JPH07132722A - Suspension spring mechanism - Google Patents

Abstract

PURPOSE:To improve riding comfortableness of a vehicle by reducing sliding resistance of a shock absorber, in a suspension spring mechanism having the shock absorber integrally used with a coil spring to support at least one end thereof to an upper rod or lower case of the shock absorber through a spring seat. CONSTITUTION:A helical shape surface 3b of a lower spring seat 3 is set to a shape such that a coil spring 1 and the lower spring seat 3 are brought into contact with a uniformly equal distribution load in the circumferential direction under a normal load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a suspension spring mechanism used in an automobile, and more particularly to a suspension spring mechanism in which a shock absorber and a coil spring are coaxially mounted.

[0002]

2. Description of the Related Art Conventionally, as a suspension spring mechanism in which a shock absorber and a coil spring are coaxially mounted, for example, Japanese Utility Model Laid-Open No. 52-67117, Japanese Utility Model Laid-Open No. 60-115705, and Japanese Utility Model Laid-Open No. 60 are disclosed. Those described in Japanese Patent Publication No. 46312 and Japanese Utility Model Laid-Open No. 55-138109 are known. Here, the coaxial arrangement is meant to include a coaxial arrangement in which two axes coincide and an offset axis arrangement in which the two axes are offset.

[0003]

However, in each of the above-mentioned prior arts, the coil springs having the equal pitch, the equal winding diameter, and the equal wire diameter are bent by a predetermined amount, and both ends thereof are spring-loaded. It is supported by a seat, and at the contact portion between the coil spring and the spring seat, the amount of deflection increases as it approaches the tip of the spring, and the load increases according to the amount of deflection.
Since the structure is such that the load does not come into contact with the load evenly distributed in the circumferential direction under the normal load, the suspension spring of the coaxial arrangement in which the axes of the shock absorber and the coil spring are aligned, as shown in FIG. There is a problem that a moment M in the bending direction of the spring is generated at the spring end, and as a result, the sliding resistance of the shock absorber increases and the riding comfort deteriorates.

Similarly, even in a suspension spring having an offset shaft arrangement in which the axes of the shock absorber and the coil spring are offset from each other, the lateral force to the shock absorber also increases, so that the sliding resistance increases and the riding comfort increases. However, there was a problem that it deteriorated.

Here, the lateral force generating mechanism of the strut type shock absorber will be described with reference to FIG.

[0006] The support points on the vehicle body side of the struts and the input points from the tires do not coincide with each other in the vehicle width direction due to operational stability and structural restrictions. When a reaction force acts on the tire in this state, the strut receives a vertical force A, and this force A
The moment multiplied by the deviation is applied to the shock absorber, and lateral force is generated at the contact point between the rod and the inner and outer cylinders. Since the sliding resistance is drag (lateral force) × friction coefficient, it increases in proportion to the lateral force.

Therefore, it is possible to cancel the lateral force by canceling the vector of the external force and the vector of the reaction force of the coil spring spring by installing the coil spring with the shaft center offset to the shock absorber. That is, since the distance B is larger than the distance C, a coil spring spring reaction force that opposes the bending of the strut is generated. At present, the coil spring arrangement is determined based on this idea.

In the above examination, it is assumed that the contact load between the spring end surface of the coil spring and the spring seat surface is evenly distributed in the circumferential direction. Since the load is concentrated on the circumferential surface on one side, this precondition is not satisfied, and in the current suspension system, achieving zero lateral force has not been achieved.

The present invention has been made in view of the above problems, and an object thereof is to have a shock absorber used integrally with a coil spring, and at least one end of the coil spring is a shock absorber. In the suspension spring mechanism supported by the upper rod or the lower case via the spring seat, the riding comfort of the vehicle is improved by reducing the sliding resistance of the shock absorber.

[0010]

In order to achieve the above object, the suspension spring mechanism of the first invention has a shock absorber used integrally with a coil spring, and at least one end of the coil spring has an upper rod or a shock absorber. In a suspension spring mechanism supported by a lower case via a spring seat, at least one of an end shape of the coil spring and a spring receiving shape of the spring seat is formed into a circular shape between the coil spring and the spring seat under a normal load. It is characterized in that the shape is set so as to make a contact with an evenly distributed load in the circumferential direction.

In order to achieve the above object, the suspension spring mechanism of the second invention has a shock absorber used integrally with the coil spring, and at least one end of the coil spring is interposed between the upper rod or the lower case of the shock absorber via the spring seat. In a suspension spring mechanism supported by an elastic member, an elastic member is provided between the coil spring and the spring seat for contacting the coil spring and the spring seat with a uniform load in the circumferential direction under a normal load. Is characterized by.

[0012]

When the suspension spring mechanism of the present invention is applied to the suspension of the vehicle, the first invention sets the shape of at least one of the end shape of the coil spring and the spring seat shape of the spring seat. In the second aspect of the invention, the elastic member interposed between the coil spring and the spring seat allows the coil spring and the spring seat to contact with each other in the circumferential direction with an evenly distributed load under a normal load.

Therefore, in the coaxially arranged suspension spring in which the axes of the shock absorber and the coil spring are coincident with each other, it is possible to suppress the occurrence of a moment in the bending direction of the spring at the spring end and reduce the sliding resistance of the shock absorber. it can.

Further, in the suspension spring having the offset shaft arrangement in which the shaft centers of the shock absorber and the coil spring are offset from each other, the coil spring spring force due to the offset amount and the spring force can be satisfied by satisfying the precondition of the uniformly distributed load. By setting the force, the bending force applied to the shock absorber can be offset, and the sliding resistance of the shock absorber can be reduced.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) First, the structure will be described.

FIG. 1 is a perspective view showing a suspension spring mechanism of a first embodiment corresponding to the first aspect of the invention.

In FIG. 1, 1 is a coil spring, 2
Is a shock absorber, and 3 is a lower spring seat.

The coil spring 1 is wound at an equal pitch p when no load is applied, and is wound at a pitch p ₀ under a normal load.

The shock absorber 2 has a lower case 2a and a rod 2b, and has a coaxial arrangement in which the axis of the coil spring 1 and the axis of the shock absorber 2 are aligned with each other.

The lower spring seat 3 has a spring end stopper surface 3a and a spiral-shaped surface 3b. The spiral-shaped surface 3b circumferentially connects the coil spring 1 and the lower spring seat 3 under a normal load. It is set to a seat surface shape that makes contact with an evenly distributed load.

Here, the shape setting of the spiral-shaped surface 3b is as follows.
As shown in FIG. 3, when the spring end portion is the P ₀ point and the point separated by one turn from the spring end portion is the Q ₀ point, the spiral shape follows the spring pitch spiral shape under the normal load in the vicinity of the Q ₀ point. , Near the point P _{0 of the} spring end, the spiral shape between the spring pitch spiral shape under normal load and the spring pitch spiral shape under no load is almost intermediate, and the spiral shape between the P ₀ point and the Q ₀ point is , So that the flexure state shown in FIG. 7 is achieved.

Here, the derivation method of FIGS. 7 to 2 will be briefly described. First, since the spring pitch when there is no load is p,
Since a uniformly distributed load is applied to the spring ends where the pitch when loaded is p ₀ , the spring pitch p is evenly bent from point Q ₀ onward.
You can draw the ₀ line.

Next, the position of the spring center line direction of the point P between P ₀ point to Q ₀ point reads the deflection amount ε in Figure 7, the point was one turn fraction spring Tsu septum from the point P in FIG. 2 Can be determined by the spring pitch p and the deflection amount ε when there is no load. Then, if this operation is repeated by moving the point P, the point P _0-
In FIG. 2, the shape of the spiral surface 3b of the lower spring seat 3 is determined so that the shape of the spring between the points Q ₀ is found and the shape is the same.

Next, the operation will be described.

[Deflection of Coil Spring] In order to make the explanation of the following operation easier to understand, the deflection and general properties of the coil spring 1 will be described here.

First, a relative distance P between a point P on the coil spring 1 and a point Q on the spring which is different from the point P by one round of the spring.
The length change ΔPQ when Q is loaded is defined as the deflection of the point P (FIG. 3).

Therefore, as shown in FIG. 3, if a spring having an equal pitch, an equal winding diameter, and an equal wire diameter is loaded under a terminal condition such that a force F is applied to the spring center line, the torsional moment applied to the spring wire element is increased. Are equal over the entire area of the spring, resulting in equal deflections at each point on the spring. This is called a state of equal flexural deformation. Since the deformed deformed state is easily deformed and the calculation is easy, the shapes of the spring end portion and the spring seat are often designed by assuming the deformed deformed state.

However, generally used in vehicles,
Moreover, in the coil spring 1 commonly used in the coaxial arrangement with the shock absorber, it is impossible to have a structure in which a concentrated load is applied on the coil spring central axis C as shown in FIG. , As shown in FIG.
A load is applied in the form of a distributed load w that acts on the coil spring 1 and the spring seat contact portion (see FIG. 4).

If the center of gravity G of this distributed load w coincides with the central axis C of the coil spring, as shown in FIG. 5, the bending moment M of the coil spring 1 does not occur, and the friction does not increase, but the conventional In the coil spring and the spring seat shape which are designed on the assumption of the equal flexure deformation, the center of gravity G of the distributed load w does not coincide with the coil spring central axis C, so that a bending moment M is generated at the spring end by the coil spring 1. Hereafter, this moment M
Will be described.

As shown in FIG. 5, considering the deformation of the spring end portion when a uniform load is applied over the entire circumference of the spring end portion, the torsion moment distribution acting on the spring wire element is shown in FIG.
As shown in, the spring end portion gradually increases from the point P _{0 to the} point Q _{0, and} from the point Q _{0 to the} point of equal torsion moment. When this is expressed by an equation, the torsional moment T (θ) from the P ₀ point to the Q ₀ point is T (θ) = wr ² (θ-sin θ), and from the Q ₀ point onward, T (θ) = It becomes constant at 2πrw · r = W · r, and the characteristic shown in FIG. 6 is obtained (note that r is the radius of the coil spring, and W = 2πrw).

Since the point after Q ₀ has an equal moment distribution, the point after Q ₀ (assuming an equal line diameter) is
It has an equal deflection distribution. The deflection of the point P between the points P _{0 and} Q ₀ is given by integrating the effect of the torsional deformation at each point up to the point Q, which is separated from the point P by one round, on the displacement of the point P. The characteristic shown in FIG. 7 is obtained as the characteristic of ΔPQ. According to FIG. 7, it is understood that when the uniformly distributed load is applied over the entire circumference of the spring end portion, the flexure of the spring wire element decreases as it approaches the spring end portion P ₀ .

That is, when the spring seat is designed assuming equal deflection up to the tip of the spring, the load cannot be evenly distributed, and the load is concentrated on the tip of the spring, and the distributed load w
The center of gravity G of C does not coincide with the central axis C of the coil spring 1 and causes a bending moment M as shown in FIG.

FIG. 8 shows a general shock absorber in which the sliding resistance (friction) of the shock absorber when the center of gravity of the distributed load is offset from the central axis of the shock absorber is determined. Here, assuming that the static load of the spring is 300 kgf, the moment M applied to the shock absorber is obtained by the offset amount of the center of gravity of the distributed load. The dynamic resistance was estimated.

According to FIG. 8, the increase in the sliding resistance of the shock absorber due to the offset of the center of gravity of the distributed load is large, and it is presumed that this is the cause of deteriorating the riding comfort of the vehicle.

[Vehicle running] When the suspension spring mechanism of the first embodiment is applied to the suspension of the vehicle, the spiral surface 3b of the lower spring seat 3 has a shape capable of obtaining the flexed state shown in FIG. Since it is set, the coil spring 1 and the lower spring seat 3 come into contact with each other with a uniform load in the circumferential direction under a normal load.

Therefore, as shown in FIG. 1, in the case of a coaxially arranged suspension spring in which the axes of the shock absorber 2 and the coil spring 1 coincide with each other, the center of gravity G of the distributed load w is approximately on the central axis C of the coil spring 1. It is possible to suppress the occurrence of the bending moment of the spring at the spring end, reduce the sliding resistance of the shock absorber, and improve the riding comfort of the vehicle.

Next, the effect will be described.

In a suspension spring mechanism having a shock absorber 2 coaxially arranged with the coil spring 1, one end of the coil spring 1 being supported by a lower case 2a of the shock absorber 2 via a lower spring seat 3 Since the spiral surface 3b is set to a shape in which the coil spring 1 and the lower spring seat 3 come into contact with each other in a circumferential direction with an evenly distributed load under a normal load, the sliding resistance of the shock absorber 2 is reduced and the riding comfort of the vehicle is reduced. Can be improved.

(Second Embodiment) First, the structure will be described.

FIG. 9 is a vertical sectional side view showing a suspension spring mechanism of a second embodiment corresponding to the first aspect of the invention.

In FIG. 9, 1 is a coil spring, 2
Is a shock absorber, 3 is a lower spring seat, 4 is
Is the upper spring seat.

The coil spring 1 is wound at an equal pitch p when no load is applied, and is wound at a pitch p ₀ under a normal load.

The shock absorber 2 has a lower case 2a and a rod 2b, and has an offset shaft arrangement in which the axis of the coil spring 1 and the axis of the shock absorber 2 are offset from each other.

Similar to the first embodiment, the lower spring seat 3 has a spiral-shaped surface 3b which allows the coil spring 1 and the lower spring seat 3 to contact with each other in a circumferential direction with an evenly distributed load under a normal load. .

The upper spring seat 4 has a spring end stopper surface (not shown) and a spiral-shaped surface 4b which allows the coil spring 1 and the lower spring seat 3 to come into contact with each other in a circumferential direction with an evenly distributed load under a normal load. Have.

Next, the operation will be described.

When the suspension spring mechanism of the second embodiment is applied to the suspension of the vehicle, the lower spring seat 3
Since the spiral-shaped surface 3b and the spiral-shaped surface 4b of the upper spring seat 4 are set so as to obtain the flexed state shown in FIG. 7, the coil spring 1 and the lower spring seat 3 are circumferentially arranged under a normal load. Contact with evenly distributed load in the same direction.

Therefore, as shown in FIG. 9, in the case of a suspension spring having an offset shaft arrangement in which the shaft centers of the shock absorber 2 and the coil spring 1 are offset, the center of gravity G of the distributed load w is the central axis C of the coil spring 1. By satisfying the precondition for designing that the coil spring spring reaction force is set, the bending force applied to the shock absorber 2 by the offset amount and the spring force is canceled by the coil spring spring reaction force as designed. The sliding resistance of the shock absorber 2 can be reduced, and the riding comfort of the vehicle is improved.

Next, the effect will be described.

A coil spring 1 and a shock absorber 2 having an offset shaft are arranged. The lower end of the coil spring 1 is supported by a lower case 2a of the shock absorber 2 via a lower spring seat 3, and the upper end of the coil spring 1 is a shock. Upper rod 2 of absorber 2
In the suspension spring mechanism which is supported by b via the upper spring seat 4, the coil spring 1 and the lower spring seat 3 are formed into a circle on the spiral-shaped surfaces 3b and 4b of the lower spring seat 3 and the upper spring seat 4 under normal load. Since the shape is set so as to make a contact with an evenly distributed load in the circumferential direction, the riding resistance of the vehicle can be improved by reducing the sliding resistance of the shock absorber 2. Moreover, as compared with the case where the spiral-shaped surface 3b is applied only to the lower end portion of the coil spring 1 as in the first embodiment, the spiral-shaped surfaces 3b and 4b are applied to both ends of the coil spring 1 so that the coil spring 1 slides further. The resistance reduction effect is enhanced.

(Third Embodiment) First, the structure will be described.

FIG. 10 is a perspective view showing a suspension spring mechanism of a third embodiment corresponding to the first aspect of the invention.

In FIG. 1, 1 is a coil spring, 2
Is a shock absorber, and 3 is a lower spring seat.

The shock absorber 2 has a lower case 2a and a rod 2b, and has a coaxial arrangement in which the axis of the coil spring 1 and the axis of the shock absorber 2 are aligned with each other.

The lower spring seat 3 has a seat surface shape having a spring end stopper surface 3a and a simple uniform pitch spiral surface 3c.

The coil spring 1 is wound at an equal pitch p in the region of Q ₀ or more at no load and at a pitch p ₀ under normal load, but in the region of P _{0 to} Q ₀ , When the coil spring 1 and the lower spring seat 3 are brought into contact with the uniform pitch spiral surface 3c under a normal load, the coil spring 1 and the lower spring seat 3 are contacted with an evenly distributed load in the circumferential direction to form a nonuniform pitch spring end 1a. ing.

The shape of the unequal pitch spring end portion 1a is the same as that of the first embodiment so that an unloaded shape and a normally loaded shape between points P _{0 and} Q ₀ shown in FIG. 11 are given. Properly created by various methods.

The operation and effect are the same as those of the first embodiment.

(Fourth Embodiment) First, the structure will be described.

FIG. 12 is a perspective view showing the upper spring seat portion of the suspension spring mechanism of the fourth embodiment corresponding to the second aspect of the invention, and FIG. 13 is the upper spring seat of the suspension spring mechanism of the fourth embodiment. It is sectional drawing of a part.

12 and 13, 1 is a coil spring, 4 is an upper spring seat, 5 is an elastic belt holding plate, and 6 is an elastic belt. The entire structure including the shock absorber and the lower spring seat is the same as that of the above-mentioned embodiment, and therefore its explanation is omitted.

The elastic belt holding plate 5 is joined to the inner peripheral portion of the upper spring seat 4 in parallel with each other, and has a plurality of slits 5a cut in the radial direction at equal intervals in the circumferential direction. .

The elastic belt 6 is attached in a wavy shape by alternately passing the slit 5a from the lower side and the upper side, and is in contact with the lower surface of the elastic belt 6 by loose insertion and attachment to the slit 5a. Coil spring 1
It is possible to move in the axial direction by an external force (contact force) from.

The elastic belt holding plate 5 and the elastic belt 6 correspond to the elastic member in claim 2.

Next, the operation will be described.

When the axial contact force from the coil spring 1 is applied to the elastic belt 6, the elastic belt 6 itself can be deformed according to the magnitude of the force, and the elastic belt 6 is axially moved through the slit 5a. Since the directional movement is possible, the spring contact force on the elastic belt 6 is automatically adjusted to be uniform at each contact point. Moreover, since the upper spring seat 4 and the elastic belt holding plate 5 are parallel and the slits 5a are equally spaced in the circumferential direction, the curvature of the elastic belt 6 at each contact point between the upper spring seat 4 and the elastic belt 6 becomes equal. . Therefore, the axial force that the upper spring seat 4 receives from the elastic belt 6 becomes equal at each belt contact point with the upper spring seat 4. Of course, since the respective belt contact points are evenly spaced on the circumference corresponding to the slits 5a, regardless of the contact state between the coil spring 1 and the elastic belt 6,
A uniform spring reaction force is input to the upper spring seat 4 in the circumferential direction.

Next, the effect will be described.

In the suspension spring mechanism having the shock absorber 2 coaxially arranged with the coil spring 1, one end of the coil spring 1 is supported by the upper rod 2b of the shock absorber 2 via the upper spring seat 4. And upper spring seat 4
Since the elastic belt holding plate 5 and the elastic belt 6 which make the coil spring and the spring seat contact with each other in the circumferential direction with a uniform and even load in the circumferential direction are interposed between them, the sliding resistance of the shock absorber 2 is reduced. It is possible to improve the riding comfort of the vehicle.

(Fifth Embodiment) First, the structure will be described.

FIG. 14 is a perspective view showing the upper spring seat portion of the suspension spring mechanism of the fifth embodiment corresponding to the second aspect of the invention, and FIG. 15 is the upper spring seat of the suspension spring mechanism of the fifth embodiment. It is sectional drawing of a part.

14 and 15, 1 is a coil spring, 4 is an upper spring seat, 7 is an elastic bag, and 8 is a fluid. The entire structure including the shock absorber and the lower spring seat is the same as that of the above-mentioned embodiment, and therefore its explanation is omitted.

The elastic bag body 7 is fixed to the inner peripheral portion of the upper spring seat 4 by forming a hollow portion therein, and the fluid body 8 is enclosed in the hollow portion of the elastic bag body 7. The elastic bag body 7 and the fluid body 8 correspond to the elastic member in claim 2.

Next, the operation will be described.

When the axial contact force from the coil spring 1 is applied to the elastic bag body 7, the shape of the elastic bag body 7 is changed to the end shape of the coil spring 1 by the flow of the fluid 8 enclosed therein. Transform along. This deformation increases the internal pressure of the elastic bag body 7, but the presence of the fluid 8 causes the internal pressure acting on the inner surface of the elastic bag body 7 to be a constant pressure in all parts, and therefore acts on the upper spring seat 4 from the coil spring 1. The spring reaction force that acts becomes a uniform force in the circumferential direction.

Therefore, the same effect as that of the fourth embodiment can be obtained.

Although the embodiments have been described above with reference to the drawings, the specific configuration is not limited to the embodiments, and modifications and additions within the scope of the present invention are included in the present invention. Be done.

[0078]

According to the present invention, there is provided a shock absorber used integrally with a coil spring, and at least one end of the coil spring is connected to an upper rod or a lower case of the shock absorber via a spring seat. In the suspension spring mechanism supported,
At least one of the end shape of the coil spring and the spring seat shape of the spring seat is set to a shape that causes the coil spring and the spring seat to contact with each other in a circumferential direction with an evenly distributed load under a normal load. By reducing the sliding resistance of the absorber, the riding comfort of the vehicle can be improved.

According to the second aspect of the present invention, there is provided a shock absorber used integrally with the coil spring, and at least one end of the coil spring is supported by the upper rod or the lower case of the shock absorber via the spring seat. In the suspension spring mechanism, an elastic member is placed between the coil spring and the spring seat to make the coil spring and the spring seat contact with each other in a circumferential direction with an evenly distributed load, so that the shock absorber slides. An effect that the riding comfort of the vehicle can be improved by reducing the resistance is obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a suspension spring structure of a first embodiment of the present invention.

FIG. 2 is a distance characteristic diagram in the spring center line direction with respect to the position of a spring wire element in the suspension spring structure of the first embodiment.

FIG. 3 is an explanatory view of the definition of the deflection of the coil spring.

FIG. 4 is an explanatory diagram when a non-uniformly distributed load acts on an end portion of a coil spring.

FIG. 5 is an explanatory diagram when a uniformly distributed load acts on an end portion of a coil spring.

FIG. 6 is a characteristic diagram of a torsional moment acting on a spring wire element.

FIG. 7 is a deflection characteristic diagram of the spring at each point on the spring.

FIG. 8 is a shock absorber sliding resistance characteristic diagram.

FIG. 9 is a vertical sectional side view showing a suspension spring structure according to a second embodiment.

FIG. 10 is a perspective view showing a suspension spring structure of a third embodiment.

FIG. 11 is a distance characteristic diagram in the spring center line direction with respect to the position of the spring wire element, which illustrates the shape of the spring seat and the shape of the spring end portion in the third embodiment.

FIG. 12 is a perspective view showing an upper spring seat portion of the suspension spring mechanism of the fourth embodiment.

FIG. 13 is a sectional view of an upper spring seat portion of the suspension spring mechanism of the fourth embodiment.

FIG. 14 is a perspective view showing an upper spring seat portion of the suspension spring mechanism of the fifth embodiment.

FIG. 15 is a sectional view of an upper spring seat portion of the suspension spring mechanism of the fifth embodiment.

FIG. 16 is an explanatory diagram of a bending moment generation in a conventional suspension spring mechanism having a coaxial arrangement.

FIG. 17 is an explanatory diagram of bending of a strut and spring reaction force in a conventional suspension spring mechanism having an offset shaft arrangement.

[Explanation of symbols]

 1 Coil Spring 2 Shock Absorber 2a Lower Case 2b Upper Rod 3 Lower Spring Seat 4 Upper Spring Seat 5 Elastic Belt Holding Plate 6 Elastic Belt 7 Elastic Bag Body 8 Fluid

Claims (2)

[Claims] 1. A suspension spring mechanism having a shock absorber used integrally with a coil spring, wherein at least one end of the coil spring is supported by an upper rod or a lower case of the shock absorber via a spring seat. At least one of the end shape and the spring receiving shape of the spring seat is set to a shape in which the coil spring and the spring seat are brought into contact with each other in a circumferential direction with an evenly distributed load under a normal load. Suspension spring mechanism. 2. A suspension spring mechanism having a shock absorber used integrally with a coil spring, wherein at least one end of the coil spring is supported by an upper rod or a lower case of the shock absorber via a spring seat. Between the spring seats,
A suspension spring mechanism comprising an elastic member for contacting a coil spring and a spring seat with a uniform load in the circumferential direction under a normal load.