GB1583964A - Vibration absorbing mountings for machines - Google Patents

Description

PATENT SPECIFICATION (

( 21) Application No 39913/79 ( 22) Filed 26 April 1977 ( 19) ( 62) Divided out of No 1 583 963 ( 31) Convention Application Nos.

( 33) Fed Rep of Germany (DE) 2618333 2 647 105 2 648 526 2718 121 2713 008 ( 11) ( 32) Filed 27 April 1976 19 Oct 1976 27 Oct 1976 23 March 1977 24 March 1977 in Complete Specification published 4 Feb 1981

INT CL 3 F 16 F 13/00 Index at acceptance F 2 S 101 410 411 AA ( 72) Inventors HEINZ BRENNER AND ARNO HAMAEKERS ( 54) VIBRATION ABSORBING MOUNTINGS FOR MACHINES ( 71) We, BOGE Gmb H, 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 has 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 up by the expansion chamber is not available for the main function of the coupling, namely the springing function 50 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 55 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 com 60 ponents, 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 65 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 70 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 75 whereby the coupling can accommodate vibrations of relatively small amplitude without, hydraulic damping.

In the coupling according to the present invention the space of the auxiliary chamber 80 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.

The rigid connection of the end portions 85 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 90 with the fluid pressure balanced in the main chamber and the auxiliary chamber can be Co 1 583 964 ( 44) ( 51) ( 52) 1,583; 964 made equal to one another or different from one another by appropriate shaping of the peripheral walls and, if necessary, of a resilient dividing wall between the chambers.

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.

The pressure-absorbing means may comprise a sheet of a resilient material extending over an inner plate member of the end portion The sheet can be of a resilient plastics foam material and, to separate the sheet from the damping fluid in the interior of the coup ling, an impervious barrier layer, for example of -metal: foil or a plastics material, may extend over an inner surface of the sheet.

There -may be a plurality of openings in the plate member covered by the sheet.

In an alternative arrangement, one end portion comprises a plate member in which there is a pluraility of apertures, and both sides of the plate member are covered with a resilient material The resilient material extends over the apertures, so that the apertures are closed by resilient diaphragms provided by the resilient material Preferably there are four apertures of a generally triangular shape in the plate member, the apertures beinguniformly spaced in a circular pattern.

In a further alternative arrangement, the pressure-absorbing means comprises a diaphragm member mounted opposite an inner surface of a plate member of the end portion, a cavity being formed between the diaphragm member and the plate member, the cavity being sealed from the damping fluid in the interior of the coupling The cavity may suitably be of an annular form The cavity can be vented to atmosphere through one or more apertures in the plate member, or alternatively can be a sealed cavity filled witha gas at a pressure different from that within the main and auxiliary chambers The diaphragm member can comprise a metal reinforcing disc, and an annular portion of a resilient material extending around the outer periphery of the disc Furthermore, the disc itself may be of annular form and the diaphragm member comprise also an annular portion of a resilient material extending around the inner periphery of the disc The or each annular portion of the diaphragm member may comprise an annular raised, bead arranged to engage the plate member to limit deflection of the diaphragm member.

Alternatively, a plurality of protuberances of a resilient material can be provided on the reinforcing disc to engage the plate member to limit deflection of the diaphragm member.

There is described and claimed in copending Patent Application No 17279/77 (Serial No 1,583,963), from which the present Application is divided, a resilient 70 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 75 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 80 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 85 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 resili 90 ent 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 95 There is described and claimed in copending Patent Application No 7944377 (Serial No 1,583,965), a resilient coupling for resiliently connecting two components movable relative to each other, the coupling 100 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 105 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 com 110 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 posi 115 tioned generally between said two end por tions and resilient wall means which connects said first and second mounting means and, comprises resilient annular wall portions which connect said second mounting means -120 with said end portions, said partition means comprising a movable portions arranged tomove to accommodate small variations in the volumes of the main and auxiliary chambers so that the coupling can accom 125 modate vibrations of small amplitude with out hydraulic damping.

Some embodiments of couplings according.

to the invention are illustrated by, way of 1,583,964 example only; in the accompanying drawings' wherein:

Figure 1 shows, a first embodiment; Figure 2 'shows' a second embodiment; Figure 3 shows-a'third embodiment; Figure 4 " shows part' of a fourth embodiment, being a modified form of the coupling shown in Figure 3; Figure' 5 shows a: fifth embodiment; and.

Figure 6 is a plan view of the coupling shown in Figure 5.

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 and resilient wall means 4 The end portions of the body comprise plate members, in the form of end plates 2 and 3, which are spaced apart' and' fixed relative to each other; the end portions are provided by first mounting means which is adapted to be connected to the engine 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 a 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 to 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 in' Figure 1, 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 resilient annular wall portions in the form of a pair of annular rubber rings 43, 44 which connect the mounting means 9 with the end portions of the body 1 The ring 43 is adhesively bonded at its outer edge to a concave frusto-conical surface of a metal ring 46 of one end portion and at its inner edge to a convex frusto-conical surface 47 of a flange 48 The flange 48 is pressed out of a sheet metal component forming an annular mounting bracket 49 of the mounting means 9 The ring 44 is adhesively bonded at its outer edge to a concave frustoconical surface 50 of a metal ring 51 of the other end portion, 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 of the mounting means 9 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.

' Partition means of the coupling comprises-a resilient rubber dividing wall' 55 integral with the ring; 43 The dividing wall 55 ' is' fornied' with an axially extending bore though which the sleeve 40 extends The wall 55 is adhesively bonded at its outer surface to'a cbon 70 cave frusto-conical surface 56 of the flange-48 and at its inner' surface to the sleeve 40.

Although the ring 43 anid dividing wall 55 are formed integrally$ they may, if desired be" formed 'as' separatecomponents 75 The bolts is formed'with two portions of reduced cross-section' defining a pair' oflands' 57, 58 and the portion of the bolt interinediate the lands is formed' with a' longitudinally extending channel' 5 Y providing a fluid con 80 nection between the lands The sleeve 40 is formed with a pair of'openings'60,' 61 Theopening 60 provides' a' fluid connection between the main chamber-6 and the land 57 and the opening 61 provides a fluid connection 85 between the land 58 and the auxiliary chamtber 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 90 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 95 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 inner surface of the end plate' 2 of one 100 end portion of the body 1 is formed with an annular recess 64 Opposite the inner surface of the end plate is a resilient diaphragm 65 of pressure-absorbing means of the'end portion; a sealed annular cavity 66 is thus' formed 105 ' between the diaphragm 65 and the end plate' 2 which is sealed relative to the main fluid' chamber 6 The cavity is filled with fluid,' preferably a gas As will be described in more detail later, the diaphragm 65 enables oscilla 110 tions'of small amplitude to be accommodated' without hydraulic damping The coupling can be used for mounting a vehicle engine; the end plate 2 being connected to 'the engine' crankcase by means of the bolt 41, and the 115 mounting bracket 49 being connected to an engine-carrying sub-frame of the vehicle.

In use when the crankcase of the engine oscillates in the direction of the axis of the bolt 41, i e towards 'and away 'from the 120 mounting bracket 49, variable dynamic engine' mounting forces are produced, dependent' on' the frequency-and amplitude of the oscillations.

These oscillations cause resilient' deforma 125 tion 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 " 130 " 1,583,964 diaphragm 65 against the fluid pressure in the cavity 66 Thus the 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 occuring and the diaphragm acts as a rigid wall For oscillations 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 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, 68 and channel 59.

As well as allowing oscillations in the direction of the bolt connecting the end plates together, limited transverse movements are also allowed and the coupling acts as a resilient spring in respect of them The transverse movements are limited by the resilience of the rubber dividing wall 55.

Referring now to the coupling shown in Figure 2, 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.

The body 73 provides resilient annular wall portions 74 and 77 which connect the mounting means 9 with the end portions of the body 1 One wall portion 74 is adhesively bonded to an inner frusto-conical surface 75 of a metal ring 76 of one end portion and the other wall portion 77 is adhesively bonded to an inner surface 78 of a metal ring 79 of the other end portion A frusto-conical flange 80 is formed by pressing from a sheet metal component 81 is embedded in and adhesively bonded to the central portion of the rubber body 73 The sheet metal component 81 forms a mounting bracket 82 of the mounting means 9 The rings 76, 79 are sealingly connected to the end plates 2, 3 by rolling the inner edges of the rings over the periphery of the associated end plate.

The central portion of the integral rubber body 73 which forms the partition means 5 forms an aperture defined by an annular collar portion 90 extending towards the auxiliary chamber 7 The sleeve 70 extends through the collar portion 90, the latter being of greater diameter than the sleeve 70 so that an annular gap 85 is formed The gap 85 provides the fluid control means between the chambers 6 and 7 The end portion of the collar portion 90 is reinforced by an angled metal insert 91.

Pressure-absorbing means of the second embodiment comprises a pair of disc-shaped sheets 92 of a resilient material, viz a plastics 75 foam material, one being attached to the inner surface of the end plate 2 and the other being attached to the inner surface of the end plate 3.

The coupling provides a resilient mounting 80 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, and the mounting bracket 82 is connected to an engine carrying sub-frame (not shown) 85 In use engine oscillations in direction of the axis of he bolt 71 produce variable dynamic engine mounting forces dependent on the frequency and amplitude of the oscillations.

These oscillations cause resilient deforma 90 tion of the rubber body 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 de 95 formation of the sheets 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 sheets 92 is dependent on the 100 resilience of the material of the bodies As the amplitude of the oscillations increases the deformation of the sheets 92 increases until it reaches a maximum at which they act as rigid bodies For oscillations of higher amplitude 105 the changes in volume result in fluid being forced through the gap 85 to produce hydraulic damping forces which absorb the engine mounting forces It will be appreciated that by appropriate selection of the material of the 110 sheets the range of oscillations which the coupling can absorb without hydraulic damping occurring can be set as desired.

For transverse movements of the engine greater than the width of the gap 85 the sleeve 115 comes into contact with the end portion of the collar portion 90 The end portion offers relatively small resistance to further transverse movement The magnitude of the transverse stiffness of the coupling can be set to 120 any desired value by appropriate shaping of the collar portion In addition to being able to yield transversely the collar portion 90 is sufficiently resilient to yield in the axial direction of the bolt 71 Axial movement of the 125 collar portion 90 allows differences in volume between the main and auxiliary chambers to be balanced out and also assists high frequency vibrations of small amplitude to be 1,583,964 absorbed with no displacement of fluid between the: chambers i e without hydraulic damping.

Figure 3 shows a coupling similar to the coupling shown in Figure 2 but incorporating an important modification Like reference numerals have been used for similar components The inner surface of each end plate is formed with an annular recess 100: Opposite 1:0 the inner surfaces of the end plates are mounted resilient rubber and metal diaphragms 101 of pressure-absorbing means of the end portions, to define annular cavities 102 which are vented to atmosphere through 15; apertures 103 in the end plates Each cavity 102 is sealed relative to the associated fluid chamber.

As shown each diaphragm 101 comprises, concentrically from inwards to outwards, an inner metal ring 104 clamped between the spacer sleeve 70 and the end plate, an inner annular rubber portion 105, a metallic annular reinforcing disc 106, an outer annular rubber portion 107 and an outer metal ring 108 which is clamped between the metal ring 76 and the end plate 2 Each outer rubber portion 107 comprises an annular raised bead 109 ' arranged to engage the associated end plate.

Each inner rubber portion 105 comprises an annular raised bead 110 arranged to engage the associated end plate The beads 109 and 110 are arranged to limit deflection of the diaphragms The region of the disc 106 lying between the beads 109 and 110 is coated with a thin layer of rubber.

Assume displacement of the end plate 2 from the position shown in Figure 3, regarded as static for simplicity, which should 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 101 towards the end plate 2 The resulting simultaneous increase in volume of the auxiliary chamber is balanced out by the deformation of the other diaphragm 101 away from the end plate 3 so that a vacuum, with a consequent undesired cavitation on 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 each diaphragm a gap remains between the disc 106 and the associated end plate, this gap being vented to atmosphere through the apertures 103.

The coupling can be used to mount an engine' and in use dynamic engine mounting forces produced by engine oscillations of high 70 frequency and small amplitude are, absorbed without hydraulic damping, the corresponding inward and outward movements of the diaphragms 101 being sufficient to accommodate small changes in volume without any' signi 75 ficant increase in pressure in the chambers.

Dynamic engine mounting forces produced by oscillations of low frequency and high amplitude are hydraulically damped by liquid being forced through the gap 85 to accommo 80 date the larger changes in volume of the chambers Transverse movements are accommodated in similar manner to the coupling described with reference to Figure 2.

Figure 4 shows a modification to the coup 85 ling shown in Figure 3 Like reference numerals are used for similar components In this embodiment the end plates are held spaced relative to each other by means of U-shaped retaining components (not shown), the limbs 90 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), 95 and the end portions of the couplings comprise pressure-absorbing means of slightly different construction from that shown in Figure 3 The pressure-absorbing means comprises an annular metal reinforcing disc 121 100 having an annular rubber portion 122 around it The rubber portion 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 resilient engagement of 105 the rubber portion 122 with the end plate.

Limitation of the movement of the diaphragm towards the end plate is further achieved by the provision of a plurality of resilient rubber protuberances, one only of 110 which is indicated by reference numeral 123, fixed to the metal disc 121 The diaphragm of the other end portion is of similar construction Operation of this coupling is similar to the operation of the coupling described with 115 reference to Figure 3, and vibrations of small amplitude are accommodated by the coupling without hydraulic damping.

In a modification the cavities 102 in the embodiments of Figures 3 and 4 can be filled 120 with a fluid, preferably a gas, at a higher or lower pressure than that within the chambers 6 and 7, in similar manner to the cavity described in the embodiment of Figure 1 The apertures 103 in the end plates are, of course, 125 omitted so that the cavities are sealed 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 drops; the resistance to inward displace 130 so 1,583,964 ment of the diaphragms would correspondingly be reduced to an undefined value For this reason it may be preferred to vent the cavities to atmosphere as initially described, so that a constant defined pressure is obtained in the cavities.

Figures 5 and 6 show a coupling similar to the coupling shown in Figure 2 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 discshaped member 133 The end plate 3 engages the shoulder 132 and is secured in positon by a nut 134.

As best shown in Figure 6, the end plate 2 is provided with four apertures 135 of a generally triangular shape, the apertures being uniformly spaced in a circular pattern As shown in Figure 5 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 of pressure-absorbing means of that end portion The end plate 3 is provided with a number of openings 138 which are covered by a sheet 139 of a resilient plastics foam material, for example a polyurethane foam, arranged over the inner surface of the end plate The sheet 139 is adhesively bonded to the inner surface of the end plate 3, but could be secured at its peripheral portions only so that the major portion freely engage the end plate 3 There is a danger that with a foamed plastics sheet comprising a number of individual cells there may be an exchange ofdamping fluid or gas between the sheet 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 sheet may be forced through the openings in the end plate Both these possibilities are undesirable and therefore it is preferred to provide a thin impervious barrier layer, of metal foil or plastics material, over the inner surface of the sheet as indicated in the right hand side of Figure 5 by reference numeral 139 a The barrier layer serves to separate the sheet from the damping fluid in the chamber 7, and generally to strengthen the sheet.

The coupling provides a resilient mounting for a vehicle engine (not shown) The end plate 2 is connected to the engine crankcase 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 -60 bolts 143.

The coupling shown in Figure 5 is in its rest position, ready for operation, which corresponds to a dynamic rest position of the coupling in which the four diaphragms 136 and the sheet 139 are relaxed.

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 dyamic engine 70 mounting forces are absorbed by resilient deformation of the diaphragm 136 and of the sheet 139 without any displacement of fluid occurring i e without hydraulic damping As the amplitude of the oscillations increases the 75 deformation of the diaphragms and the sheet 139 increases, the diaphrgams 136 assuming a curved shape, and the resistance to deformation progressively increases in corresponding manner until no further deformation can 80 occur and the diaphragms and the sheet 139 act as rigid bodies For outward movement of the diaphragms 136 this position is determined by engagement of the diaphrgams with the member 133 which acts as a stop to limit 85 outward movement, for example to 1 mm.

Inward movement of the diaphragm 136 is smaller and may for example be 02 mm For oscillations of larger amplitude, with the diaphragms and the sheet 139 acting as rigid 90 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 95 similar manner to the coupling described with reference to Figure 2.

Although the member 133 acts as a stop to limit outward movement of the diaphragms 136 this may not be necessary when the dia 100 phragms are made from a resilient material having a deformation-resistance sufficient to prevent outward movement beyond a predetermined distance irrespective of the pressure differences that may arise in the chambers 105 As shown the annular wall portion 144 which is connected to the end plate 2 is made thicker than the wall portion 145 which is connected to the end plate 3 The wall portion 144 substantially determines the resilient support 110 ing capacity of the coupling The wall portion comprises a flat, 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 115 changes in volume produced in the main chamber 6 and the auxiliary chamber 7 are different from one another This avoids the possibility that a sub-atmospheric pressure could arise in one of the chambers 6 or 7 120 with the formation of cavities in the liquid, giving rise to noise The same result may be obtained by making the wall portion 144 stronger than the wall portion 145.

Furthermore, while both end portions des 125 cribed comprise resilient pressure-absorbing means, in order to be able to compensate for the changes in both chambers during oscillations of small amplitude and high frequency, when the wall portion 144 connected to the 130 1,583,964 end plate 2 determines the resilient loadcarrying capacity of the coupling, and the wall portion 145 connected to the end plate 3 is made to yield in such a manner that it can on -5 its own accord absorb by corresponding deformation the volumes displaced at small amplitudes and high frequencies, it may be sufficient to provide resilient pressure-absorbing means only at the end plate 2 It may be preferably to provide resilient pressure absorbing means 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.

A coupling according to the invention may 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 amplitude-dependent measures can be combined with those described, in order to influence the damping in a particular sense for further characteristic frequency-amplitude ranges.

Claims (1)

1. 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 comprising resilient pressure-absorbing means whereby the coupling can accommodate vibrations of relatively small amplitude without hydraulic damping.

   2 A coupling according to Claim 1 wherein said pressure-absorbing means comprises a sheet of a resilient material extending over an inner surface of a plate member of the end portion.

   3 A coupling according to Claim 2 in which said sheet is of a resilient plastics foam 65 material.

   4 A coupling according to Claim 3 in Which an impervious barrier layer extends over an inner surface of said sheet to separate said sheet from the damping fluid in the in 70 terior of the coupling.

   A coupling according to any one of Claims 2, 3 and 4 in which said plate member is provided with a plurality of openings which are covered by said sheet 75 6 A coupling according to Claim 1 in which one end portion comprises a plate member in which there are apertures, both sides of said plate member being covered with a resilient material whereby each aperture is 80 closed by a resilient diaphragm of said pressure-absorbing means.

   7 A coupling according to Claim 6 in which there are four apertures of a generally traingular shape in the plate member, the 85 apertures being uniformly spaced in a circular pattern.

   8 A coupling according to Claim 1 in which said pressure-absorbing means comprises a diaphragm member mounted oppo 90 site an inner surface of a plate member of the end portion, a cavity being formed between the diaphragm member and the plate member, the cavity being sealed from the damping fluid in the interior of the coupling 95 9 A coupling according to Claim 8 in which the cavity is of an annular form.

   A coupling according to either one of Claims 8 and 9 in which the cavity is vented to atmosphere through an aperture in the plate 100 member.

   11 A coupling according to either one of Claims 8 and 9 in which the cavity is a sealed cavity filled with a gas at a pressure different from that within the main and auxiliary 105 chambers.

   12 A coupling according to any one of Claims 8 to 11 in which said diaphragm member comprises a metal reinforcing disc, and an annular portion of a resilient material 110 extending around the outer periphery of said disc.

   13 A coupling according to Claim 12 in which said disc is of annular form and said diaphragm member comprises also an annular 115 portion of a resilient material extending around the inner periphery of said disc.

   14 A coupling according to Claim 12 in which said annular portion of the diaphragm member comprises an annular raised bead 120 arranged to engage the plate member to limit deflection of the diaphragm member.

   A coupling according to Claim 13 in which said annular portion extending around the inner periphery of the disc comprises an 125 annular raised bead arranged to engage the plate member to limit deflection of the diaphragm member.

   1 l,583,964 16 A coupling according to Claim 12 in which a plurality of proturberances of a resilient material are provided on said disc to engage the plate member to limit deflection of the diaphragm member.

   BARKER, BRETTELL & DUNCAN Chartered Patent Agents, Agents for the Applicants, 138 Hagley Road, Edgbaston, Birmingham B 16 9 PW.

   Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon), Ltd -1981.

   Published: at The Patent Office, 25 Southampton Buildings, London, WC 2 A l AY from which copies may be obtained.

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