Fluid filled vibration damping device Number:7,419,144 from the United States Patent and Trademark Office (PTO) owispatent A fluid filled vibration damping device wherein a first and second mounting member are connected by a main rubber elastic body, a pressure receiving chamber partially formed by the rubber elastic body and an equilibrium chamber partially formed by a flexible film are formed on either side of a partition member supported by the second mounting member, an orifice passage is formed for permitting a fluid communication between the pressure receiving chamber and equilibrium chamber communicate both having a non-compressible fluid; and a movable rubber plate is housed in a housing space so that minute pressure fluctuations in the pressure receiving chamber can be absorbed by the equilibrium chamber by means of the movable rubber plate. The movable rubber plate includes at least partially a corrugated part expanding generally a form of a corrugated panel by means of continuous depressions and protrusions.<H vibration, damping, Fluid, filled, vi, 7419144.html, Patent, pto, 7419144

Title: Fluid filled vibration damping device

Abstract: A fluid filled vibration damping device wherein a first and second mounting member are connected by a main rubber elastic body, a pressure receiving chamber partially formed by the rubber elastic body and an equilibrium chamber partially formed by a flexible film are formed on either side of a partition member supported by the second mounting member, an orifice passage is formed for permitting a fluid communication between the pressure receiving chamber and equilibrium chamber communicate both having a non-compressible fluid; and a movable rubber plate is housed in a housing space so that minute pressure fluctuations in the pressure receiving chamber can be absorbed by the equilibrium chamber by means of the movable rubber plate. The movable rubber plate includes at least partially a corrugated part expanding generally a form of a corrugated panel by means of continuous depressions and protrusions.

Patent Number: 7,419,144 Issued on 09/02/2008 to Hasegawa, et al.

Inventors: Hasegawa; Koichi (Kasugai, JP), Yoshii; Noriaki (Nagoya, JP)
Assignee: Tokai Rubber Industries, Ltd. (Komaki, JP)

Appl. No.: 11/236,762

Filed: September 28, 2005

Foreign Application Priority Data


Sep 30, 2004 [JP]			2004-286205

Current U.S. Class: 267/140.13 ; 267/219

Current International Class: F16F 13/10 (20060101)

Field of Search: 267/140.13,140.14,140.15,219

References Cited [Referenced By]

U.S. Patent Documents


4647023	March 1987	Ray et al.
4738435	April 1988	Flower et al.
4742999	May 1988	Flower
4773634	September 1988	Hamaekers
4815720	March 1989	Vanessi
4974818	December 1990	Kato
5104100	April 1992	Simuttis
5443245	August 1995	Bellamy et al.
6485005	November 2002	Tewani et al.
6637734	October 2003	Thomazeau et al.
2003/0168789	September 2003	Kries et al.

Foreign Patent Documents


2 674 590	Oct., 1992	FR
2 341 908	Mar., 2000	GB
62-147139	Jul., 1987	JP
5-34535	Feb., 1989	JP
4-33478	Aug., 1992	JP
5-34535	May., 1993	JP
2569561	Jan., 1998	JP

Primary Examiner: Williams; Thomas J
Attorney, Agent or Firm: Oliff & Berridge, PLC

Claims

What is claimed is:

1. A fluid filled vibration damping device comprising: a first mounting member; a second mounting member; a main rubber elastic body elastically connecting the first and second mounting members; a pressure receiving chamber whose wall is partially formed by the rubber elastic body to accommodate pressure fluctuations during vibration input; an equilibrium chamber whose wall is partially formed by a flexible film to accommodate changes in volume; the pressure receiving chamber and the equilibrium chamber being disposed on either side of a partition member supported by the second mounting member, and having a non-compressible fluid sealed therein; an orifice passage through which the pressure receiving chamber and equilibrium chamber communicate with each other; a movable panel housed in a housing space that is provided in the partition member and held in communication with the pressure receiving chamber and the equilibrium chamber via through holes formed through the partition member so that a pressure of the pressure receiving chamber is exerted onto one side of the movable panel and a pressure in the equilibrium chamber is exerted onto another side of the movable panel, wherein minute pressure fluctuations in the pressure receiving chamber during vibration input can be escaped into and absorbed by the equilibrium chamber by means of the movable panel, the movable panel is composed of a movable rubber plate formed by a rubber elastic body, and includes at least partially a corrugated part which expands in generally a form of a corrugated panel by means of continuous depressions and protrusions, the movable rubber plate has at a central portion thereof a circular flat plate portion, and at a peripheral portion thereof an annular plate portion that constitutes the corrugated part and is formed in a curved and undulating shape so as to be corrugated in a thicknesswise direction in a circumferential direction along an entire circumference thereof, wherein a center portion in the thicknesswise direction of the annular plate portion oscillates vertically in the circumferential direction.

2. A fluid filled vibration damping device according to claim 1, wherein a height of undulations in a thicknesswise direction of the movable rubber plate between the protrusions on one side and the protrusions on another side of the corrugated part of the movable rubber plate is greater than a distance between vertically opposite inner surfaces in the housing space, and the movable rubber plate thickness at each location of the corrugated part is less than the distance between the vertically opposite inner surfaces in the housing space, so that all the protrusions on both sides of the corrugated part are in contact with the inner surfaces of the housing space, and all the depressions on both sides of the corrugated part are apart from the inner surfaces of the housing space, forming a gap therebetween.

3. A fluid filled vibration damping device according to claim 1, wherein a positioning member is disposed for positioning the movable rubber plate relative to the partition member to locate the movable rubber plate in generally a center inside the housing space in a direction perpendicular to a thicknesswise direction.

4. A fluid filled vibration damping device according to claim 3, wherein the positioning member comprises a positioning engagement portion formed generally on center on at least one side of the movable rubber plate in order to position the movable rubber plate relative to the partition member.

5. A fluid filled vibration damping device according to claim 1, wherein the corrugated part has a shock-absorbing lip protrusion integrally formed at a surface in contact with at least one of vertically opposite inner surfaces of the housing space.

6. A fluid filled vibration damping device according to claim 1, wherein the flat plate portion and corrugated part both have integrally formed shock-absorbing lip protrusions on both sides in a thicknesswise direction of the movable rubber plate, which are in contact in a pre-compressed state with inner surfaces of the housing space.

7. A fluid filled vibration damping device according to claim 1, wherein the movable rubber plate has the corrugated part along substantially an entirety thereof.

8. A fluid filled vibration damping device according to claim 1 wherein the movable rubber plate is micro-displaceably disposed in the housing space in a thicknesswise direction of the movable rubber plate with a given amount of gap all a way around, and the corrugated part, on at least one side of the movable rubber plate, initially strikes an inner surface of the housing space when the movable rubber plate is displaced and strikes the inner surface of the housing space at the partition member.

9. A fluid-filled vibration damping device according to claim 1, wherein a height of undulations in a thicknesswise direction of the movable rubber plate between the protrusions on one side and the protrusions on the other side of the corrugated part of the movable rubber plate is less than a distance between vertically opposite inner surfaces in the housing space, so that the corrugated part of the movable rubber plate is displaceably housed, with a given amount of gap in the thicknesswise direction of the movable rubber plate, and the corrugated part is displaced in the thicknesswise direction of the movable rubber plate into contact with the inner surface of the space.

10. A fluid filled vibration damping device according to claim 1, wherein the second mounting member is generally cylindrical, the first mounting member is disposed apart from the second mounting member, an opening at one end of the second mounting member is fluid-tightly sealed by the main rubber elastic body that elastically connects the first and second mounting members, an opening at the other end of the second mounting member is fluid-tightly sealed by the flexible film, the partition member fixedly supports the second mounting member, being disposed so as to expand perpendicularly to an axis of the second mounting member between facing surfaces of the main rubber elastic body and flexible film, so that the pressure receiving chamber and equilibrium chamber are formed on either side of the partition member, the housing space is formed so as to expand perpendicularly to the axis of the second mounting member inside the partition member, and the movable rubber plate is housed in the housing space so as to expand perpendicularly to the axis of the second mounting member.

11. A fluid filled vibration damping device according to claim 1, wherein the circular flat plate portion is a disk-shaped center flat panel portion; the annular plate portion is a disk-shaped outer peripheral annular portion; and an annular thin connector is interposed between and elastically connects the center flat panel portion and the outer peripheral annular portion.

12. A fluid filled vibration damping device according to claim 1, wherein the peripheral portion is altered with substantially no change in a radial cross section shape and size.

Description

INCORPORATED BY REFERENCE

The disclosure of Japanese Patent Application No. 2004-286205 filed on Sep. 30, 2004 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vibration damping device applicable as an engine mount for use in an automotive vehicle, for example, and in particular to a fluid filled vibration damping device in which damping effects are obtained based on flow action of a non-compressible fluid sealed in the interior.

2. Description of the Related Art

A fluid filled vibration damping is known as one type of damping connectors or damping supports mounted between members forming a vibration transmission system. JP-Y-4-33478 shows one example of the fluid filled vibration damping device. This type of damping device typically includes: a first and a second mounting member elastically connected together by a rubber elastic body; a pressure receiving chamber in which part of the wall is composed of the rubber elastic body; an equilibrium chamber in which part of the wall is composed of a readily deformable flexible film; an non-compressible fluid being sealed in the pressure receiving chamber and equilibrium chamber. Damping effects are brought about based on the resonance action of the fluid flowing through the orifice passage that is formed so as to connect the pressure receiving chamber and equilibrium chamber to each other, as a result of the relative change in pressure between the pressure receiving and equilibrium chambers when vibrations are input between the first and second mounting members.

Damping effects based on the resonance action of the non-compressible fluid flowing through the orifice passage are readily brought about only in a specific pre-tuned range of frequencies. A hydraulic absorption mechanism based on a movable panel has been proposed in order to improve damping performance by avoiding the development of extremely high dynamic spring, particularly during the input of vibrations in frequency ranges higher than the tuned frequency range of the orifice passage. In this hydraulic absorption mechanism, a housing space is generally formed in the partition member dividing the pressure receiving chamber and equilibrium chamber, and a movable panel is micro-displaceably disposed in the housing space. The housing space is formed via through holes in the pressure receiving chamber and equilibrium chamber, so that the pressure in the pressure receiving chamber is exerted on one side of the moveable panel, and the pressure in the equilibrium chamber is exerted on the other side.

The displacement of the movable panel due to differences in pressure between the pressure receiving chamber and the equilibrium chamber allows minute fluctuations in pressure in the pressure receiving chamber to escape into the equilibrium chamber during the input of high frequency vibrations. Because of the substantial vibration amplitude during the input of low frequency vibrations for which the orifice passage has been tuned, the movable panel comes into contact with and overlaps the inner surface of the housing space, effectively closing off the through holes. This prevents the absorption of pressure in the pressure receiving chamber by the hydraulic absorption mechanism, resulting in the effective production of relative pressure fluctuations between the pressure receiving chamber and equilibrium chamber, while also ensuring a sufficient flow of fluid through the orifice passage between the two chambers to bring about damping effects by the orifice passage.

However, during rapid pressure fluctuations in the pressure receiving chamber upon the input of vibrations of greater amplitude in this type of hydraulic absorption mechanism, the movable panel strikes the inner surface of the housing space. The impact of the movable panel striking the surface tends to result in noise and vibration. If used as an automobile engine mount, for example, the noise will sound disagreeable to the operator when the engine is cranked or while driving over bumps, detracting from the driving experience.

To address such problems, JP-Y-4-33478 proposed constructing a movable pane with a rubber elastic panel, and integrally forming a small protrusion in the form of a lip on the surface, so that the protrusion could absorb impact when struck. Although this type of small protrusion is effective against low energy strikes, it is not very effective during rapid and extensive pressure fluctuations in the pressure receiving chamber, and another way of dealing with this problem is needed.

SUMMARY OF THE INVENTION

It is therefore one object of this invention to provide a fluid filled vibration damping device equipped with a hydraulic absorption mechanism, which alleviates impact when the inner surface of the housing space of the movable late forming the hydraulic absorption mechanism is struck, thereby being capable of rapidly reducing disagreeable noise and the like caused by such strikes.

The above and/or optional objects of this invention may be attained according to at least one of the following modes of the invention. The following modes and/or elements employed in each mode of the invention may be adopted at any possible optional combinations. It is to be understood that the principle of the invention is not limited to these modes of the invention and combinations of the technical features, but may otherwise be recognized based on the teachings of the present invention disclosed in the entire specification and drawings or that may be recognized by those skilled in the art in the light of the present disclosure in its entirety.

According to a first mode of the invention provides: a fluid filled vibration damping device comprising: a first mounting member; a second mounting member; a main rubber elastic body elastically connecting the first and second mounting members; a pressure receiving chamber whose wall is partially formed by the rubber elastic body to accommodate pressure fluctuations during vibration input; an equilibrium chamber whose wall is partially formed by a flexible film to accommodate changes in volume; the pressure receiving chamber and the equilibrium chamber being disposed on either side of a partition member supported by the second mounting member, and having a non-compressible fluid sealed therein; an orifice passage through which the pressure receiving chamber and equilibrium chamber communicate with each other; a movable panel housed in a housing space that is provided in the partition member and held in communication with the pressure receiving chamber and the equilibrium chamber via through holes formed through the partition member so that a pressure of the pressure receiving chamber is exerted onto one side of the movable panel and the pressure in the equilibrium chamber is exerted onto an other side of the movable panel, wherein minute pressure fluctuations in the pressure receiving chamber during vibration input can be escaped into and absorbed by the equilibrium chamber by means of the movable panel, wherein the movable panel is composed of a movable rubber plate formed by a rubber elastic body, and includes at least partially a corrugated part which expands in generally a form of a corrugated panel by means of continuous depressions and protrusions.

In a fluid filled vibration damping device constructed according to this mode, the movable rubber plate includes at least partially the corrugated part in which the movable rubber plate is itself in the form of the corrugated panel. Based on the difference in pressure between the pressure receiving chamber and equilibrium chamber acting on both sides during the input of vibrations of substantial amplitude, the corrugated part repeatedly strikes the inner surface of the housing space or is further forced from a pre-contact state for an even broader range of contact. That is, when the movable rubber plate strikes the inner surface of the housing space, it results in hydraulic force which acts on the surface of the corrugated part through the through holes to force the movable rubber plate toward the inner surface of the housing space as well as a force reaction received from the inner surface of the housing space. As a result, the entire corrugated part becomes elastically deformed, and the impact energy occurring during the contact described above is effectively absorbed based on the attenuating force or elasticity associated with the elastic deformation of the corrugated part.

The elastic deformation of the corrugated part thus absorbs impact energy far more effectively than the conventional lip-shaped small protrusion on the surface of movable panels. Problems such as noise caused by the movable rubber plate striking the inner surface of the housing space can thus be effectively minimized or eliminated even in cases where sudden fluctuations in pressure occur such as when the engine is cranked or while driving over bumps in automobile engine mount applications, for example, contributing to a more comfortable driving experience.

In this mode, part of the corrugated part (protrusions on both sides) may be in previous contact with the inner surface of the housing space, as described in a second mode below, or the entire part may be stroke displaceable while floating between opposing inner faces of the housing space, as described in a ninth and tenth mode below. The impact caused by the corrugated part in the former case occurs due to strikes at points of contact which expand as a result of vibration beyond the point of contact in the initial vibration-free state, and strikes at the point of contact in the initial state as a result of the elastic deformation of the corrugated part during vibration input. The impact caused by the contact of the corrugated part in the latter case occurs as a result of strikes in cases where the corrugated part comes into contact with the inner surface of the housing space whenever the amplitude of the input vibrations increases, limiting the displacement.

The size and configuration of the corrugated part used in this mode are not particularly limited, and a variety of modes can be employed as noted in the various ones described below, such as those with continuous corrugations in the circumferential direction, those with continuous corrugations in one direction, or those in which corrugations are formed by dividing the movable rubber plate over a plurality of areas. The configuration and pitch of the corrugated part, as well as the size of its depressions and protrusions, and the like can be suitably designed to ensure effective absorption of contact impact according to the thickness (plate thickness of the movable rubber plate) and material of the corrugated part, the magnitude of the hydraulic pressure that is exerted, and the like. A specific example of a suitable configuration for the corrugations in order to achieve effective absorption of impact would be curved corrugations without sine wave-shaped corners, rather than a linear saw-toothed configuration. Preferably, the corrugated part thickness T (when the corrugated part has a shock-absorbing lip-shaped protrusion, the thickness includes this lip-shaped protrusion) should be 2 mm to 15 mm. The movable rubber plate including the corrugated part does not have to be of a constant thickness in its entirety. To ensure a stable state of contact on the inner surface of the housing space and effective impact absorption performance, the pitch P of the corrugations should preferably be at least two corrugation cycles, and even more preferably the distance PL between adjacent protrusions or between adjacent depressions should be 10 mm.ltoreq.PL.ltoreq.50 mm, preferably. The corrugation depth D (distance in the thicknesswise direction between the tips of the protrusions and the bottoms of the depressions on the same surface) should be at least 0.1 mm, preferably, and more preferably 0.2 mm.ltoreq.D.ltoreq.1 mm.

A second mode of the invention provides a fluid filled vibration damping device according to the first mode, wherein a height of undulations in a thicknesswise direction of the movable rubber plate between the protrusions on one side and the protrusions on an other side of the corrugated part of the movable rubber plate is greater than a height distance between opposite inner surfaces in the housing space, and the movable rubber plate thickness at each location of the corrugated part is less than the height distance between opposite inner surfaces in the housing space, so that all the protrusions on both sides of the corrugated part are in contact with the inner surfaces of the housing space, and all the depressions on both sides of the corrugated part are apart from the inner surfaces of the housing space, forming a gap therebetween.

In the fluid filled vibration damping device of this mode, the corrugated part is incorporated while elastically positioned in the thicknesswise direction of the plate inside the housing space, and the points of contact on the inner surfaces of the housing space expand in the circumferential direction through the elastic deformation of the corrugated part as a whole due to the hydraulic action associated with vibration input. Along with that, pressure fluctuations in the pressure receiving chamber escape into the equilibrium chamber, affording hydraulic absorption performance. Since the protrusions of the corrugated part are already in contact with the inner surface of the housing space, impact is promptly controlled for more effective suppression of noise and vibration during contact associated with displacement of the corrugated part.

A third mode of the invention provides a fluid filled vibration damping device according to the first or second mode, wherein a positioning member is disposed for positioning the movable rubber plate relative to the partition member to locate the movable rubber plate in generally a center inside the housing space in a direction perpendicular to the thicknesswise direction.

In the fluid filled vibration damping device in this mode, the movable rubber plate can be prevented from becoming off set inside the housing space, thus making it possible to stabilize the flow of the fluid in the housing space to obtain more stable hydraulic absorption performance in the pressure receiving chamber along with the displacement (including displacement based on deformation) of the movable rubber plate. Particularly when the structure of the second mode is employed, because the movable rubber plate is incorporated while positioned as it is compressed to a certain extent in the thicknesswise direction of the panel inside the housing space, it is extremely difficult to correct the movable rubber plate if it becomes off set in the housing space. The use of the present mode is a reliable way to avoid the problem of movable rubber plate displacement in the housing space.

A fourth mode of the invention provides a fluid filled vibration damping device according to the third mode, wherein the positioning member comprises a positioning engagement portion formed on a generally center on at least one side of the movable rubber plate in order to position the movable rubber plate relative to the partition member.

In the fluid filled vibration damping device of this mode, the positioning engagement portion is formed in generally the center, allowing the movable rubber plate to be readily attached, without the need for circumferential positioning relative to the partition member. The positioning engagement portion is also used to attach the movable rubber plate by simply superposing it on the partition member, making it even easier to attach the movable rubber plate on the partition member.

A fifth mode of the invention provides a fluid filled vibration damping device according to any one of the first through fourth modes, wherein the corrugated part has a shock absorbing lip protrusion integrally formed at a surface in contact with at lest one of the vertically opposite surfaces of the housing space.

In the fluid filled vibration damping device of this mode, the impact resulting when the movable rubber plate comes into contact with the partition member (inner surface of the housing space) is absorbed and attenuated not just by the deformation of the corrugated part as a whole, but also by the elastic deformation of the shock-absorbing lip protrusion. Since the shock-absorbing lip protrusion in particular is formed with soft spring properties relative to the entire corrugated part, it acts to complement the deformation of the corrugated part as a whole, allowing a broad range of impact to be even more effectively absorbed and attenuated, from the start of contact to the end, and furthermore from low to high frequencies. The shock-absorbing lip protrusion may, for example, extend linearly or distributed in the form of dots. A plurality of shock-absorbing lip protrusions of differing height may also be formed, or the height of a single linearly extending lip protrusion may be varied here and there.

A sixth mode of the invention provides a fluid filled vibration damping device according to any one of the first through fifth modes, wherein the movable rubber plate has at a central portion thereof a circular flat plate portion, and at a peripheral portion thereof an annular plate portion that is corrugated in the circumferential direction along an entire circumference thereof to constitute the corrugated part.

The fluid filled vibration damping device of this mode comprises both the flat plate portion and the corrugated portion so that the flow of fluid in the orifice passage is secured as a result of the through holes being effectively constricted or blocked by the flat panel portion, while ensuring that the impact from the corrugated part coming into contact with the inner surface of the housing space is absorbed and alleviated. In this mode, the shock-absorbing lip protrusion should be integrally formed on both sides in the thicknesswise direction of the flat panel portion. In this way, as will be described in a seventh mode below, the flat panel portion is sandwiched between a pair of facing inner surfaces in the housing space, with the shock-absorbing lip protrusion elastically deformed to a certain extent. The flat panel portion is displaced substantially in the thicknesswise direction of the panel in the housing space by the elastic deformation of the shock-absorbing lip protrusion, so as to effectively control noise and vibrations produced when the flap panel portion strikes the inner surface of the housing space. Alternatively, a gap is formed between the pair of facing inner surfaces in the housing space and the shock-absorbing lip protrusion on both sides of the movable rubber plate, so that even though the flat plate portion is freely displaceable to a certain extent in the thicknesswise direction of the panel in the housing space, the impact caused by the flat panel portion coming into contact with the inner surface of the housing space is effectively absorbed and attenuated by the elastic deformation of the shock-absorbing lip protrusion.

Also in the fluid filled vibration damping device in this mode, the corrugated part is formed in the outer peripheral portion of the movable rubber plate, ensuring a beneficial balance between the elasticity and rigidity of the movable rubber plate as a whole. When the movable rubber plate is displaced in the thicknesswise direction of the panel by differences in the pressure action on both sides, the maximum rate of slip is readily reached at the outer peripheral edge, which is the free end, and the maximum energy involved in the strikes on the inner surface of the housing space is readily reached. The problematic energy involved in the strikes at the outer peripheral edge can be effectively attenuated by the elastic deformation of the corrugated part, and the corrugated part even more effectively reduces disagreeable noise and the like caused by such strikes.

A seventh mode of the invention provides a fluid filled vibration damping device according to any one of the first through sixth modes, wherein the movable rubber plate has at a central portion thereof a circular flat plate portion, and at a peripheral portion thereof an annular plate portion at a peripheral portion thereof that is corrugated in the circumferential direction along an entire circumference thereof to constitute the corrugated part, and wherein the flat plate portion and corrugated part both have integrally formed shock-absorbing lip protrusions on both sides in the thicknesswise direction of the movable rubber plate, which are in contact in a pre-compressed state with the inner surface of the housing space.

In the fluid filled vibration damping device in this mode, the impact that occurs when the flat panel portion strikes the inner surface of the housing space is effectively suppressed as noted in the sixth mode, and the impact that occurs when the corrugated part strikes the inner surface of the housing space is also effectively suppressed as noted in the second mode. Also, since the corrugated part is formed on the outer peripheral edge of the rubber elastic panel, even though all of the flat plate portion formed in the center is substantially superposed on the inner surface of the housing space to limit its displacement, the radial cross section of the corrugated part has a cantilevered structure, where it is supported only at the inner peripheral edge joined to the flat panel portion, effectively permitting oscillating displacement in the corrugated part, whereby impact is absorbed during the input of vibrations with greater amplitude.

An eighth mode of the invention provides a fluid filled vibration damping device with a structure according to any one of the first through third modes, wherein the movable rubber plate has a corrugated part along substantially an entirety thereof.

Because the corrugated part can be formed along a sufficiently large area in the fluid filled vibration damping device of this mode, the corrugated part can even more effectively absorb impact caused by the contact of the movable rubber plate on the inner surface of the housing space.

A ninth mode of the invention provides a fluid filled vibration damping device according to any one of the first, third, fourth, fifth, sixth and eighth modes, wherein the movable rubber plate is micro-displaceably disposed in the housing space in the thicknesswise direction of the plate with a given amount of gap all a way around, and the corrugated part, on at least one side of the movable rubber plate, initially strikes the inner surface of the housing space when the movable rubber plate is displaced and strikes the inner surface of the housing space at the partition member.

In the fluid filled vibration damping device in this mode, the entire rubber elastic panel is displaceable in the thicknesswise direction of the panel while in a free, unrestrained state, with a gap between the facing inner surfaces of the housing space. Thus, during vibration input, the entire rubber elastic panel is displaceable while in a floating state in the housing space, resulting in even more effective absorption of pressure in the pressure receiving chamber.

It is also effective to construct the mode in such a way that, when the movable rubber plate is displaced into contact with the inner surface of the housing space at the partition member, the corrugated part first strikes the inner surface of the housing space on at least one side. Thus, even when the corrugated part is formed on part of the movable rubber plate, the corrugated part first comes into contact with the inner surface of the housing space, so that the impact produced by strikes is effectively absorbed by the elastic deformation action of the corrugated part in the early stages of the contact.

A tenth mode of the invention provides a fluid filled vibration damping device according to any one of the first, third, fourth, fifth, sixth, eighth and ninth modes, wherein a height of the undulations in the thicknesswise direction of the movable rubber plate between the protrusions on one side and the protrusions on the other side of the corrugated part of the movable rubber plate is less than the distance between vertically opposite inner surfaces in the housing space, so that the corrugated part of the movable rubber plate is displaceably housed, with a given amount of gap in the thicknesswise direction of the movable rubber plate, and the corrugated part is displaced in the thicknesswise direction of the movable rubber plate into contact with the inner surface of the space.

In the fluid filled vibration damping device of this mode, the entire corrugated part is displaceable in the thicknesswise direction of the panel while in a free, unrestricted state, with a gap between the opposite inner surfaces in the housing space. Thus, during vibration input, the entire corrugated part is displaceable while in a floating state in the housing space, resulting in even more effective absorption of pressure in the pressure receiving chamber.

An eleventh mode of the invention provides a fluid filled vibration damping device according to any one of the first through tenth modes, wherein the second mounting member is generally cylindrical, the first mounting member is disposed apart from the second mounting member, an opening at one end of the second mounting member is fluid-tightly sealed by the main rubber elastic body that elastically connects the first and second mounting members, an opening at the other end of the second mounting member is fluid-tightly sealed by the flexible film, the partition member fixedly supports the second mounting member, being disposed so as to expand perpendicularly to the axis of the second mounting member between the facing surfaces of the main unit elastic body and flexible film, so that the pressure receiving chamber and equilibrium chamber are formed on either side of the partition member, the housing space is formed so as to expand perpendicularly to the axis of the second mounting member inside the partition member, and the movable rubber plate is housed in the housing space so as to expand perpendicularly to the axis of the second mounting member.

The fluid filled vibration damping device in this mode allows the pressure receiving chamber and equilibrium chamber to be effectively formed on either side of the partition member forming the housing space for the movable rubber plate, resulting in a more compact fluid filled vibration damping device overall. This is particularly suitable for use as automobile engine mounts or the like.

As is evident from the description above, in the fluid filled vibration damping device of the invention, impact caused when the movable panel strikes the inner surface of the housing space during the input of vibrations of greater magnitude is absorbed and attenuated by the impact absorption action associated with the elastic deformability of the movable rubber plate itself based on the elastic deformation of the corrugated part provided on the movable rubber plate as a movable panel. Disagreeable noise and the like can thus be effectively prevented because impact energy is effectively attenuated even when strikes or the like on the inner surface of the housing space result in impact force that is too great to be absorbed by conventional lip-shaped protrusions such as disclosed in the aforementioned JP-Y-4-33478 as a result of vibration loads of extremely high energy.

BRIEF DESCRIPTION OF THE DRAWINGS

The forgoing and/or other objects features and advantages of the invention will become more apparent from the following description of a preferred embodiment with reference to the accompanying drawings in which like reference numerals designate like elements and wherein:

FIG. 1 is an elevational view in axial or vertical cross section of a fluid filled vibration damping device in the form of an engine mount of construction according to a first embodiment of the invention;

FIG. 2 is a top plane view of the engine mount of FIG. 1;

FIG. 3 is a top plane view of a partition member of the engine mount of FIG. 1;

FIG. 4 is a cross sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is a bottom plane view of the partition member of FIG. 3;

FIG. 6 is a top plane view of a rid metal member of the engine mount of FIG. 1;

FIG. 7 is a top plane view of a movable rubber plate of the engine mount of FIG. 1;

FIG. 8 is a cross sectional view taken along line 8-8 of FIG. 7;

FIG. 9 is an exploded view of a quarter circumferential face of the movable rubber plate of FIG. 7;

FIG. 10 is a graph demonstrating a result of frequency analysis of the output data of the active load sensed when the engine mount of FIG. 1 is subjected to vibration input;

FIG. 11 is an exploded view corresponding to FIG. 9, illustrating a quarter circumferential face of a movable rubber plate of another construction;

FIG. 12 is an exploded view corresponding to FIG. 9, illustrating a quarter circumferential face of a movable rubber plate of yet another construction;

FIG. 13 is an exploded view corresponding to FIG. 9, illustrating a quarter circumferential face of a movable rubber plate of still another construction;

FIG. 14 is an elevational view in axial or vertical cross section of an engine mount of construction according to a second embodiment of the invention;

FIG. 15 is a vertical cross sectional view of a movable rubber plate of the engine mount of FIG. 14;

FIG. 16 is a fragmentary enlarged cross sectional view of a principle part of the movable rubber plate of FIG. 15;

FIG. 17 is a fragmentary enlarged cross sectional view of a principle part of the movable rubber plate of FIG. 15;

FIG. 18 is a perspective view of a movable rubber plate of another construction that is usable in the present invention; and

FIG. 19 is a perspective view of a movable rubber plate of another construction that is usable in the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1 and 2 illustrate an automobile engine mount 10 in a first embodiment of the invention. This engine mount 10 has a construction wherein a metallic first mounting member 12 and a metallic second mounting member 14 are elastically connected by means of a main rubber elastic body 16. The engine mount 10 is such that the first mounting member 12 is attached to a power unit, while the second mounting member 14 is attached to a n automobile body, so that the power unit is supported in a vibration damping manner in cooperation with other engine mounts and the like (not shown) relative to the body. The first mounting member 12 and second mounting member 14 are vertically (in FIG. 1) displaced a certain distance toward each other as the main rubber elastic body 16 is elastically deformed by the input of the shared load of the power unit onto the mount 10 which has been set up in the manner described above, and the primary vibrations which are to be damped are input in generally the vertical direction in FIG. 1 between the first mounting member 12 and second mounting member 14. Mounted in this state, as illustrated in FIG. 1, the engine mount 10 in this embodiment is mounted with the central axis of the mount (central axis of the first and second mounting members 12 and 14) in the generally vertical direction, and the vertical direction in the following description will refer to the vertical direction in FIG. 1.

More specifically, the first mounting member 12 is generally disk shaped, with an upward (upward in FIG. 1) protruding attachment bolt 18 fixed in its center portion. A metallic retaining fixture 20 is fixed along the center axis to the bottom surface of the first mounting member 12. The retaining fixture 20 comprises a tapered peripheral wall gradually expanding toward the upper opening, and is fixed to the bottom surface of the first mounting member 12 at the peripheral opening.

The second mounting member 14 has a generally annular shape of large diameter, and is disposed along generally a concentric axis apart from and under (under in FIG. 1) the first mounting member 12. The structure of the second mounting member 14 is such that a fitting sleeve 23 protruding axially downward from the outer peripheral edge is integrally formed with a generally annular disk-shaped rubber fixing portion 22. The inner periphery of the rubber fixing portion 22 has a tapered slanting shape inclined gradually downward in the axial direction toward the center.

The main rubber elastic body 16 is disposed between the facing surfaces of the first mounting member 12 and second mounting member 14. The main rubber elastic body 16 has a generally conical shape of large diameter, with a large tapered round recess 26 in the center. The round recess 26 is a bottomed, inverted round hole that gradually expands radially downward and that is open at the large diameter end surface of the main rubber elastic body 16. The round recess 26 is formed so that the main rubber elastic body 16 has a thick-walled inverted cup shape overall.

The first mounting member 12 is superposed on a small diameter end surface in the upper axial direction of the main rubber elastic body 16, and the main rubber elastic body 16 is bonded by vulcanization to the first mounting member 12 and the retaining fixture 20 that is fused and fixed to the bottom surface of the first mounting member 12. The main rubber elastic body 16 is also packed into the retaining fixture 20. The rubber fixing portion 22 of the second mounting member 14 is also bonded by vulcanization, while generally embedded in a configuration inserted from the outer peripheral surface, in the large diameter end of the main rubber elastic body 16. In a word, the main rubber elastic body 16 is formed as an integrally vulcanized molded product comprising the first mounting member 12 and second mounting member 14.

A generally annular disk-shaped metallic reinforcing member 24 is fixed to the axial intermediate portion where the main rubber elastic body 16 is in the form of a thick-walled pipe, allowing the spring properties of the main rubber elastic body 16 to be adjusted. As illustrated in FIG. 1, the second mounting member 14 is covered by integrally forming a seal rubber layer 28 with the main rubber elastic body 16 so as to cover generally the entire inner peripheral surface of the fitting sleeve 23 and bottom surface of the rubber fixing portion 22.

A metallic partition member 30 as the dividing member and a diaphragm 32 as a flexible film are incorporated, from the opening in the lower axial direction of the second mounting member 14, with the integrally vulcanized molded article of main rubber elastic body 16 comprising the first and second mounting members 12 and 14.

The partition member 30 has a thick-walled generally disk shape. The diaphragm 32 is made of a readily deformable thin-walled rubber elastic film, and is bonded by vulcanization to a fitting fixture 34, the outer peripheral edge of which is generally annular disk-shaped. The partition member 30 and diaphragm 32 are thus fixed by being fitted to the second mounting member 14.

Specifically, the partition member 30 is fitted to the fitting sleeve 23 of the second mounting member 14, expanding in the axis-perpendicular direction. An outer peripheral surface and an upper surface of the outer peripheral surface of the partition member 30 is fluid-tightly placed on top of the fitting sleeve 23 and the rubber fixing portion 22 of the second mounting member 14, with the seal rubber layer 28 interposed between.

The diaphragm 32 is generally disk-shaped, with enough slack in the middle to be readily deformed. The diaphragm 32 is bonded by vulcanization at its outer peripheral edge to a metallic fitting fixture 34. The fitting fixture 34 has a structure wherein a cylindrical fixing pipe 35 protruding upward from the outer peripheral edge is integrally formed with an annular disk-shaped support 33. The outer peripheral edge of the diaphragm 32 is bonded by vulcanization to the inner peripheral edge of the support 33. The fixing pipe 35 is fitted to the fitting sleeve 23 of the second mounting member 14, and the diameter of the fixing pipe 35 is reduced by being constricted on all sides. The support 33 of the fitting fixture 34 is in contact with the bottom surface of the outer periphery of the partition member 30, and the fixing pipe 35 of fitting fixture 34 is fitted to the fitting sleeve 23. The surfaces where the fixing pipe 35 and fitting sleeve 23 are fitted together are fluid-tightly sealed with a seal rubber layer which has been formed as a coating on the fixing pipe 35.

In this way, the opening which opens downward through the center hole in the second mounting member 14 is fluid-tightly sealed by the diaphragm 32 at the round recess 26 formed in the main rubber elastic body 16. A non-compressible fluid is sealed in the area between the facing surfaces of the diaphragm 32 and main rubber elastic body 16, which has been formed by utilizing the round recess 26 and sealed off against external space, so that the area where the fluid is sealed is formed. Examples of sealed fluids which can be used include alkylene glycol, polyalkylene glycol, and silicone oil, but the use of low viscosity fluids no greater than 0.1 Pas is particularly preferred for more effective damping based on the resonance action of the fluid. The non-compressible fluid can be sealed, for example, by assembling the diaphragm 32 and partition member 30 with the integrally vulcanized and molded article of the main rubber elastic body 16, which comprises the first and second mounting members 12 and 14, in the non-compressible fluid.

The area in which the fluid is sealed is also divided into a top and bottom by providing the partition member 30 in the interior so as to expand in the axis-perpendicular direction. With this arrangement, part of the wall is formed by the main rubber elastic body 16 on one side of the partition member 30 (top in FIG. 1) in the axial direction, forming a pressure receiving chamber 36 in which fluctuations in pressure are caused by the elastic deformation of the main rubber elastic body 16 when vibrations are input between the first mounting member 12 and second mounting member 14. Part of the wall is formed by the diaphragm 32 on the other side of the partition member 30 in the axial direction, forming an equilibrium chamber 38 in which volume changes are readily accommodated by the elastic deformation of the diaphragm 32.

As illustrated in FIGS. 3 through 5, a groove 40 that is open in the upper surface and extends continuously in the circumferential direction is formed in the outer circumferential surface, and the groove 40 is fluid-tightly sealed off by the rubber fixing portion 22 of the second mounting member 14, forming a tunnel-shaped conduit. In this embodiment, the groove 40 is formed reciprocally in the circumferential direction, traversing a portion around about 3/4 of the upper circumference of the partition member 30. A weight-lightening recess is formed in a portion traversing about one fourth of the upper periphery where the groove 40 has not been formed, and is fluid-tightly sealed off by the rubber fixing portion 22 in the same manner as the groove 40.

One end of the groove 40 extends radially inward further than the inner periphery of the rubber fixing portion 22 of the second mounting member 14, so that the end of the groove 40 is open in the upper surface of the partition member 30 on the inner peripheral side past the rubber fixing portion 22, forming a through hole 42. One end of the groove 40 is connected through this through hole 42 to the pressure receiving chamber 36. The other end of the groove 40 opens through a through hole 44 formed in the floor of the groove 40 in the partition member 30, to open into and connect to the equilibrium chamber 38. The groove 40 in the partition member 30 is thus used to form an orifice passage 46, and the pressure receiving chamber 36 and equilibrium chamber 38 communicate with each other through this orifice passage 46.

Thus, during the input of vibrations, relative pressure fluctuations are produced between the equilibrium chamber 38 in which volume changes are accommodated by the deformation of the diaphragm 32, and the pressure receiving chamber 36, in which pressure fluctuations are produced, resulting in the flow of fluid through the orifice passage 46 between the two chambers 36 and 38. Axial vibrations (vertical direction in FIG. 1) which should be damped are thus effectively damped based on the resonance action of the fluid flowing through the orifice passage 46 between the pressure receiving chamber 36 and equilibrium chamber 38.

In this embodiment in particular, the resonance frequency of the fluid flowing through the orifice passage 46 is tuned so as to ensure effective damping of vibrations having greater amplitude and a lower frequency of about 10 Hz, such as shaking, based on the resonance action of the fluid. The resonance frequency is tuned by setting and adjusting the passage cross section area, length, and the like of the orifice passage 46, for example, while taking into consideration the wall spring synthesis or the like of the pressure receiving chamber and equilibrium chamber.

A round center recess 48 open at the top is formed in the center of the partition member 30, and a movable rubber plate 50 is housed in the center recess 48. In this embodiment, the entire center recess 48 is generally a fixed depth. Also, a disk-shaped lid fixture 52 as illustrated in FIG. 6 is superposed onto the center of the partition member 30 by being aligned with three positioning protrusions on the partition member 30, and the positioning protrusions are crimped to fix the lid to the partition member 30 so as to cover the center recess 48. A hollow housing space 49 expanding in the form of a disk with a certain inside diameter and height is thus formed in the interior of the partition member 30. That is, the housing space 49 is formed between the axially facing surfaces of a pair of flat inner surfaces 53, 55 which both expand in the axis-perpendicular direction, and the distance L between the facing surfaces of the pair of inner surfaces 53 and 55 is greater by to a certain extent than the maximum panel thickness T (thickness of the panel, including shock-absorbing lip protrusions 64, 66, 68, 72, and 74) of the movable rubber plate 50 described below, as indicated by the imaginary lines in FIG. 8.

The movable rubber plate 50 is generally disk-shaped as a whole, and is integrally formed by rubber material. As noted above, the maximum panel thickness T of the movable rubber plate 50 is less than the height L of the housing space 49, resulting in the formation of a gap that expands along the entirety between the inner surfaces of the housing space 49 around the entire circumference of the movable rubber plate 50 while the movable rubber plate 50 is positioned in the center in the housing space 49. The movable rubber plate 50 is freely displaceable, while floating in the housing space 49, by a stroke corresponding to the size of the gap.

Through holes 54 and 56 are formed in the axial direction (vertical direction) in the floor of the center recess 48 of the partition member 30 forming the vertical wall of the groove 40, and in the lid fixture 52. The upper surface of the movable rubber plate 50 housed in the housing space 49 is exposed to the pressure receiving chamber 36 through the through hole 56 in the lid fixture 52, while the bottom surface of the movable rubber plate 50 is exposed to the equilibrium chamber 38 through the through hole 54 in the floor of the center recess 48. The through holes 54 and 56 are located along generally the entirety of the vertical opposite inner surfaces 53 and 55 of the housing space 49, and are open in particular in the facing areas of the central flat panel portion 60 described below, located in the center of the movable rubber plate 50, and the outer peripheral annular plate portion 62 described below, located in the outer peripheral portion.

The pressure in the pressure receiving chamber 36 and equilibrium chamber 38 are exerted on the upper surface and lower surface of the movable rubber plate 50, respectively, resulting in the displacement of the movable rubber plate 50 in the panel thicknesswise direction caused by differences in the pressure between the pressure receiving chamber 36 and equilibrium chamber 38 during the input of vibrations. The axial displacement of the movable rubber plate 50 results in the flow of fluid through the through holes 56 and 54 of the lid fixture 52 and partition member 30, so that the resonance action of the fluid or the hydraulic absorption action based on the escape of the pressure fluctuations in pressure receiving chamber 36 into the equilibrium chamber 38 results in low dynamic spring effects against input vibrations.

The vertical (thicknesswise direction of panel) stroke tolerance of the movable rubber plate 50 in the housing space 49 may be suitably adjusted on the basis of the amplitude of the input vibrations that should be damped, or the effective piston diameter and the size of the movable rubber plate 50, etc., in the pressure receiving chamber 36 of the engine mount 10. In this embodiment, the size of the gap between the facing surfaces of the upper and lower surfaces of the movable rubber plate 50 and the upper and lower surfaces of the housing space 49 is set so that the movable rubber plate 50 strikes the inner surface of the housing space 49 when vibrations with an amplitude of .+-.0.5 to 2.0 mm corresponding to engine shake act between the first mounting member 12 and second mounting member 14, but the movable rubber plate 50 is displaceable in areas where it does not strike the inner surface of the housing space 49 when vibrations of intermediate or low amplitude of no more than .+-.0.25 mm corresponding to the muffled sounds of driving or idling vibrations are input.

As illustrated in FIGS. 7-9, the movable rubber plate 50 in this embodiment comprises the central flat panel portion 60 in the shape of a round flat panel as the flat panel portion, and the outer peripheral annular plate portion 62 in the form of an annular disk extending continuously in the circumferential direction at the outer peripheral edge.

The central flat panel portion 60 expands in a round shape at a generally constant thickness on the center axis, with several shock-absorbing lip protrusions integrally formed protruding on the upper and lower surfaces (on both sides in the thicknesswise direction). The shock-absorbing lip protrusions are composed of a) an annular first shock-absorbing lip protrusion 64 extending continuously in the circumferential direction through the radially intermediate portion, b) eight independent second shock-absorbing lip protrusions 66 extending radially outward from around the center axis, and c) an annular third shock-absorbing lip protrusion 68 extending continuously in the circumferential direction through the outer peripheral edge portion.

The outer peripheral annular plate portion 62 has an inside diameter greater than the outside diameter of the central flat panel portion 60, and is positioned along the same center axis as the central flat panel portion 60. In generally the center portion in the thicknesswise direction of the panel, the outer peripheral surface of the central flat panel portion 60 and the inner peripheral surface of the outer peripheral annular plate portion 62 are integrally joined together by facing radially extending thin-walled connectors 69. In other words, the upper and lower surfaces of the movable rubber plate 50 in this embodiment have a pair of excavated portions 70 and 70 continuously extending radially through portions which are a certain distance in the inward radial direction from the outer peripheral edge, and it is by means of these excavated portions 70 and 70 that the inner peripheral side serves as the central flat panel portion 60 and the outer peripheral side serves as the outer peripheral annular plate portion 62 on either side of the thin-walled connectors 69.

A fifth shock-absorbing lip protrusion 74 and an annular fourth shock-absorbing lip protrusion 72 continuously extending in the circumferential direction are formed in the inner peripheral edge and outer peripheral edge, respectively, on the upper and lower surfaces of the outer peripheral annular plate portion 62.

The thickness (including the upper and lower shock-absorbing lip protrusions) of the outer peripheral annular plate portion 62 is less than the thickness (including the upper and lower shock-absorbing lip protrusions) of the central flat panel portion 60. The outer peripheral annular plate portion 62 is in the form of a corrugated part which has been formed with a shape that curves and undulates as a whole so as to be corrugated in the panel thicknesswise direction (vertical direction in FIGS. 8 and 9) in the circumferential direction. That is, the outer peripheral annular plate portion 62 is altered in such a way that the center position in the thicknesswise direction oscillates vertically in the circumferential direction, with substantially no change in the radial cross section shape and size. In this embodiment in particular, as illustrated in FIG. 9, the vertical surface or center line of the outer peripheral annular plate portion 62 is corrugated in the circumferentia