GB2083168A - Flexible shaft couplings - Google Patents

Abstract

A shaft coupling has a hub part 1 of one half of the coupling and an outer ring 2 concentrically surrounding the hub part 1 and associated with the other half of the coupling. These hub parts are connected by two identical reinforced elastic annular discs 3, 4 which are arranged in laterally inverted relationship and which are curved axially outwards to form a cavity between their edges clamped to the hub part 1 and the outer ring 2. The outwardly curved parts 18, 19 are respectively braced relative to one another by means of annular elastic elements 20, 21 whose inner end faces carry friction rings 30, 31. A support ring 22 is connected to the hub part 1 so as to rotate therewith and carries brake rings 25, 26. The mutual contact surfaces of the annular elements 20,21 and of the brake rings 25, 26 are in the form of friction surfaces. <IMAGE>

Description

SPECIFICATION Improvements relating to flexible shaft couplings This invention relates to a flexible shaft coupling in which the hub part of one half of the coupling and an outer ring concentrically surrounding the hub part and associated with the other half of the coupling are connected by two identical elastic annular discs which are arranged in laterally inverted relationship and which are curved axially outwards to form a cavity between their edges clamped to the hub part and the outer ring.

In a known shaft coupling of this kind, damping is determined practically only by the material damping, which is usually relatively small. However, there are conditions of use, for example in multi-engine installations feeding a common reduction gear, where greater damping is required than is possible with a conventional rubber fabric coupling.

To achieve greater damping, it is known basically to use additional dampers connected in parallel.

These steps are not only expensive, but also greatly restrict the radial and axial movement of a coupling because ofthestructural features of the dampers suitable for the purpose. The moment of inertia on the drive side is also increased, and this is a disadvantage in modern diesel engine installations, because crankshaft stresses automatically increase as a result.

It is an object of this invention to provide a flexible shaft coupling of this kind utilizing additional damping based on mechanical friction forces which will come into operation in addition to the normal material damping, without substantially limiting the radial and axial ability of the coupling to move and without substantially increasing the external moment of inertia of the coupling.

Accordingly, this invention provides a flexible shaft coupling comprising a hub part of one half of the coupling, an outer ring concentrically surrounding the hub part and associated with the other half of the coupling, two substantially identical elastic annular discs which are arranged in laterally inverted relationship and which are curved axially outwards to form a cavity between their edges which are clamped respectively to the hub part and the outer ring, said annular discs being provided with reinforcing plies which transmit the torque between the clamped edges, the curved parts of the elastic annular discs being braced relative to one another by means of a respective annular elastic element, which does not fill the cavity, the inner end faces of the annular elements bearing against a rigid support ring, the support ring being connected to one half of the coupling so as to rotate therewith, and the mutual contact surfaces of the ring elements and of the support ring being constructed as friction surfaces.

Advantageously, the support ring consists of the outer edge of an intermediate ring mounted on the hub part of the inner half of the coupling so as to rotate therewith.

With this construction of the shaft coupling, relative movements in the direction of rotation occur between the support ring and the hollow-cylindrical elastic annular elements during operation. The frictional engagement results in additional damping which can be controlled by the choice of material for the friction surfaces and the mutual contact pressure. Thus additional damping is utilized with simple means apart from the material damping of the coupling. It is very advantageous that the radial and axial ability to move the coupling is not generally impaired and the external dimensions of the coupling are maintained so that the moment of inertia is not effectively increased.

Advantageously, a friction ring is disposed rigidly on each of the inner ends of the elastic annular elements, each friction ring preferably having a U-shaped cross-section, with the U-limbs bearing positively against the annular element. The friction rings can also be connected to the elastic ring elements by vulcanisation.

To enable the moment of friction to be controlled and preventthe brake rings from falling off with wear, advantageously brake rings movable axially independently of one another are mounted on the support ring and elastic members which press the brake rings apart are provided between them. Preferably, the elastic members are in the form of compression springs by means of which the axial prestressing of the parts frictionally in contact with one another and hence the available moment of friction is adjustable.

With regard to the construction of the mounting of the brake rings, advantageously, a plurality of studs each directed towards the support ring are secured with equal spacing on each brake ring over the entire periphery thereof, the studs engaging alternately from opposite sides positively into axis-parallel bores in the support ring without touching the respective other brake ring by their free ends. It is further of advantage to provide that the compression springs are disposed in additional axis-parallel bores in the support ring in the middle in each case between two consecutive opposite studs. This construction ensures uniform distribution of the axially directed pressure forces over the entire periphery of the brake rings and thus avoids the risk of inclination of tilting of the studs which axially guide the brake rings.

The invention may be performed in various ways and one preferred embodiment thereof will now be described with reference to the accompanying drawings, in which Figure 1 is an axial half-section through a flexible shaft coupling of the invention; and Figure2 is a partial section illustrating a guide ring and brake rings of the coupling.

The flexible shaft coupling shown in the drawings consists essentially of a hub part 1 of one half of the coupling, which hub part is secured on the end of one shaft, an outer ring 2 of the other half of the coupling for connection to the other shaft, the outer ring 2 concentrically surrounding the hub part 1, and two identical elastic annular discs 3 and 4 which are arranged in laterally inverted relationship and which flexibly connect the hub part 1 and the outer ring 2.

The annular discs 3,4 consist of rubber or another elastic material and are curved axially outwards in order to increase their flexibility.

Reinforcing plies 5,6, e.g. of fabric, are embedded inside the annular discs 3,4 and their outer and inner edges are also taken around edge reinforcing rings 7,8,9 and 10 embedded in the elastic material and are anchored thereto so as to be resistant to tensional separating forces. At their inner edges the annular discs 3,4 are clamped on the hub part 1 by axis-parallel bolts 11 between an outer flange of the hub part 1 and a clamping ring 12 via an intermediate ring 14. The outer edges of the elastic annular discs 3,4 are correspondingly secured or clamped on the outer ring 2 by means of bolts 15 between an inner flange of said ring and a clamping ring 16 via a rigid spacer ring 17.

The outwardly curved zones 18, 19 of the elastic annular discs 3,4 are braced, relative to one another by substantially annular elastic elements 20,21.

These elements 20, 21 may be in the form of individual rings fitted with axial prestressing between the elastic annular discs 3,4 and be secured thereto by vulcanization, or alternatively may form integral parts of the annular discs 3,4 as shown in Figure 1.

The relative bracing of the elastic ring elements 20, 21 is constructed as follows. The outer edge of the intermediate ring 14, which forms a support ring 22, contains a number of axis-parallel bores 23 spaced by equal amounts over its entire periphery. Every other bore 23 is lined by a guide bush 24. The bores with the guide bushes 24 serve for mounting brake rings 25,26 which are disposed on both sides of the support ring 22. Studs 27 and 28, directed towards the support ring 22, are secured to each brake ring 25, 26 and are mounted so as to be positively slidable in the guide bushes 24. A compression spring 29 is mounted in each of the bores 23 situated between two consecutive oppositely directed studs 27 and these springs tend to urge the brake rings 25, 26 axially apart.

The inner ends of the elastic ring elements 20,21 are not braced directly against the outsides of the brake rings 25,26, but through the agency of friction rings 30 and 31 respectively. The friction rings 30,31 are of U-shaped cross-section, their limbs bearing against the inner and outer surfaces of the hollow cylindrical elastic ring elements 20, 21. Each friction ring 30 and 31 is rigidly connected to its respective elastic ring element 20 or 21. Suitable friction materiais for the main components of the friction rings 30 and 31 are synthetic resin and asbestos.

When the above-described flexible shaft coupling is subjected to loads during operation, the flexibility of the elastic annular discs 3,4 results in anguiar displacements between the inner and outer halves of the coupling depending upon the torque requiring transmission and these displacements are automatically associated with corresponding relative movements of the frictionally engaging surfaces of the friction rings and of the brake rings 30, 25 and 31,26 respectively. The frictional resistance to be overcome in these conditions acts as mechanical damping in addition to the material damping present in any case. This damping can readily be controlled by the choice of material for the friction surfaces and/or a suitable value for the mutual contact pressure. The construction according to the invention thus enables the overall damping of the flexible shaft coupling to be increased without any detrimental effect as regards the overall behaviour, more particularly as regards the degree of ability for relative movement between the parts of the coupling.

Claims (7)

1. Aflexible shaft coupling comprising a hub part of one half of the coupling, an outer ring concentrically surrounding the hub part and associated with the other half of the coupling, two substantially identical elastic annular discs which are arranged in laterally inverted relationship and which are curved axially outwards to form a cavity between their edges which are clamped respectively to the hub part and the outer ring, said annular discs being provided with reinforcing plies which transmit the torque between the clamped edges, the curved parts of the elastic annular discs being braced relative to one another by means of a respective annular elastic element, which does not fill the cavity, the inner end faces of the annular elements bearing against a rigid support ring, the support ring being connected to one half of the coupling so as to rotate therewith, and the mutual contact surfaces of the ring elements and of the support ring being constructed as friction surfaces.

2. A shaft coupling according to claim 1, wherein the support ring consists of the outer edge of an intermediate ring mounted on the hub part of the inner half of the coupling so as to rotate therewith.

3. A shaft coupling according to claim 1 or claim 2, wherein a friction ring is disposed rigidly on each of the inner ends of the elastic annular elements, each friction ring preferably having a U-shaped cross-section, with the U-limbs bearing positively against the annular element.

4. A shaft coupling according to any one of claims 1 to 3, wherein brake rings movable axially independently of one another are mounted on the support ring and elastic members which press the brake rings apart are provided between the brake rings.

5. A shaft coupling according to claim 4, wherein a plurality of studs, each directed towards the support ring, are secured with equal spacing on each brake ring overthe entire periphery thereof, the studs engaging peripherally alternately from opposite sides positively into axis-parallel bores in the support ring without touching the respective other brake ring by their free ends.

6. A shaft coupling according to claims 4 and 5, wherein compression springs are provided in additional axis-parallel bores in the support ring in the middle in each case between two consecutive opposite studs, said compression springs bearing against the brake rings under tension.

7. A shaft coupling substantially as herein de scribed with reference to the accompanying draw ings.