JPH02275127A - Elastic bush - Google Patents

Abstract

PURPOSE: To improve fatigue life of a resilient bush having a reinforced intermediate layer by reinforcing the interlayer of resilient elastomer material by a tubular reinforcing layer made of a material deformable in response to the compressive force generated in the radial tubular part. CONSTITUTION: A resilient bush 10 having a circular section includes inner and outer side members 11, 12 made of steel, and a resilient elastomer interlayer 13 formed by two parts 15, 16 made of natural rubber. The respective parts 15, 16 are made adhere to the opposing faces of rigid members 11, 12 between the rigid members 11, 12. Subsequently to assembling of the bush 10 and adhesion of the opposing faces of the rigid members 11, 12 and the sleeve 14 to the inner and outer parts 16, 15 of the interlayer 13, the outer part 15 is put in the pre-load state by the radial reduction of the outer rigid member 12. Accordingly, the sleeve 14 is subjected to the compressive hoop stress to be decreased in diameter, so that the inner part 16 of the interlayer 13 applies the compressive force to the outer surface of the inner rigid member 11.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an elastic bushing, comprising an inner rigid member (11);
outer rigid members (1) extending spaced apart around the inner rigid member;
2) and an intermediate layer (13) of resilient elastomeric material extending between said inner and outer rigid members (11112) and bonding them together. The invention particularly relates to an elastic bushing of the type described above, in which the intermediate layer (13) of said elastic elastomeric material is provided with an embedded reinforcement (14), so that if the intermediate layer is not accompanied by a reinforcement, In contrast, it relates to an elastic bushing with increased radial stiffness of the bushing.

The invention also relates to, but is not limited to, an elastic bushing having embedded reinforcement as described above and in which the elastomeric material is radially precompressed.

Prior Art In one established form of this type of resilient bushing, the buried reinforcement was a tubular steel insert. In this, the elastic elastomeric intermediate layer is divided into radially inner and radially outer tubular sections, which are conventionally secured to the steel insert by adhesive. The radial precompression of the intermediate layer is achieved by swaging the outer rigid member (swaging process: a process in which a tube material is compressed between tools to reduce its thickness or diameter). Part □
This is done by pre-compressing the material. At the same time, the radially inner tubular portion of the intermediate layer is precompressed by expansion of the inner rigid member (which also has a tubular cross-sectional shape).

Although the bushing configuration described above exhibits good performance and fatigue life when used in many applications, during its processing two operations are required to provide precompression to the radially inner and outer portions of the reinforcing elastic elastomer material. That is, since it is necessary to perform swaging processing and expansion processing, there are disadvantages in that manufacturing takes time and increases cost. Furthermore, the bushing necessarily needs to have a tubular inner rigid member rather than a solid configuration. Additionally, in some applications, the fatigue life of the elastic bushings has not been as high as desired.

In order to avoid the need for the above swaging and expansion operations and to enable the use of solid inner rigid members, it has been proposed to use an intermediate layer reinforcement consisting of a pair of semi-cylindrical steel shells. According to this, as in the case of tubular steel reinforcements, the pair of steel shells is glued to the radially inner and outer portions of the intermediate layer. During initial assembly, adjacent longitudinal ends of each shell are spaced slightly circumferentially apart. Simultaneously with the swaging of the outer rigid member, the radially outer portion of the intermediate layer is compressed to urge adjacent ends of each shell toward each other without requiring expansion of the inner rigid member. This creates a compressive force in the radially inner portion of the intermediate layer.

Therefore, manufacturing can be facilitated by using a pair of semi-cylindrical shell reinforcements, and it is also possible to use an inner rigid member with a solid cross-section.

Problems to be Solved However, in many product applications these advantages are often offset by reduced fatigue life.

Particularly undesirable stresses are concentrated in the adjacent longitudinal end regions of each shell, which leads to premature fatigue failure of the bushing.

It was also difficult to properly position the shell within the molding tool.

OBJECTS AND SUMMARY OF THE INVENTION The broadest object of the invention is to provide an improved elastic bushing of the type having a reinforcing intermediate layer. Another object of the invention is to provide an improved radially prestressed elastic bushing which can facilitate the production of bushings of the kind with semi-cylindrical reinforcements, according to which the hollow cross-sectional shape It is possible to eliminate the use of an inner rigid member and can be designed to have good fatigue life.

According to the invention, the intermediate layer of elastic elastomeric material of the elastic bushing is reinforced by a tubular reinforcing layer of material capable of deforming in response to compressive forces exerted on the radially inner and outer tubular portions of the intermediate layer. There is. Preferably the tubular reinforcing layer is capable of responding to any compressive force caused by each radial expansion or contraction of the inner or outer rigid member;
This creates radial compressive forces on other portions of the radially inner and outer tubular portions of the intermediate layer.

For the avoidance of doubt, in this specification "variations (
The term "deform" means both a change in shape, that is, a local change in shape, and a change in dimension, which does not necessarily involve a change in shape.

In the present invention, the tubular reinforcing layer will be a non-metallic material as compared to the previously used steel materials.

Accordingly, the present invention utilizes a tubular, one-piece type of reinforcement as opposed to a conventional multi-shell multi-piece assembly;
Moreover, the reinforcing body is made of a substantially semi-rigid material compared to the highly rigid steel material used in the past.

The material of the semi-rigid reinforcement is s, ooo~7.0000Kgf
/cm2, and more preferably in the range of 16,000 to 30,000 kg17 cm2. Thus, swaging of the outer rigid member creates a radial compressive force on the radially outer portion of the elastic elastomer intermediate layer and a compressive force on the tubular reinforcement.
- creating a compressive stress which, in conjunction with the Young's modulus of the reinforcement material, necessarily creates a radial compressive force in the radially inner portion of the intermediate layer of elastic elastomeric material.

Conversely, if the inner rigid member were to have a tubular shape and the inner rigid member was subjected to an expansion operation, it would create a radial compressive force on the radially inner portion of the intermediate layer, which would inevitably cause a tensile force on the tubular reinforcement. Causes hoop stress.

The tubular reinforcement thus provides sufficient radial expansion to provide the necessary radial compression of the outer portion of the elastic elastomeric intermediate layer. In general, it is operationally advantageous to apply a radial compressive force to the outer rigid member and thereby achieve compression of the radially concentric portion of the intermediate layer, which is due to expansion of the inner rigid member. This has the advantage that compression of the radially outer part can be achieved more easily than with the radially outer part.

Another object of the invention is that the intermediate layer of elastic elastomeric material has a bending strength in the range of 600-2,500 Kgf/cm'', preferably 900-1°000' Kg.
It is reinforced by a tubular reinforcing layer made of a material with a bending strength of f/cm''.

By providing a tubular reinforcing layer made of a material having a wide range of bending strengths as described above, when the bushing undergoes relative radial or conical movement between the inner and outer rigid members, the reinforcing layer is Appropriate deformation can occur, thereby avoiding or reducing the occurrence of undesirably high stress concentrations which normally have an unfortunate effect on the fatigue life of the bushing.

Generally, a tubular reinforcing layer of a given thickness can be suitably provided by a material having a bending strength over a wide range as described above, and more preferably over a limited range as described above. The predetermined thickness is such that it provides the reinforcing effect necessary to stiffen the bushing to specifically withstand relative radial movement of the inner and outer rigid members, but may not be applied to the radially inner or outer sides of the intermediate layer, if desired. The thickness must be such that it is suitably circumferentially compressible or expandable in transmitting radial compressive forces from one section to another section of the intermediate layer.

According to the invention, it is further preferred that the tubular reinforcing layer is deformable only within its elastic limits during use of the bushing.

Thus, when the bushing is released from an externally applied load, the tubular reinforcing layer will inherently tend to return to its original shape and configuration.

Particularly suitable non-metallic materials for forming the tubular reinforcing layer are polyamide, nylon 6 and nylon 66, acetal, Hytrel sad Delrin.
Contains plastic materials such as. The reinforcing layer is a textile type (f
The tubular reinforcing layer is usually made of a non-textile material (abric LyPe) IR construction, but generally this will not have a sufficiently high bending strength.
It is intended to be formed from a tubular layer of stator (l). However, the reinforcing layer may also consist of embedded reinforcing bodies. (Then, the tubular reinforcement is e.g.
It may consist of a tubular sleeve of nylon 6 with embedded reinforcement of fiberglass beads or spheres or textile material.

The tubular reinforcing layer may have at least one hole formed in its wall. This facilitates the flow of material radially inwardly or outwardly through the reinforcing layer during the molding operation to form the radially inner and outer portions of the elastic elastomer intermediate layer.

Furthermore, this allows continuity and mechanical bonding between the molded materials of the radially inner and outer portions of the intermediate layer. Preferably, the reinforcing layer has at least one circumferentially arranged series of holes.

The radial thickness of the tubular reinforcing layer is typically 15% to 25% of the radial distance between opposing surfaces of the inner and outer rigid members.
is intended to be within the range of

This has, on average, a thickness in the range of 10% to 20% of the radial distance of the opposing surfaces of the traditionally used tubular or semi-cylindrical reinforcements, typically the inner and outer rigid members. Contrasted with things.

In order to further reduce or eliminate stress concentrations, one or preferably both axial ends of the tubular reinforcing layer have a reduced wall thickness compared to the central portion of the layer.

The inner and outer surfaces of the reinforcing layer may be shaped to give the layer a tapered end region.

An embodiment of the invention will now be described with reference to the accompanying drawings.

Embodiment As shown in FIGS. 1 and 2, an elastic bushing 10 having a circular cross section is provided with inner and outer rigid members 11 and 1 made of steel, respectively.
2 and an elastic elastomer intermediate layer 13 consisting of two parts 15, 16 made of natural rubber. Each part 15
．． 16 is between the rigid members 11 and 12.
, 12 are adhered to the opposing surfaces of the plates.

The rubber intermediate layer 13 is reinforced by a tubular reinforcing sleeve 14 made of nylon 66 and is divided by this sleeve 14 into a radially inner section 16 and a radially outer section 15, each section 16.15 being glued to the sleeve 14. There is.

Sleeve 14 is formed of nylon 66 over a major portion of its length and has a thickness of 1.5 mm. This thickness corresponds to the distance 6,5 mm between the opposing outer and inner surfaces of the inner and outer rigid members 11.12.
This corresponds to 3%. The axial end of the wall of the sleeve 14 has a tapered cross section. This is achieved by chamfering the inner and outer surfaces of the sleeve 14 at each of its axial ends.

Nylon 66 material is 880K g f/c
m 2 and a Young's modulus of 1 g, 000 Kgf/cm”. The sleeve 14 has a thickness of 1.5 mm in this case, an axial length of 3 mm and an average diameter of 24° 5 mm.

The axial length of the outer rigid member 12 is smaller than that of the inner rigid member 11 and the axial length of the sleeve 14 is intermediate between the axial lengths of the inner and outer members 11,12. Sleeve 14
is located approximately radially intermediate between the inner and outer members 11 , 12 , but slightly closer to the inner member 11 . Thereby, the inner and outer portions 1 of the elastic intermediate layer 13
6.15 have substantially equal volumes.

The inner rigid member 11 has a relatively thick wall cross section and has both ends 1
A circumferential recess 18 having an axial length corresponding to the axial length of the sleeve 14 is provided between the sleeves 14 and 7.

Assembly of the above elastic bushing 10 and rigid member 11%
The facing surfaces of the sleeve 12 and the sleeve 14 are covered with an elastomer intermediate layer 1.
Following bonding with the inner and outer portions 16.15 of 3, radial reduction of the outer rigid member 12 causes the outer portion 15
is placed under preload.

As a result, the inner portion 16 of the intermediate layer 13 exerts a compressive force on the outer surface of the inner rigid member 11 as the sleeve 14 is subjected to a compressive stress and is reduced in diameter.

According to a further feature of the present invention, the resilient bushing IO has a tubular reinforcing sleeve 2, as shown in FIGS. 3 and 4.
0 can be used as a replacement example. The sleeve 20 is formed from nylon 66 and is provided between its ends with a series of holes 21 consisting of two axially spaced circular holes 22. The series of holes 21 consists of four holes arranged at equal intervals in the circumferential direction. The axial end of the sleeve 20 may be U-shaped in cross-section, as shown in FIG. 3, or be chamfered, for example, in the manner described for the sleeve 14 of FIG.

The perforated sleeve facilitates the shaping of the inner and outer parts 16.15 of the rubber intermediate layer 13 by in-situ molding operations. In that case,
the moldable material flows through the walls of the sleeve 20;
A mechanical interlock is achieved between the inner and outer portions 16.15.

In view of the above, the use of elastic bushings with specific types of reinforcing layers is an important departure from the long-established track record in the manufacturing and design technology of elastic bushings, thereby limiting fatigue life. It does not have any significant drawbacks, and allows for ease of manufacture and flexibility in using tubular inner rigid members. In fact, the use of reinforcing sleeves of the type described above according to the present invention may exhibit the most significant fatigue life improvement over that exhibited by conventional bushings of long established designs.

Although the present invention has been particularly described with respect to a resilient bushing in which the reinforcing elastomeric intermediate layer is subjected to a radial precompression force due to the expansion of the inner rigid member and the compressive force of the outer rigid member, in alternative embodiments the elastomeric material is Either it is not subjected to compression forces or it is subjected to radial precompression forces by alternative means. Thus, in the modified example shown in FIGS. 1 to 4, there is no radial precompression force on the rubber intermediate layer 13.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of the elastic bushing according to the present invention, FIG. 2 is an end view of the elastic bushing No. 11150, and FIG.
FIG. 4 is a longitudinal cross-sectional view of another example of the sleeve used in the elastic bushing shown in FIGS. 10... Elastic bushing 11... Inner rigid member 1
2...Outer rigid member 13...Elastic elastomer intermediate layer 14.20...Tubular reinforcing sleeve 15...Radially outer portion 16...Radially inner portion

Claims (1)

[Claims] 1. An inner rigid member (11), an outer rigid member (12) extending spaced apart around the inner rigid member, and between the inner and outer rigid members (11, 12). an elastic bush consisting of an intermediate layer (13) of elastic elastomeric material extending and bonding them to each other, said intermediate layer (13) of elastic elastomeric material being reinforced by a tubular reinforcing layer (14), said reinforcing layer ( 14) of the radially inner or outer tubular portion (16, 1) of said intermediate layer.
5) An elastic bushing capable of deforming in response to the compressive force generated. 2. Elastic bushing according to claim 1, characterized in that the tubular reinforcing layer (14) is made of a substantially semi-rigid material. 3. an inner rigid member (11), an outer rigid member (12) extending spaced apart around the inner rigid member, and an outer rigid member (12) extending between the inner and outer rigid members (11, 12) to An elastic bush consisting of an intermediate layer (13) of elastic elastomeric material bonded to each other, said intermediate layer (13) of elastic elastomeric material being reinforced by a tubular reinforcing layer (14), the material of said reinforcing layer (14) being 600% An elastic bush characterized by having a bending strength in the range of ~2,500 Kgf/cm^2. 4. The material of the tubular reinforcing layer (14) is 900 to 1,000
The elastic bush according to claim 3, characterized in that it has a bending strength of 0 Kgf/cm^2. 5. The elastic bushing according to any one of claims 1 to 4, characterized in that the tubular reinforcing layer (14) is made of a non-metallic material. 6. said tubular reinforcing layer (14) is deformable in response to compressive forces generated in said elastomeric material as a result of each radial expansion or contraction of said inner or outer rigid member (11, 12); radially inner and outer tubular portions (16, 15) which are other portions of said intermediate layer (13);
Claim 1 characterized in that a radial compressive force is applied to the
The elastic bush according to any one of items 5 to 5. 7. characterized in that said inner and outer parts (16, 15) of the intermediate layer of elastic elastomeric material arranged inside and outside of said tubular reinforcing layer (14), respectively, are in a state of residual compressive force; The elastic bushing according to claim 6. 8. The outer rigid member (12) is such that upon being subjected to a compressive force, a residual compressive force is created in both the inner and outer portions (16, 15) of the intermediate layer (13) of elastic elastomeric material. The elastic bush according to claim 7, characterized in that it is. 9. Said tubular reinforcing layer (14) is such that, in normal use of the elastic bushing, it will inherently tend to return to its original shape and configuration when the elastic bushing is released from an externally applied load. The elastic bush according to any one of claims 1 to 8, characterized in that it is of a type of elastic bushing. 10. Elastic bushing according to any one of claims 1 to 9, characterized in that the tubular reinforcing layer (14) is formed from a tubular layer of non-woven material. 11. The radial thickness of the tubular reinforcing layer (14) is in the range of 15% to 25% of the radial separation between opposing surfaces of the inner and outer rigid members (11, 12). An elastic bush according to any one of claims 1 to 10. 12. The radial thickness of the tubular reinforcing layer (14) is in the range of 20% to 25% of the radial separation between opposing surfaces of the inner and outer rigid members (11, 12). The elastic bush according to claim 11. 13. Elastic bushing according to any one of claims 1 to 12, characterized in that the tubular reinforcing layer (14) has at least one hole (22) formed in its wall. 14. Elastic bushing according to claim 13, characterized in that the reinforcing layer (14) is provided with at least one circumferentially arranged series of holes (21; 22). 15. Any one of claims 1 to 14, characterized in that at least one axial end region of the tubular reinforcing layer (14) has a reduced thickness compared to the axial central region. Elastic bushing as described in section.