JPH06106931A - Suspension for vehicle - Google Patents

Abstract

PURPOSE:To improve stability of a vehicle at turn braking time and a responsive feeling of a handle at turning time. CONSTITUTION:A suspension has a lower arm 22 pivotally supported to a car body by elastic joints 26, 28 in two internal ends placed with a space in a vehicle longitudinal direction and pivotally supported to the lower end of a carrier 10 in the external end. The joint 28 in a vehicle rear side has inner and outer tubes 34, 36, concentrically arranged relating to a center axial line 32 extended in a vertical direction, and a rubber bush 38 interposed between these inner and outer tubes. A distance between an external surface of the inner tube and an internal surface of the outer tube is set in both end parts smaller than in the central, part along the center axial line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension of a vehicle such as an automobile, and more particularly, to a lower arm pivotally supported on a vehicle body through elastic joints at two inner ends spaced from each other in the front-rear direction. Related to suspension including.

[0002]

2. Description of the Related Art As one of suspensions for vehicles such as automobiles, a carrier that rotatably supports wheels, as described in, for example, Japanese Utility Model Laid-Open No. 61-91408,
An L-shaped lower arm pivotally supported on the vehicle body by elastic joints at two inner ends that are pivotally attached to the lower end of the carrier at the outer ends and are spaced apart from each other in the vehicle front-rear direction; The elastic joint provided at the inner end on the side is an inner cylinder concentrically arranged with respect to the central axis extending in the vertical direction and fixed to the vehicle body, and the inner end on the vehicle rear side of the lower arm extending concentrically with the inner cylinder. BACKGROUND ART A suspension having an outer cylinder fixed to an outer cylinder and a rubber bush interposed therebetween is well known in the art.

According to such a suspension, as compared with a structure in which both of the two inner ends of the lower arm are pivotally supported by the vehicle body through elastic joints having central axes extending in the vehicle front-rear direction, The front-rear compliance can be increased, which can improve the riding comfort of the vehicle.

[0004]

However, in the conventional suspension as described above, the spring constant of the elastic joint provided at the vehicle rear side inner end of the lower arm is set to be low so that the longitudinal compliance of the suspension is high. Therefore, when a force to the rear of the vehicle acts on the outer end of the lower arm due to the braking force during braking of the vehicle and the component of the cornering force in the vehicle front-rear direction during turning of the vehicle, the lower arm will move to the inner end on the front side of the vehicle. Pivots around the car relatively easily, and the caster angle and the amount of caster trail reduction are relatively large, so the stability of the vehicle during braking and the straight running performance are likely to deteriorate, and the handling of the steering wheel is good when turning. There is a problem that the feeling tends to deteriorate.

In view of the above-mentioned problems in the conventional suspension having the L-shaped lower arm, the present invention is superior to the conventional one in the stability of the vehicle during turning braking, and in the feeling of the steering wheel during turning. The purpose is to provide a vehicle suspension.

[0006]

According to the present invention, the above object is to provide a carrier that rotatably supports a wheel and an outer end of the carrier that is pivotally attached to the lower end of the carrier at least in the longitudinal direction of the vehicle. A lower arm pivotally supported by the vehicle body through elastic joints at two spaced apart inner ends, and one of the elastic joints is arranged concentrically with respect to a central axis extending substantially in the vertical direction. An inner cylinder and an outer cylinder and a rubber bush interposed therebetween, one of the inner cylinder and the outer cylinder is fixed to the vehicle body, and the other of the inner cylinder and the outer cylinder is the lower arm. Achieved by a vehicle suspension fixed to one inner end, characterized in that the distance between the outer surface of the inner cylinder and the inner surface of the outer cylinder is smaller at both end portions than at the central portion along the central axis. To be done.

[0007]

According to the above construction, when the lower arm pivots upward around the inner end of the wheel when the wheel bounces, the rubber bush of one elastic joint causes the upper end of the outboard side and the inboard side of the central axis. When the lower arm pivots downward around its inner end due to strong compression at the lower end of the wheel and when the wheel rebounds, the rubber bush of one elastic joint causes the lower bushing on the outboard side of the central axis and By being strongly compressed at the upper end on the inboard side, the spring constant of the rubber bush as a whole increases relatively rapidly, which makes it difficult for the lower arm to pivot around the other elastic joint in the vehicle longitudinal direction. Therefore, even if a force toward the rear of the vehicle is applied to the outer end of the lower arm, the caster angle and the reduction amount of the caster trail are small,
This improves the stability of the vehicle during turning braking,
In addition, the handle feel when turning is improved.

Further, according to the above-mentioned structure, the distance between the inner cylinder and the outer cylinder of the one elastic joint is reduced over the entire length thereof, and the thickness of the rubber bush is reduced, so that the spring constant of the elastic joint is reduced. Since it is not raised over the
The front and rear compliance of the suspension is not compromised when the wheels are in the neutral position.

[0009]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view showing one embodiment of a vehicle suspension constructed as a MacPherson strut suspension according to the present invention, and FIG. 2 is an enlarged plan view showing an L-shaped lower arm of the embodiment shown in FIG. Is.

In these figures, 10 indicates a carrier for rotatably supporting the wheel 12. A lower end of a MacPherson strut 18 including a shock absorber 14 and a suspension spring 16 is connected to the upper end of the carrier 10, and the upper end of the MacPherson strut 18 is pivotally supported by an upper support 20 on a vehicle body not shown in FIG. ing.

An outer end of a lower arm 22 is pivotally attached to a lower end of the carrier 10 by a ball joint 24. Inner ends of the lower arm 22 separated from each other in the vehicle front-rear direction are pivotally supported by the vehicle body by elastic joints 26 and 28. The lower arm 22 is an L-shaped lower arm in the illustrated embodiment, and the joint 26 is a ball joint 24.
And the joint 28 is separated from the joint 26 toward the rear of the vehicle.

The joint 26 has a central axis 30 extending in the longitudinal direction of the vehicle, and the joint 28 has a central axis 32 extending in the vertical direction.
They intersect each other at the center of 8. As shown in FIGS. 2 and 3, the joint 28 extends vertically along the central axis 32 and is fixed to the vehicle body by bolts and nuts (not shown). On the other hand, it has an outer cylinder 36 arranged concentrically and fixed to the inner end of the lower arm 22 on the vehicle rear side, and a rubber bush 38 interposed between the inner cylinder and the outer cylinder.

In particular, in the first embodiment shown in FIGS. 2 and 3, the inner cylinder 34 has a cylindrical shape extending along the axis 32, while the outer cylinder 36 is a wheel. When viewed in the neutral position, the cylindrical central portion 36a extends along the axis 32 and the curved end portions 36 located above and below the central portion 36a.
b and 36c. Ends 36b and 36c
Respectively have a portion curved inward in the radial direction toward the outer end and a portion curved slightly outward in the radial direction toward the outer end, whereby a portion between the outer surface of the inner cylinder and the inner surface of the outer cylinder is formed. The distance is set smaller at both ends than at the center.

In the illustrated first embodiment, if the lower arm 22 pivots upward about the central axis 30 by the angle θ due to the wheel bouncing, as shown in FIG. 3 (b). The outer cylinder 36 also pivots about the center of the joint 28 relative to the inner cylinder 34 in the counterclockwise direction by an angle θ.
On the contrary, when the lower arm 22 pivots downward about the central axis 30 due to the rebound of the wheels, the outer cylinder 36 also rotates relative to the inner cylinder 34 around the center of the joint 28 in the clockwise direction as viewed in FIG. Pivot.

Therefore, the rubber bush 38 is strongly compressed at the upper end on the outboard side of the inner cylinder 34 and at the lower end on the inboard side of the inner cylinder when the wheel bounces, and at the outboard side of the inner cylinder when the wheel rebounds. The rubber bush 38 is strongly compressed at the lower end and the upper end on the inboard side of the inner cylinder, whereby the lower arm 22 is pivoted rearward of the vehicle around the center of the joint 26.
As shown in FIG. 4, the spring constant as a whole increases gradually as the pivot angle θ of the lower arm increases, and the increase rate also gradually increases as the angle θ increases. 4 is larger than the conventional case shown by the broken line.

In other words, the lower arm 22 bounds,
As the pivot angle in the rebound direction increases, the front-rear compliance of the suspension decreases relatively sharply, and it becomes difficult for the lower arm 22 to pivot around the joint 26 in the front-rear direction. Therefore, as the bounce amount and the rebound amount of the wheel increase, That is, as the pivot angle θ of the lower arm increases, the caster angle and the reduction amount of the caster trail decrease.

FIGS. 5 and 6 respectively show the joint of the rear inner end of the lower arm in the second and third embodiments of the suspension according to the present invention when the wheel is in the neutral position (a) and when the wheel bounces. It is an expanded longitudinal cross-sectional view showing the case (b). In these figures, the parts corresponding to the parts shown in FIG. 3 are designated by the same reference numerals as those shown in FIG.

In the second embodiment shown in FIG. 5, the outer cylinder 36 has a cylindrical shape extending along the axis 32 when the wheel is in the neutral position. The inner cylinder 34 has a small-diameter central portion 34a and large-diameter end portions 34b and 34c. Each of the end portions 34b and 34c has a tapered portion whose diameter gradually increases toward the outer end and a portion whose diameter is substantially constant, whereby the inner cylinder 34 is formed.
The distance between the outer surface of the outer cylinder and the inner surface of the outer cylinder 36 is set to be smaller at both end portions than at the central portion.

In the third embodiment shown in FIG. 6, both the inner cylinder 34 and the outer cylinder 36 are cylindrical, but rubber bushes 38 are formed on the inner peripheral surfaces of both ends of the outer cylinder. Rings 40a and 4 made of a material having a spring constant much higher than that of the rubber constituting the rubber or a substantially rigid material.
0b is fixed. Illustrated rings 40a and 40b
The inner diameter of the ring is set to be the smallest in the central portion in the longitudinal direction, so that these rings can be attached to the outer cylinder 36.
Functioning in the same manner as the radially inwardly curved ends of the outer cylinder of the first embodiment, the distance between the outer surface of the inner cylinder and the substantially inner surface of the outer cylinder is It is set to be smaller at both ends than at the center.

Therefore, also in the second and third embodiments, the front-rear compliance of the suspension is relatively sharply reduced as the pivoting angle of the lower arm 22 in the bounding and rebounding directions increases, and the lower arm 22 is connected to the joint 26. Since it becomes difficult to pivot around in the front-rear direction, the caster angle and the caster trail decrease amount decrease as the wheel bounce amount and the rebound amount increase, that is, as the lower arm pivot angle θ increases.

Thus, according to the illustrated embodiments, it is possible to reduce the caster angle and the reduction amount of the caster trail when the wheel bounces and rebounds.
As compared with the case of the conventional suspension having the L-shaped lower arm, the stability of the vehicle at the time of turning braking can be improved and the feeling of the steering wheel at the time of turning can be improved. Further, a joint 2 provided at the inner end of the lower arm on the rear side of the vehicle
8 does not increase the spring constant of the rubber bush 38 over its entire length, and the front-rear compliance of the suspension is not impaired when the wheel is substantially in the neutral position. It is possible to avoid the deterioration of the vehicle and the deterioration of the riding property of the vehicle.

Although the present invention has been described above in detail with reference to specific embodiments, the present invention is not limited to these embodiments, and various other embodiments within the scope of the present invention. It will be apparent to those skilled in the art that

For example, in the illustrated embodiment, the inner cylinder 34 is fixed to the vehicle body and the outer cylinder 36 is fixed to the inner end of the lower arm. However, the inner cylinder is fixed to the inner end of the lower arm and the outer cylinder is fixed to the vehicle body. May be fixed to. Further, for example, by combining the first or third embodiment and the second embodiment, both ends of both the outer cylinder and the inner cylinder may be curved inward in the radial direction to set a large diameter. . Further, rings similar to the rings 40a and 40b in the third embodiment may be fixed to the outer surfaces of both ends of the inner cylinder 34, and both the outer surfaces of both ends of the inner cylinder and the inner surfaces of both ends of the outer cylinder may be fixed. May be fixed to.

Further, in the illustrated embodiment, the joint structure of the present invention is applied to the pivot portion of the inner end of the lower arm on the vehicle rear side, but the joint structure of the present invention is applied to either of the two inner ends. It may be applied, in particular, it is preferably applied to the inner end of the two inner ends of the lower arm on the side where the distance in the vehicle front-rear direction between the outer end and the outer end is large, for example, the inner end of the lower arm on the vehicle rear side is When the inner end on the vehicle front side is substantially laterally aligned with the outer end and the inner end on the vehicle front side is separated from the inner end on the vehicle rear side toward the vehicle front side, the joint of the present invention is applied to the inner end on the vehicle front side. Structures may be applied.

Further, in the above embodiment, the lower arm is L
Although it is a lower arm of a type, the lower arm may be an arm of type A, and the suspension of the present invention is not limited to the MacPherson strut suspension, and may be configured as a double wishbone suspension, for example. Is.

[0027]

As is apparent from the above description, according to the present invention, when the lower arm pivots upward around the inner end of the wheel due to the bouncing and rebounding of the wheel, the entire rubber bushing increases as the pivoting angle increases. As the spring constant of the lower arm increases relatively rapidly, and this makes it difficult for the lower arm to pivot around the other elastic joint in the vehicle front-rear direction, the caster when a rearward force acts on the outer end of the lower arm. It is possible to reduce the amount of reduction in the corners and caster trails, which improves the stability of the vehicle during turning braking and improves the feel of the steering wheel during turning.

Further, according to the present invention, the distance between the inner cylinder and the outer cylinder of the one elastic joint is reduced over the entire length thereof, and the thickness of the rubber bush is reduced, so that the spring constant is extended over the entire length. Since the height is not increased, the front-rear compliance of the suspension is not impaired when the wheels are in the neutral position, and thus it is possible to avoid deterioration of the riding comfort of the vehicle during normal running of the vehicle.

[Brief description of drawings]

FIG. 1 is a perspective view showing one embodiment of a vehicle suspension according to the present invention configured as a MacPherson strut suspension.

FIG. 2 is an enlarged plan view showing an L-shaped lower arm of the embodiment shown in FIG.

FIG. 3 shows a joint provided at the rear inner end of the lower arm of the first embodiment shown in FIG. 2 when the wheel is in a neutral position (a) and when the wheel bounces (b). FIG. 3 is an enlarged vertical sectional view taken along the line III-III in FIG. 2.

FIG. 4 is a vertical spring angle of the lower arm and a spring constant as a whole of an elastic joint on the rear side of the vehicle when viewed in a direction in which the lower arm pivots in a front-rear direction around a joint on the front side of the vehicle. 3 is a graph showing the relationship between

FIG. 5 is an enlarged view showing a joint provided at the rear inner end of the lower arm of the second embodiment of the suspension according to the present invention when the wheel is in the neutral position (a) and when the wheel is bound (b). FIG.

FIG. 6 is an enlarged view showing a joint provided at a rear inner end of a lower arm of a suspension according to a third embodiment of the present invention when the wheel is in a neutral position (a) and when the wheel is bound (b). FIG.

[Explanation of symbols]

 10 ... Carrier 18 ... MacPherson strut 22 ... Lower arm 24 ... Ball joint 26, 28 ... Elastic joint 34 ... Inner cylinder 36 ... Outer cylinder 38 ... Rubber bush

Claims (1)

[Claims] 1. A vehicle body that rotatably supports wheels, and a vehicle body through elastic joints at two inner ends pivotally attached to the lower end of the carrier at the outer ends thereof and separated from each other at least in the vehicle front-rear direction. A lower arm pivotally supported on one side, and one of the elastic joints is provided with an inner cylinder and an outer cylinder arranged concentrically with respect to a central axis extending substantially in the vertical direction, and a rubber interposed therebetween. A bush, one of the inner cylinder and the outer cylinder is fixed to the vehicle body, the other of the inner cylinder and the outer cylinder is fixed to one inner end of the lower arm, and the outer surface of the inner cylinder and the outer cylinder A vehicle suspension characterized in that the distance from the inner surface of the cylinder is smaller at both end portions than in the central portion along the central axis.