JP2001165219A - Vibration control bush and vibration control bush assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability by reducing the concentration of a tensile stress of a rubber elastic body in inputting load between inner/outer cylinder metal fittings in the axial and wrenching directions in a vibration control bush elastically connecting axis-perpendicularly opposite faces and axially opposite faces of the inner cylinder metal fittings and the outer cylinder metal fittings having flanges in their axial ends respectively. SOLUTION: An annular projection 46 projecting radially outward and extending circumferentially with a bent erecting face on axial both sides is formed integrally with the outer circumferential face of the rubber elastic body 42 arranged between the respective flanges 24, 28 of the inner member 18 and the outer cylinder member 20, and the annular projection 46 is positioned towards the flange 28 side of the outer cylinder member 20 than the axial center. In compression deformation of the rubber elastic body 42, the annular projection 46 is positively compressed and deformed to store the compression deformation, and in tensile deformation, the tensile stress in the outer circumferential part of the rubber elastic body 42 is relieved by the enlarging deformation of the annular projection 46 in the axial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration bush and an anti-vibration bush assembly used, for example, as a suspension bush for automobiles, and more particularly, to an anti-vibration bush in which stress concentration in a rubber elastic body is reduced and excellent durability is exhibited. The present invention relates to a vibration bush and a vibration-proof bush assembly.

[0002]

2. Description of the Related Art Conventionally, as one type of a bush assembly interposed at a pivot connection portion of a suspension arm of an automobile to a vehicle body, for example, as described in Japanese Utility Model Laid-Open No. 2-1244, an inner bush assembly has been disclosed. The metal fittings and the outer cylindrical metal fittings are arranged apart from each other in the radial direction, and the inner metal fittings and the outer cylindrical metal fittings are integrally formed with a flange portion at one axial end thereof, respectively. A pair of anti-vibration bushes having a structure in which a rubber elastic body is interposed between the opposing surfaces and between the axially opposing surfaces of the flange portions and elastically connected to each other is used. After inserting into the cylindrical arm eye formed from the axial end side where the flange portion is not formed, between the pair of mounting plate portions fixed to the vehicle body side Fitted, by allowed to pivotally supporting both inner fitting between these attachment plate portion, is that as allowed to connecting antivibration suspension arm to the vehicle body,
Are known.

In such a bush assembly, when an axial load or a prying load is input between the inner metal fitting and the outer cylindrical metal fitting in the mounted state, the inner metal fitting and the outer cylindrical metal fitting are connected to each other. A tensile load may be applied to the rubber elastic body interposed between the two flange portions. Particularly, in the conventional vibration-isolating bush, as shown in FIG. 6, the flange portion 4 of the inner fitting 2 and the outer cylindrical fitting 6 are provided.
Since the outer peripheral surface of the rubber elastic body 9 interposed between the flange portions 8 has a single substantially arc-shaped cross-sectional shape as a whole, as shown by a virtual line in the drawing. At the time of input of a torsion load, a tensile load F is applied in a direction in which the rubber elastic body 9 is peeled off from the flange portion 8 of the outer tubular metal fitting 6 in a direction substantially along the surface of the rubber elastic body 9. In this case, since concentrated stress acts on the adhesive end face of the outer cylindrical metal member 6 to the flange portion 8 in the above, cracks and the like are easily generated in the rubber elastic body 9 and there is a problem that it is difficult to obtain sufficient durability.

[0004]

Here, the present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a rubber elastic body having a tensile stress at the time of inputting a load in an axial direction or a twisting direction. Concentration is reduced or prevented,
It is an object of the present invention to provide an anti-vibration bush having a novel structure and an anti-vibration bush using the anti-vibration bush, which achieves an improvement in durability.

[0005]

An embodiment of the present invention which has been made to solve such a problem will be described below. In addition, each aspect described below can be adopted in any combination as much as possible. In addition, aspects and technical features of the present invention are not limited to those described below, but are described in the entire specification and drawings, or based on an inventive idea that can be understood by those skilled in the art from the descriptions. It should be understood that the

That is, in the first aspect of the present invention relating to the vibration-proof bush, the inner member and the outer cylinder member fixedly attached to each connected member to be vibration-isolated are separated from each other in the radial direction. At the same time, a flange portion is formed integrally with at least one axial end portion of the inner member and the outer cylinder member, so that the inner member and the outer cylinder member are opposed to each other in a direction perpendicular to the axis and in the axial direction. In the vibration-isolating bush elastically connected by interposing a rubber elastic body between the surfaces, the outer peripheral surface of the rubber elastic body positioned between the flange portions of the inner member and the outer cylindrical member, An annular projection that projects radially outward with curved rising surfaces on both sides in the axial direction and that extends in the circumferential direction is integrally formed. That it allowed located close to the flange portion side of the motor cylinder member, and wherein.

In the vibration-isolating bush having the structure according to this aspect, when a tensile load is applied to the rubber elastic body interposed between the inner member and the flange portion of the outer cylindrical member, the shaft is applied to the rubber elastic body. Direction tensile stress is generated, but since the tensile stress occurs along the surface on the outer peripheral surface of the rubber elastic body, the annular protrusion formed near the flange portion of the outer cylinder is expanded. A tensile stress acts in the direction, and the annular protrusion expands in the axial direction and is elastically deformed, so that the tensile stress on the outer peripheral surface of the rubber elastic body is reduced.

Further, since the annular projection is formed near the flange portion of the outer cylinder member, the annular projection is particularly formed on the rubber elastic body based on the action of reducing the tensile stress of the rubber elastic body based on its elastic deformation. The occurrence of cracks and the like at the bonding portion with the outer cylinder member, which is a problem, is prevented, and the durability can be improved.

In this embodiment, the radially opposed surfaces of the inner member and the outer cylindrical member may be formed in various cylindrical shapes such as a cylindrical shape, an elliptical shape, and a polygonal cylindrical shape. In addition, the rubber elastic body that elastically connects the inner member and the outer member extends integrally between the radially opposed surfaces of the inner member and the outer member and the axially opposed surfaces of the flange portions of both members. It is desirable to form it.
In addition, in consideration of elastic deformation characteristics, formability, and the like, the annular protruding portion can be advantageously formed to have, for example, a flared substantially mountain-shaped cross-sectional shape having a flat or arc-shaped protruding tip portion.

According to a second aspect of the present invention relating to an anti-vibration bush, in the anti-vibration bush having the structure according to the first aspect, the inner member and the outer member are connected to each other by anti-vibration. By being fixedly attached to the connecting member, an initial load in the axial direction is applied between the inner member and the outer member, and the inner member and the outer cylindrical member are positioned between the flange portions of the outer cylindrical member. It is characterized in that the rubber elastic body is compressed and deformed. In the vibration-isolating bush having such a structure according to this aspect, under the mounted state, a compressive force applied to the rubber elastic body generates a compressive stress along the surface of the rubber elastic body. The annular protrusion formed near the flange portion is elastically deformed in a direction in which the annular protrusion is compressed and shrunk in the axial direction to be radially protruded, whereby the amount of elastic deformation in the compression direction of the annular protrusion is advantageously reduced. It is stored. Therefore, in the vibration-isolating bush according to the present embodiment, when a tensile load is applied to the rubber elastic body in the mounted state, the rubber elastic body is compressed by the elastic deformation amount in the compression direction previously stored in the annular protrusion. Therefore, the tensile stress in the axial direction, which is generated in the above, can be reduced more effectively. The amount of compressive deformation in the axial direction applied to the rubber elastic body between the inner member and the flange portion of the outer cylindrical member is preferably 5 in a dimensional ratio (compression amount / initial size).
It is set to ％ 30%.

According to a third aspect of the present invention relating to an anti-vibration bush, in the anti-vibration bush according to the first or second aspect, the annular projecting portion of the rubber elastic body and the flange portion of the outer cylindrical member are provided. The outer peripheral surface between them has a substantially arc-shaped cross-sectional shape throughout, and the radius of curvature is smaller than the radius of curvature of the curved rising surface on the opposite side in the axial direction of the annular protrusion. That
Features. In such an embodiment, the annular projection is moved closer to the flange of the outer cylinder member while securing the free length of the rubber elastic body between the annular projection and the flange of the outer cylinder by the arc-shaped outer peripheral surface. And the surface distance of the rising surface on the flange side of the inner member in the annular projection can be set large, thereby increasing the amount of elastic deformation of the annular projection extending in the axial direction. In addition to the above, the effect of reducing the tensile stress in the bonding portion between the rubber elastic body and the flange portion of the outer cylinder member based on the elastic deformation of the annular protrusion is more effectively exerted.

According to a fourth aspect of the present invention relating to an anti-vibration bush, in the anti-vibration bush according to any one of the first to third aspects, in the rubber elastic body, the annular protrusion and the inner member may be provided. Is characterized in that the minimum value of the outer diameter dimension between the outer cylindrical member and the flange portion is smaller than the minimum value of the outer diameter dimension between the annular projection and the flange portion of the outer tubular member. In this embodiment, the surface distance (the distance along the surface of the rubber elastic body) from the bonding portion between the outer cylindrical member and the rubber elastic body to the annular protrusion is sufficiently reduced to allow the inner member to be closer to the flange portion. By increasing the surface distance of the rising surface of the ring, it is possible to increase the amount of elastic deformation in which the annular protrusion expands in the axial direction, and the tensile stress exerted by the annular protrusion on the bonding portion between the rubber elastic body and the outer cylinder member Can be reduced.

According to a fifth aspect of the present invention relating to an anti-vibration bush, in the anti-vibration bush according to any one of the first to fourth aspects, the distance between each of the flange portions of the inner member and the outer cylindrical member is set. A second annular projection that projects radially outward with rising surfaces on both sides in the axial direction and that extends continuously in the circumferential direction with respect to the outer peripheral surface of the rubber elastic body positioned at It is characterized by being located on the flange portion side of the inner member and integrally formed. In this aspect, in addition to the effect of reducing the tensile stress at the bonding portion between the rubber elastic body and the outer cylindrical member by the annular protrusion as described above, the rubber elastic body and the inner cylindrical member are formed by the second annular protrusion. Since the effect of reducing the tensile stress at the bonding site is exhibited, it is possible to more advantageously prevent the occurrence of cracks in the rubber elastic body and improve the durability.

According to a sixth aspect of the present invention relating to a vibration isolating bush, an inner member and an outer cylinder member are disposed apart from each other in a radial direction, and one end in an axial direction of the inner member and the outer cylinder member. The flange part is integrally formed on each,
A rubber elastic body is interposed between the opposed surfaces of the inner member and the outer cylindrical member in the direction perpendicular to the axis and between the opposed surfaces of the flange portions to elastically connect the inner member and the outer member. An axial vibration load is applied between the inner member and the outer cylindrical member in a state where the rubber elastic body is positioned between the respective flange portions, and the rubber elastic body positioned between the flange portions is axially compressed. In an attached state between the connected members, the outer cylindrical member is located closer to the outer peripheral surface of the rubber elastic body positioned between the flange portions of the inner member and the outer cylindrical member than the center in the axial direction. The part located close to the flange side of
It is characterized in that annular projections that protrude radially outward with curved rising surfaces on both sides in the axial direction and that extend continuously in the circumferential direction are integrally formed.

In the vibration isolating bush having the structure according to this aspect as well, the annular projection is formed integrally with the rubber elastic body in the mounted state, so that the vibration isolating bush according to the first to fifth aspects is provided. As in the case of the vibration bush, when a tensile load is applied to the rubber elastic body interposed between the inner member and the flange portion of the outer cylindrical member, the annular protrusion expands in the axial direction and is elastically deformed, so that the rubber elasticity is increased. Tensile stress at the bonding portion between the body and the outer cylinder member is reduced, and the durability of the rubber elastic body can be improved by preventing the occurrence of cracks.

A feature of the present invention relating to the vibration isolating bush assembly is that any one of the first to fifth aspects wherein a flange portion is integrally formed at one axial end of the inner member and the outer cylinder member. By using a pair of anti-vibration bushes according to the above, the inner member and the outer member of each anti-vibration bush are fixedly connected to each other by being opposed to each other at an axial end surface opposite to the flange portion. A vibration-isolating bush assembly in which an axial pre-compression is applied to a rubber elastic body positioned between each flange portion of an inner member and an outer cylinder member in a bush.

In such a vibration isolating bushing assembly having a structure according to the present invention, a pair of vibration isolating bushes are arranged to face each other in the axial direction, so that any one of the vibration isolating bushes can be applied to any one of the axial loads. The compression load will be applied to the rubber elastic body between the flange parts in the anti-vibration bush of
Vibration isolation performance and load bearing performance in both axial directions are advantageously ensured. In addition, even in the vibration-isolating bush on the side where a tensile load is applied to the rubber elastic body between the flange portions, the effect of reducing the tensile stress of the rubber elastic body by the annular projection is exhibited, so that excellent durability is exhibited. It is.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

First, FIG. 1 shows an embodiment of the present invention, in which a suspension arm in a wheel suspension system of an automobile is interposed in a pivotally connecting portion with respect to a vehicle body, and the suspension arm can swing with respect to the vehicle body. An anti-vibration bushing assembly 10 is shown that is coupled to the anti-vibration bush. The anti-vibration bush assembly 10 includes a pair of anti-vibration bushes 12 and 12.
An arm eye 14 as a mounting cylinder member, which is a connected member integrally formed at an axial end of a suspension arm (not shown), and a pair of mounting plate members, which are connected members fixed to a vehicle body (not shown). Fixed opposed plates 16, 16
The arm eye 14 (suspension arm) is interposed between the fixed opposing plates 16 and 16 (vehicle body) so as to be swingable about a central axis.

More specifically, each of the pair of vibration isolating bushes 12 has the same structure as shown in FIG. The anti-vibration bush 12 has an inner cylindrical member 18 as an inner member and an outer cylindrical member 20 as an outer cylindrical member. The inner cylindrical member 18 includes a cylindrical portion 22 having a thick cylindrical shape, and a flange portion 24 that extends radially outward from one axial end of the cylindrical portion 22. Similarly, the outer tube fitting 20 also includes a cylindrical tube portion 26 and a flange portion 28 that extends radially outward from one axial end of the tube portion 26. The inner and outer tube fittings 18 and 20 are advantageously formed by press working, forging work, cutting work, or the like. Here, the outer cylindrical member 20 is thinner than the inner cylindrical member 18, and the cylindrical portion 26 has a larger diameter than the cylindrical portion 22 of the inner cylindrical member 18 by a predetermined size and a shorter axial length. It is disposed on the same axis at a predetermined distance radially outward of the inner cylindrical fitting 18.

Further, the flange 24 of the inner cylinder 18 and the flange 28 of the outer cylinder 20 are positioned on the same side in the axial direction, and the outer cylinder 20 is connected to the inner cylinder 1.
8, the axial end face 33 of the outer cylindrical fitting 20 on the side where the flange 28 is not formed is biased toward the axial end side opposite to the flange part 24. Are located axially inward in the axial direction by a predetermined distance: L1 from the axial end face 36 on the side where the flange portion 24 is not formed. In addition, the flange portions 24, 28 of the inner and outer tube fittings 18, 20 are axially separated from each other by a predetermined distance: L
2 are opposed to each other.

The flange 28 of the outer tube fitting 20 is
The inner diameter is larger than the outer diameter of the cylindrical portion 22 of the inner cylinder 18 and smaller than the outer diameter of the flange 24 of the inner cylinder 18, and is smaller than the outer diameter of the flange 24 of the inner cylinder 18. It is formed with a large outer diameter. Also,
The axial inner side surface 30 of the flange portion 24 of the inner cylinder fitting 18 is
It has a substantially arcuate curved cross section that gradually approaches the outer cylinder fitting 20 as it goes inward in the radial direction. Furthermore, the axial end face of the inner cylindrical member 18 on the flange portion 24 side is formed by serration and quenching of the central portion 36 in an annular shape to be a pressure fixing surface to the fixed opposing plate 16.
The inner hole 32 of the inner cylindrical member 18 has an axial end portion opposite to the flange portion 24 and has a large diameter in a predetermined length in the axial direction, and a large diameter opening on one side in the axial direction. And the connection fixing portion 34.

A rubber elastic body 38 is provided between the inner cylindrical member 18 and the outer cylindrical member 20 which are spaced apart in the radial direction as described above.
Is interposed. Then, for the rubber elastic body 38,
The outer peripheral surface of the cylindrical portion 22 in the inner cylindrical member 18, the axial inner surface of the flange portion 24, and the cylindrical portion 2 in the outer cylindrical member 20.
6 and the axially outer surface of the flange portion 28 are integrally vulcanized and formed by vulcanization bonding. In short, the rubber elastic body 38 has a thick, substantially cylindrical shape as a whole, and is provided between the inner and outer cylindrical fittings 18 and 20 and between the radially opposed surfaces of the cylindrical portions 22 and 26. It comprises an annular rubber portion 40 and an annular rubber portion 42 interposed between the axially opposed surfaces of the flange portions 24 and 28. And, by these cylindrical rubber portion 40 and annular rubber portion 42,
The space between the axially and radially opposed surfaces of the inner and outer tube fittings 18 and 20 is substantially entirely filled.

After vulcanization molding of the rubber elastic body 38,
If necessary, the cylindrical portion 26 of the outer metal fitting 20 is reduced in diameter by an eight-way drawing process or the like, so that the tensile stress of the rubber elastic body 38 is eliminated and precompression is applied.

Further, the cylindrical rubber portion 40 has a concave portion 44 having a semicircular or U-shaped cross section which opens toward the axial end face between the cylindrical portions 22 and 26 of the inner and outer cylindrical fittings 18 and 20. , Are formed continuously or discontinuously in the circumferential direction. On the other hand, the annular rubber portion 42 is disposed over substantially the entire axially facing surface of each of the flange portions 24 and 28 of the inner and outer cylindrical fittings 18 and 20. The end of the outer tube fitting 20 on the flange portion 28 side has a slightly larger diameter than the portion. The outer peripheral surface of the annular rubber portion 42 is
As a whole, the central portion in the axial direction has a concave curved cross section with a reduced diameter, and the bonding portions to the flange portions 24 and 28 at both axial end portions of the annular rubber portion 42 respectively have
Fillet are attached.

On the outer peripheral surface of the annular rubber portion 42, an intermediate portion in the axial direction is projected radially outward, so that the intermediate portion in the axial direction is formed as an annular projection extending continuously in the circumferential direction. Are formed integrally with each other. In the axial cross section shown in FIG. 2, the annular elastic projection 46 has a substantially flat top portion 48 at the tip end, and a curved surface that gradually extends in the axial direction on both sides in the axial direction with the top portion 48 interposed therebetween. 50, 50, which are continuously formed in the circumferential direction with a substantially constant mountain-shaped cross section as a whole. In other words, the outer peripheral surface of the annular rubber portion 42 is curved at the axially intermediate portion on both side rising surfaces 50 and 5.
An annular elastic projection 46 is formed to protrude outward in the radial direction with 0. Further, on the outer peripheral surface of the rubber elastic body 38, on both sides in the axial direction with the annular elastic protrusion 46 interposed therebetween,
Recessed groove-shaped portions that open radially outward and extend in the circumferential direction are formed. In particular, in the rubber elastic body 38, between the portion of the inner cylinder fitting 18 that is bonded to the flange portion 24 and the annular elastic protrusion 46, both of the portion that is bonded to the flange portion 24 and the annular elastic protrusion 46 are smaller. A small outer diameter portion is formed, and a fillet radius is attached to a bonding portion of the outer peripheral portion of the rubber elastic body 38 to the flange portion 24.

Further, the annular elastic projection 46 is formed between the outer cylindrical metal fitting 20 and the annular rubber portion 42 more than the intermediate portion in the axial direction.
Is formed close to the flange portion 28 side. In other words, the axial distance between the annular elastic projection 46 and the flange 28 of the outer cylinder 20 is L2b, rather than the axial distance L2a between the annular elastic protrusion 46 and the flange 24 of the inner cylinder 18. Is set smaller. In particular, in this embodiment, L2a ≧ L2b × 2. Further, in the present embodiment, in the axial section as shown in FIG. 2, the outer peripheral surfaces of the annular rubber portions 42 located on both sides in the axial direction with the annular elastic projection 46 interposed therebetween are both substantially arc-shaped. The annular elastic protrusion 46 and the flange 2 of the outer cylinder fitting 20.
8 is set to be smaller than the radius of curvature: Ra of the outer peripheral surface located between the annular elastic projection 46 and the flange portion 24 of the inner cylinder 18. In addition, this allows the annular elastic projection 46 and the outer cylinder 2
The minimum outer diameter dimension of the annular rubber portion 42 between the zero flange portions 28: rb is smaller than the minimum outer diameter dimension of the annular rubber portion 42 between the annular elastic projection 46 and the flange portion 24 of the inner cylindrical member 18: ra. Is also set large.

As shown in FIG. 1, the pair of anti-vibration bushes 12 and 12 each having the above-described structure are configured such that the outer cylindrical metal fittings 20 are formed with respect to the arm eyes 14.
At the axial end on the side where the flange portion 28 is not formed, the arm eye 14 is inserted and assembled by being press-fitted from both axial sides. Here, the cylindrical portion 26 of the outer cylindrical member 20 constitutes a press-fit portion for the arm eye 14 as a whole. Also,
In each of the vibration-isolating bushes 12, the axial length of the cylindrical portion 26 of the outer cylindrical fitting 20 is shorter than half the axial length of the arm eye 14, and the flange 28 of the outer cylindrical fitting 20 is The insertion end with respect to the arm eye 14 is positioned by contacting the axial end surface. In such a positioning state, an annular gap 52 extending continuously in the circumferential direction is formed between the axial end faces of the outer cylindrical fittings 20, 20 and the cylindrical rubber portions 40, 40.

Further, such a pair of anti-vibration bushes 1
At the time of assembling with the arm eyes 14, the connecting fixing portions 34 of the inner cylindrical fittings 18,
Both ends in the axial direction of the cylindrical connecting tube fitting 54 are press-fitted and fixed.
8, 18 are connected and fixed to each other with their axial end faces abutting each other. Further, a pair of vibration isolating bushes 12, 12 by connecting the inner cylindrical fittings 18, 18 as described above.
In the assembled state, the distance between the axial end faces of the inner cylindrical fittings 18, 18 on the flange portion 24 side, in other words, the pair of vibration isolating bushes 12, 1 assembled to the arm eye 14.
2 preferably has a maximum axial dimension L3 substantially equal to the distance between the opposing surfaces of the pair of fixed opposing plates 16 to which the arm eye 14 is vibration-isolated.
The axial length of the inner cylindrical member 18 is set to be a pair of the fixed opposing plates 1 so as to be slightly smaller than the distance between the opposing surfaces 6 and 16.
The size is set in consideration of the dimension between 6 and 16.

In short, as described above, the inner tube fittings 18, 18
Are connected and integrated with each other by a connecting cylinder fitting 54, and a pair of vibration isolating bushes 12, 12 attached to the arm eye 14.
In the vibration-isolating bush assembly 10 composed of the vibration-isolating bushes 12, each of the vibration-isolating bushes 12 is, as shown by a virtual line in FIG.
Are mutually displaced in the axial direction, and the two cylindrical fittings 18, 2 are displaced.
That is, the distance between the axially opposed surfaces between the 0 flange portions 24 and 28 is reduced. In addition, the inner and outer cylindrical fittings 1
A compressive load is applied in the axial direction to the annular rubber portion 42 disposed between the two flange portions 24 and 28 based on the relative displacement of the annular rubber portions 8 and 20 in the axial direction.
The inner and outer cylindrical fittings 18 and 20 are compressed and deformed in the axial direction by the relative displacement amount L4 in the axial direction.

When the annular rubber portion 42 is compressed and deformed in the axial direction, the axial compressive force applied to the outer peripheral portion of the annular rubber portion 42 acts substantially along the outer peripheral surface of the annular rubber portion 42. A compression force directed radially outward from both sides in the axial direction is exerted on the portion where the annular elastic projection 46 is formed, so that the annular elastic projection 46 projects radially outward while being compressed in the axial direction. Elastically deformed. Accordingly, the compressive deformation is collected from both sides in the axial direction toward the annular elastic protrusion 46, so that the annular elastic protrusion 46 is positively elastically deformed.

As shown in FIG. 1, the pair of anti-vibration bushes 12, 12 assembled to the arm eye 14 further comprises a pair of fixed opposing plates 16, 16 fixed to the vehicle body side. The two vibration-isolating bushes 12, 12 are disposed in a state of being arranged in series so as to be fitted between the pair of fixed opposing plates 16, 16. Then, a support bolt 56 that is inserted into a through hole provided in the pair of fixed opposing plates 16 and 16 and that is disposed so as to straddle the pair of fixed opposing plates 16 and 16 is provided.
The anti-vibration bush assembly 10 is supported by the fixed opposing plates 16, 16 via support bolts 56 by being inserted into the inner holes 32, 32 of the anti-vibration bushes 12, 12.

The support bolt 56 inserted into the vibration isolating bush assembly 10 is tightened, and the pair of fixed opposing plates 16, 16 are deformed in a direction approaching each other, so that they are connected and integrated in the axial direction. Inner tube fittings 18 and 1
8, an axial clamping force is exerted. Due to this tightening force, the serrated portions on the axially outer surfaces 36 of both inner cylindrical fittings 18 are pressed against the contact surfaces of the fixed opposed plates 16.

That is, in the vibration-isolating bush assembly 10 assembled in this manner, the inner cylindrical fittings 18, 1 are provided.
The pair of fixed opposing plates 16, 16 to which the fixing member 8 is fixed and the arm eye 14 to which the outer metal fittings 20, 20 are fixed are elastically connected via rubber elastic members 38, 38. Based on the elastic deformation action of
The suspension arm on the arm eye 14 side is swingably connected to the vehicle body on the fixed opposing plate 16 side in a vibration-damping manner.

In the vibration isolating bush assembly 10 assembled as described above, loads are input not only in the direction perpendicular to the axis but also in the axial direction and the twisting direction. Since the annular projection 46 formed integrally with the annular rubber portion 42 is actively compressed and deformed in the axial direction, the rubber elastic body 3 when a load is input is provided.
This reduces or avoids the concentration of tensile stress on the substrate 8, thereby preventing the occurrence of cracks and the like.

That is, as shown in FIG. 3, for example, a load in the prying direction is input between the inner and outer cylindrical fittings 18 and 20, and as shown by a virtual line,
When the prying 20 is relatively distorted, the flange portions 24, 28 of the inner and outer cylindrical fittings 18, 20 are displaced relative to each other in the axial direction on one radial side of the prying surface. Accordingly, tensile deformation is caused particularly on the outer peripheral surface of the annular rubber portion 42 interposed therebetween. However, since an annular elastic projection 46 which is positively deformed by compression is formed on the outer peripheral surface of the annular rubber portion 42, when a tensile force is applied to the annular rubber portion 42, the annular elastic projection is formed. 46 is elastically deformed in a direction that spreads to both sides in the axial direction so as to release the stored compressive deformation, whereby the tensile stress near the annular elastic protrusion 46 is reduced or avoided. Becomes Since the annular elastic projection 46 is formed near the bonding portion of the outer tube fitting 20 to the flange portion 28 where the concentration of tensile stress is particularly likely to be a problem, the maximum generated in the annular rubber portion 42 can be obtained. The tensile stress is suppressed, and the occurrence of cracks and the like in the annular rubber portion 42 is prevented,
Thus, excellent durability is realized.

In the present embodiment, in particular, the annular rubber portion 4
2, since the outer peripheral surfaces on both sides in the axial direction with the annular elastic projection 46 interposed therebetween are each a continuous arc-shaped cross section having a substantially constant radius of curvature, stress concentration on the surface of the annular rubber portion 42. Can be more advantageously achieved, and the durability can be further improved.

Further, in the present embodiment, in the annular rubber portion 42 of the vibration isolating bush 12 in a single state before assembly, the outer peripheral surfaces on both sides sandwiching the annular elastic projection 46 in the axial direction have a substantially arc shape. In addition, the radius of curvature: Rb on the flange portion 28 side of the outer cylinder 20 is smaller than the radius of curvature: Rb on the flange portion 24 side of the inner cylinder 18. Minimum outside diameter of 24 side:
Since the minimum outer diameter dimension: rb on the flange portion 28 side of the outer cylindrical member 20 is larger than ra, the outer cylindrical member 20 of the rubber elastic body 38 by the action of the annular elastic protrusion 46 as described above. Thus, the effect of reducing the tensile stress in the vicinity of the bonded portion can be more effectively exerted.

The embodiment of the present invention has been described above in detail, but this is merely an example.
It is not to be construed that the invention is limited only to such specific examples.

For example, in order to adjust the spring characteristics of the vibration-isolating bush 12, a hollow portion or a hollow portion extending continuously or at a predetermined length in the circumferential direction may be formed on the rubber elastic body 38. It is possible. Also, an intermediate cylindrical metal fitting extending continuously in the circumferential direction between the facing surfaces of the inner cylindrical metal fitting 18 and the outer cylindrical metal fitting 20 or an intermediate plate metal fitting extending a predetermined length in the circumferential direction is provided so that the rubber elastic body 38 is provided. It is also possible to embed and fix it. As described in Japanese Utility Model Application Laid-Open No. 2-1244 and the like, the flange portions 24, 28 of the inner and outer cylindrical fittings 18, 20 are provided between the facing surfaces of the inner and outer tubular fittings 18, 20.
In the case of employing an intermediate cylindrical member having a flange-shaped portion extending to the middle, the intermediate cylindrical member becomes an inner cylindrical member with respect to the outer cylindrical member 20. The present invention is applied as a cylindrical metal fitting.

In the annular rubber portion 42, the outer peripheral surfaces on both sides in the axial direction with the annular elastic projection 46 interposed therebetween do not necessarily have to have an arc-shaped cross section. For example, as shown in FIG. 4, the annular elastic projection 46 and the inner cylindrical fitting 18 and the outer cylindrical fitting 2 are provided.
In the axially intermediate portion between the flange portions 24 and 28, a cylindrical outer peripheral surface portion 60 that extends straight in the axial direction.
May be provided.

Further, as shown in FIG. 5, a second annular projection 62 having a structure similar to that of the annular elastic projection 46 as described above is provided on the outer peripheral surface of the annular rubber portion 42. It may be formed at a position closer to the flange portion 24 of the inner cylindrical member 18 than the center in the axial direction. By forming such a second annular protrusion 62, the annular rubber portion 42 can be attached to the inner cylindrical member 18. Even in the vicinity of the bonded portion, the tensile stress is reduced, and the occurrence of cracks and the like is prevented. In FIGS. 4 and 5, in order to facilitate understanding, the members and the parts having the same structure as the vibration-isolating bush 12 in the first embodiment are shown in FIGS. The same reference numerals as in the first embodiment denote the same.

As described above, the annular elastic projection 46 on the outer peripheral surface of the annular rubber portion 42 and the second annular elastic projection 6
A plurality of 2 may be formed apart from each other in the axial direction of the annular rubber portion 42.

Further, the inner cylindrical fitting 18 and the outer cylindrical fitting 20
For example, it is also possible to adopt a structure in which an annular flat plate-shaped flange portion is fixed to an axial end portion of a cylindrical metal fitting having substantially constant inner and outer diameter dimensions by welding or the like.

Further, in the vibration-isolating bush assembly 10 in the above-described embodiment, a pair of vibration-isolating bushes 12 and 12 having a flange portion and an annular rubber portion at one end in the axial direction are formed by opening the arm eye 14 at both axial sides. Although it was designed to be fitted and assembled from the part, in addition, after a pair of anti-vibration bushes were connected and integrated in the axial direction in advance, the cylindrical part divided in the circumferential direction was attached to the outer cylindrical metal fitting from both sides in the radial direction. By being fitted, it is also possible to mount a vibration isolating bush. Also,
When such a mounting structure is adopted, it is also possible to employ an inner cylinder fitting and an outer cylinder fitting each composed of a single member provided with flange portions at both ends in the axial direction. The anti-vibration bush assembly in the form can be realized by a single anti-vibration bush.

In addition, in the preceding embodiment, a specific example in which the present invention is applied to a vibration-proof connecting member for a vehicle body of a suspension arm of an automobile is shown. Needless to say, it can be widely applied to an interposed elastic connector or the like.

In addition, although not enumerated one by one, the present invention
Based on the knowledge of those skilled in the art, the present invention can be implemented in a form in which various changes, modifications, improvements, and the like are made.
It goes without saying that all such embodiments are included within the scope of the present invention, without departing from the spirit of the present invention.

[0048]

As is apparent from the above description, in the vibration isolating bush having the structure according to the present invention and the vibration isolating bush assembly using the same, each of the flanges of the inner member and the outer cylindrical member is provided. Of the outer peripheral surface of the rubber elastic body interposed between the parts, the concentration of tensile stress in the vicinity of the bonding portion to the outer member, which is particularly problematic, is reduced by the annular protrusion integrally formed on the outer peripheral surface of the rubber elastic body. As a result, the occurrence of cracks in the rubber elastic body can be prevented, and the durability can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory longitudinal sectional view showing an anti-vibration bush assembly as one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a single vibration-isolating bush constituting the vibration-isolating bush assembly shown in FIG.

FIG. 3 is an explanatory longitudinal sectional view for explaining an operation of the vibration isolating bush when a twisting load is input to the vibration isolating bush assembly shown in FIG. 1;

FIG. 4 is a longitudinal sectional view showing a main part of a single vibration-isolating bush as another embodiment of the present invention.

FIG. 5 is a longitudinal sectional view showing a main part of a single vibration-isolating bush as still another embodiment of the present invention.

FIG. 6 is an explanatory longitudinal sectional view showing a state of input of a torsion load in a vibration-proof bush having a conventional structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vibration-proof bush assembly 12 Vibration-proof bush 14 Arm eye 16 Fixed opposing plate 18 Inner cylinder 20 Outer cylinder 22 Cylindrical part 24 Flange part 26 Cylindrical part 28 Flange 38 Rubber elastic body 40 Cylindrical rubber part 42 Part 46 annular elastic projection 56 support bolt

Claims (7)

[Claims] An inner member and an outer cylinder member fixedly attached to each connected member to be vibration-isolated are disposed apart from each other in a radial direction, and the inner member and the outer cylinder member are separated from each other. At least one flange portion is integrally formed at one end in the axial direction, and a rubber elastic body is interposed between opposing surfaces of the inner member and the outer cylinder member in the direction perpendicular to the axis and between the opposing surfaces of the flange portions. In the vibration-isolating bush connected to the outer circumferential surface of the rubber elastic body positioned between the respective flange portions of the inner member and the outer tubular member, a radially outer side is provided with rising surfaces on both sides in the axial direction that are curved. And an annular projecting portion extending in the circumferential direction is integrally formed, and the annular projecting portion is positioned closer to the flange portion side of the outer tubular member than the center in the axial direction. Vibration-isolating bush to be characterized. 2. An axial initial load is applied between the inner member and the outer member by fixedly attaching the inner member and the outer member to the respective connected members to be vibration-isolated. 2. The vibration-isolating bush according to claim 1, wherein the rubber elastic body positioned between the flanges of the inner member and the outer cylindrical member is compressed and deformed. 3. An outer peripheral surface of the rubber elastic body between the annular projecting portion and a flange portion of the outer cylinder member has a substantially arc-shaped cross-sectional shape throughout, and has a radius of curvature. The anti-vibration bush according to claim 1, wherein a radius of curvature of a curved rising surface on the opposite side in the axial direction of the annular protrusion is smaller than a radius of curvature. 4. The rubber elastic body, wherein a minimum value of an outer diameter between the annular protrusion and the flange of the inner member is determined by a distance between the annular protrusion and the flange of the outer tubular member. The anti-vibration bush according to any one of claims 1 to 3, wherein the outer diameter is smaller than a minimum value. 5. An outer peripheral surface of the rubber elastic body positioned between respective flange portions of the inner member and the outer cylindrical member, and protrudes radially outward with curved rising surfaces on both sides in the axial direction, The anti-vibration bush according to any one of claims 1 to 4, wherein the second annular projecting portion extending continuously in the circumferential direction is located on the flange portion side of the inner member with respect to the center in the axial direction and is integrally formed. 6. An inner member and an outer cylindrical member are disposed apart from each other in a radial direction, and a flange portion is integrally formed at one axial end of the inner member and the outer cylindrical member, respectively. A rubber elastic body is interposed between the opposed surfaces of the outer cylinder member in the direction perpendicular to the axis and between the opposed surfaces of the flange portions to elastically connect the inner member and the outer member, while being attached to the connected members. An anti-vibration bush under which an axial load is applied between the inner member and the outer cylindrical member, and the rubber elastic body positioned between the flange portions is compressed in the axial direction. In the mounted state between the members, the outer cylindrical member is positioned at a position closer to the outer peripheral surface of the rubber elastic body positioned between the flange portions of the inner member and the outer cylindrical member than the center in the axial direction. In the portion located close to the flange portion side, the annular protrusion protruding radially outward with the curved rising surfaces on both sides in the axial direction and continuously extending in the circumferential direction is integrally formed. Anti-vibration bush. 7. An anti-vibration bush according to claim 1, wherein said flange portion is integrally formed at one axial end of said inner member and said outer cylindrical member. The inner member and the outer member of the bush are opposed to each other at the axial end surface opposite to the flange portion and fixedly connected to each other, so that in each of these vibration-isolating bushes, each flange portion of the inner member and the outer cylindrical member is provided. An anti-vibration bush assembly, wherein axial pre-compression is applied to a rubber elastic body positioned between the two.