JPH092039A - Suspension device - Google Patents

Abstract

PURPOSE: To nearly conform the geometrical axis of a coil spring to the axis of a damper rod in a fixed load range so as to reduce friction generated in a damper and improve riding comfortableness by arranging the geometrical axis of the coil spring slanting against the axis of the damper rod. CONSTITUTION: The geometrical axis Ls of a compression coil spring 9 is slanted against the axis Ld of the damper rod 8a of a damper 8 centering around the middle point O in the vertical direction of the coil spring 9. The slanting direction and the slanting quantity are set so that the loaded axis Lm of the coil spring 9 is nearly conformed to the axis Ld of the damper rod 8a in a fixed load range. When the load range is 100kg-600kg; namely in a normal load, the distance (l) between at least one axis Ls of both end faces of the coil spring 9 and the axis Ld of the damper rod is in the range of 10-25% of the coil radius S of the coil spring 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension device for vehicles such as automobiles and small trucks, and more particularly to a suspension device characterized by the arrangement of coil springs.

[0002]

2. Description of the Related Art With the increase in paved roads in recent years, the spring constant of the coil spring of a suspension device has been reduced in order to improve the riding comfort of automobiles, especially passenger cars. It is desirable to study the improvement up to the range up to the friction area in order to improve it.

Conventionally, it has been considered that a load is generated on the geometric center axis of a coil spring. For example, "Spring Papers No. 31 (1985). P54-p60 Takeshi Hirano, Yukio Saraku, Akihiko Nishikawa, Hamano. As is clear from the description of "Toshio", when compressing the coil spring in the vertical direction, the contact state between the end turn part, the spring seat, and the wire changes, so the geometric center axis of the coil spring and the load It has been found that it is different (inclined) from the axis (hereinafter referred to as eccentric load in this specification). Therefore, in a normal layout in which the geometric axis of the coil spring and the central axis of the damper rod are aligned with each other, the eccentric load of the coil spring causes a gap between the damper rod and the rod guide or between the piston of the damper and the inner wall of the damper tube. It was also found that friction occurred in the car, which was a factor that deteriorated the riding comfort.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the prior art as described above, and its main purpose is to reduce friction generated in the damper and improve riding comfort. To provide a suspension device capable of

[0005]

According to the present invention, there is provided a suspension device in which a coil spring is wound around the outer periphery of a cylindrical damper provided between a vehicle body and wheels. By arranging the geometric axis of the coil spring so as to be inclined with respect to the axis of the damper rod, the load axis of the coil spring is substantially aligned with the axis of the damper rod in a predetermined load range. This is accomplished by providing a suspension device.

[0006]

As described above, by tilting the geometric axis of the coil spring with respect to the axis of the damper rod so that the load axis of the coil spring substantially coincides with the axis of the damper rod, this occurs in the suspension device, particularly in the damper. Friction can be reduced. If this is done, the load range will be 100 kg to 6
When the weight is 00 kg, that is, in the normal range, the inclination range is 10 mm of the coil radius of the coil spring in most cases when the distance between the geometric axis and the axis of the damper rod on at least one of both end surfaces of the coil spring is large. % To 25%.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a preferred embodiment of the present invention.

FIG. 1 is a schematic side view showing a simplified structure of a double wishbone type suspension device to which the present invention is applied. A load in the range of 100 kg to 600 kg on one side is normally applied to this suspension device. The steering knuckle 2 connected to a wheel hub (not shown) of the tire T has joints 3, 4
It is connected to the free ends of the lower arm 5 and the upper arm 6 via. The base ends of the lower arm 5 and the upper arm 6 are swingably connected to the vehicle body 1 via bushes (not shown). Further, between the lower arm 5 and the vehicle body 1, a known cylindrical damper 8 having a substantially cylindrical shape, and a compression coil spring 9 wound around the damper 8 are provided.

As shown in FIG. 2, the geometrical axis line Ls of the compression coil spring 9 is centered on the vertical middle point O of the coil spring 9 with respect to the axis line Ld of the damper rod 8a of the damper 8. It is inclined. The inclination direction and the inclination amount are set so that the load axis Lm of the coil spring 9 obtained by the method described later substantially coincides with the axis Ld of the damper rod 8a. Then, as shown in FIG.
As can be seen from FIG. 4 (b), the distance l between the axis Ls of at least one of the two end faces of the coil spring 9 and the axis Ld of the damper rod is 10% of the coil radius s of the coil spring 9. It is in the range of 25%.

The load axis of the eccentric load generated by the coil spring 9 in this embodiment will be calculated below. Since the contact state between the end turn portion, the seat surface, and the wire changes as the coil spring is compressed, a non-linear analysis that takes these contacts into account is required. When calculating the lateral force from the contact reaction force in the overall coordinate form obtained by the nonlinear analysis, the eccentric load P is applied to the coil spring.
Not only the bending moment M also occurs. Since this bending moment also acts on the rod, the point C where Pξ = Pη = Mξ = Mη = 0 on the local coordinate system λ (ξη ζ) shown in FIG. 2 from the mechanical relationship in the coil spring. think of. At this time, at point C, only Pξ ₁ and Mξ ₁ act. This point C is obtained below. If the coordinate transformation matrix from the global coordinate system to the local coordinate system is [T],

[0011]

## EQU1 ## F _t = [T] F _h

Where [T] is

[0013]

[Equation 2]

[0014]

[0015]

(Equation 3)

## EQU1 ## When the origin of the local coordinate system λ is set to a point H and the load P _h and the moment M _h are represented by a coordinate transformation matrix [T],

[0017]

Equation 4] _{P t = {Pξ Pη Pζ}} T = [T] P h M t = {Mξ Mη Mζ} T = [T] P h

## EQU1 ## At this time,

[0019]

(Equation 5)

Next, the point C (ξ where Mξ = 0 and Mη = 0
Let ₁ , η ₁ , ζ ₁ ) be on λ. r _t = (ξ ₁ , η ₁ ,
If ζ ₁ ) then M _t = r _t × P _t

[0021]

(Equation 6)

,

[0023]

(7) ξ ₁ = -Mη / Pζ and η ₁ = Mξ / Pζ (ζ ₁ is indefinite)

Is obtained. Therefore, it is possible to set an axis that passes through the point C and is parallel to the ζ axis of the coordinate system λ, that is, a load axis Lm that satisfies Pξ = Pη = Mξ = Mη = 0.

After actually measuring the shape of the spring and creating an analytical model, a non-linear analysis in which a compressive load is applied in parallel is performed, and the point through which the load axis Lm passes is found on the upper end surface or the lower end surface of the coil spring. A locus of points that move with changes in spring height (= changes in compression load) was obtained (FIG. 4A, FIG.
(B)). From this figure, it can be seen that the load axis Lm tends to move toward the geometric center axis of the coil as the vertical load increases.

On the other hand, a coil spring for a suspension device of an automobile such as a passenger car or a light truck is practically 100.
Used in the load range of kg to 600 kg. In FIGS. 4 (a) and 4 (b), the range through which the load axis Lm of this range passes on at least one of both end surfaces of the coil spring is
The average radius of the coil spring is 10% to 25%.
In this way, the load axis Lm in which the bending moment is not generated in the coil spring 9 changes with the spring height, so that the axis Ld of the damper rod 8a has this load within a predetermined spring height, that is, a predetermined load range (100 kg to 600 kg). The coil spring 9 may be laid out with respect to the damper 8 so as to pass through the axis Lm. In addition, although the double wishbone type suspension device is described in the present embodiment, it is needless to say that the same can be applied to other types of suspension devices. In particular, for example, a torsion beam type damper is a part of the link. When the present invention is applied to a suspension device of a type that is not used as the above and a lateral force from the tire is not generated so much, the effect becomes more remarkable.

[0027]

As is apparent from the above description, according to the suspension device of the present invention, the geometric axis of the coil spring is set so that the load axis of the coil spring substantially coincides with the axis of the damper rod. By making the load axis of the coil spring coincide with the axis of the damper rod by inclining with respect to the axis, the friction generated particularly in the damper of the suspension device can be reduced and the riding comfort is improved. In this way, when the load range is 100 kg to 600 kg, that is, in the normal range, the inclination range is the distance between the geometric axis and the axis of the damper rod on either one of the two end faces of the coil spring. 10% of the coil radius of
It becomes 25%.

[Brief description of drawings]

FIG. 1 is a schematic side view showing a simplified structure of a double wishbone type suspension device to which the present invention is applied.

FIG. 2 is an enlarged side view of a main part of FIG. 1;

FIG. 3 is a diagram illustrating a procedure for obtaining a load axis line of a coil spring.

4 (a) and 4 (b) show a locus along which a point on the upper end surface or the lower end surface of a coil spring through which a load axis Lm passes moves along with a change in spring height (= change in compression load). The obtained graph.

[Explanation of symbols]

 1 Car Body 2 Steering Knuckle 3, 4 Joint 5 Lower Arm 6 Upper Arm 8 Oil Damper 8a Damper Rod 9 Compression Coil Spring T Tire Ls Coil Spring Geometric Axis Lm Coil Spring Load Axis Ld Damper Rod Axis s Coil Spring Coil Radius l Distance between Ls and Ld on both ends of coil spring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Michiharu Okada 3-10 Fukuura, Kanazawa-ku, Yokohama, Kanagawa Prefecture

Claims (1)

[Claims] 1. A suspension device in which a coil spring is wound around an outer periphery of a cylindrical damper provided between a vehicle body and a wheel, wherein a load axis line of the coil spring is within a predetermined load range. The suspension device in which the geometric axis of the coil spring is arranged to be inclined with respect to the axis of the damper rod so as to substantially coincide with the axis of the suspension rod.