JP2001074080A - Elastic bush and its assembly - Google Patents

Abstract

(57) [Problem] To provide an elastic bush, which is a synthetic resin outer cylinder and can improve durability by applying pre-compression to a rubber elastic body. SOLUTION: An inner cylinder 12, an outer cylinder 14 surrounding the inner cylinder 12 in a direction parallel to the axis, and a rubber elastic body 16 connecting the inner cylinder and the outer cylinder are provided. In the bush 10, the outer diameter D of the outer cylinder 14 made of synthetic resin is set to be larger than the inner diameter d of the cylindrical member 6,
The rubber elastic body 16 is pre-compressed by press-fitting the outer cylinder 14 into the cylindrical member 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elastic bush as an anti-vibration device used for a suspension or an engine mount of an automobile, and an elastic bush assembling the elastic bush to an arm member of a suspension or various brackets. About the body.

[0002]

2. Description of the Related Art Conventionally, this type of elastic bush is formed by vulcanizing and bonding a metal inner and outer cylinder via a rubber elastic body, and after vulcanization, the outer bushing is formed. A diameter reduction (drawing) process is added to the cylinder, and then the cylinder is press-fitted into the arm members of the suspension and the cylindrical portions of various brackets. When the metal outer cylinder is used in this manner, the rubber elastic body is pre-compressed by the above-described diameter reducing step performed prior to the press-fitting into the cylindrical member, whereby the rubber elastic body is vulcanized and contracted. By reducing tensile strain to improve durability.

In recent years, synthetic resin parts have been used in place of metal parts to reduce the weight of automobiles. For the above-mentioned elastic bush, the outer cylinder will be made of resin in order to reduce the weight. There is an attempt.

[0004] However, when the outer cylinder is made of resin, there is a problem that the durability of the rubber elastic body is greatly reduced because the diameter cannot be reduced as in the case of the metal outer cylinder described above.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an elastic bush and an assembled body thereof, which can improve the durability by applying a pre-compression to a rubber elastic body while being an outer cylinder made of a synthetic resin. And

[0006]

An elastic bush according to the present invention comprises an inner cylinder, an outer cylinder surrounding the inner cylinder in an axially parallel manner, and a rubber elastic body connecting the inner cylinder and the outer cylinder. In the elastic bush assembled by press-fitting the cylindrical member, the outer cylinder is made of synthetic resin, and the outer diameter of the outer cylinder is
The inner diameter of the cylindrical member to be press-fitted is set to be as large as necessary so that the rubber elastic body can be precompressed by the press-fitting.

[0007] An elastic bush assembly according to the present invention comprises an inner cylinder,
An outer cylinder surrounding the inner cylinder in an axis-parallel manner, and an elastic bushing including a rubber elastic body that couples the inner cylinder and the outer cylinder, in an elastic bushing assembly that is press-fitted into a cylindrical member and assembled. The outer cylinder made of a synthetic resin is formed to have a required outer diameter larger than the inner diameter of the cylindrical member, and the rubber cylinder is pre-compressed by press-fitting the outer cylinder into the cylindrical member. It has been granted.

According to the present invention, by providing a required press-fit allowance to the outer diameter of the outer cylinder with respect to the inner diameter of the cylindrical member to be press-fitted, when the elastic bush is press-fitted into the cylindrical member, the elastic bush is pressed into the rubber elastic body. Precompression is applied, and the durability of the rubber elastic body is improved. Here, since the outer cylinder made of synthetic resin is elastically deformed,
Even when the press-in allowance of the outer cylinder is large compared to the case of metal, it can be press-fitted with a relatively small press-fit load.
The rubber elastic body can be pre-compressed by the press-fitting described above. In other words, in the case of a metal outer cylinder, since the press-fitting load is large, press-fitting becomes difficult if a press-in allowance capable of substantially applying precompression to the rubber elastic body is set. Is small, it is possible to secure a press-fit allowance that can apply pre-compression to the rubber elastic body.

As the synthetic resin for forming the outer cylinder, a resin obtained by blending glass fiber with polyamide is preferable. The outer diameter of the outer cylinder is 1.02 times the inner diameter of the cylindrical member.
Preferably, it is set to 1.03 times.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an elastic bush 10 according to an embodiment of the present invention and a cylindrical member 6 to which the elastic bush 10 is assembled, and FIG. 2 is a sectional view showing the assembled state.

The elastic bush 10 is used for an automobile suspension, and is assembled to a cylindrical metal member 6 provided at the tip of an arm member 8 of the suspension.

The elastic bush 10 includes a metal-made cylindrical inner cylinder 12 laid horizontally, a cylindrical outer cylinder 14 surrounding the inner cylinder 12 concentrically and axially, and these inner cylinder 12 and the outer cylinder. And a rubber elastic body 16 which is interposed between the rubber elastic body 14 and the rubber elastic body 16 and is integrally connected to each other by vulcanization bonding means.

A flange 18 is provided at one end of the outer cylinder 14 in the axial direction so as to expand radially outward. The flange 18 restricts a large displacement of the outer cylinder 14 in the axial direction. A stopper rubber 20 extending from the rubber elastic body 16 is provided. A bore 22 is formed at each end of the rubber elastic body 16 in the axial direction by indentation in a curved surface.
Are formed.

In the elastic bush 10, an injection molded product of a synthetic resin is used as the outer cylinder 14. As the synthetic resin forming the outer cylinder 14, a resin obtained by mixing glass fiber with polyamide is preferable. More specifically, a resin obtained by mixing 20 to 60 parts by weight of glass fiber with respect to 100 parts by weight of polyamide is mentioned. Can be As the polyamide, polyamide 66 is preferable. Further, the lower limit of the amount of the glass fiber to 100 parts by weight of the polyamide is more preferably 30 parts by weight, and the upper limit thereof is more preferably 50 parts by weight.

By using a synthetic resin obtained by mixing glass fiber with polyamide, the heat resistance and the strength against the press-fitting load required for the elastic bush 10 can be maintained. Equipment in the case of using a metal outer cylinder can be used as it is, and no capital investment is required.

The outer cylinder 14 has an outer diameter D whose inner diameter D is press-fitted into the cylindrical member 6 so that a predetermined pre-compression is applied to the rubber elastic body 16. d
Is set as large as required. Rubber elastic body 16
Is usually shrunk by about 3% due to vulcanization shrinkage. Specifically, the rubber elastic body 16 is more than 3%, more preferably 4 to 8%.
%, It is preferable to set the dimension of the outer diameter D so as to be precompressed.

The outer diameter D of the outer cylinder 14 is 1.02 to 1.03 times the inner diameter d of the cylindrical member 6 (D = 1.02d
~ 1.03d). If it is less than 1.02 times, it is difficult to secure a predetermined removal load (normally, 5 kN or more). On the other hand, when it exceeds 1.03 times, although the press-fit load does not exceed a predetermined load (normally 30 kN or less),
At the time of press-fitting, abnormal noise such as chattering noise is likely to be generated. In addition,
By setting D = 1.02d to 1.03d in this manner, the rubber elastic body 16 can normally be given a precompression of 3% or more, depending on the outer diameter a of the inner cylinder 12.

As shown in FIG. 1, this elastic bush 10
Is press-fitted into the tubular member 6 from the end opposite to the axial end where the flange portion 18 is provided. In the outer cylinder 14, the axial end on the press-fitted side is chamfered 26 in a tapered shape, thereby facilitating press-fitting into the tubular member 6. The inner end of the cylindrical member 6 in the axial direction is also chamfered 7 to facilitate receiving the outer cylinder 14.

The axial dimension of the cylindrical member 6 is set shorter than the axial dimension of the outer cylinder 14.
The outer cylinder 14 is assembled such that the press-fitting tip of the outer cylinder 14 protrudes from the opposite end of the tubular member 6. As a result, as shown in FIG. 3, in the assembled state, the press-fitting tip of the outer cylinder 14 protrudes from the cylindrical member 6, and the protruding portion 28 returns to the original outer diameter D by elastic deformation. Are difficult to come off from the tubular member 6.

A bush shaft (not shown) supported by a vehicle body-side member is inserted into the inner cylinder 12, thereby connecting the vehicle body and the suspension in a vibration-proof manner.

The elastic bush 1 according to the present embodiment as described above.
0 is press-fitted into the cylindrical member 6 of the arm member 8, whereby the outer cylinder 14 having the outer diameter D is reduced to the diameter d, and the rubber elastic body 16 is pre-compressed. Therefore, the vulcanization shrinkage of the rubber elastic body 16 can be removed, the tensile strain can be reduced, and the durability of the elastic bush 10 can be improved.

The outer cylinder 14 made of synthetic resin has a smaller press-fitting load due to its elastic deformation than a metal-made outer cylinder. Pre-compression can be applied to the rubber elastic body 16 by securing a sufficient press-fitting allowance in the cylinder 14. Therefore, no special capital investment is required for press-fitting.

In addition, since the outer cylinder 14 is made of resin,
In addition to reducing weight, rust prevention treatment (phosphate treatment, painting, etc.) and the step of reducing the diameter before press-fitting, which were necessary in the case of a metal outer cylinder, are not required, so the cost of the entire product is reduced. Up can be prevented.

[0025]

EXAMPLE An elastic bush 10 shown in FIG. 1 was prepared as an example. In this embodiment, a material obtained by blending 100 parts by weight of polyamide 66 with 25 parts by weight of glass fiber was used as the material of the outer cylinder 14.
mm, and the outer diameter D was 55 mm. The outer diameter a of the inner cylinder 12 is 23 mm, and the rubber elastic body 16 has a rubber hardness of 6
0 ° natural rubber was used.

Then, while the inner diameter d of the cylindrical member 6 was changed, the relationship between the press-fitting amount (Dd) of the outer cylinder 14 and the press-fitting and removing loads was examined. However, when measuring the load,
As shown in FIG.
Was press-fitted into the cylindrical member 6.

As a result, the press-fit allowance of the outer cylinder 14 is 1.6 mm.
, The press-fit load is about 20 kN and 30 kN
However, when it exceeded 1.6 mm, abnormal noise occurred during press-fitting. On the other hand, the press fitting allowance of the outer cylinder 14 is 1.
When it is less than 2 mm, the release load after the heat treatment (80 ° C. × 500 hours) was less than 5 kN, and a sufficient release load was not obtained. Thereby, as a press-fit allowance of the outer cylinder 14,
1.2 to 1.6 mm is preferable, and therefore, the relationship between the outer diameter D of the outer cylinder 14 and the inner diameter d of the cylindrical member 6 is D =
1.02 to 1.03d was suitable. In addition, a pre-compression of 4.6% to 6.2% was applied to the rubber elastic body 16 by the press-fitting allowance.

Next, the elastic bush 10 is connected to the cylindrical member 6.
Heat treatment (80 ° C x 500)
Time), thermal shock treatment (-30 ° C x 2 hours and 8
100 cycles of 0 ° C. × 2 hours) and calcium chloride treatment (10 cycles of 80 ° C./humidity 60% × 20 hours, 40% aqueous solution of calcium chloride × 30 seconds and 100 ° C. × 4 hours) After the treatment, an adhesive strength test (a test for obtaining a breaking strength by applying an axial load to the inner cylinder 12 with the outer cylinder 14 fixed) was performed. Further, the calcium chloride-treated product was subjected to a dynamic durability test (a test in which a constant load amplitude (0 ± 4,000 N (2 Hz)) was repeated 200,000 times in the direction perpendicular to the axis of the assembled body).

As a result, all of the treated products were broken at the rubber elastic body 16 in the adhesive strength test, and did not break at the interface between the outer cylinder 14 and the rubber elastic body 16. In the dynamic endurance test, neither the outer cylinder 14 nor the rubber elastic body 16 had any abnormality at the end of the test.

[0030]

According to the present invention, the elastic bush is press-fitted into the cylindrical member by providing a required press-fit allowance to the outer diameter of the outer cylinder with respect to the inner diameter of the cylindrical member to be press-fitted. Precompression can be applied to the body, and the durability of the rubber elastic body can be improved. In addition, since the outer cylinder is made of resin, the weight can be reduced, and the rust prevention process and the diameter reduction step are not required, so that the cost of the entire product can be prevented from increasing.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an elastic bush according to an embodiment of the present invention and a tubular member into which the elastic bush is press-fitted.

FIG. 2 is a cross-sectional view showing an assembled state of the elastic bush to a cylindrical member.

FIG. 3 is a partially enlarged sectional view of FIG. 2;

[Explanation of symbols]

 6 ... cylindrical member 10 ... elastic bush 12 ... inner cylinder 14 ... outer cylinder 16 ... rubber elastic body D ... outer diameter of outer cylinder d ... inner diameter of cylindrical member

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J048 AA01 BA05 BA19 BD01 EA15 3J059 AB12 AE04 AE05 BA42 BA72 BB01 BC04 BC13 BC19 BD07 CB16 GA04 GA09

Claims (7)

[Claims] An inner cylinder, an outer cylinder surrounding the inner cylinder in a direction parallel to the axis thereof, and a rubber elastic body connecting the inner cylinder and the outer cylinder, the elastic body being press-fitted into the cylindrical member to be assembled. In the bush, the outer cylinder is made of a synthetic resin, and the outer diameter of the outer cylinder is set to be larger than the inner diameter of the cylindrical member to be press-fitted so that the rubber elastic body can be pre-compressed by the press-fitting. An elastic bush characterized by being made. 2. The elastic bush according to claim 1, wherein the synthetic resin forming the outer cylinder is a mixture of polyamide and glass fibers. 3. The elastic bush according to claim 2, wherein said polyamide is polyamide 66. 4. The elastic bush according to claim 2, wherein the glass fiber is blended in an amount of 20 to 60 parts by weight with respect to 100 parts by weight of the polyamide. 5. The elastic bush according to claim 2, wherein said glass fiber is blended in an amount of 30 to 50 parts by weight with respect to 100 parts by weight of said polyamide. 6. The elastic bush according to claim 1, wherein the outer diameter of the outer cylinder is set to 1.02 to 1.03 times the inner diameter of the tubular member. 7. An elastic bush comprising an inner cylinder, an outer cylinder surrounding the inner cylinder in a direction parallel to the axis, and a rubber elastic body connecting the inner cylinder and the outer cylinder is press-fitted into a cylindrical member. In the elastic bush assembly, the outer cylinder made of synthetic resin is formed to have a required outer diameter larger than the inner diameter of the cylindrical member, and the outer cylinder is press-fitted into the cylindrical member. An elastic bushing assembly, wherein a pre-compression is applied to the rubber elastic body.