Liquid-sealed antivibration device

Abstract

To provide a liquid-sealed antivibration device capable of improving durability of a valve part.SOLUTION: A plate part 41 of a switching membrane 40 is sandwiched between a first partition plate 23 and a second partition plate 26. A pair of cylindrical valve parts 42, 43 protrudes from the entire circumference of an outer peripheral edge 41c of the plate part 41 toward both sides in a plate thickness direction of the plate part 41. On an outer peripheral surface of the switching membrane 40, inclined surfaces 42a, 43a that incline radially inward toward a center in the plate thickness direction of the plate part 41 are formed at a position including the outer peripheral edge 41c of the plate part 41. The inclined surfaces 42a, 43a make it easy to tilt one of the pair of valve parts 42, 43 radially outward independently of the other. Therefore, when one of the valve parts 42, 43 blocks an orifice, it is possible to suppress deformation of the other of the valve parts 42, 43, thereby improving durability of the valve parts 42, 43.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a liquid-filled vibration isolator, and particularly to a liquid-filled vibration isolator capable of improving the durability of a valve portion.

Background Art

[0002] As a vibration isolator for supporting a vibration source such as an engine on a vehicle body (support side), for example, a liquid-filled vibration isolator disclosed in Patent Document 1 is known. The liquid-filled vibration isolator disclosed in Patent Document 1 has a liquid chamber formed therein partitioned into a first liquid chamber and a second liquid chamber by a partition body, and the first liquid chamber and the second liquid chamber are communicated with each other by an orifice. The partition body includes a first partition plate facing the first liquid chamber, a second partition plate facing the second liquid chamber, and a switching valve for switching between a communicating state and a blocking state of the orifice.

[0003] The switching valve of Patent Document 1 includes an annular support portion sandwiched between the first partition plate and the second partition plate, and a pair of annular (cylindrical) valve portions protruding axially from both sides of the support portion. When switching from a communicating state where there is a gap between the valve portion and the inner wall of the orifice to a blocking state, the entire valve portion falls down due to the liquid flow in the orifice and contacts the inner wall of the orifice, thereby switching to the blocking state.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the above Patent Document 1, when switching the orifice from the communicating state to the blocking state, one of the pair of valve portions contacts the inner wall of the orifice, but the other deforms so as to be separated from the inner wall and does not contribute to the blocking of the orifice. Due to this deformation of the other valve portion, the durability of the valve portion may be reduced.

[0006] 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 improving the durability of a valve portion.

Means for Solving the Problems

[0007] To achieve this object, the liquid-filled vibration isolator of the present invention includes a first member and a cylindrical second member, a vibration isolation base made of an elastic body that connects the first member and the second member, an elastic diaphragm that is attached to the second member and forms a liquid chamber in which a liquid is enclosed between the vibration isolation base, a partition body that partitions the liquid chamber into a first liquid chamber and a second liquid chamber, an orifice formed in the partition body that communicates the first liquid chamber and the second liquid chamber, and an elastic switching film that switches between a communicating state and a blocking state of the orifice. The partition body includes a first partition plate facing the first liquid chamber and a second partition plate facing the second liquid chamber. The orifice is formed by an annular accommodation space formed between the first partition plate and the second partition plate, a plurality of first through holes formed through the first partition plate to communicate the first liquid chamber and the accommodation space, and a plurality of second through holes formed through the second partition plate to communicate the second liquid chamber and the accommodation space. The switching film has an outer peripheral edge that faces the outer peripheral wall surface of the accommodation space in the radial direction over the entire circumference, and a plate portion sandwiched between the first partition plate and the second partition plate so that the outer peripheral edge side protrudes into the accommodation space, and a pair of cylindrical valve portions that protrude from the entire circumference of the outer peripheral edge of the plate portion toward both sides in the plate thickness direction of the plate portion. In the communicating state, a space is formed between the valve portion and the outer peripheral wall surface, and in the blocking state, the valve portion deformed radially outward contacts the outer peripheral wall surface, thereby blocking the orifice. An inclined surface that inclines radially inward toward the center in the plate thickness direction of the plate portion is formed at least at a position including the outer peripheral edge on the outer peripheral surface of the switching film including the outer peripheral edge and the outer peripheral surface of the valve portion.

[0008] Furthermore, the liquid-sealed vibration isolator of the present invention includes a first member and a cylindrical second member, a vibration isolation base made of an elastic body that connects the first member and the second member, an elastic diaphragm that is attached to the second member and forms a liquid chamber in which liquid is enclosed between the vibration isolation base, a partition body that partitions the liquid chamber into a first liquid chamber and a second liquid chamber, an orifice formed in the partition body that communicates the first liquid chamber and the second liquid chamber, and an elastic switching film that switches between a communicating state and a blocking state of the orifice. The partition body includes a first partition plate facing the first liquid chamber and a second partition plate facing the second liquid chamber. The orifice is formed by an annular accommodation space formed between the first partition plate and the second partition plate, a plurality of first through holes formed through the first partition plate to communicate the first liquid chamber and the accommodation space, and a plurality of second through holes formed through the second partition plate to communicate the second liquid chamber and the accommodation space. The switching film has an inner peripheral edge that faces the inner peripheral wall surface of the accommodation space in the radial direction over the entire circumference, and an annular plate portion that is sandwiched between the first partition plate and the second partition plate so that the inner peripheral edge side protrudes into the accommodation space. The switching film includes a pair of cylindrical valve portions that protrude from the entire circumference of the inner peripheral edge of the plate portion toward both sides in the plate thickness direction of the plate portion. In the communicating state, a space is formed between the valve portion and the inner peripheral wall surface. In the blocking state, the orifice is blocked when the valve portion deformed radially inward contacts the inner peripheral wall surface. An inclined surface that inclines radially outward toward the center in the plate thickness direction of the plate portion is formed at least at a position including the inner peripheral edge on the inner peripheral surface of the switching film including the inner peripheral edge and the inner peripheral surface of the valve portion.

Advantages of the Invention

[0009] According to the liquid-filled vibration isolator described in claim 1, the plate portion of the switching film is sandwiched between the first partition plate and the second partition plate so as to protrude into the accommodation space that forms part of the orifice. The outer peripheral edge of this plate portion faces the outer peripheral wall surface of the accommodation space in the radial direction over the entire circumference. A pair of cylindrical valve portions protrude from the entire circumference of the outer peripheral edge of the plate portion toward both sides in the plate thickness direction of the plate portion. The switching film switches between a communication state in which the space between the valve portion and the outer peripheral wall surface is separated and a blocking state in which the orifice is blocked when the valve portion deformed (tilted) radially outward contacts the outer peripheral wall surface. This deformation radially outward is caused by the liquid flow in the orifice.

[0010] On the outer peripheral surface of the switching film including the outer peripheral edge of the plate portion and the outer peripheral surface of the valve portion, an inclined surface that inclines radially inward toward the center in the plate thickness direction of the plate portion is formed at least at a position including the outer peripheral edge. Due to this inclined surface, one of the pair of valve portions can be easily tilted radially outward independently of the other. Therefore, when one of the valve portions blocks the orifice, deformation of the other valve portion can be suppressed, and the durability of the valve portion can be improved.

[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. The outer peripheral surface of the valve portion is formed by the inclined surface, and the inner peripheral surface of the valve portion inclines along the inclined surface. As a result, the thickness of the valve portion can be made closer to being substantially constant, so that when the valve portion tilts, concentration of strain in the thin portion of the valve portion can be suppressed. As a result, the durability of the valve portion can be further improved.

[0012] According to the liquid-filled vibration isolator described in claim 3, in addition to the effects exhibited by the liquid-filled vibration isolator described in claim 2, the following effects are exhibited. A concave portion recessed radially inward is formed on the outer peripheral edge side of the inclined surface. Since the valve portion easily tilts with this concave portion as a fulcrum, it becomes difficult for the pair of valve portions to deform integrally. As a result, the durability of the valve portion can be further improved.

[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 3, the following effects are achieved. On the inner peripheral surface of the valve portion, a convex portion that bulges radially inward on the side opposite to the concave portion in the radial direction is provided. Thereby, even when the concave portion is provided, the thickness of the valve portion can be made closer to being substantially constant by the convex portion. As a result, when the valve portion is deformed, it is possible to suppress the concentration of strain in the vicinity of the concave portion and the reduction in the durability of the valve portion.

[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 3, the following effects are achieved. The concave portion is formed across the outer peripheral surface of the valve portion and the outer peripheral edge of the plate portion. Thereby, since the valve portion is more likely to fall from the base, the time from when the valve portion starts to fall until it contacts the outer peripheral wall surface can be shortened compared to the case where the valve portion bends midway. As a result, the switching sensitivity from the communicating state to the blocking state of the orifice 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 claim 2, the following effects are achieved. The first through-hole and the second through-hole each open into the accommodation space at a position radially opposed to the inner peripheral surface of the valve portion. The wall surfaces on the plate portion side of the first through-hole and the second through-hole are each inclined toward the plate portion side as they go radially outward. Thereby, since the flow of the liquid that has exited the accommodation space from the first through-hole or the second through-hole acts substantially perpendicular to the inner peripheral surface of the valve portion, the valve portion can be quickly brought into contact with the outer peripheral wall surface. As a result, the switching sensitivity from the communicating state to the blocking state of the orifice can be improved.

[0016] According to the liquid-filled vibration isolator described in claim 7, in addition to the effects achieved by the liquid-filled vibration isolator described in any one of claims 1 to 6, the following effects are achieved. The shortest distance from the portion where the plate portion is sandwiched between the first partition plate and the second partition plate to the valve portion is half or less of the length of the valve portion in the protruding direction. Thereby, it is possible to suppress the entire displacement of the switching film in the plate thickness direction in the accommodation space due to the liquid flow in the orifice, and it is possible to make only the valve portion more likely to fall.

[0017] The liquid-filled vibration isolator according to claim 8 has the same arrangement and shape of each part as those of the liquid-filled vibration isolator according to claim 1, but with the inside and outside in the radial direction reversed. Therefore, it exhibits the same effects as the liquid-filled vibration isolator according to claim 1.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0019] Hereinafter, preferred embodiments will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a liquid-filled vibration isolator 10 in the first embodiment. Note that FIG. 1 shows a no-load state in which no vibration (load) is input to the liquid-filled vibration isolator 10. Unless otherwise specified, each part of the liquid-filled vibration isolator 10 will be described in the no-load state. Also, in the following description, the upper side on the paper surface of FIG. 1 will be described as the upper side of the liquid-filled vibration isolator 10 and the like, but the up and down of this liquid-filled vibration isolator 10 does not necessarily coincide with the up and down of the vehicle to which the liquid-filled vibration isolator 10 is attached.

[0020] The liquid-filled vibration isolator 10 is an engine mount that elastically supports the engine of an automobile. The liquid-filled vibration isolator 10 mainly includes a first member 11 attached to the engine side as the vibration source, a cylindrical second member 12 attached to the vehicle body on the support side, and a vibration isolation base 13 composed of an elastic body that connects the first member 11 and the second member 12. Note that the cross-sectional view of the liquid-filled vibration isolator 10 in FIG. 1 is an axial cross-sectional view including the axial center C of the cylindrical second member 12. The direction of the axial center C is the vertical direction of the liquid-filled vibration isolator 10. Hereinafter, the direction perpendicular to the axial center C will be simply referred to as the radial direction, and the direction around the axial center C will be simply referred to as the circumferential direction for explanation.

[0021] The first member 11 is a boss fitting arranged on the axial center C so as to be located above the second member 12, and is formed of a metal such as steel or aluminum alloy. Bolt holes are formed on the upper end surface of the first member 11. The first member 11 is attached to the engine side via bolts attached to the bolt holes.

[0022] The second member 12 is a cylindrical member centered on the axial center C, and is mainly formed of a metal such as steel. The second member 12 includes a large-diameter portion 12a on the upper end side, a reduced-diameter portion 12b that continues to the lower end of the large-diameter portion 12a and whose inner and outer diameters gradually decrease downward, and a small-diameter portion 12c that continues to the lower end of the reduced-diameter portion 12b and whose inner and outer diameters are smaller than those of the large-diameter portion 12a. For example, the second member 12 is attached to the vehicle body side by being inserted into a cylindrical bracket provided on the vehicle body side.

[0023] The vibration isolation base 13 is a member made of an elastic body such as rubber or thermoplastic elastomer formed in a substantially umbrella shape. The vibration isolation base 13 is vulcanized and adhered to the lower part of the first member 11 and the inner peripheral surfaces of the large-diameter portion 12a and the reduced-diameter portion 12b, respectively, to connect them. A rubber film-like film portion 14 that covers the inner peripheral surface of the small-diameter portion 12c is continuous with the lower end portion of the vibration isolation base 13. This film portion 14 is a part of the second member 12.

[0024] A diaphragm 15 is attached to the second member 12 through an attachment portion 16 so as to close the lower end opening of the small-diameter portion 12c. The diaphragm 15 is a film made of an elastic body such as rubber. The attachment portion 16 is an annular member made of metal such as steel. The outer peripheral portion of the diaphragm 15 is vulcanized and adhered to the inner peripheral portion of the attachment portion 16 over the entire circumference.

[0025] A liquid chamber is formed by a sealed space defined by the vibration-proof base 13, the second member 12, and the diaphragm 15. An antifreezing liquid (not shown) such as ethylene glycol is enclosed in the liquid chamber. The liquid chamber is partitioned by a partition body 20 into a first liquid chamber 17 in which the vibration-proof base 13 constitutes a part of the chamber wall and a second liquid chamber 18 in which the diaphragm 15 constitutes a part of the chamber wall.

[0026] In order to attach the diaphragm 15 and the partition body 20 to the second member 12, first, the partition body 20 is inserted into the small-diameter portion 12c of the second member 12 until it hits the step 13a of the vibration-proof base 13 that projects stepwise inward in the radial direction from the upper end of the film portion 14. Next, after the attachment portion 16 integrated with the diaphragm 15 is inserted into the small-diameter portion 12c, the small-diameter portion 12c (second member 12) is reduced in diameter by drawing, and the outer peripheral portions of the partition body 20 and the attachment portion 16 are held by the film portion 14. Thereby, the diaphragm 15 and the partition body 20 are attached to the second member 12.

[0027] In addition to FIG. 1, the partition body 20 will be described with reference to FIGS. 2 to 4. FIG. 2 is a plan view of the partition body 20. The cross section of the partition body 20 taken along line I-I in FIG. 2 is shown in FIG. 1. FIG. 3 is a plan view of the partition body 20 with the first partition plate 23 removed. FIG. 4 is a partially enlarged cross-sectional view of the liquid-filled vibration-proof device 10 showing an enlarged view of a portion IV in FIG. 1.

[0028] As shown in FIGS. 1 and 2, the partition body 20 includes a cylindrical member 21 held inside the film portion 14, flat plate-shaped first and second partition plates 23 and 26 that vertically partition the inner peripheral side of the cylindrical member 21, and a valve 30 and a switching film 40 disposed between the first partition plate 23 and the second partition plate 26. The first partition plate 23 faces the first liquid chamber 17, and the second partition plate 26 faces the second liquid chamber 18.

[0029] The cylindrical member 21 is a cylindrical part made of metal or synthetic resin. The outer peripheral surface of the cylindrical member 21 is pressed against the small-diameter part 12c of the second member 12 via the film part 14 over the entire circumference. An outer peripheral groove 22 having a length of approximately two turns is formed on the outer peripheral surface of the cylindrical member 21. The first orifice 19 is formed between the outer peripheral groove 22 and the film part 14.

[0030] One end of the outer peripheral groove 22 opens to the inner peripheral surface of the cylindrical member 21 above the first partition plate 23 or to the upper end of the cylindrical member 21, whereby the first orifice 19 communicates with the first liquid chamber 17. The other end of the outer peripheral groove 22 opens to the inner peripheral surface of the cylindrical member 21 below the second partition plate 26 or to the lower end of the cylindrical member 21, whereby the first orifice 19 communicates with the second liquid chamber 18.

[0031] Thus, the first orifice 19 is a flow path that communicates the first liquid chamber 17 and the second liquid chamber 18. The first orifice 19 is set such that, for example, in order to attenuate the shake vibration during vehicle travel, the cross-sectional area, length, cross-sectional perimeter, etc. of the flow path of the first orifice 19 are such that the attenuation coefficient increases in a frequency band (for example, about 5 to 15 Hz) corresponding to the shake vibration when a large-amplitude shake vibration is input.

[0032] The first partition plate 23 is a part made of metal or synthetic resin and is formed in a substantially disc shape perpendicular to the axis C. From the lower surface of the first partition plate 23, a cylindrical first cylindrical wall 23a centered on the axis C projects downward (toward the second partition plate 26).

[0033] A plurality of holes are formed through the first partition plate 23 in the plate thickness direction (vertical direction) inside the first cylindrical wall 23a in the radial direction. Among the plurality of holes, there are one central hole 24a provided on the axis C and a plurality (four in this embodiment) of first valve holes 24b provided around the central hole 24a. The plurality of first valve holes 24b are arranged side by side in the circumferential direction.

[0034] The first partition plate 23 includes an annular first clamping portion 23b that extends radially outward from the first cylindrical wall 23a, a plurality (eight in this embodiment) of connecting portions 23c that extend radially outward and upward from the outer peripheral edge of the first clamping portion 23b, and an annular outer peripheral portion 23d to which the connecting portions 23c are connected at their inner peripheral edges. An annular protrusion 25 centered on the axis C protrudes from the lower surface of the first clamping portion 23b. This protrusion 25 is disposed at the radial center of the first clamping portion 23b and is located at a position radially away from the first cylindrical wall 23a and the connecting portions 23c.

[0035] The plurality of connecting portions 23c are arranged side by side in the circumferential direction. A first through hole 24c that penetrates the first partition plate 23 is formed by a portion surrounded by the outer peripheral edge of the first clamping portion 23b, the connecting portions 23c adjacent in the circumferential direction, and the inner peripheral edge of the outer peripheral portion 23d. A plurality (eight in this embodiment) of these first through holes 24c are also arranged side by side in the circumferential direction.

[0036] A cylindrical portion 23e extends upward from the outer peripheral portion 23d, and a flange 23f extends radially outward from the upper end edge of the cylindrical portion 23e. The cylindrical portion 23e is fitted inside the inner circumference of the cylindrical member 21 until the flange 23f contacts the upper end of the cylindrical member 21. The flange 23f and the upper end of the cylindrical member 21 are joined by a fastening member such as a bolt, welding, adhesion, etc., thereby fixing the first partition plate 23 to the cylindrical member 21.

[0037] The second partition plate 26 is a portion integrally formed with the cylindrical member 21 and is formed in a substantially disk shape perpendicular to the axis C. A cylindrical second cylindrical wall 26a centered on the axis C protrudes upward (toward the first partition plate 23) from a position on the upper surface of the second partition plate 26 that faces the first cylindrical wall 23a. The second cylindrical wall 26a has the same inner and outer diameters as the first cylindrical wall 23a. One second valve hole 27a is formed through the second partition plate 26 in the plate thickness direction (up and down direction) radially inside the second cylindrical wall 26a and on the axis C.

[0038] The second partition plate 26 includes an annular second clamping portion 26b extending radially outward from the second cylindrical wall 26a, a plurality of connecting portions 26c extending radially outward and downward from the outer peripheral edge of the second clamping portion 26b, and an annular outer peripheral portion 26d to which the connecting portions 26c are connected at their inner peripheral edges. An annular protrusion 28 centered on the axis C protrudes from the upper surface of the second clamping portion 26b. This protrusion 28 is disposed at the radial center of the second clamping portion 26b and is located at a position radially away from the second cylindrical wall 26a and the connecting portions 26c. The protrusion 28 and the protrusion 25 face each other in the axial direction.

[0039] The plurality of connecting portions 26c are arranged side by side in the circumferential direction so as to face the plurality of connecting portions 23c of the first partition plate 23 in the axial direction. A second through hole 27c penetrating the second partition plate 26 is formed by a portion surrounded by the outer peripheral edge of the second clamping portion 26b, the connecting portions 26c adjacent to each other in the circumferential direction, and the inner peripheral edge of the outer peripheral portion 26d. A plurality of the second through holes 27c are also arranged side by side in the circumferential direction so as to face the first through holes 24c in the axial direction.

[0040] As shown in FIGS. 1 and 4, the outer peripheral edge of the outer peripheral portion 26d is connected to the inner peripheral surface of the cylindrical member 21 over the entire circumference. Thereby, a predetermined space is formed between the first partition plate 23 and the second partition plate 26. Specifically, this space includes a cylindrical inner space 29a provided inside the first cylindrical wall 23a and the second cylindrical wall 26a, an annular clamping space 29b between the first clamping portion 23b and the second clamping portion 26b, and an accommodation space 29c continuous with the outer peripheral side of the clamping space 29b.

[0041] The inner space 29a and the first liquid chamber 17 are communicated with each other through the central hole 24a and the first valve hole 24b. The inner space 29a and the second liquid chamber 18 are communicated with each other through the second valve hole 27a. The accommodation space 29c is a space that spreads on both the upper and lower sides with respect to the clamping space 29b, and an outer peripheral wall surface 29d is formed by the inner peripheral surface of the cylindrical member 21. The accommodation space 29c and the first liquid chamber 17 are communicated with each other through the first through hole 24c. The accommodation space 29c and the second liquid chamber 18 are communicated with each other through the second through hole 27c.

[0042] As shown in FIGS. 1 and 3, the valve 30 is a member made of an elastic body such as rubber or a thermoplastic elastomer, and is formed in a disk shape centered on the axis C. The valve 30 is housed in the inner space 29a between the first partition plate 23 and the second partition plate 26. The outer peripheral portion of the valve 30 is sandwiched between the first cylindrical wall 23a and the second cylindrical wall 26a over the entire circumference. This sandwiched outer peripheral portion is connected to the switching film 40.

[0043] The valve 30 includes a cylindrical valve portion 31 that protrudes upward from the upper surface toward the first partition plate 23, a cylindrical valve portion 32 that protrudes downward from the lower surface toward the second partition plate 26, and a plurality of ribs 33 that reinforce the cylindrical valve portions 31 and 32. A plurality of valve hole portions 34 that penetrate the valve 30 in the plate thickness direction are formed radially outside the cylindrical valve portions 31 and 32 and radially inside the first cylindrical wall 23a and the second cylindrical wall 26a. The plurality of valve hole portions 34 are arranged in the circumferential direction so as to face the plurality of first valve holes 24b respectively.

[0044] The cylindrical valve portions 31 and 32 are formed in a cylindrical shape centered on the axis C. The outer peripheral surfaces of the cylindrical valve portions 31 and 32 are formed in a tapered shape that decreases in diameter toward the tip. The cylindrical valve portion 31 and the cylindrical valve portion 32 are arranged symmetrically up and down.

[0045] In the unloaded state of the liquid-sealed vibration isolator 10, the cylindrical valve portion 31 contacts the entire circumference radially outside the central hole 24a and radially inside the plurality of first valve holes 24b in the first partition plate 23. Further, in the unloaded state, the cylindrical valve portion 32 contacts the entire circumference radially outside the second valve hole 27a in the second partition plate 26. Thus, in the unloaded state, the movement of the liquid between the first liquid chamber 17 and the second liquid chamber 18 through the inner space 29a is blocked by the valve 30.

[0046] On the other hand, when a large load (vibration with a large amplitude) is input to the liquid-sealed vibration isolator 10 and the first liquid chamber 17 is excessively depressurized as the vibration isolation base 13 deforms, the valve 30 is displaced toward the first partition plate 23 side and the cylindrical valve portion 31 collapses. As a result, the space between the cylindrical valve portion 32 and the second partition plate 26 is separated. As a result, liquid flows from the second liquid chamber 18 into the first liquid chamber 17 through the second valve hole 27a, the inner space 29a, the valve hole portion 34, and the first valve hole 24b. Therefore, excessive negative pressure in the first liquid chamber 17 can be eliminated, and cavitation associated with the negative pressure can be suppressed. The portion that functions in this way is called a cavitation valve.

[0047] When the first liquid chamber 17 is under positive pressure, the force pressing the cylindrical valve portion 32 against the second partition plate 26 only becomes stronger. Therefore, as in the no-load state, the movement of liquid through the inner space 29a is blocked by the valve 30. Furthermore, since the liquid pressure from the first liquid chamber 17 is applied to the center of the valve 30 through the central hole 24a, it is possible to make it difficult for the liquid to leak through the gap between the cylindrical valve portion 32 and the second partition plate 26.

[0048] The ribs 33 project from both the upper and lower surfaces of the valve 30 inside the radial direction of the cylindrical valve portions 31 and 32. Furthermore, the ribs 33 extend radially from the axis C and are connected to the inner peripheral surfaces of the cylindrical valve portions 31 and 32. The ribs 33 can make it difficult for the cylindrical valve portions 31 and 32 to fall over in the radial direction. As a result, it is possible to suppress the leakage of liquid through the gap between the cylindrical valve portion 32 and the second partition plate 26 due to the collapse of the cylindrical valve portions 31 and 32.

[0049] As shown in FIGS. 1 and 4, the switching film 40 is an annular member made of an elastic body such as rubber or thermoplastic elastomer. The valve 30 is connected to the entire circumference of the inner peripheral edge of the switching film 40. The switching film 40 and the valve 30 are integrally molded products. Therefore, the productivity of the switching film 40 and the valve 30 can be improved compared to the case where they are molded separately and then integrated.

[0050] The switching film 40 includes an annular plate portion 41 centered on the axis C, and a pair of cylindrical valve portions 42 and 43 protruding from both sides of the plate portion 41 in the vertical direction (plate thickness direction). The inner peripheral edge of this plate portion 41 is connected to the valve 30. Also, in FIG. 4, the boundary between the plate portion 41 and the valve portions 42 and 43 is indicated by a broken line.

[0051] The plate portion 41 is arranged throughout the entire circumference within the clamping space 29b, and a part of the outer peripheral edge 41c side projects into the accommodation space 29c. The outer peripheral edge 41c of the plate portion 41 faces the outer peripheral wall surface 29d of the accommodation space 29c at a radial interval throughout the entire circumference.

[0052] The plate portion 41 is formed by an annular thick portion 41a from the inner peripheral edge to approximately the center in the radial direction. The thick portion 41a is formed thicker in the vertical direction than the portion on the outer peripheral edge 41c side (outside the thick portion 41a) of the plate portion 41. The thick portion 41a is axially sandwiched between the first clamping portion 23b and the second clamping portion 26b. Further, the thick portion 41a is respectively accommodated between the first cylindrical wall 23a and the protrusion 25, and between the second cylindrical wall 26a and the protrusion 28. Thereby, the switching film 40 is positioned in the vertical direction and the radial direction with respect to the first partition plate 23 and the second partition plate 26.

[0053] A plurality of clamping protrusions 41b project vertically from both the upper and lower surfaces of the plate portion 41. The clamping protrusions 41b are located at positions radially outside the thick portion 41a. The tips of the clamping protrusions 41b contact the vicinity of the outer peripheral edges of the first clamping portion 23b and the second clamping portion 26b. By these clamping protrusions 41b, the plate portion 41 is sandwiched between the first partition plate 23 and the second partition plate 26 near the outer peripheral edge of the clamping space 29b.

[0054] A plurality (16 in this embodiment) of clamping protrusions 41b are arranged side by side in the circumferential direction centered on the axis C (see FIG. 3). Thereby, fluctuations in the hydraulic pressure in the first liquid chamber 17 and the second liquid chamber 18 are applied to the plate portion 41 between the thick portion 41a and the clamping protrusion 41b through the first through hole 24c, the second through hole 27c, the clamping space 29b, and between the plurality of clamping protrusions 41b. When the plate portion 41 at this part deforms according to the fluctuations in the hydraulic pressure, the vibration energy input to the liquid-filled vibration isolator 10 is consumed, and the dynamic spring constant of the liquid-filled vibration isolator 10 can be reduced.

[0055] The valve portion 42 is a conical cylindrical portion that protrudes upward and radially outward from the entire circumference of the outer peripheral edge 41c of the plate portion 41. The outer peripheral surface of the valve portion 42 is formed by an inclined surface 42a that is inclined radially inward toward the center in the vertical direction of the plate portion 41, except for the tip portion. Similarly, the valve portion 43 is a conical cylindrical portion that protrudes downward and radially outward from the entire circumference of the outer peripheral edge 41c of the plate portion 41. The outer peripheral surface of the valve portion 43 is formed by an inclined surface 43a that is inclined radially inward toward the center in the vertical direction of the plate portion 41, except for the tip portion.

[0056] The outer peripheral surface of the switching film 40 is formed by the inclined surfaces 42a and 43a and the outer peripheral edge 41c of the plate portion 41. In the unloaded state, there is a gap over the entire circumference between the outer peripheral surface of this switching film 40 and the outer peripheral wall surface 29d of the accommodation space 29c. Also, in the unloaded state, there is a gap over the entire circumference between the tip portions of the valve portions 42 and 43 and the upper and lower wall surfaces (outer peripheral portions 23d and 26d) of the accommodation space 29c.

[0057] These gaps in the accommodation space 29c, the first through hole 24c, and the second through hole 27c form a second orifice that communicates the first liquid chamber 17 and the second liquid chamber 18. The second orifice is set with the flow path cross-sectional area, length, cross-sectional perimeter, etc. of the second orifice so that the spring constant becomes low in a frequency band (for example, about 15 to 50 Hz) corresponding to the idle vibration when the input of small-amplitude idle vibration is applied, for example, to reduce the idle vibration during idling (when the vehicle is stopped).

[0058] When a hydraulic pressure difference occurs between the first liquid chamber 17 and the second liquid chamber 18 due to the application of a load to the liquid-sealed vibration isolator 10, liquid flow occurs in the second orifice. For example, when liquid flow occurs in the second orifice from the first liquid chamber 17 toward the second liquid chamber 18, the valve portion 42 on the first liquid chamber 17 side deforms so as to fall radially outward. When the hydraulic pressure applied to the valve portion 42 is large, as shown by the two-dot chain line in FIG. 4, the valve portion 42 contacts the outer peripheral wall surface 29d, and the second orifice is blocked. Similarly, when liquid flow occurs in the second orifice from the second liquid chamber 18 toward the first liquid chamber 17 and the valve portion 43 deforms so as to fall radially outward and contacts the outer peripheral wall surface 29d, the second orifice is blocked.

[0059] The state in which the second orifice is blocked in this way is referred to as a blocked state. On the other hand, the state in which both the valve portions 42 and 43 are separated from the outer peripheral wall surface 29d and the second orifice is in communication is referred to as a communication state. In the blocked state of the second orifice, the damping characteristics by the first orifice 19 are mainly exhibited. In the communication state of the second orifice, the damping characteristics of both the first orifice 19 and the second orifice are exhibited. That is, by switching between the communication state and the blocked state of the second orifice, the damping characteristics of the liquid-sealed vibration isolator 10 are switched.

[0060] Here, when the second orifice is blocked by one of the pair of valve portions 42 and 43, the other of the valve portions 42 and 43 does not contribute to the blocking. If the other of the valve portions 42 and 43 that does not contribute is also greatly deformed by the liquid flow, the durability of the valve portions 42 and 43 may be reduced.

[0061] On the other hand, in the present embodiment, the outer peripheral surfaces of the valve portions 42 and 43 are each formed by inclined surfaces 42a and 43a that incline radially inward toward the center in the plate thickness direction of the plate portion 41. Further, each of the inclined surfaces 42a and 43a is provided to extend so as to include not only the outer peripheral surfaces of the valve portions 42 and 43 but also a part of the outer peripheral edge 41c of the plate portion 41. The outer peripheral surface of the switching film 40 including such inclined surfaces 42a and 43a is constricted radially inward in the vicinity of the plate portion 41.

[0062] As a result, one of the pair of valve portions 42 and 43 respectively positioned on both sides of the constriction can be easily tilted radially outward independently of the other. Therefore, when one of the valve portions 42 and 43 blocks the second orifice, deformation of the other of the valve portions 42 and 43 can be suppressed, so that the durability of the valve portions 42 and 43 can be improved.

[0063] The inner peripheral surface 42b of the valve portion 42 is formed substantially parallel along the inclined surface 42a except for the tip portion. That is, the inner peripheral surface 42b is inclined radially inward toward the plate portion 41. Similarly, the inner peripheral surface 43b of the valve portion 43 is formed substantially parallel along the inclined surface 43a except for the tip portion. That is, the inner peripheral surface 43b is inclined radially inward toward the plate portion 41.

[0064] Thereby, the thicknesses (dimensions in the direction perpendicular to the inclined surfaces 42a and 43a) of the valve portions 42 and 43 can be made substantially constant, so that when the valve portions 42 and 43 are tilted, concentration of strain in the thin portions of the valve portions 42 and 43 can be suppressed. As a result, the durability of the valve portions 42 and 43 can be further improved.

[0065] Since the valve portions 42 and 43 having substantially constant thicknesses extend obliquely radially outward from the plate portion 41, the circumferential free lengths of the valve portions 42 and 43 become longer toward the tip portions of the valve portions 42 and 43. Further, when the valve portions 42 and 43 are tilted radially outward, they tend to greatly elongate and deform circumferentially toward the tip portions of the valve portions 42 and 43. Thus, since the original free length is longer in the portion that tends to greatly elongate and deform circumferentially, concentration of strain in a part of the valve portions 42 and 43 can be suppressed, and the durability of the valve portions 42 and 43 can be further improved.

[0066] On the outer peripheral edge 41c side of the inclined surface 42a, a concave portion 42c recessed radially inward is formed. Similarly, on the outer peripheral edge 41c side of the inclined surface 43a, a concave portion 43c recessed radially inward is formed. The valve portion 42 easily tilts with the concave portion 42c as a fulcrum, and the valve portion 43 easily tilts with the concave portion 43c as a fulcrum. Therefore, it becomes difficult for the pair of valve portions 42 and 43 to deform integrally, and the durability of the valve portions 42 and 43 can be further improved.

[0067] Furthermore, the recesses 42c and 43c are formed so as to straddle the outer peripheral surfaces of the valve portions 42 and 43 and the outer peripheral edge 41c of the plate portion 41, respectively. As a result, the valve portions 42 and 43 are more likely to fall from the base (the boundary with the plate portion 41), so the time from when the valve portions 42 and 43 start to fall until they contact the outer peripheral wall surface 29d can be shortened compared to the case where the valve portions 42 and 43 are bent midway. As a result, the switching sensitivity from the communicating state to the blocking state of the second orifice can be improved.

[0068] On the inner peripheral surface 42b of the valve portion 42, a convex portion 42d that bulges the radially opposite side of the recess 42c radially inward is provided. On the inner peripheral surface 43b of the valve portion 43, a convex portion 43d that bulges the radially opposite side of the recess 43c radially inward is provided. As a result, even when the recesses 42c and 43c are provided, the thicknesses of the valve portions 42 and 43 can be made closer to being substantially constant by the convex portions 42d and 43d. As a result, when the valve portions 42 and 43 are deformed, it is possible to suppress the concentration of strain in the vicinity of the recesses 42c and 43c and the reduction in the durability of the valve portions 42 and 43.

[0069] In particular, the convex portions 42d and 43d are provided so as to extend toward the tip end side of the valve portions 42 and 43 and up to the boundary with the plate portion 41, rather than at the position where the recesses 42c and 43c are projected in the width direction of the valve portions 42 and 43. As a result, when the valve portions 42 and 43 fall with the recesses 42c and 43c as fulcrums, the free length in the vicinity of the convex portions 42d and 43d that mainly undergo elongation deformation can be ensured, so the concentration of strain in the vicinity can be suppressed. Therefore, the durability of the valve portions 42 and 43 can be further improved.

[0070] The shortest distance L1 from the portion where the plate portion 41 is sandwiched between the first partition plate 23 and the second partition plate 26 to the valve portions 42 and 43 is shortened by the contact between the sandwiching protrusion 41b and the first partition plate 23 or the second partition plate 26. This shortest distance L1 is less than or equal to half of the length L2 in the protruding direction (the direction perpendicular to the width direction) of the valve portions 42 and 43. The length L2 is the dimension from the plate portion 41 to the tip end portions of the valve portions 42 and 43 at the center in the width direction of the valve portions 42 and 43.

[0071] According to such dimensional relationships, it is possible to suppress the plate portion 41 from being bent up and down by the liquid flow in the second orifice between the portion of the plate portion 41 sandwiched between the first partition plate 23 and the second partition plate 26 and the valve portions 42 and 43. That is, it is possible to suppress the switching film 40 from being displaced entirely in the vertical direction in the accommodation space 29c due to the liquid flow, and only the valve portions 42 and 43 can be easily tilted.

[0072] The first through hole 24c and the second through hole 27c open into the accommodation space 29c at positions radially opposed to the inner peripheral surfaces 42b and 43b of the valve portions 42 and 43. Therefore, the valve portions 42 and 43 can be tilted in the same direction as the flow of the liquid flowing out from the first through hole 24c and the second through hole 27c into the accommodation space 29c. As a result, the valve portions 42 and 43 can be quickly brought into contact with the outer peripheral wall surface 29d, so that the switching sensitivity from the communication state to the blocking state of the second orifice can be improved.

[0073] Furthermore, the first through hole 24c and the second through hole 27c open into the accommodation space 29c at positions radially opposed to the tip portions of the valve portions 42 and 43. Therefore, the liquid pressure from the first through hole 24c and the second through hole 27c is easily applied to the tip portions of the valve portions 42 and 43, so that the valve portions 42 and 43 can be easily tilted from the root by the lever principle. As a result, the valve portions 42 and 43 can be brought into contact with the outer peripheral wall surface 29d more quickly, so that the switching sensitivity from the communication state to the blocking state of the second orifice can be further improved.

[0074] Next, a second embodiment will be described with reference to FIG. 5. In the first embodiment, the case where the wall surfaces on the plate portion 41 side of the first through hole 24c and the second through hole 27c are substantially parallel to the radial direction has been described. In contrast, in the second embodiment, the case where the wall surfaces 51 and 52 on the plate portion 41 side of the first through hole 24c and the second through hole 27c are inclined with respect to the radial direction 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 will be omitted.

[0075] FIG. 5 is a partially enlarged cross-sectional view of the liquid-filled vibration isolator 50 in the second embodiment. The cross-sectional view of FIG. 5 is a cross-sectional view at the same position as that of FIG. 4. The liquid-filled vibration isolator 50 is configured substantially the same as the liquid-filled vibration isolator 10 of the first embodiment, except for the wall surfaces 51 and 52 on the plate portion 41 side of the first through hole 24c and the second through hole 27c.

[0076] The wall surface 51 of the first through hole 24c is the outer edge portion of the upper surface of the first clamping portion 23b, and is inclined toward the plate portion 41 side (lower side) as it goes radially outward. The wall surface 52 of the second through hole 27c is the outer edge portion of the lower surface of the second clamping portion 26b, and is inclined toward the plate portion 41 side (upper side) as it goes radially outward. As a result, the flow of the liquid flowing out from the first through hole 24c and the second through hole 27c into the accommodation space 29c acts substantially perpendicular to the inner peripheral surfaces 42b and 43b of the valve portions 42 and 43, so that the valve portions 42 and 43 can be quickly brought into contact with the outer peripheral wall surface 29d. As a result, the switching sensitivity from the communicating state to the blocking state of the second orifice can be improved.

[0077] Furthermore, if the angle formed by the inner peripheral surface 42b and the wall surface 51 and the angle formed by the inner peripheral surface 43b and the wall surface 52 are within the range of 70 to 110°, the direction of the liquid flow from the first through hole 24c and the second through hole 27c and the inner peripheral surfaces 42b and 43b approach more perpendicularly. Therefore, the valve portions 42 and 43 can be brought into contact with the outer peripheral wall surface 29d more quickly, and the switching sensitivity from the communicating state to the blocking state of the second orifice can be further improved.

[0078] Next, the third embodiment will be described with reference to FIG. 6. In the first embodiment, the case where the valve portions 42 and 43 extend obliquely radially outward from the plate portion 41 has been described. In contrast, in the third embodiment, the case where the valve portions 62 and 63 rise substantially perpendicularly from the plate portion 41 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.

[0079] FIG. 6 is a partially enlarged cross-sectional view of the liquid-filled vibration isolator 60 in the third embodiment. The cross-sectional view of FIG. 6 is a cross-sectional view at the same position as in FIG. 4. The liquid-filled vibration isolator 60 is configured substantially the same as the liquid-filled vibration isolator 10 of the first embodiment, except for the switching film 61.

[0080] The switching film 61 includes an annular plate portion 41 and a pair of cylindrical valve portions 62 and 63 that project from both sides of the plate portion 41 in the plate thickness direction (vertical direction). In FIG. 6, the boundary between the plate portion 41 and the valve portions 62 and 63 is indicated by a broken line.

[0081] The valve portion 62 is a cylindrical portion that projects substantially vertically upward from the entire circumference of the outer peripheral edge 41c of the plate portion 41. The outer peripheral surface 62a and the inner peripheral surface 62b of the valve portion 62 are parallel to each other and to the vertical direction, and the thickness (dimension in the radial direction) of the valve portion 62 is substantially constant. The valve portion 63 is a cylindrical portion that projects substantially vertically downward from the entire circumference of the outer peripheral edge 41c of the plate portion 41. The outer peripheral surface 63a and the inner peripheral surface 63b of the valve portion 63 are parallel to each other and to the vertical direction, and the thickness (dimension in the radial direction) of the valve portion 63 is substantially constant.

[0082] On the outer peripheral surfaces of the switching film 61 including these outer peripheral surfaces 62a and 63a and the outer peripheral edge 41c of the plate portion 41, inclined surfaces 64 and 65 that incline radially inward toward the center in the plate thickness direction of the plate portion 41 are formed at positions including the outer peripheral edge 41c, respectively. The inclined surface 64 is formed from a part on the base side of the outer peripheral surface 62a to the center in the plate thickness direction of the outer peripheral edge 41c. The inclined surface 65 is formed from a part on the base side of the outer peripheral surface 63a to the center in the plate thickness direction of the outer peripheral edge 41c. That is, the outer peripheral surface of the switching film 61 is constricted radially inward in the vicinity of the plate portion 41 by the inclined surfaces 64 and 65.

[0083] Thus, also in the third embodiment, as in the first embodiment, one of the pair of valve portions 62 and 63 can be easily tilted radially outward independently of the other. Therefore, when one of the valve portions 62 and 63 shuts off the second orifice, deformation of the other of the valve portions 62 and 63 can be suppressed, so that the durability of the valve portions 62 and 63 can be improved.

[0084] Note that the inclined surfaces 64 and 65 only need to be formed at least on the outer peripheral edge 41c, and do not necessarily need to be formed on the outer peripheral surfaces 62a and 63a of the valve parts 62 and 63. Even in this case, one of the pair of valve parts 62 and 63 can be easily tilted radially outward independently of the other, and the durability of the valve parts 62 and 63 can be improved.

[0085] However, since the inclined surfaces 64 and 65 are formed up to the outer peripheral surfaces 62a and 63a, it is easy to make the deformation of one of the pair of valve parts 62 and 63 independent of the deformation of the other. As a result, the durability of the valve parts 62 and 63 can be further improved.

[0086] Further, when the inclined surfaces 64 and 65 are formed up to the outer peripheral surfaces 62a and 63a, although not shown, convex portions 42d and 43d similar to those in the first embodiment may be provided so as to bulge the inner peripheral surfaces 62b and 63b on the radially opposite side to the inclined surfaces 64 and 65. Thereby, even when the inclined surfaces 64 and 65 are provided on the valve parts 62 and 63 having a substantially constant thickness, the thickness of the valve parts 62 and 63 can be kept substantially constant. As a result, when the valve parts 62 and 63 are deformed, it is possible to suppress the concentration of strain in the vicinity of the inclined surfaces 64 and 65 and the decrease in the durability of the valve parts 62 and 63.

[0087] The shortest distance L3 from the portion (clamping protrusion 41b) where the plate portion 41 is sandwiched between the first partition plate 23 and the second partition plate 26 to the valve parts 62 and 63 is equal to or less than the length L4 in the protruding direction (vertical direction) of the valve parts 62 and 63. Thereby, similarly to the first embodiment, it is possible to suppress the entire switching film 61 from being displaced in the vertical direction in the accommodation space 29c due to the liquid flow in the second orifice, and it is possible to easily tilt only the valve parts 62 and 63.

[0088] Next, a fourth embodiment will be described with reference to FIG. 7. In the first embodiment, the case where the inner peripheral edge side of the annular switching film 40 is sandwiched between the first partition plate 23 and the second partition plate 26 has been described. In contrast, in the fourth embodiment, the case where the outer peripheral edge side of the annular switching film 80 is sandwiched between the first partition plate 71 and the second partition plate 73 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.

[0089] FIG. 7 is a cross-sectional view of a partition member 70 of the liquid-filled vibration isolator according to the fourth embodiment. The cross-sectional view of FIG. 7 is a cross-sectional view including the axis C. The partition member 70 is assembled to the liquid-filled vibration isolator 10 in place of the partition member 20 in the first embodiment.

[0090] The partition member 70 includes a cylindrical member 21, flat plate-shaped first partition plate 71 and second partition plate 73 that vertically partition the inner peripheral side of the cylindrical member 21, and a switching film 80 disposed between the first partition plate 71 and the second partition plate 73. The first partition plate 71 faces the first liquid chamber 17, and the second partition plate 73 faces the second liquid chamber 18.

[0091] The first partition plate 71 is a part made of metal or synthetic resin, and is formed in a substantially disc shape perpendicular to the axis C. The first partition plate 71 includes an annular plate-shaped first clamping portion 71a that constitutes the outer peripheral side of the first partition plate 71, a plurality of connecting portions 71b that extend radially inward and upward from the inner peripheral edge of the first clamping portion 71a, and a disc-shaped inner peripheral portion 71c to which the connecting portions 71b are connected at the outer peripheral edge.

[0092] From the outer peripheral edge of the first clamping portion 71a, a cylindrical portion 23e extends upward, and a flange 23f extends radially outward from the upper end edge of the cylindrical portion 23e. From the lower surface of the first clamping portion 71a, an annular protrusion 74 that centers on the axis C protrudes. This protrusion 74 is provided from the radial center to the inner peripheral edge of the first clamping portion 71a.

[0093] The plurality of connecting portions 71b are arranged side by side in the circumferential direction. A first through hole 71d that penetrates the first partition plate 71 is formed by a portion surrounded by the inner peripheral edge of the first clamping portion 71a, the connecting portions 71b adjacent in the circumferential direction, and the outer peripheral edge of the inner peripheral portion 71c. A plurality of the first through holes 71d are also arranged side by side in the circumferential direction.

[0094] The second partition plate 73 is a part integrally formed with the cylindrical member 21 and is formed in a disc shape perpendicular to the axial center C. The second partition plate 73 includes an annular second clamping portion 73a extending radially inward from the inner peripheral surface of the cylindrical member 21, a plurality of connecting portions 73b extending radially inward and downward from the inner peripheral edge of the second clamping portion 73a, an annular inner peripheral portion 73c to which the connecting portions 73b are connected at the outer peripheral edge, a cylindrical cylindrical portion 73d extending upward from the inner peripheral edge of the inner peripheral portion 73c, and a disc-shaped disc portion 73e closing the upper end of the cylindrical portion 73d. An annular protrusion 75 centered on the axial center C protrudes from the lower surface of the second clamping portion 73a. This protrusion 75 is provided from the radial center to the inner peripheral edge of the second clamping portion 73a.

[0095] The plurality of connecting portions 73b are arranged side by side in the circumferential direction so as to face the connecting portions 71b of the first partition plate 71 in the axial direction. A second through hole 73f penetrating the second partition plate 73 is formed by a portion surrounded by the inner peripheral edge of the second clamping portion 73a, the connecting portions 73b adjacent to each other in the circumferential direction, and the outer peripheral edge of the inner peripheral portion 73c. A plurality of these second through holes 73f are also arranged side by side in the circumferential direction so as to face the first through hole 71d in the axial direction.

[0096] The inner peripheral portion 71c of the first partition plate 71 is overlapped on the upper surface of the disc portion 73e, and the first partition plate 71 and the second partition plate 73 are joined by welding or adhesion. In this joined state, a predetermined space is formed between the first partition plate 71 and the second partition plate 73. Specifically, this space includes an annular clamping space 76 between the first clamping portion 71a and the second clamping portion 73a, and an accommodation space 77 continuous with the inner peripheral side of the clamping space 76.

[0097] The accommodation space 77 is a space that spreads to both the upper and lower sides with respect to the clamping space 76, and an inner peripheral wall surface 78 is formed by the outer peripheral surface of the cylindrical portion 73d. The accommodation space 77 and the first liquid chamber 17 (see FIG. 1) are communicated by the first through hole 71d. The accommodation space 77 and the second liquid chamber 18 (see FIG. 1) are communicated by the second through hole 73f.

[0098] The switching film 80 is an annular member composed of an elastic body such as rubber or a thermoplastic elastomer. The switching film 80 includes an annular plate portion 81 centered on the axis C, and a pair of cylindrical valve portions 82 and 83 protruding from both sides of the plate portion 81 in the vertical direction (plate thickness direction).

[0099] The plate portion 81 is disposed throughout the entire circumference within the clamping space 76, and a part of the inner peripheral edge 81c side protrudes into the accommodation space 77. The inner peripheral edge 81c of the plate portion 81 faces the inner peripheral wall surface 78 of the accommodation space 77 at a radial interval throughout the entire circumference.

[0100] The plate portion 81 is formed by an annular thick portion 81a from the outer peripheral edge to approximately the center in the radial direction. The thick portion 81a is formed thicker vertically with respect to the portion on the inner peripheral edge 81c side (other than the thick portion 81a) of the plate portion 81. The thick portion 81a is axially sandwiched between the first clamping portion 71a and the second clamping portion 73a. Further, the thick portion 81a is accommodated between the inner peripheral surface of the cylindrical member 21 and the protrusions 74 and 75, and the plate portion 81 other than the thick portion 81a is also axially sandwiched between the protrusions 74 and 75. Thereby, the switching film 80 fills substantially the entire clamping space 76 and is positioned in the vertical direction and the radial direction with respect to the first partition plate 71 and the second partition plate 73.

[0101] The valve portion 82 is a conical cylindrical portion protruding upward and radially inward from the entire circumference of the inner peripheral edge 81c of the plate portion 81. The valve portion 82 is obtained by inverting the inner and outer sides in the radial direction with respect to the valve portion 42 of the first embodiment. That is, the inclined surface 82a, the outer peripheral surface 82b, the concave portion 82c, and the convex portion 82d of the valve portion 82 are obtained by inverting the inclined surface 42a, the inner peripheral surface 42b, the concave portion 42c, and the convex portion 42d of the valve portion 42, respectively.

[0102] Similarly, the valve portion 83 is a conical tubular portion that projects downward and radially inward from the entire circumference of the inner peripheral edge 81c of the plate portion 81. The valve portion 83 is obtained by inverting the inner and outer sides in the radial direction with respect to the valve portion 43 of the first embodiment. That is, the inclined surface 83a, the outer peripheral surface 83b, the concave portion 83c, and the convex portion 83d of the valve portion 83 are obtained by inverting the inclined surface 43a, the inner peripheral surface 43b, the concave portion 43c, and the convex portion 43d of the valve portion 43, respectively, inside and outside.

[0103] In addition, the accommodation space 77, the inner peripheral wall surface 78, the first through hole 71d, the second through hole 73f, and the second orifice are also obtained by inverting the inner and outer sides in the radial direction with respect to the accommodation space 29c, the outer peripheral wall surface 29d, the first through hole 24c, the second through hole 27c, and the second orifice of the first embodiment.

[0104] Therefore, according to the liquid-filled vibration isolator of the fourth embodiment, the same effects as those of the liquid-filled vibration isolator 10 of the first embodiment are achieved. For example, specifically, the inner peripheral surfaces of the valve portions 82 and 83 are respectively formed by inclined surfaces 82a and 83a that incline radially outward toward the center in the plate thickness direction of the plate portion 81. Further, each of the inclined surfaces 82a and 83a is provided to extend so as to include not only the inner peripheral surfaces of the valve portions 82 and 83 but also a part of the inner peripheral edge 81c of the plate portion 81. The inner peripheral surface of the switching film 80 including such inclined surfaces 82a and 83a is constricted radially inward in the vicinity of the plate portion 81.

[0105] As a result, it is possible to easily tilt one of the pair of valve portions 82 and 83 located on both sides of the constriction radially inward independently of the other. Therefore, when one of the valve portions 82 and 83 shuts off the second orifice, deformation of the other of the valve portions 82 and 83 can be suppressed, so that the durability of the valve portions 82 and 83 can be improved.

[0106] As described above, the present invention has been described based on the embodiments. However, it can be easily inferred that the present invention is not limited to the above embodiments at all, and various improvements and modifications are possible without departing from the spirit of the present invention. For example, the number of the first through hole 24c, the second through hole 27c, the sandwiching protrusion 41b, etc. may be appropriately changed.

[0107] The first member 11 may be disposed at a position offset radially from the axis C. Also, the axis C of the second member 12 and the axis C of the valve 30, switching membranes 40, 61, 80, accommodation spaces 29c, 77, etc. may be offset.

[0108] The formation position, length, etc. of the first orifice 19 may be appropriately changed. A liquid chamber different from the first liquid chamber 17 and the second liquid chamber 18 may be formed inside the partition bodies 20, 70, etc. The two liquid chambers may be communicated by an orifice different from the first orifice 19. The first orifice 19 may be omitted.

[0109] A cup-shaped cap fitting may be provided at the lower portion of the diaphragm 15 (on the side opposite to the first liquid chamber 17 and the second liquid chamber 18), and an air chamber may be formed by the inner surface of the cap fitting and the diaphragm 15. This air chamber may be made into a sealed space to have an air spring effect. A through hole may be provided in a part of the cap fitting to open the air chamber to the atmosphere, and a damping effect by the air passing through the through hole may be added to the liquid-filled vibration isolators 10, 50, 60.

[0110] In the above embodiment, an engine mount was exemplified as an application target of the liquid-filled vibration isolators 10, 50, 60, but the application target is arbitrary. Other application targets include, for example, motor mounts, member mounts, and differential mounts. Also, it is not limited to the case where the first member 11 is attached to the vibration source side such as an engine and the second member 12 is attached to the vibration receiving side such as a vehicle body. The second member 12 may be attached to the vibration source side and the first member 11 may be attached to the vibration receiving side.

[0111] In the above embodiment, the case where a part of the chamber wall of the first liquid chamber 17 is constituted by the vibration isolation base 13 and a part of the chamber wall of the second liquid chamber 18 is constituted by the diaphragm 15 was described, but it is not necessarily limited to this. For example, the second liquid chamber 18 may be referred to as the first liquid chamber, and the first liquid chamber 17 may be referred to as the second liquid chamber.

[0112] Some parts of the above embodiments may be omitted. For example, the film part 14 may be omitted, and the partition bodies 20, 70 and the diaphragm 15 may be attached to the inner peripheral surface of the second member 12. The connection part between the valve 30 and the switching film 40 may be omitted, and they may be independent. The valve 30 or the inner space 29a may be omitted. In this case, the inner edge side of the switching film 40 may be blocked, and the switching film 40 may be formed in a disc shape.

[0113] Some parts of the above embodiments may be combined with some parts of other embodiments. For example, the valve 30, the inner space 29a, etc. in the first embodiment may be provided on the inner peripheral side of the cylindrical part 73d in the fourth embodiment. The wall surfaces 51, 52 of the second embodiment with the inner and outer sides in the radial direction reversed may be provided in the fourth embodiment. The valve parts 82, 83 in the fourth embodiment may be projected substantially perpendicularly from the plate part 81 as in the third embodiment.

[0114] Like the protrusion parts 74, 75 in the fourth embodiment, the protrusion parts 25, 28 such as in the first embodiment may be provided up to the outer peripheral edges of the first clamping part 23b and the second clamping part 26b, and the clamping protrusion 41b may be omitted. Also, the protrusion parts 25, 28, 74, 75 and the clamping protrusion 41b may be omitted, and the thick part 41a may be provided up to the outer peripheral edge of the clamping space 29b, or the thick part 81a may be provided up to the inner peripheral edge of the clamping space 76.

[0115] In the above embodiments, the case where a plurality of clamping protrusions 41b are arranged in the circumferential direction has been described, but it is not necessarily limited to this. The clamping protrusion 41b may be an annular member continuous over the entire circumference around the axis C. The clamping protrusion 41b may be omitted.

[0116] In the above embodiments, the cases where the valve parts 42, 43, 62, 63, 82, 83 are conical cylindrical or cylindrical have been described, but it is not necessarily limited to this. The valve parts 42, 43, 62, 63, 82, 83 may be cylindrical (annular in a cross-section perpendicular to the axis C). For example, in a cross-section perpendicular to the axis C, the valve parts 42, 43, 62, 63, 82, 83 may be annular such as a polygon, an ellipse, or an oblong.

Explanation of Reference Numerals

[0117] Liquid-sealed vibration isolator for 10, 50, 60 11 First member 12 Second member 13 Vibration isolation base 15 Diaphragm 17 First liquid chamber 18 Second liquid chamber 20, 70 Partition body 23, 71 First partition plate 24c, 71d First through hole (part of orifice) 26, 73 Second partition plate 27c, 73f Second through hole (part of orifice) 29c, 77 Accommodation space (part of orifice) 29d Outer peripheral wall surface 40, 61, 80 Switching film 41, 81 Plate part 41c Outer peripheral edge 42, 43, 62, 63, 82, 83 Valve part 42a, 43a, 64, 65, 82a, 83a Inclined surface 42b, 43b, 62b, 63b Inner peripheral surface of valve part 42c, 43c Concave part 42d, 43d Convex part 51, 52 Wall surface 62a, 63a, 82b, 83b Outer peripheral surface of valve part 78 Inner peripheral wall surface 81c Inner peripheral edge

Claims

1. a first member and a cylindrical second member; a vibration isolation base made of an elastic body that connects the first member and the second member; a diaphragm made of an elastic body that is attached to the second member and forms a liquid chamber in which a liquid is enclosed between the vibration isolation base; a partition body that partitions the liquid chamber into a first liquid chamber and a second liquid chamber; an orifice formed in the partition body that communicates the first liquid chamber and the second liquid chamber; a switching film made of an elastic body that switches between a communicating state and a blocking state of the orifice, and the partition body includes a first partition plate facing the first liquid chamber, a second partition plate facing the second liquid chamber, the orifice is formed by an annular accommodation space formed between the first partition plate and the second partition plate, a plurality of first through holes formed through the first partition plate to communicate the first liquid chamber and the accommodation space, and a plurality of second through holes formed through the second partition plate to communicate the second liquid chamber and the accommodation space; the switching film has an outer peripheral edge that faces the outer peripheral wall surface of the accommodation space in the radial direction over the entire circumference, and a plate portion that is sandwiched between the first partition plate and the second partition plate so that the outer peripheral edge side protrudes into the accommodation space; a pair of cylindrical valve portions protruding from the entire circumference of the outer peripheral edge of the plate portion toward both sides in the plate thickness direction of the plate portion, and in the communicating state, a space is formed between the valve portion and the outer peripheral wall surface; in the blocking state, the valve portion deformed radially outward contacts the outer peripheral wall surface, thereby blocking the orifice; a liquid-filled vibration isolation device, characterized in that an inclined surface that inclines radially inward toward the center in the plate thickness direction of the plate portion is formed at least at a position including the outer peripheral edge on the outer peripheral surface of the switching film including the outer peripheral edge and the outer peripheral surface of the valve portion.

2. The liquid-filled vibration isolation device according to claim 1, wherein the outer peripheral surface of the valve portion is formed by the inclined surface, and the inner peripheral surface of the valve portion inclines along the inclined surface.

3. The liquid-filled vibration isolation device according to claim 2, characterized in that a recess recessed radially inward is formed on the outer peripheral edge side of the inclined surface.

4. The liquid-filled vibration isolation device according to claim 3, characterized in that a convex portion that bulges radially inward on the side opposite to the recess in the radial direction is provided on the inner peripheral surface of the valve portion.

5. The liquid-filled vibration isolator according to claim 3, wherein the concave portion is formed across the outer peripheral surface of the valve portion and the outer peripheral edge of the plate portion.

6. The first through hole and the second through hole each open into the accommodation space at a position radially opposed to the inner peripheral surface of the valve portion, The liquid-filled vibration isolator according to claim 2, wherein the wall surfaces on the plate portion side of the first through hole and the second through hole are each inclined toward the plate portion side as they extend radially outward.

7. The liquid-filled vibration isolator according to any one of claims 1 to 6, wherein the shortest distance from the portion of the plate portion sandwiched between the first partition plate and the second partition plate to the valve portion is half or less of the length of the valve portion in the protruding direction.

8. A first member and a cylindrical second member, A vibration isolation base body made of an elastic body that connects the first member and the second member, A diaphragm made of an elastic body that is attached to the second member and forms a liquid chamber in which a liquid is sealed between the diaphragm and the vibration isolation base body, A partition body that partitions the liquid chamber into a first liquid chamber and a second liquid chamber, An orifice formed in the partition body that communicates the first liquid chamber and the second liquid chamber, An elastic switching film that switches between a communicating state and a blocking state of the orifice, and The partition body includes a first partition plate facing the first liquid chamber, A second partition plate facing the second liquid chamber, The orifice is formed by an annular accommodation space formed between the first partition plate and the second partition plate, a plurality of first through holes formed through the first partition plate to communicate the first liquid chamber and the accommodation space, and a plurality of second through holes formed through the second partition plate to communicate the second liquid chamber and the accommodation space, The switching film has an inner peripheral edge that faces the inner peripheral wall surface of the accommodation space over the entire circumference, and an annular plate portion that is sandwiched between the first partition plate and the second partition plate so that the inner peripheral edge side protrudes into the accommodation space, The plate portion includes a pair of cylindrical valve portions that protrude from the entire circumference of the inner peripheral edge of the plate portion toward both sides in the plate thickness direction of the plate portion, In the communicating state, a space is formed between the valve portion and the inner peripheral wall surface, In the blocking state, the orifice is blocked when the valve portion deformed radially inward contacts the inner peripheral wall surface. A liquid-sealed vibration isolator, characterized in that an inclined surface that inclines radially outward toward the center in the plate thickness direction of the plate portion is formed at least at a position including the inner peripheral edge on the inner peripheral surface of the switching film including the inner peripheral edge and the inner peripheral surface of the valve portion.

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