GB2304170A

GB2304170A - Fluid damping mount

Info

Publication number: GB2304170A
Application number: GB9616086A
Authority: GB
Inventors: Jin Shy Gau; Jeffry D Cotton
Original assignee: BTR Antivibration Systems Inc
Current assignee: Metzeler Automotive Profile Systems Iowa Inc
Priority date: 1995-08-08
Filing date: 1996-07-31
Publication date: 1997-03-12
Also published as: ES2138496B1; BR9603330A; ES2138496A1; JPH09119476A; KR970011492A; GB9616086D0; DE19632098A1

Description

2304170 PLUID DAMPING XODUT is The present invention relates to a fluid

damping mount. More particularly, the present invention relates-to a fluid damping mount used in vehicle suspensl.Lons and power train applications including a vibration absorbing elastomeric body defining two load bearing chambers and containing a damping fluid. The two load bearing chambers are in communication with one another through an inertia track for damping vibrations as a function of the flow of the damping fluid contained therein and the volume stiffness of the chambers.

A fluid damping mount is generally used in a vehicle to damp vibrations at particular frequencies. The fluid damping mount typically includes a vibration absorbing elastomeric body having one or more load bearing chambers containing a damping fluid. The load bearing chambers are in communication with one another through an inertia track. Depending upon the intended application of the fluid mount, the fluid damping mount may be subjected to oscillations oriented along the diametrical direction or compressive forces along the axial direction in such a manner that the fluid within the chambers flows between the chambers through the inertia track as a function of the deformation of the elastomeric body. The deformation of the elastomeric body and the displacement of the fluid within the chambers damp or isolate the noise and/or vibrations generated during operation of the vehicle.

Fluid damping mounts may be typically divided into two main types 1) those in which only one of two 0 chambers bears the load and 2) those in which both chambers bear the load. Each type has certain characteristics which make it more suitable for a particular application. The single load bearing chamber type fluid mount has one stiff chamber (the load bearing chamber) and one very soft chamber. The oft chamber usually includes a soft diaphragm to educe the chamber volume stiffness. Chamber volume stiffness is defined as a pressure change for a unit change in the chamber volume. The single load bearing chamber type fluid mount is generally used in engine mount applications in a compression mode. In contrast, the two load bearing chamber type fluid mount has two stiff chambers. The two load bearing chamber type fluid mount is generally used in vehicle suspension applications in a shear mode.

It will be appreciated.that the typical two load bearing chamber fluid mount provides considerable damping characteristics, loss stiffness (K"), at particular frequencies, such as during engine idling. At low frequencies the elastomeric body and fluid inside the inertia track vibrate in phase causing the fluid damping mount to function as a conventional rubber mount. However, as the vibration frequency reaches the damping fluid resonance of about 50 Hz or more, the elastomeric body and the damping fluid inside the chamber vibrate 90 degrees out of phase due to fluid inertia. As a result of the 90 degrees phase shift, the storage stiffness (M) of the chamber increases considerably reducing the damping characteristics (loss stiffness (KN)) of the mount. Furthermore, at higher frequencies, about 80 Hz or more, the elastomeric body and the damping fluid inside the inertia track vibrate 180 degrees out of phase a 41 ' is causing the fluid mount to have a very high storage stiffness (M) above fluid resonance.

Although heretofore known fluid mounts have been proven to perform satisfactorily under certain conditions, further improvements on fluid damping mounts are desired. An object of the present invention is to provide a two load bearing chamber type fluid damping mount which utilizes individual pneumatically controlled flexible diaphragms to provide variable damping characteristics so as to more efficiently isolate vibrations over the entire range of vehicle operating and road conditions. Yet another object of the present invention is to provide a two load bearing chamber type fluid damping mount whereby the fluidfilled chambers within the damping mount can be selectively activated or deactivated to provide a volume stiffness at frequenaies above the fluid resonance and, when desired, a damping function characteristic of a conventional rubber mount. Still another object of the present invention is to provide a two'load bearing chamber type fluid damping mount having two fluid chambers of a controlled volume stiffness. Another object of the present invention is to provide a two load bearing chamber type fluid damping mount that is simple and economical to manufacture.

Briefly, according to this invention, there is provided a two load bearing chamber type fluid damping mount for interconnection between a vibrating body and a base for damping vibrations from the vibrating body. The twu load bearing chamber type fluid damping mount includes an inner metal, an elastomeric body, a support member and an inertia track. The inner metal is a is cylindrical member operatively connected to the base. The elastomeric body circumscribes the inner metal and includes two load bearing chambers containing a substantially incompressible damping fluid. The support member is operatively connected to the vibrating body and the elastomeric body. The inertia track passage provides fluid communication between the load bearing chambers. In addition, the fluid mount includes a means for reducing the volume stiffness of at least one of the load bearing chambers.

The Invention will now be further described by way of eKample with reference to the accompanying drawings in which: - Figure 1 is an exploded, perspective view of a fluid damping mount in accordance with the present i:wention; Figure 2 is a cross sectional view of the fluid damping mount of Figure 1 taken along line 1-1; Figure 3 is a cross sectional view of the fluid damping mount of Figure 2 taken along line 2-2; Figure 4 is a cross sectional view of another embodiment of a fluid damping mount in accordance with the present invention; Figure 5 is a cross sectional view of the fluid damping mount of Figure 4 taken along line 4-4; Figure 6 is a cross sectional view of an elastomeric body of a fluid damping mount in accordance with the present invention; Figure 7 is an exploded, perspective view of a fluid damping mount in accurdance with the present invention; Figure 8 is an exploded, perspective view of a decoupler of a fluid damping mount in accordance with the present invention; Figure 9 is a cross sectional view of the f luid damping mount of Figure 7 taken along line 7-7; Figure 10 is a cross sectional view of the fluid damping mount of Figure 9 taken along line 10-10; Figure 11 is a cross sectional view of another embodiment of a fluid damping mount in accordance with the present invention; Figure 12 is a cross sectional view of the fluid damping mount of Figure 11 taken along line 12-12; Figure 13 is a cross sectional view of an elastomeric body of a fluid damping mount in accordance with the present invention; Figure 14 is a partial sectional perspective view of a damping mount in accordance with the present invention; Figures 15-17 are cross sectional views of different embodiments of a damping mount in accordance with'the present invention; Figure 18 is an exploded, perspective view of yet another embodiment of a damping mount in accordance with the present invention; Figure 19 is a cross sectional view of a damping mount in accordance with the present invention; Figure 20 is a cross sectional view of the damping mount of Figure 19 taken along line 20-20; Figures 21 and 22 are partial sectional views of an intermediate member of an elastomeric body of a fluid damping mount in accordance with the present invention; Figure 23 is a cross sectional view of a damping mount in accordance with the present invention; and 1 0 0 Figure 24 is a cross sectional view of the damping mount of Figure 23 taken along line 24-24.

is Referring to the drawings, wherein like reference characters represent like elements, there is-shown in the drawings a two load bearing chamber type fluid damping mount 10 for interconnection between a vibrating body, (e.g., an engine), and a base, (e.g., a chassis), for damping vibrations from the vibrating body. The fluid damping mount 10 generally includes an inner metal 12, an elastomeric body 14 circumscribing the inner metal and a support member 16. The support member 16 provides rigidity and an attachment point for the fluid damping mount 10 to the vibrating body (not shown) and the inner metal 12 serves as an attachment point to the base (not shown).% The support member 16 and the inner metal 12 may be formed of most any suitthble metal such as steel and the like. The elastomeric body 14 may be f ormed of a homogeneous elastomer material (Figures 1-5, 7, 9-12) such as natural rubber, synthetic rubber or plastic and the like or the elastomeric body may be formed from two different elastomer materials (Figures 6 and 13) to provide an elastomeric body having a dual durometer hardness. The durometer hardness of the elastomer materials forming the elastomeric body 14 may range between about 55 - 70 Shore A, and preferably about 65 Shore A. It will be appreciated that a dual durometer hardness elastomeric body 14 allows for the selective variation of the fluid resonant frequency of the mount and the volume stiffness and damping capability of the muunt.

Disposed within the elastomeric body 14 are two load bearing chambers, 18 and 20, containing a J substantially incompressible damping fluid 22 of a type well known in the art. The damping fluid 22 flows between the two load bearing chambers, 18 and 20, within an inertia track passage 24.

Incontrast to heretofore known two load bearing chamber type fluid damping mounts the fluid damping mount 10 includes a means for reducing the volume stiffness of at least one of the load bearing chambers such that the fluid mount is capable of functioning as a single load bearing chamber type fluid mount at the fluid resonance frequency (below about 20 Hz) or a double load bearing chamber type fluid mount at the fluid resonance frequency (above about 20 Hz) and, depending upon the configuration, as a conventional rubber mount.

Referring now to Figures 1-13, a two load bearing chamber type fluid damping mount 10 which may be used in a vehicle suspension is shown. The inner metal 12 may be connected to a tire knuckle of a vehicle while the support member 16 may be connected to the chassis of a vehicle (not shown) as well known in the art. With this connection, the elastomeric body 14 supports the chassis to dampen vibration from a dynamic load from the tire knuckle to the chassis. The inner metal 12 is a hollow cylindrical member and is concentric with the central axis of the support member 16. The Support member 16 is of a hollow cylindrical sleeve and circumscribes the elastomeric body 14. The inner metal 12 is fixably connected to the elastomeric body 14 by most any suitable method such as vulcanizing and the like such that the elastomeric body 14 is disposed between the inner metal 12 and the support member 16. The elastomeric body 14 includes radially positioned cavities 28 and 30 and load bearing chambers 18 and 20 a 1 which extend generally parallel to a longitudinal axis of the inner metal 12. The cavities 28 and 30 are formed in opposing portions of the upper half of the elastomeric body 14 and project through the sides of the elastomeric body. The chambers, 18 and 20, are formed in the top half and the bottom half of the elastomeric body 14 and project through the top circumferential edge and bottom circumferential of the elastomeric body, respectively..

The fluid damping mount 10 includes a means for reducing the volume stiffness of at least one of the load bearing chambers, IS and 20. As shown in Figures 1-3 and Figures 4 and 5, a flexible diaphragm 32 is attached to the inner wall of the support member 16 using techniques well known in the art to divide one or more of the load bearing chambers, IS and 20. The flexible diaphragm 32 partitions the chambers, 18 and/or 20, to define a first compartment 34 between tba diaphragm, elastomeric body and the support member 16 and a second compartment 35 between the diaphragm and the elastomeric body. The first compartment 34 includes an opening 36 for applying a Vacuum and/or a pressurized fluid or gas to the first compartment thereby creating a pressure change to actuate the flexible diaphragm 32. Formed between the load bearing chambers, 18 and 20, within the outer circumferential edge of the elastomeric body 14 are channels 38. The channels.38 cooperate with the inside surface of the support member 16 to form fluid containing inertia track passages 24 to provide -fluid communication between the chamber 20 and the second compartment 35. By selectively changing the applied pressure to the outer surface of the flexible diaphragm 32 the volume stiffness of at least one of the load bearing chambers - 9 18 and 20 and the dampening capacity of the fluid damping mount 10 at various frequencies may be controlled.

Referring to Figures 1-3, a mount having a single flexible diaphragm 32 to divide one of the load bearing chambers, 18 or 20, to define a first compartment 34 and,second compartment 35 is shown. A single load bearing chamber type fluid mount response may be obtained by not effecting a pressure change within the first compartment 34 of the load bearing chamber, 18 or 20, to change the chamber volume stiffness and a double load bearing chamber type fluid mount response may be obtained by applying a pressure. change within the first compartment 34 of the load bearing chamber, 18 or 20, to cause a change in the chamber volume stiffness. An increase in chamber volume stiffness effects an increase in loss stiffness KM and storage stiffness K' at increased frequency of the f luid mount.

Referring to FityC2es 4 and 5, a mount having a flexible diaphragm 32 dividing each of the load bearing chambers, 18 and 20, to define first compartments 34 and second compartments 35 is shown. A conventional rubber mount response may be obtained by not applying a pressure change to the flexible diaphragm 32. A single load bearing chamber type fluid mount response may be obtained by applying a pressure change within a first compartment 34 of only one load bearing chamber, 18 or 20, thereby changing the chamber volume and a double load bearing chamber type fluid mount response may be obtained by applying- a pressure change within both first compartments 34 of both load bearing chambers, 18 and 20, thereby changing the chamber volume of both chambers. An increase in chamber volume stiffness effects an increase in loss stiffness K" and storage stiffness K' at increased frequency of the fluid mount.

is It will be appreciated that the increase in chamber volume stiffness increases the resistance to flow of the damping fluid 22 between the load bearing chambers thereby increasing the resonant frequency of the damping fluid 22 in the inertia track passage 24 and the efficiency that vibration energy is converted into fluid motion such that the storage stiffness (V) of the fluid damping mount 10 is increased, i.e., the volume stiffness increases and the loss stiffness (K") also increases.

During low frequency vibrations, the flexible diaphragm 32 may be prevented from flexing by drawing a vacuum within the first compartment 34 of the chamber, 18 and/or 20. As a result, the damping fluid 22 encounters increased resistance to flow between the load bearing chambers, 18 and 20, thereby increasing the resonant frequency of the, damping fluid in the inertia track passage 24 and the efficiency that vibra(--ion energy is converted into fluid motion such that the storage stiffness K' of the fluid damping mount increases. As the vibration frequency increases above the damping fluid resonant frequency, e.g., at about 50 Hz., the inertial force of the damping fluid 22 within the chambers, 18 and 20, dramatically increases the storage stiffness (M) of the fluid damping mount 10. The storage stiffness (M) and loss stiffness (M) of the mount may be reduced by reversing the applied pressure within the first compartment 34 and permitting the flexible diaphragm(s) 32 to flex thereby decreasing the efficiency by which vibration energy is converted to fluid motion within the chambers, 18 and 20. In other words. as the flexible diaphragm 32 deflects, the amount of fluid which can be induced to resonate back and forth through the inertia track passage 24 tends to decrease,such that the damping affect of the fluid damping mount 10 becomes associated with the high dynamic spring constant of the elastomeric body 14.

Referring to Figures 7-12, yet another embodiment is shown. The means for reducing the volume stiffness of at least one of the load bearing chambers, 18 and 20, includes one (Figures 7, 9 and 10) or more decouplers 40 (Figures 11 and 12). The decoupler 40 functions as a valve to block the flow of fluid within the second compartment 35. The decoupler 40 is mounted in the second compartment 35 in either one or both of the chambers, 18 and 20, and includes an upper divider plate 42 and a lower divider plate 44 having an opening therein. The upper divider plate 42 and the lower divider plate 44 may be formed, for example, of a material such as a suitable plastic or metal as known in the art, The upper divider plate 42 and lower divider plate 44 are rigidly attached to the inner circumferential wall of the support member 16 using techniques well known in the art. A partition plate 46 having depending legs 48 is positioned between the upper and lower divider plates 42 and 44 and allowed to float freely therebetween for controlling the pressure from the flow of damping fluid 22 against the flexible diaphragm 32 within the chambers, 18 and 20. The partition plate 46 may be formed of a suitable plastic material such as nylon and the like.

Figures 7, 9 and 10 illustrate a single decoupler 40 mounted in the second compartment 35 defined by flexible diaphragm 32. A single load bearing chamber type fluid mount response may be obtained by not blocking the flow of fluid in the compartment and a double load bearing chamber type fluid mount response may be obtained by blocking the flow of fluid in the Compartment. Figures 11 and 12 illustrate a decoupler mounted in both of the second compartments 35 defined by the flexible diaphragm 32. A conventional rubber mount response may be obtained by not blocking the flow of fluid in either compartment, a single load bearing chamber type fluid mount response may be obtained by blocking the flow of fluid in only one compartment and a double load bearing chamber type fluid mount response may be obtained by blocking the flow of fluid within both compartments.

During periods when a vehicle suspension system generates high amplitude vibrations, the partition plate 46 compensates for the displacement of the elastomeric body 14 and the variations in the volume of the first and second chambers, 18 and 20, by moving against the opening in the upper divider plate 42 so that there is substantially no transfer of fluid beyond the upper divider plate to the diaphragm 32 thereby preventing application of a pressure change and eliminating the flexibility of tkAd1aphragms. More particularly, when the elastomeric body 14 is sufficiently deformed by a dynamic load the change in chamber volume creates a high pressure damping fluid surge within the chamber, 18 and/or 20, forcing the partition plate 46 to contact the upper divider plate 42 and substantially seal off the chamber from the corresponding flexible diaphragm 32 thereby increasing the volume stiffness (storage stiffness, KI) of the chamber and the damping characteristics of the fluid damping mount 10. Fluid flow under these conditions occurs only between the load bearing chambers, 18 and 20, without the damping affect of the flexible diaphragm 32. During periods when the elastomeric body 14 experiences low amplitude vibrations the resulting low fluid pressure is not large enough to cause the decoupler 4 0 to block the flow of, fluid within the compartments of the chambers by forcing the partition plate against the opening in the upper divider plate 42. Consequently, the diaphragms are allowed to flex thereby reducing the chamber volume stiffness and causing the mount to respond as a conventional rubber mount.

Figures 14 tb-17 illustrate another embodiment of a fluid damping mount 10. The fluid damping mount 10 includes a support member 16 in the form of a cylindrical collar 50 having a. radially outwardly projecting flange 52 extending through the sides of the elastomeric body 14 and adapted for connection to a source of vibration. Secured to each end of the elastomeric body are an upper cap element 54 and a lower cap element 56 having a central bore through' which the inner metal 12 extends. The elastomeric body 14 is vulcanized to a selected portion of the inner peripheral rim of the cap elements 54 and 56. The %inner metal 12 extends through the cap elements 54 and 56.

The elastomeric body 14, inner metal 12, cap elements 54 and 56 and support member 16 define load bearing chambers, 18 and 20. The load bearing chambers, 18 and 20, are cylindrical in shape and are in fluid communication through a cylindrical inertia track passage 24. The flexible diaphragm 32 is mounted within a portion of the upper and lower cap elements 54 and 56 and divides the load bearing chambers, 18 and 20, into a first compartment 34 and a second compartment 35.

The fluid mount of Figures 16 and 17 further includes a decoupler 40 which functions in a manner as previously described. The decoupler 40 may be formed integral with the support member 16 (Figure 17) or the decoupler may be formed integral with the upper and is lower cap element 54 and 56. Each decoupler 40 includes a partition plate 46 having depending legs 48 which freely float between a closed position and an open position for controlling the flow of damping fluid 22 against the flexible diaphragm 32 thereby adjusting the volume stiffness of the load bearing chambers, 18 and;,20. During high dynamic loads the pressure change in the load bearing chambers, 18 and 20, forces the partition plate 46 against a sealing surface thereby blocking damping fluid 22 from flowing to the diaphragm 32 and increasing the volume stiffness of the load bearing chambers, 18 and 20. Similarly, during low dynamic loads the small pressure changes in the chambers, 18 and 20, does not force the partition plate 46 against the sealing surface such that damping fluid 22 flows against the flexible diaphragm 32 allowing the diaphragm to flex and decrea&ing the volume stiffness of the load bearing chambers.

Figures 18-26 illustrate a fluid damping mount 10 having a support member 16 of an annular cylinder concentric with the inner metal 12. The elastomeric body 14 includes an upper cap element 54, a lower cap element 56 and an intermediate ring member 60. The upper and lower cap elements 54 and 56 are force fit between the inner metal 12 and support member 16 at opposing ends thereof to form a fluid tight seal between the inner metal and the support member. Similarly, the intermediate ring member 60 is secured between the upper and lower cap elements 54 and 56 by an interfering fit with the sides of the inner metal 12 and/or the sides of the support member 16 to define load bearing chambers, 18 and 20. A flexible diaphragm 32 is secured across the load bearing chambers, 18 and 20, to divide the load bearing chambers and provide separate first compartments 34 and-second compartments is - is - as previously described. The diaphragms 32 are held in place by support rings 62 which frictionally engage the contiguous surfaces of the inner metal 12 and the support member 16.

The inertia track passage may be provided in a variety of configurations. For example, as shown in Figure 21, the intermediate ring member 60 may-have an internal diameter greater than the outer diameter of the inner metal 12 and be vulcanized to only the inner periphery of the support member 16 such that an inertia track is formed between the intermediate ring member and the inner metal. Similarly, as shown in Figure 23, the intermediate ring member 60 may have an external diameter less than the internal diameter of the support member 16 and be vulcanized to only the outer periphery of the inner metal 12 such that an inertia track is formed between the support member and the intermediate ring member 60. In yet another embodiment, the inertia track may be formed within the inntermediate ring member 60 as shown in Figures 19, 20 and 22.

A conventional rubber mount response may be obtained by allowing the flexible diaphragm 32 to freely respond without application of a pressure change to the diaphragm 32. A single load bearing chamber type fluid mount response may be obtained by applying a pressure change within a first compartment 34 of only one load bearing chamber, 18 or 20, to prevent the flexible diaphragm 32 from flexing and a double load bearing chamber type fluid mount response may be obtained by applying a pressure change within both first compartments 34 of both chambers, 18 and 20, to prevent both flexible diaphragms from flexing.

The fluid mount of Figure 19 further includes a decoupler 40 which functions in a manner as previously 35. described. The decoupler 40 includes a ring shape partition plate 46 having depending legs 48 which freely float between a closed position and an open position for controlling fluid communication against the flexible diaphragm 32 thereby adjusting the volume stiffness of the load bearing chambers, 18 and 20.

A conventional rubber mount response may be obtained by not preventing the flexible diaphragm 32 from flexing, a single load bearing chamber type fluid mount response may be obtained by preventing one of the flexible diaphragms from flexing and a double load bearing chamber type fluid mount response may be obtained by preventing both of the flexible diaphragms from flexing.

During high dynamic loads associated with large amplitude vibrations the fluid pressure change in the load bearing chambers, 18 and 20, forces the partition plate 46 against'the support..ring 62 thereby blocking damping fluid 22 from flowing to the diaphragm 32 thereby increasing-the volume stiffness of the load bearing chambers, 18 and 20. Similarly, during low dynamic loads the small fluid pressure changes in the load bearing chambers, 18 and 20, does not force the partition plate 46 against the sealing surface such that damping fluid 22 flows against the diaphragm 32 allowing the diaphragm to flex and decrease the volume stiffness of the load bearing chambers.

With respect to the above description, it will be appreciated that the various elements of the invention may include variations in size, materials, shape, form, function and manner of operation, assembly and use and are deemed readily apparent once the invention is disclosed and explained to one skilled in the art. For example, as shown throughout the figures, the shape and size of the load bearing chambers, 18 and 20, cavities 28 and 30 and the air and second compartments 34 and 35 is may vary as desired to tune or adJust the fluid resonance of the mount. In addition, the first compartment 34 of the chambers, 18 and 20, may be in communication with a vacuum, pressurized gas or fluid or ambient air to selectively control the response of the. flexure of the diaphragm 32 as desired. It will be appreciated that by selectively controlling the pressure applied to the diaphragm, it is possible, for example during engine idling where high damping is needed, to draw a vacuum against the non-fluid side of the diaphragms to prevent the diaphragms from flexing. Preventing the diaphragms from flexing allows the damping fluid to flow between the two fluid-filled chambers such that the resistance to flow of the damping fluid and the fluid inertia provide an increase in volume stiffness in the fluid chambers for damping action. In addition, by reversing the direction of pressure application, the flexible diaphragms function to reduce the chamber volume stiffness by flexing during high frequency vibratory amplitudes common during normal driving operations such that the mount responds as a rubber mount. A shifting between anincrease or decrease in chamber stiffness states can be undertaken at random or automatically by means of solenoid valves or an automated system as a function of selected predetermined parameters as well known in the art.

Having described presently preferred embodiments of the invention it is to be understood that it may be otherwise embodied within the scope of the appended claims.

Claims

1. A two load bearing chamber type fluid damping mount for interconnection between a vibrating body and a base for damping vibrations from the vibrating body, the two load bearing chamber type fluid damping mount comprising a cylindrical inner metal operatively connected to the base, an elastomeric body circumscribing the inner metal, the elastomeric body including two load bearing chambers disposed therein containing a substantially incompressible damping fluid, a support member operatively connected to the vibrating body and the elastomeric body, an inertia track passage providing fluid communication between the load bearing chambers, and means for reducing the volume stiffness of at least one of the load bearing chambers such that the fluid damping mount is capable of functioning as a fluid mount at the flii!CL- resonance frequency, and functioning as a conventional rubber mount at higher frequencies.

2. A fluid damping mount as claimed in Claim 1 wherein the elastomeric body is formed of a homogeneous elastomer material.

3. A fluid damping mount as claimed in Claim 2 wherein the durometer hardness of the elastomeric body is between about - 70 Shore A.

4. A fluid damping mount as claimed in Claim 1 wherein the elastomeric body is formed of two elastomer materials to provide an elastomeric body having a dual durometer hardness.

19 5. A fluid damping mount as claimed in any preceding claim wherein the inner metal is a hollow cylindrical member and passes through a centraIaxis of the support member.

6. A fluid damping mount as claimed in Claim 5 wherein the support member is a hollow cylindrical sleeve and circumscribes the elastomeric body.

7. A fluid damping mount as claimed in either Claim 5 or Claim 6 wherein the elastomeric body include radially positioned cavities and load bearing chambers which extend -generally parallel to a longitudinal axis of the inner metal.

8.. A fluid damping mount as claimed in any preceding claim wherein the load bearing chambers are formed in a top half and ' body and project through a top a bottom half of the elastomel,.'.C edge and a bottom edge of the elastomeric body, respectively.

9. A fluid damping mount as claimed in Claim 8 wherein the means for reducing the volume stiffness of at least one of the load bearing chambers includes a flexible diaphragm attached to an inner wall of the support member to divide one or more of the load bearing chambers to define a first compartment between the diaphragm, elastomeric body and the support member and a second compartment between the diaphragm and the elastomeric body.

10. A fluid damping mount as claimed in Claim 9 wherein the first compartment includes an opening for applying a vacuum, a pressurized fluid or gas to the first compartment thereby actuating the flexible diaphragm.

11. A f luid damping mount as claimed in either Claim 9 or Claim 10 wherein the means for.reducing the volume stiffness of at least one of the load bearing chambers includes at least one decoupler mounted in the second compartment.

12. A fluid damping mount as claimed in Claim 11 wherein the decoupler includes a partition plate, an upper divider plate and a lower divider plate each having an opening therein, the upper divider plate and the lower divider plate being rigidly attached to an inner circumferential wall of the support member, the partition plate -positioned between the upper and lower divider plates for controlling the flow of damping fluid against the flexible diaphragm such that during periods of high amplitude vibrations, the partition plate compensates for the elastomeric body displacement and variation in the volume of the load bearing chambers by moving against the opening in said upper divider plate such that there is substantially no transfer of liquid beyond the upper divider plate to the diaphragm and during periods of low amplitude vibrations a variation in volume of the load bearing chambers is insufficient to force the partition plate against the opening in the upper divider plate.

21 14. A fluid damping mount as claimed in any one of Claims 1 to 5 wherein the support member is a cylindrical collar having a radially outwardly projecting flange extending through said elastomeric body sides.

is. A fluid damping mount as claimed in Claim 14 wherein the elastomeric body. has secured to each end thereof an upper cap element and a lower cap element having a central bore through which the inner metal extends.

1 i:- I;T, 16. A fluid dampin. g mount as claimed in Claim 15 wherein a flexible diaphragm is mounted within a portion of the upper and lower cap elements and divides the chambers into a first compartment and a second compartment.

17.. A fliji.c'...damping mount as claimed in Claim 16 wherein the means for reducing the volume stiffness of at least one of the load bearing chambers includes at least one decoupler mounted in the second compartment, the decoupler including a partition plate which freely floats between a closed position and an open position for controlling fluid communication against the flexible diaphragm thereby adjusting the volume stiffness of the load bearing chambers.

18. A fluid damping mount as claimed in any one of Claims 1 to 5 wherein the support member is of an annular cylinder positioned concentric with said inner metal.

22 19. A fluid damping mount as claimed in Claim 18 wherein the elastomeric body includes an upper cap element, a lower cap element and an intermediate member, the upper and lower cap elements positioned between the inner metal and the support member at opposing ends thereof to form a fluid tight seal between the inner metal and the support member, the intermediate member positioned hetween the upper and lower cap elements to define the load bearing chambers.

20. A fluid damping mount as claimed in Claim 19 wherein the means for reducing the volume stiffness of at least 6ne of the load bearing chambers includes a flexible diaphragm secured across the chambers to divide the load bearing chambers and provide a first compartment and a second compartment, the diaphragms retained in position by support rings which fxi:.tionally engage the inner metal and the support member.

21. A fluid damping mount as claimed in either Claim 19 or Claim 20 wherein the inertia track is formed between the intermediate member and the inner metal.

22. A fluid damping mount as claimed in either Claim 19 or Claim 20 wherein the inertia track is formed between the support member and the intermediate member.

23. A fluid damping mount as claimed in either Claim 19 or Claim 20 wherein the inertia track is formed within said intermediate member.

23 24. A fluid damping mount as claimed in any one of Claims 20 to 23 further including a decoupler having a ring shape partition plate which freely floats between a closed position and an open position for controlling fluid communication against the flexible diaphragm to adjust the volume stiffness of the load bearing chambers.

25. A fluid damping mount substantially as hereinbefore described and illustrated in the accompanying drawings.

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