JPH10318312A - Rubber bush - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a press-in member from comining off by promoting the stabilization of spring load characteristics and the betterment of vibratory fatigue characteristics. SOLUTION: Out of two circumferential recesses 11 and 12 formed inside each of both end rubber flanges 8 and 9 of a rubber bush 1, a tile angle βof a recess side wall 15 at the press-in rear end side is set up to be smaller than another tilt angle α of a recess side wall 14 at the press-in front end side. After press-in operation, any flexure is made so as not to be produced in the side wall 15 at the press-in rear end side and thereby durability is well improved, and stable spring load characteristics are made so as to be securable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration rubber bush used for a connecting portion of an automobile suspension or the like.

[0002]

2. Description of the Related Art A rubber bush is widely used as a vibration isolating mechanism in a connecting portion of a suspension or the like in order to improve the driving stability and riding comfort performance of an automobile. This rubber bush is generally formed by vulcanizing and bonding a rubber-like elastic body around a shaft member. A connecting cylinder of a suspension arm can be directly fitted around the rubber-like elastic body, or an outer cylinder can be used. It is used in a form to be fitted to the connecting cylinder via the.

[0003] In order to obtain a higher compression ratio than such a rubber bush of the outer cylinder-bonded type, a rubber-like elastic body is press-fitted into a press-fitting member such as an outer cylinder or a connecting cylinder of a suspension arm from the axial direction. In addition, there is a press-fit type rubber bush in which the spring rigidity in the direction perpendicular to the axis is increased and the rubber-like elastic body is pre-compressed to improve its durability. Furthermore, in this press-fit type rubber bush, the axial length of the rubber-like elastic body is made longer than that of the press-fit member, rubber flanges are integrally formed at both ends in the axial direction, and the press-fit member is sandwiched from both sides in the axial direction. There is a device that regulates the movement in the axial direction.

In this rubber bush with a rubber flange, a pressing force in a direction perpendicular to the axis is applied at the axial center portion by the fitting pressure to the press-fitting member, and rubber of the rubber-like elastic body is moved from the central portion of the shaft. Flow deformation to the outside in the axial direction is converted to compressive deformation to the inside in the axial direction of the rubber flanges at both ends, resulting in residual distortion in this part, so that a circumferential recess is formed inside the rubber flange in the axial direction. However, there has appeared a structure in which the concave portion absorbs the flow deformation at the time of fitting to the press-fitting member.

[0005] Further, in the rubber bush with the rubber flange having the circumferential recessed portion, the spring constant in the direction perpendicular to the axis, and
From the relationship of setting the spring constant in the axial direction and the spring constant in the twisting direction inclined with respect to the axial direction to the desired spring constant,
There are a type in which the concave portion is not canceled after press-fitting due to the expansion and deformation of the rubber in the axial direction due to the press-fitting into the press-in member, and a type in which the circumferential concave portion remains.

FIG. 5 is a view showing a process of press-fitting a press-fitting member in a rubber bush with a rubber flange in which a circumferential concave portion remains after press-fitting. In the actual press-fitting process, FIG.
In the drawing, the left side of the rubber bush is referred to as a press-fit front end side, and the right side is referred to as a press-fit rear end side in order to press-fit the rubber bush located on the right side into the press-fitting member located on the left side in the axial direction. the same).

As shown in FIG. 5A, in this rubber bush 101, a rubber elastic body 103 is provided around a shaft member 102.
Are vulcanized and bonded to each other, and rubber flanges 104 and 105 are formed at both axial ends of the rubber-like elastic body 103. A fitting portion 10 of the press-fitting member 106 is formed between the rubber flanges 104 and 105.
7 is set. Before the press-fitting, the fitting portion 107 has a circumferential concave portion 108, 1
09 and a contact portion 110 formed at a central portion in the axial direction with a diameter larger than the inner diameter of the press-fitting member 106. The length of the fitting portion 107 in the axial direction is smaller than the axial width of the press-fitting member 106 in consideration of the expansion in the axial direction due to the flow of rubber at the time of press-fitting. At the time of press-fitting
Thereby, the press-fitting member 106 is pressed in the axial direction.

The circumferential recesses 108 and 109 are set to a depth that exists even after press-fitting into the press-fitting member.
Side walls 111 and 112 are conical inclined surfaces inclined with respect to the central axis A of the shaft member 102, and the inclination angles α and
β is set to approximately 40 °. In FIG. 5, the inclination angles α and β should be expressed as angles formed with the axis A. However, for convenience of illustration, the axial outer peripheral edge of the contact portion 110 parallel to the axis A and the side walls 111 and 112 are not shown. It was expressed as an angle (complex angle).

The rubber bush 101 is inserted into the press-fitting member 106.
5 (a), the rubber flange 104 on the front end side of the press-fitting member is separated from the one end side 106a in the axial direction of the press-fitting member 106 by the opening edge 106b at the other end of the press-fitting member 106.
Until it is engaged. Incidentally, the interval between the rubber flanges 104 and 105 before press-fitting is determined by the press-fitting member 106.
In order for the rubber flange 104 on the front end side of the press-fitting to engage with the opening edge 106b at the other end of the press-fitting member 106, the rubber bushing to the position shown in FIG. It is necessary to insert and move 101 excessively. After that, by releasing the axial insertion force, the restoring force of the rubber-like elastic body 103 is used to stabilize the position of FIG. Become.

[0010]

By the way, as shown in FIG. 5, in a rubber bush with a rubber flange, the side walls 111 of the recesses 108, 109 of the fitting portion 107 before press-fitting.
Since the inclination angles α and β of 112 are set to be equal (about 40 degrees), when the press-fitting member 106 is press-fitted, FIG.
As shown, the side wall 11 of the recess 109 on the rear end side of the press-fit after press-fitting.
2 greatly expands and deforms, and a bent portion is formed. Therefore, the set spring constant of the press-fitting member contact portion 110 in the direction perpendicular to the axis is not constant, and the stability of the spring characteristics is deteriorated.

Further, since the recess side wall 112 on the rear end side of the press-fitting is greatly expanded and deformed, the vibration fatigue characteristics of the portion are also deteriorated. Furthermore, since there is a residual stress in the expanded and bent portion of the side wall 112 of the concave portion, the compressive stress with other contact portions is not uniform, and the press-fit member 106 may be easily detached.

An object of the present invention is to solve the above-mentioned problems and eliminate the expansion and bending portion of the side wall of the concave portion on the rear end side of the press-fitting, stabilize spring characteristics and improve vibration fatigue characteristics, and prevent the press-fitting member from coming off. It is an object.

[0013]

Means for Solving the Problems In order to achieve the above object, the present inventor focused on changing the shape of the rubber-like elastic body before press-fitting at the fitting portion, and as a result of intensive research, as a result, the press-fitting before press-fitting was carried out. By setting the inclination angle of the recess side wall on the rear end side with respect to the axis line smaller than the inclination angle of the depression side wall on the front end side with respect to the axis, after the press-fitting, the formation of the expansion bent portion in the concave part on the rear end side of the press-fitting is suppressed. Was obtained.

Accordingly, the present invention provides a fitting portion comprising a circumferential concave portion on the inner side in the axial direction of the rubber flange, and a contact portion formed at a central portion in the axial direction with a diameter larger than the inner diameter of the press-fitting member. In at least one of the side walls of the recesses, the side wall on the contact portion side is a conical inclined surface whose diameter gradually increases toward the center in the axial direction. An object of the present invention is to provide a press-fit type rubber bush in which the inclination angle is set smaller than the inclination angle with respect to the axis of the side wall of the recess at the front end side.

A preferable side wall inclination angle on the rear end side of the press-fitting, which suppresses the formation of the inflated bent portion, may be set to be smaller than the side wall inclination angle on the front side of the press-fitting by 15 to 25 degrees. Specifically, when the side wall inclination angle on the press-fit front end side is set to about 40 degrees, the side wall inclination angle on the press-fit rear end side may be set to 15 to 25 degrees. The reason why the inclination angle of the side wall on the rear end side of the press-fitting is set to the range of 15 to 25 degrees with respect to the inclination angle of the side wall on the front end side of the press-fitting of 40 degrees is related to the direction perpendicular to the axis, the set spring constant, the compression ratio, and the like. Because it cannot be uniquely determined,
If the angle is smaller than 5 degrees, the concave portion on the rear end side of the press-fit will disappear due to deformation of the rubber after press-fitting, and it is considered that the spring constant determined by the contact area with the press-fit member cannot be set accurately. If it is larger than this, the expanded and bent portion is formed by deformation of the rubber after press-fitting.

As shown in the embodiment shown in FIG. 2, when the side wall inclination angle α on the rear end side of the press-fitting is set to 40 degrees and the side wall inclination angle β on the front end side of the press-fitting is set to 20 degrees under a specific condition. No expansion and bending portions of rubber were formed on the rear side wall, and favorable results were obtained.

As described above, the setting of the inclination angle of the side wall of the concave portion can prevent the formation of a bent portion due to expansion in the axial direction at the time of press-fitting. Therefore, wrinkles can be prevented from being generated at the side wall portion during bending fatigue. , The durability is greatly improved. In addition, since there is no expansion bending portion, the spring characteristics of the press-fitting member contact portion are also stabilized.

Further, the rubber flows smoothly in the axial direction at the time of press-fitting, and the rubber bush can be easily mounted on the outer cylinder, the suspension arm and the like, which leads to an improvement in productivity. In addition, since no residual stress is generated on the side wall of the concave portion, the press-fit state of the press-fitting member contact portion is stabilized, and the resistance to removal by an external force from the axial direction is significantly improved.

The present invention aims at preventing the deformation of the side wall of the circumferential recess of the rubber bush at the time of press-fitting into the press-fitting member, and is directed to a rubber bush in which the circumferential recess remains even after press-fitting. In a rubber bush in which the circumferential concave portion does not remain after the press-fitting, the rubber flows to the rubber flange side by the press-fitting, and it is considered that problems such as spring characteristics and vibration fatigue do not occur. Outside.

However, from the viewpoint of preventing deformation of the side wall of the concave portion, the shaft member to which the rubber-like elastic body is fixed may be either a solid rod or a pipe-shaped member. An inner cylinder in which a rod can be inserted into the center and a rubber-like elastic body is fixed to the outer periphery may be included. Regardless of the rod or pipe in the solid state, a semispherical projection is provided at the axial center of the shaft member to increase the spring constant in the direction perpendicular to the axis and to reduce the spring constant in the twisting direction. The present invention can also be applied to a so-called bulge type rubber bush formed. Further, when the shaft member is a pipe-shaped one such as an inner cylinder, the fixing with the rubber-like elastic body may be performed by not only the vulcanization bonding method but also the press-fitting method.

The rubber-like elastic body may be any material as long as it is a natural rubber or a synthetic rubber generally used for a vibration-proof rubber, or a resinous elastomer. In addition, the outer shape of the center contact portion of the rubber-like elastic body is
The present invention can be applied to not only a round bar shape but also a concave shape having a concave center in the axial direction or a convex shape swelling conversely.
Further, the present invention can be applied to any press-fitting member into which the rubber-like elastic body is press-fitted, such as an outer cylinder or a connection cylinder such as a suspension arm.

[0022]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an exploded perspective view showing a main part of a vehicle suspension according to an embodiment of the present invention. As shown in FIG. 1, a rubber bush 1 according to the present invention is used for a connecting portion 4 of a vehicle body side frame 3 in a lower arm 2 of a MacPherson strut type suspension, and a connecting cylinder 5 of a lower arm 2 which is a press-fit member. It is used by press-fitting.

FIG. 2 is a sectional view showing a state of the rubber bush 1 before press-fitting, and FIG. 3 is a sectional view showing a state of the rubber bush after press-fitting. As shown in FIGS. 2 and 3, the rubber bush 1 is a rubber-like elastic body which is vulcanized and bonded to its shaft member 6 and has a longer shaft length than the press-fitting member 5 which is press-fitted from the axial direction. 7 is provided.

The rubber-like elastic body 7 has rubber flanges 8 and 9 formed at both ends in the axial direction, and a region inside the rubber flange 8 serves as a fitting portion 10 of the connecting cylinder 5 which is a press-fit member. The fitting portion 10 has an outer diameter before press-fitting formed at a central portion in the axial direction thereof larger than an inner diameter of the connecting tube 5, and a contact portion 11 in contact with an inner surface of the connecting tube 5, and rubber flanges on both sides thereof. 8 and 9 are formed.

The circumferential concave portions 12 and 13 allow the rubber of the contact portion 11 to flow in the axial direction when the fitting portion 10 is press-fitted into the connecting cylinder 5 so that the circumferential concave portions 12 and 13 can be formed even after press-fitting. , 1
The recesses 12 and 13 are set to the same depth at a depth such that 3 exists.

Circumferential recess 1 of rubber elastic body 7 before press-fitting
Reference numerals 2 and 13 denote conical inclined surfaces of which at least the side walls 14 and 15 on the press-fitting member contact portion 11 side gradually increase in diameter toward the contact portion 11. The inclination angle β of the concave side wall 15 on the rear end side of the press-fitting with respect to the axis A (the axis center line of the shaft member) is set smaller than the inclination angle α of the side wall 14 on the front end side of the press-fitting with respect to the axis A. As a result, the width L1 of the side wall 15 on the rear end side of the press-fitting is longer than the width L2 of the side wall 14 on the front end side of the press-fitting. On the other hand, the side wall on the rubber flange side of each of the concave portions 12 and 13 is a substantially vertical wall in accordance with the end wall surface of the connecting cylinder 5 to be fitted.

The rubber flanges 8 and 9 are connected to the connecting cylinder 5 after press-fitting.
The contact portion 11 is formed to have a larger diameter than the outer diameter of the contact portion 11 so as not to fall off. Further, the rubber flanges 8 and 9 have a conical surface on the outer wall of the rubber flange 8 on the front end side of the press-fitting in order to facilitate press-fitting into the connecting tube 5 from both sides when press-fitted into the connecting tube 5. , Rubber flange 9 on the rear end side of press fit
Is formed to be thin, thereby facilitating deformation of the connecting cylinder 5 in the axial direction during press-fitting.

The shaft member 6 is a forged product of a solid rod. A flange 18 for preventing the connecting cylinder from falling off is integrally formed outside the rubber flange 9 on the rear end side of the press-fitting. Is formed with a connection hole 19 for attachment to the vehicle body.
Although not shown, a flange for preventing the connecting cylinder 5 from falling off is fitted to the front end of the shaft member 6 on the press-fit side after the press-fitting into the connecting cylinder 5.

The side walls 14, 15 of the circumferential recesses 12, 13
Are not uniform depending on the diameter, compression ratio, set spring constant, etc. of the fitting portion before the rubber-like elastic body 7 is press-fitted,
More specifically, the outer diameter of the shaft member 6 is 20 mm, the axial length of the connecting tube 5 is 44 mm, the inner diameter is 30 mm, the outer diameter of the rubber flanges 8 and 9 is 34 mm, the distance between the rubber flanges is 35 mm, 11 has an outer diameter of 32 mm, the contact portion 11 has an axial length of 18 mm, and the peripheral recesses 12 and 13 have a depth of 2.5 mm (a bottom diameter of 27 mm). The side wall inclination angle α on the part 11 side is 40
When the side wall inclination angle β of the concave portion 13 on the rear end side of the press-fitting on the contact portion 11 side is set to 20 degrees, as shown in FIG. No expansion bend due to the flow was formed.

FIG. 4 is a view showing a step of press-fitting the rubber bush 1 into the connecting cylinder 5. The press-fitting work into the connecting cylinder 5 is performed by the same method as the conventional method shown in FIG. That is, when the rubber bush 1 is press-fitted into the connecting cylinder 5, FIG.
As shown by the arrow, the rubber flange 8 on the front end side of the press-fitting is inserted from one axial end 5a of the connecting cylinder 5 until it engages with the other end opening edge 5b.

At this time, since the interval between the rubber flanges 8 and 9 before press-fitting is set smaller than the axial width of the connecting cylinder 5, the rubber flange 8 on the front end side of the press-fitting is connected to the other end of the connecting cylinder 5. In order to engage with the opening edge 5b, the rubber bush 1 is excessively inserted and moved to the position shown in FIG. 4B, and then the rubber-like elastic body 7 is released by releasing the axial insertion force. By using the restoring force, the position is stabilized at the position shown in FIG.

In this case, the side wall 1 of the recess 13 on the rear end side of the press-fitting.
5, the side wall 14 of the recess 12 on the front end side of the press-fitting.
4c, the side wall 15 on the rear end side of the press-fit after press-fitting does not have an expansion bent portion due to the flow of rubber as shown in FIG. The inclined surface is substantially equiangular with the side wall inclination angle on the side.

Therefore, no wrinkles or the like are generated on the side wall portion, and the durability can be improved. Further, since there is no bent portion on the side wall 15, the set spring constant is also stabilized without affecting the spring constant determined at the center of the contact portion, which is the contact portion of the connecting cylinder 5. Also, conventionally, the presence of the inflated bent portion causes the press-fitting pressing force to increase,
In the present embodiment, since there is no bent portion, the connecting cylinder 5
Can be easily fitted, and productivity can be improved.

Further, the possibility of the connecting cylinder 5 falling off could be minimized. A comparative test was performed on the pulling force of the connecting cylinder 5 with the conventional one shown in FIG. As a test condition, while applying a constant force (for example, 100 kgf) to the shaft member in the axial direction, a relative amplitude of ± 15 degrees is given between the connecting tube and the rubber bush, and the shaft member is moved from the connecting tube. The pull-out force was evaluated based on the number of amplitudes at which pull-out started. As a result, the shaft member started to come out after about 200,000 times of the conventional one, whereas the one shown in the present embodiment started to come out after about 500,000 times, and the pull-out strength was about 2.5 times that of the conventional one. It has been proven that there is.

[0036]

As is apparent from the above description, according to the present invention, of the circumferential recesses formed inside the rubber flanges at both ends of the rubber bush, the inclination angle of the recess side wall on the rear end side of the press-fitting is set to the front end side on the press-fitting side. Is set smaller than the inclination angle of the side wall of the recess, so that after the press-fitting, the side wall on the rear end side of the press-fit does not have an expansion bending portion due to the flow deformation of rubber, so that the durability is improved and stable spring characteristics are obtained. In addition, the press-fitting member can be prevented from falling off.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a main part of a vehicle suspension according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a state before press-fitting a rubber bush;

FIG. 3 is a sectional view showing a state after press-fitting of a rubber bush;

FIG. 4 is a view showing a process of press-fitting a rubber bush into a connecting cylinder.

FIG. 5 is a view showing a step of press-fitting a conventional rubber bush with a rubber flange into a press-fitting member.

[Explanation of symbols]

 A Axis α, β Inclination angle 1 Rubber bush 2 Lower arm 5 Connecting cylinder 6 Central shaft member 7 Rubber-like elastic body 8, 9 Rubber flange 10 Fitting part 11 Contact part 12, 13 Circumferential recess 14, 15 Side wall

Claims (3)

[Claims] 1. A rubber-like elastic body fixed around a shaft member and having an axial length longer than that of a press-fitting member which is press-fitted from outside in an axial direction, and is provided at both ends in the axial direction of the rubber-like elastic body. In a press-fit rubber bush in which a rubber flange is formed and a circumferential recess is formed in the rubber flange in the axial direction, at least the axially central portion of both of the recesses has a side wall on the side of the press-fitting member contact portion that is axially centered. The inclined angle with respect to the axis of the concave side wall on the press-fitting rear end side is larger than the inclination angle with respect to the axis of the concave side wall on the press-fit front end side. A rubber bush characterized by having a smaller size. 2. The rubber bush according to claim 1, wherein the inclination angle of the side wall on the rear end side of the press-fitting is set smaller by 15 to 25 degrees than the inclination angle of the side wall on the front end side of the press-fitting. 3. The side wall inclination angle of the recess at the press-fit front end side on the side of the press-fitting member contacting portion is set to 40 degrees, while the inclination angle of the side wall of the recess at the press-fitting rear end side on the side of the press-fitting member contact portion. Is 1
The rubber bush according to claim 1, which is set at 5 to 25 degrees.