JPH0669778B2 - Suspension device for automobile - Google Patents

Description

TECHNICAL FIELD The present invention relates to a suspension device for an automobile.

[Prior Art] In automobiles, there is a demand to lower the floor surface as much as possible in order to increase the space such as the rear seats, the trunk room, or the luggage compartment. The top and bottom width of the must be as small as possible.

Therefore, while supporting the wheel at the rear end of the trailing arm extending in the front-rear direction of the vehicle body, a torsion bar spring extending inward in the vehicle width direction is adopted as a buffer member between the trailing arm and the vehicle body instead of the coil spring. Conventionally, a suspension device including the above is known.

However, in that case, there is a problem in that the torsion bar spring interferes with a member such as a main side frame extending in the front-rear direction of the vehicle body, which makes it difficult to make an arrangement.

On the other hand, in place of the above-mentioned torsion bar spring, a leaf spring that extends in the vehicle front-rear direction behind the trailing arm is adopted, and the rear end of this leaf spring is fixed and attached to the vehicle body, and the front end of the leaf spring and the trailing A suspension device in which the rear end of an arm is linked to an axle has been proposed (see Japanese Utility Model Laid-Open No. 57-159809).

However, in the above suspension device, in order to secure the lateral rigidity of the trailing arm and reduce the rolling of the vehicle body sufficiently, it is necessary to form the trailing arm in a wide width. And the side sills interfere with each other, and the difficulty of the arrangement under the floor of the vehicle body cannot be eliminated.

[Object of the Invention] The present invention has been made in view of the above problems, and an object of the present invention is to provide a suspension device having a small lateral width suitable for a low-floor vehicle.

[Structure of the Invention] Therefore, the vehicle suspension device according to the present invention is
It is arranged along the vehicle front-rear direction between the side frame and the side sill extending in the vehicle front-rear direction, and the middle part in the vehicle body front-rear direction is swingable on the shaft member whose both ends are fixed to the side frame and the side sill. And a trailing arm having a wheel rotatably attached to one end thereof, and an end on the trailing arm side is linked to the other end of the trailing arm, and the trailing arm extends from the other end. A leaf spring that extends approximately on the same line as the arm and has its end on the side opposite the trailing arm rotatably attached to at least one of the side frame and side sill, and fixed to at least one of the side frame and side sill And a supporting member for supporting the lower surface of the leaf spring between both ends of the leaf spring. It is set to.

With the above configuration, when the wheel moves upward (during bumping), a downward moment is applied to the leaf spring about its end on the side opposite to the trailing arm (attachment point to the vehicle body). The leaf spring is pressed by the lower surface of the middle portion thereof abutting against the supporting member, and is bent downward with the contact point as a fulcrum, thereby generating a relatively large cushioning force. On the other hand, when the wheel moves downward (when rebounding), an upward moment is applied to the leaf spring centering on the end portion on the side opposite to the trailing arm, and the leaf spring has the end on the side opposite the trailing arm. It comes to freely rotate upward with the section as a fulcrum.

[Advantages of the Invention] In the present invention, the suspension device can have a linear structure along the vehicle body front-rear direction, and both ends of the trailing arm in the vehicle body front-rear direction are fixed to the side frame and the side sill. Since it is pivotally supported by the shaft member, it is possible to prevent lateral rolling due to the sandwiching effect and to secure the lateral rigidity of the trailing arm, and therefore it is not necessary to form the trailing arm in a wide width. Therefore, since the suspension device can be arranged between the side frame and the side sill, the floor of the vehicle body can be lowered without interfering with the suspension device, and the flexibility of the vehicle body layout is improved.

Further, according to the present invention, the supporting member for supporting the lower surface of the leaf spring between both ends of the leaf spring is fixedly provided on at least one of the side frame and the side sill. You can change the fulcrum. That is, as described above, when the wheel moves upward (during bumping), the leaf spring is acted on by a downward moment centered on the end portion on the side opposite to the trailing arm (attachment point to the vehicle body side). The leaf spring is pressed by the lower surface of the middle portion thereof abutting against the supporting member, and is bent downward with the contact point as a fulcrum, thereby generating a relatively large cushioning force. On the other hand, when the wheel moves downward (when rebounding), an upward moment is applied to the leaf spring centering on the end portion on the side opposite to the trailing arm, and the leaf spring has the end on the side opposite the trailing arm. It freely rotates upward with the portion as a fulcrum. In this case, generally, the cushioning force due to the spring force of the leaf spring does not act. Even if the rebound speed is faster than the rotation speed of the leaf spring and some spring force is generated, in that case, the effective length of the leaf spring as a spring is equal to its total length, and the spring constant is higher than that at the time of bumping. Will be lower. In other words, the spring constant of the leaf spring can be changed so as to be considerably high during bumping and to be low during rebounding (including the case where no spring force acts), and the spring characteristics that are suitable for vertical movement of the wheel respectively. Will be able to be granted.

[Embodiment] Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

That is, FIGS. 1 and 2 are a schematic side view and a schematic plan view, respectively, of a rear suspension device for an automobile to which the present invention is applied. In both figures, the rear suspension device 1 includes a rear end portion 4b of an axle 2 of a rear wheel 12. Is rotatably supported at the front end
A trailing arm 4 extending in the vehicle front-rear direction is swingably supported by a horizontal shaft 3 in the vehicle width direction in the vicinity of 4a (that is, a middle portion in the vehicle front-rear direction) and a front end of the trailing arm 4. The rear end portion 5b is linked to the portion 4a, and extends substantially collinear with the trailing arm 4 toward the front of the vehicle body.
A GFRP (glass
A relatively short leaf spring 5 made of fiber reinforced plastic, a support member 6 fixed to the vehicle body side and supporting the lower surface of the leaf spring 5 between the front and rear end portions 5a and 5b of the leaf spring 5, and a lower end portion. 7b is connected to the trailing arm 4, and the upper end 7a is basically constituted by a vehicle height adjusting air spring 7 connected to the vehicle body side.

The trailing arm 4 and the leaf spring 5 are
It is arranged in the underfloor space between the main side frame 8 and the side sill 9 extending in the vehicle front-rear direction, and the side sill 9 supports the tire house 10 in the front and rear. A tire wheel 12 and an air spring 7 are housed in the tire house 10. The tire wheel 12 is supported by the rear axle 2 via a disc wheel 13.
A floor panel (not shown) is installed on the main side frame 8.

The air spring device 7 includes a bottomed cylindrical outer cylinder 14 and the outer cylinder 14
An inner cylinder 15 slidably fitted therein, a cylinder 16 is fixedly mounted in the inner cylinder 15, while a guide rod 17 fitted to the cylinder 16 is provided from the bottom of the outer cylinder 14. In addition, an air spring is configured by compression and expansion of air enclosed in a chamber 14A formed between the outer cylinder 14 and the inner cylinder 15.

A vertical flange 18 extending upward is formed at the outer end of the trailing arm 4, and a substantially L-shaped flange 19 extending outward from the outer end in the vehicle width direction and then bent upward is formed. Boss portions 21 and 22 are concentrically provided on opposite side surfaces of both flanges 18 and 19, respectively. The air spring device 7
The lower end of the cylinder 16 is rotatably connected to a pin 23 in the vehicle width direction that fits into the bosses 21 and 22, while the upper end boss 30 of the outer cylinder 14 is pivoted to the tire house 10 by a hinge pin 31. Can be freely connected. The champer 14A communicates with an air pressure adjusting mechanism (not shown) for adjusting the vehicle height.

The horizontal shaft 3 rotatably penetrates a circular hole 24 provided at the front end 4a of the trailing arm 4 and has small-diameter portions 3a, 3a at both ends thereof.
Is a tubular bush 26,27 with a bottom through an annular rubber 25,25.
It is supported by. The bushes 26, 27 are fixed to the main side frame 8 and the side sill 9 via brackets 28, 29, respectively.

An annular portion for connection is provided at the front and rear ends of the leaf spring 5.
5a, 5b are formed, and the rear end annular portion 5b is fitted in the notch 31 at the front end of the trailing arm 4 and is pivotally attached to the opposing overhanging portions 31a, 31a of the trailing arm 4 by the pin 32. . On the other hand, the front end annular portion 5a of the leaf spring 5 is rotatably connected to a bracket 34 on the outer surface of the main side frame 8 via a shackle 33.

The support member 6 has an L-shaped bracket 35 whose upper end is bolted to the outer surface of the main side frame 8, and a pair of front and rear vehicle bodies which are parallel to each other are provided on the bottom 35a of the bracket 35 as shown in FIG. Plates 36, 37 extending in the direction are erected and reinforced by a pair of reinforcing plates 38, 38, 39, 39 in the vehicle width direction. Support bolt 41 is on both plates 36, 37
The vertical portion 35b of the bracket 35 penetrates in the vehicle width direction, and is screwed into the nut 42 inside the bracket 35. The support bolt 41 is inserted into a pair of oil-impregnated bearings 43, 44 between the plates 36, 37, and the oil-impregnated bearings 43, 44 are supported by the support bolt 41 so that their annular flange portions 43a, 44a are of the plates 36, 37. It abuts the side. A roller 45 made of steel is fitted around the oil-impregnated bearings 43, 44, and the roller 45 made of steel abuts and supports the lower surface of the leaf spring 5 between both ends of the leaf spring 5.

In the above configuration, if you want to adjust the vehicle height,
The chamber 14A in the air spring 7 is controlled by the air pressure adjusting mechanism.
The vehicle height can be adjusted by adjusting the air pressure of and the degree of expansion and contraction of the air spring 7. That is, when the air pressure in the chamber 14A is increased, the air spring 7 is extended and the vehicle height is increased. On the other hand, when the air pressure in the chamber 14A is lowered, the vehicle height is lowered.

Next, the operation of the trailing arm 4 will be described. When the tire wheel 12 (FIG. 1) moves up and down, the trailing arm 4 swings around the horizontal shaft 3, and the impact due to the swinging of the trailing arm 4 is buffered by the leaf spring 5 and the air spring 7.

Now, focusing on the leaf spring 5, the cushioning action will be described. When the tire wheel 12 moves upward relative to the vehicle body (during bumping), the trailing arm 4 swings counterclockwise in FIG. Then, accordingly, the leaf spring 5 restricts the upward movement of the tire wheel 12 while bending downward with the roller 45 of the supporting member 6 as a fulcrum. In this case, since only the portion of the leaf spring 5 behind the roller 45 is bent, the swing of the trailing arm 4 is buffered by the leaf spring 5 with a relatively large spring constant during pumping.

On the other hand, when the tire wheel 12 moves downward relative to the vehicle body (at the time of rebound), the trailing arm 4 swings clockwise about the horizontal shaft 3, and the leaf spring 5 accordingly moves the shackle shaft. In this case, the cushioning force by the spring force of the leaf spring 5 generally does not act on the trailing arm 4 because it freely rotates upward with 33a as a fulcrum. Even if the rebound speed is faster than the rotation speed of the leaf spring 5 and some spring force is generated, in that case, the effective length of the leaf spring 5 as a spring is equal to its entire length, and compared with the time of bumping. The spring constant is low.

According to the present embodiment, (i) the vicinity of the front end portion 4a of the trailing arm 4 (that is, the middle portion in the vehicle front-rear direction) is pivotally supported by the horizontal shaft 3 having both ends fixed to the main side frame 8 and the side sill 9. Therefore, the rolling of the vehicle body can be effectively reduced, and it is not necessary to form the trailing arm 4 in a wide width. Therefore, even in a low floor type vehicle, the main side frame 8 and the side sill 9 below the floor of the vehicle body do not interfere with the trailing arm 4 with other members.
It can be easily placed in the space between.

(Ii) Since the lower surface of the leaf spring 5 between both ends of the leaf spring 5 is supported by the support member 6, the leaf spring 5 bends downward with the support member 6 as a fulcrum at the time of bumping, while at the time of rebounding, the shackle shaft 33a. With this as a fulcrum, the leaf spring 5 can be freely rotated upward, and the spring constant of the leaf spring 5 can be changed during bumping and rebounding. In other words, the spring constant of the leaf spring 5 can be changed so as to be considerably high at the time of bumping and to be low at the time of rebounding (including the case where no spring force acts), which is suitable for vertical movement of the axle. The spring characteristic can be given.

(Iii) Since the leaf spring 5 is formed of GFRP, it is possible to obtain sufficient elasticity with a shorter length than the conventional metal leaf spring, and thereby it is possible to shorten the front-rear width of the rear suspension device 1. become.

The present invention is not limited to the above-described embodiment, and for example, the air spring 7 may be omitted, or the front end portion 4a of the trailing arm 4 and the rear end annular portion 5b of the leaf spring 5 may be connected via a shackle. At the same time, the front annular portion 5a of the leaf spring 5 can be freely pivoted directly on the bracket 34 and the like.

[Brief description of drawings]

1 and 2 are a schematic side view and a schematic plan view of a rear suspension device for an automobile to which the present invention is applied, respectively, and FIG. 3 is an enlarged sectional schematic view taken along the line AA in FIG. 4 ... Trailing arm, 5 ... Leaf spring,
6 ... Support member.

Claims (1)

[Claims] 1. A vehicle body front-rear direction is arranged between a side frame and a side sill extending in a vehicle body front-rear direction,
A trailing arm in which a middle portion in the vehicle front-rear direction is swingably supported by a shaft member having both ends of the side frame and the side sill fixed, and wheels are rotatably attached to one end, and the trailing arm is provided. An end portion on the arm side is linked to the other end portion of the trailing arm, extends from the other end portion on substantially the same line as the trailing arm, and an end portion on the side opposite to the trailing arm is at least one of a side frame and a side sill. A leaf spring rotatably attached to one of the leaf springs, and a support member fixed to at least one of the side frame and the side sill and supporting the lower surface of the leaf spring between both ends of the leaf spring. Suspension device for automobile characterized by.