GB2078907A - Improvements relating to highly resilient shaft coupling devices - Google Patents

Abstract

A first coupling (3) has a linear characteristic and its resilient transmission elements (9) are preferably elastomers, a second coupling (4) has a progressive characteristic and its resilient transmission elements (19) are preferably elastomers having extra- strength reinforcing inserts. The linear coupling (3) extends co-axially around the progressive coupling (4) and the inner coupling and outer coupling (4,3) each have one flange (2, 1) at opposite axial ends for connection to the shafts to be interconnected. The two individual couplings are resiliently movable relative to one another axially, radially and in rotation. This produces a characteristic which is basically progressive but whose progressiveness is less than that of a conventional progressive characteristic, so that the coupling device has increased torsional resilience in the full-load range. <IMAGE>

Description

SPECIFICATION Improvements relating to highly resilient shaft coupling devices There are basically two different kinds of resilient shaft coupling devices. In one kind the resilient members serving to transmit the torque are elastomers which usually have metal parts vulcanized on to their connection ends. The resilience of devices of this kind follows a linear characteristic - i.e., they are soft in the fuil-load range and fairly hard in the partial-load range.

In the other kind of coupling device the resilient members serving to transmit the torque are elastomers in which fabric inserts have been vulcanized.

Devices of this kind have a progressive characteristic - i.e., they are relatively hard in the full-load range and very soft in the partial-load range.

Devices of the first kind are of a relatively large overall size because of limitations on the extent to which the elastomers used for them can be loaded. If the highly resilient elements are torsion elements, relatively considerable radial mobility can be provided, but axial displacements call for high restoring forces, so that axial mobility is very limited.

Because of the presence of the fabric torquetransmitting inserts in the resilient transmission elements, shaft coupling devices having a progressive characteristic have a much greater specific power, a feature which of course reacts favourably on overall size. Coupling devices of the progressive kind can be smaller and more compact than linear devices. Progressive coupling devices can deal with radial and axial movements of the shafts they connect but radial mobility is much less than in a linear coupling device whose resilient elements are torsion elements.When progressive devices are used in plant driven by diesel engines, their high rigidity on full load is not a disturbance in normal operation, but in the event of disturbances in engine operation, such as the malfunctioning of individual cylinders, conditions may arise in which there is a risk of overstressing and therefore destruction of the coupling and/or the facilities driven through it.

For many cases in which resilient shaft coupling devices are used it would be desirable to have available a coupling device whose characteristic is basically progressive but whose progressive behaviour is less than that provided by a conventional progressive characteristic, so that the device has correspondingly increased torsional resilience in the full-load range.

It is the object of the invention so to devise a shaft coupling device with desirable resilient characteristics.

The invention accordingly provides a highly resilient shaft coupling device formed from two individual couplings which are resiliently movable rela timely to one another axially, radially and in rotation, the couplings being combined structurally in series with one another for the transmission of forces and comprising a first and linear-characteristic coupling whose resilient transmission elements are formed from elastomers or other suitable material, and a second and prog ressive-characteristic coupling whose resilient transmission elements are formed from elastomers having extra-strength reinforcing inserts, or other suitable material.

The characteristic of a combined device of this kind is basically progressive but the progressiveness is reduced - i.e., the device is more torsionally resilient in the full-load range than a conventional progressive device.

In the preferred embodiment the linear coupling extends axially around the progressive coupling, and the inner coupling and outer coupling each have one flange at opposite axial ends for connection to the shafts to be interconnected. With the two individual couplings in a nested arrangement of this kind, the overall size of the complete device is virtually no greater than that of a conventional linear shaft coupling. It is advantageous for the progressive coupling to be the inside coupling since the elastomers having the fabric inserts can deal with heavier loads than elastomers alone and can therefore receive the high peripheral forces in the interior of the coupling device, whereas the elastomers without fabric inserts are best disposed in the outer region of the device where the peripheral forces are correspondingly less.

It is preferred that the outer coupling incorporates a cylindrical flange cover which is secured to its connecting flange and, at its exposed end, defines a flange ring directed inwardly at right-angles to the rest of the cover, two elastomeric annular members are disposed in concentric and consecutive relationship with metal rings secured to their end faces, the annular members being secured by way of the metal rings in one case to the connecting flange of the outer coupling and in the other case to the flange ring of the flange cover, and by way of their inner end faces to a central connecting flange of the inner coupling. Each annular member can be in one or more parts.

Advantageously, the inner coupling has an inwardly extending hub secured to the connecting flange of the inner coupling, and two annular members made of elastomers with fabric inserts and centred by and clamped to the hub, the latter annular members being clamped by way of their outer edges on opposite sides to the inner edge of the central connecting flange of the inner coupling.

Since the outer coupling has greater radial mobilits than the inner coupling, it is convenient to secure the inner coupling against radial mobility and to use only the radial mobility of the outer and linear coupling. In the preferred embodiment, therefore, the central connecting flange of the inner coupling has an inner bearing surface concentric with the rotational axis which is mounted for rotation and for axial movement on a bearing bush which is axially immobile on an intermediate ring resting on the hub, and is clamped between and together with the inner-coupling annular members of elastomer with fabric inserts and the hub. This feature, since it obviates radial movements of the inner coupling and, therefore, of the annular members of elastomer with fabric inserts, also reduces heating of such members.

It may be convenient if the inner-coupling annular members when assembled bulge out like beadings on opposite sides.

Conveniently, the annular members are clamped by means of bolts. Thus there may be a number of equi-angularly disposed bolts and nuts extending through registering bores for interconnecting respectively the outer periphery of the inner coupling annular members with the central connecting flange of the inner coupling and the inner periphery of the inner coupling to annular members with the intermediate ring and the hub, the bolts having their axes parallel to one another.

A highly resilient shaft coupling device of this kind is particularly suitable for use in drives where oscillations are likely to occur. Since, as previously mentioned, the progressiveness of the progressive characteristic of the combined coupling device is so low that it provides high torsional resilience even in the full-load range, overstressing of the coupling device cannot occur even when, for example, a driving diesel engine mis-operates because one or more of its cylinders is not firing.

The invention may be performed in various ways and one preferred embodiment thereof will now be described with reference to the drawing, which is an axial section cutaway along the axis of a shaft coupling device constructed in accordance with the invention.

Two outer flanges 1,2 are provided for attachment to the ends of shafts which it is required to interconnect by the shaft coupling device. In the embodiment shown the flange 1 is the input or driving flange and the flange 2 is the output or driven flange.

The device comprises two individual couplings 3, 4which are disposed in consecutive or series relationship. Coupling 3 has a linear characteristic and is the outer coupling, while the other individual coupling 4 has a progressive characteristic and is disposed axially inside the outer coupling 3 and, therefore, is the inner coupling.

The outer coupling 3 has a cylindrical flange cover 5 which is secured to the flange 1 and which, at its free end forms a flange ring 6 directed inwardly at right-angles to the rest of the cover. The two elements 1 and 5 are connected together by equiangularly spaced screws 7. In order to keep the outer periphery of the compiete device as small as possible, the heads of the screws are received to some extent in corresponding recesses in the cover 5.

The outer coupling 3 has transmission elements which are made of an elastomeric substance. Thus two annular members 9 are provided which are of appropriate axial length. The members 9 are stressed when a torsional load is applied to the coupling device and have metal rings 10 vulcanized on to their outer end faces. Metal rings are also vulcanized on to their inner end faces and are in the form of conicai rings 11 whose outside surfaces extend parallel to the outer metal rings 10. The annular members 9 are secured on their outsides by pins 12 received in a positive connection in registering bores in the flange 1 and the metal ring 10 in one case and in the flange ring 6 and the metal ring 10 in the other case. This ensures that the members 9 co-rotate with one another.On their outside edge the rings 11 engage with opposite sides of a connecting flange 13 which is a component of the inner coupling 4. Co-rotation of the rings 11 with the flange 13 is achieved by means of a number of equi-angularly spaced pins 14.

The flange 13 has an inner foot or base portion defining a cylindrical bearing surface 15 extending co-axially of the axis of rotation. The surface 15 enables flange 13 to move axially on a bearing bush 16 which is axially immobile on a multi-element intermediate ring 17. The ring 17 is in positive engagement with a hub 18 which is unitary with the driven or output flange 2.

Disposed on both sides of the flange 13 and the ring 17 are annular members 19 consisting of elastomers with fabric inserts, the members 19 bulging outwards like beadings in opposite directions. A number of bolts 20 whose axes are parallel to one another, extend through the outer edges of the annular members 19 and serve to clamp the same to the flange 13. Associated with the bolt heads and associated nuts are clamping rings 21 which ensure that the pressures produced by the bolts 20 are transmitted uniformly to the annular members 19.

The inner peripheries of the annular members 19 are clamped, together with the intermediate ring 17, to a collar 22 of the hub 18, by means of bolts 23.

Accordingly, a clamping ring 24 is provided on the end of the hub 18 and is centred on its inner face, by means of a cylindrical recess 25 mating with the exposed end face of the hub 18. The axial distance between the radial contact surface of the collar 22 and the radial contact surface of the clamping ring 24 is such that, for a non-positive engagement of the clamping ring 24 with the hub end face, the annular members 19 can be clamped with a required clamping force. As will be readily apparent from a consideration of the construction of the shaft coupling device, relative radial movements between the flanges 1 and 2 stress only the purely elastomeric annular members 9 of the outer coupling, whereas relative axial movements stress mainly the elastomer-plus-fabric-insert annular members 19 of the inner coupling, since the axial resilience of the annular members 19 is greater than that of the i annular members 9.

Claims (7)

1. A highly resilient shaft coupling device formed from two individual couplings which are resiliently movable relatively to one another axially, radially and in rotation, the couplings being combined structurally in series with one another for the transmission of forces and comprising a first and linear-characteristic coupling whose resilient transmission elements are formed from elastomers and other suitable material, and a second and progressive-characteristic coupling whose resilient transmission elements are formed from elastomers having extra-strength reinforcing inserts, or other suitable material.

2. A device according to claim 1, wherein the linear coupling extends axially around the progressive coupling, and the inner coupling and outer coupling each have one flange at opposite axial ends for connection to the shafts to be interconnected.

3. A device according to claim 2, wherein the outer coupling incorporates a cylindrical flange cover which is secured to its connecting flange and, at its exposed end defines a flange ring directed inwardly at right-angles to the rest of the cover, two elastomeric annular members are disposed in concentric and consecutive relationship with metal rings secured to their end faces, the annular members being secured by way of the metal rings in one case to the connecting flange of the outer coupling and in the other case to the flange ring of the flange cover, and by way of their inner end faces to a central connecting flange of the inner coupling.

4. A device according to claim 3, wherein the inner coupling has an inwardly extending hub secured to the connecting flange of the inner coupling, and two annular members made of elastomers with fabric inserts and centred by and clamped to the hub, the latter annular members being clamped by way of their outer edges on opposite sides to the inner edge of the central connecting flange of the inner coupling.

5. A device according to claim 4, wherein the central connecting flange has an inner bearing surface concentric with the rotational axis which is mounted for rotation and for axial movement on a bearing bush which is axially immobile on an intermediate ring resting on the hub, and is clamped centrally between and together with the inner coupling annular members and the hub.

6. A device according to claim 5, wherein the inner coupling annular members, when assembled, bulge out like beadings on opposite sides.

7. A device according to any one of claims 4 to 6, wherein a number of equiangularly disposed bolts and nuts extend through registering bores for interconnecting respectively the outer periphery of the inner coupling annular members with the central connecting flange of the inner coupling and the inner periphery of the inner coupling to annular members with the intermediate ring and the hub, the bolts having their axes parallel to one another.