JPH10169711A - Bush - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-layered bush which has a smooth bottom surface and a good appearance and which is excellent in its adhesive property and in durability. SOLUTION: A bush is formed by layering an inner cylinder 12, which is made of highly slidable rubber, on an inner periphery of an outer cylinder 11 made up of rubber elastic body, using injection molding. In this bush, the inner peripheral edge on the end part, which becomes a bottom side, of the outer cylinder 11 is projected inward in the radial direction, thereby forming a receiving part 14. By receiving the inner cylinder (12) member, which is injected from a gate facing the receiving part 14, by the receiving part, the deformation of the outer cylinder during the forming work can be restricted and moreover an occurrence of a difference in level of the bottom surface can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bush used for a stabilizer bush or the like, and more particularly to a two-layer bush in which an inner cylinder and an outer cylinder having different characteristics are laminated.

[0002]

2. Description of the Related Art A stabilizer bush is made of a thick cylindrical rubber elastic body, in which a stabilizer bar of a vehicle is inserted and held, and the outer periphery is held in a bracket fixed to a vehicle body. It is. As shown in FIG. 4, there is a stabilizer bush 1 having a two-layer structure in which an inner cylinder 12 is laminated on the inner periphery of an outer cylinder 11.
By forming the inner cylinder 12 from a highly slidable rubber, it is possible to prevent generation of abnormal noise due to a sudden relative displacement between the inner peripheral surface of the bush and the stabilizer bar when the vehicle starts moving.

[0003]

When the stabilizer bush 1 having the two-layer structure is manufactured by the injection molding method, usually, first, the outer cylinder 11 is preformed, and the molded product is attached to the lower core while the molded product is attached to the lower die. In general, a method of injection-molding the inner cylinder 12 by changing the inner diameter is used. However, in this case, there is a problem that the outer cylinder 11 is deformed downward when the inner cylinder 12 is filled, and is directly vulcanized and bonded to the inner cylinder 12.

This will be described with reference to FIG. FIG. 5 (a)
Is a preformed outer cylinder 11, which is arranged in a mold (not shown) with the axial direction being the vertical direction. In the figure, point b is the outer cylinder 11
An arbitrary point on the inner peripheral surface close to the bottom surface, point c, is an intersection between the inner peripheral surface and the bottom surface. As shown in FIG. 5B, when the unvulcanized rubber constituting the inner cylinder 12 is injected from the gate provided above the drawing, the injection pressure causes the point b in FIG. It moves to a point and is vulcanized and adhered while in contact with the bottom surface. When this is taken out of the mold, as shown in FIG. 5 (c), the external pressure disappears and the outer cylinder 11 which has been pressure-deformed returns to its original state. It moves to the upper b "point. At this time, the inner cylinder 1 which is vulcanized and bonded to the outer cylinder 11
Since 2 is pulled by the outer cylinder 11, the bottom surface of the inner cylinder 12 rises upward. For this reason, there is a problem that a step is generated (diameter of the outer cylinder 11: about 40 to 0.3 mm at about 40 mm), and the bottom surface of the product becomes uneven.

[0005] Further, since the outer cylinder 11 is vulcanized and bonded in a deformed state, internal stress may remain in the product and durability may be reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a two-layered bush having a uniform bottom surface and a good appearance, and having excellent adhesive durability.

[0007]

The bush of the present invention comprises an outer cylinder made of a rubber elastic body and an inner cylinder made of a rubber elastic body having different characteristics from the outer cylinder laminated on the inner periphery of the outer cylinder. The inner peripheral edge of the end portion in the axial direction protrudes inward in the radial direction to form a receiving portion that receives and joins the end portion of the inner cylinder during injection molding (claim 1).

When the bush having the above structure is injection-molded, the outer cylinder is preformed so that the receiving portion is on the side opposite to the gate of the die, and the preformed product is placed in the die while the preform is placed in the die. Change the core and inject the inner cylinder. At this time, since the outer cylinder has the receiving portion, deformation of the outer cylinder when the inner cylinder is injected is suppressed. Therefore, occurrence of a step is prevented, and a uniform and good appearance is obtained. Further, no internal stress is generated due to the deformation, and the bonding durability is greatly improved.

The inner cylinder is made of, for example, a highly slidable rubber provided with a high slidability by blending a higher fatty acid amide into a base rubber. When the inner cylinder is made of highly slidable rubber, sliding resistance of a stabilizer bar or the like held in the inner cylinder can be reduced, and generation of abnormal noise can be prevented.

[0010] The width of the receiving portion is preferably not less than 1/2 of the thickness of the inner cylinder and not more than the thickness of the inner cylinder. Within this range, a high effect by providing the receiving portion can be obtained, and the sliding resistance of the stabilizer bar or the like held in the inner cylinder can be kept low.

The rubber as a base material of the highly slidable rubber is a rubber material similar to the rubber constituting the outer cylinder,
It is preferable in improving the adhesive strength (claim 4).

[0012]

1 (a) and 1 (b) show an embodiment in which the present invention is applied to a stabilizer bush. In the drawings, a stabilizer bush 1 has a thick cylindrical rubber elasticity. An inner cylinder 12 is laminated on the inner periphery of an outer cylinder 11 made of a body. The inner cylinder 12 is cylindrical and made of highly slidable rubber, and the stabilizer bar of the vehicle is inserted and held in the cylinder.

The outer cylinder 11 is formed in a substantially U-shaped cross section having a top surface as a plane. The outer cylinder 11 has flanges 13 formed by radially extending the outer peripheral edges of both ends thereof. The outer peripheral surface between the flanges 13 is fixed to a vehicle frame by a substantially U-shaped mounting bracket (see FIG. (Abbreviated).

A receiving portion 14 is formed at one end of the outer cylinder 11 in the axial direction so as to protrude radially inward along the entire circumference of the inner peripheral edge. The receiving portion 14 is provided so as to be opposite to the gate in the molding die, usually on the bottom surface side, and suppresses deformation of the outer cylinder 11 when injecting and filling the inner cylinder 12 material. The receiving portion 14 has a triangular cross-sectional shape that is inclined inward and downward as shown in FIG.

In order to obtain the above-described effects, it is preferable that the width w of the receiving portion 14 in the radial direction be equal to or more than の of the thickness of the inner cylinder 12. The inclination angle of the receiving portion 14 is determined by the width w
However, for example, the angle may be about 45 °. The width w of the receiving portion 14 is set to be equal to or less than the thickness of the inner cylinder 12. In addition, from the viewpoint of the slidability with the stabilizer bar, it is desirable that the receiving portion 14 is not exposed to the inner peripheral surface of the bush, and more preferably, the width w of the receiving portion 14 is smaller than the thickness of the inner cylinder 12. Is good.

The outer cylinder 11 may have a rectangular cross section having a constant thickness as shown in FIG. In this case, the thickness t of the receiving portion 14 is, for example, 40 mm in diameter of the outer cylinder 11.
It is good to be about 1-2 mm.

When the stabilizer bush having the above structure is manufactured by injection molding, first, the constituent material of the outer cylinder 11 is injected into a mold and semi-vulcanized. At this time, the receiving portion 1
4 is formed so as to be on the bottom side (the side facing the gate). Thereafter, the constituent material of the inner cylinder 12 may be injected by changing the center, and the inner and outer cylinders may be vulcanized and bonded.

As the rubber material constituting the outer cylinder 11, various rubber materials generally used as stabilizer bushing materials, specifically, natural rubber (NR), butadiene rubber (BR), isoprene rubber (IR), Styrene butadiene rubber (SBR), chloroprene rubber (C
R), nitrile rubber (NBR), ethylene propylene diene copolymer rubber (EPDM), butyl rubber (IIR),
And blended rubbers thereof can be used. Preferably, natural rubber (NR), butadiene rubber (BR), and a blend rubber (NR / BR) of natural rubber (NR) and butadiene rubber (BR) are suitably used.

The highly slidable rubber constituting the inner cylinder 12 is as follows:
High slidability is imparted by blending a higher fatty acid amide into rubber as a base material. Here, the rubber used as the base material is not particularly limited. For example, natural rubber (N
R), butadiene rubber (BR), isoprene rubber (I
R), styrene butadiene rubber (SBR), chloroprene rubber (CR), nitrile rubber (NBR), ethylene propylene diene copolymer rubber (EPDM), butyl rubber (IIR), and a blend rubber thereof. Preferably, natural rubber (NR), butadiene rubber (BR), and a blend rubber (NR / BR) of natural rubber (NR) and butadiene rubber (BR) are suitably used.

The higher fatty acid amide compounded in the base rubber functions as a lubricant by blooming from the base rubber during use, thereby improving the slidability. Specific examples of higher fatty acid amides include saturated / unsaturated fatty acid amides having 12 to 22 carbon atoms, such as oleic acid amide, palmitic acid amide, stearic acid amide, and erucic acid amide. The amount of the higher fatty acid amide to be added to the base rubber is usually preferably in the range of 5 to 20% by weight, and if the amount is less than 5% by weight, it is difficult to sufficiently maintain the effect of reducing the sliding resistance. If the amount exceeds 20% by weight, the physical properties of the rubber may be adversely affected.

The highly slidable rubber is obtained by blending the base rubber and higher fatty acid amide at a predetermined blending ratio. At this time,
Generally known additives, for example, vulcanizing agents, vulcanization accelerators, vulcanization aids, processing aids and the like can be used.

Here, the combination of the inner cylinder 12 and the outer cylinder 11 is not particularly limited, but the rubber serving as the base of the highly slidable rubber constituting the inner cylinder 12 is replaced with the rubber constituting the outer cylinder 11. If the rubber material is the same as or similar to the above, the bonding property between the two is improved.

When the stabilizer bush is used, the high-sliding rubber gives the sliding property due to the blooming of the higher fatty acid amide from the inside of the stabilizer bush. The bloomed higher fatty acid amide may migrate to the outer cylinder 11 side. In order to avoid this shift, the difference in the SP value (solubility parameter) of the fatty acid amide in the highly slidable rubber constituting the outer cylinder 11 and the inner cylinder 12 should be 1.5 or more, preferably 2 or more. It is desirable to select a material.

According to the above configuration, since the receiving portion 14 is provided at the bottom of the outer cylinder 11, when the inner cylinder 12 material is injected, the outer cylinder 1
Even if pressure is applied to the point 1, the point a (FIG. 2), which is an arbitrary point on the upper surface of the receiving portion 14, does not contact the bottom surface. Therefore, a step can be prevented from being formed on the bottom surfaces of the inner and outer cylinders, and unevenness of the bottom surfaces is eliminated, and a product having a good appearance can be obtained. Further, since no internal stress is generated in the outer cylinder at the time of molding, the bonding durability between the inner and outer cylinders is greatly improved.

In the above embodiment, an example in which the present invention is applied to a stabilizer bush has been described. However, the present invention is not limited to this, and any bush having a two-layer structure can be applied.

[Brief description of the drawings]

FIGS. 1A and 1B show a first embodiment of the present invention, in which FIG. 1A is an axial sectional view of a stabilizer bush, and FIG. 1B is a sectional view taken along line AA of FIG.

FIG. 2 is a sectional view of the outer cylinder according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of an outer cylinder showing a second embodiment of the present invention.

FIG. 4 is an overall schematic perspective view of a conventional stabilizer bush.

FIGS. 5A to 5C are views for explaining a conventional method of forming a stabilizer bush.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stabilizer bush (bush) 11 Outer cylinder 12 Inner cylinder 13 Flange 14 Receiving part

Claims (4)

[Claims] A bush comprising an inner cylinder made of a rubber elastic body having a characteristic different from that of the outer cylinder laminated by injection molding on an inner periphery of an outer cylinder made of a rubber elastic body. A bush characterized in that an inner peripheral edge of the bush protrudes radially inward to receive and be joined to an end of the inner cylinder during injection molding. 2. The bush according to claim 1, wherein said inner cylinder is made of a highly slidable rubber provided with a high slidability by blending a higher fatty acid amide into a rubber as a base material. 3. The width of the receiving portion is 1 / th of the thickness of the inner cylinder.
The bush according to claim 1 or 2, wherein the thickness is not less than 2 and not more than the thickness of the inner cylinder. 4. The rubber as a base material of the highly slidable rubber,
4. The bush according to claim 2, wherein the bush is a rubber material similar to the rubber constituting the outer cylinder.