Liquid-sealed antivibration device

Abstract

To provide a liquid-sealed antivibration device capable of suppressing characteristic failure due to leakage of liquid from an orifice.SOLUTION: Contact end surfaces 55 of orifice forming members 51, 52 contact a circumferential end surface 34b of a second partition 34, and fitting protrusions 56 protruding in a circumferential direction from the contact end surfaces 55 are fitted between a pair of elastic walls 37 of the second partition 34. The orifice forming members 51, 52 are provided with an extension part 57 that extends the contact end surfaces 55 in an axial direction, and a holding protrusion 58 that protrudes in the circumferential direction from the extension part 57 and sandwiches the elastic wall 37 in the axial direction between itself and the fitting protrusions 56, on at least one axial side of the fitting protrusions 56. As the result, it is possible to prevent liquid from leaking from the orifice, and to suppress the characteristic failure of a liquid-sealed antivibration device 1 caused by the leakage.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a liquid-filled vibration isolator, and more particularly to a liquid-filled vibration isolator capable of suppressing deterioration of characteristics due to leakage of liquid from an orifice.

Background Art

[0002] Conventionally, for the purpose of vibration damping, buffering, etc., a liquid-filled vibration isolator is disposed at a connecting portion between a vibration source such as a wheel or an engine and a vehicle body. For example, in this liquid-filled vibration isolator, an outer peripheral surface of an inner member and an inner peripheral surface of a cylindrical outer member are connected by a vibration isolation base made of an elastic body. By a first partition wall and a second partition wall of the vibration isolation base, a space between the inner member and the outer member is partitioned in the circumferential direction to form a pair of liquid chambers. One end portions in the circumferential direction of a pair of orifice forming members abut against each other inside a communication groove provided in the first partition wall, and an orifice that communicates the pair of liquid chambers is formed by an outer peripheral groove provided on an outer peripheral surface of the orifice forming member and an inner peripheral surface of the outer member.

[0003] In the liquid-filled vibration isolator disclosed in Patent Document 1, a total of six grooves, three from each of a pair of circumferential end faces of the second partition wall toward the center in the circumferential direction, are formed on a radial end face of the second partition wall that contacts the inner peripheral surface of the outer member. A total of four elastic walls are formed in the axial direction between the three grooves. While fitting a fitting convex portion provided at the other end portion in the circumferential direction of the orifice forming member between the pair of elastic walls, by bringing a step (contact end face) at the base of the fitting convex portion into contact with the circumferential end face of the elastic wall, the other end portion in the circumferential direction of the orifice forming member is positioned with respect to the second partition wall.

[0004] To manufacture this liquid-filled vibration isolator, first, an object in which a vibration isolation base is connected to an outer peripheral surface of an inner member, an orifice forming member, and an outer member are immersed in a liquid. Next, an object in which each part of the orifice forming member is fitted between a communication groove of the vibration isolation base and between a pair of elastic walls is inserted into the outer member, and the outer member is subjected to a drawing process. Finally, the liquid-filled vibration isolator is obtained by caulking an axial edge of the outer member radially inward.

Prior Art Documents

Patent Document

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the technique disclosed in the above Patent Document 1, due to the load when the outer member is subjected to drawing, the pair of elastic walls may deform outward in the axial direction, and the step at the root of the fitting convex portion may be pushed into the space between the pair of elastic walls. Then, the other end in the circumferential direction of the orifice forming member positioned with respect to the second partition wall may shift in the circumferential direction, and a gap may occur between the outer peripheral surface of the orifice forming member and the inner peripheral surface of the outer member. Similarly, due to the load during drawing, the elastic wall may be greatly compressed and deformed in the circumferential direction, resulting in a misalignment of the positioning, and a gap may occur between the outer peripheral surface of the orifice forming member and the inner peripheral surface of the outer member. If liquid leaks from the orifice due to this gap, there is a possibility that the characteristics of the liquid-filled vibration isolator may deteriorate.

[0007] The present invention has been made to solve the above-described problems, and an object thereof is to provide a liquid-filled vibration isolator capable of suppressing deterioration of characteristics due to leakage of liquid from an orifice.

Means for Solving the Problems

[0008] To achieve this object, the liquid-sealed vibration isolator of the present invention includes an inner member extending along an axis, a cylindrical outer member surrounding the inner member, and elastic bodies that connect the outer peripheral surface of the inner member and the inner peripheral surface of the outer member over the entire circumference, forming a pair of radial partitions spaced apart from each other in the axial direction. Elastic first and second partitions made of an elastic body that extend radially outward from the outer peripheral surface of the inner member and contact the inner peripheral surface of the outer member to partition the space surrounded by the inner member, the outer member, and the pair of radial partitions in the circumferential direction into a pair of liquid chambers. A pair of orifice-forming members having an outer peripheral surface that contacts the inner peripheral surface of the outer member and whose circumferential end portions abut against each other inside the communication groove provided in the first partition. An orifice formed by an outer peripheral groove provided on the outer peripheral surface of the orifice-forming member and the inner peripheral surface of the outer member to communicate the pair of liquid chambers. The second partition includes a radial end surface that contacts the inner peripheral surface of the outer member, a pair of circumferential end surfaces that extend radially inward from the edges on both sides in the circumferential direction of the radial end surface, a pair of central grooves formed on the radial end surface so as to extend from the pair of circumferential end surfaces toward the center in the circumferential direction and spaced apart from each other, four side grooves formed on the radial end surfaces on both sides in the axial direction with respect to the pair of central grooves and extending from the circumferential end surfaces toward the center in the circumferential direction and spaced apart from each other, and four elastic walls formed respectively between the pair of central grooves and the four side grooves in the axial direction. The circumferential other end portions of the pair of orifice-forming members each include a contact end surface that contacts the circumferential end surface, a fitting convex portion that protrudes in the circumferential direction from the contact end surface and is fitted into the central groove, an extension portion that extends the contact end surface in the axial direction, and a holding protrusion that protrudes in the circumferential direction from the extension portion and axially sandwiches the elastic wall between the holding protrusion and the fitting convex portion. The extension portion and the holding protrusion are provided on at least one side in the axial direction with respect to the fitting convex portion.

Advantages of the Invention

[0009] According to the liquid-filled vibration isolator described in claim 1, on each of both sides in the circumferential direction of the second partition wall, between one central groove and two side grooves extending from the circumferential end face of the second partition wall toward the center in the circumferential direction, a pair (two sheets) of elastic walls are formed in the axial direction. The contact end face at the other end in the circumferential direction of the orifice forming member contacts the circumferential end face of the second partition wall, and a fitting convex portion protruding in the circumferential direction from the contact end face is fitted into the central groove between the pair of elastic walls. Thereby, the other end in the circumferential direction of the orifice forming member is positioned with respect to the second partition wall.

[0010] On the orifice forming member, an extension portion that extends the contact end face in the axial direction and a holding protrusion that axially sandwiches the elastic wall between the extension portion and the fitting convex portion protruding in the circumferential direction are provided on at least one side in the axial direction with respect to the fitting convex portion. Thereby, when the outer member is necked down, at least one of the pair of elastic walls can be restricted by the holding protrusion from deforming axially outward. Therefore, an elastic reaction force applied from the circumferential end face of the elastic wall can be ensured at the contact end face that is the base of the fitting convex portion. For this reason, it is possible to suppress that other than the fitting convex portion of the orifice forming member is pushed into between the pair of elastic walls or the elastic wall is greatly compressed and deformed in the circumferential direction. Thus, it is possible to make it difficult to generate a gap between the outer peripheral surface of the orifice forming member and the inner peripheral surface of the outer member, and it is possible to make it difficult for the liquid to leak from the orifice formed therebetween, and it is possible to suppress the characteristic failure of the liquid-filled vibration isolator caused by the leakage.

[0011] According to the liquid-filled vibration isolator described in claim 2, in addition to the effects exhibited by the liquid-filled vibration isolator described in claim 1, the following effects are exhibited. Since the extension portion and the holding protrusion are respectively provided on both sides in the axial direction with respect to the fitting convex portion, when the outer member is necked down, both of the pair of elastic walls can be restricted by the holding protrusion from deforming axially outward. As a result, it is possible to further suppress that other than the fitting convex portion of the orifice forming member is pushed into between the pair of elastic walls or the elastic wall is greatly compressed and deformed in the circumferential direction, and thus it is possible to further suppress the characteristic failure caused by the leakage of the liquid from the orifice.

[0012] According to the liquid-filled vibration isolator described in claim 3, in addition to the effects achieved by the liquid-filled vibration isolator described in claim 1, the following effects are achieved. Since the holding projection contacts the inner peripheral surface of the outer member, the holding projection can be applied to the vicinity of the outer member of the elastic wall that is likely to deform greatly in the axial direction. As a result, it is possible to suppress the deformation of the vicinity of the outer member of the elastic wall in the axial direction so as to overcome the holding projection. As a result, it becomes difficult for a part of the orifice forming member to be further pushed between the pair of elastic walls, and it is possible to further suppress the characteristic deterioration caused by the leakage of the liquid from the orifice.

[0013] According to the liquid-filled vibration isolator described in claim 4, in addition to the effects achieved by the liquid-filled vibration isolator described in claim 1, the following effects are achieved. Since the holding projection is radially separated from the groove bottom inside the radial direction of the both-side grooves, it is possible to suppress the holding projection from interfering with the vicinity of the groove bottom when the holding projection is inserted into the both-side grooves. Therefore, the insertability of the holding projection into the both-side grooves can be improved.

[0014] According to the liquid-filled vibration isolator described in claim 5, in addition to the effects achieved by the liquid-filled vibration isolator described in claim 1, the following effects are achieved. Since the holding projection is radially separated from the inner peripheral surface of the outer member, the load during the necking process of the outer member is less likely to be applied to the holding projection, and the durability of the holding projection can be improved.

[0015] According to the liquid-filled vibration isolator described in claim 6, in addition to the effects achieved by the liquid-filled vibration isolator described in any one of claims 1 to 5, the following effects are achieved. The extension portion faces the circumferential end surface of the second partition wall in the radial direction inside the groove bottom inside the radial direction of the both-side grooves in the circumferential direction. Therefore, during the necking process of the outer member, even if the elastic wall deforms over the holding projection or the elastic wall tries to be greatly compressed and deformed in the circumferential direction, the extension portion that contacts the circumferential end surface of the second partition wall functions as a stopper. As a result, it becomes difficult for the other end portion in the circumferential direction of the orifice forming member to be displaced in the circumferential direction with respect to the second partition wall, so that it is possible to further prevent a gap from occurring between the outer peripheral surface of the orifice forming member and the inner peripheral surface of the outer member. Therefore, it is possible to further suppress the characteristic deterioration caused by the leakage of the liquid from the orifice.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0017] Hereinafter, preferred embodiments will be described with reference to the accompanying drawings. FIG. 1 is a plan view of the liquid-filled vibration isolator 1 in the first embodiment. FIG. 2 is a front view of the liquid-filled vibration isolator 1. The arrows U, D, L, R, F, and B in each drawing indicate the upward, downward, leftward, rightward, forward, and backward directions of the liquid-filled vibration isolator 1, respectively. Note that the up-down direction, left-right direction, and front-back direction of this liquid-filled vibration isolator 1 do not necessarily coincide with the up-down direction, left-right direction, and front-back direction of a vehicle or the like on which the liquid-filled vibration isolator 1 is mounted.

[0018] The liquid-sealed vibration isolator 1 mainly includes a substantially cylindrical inner member 10 extending along the axis C, a substantially cylindrical outer member 20 concentrically surrounding the outer peripheral side of the inner member 10, and a vibration isolation base 30 connecting the inner member 10 and the outer member 20. The axial direction of the axis C is the vertical direction. Hereinafter, the direction perpendicular to the axis C will be simply referred to as the radial direction, and the direction around the axis C will be simply referred to as the circumferential direction for explanation.

[0019] The inner member 10 is a member formed of a rigid material such as a steel material or an aluminum alloy. The inner member 10 is fixed to the mating member by bolts inserted on the inner peripheral surface side of the inner member 10. The outer member 20 is press-fitted and fixed to another mating member.

[0020] FIG. 3 is a cross-sectional view of the liquid-sealed vibration isolator 1 taken along line III-III of FIG. 1. FIG. 4 is a cross-sectional view of the liquid-sealed vibration isolator 1 taken along line IV-IV of FIG. 1. FIG. 5 is a cross-sectional view of the liquid-sealed vibration isolator 1 taken along line V-V of FIG. 2. In FIG. 3, the upper surface of the orifice forming member 51 and the lower surface of the orifice forming member 52 are each indicated by a two-dot chain line.

[0021] As shown in FIG. 3, the outer member 20 includes a substantially cylindrical tubular portion 21 formed of a rigid material such as a steel material or an aluminum alloy, and an elastic film 22 made of an elastic body such as rubber or thermoplastic elastomer and vulcanized and adhered to the inner peripheral surface of the tubular portion 21. The inner peripheral surface 23 of the outer member 20 is formed by the elastic film 22. An intermediate cylinder 40 is fitted on the inner peripheral surface 23 of the outer member 20. The outer member 20 is caulked and fixed to the intermediate cylinder 40 by bending the axial edge radially inward.

[0022] The vibration isolation base 30 is a member composed of an elastic body such as rubber or a thermoplastic elastomer, and connects the outer peripheral surface of the inner member 10 and the inner peripheral surface of the outer member 20. The vibration isolation base 30 includes a pair of annular radial partition walls 31 formed on both axial sides of the inner member 10 and the outer member 20, respectively, and an elastic stopper 32 formed between the radial partition walls 31. The radial partition walls 31 and the elastic stopper 32 are integrally vulcanized and molded, and the inner circumferences of the radial partition walls 31 and the elastic stopper 32 are vulcanized and adhered to the outer peripheral surface of the inner member 10.

[0023] The outer circumference of the radial partition wall 31 is vulcanized and adhered to the inner circumference of the fitting peripheral wall 41 of the intermediate cylinder 40 that concentrically surrounds the inner member 10. By closing both axial ends between the inner member 10 and the outer member 20 with a pair of radial partition walls 31, a first liquid chamber 61 and a second liquid chamber 62 are formed. An antifreeze liquid (liquid) such as ethylene glycol is enclosed in the first liquid chamber 61 and the second liquid chamber 62.

[0024] As shown in FIGS. 4 and 5, the intermediate cylinder 40 includes a pair of ring-shaped fitting peripheral walls 41 that fit on the inner peripheral surface 23 of the outer member 20, and a connecting wall 42 that connects the fitting peripheral walls 41 and is recessed radially inward with respect to the fitting peripheral walls 41. The pair of connecting walls 42 are respectively arranged on the front and rear sides with respect to the inner member 10, and a cross section perpendicular to the axis C is formed in an arc shape.

[0025] A pair of first partition walls 33 and second partition walls 34 that are integrally vulcanized and molded with the radial partition walls 31 are respectively vulcanized and adhered to the inner circumferential surfaces of the pair of connecting walls 42. Also, the first partition walls 33 and the second partition walls 34 are provided so as to wrap around the outer peripheral surface side of the connecting wall 42, and the first partition walls 33 and the second partition walls 34 are vulcanized and adhered to the outer peripheral surface of the connecting wall 42. That is, the connecting wall 42 is embedded in the first partition walls 33 and the second partition walls 34. The first partition walls 33 and the second partition walls 34 of the portion where the connecting wall 42 is embedded extend in the circumferential direction along the connecting wall 42.

[0026] The first partition wall 33 is a portion that extends rearward in the radially outer direction from the outer peripheral surface of the inner member 10 and axially connects between the pair of radial partition walls 31. The second partition wall 34 is a portion that extends forward in the radially outer direction from the outer peripheral surface of the inner member 10 and axially connects between the pair of radial partition walls 31. The radial end surface 33a of the first partition wall 33 and the radial end surface 34a of the second partition wall 34 are each in contact with the inner peripheral surface 23 of the outer member 20. A communication groove 33b that recesses radially inward is formed over the entire circumferential length on the radial end surface 33a of the first partition wall 33.

[0027] The space surrounded by the inner member 10, the outer member 20, and the pair of radial partition walls 31 is circumferentially partitioned by the first partition wall 33 and the second partition wall 34, and the first liquid chamber 61 and the second liquid chamber 62 are formed. The first liquid chamber 61 and the second liquid chamber 62 face each other with the inner member 10 interposed therebetween and are formed substantially symmetrically with each other. The first liquid chamber 61 is located on the left side of the first partition wall 33 and the second partition wall 34, and the second liquid chamber 62 is located on the right side of the first partition wall 33 and the second partition wall 34.

[0028] As shown in FIGS. 3 and 5, a pair of orifice forming members 51, 52 are disposed between the inner member 10 and the outer member 20. The orifice forming members 51, 52 are members for forming an orifice 63 that communicates the first liquid chamber 61 and the second liquid chamber 62.

[0029] The orifice forming members 51, 52 are formed in a substantially semi-annular shape by metal or synthetic resin. The orifice forming member 51 is disposed in the first liquid chamber 61, and the orifice forming member 52 is disposed in the second liquid chamber 62.

[0030] One end portion 54 (the rear end portion) in the circumferential direction of the pair of orifice forming members 51 and 52 fits into the communication groove 33b of the first partition wall 33 and abuts against each other within the communication groove 33b. Although details will be described later, the other end portions (the front end portions) in the circumferential direction of the pair of orifice forming members 51 and 52 are respectively fitted to the second partition wall 34 without abutting against each other. In this way, the orifice forming members 51 and 52 are assembled to the vibration isolation base body 30 vulcanized and adhered to the inner member 10, and the outer peripheral surfaces of the orifice forming members 51 and 52 contact the inner peripheral surface 23 of the outer member 20 over substantially the entire circumference.

[0031] On the outer peripheral surfaces of the pair of orifice forming members 51 and 52, outer peripheral grooves 53 that are continuous with each other via the abutting end portions 54 are formed. By bringing the outer peripheral surfaces of the orifice forming members 51 and 52 where the outer peripheral grooves 53 are formed into contact with the inner peripheral surface 23 of the outer member 20, an orifice 63 is formed between the outer peripheral groove 53 and the inner peripheral surface 23. When the outer peripheral groove 53 opens on the upper surface of the central portion in the circumferential direction of the orifice forming member 51, the orifice 63 communicates with the first liquid chamber 61. When the outer peripheral groove 53 opens on the lower surface of the central portion in the circumferential direction of the orifice forming member 52, the orifice 63 communicates with the second liquid chamber 62.

[0032] When a load in the left - right direction is input to the liquid - filled vibration isolation device 1, the radial partition wall 31, the first partition wall 33, and the second partition wall 34 elastically deform, and the inner member 10 and the outer member 20 are displaced relative to each other. Along with this elastic deformation, hydraulic pressure fluctuations occur in the first liquid chamber 61 and the second liquid chamber 62, and the liquid in the first liquid chamber 61 and the second liquid chamber 62 flows through the orifice 63. Liquid column resonance is generated by the orifice 63, and vibration is attenuated. The attenuation characteristics by the orifice 63 are adjusted by the flow path length, the flow path cross - sectional area, etc. of the orifice 63.

[0033] To manufacture such a liquid-sealed vibration isolator 1, first, the inner member 10 and the intermediate cylinder 40 are set in a mold, and the vibration isolation base 30 is vulcanized and molded, and the inner member 10 and the intermediate cylinder 40 are vulcanization-bonded to the vibration isolation base 30. Next, the vulcanized molded product, the orifice forming members 51, 52, and the outer member 20 are submerged in a liquid. Then, the orifice forming members 51, 52 are assembled to the vulcanized molded product and inserted into the inner peripheral surface 23 side of the outer member 20. Then, the outer member 20 is reduced in diameter by drawing, and the inner peripheral surface 23 of the outer member 20 is pressed against the outer peripheral surfaces of the orifice forming members 51, 52 and the like. Finally, the axial edge of the outer member 20 is bent radially inward to clamp and fix the outer member 20 to the intermediate cylinder 40. Thereby, the liquid-sealed vibration isolator 1 is obtained.

[0034] However, since the other ends in the circumferential direction of the pair of orifice forming members 51, 52 do not abut against each other, they may shift circumferentially with respect to the second partition wall 34 due to the load when the outer member 20 is drawn, and the interval between their other ends may narrow. Due to this narrowing, if a gap is generated between the outer peripheral surface of the orifice forming members 51, 52 and the inner peripheral surface 23 of the outer member 20, liquid may leak from the orifice 63. Then, there is a possibility that the liquid-sealed vibration isolator 1 may have a defect in the damping characteristics according to the flow path length of the orifice 63.

[0035] Referring to FIGS. 6 to 8, a configuration for making it difficult to generate such a characteristic defect will be described with respect to the fitting portion between the other ends in the circumferential direction of the orifice forming members 51, 52 and the second partition wall 34. FIG. 6 is a front view of the liquid-sealed vibration isolator 1 with the outer member 20 removed. FIG. 7 is a cross-sectional view of the liquid-sealed vibration isolator 1 taken along line VII-VII of FIG. 6. FIG. 8 is a cross-sectional view of the liquid-sealed vibration isolator 1 taken along line VIII-VIII of FIG. 6. The liquid-sealed vibration isolator 1 shown in FIGS. 7 and 8 is also in a state where the outer member 20 is removed, and the inner peripheral surface 23 of the outer member 20 is shown by a broken line in FIG. 7.

[0036] The second partition wall 34 is formed symmetrically with respect to the center in the circumferential direction (left - right direction). Hereinafter, regarding the second partition wall 34, the side of the orifice forming member 52 (right side) will be mainly described, and the description of the side of the orifice forming member 51 (left side) will be partially omitted.

[0037] In the second partition wall 34, the circumferential end face in the portion (near the radial end face 34a) where the connecting wall 42 is embedded is the circumferential end face 34b. This circumferential end face 34b extends radially inward from the circumferential edge of the radial end face 34a of the second partition wall 34.

[0038] On the radial end face 34a of the second partition wall 34, three grooves are formed that extend parallel to each other from the circumferential end face 34b toward the circumferential center and are recessed radially inward. Among these three grooves, the groove at the axial center is the central groove 35, and the grooves located on both axial sides with respect to the central groove 35 are the side grooves 36. A pair of central grooves 35 provided on both circumferential sides of the second partition wall 34 are separated from each other in the circumferential direction, and a total of four side grooves 36 are also separated from each other in the circumferential direction.

[0039] The groove bottom on the radial inner side of the central groove 35 is at a position deeper radially than the groove bottom on the radial inner side of the side grooves 36. A thin film made of an elastic body is formed between the groove bottom of the central groove 35 and the outer peripheral surface of the connecting wall 42 so that they do not come into direct contact. The wall surface on the central side in the circumferential direction of the central groove 35 and the wall surface on the central side in the circumferential direction of the side grooves 36 are at substantially the same position in the circumferential direction.

[0040] In the second partition wall 34, a pair of plate - shaped elastic walls 37 are formed axially between one central groove 35 and two side grooves 36. The closer the elastic wall 37 is to the radial end face 34a or the circumferential end face 34b, the more easily it deforms greatly axially. The closer the elastic wall 37 is to the radial end face 34a, the more easily it deforms greatly circumferentially.

[0041] A relief valve 39 protrudes from the circumferential center of the radial end face 34a. The relief valve 39 is a low protrusion continuous over the entire axial length between a pair of fitting circumferential walls 41. When this relief valve 39 bites into the inner circumferential surface 23 of the outer member 20, basically, the space between the radial end face 34a and the inner circumferential surface 23 is sealed.

[0042] However, when the hydraulic pressure difference between the first liquid chamber 61 and the second liquid chamber 62 exceeds a predetermined threshold value, as the second partition wall 34 deforms, the radial end face 34a including the relief valve 39 separates from the inner circumferential surface 23. As a result, at thresholds and above, liquid can be sent from the negative pressure side to the positive pressure side of the first liquid chamber 61 and the second liquid chamber 62, so the occurrence of cavitation due to excessive negative pressure can be suppressed. Consequently, the generation of abnormal noise due to cavitation can be suppressed.

[0043] This threshold value is adjusted by factors such as the height of the relief valve 39 and the ease of deformation of the second partition wall 34 near the relief valve 39. The ease of deformation of the second partition wall 34 is determined according to factors such as the circumferential length of the central groove 35 and the both-side grooves 36, and the axial thickness of the elastic wall 37. In order to make the second partition wall 34 easier to deform, the thickness of the elastic wall 37 in the present embodiment is formed to be sufficiently thin, about half of the axial interval between the pair of elastic walls 37.

[0044] Similar to the second partition wall 34, the other circumferential end of the orifice forming member 51 and the other circumferential end of the orifice forming member 52 are formed symmetrically with respect to the circumferential center of the second partition wall 34. Hereinafter, the orifice forming member 52 will be mainly described, and the description of the orifice forming member 51 will be partially omitted.

[0045] The other circumferential end of the orifice forming member 52 includes a contact end face 55 that contacts the circumferential end face 34b of the second partition wall 34 (elastic wall 37), a fitting convex portion 56 that protrudes circumferentially from the contact end face 55, an extension portion 57 that extends the contact end face 55 axially, and a holding protrusion 58 that protrudes circumferentially from the extension portion 57. When the contact end face 55 contacts the circumferential end face 34b, the other circumferential end of the orifice forming member 52 is positioned circumferentially with respect to the second partition wall 34.

[0046] The fitting convex portion 56 is a portion of the central groove 35 that is fitted between the pair of elastic walls 37. Thereby, the other end portion of the orifice forming member 52 in the circumferential direction is axially positioned with respect to the second partition wall 34. Further, since the fitting convex portion 56 contacts the groove bottom of the central groove 35, the other end portion of the orifice forming member 52 in the circumferential direction is radially positioned with respect to the second partition wall 34.

[0047] The tip of the fitting convex portion 56 is separated from the circumferentially central side wall surface of the central groove 35. Thereby, the contact between the tip of the fitting convex portion 56 and the wall surface of the central groove 35 can prevent the contact end surface 55 and the circumferential end surface 34b from separating. As a result, the positioning by the contact between the contact end surface 55 and the circumferential end surface 34b can be maintained.

[0048] The extension portion 57 and the holding projection 58 are respectively provided on both axial sides with respect to the fitting convex portion 56. The holding projection 58 projects from the extension portion 57 into the both-side grooves 36 and axially sandwiches the elastic wall 37 between it and the fitting convex portion 56.

[0049] Thereby, when the outer member 20 is necked down, the holding projection 58 can restrict both of the pair of elastic walls 37 from deforming axially outward. Therefore, an elastic reaction force applied from the circumferential end surface 34b of the elastic wall 37 can be ensured at the contact end surface 55 which is the base of the fitting convex portion 56. By ensuring this elastic reaction force, it is possible to suppress the pushing in of portions other than the fitting convex portion 56 of the orifice forming member 52 between the pair of elastic walls 37 and the large compressive deformation of the elastic wall 37 in the circumferential direction.

[0050] Then, since it becomes difficult for the other end portion of the orifice forming member 52 in the circumferential direction to shift in the circumferential direction from the state of being positioned with respect to the second partition wall 34, it is possible to make it difficult for a gap to occur between the outer peripheral surface of the orifice forming member 52 and the inner peripheral surface 23 of the outer member 20. Therefore, it is possible to make it difficult for liquid to leak from the orifice 63 formed therebetween, and it is possible to suppress the characteristic deterioration of the liquid-sealed vibration isolator 1 due to such leakage.

[0051] The length from the contact end face 55 to the tip of the holding protrusion 58 is substantially the same as the length from the contact end face 55 to the tip of the fitting convex portion 56. Thereby, when the outer member 20 is subjected to the drawing process, it is possible to suppress the elastic wall 37 from being deformed in the axial direction so as to overcome the holding protrusion 58. As a result, it becomes difficult for parts other than the fitting convex portion 56 of the orifice forming member 52 to be pushed further between the pair of elastic walls 37, and it is possible to further suppress the characteristic defect caused by the liquid leakage from the orifice 63.

[0052] Note that the length of the holding protrusion 58 and the length of the fitting convex portion 56 may be different. If the length of the holding protrusion 58 is at least half of the length of the fitting convex portion 56, when the outer member 20 is subjected to the drawing process, it is possible to sufficiently suppress the elastic wall 37 from being deformed in the axial direction so as to overcome the holding protrusion 58.

[0053] As shown in FIG. 7, the holding protrusion 58 contacts the inner peripheral surface 23 of the outer member 20. Thereby, the vicinity of the outer member 20 (on the side of the radial end face 34a) of the pair of elastic walls 37 that is likely to be greatly deformed in the axial direction can be abutted against the holding protrusion 58. Thereby, when the outer member 20 is subjected to the drawing process, it is possible to suppress the vicinity of the outer member 20 of the elastic wall 37 from being deformed in the axial direction so as to overcome the holding protrusion 58. It becomes difficult for parts other than the fitting convex portion 56 of the orifice forming member 52 to be pushed further between the pair of elastic walls 37, and it is possible to further suppress the characteristic defect caused by the liquid leakage from the orifice 63.

[0054] Since the holding protrusion 58 is radially separated from the groove bottom of the both-side groove 36, when the holding protrusion 58 is inserted into the both-side groove 36 and the orifice forming member 52 is assembled to the second partition wall 34, it is possible to suppress the holding protrusion 58 from interfering with the vicinity of the groove bottom of the both-side groove 36. Therefore, the insertability of the holding protrusion 58 into the both-side groove 36 can be improved, and the assemblability of the orifice forming member 52 to the second partition wall 34 can be improved.

[0055] Also, the axial interval between the fitting convex portion 56 and the holding protrusion 58 is slightly larger than the axial thickness of the elastic wall 37. Thereby, when inserting the fitting convex portion 56 and the holding protrusion 58 into the central groove 35 and the both-side grooves 36 on both sides of the elastic wall 37 respectively, it is possible to make it difficult for the fitting convex portion 56 and the holding protrusion 58 to be caught by the elastic wall 37. As a result, the insertability of the fitting convex portion 56 and the holding protrusion 58 into the central groove 35 and the both-side grooves 36 can be improved, and the assemblability of the orifice forming member 52 to the second partition wall 34 can be improved.

[0056] A protrusion 37a having substantially the same height as the relief valve 39 protrudes from the radial end face 34a of the elastic wall 37. When this protrusion 37a bites into the inner peripheral surface 23 of the outer member 20, during the throttling process of the outer member 20, it becomes difficult for the elastic wall 37 to slip axially and circumferentially with respect to the inner peripheral surface 23, and it is possible to suppress the elastic wall 37 from being deformed axially or compressed and deformed circumferentially. As a result, it is possible to further suppress characteristic defects caused by leakage of liquid from the orifice 63.

[0057] As shown in FIG. 8, the extension portion 57 is in contact with the circumferential end face 34b of the second partition wall 34 radially inside the groove bottom of the both-side grooves 36 in the circumferential direction. Therefore, during the throttling process of the outer member 20, even if the elastic wall 37 rides over the holding protrusion 58 and deforms, or the elastic wall 37 tries to be greatly compressed and deformed circumferentially, the extension portion 57 in contact with the circumferential end face 34b functions as a stopper. As a result, it becomes more difficult for the other end portion in the circumferential direction of the orifice forming member 52 to shift further circumferentially from the state of being positioned with respect to the second partition wall 34, so that it is possible to further suppress characteristic defects caused by leakage of liquid from the orifice 63.

[0058] Note that the circumferential end face 34b radially inside the groove bottom of the both-side grooves 36 and the extension portion 57 may face each other with a gap in the circumferential direction. Also in this case, since the extension portion 57 functions as a stopper when it contacts the circumferential end face 34b, it is possible to suppress characteristic defects caused by leakage of liquid from the orifice 63.

[0059] Next, the second embodiment will be described with reference to FIG. 9(a). In the first embodiment, the case where the holding protrusion 58 is radially separated from the groove bottom of the both-side grooves 36 was described. In contrast, in the second embodiment, the case where the holding protrusion 72 contacts the groove bottom of the both-side grooves 36 will be described. Note that the same parts as those in the first embodiment are denoted by the same reference numerals, and the following description thereof will be omitted.

[0060] FIG. 9(a) is a cross-sectional view of the liquid-filled vibration isolator 70 in the second embodiment. The liquid-filled vibration isolator 70 is configured in the same manner as the liquid-filled vibration isolator 1 in the first embodiment, except that the position and shape of the holding protrusion 72 of the orifice forming member 71 are different.

[0061] The holding protrusion 72 of the orifice forming member 71 is a part that is inserted into the both-side grooves 36 and axially sandwiches the elastic wall 37 between the fitting convex portions 56, and is provided on both axial sides with respect to the fitting convex portion 56. Since the holding protrusion 72 is radially separated from the inner peripheral surface 23 of the outer member 20, it is difficult for the load during the drawing process of the outer member 20 to be applied to the holding protrusion 72, and the durability of the holding protrusion 72 can be improved.

[0062] Furthermore, since it is difficult for the load during the drawing process to be applied to the holding protrusion 72, the required strength of the holding protrusion 72 is low, and it is easy to reduce the axial dimension and the radial dimension of the holding protrusion 72. As a result, the axial depth and the radial width of the both-side grooves 36 into which the holding protrusion 72 is inserted can be reduced, and the both-side grooves 36 and the holding protrusion 72 can be provided even in a narrow space.

[0063] Also, since the holding protrusion 72 contacts the groove bottom of the both-side grooves 36, when the elastic wall 37 is deformed so as to fall axially during the drawing process of the outer member 20, the starting point of the fall can be moved away from the groove bottom. Since it is easy to reduce the axial deformation amount of the elastic wall 37, it is difficult for parts other than the fitting convex portion 56 of the orifice forming member 71 to be pushed into the space between the pair of elastic walls 37. Therefore, characteristic defects caused by liquid leakage from the orifice 63 can be more effectively suppressed.

[0064] Next, the third embodiment will be described with reference to FIG. 9(b). In the first embodiment, the case where the holding projection 58 contacts the inner peripheral surface 23 of the outer member 20 while being radially separated from the bottom of the both-side grooves 36 was described. In contrast, in the third embodiment, the case where the holding projection 82 contacts both the inner peripheral surface 23 of the outer member 20 and the bottom of the both-side grooves 36 will be described. Note that the same parts as those in the first and second embodiments are denoted by the same reference numerals, and the following description thereof will be omitted.

[0065] FIG. 9(b) is a cross-sectional view of the liquid-filled vibration isolator 80 according to the third embodiment. The liquid-filled vibration isolator 80 is configured in the same manner as the liquid-filled vibration isolator 1 in the first embodiment, except that the position and shape of the holding projection 82 of the orifice forming member 81 are different.

[0066] The holding projection 82 of the orifice forming member 81 is a part that is inserted into the both-side grooves 36 and axially sandwiches the elastic wall 37 between the fitting convex portions 56, and is provided on both axial sides with respect to the fitting convex portions 56. The holding projection 82 contacts both the inner peripheral surface 23 of the outer member 20 and the bottom of the both-side grooves 36.

[0067] The holding projection 82 is continuously formed from the inner peripheral surface 23 of the outer member 20 to the bottom of the both-side grooves 36, and is in contact with the elastic wall 37 in the radial direction. Therefore, when a circumferential compressive load is applied from the orifice forming member 81 to the elastic wall 37 due to the necking process of the outer member 20, the holding projection 82 can restrict the elastic wall 37 from bulging between the inner peripheral surface 23 and the groove bottom. Thereby, a circumferential elastic reaction force applied from the elastic wall 37 to the orifice forming member 81 can be ensured, so that it is possible to suppress that other than the fitting convex portion 56 of the orifice forming member 81 is pushed into between the pair of elastic walls 37 or the elastic wall 37 is greatly compressed and deformed in the circumferential direction. Therefore, it is possible to further suppress the characteristic failure caused by the leakage of the liquid from the orifice 63.

[0068] The present invention has been described based on the embodiments. However, the present invention is not limited to the above embodiments at all, and it can be easily inferred that various improvements and modifications are possible without departing from the gist of the present invention. For example, the shapes and materials exemplified in the above embodiments are just examples, and it is of course possible to adopt other shapes and materials. Also, the relief valve 39 may be omitted.

[0069] The inner member 10 and the outer member 20 may be in a cylindrical shape other than a substantially cylindrical shape. The inner member 10 is not limited to a cylindrical shape and may be a columnar shape. In this case, a threaded portion protruding from an end portion in the axial direction of the inner member 10 may be joined to the mating member, or the end portion in the axial direction of the inner member 10 may be integrally formed with the mating member.

[0070] In the above embodiment, the case where the extension portions 57 and the holding protrusions 58, 72, 82 are provided on both sides in the axial direction with respect to the fitting convex portion 56 has been described, but it is not necessarily limited to this. The extension portions 57 and the holding protrusions 58, 72, 82 may be provided only on one side in the axial direction with respect to the fitting convex portion 56. Even in this case, when the outer member 20 is necked down, the holding protrusions 58, 72, 82 can restrict one of the pair of elastic walls 37 from deforming outward in the axial direction, so that the circumferential elastic reaction force applied from the elastic wall 37 to the orifice forming members 51, 52, 71, 81 can be ensured.

[0071] However, compared with this one-sided case, providing the extension portions 57 and the holding protrusions 58, 72, 82 on both sides can make the circumferential elastic reaction force applied from the elastic wall 37 to the orifice forming members 51, 52, 71, 81 larger. Therefore, characteristics deterioration caused by liquid leakage from the orifice 63 can be more effectively suppressed on both sides than on one side.

[0072] In the above embodiment, the case where the second partition wall 34 is symmetric with respect to the center in the circumferential direction has been described, but it is not necessarily limited to this and may be asymmetric. Similarly, the other end portion in the circumferential direction of the orifice forming member 51 and the other end portion in the circumferential direction of the orifice forming member 52 are not limited to the case where they are symmetrically formed with respect to the center in the circumferential direction of the second partition wall 34, and may be asymmetrically formed.

Description of Symbols

[0073] 1,70,80 Liquid-filled Vibration Isolation Device 10 Inner Member 20 Outer Member 23 Inner Peripheral Surface 31 Radial Partition Wall 33 First Partition Wall 33b Communication Groove 34 Second Partition Wall 34a Radial End Face 34b Circumferential End Face 35 Central Groove 36 Both-Side Grooves 37 Elastic Wall 51,52,71,81 Orifice Forming Members 53 Outer Peripheral Groove 54 One End Portion 55 Contact End Face 56 Fitting Projection 57 Extension Portion 58 Holding Projection 61 First Liquid Chamber (Liquid Chamber) 62 Second Liquid Chamber (Liquid Chamber) 63 Orifice C Axis

Claims

1. an inner member extending along an axis; a cylindrical outer member surrounding the inner member; a pair of radial partitions formed by elastic bodies that connect the outer peripheral surface of the inner member and the inner peripheral surface of the outer member over the entire circumference and are axially spaced apart from each other; first and second elastic body-made partitions that extend radially outward from the outer peripheral surface of the inner member and contact the inner peripheral surface of the outer member, thereby partitioning the space surrounded by the inner member, the outer member, and the pair of radial partitions in the circumferential direction into a pair of liquid chambers; a pair of orifice forming members having outer peripheral surfaces that contact the inner peripheral surface of the outer member and whose circumferential end portions are butted against each other inside a communication groove provided in the first partition; an orifice formed by an outer peripheral groove provided on the outer peripheral surface of the orifice forming member and the inner peripheral surface of the outer member to communicate the pair of liquid chambers; and the second partition includes a radial end surface that contacts the inner peripheral surface of the outer member; a pair of circumferential end surfaces that extend radially inward from edges on both circumferential sides of the radial end surface; a pair of central grooves formed in the radial end surface so as to extend from the pair of circumferential end surfaces toward the center in the circumferential direction and are spaced apart from each other; four side grooves formed in the radial end surfaces on both axial sides of the pair of central grooves and extending from the circumferential end surfaces toward the center in the circumferential direction and spaced apart from each other; four elastic walls respectively formed between the pair of central grooves and the four side grooves in the axial direction; and the circumferential other end portions of the pair of orifice forming members include contact end surfaces that contact the circumferential end surfaces; fitting convex portions that project in the circumferential direction from the contact end surfaces and are fitted into the central grooves; extension portions that extend the contact end surfaces in the axial direction; and holding projections that project in the circumferential direction from the extension portions and axially sandwich the elastic walls between the holding projections and the fitting convex portions, respectively; the liquid-filled vibration isolator, wherein the extension portion and the holding projection are provided on at least one axial side with respect to the fitting convex portion.

2. The liquid-filled vibration isolator according to claim 1, wherein the extension portion and the holding projection are provided on both axial sides with respect to the fitting convex portion.

3. The liquid-filled vibration isolator according to claim 1, wherein the holding projection contacts the inner peripheral surface of the outer member.

4. The liquid-filled vibration isolator according to claim 1, wherein the holding projection is radially separated from the groove bottom inside the radial direction of the both-side grooves.

5. The liquid-filled vibration isolator according to claim 1, wherein the holding projection is radially separated from the inner peripheral surface of the outer member.

6. The liquid-filled vibration isolator according to any one of claims 1 to 5, wherein the extension portion faces in the circumferential direction the circumferential end surface on the radially inner side than the groove bottom on the radially inner side of the both-side grooves.

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