GB2094936A - Improvements relating to shaft couplings - Google Patents

Abstract

A shaft coupling comprises a combination of two parallel- connected resilient ring elements 3, 4 and, disposed thereafter, at least one resilient ring element 5. Metal members 3b, 4b, 5b serving to connect the ring elements to the rigid parts of the coupling are secured to the ring elements 3, 4, 5, by vulcanisation. The two ring elements 3, 4 are disposed in axial adjacent relationship to one another around a hub 1 of a first coupling part and have their outer end faces secured to the hub 1 and their inner end faces to an annular disc 15 bearing radially on the hub 1. Also, the outer ring element 5 has one end face secured to a projecting edge portion of the annular disc 15 and its other end face secured to the second part 2 of the coupling. Advantageously, the ring elements 3, 4, 5 with the metal members secured to them are formed from at least two, preferably eight, independent ring segments. <IMAGE>

Description

SPECIFICATION Improvements relating to shaft couplings This invention relates to an extra-resilient shaft coupling in which the resilient intermediate member interconnecting the two parts of the coupling comprises a combination of concentric ring elements made of rubber or other resilient material, there being at least two parallelconnected ring elements and, disposed thereafter, at least one ring element, together with metal members which serve to connect the ring elements to the rigid coupling parts being secured to the ring elements, prefererably by vulcanisation.

Shaft couplings of the kind described, i.e., having a combination of a number of concentric rubber rings transmitting the torque in a parallel and series arrangement, are known. To interconnect and secure the closed rubber rings, metal members are vulcanised on to them. One known shaft coupling comprises two parallelconnected inner rubber rings and two parallelconnected outer rubber rings, the resulting pairs being disposed in series with one another. The inner rings transmit the torque by rotary shear while the outer rubber rings are arranged to experience torsion.

Using a combination consisting of a number of concentric rubber rings leads to a shaft coupling having overall satisfactory resilient properties.

However, a disadvantage is that the outer rubber rings and the associated securing members are connected freely to the inner rubber rings and do not bear unmovingly in the radial direction on one of the two coupling parts. In this kind of construction, manufacturing tolerances and/or static strokes of the rubber members arising from the weight loading may cause eccentric displacements of the unsupported masses. The resulting dynamic imbalance may become excessive when the coupling is rotating. In any case, dynamic imbalance is an additional stress on shafts and bearings, and makes for noisy running.

Also, shaft couplings having a number of concentric rubber rings require relatively large fitting spaces at the place of use of the replacement of damaged rubber rings, in order that the closed rubber rings can be removed and replaced vertically in the space between the two rigid parts of the coupling. However, since shaft couplings are usually required to be of very reduced overall axial length, it is a nuisance to have to arrange for special free spaces just for replacement of the rubber rings. Another factor complicating the replacement of closed rubber rings is that the necessary securing means, such as screws or the like, inside the rubber rings are usually difficult to get at.

It is an object of the invention to minimise these disadvantages and provide a shaft coupling having a combination of concentric resilient ring elements such that the outer ring elements have radial support, without this feature impairing the general resilience of the coupling, and desirably such that the ring elements are also readily replaceable without special spaces having to be arranged for the replacement operation. Also, the shaft coupling is required to be not only torsionally resilient but also to have considerable displaceability to cope with radial, axial and angular offsets between the shafts connected by the coupling.

In accordance with the invention, there is provided a resilient shaft coupling in the form of a resilient intermediate member interconnecting the two parts of the coupling comprising a combination of concentric ring elements made of rubber or a like resilient material, there being at least two parallel-connected ring elements and, disposed thereafter, at least one further ring element, metal members which serve to connect the ring elements to the rigid coupling parts being secured to the ring elements, preferably by vulcanisation, and wherein two ring elements which are disposed in axially adjacent relationship to ome another around a hub of a first coupling part, have their outer end faces secured to the hub and their inner end faces secured to an annular disc bearing radially on the hub, and an outer ring element has one end face secured to a projecting edge of the annular disc and its other end face secured to the second part of the coupling.

The annular disc disposed between the two inner ring elements and supported radially on the hub serves not only to support the inner ring elements but also to support the output side of the outer ring element. Similarly, two outer ring elements can be provided, in which event they are connected to the centre annular disc on opposite sides, like the inner ring elements.

Preferably, the ring elements with the metal members secured to them are formed from at least two, preferably eight, independent ring segments. In practice it is convenient to provide more than two independent ring segments, the number depending mainly upon the size of the shaft coupling. In the case of very large shaft couplings it may be convenient for the resilient ring elements to comprise eight or more independent ring segments. This feature not only greatly simplifies the assembly of such a shaft coupling and replacement operations when in use but also saves considerable costs in the production of resilient ring elements for large and extra-large couplings.

Shaft couplings to deal with substantial drive powers are required only in special cases and can, correspondingly, be purpose-made. The production of closed resilient ring elements for extra-large couplings entails corresponding production risks, with the result that the total costs of producing such couplings are difficult to calculate. Previously, a number of individual couplings have been connected in parallel with one another to transmit very substantial powers; unfortunately, there are limits to coupling arrangements of this kind due to the conflict between available space and the necessary overall axial length. The use of ring elements embodied by a number of independent ring segments is a simple way out of these difficulties.

Advantageously, the metal securing members are made of spring steel. This feature further increases the axial displaceability afforded by the resilient ring element.

Conveniently, the metal members extend radially beyond the ring elements in the securing zones, their projecting edge portions being disposed in planes perpendicular to the axis of rotation. As a rule, screws are used to secure the ring elements releasably and to one another.

Conveniently, therefore, the connection edge portions of the metal members have partially axially projecting thickenings of the places where securing screws wiil be used.

Preferably, the metal member which is associated with the outer ring element and which serves to connect the same to the inner ring elements has on its inner edge peripherally extending axially-projecting integrai thickenings to which both the connection edge portions of the metal members of the inner ring elements and also the annular disc are connected, e.g. by means of bolts screwed into axially-parallel tapped bores in the thickenings.

The annular disc providing radial support for the resilient ring elements may bear on the hub by way of a rotation-transmitting bearing movable axially in both directions. This feature does not impair the axial and rotational resilience of the resilient ring elements.

The shaft coupling in accordance with the invention is also of use for forming a double coupling wherein two individual couplings are arranged axially and consecutively in mirror-image relationship with their outer ring elements near one another and rigidly secured to a flanged ring bearing radially, but with provision for axial movement, on the hub of one of the individual couplings. The outer resilient ring elements of both individual couplings have radial support in this arrangement. However, since the radial support acts on only one of the two individual couplings, the same are radially displaceable relatively to one another. In a double coupling of this kind, the satisfactory radial, axial and angular displaceability is retained and the torsional resilience is doubled.

The invention may be performed in various ways and a preferred embodiment thereof will now be described with reference to the accompanying drawings, in which: Figure 1 is an axial section through a shaft coupling of the invention having three concentric multi-element resilient ring elements; Figure 2 is an end view onto the outer part of the coupling of Figure 1, with parts of the interior broken away; and Figure 3 shows an arrangement of a double coupling in a half axial section in relation to the common axis of rotation.

The shaft coupling shown by way of example in the drawings is employed to interconnect two parts 1, 2 resiliently by means of two inner parallel-connected resilient ring elements 3, 4 and one outer resilient ring element 5 which is disposed in series with the ring elements 3, 4. As Figure 2 shows, each individual element 3 to 5 is subdivided into eight independent ring segments.

The angle dimensioning of the ring segments 3a, 4a of the inner ring elements 3, 4 respectively, is the same as the ring segments 5a of the outer ring element 5. Also, the segments 5a are so arranged that their radial centre-lines coincide with the radial centre-iines of the associated inner ring segments 3a and 4a. In other words, continuous narrow radial gaps 6 are present between adjacent groups of inner and outer ring segments 3a, 4a and 5a. This kind of registering arrangement for the individual ring segments is advantageous for fitting and removing such segments. There is no need to emphasise that a staggered arrangement is equally possible.

Operation of the shaft coupling is not affected by the arrangement of the ring segments.

The resilient ring elements are of trapezoidal cross-section, the longer parallel side always being on the outside. Since the torque loading is greater in the outer zones than in the inner zones, this shaping helps to save material and weight. On their end faces the ring segments are enclosed by plane metal members 3b, 4b, Sb whose radial side edges are flush with the radial side surfaces of the inner segments. The resilient members are made of a resilient material such as rubber or the like and the outer metal members are secured to the inner resilient members, preferably by vulcanisation.

In the case of the inner ring segments 3a, 4a the metal members 3b, 4b have, on the outside, edge portions 3c, 4c respectively which project radially beyond the resilient member and which are so bent relatively to the adjacent portions of the metal members as to extend in planes perpendicular to the axis of rotation. To secure the ring segments 3a to the coupling part 1 , which is an inner hub, a connecting ring 7 is so mounted on the hub end face as to co-rotate with the hub and is secured thereto by connecting means (not shown), such as screws. The outer connection edge portions 3c of the segments 3a are flush with the connecting ring 7. The edge portion 3c is rigidly connected to the ring 7 by means of bolts 8 on which nuts 9 are secured, the bolts 8 being mounted in registering bores in the two elements 3c and 7. In the embodiment shown each ring segment 3a has three bolts 8 which are equidistant from one another.

A similar form of securing is provided for the ring segments 4a on the opposite end face of the hub 1, a connecting disc 10 being secured to the hub end face by means of bolts 11. Additional securing can be provided by pins introduced by frictional engagement in axially parallel bores 13.

As Figure 1 shows, a continuous spacer ring 14 is disposed between the connection edge portion 4c and the connection disc 10. Edge portion 4c is clamped to the disc 10 by means of bolts 8 associated with nuts 9 and received in registering bores in the elements thus interconnected.

On the inner end faces of the segments 3a, 4a, projecting edge portions 3d, 4d respectively engage, on opposite sides, with an annular disc 1 5 supported radially on the hub 1 through the agency of a rotation-transmitting bearing permitting axial movement in both directions.

Accordingly, two flanged rings 1 6 are rigidly secured to the disc 1 5 and are so mounted on a collar 17 rigidly secured to the hub 1 as to be rotatable and axially movable.

The ring segments 5a of the outer ring element are also enclosed by metal members Sb. The members Sb adjacent the coupling part 2 have, just like the inner ring segments, outwardly projecting connection edge portions 5c. Securing is by means of through-bolts 18 and nuts 19.

On its axially opposite end face the metal member 5b has an axially projecting thickening 5d. The same forms a unitary component with the metal member. Disposed in the thickening are axially parallel tapped bores adapted to receive bolts 20. Each bolt 20 extends through registering bores in the edge portions 3d, 4d and the disc 1 5, and serves to fasten all of the latter elements to the outer ring segment 5a. Three securing screws 20 are provided on each individual ring segment 5a. In the peripheral direction, and not only near a ring segment but also at transitions between segments, all the screws 20 are equidistant from one another.

Conveniently, the metal members of the ring segments are made of spring steel, thus further improving the axial resilience of the shaft coupling.

Since the connections with the rigid parts of the coupling are by way of the end faces of the ring segments, both the inner ring segments and also the outer ring segments are placed in torsion by the torque. The rotational resilience of the coupling is increased by the series connection of the inner ring segments with the outer ring segments. The subdivision of the resilient intermediate members into discrete independent ring segments facilitates replacement of the ring elements. One considerable advantage is that the machines interconnected by the shaft coupling do not have to be moved relatively to one another axially to dismantle the resilient intermediate members. Also, in contrast to what happens with the known shaft couplings having closed resilient ring elements, there is no need to make additional space available for fitting and removing the resilient intermediate members.Also, the segmental construction helps to reduce the costs of shaft couplings for extra-heavy duties, e.g. for torques of up to 2,000 kNm.

The fact that the radial support disc 1 5 is rotatably mounted on the hub 1 helps to increase the total damping of the coupling during relative movements caused by loading of the coupling, to an extent dependent upon the losses caused by friction between the contacting surfaces.

Figure 3 shows a double coupling comprising two individual couplings of the kind hereinbefore described arranged in axially consecutive relationship. Except for the outer securing of the outer ring segments, the individual couplings are identical to the coupling shown in Figures 1 and 2.

As Figure 3 shows, the individual couplings are arranged in mirror image relationship with opposite OL er ring segmen.~ 5a disposed axially adjacent one another. The outer ring segments 5a are interconnected by means of bridging ring 21 having a radially inwardly extending flange ring 22. The projecting connection edge portions Sc of the ring segments 5a are disposed on opposite end faces of the ring 21. Bolts 23 are mounted in registering bores in the elements to be interconnected, and have at their screwthreaded end a clamping nut 24. The ring 22 bears radially by way of its cylindrical inside surface on the spacer ring 14 of the individual coupling which is on the right in Figure 3. The ring 27. can move axially in both directions relatively to the spacer ring 14 and therefore relatively to the hub part of the coupling on the right in Figure 3, thus ensuring that the individual couplings can move axially relatively to one another -- i.e., are dispiaceable.

The radial support for the outer ring segments which is provided for one of the two individual couplings also serves as a radial support for the ring segments 5a of the other individual coupling.

Claims (9)

1. A resilient shaft coupling in the form of a resilient intermediate member interconnecting the two parts of the coupling comprising a combination of concentric ring elements made of rubber or a like resilient material, there being at least two parallel-connected ring elements and, disposed thereafter, at least one further ring element, metal members which serve to connect the ring elements to the rigid coupling parts being secured to the ring elements, preferably by vulcanisation, and wherein two ring elements which are disposed in axially adjacent relationship to one another around a hub of a first coupling part, have their outer end faces secured to the hub and their inner end faces secured to an annular disc bearing radially on the hub, and an outer ring element has one end face secured to a projecting edge of the annular disc and its other end face secured to the second part of the coupling.

2. A coupling according to claim 1, wherein the ring elements with the metal members secured to them are formed from at least two, preferably eight, independent ring segments.

3. A coupling according to claim 1 or claim 2, wherein the metal securing members are made of spring steel.

4. A coupling according to any one of claims 1 to 3, wherein the metal members extend radially beyond the ring elements in the securing zones and their projecting edge portions are disposed in planes perpendicular to the axis of rotation.

5. A coupling according to any one of claims 1 to 4, wherein the metal members have partial axially-projecting thickenings on the connecting edge portions.

6. A coupling according to any one of claims 1 to 4, wherein the metal member which is associated with the outer ring element and which serves to connect the same to the inner ring elements has on its inner edge peripherally extending axially-projecting thickenings to which both the connection edge portions of the metal members of the inner ring elements and also the annular disc are connected, preferably by bolts screwed into axially parallel tapped bores in the thickenings.

7. A coupling according to any one of claims 1 to 6, wherein the annular disc bears on the hub by way of an axially movable rotation-transmitting bearing.

8. A double coupling comprising two individual couplings according to any one of claims 1 to 7 arranged axially and consecutively in mirror image relationship with their outer ring elements near one another and rigidly secured to a bridging ring bearing radially, but with provision for axial movement, on the hub of one of the individual couplings.

9. A shaft coupling substantially as herein described with reference to the accompanying drawings.