GB1603188A

GB1603188A - Felxible coupling for shafts

Info

Publication number: GB1603188A
Application number: GB15351/78A
Authority: GB
Original assignee: Boge GmbH
Current assignee: ZF Boge GmbH
Priority date: 1977-04-19
Filing date: 1978-04-19
Publication date: 1981-11-18
Also published as: ES468889A1; BR7802410A; AU501637B1; IT1094437B; AR214007A1; CA1080989A; NL7804080A; FR2388164A1; JPS5413855A; CS214769B2; DD135752A5; IT7822445A0; SE7804066L; ATA273478A

Description

(54) FLEXIBLE COUPLING FOR SHAFTS (71) We, BOGE GMBH, a German Company of 5208 Eitorf, Sieg, 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 stateme't : - The present invention concerns improvements in or relating to flexible shaft couplings.

Such couplings are capable of resiliently handling and absorbing non-uniform torques as well as axial and angular displacements between the driving and driven shafts of two machines connected together by the coupling.

In the coupling of this kind known from German Patent Specification 1450191 a number of pre-loaded rubber elements are each vulcanised to the adjacent surfaces of two adjacent spokes between which they are arranged. The rubber elements have a massive cross section and, by virtue of their damping characteristics resulting from the hysteresis in the rubber material, they are able to damp out resonant oscillations in the machines in a peripheral direction as long as the exciting forces of these torsional oscillations do not exceed the damping forces that the rubber elements are capable of developing. When the exciting forces exceed the damping forces that can be generated, the amplitudes of the oscillations can become so large in a disadvantageous manner that unacceptable rough running occurs, or destruction of the coupling or of other components of the drive can take place.

According to the present invention we provide a flexible coupling for connecting a driving shaft to a driven shaft comprising two coupling members adapted to be connected one to each of the driving and driven shafts for rotation therewith and resilient torquetransmitting and damping means extending between the coupling members so as to be subjected to compression and/or shear loading for the transmission of torque from one member to the other, said means comprising a first portion extending between an abutment of a first of said coupling members and a first abutment of the second coupling member and comprising a first cavity, and a second portion extending between the abutment of the first member and a second abutment of the second member and comprising a second cavity, each of the cavities containing a damping fluid and the arrangement being such that in use relative movement of approach between the abutment of the first member and the first abutment of the second member, upon relative rotation between the coupling members in one direction, is damped by the displacement of damping fluid from said first cavity, and relative movement of approach between the abutment of the first member and the second abutment of the second member, upon relative rotation between the coupling members in the opposite direction, is damped by the displacement of damping fluid from said second cavity.

In one possible form, the torque-transmitting and damping means comprises a ring of hollow resilient elements containing damping fluid, each element extending between a resspective surface on the first member and a respective surface on the second member.

Conveniently the surfaces on each member can be defined by spokes which project either radially or axially from a central hub adapted for connection to the driving or driven shaft. Each element preferably comprises a body portion made of rubber and extends between a spoke of the first member and a spoke of the second member and elements on opposite sides of certain spokes are in communication with one another through a throttling restriction to control the passage of damping fluid. The damping fluid may be a liquid or a gas.

When there is elastic deformation of the resilient elements, associated with torsional oscillations of the coupling, the volume of the cavity of the element on one side of the spoke, preferably filled with a liquid, is in creased and simultaneously the volume of the cavity of the element on the other side is reduced, so that there is an exchange of fluid between the cavities through the throttling restrictions in the spokes and the resistance to flow of the restrictions can, by appropriate shaping and dimensions of the components of the coupling, produce sufficient hydraulic damping forces to ensure smooth running of the machines and to prevent destruction of the machine components by resonant oscillations.

In a coupling made up generally of annular components of the same shape, all the spokes or only those associated with one member can have holes providing throttling restrictions. The resilient elements preferably have a sufficiently large pre-loading when the coupling is without torque, in the interests of long life, that under all conditions of operation the stresses in the elements that transmit the circumferential forces experience no change of sign.

The resilient elements can form a unitary coupling ring with the spokes, vulcanised together in one operation, if the elements have cavities produced in an appropriate process.

A coupling ring can be made up of two halves brought together axially, and having recesses which form the cavities in the coupling. In order to obtain the abovementioned pre-loading of the resilient elements, a correspondingly large coupling ring can be reduced, by suitable means, to the insertion diameter as the coupling is assembled together. The elements can form a rubber/ metal component with the spokes of one member, gaps being provided between the elements, into which the spokes of the other member are inserted or are capable of being inserted.

Where a coupling is built up of individual vulcanised rubber/metal components of which the cavities are obtained by the use of easily withdrawn tool parts, the elements can be held between the spokes by pre-loading, the retention being assisted by an adhesive bond if necessary. Metallic end plates can be vul canised onto the rubber portions of the elements, these plates being stuck to the spokes or sealed by a rubber skin which engages against the spokes under pre-loading. For this purpose projecting edges on the end plates, folded over before or during assembly, engage in grooves in the spokes, thereby ensuring the connection of the end plates to the spokes. The end plates can be provided with the throttling restrictions to control the flow of fluid. The end plates of adjacent resilient elements can abut against one another, can be connected together and can have means for connection to a member so that the end plates effectively form spokes.

A preferred form of a compression-loaded resilient element is a tubular component with a cavity extending circumferentially of the coupling. The walls of a rubber body portion of the element, especially in the region of the cavity, can be reinforced circumferentially of the coupling by yielding inserts, for example by a coil spring, to prevent the element folding outwards under the action of the circumferential forces or centrifugal forces. The latter can also be achieved by the provision of one or more radially extending supporting walls vulcanised to the element, by which walls two mutually separated cavities of the element can be formed, each of which can exchange fluid with a respective cavity lying on the other side of the adjacent spoke. Where there is a danger that the elements might be displaced outwards unacceptably by centrifugal forces, assistance can be given by vulcanised-on support plates connected together by tension members or enclosed by support rings which are clear of the spokes. One or more rings enclosing the coupling could also serve to hold the spokes in their positions, the supporting rings being removed on completion or they could remain as a rigid component of the coupling. If two resilient elements are contemplated, formed as compression-loaded annular components, of which one engages one side of the spoke and the other engages the other side of that spoke, the one element will be shortened in a circumferential direction by a correspondingly directed circumferential force in the coupling and simultaneously the other element will be circumferentially stretched.

The corresponding reduction in volume produced in the one element for the quantity of fluid that is exchanged-therefore also for the damping forces that can be obtained can be partially relieved by expansion of the element in an transverse direction in a manner that reduces the damping, and the increase in volume produced in the other element can be partially relieved by transverse contraction of the cavity. In order to be able to achieve as high a fluid damping as possible, means are preferably provided to balance out this effect, for example the cavities can be provided with a constriction which on increasing compression loading of the resilient element, is increasingly constricted, or expansion or contraction of the cavity can be prevented by vulcanising in a coil spring already mentioned, into the wall of the cavity.

Also the radially directed supporting walls already mentioned have a weakening effect in this direction. Projections on the spokes, extending into the cavities, can be employed for mechanically limiting the relative ap proach of the spokes or can increase the compression ratio of the cavities on relative movements of the spokes of the two hubs if the cavities are filled with a compressible damping medium In a preferred form of a shear-loaded resi lient element, a rubber ring has an outer peripheral surface vulcanised to an outer peripheral wall member connected to a spoke of the one hub, and an inner peripheral surface vulcanised to an inner peripheral wall member connected to a spoke of the other hub. The peripheral wall members can have free faces provided with sealing means and engaging the spokes with pre-loading in the assembled coupling.

The spokes could be in one piece with a hub or could be connected to a hub in a suitable manner, for example by seam welds.

The spokes could be provided with sleeves or bores into which are inserted the pins of a hub. If the circumferential forces do not pass through the centre of the sleeve or the centre of the bore and exert a moment with respect to these means, provision must be made to prevent the spokes turning. This can be achieved by peripheral rings or annular discs connected to the spokes, for example by welding.

The damping medium is preferably in serted after the coupling is assembled together. Closable filler openings can be provided for this purpose at suitable points and if necessary additional closable air-venting openings can be provided.

Where all the cavities of the resilient ele ments are connected together, it is sufficient to provide only a single filler opening. The damping medium can, in the finished coup ling, be at a pressure which is equal to, above or below atmospheric pressure. In particular where the damping medium is gaseous we prefer to use a pressure above atmospheric.

The heat generated in the fluid by oscillation of the coupling can only escape to a small extent through the poor conducting medium of the rubber material and must largely be conducted away to the metallic components of the coupling lying in the region of the cavities, for example through the spokes or through radial supporting plates which may be provided. These components can be pro vided with enlarged surfaces dissipating the heat to atmosphere and can be of a shape such that they promote a cooling air circula tion around the coupling like fans.

Where resilient elements are used with the circumferential forces taken by compression stresses and with cylindrical cavities extending through them in a circumferential direction, and where they are supported, against dis placement, especially against displacement by centrifugal forces, by substantially radially extending end plates or end pieces connected to the spokes there arise, between the end plates and end pieces, unsupported regions of the elements which are bulged outwards by the centrifugal forces and must therefore withstand the resulting additional internal stresses. From a predetermined limiting rota tional speed upwards the elements are then no longer in a position to withstand the internal stresses produced by the centrifugal forces.

In order to allow a shaft coupling to be used even at high speeds, the arrangement can be such that annular cylindrical resilient elements are inserted in openings in a coupling disc (the openings extending parallel to the axis of the coupling and being uniformly spaced about the axis) and serve to receive follower pins forming the spokes of . one member and inserted axially into the elements, fluid filled cavities being formed by opposed pockets in the elements and each cavity being closed by a portion of the wall bounding that opening in the coupling disc.

The annular cylindrical resilient elements can be connected directly to a follower pin or comprise a rigid inner sleeve to which a rubber body portion is secured, preferably adhesively, the sleeve serving to receive a follower pin. The resilient elements can be made over-size with respect to the openings in the coupling disc and are inserted in the openings with compression pre-load or they comprise a rigid ring-shaped sleeve, to which the rubber body portion may also be secured adhesively, that can be inserted into the openings. Edges of the pockets in the elements, forming the cavities, can be provided with sealing beads which achieve a reliable sealing of the cavities with respect to the walls bounding the openings of the coupling disc.

In a first embodiment of this shaft coupling with resilient elements inserted in openings in a coupling disc, the walls of the disc remaining between the openings form the spokes of the other member, the coupling disc being provided with suitable means for connecting it to the driving and driven shafts.

In a second embodiment of this coupling the follower pins alternately form the spokes of the one and of the other member, the coupling disc being being held floating between the hubs in a manner known in itself.

For a given number of identical resilient elements in a given coupling disc, a shaft coupling of the first kind can transmit twice the torque of a coupling of the second kind.

On the other hand the stiffness (torque per unit angular deflection) of a coupling of the first kind is four times that of a coupling of the second kind. Correspondingly a coup ling of the second kind is in a better position to compensate for errors of alignment of the driving and driven shafts.

A floating coupling disc can be connected in a known manner to the member by additional means and retained by it in order to prevent any danger of the disc breaking away at high rotational speeds through lack of balance. In shaft couplings of the first kind, the throttling restrictions that control the damping forces can be provided in the walls between the openings of the coupling disc and/or in the resilient elements between their two pockets. In shaft couplings of the second kind, with a floating coupling disc, throttling restrictions between the pockets of each rubber element are essential, whereas throttling restrictions in the walls between the openings of the coupling disc may be unnecessary or ineffective as the cavities separated by these walls in two adjacent rubber elements experience equal volume changes on grounds of symmetry. Preferably throttling restrictions are provided both in the walls between the openings of the coupling disc and also in the resilient elements in order to provide a continuous communication between all cavities for filling of the damping fluid and also for the venting of air. For filling and venting, suitable passages, if necessary capable of being closed off, can be provided at other points in the coupling disc and the resilient elements.

Some embodiments of couplings according to the invention are illustrated in the drawings by way of example and further features of the invention are disclosed by the description of the Figures. In the drawings: Figure 1 shows a cross section through a coupling with two hubs provided with cranked spokes and with compression pre-loaded resilient elements held between the spokes, Figure 2 is a longitudinal section through the coupling of Figure 1, Figure 3 shows a resilient element of the coupling of Figure 1 before assembly, Figure 4 shows a coupling in which six resilient elements together with three spokes of a hub form a rubber/metal component with gaps between the resilient elements after assembly, Figure 5 is a partial view of the rubber/ metal component of Figure 4 before assembly, Figure 6 shows a rubber/metal resilient element of a coupling ring made up of three identical elements, Figure 7 shows the element of Figure 6 in its assembled condition with an adjacent element, shown circumferentially sectioned, Figure 8 shows a further form of resilient element before assembly, Figure 9 shows the element of Figure 8 shear-loaded and fitted in place between two spokes, Figure 10 shows in cross section a shaft coupling with six resilient elements inserted in openings in a coupling disc and adhesively connected to follower pins, Figure 11 shows a longitudinal section through the coupling of Figure 10, Figure 12 shows, in longitundinal section in the circumferential direction of a a notional coupling disc, a resilient element comprising a rubber body portion adhesively connected to a peripheral ring and capable of insertion in an opening in a coupling disc, Figure 13 shows a section through the element of Figure 12, Figure 14 shows a longitudinal section through a shaft coupling in which elements as shown in Figures 12 and 13 are inserted in openings in a coupling disc, the elements each comprising an inner sleeve and an annular peripheral ring adhesively connected to the rubber body portion.

In the description of the drawings a first hub is a hub that can be connected to the one machine and a second hub is a hub that can be connected to the other machine.

The coupling shown in Figures 1 and 2 comprises a first hub 1 provided with an attachment flange 15 and with four cranked spokes 11 to 14 and a second hub 2 provided with an attachment flange 25 and with four cranked spokes 21 to 24. The spokes 11 to 14 lie between the spokes 21 to 24, and are attached to a stub shaft 16 integral with the flange 15 by welds 17. The spokes 21 to 24 are attached to a stub shaft 26 integral with the flange 25 by welds 27. Between the spokes 11 and 21, 21 and 12 and so on are held a respective one of eight resilient elements 31 to 38 comprising tubular rubber body portions having cavities 41 to 48 and 41' to 48' filled with fluid and separated by supporting walls 51 to 58. As shown in Figure 2, the elements 31 to 38 have, in the torque-free condition of the coupling as drawn, a rectangular cross section 38' with markedly rounded corners, and cavities 41 to 48 and 41' to 48' have a round cross section 48". The elements 31 to 38 are, before assembly, identical with the element 36 shown in Figure 3 which, comprising the supporting wall 56 and end plates 59 and 60, forms a cylindrical annular vulcanised rubber/ metal component of the coupling. The mean length of the element 36 is greater before than after assembly in the coupling, the element being compression pre-loaded upon insertion into the space between the spokes 14 and 23 in assembly of the coupling. The element 36 is provided with cavities 46 and 46' of which the shape (before assembly) differs correspondingly from the shape of the cavities shown in Figure 1. The end plates 59 and 60 have on their outer faces a rubber skin 61 and 62 respectively and a projecting rim 63 and 64 respectively all round. The spokes 11 to 14 and 21 to 24 are provided with longitudinal grooves 71 and 72 and with radial grooves which are not visible but which are of the same form as the grooves 71, into which grooves the correspondingly folded down rims 63 and 64 of the end plates 59 and 60 engage so that the respective end plates 59 and 60 of the elements 31 to 38 are pressed rigidly and tightly against the faces of the spokes 11 to 14 and 21 to 24 and thereby secured against displacement. The spokes 11 to 14 and 21 to 24 each have a throttling restriction 91 to 98 formed as a hole in each spoke. The spoke 24 is provided with a closeable filler opening 65 from which a passage 73 leads to the throttling hole 98. The supporting plates 51 to 58 could be provided with holes 66 solely for the purpose of providing an interconnection between all the cavities to allow filling with fluid to be undertaken from a single filler opening 65. Some further optional features are that the element 34 can have a circumferentially yielding insert in the form of, for example, a reinforcing coil spring 67 vulcanised into the walls of the cavities 44 and 44', and in the spoke 23 there is indicated a freely moveable valve body 68 of limited travel provided in the throttling hole 96 to damn out high frequency oscillations of small amplitude without the exchange of fluid between the cavities 45' and 46, in order to prevent the transmission of high frequency oscillations, in particular acoustic frequencies, from one to the other of the coupled machines.

In element 35 there is indicated the possibility of providing a constriction 69 and a constriction 70 of the cavity 45 which is further constricted on increasing compression force loading in a circumferential direction (with respect to the coupling).

On relative clockwise angular movement of the hub 1 with respect to the hub 2, thought of as stationary, the spokes 11, 12, 13 and 14 approach spokes 21, 22, 23 and 24 and simultaneously move away from the spokes 24, 23, 22 and 21 so that the volume of the cavities 41 and 41', 43 and 43', 45 and 45', and 47 and 47' is reduced and the volume of the cavities 42 and 42', 44 and 44', 46 and 46' and 48 and 48' is increased.

This causes an exchange of fluid between the cavities adjacent to each spoke through the throttling hole 91 to 98 in a corresponding direction, for example between the cavities 41 and 48' through the hole 91 in a direction from the cavity 41 to the cavity 48', causing an excess pressure to be built up in the cavity 41, determined by the resistance to flow offered by the throttling hole 91. On grounds of symmetry the same pressure is built up in the cavity 41' separated from the cavity 41 by the supporting wall 51, causing emptying into the cavity 42, it being irrelevant whether the supporting wall 51 has a hole 66 or not. The same sequence of events takes place in all the cavities as in the named cavities 41, 48' and 41', 42 and correspondingly in the reverse sense when there is angular displacement of the hub 1 with respect to the hub 2 in a counterclockwise direction.

In the coupling shown in Figure 4 a first hub 101 is formed by a hub ring 117 provided with a bore 115 and a keyway 116 and by three spokes 111 to 113 projecting from the ring 117.

Rubber elements 131, 132, 133, 134, 135 and 136 are vulcanised to the side faces of the spokes 111 to 113, the free end faces 131' to 136' of the elements engaging tightly and securely with compression pre-loading against the side faces of three wedge-shaped spoke sockets 121 to 123 with bores 124 to 126 through them, in which bores follower pins of a second hub, are inserted. The rubber elements 131 to 136 have cavities 141 to 146 separated from one another by. the spokes 111 to 113. The spoke sockets 121 to 123 are provided with throttling restrictions 191 to 193 which each open into the respective adjacent cavities and control the damping forces. The spoke sockets 121 to 123 are provided on both sides with projecting edges, preferably forming box-shaped projections 151 to 156, which hold the ends of the rubber elements 131 to 136 in position and secure them against displacement. A tension hoop, (not shown) which encloses the coupling and which can be removed as soon as the follower pins of the second hub are inserted in the bores 124 to 126, may serve to hold the spoke sockets 121 to 123 in their positions shown.

Figure 5 shows the shape of the elements 131 and 132 and of the cavities 141 and 142 before assembly. It can be seen that the hub 101 and the elements 131 to 136 of Figure 4 form a complete rubber/metal component with gaps 137 between the elements before assembly of the coupling.

The rubber/metal element shown in Figure 6 comprises, adhesively secured together, a box-shaped metallic end plate 259, provided with a bore 275, a rubber body portion 231 provided with a cavity 241, a spoke socket 251 forming a sleeve 254, a rubber body portion 232 provided with a cavity 242 and a box-shaped metallic end plate 260 provided with a through bore 276. The end plate 259 comprises walls 258 which embrace the rubber body portion 231 and a base 257 provided on its outer face with an annular sealing lip 256. The end plate 260 comprises a base 261 vulcanised to the rubber body portion 232 and with its face that is away from the body portion 232 provided with a sealing lip 262, and outwardly directed walls 263. The end plate 259 is smaller than the end plate 260 and can be inserted into the end plate 260' of the adjacent rubber/ metal element, and an intermediate sheet metal wall 264 provided with a throttling restriction 291 is placed between the base 257 and the base 261'.

As shown in Figure 7, a follower pin 265 passing through the cavity 241 can be inserted into the bores 275 and 276' and secured by means of a nut 266 which connects the end plates 259 and 260' together, the sealing lips 256 and 262' sealing the cavities 241 and 242' from atmosphere and the follower pins 265 are sealed by sealing beads 267 and 268 of the bore 275. Three rubber/metal elements of the kind as shown in Figure 6, assembled in this manner, form a coupling ring, in the sleeves 254 of which there are inserted respective follower pins of a threearmed first hub (not shown), whilst three follower pins 265 are connected to a second hub (not shown). The radius of curvature of the rubber/metal elements, when unstressed, is larger than required to correspond with the hubs. On assembly of the coupling ring to the hubs the diameter of the coupling ring is reduced, for example by means of a tension hoop, until the radii of curvature match. Then the follower pins can be inserted and a residual pre-loading of all three rubber/metal elements is obtained.

As shown in Figure 8 a vulcanised resilient element 331 is formed by an outer metal sleeve 357, an inner metal sleeve 358 and a rubber ring 356 of parallelogram section and is provided with a cavity 341 passing right through it. The sleeve 357 has a rubbercoated flange 359, and the sleeve 358 has a rubber-coated flange 360 parallel to the flange 359.

In the assembled condition shown in Figure 9 the element 331, of which the flanges remain parallel, is clamped between two wedge- shaped spoke sockets 311 and 321, the rubber ring 356 having taken up a rectangular cross section, the element 331 engaging tightly against the side faces of the spoke sockets 311 and 321 and being secured against lateral displacement by projecting flanges 361 and 362 on the spoke sockets. The spoke socket 321 is provided with a throttling restriction 391 which connects the cavity 341 to the cavity of an adjacent mirror image element 332. The spoke socket 311 has a lug 363 to receive a follower pin of a first hub, and the spoke socket 321 has a bore 364 to receive a follower pin of a second hub. The spoke socket 311, a second spoke socket 312 and all further spoke sockets of the first hub are connected rigidly together by an annular disc 365 to which they are secured for example by welding.

The spoke socket 321 and all further spoke sockets of the second hub have no contact with the disc 365 and are rigidly connected together by an annular disc (not shown) lying in front of the plane of the drawing.

The shaft coupling shown in Figures 10 and 11 has a coupling disc 407 provided with six openings 408 which extend parallel to the axis of the coupling and are uniformly spaced about the axis. Six rubber elements 401 to 406 are inserted into the openings.

Follower pins 410 adhesively connected directly to the elements 401 to 406 are secured to a flange 414 of a hub 415 which has a bore 413 for the insertion of a shaft, for example a driving shaft (not shown). A hub 416 provided with a bore 418 to receive the driven shaft (not shown) is connected through a flange 417 to the coupling disc 407 by means of follower pins 411 secured in the flange and engaging in bores 409 in the disc 407. The walls 412 of the disc 407, formed between the openings 408, forming spokes of the hub 416. A central bore 419 in the disc 407 can also serve directly to receive the driving or driven shaft, in which case the coupling disc is also a hub and then no separate hub 416 is needed.

The rubber elements 401 to 406 are in an over-size condition before insertion into the openings 408, so that a compression pre-load is present after insertion into the openings 408. They can also be adhesively connected to the periphery of the openings 408. As illustrated on the element 401, the elements 401 to 406 are provided in the circumferential direction of the disc 407, on opposite sides of the follower pin 410, with opposed pockets 421 and 422 which are separated from one another by rubber webs 42 on of all the elements 401 to 406 are increased and reduced in size, so that between these cavities there is an exchange of damping fluid against the resistance to flow offered by the respective throttling restrictions. The holes can be of such dimensions and of such shape that the oscillations, in particular of large amplitude, are effectively damped and the holes can also be provided with means for controlling the resistance to flow in accordance with velocity or with other factors.

The resilient element shown in Figures 12 and 13 is a rubber/metal component and comprises an inner bush 440, an external sleeve 441 and an annular cylindrical rubber body portion 444 which is adhesively connettted to these parts and in which, opposite rectangular recesses 442 and 443 of the sleeve 441 there are formed opposed pockets 445 and 446. The edges of the pockets 445 and 446 are provided with sealing beads 447 projecting at the outer periphery of the sleeve 441. The pockets 445 and 446 are separated by rubber webs 449 and 450. A cylindrical hole 452 reinforced by a rigid tube 451 connects the pockets 445 and 446 together.

In the shaft coupling shown in Figure 14 a coupling disc 470 can be the same as the disc 407 of Figure 10 with regard to the number and disposition of the resilient ele ments. In openings 481 of the disc 470 there e provided either an element 482 provided iith pockets 494, which corresponds to the element of Figures 12 and 13, or an element 483 provided with pockets 495 and corresponding substantially to the element 482 but, departing from this, it has not a sleeve 484 but two separate sleeves 485 and 486 so that in the region of the pockets 495 the reinforcement provided by the sleeve 484 on the element 482 is absent. Follower pins 487 are inserted into the element 482 from the right and pins 488 are inserted into the element 483 from the left.

Parts 489 and 490 of the follower pins 487 projecting to the right can be connected to a hub 496, shown in broken lines, of a shaft, for example the driving shaft. Portions 491 and 492 of the follower pins 488 projecting to the left can be connected to a hub 497, indicated in broken lines, of the driven shaft. Throttling restrictions 498 and 499 in the elements 482 and 483 control the damping forces produced by changes in volume of the cavities formed by the pockets 494 and 495. The coupling disc 470 is held floating between the hubs 496 and 497.

WHAT WE CLAIM IS: 1. A flexible coupling for connecting a driving shaft to a driven shaft comprising two coupling members adapted to be connected one to each of the driving and driven shafts for rotation therewtih and resilient torquetransmitting and damping means extending between the coupling members so as to be subjected to compression and/or shear loading for the transmission of torque from one member to the other, said means comprising a first portion extending between an abutment of a first of said coupling members and a first abutment of the second coupling member and comprising a first cavity, and a second portion extending between the abutment of the first member and a second abutment of the second member and comprising a second cavity, each of the cavities containing a damping fluid and the arrangement being such that in use relative movement of approach between the abutment of the first member and the first abutment of the second member, upon relative rotation between the coupling members in one direction, is damped by the displacement of damping fluid from said first cavity, and relative movement of approach between the abutment of the first member and the second abutment of the second member, upon relative rotation between the coupling members in the opposite direction, is damped by the displacement of damping fluid from said second cavity.

2. A coupling according to claim 1 wherein the torque-transmitting and damping means comprises a ring of hollow resilient elements containing damping fluid, each element extending between a respective surface on the first member and a respective surface on the second member.

3. A coupling according to claim 2 wherein the first and second members each comprise a central hub with uniformly spaced radially extending spokes, the spokes of the first member being angularly offset relative to the spokes of the second member with one of said elements extending between each spoke of the first member and an adjacent spoke of the second member.

4. A coupling according to claim 3 wherein the elements on opposite sides of each spoke of the second member are in communication with one another through a respective throttling restriction adapted to control the flow of damping fluid between the elements.

5. A coupling according to claim 4 wherein the resilient elements on opposite sides of each spoke of the first member are in communication with one another through a respective throttling restriction.

6. A coupling according to claim 4 or claim 5 wherein each throttling restriction comprises a hole in the associated spoke.

7. A coupling according to claim 6 wherein each throttling restriction includes a moveable valve body mounted in the hole in the associated spoke.

8. A coupling according to any one of claims 3 to 7 wherein each element has two cavities containing damping fluid separated by a respective separating wall.

9. A coupling according to claim 8 wherein

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. on of all the elements 401 to 406 are increased and reduced in size, so that between these cavities there is an exchange of damping fluid against the resistance to flow offered by the respective throttling restrictions. The holes can be of such dimensions and of such shape that the oscillations, in particular of large amplitude, are effectively damped and the holes can also be provided with means for controlling the resistance to flow in accordance with velocity or with other factors. The resilient element shown in Figures 12 and 13 is a rubber/metal component and comprises an inner bush 440, an external sleeve 441 and an annular cylindrical rubber body portion 444 which is adhesively connettted to these parts and in which, opposite rectangular recesses 442 and 443 of the sleeve 441 there are formed opposed pockets 445 and 446. The edges of the pockets 445 and 446 are provided with sealing beads 447 projecting at the outer periphery of the sleeve 441. The pockets 445 and 446 are separated by rubber webs 449 and 450. A cylindrical hole 452 reinforced by a rigid tube 451 connects the pockets 445 and 446 together. In the shaft coupling shown in Figure 14 a coupling disc 470 can be the same as the disc 407 of Figure 10 with regard to the number and disposition of the resilient ele ments. In openings 481 of the disc 470 there e provided either an element 482 provided iith pockets 494, which corresponds to the element of Figures 12 and 13, or an element 483 provided with pockets 495 and corresponding substantially to the element 482 but, departing from this, it has not a sleeve 484 but two separate sleeves 485 and 486 so that in the region of the pockets 495 the reinforcement provided by the sleeve 484 on the element 482 is absent. Follower pins 487 are inserted into the element 482 from the right and pins 488 are inserted into the element 483 from the left. Parts 489 and 490 of the follower pins 487 projecting to the right can be connected to a hub 496, shown in broken lines, of a shaft, for example the driving shaft. Portions 491 and 492 of the follower pins 488 projecting to the left can be connected to a hub 497, indicated in broken lines, of the driven shaft. Throttling restrictions 498 and 499 in the elements 482 and 483 control the damping forces produced by changes in volume of the cavities formed by the pockets 494 and 495. The coupling disc 470 is held floating between the hubs 496 and 497. WHAT WE CLAIM IS:

1. A flexible coupling for connecting a driving shaft to a driven shaft comprising two coupling members adapted to be connected one to each of the driving and driven shafts for rotation therewtih and resilient torquetransmitting and damping means extending between the coupling members so as to be subjected to compression and/or shear loading for the transmission of torque from one member to the other, said means comprising a first portion extending between an abutment of a first of said coupling members and a first abutment of the second coupling member and comprising a first cavity, and a second portion extending between the abutment of the first member and a second abutment of the second member and comprising a second cavity, each of the cavities containing a damping fluid and the arrangement being such that in use relative movement of approach between the abutment of the first member and the first abutment of the second member, upon relative rotation between the coupling members in one direction, is damped by the displacement of damping fluid from said first cavity, and relative movement of approach between the abutment of the first member and the second abutment of the second member, upon relative rotation between the coupling members in the opposite direction, is damped by the displacement of damping fluid from said second cavity.

9. A coupling according to claim 8 wherein

each separating wall has an aperture to allow the passage of damping fluid between the cavities.

10. A coupling according to any one of claims 3 to 9 wherein each element has end plates adapted to engage the spokes of the associated first and second members to retain the elements in position.

11. A coupling according to any one of claims 3 to 10 wherein each element comprises a tubular body which is compression pre-loaded.

12. A coupling according to any one of claims 3 to 11 wherein the walls of each element -are reinforced by inserts arranged to yield circumferentially of the coupling.

13. A coupling according to any one of claims 3 to 12 wherein each element has a constriction for conntrolling the flow of damping fluid which is constricted on increasing the compression loading of the element.

14. A coupling according to claim 2 wherein the first member comprises a central hub having uniformly spaced radially extending spokes, a respective pair of resilient elements connected to each spoke such that adjacent elements which are connected to consecutive spokes have a gap therebetween and the second member comprises a respective wedgeshaped component located in the gap between adjacent elements.

15. A coupling according to claim 14 wherein the elements are pre-loaded on insertion of the wedge-shaped components.

16. A coupling according to claim 14 or claim 15 wherein the elements on opposite sides of each wedge-shaped component are in communication with one another through a throttlnig restriction adapted to control the flow of damping fluid between the elements.

17. A coupling assembly according to claim 16 wherein each throttling restriction comprises a hole in the associated wedge-shaped component.

18. A coupling according to claim 2 wherein each element has a pair of opposed cavities, adjacent end plates of consecutive elements engage one another to connect the elements together and the end plates are adapted for connection to one of the first and second members and each element is adapted for connection to the other of the first and second members intermediate the associated cavities.

19. A coupling according to claim 18 wherein adjacent cavities in consecutive elements are in communication with one another through a throttling restriction in an intermediate plate located between the end plates.

20. A coupling according to claim 18 or claim 19 wherein connected end plates are adapted to receive an axially extending follower pin connected to one of the first and second members and each element has an axially extending sleeve intermediate the cavities adapted to receive a follower pin connected to the other of the first and second members.

21. A coupling according to any one of claims 19, 20 or 21 wherein the end plates are vulcanised onto rubber body portions of the elements.

22. A coupling according to claim 1 including a coupling disc having a plurality of openings extending parallel to the axis of the coupling and being uniformly spaced about the axis and in each of which a resilient element is received, each element having a pair of opposed pockets containing damping fluid and being connected to one of the first and second members intermediate the associated pockets and the portion of the disc between consecutive elements being connected to the other of the first and second members.

23. A coupling according to claim 1 including a coupling disc having a plurality of openings extending parallel to the axis of the coupling and being uniformly spaced about the axis and in each of which a resilient element is received, each element having a pair of opposed pockets containing damping fluid and the elements being connected alternately to the first and second members.

24. A coupling according to claim 22 or claim 23 wherein the adjacent pockets of consecutive elements are in communication with one another through a throttling restriction in the coupling disc.

25. A coupling according to claim 24 wherein the opposed pockets of each element are in communication with one another through a throttling restriction in the element.

26. A coupling according to any one of claims 22, 23, 24, or 25 wherein the elements receive axially extending follower pins adapted for connection to the first or second members.

27. A coupling according to claim 26 in which each follower pin is located in an inner sleeve of the associated element.

28. A coupling according to claim 27 in which each element has an outer sleeve and a sealing bead in the region of the pockets projects beyond the periphery of the outer sleeve to sealingly engage the openings in the disc.

29. A flexible coupling substantially as herein described with reference to Figures 1, 2 and 3 of the accompanying drawings.

30. A flexible coupling substantially as herein described with reference to Figures 4 and 5 of the accompanying drawings.

31. A flexible coupling substantially as herein described with reference to Figures 6 and 7 of the accompanying drawings.

32. A flexible coupling substantially as herein described with reference to Figures 8 and 9 of the accompanying drawings.

33. A flexible coupling substantially as herein described with reference to Figures 10 and 11 of the accompanying drawings.

34. A flexible coupling substantially as herein described with reference to Figures 12, 13 and 14 of the accompanying drawings.