JPH0585116A - Double wishbone type suspension - Google Patents

Abstract

PURPOSE:To improve ride comfortability against harshness or the like, and reduce the steering changes during acceleration/deceleration. CONSTITUTION:A double wishbone type suspension is provided with a torsion member 16 which is fixed to a vehicle body 18 at the upper and the lower ends and elastically twisted around the axial line 20, and an upper and a lower brackets 22, 24 which are fixed to the torsion member. An upper arm 26 is pivotably fixed by a carrier 10 at the outer end, and pivotably supported by the vehicle body at the inner end on the fore side, and pivotably supported at the tip of the upper bracket at the inner end on the rear side, while a lower arm 28 is pivotably fixed by the carrier at the outer end and pivotably supported by the vehicle at the inner end on the fore side, and pivotably supported at the tip of the lower bracket at the inner end on the rear side. The upper bracket is longer than the lower bracket.

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 double wishbone type suspension.

[0002]

2. Description of the Related Art As one of the double wishbone type suspensions for vehicles such as automobiles, for example, Japanese Patent Laid-Open No. 2-7
As described in Japanese Patent No. 7310, a double-wishbone type suspension in which the inner ends of the upper arm and the lower arm, which are A-type arms, on the vehicle rear side are pivotally supported by the vehicle body through a torsion member extending in the vertical direction is disclosed. It is already known from the past.

FIG. 3 is a perspective view showing a suspension equivalent to the suspension described in the above publication as a skeleton diagram. In FIG. 3, the shock absorber and the suspension spring are omitted.

In FIG. 3, reference numeral 10 denotes a carrier that rotatably supports a wheel 12 around a spindle 14, and 16 is fixed to a vehicle body 18 at an upper end and a lower end, and an axis line 2 is provided.
A torsion member elastically twisted around 0 is shown. An upper bracket 22 and a lower bracket 24, which are vertically spaced from each other, are fixed to the torsion member 16, and these brackets extend from the torsion member toward the front of the vehicle and in the inboard direction. Further, in FIG. 4, reference numerals 26 and 28 respectively denote an upper arm and a lower arm. Each of the upper arm and the lower arm is an A-shaped arm having one outer end and two inner ends spaced apart from each other in the vehicle front-rear direction.

The upper arm 26 is pivotally attached to the upper end of the carrier 10 by a ball joint 30 at its outer end, pivotally supported on the vehicle body 18 by a joint 32 including a rubber bush at its front inner end, and at its rear inner end. Ball joint 34
Is pivotally attached to the tip of the upper bracket 22. Similarly, the lower arm 28 is pivotally attached to the lower end of the carrier 10 by a ball joint 36 at the outer end, is pivotally supported on the vehicle body 18 by a joint 38 including a rubber bush at the inner end on the front side, and has a ball at the inner end on the rear side. The joint 40 is pivotally attached to the tip of the lower bracket 24.

In such a suspension, when the wheel bounces and rebounds, the upper arm 26 pivots about a straight line 42 connecting the center of the joint 32 and the center of the ball joint 34, and the lower arm 28 moves to the center of the joint 38. It pivots about a straight line 44 connecting the center of the ball joint 40. When longitudinal force acts on the wheel, the torsion member 16 is elastically twisted around the axis 20 and the ball joints 34 and 40 are displaced in the lateral direction of the vehicle, so that the upper arm and the lower arm rotate around the joints 32 and 38, respectively. And the ball joints 30 and 36 are displaced rearward of the vehicle to ensure the longitudinal compliance of the suspension.

[0007]

Generally, in vehicles such as automobiles, as is well known, in order to reduce the change in steering caused by longitudinal force acting on the grounding point of the wheel during acceleration / deceleration, the grounding point of the wheel is to be reduced. The front-rear compliance at the wheel center is preferably a low value, and conversely, the front-rear compliance at the wheel center is a high value in order to improve the riding comfort with respect to the harshness etc. in which the front-rear force acts on the wheel center. Is preferred.

However, in the conventional double wishbone suspension in which the above-mentioned torsion member is incorporated, since the upper bracket 24 and the lower bracket 26 have the same length, these brackets of the torsion member are fixed. If the amount of twist about the axis 20 in the open portion is the same, the ball joints 34 and 40 at the ends of these brackets are also displaced in the lateral direction of the vehicle by the same amount.

Therefore, when substantially the same vehicle rearward force acts on the ball joints 30 and 36 by the vehicle rearward force acting on the wheels, as indicated by the phantom line in FIG. Since these ball joints and wheel spindles 14 are displaced to the rear of the vehicle by the same amount, the front-rear compliance at the wheel center and the front-rear compliance at the wheel contact point are substantially the same.

Therefore, if an attempt is made to increase the front-rear compliance in the wheel center to improve the riding comfort with respect to the harshney, the steer change during acceleration / deceleration cannot be reduced, and conversely at the ground contact point of the wheel. If it is attempted to reduce the steering change during acceleration / deceleration by reducing the front / rear compliance, the riding comfort deteriorates, so it is difficult to reduce the steering change during acceleration / deceleration while ensuring good riding comfort for harshness etc. is there.

In view of the above-mentioned problems in the conventional double wishbone suspension as described in the above publication, the present invention has an improved riding comfort against harshness and the like, and has a small steer change during acceleration / deceleration. The purpose is to provide a double wishbone suspension.

[0012]

SUMMARY OF THE INVENTION According to the present invention, the above object is achieved by a carrier for rotatably supporting a wheel and a torsion member which is fixed to a vehicle body at its upper and lower ends and is elastically twisted about its axis. Member, an upper bracket and a lower bracket which are vertically separated from each other and fixed to the torsion member, an upper arm and a lower arm having one outer end and two inner ends which are substantially separated from each other in the vehicle front-rear direction. And the upper arm is pivotally attached to the carrier at the outer end, pivotally supported on the vehicle body at one inner end, and pivotally supported at the tip of the upper bracket at the other inner end. Is pivotally attached to the carrier at the outer end, pivotally supported by the vehicle body at one inner end, and pivotally supported at the tip of the lower bracket at the other inner end. Each A and B vehicle lateral distance between the pivot point of the pivot point and the one inner end of the outer end of the arm
The distances in the vehicle front-rear direction between the pivot points of the one inner end of the upper arm and the lower arm and the pivot point of the other inner end are C and D, respectively, and the axis of the torsion member and the upper bracket are If the distance in the vehicle front-rear direction between the pivot point of the tip of the lower bracket and the tip of the lower bracket is a and b, respectively, there is a relationship of A · a / C> B · b / D between these distances. It is achieved by the double wishbone suspension system.

[0013]

According to the above-described structure, the distance between the pivot points has the relationship represented by the above inequality, so that the longitudinal force acts on the wheel as described in detail later. When the upper arm and the lower arm are pivoted about their corresponding inner end pivot points, the other inner end pivot point of the upper arm is a greater distance than the other inner end pivot point. Since the vehicle moves in the left-right direction, the movement distance of the pivot point at the outer end of the upper arm in the vehicle front-rear direction is greater than the movement distance of the pivot point at the outer end of the lower arm in the vehicle front-rear direction. Therefore, since the front-rear compliance at the wheel center is higher than the front-rear compliance at the ground contact point of the wheel, it is possible to reduce the steer change during acceleration / deceleration while ensuring good riding comfort for harshness and the like.

[0014]

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

FIG. 1 is a schematic perspective view showing one embodiment of a double wishbone suspension according to the present invention as a skeleton diagram, and FIG. 2 is an explanatory view showing the operation of the embodiment shown in FIG. In these figures, the shock absorber and the suspension spring are omitted, and the parts corresponding to the parts shown in FIGS. 3 and 4 have the same reference numerals as those in these figures. Is attached.

In FIG. 1, reference numeral 10 denotes a carrier that rotatably supports a wheel 12 around a spindle 14, and 16 is fixed to a vehicle body 18 at an upper end and a lower end, and an axis 2
A torsion member elastically twisted around 0 is shown. An upper bracket 22 and a lower bracket 24, which are vertically spaced apart from each other, are fixed to the torsion member 16, and these brackets extend forward of the vehicle from the torsion member. Further, in FIG. 1, 26 and 28
Indicates an upper arm and a lower arm, respectively.
Each of the upper arm and the lower arm is an A-shaped arm having one outer end and two inner ends spaced apart from each other in the vehicle front-rear direction.

The upper arm 26 is pivotally attached to the upper end of the carrier 10 by a ball joint 30 at the outer end, pivotally supported on the vehicle body 18 by a joint 32 including a rubber bush at the front inner end, and at the rear inner end. Ball joint 34
Is pivotally attached to the tip of the upper bracket 22. Similarly, the lower arm 28 is pivotally attached to the lower end of the carrier 10 by a ball joint 36 at the outer end, is pivotally supported on the vehicle body 18 by a joint 38 including a rubber bush at the inner end on the front side, and has a ball at the inner end on the rear side. The joint 40 is pivotally attached to the tip of the lower bracket 24.

As shown, the length of the upper bracket 22 is set longer than the length of the lower bracket 24. Further, the center of the ball joint 34 at the tip of the upper bracket 22 and the ball joint 4 at the tip of the lower bracket 24.
A straight line 46 connecting the center of 0 intersects the axis 20 of the torsion member 16 at an intersection P on the road surface 48.

A distance between the centers of the ball joints 30 and 32 in the lateral direction of the vehicle is A, a distance between the centers of the ball joints 36 and 38 in the lateral direction of the vehicle is B, and the joints 32 and 34 are jointed. The distance in the vehicle front-rear direction between the centers of the two is C, the distance in the vehicle front-rear direction between the centers of the joint 38 and the ball joint 40 is D, and the axis 20 of the torsion member and the ball joint 34 at the tip of the upper bracket 22 are defined. Let a be the distance in the vehicle front-rear direction from the center, and b be the distance in the vehicle front-rear direction between the axis 20 and the center of the ball joint 40 at the tip of the lower bracket 24. There is a relationship of A · a / C> B · b / D.

In the suspension thus constructed, when the wheels bounce and rebound, the upper arm 26 rotates around the straight line 42 connecting the center of the joint 32 and the center of the ball joint 34, as in the case of the conventional suspension described above. The lower arm 28 pivots about a straight line 44 connecting the center of the joint 38 and the center of the ball joint 40. When a longitudinal force is applied to the wheels, the torsion member 16 is elastically twisted around the axis 20 and the ball joints 34 and 40 are displaced in the inboard direction, so that the upper arm and the lower arm move around the joints 32 and 38, respectively. By pivoting and displacing the ball joints 30 and 36 rearward of the vehicle, front-rear compliance of the suspension is secured.

When the wheel 12 receives a rearward force from the road surface 48 of the vehicle, the ball joints 30 and 36 are moved.
If the vehicle receives a rearward force F, the rotational moment Mu around the upper arm joint 32 and the rotational moment Ml around the lower arm joint 38 are respectively expressed by the following equations.

Mu = F · A Ml = F · B Since the ball joints 34 and 40 are provided on the upper arm and the lower arm, respectively, the force F for moving these ball joints in the inboard direction is given.
u and Fl are respectively represented by the following formulas.

Fu = F · A / C Fl = F · B / D Therefore, the rotational moments Mub and Mlb of the ball joints 34 and 40 about the axis 20 are represented by the following equations, respectively.

Mub = F.A.a / C Mlb = F.B.b / D Since A.a / C and B.b / D have the above inequality, Mub> Mlb The torsion member 16 is twisted about the axis 20 over a larger angular range in the portion in which the lower bracket 24 is fixed than in the portion in which the upper bracket 22 is fixed.

Therefore, the distance that the ball joint 34 moves in the inboard direction is greater than the distance that the ball joint 40 moves in the inboard direction, so that the angle at which the upper arm 26 pivots rearward around the joint 32 is lower arm 28. Is greater than the pivoting angle about joint 38, the distance that joint 30 travels rearward is greater than the distance that joint 36 travels rearward, as shown in FIG.

Therefore, since the front-rear compliance at the wheel center is high and the front-rear compliance at the ground contact point of the wheel is low, it is possible to improve the riding comfort with respect to harshness and reduce the steer change during acceleration / deceleration.

In the above embodiment, the torsion member 16 is arranged rearward of the vehicle with respect to the upper arm and the lower arm, but the torsion member is arranged on the front side of the vehicle with respect to the upper arm and the lower arm. They may be pivotally attached to the tips of the upper and lower brackets, respectively, at the inner ends on the front side of the vehicle.

In the illustrated embodiment, the bracket 2
2 and 24 extend toward the front of the vehicle from the torsion member, but unless the ball joints 34 and 40 are on imaginary straight lines connecting the ball joints 30 and 36 and the axis 20, respectively, these brackets serve as torsion members. It may extend in any direction.

In the illustrated embodiment, the straight line 46 connecting the centers of the ball joints 34 and 40 intersects the axis 20 of the torsion member at the intersection P on the road surface 48, but the straight line 46 is the road surface. It may intersect the axis 20 below or above, and the straight line 46 may not intersect the axis 20 as long as the above inequality is satisfied.

Further, in the above embodiment, the joint 3
2, ball joint 34, axis 20 and joint 3
Although the ball joint 40, the ball joint 40, and the axis 20 are aligned with each other in the vehicle front-rear direction, they may be provided at positions deviated from each other in the vehicle lateral direction.

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

[0032]

As is apparent from the above description, according to the present invention, when the longitudinal force acts on the wheel, the upper arm and the lower arm pivot about the pivot points of the corresponding inner ends. , The pivot point of the other inner end of the upper arm moves in the left-right direction of the vehicle by a distance larger than the pivot point of the other inner end of the lower arm, and the movement distance of the pivot point of the outer end of the upper arm in the vehicle front-rear direction. Is larger than the movement distance in the vehicle front-rear direction of the pivot point at the outer end of the lower arm,
It is possible to increase the front-rear compliance at the wheel center and lower the front-rear compliance at the ground contact point of the wheel, thereby reducing the steer change during acceleration / deceleration while ensuring good ride comfort for harshness etc. be able to.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing, as a skeleton diagram, one embodiment of a double wishbone suspension according to the present invention.

FIG. 2 is an explanatory view showing the operation of the embodiment shown in FIG.

FIG. 3 is a perspective view showing, as a skeleton diagram, a suspension equivalent to the suspension described in JP-A-2-77310.

FIG. 4 is an explanatory view showing the operation of the embodiment shown in FIG.

[Explanation of symbols]

 10 ... Carrier 12 ... Wheels 16 ... Torsion member 18 ... Car body 22 ... Upper bracket 24 ... Lower bracket 26 ... Upper arm 28 ... Lower arm

Claims (1)

[Claims] 1. A carrier for rotatably supporting wheels, a torsion member fixed to a vehicle body at upper and lower ends and elastically twisted around an axis, and vertically fixed to the torsion member. An upper bracket and a lower bracket, and an upper arm and a lower arm having one outer end and two inner ends substantially separated from each other in the vehicle longitudinal direction, the upper arm being attached to the carrier at the outer end. The lower arm is pivotally attached to the vehicle body at one inner end and is pivotally attached to the tip of the upper bracket at the other inner end, and the lower arm is pivotally attached to the carrier at the outer end and one inner end. Between the outer arm pivot point of the upper arm and the lower arm and the one inner end pivot point of the upper arm and the lower arm.輌横 direction of distances A and B, respectively
The distances in the vehicle front-rear direction between the pivot points of the one inner end of the upper arm and the lower arm and the pivot point of the other inner end are C and D, respectively, and the axis of the torsion member and the upper bracket are If the distance in the vehicle front-rear direction between the pivot point of the tip of the lower bracket and the tip of the lower bracket is a and b, respectively, there is a relationship of A · a / C> B · b / D between these distances. Double wishbone suspension.