CA1080989A - Elastic coupling for shafts - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE:

An elastic coupling, for shafts, comprising a series of radial spokes, every second one of which is connected to a hub element of a drive shaft, while the remaining spokes are connected, or adapted to be connected, to a hub element on a driven shaft.
The coupling also has rubber elements mounted between successive spokes, for the transfer of peripheral forces and filled with a damping medium, to be deformed resiliently when the said hub elements do not rotate in the same direction. The coupling is characterized in that the rubber elements, mounted on each side of a spoke, have variable-volume cavities communicating with each other through aperture means, in the spokes, which offer resistance to the flow of said damping medium.

Description

The present invention relates to an elastic coupling for shafts,coupling having a ring of radial spokes, every second one of the said spokes being connected to a hub element on a drive shaft, while the remaining spokes are connected, or adapted to be connected, to a hub element on a driven shaft. This coupling also has rubber elements arranged between the spokes which trans-fer peripheral forces, are filled with a damping medium,and are .
reslliently deformed if the said hub elements do not rotate in the same direction.
Couplings of this kind are adapted to absorb and resiliently equalize non-uniform torques as well as axial and angular displacements of the driving and driven shafts of two machines connected by the shaft coupling. In the case of a coupling of this kind disclosed in German Patent 1 450 191, in-dividual, prestressed rubber elements are vulcanized, between con- .
secutive spokes, to the surfaces thereof. These rubber elements are solid, and the damping properties produced b~ hy~sterisis of the rubber can provide adequate damping for the resonant vibra- . .
tions of the machines, in the peripheral direction, as long as the forces creating these torsional vibrations do not exceed the .
damping forces which the rubber elements can provide. If the said forces do exceed the damping forces, the amplitude o the vibra-. tions can become large enough to produce unacceptably rough :
running, or even destroy the coupling or other parts of the shafts. .
It is the purpose of the inven-tion to eliminate the above-mentioned disadvantage of the known coupling by providing additional damping means. .
'l'his purpose is achieved, accordiny to the invention ~.
as herein claimed, in the provision of an elastic coupling for ~:
connecting a driving shaft and a driven shaft, essentially comprising:
a plurality of members adapted to be connected alternately with the driv:ing and the driven shafts in such a manner as to be disposed .

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, outwardly about the axes of the shafts when so connected; elastic means disposed between and in-terconnectiny the members for trans-mitting peripheral forces, from the members connectable to the driving shaf-t to the said members connectable to the driven shaft,~
and for elastically deforming upon application of torsion to the respective members about the axis of the coupling; the elastic means at least partially defining deformable cavities between the respec-tive members which vary in volume upon elastic deformation o~ the elastic means; a damping liquid in the cavities, and restricted flow passage means between at least some of the cavities so as to provide hydraulic damping of torsional vibra-tions in the coupling.
According to a preferred embodiment, the members are disposed generally in a ring--like configuration and comprises spoke-like elements, whereby alternately one spoke-like element is connectable with the driving shaft and the next spoke-like element is connectable with the driven shaft. The elastic means, in this preferred embodiment, comprises rubber~like elements disposed between spokes and pre~stressed in compression so as to transmit substantial peripheral forces and to deform upon sufficient torsion 20 of the respective spoke-like elements about the axes of the shafts ;
to which they are connectable. In this embodiment, the rubber-like elements are disposed on either side of at least some of the spoke-like elements having variable volume cavities suah that -the cavity on one side of the spoke-like element comprises a drive cavity and the cavity on the other side of the spoke-like element comprises a driven cavity. The said drive and driven cavities of each of the at least some spoke-like elements are interconnected Yia the restricted flow passage formed by the restricted flow passage means.

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As a result of the resilent deformation of rubber elements, due to torsional vibration o~ the coupling, the volumes of the cavities in the rubber elements, which are preferably filled with a fluid, are increased on one side of the spo]ce and simultaneously reduced on the other side, This causes the fluid to move back and forth between the cavities through the apertuEeS
in the spoke. If the parts of the coupling are of suitable shape and size, the resistance to flow offered by the said apertures can produce an adequate hydraulic damping effect, thus ensuring that the machines run quietly and preventing any parts of the machines from being destroyed by resonant vibrations.
If the coupling consists of generally similar circular parts, all of the spokes, or only the spokes of one hub element may thus be apertured. The configuration of the rubber elements is preferably such that the peripheral forces of the coupling are absorbed by compression or thrust forces in the rubber elements.
In this connection, and for longer life, it is desirable for the rubber elements to be prestressed in the torque-free condition of the coupling, to an extent such that, under all operating condi-ZO tions, the forces in the rubber elements which transfer the peri~pheral forces undergo no change of sign.
The rubber elements and spokes may constitute an - integral coupling ring vulcanized in one operation, if the rubber ;
elements have cavities which can be produced in a corresponding process.
A coupling ring may consist of two half-coupling rings adapted to be fitted together axially and provided with re-cesses forming the cavities in the coupling. In order to achleve ; ~;
the above-mentioned prestressing of the rubber elements, a coupling i;;
ring rnade correspondingly larger may be reduced to the installed ~iameter, by suitable means, either before or during assembly of the coupling. The rubber elements and spokes of a hub element may ~2-.

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form a rubber-metal part, gaps being provided between the said rubber elements into which the spokes of the other hub ele~ent are inserted or insertable.
If a coupling is made of individually vulcanized rubber-metal parts, the cavities of which are produced by easily extruded tool parts, the rubber element may be held in prestress between the spokes and this may be assisted by the use of an adhesive. Uetal end plates may be vulcanized to the rubber elernents, and these may be glued to the spokes or may be pre-stressed to bear against the said spokes, with a rubber-film seal.
In this case, edges projecting from the end plates, and bent over before or during assembly, may engage in grooves in the spokes, thus forming the joint between the said end plates and spokes. The end plates may be provided with apertures and may form the spokes, in which the end plates of adjacent rubber elements may butt to-gether, may be connected together, and may have means for attach-ment to a hub element.
One preferred form of pressur-loaded rubber element is a cylindrical part through which a cavity, running peripherally, passçs. In this case, the walls of the rubber element, especially in the vicinity of the cavity, may be reinforced with peripheral-ly flexible inserts, for example helical springs, in order to prevent the rubber element from buckling outwardly as a result of peripheral or centrifugal forces. The latter may also be achieved by the provision of one or more radial supporting walls vulcanized to the rubber element. These may also form two separate cavities in a rubber element, each of which may exchange fluid with a cavity located on the other side of the adjacent spoke. If there ; i5 any danger of the rubber elements being pushed out too far by centrifugal forces, this may be counteracted by means o supporting plates vulcanized in position and connected together by tension members or enclosed by supporting rings not in contact with the ,' , : . .
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spokes. One or more rings enclosing the coupling may also serve to hold the spokes in position, in which case the supporting rings may be removed when the unit is complete or may remain as a permanent component of the coupling.
If consideration is given to two rubber elements in the form of pr~ssure-loaded circular parts, one of which bears against one side of a spoke, while the other bears against the other side of the spoke, then one of the rubber elements will be shortened peripherally by a suitably directed peripheral force -in the coupling, whereas the other rubber element is simultaneous-ly lengthened. The reduction in volume thus produced in one rubber element, which affects the amount of fluid exchanged, and thus the damping forces available, may be partly eliminated by transverse expansion of the rubber element in a manner which reduces the damping effect, whereas the increase in volume produced in the other rubber element may be partly eliminated by transverse con-traction of the cavity. In order to be abLe to obtain maximum fluid damping, it is desirable to provided means for equalizing effects. For example, the cavities may be provided with a cons-triction whereby the rubber element is increasingly restricted as the pressure loading increases; or any expansion or contraction of the cavity may be prevented by vulcanizing a helical spring, as previously mentioned, into the wall of the cavity. Even the radial supporting walls mentioned above have a weaking effect. -Projections from the spokes entering into the cavities may be used for mechanically limiting the approach of the spokes, or may in-crease the compression ratio of the cavities in the event of relative movement between the spokes of the two hub elements, if the said cavities are filled with a compressible damping agent.
One preferred design of thrust-loaded rubber element is a rubber disc adapted to be connected to an outer casing desi~ned to be connected to a spoke of one hub element, and vulcanized to .

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~ . , ~;, ' ,. , an inner casing designed to be connected to a spoke of the other hub element, the sai~ rubber disc having parallel or wedge shaPed end-faces. The said casing may have free end-faces-provide with seals which, in the finished coupling, lie prestressed against the spokes.
The spokes may be integral with a hub element or may be connected to a hub element by suitable means, for example by weld-ing. The spokes may be provided with sleeves or holes into which the pins of a hub element may be inserted. In this case, if the peripheral forces do not pass through the centres of the sleeves or holes, and therefore have a lever arm in relation thereto, precautions must be taken to prevent the spokes from rotating.
This may be achieved with peripheral rings or annular discs con-nected to the spokes, for example by welding.
The damping medium is preferably introduced after the coupling has been assembled, closable filling openings and vent openings, if necessary, beiny provided for this purpose at suit-.
able locations.
If all of the cavities in the rubber elements communi-cate with each other, only one filling opening is needed. In the serviceable coupling, the pressure of the damping medium may be equal to, higher than, or lower than atmospheric pressure. A pres-sure higher than atmospheric pressure is preferable, especially if a gaseous damping medium is used. Only a small portion of the hea* produced in the fluid by coupling vibration can escape to the outside through the rubber material, since the latter is a poor heat conductor. Instead, most of this heat must be dissipated through the metal parts of the coupling in the vicinity of the cavities, for example through the spokes or through any radial supporting plates that may be present. These parts may be provlded with enlarged surfaces releasing heat to the environment, and may be designed in a manner such as to promote cooling in the vicinity of the coupling in the manner of a blower.

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If rubber elements which absorb peripheral forces by compressive stresses are traversed by cylindrical cavities running ~ :
peripherally, and are supported by end plates or end pieces running approximately radially and connected to the spokes, agaist displacement, especially against displacement by centrifugal forces, there remain between the said end plates and end pieces, unsupported areas of the rubber elements which are arched out- -wardly by centrifugal force and must absorb the resulting additional inherent stresses. Above a specific limit rotary speed these rubber elements are no longer capable of withstanding the inherent stresses produced by centrifugal force.
In order that the shaft coupling may also be used at high speed, the arrangement may be such that annular rubber ele~
ments are inserted into apertures, running parallel with the axis of the shaft coupling, in a coupling disc, the said elements serving to accommodate drive pins inserted axially into the saicl ~` rubber elements and forming the spokes of one hub elemént, in which case the cavities, filled with pressure medium, are formed by opposing pockets in the said rubber elements and are respective-ly~defined by the inner casings of the apertures in the coupling disc.
The annular rubber elements may be connected directly wlth a drive bolt or with a rigid inner sleeve, preferably adhesi-vely, the said inner sleeve accommodating a drive pin. The rubber -elements may be made oversize in relation to the holes in the coupling disc and may be seated therein with compressive prestress, or they may be adhesively attached to a rigid sleeve adapted to be inserted into the said holes. The edges of the pockets in the rubber ~elements constituting the cavities may be provided with a sealing ~`
bead ensuring adequate sealing of the cavities in relation to the internal surfaces of the holes in the coupling disc.

` In a first type of this shaft coupling, with a rubber ' - . . "",:
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' . , ' ' , ' elements inserted into holes in the coupling disc, the walls of -the coupling disc located between the holes may form the spokes of the other hub element, in which case the coupling disc is to be provided with suitable means of connection to the driving or driven shaft. In a second type of this shaft coupling, the drive pins may form alternately the spokes of one and the other hub element, the sai~ coupling disc floating, in a manner known per se, between the said hub elements. With a given number o~ similar rubber elements in the same coupling disc, a shaft couplin~ of the first type can transfer twice the torque transferred by a shaft coupling of the second type. However,the rigidity (torque to angle of rotation) of a shaft coupling of the first type is ; much greater than that of a shaft coupling of the second type. A
shaft coupling of the second type is therefore better able to compensate for misalignment between:the driving and driven shafts.
i A floating coupling disc may be connected to the hub elements in known fashion by additional means and ma~ be held thereby, in order to prevent the coupling disc from coming loose at high r.p.m. as a result of imbalance.
The apertures controlling the damping forces may be located in the walls between the holes in the coupling disc and/or in the rubber elements in the wall between the two pockets. In the case of shaft couplings of the second type, which has a floating coupling disc, openings between the pockets of each rubber element are indispensable, whereas openings in the walls between the holes in the coupling disc are unnecessary and in-effective, since the cavities, separated by these walls, in two adjacent rubber elements undergo volume changes in the same direc-tion for reasons of symmetry. It is desirable to provide openings in the said walls both in the coupllng disc and in the rubber elements, in order to provide a through-connection between all cavities, both for filling them with the damping medium and for , ;.. . .. .

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vénting them. Suitable and, if necessary, closable channels may also be provided elsewherc:in the coupling disc and rubber elements for filling and venting.
A description of various embodiments of the invention now follows having reference to the appended drawings, wherein:
Fig. 1 is a cross section of a coupling having two hub elements provided with radial spokes and pressure-loaded rubber elements in between;
Fig. 2 is a longitudinal section through the coupling of Fig. l;
Fig.~3 is a cross-section through one of the rubber elements of the coupling of Fig. 1, prior to assembly;
Fig. 4 is a cross-section of a coupling in which six - rubber elements form with three spokes of a hub element, a rubber-.
metal part with gaps between the rubber elements, after assembly;
Fig. 5 is a part-view of the rubber-metal part of Fig.
4 prio~r to assembly;
~Fig. 6 is a cross-section of a rubber-metal part of a coupling ring consisting of three similar rubber-metal parts;
~ Fig. 7 shows a rubber-metal part according to Fig. 6 assembled to an adjacent rubber-metal part, in cross-section in ; the peripheral direction;
~ - Fig. 8 is a cross-section through a thrust-loaded `;~ rubber element prior to assembly;
Fig. 9 is a cross-section through the rubber element -~ according to Fig. 8 incorporated between two spokes;
.~ Fig. 10 is a cross-section of a shaft coupling of the first type having six rubber elements inserted into bores in a coupling disc and connected adhesively with drive pins;
Fig. 11 is a longitudinal section of the shaft coupling according to Fig. 10;
Fig. 12 is a cross-section of a rubber element adapted - ' .' ' -- . . . . . ,~ . . ..
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to be inserted, adhesively connected, to an annular casing onto bores in a coupling disc, in a longitudinal section conceived as lying in the peripheral direction;
Fig. 13 shows the rubber element according to Fig. 12 in cross-section;
Fig. 14 shows a shaft coupling of the second type in cross-section, in which the rubber elements inserted into the holes in a coupling disc are connected adhesively to an inner sleeve and an annular casing.
In the following description, it is to be understood that a first hub element is connected to one machine white a second hub element is connected to the other machine.
The coupling according to Figs. 1 and 2 comprises a first hub element 1, provided with a securing flange 15 and having four cranked spokes 11 to 14, and a second hub ele~Etent 2 provided <: with a securing flange 25 and having four cranked spokes 21 to 24.
Spokes 11 to 14 lie between spokes 21 to 24 and are attached to stub shaft 16 integral with flange 15 . Spokes 21 to 24, on the other hand are attached to stub shaft 26 integral with flanged 25, 20 the above attachments being by welding. ~leld between successive pairs of spokes 11 and 21, 21 and 12, etc. is one of eight rubber elements 31 to 38 comprising cavities 41 to 48 and 41' to 48', divlded by supporting walls 51 to 58 and filled with fluid. A5 shown in Fig. 2, rubber elements 31 to 38 have, in the torque-free condition shown in the said figure, a square cross-section 38' with rounded corners, and cavities 41 to 48 and 41' and 48' are of cir~
cular cross-section 48". Prior to assembly, rubi:er elements 31 to 38 are identical to rubber element 3G shown in Fi 7. 3 which forms, with supporting disc 56 and end plates 59, 60, a vulcanized rubber-3a metal part, the peripheral length of which is greater than thelength once the rubber element is assembled. The latter is provided with cavities 46 and 46', the shape of which accordin~ly difEers , _ g _ , , ': , '' ~, , , . ~ :
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from that of the cavities in Fig. 1. The outer faces of end plates 59,60 have rubber films and protruding edges 63, 64 on all sides. In the longitudinal direction, spokes 11 to 14 and 21 to 24 have grooves 71,72. In the radial direction, the same spokes have grooves similar to groove 71, not shown, in which the suitably bent edges 63,64 of end plates 59,60 engage in such a manner that ; the end plates 59,60 of the rubber elements 31 to 38 are pressed firmly and closely against the end faces of the spokes 11 to 14 an~ 21 to 24 and are thus secured against displacement. Spokes 11 to 14 and 21 to 24 each have a choke aperture 91 to 98 consti-tuting the apertures in the spokes within the meaning of claim 1.
Spoke 24 is provided with a closable feel opening 65, whence a - duct 66 leads to choke aperture 98. Support plates 51 to 5~ may be provided with apertures 66, the purpose of which is merely to connect all of the cavities together so that they can be filled with fluid from a single filler opening 65. Rubber eIement 34 may, if required, have a helical spring 67 which is vulcanized in and which reinforces the walls of cavities 44, 44'. The hub 23 may have a freely movable valve element 68, the rise of which is res-20 tricted, and may be provided with a choke aperture 96, which can -~
compensate for high-frequency vibrations of small amplitude with-out any exchange of fluid between cavities 45' and 46, in order to prevent thé transfer, from one machine to the other, of high-frequency vibrations, especially acoustic vibrations. There is shown, in rubber element 35, a possible constriction 69 and a constriction 70 of the cavity 45 which is still further constricted with increasing peripheral pressure loading.
When hub element 1 rotates in relation to hub element

2, assumed to be stationary, in a clockwise direction, spokes 11 t 12,13,14 move closer spokes 21,22t23,24 and, at the same time, move away from spokes 24,21,22,23, respectively thus reducing the volume of cavities 41 and 41', 4~ and 43', 45 and 45', and 47 and .
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47', while increasing the volume of cavities 48 and 48', ~2 and 42', ' 44 and 44', and 46 and 46'. This brings about a trans~er o~ fluid between the cavities adjacent each spoke, through choke apertures 91 to 98, in the appropriate direction, for instance from cavity 41, through choke aperture 91, into cavity 48', with an over-pressure building up in cavity 41 due to the flow resistance offer-ed by the said choke aperture. For reasons of symmetry, the same over-pressure builds up in cavity 41' which is separated from cavity 41 by supporting wall 51, the said cavity 41' emptying into 10 cavity~ 42, and it is immaterial whether supporting wall 51 has an ~' aperture 66 or not. The steps described above as taking place in ~, cavities 41,48' and 41',42 also take place in all of the cavities.
They also take place in reverse direction if the hub element 1 ', ' '~ rotates anti-clockwise in relation to hub element 2.
In the coupling shown Fig. 4, there is a first hub ' element 101 consisting of a hub ring 117 provided with a bore 115 :: .
and a keyway 116, and of three spokes 111 to 113 extending radial-ly from,the hub ring 117. ' Vulcanized to the lateral surfaces of spokes 111 to , ~ , 113 are rubber elements 131, 132; 133,13~; and 135,136. Free end-surfaces 131' to 136' bear firmly and closely, under compressive : ' prestress, against the lateral faces o~ three wedge-shaped spokes 121 to 123 which have through passages 124 to 126 into which drive pins of a second hub element, not shown, are inserted. Rubber elements 131 to 136 comprise cavities 141 to 146 divided from each ~, other by spokes 111 to 113. Spokes 121 to 123 are provided with ,~
choke apertures L91 to 193 which open into the respective adjacent ~' cavities and control the damping forces. Spokes 121 to 123 are also provided, on both sides, with projecting edges 151 to 156, ' ; .. .
defining bones which receive the ends of rubber elements 131 to 136 '' and secure them against displacement. A tension strip, not shown, , , which surrounds the coupling and which can be removed as soon as ' ~' -the drive pins of the second hub element are inserted into bores 124 to 126, keeps spokes 121 to 123 in the position indicated.
Fig. 5 shows the shape of the rubber elements 131 to 132, and of the cavities 141 and 142, prior to assembly. It may be seen that hub elements 101 and rubber elements 131 to 136, according to Fig. 4, form, before the coupling is completed co-herent rubber-metal parts having gaps 137 between successive rubber elements.
The rubber-metal part illustrated in Fig. 6 comprises, connected adhesively together, a box-shaped metal end part 259 formed with holes 275, a rubber element 231 having a cavity 241, a spoke 251 forming a sleeve 254, a rubber element 232 having a cavity 242, and a box-shaped metal end part 260 having holes 276.
End part 259 has side walls 258 which enclose the rubber element 231, and a bottom wall 257 the outer surface of which is formed with a sealing lip 256. End part 260 has a bottom wall 261 vul-canized to the rubber element 232; the surface of the said bottom wall, facing the rubber element, being provided with a sealing lip 262 and outwardly-directed side walls 263~ End part 259 is smaller than end part 260 and is adapted to be inserted into end part 260 of an adjacent rubber-metal part. An intermediate plate 264, having a choke aperture 291, may be placed between bottom wall 257 and bottom wall 261.
As illustrated in Fig. 7, a drive pin 265, passing through cavity 241, may be inserted through holes 275 and 276' and may be secured by a nut 266, the said pin connecting end parts 259 and 260' together. Sealing lips 256 and 262' seal cavities 241 and 242' from the outside, drive pin 265 being sealed by beads 267,268 in the holes 275. Three of the rubber-metal parts accord-ing to Fig. 6, assembled in this manner form a coupling ring. A
drive pin of a first three-armed hub element, not shown, may be inserted into each sleeve 254 of the said rubber-metal parts, and three drive pins 265 may be fitted to a second hub element, not shown. The pitch circles of sleeves 254 and of holes 275 and 276 of the rubber-metal part, shown uncompressed, are larger than the corresponding pitch circles of the hub elements. In assemhling the coupling rings to the hub elements, the diameter of the latter may be reduced, for example by means of a tensioning strip, until the said pitch circles coincide, whereupon the drive pins may be inserted, thus providing permanent prestressing of rubber elements 231 and 232 of all three rubber-metal parts.
Shown in Fig. 8~ is a vulcanized rubber element 331 which consists of an outer metal sleeve 357, an inner metal sleeve 358, and a rubber ring 356 having in cross-section, the shape of - a parallelogram and a through-cavity 341. Sleeve 357 has a rubber-coated flange 359, while sleeve 358 has a rubber-coated flange 360 running parallel with flange 359.
In the assembled condition shown in Fig. 9, rubber element 331, the flanges of which are still parallel, is clamped between two wedge-shaped spokes 311, 321. Rubber ring 356 has now assumed a rectangular cross-section Rubber element 331 lies close ;
to the lateral surfaces of spokes 311,321 and is prevented from moving laterally by projectin~ edges 361,362 thereo. Spoke 321 ~ is provided with a choke aperture 391 which connects cavity 3~1 ; with the cavity in adjacent, mirror-image rubber element 332.
Spoke 331 has an eye 363 for the accommodation of the drive pin of a first hub element, and spoke 321 has a bore 36~ for the ac-commodation of a drive pin of a second hub element Spoke 311, a second spoke 312, and all other spokes on the first hub element are joined securely together by means of an annular member 365, for example by welding. Spoke 321 and all other spokes on the second hub element have no contact with annular disc 365 and are joined securely together by means of an annular disc, not shown, lying in front of the plane of the drawing.

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The shaft coupling according to Figs. 10 and 11 is formed of a coupling disc 407 provided with six holes 408 into which are inserted six rubber elements 401 to 406. Drive pins 410, connected adhesively and directly to the said rubber elements, are secured to a flange 414 of a hub element 415 having a bore 413 for the insertion of a drive shaft, not shown. A hub element 416, having a bore 418 for the accommodation of a driven shaft, is connected, thrugh a flange 417, and by means of a drive pin 411 secured to the said flange, to coupling disc 407 through which it passes. Wall 412 between the holes 408, in coupling disc 407, form the spokes of hub element 416. A central bore 419 in coupling disc 407 may also serve for the direct accommodation of the driving o~ driven shaft, in which case the coupling disc is also the hub element and a separate hub element 416 may be dispensed with.
Rubber elements 401 to 406 may be oversize in relation to holes 408, so that, when inserted therein, they are prestressed -~
; in compressionin relation to the surfaces of holes 408. The said elements may also be connected adhesively to the surfaces of holes 408. As illustrated by rubber element 401, rubber elements 401 to 406 are provided, in the peripheral direction of coupling disc 407 and on both sides of drive pin 410, with pockets 421,422 separated from each other by rubber webs 425,426. Pockets 421,422 are bound - laterally by rubber walls 423,424. In this respect, Fig. 10 shows the rubber elements 401 to 403 as taken along line I-I in Fig. 11, passing through the pockets 421,422, while the rubber elements 404 to 406 are taken along line II-II in Fig. 11, passing through the rubber wall 423. Peripheral forces are transferred, with resilient deformation of rubber elements 401 to 406, substantially by normal stresses in the viainity of rubber walls 423,424, by drive pins 410, to coupling disc 407. To a lesser extent, the thrust stresses between rubber elements 401 to 406 and the surfaces of holes 408 ~v~

also contribute to the transfer of peripheral forces.
Reference numberals 421,422 identify pockets 421 and 422 as well as cavities 921 and 422 in rubber element 401, the said cavities being separated by rubber webs 425,426, defined by the surfaces of holes 408, and filled with a damping medium.
Apertures 427,428 in rubber webs 425,426 connect cavities 421,422.
A channel aperture 429 in wall 412 also joins cavity 421 with cavity 422' in the next rubber element 402. Ducts 430,431 and 432, shown in dotted lines in Fig. 10, are used to fill and vent ~-the cavities 421,422. In the event of torsional vibration of hub element 415 in relation to hub element 416, cavities 421, 421' etc of all rubber elements 401 to 406 are alternately reduced and ;~
increased in size, while cavities 422,422' of all ruber elements 401 to 406 are inversely increased and reduced in size, so that exchange of damping fluid takes place between these cavities against the flow resistance offered by respective apertures 427, 428, 429. The apertures may be of a size and shape such that vibrations, especially those of large amplitude, are effectively damped. Moreover, the said apertures may also be provided with means for controlling the flow resistance as a function of flow velocity or other factors.
The rubber element shown in Figs. 12 and 13 is a ., . " .. .
rubber-metal part and consists of an inner sleeve 440, an annular casing 441, and an annular rubber part g44 adhesively secured thereto. Opposing pockets 445,446 are recessed into annular casing 441 in the vicinity of rectangular incisions 442,443. The outer edges of pockets 445,446 are defined by sealing beads 447,448 projecting past the outer periphery of casing 441, and are separat-ed b~ rubber webs 449,450. A conical channel aperture 452, re-inforced by means of a rigid tube 451, connects pockets 445 and 446 together.

In the case of the shaft coupling shown in Fig. 14, ' . ' .

a coupling disc 470 is provided with the same number and arrange-ment of rubber elements as coupling disc 407 of Fig. 10. Bores 481 in this coupling disc 470 accommodate rubber elements 482 having pockets 494 of the type shown in the rubber elements of Figs. 12 and 13, or a rubber element 483 having pockets 495 sub-stantially similar to rubber element 482, but differing therefrom in that it comprises not on~ annular casing 489, but two separate annular casings 485,486, so that the reinforcement provided by annular casing 484, in rubber element 482, is lacking. In rubber elements 482, drive pins 482 are inserted from the right, while in rubber elements 483, drive pins 488 are inserted from the left.
Parts 489 and 390 of drive pins 487 extending to the right, are adapted to be connected to a hub element 496, shown in dotted lines, of a driving shaft, for example. Parts 491, 492 of drive pins 488, extending to the left, are adapted to be connected to a hub element 497, shown in dotted lines, of the driven shaft.
Apertures 498,499 in rubber elements 482,483 control the damping forces produced by changes in volume of the cavities formed by pockets 494,495. Coupling disc 470 floats between hub elements ~0 496,497.

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Claims (24)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An elastic coupling for connecting a driving shaft and a driven shaft, comprising: a plurality of members adapted to be connected alternately with the driving and the driven shafts in a manner to be disposed outwardly about the axes of the shafts when so connected; elastic means disposed between and interconnecting said members for transmitting peri-pheral forces, from the said members connectable to the driving shaft to the said members connectable to the driven shaft, and for elastically deforming upon application of torsion to the respective members about the axis of the coupling; said elastic means at least partially defining deformable cavities between said respective members which vary in volume upon elastic defor-mation of said elastic means; a damping liquid in said cavities, and restricted flow passage means between at least some of said cavities so as to provide hydraulic damping of torsional vibrations in said coupling.

2. A coupling according to claim 1, wherein said members are disposed generally in a ring-like configuration and comprise spoke-like elements, whereby alternately one spoke-like element is connectable with the driving shaft and the next spoke-like element is connectable with the driven shaft, said elastic means comprising rubber-like elements disposed between spokes and pre-stressed in compression so as to transmit substantial peripheral forces and to deform upon sufficient torsion of the respective spoke-like elements about the axes of the shafts to which they are connectable, the rubber-like elements disposed on either side of at least some of the spoke-like elements having variable volume cavities such that the cavity on one side of a spoke-like element comprises a drive cavity and the cavity on the other side of the spoke-like element comprises a driven cavity, the drive and driven cavities of each of said at least some spoke-like elements being interconnected via a restricted flow passage of said restricted flow passage means.

3. A coupling according to claim 2, wherein said at least some of said spoke-like elements are provided with said flow passage means joining said drive and driven cavities to form therewith a closed circuit for said damping liquid.

4. A coupling according to claim 2, wherein only the spoke-like elements connectable with one of said shafts are provided with said flow passage means joining said cavities to form a closed circuit for said damping liquid.

5. A coupling according to one of claims 2, 3 or 4, wherein the rubber-like elements form, with the spoke-like members a vulcanized coupling ring.

6. A coupling according to claims 2, 3 or 4, wherein the rubber-like elements corresponding to one of said shafts form, with the spokes of said one shaft, a rubber-metal part defining gaps between rubber elements into which the spokes corresponding to the other shaft are inserted.

7. A coupling according to claim 2, wherein metal end-plates are vulcanized onto the rubber-like elements.

8. A coupling according to claim 7, wherein said end plates have bent edges engaging into grooves in said spokes for securement thereto.

9. A coupling according to claim 7, wherein said end plates form said spokes and are provided with means for mounting onto hub elements for connection onto said shafts.

10. A coupling according to claim 9, wherein each coupling ring is formed by rubber-metal parts comprising, consecutively, a box-shaped end-part, a first rubber-like element, a spoke provided with a means attachment to a hub element, a second rubber-like element and a box-shaped end-part;
said end-parts of adjacent rubber-metal parts being adapted to be pushed one into the other and comprising bores for the accommo-dation of a drive pin of the other hub element; and wherein an intermediate plate, provided with a choke aperture, is held between the said end-parts.

11. A coupling according to claim 2, 3 or 4, wherein said rubber-like elements are in the form of rings and said cavities are cylindrical and run peripherally thereof.

12. A coupling according to claims 2, 3 or 4, wherein the walls of said cavities are reinforced by inserts which yield peripherally.

13. A coupling according to claim 2, wherein each rubber-like element has a central radial supporting wall.

14. A coupling according to claim 13, wherein said cavities are separated from each other by said supporting walls.

15. A coupling according to claims 2, 3 or 4, wherein one of said cavities of one of said rubber-like elements is pre-constructed and is further constricted in the direction of pressure as the load on said one of said rubber like elements increases.

16. A coupling according to claims 2, 3 or 4, wherein a valve element, the rise of which is restricted and which is provided with a choke aperture, is arranged to move freely in an aperture in one of said spoke-like elements.

17. A shaft coupling according to claim 2, wherein said rubber-like elements are annular and inserted into bores running parallel with the axis of said coupling in a coupling disc and serve to accommodate drive pins into said rubber-like elements and which form the spokes corresponding to one of said shafts, the cavities, filled with pressure liquid, being formed by pockets facing each other in the rubber-like elements and being defined by the internal surfaces of the bores in said coupling disc.

18. A shaft coupling according to claim 17, wherein the walls between said bores in the coupling disc form the spokes corresponding to a shaft.

19. A shaft coupling according to claim 17, wherein the drive pins form alternately the spokes of one and the other shafts, the coupling disc being arranged to float between the said shafts.

20. A shaft coupling according to claim 17, wherein the cavities in adjacent rubber-like elements communicate with each other through apertures in the coupling disc which form said flow restricted passage means.

21. A shaft coupling according to claim 17, wherein the cavities in a rubber element are in communication with each other through apertures forming said flow restricted passage means.

22. A shaft coupling according to claim 17, wherein the rubber elements are connected adhesively and directly to the drive pins and connected adhesively with an inner sleeve serving to accommodate the drive pins.

23. A shaft coupling according to claims 17, wherein the rubber elements are connected adhesively to annular casings.

24. A shaft coupling according to claim 23, wherein the rubber element has sealing beads projecting from the outer peripheries of the annular casings in the vicinity of the pockets.