JP2000088026A - Rubber bush and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce deformation of a cylindrical rubber elastic body in a circumferential direction end part of a slit, and improve durability by forming both end surfaces of a circumferential direction in the slit in nearly flat surfaces extending linearly in a diameter direction. SOLUTION: A load of a diameter direction and a load of a twisting direction are inputted between a stem member 12 and an outer cylindrical member 14, in a rubber bush 10. When extension deformation of a diameter direction is generated on a cylindrical rubber elastic body 16 in the vicinity of a circumferential direction end part of a slit 26, the circumferential direction end surface 34 of the slit 26 is formed in a nearly flat surface extending linearly in a diameter direction, and thereby, nearly uniform extension stress is distributed on nearly all surfaces of the circumferential direction end surface 26 of the slit 26. Accordingly, local concentration of the extension stress in the cylindrical rubber elastic body 16 is reduced or avoided. It is thus possible to prevent generation of cracking and the like on the circumferential direction end surface 34 of the slit 26, and it is also possible to improve durability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention has a structure in which a shaft member and an outer cylinder member which are arranged radially apart from each other are connected by a cylindrical rubber elastic body,
For example, the present invention relates to a rubber bush that can be suitably used as a suspension bush or the like for an automobile, and a method for manufacturing the rubber bush.

[0002]

2. Description of the Related Art Conventionally, as one type of vibration isolator interposed between members constituting a vibration transmission system, a shaft member and an outer cylindrical member which is separately inserted and arranged on the outer peripheral side of the shaft member are disclosed. A rubber bush having a structure connected by a cylindrical rubber elastic body interposed therebetween is known. Also, in such a rubber bush, for the purpose of adjusting the spring characteristics, for example, in order to make the spring characteristics different in different radial directions or to adjust the spring characteristics in the twisting direction, etc. In many cases, a slit is formed in the body to penetrate in the axial direction. Further, such a slit is generally formed with a predetermined length in the circumferential direction of the cylindrical rubber elastic body, and both ends in the circumferential direction have a semicircular arc shape in a radial cross section.

However, in a conventional rubber bush provided with such a slit, when a load is applied between the shaft member and the outer cylindrical member, a cylindrical rubber elastic body is formed at the circumferential end of the slit. There was a problem that tensile strain was easily concentrated. In particular, when a load in the twisting direction that inclines the center axis of the outer cylinder member with respect to the center axis of the shaft member is input and the cylindrical rubber elastic body is twisted and deformed, with respect to the circumferential end of the slit, There is a problem that large tensile strain is apt to be caused intensively, which makes it difficult to secure sufficient durability.

[0004]

Here, the present invention has been made in view of the above-mentioned circumstances, and a problem to be solved is that the deformation distortion of the cylindrical rubber elastic body at the circumferential end of the slit is reduced. It is an object of the present invention to provide a rubber bush having a new structure that is reduced and exhibit excellent durability, and a method for manufacturing a new rubber bush.

[0005]

In order to solve such a problem, a feature of the present invention relating to a rubber bush is that a shaft member and an outer cylindrical member which is externally arranged and spaced apart from the outer peripheral side of the shaft member are provided. A rubber bush formed by connecting a cylindrical rubber elastic body interposed therebetween and having a slit penetrating in the axial direction with respect to the cylindrical rubber elastic body; The surfaces are substantially flat surfaces extending linearly in the radial direction.

In such a rubber bush having the structure according to the present invention, a radial load or a prying load is input between the shaft member and the outer cylindrical member, so that the vicinity of the circumferential end of the slit is provided. Even when the cylindrical rubber elastic body is subjected to radial tensile deformation in the above, since the circumferential end surface of the slit is a substantially flat surface extending linearly in the radial direction, the circumferential direction of the slit is The tensile stress is distributed substantially uniformly over substantially the entire end face, and local concentration of the tensile stress in the tubular rubber elastic body is reduced or avoided. As a result, cracks and the like at the circumferential end surfaces of the slits are prevented, and the effect of improving durability is exhibited.

According to the present invention, in order to solve the above-mentioned problems, a shaft member and an outer cylindrical member which is separately inserted and arranged on the outer peripheral side of the shaft member are interposed therebetween. It is connected by a cylindrical rubber elastic body, and a slit penetrating in the axial direction is formed in the cylindrical rubber elastic body, and a radial compressive force is exerted on the cylindrical rubber elastic body at the time of mounting. In the rubber bush, both ends in the circumferential direction of the slit in the cylindrical rubber elastic body become substantially flat surfaces extending linearly in the radial direction, respectively, by elastic deformation due to the radial compressive force exerted at the time of mounting. As described above, a rubber bush whose both end surfaces are curved concave surfaces concaved in an arc shape in a cross section perpendicular to the axis in a state before the radial compression force is not applied thereto before mounting is also characterized.

[0008] In the rubber bush having the structure according to the present invention, even when the outer cylinder member is reduced in diameter during mounting, for example, by press-fitting the outer cylinder member into the mounting hole, etc. Under the condition, since both end surfaces in the circumferential direction of the slit are substantially flat surfaces, as described above, the effect of improving the durability by reducing or avoiding local concentration of tensile stress in the cylindrical rubber elastic body, It is stable.

The slits employed in the present invention have their forming position, circumferential size, etc. appropriately set according to the spring characteristics and the like required of the rubber bush. Specifically, for example, by forming a pair of slits at positions radially opposed to each other across the shaft member, a large spring ratio can be obtained in the radial direction in which the slits are opposed to each other and in the radial direction perpendicular thereto. It can be set.

Further, in the rubber bush having each structure according to the present invention, for example, each of both circumferential end faces of the slit is formed in a radial direction of 60% or more of a radial thickness of the cylindrical rubber elastic body. Preferably, the width is 7 mm, more preferably 7 mm in the radial thickness of the cylindrical rubber elastic body.
The radial width is set to 0% or more, more preferably 80% or more of the radial thickness of the cylindrical rubber elastic body. As a result, the rubber free length in the vicinity of the circumferential end of the slit where the tensile stress tends to concentrate in the cylindrical rubber elastic body, that is, the surface area of the circumferential end face in the slit is advantageously secured, and the generated stress is further reduced. Thus, the durability can be further improved. In the case where the cylindrical rubber elastic body is compressed and deformed in the radial direction due to, for example, contraction of the outer cylindrical member in a state where the cylindrical rubber elastic body is mounted on a vehicle or the like, the above-described state may be obtained under the compression deformed state of the cylindrical rubber elastic body. It is desirable to set the radial dimension of the slit such that the radial dimension as described above is realized. Further, in the present invention, when adjusting the torsion spring characteristics or tuning the spring ratio in the direction perpendicular to the axis and in the torsion direction, for example, with respect to the axial center portion of the shaft member, the outer peripheral surface is formed by a spherical convex surface or a cylindrical surface. It is also possible to form a large-diameter convex portion that protrudes upward, in which case the radial thickness of the cylindrical rubber elastic body changes in the axial direction, but the cylindrical rubber elastic body By setting the radial dimension of the slit such that the radial dimension as described above is realized in the thinnest part, the effect of improving durability and the like can be effectively exhibited.

Further, in the rubber bush having each structure according to the present invention, for example, the axial thickness of a portion of the cylindrical rubber elastic body where the slit is not formed may be changed in the circumferential direction near the slit. In the configuration, the inclination is gradually reduced toward the slit in the axial direction at both end surfaces in the axial direction of the cylindrical rubber elastic body. Adopted. If such a configuration is adopted,
When the shaft member and the outer cylindrical member are torsionally displaced by the input load in the torsion direction, the maximum distortion caused by the cylindrical rubber elastic body near the circumferential end of the slit is further reduced, so that the cylindrical member is formed. The generation stress of the rubber elastic body is suppressed, and the generation of cracks and the like is more effectively prevented, and excellent durability can be exhibited even when there is a large input in the twisting direction.

As described above, in the case where the two axial end surfaces of the cylindrical rubber elastic body are inclined near the both ends in the circumferential direction of the slit, for example, a surface extending in a direction perpendicular to the axis of the inclined surface is used. It is desirable to set the inclination angle with respect to the reference plane at 20 to 60 degrees, more preferably at 30 to 50 degrees. Even if such an inclination angle is too small or large, the sufficient securing of the volume of the cylindrical rubber elastic body and the effect of reducing the maximum distortion of the cylindrical rubber elastic body at the time of the input load in the twisting direction are sufficient. Is difficult to secure. Further, such an inclined surface has a circumferential length of 15 to 40 degrees in the circumferential direction of the cylindrical rubber elastic body,
More preferably, it is desirable to form over a circumferential length range of 20 to 30 degrees, whereby reduction of the tensile strain of the cylindrical rubber elastic body at the time of twisting input is more effectively achieved.

In the rubber bush having each structure according to the present invention, for example, at least one side of the shaft member and the outer cylinder member which are radially opposed to each other across the slit, the rubber bush is provided in the slit. A stopper rubber protruding radially toward the projection is provided, and both circumferential end surfaces of the stopper rubber are respectively connected to the circumferential end surface of the slit by an arc-shaped connection concave surface in the circumferential direction. Is preferably adopted. By providing such a stopper rubber, the surface area of the circumferential end face of the slit (the free rubber length near the circumferential end of the slit)
And a stopper mechanism for buffering the relative displacement of the shaft member and the outer cylinder member in the radial direction can be advantageously realized. As a result of suppressing the distortion, more excellent durability can be realized.

Further, in the rubber bush having each structure according to the present invention, for example, at least one side of the shaft member and the outer cylinder member radially opposed to each other with the slit interposed therebetween, the rubber bush is provided in the slit. A stopper rubber protruding radially toward the projection is provided, and the protruding tip end surface of the stopper rubber is inclined in the axial direction so that the radial inner dimension of the slit is reduced from the axial central portion to the outer side in both axial directions. It is preferable to adopt a configuration in which the size gradually increases as the position goes. If such a stopper rubber is adopted, a nonlinear stopper characteristic can be obtained when a load in the radial direction is input, and even when a load in the twist direction and a load in the radial direction are input together, A stable stopper function can be obtained.

In the rubber bush having each structure according to the present invention, for example, the axial length of the outer cylindrical member is made smaller than that of the axial member, and both ends of the cylindrical rubber elastic body in the axial direction. A generally tapered surface that gradually projects outward in the axial direction from the outer cylinder member side toward the shaft member side is preferably adopted. By adopting such a configuration, it is possible to equalize the rubber volume in the circumferential direction at the inner circumferential portion and the outer circumferential portion, and to secure the spring rigidity in the radial direction and the spring in the twisting direction. It is possible to set the rigidity small,
A large degree of freedom in tuning the spring characteristics can be ensured, and the deformation of the cylindrical rubber elastic body due to the displacement of the shaft member and the outer cylindrical member in the twisting direction can be suppressed as a whole.

On the other hand, in order to solve the above-mentioned problem, a feature of the present invention relating to a method for manufacturing a rubber bush is that the cylindrical rubber elastic body is added between the shaft member and the outer cylindrical member. When manufacturing various rubber bushes having the structure according to the present invention as described above by vulcanizing, the cylindrical rubber is vulcanized between the vulcanization of the cylindrical rubber elastic body and the mounting of the rubber bush. In consideration of the radial compressive force exerted on the elastic body, by applying the radial compressive force, both circumferential end faces of the slit of the cylindrical rubber elastic body linearly extend in the radial direction, respectively. There is provided a method for manufacturing a rubber bush in which both end surfaces in the circumferential direction of the slit are vulcanized and formed to have a curved concave shape which is concave in an arc shape in a radial cross section so as to have a substantially flat surface.

According to the method of the present invention, when mounted on a vehicle or the like, the rubber bush whose both end surfaces in the circumferential direction of the slit are substantially flat surfaces each extending linearly in the radial direction is advantageously used. In the rubber bush obtained according to the method of the present invention, the concentration of tensile stress at the circumferential end of the slit in the cylindrical rubber elastic body is reduced or avoided. The excellent durability can be exhibited stably.

[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.
This will be described in detail with reference to the drawings.

First, FIGS. 1 and 2 show product drawings of an automobile suspension bush 10 as one embodiment of the present invention. The bush 10 includes an inner cylinder fitting 12 as a shaft member and an outer cylinder fitting 14 as an outer cylinder member.
It is elastically connected by a rubber elastic body 16 as a cylindrical rubber elastic body, and has a substantially cylindrical shape as a whole. The bush 10 has an inner cylinder fitting 12 attached to the vehicle body frame side of the automobile, and an outer cylinder fitting 1.
When the suspension arm 4 is attached to the suspension arm, the suspension arm is attached to a portion where the suspension arm is attached to the vehicle body frame, and the suspension arm is elastically connected to the vehicle body frame.

More specifically, the inner cylindrical fitting 12 is formed of a rigid material such as a metal material such as iron and steel, and has a thick straight straight tubular shape. In addition, the inner cylinder fitting 1
The corner inner peripheral surface 18 at the opening end on both axial sides of
Each is a tapered surface that expands outward in the axial direction.

On the outer peripheral surface of the inner cylindrical member 12, an outer cylindrical member 14 is arranged radially outwardly. The outer tube fitting 14 is made of a rigid material such as a metal material such as steel, like the inner tube fitting 12, and has a straight cylindrical shape. And these inner cylinder fittings 12
And the outer tube fitting 14 are disposed substantially coaxially with each other and in a state where their axial center points coincide with each other. The outer tube 14 is thinner than the inner tube 12 and has a smaller axial length. For example, the outer tube 14 has an axial length of about ３ to ／ of the inner tube 12. In this embodiment, the length in the axial direction is about 1/2. Further, a corner outer peripheral surface 2 at an opening end portion on both axial sides of the outer cylinder fitting 14.
Numerals 0 are tapered surfaces whose diameter is reduced outward in the axial direction.

The outer tube fitting 14 is externally arranged with respect to the inner tube member 12, and is located on the same central axis: L. The outer tube fitting 14 is disposed at the axial center of the inner tube fitting 12 so as to cover the outer peripheral surface of the axial center portion of the inner tube fitting 12. As a result, between the radially opposed surfaces of the inner and outer cylindrical fittings 12, 14,
An annular region extending in a substantially constant size continuously in the circumferential direction is formed. In particular, in the present embodiment, the outer tube fitting 14
Is set to be about twice as large as the outer diameter of the inner cylindrical fitting 12, so that such an annular region is formed with a sufficient width in the radial direction (distance between opposed surfaces in the radial direction). It has become.

A rubber elastic body 16 is provided in an annular region formed between the radially opposed surfaces of the inner and outer cylindrical fittings 12 and 14.
The inner and outer cylindrical fittings 12 and 14 are elastically connected by a rubber elastic body 16. The rubber elastic body 16 has a substantially thick cylindrical shape as a whole, and its inner peripheral surface is adhered to the outer peripheral surface of the inner cylinder fitting 12, while the outer peripheral surface is formed on the inner periphery of the outer cylinder fitting 14. Adhered to the surface. Such a rubber elastic body 16 is, for example, as shown in FIGS.
If necessary, the inner cylinder 12 and the outer cylinder 14 that have been subjected to an adhesive treatment or the like are set, and a rubber material is filled between the inner and outer cylinders 12 and 14 and vulcanized to form the inner and outer cylinders 12 and 14. The rubber elastic body 16 can be advantageously formed as an integral vulcanized molded product 22 to which the rubber elastic body 16 is vulcanized and adhered.

Further, the integrally vulcanized molded product 22 obtained as described above is subjected to a diameter reducing process such as an eight-way drawing on the outer tube fitting 14 as necessary. Thereby, FIGS.
The bush 10 as shown in FIG. By such diameter reduction processing, internal stress generated in the rubber elastic body 16 due to shrinkage during vulcanization or the like is reduced or eliminated,
Further, rubber properties including spring properties and durability can be adjusted by applying pre-compression.

Here, the rubber elastic body 16 formed as an integral vulcanized molded product 22 as described above has its axial dimension gradually reduced from the inner peripheral side to the outer peripheral side, and the inner peripheral surface is formed on the inner peripheral surface. The outer peripheral surface is adhered to substantially the entire inner peripheral surface of the outer cylindrical metal fitting 14 while being adhered to substantially the entire outer peripheral surface of the cylindrical metal fitting 12. That is, both axial end faces 24, 24 of the rubber elastic body 16 are substantially tapered cylindrical surfaces protruding outward in the axial direction from the outer cylindrical fitting 14 toward the inner cylindrical fitting 12. These axial end faces 24, 24 are shown in FIG.
As shown in the figure, a curved surface in which an inner peripheral side portion having an arc-shaped cross section of a radius of curvature: Ra and an outer peripheral side portion having an arc-shaped cross section of a smaller radius of curvature: Rb are connected continuously. The point at which the rubber elastic body 16 has the smallest axial dimension is located near the outer tube fitting 14.

The rubber elastic body 16 has a pair of slits 26, 26 extending therethrough in the axial direction. Each of the slits 26 has a shape extending substantially in the radial direction at a substantially central portion of the rubber elastic body 16 in a circumferential direction with a length of about 1/4 circumference. 3
(Medium, vertical direction). In particular, in the present embodiment, the slit 26 has a radial width dimension B substantially over the entire radial thickness of the rubber elastic body 16 at both ends in the circumferential direction. An inner peripheral stopper rubber 28 that is bonded to the inner cylindrical fitting 12 and protrudes radially outward from the inner cylindrical fitting 12 is bonded to the outer cylindrical fitting 14 at a central portion in the circumferential direction of the slit 26. The outer tube fitting 1
An outer peripheral side stopper rubber 30 protruding radially inward from the fourth side is formed. The protruding distal end surfaces of the inner peripheral side stopper rubber 28 and the outer peripheral side stopper rubber 30 are opposed to each other with a predetermined distance in the radial direction across the slit 26.

The stopper rubbers 28, 30
Is protruded into the slit 26, so that the slit 2
3, as a whole, has a substantially H-shaped cross section in a cross section perpendicular to the axis, as shown in FIG. In other words, the width in the radial direction of each slit 26 is changed in the circumferential direction, is small at the center in the circumferential direction, and is large at both ends in the circumferential direction. Also,
Both ends of the slit 26 in the circumferential direction are the inner and outer cylindrical fittings 12 and 14.
The rubber elastic body 16 is substantially divided in the circumferential direction by a pair of slits 26, 26 by being formed with a radial width dimension substantially over the entire distance between the radially opposed surfaces of the pair. The inner and outer cylindrical fittings 12 and 14 are connected to each other only at a portion where the slits 26 and 26 are not formed, that is, at a pair of elastic connecting portions 38 and 38 that are opposed to each other in a radial direction orthogonal to the facing direction of the slits 26 and 26. It exists in a state where it does. The stopper rubber 28,
Reference numeral 30 denotes a slight thickness: T (for example, on the surfaces of the inner and outer cylindrical metal fittings 12 and 14 at both ends in the circumferential direction of the slit 26).
The rubber elastic body 16 is connected to an elastic connecting portion 38 located adjacently in the circumferential direction through the rubber turning portions 32, 32 formed with the minimum thickness allowed for technical reasons such as a mold structure of the rubber elastic body 16). It is integrated.

The inner peripheral side stopper rubber 28 is formed as an inclined surface whose protruding tip surface becomes lower as it goes from the center in the axial direction to both sides in the axial direction, and as a whole, as shown in FIG. The cross section has a substantially mountain-shaped cross-sectional shape in which the protruding height is greatest at the central portion in the axial direction. In other words, the inner dimension in the radial direction of the slit 26 is gradually increased from the central portion in the axial direction to the outer sides on both sides in the axial direction. Further, the inner peripheral side stopper rubber 28 has the highest protruding height at the center in the circumferential direction. On the other hand, the outer peripheral side stopper rubber 3
No. 0 has a substantially constant protruding height over the entirety, and small crimped or wavy irregularities are provided on substantially the entire protruding tip surface.

Further, in the integrally vulcanized molded product 22,
Both circumferential end surfaces 34 (ie, inner circumferential surfaces at both circumferential end portions) of the slit 26 are radial cross sections as shown in FIG. 3 and are arc-shaped with a substantially constant radius of curvature: rb. It has a concave concave surface. Here, the radius of curvature: rb is set in consideration of the elastic deformation in the process from the vulcanization of the rubber elastic body 16 to the mounting state on the vehicle. That is, as described above, the rubber elastic body 16 is formed by the diameter reduction processing applied to the outer cylinder fitting 14 after the vulcanization molding.
When a radial compressive force is applied to the rubber elastic body 16, the rubber elastic body 16 expands into the slit 26 due to the elastic deformation of the rubber elastic body 16. As described above, in consideration of the amount of compressive deformation of the rubber elastic body 16, the circumferential both end surfaces 34, 34 are substantially flat surfaces extending linearly in the radial direction. The curvature radius: rb at 34, 34 is designed.

Particularly, in this embodiment, in the radial cross section of the integrally vulcanized molded product 22 shown in FIG.
The circumferential end face 34 of the slit 26 formed by b at both ends thereof has a radius of curvature sufficiently smaller than rb: r
Through the arcuate connection concave surfaces 36, 36 having the a, the inner peripheral side stopper rubber 28 and the outer peripheral side stopper rubber 30 are smoothly connected to the circumferential end surfaces with a continuous surface. In the present embodiment, the inner peripheral side stopper rubber 2 is formed by reducing the diameter of the outer cylinder 14 after vulcanization molding as described above.
Although the distance between the radially opposed surfaces of the stopper rubber 8 and the outer peripheral side stopper rubber 30 is reduced, as shown in FIGS. The height of the protrusions of the stopper rubbers 28 and 30 is set so that the stopper rubbers 28 and 30 are opposed to each other with a slight contact or a very small gap in the central portion.

Further, each of the elastic connecting portions 38, 38 formed by the rubber elastic body 16 is substantially one in the circumferential direction.
/ 4 circumference and each elastic connecting portion 38
Are formed as thickness change portions whose axial thickness gradually decreases as approaching the slit 26 over a predetermined length in the circumferential direction. That is, both end portions in the circumferential direction of the elastic connection portion 38 are inclined surfaces 40, 40 that are gradually inclined inward in the axial direction toward the slit 26 in the circumferential direction. In the present embodiment, the inclined surface 40 is formed in each of the elastic connection portions 38 over a length of approximately 1/4 to 1/3 of the circumferential end. Further, as shown in FIG. 5, the change in wall thickness per unit central angle around the central axis: L due to the inclined surface 40 is larger on the outer peripheral side than on the inner peripheral side. Has been enlarged.

In particular, in the present embodiment, as shown in FIG. 6, a plane (axial face) extending perpendicular to the central axis: L with respect to the inclined surface 40: a circumferential inclination angle with respect to A. : Θ is set to be 30 to 50 degrees. Further, each inclined surface 40 is provided with an arc-shaped curved surface which is slightly convex outward.

In short, each of the elastic connecting portions 38 has a shape in which the corners on both sides in the axial direction are cut off by the inclined surfaces 40, 40 on both sides in the circumferential direction constituting the walls on both sides in the circumferential direction of the slit 26. It has been. As a result, the circumferential end surfaces 34 of the slit 26 are each reduced in axial length.

The bush 10 structured as described above is
Although not explicitly shown in the drawings, for example,
A rod fixed to the vehicle body frame side is inserted into and fixed to the inner hole 42 of the vehicle, while the outer tube fitting 14 is fitted to an arm eye formed on a suspension arm such as an L-shaped arm or an A-shaped arm of the vehicle. By being press-fitted and fixed, the suspension axis is interposed in a portion where the suspension arm is attached to the vehicle body frame in a state in which the center axis L extends substantially vertically. In this mounting state, an input load in the direction perpendicular to the axis is applied to the bush 10 in accordance with running conditions such as unevenness of the road surface, acceleration / braking, cornering, and the like, and the bush 10 responds to swinging of the suspension arm and the like. As a result, an input load is applied in the twisting direction in which the central axis of the inner cylindrical member 12 and the central axis of the outer cylindrical member 14 are mutually inclined.

Here, in this bush 10, the spring ratio in the radial direction is set to be large by the pair of slits 26, 26, so that the slits 26, 26 are soft in the radial direction where they oppose each other, and are radial in the orthogonal direction. Since a hard spring characteristic is developed in, for example, it is easy to provide a soft spring characteristic in the vehicle front-rear direction and a hard spring characteristic in the vehicle left-right direction to achieve a high degree of both riding comfort and steering stability. You can.

In addition, in the rubber bush 10, both ends 3 in the circumferential direction of the slit 26 are formed by diameter reduction processing.
4 and 34 are substantially flat surfaces that extend linearly in the radial direction, so that even when a radial tensile force acts on the rubber elastic body 16 located on both sides of the slit 26, the tensile stress is reduced. 26 is generated substantially uniformly over substantially the entire circumferential end surface 34 of the peripheral surface 26, and the local concentration of tensile stress is effectively avoided. Therefore, on the circumferential end face 34 of the slit 26, the occurrence of cracks or the like due to stress concentration is reduced or prevented, and thus excellent durability is exhibited. In particular, in the present embodiment, since the circumferential end face 34 of the slit 26 is formed with a radial width that covers almost the entire radial thickness of the rubber elastic body 16 and a large area is set, the tensile end Stresses are more advantageously dispersed, and improved durability can be achieved more advantageously.

In the bush 10, the relative displacement of the inner and outer cylindrical fittings 12, 14 in the radial direction is buffered by the stopper rubbers 28, 30 projecting into the respective slits 26. Therefore, even when a large load is applied, the rubber elastic body 16 is prevented from being excessively deformed, and the generated tensile stress is limited, whereby the crack in the circumferential end face 34 of the slit 26 is also reduced. Occurrence is suppressed, and the durability can be further improved.

Further, in such a bush 10,
The axial thickness of the rubber elastic body 16 (elastic connecting portion 38) is
Near the circumferential end of the slit 26, the inclined surface 40,
Since it is set small by 40, for example,
Even when a load in the twisting direction is input between the inner and outer tube fittings 12 and 14, the radial tensile strain generated near the circumferential end of the slit 26 is advantageously reduced. The accompanying tensile stress of the rubber elastic body 16 can be effectively suppressed. Therefore, even if the twisting direction (the direction of inclination of the central axes of the inner and outer cylindrical fittings 12 and 14 due to the twisting load) is
Even in the case of being located near the circumferential end face 34 of the slit 26, the tensile strain of the rubber elastic body 16 due to the twisting load is reduced, and the generation of cracks on the circumferential end face 34 of the slit 26 is prevented, resulting in good durability. The nature is exhibited.

In this way, the concentration of the stress which is likely to be generated at the circumferential end of the slit 26 can be advantageously reduced or prevented with respect to the loads in both the radial direction and the twisting direction.
In the rubber bush 10 having the above structure,
In the automotive suspension bush used for the L-shaped arm or the like as described above in which the radial load and the pry load are often input simultaneously, the stress generated at the circumferential end of the slit 26 is advantageously reduced. As a result, it is possible to obtain excellent durability while sufficiently securing the tuning effect of the radial spring ratio by the slits 26, 26.

Incidentally, the maximum principal strain (radial strain) in the rubber elastic body 16 when the load in the twisting direction and the radial direction is applied to the bush 10 having the above structure is analyzed by the finite element method. The results obtained are shown in FIG. In this analysis, the inner cylinder fitting 12 and the outer cylinder fitting 14 are connected to the slits 26 and 2 in consideration of the load input in the actual vehicle.
6, the relative inclination angle of the inner and outer cylindrical fittings 12 and 14 is 12.4 with the axial center point as a twisting center.
Degrees, and then, while maintaining such a twist angle (12.4 degrees), the inner and outer cylindrical fittings 12, 14 are radially opposed to the slits 26, 26 to a maximum of 3 mm. The condition of relative displacement was adopted.

As a comparative example, as shown in FIGS. 8 and 9, both circumferential end surfaces 34 of each slit 26,
34 employs rubber bushes 44 and 46 having substantially semicircular curved surfaces in a product state after the outer tube fitting 14 has been subjected to diameter reduction processing.
Also, the maximum principal strain generated in the rubber elastic body 16 was determined under the same conditions. The rubber bush 44 of Comparative Example 1 shown in FIG. 8 has a smaller radial width of the slit 26 than the rubber bush 46 of Comparative Example 2 shown in FIG. In the rubber bushes 44 and 46 as comparative examples, various conditions other than the cross-sectional shape of the slit 26, such as the shape and material of each member and portion, were set to be the same as those of the rubber bush 10 of the present embodiment.

Further, the bush 1 of the present embodiment as described above
0 and the rubber bushings 44 and 46 of Comparative Examples 1 and 2 were actually manufactured, and the inner and outer cylinders were kept at 12.4 degrees with respect to the twisting direction of the inner and outer cylinder fittings 12 and 14 for each. Fittings 12 and 14 to slits 26 and 2
A durability test was carried out in which the relative displacement was repeated 5 × 10 ⁵ times with an amplitude of ± 3 mm in the radial direction in the facing direction of No. 6. The results are shown in Table 1 below together with the above-described analysis result of the maximum principal strain (strain when only a 12.4 degree twisting displacement is input).

[0043]

[Table 1]

As is clear from the results of the analysis and test shown in FIG.
In any of the rubber bushings 44,
It is apparent that the maximum principal strain at the time of load input in the prying direction and the radial direction is reduced, and excellent durability can be exhibited as compared with 46. Each of the cracks in Comparative Examples 1 and 2 is a substantially central portion in the circumferential direction of the arcuate circumferential end face 34 of the slit 26, and is substantially the same as the portion where the maximum principal strain is generated by the finite element method. Was consistent. In particular, in the rubber bush 44 of Comparative Example 1, when the inner and outer cylindrical fittings 12 and 14 are relatively displaced by 1.0 mm or more in the radial direction under a state in which a twist displacement of 12.4 degrees is exerted, the element is destroyed. It was evident from the analysis results that occurred.

While the embodiments and examples of the present invention have been described in detail, these are merely examples,
The present invention is not limited in any way by the above specific description.

For example, after the rubber elastic body 16 is vulcanized and the outer cylinder 14 is reduced in diameter as required, when the bush 10 is mounted, the outer cylinder 14 is pressed into a mounting hole such as an arm eye of a suspension arm. By doing so, if the outer tube fitting 14 is reduced in diameter, thereby causing radial elastic deformation of the rubber elastic body 16, the elastic deformation of the rubber elastic body 16 during such mounting is also taken into consideration. In a state in which the bush 10 is mounted, the circumferential end surface 34 of the slit 26 becomes a substantially flat surface that extends linearly in the radial direction.
It is desirable to design the shape of the rubber elastic body 16 at the time of vulcanization molding.

The stopper rubbers 28 and 30 in the slit 26 are not always necessary, and even if a radial stopper mechanism is required, either one of the inner peripheral stopper rubber 28 and the outer peripheral stopper rubber 30 is required. It is also possible to constitute the stopper mechanism only by the above.

Furthermore, in the above embodiment, the inner peripheral side stopper rubber 28 has the most protruding shape at the central portion in the circumferential direction and the axial direction, so that a nonlinear cushioning stopper function is provided and , Outer peripheral stopper rubber 3
The projection end surface of the protrusion 0 is made uneven so as to reduce the occurrence of hammering noise.
The specific shape or structure of 8, 30 is not particularly limited.

The length of the slit 26 in the circumferential direction and the like are appropriately determined according to the anti-vibration performance and the like required of the bush 10, and are not limited at all. Further, the slit 26 is not limited to the one formed in a pair at the position facing in the radial direction. For example, according to the characteristics required for the bush 10, only one slit 26 may be formed on the circumference, It is also possible to form three or more independently in the circumferential direction.

Further, the inclined surfaces 40, 40 in the elastic connecting portion 38 are not necessarily formed, and the rubber elastic body 16 may be formed with a substantially constant thickness in the circumferential direction.

Further, the direction in which the bush 10 is disposed is not limited, and the required spring characteristics, vibration damping performance, and the like are advantageously achieved with respect to the input direction of the main radial load and the twisting load. As described above, it can be set appropriately in consideration of the relative position of the slit 26 and the like.

The outer peripheral surface of the inner cylindrical member 12 and the outer cylindrical member 1
The inner peripheral surface of 4 has an elliptical shape or the like in a cross section perpendicular to the axis,
It is also possible to adjust the spring characteristics of the bush by bonding a restricting member that restricts deformation to the rubber elastic body 16 or the like.

In addition, the present invention can be applied to various rubber bushes without being limited to the suspension bush for automobiles as illustrated, and can be applied to a rubber bush in which a load in a radial direction or a twisting direction is not input. The present invention can be advantageously applied.

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 in the scope of the present invention, without departing from the spirit of the present invention.

[0055]

As is apparent from the above description, in the rubber bush having the structure according to the present invention, since the circumferential end surface of the slit is a substantially flat surface extending linearly in the radial direction, the shaft is formed. When a radial or twisting load is applied between the member and the outer cylindrical member, local concentration of tensile strain generated near the circumferential end of the slit in the cylindrical rubber elastic body is reduced or prevented. Therefore, since the dispersion is advantageously performed, the maximum distortion generated in the cylindrical rubber elastic body is reduced, and the effect of improving the durability is exhibited.

Further, according to the method of the present invention, the shape of the cylindrical rubber elastic body is designed in consideration of the process leading up to the mounting of the rubber bush. A substantially flat surface shape extending linearly in the circumferential direction at the circumferential end face is stably provided. Therefore, in such a rubber bush, the effect of improving the durability based on the reduction of the tensile strain of the cylindrical rubber elastic body is obtained. Can be enjoyed stably and advantageously.

[Brief description of the drawings]

FIG. 1 is an axial end view showing a bush as one embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is an axial end view showing an integrally vulcanized molded product obtained in a manufacturing process of the bush shown in FIG. 1;

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a sectional view taken along line VV in FIG. 3;

FIG. 6 is a sectional view taken along line VI-VI in FIG. 3;

7 is a graph showing a result of analyzing a maximum principal strain of the bush shown in FIG. 1 when a load is input by a finite element method, together with a result of a comparative example.

FIG. 8 shows Comparative Example 1 for the analysis shown in FIG.
FIG. 4 is an end view in the axial direction showing a rubber bush adopted as the first embodiment.

FIG. 9 shows Comparative Example 2 for the analysis whose results are shown in FIG.
FIG. 4 is an end view in the axial direction showing a rubber bush adopted as the first embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Bush 12 Inner cylinder metal fitting 14 Outer cylinder metal fitting 16 Rubber elastic body 22 Integral vulcanization molding 26 Slit 34 Circumferential end face 40 Inclined surface

Claims (9)

[Claims] A shaft member and an outer cylindrical member which is separately inserted and arranged on the outer peripheral side of the shaft member are connected by a cylindrical rubber elastic body interposed therebetween, and the cylindrical member is connected to the cylindrical member. A rubber bush in which a slit penetrating in the axial direction is formed with respect to the rubber elastic body, wherein both end surfaces in the circumferential direction of the slit are substantially flat surfaces extending linearly in the radial direction, respectively. bush. 2. A shaft member and an outer cylindrical member which is separately inserted and arranged on the outer peripheral side of the shaft member are connected by a cylindrical rubber elastic body interposed between the shaft member and the cylindrical member. A slit is formed in the rubber elastic body so as to penetrate in the axial direction, and a radial compressive force is applied to the cylindrical rubber elastic body at the time of mounting. Due to the elastic deformation of the cylindrical rubber elastic body, both end faces in the circumferential direction of the slit are compressed in the radial direction so that the end faces in the circumferential direction of the slit become substantially flat surfaces extending linearly in the radial direction, respectively. A rubber bush having a curved concave surface that is concave in an arc shape in a cross section perpendicular to the axis in a state before mounting without applying force. 3. The rubber bush according to claim 1, wherein radial widths of both circumferential end surfaces of the slit are each 60% or more of a radial thickness of the cylindrical rubber elastic body. 4. An axial thickness of a portion of the cylindrical rubber elastic body in which the slit is not formed is gradually reduced near the slit in the circumferential direction as approaching the slit. The rubber bush according to any one of claims 1 to 3, wherein inclined surfaces gradually inward in the axial direction are formed with respect to both end surfaces in the axial direction of the body in the circumferential direction as approaching the slit. 5. The rubber bush according to claim 4, wherein the inclined surface is inclined by 20 to 60 degrees with respect to a surface extending in a direction perpendicular to the axis. 6. A stopper rubber protruding radially toward the inside of the slit is provided on at least one side of the shaft member and the outer cylinder member radially opposed to each other with the slit therebetween. The rubber bush according to any one of claims 1 to 5, wherein both end surfaces in the circumferential direction of the stopper rubber are continuously connected to the circumferential end surfaces of the slits in the circumferential direction by arcuate connection concave surfaces. 7. A stopper rubber protruding radially toward the inside of the slit is provided on at least one side of the shaft member and the outer cylinder member radially opposed to each other across the slit, and 7. The protruding front end surface of the stopper rubber is inclined in the axial direction so that the radial inner dimension of the slit gradually increases from the central portion in the axial direction to the outside on both sides in the axial direction. The rubber bush according to any one of the above. 8. An axial length of the outer cylinder member is made smaller than that of the shaft member, and both axial end surfaces of the cylindrical rubber elastic body are entirely moved from the outer cylinder member side to the shaft member side. The rubber bush according to any one of claims 1 to 7, wherein the rubber bush has a substantially tapered surface that gradually projects outward in the axial direction as it goes. 9. The method for manufacturing the rubber bush according to claim 1, wherein the cylindrical rubber elastic body is vulcanized and molded between the shaft member and the outer cylindrical member. Considering the radial compressive force exerted on the cylindrical rubber elastic body after the vulcanization molding of the rubber elastic body until the mounting of the rubber bush, the radial compressive force is applied, The circumferential end surfaces of the slits of the cylindrical rubber elastic body are formed such that both circumferential end surfaces of the slits are substantially flat surfaces extending linearly in the radial direction.
A method for producing a rubber bush, characterized in that vulcanization molding is performed with a curved concave surface shape concave in an arc shape in a radial cross section.