JP2007062567A - Automobile suspension - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automobile suspension improving ride comfort by lowering the fore-and-aft stiffness of a suspension bush, making a wheel on a steering outer ring side promptly toe in while keeping lateral stiffness, and facilitating a layout. <P>SOLUTION: Right and left trailing arms 10 in a vehicle body fore-and-aft direction are rigidly united by a torsion beam 12 in a vehicular width direction. A wheel attaching portion 11 is provided at a rear end of the trailing arm, and right and left shock absorbers and spring members 13 are provided between the torsion beam or the wheel attaching portion and a vehicle body. A tip end part of the trailing arm is elastically united to the vehicle body by the suspension bush 14. The right and left trailing arms are coupled with each other at tip ends and rear ends by making two beams 10A oppose to each other. The right and left trailing arms are structured to be a flat surface trapezoidal shape wherein a clearance between the two beams is decreased from the tip ends to the rear ends. The trailing arms are deformed in a direction which lateral force acts, and the wheel on the turning outer ring side is displaced in a toe-in direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a suspension for an automobile, and in particular, it can improve the ride comfort by reducing the longitudinal rigidity of the suspension bush, and quickly displace the wheel on the turning outer wheel side in the toe-in direction while maintaining the lateral rigidity of the wheel on the turning outer wheel side. Further, the present invention relates to a suspension that can be easily laid out.

  In automobiles, for example, front-wheel drive vehicles (hereinafter referred to as FF vehicles), a torsion beam type suspension is often adopted as a rear suspension of a small vehicle. This torsion beam suspension basically has a structure in which trailing arms are arranged on the left and right, and the left and right trailing arms are connected by a torsion beam (cross beam), and the torsion beam is provided at the tip of the trailing arm. An intermediate beam type provided between the intermediate parts and a rear end beam type provided between the wheel mounting parts of the trailing arm are known (Patent Document 1, Patent Document 2, Patent Document 3).

  FIG. 3 shows a structural example of a conventional intermediate beam type rear suspension. A suspension bush (not shown) is provided at the tip of the left and right trailing arms 100, and the tip of the trailing arm 100 is elastically coupled to a vehicle body, for example, a vehicle body frame (not shown) via the suspension bush. It is like that.

  In addition, a wheel mounting portion 110 is provided at the rear end portion of the left and right trailing arms 100, a rear wheel (not shown) is mounted, and the lower ends of the shock absorber and the coil spring 130 are supported, and the shock absorber and the coil are supported. The upper end of the spring 130 is supported by a vehicle body, for example, a vehicle body frame.

  The intermediate portions of the left and right trailing arms 100 are coupled to each other by, for example, a torsion beam 120 having a closed cross-sectional shape.

  Incidentally, it is known that in a rear suspension of an automobile, particularly an FF vehicle, an appropriate toe-in of the turning outer wheel contributes to the stability of the turning vehicle and leads to an improvement in straightness.

  However, in the conventional torsion beam type rear suspension, in order to obtain an appropriate toe-in of the turning outer wheel against the lateral force, it is necessary to keep the front and rear rigidity of the suspension bush at the tip of the trailing arm to a certain extent, and the vibration of the rear wheel is accordingly increased. There was room for improvement in terms of ride comfort.

  On the other hand, one of the applicants of the present application configured the cross beam, the left and right side beams, and the base beam in a flat trapezoidal shape, deforms the left and right side beams in the direction in which the lateral force acts during turning, and the cross beam An automotive suspension has been proposed in which the vehicle is tilted or deformed so that the axle beam is tilted so that the wheel on the turning outer wheel side is displaced in the toe-in direction (Patent Document 4). In this automobile suspension, the stability of the automobile during turning can be achieved, and the front and rear rigidity of the suspension bush can be reduced to improve the riding comfort.

JP 2001-187526 A JP 2002-103938 A JP 2002-127724 A JP 2004-358991 A

  However, in the automobile suspension described in Patent Document 4, since the cross beam, the left and right side beams, and the base beam are configured in a flat trapezoidal shape, the layout may be limited in relation to other automotive parts and the like. .

  Further, since the left and right side beams are deformed in the direction in which the lateral force acts to incline the cross beam or the axle beam, there is a risk that the lateral stiffness of the wheel on the turning outer wheel side at the start of turning of the automobile may be reduced. There was room for improvement.

  In view of such problems, the present invention can improve the ride comfort by reducing the longitudinal rigidity of the suspension bushing, and quickly displace the wheel on the turning outer wheel side in the toe-in direction while maintaining the lateral rigidity of the wheel on the turning outer wheel side. It is another object of the present invention to provide an automobile suspension that can be made easy to lay out.

  A suspension for an automobile according to the present invention is a suspension for supporting a non-driving side wheel of an automobile on a vehicle body, extending in the longitudinal direction of the vehicle body, and each having two beams opposed to each other so that a rear end and a front end are mutually opposite. And left and right trailing arms configured to form a flat trapezoidal shape so that the distance between the two beams decreases from the front end to the rear end, and extends in the vehicle width direction, A torsion beam rigidly coupled between the trailing arms, a wheel mounting portion provided at a rear end of the trailing arm, to which a wheel is rotatably mounted, and the trailing arm, torsion beam or wheel mounting portion and the vehicle body. Suspension bush that elastically couples the left and right shock absorbers and spring members provided between them and the leading end of the trailing arm to the vehicle body With the door, trailing arms of the left and right during turning of the vehicle deforms in the direction of action of lateral force, the wheel of the turning outer wheel side is characterized by being configured so as to be displaced in the toe-in direction.

  One of the features of the present invention is that each of the left and right trailing arms is formed in a flat trapezoidal shape, and each of the left and right trailing arms is deformed in a direction in which a lateral force acts during turning. As a result, the wheel on the outer wheel side is displaced in the toe-in direction during turning, and even if the wheel on the outer wheel side becomes toe-out, the toe-out is small and the stability of the automobile during turning can be improved.

  Also, since the displacement of the wheels in the toe-in direction is obtained by a slight deformation of the trailing arm, the displacement of the toe-in direction is obtained by inclining the cross beam or axle beam by the deformation of the side beam, or the deformation of the bush 2 has a shorter dimension between AB in FIG. 2 than when obtaining a displacement in the toe-in direction of the wheel, so that a large displacement in the toe-in direction can be obtained with a slight lateral displacement, and the response of the displacement in the wheel toe-in direction at the start of turning Is fast.

  Further, since the displacement of the wheels in the toe-in direction is obtained by deformation of the trailing arm, the longitudinal rigidity of the suspension bush can be lowered correspondingly, and the riding comfort can be improved.

  Here, the origin is set at the ground contact center of the tire (the intersection of the center plane passing through the center of the wheel and the wheel rotation axis vertically projected on the road surface), and the X axis is taken as the intersection line between the wheel center plane and the road surface. The moving direction of is positive. If the Z-axis is perpendicular to the road surface, the Y-axis is on the road surface, and taken in the tire rotation axis direction, the lateral force (side force) is defined as the force in the Y-axis direction acting on the tire on the road surface.

Next, the behavior of the automobile suspension according to the present invention will be described dynamically.
[Toe change when using rear suspension]
The amount of toe change when the suspension of the present invention is used for a rear suspension will be examined. When receiving a lateral force, the suspension deformation model shown in FIG. 2 is assumed.

Since the connecting portion or connecting portion between the trailing arm and the torsion beam is rigidly connected (rigidly connected), the trailing arm is deformed in a curved line due to deflection or torsion. The toe change occurs when AB in FIG. 2 moves to ab. Now, assuming that ∠FEA = ∠EFB = 88 °, longitudinal elastic modulus E = 21000 kgf / mm ² , and lateral force P = 200 kgf, the cross-sectional secondary moments in the lateral force direction of the two beams facing each other average I = 58700mm ⁴ Assuming that the beam length L = 500mm,

さらに図２のＡＢ間の長さを７５ｍｍ、タイヤ径を５７０ｍｍとすると、

Furthermore, when the length between AB in FIG. 2 is 75 mm and the tire diameter is 570 mm,

となる（近似計算）。

(Approximate calculation).

  The lateral displacement of 3.3 mm is the value when the lateral force is 200 kgf (spring constant 60 kgf / mm), and the lateral stiffness is equal to or greater than the tire spring constant, and the tire has a side slip angle on an uneven road surface. In addition to preventing toe-out, it also has the effect of absorbing shocks from the front of the slant. Further, since there is no lateral displacement with respect to the longitudinal force, it is difficult to toe out.

[About components]
The trailing arm may be formed by integrating two beams facing each other. For example, the trailing arm may have a closed cross-sectional shape. However, considering the response of toe-in, the trailing arm is preferably open. The cross-sectional shape of the beam is not particularly limited. However, when the trailing arm has an open cross-sectional shape, the beam should have a U-shaped cross-section. That is, the two beams should have a U-shaped cross-sectional shape in which the dimensions of the upper and lower sides gradually decrease toward the rear end, and the trailing arm should have an open cross-sectional shape.

  Furthermore, it is desirable that the leading end of the trailing arm be bent as large as possible in order to reduce the stress concentration when the opposing beam changes minutely. When bending R is applied as shown in the figure, stress concentration when 際 EAB and ∠FBA change slightly can be reduced. The torsion beam can have an open cross-sectional shape or a closed cross-sectional shape.

[Differences in structure and function from conventional torsion beam type suspension]
The suspension of the present invention has a structure that can cope with toe-out due to lateral force by making the trailing arm trapezoidal, and the position of the suspension bushing of the attachment portion to the vehicle body as in the conventional torsion beam type suspension. In addition to obtaining the outer ring toe by roll steer when receiving lateral force by lowering the wheel from the center of the wheel, the outer ring toe is obtained by deflection steer due to deformation such as structural deflection and torsion. Therefore, it is possible to improve the riding comfort by reducing the longitudinal rigidity of the suspension bush by that amount.

  Hereinafter, the present invention will be described in detail based on specific examples shown in the drawings. FIG. 1 shows a preferred embodiment of an automobile suspension according to the present invention, which is an example applied to a rear suspension of an FF vehicle. In the figure, the left and right trailing arms 10 have an open cross-sectional shape and extend in the longitudinal direction of the vehicle body, and a torsion beam 12 extends in the vehicle width direction and is rigidly coupled between the vicinity of the middle part of the left and right trailing arms 10. The torsion beam 12 has a closed cross-sectional shape.

  A suspension bush 14 is attached to the tip of the trailing arm 10, and the suspension bush 14 is elastically coupled to the vehicle body.

  Further, a wheel mounting portion 11 is attached to the rear end of the trailing arm 10, and a rear wheel (non-driving side wheel) is rotatably attached to the wheel mounting portion 11 by a known method.

  Further, a lower end portion of a shock absorber 13 having a coil spring (spring member) is swingably connected to the rear end portion of the trailing arm 10 so that the upper end portion of the shock absorber 13 is supported by the vehicle body. Yes.

  The trailing arm 10 is configured by two beams 10A facing each other, and the two beams 10A have a U-shaped cross-section in which the dimensions of both upper and lower sides gradually decrease toward the rear end. The front end of the beam 10A is connected to each other by a mounting pin 15 of the suspension bush 14, and the rear end is integrated by fixing the beam 10A to each other, so that the trailing arm 10 has a distance between the two beams 10A. It has a flat trapezoidal shape that decreases from the front end toward the rear end. Further, a large bending radius R is given to the tip corner portion of the trailing arm 10.

  When the suspension of this example receives a lateral force, the left and right trailing arms 10 are deformed in the direction of the lateral force as described above, and the rear wheels of the turning outer wheel are displaced in the toe-in direction by the deformation of the trailing arm 10. To do.

1 is an overall perspective view showing a preferred embodiment of an automobile suspension according to the present invention. It is a figure for demonstrating the means for solving a subject. It is a figure which shows the conventional torsion beam type suspension.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Trailing arm 11 Wheel attachment part 12 Torsion beam 13 Shock absorber and coil spring 14 Suspension bush

Claims (3)

A suspension that supports the vehicle's non-driving wheel on the vehicle body,
A flat table that extends in the longitudinal direction of the vehicle body, connects each of the two beams to each other and connects the front end and the rear end, and the distance between the two beams decreases from the front end to the rear end. Left and right trailing arms configured to form a shape;
A torsion beam extending in the vehicle width direction and rigidly coupled between the left and right trailing arms;
A wheel mounting portion provided at the rear end of the trailing arm, to which the wheel is rotatably mounted;
Left and right shock absorbers and spring members provided between the trailing arm, torsion beam or wheel mounting portion and the vehicle body;
A suspension bush for elastically coupling the leading end of the trailing arm to the vehicle body,
A suspension for an automobile characterized in that the left and right trailing arms are deformed in a direction in which a lateral force acts when the automobile turns, and the wheels on the turning outer wheel side are displaced in a toe-in direction.   2. The automobile suspension according to claim 1, wherein the two beams have a U-shaped cross-section such that the dimensions of both upper and lower sides gradually decrease toward the rear end, and the trailing arm has an open cross-sectional shape. The automobile suspension according to claim 1, wherein the torsion beam has a closed cross-sectional shape or an open cross-sectional shape.

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