JP2018169013A - Cylindrical vibration-proof device - Google Patents

Abstract

To provide a cylindrical vibration-proof device in novel structure capable of realizing excellent durability while adjusting a spring property by bored parts.SOLUTION: In a cylindrical vibration-proof device 10 having a structure in which an inner shaft member 12 and an outer cylinder member 14 are elastically coupled with each other by a main body rubber elastic body 16, a first bored part 38 and a second bored part 40 that are opened on an axial end face of the main body rubber elastic body 16 are formed while being serially arranged side by side in a circumferential direction of the main body rubber elastic body 16. A depth dimension of the first bored part 38 is set larger than that of the second bored part 40. A connection portion between an inner surface of the first bored part 38 and an inner surface of the second bored part 40 is made into an inclined plane 42, and the inner surface of the first bored part 38 and the inner surface of the second bored part 40 are smoothly continued by the inclined plane 42.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cylindrical vibration isolator used for a suspension bush or a cab mount of an automobile.

  2. Description of the Related Art Conventionally, a cylindrical vibration isolator for use in a suspension bush for connecting a suspension arm of an automobile and a vehicle body in an anti-vibration manner, a cab mount for connecting a truck cab and a vehicle body in an anti-vibration manner, and the like is known. In this cylindrical vibration isolator, for example, as shown in Japanese Patent No. 4865637 (Patent Document 1), an inner shaft member and an outer cylinder member arranged in an externally inserted state are elastically connected to each other by a main rubber elastic body. Has a structured.

  By the way, the cylindrical vibration isolator shown in Patent Document 1 has a concave straight part that opens in the axial end surface of the main rubber elastic body in order to adjust the spring characteristics in the direction perpendicular to the axis. Is formed. Moreover, in the cylindrical vibration isolator as in Patent Document 1, it is conceivable that the first and second straight portions having different depths are formed in series in the circumferential direction.

  However, when the first and second straight portions having different depths are formed in series in the circumferential direction in the cylindrical vibration isolator, the first and second straight portions having the different depths are formed. Since a step is formed in the connection part of the second curb portion, at the time of elastic deformation of the main rubber elastic body due to input of vibration, a crack is likely to occur in the connection portion of the first curb portion and the second curb portion, Further improvement in durability has been demanded.

Japanese Patent No. 4865637

  The present invention has been made in the background of the above-mentioned circumstances, and its solution is a cylindrical structure with a novel structure capable of realizing excellent durability while adjusting the spring characteristics by the straight portion. The object is to provide a vibration isolator.

  Hereinafter, the aspect of this invention made | formed in order to solve such a subject is described. In addition, the component employ | adopted in each aspect as described below is employable by arbitrary combinations as much as possible.

  That is, according to a first aspect of the present invention, in the cylindrical vibration isolator having a structure in which the inner shaft member and the outer cylinder member are elastically connected to each other by the main rubber elastic body, an axial end surface of the main rubber elastic body is provided. The first straight part and the second straight part that are open are formed in series in the circumferential direction of the main rubber elastic body, and the first straight part is deeper than the second straight part. The connecting portion between the inner surface of the first curb portion and the inner surface of the second curb portion is an inclined surface, and the inner surface of the first curb portion and the second curb portion are It is characterized in that the inner surface is smoothly continuous by the inclined surface.

  According to the cylindrical vibration isolator having the structure according to the first aspect as described above, the object is achieved by appropriately adjusting the spring characteristics in the direction perpendicular to the axis by the first and second straight portions. Anti-vibration performance can be advantageously obtained. In addition, since the depths of the first and second straight portions are different from each other, the direction perpendicular to the axis in which the first straight portion is formed and the direction perpendicular to the axis in which the second straight portion is formed. Each direction spring characteristic is adjusted appropriately.

  Furthermore, when the main rubber elastic body is elastically deformed by vibration input, the first curb portion is formed by connecting the inner surface of the first curb portion and the inner surface of the second curb portion as an inclined surface. It is possible to prevent stress from concentrating on the connecting portion between the inner surface of the second and the second curb portion, and the durability can be improved by dispersing the stress.

  According to a second aspect of the present invention, in the cylindrical vibration isolator described in the first aspect, the inclined surface is inclined at an inclination angle of 10 to 30 degrees in the circumferential direction of the main rubber elastic body. It is.

  According to the second aspect, since the inclination angle of the inclined surface is 10 degrees or more, the stress concentration on the connection portion between the inner surface of the first curving portion and the inner surface of the second curving portion is effectively performed. Is prevented. Further, since the inclined angle of the inclined surface is 30 degrees or less, the connecting portion between the first and second straight portions is not excessively long in the circumferential direction, and the first straight portion and the second straight portion The region where the second curb portion can be formed is set sufficiently long in the circumferential direction.

  According to a third aspect of the present invention, in the cylindrical vibration isolator described in the first or second aspect, a circumferential end on the connection side to the second straight portion in the first straight portion is provided. The depth is a deep bottom with a partially increased depth.

  According to the third aspect, the deep bottom portion is provided in the first curb portion so that the inclined surface connecting the inner surface of the first curb portion and the inner surface of the second curb portion includes the inner surface of the deep bottom portion. Thus, a larger area of the inclined surface is ensured. In this way, by ensuring a large free surface at the connecting portion between the first and second curving portions, the stress can be more effectively distributed, and the durability of the main rubber elastic body can be improved. Improvement is advantageously achieved.

  According to a fourth aspect of the present invention, in the cylindrical vibration damping device according to any one of the first to third aspects, an inner flange portion in which an axial end portion of the outer tubular member projects toward the inner peripheral side; A stopper rubber integrally formed with the main rubber elastic body is fixed to the outer surface in the axial direction of the inner flange portion, and the first shaft portion and the second shaft portion are the inner shaft member. And the inner flange portion of the outer cylinder member is formed between the directions perpendicular to the axis.

  According to the fourth aspect, the inner flange portion provided on the outer cylinder member abuts against the member attached to the inner shaft member side via the stopper rubber in the axial direction, so that the inner shaft member and the outer The relative displacement amount in the axial direction of the cylindrical member is limited, and excessive elastic deformation of the main rubber elastic body is prevented, thereby improving durability.

  In such a structure provided with a stopper, a large load may occur in the rubber elastic body due to the stopper load acting on the stopper rubber, but the connection part between the first and second straight parts Since it is made into the smooth inclination shape, it is made difficult to concentrate the distortion | strain of the main body rubber elastic body resulting from a stopper load, and durability of a main body rubber elastic body is ensured.

  A fifth aspect of the present invention is the cylindrical vibration damping device according to any one of the first to fourth aspects, wherein the main rubber elastic body is formed with an annular circumferential groove that opens to an axial end surface. And a recess that partially opens at the bottom surface of the circumferential groove is formed, and the first straight portion is constituted by the formation portion of the recess, and the recess in the circumferential groove is formed. The second curb portion is constituted by a portion that is deviated in the circumferential direction.

  According to the fifth aspect, since the first straight portion and the second straight portion are formed continuously over the entire circumference in the circumferential direction, in the first straight portion and the second straight portion. A large free surface of the main rubber elastic body is secured, and the durability is further improved by dispersing the stress.

  According to the present invention, the desired vibration-proof performance can be advantageously obtained by appropriately adjusting the spring characteristics in the direction perpendicular to the axis by the first and second straight portions having different depths. it can. In addition, when the main rubber elastic body is elastically deformed by vibration input, the first curb portion is formed by connecting the inner surface of the first curb portion and the inner surface of the second curb portion as an inclined surface. It is possible to prevent stress from concentrating on the connecting portion between the inner surface of the second and the second curb portion, and the durability can be improved by dispersing the stress.

The top view which shows the cab mount 10 as 1st embodiment of this invention. II-II sectional drawing of FIG. Sectional drawing which expands and shows the part corresponded to the III-III cross section of FIG. The top view which shows the cab mount 10 as 2nd embodiment of this invention. VV sectional drawing of FIG. Sectional drawing which expands and shows the part corresponded to the VI-VI cross section of FIG.

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

  FIG. 1 shows a cab mount 10 as a first embodiment of a cylindrical vibration isolator having a structure according to the present invention. The cab mount 10 has a structure in which an inner shaft member 12 and an outer cylinder member 14 are elastically connected to each other by a main rubber elastic body 16. In the following description, unless otherwise specified, the front-rear direction refers to the up-down direction in FIG. 1, the left-right direction refers to the left-right direction in FIG. 1, and the up-down direction refers to the up-down direction in FIG.

  More specifically, the inner shaft member 12 is a high-rigidity member formed of metal or the like, and has a substantially annular plate-shaped end plate portion on the axial end surface of the cylindrical portion 18 having a small cylindrical shape. 20 has a structure in which the cylindrical portion 18 and the end plate portion 20 are fixed to each other by means such as welding.

  The outer cylinder member 14 is a highly rigid member made of metal or the like, and has a large-diameter, generally cylindrical shape. Further, an upper flange portion 22 that extends to the outer periphery is integrally formed at the upper end of the outer cylinder member 14 in the axial direction, and the width of the upper flange portion 22 in the direction perpendicular to the axis is partially increased on both sides in the left-right direction. Thus, a bolt hole 24 penetrating vertically is formed. Furthermore, a lower flange portion 26 as an inner flange portion protruding toward the inner periphery is integrally formed at the lower end portion in the axial direction of the outer cylinder member 14. The outer cylinder member 14 of the present embodiment can be obtained, for example, by forming the upper and lower flange portions 22 and 26 at the upper and lower end portions of a pipe-shaped metal material by press working.

  The cylindrical portion 18 of the inner shaft member 12 is disposed in a state of being inserted through the inner hole of the outer cylindrical member 14, and the space between the inner shaft member 12 and the outer cylindrical member 14 is mutually elastic by the main rubber elastic body 16. It is connected. The outer peripheral end portion of the end plate portion 20 of the inner shaft member 12 and the inner peripheral end portion of the upper flange portion 22 of the outer cylinder member 14 are disposed to face each other apart vertically.

  The main rubber elastic body 16 has a cylindrical shape as a whole, and its upper surface and inner peripheral surface are vulcanized and bonded to the inner shaft member 12, and its outer peripheral surface is vulcanized and bonded to the inner peripheral surface of the outer cylindrical member 14. Has been. Note that the lower flange portion 26 of the outer cylindrical member 14 is fixed to the lower end portion of the main rubber elastic body 16 in an embedded state.

  Further, the upper part of the main rubber elastic body 16 has a constricted shape, and a concave groove opened on the outer peripheral surface between the end plate portion 20 of the inner shaft member 12 and the outer cylinder member 14 in the main rubber elastic body 16. 28 is continuously formed over the entire circumference.

  An annular stopper rubber 30 integrally formed with the main rubber elastic body 16 is fixed to the lower flange portion 26 of the outer cylindrical member 14 and protrudes downward on the outer periphery from a circumferential groove 32 described later. . Furthermore, the stopper rubber 30 is formed with a plurality of air vent communication grooves 34 that open in the lower surface and extend in the radial direction at a plurality of locations in the circumferential direction (four locations in the present embodiment).

  Further, a circumferential groove 32 that opens to the lower surface is formed in the inner peripheral portion of the main rubber elastic body 16. The circumferential groove 32 is formed in the lower end portion of the main rubber elastic body 16 between the direction perpendicular to the axis of the cylindrical portion 18 of the inner shaft member 12 and the lower flange portion 26 of the outer cylindrical member 14, and extends over the entire circumference. And a continuous annular groove.

  Further, the circumferential groove 32 is formed with a pair of recesses 36, 36 that open to the bottom surface. The recesses 36 have a bottomed recess shape extending in the circumferential direction with a length less than a half circumference, and are formed on both sides of the main rubber elastic body 16 in the direction perpendicular to the axis, and open to the lower surface of the main rubber elastic body 16. doing.

  And the formation part of a pair of recessed parts 36 and 36 is made into the 1st curling part 38 and 38 in this embodiment. On the other hand, the part which remove | deviated the formation part of a pair of recessed parts 36 and 36 in the circumferential groove 32 in the circumferential direction is made into the 2nd curling part 40 and 40 in this embodiment. In short, the pair of second straight portions 40, 40 are provided between the pair of first straight portions 38, 38 in the circumferential direction, and the first straight portion 38 and the second straight portion 40 are circumferentially arranged. They are alternately arranged side by side in series.

  As shown in FIG. 2, the depth dimension d1 of the first straight portion 38 constituted by the circumferential groove 32 and the recess 36 is greater than the depth dimension d2 of the second straight portion 40 constituted by the circumferential groove 32. (D1> d2). The depth dimension d1 of the first curb portion 38 is desirably 1.3 times or less than the depth dimension d2 of the second curb portion 40, but the axial dimension of the main rubber elastic body 16 is not preferred. In some cases, d1 can be 1.5 times or less of d2.

  Here, the connecting portion in the circumferential direction between the inner surface of the first curb portion 38 and the inner surface of the second curb portion 40 is an inclined surface 42. The inclined surfaces 42 are inner surfaces at both ends in the circumferential direction of the recess 36, and are inclined outward in the axial direction from the first straight portion 38 to the second straight portion 40 in the circumferential direction. Is connected to the inner surface of the first curving portion 38 and to the inner surface of the second curving portion 40 at the other end in the circumferential direction. Thereby, the inner surface of the first curled portion 38 and the inner surface of the second curled portion 40 are formed into a continuous surface shape that is smoothly connected via the inclined surface 42 without a break point or a broken line.

  More preferably, as shown in FIG. 3, the inclined surface 42 has an inclination angle α of 10 to 30 degrees with respect to the axial direction in the circumferential direction of the main rubber elastic body 16. Accordingly, the connection between the first and second straight portions 38 and 40 described later is prevented while preventing the circumferential length of the connection portion between the first and second straight portions 38 and 40 from becoming too large. Dispersion of stress in the portion is effectively realized.

  In addition, the inclined surface 42 is not necessarily limited to the entire surface inclined at a substantially constant inclination angle. For example, the inclined surface 42 is a curved surface whose inclination angle continuously changes in the circumferential direction of the main rubber elastic body 16. Also good. Thus, when the inclination angle of the inclined surface 42 changes, the inclination angle of each part of the inclined surface 42 is set so that the average value of the inclined angle of the inclined surface 42 is in the range of 10 to 30 degrees. Is desirable.

  In the cab mount 10 having such a structure, for example, the inner shaft member 12 is attached to an automobile cab (not shown), and the outer cylinder member 14 is also attached to an automobile frame (not shown). In FIG. 2, the cab mount 10 is shown before being mounted on the vehicle, but when the cab mount 10 is mounted on the vehicle, a static shared support load of the cab is input in the axial direction of the cab mount 10. The inner shaft member 12 is displaced downward with respect to the outer cylinder member 14.

  Further, when the cab mount 10 is mounted on the vehicle, the stopper member 47 is attached to the inner shaft member 12 in a state of being superimposed on the lower surface of the inner shaft member 12. The stopper member 47 is disposed to face the lower flange portion 26 of the outer cylinder member 14 with a predetermined distance downward, and the stopper member 47 and the lower flange portion 26 are indirectly connected via the stopper rubber 30. By abutting, the relative axial displacement amount of the inner shaft member 12 and the outer cylinder member 14 is limited. In short, when the cab mount 10 is mounted on the vehicle, the stopper 48 for limiting the relative displacement in the axial direction of the inner shaft member 12 and the outer cylinder member 14 includes the stopper member 47 attached to the inner shaft member 12 and the outer member. It is configured by contact with a lower flange portion 26 provided on the cylindrical member 14 via a stopper rubber 30.

  When a vibration load in a direction perpendicular to the axis is input between the inner shaft member 12 and the outer cylinder member 14 in such a mounting state on the vehicle, the elastic deformation of the main rubber elastic body 16 causes the vibration energy to be attenuated. The intended anti-vibration effect is exhibited. In the present embodiment, the main rubber elastic body 16 is formed with the first straight portions 38, 38 and the second straight portions 40, 40, and the direction perpendicular to the axis in which the first straight portions 38, 38 are formed. Since the spring characteristics are adjusted in the direction perpendicular to the axis in which the second straight portions 40, 40 are formed, excellent anti-vibration performance, good riding comfort and excellent driving performance in the two directions perpendicular to the axis. It is realized with both.

  In addition, since the depths of the first and second curving portions 38 and 40 are set separately, the required performances differing in two directions perpendicular to the axis are highly realized, and excellent vibration isolation is achieved. Performance, good ride comfort, and excellent driving performance are both achieved.

  In addition, a connecting portion between the inner surface of the first curb portion 38 and the inner surface of the second curb portion 40 is an inclined surface 42, and the inner surface of the first curb portion 38 and the inner surface of the second curb portion 40 are The inclined surface 42 is smoothly continuous. Therefore, when the main rubber elastic body 16 is elastically deformed by the input of a vibration load, stress concentration on the connection portion between the inner surface of the first curving portion 38 and the inner surface of the second curling portion 40 is avoided, The durability is improved by dispersing the stress. Therefore, the problem that cracks are generated due to stress concentration at the connection portion between the inner surface of the first curb portion 38 and the inner surface of the second curb portion 40 can be avoided, and excellent reliability can be realized.

  Since the inclined surface 42 is provided, the angles formed by the upper and bottom surfaces of the first and second straight portions 38 and 40 extending substantially in the direction perpendicular to the axis and the inclined surface 42 are obtuse angles. Compared with the conventional structure in which the upper and bottom surfaces of the first and second straight portions 38 and 40 and the surface connecting them are perpendicular to each other, the stress concentration is reduced. In addition, since the surface connecting the upper and bottom surfaces of the first and second straight portions 38 and 40 is inclined, a larger free surface is secured, and stress distribution is more effectively realized. .

  Furthermore, in the present embodiment, the stress acting on the inclined surface 42 during vibration input is effectively reduced by setting the inclination angle α of the inclined surface 42 to 10 degrees or more. Further, since the inclination angle α of the inclined surface 42 is 30 degrees or less, the connection portion between the first and second straight portions 38 and 40 is prevented from becoming too long in the circumferential direction. The region where the straight portion 38 and the second straight portion 40 can be formed can be set sufficiently long in the circumferential direction.

  Furthermore, in the present embodiment, the first straight portions 38, 38 and the second straight portions 40, 40 are constituted by the annular circumferential groove 32 and the recess 36 opened in the bottom surface thereof. A large free surface is secured on the inner surfaces of the first and second straight portions 38 and 38 and the inner surfaces of the second straight portions 40 and 40, and the durability is improved more advantageously by dispersing the stress.

  Further, when a large load is input in the vertical direction, the lower surface of the stopper rubber 30 is pressed against the stopper member 47 attached to the inner shaft member 12, so that the inner shaft member 12 and the outer cylinder member 14 are moved in the vertical direction. The relative displacement is limited by the stopper 48. Here, even if the main rubber elastic body 16 is distorted because the stopper rubber 30 is greatly deformed, the connecting portion of the main rubber elastic body 16 between the first straight portion 38 and the second straight portion 40. The generation of the intensive strain in is prevented by providing the inclined surface 42. Therefore, even in the structure in which the stopper rubber 30 to which a large stopper load is input is formed integrally with the main rubber elastic body 16, the durability of the main rubber elastic body 16 can be sufficiently ensured.

  In the state where the lower surface of the stopper rubber 30 is pressed against the stopper member 47, the space by the circumferential groove 32 is communicated with the outer space on the outer peripheral side through the communication groove 34, and the lower opening of the circumferential groove 32 is the stopper member 47. Occurrence of abnormal noise due to sealing is prevented.

  4 and 5 show a cab mount 50 as a second embodiment of the present invention. The cab mount 50 has a structure in which the inner shaft member 12 and the outer cylindrical member 14 are elastically connected by the main rubber elastic body 16. The main rubber elastic body 16 includes a circumferential groove 32 that opens on the lower surface, and a peripheral groove 32. Two recesses 52, 52 that open to the bottom surface of the groove 32 are formed. In addition, in the following description, about the member and site | part substantially the same as 1st embodiment, description is abbreviate | omitted by attaching | subjecting the same code | symbol in a figure.

  More specifically, the recess 52 extends in the circumferential direction with a predetermined length of less than a half circumference, and opens on the lower surface of the main rubber elastic body 16. Further, in the recess 52, the depth d3 at both ends in the circumferential direction is made larger than the depth d4 at the center portion in the circumferential direction, and both end portions in the circumferential direction having a large depth are opened to the bottom surface of the recess 52, respectively. A concave deep bottom portion 54 is formed. And the 1st curling part 56 of this embodiment is comprised by the recess 52 containing the deep bottom parts 54 and 54. FIG. Accordingly, in the first curb portion 56 of the present embodiment, the depth d3 at both ends in the circumferential direction is made larger than the depth d4 at the center portion in the circumferential direction. A pair of first straight portions 56, 56 are arranged on both the front and rear sides of the inner shaft member 12 and open to the lower surface of the main rubber elastic body 16.

  In addition, a second straight portion 40 is formed between the pair of first straight portions 56 and 56 in the circumferential direction. The depth d2 of the second curb portion 40 is smaller than the depth d4 of the central portion in the circumferential direction of the first curb portion 56.

  Here, the connecting portion between the inner surface of the first curling portion 56 and the inner surface of the second curling portion 40 is an inclined surface 42. Thereby, the inner surface of the first curled portion 56 and the inner surface of the second curled portion 40 are smoothly continued by the inclined surface 42. The inclined surface 42 forms the inner surface of each recess 52 on the outer side in the circumferential direction (the outer side in the left-right direction in FIG. 4). In this embodiment, deep bottom portions 54, 54 are provided at the end in the circumferential direction of the recess 52. As a result, a large area of the inclined surface 42 is secured.

  In the cab mount 50 structured according to this embodiment as well, the spring characteristics in two directions perpendicular to the axis can be adjusted by the first straight portion 56 and the second straight portion 40 as in the first embodiment. As a result, the concentration of stress on the connecting portion between the first and second straight portions 56 and 40 is alleviated, and durability is improved.

  Moreover, the deep bottom portions 54 and 54 are formed at both ends in the circumferential direction of the first straight portion 56, so that the inclined surface 42 that connects the inner surface of the first straight portion 56 and the inner surface of the second straight portion 40. Therefore, the stress distribution at the connecting portion between the first and second straight portions 56 and 40 is more effectively realized, and the durability of the main rubber elastic body 16 is improved. Improvement is achieved more advantageously.

  As mentioned above, although embodiment of this invention was explained in full detail, this invention is not limited by the specific description. For example, the first straight portion 38 and the second straight portion 40 are not limited to a pair formed at positions facing each other in the radial direction, and at least one of them is formed in series in the circumferential direction. It only needs to be arranged side by side. Moreover, the 1st curling part 38 and the 2nd curling part 40 may be comprised by the recessed part formed independently and mutually arranged in series in the circumferential direction.

  Further, it is not always necessary for the first and second straight portions 38 and 40 to extend in the circumferential direction with a substantially constant cross-sectional shape, and the depth and the like change in the circumferential direction. Also good.

  In the above-described embodiment, the example in which the present invention is applied to the cab mount 10 of the automobile has been shown. Can be done. The present invention can be applied not only to a cylindrical vibration isolator for automobiles but also to a cylindrical vibration isolator used for motorcycles, railway vehicles, industrial vehicles, and the like.

10, 50: Cab mount (cylindrical vibration isolator), 12: Inner shaft member, 14: Outer cylinder member, 16: Main rubber elastic body, 26: Lower flange part (inner flange part), 30: Stopper rubber, 32 : Circumferential groove, 36, 52: Recess, 38, 56: First straight part, 40: Second straight part, 42: Inclined surface, 54: Deep bottom part

Claims (5)

In the cylindrical vibration isolator having a structure in which the inner shaft member and the outer cylindrical member are elastically connected to each other by the main rubber elastic body,
A first curving portion and a second curling portion that are open on an axial end surface of the main rubber elastic body are formed in series in the circumferential direction of the main rubber elastic body, and the first curling portion is The depth dimension is made larger than the second curb portion,
A connecting portion between the inner surface of the first curb portion and the inner surface of the second curb portion is an inclined surface, and the inner surface of the first curb portion and the inner surface of the second curb portion are smoothed by the inclined surface. A cylindrical vibration isolator characterized by being continuous.   The cylindrical vibration isolator according to claim 1, wherein the inclined surface is inclined at an inclination angle of 10 to 30 degrees in a circumferential direction of the main rubber elastic body.   The cylindrical shape according to claim 1 or 2, wherein a circumferential end of the first curb portion on the connection side to the second curb portion is a deep bottom portion having a partially enlarged depth dimension. Anti-vibration device.   An axial end portion of the outer cylindrical member is an inner flange portion that protrudes toward the inner peripheral side, and a stopper rubber that is integrally formed with the main rubber elastic body is fixed to an axial outer surface of the inner flange portion. In addition, the first straight portion and the second straight portion are formed between the inner shaft member and the inner flange portion of the outer cylinder member in a direction perpendicular to the axis. The cylindrical vibration isolator described in 1. In the main rubber elastic body, an annular circumferential groove that opens to the axial end surface is formed, and a recess that partially opens on the bottom surface of the circumferential groove is formed,
The first curb portion is constituted by the formation portion of the recess, and the second curb portion is constituted by a portion of the circumferential groove that is out of the recess in the circumferential direction. The cylindrical vibration isolator according to any one of 4.

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