JP2008169914A - Vibration isolation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration isolation device capable of sufficiently securing the degree of freedom of the tuning of a spring characteristic in a direction orthogonal to an axis, and exerting excellent durability by preventing the occurrence of a crack of a rubber-like elastic body. <P>SOLUTION: This vibration isolation device is provided with: an inner pipe 2; an outer pipe 3 surrounding the inner pipe 2 in parallel with the axis thereof; the rubber-like elastic body 4 connecting the inner pipe 2 to the outer pipe 3; a pair of bored parts 5 positioned by interposing the inner pipe 2 therebetween; and an annular projecting part 7 projecting from a circumferential surface at the axial center of the inner pipe 2 to the outside in the radial direction. The annular projecting part 7 includes: a pair of first parts 71 projecting in a first direction RD1 orthogonal to the axis, and facing the bored parts 5; a pair of second parts 72 projecting in a second direction RD2 perpendicular to the first direction and orthogonal to the axis; and third parts 73 recessed inward in the radial direction by reducing a projecting height relative to the first parts 71 and the second parts 72, and interposed between the first parts 71 and the second parts 72 to connect them to each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vibration isolator that includes an inner cylinder, an outer cylinder that surrounds the inner cylinder in an axially parallel manner, and a rubber-like elastic body that connects the two.

  An example of such a vibration isolator is shown in FIG. 5 is a cross-sectional view taken along the line B-B in FIG. 4, and FIG. 6 is an enlarged view of a main part in FIG. 5. The vibration isolator 81 includes an inner cylinder 82, an outer cylinder 83 that surrounds the inner cylinder 82, a rubber-like elastic body 84 that couples the inner cylinder 82, and a pair of straight portions 85 that are positioned with the inner cylinder 82 interposed therebetween. The axial side surface 84a of the rubber-like elastic body 84 extends radially outward from the outer peripheral surface of the inner cylinder 82, and has the same axial position as the end surface 83a of the outer cylinder 83 as shown in FIG. Has reached the inner peripheral surface.

  The vibration isolator 81 is a so-called bulge type vibration isolator including an annular convex portion 86 protruding radially outward from the outer peripheral surface of the central portion of the inner cylinder 82 in the axial direction. In such a bulge type vibration isolator, as disclosed in Patent Document 1 below, the thickness of the central portion in the axial direction of the rubber-like elastic body is reduced, so that the rigidity in the direction perpendicular to the axis is increased. Can do. For this reason, when used as a suspension bush, the rubber-like elastic body is molded from soft rubber to reduce the rigidity in the twisting direction, while ensuring the rigidity in the direction perpendicular to the axis, so that riding comfort and handling stability are improved. Can be achieved.

  By the way, in this type of vibration isolator, various characteristics are required depending on the apparatus and part to be mounted, and it is necessary to appropriately tune the spring constant and the spring ratio in the direction perpendicular to the axis according to the required characteristics. There is. Tuning of the spring characteristics is generally performed by adjusting the hardness of the rubber-like elastic body and the shape of the straight portion, and it is desirable that the degree of freedom is sufficiently secured.

  Further, as a result of the analysis, in the vibration isolator 81 as described above, the strain around the surface of the rubber-like elastic body 84 and the inner cylinder 82 increases when vibration is input, and cracks occur at both circumferential ends 85a of the straight portion 85. It turned out to be easier. In addition, since the rubber-like elastic body 84 is strongly pressed when the inner cylinder 82 and the outer cylinder 83 are relatively close to each other by providing the annular convex portion 86, the axial side surface 84 a is axially outer (see FIG. 6 right side) tends to bulge greatly, and it has been found that cracks are more likely to occur from the interface 87 with the inner peripheral surface of the outer cylinder 83.

In the following Patent Document 2, a pair of straight portions positioned between the inner cylinders are provided, and a restraining ring is embedded in the central portion in the axial direction of the rubber-like elastic body so that the restraining ring is completely exposed at the straight portion. An anti-vibration device is described. According to this vibration isolator, while increasing the spring constant in the direction perpendicular to the axis, the spring constant can be reduced in the arrangement direction of the straight portions, which is useful in terms of ensuring the degree of freedom in tuning. However, an increase in the number of parts is inevitable.
Japanese Utility Model Publication No. 6-76729 Japanese Utility Model Publication No. 6-22639

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vibration isolator capable of sufficiently securing the degree of freedom of tuning of spring characteristics in the direction perpendicular to the axis. An object of the present invention is to provide a vibration isolator capable of suppressing the occurrence of cracks in a rubber-like elastic body and exhibiting excellent durability.

  The above object can be achieved by the present invention as described below. That is, the vibration isolator according to the present invention includes an inner cylinder, an outer cylinder that surrounds the inner cylinder in an axially parallel manner, a rubber-like elastic body that connects the inner cylinder and the outer cylinder, the inner cylinder, and the outer cylinder. A pair of straight portions positioned between the cylinder and the inner cylinder, and an annular protrusion protruding radially outward from the outer peripheral surface of the axially central portion of the inner cylinder, the annular protrusion A pair of first portions projecting in a first direction perpendicular to the axis and facing the straight portion; and a pair of second portions projecting in a second direction orthogonal to the first direction and perpendicular to the axis And a third portion that is recessed inwardly in the radial direction with a projecting height smaller than that of the first portion and the second portion, and is interposed between the first portion and the second portion. It is what you have.

  According to the vibration isolator of the present invention, the annular convex part has the first part and the second part protruding in the direction perpendicular to the axis orthogonal to each other, and the third part recessed inward in the radial direction and connecting the both. Thus, the protruding heights of the first part and the second part can be individually set. For example, the protruding height of the second part can be easily increased or decreased while maintaining the protruding height of the first part. it can. As a result, the spring constant in the direction perpendicular to the axis where the straight portions are arranged, the spring constant in the direction perpendicular to the axis perpendicular thereto, and the spring ratio thereof can be adjusted appropriately and easily, and the degree of freedom in tuning the spring characteristics in the direction perpendicular to the axis Can be secured sufficiently.

  On the other hand, when the outer peripheral surface of the annular convex portion is circular or elliptical when viewed from the axial direction, the projecting height of the annular convex portion in the direction perpendicular to the axis is the annular convex portion in the direction perpendicular to the axis perpendicular thereto. Since the setting range of the spring constant and the spring ratio in the direction perpendicular to the axis is narrowed, it is difficult to ensure a sufficient degree of freedom in tuning the spring characteristics.

  In the above, the curb portion extends in an arc shape along the circumferential direction, both ends of the curb portion in the circumferential direction are bulged, and radially inward from the outer peripheral surface of the first portion or the second portion. It is preferable that it extends in the direction facing the third portion. Thereby, it is possible to ensure a large width dimension at both ends in the circumferential direction of the straight portion, and it is possible to suitably suppress the concentration of distortion at the both ends. As a result, it is possible to effectively prevent cracking of the rubber-like elastic body and improve durability.

  The vibration isolator according to the present invention includes an inner cylinder, an outer cylinder that surrounds the inner cylinder in an axially parallel manner, a rubber-like elastic body that connects the inner cylinder and the outer cylinder, the inner cylinder, and the outer cylinder. A rubber-like elastic body, comprising: a pair of straight portions positioned between the cylinder and the inner cylinder; and an annular convex portion protruding radially outward from an outer peripheral surface of an axially central portion of the inner cylinder. A first surface extending from the inner cylinder toward the outer cylinder while gradually decreasing the axial length of the rubber-like elastic body, and rising from the outer periphery of the first surface A second surface that increases the axial length of the rubber-like elastic body, and extends from the outer periphery of the second surface toward the inner peripheral surface of the outer cylinder, and is axially central from the end surface of the outer cylinder. And a third surface having an arcuate shape that is recessed toward the axially central side in the axial cross section.

  According to the above configuration, when the axial side surface of the rubber-like elastic body reaches the inner peripheral surface of the outer cylinder via the third surface as described above, the rubber-like elastic body is strongly pressed and the axial side surface is expanded. Even at the time of deformation, the occurrence of cracks can be suppressed and the durability of the rubber-like elastic body can be improved without concentrating strain near the interface with the inner peripheral surface of the outer cylinder. On the other hand, in the case of the example shown in FIGS. 4 to 6, cracks are likely to occur at the interface with the inner peripheral surface of the outer cylinder as described above. Further, when the third surface is simply inclined toward the inner peripheral surface of the outer cylinder in the axial cross section, strain is concentrated near the interface and cracks are easily generated. The demoldability of is reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing an example of a vibration isolator according to the present invention. 2 is a cross-sectional view taken along the line AA of FIG. 1, and FIG. 3 is an enlarged view of a main part of FIG. The vibration isolator 1 can be used as a suspension bush interposed between members constituting a vibration transmission system such as an automobile suspension mechanism.

  The vibration isolator 1 includes an inner cylinder 2, an outer cylinder 3 that surrounds the inner cylinder 2 in an axially parallel manner, and a rubber-like elastic body 4 that is interposed between the inner cylinder 2 and the outer cylinder 3 and elastically connects the two. With. The inner cylinder 2 is formed with sawtooth-shaped chevron grooves on its end surface, and the outer peripheral surface is covered with a rubber-like elastic body 4 with a little axial end. The inner cylinder 2 and the outer cylinder 3 can be formed of a known high-rigidity material such as a steel material or a high-rigidity resin material. On the other hand, as the rubber-like elastic body 4, a known rubber material in the technical field of automobile vibration-proof rubber can be used without limitation.

  In addition, the vibration isolator 1 includes a pair of straight portions 5 positioned between the inner cylinder 2 and the outer cylinder 3 with the inner cylinder 2 interposed therebetween. Each of the straight portions 5 extends in a circular arc shape with a required length along the circumferential direction. The curled portion 5 can be easily molded by arranging a core corresponding to the curled portion 5 in the mold when the rubber-like elastic body 4 is vulcanized. You may shape | mold by giving a hollow process to the rubber-like elastic body 4 after.

  The straight portion 5 has a length of approximately ¼ circumference in the circumferential direction and penetrates the rubber-like elastic body 4 in the axial direction, and a fillet portion recessed on both sides in the circumferential direction of the penetration portion 51. 52. The stopper rubber 6 is provided so as to protrude from the outer cylinder 3 toward the inner cylinder 2 so as to face the penetrating portion 51, and when a predetermined load or more is input in the first direction RD1 that is perpendicular to the axis. In this way, an excessive relative displacement between the inner cylinder 2 and the outer cylinder 3 is restricted.

  Further, the vibration isolator 1 includes an annular protrusion 7 that protrudes radially outward from the outer peripheral surface of the central portion in the axial direction of the inner cylinder 2. The annular convex portion 7 projects in the first direction RD1 and faces the straight portion 5, and a pair projects in the second direction RD2 perpendicular to the first direction RD1 and perpendicular to the axis. The second portion 72 and the first portion 71 and the second portion 72 have a lower projection height and are recessed radially inward, and are interposed between the first portion 71 and the second portion 72 to link them together. The third portion 73 has a cross-shaped outer shape as shown in FIG. 1 when viewed from the axial direction AD.

  In the present embodiment, the outer peripheral surfaces of the first portion 71 and the second portion 72 are constituted by curved surfaces as shown in FIGS. Further, the outer peripheral surface of the third portion 73 is formed in an arc shape when viewed from the axial direction AD, and the first portion 71 and the second portion 72 are connected smoothly to suppress the concentration of distortion as much as possible. In the present embodiment, an example in which the annular convex portion 7 is forged integrally with the inner cylinder 2 is shown, but the present invention is not limited to this, and the annular convex portion made of, for example, a resin is used as the inner cylinder. 2 may be externally fitted and fixed to the central portion in the axial direction.

  In the annular convex portion 7, the protruding heights of the first portion 71 and the second portion 72 can be set individually. For example, it is possible to easily reduce the spring in the second direction RD2 by reducing only the protrusion height of the second portion 72 while maintaining the protrusion height shown in FIG. it can. Therefore, the spring constants in the first direction RD1 and the second direction RD2 and their spring ratios can be adjusted appropriately and easily, and a sufficient degree of freedom in tuning the spring characteristics in the direction perpendicular to the axis can be secured.

  In the present embodiment, the protrusion heights of the first portion 71 and the second portion 72 are the same. However, in the present invention, when performing the tuning of the spring characteristics in the direction perpendicular to the axis, the protrusion heights are set to each other. You can make them different. Further, in the present embodiment, an example in which the circumferential length and the curvature of the outer circumferential surface of the first portion 71 and the second portion 72 are equivalent is shown, but these may be different.

  The pair of straight portions 5 are formed so that their circumferential ends 5 a bulge, and further expand radially inward from the outer peripheral surfaces of the first portion 71 and the second portion 72 and face the third portion 73. Yes. Thereby, the width dimension of the circumferential direction both ends 5a of the straight part 5 can be ensured large, and the concentration of the distortion to the both ends 5a can be suppressed. As a result, generation of cracks in the rubber-like elastic body 4 is effective. It can prevent and improve durability. In order to achieve this effect more suitably, in this embodiment, the inner wall surfaces of the circumferential ends 5 a of the straight portion 5 are formed in an arc shape so as to correspond to the outer peripheral surface of the third portion 73.

  On the other hand, when the annular protrusion 7 is circular as viewed from the axial direction, not only is it difficult to ensure a sufficient degree of freedom in tuning the spring characteristics described above, but also the circumferential direction of the straight portion 5. The width dimension of the both ends 5a cannot be ensured as shown in FIG. That is, this embodiment ensures the width dimension of the circumferential direction both ends 5a large using the shape of the 3rd part 73 of the cyclic | annular convex part 7, and is the largest of the cyclic | annular convex part 7 with respect to the example of FIG. When the diameters are the same, the durability can be improved without changing the spring characteristics.

  The rubber-like elastic body 4 is vulcanized and bonded to the outer peripheral surface of the inner cylinder 2 and the inner peripheral surface of the outer cylinder 3, and elastically supports the inner cylinder 2 with respect to the outer cylinder 3. When vibration having a relatively small amplitude is input, the vibration-proof effect is exhibited by the bending of the rubber-like elastic body 4. The protrusion 42 protrudes along the second direction RD2 on the axial side surface 41 of the rubber-like elastic body 4 and is used for identification of the vibration isolator 1 and positioning in the circumferential direction.

  The axial side surface 41 of the rubber-like elastic body 4 extends from the inner cylinder 2 toward the outer cylinder 3 while gradually decreasing the axial length of the rubber-like elastic body 4 as shown in FIG. The first surface 41a, the second surface 41b that rises from the outer periphery of the first surface 41a and increases the axial length of the rubber-like elastic body 4, and the outer tube 3 from the outer periphery of the second surface 41b. A third surface 41c extending toward the inner peripheral surface is connected. The protrusion 42 described above is provided on the first surface 41a.

  The third surface 41c reaches a position spaced from the end surface 31 of the outer cylinder 3 toward the axially central side, and has an arc shape recessed toward the axially central side in the axial section. Thereby, not only the free length of the axial side surface 41 is increased, but also the third surface 41 c is interposed between the second surface 41 b and the inner peripheral surface of the outer cylinder 3, so that the rubber-like elastic body 4. It is possible to prevent the bulging deformation of the axial side surface 41 when the pressure is strongly pressed from reaching the vicinity of the interface with the inner peripheral surface of the outer cylinder 3 and to improve the durability of the rubber-like elastic body 4. it can.

  On the other hand, when the third surface 41c is not provided, or when the third surface 41c is simply inclined toward the inner peripheral surface of the outer cylinder 3, the bulging deformation of the axial side surface 41 is caused. It becomes easy to reach the vicinity of the interface with the inner peripheral surface of the outer cylinder 3, and for this reason, strain is concentrated near the interface and cracks are likely to occur. In the present embodiment, the distance G from the end surface 31 of the outer cylinder 3 to the third surface 41c is preferably 0.5 mm or more from the viewpoint of appropriately achieving the durability improvement effect described above, and is preferably 1 mm or more. It is more preferable.

  The present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the spirit of the present invention. For example, the characteristics of the rubber-like elastic body depend on the application to be used. It can be changed as appropriate.

The top view which shows an example of the vibration isolator which concerns on this invention AA arrow sectional view of FIG. 2 is an enlarged view of the main part of FIG. Plan view showing an example of a vibration isolator BB arrow sectional view of FIG. Enlarged view of the main part of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Anti-vibration device 2 Inner cylinder 3 Outer cylinder 4 Rubber-like elastic body 5 Curled part 5a Both circumferential ends 7 of the curled part Annular convex part 31 End surface 41 Axial side surface 41a First surface 41b Second surface 41c Third surface 51 Penetration part 52 Fillet part 71 1st part 72 2nd part 73 3rd part AD Axial direction RD1 1st direction RD2 2nd direction

Claims (3)

An inner cylinder, an outer cylinder that surrounds the inner cylinder in an axially parallel manner, a rubber-like elastic body that connects the inner cylinder and the outer cylinder, and the inner cylinder is sandwiched between the inner cylinder and the outer cylinder And a pair of straight portions, and an annular convex portion projecting radially outward from the outer peripheral surface of the axial central portion of the inner cylinder,
The annular convex portion is
A pair of first portions projecting in a first direction perpendicular to the axis and facing the straight portion;
A pair of second portions projecting in a second direction perpendicular to the first direction and perpendicular to the axis;
A protective portion having a third portion that is recessed inwardly in the radial direction with a projecting height smaller than that of the first portion and the second portion, and is interposed between the first portion and the second portion. Shaker. The straight portion extends in an arc shape along the circumferential direction,
The anti-vibration device according to claim 1, wherein both ends of the curb portion in the circumferential direction are formed to bulge and extend radially inward from the outer peripheral surface of the first portion or the second portion to face the third portion. apparatus. An inner cylinder, an outer cylinder that surrounds the inner cylinder in an axially parallel manner, a rubber-like elastic body that connects the inner cylinder and the outer cylinder, and the inner cylinder is sandwiched between the inner cylinder and the outer cylinder And a pair of straight portions, and an annular convex portion projecting radially outward from the outer peripheral surface of the axial central portion of the inner cylinder,
An axial side surface of the rubber-like elastic body is
A first surface extending from the inner cylinder toward the outer cylinder while gradually decreasing the axial length of the rubber-like elastic body;
A second surface that rises from the outer periphery of the first surface and increases the axial length of the rubber-like elastic body;
Extends from the outer periphery of the second surface toward the inner peripheral surface of the outer cylinder, reaches a position spaced from the end surface of the outer cylinder toward the axially central side, and is recessed toward the axially central side in the axial section. And a third surface having an arcuate shape.

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