GB1583963A

GB1583963A - Vibration absorbing mountings for machines

Info

Publication number: GB1583963A
Application number: GB17279/77A
Authority: GB
Original assignee: Boge GmbH
Current assignee: ZF Boge GmbH
Priority date: 1976-04-27
Filing date: 1977-04-26
Publication date: 1981-02-04
Also published as: SE7704780L; AR212993A1; DD129760A5; AU501777B2; IT1125741B; CA1053642A; GB1583964A; NL167017C; SU843718A3; MX4249E; BR7702629A; AU2457077A; NL7704545A; GB1583965A

Description

(54) VIBRATION ABSORBING MOUNTINGS FOR MACHINES (71) We, BOGE GmbH, a German Company of 5208 Eitorf, Western Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a resilient coupling for resiliently connecting two components movable relative to each other in particular, though not exclusively, to a coupling which is suitable for mounting a motor vehicle engine.

In engine couplings having resilient side walls the spring characteristics of the engine suspension can be set in an optimum manner by appropriate design of the coupling and choice of the quality of rubber and at the same time the damping provided by the hysteresis of the rubber walls can be added to hydraulic damping by appropriate design so that also for the oscillation damping of the engine suspension the relationships are an optimum. It is also possible to fulfil the requirement of motor vehicle construction that the low-frequency large-amplitude oscillations of the engine are heavily damped and the high frequency vibrations of small amplitude, for example 0.1 mm, of the engine are transmitted, as far as possible, undamped.

A hollow liquid spring with built-in damping is known. The spring having a main chamber and an expansion chamber which are filled with a liquid medium and are connected together through openings in an intermediate wall that serves as a mounting bracket, the main chamber comprising a hollow spring body of resilient rubber material and the expansion chamber being defined by a rubber diaphragm. In this known arrangement the expansion chamber has the sole function of accepting fluid forced out of the main chamber and of returning it to the main chamber, the resilient deformation of the diaphragm assisting in the springing action only to a minimal extent. A drawback in this known arrangement is that the space taken by the expansion chamber is not available for the main function of the coupling, namely the springing function.

According to the present invention we provide a resilient coupling for resiliently connecting two components movable relative to each other, the coupling being in the form of a hollow body which in use of the coupling contains a hydraulic damping fluid, and the interior of the body being divided into main and auxiliary chambers between which a restricted flow of fluid can take place upon relative movement between said two components, the coupling comprising first mounting means to which one of the components can be secured and which cdm- prises two end portions of the hollow body which are spaced apart and fixed relative to each other, second mounting means to which the other of the components can be secured and which is of an annular form and is positioned generally between said two end portions, and resilient wall means which connects said first and second mounting means and comprises resilient annular wall portions which connect said second mounting means with said end portions, at least one of said end portions engaging the associated annular wall portion over a frusto-conical surface. Preferably at least one of the annular wall portions engages each of the associated end portion and the second mounting means over a frusto-conical surface.

In the coupling according to the present invention the space of the auxiliary chamber is employed not only for the damping function, by accepting and returning the fluid forced out of the main chamber, but also for the springing function.

Partition means between the main and auxiliary chambers may comprise a rigid dividing wall or a resilient dividing wall. In one preferred arrangement the dividing wall comprises a sheet metal component, the resilient wall portions comprise two rubber rings, and the second mounting means comprises a pair of sheet metal components defining a mounting bracket with the rigid dividing wall clamped between the com ponents. One ring is adhesively bonded to one end portion, in the form of a plate, and to one of the sheet metal components and the other ring is adhesively bonded to the other end portion, also in the form of a plate, and to the other of the sheet metal components. Conveniently each ring and its associated metal component are formed as individual rubber and metal components.

Each ring can be adhesively bonded to an outer frusto-conical surface of the associated end plate and to an inner frdsto-conical surface of the associated sheet metal component.

A resilient dividing wall and the resilient wall means can be formed as an integral component of generally H- section (as seen in axial cross-section), the centre portion defining the dividing wall between the resilient annular wall portions. The second mounting means may comprise an annular mounting bracket embedded in, and adhesively bonded to, the central portion of the component. Each annular wall portion may be bonded to an inner frusto-conical surface of an end plate, or of a component secured to the end plate, of the associated end portion of the coupling.

Preferably the end portions of the coupling are spaced apart by means of a spacer sleeve extending through an aperture in the dividing wall and are fixed relative to each other by a bolt extending through the sleeve.

Fluid control means may conveniently comprise an annular gap defining a throttling restriction between the surface bounding the aperture and the outer surface of the sleeve.

The degree of throttling can be matched to requirements by altering the diameter of the spacer sleeve.

The rigid connection of the end portions makes the axial spring movements of the end portions with respect to the second mounting means equal to one another. The variations in volume in the main and the auxiliary chambers caused by a predetermined spring travel with the fluid pressure balanced in the main chamber and the auxiliary chamber can be made equal to one another or different from one another by appropriate shaping of the peripheral wails and, if necessary, of the resilient dividing wall. When the reduction in the volume of the main chamber is greater than the increase in volume of the auxiliary chamber the balanced fluid pressure rises, with corresponding outward distension of the peripheral walls. When the increase in volume of the main chamber is greater than the decrease in volume of the auxiliary chamber the balanced fluid pressure falls, with a corresponding inward contraction of the peripheral walls, so that a vacuum can arise and cavities can be formed. Such cavities, or those that are produced deliberately, for example by incomplete filling, may serve to damp, in an engine mounting, the low frequency large-amplitude oscillations, whilst high frequency vibrations of small amplitude can be transmitted without exchange of fluid between the main and auxiliary chambers and thereby without fluid damping. The same aim can be fulfilled also be making the dividing wall slightly movable, the travel of which is correspondingly strictly limited. Alternatively inside the body cavities can be provided, closed off from the liquid by a diaphragm, these cavities being either filled with fluid at a higher or lower pressure than the surroundings or being vented to atmosphere. The chambers are filled with fluid at an elevated pressure in order to give the peripheral walls an outward bulge right from the start and avoid a vacuum arising, when such a thing is considered undesirable, There is described and claimed in copending Patent Application No. 7939913 (Serial No. 1,583,964) divided from the present Application, a resilient coupling for resiliently connecting two components movable relative to each other, the coupling being in the form of a hollow body which in use of the coupling contains a hydraulic damping fluid, and the interior of the body being divided into main and auxiliary chambers between which a restricted flow of fluid can take place upon relative movement between said two components, the coupling comprising first mounting means to which one of the components can be secured and which comprises two end portions of the hollow body which are spaced apart and fixed relative to each other, second mounting means to which the other of the components can be secured and which is of an annular form and is positioned generally between said two end portions, and resilierit wall means which connects said first and second mounting means and comprises resilient annular wall portions which connect said second mounting means with said end portions, at least one of said end portions comprising resilient pressure-absorbing means whereby the coupling can accommodate vibrations of relatively small amplitude without hydraulic damping.

There- is described and claimed in cow pending Patent Application No. 7944377 (Serial No. 1,583,965) divided from the present Application, a resilient coupling for resiliently connecting two components mov-- àblè relative to each other, the coupling being in the form of a hollow body which in use of the- coupling contains a hydraulic damping fluid, and the interior of the body being divided by partition means of the coupling into main and auxiliary chambers between which a restricted flow of fluid can take place upon relative movement between said two components, the coupling corn prising first mounting means to which one of the components can be secured and which comprises two end portions of the hollow body which are spaced apart and fixed rela- tive to each other, second mounting means to which the other of the components can be secured and which is of an annular form and is positioned generally between said two end portions, and resilient wall - means which connects said first and second mount ing means and comprises resilient annular wall portions which connect said second mounting means with said end portions, said partition means comprising a movable portion arranged to move to accommodate small variations in the volumes of the main and auxiliary chambers so that the coupling can accommodate vibrations of small ampli tude without hydraulic damping.

Some embodiments of couplings accord ing to the invention are illustrated, by way of example only, in the accompanying draw ings wherein: Figure 1 shows a coupling having a rigid dividing wall, Figure 2 shows a coupling having a resilient dividing wall, Figure 3 shows a coupling having a resilient dividing wall which is integral with the resilient annular wall portions, Figure 4 shows the vulcanised rubber and metal component of the coupling shown in Figure 3 before assembly, Figure 5 shows a coupling provided with bodies made of resilient material for absorb ing oscillations of high frequency without fluid damping, Figure 6 shows a modification to the coupling shown in Figure 5, Figure 7 shows a modification to the coupling shown in Figure 6 Figure 8 shows a modification to the coupling shown in Figure 5 Figure 9 is a plan view of the coupling shown in Figure 8, Figure 10 shows a modification to the coupling shown in Figure 5, Figure 11 shows a modification to the coupling shown in Figure 10, and Figure 12 shows a modification to the coupling shown in Figure 10.

Referring to the accompanying drawings, each of the resilient couplings illustrated is suitable for mounting an engine (not -shown) to an engine carrying sub-frame. In general each coupling comprises a hollow body 1 defined by end portions, comprising end plates 2, 3, provided by first mounting means which is adapted to be connected to the engine, and by resilient wall means 4.

The end portions of the body are spaced apart and fixed relative to each other. Each coupling further includes partition means 5 dividing the body into a main fluid chamber 6 and an auxiliary fluid chamber 7, fluid control means fOr controlling å restricted flow of fluid between the chambers, and second mounting means 9 (positioned generally between- the two end portions of the body 1) adapted to be connected to the engine carrying sub-frame and being connected lo the first mounting means by the wall means 4. The main fluid chamber 6 and auxiliary fluid chamber 7 are filled with damping liquid which is preferably made of 50% water and 50% glycol.

Referring now to the coupling shown iti Figure 1, the end plates 2, 3 are spaced apart by means of a rigid spacer sleeve 10 and are fixed relative to each other by means of a bolt 11 and a nut 12 as shown.

The resilient wall means 4 comprises resilient annular wall portions in the form of a pair of annular rubber rings 13, 14 which connect the mounting means 9 with the end portions of the body 1. The ring 13 is adhesively bonded at its inner periphery 16 to a convex frusto-conical outer surface 15 of the end plate 2 and at its outer periphery 17 to a concave frusto-conical inner surface 18 of å flange 19 of the mounting means 9. The ring 14 is adhesively - bonded at its inner periphery 20 to a convex frusto-conical sur face 21 of the end plate 3 and at its outer periphery 22 to a concave frusto-conical surface 23 of a flange 24 of the mounting means 9. The flanges 19, 24 are formed as pressings out of sheet metal components 25, 26 which togther define an annular mount-- ing bracket 27 of the mounting means 9.

The partition means 5 comprises á rigid dividing wall 28 formed from sheet metal which is clamped between the components 25, 26 by bolts 29 securing the components together. The dividing wall 28 is formed with an aperture through which the sleeve 10 extends. The diameter of the aperture is slightly greater than the diameter of the sleeve 10 so that an annular gap 30 is formed between the dividing Wall 28- and the sleeve 10. The annular gap provides the fluid control means 8 for controlling the flow of fluid between the main chamber 6 and auxiliary chamber 7. In one method of construction the coupling is assembled under the liquid surface of a c-ontainer filled wfth the damping liquid.

The assembled coupling provides a resili- ent mounting for a vehicle engine (not shown). The end plate 2 is cOnnected to the engine crankcase 31 by means of the bolt 11 and a nut 32 as shown and the mounting bracket 27 is connected to an engine carrying sub-frame 33 by means of bolts 34.

In use when the crankcase 31 oscillates in the direction of the axis of the bolt 11, i.e.

towards or away from the mounting bracket 27, variable dynamic engine mounting forces are produced dependent on the frequency and amplitude of the oscillations.

The oscillations cause resilient deformation of the rings 13, 14, which results in the volumes of the main chamber 6 and the auxiliary chamber 7 undergoing variations forcing corresponding quantities of liquid through the gap 30 to produce hydraulic damping forces which absorb the dynamic engine mounting forces.

In addition to the gap 30 the dividing wall may also be provided with an aperture 35 for further controlling the flow of fluid between the chambers A valve (not shown), preferably of the type known in wheel suspension shock absorbers and dependent on the stroke and frequency, may also be provided.

It will be appreciated that the behaviour of the damping force can be controlled by selecting the required size of the gap 30 and where necessary, by providing other suitable means (such as the valve referred to).

Referring now to the coupling shown in Figure 2 the end plates 2, 3 are spaced apart by means of a rigid spacer sleeve 40 and are fixed relative to each other by means of a bolt 41 and a nut 42 as shown. The resilient wall means 4 comprises a pair of annular rubber rings 43, 44. The ring 43 is adhesively bonded at its outer edge to a concave frusto-conical surface 45 of a metal ring 46 and at its inner edge to a convex frustoconical surface 47 of a flange 48. The flange 48 is pressed out of a sheet metal component forming a mounting bracket 49 comprising the mounting means 9. The ring 44 is adhesively bonded at its outer edge to a concave frusto-conical surface 50 of a metal ring 51 and at its inner edge to a convex frusto-conical surface 52 of a flange 53 formed by pressing from a sheet metal component 54. The component 54 is welded to the bracket 49. The rings 46, 51 are sealingly connected to the end plates 2, 3 respectively by rolling the inner edges of the rings over the periphery of the associated end plate.

The partition means comprises a resilient rubber dividing wall 55 integral with the ring 43. The dividing wall 55 is formed with an axially extending bore through which the sleeve 40 extends. The wall 55 is adhesively bonded at its outer surface to a concave frusto-conical surface 56 of the flange 48 and at its inner surface to the - sleeve 40.

Although the ring 43 and dividing wall 55 are formed integrally they may, if desired be formed as separate components.

The bolt is formed with two portions of reduced cross-section defining a pair of lands 57, 58 and the portion of the bolt intermediate the lands is formed with a longitudinally extending channel 59 providing a fluid connection between the lands.

The sleeve 40 is formed with a pair of openings 60, 61. The opening 60 provides a fluid connection between the main chamber 6 and the land 57 and the opening 61 provides a fluid connection between the land 58 and the auxiliary chamber 7. The lands 57, 58, channel 59 and the openings 60, 61 form the fluid control means for controlling the flow of fluid between the chambers. The bolt 41 is further provided with an axially extending bore 62 providing a filling opening for introducing the damping liquid into the coupling. The bore is closed by a pressed in ball 63 after filling. The coupling can be filled with fluid at a pressure which is higher or lower than that of the surroundings. A closable air vent (not shown) can be provided at a suitable point to facilitate the filling of the coupling with the damping liquid. The end plate 2 is formed with an annular recess 64 which is closed by a resilient diaphragm 65 to form a cavity 66 sealed relative to the main fluid chamber 6. The cavity 66 can be filled with fluid, preferably a gas, and, as will be described in more detail later, allows oscillations of small amplitude to be absorbed without hydraulic damping. The coupling can be used for mounting an engine in similar manner to the coupling described with reference to Figure 1.

In use when the crankcase of the engine oscillates in the direction of the axis of the bolt 41, i.e. towards or away from the mounting bracket 49, variable dynamic engine mounting forces are produced, dependent on the frequency and amplitude of the oscillations.

These oscillations cause resilient deformation of the rings 43, 44 causing the volumes of the fluid chambers to undergo variations.

For oscillations of high frequency and low amplitude, the changes in volume are small and are accommodated by resilient deformation of the diaphragm 65 against the fluid pressure in the cavity 66. Thus dynamic engine mounting forces produced by oscillations of high frequency and low amplitude are absorbed without hydraulic damping.

The deformation of the diaphragm 65 is controlled by the fluid pressure in the cavity 66. As the amplitude of the oscillations increases the deformation of the diaphragm increases until the fluid pressure in the cavity 66 prevents any further deformation of the diaphragm occurring and the diaphragm acts as a rigid wall. For oscil låtions of higher amplitude the changes in volume result in fluid being forced through the openings 60, 61 connecting the chambers to produce hydraulic damping forces which absorb the dynamic engine mounting forces.

It will be appreciated that by appropriate selection of the pressure of the fluid in the cavity 66 the range of oscillations which the coupling can absorb without hydraulic damping - occurring can be set as desired.

Preferably the fluid pressure in the cavity 66 is chosen so that only oscillations of high frequency and - low amplitude are absorbed without hydraulic damping. It will be further appreciated that the shape and dimensions of the lands 57, 58 and channel 59 control the behaviour of hydraulic damping forces and the latter can be controlled by selecting the required dimensions of - the lands 57, 58 and channel 59.

Referring now to the coupling shown in Figure 3, the end plates 2, 3 are spaced apart by means of a rigid spacer sleeve 70 and are fixed relative to each other by means of a bolt 71 and a nut 72. The resilient wall means 4 and the partition means 5 are provided by a single body 73, of a resilient rubber material, which in its uncompressed state has the shape shown in Figure 4. The outer peripheral portion of one end of the component is adhesively bonded to an inner frusto-conical surface 75 of a metal ring 76 and the outer peripheral portion 77 of the other end is adhesively bonded to an inner surface 78 of a metal ring 79. A frustoconical flange 80 formed by pressing from a sheet metal component 81 is embedded in and adhesively bonded to the central portion of the rubber component 73. The sheet metal component 81 forms a mounting bracket 82 comprising the mounting means 9. The rings 76, 79 are sealingly connected to the end plates 2, 3 respectively by rolling the inner edges of the rings over the periphery of the associated end plate. The central portion of the rubber component fprms the partition means 5 and is formed with an axially extending through bore 83 through which the sleeve 70 extends. A rigid sleeve 84 is located in the bore 83. The inner diameter of the sleeve 84 is greater than the outer diameter of the sleeve 70 so that an annular gap 85 is formed between the sleeves. The gap 85 provides the fluid control means for controlling the flow of fluid between the main chamber 6 and the auxiliary chamber 7.

The axial length b of the assembled coupling is less than the axial length a of the component 73 so that in the assembled coupling the end portions of the component, which are connected to the end plates, are compressed having mutually oppositely directed pre-loadings. The magnitude of these pre-loadings is determined by the length of the spacer sleeve 70 and can be made to match requirements whereby the overall spring characteristics of the assembled coupling can be set in the favourable range of the individual characteristics, known to be non-linear, of the end pdrtions of the component 73.

The coupling can be used for mounting an enginge in similar manner to the coupling -shown in Figure 1. When the engine is mounted the weight of the engine causes -resilient deformation of the component 73, reducing the distance of the end plate 2 from the bracket 82. From this theoretical static rest position the coupling- has freedom of movement in the direction of the axis of the bolt 71 between two extreme positions.

In one extreme position a rubber collar 86 on the component 73 engages the end plate 2 and in the other extreme position a rubber collar 87 on the component 73 engages the end plate 3, this other extreme position being shown in Figure 3. The outer edge of the flange 80 is arranged to provide local stiffening for the collar 86 so that a relatively hard engagement is obtained between the collar and the end plate 2 in the one extreme position. On the other hand tte collar 87 is not locally stiffened so that a relatively soft engagement is obtained between the collar and the end plate 3 in the other extreme position and the end portion of the component 73 which is attached to the end plate 3 therefore acts as a compression spring in this direction of movement or engagement.

In use the dynamic engine mounting forces produced by all engine oscillations in the direction of the axis of the bolt 71 are absorbed by hydraulic damping forces as a result of fluid being forced through the gap 85 to accommodate changes in volume of the main and the auxiliary chambers.

Each of the above described couplings as well as allowing oscillations in the direction of the respective bolt connecting the end plates together also allow limited transverse movements and act as a resilient spring in respect of them. In the coupling shown in Figure 1 transverse movements are limited by contact between the spacer sleeve 10 and the rigid dividing wall 28. The magnitude of the transverse movement is therefore determined by the width of the gap 30.

Both the spacer sleeve and the rigid dividing wall are metallic so that the contact between them generates undesirable noise. This problem is overcome in the coupling shown in Figure 2 where transverse movements are Imiited by the resilience of the rubber dividing wàll 55, there being no contact between two metallic components as in the coupling shown in Figure 1. In the coupling shown in Figure 3 transverse movements are limited by the resilient engagement of the spacer sleeve 70 with the spacer sleeve 84 mounted in the rubber dividing wall. Both sleeves are metallic and in order to reduce undesirable noise produced by contact between the components a skin or rubber is applied by a vulcanisation process to the inner surface of the sleeve 84. As a further improvement on the couplings shown in Figures 1 and 2 the end portions of the component 73 are formed with pockets 88 which allow the springing to have a different characteristic according to the -direction of -the transverse movement.

Figure 5 shows a coupling similar to the coupling shown in Figure 3 but incorporating some important modifications. Like reference numerals have been used to indicate similar componets. The central portion of the integral rubber component 73 which forms the partition means includes an aperture defined by an annular collar 90 extending towards the auxiliary chamber 7. The sleeve 70 extends through the collar 90 which is of greater diameter than the sleeve 70 so that the gap 85 is formed. The end portion of the collar 90 is reinforced by an angled metal insert 91. The collar 90 replaces the sleeve 84 of the embodiment shown in Figure 3 and, as will be described in more detail later allows improved transverse movement of the coupling. A pair of disc shaped bodies 92 made of resilient material e.g. foam plastics material are arranged in the chambers, one being attached to the inner surface of the end plate 2 the other being attached to the inner surface of the end plate 3.

The coupling provides a resilient mounting for a vehicle engine (not shown). The end plate 2 is connected to the engine crankcase 93 by means of the bolt 71 and a nut 94 as shown and the mounting bracket 82 is connected to an engine carrying subframe (not shown).

In use engine oscillations in the direction of the axis of the bolt 71 produce variable dynamic engine mounting forces dependent on the frequency and amplitude of the oscillations.

These oscillations cause resilient deformation of the component 73 causing the volumes of the fluid chambers to undergo variations. For oscillations of high frequency and low amplitude, the changes in volume are small and are accommodated by resilient deformation of the bodies 92. Thus the dynamic engine mounting forces produced by oscillations of high frequency and low amplitude are absorbed without hydraulic damping. The deformation of the bodies 92 is dependent on the resilience of- the material comprising the bodies. As the amplitude of the oscillations increases the deformation of the bodies 92 increases until it reaches-a maximum at which the bodies act as rigid bodies. For oscillations of higher amplitude the changes in volume result i correspond to the mean position of the coupling, in the direction towards the mounting bracket 82. For a small displacement the reduction in volume in the main chamber which arises is balanced out by the deformation of the diaphragm towards the end plate 2. The resulting simultaneous increase in volume of the auxiliary chamber is balanced out by the deformation of the diaphragm away from the end plate 3 so that a vacuum, with a consequent undesired cavitation in the side walls of the auxiliary chamber, does not occur. The displacement therefore results in little or no fluid being displaced between the chambers.- As the displacement increases the deformation of the diaphragms increases until the bead 109 engages the end plate 2. The diaphragm in the main chamber, unable to deform any further, acts as a rigid wall. For a higher displacement, the fluid pressure in the main chamber rapidly builds up resulting in flow of fluid through the annular gap 85 into the auxiliary chamber. The spatial arrangements are arranged so that in the end position of the diaphragms a gap remains between the disc 106 and the associated end plate, this gap being vented to atmosphere through the openings 103, the diaphragms being held by suction against the end plates.

The coupling can be used to mount an engine and in use dynamic engine mounting forces produced by engine oscillations of high frequency and small amplitude are absorbed without hydraulic damping. The corresponding inward and outward movements of the diaphragms being sufficient to accommodate small changes in volume without any significant increase in pressure in the chambers.

Dynamic engine mounting forces produced by oscillations of low frequency and high amplitude are hydraulically damped when the diaphragms reach their end positions by liquid forced through the gap 85 to accommodate the larger changes in volume of the chambers. Transverse movements are accommodated in similar manner to the coupling described with reference to Figure 5.

Figure 7 shows a modification to the coupling shown in Figure 6. Like reference numerals are used for similar components.

In this embodiment the end plates are spaced relative to each other by means of U-shaped retaining components (not shown), the limbs of which are fixed to the end plates in a suitable manner. The retaining components could be provided as parts of the crankcase of an engine. A bolt 120 connects the end plate 2 to the engine crankcase (not shown) and the diaphragms,-one only of which is shown, are of slightly modified construction. The diaphragm comprises an annular metal disc 121 having a peripheral rubber ring 122 around it. The ring 122 is clamped between the metal ring 76 and the end plate 2. Axial movement of the diaphragm towards the end plate 2 is limited by the resilient engagement of the ring 122 with the end plate. Resistance to movement of the diaphragm towards the end plate can be further increased by the provision of resilient rubber protuberances, one only of which is indicated by reference numeral -123, fixed-to the metal disc 121. The other diaphragm is of similar construction. Operation of this coupling is similar to the operation of the coupling described with reference to Figure 6.

In a modification the cavities 102 in the embodiments of Figures 6 and 7 could be filled with a fluid, e.g. a gas, at a higher or lower pressure than the surroundings in similar manner to the cavity described in the embodiment of Figure 2. However, when the cavities are filled with a gas at high pressure the gas may diffuse through the diaphragms so that the pressure in the cavities is reduced. The resistance of the cavities to inward displacement of the diaphragms is correspondingly reduced to an undefined value which detrimentally affects the hydraulic damping forces. For this reason it is preferred to vent the cavities to atmosphere as described so that a constant defined pressure is obtained in the cavities.

Figures 8 and 9 show a coupling similar to the coupling shown in Figure 5 but incorporating some modifications. Like reference numerals have been used for similar parts.

The end plates 2, 3 are spaced apart by means of a through bolt 130 having shoulders 131, 132. The end plate 2 engages the shoulder 131 and is secured in position by a disc-shaped member 133. The end plate 3 engages the shoulder 132 and is secured in position by a nut 134.

As best shown in Figure 9 the end plate 2 is provided with four, uniformly spaced apertures 135 of generally triangular shape.

As shown in Figure 8 the end plate 2 is covered on both sides with a resilient material, for example rubber, whereby each aperture 135 is closed by an associated resilient diaphragm 136. The end plate 3 is provided with a number of openings 138 which are closed by a diaphragm 139 made of foamed plastics material, for example a polyurethane foam, arranged on the inner surface of the end plate. The diaphragm 139 may be adhesively bonded to the inner surface of the end plate 3 or may be secured at its peripheral portions only so that the major portion freely engages the end plate 3. There is a danger that with a foamed plastics diaphragm comprising a number of individual cells there may be an exchange of damping fluid or gas between the diaphragm and the auxiliary chamber thereby altering the operating conditions of the coupling. In addition there is a possibility that for large pressures in the auxiliary chamber the diaphragm may be forced through the openings in the end plate. Both these possibilities are undesirable and therefore it is preferred to strengthen the diaphragm by providing a thin layer of metal foil or plastics material on the inner surface of the diaphragm as, indicated in the right hand side of Figure 8 by reference numeral 139n The coupling provides a resilient mounting for a vehicle engine (not shown). The end plate 2 is connected to ,the engine crankcase 140 by means of the bolt 130 and a nut 141 and the mounting bracket 82 is connected to an engine carrying sub-frame 142 by means of bolts 143.

The coupling shown in Figure 8 is in its rest position, ready ,for operation. which corresponds to a dynamic rest position of the coupling in which the diaphragms 136 and and diapragm 139 are substantially flat.

In use, assuming engine oscillations in the direction of the axis of the bolt 130, oscillations of high frequency and low amplitude produce small changes in the volumes of the fluid chambers 6, 7 and the dynamic engine mounting forces are absorbed by resilient deformation 6f the diaphragms 136 and of the diaphragm 139 without any displacement of fluid occuring i.e. without hydraulic damping. As the amplitude of the oscillations increases the deformation of the diaphragms increases, the diaphragms 136 assuming a curved shaped, and the resistance to deformation progressively increases in corresponding manner until no further deformation can occur and the diaphragms act as rigid bodies. For outward movement of the diaphragms 136 this position is determined by engagement of the diaphragms with the member 133 which acts as a stop to limit outward movement, for example to 1 mm. Inward movement of the diaphragms 136 is smaller and may for example be 0.2 mm. For oscillations of larger amplitude, with the diaphragms acting as rigid bodies, the dynamic engine mounting forces are absorbed by hydraulic damping, liquid being forced through the gap 85 to accommodate changes in volume of the chambers. Transverse movements are accommodated in similar manner to the coupling described with reference to Figure 5.

Although the member 133 acts as a stop to limit outward movement of the diaphragms 136 this may not be necessary when the diaphragms are made from a resilient material having a deformationresistance sufficient to prevent outward movement beyond a predetermined distance irrespective of the pressure differences that may arise in the chambers.

As shown the side wall 144 which is connected to the end plate 2 is made thicker than the side wall 145 which is connected to the end plate 3. The side wall 144 determines substantially the resilient supporting capacity of the coupling. The side wall 145 has a flat, diaphragm-like, annular flange portion 146 which provides a compensation or balance of volume, when, on a predetermined axial displacement of the end plates 2, 3, the changes in volume produced in the main chamber 6 and the. auxiliary chamber 7 are disfferent from one another. This avoids the possibility that a sub-atmospheric pressure could arise in one of the chambers 6 or 7, with the formation of cavities in the liquid, giving rise to noise. The same result may be obtained by making the side wall 144 stronger than the side wall 145.

Furthermore, while both the end plates described have been provided with resilient diaphragms, in order to be able to compensate for the changes in volume in both chambers during oscillations of small amplitude and high frequency, when the side wall connected to the end plate 2 determines substantially the resilient load-carrying capacity of the coupling and the side wall connected to the end plate 3 is made to yield in such a manner that it can on its own accord absorb by corresponding deformation the volumes disp]aced at small amplitudes and high frequencies, it is sufficient to provide resilient diaphragms only on the end plate 2. It may be preferable to provide resilient diaphragms on one end plate only for other reasons, for example especially when in an engine mounting additional measures of a different kind are provided to restrict hydraulic damping of high frequency, low amplitude oscillations.

Figure 10 shows a coupling similar to the coupling shown in Figure 5 but with some important modifications. Like reference numerals have been used for similar parts.

The end plates 2, 3 are spaced apart by means of a through bolt 150 having shoulders 151, 152. The end plate 2 engages the shoulder 151 and is secured in position by a disc-shaped element 153. The end plate 3 engages the shoulder 152 and is secured in position by a nut 154. The partition means 5 is formed with an annular shoulder 155 which together with an annular disc-shaped insert 157 definies a channel-shaped groove 158. The fluid control means 8 comprises a resilient body 159 having the shape shown and made for example from rubber, is located in the groove 158 and has an aperture 160 through which the bolt 150 extends. The body 159 comprises an - annular rubber ring 159a with an intermediate wall 159b of reduced thickness. The body 159 can move axially relative to the bolt 150 between two extreme positions, in one of which the body engages the shoulder 155, in the other of which the body engages the insert 157. An annular gap 161 is defined between the outer peripheral surface of the body 159 and the groove 158 and an annular gap defining a throttling restriction 162 is defined between the outer surface of the bolt 150 and the peripheral portion 163 of the body defining the aperture 160.

The portion 163 has an arcuate axial pro file, of which the bight 164 lies at the centre of the aperture 160. The intermediate wall 159b is relatively easily deformable.

The main chamber 6 and the auxiliary chamber 7 are filled with hydraulic fluid and communicate with one another through the throttling restriction 162. In the position of the body 159 illustrated there is a further communication between the chambers through the gap 161.

The displacement surface area of the body 159, effective in the axial direction, multiplied by the total distance which the body can move in either direction, equi valent to (x - + y), determines a maximum volume displacement of the body 159. In - the event of very small amplitude oscil lations of the end plates 2 and 3 with respect to the mounting bracket 82 in an axial direction, in which the changes in volume in the chambers 6 and 7 does not exceed the displacement volume of the body 159, the body 159 oscillates back and forth between the shoulder 155 and the insert 157 and no exchange of fluid takes place between the chambers i.e. there is no hydraulic damping of the oscillations of the engine mounting. On larger amplitudes of o,cil- lation with changes in volume in the cham bers which exceed the displacement volume of the body 159, fluid is forced through the throttling restriction 162 according to the prevailing engagement, determined by flow, of the body 159 against the shoulder 155 or the insert 157. The quantity of fluid flowing through the throttling restriction 162 is the greater, is the oscillatory travel re maining after the body 159 hash engaged the shoulder 155 or the insert 157, and a pressure difference is produced between the chambers 6 and 7 through the resistance of the throttling restriction 162, the velocity of flow for a given quantity being deter mined by the cross section of the restriction 162 and the flow factor of the restriction 162, itself determined by the profile of the portion 163.

In the position of the body 159 illustrated, the portion 163 produces a nozzle-shaped inlet for flow and a nozzle-shaped outlet.

When the wall 159b of the body 159 is deflected by a correspondingly large pressure difference between the chambers 6 and 7 both the cross section for flow and above all also the flow factor of the restriction 162 changes in that the inlet no longer remains nozzle-shaped but is formed by a sharp edge. As compared with a fixed profile for the portion 163, this results in a sharp rise of the resistance to flow of the restriction 162. By appropriate shaping of the portion 163 one can also achieve the result that the resistance to flow increases more slowly, especially when, with increasing deflection of the wall 159b, a cross section of the restriction 162 increases in a decisive manner. The flow relationship of the arrangement shown can be influenced by an additional control function of the body 159, for example, by the provision of openings in the insert 157 which remain open allowing flow of fluid through the gap 161 when the body 159 engages the insert 157. The resistance to flow can furthermore be made of different magnitudes according to the direction of flow; in the present case the resistance would be smaller on the flow out of the main chamber 6 into the auxiliary chamber 7 than when the main chamber 6 is being filled from the auxiliary chamber 7.

Figure 11 shows a coupling similar to the coupling shown in Figure 10 but incorporating some important modifications. Like reference numerals are used for similar parts.

The end plates 2, 3 are spaced apart by means of a U-shaped component 140. An externallly screw-threaded projection 171 on each end plate is secured to a respective one arm of the component 170 by means of an associated nut 172 as shown. The component 170 can be connected to an engine crankcase (not shown) by any suitable means (not shown) or could itself form part of the engine crankcase.

The partition means 5 is formed with an annular, inwardly directed collar 173. The fluid control means 8 comprises a body 174 comprising an outer metal ring 175 and an intermediate resilient wall 176. The end portions of the ring 175 are bent outwards to form flanges 177, 178 defining an outwardly directed, substantially channelshaped groove 179.

The collar 173 extends into the groove 179 and axial movement of the body 174 is limited by engagement of the flanges 177, 178 with the upper and lower portions 173a, 173b respectively of the collar 173.

The wall 176, made for example from rubber, has a throttling restriction 180 of which the upper peripheral portion adiacent to the main chamber 6 is formed with a sharp edge 181 while the lower peripheral portion adjacent to the auxiliary chamber 7 is formed with a rounded edge 182 so that the throttling restriction 180 has different flow factors in the two directions of flow. The operation of this coupling corre sponds to the operation of the coupling shown in Figure 10.

Figure -12 shows yet another version of fluid control means 8 which may be used in place of the fluid control means of the coupling shown in Figure 10. The fluid control means 8 comprises a body 190 having the shape shown which is formed integrally with the component 73. The body 190 has an aperture through which the bolt 150 extends to define the throttling restriction 162. The body 190 is connected to the component 73 by a relatively thin annular flange 191 which offers only slight resistance to axial movements of the body 190 so that for small axial movements the operation of the body corresponds to that of the body described with reference to Figure 10.

For large movements the resistance of the flange to deformation is substantially increased so that the movement of the body can be considered to be restricted within predetermined allowable limits.

Preferably, in each of the versions of Figures 10 to 12, the displacement volume of the body corresponds to a change in volume in the chambers produced by an overall oscillatory travel of the coupling of 0.2 to 0.3 m.m.

The invention is not limited to the particular arrangement of the end plates, chosen in the description, i.e. one end plate connected to the crankcase of the - engine and the mounting bracket connected to the engine supporting frame. The arrangement can equally well be different, as desired.

The main and auxiliary chambers could be made as mirror images without departing from the scope of the invention.

The coupling can also find use in couplings between rotating power sources and power-using machines, in that several couplings distributed around the components transmit the tangential forces and hydraulically damp out the angular vibrations.

It should be noted that quite generally other frequency-dependent and amplitudedependent measures can be combined with those according to the invention in order to increase the effect described above or to influence (for example to increase or decrease) the damping in a particular sense for further characteristic frequency-amplitude ranges.

WHAT WE CLAIM IS:- 1. A resilient coupling for resiliently connecting two components movable relative to each other, the coupling being in the form of a hollow body -which in use of the coupling contains a hydraulic damping fluid, and the interior- of the body being divided into main and auxiliary chambers between which a restricted flow of fluid can take place upon relative movement between said two components, the coupling comprising first mounting means to which one of the components can be secured and which comprises two end portions of the hollow body which are spaced apart and fixed relative to each other, second mounting means to which the other of the components can be secured and which is of an annular form and is positioned generally between said two end portions, and resilient wall means which connects said first and second mounting means and comprises resilient annular wall portions which connect said second mounting means with said end portions, at least one of said end portions engaging the associated annular wall portion over a frusto-conical surface.

2. A coupling according to Claim 1 in in which at least one of said annular wall portions engages each of the associated end portion and the second mounting means over a frusto-conical surface.

3. A coupling according to Claim 2 in which at least one of said wall portions engages an outer frusto-conical surface of the associated end portion and an inner frusto-conical surface of the second mounting means.

4. A coupling according to any one of Claims 1 to 3 in which each wall portion is adhesively bonded to the associated end portion and the second mounting means.

5. A coupling according to any one of Claims 1 to 4 wherein there is a rigid dividing wall between said main and auxiliary chambers.

6. A coupling according to Claim 5 wherein the second mounting means comprises two sheet metal portions between which the dividing wall is clamped.

7. A coupling according to either one of Claims 5 and 6 including a spacer sleeve extending between the end portions through an aperture in the dividing wall.

8. A coupling according to Claim 7 wherein a nut and bolt assembly extending axially through the spacer sleeve connects the end portions to each other.

9. A coupling according to Claim 7 or Claim 8 wherein there is a gap between the outer surface of the spacer sleeve and the portion of the dividing wall defining said aperture.

10. A resilient coupling substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

11. - A coupling according to Claim 2 in which at least one of said wall portions engages an inner frusto-conical surface of the associated end portion and an outer frusto-conical surface of said second mounting means.

12. A coupling according to any one of Claims 1, 2 and 11 including a spacer sleeve extending between the end portions through

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

sponds to the operation of the coupling shown in Figure 10.

Figure -12 shows yet another version of fluid control means 8 which may be used in place of the fluid control means of the coupling shown in Figure 10. The fluid control means 8 comprises a body 190 having the shape shown which is formed integrally with the component 73. The body 190 has an aperture through which the bolt 150 extends to define the throttling restriction 162. The body 190 is connected to the component 73 by a relatively thin annular flange 191 which offers only slight resistance to axial movements of the body 190 so that for small axial movements the operation of the body corresponds to that of the body described with reference to Figure 10.

For large movements the resistance of the flange to deformation is substantially increased so that the movement of the body can be considered to be restricted within predetermined allowable limits.

Preferably, in each of the versions of Figures 10 to 12, the displacement volume of the body corresponds to a change in volume in the chambers produced by an overall oscillatory travel of the coupling of 0.2 to 0.3 m.m.

The invention is not limited to the particular arrangement of the end plates, chosen in the description, i.e. one end plate connected to the crankcase of the - engine and the mounting bracket connected to the engine supporting frame. The arrangement can equally well be different, as desired.

The main and auxiliary chambers could be made as mirror images without departing from the scope of the invention.

The coupling can also find use in couplings between rotating power sources and power-using machines, in that several couplings distributed around the components transmit the tangential forces and hydraulically damp out the angular vibrations.

It should be noted that quite generally other frequency-dependent and amplitudedependent measures can be combined with those according to the invention in order to increase the effect described above or to influence (for example to increase or decrease) the damping in a particular sense for further characteristic frequency-amplitude ranges.

WHAT WE CLAIM IS:- 1. A resilient coupling for resiliently connecting two components movable relative to each other, the coupling being in the form of a hollow body -which in use of the coupling contains a hydraulic damping fluid, and the interior- of the body being divided into main and auxiliary chambers between which a restricted flow of fluid can take place upon relative movement between said two components, the coupling comprising first mounting means to which one of the components can be secured and which comprises two end portions of the hollow body which are spaced apart and fixed relative to each other, second mounting means to which the other of the components can be secured and which is of an annular form and is positioned generally between said two end portions, and resilient wall means which connects said first and second mounting means and comprises resilient annular wall portions which connect said second mounting means with said end portions, at least one of said end portions engaging the associated annular wall portion over a frusto-conical surface.
2. A coupling according to Claim 1 in in which at least one of said annular wall portions engages each of the associated end portion and the second mounting means over a frusto-conical surface.
3. A coupling according to Claim 2 in which at least one of said wall portions engages an outer frusto-conical surface of the associated end portion and an inner frusto-conical surface of the second mounting means.
4. A coupling according to any one of Claims 1 to 3 in which each wall portion is adhesively bonded to the associated end portion and the second mounting means.
5. A coupling according to any one of Claims 1 to 4 wherein there is a rigid dividing wall between said main and auxiliary chambers.
6. A coupling according to Claim 5 wherein the second mounting means comprises two sheet metal portions between which the dividing wall is clamped.
7. A coupling according to either one of Claims 5 and 6 including a spacer sleeve extending between the end portions through an aperture in the dividing wall.
8. A coupling according to Claim 7 wherein a nut and bolt assembly extending axially through the spacer sleeve connects the end portions to each other.
9. A coupling according to Claim 7 or Claim 8 wherein there is a gap between the outer surface of the spacer sleeve and the portion of the dividing wall defining said aperture.
10. A resilient coupling substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.
11. - A coupling according to Claim 2 in which at least one of said wall portions engages an inner frusto-conical surface of the associated end portion and an outer frusto-conical surface of said second mounting means.
12. A coupling according to any one of Claims 1, 2 and 11 including a spacer sleeve extending between the end portions through

an aperture in a resilient dividing wall between the main and auxiliary chambers.
13. A coupling according to Claim 12 wherein the dividing wall is adhesively bonded to the spacer sleeve and to said second mounting means.
14. A coupling according to Claim 12 or Claim 13 wherein a passageway extends through the spacer sleeve, the passageway being connected to the main and auxiliary chambers by respective openings in the spacer sleeve so that fluid can pass between the chambers through the sleeve.
15. A coupling according to any one of Claims 1, 2, and 11 to 14 including a resilient diaphragm defining with one end portion a cavity, said cavity being sealed relative to the fluid chambers.
16. A coupling according to Claim 15 wherein the cavity is filled with a fluid at a higher or a lower pressure than the surroundings.
17. A coupling according to Claim 16 wherein the fluid is a gas.
18. A resilient coupling substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.
19. A coupling according to any one of Claims 1, 2, 11 and 12 wherein said wall portions are provided by a single body of a resilient material.
20. A coupling according to any one of Claims 1, 2, 11, 12 and 19 including a respective resilient diaphragm defining with each of the end portions a cavity, said cavities being sealed relative to the fluid chambers.
21. A coupling according to Claim 20 wherein the cavities are filled with a fluid at a higher or a lower pressure than the surroundings.
22. A coupling according to Claim 21 wherein the fluid is a gas.
23. A coupling according to Claim 20 wherein the end portions are formed with respective openings for venting the associated cavity to atmosphere.
24. A coupling according to any one of Claims 20 to 23 wherein the diaphragms each comprise rubber and metal components.
25. A coupling according to any one of Claims 20 to 24 wherein each diaphragm includes a respective bead engageable with the associated end portion for limiting movement of the diaphragm towards the associated end portion.
26. A coupling according to Claim 25 wherein each diaphragm further includes at least one resilient protuberance engageable with the associated end portion.
27. A coupling according to any one of Claims 1, 2, 11, 12 and 19 wherein at least one of the end portions is formed with a plurality of apertures and resilient diaphragm means extends over the apertures.
28. A coupling according to Claim 27 wherein the diaphragm means is adhesively bonded to the associated end portion.
29. A coupling according to either one of Claims 27 and 28 wherein the diaphragm means is made of a foamed plastics material.
30. A coupling according to Claim 29 including a layer of metal foil or platics material secured to the surface of the diaphragm means which is in contact with damping fluid.
31. A coupling according to either one of Claims 27 and 28 including means for limiting outward movement of the diaphragm means relative to the associated end portion.
32. A coupling according to any one of Claims 1, 2, 11, 12, and 19 to 31 wherein there is a gap between the outer surface of the spacer sleeve and the portion of the dividing wall defining said aperture.
33. A coupling according to- any one of Claims 1, 2 and 11 wherein said first mounting means comprises a U-shaped component for spacing the end portions apart wherein one limb of the component is secured to one of the end portions and the other limb is secured to the other of the end portions.
34. A coupling according to any one of Claims 1, 2, 11, 12 and 19 comprising fluid control means which is adjustable in response to changes in volume of the chambers.
35. A coupling according to Claim 34 wherein the fluid control means comprises a resilient annular body axially movable relative to a dividing wall between said chambers and having an aperture for the passage of fluid between the chambers.
36. A coupling according to Claim 35 wherein the annular body is axially movable between two extreme positions, the annular body and dividing wall being formed with complementary formations for limiting axial movement of the annular body.
37. A coupling according to Claim 36 wherein the complementary formations comprise an annular groove formed in the dividing wall and a peripheral portion of the annular body which is located in the groove.
38. A coupling according to Claim 36 wherein the complementary formations comprise an annular channel shaped groove provided on the peripheral portion of the annular body and a collar provided on the dividing wall, the collar being located in the groove.
39. A coupling according to Claim 37 or Claim 38 wherein the peripheral portion of the annular body together with the dividing wall defines an annular gap for the passage of fluid between the chambers.
40. A coupling according to Claim 37 wherein the passage of fluid between the chambers through a gap between the dividing wall and the annular body can take place when the body is in one of said extreme positions but not when it is in the other of said extreme positions.
41. A coupling according to Claim 35 wherein the annular body is connected to the dividing wall by a resilient flange.
42. A coupling according to any one of Claims 35 to 40 including means for spacing the end portions apart extending through the aperture in the annular body to define a throttling restriction.
43. A coupling according to Claim 42 wherein the periphery of the aperture has an arcuate axial profile.
44. A resilient coupling substantially as hereinbefore described with reference to Figures 3 and 4 of the accompanying drawings.
45. A resilient coupling substantially as hereinbefore described with reference to Figure 5 of the accompanying drawings.
46. A resilient coupling substantially as hereinbefore described with reference to Figure 6 of the accompanying drawings.
47. A resilient coupling according to Claim 46 as modified substantially as hereinbefore described with reference to Figure 7 of the accompanying drawings.
48. A resilient coupling substantially as hereinbefore described with reference to Figures 8 and 9 of the accompanying drawings.
49. A resilient coupling substantially as hereinbefore described with reference to Figure 10 of the accompanying drawings.
50. A resilient coupling substantially as hereinbefore described with reference to Figure 11 of the accompanying drawings.
51. A resilient coupling according to Claim 49 as modified substantially as hereinbefore described with reference to Figure 12 of the accompanying drawings.