JP2000177346A - Leaf suspension - Google Patents

Abstract

(57) [Summary] [Problem] To provide a leaf suspension with improved ride comfort and trackability and increased rigidity. SOLUTION: A leaf spring 12 made of synthetic resin having a substantially triangular cross section is formed, and the leaf spring 12 is disposed laterally and the opening surface is arranged in the front-rear direction of the vehicle. 14 is fixed to the knuckle 13 provided on the wheel 6 side, and the bottom portion 15 is fixed to the subframe of the vehicle body with U bolts. Further, a tension rod 28 is attached to the knuckle 13 to restrict the movement of the vehicle body in the front-rear direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leaf suspension having a leaf spring made of synthetic resin (reinforced fiber resin).

[0002]

2. Description of the Related Art Conventionally, a suspension using a leaf spring made of a synthetic resin (fiber reinforced plastic or FRP) has been known as a suspension for a four-wheeled vehicle (Japanese Patent Laid-Open No. 4-293607). FIG.
1 shows a vehicle suspension using the leaf spring 1. The leaf spring 1 is formed of a flat plate and a single piece.

[0005] One end 1a of the leaf spring 1 on the vehicle body side is held in the center of a sub-frame 4 made of synthetic resin or the like provided in the cutout 3 of the vehicle body frame 2, and the other end on the axle side. 1b is connected via a connection fitting 5 to a hub carrier (not shown) to which the axle of the wheels 6 is attached. The leaf spring 1 reduces vibration coming from the road surface.

When the above-mentioned leaf spring 1 is used in a four-wheeled vehicle, its load-stroke (flexure) characteristics are linear as shown in FIG. That is, the leaf spring 1 has a linear spring constant.

A FRP suspension arm and a rear suspension having the same are disclosed in JP-A-7-3.
JP-A-09-112112 discloses an example. The one disclosed in this publication is provided with a plate-shaped, FRP arm main body having one end fixed to a vehicle body and the other end connected to a wheel support member, and the arm main body is offset below a neutral plane. A friction member is disposed at a position, and the friction member extends in a manner inclined in the width direction of the arm body.

[0006]

In the prior art described above, it is necessary to set a high spring constant in order to suppress the movement (rolling) under a high load. However, when the spring constant is set high, there is a problem that ride comfort and followability to a road surface are impaired. In addition, since the leaf spring is flat, the rigidity of the plate in the torsion direction is low, such as wheels.
There is a problem that displacement due to external input becomes large.

In the device disclosed in Japanese Patent Application Laid-Open No. 7-309112, the lower arm has a single plate-like shape.
It is difficult to change the spring constant.

The present invention has been made in view of this point, and a leaf spring made of a synthetic resin is formed in a substantially triangular shape in a front view so that the spring constant is constant and the movement is small with a low load. At times, it is absorbed in the part with a low spring constant, and when the movement is large under a high load, it is absorbed in the part with a high spring constant to improve ride comfort and followability to the road surface, and increase rigidity. The purpose of the present invention is to provide an improved leaf suspension.

[0009]

According to the present invention, there is provided a synthetic resin leaf spring having a substantially triangular shape in a front view. The leaf spring has an apex mounted on the wheel side and a bottom surface fixed on the vehicle body.

According to a second aspect of the present invention, in the first aspect, the leaf spring is disposed horizontally and the opening surface is arranged in the front-rear direction of the vehicle. It is characterized in that a torque rod is provided in the vehicle front-rear direction.

According to a third aspect of the present invention, in the first aspect, the bottom surface of the leaf spring is fixed to a vehicle body with a U-bolt.

Further, according to a fourth aspect of the present invention, in the third aspect, a cushion member is interposed between the U-bolt and the bottom surface.

According to a fifth aspect of the present invention, in the fourth aspect, the U bolt is fastened vertically.

According to the present invention, the apex portion of the synthetic resin leaf spring having a substantially triangular shape as viewed from the front is fixed to the wheel side and the bottom portion is fixed to the vehicle body, so that a small stroke (small deflection) with a low load is achieved. In the case of (1), the top of the leaf spring having a low spring constant is bent, and in the case of a large load (large deflection) under a high load, the bottom of the leaf spring having a high spring constant is bent.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The main parts of an embodiment of the present invention will be described below with reference to FIGS. The leaf suspension 11 of the present invention includes a knuckle 1 provided with a leaf spring (lower arm) 12 made of a synthetic resin (FRP, fiber reinforced plastic) on the wheel 6 side.
3 attached. The leaf spring 12
Is formed in a substantially triangular shape when viewed from the front,
The apex 14
Is attached to the knuckle 13 and the bottom surface portion 15 is attached to the vehicle body or the sub-frame 16 (see FIGS. 4 and 5 described later).

The apex portion 14 of the leaf spring 12
As shown in FIG. 3, the knuckle 13 to which the side wall 18 is attached is attached to the surface of a single plate member 17.
8 is a top plate 19 welded to the upper surface. That is, the knuckle 13 is formed by attaching a U-shaped member having an opening to the lower side to the plate member 17. Then, the vertex portion 14 of the leaf spring 12 is fitted inside the U-shaped portion, and the collar 22 is inserted into the hole portion 20 provided in the vertex portion 14 and the hole portion 21 provided in the side wall portion 18, and a bolt 23 is inserted. , Washer 24 and nut 25.

A mounting bracket 27 for mounting a shock absorber 26 is provided on an upper surface of the top plate 19. Further, a mounting hole 29 for mounting a torque rod, for example, a tension rod 28 (see FIG. 1), which is a torque rod, for restricting movement of the vehicle body in the front-rear direction is provided in a lower portion of the plate member 17. Although the knuckle 13 is formed by welding, the plate member 17 and the U-shaped portion may be formed by integral molding instead.

The mounting of the leaf spring 12 on the vehicle body side is performed as shown in FIGS.
That is, the bottom portion 15 of the leaf spring 12 is brought into contact with the sub-frame 16, and the bolt hole 30 (see also FIG. 3) of the leaf spring 12 and the bolt hole 31 provided in the sub-frame 16 are inserted from the inside of the leaf spring 12. The U-bolt 32 is inserted therethrough, and the nut 33 is fixed by tightening the nut 33 from the sub-frame 16 side. Note that the bottom surface portion 15 of the leaf spring 12 may be directly attached to the vehicle body instead of the sub-frame 16.

When attaching the leaf spring 12 with the U bolt 32, a cushion member 34 such as synthetic rubber or synthetic resin is interposed between the U bolt 32 and the bottom surface portion 15. Thereby, the vibration absorption performance is improved. Also,
Since the cushion member 34 is provided with two steps 35, if the U bolt 32 is engaged with the steps 35,
The adhesion of the U bolt 32 can be improved.

When mounting the U bolt 32, the U bolt 32 is fastened vertically. That is, the U-bolt 32 is attached in the horizontal direction and the line connecting both ends is in the vertical direction. This is the top 1 of the leaf spring 12
4 receives an upward load, the leaf spring 12
This is to prevent the lower part from being pulled too much and warped. Further, by using the U bolt 32, the nut 25 can be screwed from the sub-frame 16 side, and the mounting property is improved.

Next, the operation of the embodiment will be described. When the load applied to the leaf suspension 11 is small and the stroke amount is small, the top 1
The 4 (low rigid part) side flexes to absorb the movement. FIG. 6 shows a normal mounting state of the leaf suspension 11, and FIG.
The figure shows a position where the object moves and is displaced. Since the leaf spring 12 has a substantially triangular shape in a front view, the rigidity is lower and the spring constant is lower toward the distal end of the apex portion 14. Therefore, the ability to follow the road surface is improved, and the riding comfort is good.

When the load applied to the leaf suspension 11 is large and the stroke amount is large, the portion from the top portion 14 to the bottom portion (wide side) 15 of the leaf spring 12 simultaneously bends to absorb the movement (rolling). . FIG. 8 shows a state in which the leaf suspension 11 is largely moved and displaced.

As described above, the bottom portion 15 of the leaf spring 12, which is substantially triangular in a front view, has high rigidity and a high spring constant. Therefore, a large movement (rolling) with a high load is suppressed, and the stability is improved. When the leaf spring 12 is formed in a substantially triangular shape in a front view, the load-stroke characteristic becomes non-linear (curved) as shown in FIG. Thus, the leaf spring 12 of the present embodiment
Has a non-linear spring constant so that it can cope with both small and large movements.

Further, by forming the leaf spring 12 in a substantially triangular shape when viewed from the front, the rigidity of the single plate in the torsional direction, the rigidity with respect to the input from the lateral direction of the plate, and the external input from the wheels are obtained. The rigidity against displacement is improved, and the steering stability performance of the vehicle can be enhanced.

[0025]

Since the present invention is a leaf suspension configured as described above, according to the invention described in claims 1 to 5, when the load is small and the stroke is small (the deflection is small). The vertex of the leaf spring having a substantially triangular shape in a front view is bent, the spring constant is low, and the followability to the road surface is improved, so that the riding comfort can be improved. In addition, when the load is large and the stroke is large (the deflection is large), the rear end of the leaf spring also bends and the spring constant is high, so that large movement (rolling) of the vehicle can be suppressed, and the stability can be improved. it can.

Further, since the leaf spring is formed in a substantially triangular shape when viewed from the front, rigidity in the torsion direction of the plate as in the conventional case can be improved.
The rigidity of the board against input from the lateral direction and the rigidity against displacement due to external input from wheels can be improved, and the steering stability performance of the vehicle can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a main part of an embodiment of the present invention.

FIG. 2 is a perspective view of the leaf spring shown in FIG.

FIG. 3 is an exploded perspective view of a knuckle to which a vertex of the leaf spring shown in FIG. 2 is attached.

FIG. 4 is a cross-sectional view showing a mounting state of a bottom portion of the leaf spring of FIG. 2;

FIG. 5 is a partial sectional view taken along line AA of FIG.

FIG. 6 is a schematic diagram of a normal state of a wheel to which the leaf suspension of the present invention is attached.

FIG. 7 is a schematic view showing a state where a leaf spring shown in FIG. 6 receives a small impact load and a leaf spring is deformed.

FIG. 8 is a schematic diagram showing a state where the leaf suspension shown in FIG. 6 receives a large impact load and a leaf spring is largely deformed.

FIG. 9 is a graph showing load-stroke characteristics of the leaf suspension of the present invention.

FIG. 10 is a perspective view of a vehicle suspension equipped with a conventional leaf spring.

FIG. 11 shows the load of the vehicle suspension shown in FIG.
It is a figure of a stroke characteristic.

[Explanation of symbols]

 Reference Signs List 6 wheels 11 leaf suspension 12 leaf spring 14 apex 15 bottom 16 subframe 28 tension rod 32 U bolt 34 cushion member

Claims (5)

[Claims] 1. A leaf suspension comprising: a synthetic resin leaf spring having a substantially triangular shape in a front view; a vertex portion of the leaf spring attached to a wheel side; and a bottom portion fixed to a vehicle body side. 2. The leaf suspension according to claim 1, wherein the leaf spring is disposed laterally and the opening surface is arranged in the front-rear direction of the vehicle, and a torque rod is provided in the vehicle front-rear direction. . 3. The leaf suspension according to claim 1, wherein a bottom surface of the leaf spring is fixed to a vehicle body with a U-bolt. 4. The leaf suspension according to claim 3, wherein a cushion member is interposed between the U-bolt and the bottom surface. 5. The leaf suspension according to claim 4, wherein said U-bolt is fastened vertically.