JP2008248898A - Cylindrical vibration damper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylindrical vibration damper in which high damping performance with respect to input vibration in the right and left, and front and rear directions of a vehicle is advantageously secured by an easily manufacturable structure. <P>SOLUTION: In the cylindrical vibration damper, a second vibration control bush 12 is integrally assembled to a lower part of a first vibration control bush 10 for absorbing heavy load of heavy goods. The first vibration control bush 10 includes first and second mounting members 14, 16 disposed separated from each other in the vertical direction, and a first rubber elastic body 18 for connecting the first and second mounting members 14, 16, while the second vibration control bush 12 includes inner and outer cylinder members 30, 32 disposed separated from each other in the radial direction, a second rubber elastic body 34 connecting the inner and outer cylinder members 30, 32, a pair of fluid chambers 54, 56 in which a portion of a wall part is composed of the second rubber elastic body 34, and an orifice passage 58 for communicating the pair of fluid chambers 54, 56 with each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cylindrical vibration isolator, and in particular, is interposed between a predetermined heavy object provided in a vehicle and a support part that supports the heavy object from below, and the heavy object is The present invention relates to an improvement of a cylindrical vibration isolator that is elastically vibration-supported with respect to a support portion.

  Conventionally, as a type of vibration isolator as described above, for a heavy object provided in a vehicle, it is attached in a state where it is placed, and an inner cylinder member to which a weight load of the heavy object is input, Around the inner cylinder member, an outer cylinder member that is disposed at a predetermined distance outward in the radial direction and is attached to a support portion that supports a heavy object, and such an inner cylinder member and an outer cylinder member 2. Description of the Related Art There is known a cylindrical vibration isolator including a cylindrical rubber elastic body that is interposed therebetween and connects the inner and outer cylindrical members.

  In such a cylindrical vibration isolator, the inner cylinder member is mounted in a vertically placed state in contact with the heavy object provided on the vehicle at the upper end surface, and the weight load of this heavy object is the inner cylinder member. When the rubber elastic body is elastically deformed, the weight load of the heavy load is absorbed, and in such a state, the vehicle is placed between the heavy load and the support portion. Vibration loads input in the vertical direction (axial direction of the cylindrical vibration isolator), the left and right direction, and the front and rear direction (both radial directions of the cylindrical vibration isolator) are also absorbed based on the elastic deformation of the rubber elastic body. To be able to be. A cylindrical vibration isolator having such a structure is often used, for example, as a cab mount or an engine mount of an automobile.

  In this conventional cylindrical vibration isolator, when the inner cylinder member is vertically installed on a heavy object provided in the vehicle, the rubber elastic body is already in a state before the vibration load is input. It is made into the state elastically deformed by the weight load of the heavy article added to a rubber elastic body via an inner cylinder member. For this reason, if the rubber elastic body has a free surface having a horizontally extending shape, for example, the free surface is already pulled downward before vibration input to the rubber elastic body, resulting in a large tensile strain. As a result, the free surface of the rubber elastic body is further extended by the input of the vibration load, and the durability of the rubber elastic body is lowered. Therefore, in the conventional cylindrical vibration isolator having the above-described structure, in many cases, the rubber elastic body is in a state before the inner cylinder member is attached to the heavy object (a state before the weight load of the heavy object is input). ) Having a free surface having a shape that is inclined or curved upward from one side in the radial direction to the other side, and this free surface is substantially in a state of being attached to a heavy object of the inner cylinder member. The shape extends horizontally, and is configured not to be stretched as much as possible before the vibration input to the rubber elastic body.

  By the way, among these cylindrical vibration isolators, particularly those used as cab mounts for truck-based automobiles, in response to the recent trend toward higher-grade automobiles and the demand for higher running stability, etc. Thus, it may be required that a sufficiently soft spring characteristic is exhibited against the input vibration in the left-right direction and the front-rear direction of the vehicle so that high damping performance against the input vibration can be secured.

  However, as described above, a conventional cylindrical vibration isolator used for a cab mount or the like usually has a relatively simple structure in which an inner cylinder member and an outer cylinder member are simply connected by a rubber elastic body. In the vertical position where the axial direction is the vertical direction, it is only interposed between a heavy object such as an automobile cabin and the support part. At the time of input, a compression force is generated in the rubber elastic body, and a relatively hard spring characteristic is exhibited. For this reason, it has been difficult to obtain a sufficiently high damping performance with respect to the input vibration in the front-rear direction and the left-right direction.

  On the other hand, in addition to the inner cylinder member, the outer cylinder member, and the rubber elastic body that couples them, a part of the wall portion is configured by the rubber elastic body, and the inner cylinder member is sandwiched between both sides. A so-called fluid-filled cylindrical vibration isolator having a pair of fluid chambers in which a predetermined incompressible fluid is provided and an orifice passage that connects the pair of fluid chambers to each other is also generally known. (For example, see Patent Document 1 below). In such a fluid-filled cylindrical vibration isolator, a more effective vibration isolating effect can be obtained based on the resonance action of an incompressible fluid that is caused to flow through the orifice passage when vibration is input. .

  Therefore, in a cylindrical vibration isolator interposed between a heavy load such as a cabin of a truck automobile and a support portion, high damping performance based on sufficiently soft spring characteristics against left and right and front and rear input vibrations is provided. In order to achieve this, the above-described fluid-filled cylindrical vibration isolator is used so that the arrangement direction of the pair of fluid chambers is the left-right direction or the front-rear direction of the vehicle between the heavy object and the support part. In addition, it is conceivable to insert them vertically.

  However, in such a case, as described above, in consideration of the durability of the rubber elastic body and further the entire cylindrical vibration isolator, the free surface of the rubber elastic body is moved upward from one side in the radial direction to the other side. If the shape is inclined or curved, the free surface of the rubber elastic body constituting a part of the wall portion of the fluid chamber inevitably becomes an undercut shape. This causes a new problem that the productivity of the whole mold vibration isolator is significantly lowered.

Japanese Patent Laid-Open No. 8-193639

  Here, the present invention has been made in the background as described above, and the problem to be solved is that a predetermined heavy object provided in the vehicle is supported on the lower side thereof. A new technology that makes it possible to advantageously secure high damping performance against input vibrations in the lateral and longitudinal directions of a vehicle with a structure that is easy to manufacture. It is to provide.

  In the present invention, in order to solve such a problem, the gist of the present invention is between a predetermined heavy object provided on the vehicle and a support part that supports the heavy object from below. An anti-vibration device that is interposed and elastically anti-vibrates and supports the heavy object with respect to the support part, (a-1) attached to the heavy object in a state where the heavy object is placed A first mounting member to which a weight load of the heavy object is input, and (a-2) a cylindrical portion positioned at a predetermined distance below the first mounting member, A second mounting member that is spaced apart from the first mounting member and is mounted on the support; and (a-3) a cylindrical shape that extends in the vertical direction on the same axis as the cylindrical portion of the second mounting member. And having the first mounting member and the second mounting portion interposed between the first mounting member and the second mounting member. And a cylindrical first rubber elastic body that absorbs the weight load by being elastically deformed by inputting the weight load of the heavy object to the first mounting member. And (b-1) positioned below the first mounting member in the first vibration-isolating bush so as to extend in the vertical direction inside the cylindrical portion of the second mounting member. And (b-2) arranged around the inner cylinder member at a predetermined distance radially outwardly in a state of being inserted into the cylinder portion of the second mounting member. (B-3) a second rubber elastic body that is interposed between the inner cylinder member and the outer cylinder member and connects the inner cylinder member and the outer cylinder member; b-4) A part of the wall portion is constituted by the second rubber elastic body and is provided on both sides with the inner cylinder member interposed therebetween. A pair of fluid chambers in which a predetermined incompressible fluid is enclosed, and (b-5) a second vibration isolating bush having an orifice passage communicating the pair of fluid chambers with each other, The outer cylinder member of the second vibration isolation bush is fixed to the cylinder portion of the second attachment member of the first vibration isolation bush so that the outer cylinder member is the second attachment member. In the state before elastic deformation of the first rubber elastic body in the first vibration isolating bush, the inner cylindrical member of the second vibration isolating bush is The first rubber elastic member is positioned below the first mounting member with a predetermined gap from the first mounting member, and the first rubber elasticity is obtained by inputting a weight load of the heavy object to the first mounting member. Under the state of elastic deformation of the body, the inner cylindrical member has its upper end surface facing the first The cylindrical vibration isolator is configured to be brought into contact with an attachment member and attached to the heavy object via the first attachment member.

  In addition, according to one of the preferable embodiments of the cylindrical vibration isolator according to the present invention, the first attachment member is disposed in a direction in which the plate thickness direction is the vertical direction, and the heavy object is disposed on the upper surface. The second mounting member extends integrally outward in the radial direction from the upper end portion of the cylindrical portion, and the lower surface of the first mounting member An outer flange portion disposed opposite to the outer flange portion, and the outer flange portion is attached to the support portion, and the first rubber elastic body is a plate-like first attachment member. Between the lower surface of the first mounting member and the upper surface of the outer flange portion of the second mounting member, and the lower surface of the first mounting member and the upper surface of the outer flange portion are connected.

  Moreover, according to another preferable aspect of the cylindrical vibration isolator according to the present invention, at least one of the mutually opposing portions of the upper surface of the outer flange portion and the lower surface of the first mounting member is provided. A stopper rubber portion formed integrally with the first rubber elastic body is fixed.

  Furthermore, according to one of the desirable aspects of the cylindrical vibration isolator according to the present invention, the first rubber elastic body has a tapered cylindrical shape that gradually decreases in diameter toward the upper side, and the first rubber elastic body has a tapered cylindrical shape on the end surface on the small diameter side. While fixed to one mounting member, it is fixed to the second mounting member at the end face on the large diameter side.

  Furthermore, according to one of the other desirable modes of the cylindrical vibration isolator according to the present invention, the axial spring constant of the first rubber elastic body is the axial spring of the second rubber elastic body. Lower than a constant.

  According to one of the advantageous aspects of the cylindrical vibration isolator according to the present invention, the first rubber elastic body is in a state before elastic deformation between the first mounting member and the inner cylindrical member. The vertical length of the gap formed in the first mounting member is substantially the same as the amount of elastic deformation in the vertical direction of the first rubber elastic body due to the input of the weight load of the heavy object to the first mounting member. It is assumed. The “substantially the same size as the amount of elastic deformation of the rubber elastic body in the vertical direction” here refers to a size that is the same as the amount of elastic deformation, a size slightly larger than that, The one that includes a slightly smaller size.

  Furthermore, according to one of the other preferable aspects of the cylindrical vibration isolator according to the present invention, the inner cylindrical member of the second vibration isolating bush is provided with a stopper protruding inside each of the pair of fluid chambers. A protrusion is provided.

  That is, in the cylindrical vibration isolator according to the present invention, when a vibration load is input in the vertical direction while being interposed between a heavy object provided in the vehicle and the support portion, Both the first rubber elastic body in the anti-vibration bush and the second rubber elastic body in the second anti-vibration bush are elastically deformed in the axial direction so that the vertical vibration load is absorbed. become. In addition, when a vibration load is input in the left-right direction or the front-rear direction, both the first rubber elastic body and the second rubber elastic body are elastically deformed in the radial direction so that the left-right or front-rear vibration is generated. The load will be absorbed.

  In addition, in the cylindrical vibration isolator according to the present invention, when the vibration load in the left-right direction or the front-rear direction is input, the non-sealed sealed in the pair of fluid chambers is accompanied by the elastic deformation in the radial direction of the second rubber elastic body. The compressible fluid is caused to flow between the pair of fluid chambers through the orifice passage, thereby, based on the resonance action or the like of such an incompressible fluid, with respect to the input vibration in the lateral direction or the longitudinal direction, A sufficiently soft spring characteristic can be exhibited.

  In particular, in the cylindrical vibration isolator according to the present invention, the weight load of the heavy object is the first rubber elasticity in the first vibration isolating bush under the interposed state between the heavy object and the support part. It is absorbed by elastic deformation of the body. Therefore, even if the second rubber elastic body in the second vibration-proof bushing is elastically deformed by the weight load of such a heavy load, or even if it is elastically deformed, the amount of elastic deformation is It can be made as small as possible.

  Therefore, in such a cylindrical vibration isolator, the free surface of the second rubber elastic body is directed from one side in the radial direction to the other side only in a state of being attached between the heavy object and the support part. For example, even if it is a shape that extends horizontally and is easy to punch out, it is pulled downward at the time before the input of the vibration load without being an upwardly inclined or curved undercut shape. It can be advantageously avoided that the stretched state is caused by a large tensile strain. As a result, a second rubber elastic body that can effectively prevent a decrease in durability due to a large tensile strain generated before vibration input can be formed with a shape that is easy to manufacture.

  Therefore, in the cylindrical vibration isolator according to the present invention as described above, the use form in which a predetermined heavy object provided in the vehicle is elastically anti-vibrated and supported with respect to the support portion disposed on the lower side. Therefore, high damping performance against input vibrations in the left-right direction and the front-rear direction of the vehicle can be ensured extremely advantageously with a structure that can be easily manufactured.

  Hereinafter, in order to clarify the present invention more specifically, an embodiment of the present invention will be described in detail with reference to the drawings.

  First, FIG. 1 schematically shows a cab mount for a truck-type automobile as an embodiment of a cylindrical vibration isolator having a structure according to the present invention in a longitudinal sectional form. As is clear from FIG. 1, the cab mount of this embodiment has a first anti-vibration bush 10 and a second anti-vibration bush 12, which are vertically moved with the former as the upper side in FIG. It is configured as an integrally assembled product that is integrally assembled in a state aligned in the direction (axial direction). And it mounts | wears with the truck system vehicle in the state interposed in the vertical position by which an axial direction becomes an up-down direction between a cabin and a flame | frame. Hereinafter, for the sake of convenience, the side of the first anti-vibration bush 10 will be referred to as the upper side or the upper side, and the side of the second anti-vibration bush 12 will be referred to as the lower side or the lower side.

  More specifically, the first anti-vibration bush 10 includes an upper mounting bracket 14 as a first mounting member and a second mounting bracket disposed below the upper mounting bracket 14 at a predetermined distance. And the upper mounting bracket 14 and the lower mounting bracket 16 are elastic with a first rubber elastic body 18 interposed between the both mounting brackets 14 and 16. It is set as the structure formed by connecting them.

  The upper mounting bracket 14 is made of a circular metal plate having a predetermined thickness. And in this upper side attachment metal fitting 14, the bolt penetration hole 20 is pierced in the center part so that this center part may be penetrated. Further, the upper surface of the vehicle is mounted on a mounting surface 15 on which a cabin of a truck vehicle is mounted via a predetermined bracket (not shown). The weight load of the cabin is input to the mounting surface 15 of the upper mounting bracket 14 in a state where the cab mount of the present embodiment is interposed vertically between the cabin and the frame of the truck automobile. It is like that.

  The lower mounting bracket 16 is constituted by a cylindrical bracket having a cylindrical portion 22 and an outer flange portion 24 that is integrally provided around one axial end portion of the cylindrical portion 22. The cylindrical portion 22 has a cylindrical overall shape having a predetermined height and substantially the same thickness as the upper mounting bracket 14, and the inner diameter thereof is larger than that of the bolt insertion hole 20 of the upper mounting bracket 14. Is sufficiently large, and the outer diameter is smaller than the outer diameter of the upper mounting bracket 14 by a predetermined dimension.

  The outer flange portion 24 has substantially the same thickness as the cylindrical portion 22, protrudes radially outward from one end portion of the cylindrical portion 22, and continuously extends in the circumferential direction. It has an outer diameter larger than the outer diameter of the plate-like upper mounting bracket 14 by a predetermined dimension. In addition, T-shaped fixing bolts 26 are respectively provided at a plurality of locations on the circumference of the outer flange portion 24 so that the head portion is exposed on the upper surface of the outer flange portion 24 and the leg portions are on the lower surface side. In a protruding state, it is mounted so that it cannot move and cannot rotate.

  In this case, the lower mounting bracket 16 is opened below the upper mounting bracket 14 positioned so as to spread in the horizontal direction, and the end opening on the formation side of the outer flange portion 24 is opened upward. However, it is coaxially arranged so as to extend in the vertical direction (vertical direction) with a predetermined distance from the upper mounting bracket 14. Thus, the outer flange portion 24 is positioned below the upper mounting bracket 14 with the inner peripheral side portion of the upper surface facing the outer peripheral side portion of the lower surface of the upper mounting bracket 14 with a predetermined distance therebetween. I'm hurt.

  On the other hand, the first rubber elastic body 18 interposed between the upper mounting bracket 14 and the lower mounting bracket 16 has a lower surface of the upper mounting bracket 14 and an outer flange portion 24 of the lower mounting bracket 16. The overall shape of the substantially cylindrical shape which has the same height dimension as the distance between the upper surfaces of each other is exhibited.

  The lower mounting bracket 16 has a cylindrical inner peripheral surface that has an inner diameter substantially the same as the inner diameter of the cylindrical portion 22 and extends straight in the axial direction, and a tapered cylindrical outer peripheral surface that gradually decreases in diameter upward. is doing. In addition, the outer peripheral surface has a maximum outer diameter on the lower end side that is larger by a predetermined dimension than the outer diameter of the upper mounting bracket 14 and smaller by a predetermined dimension than the outer diameter of the outer flange portion 24 of the lower mounting bracket 16. Further, the minimum outer diameter on the upper end side is smaller than the outer diameter of the upper mounting bracket 14 by a predetermined dimension. Accordingly, the first rubber elastic body 18 gradually bulges outward in the radial direction as it goes downward, so that the thickness is gradually increased.

  Further, here, the lower thick portion of the first rubber elastic body 18 is a stopper rubber portion 28 fixed to the outer flange portion 24 of the lower mounting bracket 16. Further, the stopper rubber portion 28 covers the entire head portion of the fixing bolt 26 attached to the outer flange portion 24. That is, the head of the fixing bolt 26 is embedded in the stopper rubber portion 28.

  The first rubber elastic body 18 is disposed between the lower metal fittings 14, 16 between the lower surface of the upper mounting bracket 14 and the upper surface of the outer flange portion 24 of the lower mounting bracket 16 that are spaced apart in the vertical direction. On the same axis, they are interposed so as to extend straight in the vertical direction (vertical direction). In such a state, the upper end surface is integrally fixed to the lower surface of the upper mounting bracket 14 by vulcanization adhesion, while the lower end surface is fixed to the upper surface of the outer flange portion 24 of the lower mounting bracket 16. On the other hand, it is integrally fixed by vulcanization adhesion. In other words, the first rubber elastic body 18 having a cylindrical shape as a whole is integrally formed by vulcanizing and bonding the upper mounting bracket 14 on the upper end surface and the lower mounting bracket 16 on the lower end surface thereof. It is composed of vulcanized molded products. Further, in such an integrally vulcanized molded product, the stopper rubber portion 28 formed of a thick portion on the lower side of the first rubber elastic body 18 is the first rubber elastic body 18 of the upper mounting bracket 14. Is positioned vertically below the outer peripheral edge portion where it is not fixed.

  Thus, the first vibration isolating bush 10 is formed by integrally connecting the upper mounting bracket 14 and the lower mounting bracket 16 that are coaxially spaced apart in the vertical direction by the first rubber elastic body 18. It is configured as an integral product.

  On the other hand, as shown in FIGS. 1 and 2, the second vibration isolating bush 12 disposed below the first vibration isolating bush 10 having the structure as described above is straight in the vertical direction (vertical direction). And an outer cylinder member 32 as an outer cylinder member disposed coaxially around the inner cylinder member 30 with a predetermined distance therebetween in the radial direction. The inner cylinder fitting 30 and the outer cylinder fitting 32 are elastically connected by a second rubber elastic body 34 interposed between the two fittings 30 and 32. ing.

  More specifically, the inner cylinder fitting 30 has a small-diameter cylindrical shape that is thicker than the upper and lower attachment fittings 14 and 16 in the first vibration-proof bushing 10. The inner diameter is approximately the same as the inner diameter of the bolt insertion hole 20 of the upper mounting bracket 14, and its height (axial length) is greater than the height of the cylindrical portion 22 of the lower mounting bracket 16. Also, the size is increased by a predetermined dimension.

  Further, an intermediate sleeve 36 is coaxially disposed around the inner cylindrical metal fitting 30 at a predetermined distance radially outward. The intermediate sleeve 36 has a height that is a predetermined dimension higher than the height of the cylindrical portion 22 of the lower mounting bracket and lower than the inner cylindrical bracket 30, an outer diameter that is slightly smaller than the inner diameter of the cylindrical portion 22, and its thickness. It has a cylindrical shape with a thinner wall thickness. And in the two axially opposed portions of the intermediate sleeve 36 in the radial direction, the first window portion 38 and the second window portion having a substantially rectangular shape extending in the circumferential direction with a length of less than a half circumference. 40 are formed. Moreover, between the edge part of the circumferential direction both sides of these 1st window parts 38 and the 2nd window parts 40, respectively, the shallow groove | channel 42a extended in the circumferential direction and connecting those window parts 38 and 40, 42b is formed.

  Further, a second rubber elastic body 34 is interposed between the inner cylindrical fitting 30 and the intermediate sleeve 36. The second rubber elastic body 34 has a substantially large-diameter thick cylindrical shape, and the inner cylinder fitting 30 is attached to the inner peripheral surface, and the intermediate sleeve 36 is bonded to the outer peripheral surface by vulcanization. It is considered to be an integrally vulcanized molded product. In this integrally vulcanized molded product, both end portions in the axial direction of the inner cylindrical metal fitting 30 are formed from both end surfaces in the axial direction of the cylindrical second rubber elastic body 34 and both opening portions in the axial direction of the intermediate sleeve 36. , And project outward in the axial direction (vertical direction). The second rubber elastic body 34 is thicker than the first rubber elastic body 18, so that the axial spring constant of the second rubber elastic body 34 is the first rubber elastic body 34. The rubber elastic body 18 is set to have a size larger than the spring constant in the axial direction. In other words, the spring constant in the axial direction of the first rubber elastic body 18 is set lower than the spring constant in the axial direction of the second rubber elastic body 34.

  In the second rubber elastic body 34, both end surfaces 43a and 43b in the axial direction (vertical direction) are flat surfaces extending in a substantially horizontal direction or concave surfaces in which the central portion is slightly recessed. Yes. In addition, a first pocket portion 44 and a second pocket portion 46 that are open on the outer peripheral surface are formed at two locations corresponding to the radial direction in the central portion in the axial direction. An opening is formed on the outer peripheral surface of the intermediate sleeve 36 through a first window portion 38 and a second window portion 40 provided in the inner sleeve 36. Further, in each of the first and second pocket portions 44, 46, the upper inner peripheral surface portion 48a and the lower inner peripheral surface portion 48b which are opposed to each other in the vertical direction of the inner peripheral surface are substantially horizontal. It is a flat surface that spreads out.

  Further, the second rubber elastic body 34 is filled in the shallow concave grooves 42a and 42b of the intermediate sleeve 36, respectively, and is sealed to the bottom surfaces of the concave grooves 42a and 42b. 50 integrally. A circumferential groove 52 continuously extending in the circumferential direction of the seal rubber portion 50 is provided at the center in the width direction of the concave groove 42a (the axial direction of the intermediate sleeve 36) in one of the two seal rubber portions 50. Has a sufficiently narrow width and a depth reaching the bottom surface of the concave groove 42a (the outer peripheral surface of the intermediate sleeve 36) so as to open on the outer peripheral surface of the seal rubber portion 50 (the radially outer side of the intermediate sleeve 36). To be opened).

  Further, in the circumferential groove 52, the seal rubber portion 50 is continuously extended over the entire length in the circumferential direction. As a result, at both side end portions in the length direction, the two openings 38 and 40 of the intermediate sleeve 36 connected by the concave groove 42a in which the seal rubber portion 50 is provided are opened. , 40 through the first and second pocket portions 44, 46 of the second rubber elastic body 34 that opens on the outer peripheral surface of the intermediate sleeve 36. Thus, the first and second pocket portions 44 and 46 are communicated with each other through the circumferential groove 52.

  The outer cylinder fitting 32 is extrapolated to such an integrally vulcanized molded product in which the intermediate sleeve 36 is vulcanized and bonded to the second rubber elastic body 34, for example, by eight-way drawing or the like. The diameter is reduced, and the intermediate sleeve 36 is fitted and fixed to the outer peripheral surface. Further, under such a fixed state, both end portions in the axial direction of the outer cylinder fitting 32 are, for example, roll-caulked to be respectively engaged with both end surfaces in the axial direction of the intermediate sleeve 36, and further, the inner cylinder Ends on both sides in the axial direction of the metal fitting 30 are protruded outward in the axial direction from openings on both sides in the axial direction of the outer cylinder metal fitting 32, respectively.

  Thus, the opening of the first and second pocket portions 44 and 46 and the opening of the circumferential groove 52 are covered with the outer cylinder fitting 32 in a fluid-tight manner. As a result, the first fluid chamber 54 and the second fluid chamber 56 having the second rubber elastic body 34 as a part of the wall portion are provided on both sides in the radial direction with the inner cylinder fitting 30 interposed therebetween. Further, an orifice passage 58 is formed between the first fluid chamber 54 and the second fluid chamber 56 so as to communicate the fluid chambers 54 and 56. A predetermined incompressible fluid is sealed in each of the first fluid chamber 54, the second fluid chamber 56, and the orifice passage 58. In addition, although water, alkylene glycol, polyalkylene glycol, silicone oil, etc. are adopted as such a sealed fluid, in order to advantageously obtain a vibration isolation effect based on the resonance action of the fluid described later, in this embodiment, A low viscosity fluid of 0.1 Pa · s or less is suitably employed.

  In addition, a stopper is provided between the portion located in the first fluid chamber 54 and the portion located in the second fluid chamber 56 in the inner tubular fitting 30 located between the two fluid chambers 54, 56. The protrusions 60 are integrally provided so as to protrude into the fluid chambers 54 and 56, respectively. The stopper protrusion 60 has a rectangular block shape, and the upper and lower inner peripheral surface portions 48 a and 48 b of the second rubber elastic body 34 and the fluid chambers 54 and 56 are formed in the fluid chambers 54 and 56. With respect to the inner peripheral surface portion of the outer cylindrical metal member 32 that closes the tube, the axial direction and the radial direction are positioned at a predetermined distance from each other. Here, for example, the stopper protrusion 60 is integrally formed with the inner cylinder fitting 30 by insert molding using a highly rigid synthetic resin material. Using a highly rigid synthetic resin material or metal material, the stopper protrusion 60 is formed separately from the inner cylinder fitting 30 and is integrally joined to the inner cylinder fitting 30 by welding or bonding. May be. Further, the inner cylinder fitting 30 and the stopper projection 60 can be integrally formed by casting using an aluminum alloy material or the like.

  In addition, a recess 62 having a predetermined depth and a rectangular cross section is long at the center in the width direction (the axial direction of the inner tube 30 and the vertical direction in FIG. 1) of the front end surface of each stopper protrusion 60. It is formed with a groove shape extending continuously in the vertical direction (the circumferential direction of the inner cylinder fitting 30). A shock absorbing rubber portion 64 having a rectangular cross section is integrally fixed to the bottom portion of such a recess 62 with a protrusion shape extending continuously in the extending direction of the recess 62. The height of the shock absorbing rubber portion 64 is larger than the depth of the recess 62 by a predetermined dimension, and the tip end surface thereof is in the radial direction with respect to the inner peripheral surface portion of the outer cylinder fitting 32. It is positioned at a predetermined distance. Also, a covering rubber layer 66 covering substantially the entire surface is provided on four side faces respectively facing in the thickness direction of the stopper projection 60 (in the axial direction of the inner cylinder fitting 30, the vertical direction in FIG. 1) and the width direction. The second rubber elastic body 34 is integrally formed.

  The outer cylinder fitting 32 of the second vibration isolating bush 12 is press-fitted into the cylinder portion 22 of the lower mounting fitting 16 in the first vibration isolating bush 10 and fixed. As a result, the first anti-vibration bush 10 and the second anti-vibration bush 12 are integrally assembled with each other in a state where they are positioned coaxially in the vertical direction with the former facing upward. Thus, the cab mount according to the present embodiment, which is an integrally assembled product of the first anti-vibration bush 10 and the second anti-vibration bush 12, is configured.

  Further, here, in the assembled state of the first anti-vibration bush 10 and the second anti-vibration bush 12, both end portions in the axial direction of the inner cylindrical fitting 30 of the second anti-vibration bush 12 are on the lower side. An end surface (upper surface) of the upper end portion that protrudes upward from the cylindrical portion 22 of the inner cylindrical fitting 30 is protruded from the both axial opening portions of the cylindrical portion 22 of the mounting bracket 16 in the axially outward direction (vertical direction). 1 is opposed to the lower surface of the upper mounting bracket 14 of the first vibration isolating bush 10 with a gap 68 having a size indicated by L in FIG. In other words, in the cab mount of the present embodiment, the upper side in the state before being mounted on the truck vehicle, that is, before the gravity load of the cabin of the truck vehicle is input to the mounting surface 15 of the upper mounting bracket 14. The lower surface of the mounting bracket 14 and the upper end surface of the inner cylindrical bracket 30 are opposed to each other with a predetermined distance L.

  When the cab mount of the present embodiment having such a structure is attached to a truck vehicle, as shown in FIG. 3, the cylinder of the lower mounting bracket 16 of the first vibration isolating bush 10 is used. The insertion hole 72 formed in the plate-like support portion 70 provided in the frame (not shown) of the truck automobile is formed by the portion 22 and the second vibration-proof bushing 12 press-fitted into the cylindrical portion 22. The outer flange portion 24 of the lower mounting bracket 16 is placed and supported on the periphery of the opening of the insertion hole 72 on the upper surface of the support portion 70 in a state of being inserted into the inside. Further, under this support state, the fixing bolt 26 attached to the outer flange portion 24 is inserted into the attachment hole 74 formed in the support portion 70 and is fastened and fixed by the nut 76. Accordingly, the first vibration isolating bush 10 is directly attached to the support portion 70 by the lower mounting bracket 16, and the second vibration isolating bush 12 is disposed via the lower mounting bracket 16. The cab mount is attached to and supported by the support portion 70. Here, the first fluid chamber 54 and the second fluid chamber 56 are respectively positioned in the left-right direction of the vehicle body under the state of support to the support portion 70 of the cab mount.

  Further, in this way, the entire cab mount is supported by the support portion 70, while a truck automobile cabin (not shown) is mounted on the mounting surface 15 of the upper mounting bracket 14 of the first vibration isolating bush 10. It is mounted via a mounting bracket 78 provided on it. At this time, the weight load of the cabin is input to the first rubber elastic body 18 via the upper mounting bracket 14 and the first rubber elastic body 18 is elastically compressed and deformed. Accordingly, the weight load of the cabin is absorbed based on the elastic deformation of the first rubber elastic body 18.

  Also, here, the amount of deformation (deformation stroke) when the first rubber elastic body 18 is compressed and deformed by the input of the weight load of the cabin is such that the size of the cab mount before mounting on the truck vehicle ( The size of the gap 68 between the lower surface of the upper mounting bracket 14 and the upper end surface of the inner cylindrical bracket 30 (before elastic deformation of the first rubber elastic body 18) is equal to or slightly larger than L Or slightly smaller than that. That is, the amount of elastic deformation of the first rubber elastic body 18 at the time of inputting the weight load of the cabin is the size of the gap 68 between the lower surface of the upper mounting bracket 14 and the upper end surface of the inner cylindrical bracket 30: L The size is substantially the same. Therefore, as described above, when the cab mount is supported by the support portion 70 and the cabin is placed on the mounting surface 15 of the upper mounting bracket 14, the gap 68 is substantially lost, and the upper mounting bracket is removed. The lower surface of 14 and the upper end surface of the inner cylinder fitting 30 are brought into contact with each other.

  In such a state, the mounting bolt 80 is inserted into the inner cylindrical metal fitting 30 from the lower opening thereof, and the tip portion is provided in the bolt insertion hole 20 and the mounting bracket 78 of the upper mounting metal fitting 14. Through the through-hole 82 formed, it is arranged so as to protrude upward from the mounting surface 15 of the upper mounting bracket 14, and a nut 83 is screwed to the tip portion thereof. Accordingly, the first vibration isolating bush 10 is directly attached to the cabin mounting bracket 78 by the upper mounting bracket 14, and the second vibration isolating bush 12 is disposed via the upper mounting bracket 14. Attached to the mounting bracket 78, the entire cab mount is attached to the mounting bracket 78. Here, the rebound stopper 84 is attached to the lower end of the inner tubular fitting 30 in the second vibration-proof bushing 12 in such a state that the cab mount is attached to the attachment bracket 78. The rebound stopper 84 has a known structure in which a ring-shaped stopper rubber portion 88 is fixed to the outer peripheral portion of the upper surface of the disk-shaped stopper fitting 86, and the stopper rubber portion 88 is connected to the outer cylinder fitting 32. It is made to oppose with respect to each lower end surface of the cylinder part 22 of the lower side mounting bracket 16 at predetermined distance.

  Thus, in the cab mount of the present embodiment, the cab mount is mounted between the cabin (mounting bracket 78) and the frame (supporting portion 70) and mounted on the truck vehicle. Further, under such intervention, the weight load of the cabin is absorbed by the elastic deformation of the first rubber elastic body 18 in the first vibration isolating bush 10, and the second rubber elasticity in the second vibration isolating bush 12. The input of the weight load of the cabin to the body 34 is avoided as much as possible. Thus, the second rubber elastic body 34 is configured not to be elastically deformed as much as possible in a state where no vibration load is input between the cabin and the frame.

  In such a cab mount, when a vibration load is input in the vertical direction (axial direction) between the cabin and the frame in a state where the cab mount is mounted on the truck vehicle, Both of the second rubber elastic bodies 34 are elastically deformed in the axial direction. At that time, as described above, since the spring constant in the axial direction of the first rubber elastic body 18 is smaller than the spring constant in the axial direction of the second rubber elastic body 34, the vibration load in the vertical direction is It can be absorbed mainly based on the elastic deformation of the second rubber elastic body 34. Thereby, the damping performance of the vibration load in the vertical direction can be tuned relatively easily based on substantially only the spring constant of the second rubber elastic body 34.

  On the other hand, when a vibration load is input between the cabin and the frame in the front-rear, left-right direction, particularly in the left-right direction, both the first rubber elastic body 18 and the second rubber elastic body 34 are elastic in the radial direction. In addition to the deformation, the elastic deformation of the second rubber elastic body 34 causes a fluid flow through the orifice passage 58 between the first fluid chamber 54 and the second fluid chamber 56. Thus, a soft spring characteristic based on a fluid action such as a resonance action of the fluid is exhibited, and a high damping performance against the input vibration in the left-right direction can be ensured.

  In addition, here, the thicker portion on the lower side of the first rubber elastic body 18 is used as a stopper rubber portion 28, and is opposed to the lower portion of the outer peripheral portion of the upper mounting bracket 14. Further, a rebound stopper 84 having a stopper rubber portion 88 fixed to the upper surface of the stopper fitting 86 is attached to the lower end of the inner cylinder fitting 30 of the second vibration isolating bush 12. As a result, when an excessive vibration load downward is input between the cabin and the frame, the outer peripheral portion of the upper mounting bracket 14 is brought into contact with the lower mounting bracket 16 via the stopper rubber portion 28. The upper mounting bracket 14 is prevented from being excessively displaced relative to the lower mounting bracket 16 in the downward direction. Further, when an excessive vibration load upward is input between the cabin and the frame, the stopper fitting 86 fixed to the inner cylinder fitting 30 is connected to the cylinder portion of the lower mounting fitting 16 via the stopper rubber portion 88. 22 and the lower end surface of the outer cylindrical fitting 32 are brought into contact with each other, and the inner cylindrical fitting 30 is displaced excessively relative to the lower mounting bracket 16 and the outer cylindrical fitting 32 in the upward direction. It has been stopped. Thus, in the present embodiment, the durability of the first rubber elastic body 18 and the second rubber elastic body 34 can be advantageously improved.

  Furthermore, since the stopper projections 60 are respectively provided in the inner cylindrical metal fitting 30 portions located in the first and second fluid chambers 54 and 56, respectively, the overload in the left-right direction is excessive between the cabin and the frame. When a strong vibration load is input, each stopper projection 60 is brought into contact with the inner peripheral surface of the outer cylinder fitting 32, so that the inner cylinder fitting 30 is relative to the outer cylinder fitting 32 in the left-right direction. Therefore, the excessive displacement is prevented. This also advantageously improves the durability of the second rubber elastic body 34.

  As described above, in the cab mount of the present embodiment, the weight load of the cabin is the first in the state of being mounted between the cabin and the frame with respect to the truck vehicle. The vibration isolation bush 10 absorbs the vibrations in the vertical and horizontal directions between the cabin and the frame, mainly absorbed by the second vibration isolation bush 12, Further, higher damping performance can be secured based on the resonance action of the incompressible fluid that is caused to flow through the orifice passage 58 with respect to the input vibration in the left-right direction.

  Moreover, in this embodiment, the weight load of the cabin is absorbed by the first vibration isolating bush 10 so that the weight load is not input to the second vibration isolating bush 12 as much as possible. It has become. As a result, it is possible to avoid as much as possible that the second rubber elastic body 34 in the second vibration-proof bushing 12 is elastically deformed by the weight load of the cabin.

  Therefore, in the present embodiment, the upper and lower surfaces serving as the free surfaces of the second rubber elastic body 34 under the condition that they are interposed between the cabin and the frame support portion and only attached to the truck-based vehicle. Both end surfaces 43a and 43b and upper and lower inner peripheral surface portions 48a and 48b have almost the same shape as before mounting on a truck-based vehicle, that is, a flat surface extending in the horizontal direction or a concave surface slightly recessed. Can be maintained. Thus, unlike the case where only the vibration isolator having the same structure as that of the second vibration isolating bush 12 is merely interposed between the cabin and the frame support portion, the input of the vibration load is performed. At the previous time, the upper and lower end faces 43a, 43b and the upper and lower inner peripheral surface portions 48a, 48b of the second rubber elastic body 34 are stretched by a large tensile strain due to the weight load of the cabin. The situation can be advantageously avoided. Therefore, for the purpose of avoiding such an extended state, for example, the second rubber elastic body 34 is a free surface having an undercut shape that is inclined or curved upward from one side in the radial direction to the other side. The need to mold in difficult to manufacture shapes with can be advantageously eliminated.

  Therefore, in the cab mount according to the present embodiment, in the usage mode in which the cab mount is interposed between the cabin and the frame and is mounted on the truck vehicle, the input vibration between the cabin and the frame is further increased. Excellent vibration-proof performance can be ensured extremely advantageously with a structure that is easy to manufacture.

  In such a cab mount, the cylindrical first rubber elastic body 18 is provided between the lower surface of the plate-like upper mounting bracket 14 and the upper surface of the outer flange portion 24 integrally formed with the lower mounting bracket 16. The weight of the cabin is absorbed by the elastic compression deformation of the first rubber elastic body 18 by connecting the two mounting brackets 14 and 16 to each other. Therefore, a large weight load of the cabin can be more reliably absorbed by the first rubber elastic body 18.

  Furthermore, in the present embodiment, the amount of deformation (deformation stroke) when the first rubber elastic body 18 is compressed and deformed by the input of the weight load of the cabin is such that the cab mount truck vehicle is Before mounting (before elastic deformation of the first rubber elastic body 18), the size of the gap 68 between the lower surface of the upper mounting bracket 14 and the upper end surface of the inner cylindrical bracket 30 is substantially the same as L. Thus, when the cab mount is supported by the support portion 70 and the cabin is placed on the mounting surface 15 of the upper mounting bracket 14, the lower surface of the upper mounting bracket 14 and the upper end surface of the inner cylindrical bracket 30 are Can be brought into contact with each other. Therefore, the second rubber elastic body 34 can be more advantageously and reliably prevented from being elastically deformed by the weight load of the cabin.

  As mentioned above, although one Embodiment of this invention was explained in full detail, this is an illustration to the last, Comprising: This invention is not limited at all by the specific description regarding this Embodiment.

  For example, as long as the 1st rubber elastic body 18 exhibits a cylindrical shape, the specific shape is not specifically limited. Therefore, for example, as shown in FIG. 4, the first rubber elastic body 18 has a tapered surface in which both the inner peripheral surface and the outer peripheral surface gradually decrease in diameter upward, and gradually decreases in diameter upward. It is good also as a taper cylinder shape to change. In this case, for example, the first rubber elastic body 18 having a tapered cylindrical shape is fixed to the lower surface of the upper mounting bracket 14 on the upper end surface on the small diameter side, and the lower mounting bracket on the lower end surface on the large diameter side. The upper and lower mounting brackets 14 and 16 are connected to each other by being fixed to the upper surface of the 16 outer flange portions 24. In the present embodiment, the first rubber elastic body 18 has a disk-like portion that integrally extends laterally from the large-diameter end and is fixed to the outer flange portion 24 of the lower mounting bracket 16. The disk-shaped portions that integrally extend laterally from the end portion on the small diameter side and are fixed to the outer peripheral portion of the lower surface of the upper mounting bracket 14 are respectively configured as stopper rubber portions 28.

  According to such a structure, when a vertical vibration load is input between the upper mounting bracket 14 and the lower mounting bracket 16, the first rubber elastic body 18 is elastic in the axial direction. The spring constant in the axial direction can be advantageously set lower than that which can be elastically compressed and deformed in the axial direction. Accordingly, it is possible to easily prevent the axial spring characteristics of the first rubber elastic body 18 from significantly affecting the axial spring characteristics of the second rubber elastic body 34. As a result, the damping performance of the vibration load in the vertical direction can be tuned more easily based substantially only on the spring constant of the second rubber elastic body 34. For the present embodiment shown in FIG. 4, members and parts having the same structure as in the previous embodiment are denoted by the same reference numerals as in FIGS. 1 and 2, and detailed description thereof is omitted. .

  Further, the connection structure between the first mounting member and the second mounting member by the first rubber elastic body is not particularly limited to the illustrated one. For example, the first mounting member having a small diameter is integrally provided on the first mounting member, while the second mounting member has a predetermined distance outward in the radial direction around the first mounting tube portion. A large-diameter second mounting cylinder portion disposed separately is integrally provided, and a cylindrical first tube portion is provided between the outer peripheral surface of the first mounting cylinder portion and the inner peripheral surface of the second mounting cylinder portion. It is also possible to connect the first and second mounting tube portions with the first rubber elastic body by interposing one rubber elastic body.

  According to such a structure, when a vertical vibration load is input between the first mounting member and the second mounting member, the first rubber elastic body is elastically sheared in the axial direction. The axial spring constant can be set even more advantageously lower than that which can only be deformed and thereby elastically compressively deformed in the axial direction. As a result, the damping performance of the vibration load in the vertical direction can be more easily tuned based on substantially only the spring constant of the second rubber elastic body.

  Further, in the embodiment, the two fluid chambers 54 and 56 provided in the second vibration isolating bush 12 are positioned in the left and right direction of the vehicle body, so that the second vibration isolating bush 12 inputs the left and right direction. Although high damping performance against vibration was obtained, for example, if these two fluid chambers 54 and 56 are positioned in the front-rear direction of the vehicle body, the second vibration-isolating bush 12 causes the input vibration in the front-rear direction. High attenuation performance with respect to can be obtained.

  Further, as described above, the shapes of the first mounting member and the second mounting member can also be various shapes other than those illustrated.

  Further, various known structures can be adopted as the structure of the orifice passage 58 of the second vibration-proof bushing 12. For example, the intermediate sleeve 36 is vulcanized and bonded to the second rubber elastic body 34. It is also possible to form the orifice passage 58 in the second vibration-proof bushing 12 by assembling an orifice member separate from the integrally vulcanized molded product.

  Furthermore, the attachment structure of the first and second attachment members to the heavy load (cabin) and the support portion can be changed as appropriate.

  In addition, in the said embodiment, although the specific example of what applied this invention to the cab mount for truck-type cars was shown, this invention is other than the cylinder type vibration isolator for automobiles other than this cab mount, and a motor vehicle. Of course, the present invention can be advantageously applied to any of the cylindrical vibration damping devices mounted on the vehicle.

  In addition, although not enumerated one by one, the present invention can be carried out in an embodiment to which various changes, modifications, improvements, etc. are added based on the knowledge of those skilled in the art. It goes without saying that all are included in the scope of the present invention without departing from the spirit of the present invention.

It is longitudinal cross-sectional explanatory drawing which shows one Embodiment of the cylindrical vibration isolator which has a structure according to this invention, Comprising: It is a figure equivalent to the II cross section in FIG. It is II-II sectional explanatory drawing in FIG. It is explanatory drawing which shows the state which attached the cylindrical vibration isolator shown in FIG. 1 to the truck type | system | group automobile. It is a figure corresponding to FIG. 1 which shows another example of the cylindrical vibration isolator which has a structure according to this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 1st anti-vibration bushing 12 2nd anti-vibration bushing 14 Upper mounting bracket 16 Lower mounting bracket 18 First rubber elastic body 22 Cylinder part 24 Outer flange part 30 Inner cylinder fitting 32 Outer cylinder fitting 34 Second rubber Elastic body 36 Intermediate sleeve 54 First fluid chamber 56 Second fluid chamber 58 Orifice passage 68 Gap 70 Support portion 78 Mounting bracket

Claims (7)

Anti-vibration is interposed between a predetermined heavy object provided in the vehicle and a support part that supports the heavy object from below, and elastically supports the heavy object with respect to the support part. A device,
(A-1) a first attachment member that is attached to the heavy load and receives a weight load of the heavy load in a state where the heavy load is placed; and (a-2) the first load member. A second mounting member having a cylindrical portion positioned at a predetermined distance below the mounting member and spaced from the first mounting member and mounted on the support; (a-3) The second mounting member has a cylindrical shape that extends in the vertical direction on the same axis as the cylindrical portion, and is interposed between the first mounting member and the second mounting member. The first mounting member and the second mounting member are connected and elastically deformed by inputting the weight load of the heavy object to the first mounting member, thereby absorbing the weight load. A first anti-vibration bush comprising a rubber elastic body;
(B-1) An inner cylinder member that is positioned below the first attachment member in the first vibration-isolating bush so as to extend in the vertical direction inside the cylinder part of the second attachment member; (B-2) An outer cylinder member disposed around the inner cylinder member with a predetermined distance therebetween in the radial direction in a state of being inserted into the cylinder portion of the second mounting member, (B-3) a second rubber elastic body interposed between the inner cylinder member and the outer cylinder member to connect the inner cylinder member and the outer cylinder member; and (b-4) the first A pair of fluid chambers in which a part of the wall portion is constituted by two rubber elastic bodies and provided on both sides of the inner cylinder member between which a predetermined incompressible fluid is sealed; and (b -5) a second anti-vibration bush having an orifice passage communicating the pair of fluid chambers with each other;
And the second anti-vibration bushing is fixed to the cylindrical portion of the second mounting member in the first anti-vibration bush, The first vibration isolation bush is integrally assembled, and the outer cylinder member is attached to the support portion via the second attachment member, and further, the first vibration isolation bush in the first vibration isolation bush In a state before the elastic deformation of the first rubber elastic body, the inner cylindrical member of the second vibration-proof bushing is separated from the first mounting member by a predetermined gap below the first mounting member. While the first rubber elastic body is in an elastically deformed state due to the input of the weight load of the heavy object to the first mounting member, the inner cylindrical member has its upper end face on the first mounting member. The heavy object through the first mounting member. Cylindrical vibration damping device, characterized by being configured as vignetting.   While the first mounting member is arranged in a plate-like body on which the weight is placed on the upper surface, the second mounting member is arranged in an orientation with the plate thickness direction as the vertical direction, The outer flange portion that extends integrally outward in the radial direction from the upper end portion of the cylindrical portion and is disposed opposite to the lower surface of the first mounting member, is attached to the support portion at the outer flange portion Furthermore, the first rubber elastic body is interposed between the lower surface of the plate-like first mounting member and the upper surface of the outer flange portion of the second mounting member, The cylindrical vibration isolator according to claim 1, wherein a lower surface of the first mounting member and an upper surface of the outer flange portion are connected.   A stopper rubber portion integrally formed with the first rubber elastic body is fixed to at least one of the opposing portions of the upper surface of the outer flange portion and the lower surface of the first mounting member. The cylindrical vibration isolator according to claim 1 or 2.   The first rubber elastic body has a tapered cylindrical shape that gradually decreases in diameter toward the upper side, and is fixed to the first mounting member at an end surface on the small diameter side, while the second rubber is fixed on the end surface on the large diameter side. The cylindrical vibration isolator according to any one of claims 1 to 3, which is fixed to the mounting member.   The axial spring constant of the first rubber elastic body is set lower than the spring constant of the second rubber elastic body in the axial direction. Cylindrical anti-vibration device.   In the state before the elastic deformation of the first rubber elastic body, the vertical length of the gap formed between the first attachment member and the inner cylinder member is the first attachment member to the first attachment member. 6. The size according to claim 1, wherein the first rubber elastic body has an amount of elastic deformation substantially the same as that of the first rubber elastic body by inputting a weight load of a heavy object. Cylindrical vibration isolator. 7. The stopper according to claim 1, wherein a stopper protrusion that protrudes into each of the pair of fluid chambers is provided on the inner cylindrical member of the second vibration-proof bushing. Cylindrical vibration isolator.

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