Rear suspension structure for a vehicle

Abstract

To provide a vehicle rear suspension structure which has an existing structure as a basic structure and may be applied to a four-wheel-drive vehicle which is driven by a motor.SOLUTION: A vehicle rear suspension structure 100 includes a torsion beam 1 and a pair of arm units 2L, 2R. Each of the arm units (2L, 2R) includes a trailing arm 21 formed in a cylindrical shape extending in a vehicle fore and aft direction, an end plate 22 which closes a rear side opening of the trailing arm 21, an upper reinforcing member 25, and a lower reinforcing member 26. A shaft insertion hole (a hole) 2a is formed in an inner portion of a rear arm 21e of the trailing arm 21, the upper reinforcing member 25 is joined to the rear arm 21e so as to run along an upper edge portion 2a1 of a peripheral edge portion of the shaft insertion hole 2a, and the lower reinforcing member 26 is joined to the rear arm 21e so as to run along a lower edge portion 2a2 of the peripheral edge portion of the shaft insertion hole 2a.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a rear suspension structure for a vehicle.

Background Art

[0002] As an example of a rear suspension structure that can be frequently used as a rear suspension structure for the rear wheels in a 4WD vehicle (four-wheel drive vehicle) having an engine driven by an internal combustion engine as a drive source, a suspension structure disclosed in Patent Document 1 is known. The suspension structure disclosed in Patent Document 1 includes a torsion beam extending in the vehicle width direction, a left trailing arm connected to the left end of the torsion beam, a right trailing arm connected to the right end of the torsion beam, a left carrier bracket attached to the upper part of the left trailing arm, and a right carrier bracket attached to the upper part of the right trailing arm. A hub for the rear wheel is attached to each carrier bracket, and a drive shaft is connected to the hub.

[0003] In a 4WD vehicle, the driving force from the engine disposed on the front side of the vehicle is transmitted to the rear wheels via a propeller shaft extending in the vehicle longitudinal direction and a drive shaft extending in the vehicle width direction. The propeller shaft is arranged to pass above the torsion beam in order to avoid interference with the torsion beam. Therefore, the drive shaft is also arranged above the torsion beam, and the carrier bracket to which the hub is attached is also attached to the upper part of the trailing arm as described above. Thus, in the rear suspension structure of a conventional 4WD vehicle, the positions of the components are restricted by the propeller shaft.

[0004] On the one hand, most engine-driven vehicles are 2WD vehicles (two-wheel drive vehicles) that drive only two wheels, and furthermore, in most 2WD vehicles, a system that drives only the front wheels by an engine arranged on the front side of the vehicle is adopted. In the rear suspension structure of such a 2WD vehicle (that is, an FF vehicle which is a front-engine and front-wheel drive), there is no restriction by a propeller shaft. Therefore, in a 2WD vehicle (FF vehicle), the hub is often attached to an end plate joined to a trailing arm so as to close the rear opening of the cylindrical trailing arm. Thus, in a 2WD vehicle (FF vehicle), a rear suspension structure of a type in which an end plate is joined to a trailing arm so as to close the rear opening of the trailing arm (hereinafter, appropriately referred to as an end plate type structure) is frequently used.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, in recent years, due to the electrification of vehicles, a technology of driving the rear wheels by an electric motor instead of an engine has been increasingly used for 4WD vehicles. In the case of a 4WD vehicle driven by an electric motor, different from a 4WD vehicle driven by an engine, an electric motor for driving the rear wheels is arranged on the rear side of the vehicle. Therefore, in a 4WD vehicle driven by an electric motor, a propeller shaft becomes unnecessary, and in its rear suspension structure, the restriction by the propeller shaft is eliminated.

[0007] Therefore, it may be desirable to construct a new structure for application to the rear suspension structure of a 4WD vehicle that drives the rear wheels by an electric motor. However, from the viewpoint of cost and the like, it is desirable that a rear suspension structure having an existing structure as a basic structure is constructed instead of a structure completely different from the conventional one.

[0008] In view of the above problems, an object of the present invention is to provide a rear suspension structure for a vehicle that has an existing structure as a basic structure and can be applied to a motor-driven 4WD vehicle.

Means for Solving the Problems

[0009] The rear suspension structure for a vehicle according to the present invention for achieving the above object includes a torsion beam extending in the vehicle width direction, and a pair of arm units, one of which is joined to one end of the torsion beam and the other of which is joined to the other end of the torsion beam. Each of the arm units has a trailing arm formed in a cylindrical shape that has a joint portion with respect to the torsion beam and extends in the vehicle longitudinal direction, and an end plate that closes the rear opening of the trailing arm and to which a hub for a rear wheel is attached. In this rear suspension structure for a vehicle, a rear arm, which is a portion of the trailing arm on the rear side of the joint portion, is bent so as to open the rear opening to the outside in the vehicle width direction, and a hole is formed in an inner portion of the rear arm in the vehicle width direction with a size into which an end portion of a drive shaft connectable to the hub can be inserted. Each of the pair of arm units has an upper reinforcing member joined to the rear arm along at least a part of an upper edge portion of the peripheral edge of the hole, and a lower reinforcing member joined to the rear arm along at least a part of a lower edge portion of the peripheral edge of the hole.

Effects of the Invention

[0010] According to the present invention, it is possible to provide a rear suspension structure for a vehicle that has an existing end plate type structure as a basic structure and can be applied to a motor-driven 4WD vehicle.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0013] FIG. 1 is a plan view of a rear suspension structure for a vehicle according to an embodiment of the present invention as viewed from above the vehicle, and FIG. 2 is a perspective view showing a part of the rear suspension structure for a vehicle of FIG. 1. In the drawings, arrow Fr indicates the front in the vehicle longitudinal direction, and arrow B indicates the rear in the vehicle longitudinal direction. Arrows R and L indicate the right side and the left side in the vehicle width direction (vehicle width direction) when the occupant views the front of the vehicle. And arrow U indicates the upper side in the vehicle vertical direction, and arrow D indicates the lower side in the vehicle vertical direction. Also, the "front end (front part) and rear end (rear part)" in the description of the embodiment correspond to the front end and the rear end in the vehicle longitudinal direction.

[0014] Referring to FIGS. 1 and 2, a rear suspension structure 100 for a vehicle according to this embodiment is a torsion beam type rear suspension structure to which a rear wheel is attached. In this embodiment, the rear suspension structure 100 for a vehicle is assumed to be applied to a rear suspension structure of a motor-driven 4WD vehicle (four-wheel drive vehicle).

[0015] The rear suspension structure 100 for a vehicle includes a torsion beam 1 extending in the vehicle width direction and a pair of arm units 2L and 2R.

[0016] The torsion beam 1 extends linearly in the vehicle width direction and is a metal member that applies a reaction force due to torsion to each of the left and right rear wheels. One of the pair of arm units 2L and 2R is joined to one end of the torsion beam 1, and the other of the pair of arm units 2L and 2R is joined to the other end of the torsion beam 1.

[0017] The pair of arm units 2L and 2R are arranged on one end side and the other end side of the torsion beam 1 with a space therebetween in the vehicle width direction. Hereinafter, one of the pair of arm units 2L and 2R will be referred to as the left arm unit 2L, and the other of the pair of arm units 2L and 2R will be referred to as the right arm unit 2R. The left arm unit 2L is joined to the left end of the torsion beam 1, and the right arm unit 2R is joined to the right end of the torsion beam 1.

[0018] In this embodiment, each of the left arm unit 2L and the right arm unit 2R includes a trailing arm 21, an end plate 22, a spring support portion 23, and a shock absorber holding portion 24. Hereinafter, the elements of the right arm unit 2R will be mainly described. The left arm unit 2L (that is, one of the arm units 2L) and the right arm unit 2R (that is, the other of the arm units 2R) have the same structure (shape) except that they are symmetrically formed with respect to each other in the vehicle width direction (left-right direction).

[0019] The trailing arm 21 has a front portion 21a connected to the vehicle body and a joint portion 21b to the torsion beam 1, and is formed in a cylindrical shape extending in the longitudinal direction of the vehicle. Specifically, the trailing arm 21 is gently curved so as to be convex inward in the vehicle width direction as a whole, and has an arcuate shape convex inward in the vehicle width direction.

[0020] A metallic vehicle body side connecting portion 21c, which is formed in a cylindrical shape and extends generally in the vehicle width direction, is joined to the front portion 21a of the trailing arm 21. A rubber bush 21d formed in a cylindrical shape is attached to the vehicle body side connecting portion 21c. A pin (not shown) supported on the vehicle body side is inserted into the bush 21d. Thereby, the trailing arm 21 is connected to the vehicle body so as to be swingable in the vertical direction with the pin as a fulcrum.

[0021] The joint portion 21b of the trailing arm 21 is located generally in the middle in the longitudinal direction of the trailing arm 21. The inner portion in the vehicle width direction at the joint portion 21b forms the top of the curved trailing arm 21, and the end of the torsion beam 1 is joined to this portion.

[0022] A rear arm 21e, which is a portion of the trailing arm 21 behind the joint portion 21b, is bent so as to open the rear opening of the cylindrical trailing arm 21 to the outside in the vehicle width direction. In other words, the trailing arm 21 is curved so that the rear opening of the trailing arm 21 faces the outside in the vehicle width direction.

[0023] The end plate 22 is a member that closes the rear opening of the trailing arm 21 and to which the hub 3 for the rear wheel is attached. The end plate 22 is made of a metallic plate material having a predetermined thickness, and is joined to an annular end face that is the peripheral edge of the opening of the rear arm 21e of the trailing arm 21. The end plate 22 extends in the vehicle longitudinal direction and the vehicle vertical direction, and its peripheral portion projects outward from the outer peripheral surface of the rear arm 21e.

[0024] On the outer surface of the end plate 22 in the vehicle width direction, although not particularly limited, a drum-type brake unit 4 (see FIG. 1) is attached. The hub 3 is a member that rotatably supports the rear wheel and is attached to the end plate 22 through the brake unit 4. A central hole 22a is opened at the center of the end plate 22 (see FIGS. 3, 4, and 9 described later), and the end of the hub 3 is exposed into the inner space of the rear arm 21e through the central hole 22a. The shape of the end plate 22 will be described in detail later.

[0025] The spring support portion 23 is a member for supporting the lower end portion 5b of a coil spring 5 (see FIG. 2) having an upper end portion 5a connected to the vehicle body. The spring support portion 23 is joined to at least the inner portion of the rear arm 21e in the vehicle width direction. Here, the spring support portion 23 is joined not only to the rear arm 21e but also to the torsion beam 1. Specifically, the spring support portion 23 is made of a thin metal plate and has a seat surface portion 23a for receiving the lower end portion 5b of the coil spring 5. And the peripheral edge portion of the seat surface portion 23a of the spring support portion 23 is joined near the corner portion formed by the torsion beam 1 and the rear arm 21e.

[0026] A spring support hole 23a1 is opened at the center of the seat surface portion 23a of the spring support portion 23, for example, by burring. And the peripheral edge portion of the spring support hole 23a1 in the seat surface portion 23a protrudes upward. Using this upward protruding annular peripheral edge portion, the lower end portion 5b of the coil spring 5 (see FIG. 2) is supported.

[0027] The shock absorber holding portion 24 is a member for holding the lower end portion 6b of a shock absorber 6 (see FIG. 2) having an upper end portion 6a connected to the vehicle body. The shock absorber holding portion 24 is disposed more inward in the vehicle width direction than the end plate 22. The shock absorber holding portion 24 is joined to the corresponding arm unit (2L or 2R). The shape and joining position of the shock absorber holding portion 24 will be described in detail later.

[0028] In the rear suspension structure 100 for a vehicle, as described above, the rear opening of the cylindrical trailing arm 21 is closed by the end plate 22, and the hub 3 to which the rear wheel is attached is attached to the end plate 22. Such a rear suspension structure is widely adopted in many vehicles as a rear suspension structure for a 2WD vehicle (FF vehicle) with a front engine and front-wheel drive, and is also called an end plate type structure. Therefore, the rear suspension structure 100 for a vehicle is constructed based on an end plate type rear suspension structure applicable to an engine-driven 2WD vehicle (FF vehicle), and has the existing end plate type rear suspension structure as its basic structure.

[0029] By the way, the vehicle to which the rear suspension structure 100 for a vehicle of the present embodiment is applied is, as described above, a motor-driven 4WD vehicle (four-wheel drive vehicle). In a motor-driven 4WD vehicle, generally, it has an electric motor for front-wheel drive and an electric motor for rear-wheel drive. Referring to FIG. 1, the electric motor M for rear-wheel drive is disposed between a pair of trailing arms 21, 21. Specifically, the electric motor M for rear-wheel drive is fixed to the vehicle body behind the torsion beam 1 in the vehicle longitudinal direction and between the two rear arms 21e. Here, it is necessary to transmit the driving force from the electric motor M to the rear wheels via the drive shaft 7, the hub 3, etc. However, the end plate type rear suspension structure is a structure that is frequently used as a rear suspension structure for an engine-driven FF vehicle that does not need to transmit driving force to the rear wheels in the first place. Therefore, the rear suspension structure 100 for a vehicle of the present embodiment based on the end plate type structure has the following configuration in order to transmit the driving force from the electric motor M to the rear wheels.

[0030] Next, the configuration of the vehicle rear suspension structure 100 will be described in detail. FIGS. 3 to 5 are views showing a part (right side portion) of the vehicle rear suspension structure 100. FIG. 3 is an enlarged perspective view seen from the inner side in the vehicle width direction, FIG. 4 is a side view seen from the inner side in the vehicle width direction, and FIG. 5 is a rear view seen from the rear side in the vehicle longitudinal direction. In FIGS. 3 to 5 and FIGS. 6 to 9 described later, the hub 3, the brake unit 4, the coil spring 5, and the shock absorber 6 are shown in a removed state. In FIGS. 3 to 6 and FIG. 9, further, the drive shaft 7 and the boot 8 described later are removed.

[0031] Referring to FIGS. 3 to 5, in the vehicle rear suspension structure 100, a hole 2a (hereinafter referred to as the shaft insertion hole 2a) having a size that allows insertion of the end portion of the drive shaft 7 connectable to the hub 3 is formed in a portion of the rear arm 21e of the trailing arm 21 on the inner side in the vehicle width direction. Specifically, an electric motor M is connected to one end portion of the drive shaft 7, and the other end portion of the drive shaft 7 is connected to the end portion of the hub 3 exposed in the internal space of the rear arm 21e. A universal joint (not shown) covered by a boot 8 made of a hollow rubber member is provided in a portion near the other end portion of the drive shaft 7. The boot 8 is formed to have an outer diameter larger than the outer diameter of the drive shaft 7 so as to be able to accommodate the universal joint therein. The shaft insertion hole 2a is opened with a size that allows easy insertion of the boot 8, and the portion of the boot 8 on the hub 3 side is located inside the rear arm 21e. More specifically, the shaft insertion hole 2a is opened with a size such that a gap is formed between the outer peripheral surface of the boot 8 and the opening edge of the shaft insertion hole 2a even when the trailing arm 21 swings maximally.

[0032] In this embodiment, the rear arm 21e of the trailing arm 21 is formed in a flat cylindrical shape in the vehicle vertical direction and the vehicle width direction. The rear arm 21e has, for example, a substantially flat upper surface 21e1, a substantially flat inner surface 21e2 on the inner side in the vehicle width direction, and a lower surface 21e3 facing downward below the inner surface 21e2 at the rear end side portion of the trailing arm 21. The upper surface 21e1 is inclined generally downward toward the inner side in the vehicle width direction, the inner surface 21e2 extends generally in the vehicle vertical direction, and the lower surface 21e3 is gently curved so as to be continuous with the inner surface 21e2 (or is inclined generally upward toward the inner side in the vehicle width direction).

[0033] In this embodiment, the shaft insertion hole (in other words, the boot insertion hole) 2a is open from the portion on the inner side in the vehicle width direction of the rear arm 21e to the region of the substantially flat upper surface 21e1 of the rear arm 21e. Further, in this embodiment, the shaft insertion hole 2a also reaches the lower surface 21e3 of the rear arm 21e. Therefore, the shaft insertion hole 2a is open over the upper surface 21e1, the inner surface 21e2, and the lower surface 21e3 of the vertically and horizontally flat cylindrical rear arm 21e. In other words, the upper portion of the opening edge of the shaft insertion hole 2a is located in the region of the substantially flat upper surface 21e1 of the rear arm 21e, and the lower portion of the opening edge of the shaft insertion hole 2a is located in the region of the lower surface 21e3 of the rear arm 21e. Thus, the shaft insertion hole 2a is formed as an opening that extends vertically with respect to the inner surface 21e2 of the rear arm 21e.

[0034] And each of the left arm unit 2L and the right arm unit 2R further has an upper reinforcing member 25 and a lower reinforcing member 26. The upper reinforcing member 25 and the lower reinforcing member 26 are members for compensating for the reduction in arm rigidity due to the opening of the large shaft insertion hole 2a.

[0035] The upper reinforcing member 25 is a reinforcing member joined to the rear arm 21e so as to be along at least a part of the upper edge portion 2a1 of the peripheral edge portion of the shaft insertion hole 2a. The upper reinforcing member 25 is made of a metal plate material and extends generally in the vehicle longitudinal direction.

[0036] The lower reinforcement member 26 is a reinforcement member joined to the rear arm 21e so as to extend along at least a part of the lower edge portion 2a2 of the peripheral edge portion of the shaft insertion hole 2a. The lower reinforcement member 26 is made of a metal plate material and generally extends in the vehicle longitudinal direction.

[0037] In the present embodiment, the front end of the upper reinforcement member 25 and the front end of the lower reinforcement member 26 are located on the front side of the shaft insertion hole 2a, and the rear end of the upper reinforcement member 25 and the rear end of the lower reinforcement member 26 are located on the rear side of the shaft insertion hole 2a. Therefore, the lengths of the upper reinforcement member 25 and the lower reinforcement member 26 in the vehicle longitudinal direction are longer than the opening width of the shaft insertion hole 2a in the vehicle longitudinal direction. The upper reinforcement member 25 is joined to the rear arm 21e so as to straddle the shaft insertion hole 2a in the vehicle longitudinal direction and along the upper edge portion 2a1 of the shaft insertion hole 2a. The lower reinforcement member 26 is joined to the rear arm 21e so as to straddle the shaft insertion hole 2a in the vehicle longitudinal direction and along the lower edge portion 2a2.

[0038] FIG. 6 is a plan view of a part of the vehicle rear suspension structure 100 of FIG. 3 as viewed from above. Referring to FIGS. 3 to 6, in the present embodiment, the upper reinforcement member 25 is joined to the upper surface 21e1 of the rear arm 21e, bulges upward from the upper surface 21e1, and is formed so as to cover the opening region inside the upper edge portion 2a1 of the peripheral edge portion of the shaft insertion hole 2a in a top view (see FIG. 6) from above. Specifically, the upper reinforcement member 25 is formed in a half-dome shape that is open downward in the vehicle vertical direction and inward in the vehicle width direction, and has a quarter spherical surface (a half of a hemispherical surface). The lower edge of the upper reinforcement member 25 extends in an arc shape in a top view and forms a joint edge portion with the rear arm 21e.

[0039] FIG. 7 is a bottom view of a part of the rear suspension structure 100 for a vehicle in FIG. 3 as viewed from below, and FIG. 8 is a view showing a state in which the lower member is removed in the bottom view of FIG. 7. Referring to FIGS. 3 to 8, in the present embodiment, the lower reinforcement member 26 has a vertical cylinder portion 26a and a bottom plate portion 26b. The lower reinforcement member 26 extends in the vehicle front-rear direction from a predetermined position on the front side of the spring support portion 23 to a predetermined position on the rear side of the rear end of the trailing arm 21 (specifically, the rear end of the end plate 22) as a whole.

[0040] The vertical cylinder portion 26a is formed in a cylindrical shape extending in the vehicle vertical direction and has an annular upper end surface joined to the lower surfaces of the rear arm 21e of the trailing arm 21 and the spring support portion 23. Specifically, the vertical cylinder portion 26a is made of a metal plate material and is formed flat in the vehicle width direction. Most of the outer portion in the vehicle width direction of the upper end surface of the vertical cylinder portion 26a is joined to the portion below the shaft insertion hole 2a in the lower surface 21e3 of the rear arm 21e, and most of the front half of the inner portion in the vehicle width direction of the upper end surface of the vertical cylinder portion 26a is joined to the lower surface of the seat surface portion 23a of the spring support portion 23.

[0041] More specifically, the vertical cylindrical portion 26a is composed of a U-shaped portion 26a1, an L-shaped portion 26a2, an outer curved portion 26a3 connecting one end of the U-shaped portion 26a1 and one end of the L-shaped portion 26a2, and an inner curved portion 26a4 connecting the other end of the U-shaped portion 26a1 and the other end of the L-shaped portion 26a2. The U-shaped portion 26a1 constitutes the rear part of the vertical cylindrical portion 26a and is close to the vicinity of the end plate 22. The L-shaped portion 26a2 constitutes the front part of the vertical cylindrical portion 26a and is closer to the inner side in the vehicle width direction with respect to the U-shaped portion 26a1. The outer curved portion 26a3 extends along the lower surface 21e3 of the trailing arm 21 and is curved in the vehicle width direction. The inner curved portion 26a4 has a portion along the lower surface of the seat surface 23a of the spring support portion 23 and is curved in the vehicle width direction inside the outer curved portion 26a3. The portion of the annular upper end surface of the vertical cylindrical portion 26a corresponding to the outer curved portion 26a3 is mainly joined to the rear arm 21e of the trailing arm 21, and the portion of the annular upper end surface of the vertical cylindrical portion 26a corresponding to most of the L-shaped portion 26a2 and a part of the inner curved portion 26a4 is joined to the lower surface of the spring support portion 23. Note that the lower surface of the spring support portion 23 is located below the lower surface 21e3 of the rear arm 21e, and the portion of the vertical cylindrical portion 26a below the spring support portion 23 is notched downward in a shape corresponding to the position of the lower surface of the spring support portion 23. The bottom of the U of the U-shaped portion 26a1 is located behind the rear end of the end plate 22, and the portion of the L-shaped portion 26a2 extending outward in the vehicle width direction is located in front of the seat surface 23a of the spring support portion 23.

[0042] The bottom plate portion 26b is made of a metal plate material and is joined to the annular lower end surface of the vertical cylindrical portion 26a so as to close the lower opening of the vertical cylindrical portion 26a. And the peripheral edge portion of the bottom plate portion 26b projects outward from the outer peripheral surface of the vertical cylindrical portion 26a. A plurality (two in the figure) of drain holes 26b1 are opened in the bottom plate portion 26b. When liquid such as rainwater intrudes into the inside of the lower reinforcing member 26, the liquid is discharged through the drain holes 26b1.

[0043] The shock absorber holding portion 24 described above is joined to the lower reinforcing member 26. Further, the shock absorber holding portion 24 is also joined to the end plate 22. That is, in the present embodiment, the shock absorber holding portion 24 is joined to the lower reinforcing member 26 and the end plate 22.

[0044] Specifically, the shock absorber holding portion 24 is formed in a rod shape extending in the vehicle width direction so as to penetrate the rear portion (U-shaped portion 26a1) of the vertical cylinder portion 26a of the lower reinforcing member 26. The shock absorber holding portion 24 is formed in a stepped rod shape including a large-diameter portion 24a joined to the lower reinforcing member 26 and the end plate 22, and a small-diameter portion 24b holding the lower end portion 6b of the shock absorber 6 (see FIG. 2). The shock absorber holding portion 24 and the spring support portion 23 are separated from each other in the vehicle front-rear direction, and the drive shaft 7 is disposed so as to extend in the vehicle width direction in the region between the coil spring 5 and the shock absorber 6.

[0045] The large-diameter portion 24a penetrates the vertical cylinder portion 26a (U-shaped portion 26a1) and is joined to the vertical cylinder portion 26a (U-shaped portion 26a1). That is, the end portion of the large-diameter portion 24a on the inner side in the vehicle width direction protrudes inward in the vehicle width direction from the vertical cylinder portion 26a, and the end portion of the large-diameter portion 24a on the outer side in the vehicle width direction protrudes outward in the vehicle width direction from the vertical cylinder portion 26a. The large-diameter portion 24a is joined to two locations, i.e., the inner wall and the outer wall in the vehicle width direction of the U-shaped portion 26a1 of the vertical cylinder portion 26a.

[0046] The small-diameter portion 24b has an outer diameter smaller than that of the large-diameter portion 24a and extends so as to protrude inward in the vehicle width direction from the end portion of the large-diameter portion 24a on the inner side in the vehicle width direction. The lower end portion 6b of the shock absorber 6 (see FIG. 2) is held by this small-diameter portion 24b.

[0047] FIG. 9 is a side view of a part of the rear suspension structure 100 for a vehicle in FIG. 3 as viewed from the outside in the vehicle width direction. Referring to FIGS. 5 to 9, in the present embodiment, the end on the outside in the vehicle width direction of the large-diameter portion 24a of the shock absorber holding portion 24 is joined to the inner surface of the end plate 22. Specifically, referring to FIG. 9, the end plate 22 is formed in a substantially rectangular shape. The central hole 22a opened in the end plate 22 is formed as a circular hole. When viewed from the vehicle width direction (see FIGS. 4 and 9), the opening regions of the central hole 22a and the shaft insertion hole 2a substantially overlap each other. Bolt insertion holes 22b are opened at the four corners of the end plate 22. Bolts for attaching the brake unit 4 to the end plate 22 are inserted through the bolt insertion holes 22b. Further, an extension portion 22c that extends obliquely outward is provided at the rear lower corner of the end plate 22. The extension portion 22c extends to the vicinity of the bottom plate portion 26b of the lower reinforcement member 26 in the vehicle vertical direction, and the U-shaped portion 26a1 of the vertical cylinder portion 26a of the lower reinforcement member 26 is positioned inside the extension portion 22c in the vehicle width direction. The wall on the outside in the vehicle width direction of the U-shaped portion 26a1 of the vertical cylinder portion 26a and the extension portion 22c are relatively close to each other in the vehicle width direction. Then, the end on the outside in the vehicle width direction of the large-diameter portion 24a of the shock absorber holding portion 24 is joined to the inner surface of the extension portion 22c of the end plate 22.

[0048] Next, the operation of the rear suspension structure 100 for a vehicle according to the present embodiment will be described.

[0049] As described above, the rear suspension structure 100 for a vehicle has, as its basic structure, an existing end plate type rear suspension structure that is frequently used as the rear suspension structure of an engine-driven 2WD vehicle (FF vehicle), and is constructed based on this structure. Therefore, a rear suspension structure for the rear wheels of a 4WD vehicle is constructed at low cost. In the rear suspension structure 100 for a vehicle, a shaft insertion hole 2a that is open with a size capable of inserting the end of a drive shaft 7 connectable to a hub 3 is formed in a portion on the inner side in the vehicle width direction of the rear arm 21e of the trailing arm 21. The reduction in arm rigidity due to the opening of this large shaft insertion hole 2a in the trailing arm 21 is reinforced by an upper reinforcing member 25 and a lower reinforcing member 26. Therefore, although the large shaft insertion hole 2a is open in the trailing arm 21, the rear suspension structure 100 for a vehicle has sufficient arm rigidity and has a structure capable of transmitting the driving force from the electric motor M to the rear wheels by connecting the drive shaft 7 to the hub 3 attached to the end plate 22 through the shaft insertion hole 2a.

[0050] As described above, the rear suspension structure 100 for a vehicle according to the present embodiment has, as its basic structure, an existing end plate type rear suspension structure and is a rear suspension structure for a vehicle that can be applied to a motor-driven 4WD vehicle. Note that the rear suspension structure 100 for a vehicle is not limited to a motor-driven 4WD vehicle, but can be applied to a rear suspension structure of a 2WD vehicle (RR vehicle) that drives only the rear wheels by an electric motor M disposed on the rear side of the vehicle, a rear suspension structure of a 2WD vehicle (FF vehicle) that drives only the front wheels by an electric motor disposed on the front side of the vehicle, and a rear suspension structure of a 2WD vehicle (FF vehicle) that drives only the front wheels by an engine by an internal combustion engine disposed on the front side of the vehicle. That is, the rear suspension structure 100 for a vehicle is shared between 2WD vehicles and 4WD vehicles and has high versatility.

[0051] In this embodiment, the front ends of the upper reinforcing member 25 and the lower reinforcing member 26 are located on the front side of the shaft insertion hole 2a, and the rear ends of the upper reinforcing member 25 and the lower reinforcing member 26 are located on the rear side of the shaft insertion hole 2a. As a result, the upper edge portion 2a1 of the peripheral portion of the shaft insertion hole 2a is reinforced by the upper reinforcing member 25 over the entire vehicle front-rear direction, and the lower edge portion 2a2 of the peripheral portion of the shaft insertion hole 2a is reinforced by the lower reinforcing member 26 over the entire vehicle front-rear direction, and the trailing arm 21 is more effectively reinforced.

[0052] In this embodiment, the upper reinforcing member 25 is joined to the upper surface 21e1 of the rear arm 21e, bulges upward from the upper surface 21e1, and is formed so as to cover the opening region inside the upper edge portion 2a1 in a top view from above. As a result, a compact upper reinforcing member 25 having sufficient reinforcing strength is constructed, and a structure capable of easily preventing interference between the boot 8 and the trailing arm 21 during swinging of the trailing arm 21 is constructed.

[0053] In this embodiment, the lower reinforcing member 26 is formed in a cylindrical shape extending in the vehicle vertical direction, and has a vertical cylindrical portion 26a having an annular upper end surface joined to the lower surfaces of the rear arm 21e and the spring support portion 23. As a result, the trailing arm 21 is more effectively reinforced by a large joined body of the spring support portion 23 and the lower reinforcing member 26 having the vertical cylindrical portion 26a. Also, an improvement in the support rigidity with respect to the coil spring 5 is achieved.

[0054] In this embodiment, the shock absorber holding portion 24 is joined to the lower reinforcing member 26 and the end plate 22. As a result, without adding a dedicated component for ensuring the rigidity to support the shock absorber holding portion 24 itself, the shock absorber holding portion 24 is firmly supported by the large joined body of the lower reinforcing member 26 and the end plate 22. Further, since the load from the shock absorber 6 is dispersed and input over the entire trailing arm 21 via the shock absorber holding portion 24, the lower reinforcing member 26, and the end plate 22, the shock absorber 6 is stably supported by the trailing arm 21. From the viewpoint of the rigidity in the vehicle up-and-down direction capable of withstanding the input load from the coil spring 5 and the shock absorber 6, it is preferable that the lower reinforcing member 26 has a vertical cylinder portion 26a.

[0055] The description of this embodiment is an exemplification for explaining the present invention and does not limit the invention described in the claims. Further, each component configuration of the present invention is not limited to the above embodiment, and various modifications are possible within the technical scope described in the claims.

[0056] For example, although the extension portion 22c of the end plate 22 is separated from the bottom plate portion 26b of the lower reinforcing member 26, it is not limited thereto, and it may be in contact with and joined to the bottom plate portion 26b. Although the spring support portion 23 is joined to the torsion beam 1, it is not limited thereto, and it may not be joined to the torsion beam 1. Although the shock absorber holding portion 24 is formed in a rod shape, it is not limited thereto, and it may be a bracket formed by bending a metal plate. Further, the brake unit 4 may be a disk-type unit.

[0057] Although the upper reinforcing member 25 is formed in a half-dome shape, it is not limited thereto, and it may be formed along at least a part of the upper edge portion 2a1 of the peripheral edge portion of the shaft insertion hole 2a. Further, the lower reinforcing member 26 may not have a bottom plate portion 26b. The lower reinforcing member 26 is not limited to the shape having the vertical cylinder portion 26a. The lower reinforcing member 26 may be formed along at least a part of the lower edge portion 2a2 of the peripheral edge portion of the shaft insertion hole 2a.

Explanation of Symbols

[0058] 1…Torsion beam, 2L, 2R…Pair of arm units, 2a…Shaft insertion hole (hole), 2a1…Upper edge, 2a2…Lower edge, 21…Trailing arm, 21b…Joint part, 21e…Rear arm, 21e1…Upper surface, 22…End plate, 23…Spring support part, 24…Shock absorber holding part, 25…Upper reinforcement member, 26…Lower reinforcement member, 26a…Vertical cylinder part, 3…Hub, 5…Coil spring, 5a…Upper end part, 5b…Lower end part, 6…Shock absorber, 6b…Lower end part, 7…Drive shaft, 100…Rear suspension structure for vehicle

Claims

1. A torsion beam extending in the vehicle width direction, A pair of arm units, one of which is joined to one end of the torsion beam and the other is joined to the other end of the torsion beam, each having a joint portion with respect to the torsion beam and formed in a cylindrical shape extending in the vehicle longitudinal direction, a trailing arm, and an end plate that closes the rear opening of the trailing arm and to which a hub for a rear wheel is attached. A vehicle rear suspension structure including: The rear arm, which is a portion of the trailing arm behind the joint portion, is bent so as to open the rear opening to the outside in the vehicle width direction. A hole is formed in a portion of the rear arm on the inner side in the vehicle width direction, the hole being sized to allow insertion of an end portion of a drive shaft connectable to the hub. Each of the pair of arm units has an upper reinforcement member joined to the rear arm along at least a part of the upper edge portion of the peripheral edge of the hole, and a lower reinforcement member joined to the rear arm along at least a part of the lower edge portion of the peripheral edge of the hole. A vehicle rear suspension structure.

2. The front end of the upper reinforcement member and the front end of the lower reinforcement member are located in front of the hole. The rear end of the upper reinforcement member and the rear end of the lower reinforcement member are located behind the hole. The vehicle rear suspension structure according to Claim 1.

3. The rear arm is formed in a flat cylindrical shape in the vehicle vertical direction and the vehicle width direction. The hole is opened from a portion of the rear arm on the inner side in the vehicle width direction to a region of the upper surface of the rear arm. The upper reinforcement member is joined to the upper surface of the rear arm, bulges upward from the upper surface, and is formed so as to cover the opening region inside the upper edge portion from above in a top view. The vehicle rear suspension structure according to Claim 1 or 2.

4. Each of the pair of arm units has a spring support portion that supports the lower end portion of a coil spring and is joined to at least a portion of the rear arm on the inner side in the vehicle width direction. The lower reinforcement member is formed in a cylindrical shape extending in the vehicle vertical direction and has a vertical cylindrical portion having an annular upper end surface joined to the lower surfaces of the rear arm and the spring support portion. The vehicle rear suspension structure according to any one of Claims 1 to 3.

5. Each of the pair of trailing arms holds a lower end portion of a shock absorber and has a shock absorber holding portion joined to the lower reinforcing member and the end plate, the vehicle rear suspension structure according to any one of claims 1 to 4.

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