to twist the trailing arm 2. It should be noted that the portion of the torsion beam 3 where the maximum stress is generated by this twisting is the left and right end portions that become the junction of the torsion beam 3.

  By the way, in the present embodiment, the torsion beam 3 is made of a light alloy extruded material such as an aluminum alloy or a cast product of light alloy, and the left and right ends of the left and right trailing arms 2 are formed by the joining structure according to the present invention. It is joined to the tip of the connecting part 2A. Embodiments of the joint structure according to the present invention will be described below. In the following embodiment, only one of the left and right joint structures of the torsion beam 3 is shown and described, but the other joint structure is also the same, and thus illustration and description thereof are omitted.

  2 to 6 are views showing the joint structure according to the embodiment of the present invention. FIG. 2 is a partial perspective view of a torsion beam corresponding to the cross section along line AA of FIG. 1, and FIG. FIG. 4 is a perspective view of the trailing arm corresponding to the cross section taken along line BB in FIG. 1, FIG. 5 is an enlarged detail view of part A in FIG. 4, and FIG. 6 shows the joining structure of the torsion beam and the trailing arm. FIG.

  In the present embodiment, an extruded material of aluminum alloy (A6061) is used for the torsion beam 3, and as shown in FIGS. 2 and 3, the torsion beam 3 is integrally formed in an inverted U-shaped cross section with its lower part open. Has been. Specifically, the upper portion of the torsion beam 3 is formed in an arc shape having an outer diameter R of the cross section, and the lower portion is configured by a flat surface that is smoothly continuous with the upper portion of the arc shape. It is used. Then, on the inner surface of the lower lower edge (vertical open end edge) of the planar lower portion of the torsion beam 3, a convex shape protruding inside the torsion beam 3 is formed, and the thick part 3a having a predetermined height is integrally formed. Is formed.

  On the other hand, as shown in FIGS. 4 and 5, the leading end of the connecting portion 2 </ b> A of the trailing arm 2 enters the inside of the joining end at one end in the longitudinal direction of the torsion beam 3 and fits into the joining end of the torsion beam 3. Thus, the fitting convex part 2c formed in a shape matching the inner surface shape of the torsion beam 3 is integrally formed. That is, the fitting convex portion 2 c formed at the distal end portion of the connecting portion 2 </ b> A of the trailing arm 2 is formed in a shape along the inner surface shape of the torsion beam 3, and the fitting convex portion 2 c of the trailing arm 2 is formed. A fitting recess 2c1 into which the thick part 3a of the torsion beam 3 is fitted is formed at a place where the thick part 3a of the left and right torsion beams 3 is fitted. In the present embodiment, a casting of aluminum alloy (AC4CH) is used for the trailing arm 2.

  Thus, a fitting convex portion 2c formed at the tip of the connecting portion 2A of the trailing arm 2 as shown in FIG. It joins by friction stir welding (FSW) also including the location of the part 3a. Here, the friction stir welding (FSW) means that the metal is fluidized by inserting (pushing) the rotating body, which is a welding tool, into the joined portion of the joined member while rotating, thereby joining the joined members together. It is the joining method to join.

  As described above, in the joining structure according to the present embodiment, as a reinforcing structure of the open end edge of the torsion beam 3, the thick portion 3a is formed at the opening end instead of the loop portion that folds the opening end inward or outward. Therefore, the torsion beam 3 and the trailing arm 2 can be joined from the outside to the edge of the opening by friction stir welding, and the productivity of the torsion beam suspension 1 can be improved. Moreover, the effect that the rigidity of the torsion beam 3 is enhanced by the thick portion 3a of the torsion beam 3 is also obtained. In the present embodiment, since the torsion beam 3 is made of an aluminum alloy extruded material, the thick portion 3a can be easily formed on the open end edge of the torsion beam 3. In addition, the same thick part can be easily formed in places other than the open end edge of the torsion beam 3.

  In the present embodiment, the fitting convex portion 2c formed at the tip of the connecting portion 2A of the trailing arm 2 is fitted into the right and left joint ends of the torsion beam 3, so that the left and right end joints of the torsion beam 3 are joined. Since the fitting convex portion 2c is fitted inside the portion, the force is transmitted between the torsion beam 3 and the trailing arm 2 with respect to the force in the direction of twisting the torsion beam 3 and the force in the direction of twisting the trailing arm 2. The fitting convex portion 2c can also bear the load, and the durability of the torsion beam 3 can be improved by reducing the burden on the left and right joint portions. For this, the engagement between the fitting recess 2c1 of the fitting projection 2c of the trailing arm 2 and the convex shape (thick portion 3a) of the torsion beam 3 also acts effectively. As shown in FIG. 5, the base end portion of the fitting convex portion 2c (the root portion opposite to the tip portion and connected to the connecting portion 2A) has a height substantially equal to the thickness of the torsion beam 3. A step is formed, and the end surface of the torsion beam 3 is abutted against the step surface. The torsion beam 3 can be positioned in the width direction by this butting and the fitting convex portion 2 c of the trailing arm 2, which also increases the productivity of the torsion beam suspension 1.

  Furthermore, according to the joint structure according to the present embodiment, since the unjoined portion does not occur in the joint portion between the torsion beam 3 and the trailing arm 2, the joint strength between the torsion beam 3 and the trailing arm 2 is increased. The entire torsion beam 3 can be used for twisting and bending, and the torsion beam suspension 1 can be reduced in weight while increasing the torsional rigidity and bending rigidity.

  Further, the fitting strength between the torsion beam 3 and the trailing arm 2 is increased by fitting the fitting convex portion 2 c of the trailing arm 2 into the joining end of the torsion beam 3. Since the torsion beam and the trailing arm are joined together by light alloys, they can be easily joined together, and the weight of the torsion beam suspension can be reduced.

  Further, in the present embodiment, the joining end portion of the torsion beam 3 and the fitting convex portion 2c of the trailing arm 2 that are fitted to each other are joined by friction stir welding (FSW). 3a can be strongly bonded, and high strength bonding with a deep penetration depth is possible. In this case, since the fitting convex portion 2c of the trailing arm 2 enters the back side (inside) of the torsion beam 3, the fitting convex portion 2c functions as a load receiver for friction stir welding, and the load receiver is separately provided. Without being provided, the torsion beam 3 and the trailing arm 2 can be joined by friction stir welding, which also increases the productivity of the torsion beam suspension 1.

  Regarding the joining, in the state where the end portion of the torsion beam 3 is fitted to the fitting convex portion 2c of the trailing arm 2, there is a difference in the vicinity of the joining portion of the trailing arm 2 due to the step at the base end portion of the fitting convex portion 2c. The outer surface and the outer surface of the torsion beam 3 are set so as to be a substantially continuous surface, and the friction stir welding (FSW) is performed between the step portion of the trailing arm 2 and the end surface portion (left and right end portions) of the torsion beam 3. The part where and are abutted is joined. Specifically, the entire end surface of the torsion beam 3 including the end surface of the thick portion 3a is joined to the trailing arm 2. In addition to the joining of the butted portions, the rotating body with respect to the portion of the torsion beam 3 in which the fitting projection 2c of the trailing arm 2 is inserted (the portion where the torsion beam 3 and the fitting projection 2c overlap) The (joining tool) may be inserted and joined at a depth equal to or greater than the thickness of the thick portion 3a.

  By the way, in the above embodiment, although the fitting convex part 2c of the trailing arm 2 was comprised as a solid thing, as shown in FIG. 7, the circular hole 6 may be formed in the fitting convex part 2c, As shown in FIG. 8 and FIG. 9, it is possible to reduce the weight of the trailing arm 2 by forming the long grooves 7, 8 that are open at the bottom so that the fitting convex portion 2 c is thinned. Thus, it was confirmed that even if the fitting convex portion 2c of the trailing arm 2 was thinned by the circular hole 6 or the long grooves 7 and 8, there was no change in the bonding strength between the torsion beam 3 and the trailing arm 2.

  Further, in the above embodiment, the convex thick portion 3a protruding inside the torsion beam 3 is formed. However, the thick portion 3a may be bulged outward, and of course, the inner side and the outer side. The thick part 3a may be formed by bulging in both. If the thick portion 3a is formed only by bulging outward, the shape of the fitting convex portion 2c of the trailing arm 2 becomes a simple shape, and the productivity can be further improved.

DESCRIPTION OF SYMBOLS 1 Torsion beam type suspension 2 Trailing arm 2A Connecting part of trailing arm 2c Fitting convex part of trailing arm 3 Torsion beam 3a Thick part of torsion beam

Claims (4)

Each of the trailing of the torsion beam of a torsion beam suspension comprising a pair of left and right trailing arms arranged in the front-rear direction on both sides of the vehicle, and an open cross-sectional torsion beam arranged in the vehicle width direction and connecting the trailing arm. A joining structure to the arm,
A torsion beam joining structure for a torsion beam suspension, characterized in that a thick portion is formed at an open end edge of the torsion beam.   2. The torsion beam joining structure for a torsion beam type suspension according to claim 1, wherein the torsion beam is made of a light alloy extruded material or a light alloy casting.   3. The torsion beam of a torsion beam type suspension according to claim 2, wherein the trailing arm is made of a light alloy casting, and a fitting convex portion is formed on the inside of the trailing arm to be fitted into a joining end portion of the torsion beam. Joining structure. 4. The torsion beam joining structure for a torsion beam suspension according to claim 3, wherein the joining end portion of the torsion beam and the fitting convex portion of the trailing arm are joined by friction stir welding.

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