JP2008196611A - Vibration isolation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a dynamic spring constant by using a rubber with respect to a high frequency vibration upon application of a large load such at acceleration etc. while exhibiting high damping performance by polyurethane foam with respect to a low frequency vibration upon application of a general load. <P>SOLUTION: An elastic body 16 interposed between an inner cylinder 12 and an outer cylinder 14 is composed of a first elastic portion 20 made of the polyurethane foam and a second elastic portion 22 made of the rubber. The second elastic portion 22 is arranged on the side of the inner cylinder 12, and has a stopper rubber portion 26 opposing the inner peripheral surface 14A of the outer cylinder 14 at a distance from a space 24. The first elastic portion 20 is provided on each of sides of the stopper rubber portion 26 in a peripheral direction C for supporting the inner cylinder 12 with respect to the outer cylinder 14. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vibration isolator that can be suitably used for a bush such as a torque rod of an automobile.

  2. Description of the Related Art Conventionally, various types of vibration isolators are used in automobiles in order to prevent vibrations from an engine that is a vibration generation source from being transmitted to the vehicle body side. Among them, the torque rod is interposed between the engine side and the vehicle body side in order to prevent transmission of vibration due to engine torque fluctuation or the like, and has a cylindrical holding portion at both ends in the longitudinal direction. And a bush fitted and fixed to the cylindrical holding portion. And as this bush, the rubber bush formed by elastically connecting between an inner cylinder and an outer cylinder with a rubber elastic body is common.

  As a vibration isolator used as a bush of such a torque rod, in Patent Documents 1 and 2 below, the inner cylinder and the outer cylinder are coupled with a rubber elastic body, and the inside of a stopper rubber portion made of a rubber elastic body, Or what provided the polyurethane foam in the space part of a stopper rubber part and an inner cylinder is proposed. However, in the vibration isolators of these documents, it is still a rubber elastic body that exerts a vibration isolating performance against vibration input under a general load load, and polyurethane foam has a load against bending after hitting a stopper. It is only used as a buffer to relieve the sudden increase in the amount of water.

In addition, those using polyurethane foam for the vibration isolating bush are also proposed in the following Patent Documents 3 and 4, but also in these cases, the direct connection between the inner cylinder and the outer cylinder is rubber. It is an elastic body, and the polyurethane foam is only disposed in a space provided in a part of the rubber elastic body.
JP 2004-183725 A JP 2004-183724 A JP 2001-193776 A Japanese Patent Laid-Open No. 06-017864

  The torque rod of an automobile is required to have a large damping performance against low frequency vibrations to suppress engine swing during general load loading, while at the time of heavy load loading such as acceleration or starting. It is required to lower the dynamic spring constant for high-frequency vibrations to cut off the transmission of sound to the vehicle body.

  Examination in view of such requirements revealed that rubber alone has a low dynamic spring constant for high-frequency vibrations, but also has a low loss factor (damping performance) for low-frequency vibrations and cannot sufficiently meet these requirements. did. Further, it has been found that a synthetic resin foam such as polyurethane foam alone has a high loss factor (damping performance) for low-frequency vibration, but also a high dynamic spring constant for high-frequency vibration.

  Therefore, the present invention makes use of the characteristics of both the rubber and the synthetic resin foam, and exhibits high damping performance by the synthetic resin foam against low frequency vibrations under a general load load, while at the time of acceleration, etc. An object of the present invention is to provide an anti-vibration device capable of reducing the dynamic spring constant with rubber against high-frequency vibration under a heavy load.

An anti-vibration device according to the present invention is an anti-vibration device comprising a shaft member, an outer cylinder that surrounds the shaft member in an axially parallel manner, and an elastic body interposed between the shaft member and the outer cylinder. There,
The elastic body comprises a first elastic part made of a synthetic resin foam and a second elastic part made of rubber,
The second elastic portion is provided on the shaft member side, and has a stopper rubber portion facing the inner peripheral surface of the outer cylinder with a space portion therebetween,
The first elastic portion is provided to support the shaft member with respect to the outer cylinder on both sides in the circumferential direction of the stopper rubber portion.

  In this invention, the said 2nd elastic part is provided in the outer periphery of the said shaft member over the perimeter, and the said 1st elastic part is between the outer peripheral surface of the said 2nd elastic part, and the internal peripheral surface of the said outer cylinder. It may be interposed.

  Further, a second stopper rubber portion may be provided along the inner peripheral surface of the outer cylinder at a circumferential position opposed to the stopper rubber portion in the radial direction across the shaft member.

  The synthetic resin foam is preferably a polyurethane foam from the viewpoint of excellent dynamic characteristics and durability.

  According to the vibration isolator of the present invention, the shaft member is supported with respect to the outer cylinder by the first elastic portion made of the synthetic resin foam, and the second elastic portion made of rubber is in a general load state. The shaft member and the outer cylinder are not directly coupled, and a space portion as a stopper clearance is secured between the stopper rubber portion and the outer cylinder. Therefore, when a general load is applied, the dynamic characteristics of the synthetic resin foam having high damping performance can be exhibited against low frequency vibrations, and the swinging of the vibrating body such as an engine can be quickly damped. .

  In addition, when a heavy load is applied, such as when accelerating or starting, the stopper rubber part makes contact with the inner peripheral surface of the outer cylinder, so that the dynamic characteristics of rubber with a low dynamic spring constant can be exhibited against high-frequency vibrations. The transmission of sound to the vehicle body can be effectively blocked.

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

  1 and 2 show a vibration isolator 10 according to the first embodiment, and FIG. 3 shows a torque rod 1 including the vibration isolator 10. A torque rod 1 is installed between an automobile engine and a vehicle body, and includes a rod body composed of a rod portion 2 and cylindrical cylindrical holding portions 3 and 3 provided at both ends in the longitudinal direction L thereof. 4 and vibration isolators 10 and 10 as bushes press-fitted and fixed to the cylindrical holding portions 3 and 3.

  The vibration isolator 10 includes an inner cylinder 12 as a shaft member, an outer cylinder 14 that surrounds the inner cylinder 12 in an axial parallel manner, and an elastic body 16 that is interposed between the inner cylinder 12 and the outer cylinder 14. .

  The inner cylinder 12 is a cylindrical metal fitting having a bulge portion 18 that bulges outward at the central portion in the axial direction X, and is attached and fixed to the engine side or the vehicle body side. The outer cylinder 14 is a cylindrical metal fitting that is coaxial with the inner cylinder 12, that is, has a common axis, and is fixed by being press-fitted into the cylindrical holding portion 3 of the rod body 4.

  The elastic body 16 includes a first elastic portion 20 made of polyurethane foam and a second elastic portion 22 made of vulcanized rubber such as natural rubber.

  The second elastic portion 22 made of rubber is provided on the inner cylinder 12 side so as not to be directly coupled between the inner cylinder 12 and the outer cylinder 14. In this example, the second elastic portion 22 is vulcanized and bonded to the inner cylinder 12 so as to cover the outer peripheral surface of the inner cylinder 12 over the entire circumference.

  As shown in FIG. 1, the second elastic portion 22 is provided with a stopper rubber portion 26 that faces the inner peripheral surface 14 </ b> A of the outer cylinder 14 with a space portion 24 therebetween. The stopper rubber portion 26 is formed at one location in the circumferential direction C of the inner cylinder 12 so as to protrude toward the radially outer Y1 side, that is, toward the outer cylinder 14 side. The tip end of the stopper rubber portion 26 has an axial center as shown in FIG. 1 so that the contact area with the inner peripheral surface 14A gradually increases when contacting the inner peripheral surface 14A of the outer cylinder 14 when a heavy load is applied. An orthogonal cross-sectional shape is formed in a curved shape.

  On the other hand, the first elastic part 20 made of polyurethane foam is provided on both sides of the stopper rubber part 26 in the circumferential direction C so as to elastically support the inner cylinder 12 with respect to the outer cylinder 14. In this example, as shown in FIG. 1, a pair of first elastic portions 20, 20 are provided on both the left and right sides facing the radial direction Y across the inner cylinder 12. 2 It is interposed between 22 A of outer peripheral surfaces of the elastic part 22, and 14 A of inner peripheral surfaces of the outer cylinder 14 which opposes the outer side. The thickness T1 in the radial direction Y of the first elastic portion 20 is set to be larger than the thickness T2 in the radial direction Y of the second elastic portion 22 on the inside thereof, and the first elastic portion 20 has a thickness T1 when a general load is applied. The dynamic characteristics are configured to be dominant.

  The first elastic part 20 forms the first elastic part 20 by foaming and filling a polyurethane foam material between the second elastic part 22 and the outer cylinder 14 after the vulcanization molding of the second elastic part 22. Thus, the second elastic part 22 and the outer cylinder 14 can be bonded.

  As shown in FIG. 3, the vibration isolator 10 having the above-described structure is attached to the rod body 4 in a state of being positioned in the circumferential direction so that the protruding direction of the stopper rubber portion 26 faces the direction along the longitudinal direction L of the rod portion 2. Assembled. The longitudinal direction L is the main load input direction.

  In this vibration isolator 10, when a general load is applied, the inner cylinder 12 and the outer cylinder 14 are not directly coupled by the second elastic part 22 made of rubber, and the stopper rubber part 26 and the outer cylinder 14 A space 24 as a stopper clearance is secured between the two. For this reason, the first elastic portion 20 made of polyurethane foam having a large loss factor exhibits high damping performance with respect to vibration having a relatively large amplitude (for example, about ± 2 mm) and a low frequency (for example, about 10 Hz). And swinging of the engine can be quickly attenuated.

  On the other hand, when a heavy load is applied during acceleration or starting (for example, a load of about 1000 to 2000 N), the preload is applied so that the inner cylinder 12 is largely displaced in the main load input direction L as shown in FIG. As a result, the stopper rubber portion 26 comes into contact with the inner peripheral surface 14 </ b> A of the outer cylinder 14. In this state, vibration with a relatively small amplitude (for example, ± 0.05 mm) and a high frequency (for example, 100 Hz) is input to the vibration isolator 10 from the engine. Since the stopper rubber part 26 is in contact with the outer cylinder 14 with respect to this input vibration, the dynamic characteristics of the second elastic part 22 made of rubber having a lower dynamic spring constant than polyurethane foam becomes dominant. By reducing the dynamic spring constant of the vibration isolator 10, the transmission of sound to the vehicle body can be effectively blocked.

  FIG. 5 shows a vibration isolator 10A according to the second embodiment, and FIG. 6 is a diagram showing a state when the heavy load is applied. This vibration isolator 10A is also used for the torque rod 1 of an automobile as in the first embodiment, and the basic configuration is the same as that in the first embodiment.

  In this embodiment, a second stopper rubber portion 28 is provided along the inner peripheral surface 14A of the outer cylinder 14 at a circumferential position facing the stopper rubber portion 26 in the radial direction Y across the inner cylinder 12. ing.

  Specifically, in this example, the first elastic portion 20 made of polyurethane foam is filled between the second elastic portion 22 and the outer cylinder 14 except for the circumferential portion where the stopper rubber portion 26 is provided. Yes. An arcuate space portion 30 is provided between the first elastic portion 20 and the inner peripheral surface 14A of the outer cylinder 14 at a circumferential position opposed to the circumferential portion provided with the stopper rubber portion 26 in the diameter direction. The second stopper rubber portion 28 is provided so as to fill the space portion 30.

  Other configurations are the same as those of the first embodiment, and the second embodiment also exhibits the same effects as those of the first embodiment. In the second embodiment, the second stopper rubber portion 28 is provided, and a part 20A of the first elastic portion 20 made of polyurethane foam is interposed between the second stopper rubber portion 28 and the inner cylinder 12. As a result, a good stopper function can be exhibited when the inner cylinder 12 is displaced largely on the side opposite to the stopper rubber portion 26.

  In the above embodiment, the first elastic portion 20 made of polyurethane foam is coupled to the inner cylinder 12 with the thin second elastic portion 22 interposed therebetween. The first elastic part 20 may be directly coupled to the inner cylinder 12 by omitting the thin part.

  The present invention can be used for various vibration isolators including a bush for a torque rod of an automobile.

Sectional drawing of the vibration isolator which concerns on 1st Embodiment of this invention (II sectional view taken on the line of FIG. 2) II-II sectional view of FIG. Front view of torque rod incorporating the vibration isolator Cross-sectional view of the vibration isolator when a heavy load is applied Sectional drawing of the vibration isolator which concerns on 2nd Embodiment Sectional drawing at the time of heavy load of the vibration isolator which concerns on 2nd Embodiment

Explanation of symbols

10, 10A ... Vibration isolator 12 ... Inner cylinder (shaft member)
DESCRIPTION OF SYMBOLS 14 ... Outer cylinder, 14A ... Inner peripheral surface 16 ... Elastic body 20 ... 1st elastic part 22 ... 2nd elastic part, 22A ... Outer peripheral surface 24 ... Space part 26 ... Stopper rubber part 28 ... 2nd stopper rubber part C ... Circumference Direction X ... axial direction Y ... radial direction

Claims (4)

A shaft member;
An outer cylinder surrounding the shaft member in parallel to the axis;
An elastic body interposed between the shaft member and the outer cylinder;
An anti-vibration device comprising:
The elastic body comprises a first elastic part made of a synthetic resin foam and a second elastic part made of rubber,
The second elastic portion is provided on the shaft member side, and has a stopper rubber portion facing the inner peripheral surface of the outer cylinder with a space portion therebetween,
The first elastic portion is provided to support the shaft member with respect to the outer cylinder on both sides in the circumferential direction of the stopper rubber portion.
An anti-vibration device characterized by that. The second elastic portion is provided on the outer periphery of the shaft member over the entire circumference,
The vibration isolator according to claim 1, wherein the first elastic portion is interposed between an outer peripheral surface of the second elastic portion and an inner peripheral surface of the outer cylinder. The second stopper rubber portion is provided along the inner peripheral surface of the outer cylinder at a circumferential position opposed to the stopper rubber portion in the radial direction across the shaft member. The vibration isolator as described.   The vibration isolator according to any one of claims 1 to 3, wherein the synthetic resin foam is a polyurethane foam.

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