TRAILING ARM

Abstract

A trailing arm which is connected to a vehicle body and a knuckle supporting a rear wheel includes: a pair of left and right resinous plate members having a hollow portion and a metallic inner plate which is joined to the left and right plate members in the hollow portion.

Description

CROSS-REFERENCE TO RELATED APPLICATION

Priority is claimed on Japanese Patent Application No. 2021-047590, filed Mar. 22, 2021, the content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a trailing arm.

Description of Related Art

Conventionally, a trailing arm constituting a suspension of a vehicle is known (for example, see Japanese Unexamined Patent Application, First Publication No. H10-315730).

SUMMARY OF THE INVENTION

In the above-described structure, since the trailing arm is required to have high strength and rigidity, the trailing arm is made of metal and is formed in a large size, which causes an increase in weight.

An aspect of the present invention provides a trailing arm that achieves both strength and rigidity assurance and weight reduction.

(1) A trailing arm according to an aspect of the present invention is connected to a vehicle body and a knuckle supporting a vehicle wheel and includes a resinous outer portion which has a hollow portion and a metallic inner portion which is joined to the outer portion in the hollow portion.

With such a configuration of the aspect (1), since the metallic inner portion and the resinous outer portion are joined in the hollow portion, it is possible to achieve both strength and rigidity assurance and weight reduction of the trailing arm.

(2) In the configuration of the aspect (1), the outer portion may be consisted by at least two members.

With such a configuration of the aspect (2), it is possible to easily join the outer portion to the inner portion by sandwiching the inner portion from both sides by at least two outer portions.

(3) In the configuration of the aspect (1) or (2), the inner portion may be consisted by a press-processed plate material.

With such a configuration of the aspect (3), it is possible to easily process the inner portion by press working.

(4) In the configuration of any one of the aspects (1) to (3), the inner portion may include a vehicle body side inner connection portion which is connected to the vehicle body and a knuckle side inner connection portion which is connected to the knuckle.

With such a configuration of the aspect (4), since the vehicle body and the knuckle are connected by the metallic inner portion, it is possible to easily assure the strength and rigidity of the trailing arm.

(5) In the configuration of any one of the aspects (1) to (4), the outer portion may include a vehicle body side outer connection portion which is connected to the vehicle body, a knuckle side outer connection portion which is connected to the knuckle, and a convex portion or a concave portion which is disposed between the vehicle body side outer connection portion and the knuckle side outer connection portion.

With such a configuration of the aspect (5), it is possible to increase the rigidity between the vehicle body side outer connection portion and the knuckle side outer connection portion in the outer part by the convex portion or the concave portion.

(6) In the configuration of the aspect (4), the inner portion may include a vehicle body side inner through-hole and the vehicle body side inner connection portion having a tubular shape may be formed by burring work performed on an edge portion of the vehicle body side inner through-hole.

With such a configuration of the aspect (6), the vehicle body side inner connection portion which is formed by burring work can be a seat surface for fixing a bush to a connection portion between the vehicle body and the trailing arm. Therefore, a bush fixing member such as a collar is not required.

(7) In the configuration of any one of the aspects (1) to (6), the outer portion may include a rib portion which is formed on a surface on a side opposite to the hollow portion.

With such a configuration of the aspect (7), since the rib portion is provided, it is possible to increase the rigidity of the trailing arm.

(8) In the configuration of the aspect (7), the rib portion may be composed of a plurality of ribs and the plurality of ribs may be arranged in a lattice shape.

With such a configuration of the aspect (8), since the ribs are arranged in a lattice shape, it is possible to further increase the rigidity of the trailing arm.

(9) In the configuration of any one of the aspects (1) to (8), the outer portion may contain reinforcing fibers.

With such a configuration of the aspect (9), since the outer portion contains reinforcing fibers, it is possible to further increase the strength of the trailing arm.

(10) In the configuration of the aspect (7) or (8), the outer portion may include a vehicle body side outer connection portion which is connected to the vehicle body, a knuckle side outer connection portion which is connected to the knuckle, and a convex portion or a concave portion which is disposed between the vehicle body side outer connection portion and the knuckle side outer connection portion, and the rib portion may be formed along a shape of the convex portion or the concave portion of the outer portion.

With such a configuration of the aspect (10), since the height of the rib portion can be increased at the portion with the convex portion or the concave portion, it is possible to more effectively improve the rigidity of the trailing arm.

(11) In the configuration of any one of the aspects (2) to (10), the outer portion may include a sandwiching portion which is formed on an inside of a peripheral edge portion so as to sandwich the inner portion from both sides.

With such a configuration of the aspect (11), it is possible to easily position the outer portions to both sides of the inner portion by the sandwiching portion. Further, it is possible to increase the joint strength between the inner portion and the outer portion. According to an aspect of the present invention, since the resinous outer portion and the metallic inner portion are joined in the hollow portion of the outer portion, it is possible to achieve both strength and rigidity assurance and weight reduction of the trailing arm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a left side view illustrating a rear suspension of an embodiment of the present invention.

FIG. 2 is a plan view of the rear suspension.

FIG. 3 is a perspective view of a trailing arm provided in the rear suspension.

FIG. 4 is a left side view of an arm body of the trailing arm.

FIG. 5 is a perspective view of the arm body.

FIG. 6 is a perspective view illustrating a configuration of the arm body.

FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. 1.

FIG. 8 is a cross-sectional view taken along the line VIII-VIII of FIG. 1.

FIG. 9 is a cross-sectional view taken along the line IX-IX of FIG. 4.

FIG. 10 is a cross-sectional view taken along the line X-X of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Unless otherwise specified, the directions such as front, rear, left, and right in the following description are the same as the directions in the vehicle equipped with a trailing arm 5 described below. Further, an arrow FR indicating the front side of the vehicle, an arrow LH indicating the left side of the vehicle, and an arrow UP indicating the upper side of the vehicle are shown in the appropriate place of the figure used in the following description.

<Trailing Arm Type Suspension>

FIG. 1 is a left side view illustrating a rear suspension 2. FIG. 2 is a plan view of the rear suspension 2.

As shown in FIGS. 1 and 2, a vehicle body 1 of the vehicle includes a pair of left and right rear frames 1A at the rear portion and the rear suspension (so-called trailing arm type suspension) 2 is attached to the left and right rear frames 1A.

A trailing arm 5 which is attached to the lower portion of the rear frame 1A, a knuckle 6 which is fixed to the rear end portion of the trailing arm 5, and a hub 7 which is rotatably supported by the knuckle 6 is provided on each of the left and right sides of the rear suspension 2. A vehicle wheel (rear wheel (not shown)) is attached to the left and right hubs 7.

The rear suspension 2 includes various arms which connect the vehicle body 1 and the knuckle 6 and extend in the vehicle width direction, a vibration damping mechanism, an elastic member (for example, a spring), a stabilizer, and the like in addition to the above-described members and suspends the left and right rear wheels with respect to the vehicle body 1.

The trailing arm 5 includes an arm body 11 which is formed in a plate shape and a rubber bush 12 which is fixed to the front end portion of the arm body 11. The trailing arm 5 extends backward from the vehicle body 1 and connects the vehicle body 1 and the knuckle 6.

The arm body 11 is disposed so that the longitudinal direction of the cross-section of the rear portion is directed in the up and down direction. The arm body 11 includes a knuckle connection portion 11f which is provided at the rear end portion of the arm body 11 and fastens and connects a trailing arm connection portion 6a provided at the front end portion of the knuckle 6 by a plurality of bolts 14.

Both end portions of the rubber bush 12 in the vehicle width direction are respectively fastened to the rear frame 1A by a bolt 15 and a nut 16.

The knuckle 6 includes the trailing arm connection portion 6a which is integrally provided with the front end portion of the knuckle and an axle 6b which is integrally provided with the rear portion thereof. The hub 7 is rotatably supported by the axle 6b. A vehicle wheel (rear wheel) (not shown) and a brake disc 8 constituting a disc brake are attached to the hub 7 of the axle 6b. Additionally, the axle 6b may be supported by the knuckle 6 to be rotatable and the hub 7 may be supported by the axle 6b not to be rotatable.

<Trailing Arm>

FIG. 3 is a perspective view of the trailing arm 5.

As shown in FIG. 3, the arm body 11 is integrally provided with a vertical extension portion 11b, which extends in the up and down direction and of which an upper portion is provided with a bush mounting hole 11 a for mounting a rubber bush 12, and a rear extension portion 11c which extends backward from the lower portion of the vertical extension portion 11b.

One side portion (left side portion) of the arm body 11 is provided with a pair of left and right resinous rib portions 13 and 17 which are composed of a plurality of ribs 13a such that the plurality of ribs 13a are arranged in a lattice shape. These rib portions 13 and 17 increase the rigidity of the arm body 11. Since the plurality of ribs 13a are arranged in a lattice shape, it is possible to further increase the rigidity of the arm body 11. The knuckle connection portion 11f to be connected to the knuckle 6 (see FIG. 2) is provided at the rear end portion of the arm body 11. The knuckle connection portion 11f is provided with a pair of upper and lower metallic collars 21 each allowing a bolt 14 (see FIG. 2) to pass therethrough.

The rubber bush 12 includes a pair of left and right pivot brackets 35e which protrudes toward both sides in the vehicle width direction from the vertical extension portion 11b of the arm body 11. The pivot bracket 35e has a bolt insertion hole 35h formed at a flat portion of each end portion and is fastened to the rear frame 1A (see FIG. 1) by the bolt 15 (see FIG. 2) passing through the bolt insertion hole 35h and the nut 16 (see FIG. 2).

<Arm Body>

FIG. 4 is a left side view of the arm body 11.

As shown in FIG. 4, the arm body 11 is formed such that a pair of left and right resinous plate members (outer portions) 25 is disposed on the inside of the rib portions 13 and 17 (the rib portion 17 is shown in FIG. 3) in the vehicle width direction. The plate member 25 is integrally provided with a vertical extension plate portion 25a which is formed at the front portion to extend in the up and down direction and a rear extension plate portion 25b which extends backward from the lower portion of the vertical extension plate portion 25a. The plate member 25 has a plate concave portion (concave portion) 25d which has an L shape in the side view and is formed on the inside of a peripheral edge portion 25c so as to extend from the vertical extension plate portion 25a to the rear extension plate portion 25b.

The plate concave portion 25d is recessed to a uniform depth from an outer surface (a surface on the side opposite to the hollow portion) 25e of the plate member 25 (that is, a surface on the outside of the vehicle width direction) toward an inner surface 25f (that is, a surface on the inside of the vehicle width direction (see FIG. 9)) of the plate member 25. The plate concave portion 25d includes a bottom surface 25g and an annular side surface 25h which rises from the peripheral edge of the bottom surface 25g.

Each rib 13a of the rib portion 13 is formed to be in close contact with an outer surface 25e of the plate member 25 and the bottom surface 25g and the side surface 25h of the plate concave portion 25d.

FIG. 5 is a perspective view of the arm body 11.

As shown in FIGS. 4 and 5, an end surface 13b on the outside of the vehicle width direction of each rib 13a of the rib portion 13 is located on the same plane. Therefore, in each rib 13a, the height from the portion in contact with the plate member 25 to the end surface 13b is higher in the portion with the plate concave portion 25d of the plate member 25 than the portion without the plate concave portion 25d. In this way, when the plate concave portion 25d is provided in the plate member 25 and the height of each rib 13a of the rib portion 13 formed on the outside of the vehicle width direction of the plate member 25 becomes higher in the plate concave portion 25d, the rigidity of the arm body 11 can be increased.

As shown in FIGS. 3 and 5, in a lower portion of each of a front surface 11j and a rear surface 11k of the vertical extension portion 11b and an upper surface 11m, a lower surface 11n, and a rear surface 11p of the rear extension portion 11c, the peripheral edge portion 25c of the plate member 25 is exposed to the outside. Further, in the rear surface 11p of the arm body 11, a rear edge portion 26g of an inner plate (inner portion) 26 to be described later is exposed to the outside.

FIG. 6 is a perspective view illustrating a configuration of the arm body 11.

As shown in FIG. 6, a metallic inner plate 26 is disposed at the center portion of the arm body 11 (see FIG. 3) in the vehicle width direction and outer members 27 and 28 are respectively disposed on both sides of the inner plate 26 in the vehicle width direction.

The outer member 27 includes the plate member 25 that is crimped to the inner plate 26 from one side (left side) of the vehicle width direction and the rib portion 13 which is injection-molded on the outer surface 25e of the plate member 25. The outer member 28 includes the plate member 25 that is crimped to the inner plate 26 from the other side (right side) of the vehicle width direction and the rib portion 17 which is injection-molded on the outer surface 25e (see FIG. 7) of the plate member 25.

The inner plate 26 and the left and right plate members 25 are joined (specifically, heat-crimped) in a pair of molding dies and the rib portions 13 and 17 are injection-molded on each plate member 25 in the same pair of molding dies.

The inner plate 26 is made of a pressed plate material and is integrally provided with a vertical extension plate portion 26a which is formed at the front portion of the inner plate 26 so as to extend in the up and down direction and a rear extension plate portion 26b which extends backward from the lower portion of the vertical extension plate portion 26a.

The vertical extension plate portion 26a includes a vehicle body side inner through-hole 26c. The edge portion of the vehicle body side inner through-hole 26c is subjected to burring work. Accordingly, a cylindrical rising portion 26d is formed to protrude toward one side (right side) of the vehicle width direction. The rising portion 26d constitutes a part of the bush mounting hole 11a (see FIG. 5) of the arm body 11 (see FIG. 5). The rubber bush 12 (see FIG. 3) is fitted to the rising portion 26d similarly to other portions of the bush mounting hole 11a. The rising portion 26d forms a seat surface for fixing the rubber bush 12 to the arm body 11.

A knuckle side inner connection portion 26h which is connected to the knuckle 6 (see FIG. 2) is provided at the rear end portion of the rear extension plate portion 26b of the inner plate 26. The knuckle side inner connection portion 26h includes a pair of upper and lower knuckle side inner through-holes 26e. The collars 21 (see FIG. 5) are respectively inserted through the pair of knuckle side inner through-holes 26e.

The plate member 25 is made of a fiber reinforced resin containing, for example, carbon fiber as the reinforcing fiber, and the strength is increased. In addition to carbon fiber, the reinforcing fiber may be a fiber reinforced resin containing glass fiber, boron fiber, polyamide fiber, Kevlar (registered trademark) fiber, Izanas (registered trademark), and Zylon (registered trademark).

The plate member 25 is formed in advance with another molding die before the arm body 11 is molded with the molding die. The upper portion of the vertical extension plate portion 25a is integrally provided with a vehicle body side outer connection portion 25t which is formed in an annular shape and is connected to the knuckle 6 (see FIG. 2). The vehicle body side outer connection portion 25t includes a vehicle body side outer through-hole 25j.

The inner diameter of the vehicle body side outer through-hole 25j is formed to be larger than that of the vehicle body side inner through-hole 26c of the inner plate 26 in order to form the bush mounting hole 11a.

The rear end portion of the rear extension plate portion 25b is integrally provided with a pair of upper and lower outer tubular portions (knuckle side outer connection portions) 25k. The pair of outer tubular portions 25k is formed to protrude toward the inner plate 26 and the collar 21 is inserted into each of them to be crimped.

The plate member 25 includes an upper flange portion 25m and a lower flange portion 25n which are bent toward the inner plate 26 over the edge portion of the vertical extension plate portion 25a and the edge portion of the rear extension plate portion 25b. The upper flange portion 25m and the lower flange portion 25n constitute a part of the peripheral edge portion 25c of the plate member 25. In this way, when the upper flange portion 25m and the lower flange portion 25n are provided, the rigidity of the pair of plate members 25 can be increased.

The rib portion 13 includes a one-side edge portion 13c which is an edge portion of the bush mounting hole 11a on one side (left side) of the vehicle width direction, a peripheral edge portion 13d which excludes the edge portion 13c of the bush mounting hole 11a, and a plurality of ribs 13a which are formed on the inside of the one-side edge portion 13c and the peripheral edge portion 13d.

The rib portion 17 includes the other-side edge portion 17c which is the edge portion of the bush mounting hole 11a on the other side (right side) of the vehicle width direction, the peripheral edge portion 13d, and the plurality of ribs 13a which are formed on the inside of the other-side edge portion 17c and the peripheral edge portion 13d. The rib portion 17 is different from the rib portion 13 only in the other-side edge portion 17c due to the arrangement of the rising portion (vehicle body side inner connection portion) 26d of the inner plate 26.

The rib portions 13 and 17 include a collar arrangement portion 13e which is formed at the rear end portion so that a part of the pair of collars 21 (see FIG. 5) is disposed.

<Vehicle Body Side Attachment Structure of Trailing Arm>

FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. 1.

As shown in FIG. 7, the rubber bush 12 includes an outer tube 31, an inner tube 32 which is disposed in the outer tube 31, and a rubber 33 which is disposed between the outer tube 31 and the inner tube 32. The outer tube 31 is press-fitted into the bush mounting hole 11a of the arm body 11. The inner tube 32 includes an internal side inner tube 34 to which the rubber 33 is attached and an external side outer tube 35 which is attached to both end portions of the internal side inner tube 34.

The external side outer tube 35 is a member in which an upper half body 35a and a lower half body 35b are combined. The upper half body 35a has an upper bracket 35c formed at both end portions of the upper half body 35a and the lower half body 35b has a lower bracket 35d formed at both end portions of the upper half body 35a.

The upper bracket 35c and the lower bracket 35d constitute the pivot bracket 35e.

The upper bracket 35c includes an upper through-hole 35f which penetrates vertically and the lower bracket 35d includes a lower through-hole 35g which penetrates vertically. The upper through-hole 35f and the lower through-hole 35g form the bolt insertion hole 35h of the pivot bracket 35e.

The left and right pivot brackets 35e are respectively fastened to the left and right rear frames 1A of the vehicle body 1 by the bolt 15 passing through the bolt insertion hole 35h and the nut 16.

<Knuckle Side Attachment Structure of Trailing Arm>

FIG. 8 is a cross-sectional view taken along the line VIII-VIII of FIG. 1.

As shown in FIG. 8, each outer tubular portion 25k of the left and right plate members 25 includes a collar insertion hole 25p through which each collar 21 is inserted in order to attach the arm body 11 to the knuckle 6 (see FIG. 2).

Each collar insertion hole 25p of the left and right plate members 25 and the knuckle side inner through-hole 26e of the inner plate 26 form a collar through-hole 11r into which the collar 21 is inserted and crimped. As described above, the collar through-hole 11r is formed over the left and right plate members 25 and the inner plate 26 and is provided in the knuckle connection portion 11f.

The collar 21 includes a first collar 21A which is disposed in the arm body 11 on one side (left side) of the vehicle width direction and a second collar 21B which is disposed in the arm body 11 on the other side (right side) of the vehicle width direction. The first collar 21A is inserted and crimped into the collar insertion hole 25p of the plate member 25 on one side (left side) of the vehicle width direction. The second collar 21B is inserted and crimped into the collar insertion hole 25p of the plate member 25 on the other side (right side) of the vehicle width direction and one side (left side) of the vehicle width direction.

Additionally, the first collar 21A may be inserted and crimped into the collar insertion hole 25p of the plate member 25 on one side (left side) of the vehicle width direction and the other side (right side) of the vehicle width direction. Further, the second collar 21B may be inserted and crimped only into the collar insertion hole 25p of the plate member 25 on the other side (right side) of the vehicle width direction.

The first collar 21A is integrally provided with a first tubular portion 21c and a flange portion 21d extending radially outward from one end portion of the first tubular portion 21c. The other end portion of the first tubular portion 21c is integrally provided with a convex portion 21e.

A first corner portion 21f formed by the first tubular portion 21c and the flange portion 21d is provided with a first curved surface portion 21g formed on a concave curved surface. The first curved surface portion 21g is formed in an annular shape along the outer peripheral surfaces of the first tubular portion 21c and the flange portion 21d and the cross-section of the first curved surface portion 21g is formed in a concave arc shape.

The second collar 21B is integrally provided with a second tubular portion 21m and a flange portion 21d extending radially outward from one end portion of the second tubular portion 21m. The other end portion of the second tubular portion 21m is provided with a concave portion 21n. The first tubular portion 21c of the first collar 21A and the second tubular portion 21m of the second collar 21B constitute a tubular portion 21v of the collar 21. Since the tubular portion 21v is inserted into the collar through-hole 11r, the deviation between the inner plate 26 and the left and right plate members 25 (specifically, the deviation in the extension direction of the inner plate 6) is suppressed when the left and right plate members 25 are joined to the inner plate 26.

A second corner portion 21p formed by the second tubular portion 21m and the flange portion 21d is provided with a second curved surface portion 21q formed on a concave curved surface. The second curved surface portion 21q is formed in an annular shape along the outer peripheral surfaces of the second tubular portion 21m and the flange portion 21d and the cross-section of the second curved surface portion 21q is formed in a concave arc shape. The second curved surface portion 21q is formed in the same shape as the first curved surface portion 21g.

An end surface 21u of the flange portion 21d of the first collar 21A is disposed to be flush with an end surface 13b of the rib portion 13. A side surface 6c of the trailing arm connection portion 6a of the knuckle 6 comes into contact with the end surface 21u.

The end surface 21u of the flange portion 21d of the second collar 21B is flush with the end surface 13b of the rib portion 17. A washer 37 through which the bolt 14 passes comes into contact with the end surface 21u.

The first tubular portion 21c and the second tubular portion 21m have the same outer diameter and inner diameter. The outer diameter of the flange portion 21d is larger than those of the first tubular portion 21c and the second tubular portion 21m.

The convex portion 21e of the first collar 21A and the concave portion 21n of the second collar 21B has mating-connection. Due to the mating-connection, the first tubular portion 21c and the second tubular portion 21m can be coaxially arranged with high accuracy.

The first tubular portion 21c of the first collar 21A includes a first bolt insertion hole 21r through which the bolt 14 passes. The second tubular portion 21m of the second collar 21B includes a second bolt insertion hole 21s through which the bolt 14 passes. The first bolt insertion hole 21r and the second bolt insertion hole 21s constitute a bolt insertion hole 21t.

The second collar 21B is inserted and crimped into the knuckle side inner through-hole 26e of the inner plate 26. The tip end of each outer tubular portion 25k of the left and right plate members 25 is crimped to the edge portion of the knuckle side inner through-hole 26e of the inner plate 26. Additionally, the first collar 21A may be inserted and crimped into the knuckle side inner through-hole 26e or both the first collar 21A and the second collar 21B may be inserted and crimped thereinto.

A convex through-hole side curved surface portion 25r is formed on the edge portion 25q of the collar insertion hole 25p of the plate member 25. The through-hole side curved surface portion 25r is formed in an annular shape along the inner peripheral surface of the collar insertion hole 25p and the cross-section of the through-hole side curved surface portion 25r is formed in a convex arc shape.

The first curved surface portion 21g and the second curved surface portion 21q which are formed as concave curved surfaces in the collar 21 and each through-hole side curved surface portion 25r formed as a convex curved surface in the plate member 25 have the same curvature and each portion is evenly in contact with each other. Thus, the contact area between the first curved surface portion 21g and the second curved surface portion 21q with respect to each through-hole side curved surface portion 25r can be increased. Accordingly, it is possible to reduce stress concentration by improving the adhesion at the contact portion between the first corner portion 21f and the second corner portion 21p of the collar 21 and the edge portion 25q of the collar insertion hole 25p of the plate member 25.

In FIGS. 6 to 8, the inner plate 26 includes the rising portion 26d which is connected to the vehicle body 1 through the rubber bush 12 and the knuckle side inner connection portion 26h which is connected to the knuckle 6 through the collar 21 and the bolt 14. The metallic inner plate 26 connects the vehicle body 1 and the knuckle 6.

The plate member 25 includes the vehicle body side outer connection portion 25t which is connected to the vehicle body 1 via a resin material 43 and the rubber bush 12 and the outer tubular portion 25k which is connected to the knuckle 6 via the collar 21 and the bolt 14. Further, the plate member 25 is disposed between the vehicle body side outer connection portion 25t and the outer tubular portion 25k. The plate member 25 includes the plate concave portion 25d which increases the rigidity between the vehicle body side outer connection portion 25t and the outer tubular portion 25k in the plate member 25.

<Arm Body Cross-Section Structure>

FIG. 9 is a cross-sectional view taken along the line IX-IX of FIG. 4.

As shown in FIG. 9, a hollow portion 38 is formed on the inside of the pair of left and right plate members 25 and the inner plate 26 is disposed and joined to the hollow portion 38. The hollow portion 38 is divided into left and right by the inner plate 26. That is, a space 41 is formed in the inner plate 26 on one side (left side) of the vehicle width direction and a space 42 is formed in the inner plate 26 on the other side (right side) of the vehicle width direction. The spaces 41 and 42 are respectively filled with the resin material 43.

The space 41 includes a first space portion 41a which is located at the vertical extension portion 11b and a second space portion 41b which is located at the rear extension portion 11c. The first space portion 41a and the second space portion 41b communicate with each other above and below the plate concave portion 25d (also see FIG. 4) of the left plate member 25.

The space 42 includes a first space portion 42a which is located at the vertical extension portion 11b and a second space portion 42b which is located at the rear extension portion 11c. The first space portion 42a and the second space portion 42b communicate with each other above and below the plate concave portion 25d of the right plate member 25.

The resin material 43 is formed such that a molten resin injected into molding dies when injection-molding the left and right rib portions 13 and 17 flows into the spaces 41 and 42 and is filled and solidified in the spaces 41 and 42. In this way, since the spaces 41 and 42 are filled with the resin material 43, it is possible to improve the strength and rigidity of the arm body 11.

Since the spaces 41 and 42 are open to the outside in a convex arc surface 11q forming the upper end of the vertical extension portion 11b and the rear surface 11p of the rear extension portion 11c among an outer peripheral surface 11h of the arm body 11, the resin material 43 is exposed to the outside. Further, since the space 41 is open to the outside also in the inner peripheral surface of the bush mounting hole 11a, the resin material 43 is exposed to the outside. On the other hand, since the space 42 is blocked by the rising portion 26d of the inner plate 26 also in the inner peripheral surface of the bush mounting hole 11a, the resin material 43 is not exposed to the outside.

FIG. 10 is a cross-sectional view taken along the line X-X of FIG. 4.

As shown in FIG. 10, each plate concave portion 25d includes a bottom wall 25s forming the bottom surface 25g. The pair of bottom walls 25s forming the plate concave portions 25d of the left and right plate members 25 is crimped to the inner plate 26 while sandwiching the inner plate 26 from both sides. In other words, the inner surface 25f which is a surface on the side of the inner plate 26 in the left and right plate members 25 is crimped to surfaces 26f on both sides of the inner plate 26.

The plate member 25 is positioned to both sides of the inner plate 26 in the plate thickness direction of the arm body 11 in such a manner that the bottom wall 25s is brought into contact with the inner plate 26. Since the bottom wall 25s is joined to the inner plate 26 by surface, it is possible to increase the joint strength.

A third space portion 41c and a fourth space 41d constituting the space 41 are arranged in the periphery of the plate concave portion 25d on one side (left side). A third space portion 42c and a fourth space 42d constituting the space 42 are arranged in the periphery of the plate concave portion 25d on the other side (right side).

The rib portion 13 is formed on the outer surface 25e on the side opposite to the arrangement side of the third space portion 41c and the fourth space 41d with respect to the plate member 25 on one side (left side). The rib portion 17 is formed on the outer surface 25e on the side opposite to the arrangement side of the third space portion 42c and the fourth space 42d with respect to the plate member 25 on the other side (right side).

Each rib 13a of the rib portions 13 and 17 is formed along the shape of the outer surface 25e of the plate member 25. That is, each rib 13a extends from the end surface 13b to the outer surface 25e on the outside of the vehicle width direction in the third space portion 41c, the fourth space 41d, the third space portion 42c, and the fourth space 42d and extends from the end surface 13b to the bottom surface 25g or the side surface 25h in the plate concave portion 25d. In the plate concave portion 25d, the height of each rib 13a becomes higher than that of a portion other than the plate concave portion 25d.

In the upper surface 11m and the lower surface 11n of the rear extension portion 11c among the outer peripheral surface 11h of the arm body 11, the spaces 41 and 42 are covered with the upper flange portion 25m and the lower flange portion 25n of each of the left and right plate members 25. Therefore, the upper flange portion 25m and the lower flange portion 25n of each of the left and right plate members 25 are exposed to the outside, but the resin material 43 is not easily exposed to the outside. Accordingly, it is possible to suppress the bending of the resin material 43 in the spaces 41 and 42 when a bending moment in the up and down direction is applied to the rear extension portion 11c of the arm body 11.

As described above, the trailing arm of the above-described embodiment is connected to the vehicle body 1 and the knuckle 6 supporting the rear wheel and includes the resinous plate member 25 having the hollow portion 38 and the metallic inner plate 26 joined to the plate member 25 in the hollow portion 38.

With such a configuration, since the metallic inner plate 26 and the resinous plate member 25 are joined in the hollow portion 38, it is possible to achieve both strength and rigidity assurance and weight reduction of the trailing arm 5.

The plate member 25 is composed of at least two members. Therefore, it is possible to easily join the plate member 25 to the inner plate 26 by sandwiching the inner plate 26 from both sides by at least two plate members 25.

The inner plate 26 is consisted by a press-processed plate material. Therefore, it is possible to easily process the inner plate 26 by press working.

The inner plate 26 includes the rising portion 26d which is connected to the vehicle body 1 and the knuckle side inner connection portion 26h which is connected to the knuckle 6. Therefore, since the vehicle body 1 and the knuckle 6 are connected by the metallic inner plate 26, it is possible to easily assure the strength and rigidity of the trailing arm 5.

The plate member 25 includes the vehicle body side outer connection portion 25t which is connected to the vehicle body 1, the outer tubular portion 25k which is connected to the knuckle 6, and the plate concave portion 25d which is disposed between the vehicle body side outer connection portion 25t and the outer tubular portion 25k. Therefore, it is possible to increase the rigidity between the vehicle body side outer connection portion 25t and the outer tubular portion 25k in the plate member 25 by the plate concave portion 25d.

The inner plate 26 includes the vehicle body side inner through-hole 26c and the tubular rising portion 26d is formed by burring work performed on the edge portion of the vehicle body side inner through-hole 26c. Therefore, since the rising portion 26d formed by burring work can be a seat surface for fixing the rubber bush 12 to the connection portion between the vehicle body 1 and the trailing arm 5, a bush fixing member such as a collar can be omitted.

The plate member 25 includes the rib portions 13 and 17 which are formed on the outer surface 25e on the side opposite to the hollow portion 38. Therefore, since the rib portions 13 and 17 are provided, it is possible to increase the rigidity of the trailing arm 5.

The rib portions 13 and 17 are composed of the plurality of ribs 13a and the plurality of ribs 13a are arranged in a lattice shape. Therefore, since the ribs 13a are arranged in a lattice shape, it is possible to further increase the rigidity of the trailing arm 5.

Since the plate member 25 contains reinforcing fibers, it is possible to further increase the strength of the trailing arm 5.

Since the rib portions 13 and 17 are formed along the shape of the plate concave portion 25d of the plate member 25, the height of the rib portions 13 and 17 can be higher in the portion of the plate concave portion 25d and thus the rigidity of the trailing arm 5 can be further improved.

The left and right plate members 25 include the bottom walls 25s which are formed on the inside of the peripheral edge portion 25c so as to sandwich the inner plate 26 from both sides. Therefore, it is possible to easily position the plate member 25 to both sides of the inner plate 26 by the bottom walls 25s. Further, it is possible to increase the joint strength between the inner plate 26 and the plate member 25.

Additionally, the present invention is not limited to the above-described embodiment. For example, in this embodiment, the pair of plate members 25 is provided, but at least two plate members 25 may be provided. Further, the plate member 25 is provided with a single plate concave portion 25d, but may be provided with a plurality of plate concave portions.

Further, the plate member 25 is provided with the concave portion (plate concave portion 25d) which is recessed from the outer surface toward the inner surface, but the present invention is not limited thereto. For example, a convex portion may be provided to protrude from the inner surface toward the outer surface or both the concave portion and the convex portion may be provided. In this case, the rib portion is formed along the shape of the convex portion.

Further, each of the space 41 formed in the inner plate 26 on one side (left side) of the vehicle width direction and the space 42 formed in the inner plate 26 on the other side (right side) of the vehicle width direction is filled with the resin material 43 by injection-molding. However, each of the spaces 41 and 42 may not be filled with the resin material 43 after injection-molding. When injection-molding the left and right rib portions 13 and 17, it is sufficient as long as the resin material 43 flows at least around the rubber bush 12 and the collar 21.

The trailing arm of the above-described embodiment is applicable to three-wheeled and four-wheeled vehicles. Then, the configuration in the above-described embodiment is an example of the present invention, and various changes can be made without departing from the scope of the present invention, such as replacing the constituent elements of the embodiment with well-known constituent elements.

While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the present invention. Accordingly, the invention is not to be considered as being limited by the foregoing description, and is only limited by the scope of the appended claims.

Claims

1. A trailing arm which is connected to a vehicle body and a knuckle supporting a vehicle wheel, the trailing arm comprising: a resinous outer portion which has a hollow portion; anda metallic inner portion which is joined to the outer portion in the hollow portion.

2. The trailing arm according to claim 1, wherein the outer portion is consisted by at least two members.

3. The trailing arm according to claim 1, wherein the inner portion is consisted by a press-processed plate material.

4. The trailing arm according to claim 1, wherein the inner portion includes a vehicle body side inner connection portion which is connected to the vehicle body and a knuckle side inner connection portion which is connected to the knuckle.

5. The trailing arm according to claim 1, wherein the outer portion includes a vehicle body side outer connection portion which is connected to the vehicle body, a knuckle side outer connection portion which is connected to the knuckle, and a convex portion or a concave portion which is disposed between the vehicle body side outer connection portion and the knuckle side outer connection portion.

6. The trailing arm according to claim 4, wherein the inner portion includes a vehicle body side inner through-hole, andwherein the vehicle body side inner connection portion having a tubular shape is formed by burring work performed on an edge portion of the vehicle body side inner through-hole.

7. The trailing arm according to claim 1, wherein the outer portion includes a rib portion which is formed on a surface on a side opposite to the hollow portion.

8. The trailing arm according to claim 7, wherein the rib portion is composed of a plurality of ribs and the plurality of ribs are arranged in a lattice shape.

9. The trailing arm according to claim 1, wherein the outer portion contains reinforcing fibers.

10. The trailing arm according to claim 7, wherein the outer portion includes a vehicle body side outer connection portion which is connected to the vehicle body, a knuckle side outer connection portion which is connected to the knuckle, and a convex portion or a concave portion which is disposed between the vehicle body side outer connection portion and the knuckle side outer connection portion, andwherein the rib portion is formed along a shape of the convex portion or the concave portion of the outer portion.

11. The trailing arm according to claim 2, wherein the outer portion includes a sandwiching portion which is formed on an inside of a peripheral edge portion so as to sandwich the inner portion from both sides.