JP2004144150A - Vibration control bush - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a so-called bulge type vibration control bush at a low cost with excellent buckling strength in the axial direction of a inner cylinder 10 and excellent environmental aspect, while preventing displacement of a synthetic resin annular coating body 20 arranged as a bulge part on the outer peripheral surface of the central part in the axial direction of the inner cylinder 10. <P>SOLUTION: For a metal pipe constituting the inner cylinder 10, a knurling 22 is arranged on the outer peripheral surface of the central part in the axial direction, and preferably serrations 24 are arranged on the end surface 16 in the axial direction. The coating body 20 is fixed to the outer peripheral surface of the metal pipe including the knurling 22 by molding of synthetic resin. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an anti-vibration bush that is incorporated in, for example, a part of a suspension mechanism of an automobile and used to reduce vibration.
[0002]
[Prior art]
Generally, in an automobile, a vibration isolating bush is incorporated in a part of a suspension mechanism or an engine support mechanism in order to control vibration transmitted from the wheel side to the vehicle body side or vibration transmitted from the engine side to the vehicle body side. Have been. As an example of such an anti-vibration bush, in order to increase the spring constant in the direction perpendicular to the axis and decrease the spring constant in the twisting direction, a bulging portion bulging in the direction perpendicular to the axis is provided at the axial center of the inner cylinder. There is a so-called bulge-type anti-vibration bush.
[0003]
FIG. 6 shows an example of a conventional bulge bush. The anti-vibration bush is provided between a metal inner cylinder 102 having a bulging portion 101 bulging in a direction perpendicular to the axis at an axial center portion, an outer cylinder 103 surrounding the bulging portion 101, and the two cylinders 102, 103. Rubber-like elastic body 104 provided. The rubber-like elastic body 104 at the central portion in the axial direction is made thinner than the both ends by the bulging portion 101, so that the spring constant in the direction A perpendicular to the axis (the direction perpendicular to the axial direction) is increased and the torsion is caused. The spring constant in the direction B (the direction in which the central axes of the inner and outer cylinder fittings 102 and 103 are relatively inclined) is set to be small, thereby achieving both improvement in riding comfort and improvement in steering stability. I have.
[0004]
In the conventional anti-vibration bush shown in FIG. 6, the bulging portion 101 of the inner cylinder 102 is provided integrally by forging. Therefore, the processing cost is high and the product weight is increased. Further, in the case of forging, it is difficult in molding to make the outer diameter of the bulging portion 101 larger than the outer diameter of the inner cylinder 102 by a certain amount or more. Design flexibility is low.
[0005]
Therefore, it has been proposed to form the above-mentioned bulging portion with an annular covering made of synthetic resin. In Patent Document 1, as shown in FIG. 7, an annular covering 112 made of synthetic resin is fixedly provided as a bulging portion on the outer peripheral surface of a central portion of an inner cylinder 110, and the annular covering 112 is included therein. An anti-vibration bush in which a rubber-like elastic body 116 is interposed between a cylinder 110 and an outer cylinder 114 has been proposed. When the annular cover 112 is provided on the outer peripheral surface of the inner cylinder 110 as described above, when the rubber-like elastic body 116 is vulcanized, the heat and pressure may cause the annular cover 112 to move. For this reason, in Patent Document 1, two or four concave portions 118 are provided on the outer peripheral surface of the inner cylinder 110 in the circumferential direction to prevent the annular cover 112 from coming off, and these are filled with a part of the synthetic resin, or In addition, it is disclosed that the annular cover 112 is fixed by, for example, projecting the retaining member in reverse.
[0006]
In addition, as shown in FIG. 8, in order to prevent the annular cover 112 from being displaced in the axial direction and the rotational direction, as shown in FIG. A plurality of seating surfaces 120 having a length close to the covering width and having a flat bottom are formed in the circumferential direction, and synthetic resin is caused to flow into the seating surfaces 120 when the annular covering 112 is formed. It is disclosed that the annular cover 112 is seated and fixed on the cover.
[0007]
[Patent Document 1] Japanese Utility Model Publication No. 5-64544
[Patent Document 2] Japanese Unexamined Utility Model Publication No. 6-76729
[Problems to be solved by the invention]
In the vibration isolating bush shown in FIGS. 7 and 8 described above, a plurality of somewhat large concave portions are provided in the inner cylinder in order to prevent positional displacement of the annular covering member, so that the buckling strength of the inner cylinder against a load in the axial direction is reduced. Resulting in. Further, the conventional displacement prevention structure as shown in FIGS. 7 and 8 is lower in cost than the forging shown in FIG. 6, but still requires a certain number of man-hours for molding, so further cost reduction is required. Furthermore, since the shavings are generated due to the provision of the concave portion, improvement is also required from an environmental point of view.
[0010]
The present invention has been made in view of the above problems, and in a so-called bulge-type vibration-isolating bush, a buckling strength of an inner cylinder in an axial direction is prevented while preventing a position shift of a synthetic resin annular covering provided as a bulging portion on the inner cylinder surface. It is an object of the present invention to provide an anti-vibration bush that is excellent in cost, low in cost, and excellent in environment.
[0011]
[Means for Solving the Problems]
An anti-vibration bush according to the present invention includes an inner cylinder having a bulging portion bulging in a direction perpendicular to the axis at a central portion in the axial direction, an outer cylinder arranged at a distance outside the inner cylinder, and An anti-vibration bush comprising a rubber-like elastic body interposed between a cylinder and an outer cylinder, wherein the inner cylinder is provided on an outer peripheral surface of a metal pipe and an axially central portion of the metal pipe. The metal pipe is provided with knurls on an outer peripheral surface at a central portion in the axial direction, and the coating is formed of a synthetic resin on an outer peripheral surface including the knurls of the metal pipe. The rubber-like elastic body is vulcanized and formed on the outer periphery of the inner cylinder so as to surround the covering.
[0012]
In the vibration-proof bush of the present invention, the knurls are provided on the outer peripheral surface of the inner cylinder, and the annular coating as a bulging portion is provided on the surface by molding the synthetic resin. The annular coating body is firmly fixed to the outer peripheral surface of the inner cylinder by entering into the fine mesh-like groove. Therefore, displacement of the annular coating body in the axial direction and the rotation direction during vulcanization molding of the rubber-like elastic body is prevented. In addition, the knurls can be provided by a simple method of pressing while rotating a cylindrical knurl having a notch on the outer peripheral surface, so that the cost is low, and there is no cutting waste, so that the knurls are excellent in environment.
[0013]
In the anti-vibration bush of the present invention, it is preferable that the metal pipe constituting the inner cylinder has serrations provided on at least one axial end face, and is further hardened by quenching. Such an anti-vibration bush, when assembled to a vehicle, a state in which both end surfaces of the inner cylinder are sandwiched by a mounting member such as a bracket, or a state in which only one end surface of the inner cylinder is in contact with the mounting member. A shaft member, such as a bolt, is inserted through and is fastened and fixed to the mounting member. Therefore, by providing serrations on the end surface of the inner cylinder that abuts on the mounting member, the serrations bite into the mounting member when assembling to the vehicle, making the inner cylinder undesired not only during assembly but also during subsequent use. Rotation is prevented. In addition, the quenching improves the serration strength and also improves the axial buckling strength of the inner cylinder. Since the serrations and the knurls can be processed simultaneously, it is advantageous to combine the serrations for preventing rotation of the inner cylinder with the knurls for preventing displacement of the annular covering.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, a suspension bush, which is an anti-vibration bush according to an embodiment of the present invention, is arranged with an inner cylinder 10, surrounding the inner cylinder 10, and spaced outward in a direction perpendicular to the axis thereof. An outer cylinder 12 and a ring-shaped rubber-like elastic body 14 interposed between the inner cylinder 10 and the outer cylinder 12. The inner cylinder 10 is fixed to the mounting member 1 by inserting the shaft member 3 having the bolt 2 and tightening the nut 4 with the both end surfaces 16, 16 being sandwiched by the mounting member 1 such as a bracket. Further, the outer cylinder 12 is fixed by being press-fitted into the cylindrical portion 5 which is the other mounting member, whereby the vibration-proof bush connects the mounting members 1 and 5 in a vibration-proof manner.
[0015]
The inner cylinder 10 includes a metal pipe 18 made of steel and an annular covering 20 made of synthetic resin provided on an outer peripheral surface at a central portion in the axial direction. The outer cylinder 12 is, for example, a steel cylinder, and its axial length is set to be equal to or greater than that of the annular covering body 20 provided on the inner cylinder 10. Further, the rubber-like elastic body 14 is interposed between the inner cylinder 10 and the outer cylinder 12 so as to wrap the annular coating body 20 by vulcanization molding. It is thin near the center and thick near both ends in the axial direction. In this manner, the elastic constant in the direction perpendicular to the axis is set to be large by making the rubber-like elastic body 14 thin near the center in the axial direction, and the spring constant in the twisting direction is made large by making it thick near both ends in the axial direction. It is set small. In addition, the rubber-like elastic body 14 has a through hole 26 that penetrates in the axial direction in a predetermined range in the circumferential direction in order to set the spring constant in three directions of the axial direction, the direction perpendicular to the axis, and the twisting direction to desired values. Is provided.
[0016]
The metal pipe 18 constituting the inner cylinder 10 is provided with knurls 22 on an outer peripheral surface at a central portion in the axial direction, and serrations 24 on both end surfaces 16, 16 in the axial direction, and further hardened by quenching. is there.
[0017]
Here, the notch configuration of the knurls 22 is not particularly limited as long as the positional deviation of the annular coating body 20 can be prevented, but the pitch between the peaks is about 0.5 to 3.0 mm, more preferably about 1.5 mm. It is preferable to form a grid-like mesh pattern having a depth of about 0.3 to 1.5 mm, more preferably about 0.6 mm. The width W1 of the knurls 22 is preferably as wide as possible in order to enhance the fixing effect of the annular covering 20, but if it is too wide and protrudes from the annular covering 20, the vulcanization of the rubber-like elastic body 14 is performed. Since rubber enters the knurls 22 during molding, the width is preferably about 0.4 to 0.8 times the width W2 of the annular covering 20 (see FIG. 5).
[0018]
As shown in FIG. 2, the serrations 24 are formed by providing a large number of radially extending grooves on the end face of the metal pipe 18 at a predetermined pitch in the circumferential direction. As shown in FIG. Have a mountain cross section, the angle θ between adjacent slopes is set to about 60 ° to 120 °, more preferably about 90 °, and the pitch P between the peaks is about 0.5 to 3.0 mm, more preferably It is preferably set to about 1.5 mm, and furthermore, the depth D is set to about 0.3 to 1.5 mm, more preferably about 0.6 mm.
[0019]
The annular coating body 20 is fixedly provided on the outer peripheral surface of the metal pipe 18 including the knurls 22 by molding of a synthetic resin so as to completely cover the knurls 22 of the metal pipe 18. Bulges into a substantially spherical shape in the direction perpendicular to the axis. The annular coating 20 can be formed of various synthetic resins, but is preferably formed of polyamide such as nylon 6 or nylon 66, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polyphenylene oxide, or the like.
[0020]
The method of manufacturing the vibration-proof bush includes (1) a step of manufacturing the inner cylinder 10 and (2) a step of vulcanizing and molding the rubber-like elastic body 14 on the outer peripheral surface of the manufactured inner cylinder 10. Then, the step (1) further includes (1-1) a step of providing knurls 22 on the outer peripheral surface of the metal pipe 18 at the central portion in the axial direction, and (1-2) serrations 24 on the axial end face of the metal pipe 18. Providing, (1-3) quenching the metal pipe 18 provided with the knurls 24 and the serrations 24, and (1-4) forming the annular coating 20 on the outer peripheral surface of the quenched metal pipe 18 using a synthetic resin mold. Fixing by molding.
[0021]
In the step (1-1), known knurling can be applied as a method of providing the knurls 22 on the metal pipe 18, for example, while rotating a cylindrical knurl hardened and hardened by notching the outer peripheral surface. , May be pressed against the outer peripheral surface of the metal pipe 18. After the knurling, kerosene washing is preferably performed.
[0022]
In the step (1-2), a known serration process can be applied to the method of providing the serrations 24 on the metal pipe 18. For example, serration grooves may be formed on the end surface of the metal pipe 18 using a shaving cutter. .
[0023]
Step (1-1) and step (1-2) can be performed simultaneously. That is, in a state where the metal pipe 18 is fixed to the fixing jig, knurling is performed on the outer peripheral surface at the central portion in the axial direction, and serration is performed on the end surface in the axial direction, so that the knurls 22 and the serrations 24 are provided at the same time. be able to. Therefore, in order to reduce the processing time, it is preferable to perform both at the same time.
[0024]
The quenching in the step (1-3) is performed after knurling and serration. This is because it is difficult to perform knurling or serration on a metal pipe hardened by quenching. As a quenching method, carburizing and quenching in which quenching treatment is performed after carburizing is preferably used. Carburizing and quenching is a method of quenching by heating in a carburizing agent to increase the amount of carbon in the surface layer of steel, and known methods can be used for the type of carburizing agent and processing conditions. The total hardened layer depth of the carburized and quenched layer is preferably about 0.3 mm, and the surface hardness after the treatment is preferably 550 to 850 HV1 (test load of 9.8 N) in terms of Vickers hardness value according to JIS Z 2244. .
[0025]
In the step (1-4), the annular coating 20 is provided on the metal pipe 18 thus hardened (see FIG. 3) (see FIG. 5). As the molding method, injection molding, in which the quenched metal pipe 18 is set in a mold (not shown), and molten synthetic resin is injected into the cavity and molded, is preferably used.
[0026]
In the step (2), a rubber-like elastic body 14 is vulcanized and formed on the outer periphery of the inner cylinder 10 obtained as described above. At this time, the inner cylinder 10 and the outer cylinder 12 are arranged in a mold (not shown) so as to surround the inner cylinder 10, and raw rubber is injected between the two cylinders 10, 12 to vulcanize the rubber-like elastic body 14. May be. In this case, the inner cylinder 10 and the outer cylinder 12 are integrally vulcanized and bonded by the rubber-like elastic body 14. Alternatively, only the inner cylinder 10 is placed in a mold (not shown), raw rubber is injected, the rubber-like elastic body 14 is vulcanized on the outer peripheral surface of the inner cylinder 10, and then the formed rubber-like elastic body The outer cylinder 12 may be extrapolated to the outer peripheral surface of the outer cylinder 14. In this case, the outer cylinder 12 is not vulcanized and bonded to the rubber-like elastic body 14, but is integrated with the inner cylinder 10 and the rubber-like elastic body 14 inside by being extrapolated.
[0027]
According to the present embodiment described above, the annular cover 20 made of synthetic resin is used as the bulging portion provided at the center of the inner cylinder 10, so that the weight of the vibration-proof bush is reduced. Further, since the thickness of the annular covering body 20 made of synthetic resin can be freely set, the thickness of the rubber-like elastic body 14 at the central portion in the axial direction can be reduced, and the spring in the direction perpendicular to the axis can be formed. High degree of design freedom between the constant and the spring constant in the twisting direction.
[0028]
Further, the knurls 22 provided on the outer peripheral surface of the metal pipe 18 constituting the inner cylinder 10 prevent the annular coating body 20 from being displaced in the axial direction and the rotation direction during the vulcanization molding of the rubber-like elastic body 14. be able to. In addition, such a misalignment preventing structure is achieved by the knurls 22. Since the knurling can proceed simultaneously with the serration as described above, there is no significant increase in man-hours and low cost. Positional deviation can be prevented, and there is no cutting debris, so it is also environmentally friendly. In addition, the serrations 24 provided on the axial end surface of the metal pipe 18 prevent the inner cylinder 10 from being undesirably rotated at the time of assembling the vehicle and after the assembling, and improve the strength of the serrations 24 by quenching. The buckling strength of the inner cylinder 10 in the axial direction is also improved.
[0029]
【The invention's effect】
ADVANTAGE OF THE INVENTION The vibration-proof bush of this invention is excellent in the buckling strength in the axial direction of an inner cylinder, preventing environmental displacement at low cost, preventing the position shift of the synthetic resin annular coating provided as a bulge part on the inner cylinder surface. Also excellent in nature.
[Brief description of the drawings]
FIG. 1 is a sectional view of an anti-vibration bush according to an embodiment of the present invention.
FIG. 2 is a side view of the vibration isolating bush.
FIG. 3 is a front view of a metal pipe constituting an inner cylinder of the vibration-isolating bush.
FIG. 4 is an enlarged sectional view of serrations on an end face of the metal pipe.
FIG. 5 is a front view showing an inner cylinder to which a synthetic resin annular coating is fixed, by cutting the coating;
FIG. 6 is a cross-sectional view of a first conventional anti-vibration bush.
FIG. 7 is a cross-sectional view of a second conventional vibration-isolating bush.
FIG. 8 is a cross-sectional view of a third conventional example of an anti-vibration bush.
[Explanation of symbols]
10 inner cylinder 12 outer cylinder 14 rubber-like elastic body 18 metal pipe 20 annular coating body 22 knurls 24 serrations

Claims (3)

An inner cylinder having a bulging portion bulging in a direction perpendicular to the axis at a central portion in the axial direction, an outer cylinder arranged at an interval outside the inner cylinder, and between the inner cylinder and the outer cylinder. An anti-vibration bush comprising an interposed rubber-like elastic body,
The inner cylinder includes a metal pipe, and an annular covering body that constitutes the bulging portion provided on an outer peripheral surface at a central portion in the axial direction of the metal pipe,
The metal pipe is provided with knurls on an outer peripheral surface at a central portion in the axial direction,
The coating is provided by being fixed to the outer peripheral surface of the metal pipe including the knurl by molding of a synthetic resin,
The rubber-like elastic body is vulcanized and formed on the outer periphery of the inner cylinder so as to surround the covering. The anti-vibration bush according to claim 1, wherein the metal pipe is provided with serrations on at least one axial end face, and further hardened by quenching. The vibration proof bush according to claim 2, wherein the quenching is carburizing quenching.

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