JP6424112B2 - Cylindrical vibration isolator - Google Patents

Description

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

  2. Description of the Related Art Conventionally, a cylindrical vibration isolator is known as a type of a vibration isolator that is disposed between members constituting a vibration transmission system and that mutually antivibrates and connects these members. The cylindrical vibration isolator has a structure in which an inner shaft member is inserted into a cylindrical portion of an outer cylindrical member, and the inner shaft member and the outer cylindrical member are elastically connected to each other in the radial direction by a main rubber elastic body. Yes.

  In addition, for the purpose of reducing the weight and facilitating production, it has recently been proposed to form a metal outer cylinder member with a synthetic resin. For example, JP 2001-74080 A (Patent Document) 1) etc.

  By the way, like the cylindrical vibration isolator of Patent Document 1, a member such as a vehicle body in which a flange portion extending to the outer periphery is formed at one axial end portion of the outer cylindrical member and the flange portion is attached to the inner shaft member. In some cases, stopper means for limiting the amount of relative displacement in the axial direction between the inner shaft member and the outer cylinder member may be configured.

  However, such a stopper means has a problem that it is difficult to ensure a sufficient degree of freedom in tuning characteristics. That is, in order to adjust the characteristics of the stopper means, it is effective to adjust the size, shape, arrangement, etc. of the buffer rubber by enlarging the flange portion to ensure a substantial stopper contact area. However, the protrusion amount to the outer periphery of a flange part may be restrict | limited depending on the arrangement | positioning space of a cylindrical vibration isolator. Moreover, even if the flange portion can be protruded greatly to the outer periphery, the outer cylindrical member made of synthetic resin is likely to crack the flange portion due to the stopper load, resulting in the characteristic tuning of the stopper means. There is also a possibility that a large degree of freedom cannot be obtained.

JP 2001-74080 A

  The present invention has been made in the background of the above-mentioned circumstances, and the problem to be solved is to determine the relative displacement amount in the axial direction of the inner shaft member and the outer cylindrical member without causing the flange portion to protrude greatly to the outer periphery. An object of the present invention is to provide a cylindrical vibration isolator having a novel structure that can tune the characteristics of the limiting stopper means with a large degree of freedom.

  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 the first aspect of the present invention, the inner shaft member is inserted into the cylindrical portion of the outer cylinder member formed of synthetic resin, and the inner shaft member and the outer cylinder member are mutually elastic by the main rubber elastic body. A flange portion that extends to the outer periphery is integrally formed at one end portion in the axial direction of the cylindrical portion, and a buffer rubber is fixed to an outer surface in the axial direction of the flange portion, and the inner shaft member. And a stopper means for limiting the relative displacement in the axial direction of the outer cylindrical member is constituted by axial contact between the inner shaft member and the flange portion through the shock absorbing rubber. The inner diameter dimension of one end portion in the axial direction of the cylindrical portion on which the flange portion is formed is smaller than the inner diameter dimension of the other end portion in the axial direction of the cylindrical portion, and the axis of the cylindrical portion One end of the direction is the other axial direction of the cylindrical part That it is thicker than the end portion, and wherein.

  According to the cylindrical vibration isolator having the structure according to the first aspect of the present invention, the shock absorbing rubber is separated from the flange portion by making one end portion in the axial direction of the cylindrical portion thick. By fixing and providing over the axial direction end surface of a cylindrical part, the freedom degree of adjustments, such as a magnitude | size, a shape, and arrangement | positioning of a buffer rubber, can be enlarged. Thus, in the state where the inner shaft member and the axial end surface of the outer cylindrical member including the axial outer surface of the flange portion are in axial contact with each other via the buffer rubber, the axial spring characteristics of the cylindrical vibration damping device are reduced. It can be set with a large degree of freedom, and the desired anti-vibration performance can be realized advantageously.

  In addition, one axial end of the cylindrical portion is made thicker by making the inner diameter dimension smaller than the other axial end, and the axial end surface of the outer cylindrical member is secured large in the radial direction. Therefore, it is possible to obtain a large fixing surface of the buffer rubber without increasing the amount of protrusion of the flange portion toward the outer peripheral side. Therefore, it is not necessary to increase the outer diameter of the cylindrical vibration isolator in order to obtain a large fixing surface of the buffer rubber, and even when the arrangement area of the cylindrical vibration isolator is limited particularly on the outer peripheral side, A large degree of freedom in tuning the axial spring characteristics can be secured.

  Further, since the other end in the axial direction of the cylindrical portion has a larger inner diameter than the one end, the other end in the axial direction that does not affect the fixed area of the buffer rubber is A large rubber volume is ensured, and the anti-vibration performance in the direction perpendicular to the axis and the direction of twisting is advantageously exhibited, and the durability of the main rubber elastic body is prevented from being lowered. In addition, since the other end portion in the axial direction of the cylindrical portion is thinner than the one end portion, even if a large rubber volume in the radial direction of the main rubber elastic body is secured, the cylindrical portion The other end in the axial direction does not have a remarkably larger diameter than the one end.

  According to a second aspect of the present invention, in the cylindrical vibration damping device described in the first aspect, the thickness of one end portion in the axial direction and the other end portion of the cylindrical portion in which the flange portion is formed. The difference in thickness is 5 mm or less.

  According to the second aspect, it is possible to prevent the thickness dimension of the cylindrical portion from changing significantly in the axial direction, and the crack due to stress concentration at the thickness changing portion and the shape of the main rubber elastic body can be prevented. The adverse effect on the vibration isolation characteristics due to the restriction is avoided, and the cylindrical portion can be manufactured easily and with stable quality.

  According to a third aspect of the present invention, in the cylindrical vibration isolator described in the first or second aspect, one end portion in the axial direction of the cylindrical portion on which the flange portion is formed is less than the flange portion. Is thick, and the thickness of one end in the axial direction of the cylindrical portion is three times or less that of the flange portion.

  According to the third aspect, since the flange portion is made relatively thin, it is easy to secure a large adjustment width of the stopper clearance in the axial direction of the stopper means, and the axial dimension of the buffer rubber is also large and free. Can be adjusted in degrees.

  In addition, the difference between the thickness of one end in the axial direction of the cylindrical portion integrally connected to each other and the thickness of the flange portion is suppressed to some extent, so that the cylindrical end of the flange portion connected to the cylindrical portion is cylindrical. Cracks due to differences in deformation rigidity between the flange portion and the flange portion, shrinkage after molding, and the like are less likely to occur.

  According to a fourth aspect of the present invention, in the cylindrical vibration isolator described in any one of the first to third aspects, one end portion in the axial direction of the cylindrical portion in which the flange portion is formed; The difference in the inner diameter of the other end in the axial direction of the cylindrical portion is made smaller than 0.2 times the inner diameter of the one end in the axial direction of the cylindrical portion.

  According to the fourth aspect, the difference in inner diameter between one end portion in the axial direction of the tubular portion and the other end portion is made sufficiently small with respect to the size of the outer tubular member. The influence on the vibration isolation characteristics due to the difference in the inner diameter of the shaft in the axial direction is suppressed, and excellent vibration isolation performance can be obtained.

  According to a fifth aspect of the present invention, in the cylindrical vibration isolator described in any one of the first to fourth aspects, at least a part of the inner peripheral surface of the cylindrical portion forms the flange portion. The tapered surface is a tapered surface that gradually increases in diameter from one axial direction of the cylindrical portion toward the other axial direction of the cylindrical portion.

  According to the fifth aspect, the thickness and the inner diameter of the cylindrical portion gradually change in the axial direction due to the tapered surface, so that the cylindrical portion can be prevented from receiving vibration load or radial input due to mounting on the vehicle. The concentration of stress on the inner peripheral surface is reduced or avoided, and the durability of the cylindrical portion is improved. In addition, if the metal mold | die which shape | molds the internal peripheral surface of a cylindrical part is extracted to the other axial direction of a cylindrical part after shaping | molding, the outstanding mold release property can also be implement | achieved by a taper surface.

  According to a sixth aspect of the present invention, in the cylindrical vibration isolator described in any one of the first to fifth aspects, one end portion in the axial direction of the cylindrical portion on which the flange portion is formed is The inner diameter is a straight portion having a constant axial direction.

  According to the sixth aspect, it is possible to prevent the corner formed by the inner peripheral surface of the outer cylindrical member and one end surface in the axial direction from becoming an acute angle, and the durability can be improved by relaxing the stress concentration. Figured. In the case where the main rubber elastic body is formed so as to cover the inner peripheral surface of one end in the axial direction of the cylindrical portion, and the buffer rubber is integrally formed with the main rubber elastic body, the main rubber elastic body Can be prevented from tearing by touching the corner formed by the inner peripheral surface of the outer cylinder member and one end surface in the axial direction, and the durability of the main rubber elastic body can be improved.

  According to the present invention, one end portion in the axial direction of the cylindrical portion of the outer cylindrical member is thicker than the other end portion, and the inner diameter dimension of the cylindrical portion is the other end portion in the axial direction. It is made smaller than the end. As a result, one end surface in the axial direction of the outer cylinder member is formed with a large area, and the cushion rubber fixed to one end surface in the axial direction of the outer cylinder member can be set with a large degree of freedom in size, shape, arrangement, etc. Is done. Therefore, the axial direction spring characteristic in a state where the stopper means affected by the buffer rubber is in contact can be adjusted with a greater degree of freedom, and the desired anti-vibration performance can be advantageously realized. In addition, it is not necessary to project the flange portion more greatly to the outer periphery, and an increase in the diameter of the cylindrical vibration isolator can be avoided.

The front view which shows the suspension bush as 1st embodiment of this invention. II-II sectional drawing of FIG. III-III sectional drawing of FIG. The longitudinal cross-sectional view of the outer cylinder member which comprises the suspension bush shown in FIG. The longitudinal cross-sectional view which shows the suspension bush shown in FIG. 1 in the mounting state to a vehicle.

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

  1 to 3 show a suspension bush 10 for an automobile as a first embodiment of a cylindrical vibration isolator having a structure according to the present invention. The suspension bush 10 has a structure in which an inner shaft member 12 and an outer cylinder member 14 are elastically connected by a main rubber elastic body 16.

  More specifically, the inner shaft member 12 is a small-diameter cylindrical member, and is a high-rigidity member formed of metal such as iron or aluminum alloy, fiber-reinforced synthetic resin, or the like. The inner shaft member 12 is desirably thinned within a range in which deformation rigidity and mounting strength to the vehicle are sufficiently secured in order to obtain a large radial dimension of the main rubber elastic body 16 described later. In addition, the outer peripheral surface of the inner shaft member 12 is a cylindrical surface extending in the axial direction with a substantially constant outer diameter. However, the outer peripheral surface may be provided with unevenness separately or separately. By providing the recess that opens, a larger rubber volume of the main rubber elastic body 16 can be secured, while by providing the protruding portion that protrudes on the outer peripheral surface, a stopper in the direction perpendicular to the axis can be configured.

  The outer cylindrical member 14 includes a cylindrical portion 18 having a large-diameter cylindrical shape, and a flange portion 20 that protrudes in the direction perpendicular to the outer peripheral side is formed at one axial end of the cylindrical portion 18. These are integrally formed continuously over the entire circumference. The outer cylinder member 14 is a high-rigidity member, and is formed of a synthetic resin such as polyamide, polyacetal, polybutylene terephthalate, or polycarbonate, and is preferably reinforced with glass fiber or carbon fiber. Fiber reinforced synthetic resin is used. In addition, although the cylindrical part 18 of the outer cylinder member 14 has desirable cylindrical shape, an elliptical cylinder shape etc. can be employ | adopted, for example.

  The inner shaft member 12 is inserted into the cylindrical portion 18 of the outer cylinder member 14 on substantially the same central axis, and the inner shaft member 12 and the outer cylinder member 14 are elastically connected by the main rubber elastic body 16. The main rubber elastic body 16 is a rubber elastic body having a thick, substantially cylindrical shape, and its inner peripheral surface is vulcanized and bonded to the outer peripheral surface of the inner shaft member 12, and the outer peripheral surface is the outer cylindrical member 14. It is vulcanized and bonded to the inner peripheral surface, and is formed as an integrally vulcanized molded product including the inner shaft member 12 and the outer cylindrical member 14. In the state where the inner shaft member 12 is elastically connected by the outer cylindrical member 14 and the main rubber elastic body 16, both end portions in the axial direction protrude outward in the axial direction from the outer cylindrical member 14. The amount of protrusion to the right (in FIG. 2, right) is smaller than the amount of protrusion to the other (left in FIG. 2).

  Further, the main rubber elastic body 16 is formed with a straight portion 22 opened on the axial end face on both sides in the axial direction. The straight portion 22 extends in the circumferential direction at a central portion in the radial direction of the main rubber elastic body 16 with a substantially constant semicircular cross section. In the present embodiment, the curly portion 22 is an annular recess that is continuous over the entire circumference.

  Furthermore, a buffer rubber 24 is fixed to the outer surface of the outer cylinder member 14 in the axial direction. The shock absorbing rubber 24 has an annular shape extending in the circumferential direction with a substantially constant cross section, and is provided on one end surface in the axial direction of the cylindrical portion 18 constituting the axial outer surface of the outer cylindrical member 14 and the axial outer surface of the flange portion 20. It is fixed. The buffer rubber 24 of the present embodiment is connected to the main rubber elastic body 16 on the inner peripheral side of the cylindrical portion 18 and is integrally formed with the main rubber elastic body 16.

  Here, a tapered surface 26 is provided on the inner peripheral surface of the cylindrical portion 18 of the outer cylindrical member 14. That is, the inner peripheral surface of the central portion in the axial direction of the cylindrical portion 18 is a tapered surface 26 that gradually decreases in diameter toward one side in the axial direction where the flange portion 20 is provided. The central portion in the axial direction is a tapered portion 28 that gradually increases in thickness from the other axial direction to the other. In the present embodiment, the outer peripheral surface of the cylindrical portion 18 is a cylindrical surface that is straight in the axial direction, and has a substantially constant outer diameter. However, the other end portion in the axial direction of the cylindrical portion 18 is a guide surface 29 whose outer peripheral surface gradually becomes smaller in diameter toward the other axial direction in order to facilitate press-fitting into a holder 40 described later.

  In addition, on both sides in the axial direction across the taper portion 28, the inner diameter dimension of the cylindrical portion 18 is substantially constant in the axial direction, and one axial side of the cylindrical portion 18 is thicker as a straight portion than the taper portion 28. While being the meat part 30, the other axial side is the thin part 32. As described above, one end portion in the axial direction of the cylindrical portion 18 provided with the flange portion 20 is a thick portion 30 having a straight structure in which both the inner diameter dimension and the outer diameter dimension are substantially constant in the axial direction. Thus, the inner peripheral corner portion at one end portion in the axial direction of the thick portion 30 is substantially perpendicular to the longitudinal section without being an acute angle. In the present embodiment, the tapered surface 26 and the inner peripheral surfaces of the thick portion 30 and the thin portion 32 are smoothly and continuously connected by a curved surface forming an arc having a large curvature radius in the longitudinal section.

  Further, the thickness dimension t1 of the thick part 30 is larger than the thickness dimension t2 of the thin part 32 (t1> t2). Further, preferably, the difference t1-t2 between the thickness dimension t1 of the thick part 30 and the thickness dimension t2 of the thin part 32 is 5 mm or less, and the thick part 30 is extremely smaller than the thin part 32. It is set not to be thick.

  Furthermore, in this embodiment, the thickness dimension t1 of the thick part 30 is larger than the thickness dimension t3 of the flange part 20 (t1> t3). More preferably, the thickness dimension t1 of the thick part 30 is set to be not more than three times the thickness dimension t3 of the flange part 20 (t1 ≦ 3 * t3). It is set not to become extremely thick. In the present embodiment, the thickness dimension t2 of the thin portion 32 is larger than the thickness dimension t3 of the flange portion 20 (t2> t3), and the difference in thickness between the thick portion 30 and the thin portion 32 is determined. However, it is made smaller than the difference of the thickness of the thick part 30 and the flange part 20. FIG.

  Furthermore, the outer diameter dimension of the cylindrical portion 18 is made substantially constant over the entire length in the axial direction, and the outer diameter dimensions of the thick portion 30 and the thin portion 32 are substantially the same, and the thick portion 30. Is smaller than the inner diameter R2 of the thin portion 32 (R1 <R2). Preferably, the inner diameter difference R2-R1 between the thick portion 30 and the thin portion 32 is smaller than 0.2 times the inner diameter R1 of the thick portion 30 (R2-R1 <0.2 * R1). Therefore, the difference in inner diameter between the thick portion 30 and the thin portion 32 is limited with respect to the size of the outer cylinder member 14.

  In the present embodiment, the inner surface of the straight portion 22 that is the axial end surface of the main rubber elastic body 16 is positioned on the inner peripheral side of the thick portion 30 or the thin portion 32 whose inner diameter is constant in the axial direction. As described above, the axial length and the axial position of the tapered portion 28 are set. Thereby, in the vehicle mounting state of the suspension bush 10 described later, for example, the direction of the load exerted on the axial end portion of the main rubber elastic body 16 when the load is applied in the direction perpendicular to the axis or the direction of the twist is the inclination angle of the tapered surface 26. It can be prevented from changing according to. Therefore, the influence of the tapered surface 26 on the characteristics such as durability can be suppressed at the axial end of the main rubber elastic body 16 where the deformation amount tends to increase.

  A shock absorbing rubber 24 is fixed to one end surface in the axial direction of the outer cylindrical member 14, and the fixing surface of the shock absorbing rubber 24 in the outer cylindrical member 14 is between the axial outer surface of the flange portion 20 and the thick portion 30. It is comprised by the axial direction outer surface. In the present embodiment, the outer peripheral end of the buffer rubber 24 is located on the inner peripheral side with respect to the outer peripheral end of the flange portion 20.

  The suspension bush 10 having such a structure is mounted on a vehicle as shown in FIG. That is, one end surface in the axial direction of the inner shaft member 12 is overlapped with the vehicle body 34, and the inner shaft member 12 is constituted by the inner shaft member 12 and the bolt 36 inserted into the vehicle body 34 and the nut 38 screwed thereto. And the vehicle body 34 are fixed to each other. On the other hand, the outer cylindrical member 14 is fixed to the holder 40 by press-fitting the cylindrical portion 18 into the cylindrical holder 40 provided on the trailing arm or the like from the other end in the axial direction. In the present embodiment, the outer cylinder member 14 and the holder 40 are positioned in the axial direction by press-fitting until the flange portion 20 abuts on one end of the holder 40 in the axial direction in the axial direction. . As described above, the suspension bush 10 according to the present embodiment is mounted on the vehicle, and the suspension side member such as the trailing arm is connected to the vehicle body 34 in a vibration-proof manner. In addition, since the cylindrical portion 18 of the present embodiment has increased deformation rigidity in the radial direction by the thick portion 30, the difference between the outer diameter size of the cylindrical portion 18 and the inner diameter size of the holder 40 (press fitting allowance). ) Is relatively small, a sufficient resistance against the removal from the holder 40 can be obtained.

  Further, as shown in FIG. 5, when the suspension bush 10 is mounted on the vehicle, the flange portion 20 of the outer cylinder member 14 is disposed so as to face the vehicle body 34 fixed to the inner shaft member 12 in the axial direction. A cushioning rubber 24 is disposed between the axially facing surfaces of the flange portion 20 and the vehicle body 34. In the present embodiment, in a stationary state where an external force such as a vibration load does not act, the outer surface in the axial direction of the cushioning rubber 24 is in contact with the vehicle body 34, and the cushioning rubber 24 is a shaft between the flange portion 20 and the vehicle body 34. Pre-compressed in the direction.

  In such a state in which the suspension bush 10 is mounted on the vehicle, vibration input between the vehicle body 34 and the suspension is reduced based on an energy damping action or a vibration insulation action due to elastic deformation of the main rubber elastic body 16. Transmission of vibrations input from the road surface side to the vehicle body 34 is reduced.

  In addition, the vehicle body 34 fixed to the inner shaft member 12, the thick portion 30 and the flange portion 20 of the outer cylinder member 14 are disposed to face each other in the axial direction, and are mutually connected via the buffer rubber 24. It is in contact. Thereby, the relative displacement amount of the inner shaft member 12 to the other side in the axial direction with respect to the outer cylindrical member 14 due to the input in the axial direction is the vehicle body 34 fixed to the inner shaft member 12 and the buffer rubber 24 of the outer cylindrical member 14. Therefore, the stopper means 42 of this embodiment is configured. By providing such a stopper means 42, excessive shear deformation of the main rubber elastic body 16 with respect to the axial input is prevented, and durability of the main rubber elastic body 16 is improved.

  Incidentally, the axial spring characteristics of the suspension bush 10 include not only the spring component of the main rubber elastic body 16 disposed between the inner shaft member 12 and the outer cylinder member 14 in the radial direction, but also the flange portion 20 and the vehicle body 34. The spring component of the shock absorbing rubber 24 disposed between the two axial directions also affects. In particular, in the axial direction, the spring of the main rubber elastic body 16 is mainly due to the shear spring component, whereas the spring of the shock absorbing rubber 24 is mainly due to the compression spring component, and the shock absorbing rubber against the axial spring characteristics of the suspension bushing 10. The influence of 24 is great. In addition, in the present embodiment, the suspension bush 10 in the vehicle mounting state shown in FIG. 5 has the cushion rubber 24 in contact with the vehicle body 34 in the axial direction even in a stationary state where no vibration is input. The spring of the rubber 24 affects the spring characteristics of the suspension bush 10.

  In the suspension bush 10, the spring of the buffer rubber 24 is easily adjusted, and the spring characteristic in the axial direction of the suspension bush 10 can be tuned with a large degree of freedom.

  That is, in the suspension bush 10, one end (thick part 30) in the axial direction of the cylindrical part 18 of the outer cylinder member 14 is thicker (t1> t2) in the radial direction than the other end (thin part 32). Yes. In particular, the thick portion 30 of the outer cylindrical member 14 has an inner diameter smaller than that of the thin portion 32 (R1 <R2), and the thick portion 30 protrudes toward the inner peripheral side with respect to the thin portion 32 to be thick. Therefore, the protrusion amount from the cylindrical part 18 of the flange part 20 to the outer periphery is ensured to be equal to the conventional one. In this embodiment, the outer diameter dimension of the cylindrical portion 18 is substantially constant over the entire axial direction, and the outer diameter dimensions of the thick portion 30 and the thin portion 32 are substantially the same. .

  As a result, the area of one end surface in the axial direction of the outer cylinder member 14 that supports the shock-absorbing rubber 24 is increased, and the degree of freedom of the shape, size, arrangement, etc. of the shock-absorbing rubber 24 is ensured. Therefore, the degree of freedom in tuning the spring characteristics of the shock absorbing rubber 24 is increased, and the axial spring characteristics of the suspension bushing 10 affected by the compression spring of the shock absorbing rubber 24 are easily adjusted.

  Furthermore, the thick portion 30 is thickened toward the inner peripheral side with respect to the thin portion 32, and the area of one end surface in the axial direction of the outer cylindrical member 14 does not increase the outer diameter of the flange portion 20, Since a large area is secured, the degree of freedom of tuning of the axial spring can be ensured even when the arrangement area of the suspension bush 10 is limited and there is no space on the outer peripheral side. And since it is not necessary to enlarge the protrusion dimension to the outer periphery of the flange part 20, the fall of the load resistance of the flange part 20 is also prevented.

  Further, since the thin portion 32 constituting the other axial end of the cylindrical portion 18 is made thinner than the thick portion 30 and the inner diameter is increased, the rubber volume of the main rubber elastic body 16 is increased. Can be suppressed, and the vibration-proof performance in the radial direction and the twisting direction can be sufficiently ensured.

  Further, since the difference t1-t2 between the thickness dimension t1 of the thick part 30 and the thickness dimension t2 of the thin part 32 is 5 mm or less, it is caused by an extreme dimensional difference between the thick part 30 and the thin part 32. Concentration of stress to be avoided is avoided, and the outer cylinder member 14 is easily manufactured and improved in durability. In addition, since the difference in deformation due to the difference in thickness between the thick portion 30 and the thin portion 32 is reduced during cooling after molding, the resin due to the difference in the thickness of the cylindrical portion 18 in the axial direction. The adverse effect on the moldability is avoided, and the thick portion 30 and the thin portion 32 can each be formed into a predetermined cylindrical shape.

  Furthermore, since the thickness dimension t1 of the thick wall portion 30 is larger than the thickness dimension t3 of the flange portion 20 (t1> t3), the fixing area of the buffer rubber 24 on the axial end surface of the outer cylindrical member 14 is reduced. It is possible to ensure a large value, and to adjust the axial dimension of the buffer rubber 24 and the stopper clearance of the stopper means 42 more greatly. Therefore, the influence of the buffer rubber 24 on the spring characteristics in the axial direction can be adjusted with a greater degree of freedom, and the desired vibration-proof characteristics and durability can be realized advantageously.

  Moreover, since the thickness dimension t1 of the thick-walled portion 30 is not more than three times the thickness dimension t3 of the flange portion 20 (t1 ≦ 3 * t3), the thick-walled portion 30 is extremely different from the flange portion 20. Therefore, the stress concentration caused by the difference in thickness at the connecting portion between the cylindrical portion 18 and the flange portion 20 is alleviated, and cracks and the like are generated at the proximal end of the flange portion 20 and the like. Is prevented.

  Further, the difference R2-R1 in the inner diameter dimension between the thick part 30 and the thin part 32 is smaller than 0.2 times the inner diameter dimension R1 of the thick part 30 (R2-R1 <0.2 * R1). The difference between the thick portion 30 and the thin portion 32 is sufficiently small with respect to the size of the suspension bush 10. Thereby, it is possible to suppress the influence of the thick wall portion 30 provided on the cylindrical portion 18 to which the main rubber elastic body 16 is fixed and protruding toward the inner peripheral side on the vibration isolation characteristics of the suspension bush 10. The anti-vibration performance can be realized without requiring a large tuning change of the spring characteristics.

  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 inner peripheral surface of the cylindrical portion 18 in the outer cylindrical member 14 is configured by the tapered surface 26 over the entire length in the axial direction. The inner diameter dimension and the thickness dimension of the cylindrical portion 18 may change over the entire length in the axial direction.

  Further, the thick portion 30 and the thin portion 32 are not necessarily limited to the structure formed by the tapered surface 26 (tapered portion 28). For example, the cylindrical portion 18 has a stepped cylindrical shape having a step on the inner peripheral surface. Thus, by adopting a structure in which the inner diameter dimension and the thickness dimension change stepwise, one end portion in the axial direction of the cylindrical portion 18 may be thicker than the other end portion.

  Furthermore, it is desirable that the outer peripheral surface of the cylindrical portion 18 has a straight shape in which the radial dimension is substantially constant in the axial direction. For example, a tapered shape in which the outer diameter dimension gradually changes in the axial direction is also employed. Can be done.

  The buffer rubber 24 is preferably integrated with the main rubber elastic body 16 in order to reduce the number of parts. For example, the buffer rubber 24 is formed separately from the main rubber elastic body 16 so as to be buffered. By forming the rubber 24 from a material different from that of the main rubber elastic body 16, the characteristics required for the main rubber elastic body 16 and the characteristics required for the buffer rubber 24 can be advantageously realized.

  The shock absorbing rubber 24 is not necessarily in contact with the inner shaft member 12 side (the vehicle body 34) when the vehicle is mounted, and is separated in a stationary state without vibration input, and the vibration input in the axial direction. You may make it contact | abut sometimes.

  The cylindrical vibration isolator according to the present invention is not necessarily used as a suspension bush, but can be suitably used for an engine mount, a member mount, a differential mount, and the like. Furthermore, the present invention is not only applied to a tubular vibration isolator for automobiles, but can also be applied to a cylindrical vibration isolator used for, for example, a motorcycle, a railway vehicle, an industrial vehicle, and the like. is there.

10: Suspension bush (cylindrical vibration isolator), 12: Inner shaft member, 14: Outer cylinder member, 16: Rubber elastic body, 18: Cylindrical part, 20: Flange part, 26: Tapered surface, 30: Thickness Meat part (straight part), 42: Stopper means

Claims (6)

The inner shaft member is inserted into the cylindrical portion of the outer cylindrical member made of synthetic resin, and the inner shaft member and the outer cylindrical member are elastically connected to each other by the main rubber elastic body. A flange portion extending to the outer periphery is integrally formed at one end portion in the axial direction, and a buffer rubber is fixed to the outer surface in the axial direction of the flange portion, and the inner shaft member and the outer cylinder member are relatively opposite to each other in the axial direction. In the cylindrical vibration damping device in which the stopper means for limiting the amount of displacement is configured by the axial contact between the inner shaft member and the flange portion via the buffer rubber,
The inner diameter dimension of one end portion in the axial direction of the cylindrical portion on which the flange portion is formed is smaller than the inner diameter dimension of the other end portion in the axial direction of the cylindrical portion, and the axis of the cylindrical portion One end portion in the direction is thicker than the other end portion in the axial direction of the tubular portion.   The cylindrical vibration isolator according to claim 1, wherein a difference in thickness between one end in the axial direction and the other end of the cylindrical portion on which the flange portion is formed is 5 mm or less.   One end in the axial direction of the cylindrical portion on which the flange portion is formed is thicker than the flange portion, and the thickness of one end in the axial direction of the cylindrical portion is the flange portion. The cylindrical vibration isolator according to claim 1 or 2, wherein the vibration isolator is 3 times or less.   The difference between the inner diameter dimensions of one end in the axial direction of the cylindrical portion where the flange portion is formed and the other end in the axial direction of the cylindrical portion is the inner diameter of the one end in the axial direction of the cylindrical portion. The cylindrical vibration isolator as described in any one of Claims 1-3 currently made smaller than 0.2 times the dimension.   At least a part of the inner peripheral surface of the cylindrical portion is a tapered surface that gradually increases in diameter from one axial direction of the cylindrical portion on which the flange portion is formed toward the other axial direction of the cylindrical portion. The cylindrical vibration isolator according to any one of claims 1 to 4.   The cylindrical anti-body according to any one of claims 1 to 5, wherein one end portion in the axial direction of the cylindrical portion on which the flange portion is formed is a straight portion having an inner diameter dimension constant in the axial direction. Shaker.

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