Fluid-filled vibration damping device

A fluid-filled vibration-damping device including an elastic body elastically connecting a first and a second mounting member, a pressure-receiving chamber disposed inward of and partially defined by the elastic body, and a flexible rubber layer disposed outwardly of and cooperating with the elastic body to form an equilibrium chamber held in fluid communication with the pressure-receiving chamber through a first orifice passage. The first mounting member includes an elastic-body central member and a rubber-layer central member, which are fixed together at their abutting surfaces by a fixing mechanism, to constitute the first mounting member, and positioned relative to each other by an engagement of a fitting recess and projection formed on their abutting surfaces. A peripheral portion of an interface between the abutting surfaces of the elastic-body central member and said rubber-layer central member entirely faces the equilibrium chamber and/or the pressure-receiving chamber.

 

What is claimed is:

1. A fluid-filled vibration-damping device for connecting two members in a vibration damping fashion, comprising:

a first mounting member connectable to one of the two members;

a second mounting member connectable to an other of the two members;

an elastic body bonded at a central portion thereof to said first mounting member and at an outer circumferential portion thereof to said second mounting member in a process of vulcanization of a rubber material for forming said elastic body, for elastically connecting said first and second mounting members;

a pressure-receiving chamber disposed on one of axially opposite sides of said elastic body, filled with a non-compressible fluid and partially defined by said elastic body, to which a vibrational load is applied;

a flexible rubber layer disposed on an other one of said axially opposite sides of said elastic body so as to form an equilibrium chamber between said flexible rubber layer and said elastic body, said equilibrium chamber being filled with said non-compressible fluid and partially defined by said flexible rubber layer so as to easily permit a volumetric change thereof; and

a first orifice passage for fluid communication between said pressure-receiving chamber and said equilibrium chamber;

wherein said first mounting member includes an elastic-body central member bonded to said central portion of said elastic body, and a rubber-layer central member bonded to a central portion of said flexible rubber layer and having a fixing portion at which said first mounting member is connected to the one of the two members, and said elastic-body central member and said rubber-layer central member are superposed on and fixed to each other at their abutting surfaces by means of a fixing mechanism, to thereby constitute said first mounting member,

wherein one of said elastic-body central member and said rubber-layer central member has a fitting recess open in said abutting surface thereof, and an other one of said elastic-body central member and said rubber-layer central member has a fitting protrusion formed on said abutting surface thereof and being fitted into said fitting recess so that said elastic-body central member and said rubber-layer central member are positioned relative to each other, and

wherein an interface between said abutting surfaces of said elastic-body central member and said rubber-layer central member has a first peripheral portion entirely facing said equilibrium chamber and a second peripheral portion entirely facing said pressure-receiving chamber.

2. A fluid-filled vibration-damping device according to claim 1, wherein said fitting recess has an inner circumferential surface with a tapered shape that corresponds to a tapered shape of an outer circumferential surface of said fitting protrusion.

3. A fluid-filled vibration-damping device according to claim 2, wherein said fitting recess includes a press-fitting hole formed in a bottom wall thereof so as to axially extend with a substantially constant inner diameter, while said fitting protrusion includes a press-fitting part integrally formed at an protruding end portion thereof, said press-fitting part being press-fitted into said press-fitting hole to thereby provide said fixing mechanism.

4. A fluid-filled vibration-damping device according to claim 1, wherein said elastic-body central member includes a fixing bore open in said abutting surface thereof and extending therethrough in a direction in which said elastic-body central member and said rubber-layer central member are superposed on each other, while said rubber-layer central member includes a fixing shaft protruding therefrom, said fixing shaft extending through said fixing bore and disengageably fixed at a tip end thereof to said elastic-body central member, to thereby provide said fixing mechanism.

5. A fluid-filled vibration-damping device according to claim 1, further comprising: an elastic-body outer sleeve member bonded to an outer circumferential portion of said elastic body; and a rubber-layer outer sleeve member bonded to an outer circumferential portion of said flexible rubber layer, wherein said elastic-body and rubber-layer outer sleeve members are fixed together to partially constitute said second mounting member, and cooperate with each other to at least partially define said first orifice passage therebetween.

6. A fluid-filled vibration-damping device according to claim 1, further comprising a narrow passage adapted to connect said interface between said abutting surfaces of said elastic-body central member and said rubber-layer central member to at least one of said equilibrium chamber and said pressure-receiving chamber.

7. A fluid-filled vibration-damping device according to claim 1, wherein said first mounting member includes an injection bore extending through said elastic-body and rubber-layer central members in a direction in which said central members are superposed on each other, and an opening of said injection bore is fluid-tightly closed by a sealing member after filling said device with said non-compressible fluid through said injection bore.

8. A fluid-filled vibration-damping device according to claim 1, further comprising:

a heat shielding sleeve disposed radially outwardly of said flexible rubber layer and fixed at one of axially opposite end portions thereof to said second mounting member, wherein an other one of said axially opposite end portions of said heat shielding sleeve extends radially inwardly so as to provide a stop portion that is opposed to said first mounting member with a given spacing in an axial direction of said device and/or a radial direction perpendicular to said axial direction, and said stop portion is brought into abutting contact with said first mounting member via a buffer so as to limit an amount of displacement of said first and second mounting members relative to each other.

9. A fluid-filled vibration-damping device according to claim 8, further comprising: an elastic-body outer sleeve member bonded to an outer circumferential portion of said elastic body; and a rubber layer outer sleeve member bonded to an outer circumferential portion of said flexible rubber layer, said elastic-body and rubber-layer outer sleeve members being fixed together to partially constitute said second mounting member, wherein said rubber-layer central member extends radially outwardly from said elastic-body central member so as to provide an abutting portion that is brought into abutting contact with said stop portion of said heat shielding sleeve in said axial direction of said device, and said flexible rubber layer is bonded at said central portion thereof to said abutting portion of said rubber-layer central member, while said one of axially opposite end portion of said heat shielding sleeve is mounted on an outer circumferential surface of said rubber-layer outer sleeve member, and is fixed to said second mounting member by calking.

10. A fluid-filled vibration-damping device according to claim 9, further comprising a sealing rubber integrally formed at an outer peripheral portion of said flexible rubber layer over an entire circumference thereof so as to prevent entry of water into an interface between said heat shielding sleeve and said rubber-layer outer sleeve member.

11. A fluid-filled vibration-damping device according to claim 8, wherein said second mounting member has a tapered cylindrical portion formed at one of axially opposite end portions thereof and extending axially outwardly and radially outwardly, and said outer circumferential portion of said elastic body is bonded to said tapered cylindrical portion, and wherein said tapered cylindrical portion is provided with a cutout, while said elastic body is provided with a guide groove formed at a first circumferential position thereof so as to be contiguous with said cutout and so as to extend to said equilibrium chamber so that said cutout and said guide groove cooperate to connect said first orifice passage to said equilibrium chamber.

12. A fluid-filled vibration-damping device according to claim 11, wherein said guide groove has a sloped shape in which a depth dimension gradually decreases with an increase of a distance from said cutout.

13. A fluid-filled vibration-damping device according to claim 1, further comprising: a movable member partially defining said pressure-receiving chamber and being elastically supported by said second mounting member so as to be displaceable relative to said second mounting member; and an oscillating mechanism adapted to apply an oscillating force to said movable member in order to actively induce a fluid-pressure variation in said pressure-receiving chamber.

INCORPORATED BY REFERENCE

The disclosure of Japanese Patent Application No. 2001-201218 filed on Jul. 2, 2001 and No. 2001-382248 filed on Dec. 14, 2001, each including the specification, drawings and abstract, are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to fluid-filled vibration-damping devices exhibiting vibration damping effect on the basis of flows of non-compressible fluid filled therein. More particularly, the present invention is concerned with such a fluid-filled vibration-damping device that is novel in construction, and that is capable of providing an improved fluid-tight sealing without deteriorating efficiency in assembling and manufacturing the fluid-filled vibration-damping device.

2. Description of the Related Art

A fluid-filled vibration-damping device is known as one type of a vibration damping device interposed between two members of a vibration system for elastically connecting the two members, or for mounting one of the two members of the vibration system on the other member in a vibration damping fashion. JP-A-8-291844, JP-A-2001-59540 and JP-A-10-38016 disclose known examples of such a fluid-filled vibration-damping device, which includes a first mounting member adapted to be attached to one of the two members of the vibration system, a second mounting member adapted to be attached to the other member of the vibration system, and a rubber elastic body that is bonded at its central portion to the first mounting member and at its outer circumferential portion to the second mounting member for elastically connecting the first and second mounting members. The rubber elastic body partially defines a pressure-receiving chamber on one of opposite-side thereof. The pressure-receiving chamber is filled with the non-compressible fluid and adapted to receive vibrational load applied to the fluid-filled vibration-damping device. On the other side of the rubber elastic body, a flexible diaphragm formed of a rubber material is disposed so as to extend between the first and second mounting members, whereby the rubber elastic body and the flexible diaphragm cooperate to define therebetween an equilibrium chamber partially defined by the flexible diaphragm. The equilibrium chamber is filled with the non-compressible fluid, and has a volume that is variable due to deformation of the flexible diaphragm. The fluid-filled vibration-damping device further includes an first orifice passage for a fluid communication between the pressure-receiving chamber and the equilibrium chamber.

For the sake of efficiency in manufacture, the known fluid-filled vibration-damping device as disclosed in the aforesaid publication documents is arranged such that the rubber elastic body and the flexible diaphragm are formed independently from each other, and the rubber elastic body is bonded at its central portion to a central metal member for the rubber elastic body (hereinafter referred to as an "elastic-body central metal member"), while the flexible diaphragm is bonded at its central portion to a central metal member for the flexible diaphragm (hereinafter referred to as a "diaphragm central metal member"). These elastic-body and diaphragm central metal members are superposed on and fixed to each other, thereby providing the first mounting member.

However, as shown in the aforementioned JP-A-2001-59540 and JP-A-10-38016, for example, the conventional fluid-filled vibration-damping device is likely to suffer from a problem of leakage of the fluid originated in its structural feature. Namely, the elastic-body central metal member is provided with a fixing bolt protruding therefrom at which the first mounting member is fixed to one of the two members connected together in the vibration-damping fashion. On the other hand, the diaphragm central metal member is provided with a through hole formed through its central portion. These elastic-body and diaphragm central metal members are superposed on each other with the fixing bolt of the elastic body central metal member extending through the through hole of the diaphragm central portion. Consequently, an interface between the elastic-body central metal member and the diaphragm central metal member are substantially directly exposed to the atmosphere at the through hole portion of the diaphragm central metal member. Since an outer peripheral portion of the interface between the elastic-body central metal member and the diaphragm central metal member faces to the equilibrium chamber, the non-compressible fluid filling the equilibrium chamber is likely to be leaked out through the interface and the through hole of the diaphragm central metal member. In this respect, it should be noted that the fluid-filled vibration-damping device disclosed in the above described JP-A-8-291844 also suffers from the same inherent problem, although a clear depiction of the through hole formed through the diaphragm central metal member is just omitted.

In the conventional fluid-filled vibration-damping devices shown in the above-described publication documents, moreover, the elastic-body central metal member and the diaphragm central metal member are just superposed on each other at their plane abutting surfaces, in order to constitute the first mounting member. This arrangement makes it difficult to precisely position the two central metal members relative to each other upon assembling these two members together, and may possibly cause displacement of the two central metal members relative to each other, leading to undesirable leakage of the non-compressible fluid through the interface between abutting surfaces of the two central metal members.

Also, the diaphragm central metal member is not directly fixed to the elastic-body central metal member, but is just gripped by and between the elastic-body central metal member and the one member of the two members connected together in the vibration damping fashion, to which the elastic-body central metal member is bolted. This conventional structure is likely to cause looseness between the elastic-body central metal member and the diaphragm central metal member due to an effect of the vibrations applied thereto, resulting in difficulty in assuring a high fluid-tight sealing at the interface between the two central metal members with high stability.

JP-A-9-257090 discloses an example of modification of the above-described fluid-filled vibration-damping device proposed in an attempt to cope with the above-described conventional problem, in which the elastic body and the flexible diaphragm are formed as components of an integral vulcanized products. However, it is difficult in view of the shape or structure of a mold for forming the integral vulcanized product including the elastic body and the flexible diaphragm as the components. Further, such an integral vulcanized product makes it impossible to select suitable materials for the elastic body and the flexible diaphragm, respectively, in the light of required characteristics of the respective ones. For the above reasons, the proposed modification is not sufficient to solve the conventional problem.

SUMMARY OF THE INVENTION

It is therefore one object of this invention to provide a fluid-filled vibration-damping device novel in construction and capable of establishing an excellent fluid-tight sealing its chambers fluid with a non-compressible fluid with simple structure.

The above and/or other objects of this invention may be attained according to at least one of the following modes of the invention. Each of these modes of the invention is numbered like the appended claims and depending from the other mode or modes, where appropriate, to indicate possible combinations of elements or technical features of the invention. 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.

(1) A fluid-filled vibration-damping device for connecting two members in a vibration damping fashion, comprising: (a) a first mounting member connectable to one of the two members; (b) a second mounting member connectable to an other of the two member; (c) an elastic body bonded at an central portion thereof to the first mounting member and at an outer circumferential portion thereof to the second mounting member in a process of vulcanization of a rubber material for forming the elastic body, for elastically connecting the first and second mounting members; (d) a pressure-receiving chamber disposed on one of axially opposite sides of the elastic body, filled with a non-compressible fluid and partially defined by the elastic body, to which a vibrational load is applied; (e) a flexible rubber layer disposed on an other one of axially opposite side of the elastic body so as to form an equilibrium chamber between the flexible rubber layer and the elastic body, the equilibrium chamber being filled with the non-compressible fluid and partially defined by the flexible rubber layer so as to easily permit a volumetric change thereof; and (f) a first orifice passage for fluid communication between the pressure-receiving chamber and the equilibrium chamber. The first mounting member includes an elastic-body central member bonded to the central portion of the elastic body, and a rubber-layer central member bonded to a central portion of the flexible rubber layer and having a fixing portion at which the first mounting member is connected to the one of the two member, and the elastic-body central member and the rubber-layer central member are superposed on and fixed to each other at their abutting surfaces by means of a fixing mechanism, to thereby constitute the first mounting member. One of the elastic-body central member and the rubber-layer central member has a fitting recess open in the abutting surface thereof, and an other one of the elastic-body central member and the rubber-layer central member has a fitting protrusion formed on the abutting surface thereof and being fitted into the fitting recess so that the elastic-body central member and the rubber-layer central member are positioned relative to each other, and a peripheral portion of an interface between the abutting surfaces of the elastic-body central member and the rubber-layer central member entirely faces the equilibrium chamber and/or the pressure-receiving chamber.

In the fluid-filled vibration-damping device according to this mode of the invention, the peripheral portion of the interface between the abutting surfaces of the elastic-body and rubber-layer central members entirely faces to the equilibrium chamber and/or the pressure-receiving chamber, without being exposed to the external area or the atmosphere, thus preventing undesirable leakage of the non-compressible fluid through the interface between these central members. Therefore, the fluid-filled vibration-damping device of this mode of the invention is capable of securing a high fluid-tight sealing of the fluid chambers filled with the non-compressible fluid.

Also, the use of the fitting mechanism established the fitting recess and the fitting projection enables to position the elastic-body central member and the rubber-layer central member relative to each other with ease and preciseness, thus achieving improvement both in production efficiency and product quality. Moreover, the use of the combination of the fitting recess and the fitting projection prevents the engagement of the elastic-body central member and the rubber-layer central member loosing, thus establishing the high fluid-tight sealing of the chambers filled with the non-compressible fluid for a long period of time.

The fixing portion of the rubber-layer central member may have a variety of forms including a bolt or a threaded nut. The fixing mechanism for fixing the elastic-body and the rubber-layer central members together may be selected from known fixing mechanism established by pressing and by calking, and other possible fixing structures, e.g., a bolt or the like.

(2) A fluid-filled vibration-damping device according to the above mode (1), wherein the fitting recess has an inner circumferential surface with a tapered shape that corresponds to a tapered shape of an outer circumferential surface of the fitting protrusion. The fluid-filled vibration-damping device according to this mode of the invention permits an improved efficiency in assembling the elastic-body central member and the rubber-layer central member together, since these tapered surfaces function as a guide.

(3) A fluid-filled vibration-damping device according to the above-indicated mode (2), wherein the fitting recess includes a press-fitting hole formed in a bottom wall thereof so as to axially extend with a substantially constant inner diameter, while the fitting protrusion includes a press-fitting part integrally formed at a protruding end portion thereof, the press-fitting part being press-fitted into the press-fitting hole to thereby provide the fixing mechanism. According to this mode of the invention, the fixing mechanism can be embodied with simple structure. The press-fitting part may be provided with a cutout portion as needed, in order to reduce the weight thereof or alternatively to reduce a press-fitting force that is applied by the press-fitting part to the press-fitting hole upon the press-fitting. The press-fitting hole may be a recess or alternatively be a bore extending through the bottom wall of the fitting recess.

(4) A fluid-filled vibration-damping device according to any one of the above-indicated modes (1)-(3), wherein the elastic-body central member includes a fixing bore open in the abutting surface thereof and extending therethrough in a direction in which the elastic-body central member and the rubber-layer central member are superposed on each other, while the rubber-layer central member includes a fixing shaft protruding therefrom, the fixing shaft extending through the fixing bore and disengageably fixed at a tip end thereof to the elastic-body central member, to thereby provide the fixing mechanism. This arrangement enables the elastic-body central member and the rubber-layer central member to be firmly engaged together, thereby exhibiting a strong force resistive to an axial force that causes disengagement of the elastic-body and rubber-layer central members. The fixing bore and the fixing shaft may be constituted by the press-fitting hole and the press-fitting part constructed according to the above-indicated mode (3). The fixing shaft may be formed as an integral part of the rubber-layer central member, or may be formed independently of and bonded to the rubber-layer central member by means of known fastening members, e.g., screws or the like. Further, a variety of methods are adoptable for disengageably fixing the fixing shaft to the fixing bore. For instance, the fixing shaft is disengageably fixed to the fixing bore such that a tip end portion of the fixing shaft is calked against the open-end portion of the fixing bore, or alternatively such that the tip end of the fixing shaft is provided with a bolt or rivet that is fitting on the open-end portion of the fixing bore.

(5) A fluid-filled vibration-damping device according to any one of the above-indicated modes (1)-(4), further comprising: an elastic-body outer sleeve member bonded to an outer circumferential portion of the elastic body; and a rubber layer outer sleeve member bonded to an outer circumferential portion of the flexible rubber layer, wherein the elastic-body and rubber-layer outer sleeve members are fixed together to constitute the second mounting member, and cooperate with each other to at least partially define the first orifice passage therebetween. This arrangement makes it possible to form the first orifice passage that is simple in construction with a reduced number of components, resulting in improved efficiency and reduced cost of manufacture of the orifice member. These outer sleeve members may be formed of metallic or synthetic resin members having cylindrical or circumferential wall portions utilized to define the first orifice passage.

(6) A fluid-filled vibration-damping device according to any one of the above-indicated modes (1)-(5), further comprising a narrow passage adapted to connect the interface between the abutting surfaces of the elastic-body central member and the rubber-layer central member to at least one of the equilibrium chamber and the pressure-receiving chamber. In the fluid-filled vibration-damping device according to this mode of the invention, the narrow passage may be utilized to suction an air undesirably remained within the equilibrium chamber and/or the pressure-receiving chamber, upon assembling the elastic-body central member and the rubber-layer central member together Thus, the fluid-filled vibration-damping device can exhibit an improved stability in terms of its quality and capability

(7) A fluid-filled vibration-damping device according to any one of the above-indicated modes (1)-(6), wherein the first mounting member includes an injection bore extending through the elastic-body and rubber-layer central members in a direction in which the central members are superposed on each other, and an opening of the injection bore is fluid-tightly closed by a sealing member after filling the device with the non-compressible fluid through the injection bore. In the fluid-filled vibration-damping device according to this mode of the invention, the injection bore may be utilized to perform a known vacuum suction method for filling the pressure-receiving chamber and the equilibrium chamber with the non-compressible fluid. More specifically, the pressure-receiving and the equilibrium chambers are vacuumed through the injection bore, and then filled with the non-compressible fluid through the injection bore instantly, ensuring an easy and rapid filling operation. Also, the opening of the injection bore is fluid-tightly closed or sealed by means of a suitably sealing member after the termination of the process to fill the equilibrium and pressure-receiving chamber with the non-compressible fluid, thus eliminating a problem of leakage of the non-compressible fluid through the injection bore. That is, the fluid-filled vibration-damping device of this mode of the invention permits both of the desired high fluid-tight sealing of the device and an improved efficiency in the process of filling the pressure-receiving chamber and the equilibrium chamber with the non-compressible fluid. A known blind rivet or the like may be preferably employed as the sealing member adapted to fluid-tightly close the opening of the injection bore.

(8) A fluid-filled vibration-damping device according to any one of the above-indicated modes (1)-(7), further comprising: a heat shielding sleeve disposed radially outwardly of the flexible rubber layer and fixed at one of axially opposite end portion thereof to the second mounting member, wherein an other one of axially opposite end portion of the heat shielding sleeve extends radially inwardly so as to provide a stop portion that is opposed to the first mounting member with a given spacing in an axial direction of the device and/or a radial direction perpendicular to the axial direction, and the stop portion is brought into abutting contact with the first mounting member via a buffer so as to limit an amount of displacement of the first and second mounting members relative to each other.

It should be noted that the flexible rubber layer, which is a thin-walled member having a low strength and a great amount of deformation, is disposed radially outward of the elastic body and located in the outermost portion of the fluid-filled vibration-damping device. The flexible rubber layer may possibly be damaged due to undesirable contacts with other components and be affected by heat emitted from the internal engine mount or the like, JP-A-10-38016 discloses a technique to cope with this problem, in which the flexible rubber layer is formed of a heat resistive rubber material different from the material of the elastic body. The proposed technique undesirably limits materials of the flexible rubber layer in view of its heat resistance, resulting in insufficient properties of the flexible rubber layer in terms of corrosion resistance, ozone resistance, physical strength and the like. However, the heat shielding sleeve is disposed radially outwardly of the flexible rubber layer and substantially entirely covers the flexible rubber layer in this mode of the invention. Therefore, the flexible rubber layer is effectively prevented from possible damages due to the contact with the other components, and possible deterioration caused by the heat emitted from an internal combustion engine or the like. This arrangement leading to an enhanced degree of freedom in selecting materials of the elastic body and the flexible rubber layer as well, thus ensuring desired durability and properties of the flexible rubber layer in terms of ozone, chemical and heat resistances. Also, the thin-walled flexible rubber layer is likely to transmit heat emitted from the outside to the fluid filled within equilibrium chamber, possibly leading to undesirable change in the viscosity of the fluid and gas separation occurred within the fluid, resulting in deterioration of the damping characteristics of the vibration damping device. The use of the heat shielding sleeve is able to eliminate this inherent problem in the fluid-filled vibration-damping device where the flexible rubber layer is disposed in the outermost position of the device.

In addition, the heat shielding sleeve also functions to constitute a stop mechanism in cooperation with the first mounting member in order to limit an amount of displacement of the first and second mounting member relative to each other in a shock absorbing manner. That is, the present mode (8) of the invention makes it possible to provide not only the heat shielding mechanism but also the stop mechanism as well with simple structure in a fluid-filled vibration-damping device having a unique structure in which the equilibrium chamber is disposed on the axially outward of the elastic body.

The stop portion of the heat shielding sleeve may be used to constitute a stop mechanism arranged to limit an amount of displacement of the first and second mounting members relative to each other in one or both of opposite axial directions of these mounting members. Alternatively, the stop mechanism may be arranged to limit an amount of displacement of the first and second mounting members relative to each other in a direction perpendicular to the axial direction, instead of or in addition to the axial direction. For instance, the first mounting member is integrally or fixedly provided with a recess open in its outer circumferential surface with a rectangular shape in its cross section, and the stop member of the heat shielding sleeve is disposed within the recess, so that the stop member is opposed to the inner surface of the recess in both of the axial and radial directions of the first and second mounting members via a suitable buffer. As a result, the stop member and the recess cooperate to form a multi-directional stop mechanism capable of limiting the displacement of the first and second mounting members in various directions with a simple structure and reduced numbers of components.

(9) A fluid-filled vibration-damping device according to the above-indicated mode (8), further comprising: an elastic-body outer sleeve member bonded to an outer circumferential portion of the elastic body; and a rubber-layer outer sleeve member bonded to an outer circumferential portion of the flexible rubber layer, the elastic-body and rubber-layer outer sleeve members being fixed together to partially constitute the second mounting member, wherein the rubber-layer central member extends radially outwardly from the elastic-body central member so as to provide an abutting portion that is brought into abutting contact with the stop portion of the heat shielding sleeve in the axial direction of the device, and the flexible rubber layer is bonded at the central portion thereof to the abutting portion of the rubber-layer central member, while the one of axially opposite end portion of the heat shielding sleeve is mounted on an outer circumferential surface of the rubber-layer outer sleeve member, and is fixed to the second mounting member by calking. In this arrangement, the rubber-layer central member is effectively utilized to provide the abutting portion with which the stop portion of the heat shielding sleeve is brought into contact, while avoiding undesirable enlargement of the first mounting member. Further, the flexible rubber layer is formed independently of the elastic body, thereby enhancing a degree of freedom in selecting materials of the elastic body and the flexible rubber layer.

(10) A fluid-filled vibration-damping device according to the above-indicated mode (9), further comprising a sealing rubber integrally formed at an outer peripheral portion of the flexible rubber layer over an entire circumference thereof so as to prevent entry of water into an interface between the heat shielding sleeve and the rubber-layer outer sleeve member. This arrangement is effective to prevent undesirable entry of water or other objects into the interference between the rubber-layer outer sleeve member and the heat shielding sleeve, thereby effectively preventing undesirable rust of these sleeve members. Preferably, the heat shielding sleeve may be provided with a drain hole located adjacent to the sealing portion between the heat shielding sleeve and the rubber-layer outer sleeve member in order to promptly drain water or other objects gathered at the sealing portion.

(11) A fluid-filled vibration-damping device according to any one of the above-indicated modes (8)-(10), wherein the second mounting member has a tapered cylindrical portion formed at one of axially opposite end portion thereof and extending axially outwardly and radially outwardly, and the outer circumferential portion of the elastic body is bonded to the tapered cylindrical portion, and wherein the tapered cylindrical portion is provided with a cutout, while the elastic body is provided with a guide groove formed at a first circumferential position thereof so as to be contiguous with the cutout and so as to extend to the equilibrium chamber so that the cutout and the guide groove cooperate to connect the first orifice passage to the equilibrium chamber.

This arrangement permits the elastic body to be supported at its outer circumferential portion by the tapered cylindrical portion, so that the elastic body can exhibit an approximately linear spring characteristics with stability with respect to a compressive load in the axial direction. Moreover, the axially lower side of the tapered cylindrical portion that is remote from the elastic body may be effectively utilized to provide the first orifice passage with high space utilization. The guide groove may be formed on the outer circumferential surface of the elastic body with various shapes so as to extend in various directions. For instance, the guide groove is formed on the outer circumferential surface of the elastic body so as to extend in the axial direction.

(12) A fluid-filled vibration-damping device according to the above-indicated mode (11), wherein the guide groove has a slope-like shape in which a depth dimension gradually decreases with an increase of a distance from the cutout. This arrangement facilitates smooth flows of the non-compressible fluid through the guide groove from the equilibrium chamber to the first orifice passage, whereby the vibration-damping device can exhibit a damping effect on the basis of the flows of the fluid in an effective manner.

The guide groove may extends on the outer circumferential surface of the elastic body in the axial direction, or alternatively in the circumferential direction. In the latter case, the guide groove functions to guide the fluid to flow in the direction approximate to a direction in which the fluid flows through the first orifice passage, and to elongate the guide groove, resulting in further improved smoothness of the flows of the fluid through the first orifice passage and the equilibrium chamber.

(13) A fluid-filled vibration-damping device according to the above-indicated mode (12) wherein the elastic body further includes a volume balancing portion formed at a second circumferential position thereof so that a volume of the elastic body is well balanced about a central axis of the elastic body. The volume balancing portion of this mode of the invention makes it possible to well balance the volume of the elastic body about its central axis, thus preventing that the damping or supporting capability of the vibration-damping device is adversely effected or deteriorated by the guide groove formed on the elastic body. This arrangement permits a desired spring characteristics of the elastic body with respect to a static and active load in a stable manner, and eliminates stress concentration at a portion in which the guide groove is formed, resulting in improved durability of the elastic body.

The volume balancing portion may have a variety forms. For instance, the volume balancing portion may be a cutout formed at the second circumferential position that is symmetrical to the first circumferential position with respect to the central axis of the elastic body, or alternatively may be a boss formed on an inner circumferential surface of the elastic body at a circumferential position corresponding to that of the guide groove.

(14) A fluid-filled vibration-damping device according to any one of the above-indicated modes (1)-(14), further comprising: a movable member partially defining the pressure-receiving chamber and being elastically supported by the second mounting member so as to be displaceable relative to the second mounting member; and an oscillating mechanism adapted to apply an oscillating force to the oscillating member in order to actively induce a fluid-pressure variation in the pressure-receiving chamber. That is, the movable member and the oscillating force cooperate each other to provide the oscillating mechanism in the present embodiment. According to this mode of the invention, an active-type fluid-filled vibration-damping device may be embodied, in which the fluid-pressure variation induced in the pressure-receiving chamber upon application of vibrational loads to the pressure-receiving chamber can be actively compensated or reduced by the oscillating force generated by the oscillating member.

In the case where the first orifice passage is disposed outside of the pressure-receiving chamber, the pressure-receiving chamber is allowed to have a relatively large volume and the movable member can face to the pressure-receiving chamber with a relatively large surface area. Therefore, such a movable member can generate a relatively large amount of fluid-pressure variation in the pressure-receiving chamber by a relatively small amount of displacement thereof. Meanwhile, the oscillating mechanism may be selected from a pneumatic-type, an electrostrictive-type and a magnetostrictive-type actuator as well as an electrostrictive-type actuator, by way of example.

Preferably, the pressure-receiving chamber is divided by a partition member into a primary fluid chamber partially defined by the elastic body and an auxiliary fluid chamber partially defined by the movable member, and these primary and auxiliary fluid chambers are held in fluid communication through a second orifice passage. In this arrangement, fluid-pressure variation induced in the auxiliary fluid chamber by the oscillation of the movable member is efficiently transmitted to the pressure-receiving chamber with the help of resonance of the fluid flowing through the second orifice passage. As a result, the fluid-filled vibration-damping device of this arrangement can exhibit an active damping effect in an effective manner, with respect to vibrations whose frequency is held within a frequency range to which the second orifice passage is tuned.

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 vertical or axial cross section of a fluid-filled vibration-damping device in the form of an engine mount constructed according to a first embodiment of the present invention;

FIG. 2 is an elevational view in vertical cross section of an integral vulcanized product of an elastic body as a component of the engine mount of FIG. 1;

FIG. 3 is an elevational view in vertical cross section of an integral vulcanized product of a flexible diaphragm as a component of the engine mount of FIG. 1;

FIG. 4 is a fragmentary view in vertical cross section of an engine mount constructed according to a second embodiment of the present invention, where a principle part of the mount is shown;

FIG. 5 is a fragmentary view in vertical cross section of an engine mount constructed according to a third embodiment of the present invention, where a principle part of the mount is shown;

FIG. 6 is a fragmentary view in vertical cross section of an engine mount constructed according to a fourth embodiment of the present invention, where a principle part of the mount is shown;

FIG. 7 is a fragmentary view in vertical cross section of an engine mount constructed according to a fifth embodiment of the present invention, where a principle part of the mount is shown;

FIG. 8 is a fragmentary view in vertical cross section of an engine mount constructed according to a sixth embodiment of the present invention, where a principle part of the mount is shown;

FIG. 9 is a fragmentary view in vertical cross section of an engine mount constructed according to a seventh embodiment of the present invention, where a principle part of the mount is shown;

FIG. 10 is a fragmentary view in vertical cross section of an engine mount constructed according to an eighth embodiment of the present invention, where a principle part of the mount is shown;

FIG. 11 is an elevational view in vertical cross section of an engine mount constructed according to a ninth embodiment of the present invention;

FIG. 12 is a plane view of the engine mount of FIG. 11;

FIG. 13 is an elevational view in vertical cross section of an engine mount constructed according to a tenth embodiment of the present invention; and

FIG. 14 is an elevational view in vertical cross section of an engine mount constructed according to the present invention wherein further possible modifications are incorporated.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring first to FIG. 1, an engine mount 10 for use in an automotive vehicle is shown as a first embodiment of a fluid-filled vibration-damping device of the present invention. This engine mount 10 includes a first mounting member 12 and a second mounting member 14, which are made of suitable metallic materials. These first and second mounting members 12, 14 are elastically connected to each other by an elastic body 16 interposed therebetween. The first mounting member 12 is adapted to be attached to a power unit of the vehicle, while the second mounting member 14 is adapted to be attached to a body of the vehicle, so that the power unit is mounted on the vehicle body in a vibration damping fashion. With the engine mount 10 installed on the vehicle as described above, a static load or weight of the power unit and a primary vibrational load act between the first and second mounting members in an approximately axial direction of the engine mount, that is generally parallel to the vertical direction as seen in FIG. 1. In the following description, the vertical direction is basically oriented in the vertical direction as seen in FIG. 1.

Described in detail, the first mounting member 12 includes an elastic-body central member in the form of an elastic-body inner metal member 18 and a rubber-layer central member in the form of a diaphragm inner metal member 20, while the second mounting member 14 includes an elastic-body outer sleeve member in the form of an elastic-body outer-cylindrical metal member 22 and a rubber-layer outer sleeve member in the form of a diaphragm outer-cylindrical metal member 24 and a rid-metal-plate member 26. The elastic body 16 is bonded at its central portion to the elastic-body inner metal member 18 and at its outer circumferential portion to the elastic body outer-circumferential metal member 22 in the process of vulcanization of a rubber material to form the elastic body 16, thereby providing a first integral vulcanized product 28 (shown in FIG. 2). On the other hand, a flexible rubber layer in the form of a flexible diaphragm 30 is bonded at its central portion to the diaphragm inner metal member 20 and at its outer circumferential portion to the diaphragm outer-cylindrical metal member 24 in the process of vulcanization of a rubber material to form the flexible diaphragm 30, thereby providing a second integral vulcanized product 32 (shown in FIG. 3). These first and second integral vulcanized products 28, 32 are assembled together.

Referring back to FIG. 2, the elastic-body inner metal member 18 as one component of the first integral vulcanized product 28, has an inverted generally truncated conical shape, and is formed with a fixing bore 34 extending therethrough in its axial direction and open in its axially opposite ends, i.e., a large diameter end face and a small diameter end face. The axially upper end portion of the fixing bore 34 serves as a fitting recess in the form of a guide bore 36 having an inner surface with a mortar or tapered shape so that the guide bore 36 has a diameter gradually increasing toward the large diameter end face. The axially lower end portion of the guide bore 36 serves as a press-fitting hole in the form of a cylindrical fitting bore 38 extending axially downwardly with a generally constant inner diameter, to be open in the small diameter end face of the elastic-body central member.

The elastic-body outer-cylindrical metal member 22 includes a cylindrical wall portion 40 with a generally large diameter thin-walled cylindrical shape, a flange portion 42 integrally formed at an axially lower end portion of the cylindrical wall portion 40 so as to extend radially outwardly, and a tapered cylindrical portion 44 integrally formed at an axially upper end portion of the cylindrical wall portion 40. The diameter of the tapered cylindrical portion 44 gradually increases in the axially outward direction. The elastic-body outer-cylindrical metal member 22 constructed as described above thus provides a circumferential groove open in its outer circumferential surface. The elastic-body inner metal member 18 is disposed on the side of the tapered cylindrical portion 44 of the elastic-body outer-cylindrical metal member 22 with a given axial spacing therebetween, while being held in a generally concentric or coaxial relationship with the elastic-body outer-cylindrical metal member 22. In this state, the tapered outer circumferential surface of the elastic-body inner metal member 18 is spaced away from and opposed to the tapered cylindrical portion 44 of the elastic-body outer-cylindrical metal member 22 in the axial direction of the engine mount 10, and these opposed surfaces of the elastic-body inner metal member 18 and the tapered cylindrical portion 44 are elastically connected with each other via the elastic body 16 interposed therebetween.

The elastic body 16 has a generally truncated conical shape, and is bonded at its central portion to the elastic-body inner metal member 18, which extends through the central portion of the elastic body 16 along the axis of the engine mount 10, in the process of vulcanization of a rubber material to form the elastic body 16. The elastic body 16 is superposed and bonded at its large-diameter outer circumferential surface on and to the tapered cylindrical portion 44 of the elastic-body outer-cylindrical metal member 22, in the above-described vulcanization. Thus, it is formed the first vulcanized product 28 consisting of the elastic body 16, the elastic-body inner metal member 18 and the elastic-body outer-cylindrical member 22. A sealing rubber layer 46 integrally formed with the elastic body 16 coats and is bonded to a substantially entire area of an inner circumferential surface of the cylindrical portion 40 of the elastic body outer cylindrical metal member 22, and extends at its lower end portion to the lower surface of the flange portion 42.

On the other hand, the diaphragm inner metal member 20 as one component of the second integral vulcanized product 32 includes an abutting portion in the form of a disk-shaped portion 48 extending radially outwardly therefrom, and a fixing portion in the form of a boss-shaped projection 50 protruding axially outwardly from the disk-shaped portion 48, as integrally formed parts. The boss-shaped projection 50 has a tapped hole 52, thereby serving as a fixing nut. Thus, the diaphragm inner metal member 20 and the first mounting member 12 are firmly fixed to the power unit of the vehicle by a mounting bolt (not shown) threaded into the tapped hole 52.

Further, the diaphragm inner metal member 20 includes a rod shaped fixing shaft 54 integrally formed at its axially intermediate portion so as to protrude axially downwardly. The axially upper portion of the fixing shaft 54 serves as a fitting protrusion in the form of a fitting guide protrusion 56, while the axially lower portion of the fixing shaft 54 serves as a press-fitting portion 58. Described in detail, the fitting guide protrusion 56 includes a tapered outer circumferential surface with an outer diameter gradually decreasing in the axially downward direction from the bottom surface of the disk-shaped portion 48 to the press-fitting portion 58. The fitting guide protrusion 56 has an outer configuration or profile that confirms to an inner surface configuration or profile of the fitting guide recess 36 of the elastic-body inner metal member 18, while having a size that is substantially equal to and slightly smaller than the size of the fitting guide recess 36. On the other hand, the press-fitting portion 58 has a generally circular rod shape and extends axially straightly with a substantially same diameter that is made substantially equal to or slightly smaller than the inner diameter of the fitting bore 38 of the elastic-body inner metal member 18. The fixing shaft 54 includes a recess 60 open in the axially lower end of the fixing shaft 54 and extends in the axial direction with a given axial depth. In the presence of the recess 60, the axially lower end portion of the fixing shaft 54 serves as a calking part 62. FIG. 3 shows a state of the calking part 62 before being calked against the elastic-body inner metal member.

The diaphragm outer-cylindrical metal member 24 has a thin-walled large-diameter cylindrical shape, and includes an annular inward projection 64 integrally formed at its axially upper open end portion so as to slightly protrude radially inwardly, and a flange portion 66 integrally formed at its axially lower open-end portion so as to extend radially outwardly. The protruding end portion of the flange portion 66 is bent axially downwardly, to thereby provide an integrally formed annular fitting surface 68. The diaphragm inner metal member 20 is disposed on the side of the inner projection 64 with an axial and radial spacing therebetween, while being held in coaxial relationship with the inner projection 64. The diaphragm inner metal member 20 and the diaphragm outer sleeve member 24 are elastically connected with each other via the flexible diaphragm 30.

The flexible diaphragm 30 has a generally thin-walled annular plate-like shape, and has a large amount of slag at its central portion for facilitate elastic deformation thereof. In other words, the flexible diaphragm 30 is a bellows-shaped member extending axially outwardly and radially outwardly. The inner peripheral portion of the flexible diaphragm 30 is bonded to an outer circumferential surface of the disk-shaped portion 48 of the diaphragm inner metal member 20 in the process of vulcanization of a rubber material for forming the flexible diaphragm 30. The outer peripheral portion of the flexible diaphragm 30, on the other hand, is bonded to the inward projection 64 of the diaphragm outer cylindrical metal member 24 in the above-described vulcanization. Thus, it is formed the second integral vulcanized product 32 consisting of the flexible diaphragm 30, the diaphragm inner metal member 20 and the diaphragm outer cylindrical metal member 24. A sealing rubber 70 integrally formed with the flexible diaphragm 30 coats and is bonded to a substantially entire area of the inner circumferential surface of the diaphragm outer cylindrical metal member 24, such that an axially upper end portion of the sealing rubber 70 coats entirely the inward projection 64, and an axially lower end portion of the sealing rubber 70 extends to the lower surface of the flange portion 66.

The thus formed second integral vulcanized product 32 is superposed on and assembled with the first integral vulcanized product 28 in the vertical or axial direction, such that the diaphragm inner metal member 20 is fixed to the elastic-body inner metal member 18, and the diaphragm outer cylindrical metal member 24 is fixed to the elastic-body outer-cylindrical metal member 22. In this state, the flexible diaphragm 30 is disposed radially outwardly of the elastic body 16 with a given spacing therebetween, so as to surround an entire outer circumferential surface of the elastic body 16.

That is, the disk-shaped portion 48 of the diaphragm inner metal member 20 is held in close contact with the upper end face of the elastic-body inner metal member 18, and the fitting guide protrusion 56 and the press-fitting portion 58 of the fixing shaft 54 of the diaphragm