GB2244763A

GB2244763A - Positive clutch

Info

Publication number: GB2244763A
Application number: GB9022541A
Authority: GB
Inventors: Guenther Heidrich
Original assignee: BHS Voith Getriebetechnik GmbH
Current assignee: BHS Voith Getriebetechnik GmbH
Priority date: 1989-11-03
Filing date: 1990-10-17
Publication date: 1991-12-11
Also published as: DE3936680C1; GB9022541D0

Abstract

A positive clutch comprises two axially non-displaceable coupling members (2, 11) fixedly joined to respective connecting shafts (1, 15) i.e. a drive shaft (1) and an output shaft (15), and connectable to each other by way of gearing tooth via at least one axially displaceable coupling element (5). One of the coupling members (11) is mounted upon the other coupling member (2) via a bearing mounting (16), and the coupling member (11), which cooperates with the teeth (7) on the element (5) is connected to the adjacent connecting shaft (15) via an axially resilient coupling (14). The member (2) may have an extension (Fig. 2) which forms part of a bearing, the member (11) may be supported by a bearing on the element (5) (Fig. 3), and the coupling (14) may be pretensioned (Fig. 4). The element (5) also has straight teeth (8) engaging claws (9). <IMAGE>

Description

1 - SWITCHABLE GEAR COUPLING j-7 C--- - -- j This invention relates to a

switchable gear coupling between two connecting shafts, i.e. a drive shaft and an output shaft, in particular for alternate connection and disconnection of a drive unit of a ship's engine, comprising two axially nondisplaceable coupling members, which are each fixedly connected to a respective one of the connecting shafts, and which are connectable to each other by way of gearing via at least one axially displaceable coupling element.

Already known in the state of the art is a ship's drive, comprising a gas turbine, clutches, planet gears, spur gearing and propeller shaft with propeller, which employs switchable gear couplings, for alternate connection and disconnection of drive units. The engageable and disengageable gear coupling used in clutches of this type is loaded both by the torque and additionally by thermal expansions and periodic axial forces.

To restrict the aforementioned forces, insofar as they are axially effective, the torque-loaded teeth of the outer and inner tooth arrangement must be axially displaceable relative to one another so as to function correctly. In order to achieve this, the frictional resistance between the tooth flanks has to be overcome. A quantitative restriction therefore depends on the amount of frictional resistance, and thus on the coefficient of friction.

The resulting additional stress on gear couplings of this type can disadvantageously result in overloading, with continued operation increasing the coefficient of friction, inhibiting the axial displaceability of the two gearings, and finally causing damage to the clutch.

The frictional resistance of the clutch also loads the gear SJL161090 components of drives of this type, for example when the gearwheel sets are double helically geared and when thermal expansions and dynamic axial loads are transmitted via these gearings to the clutch.

In a further known ship's drive, disclosed in DE-PS 28 37 044 and having counter-rotating propellers, bypass coupling between a drive unit and a pinion wheel of a spur wheel gear are exposed to the same undesirable loads.

Separately, a torque transmitting coupling arrangement between shafts of interconnected sectional units of a machine assembly is disclosed in DEPS 35 35 557 which has a diaphragm-coupling assembly and a gear-coupling assembly arranged in series. Although this gear-coupling arrangement incorporates an externally toothed hub and an internally toothed gear ring, it does not have a switchable gear coupling between two connecting shafts, in contrast to the output paint of the present construction.

An object of the present invention is to provide a switchable gear coupling construction whereby the aforementioned overloads can be avoided whilst maintaining its desirable compact structure.

This is achieved according to the invention in that one of the nondisplaceable coupling members is mounted upon the other nondisplaceable coupling member via at least one radial/axial bearing portion, and the first mentioned non-displaceable coupling member is connected to the adjacent connecting shaft via an axially resilient coupling.

This offers the advantage that thermal expansions and/or periodic axial forces, which develop, for example in a connecting shaft, are absorbed by the axially elastic coupling. The restoring forces of the axially elastic coupling, which are SJL161090 - 3 very low due to its extremely low axial spring stiffness are then transmitted via the axial profile of a bearing and the respective non- displaceable coupling member onto the other connecting shaft and absorbed by their axial mounting arrangement. Accordingly, the engaged and torque- loaded gear coupling is completely clear of axial forces and freed from its task of limiting axial supplementary loads by way of axial displacement.

Variations of the invention include the attachment of the switchable gear coupling at the opposite end of the axially elastic coupling to either a double mounted connecting shaft or a single mounted connecting shaft. In the latter case a second bearing support for this single-mounted shaft is provided by an additional bearing of the gear coupling in the vicinity of the other, double mounted connecting shaft.

Furthermore, in preferred embodiments of the present invention the nondisplaceable coupling member which is attached to the axially elastic coupling can be mounted upon the other axially non-displaceable coupling member by means of a second bearing mount via the displaceable coupling element.

The invention will be described below in more detail, based on the embodiment examples which are illustrated in the accompanying drawings. In the drawings:

Figs. 1 to 3 are fragmentary cross-sections of three different embodiments of the synchronously switchable gear coupling of the invention between two connecting shafts; and Fig. 4 is a fragmentary detail of the axially elastic coupling used in those three embodiments shown prior to mounting in a tension-free state, and with coupling length "L".

Fig. 1 illustrates a synchronously switchable gear coupling, in SJL161090 4 the upper half in its disengaged state, and in the lower half in its engaged state.

A connecting shaft 1, i.e. a drive shaft, is double-mounted by way of bearings 40 and 41, and a coupling member 2 which is axially immovable is fixedly attached thereto. This axially non-displaceable coupling member 2 has an external thread 3 with which an internal thread 4 of an axially displaceable coupling element 5, in the form of a coupling sleeve, is engaged.

The coupling sleeve 5 has an external straight-toothed gear 6 of an engageable/disengageable gear coupling 7 as well as an external straighttoothed gear 8 for coupling claws 9.

The coupling claws 9, which are constructed in a conventional manner, are rotatably mounted in a flange 10. The flange 10 is connected to another axially non-displaceable coupling member 11, which carries the internal straight-toothed gear 12 of the gear coupling 7.

The axially non-displaceable coupling member 11 is attached, via a mounting flange 13 and an axially resilient coupling 14, to another double mounted connecting shaft 15, which is the output shaft.

The axially non-displaceable coupling member 11 is mounted via a radial/axial bearing portion 16 of the mounting flange 13 on the other axially non-displaceable coupling member 2.

The axially resilient coupling 14 can be a diaphragm coupling, which has an extremely low axial spring stiffness and which is formed by a web 34 and a web 35, which are connected to each other in a radially inner part 22 of the coupling.

Fig. 1 reveals that one of the non-displaceable coupling members 11 is supported relative to the other non-displaceable 1 SJL161090 coupling member 2 via at least one radial/axial bearing portion 16. In this respect the non-displaceable coupling member 11, disposed at the input side of axial forces and being part of the gear coupling, is connected to the adjacent connecting shaft 15 via the axially resilient coupling, i.e. the diaphragm coupling 14. More specifically the coupling member 11 is attached to a mounting flange 13, which is integral with the radial/axial bearing portion 16 at one side and at the other side is connected to the axially resilient coupling 14.

Fig. 2 illustrates another embodiment of the invention wherein the drive shaft is a single-mounted connecting shaft 18. In this case a bearing 43 is provided whereby, again, the connecting shaft 18 is rigidly connected to an axially nondisplaceable coupling member 2. The same engageable/ disengageable gear coupling 7 as that in the embodiment of Fig. 1 is used. However, the axially non-displaceable coupling member 2 has a shaft extension 20 which serves as part of a second bearing. The other part of the second bearing is formed by a bearing hub 21 of an intermediate element 30, which is connected, via a mounting flange 19, to the axially resilient coupling 14 at one side, and, at the other side, to the adjacent double-mounted connecting shaft 15. Thus, the shaft extension 20 of the first non-displaceable coupling member 2 serves as the bearing mount of the single-mounted connecting shaft 18, which is the drive.

Fig. 3 illustrates a further embodiment of the invention which is similar in construction to the Fig. 1, embodiment, in which respect, again, a connecting shaft 1, which is double-mounted via two bearings 40 and 41, serves as a drive shaft. Under special operating conditions, for example when the two connecting shafts 1 and 15, i.e. the drive shaft and output shaft, are offset at an angle it may be advantageous to support the first non-displaceable coupling member 11, via a second bearing 17, on the coupling sleeve 5, and thus on the other non- SJL161090 displaceable coupling member 2. In this respect, and in this particular case, the first non-displaceable coupling member 11 is connected to a mounting member 33, which supports itself relative to a support area 31 of the other non-displaceable coupling member 2 via an extension 32 of the displaceable coupling element 5, thus establishing the aforesaid second bearing 17.

A further improvement of the overload protection is achieved if, in accordance with what is shown in Figs. 1 and 4, the diaphragm coupling 14 is mounted in such a way as to be pretensioned with a smaller or larger length 'W' (compressed or drawn). This type of pretension is dependent on the input side of the axial load, i.e. on which side the bearing portion 16, loaded by the pretensional force of the diaphragm coupling 14, is to abut without play against the axially non-displaceable coupling member 2.

In this context, Fig. 4 illustrates the axially resilient coupling 14 prior to being assembled in a tension-free state and the coupling length "L".

Owing to the resilience of the coupling 14 it can be installed between the connecting shaft 15 or the intermediate member 30 on the one hand and the mounting flan ge 13 on the other hand in a space which is greater than, equal to, or smaller than its length "L".

The overload protection according to the present invention operates as follows:

If thermal expansion occurs and/or periodic axial forces develop, for example in the connecting shaft 15, then these are absorbed by the axially elastic coupling 14. The restoring forces, which are very small due to the extremely low axial spring stiffness of the axially resilient coupling 14, which is v SJL161090 - 7 a diaphragm coupling, are transmitted via the axial part of the bearing portion 16 and the first non-displaceable coupling member 2 to the connecting shaft 1 or 18 respectively (according to Fig. 1 or 2 respectively) and absorbed by their axial mounting arrangement. Thus, the engaged and torque-loaded gear coupling 7 is advantageously entirely free of axial forces and relieved of the task of limiting additional axial loads by axial displacement.

If gearing, such as double helical gearing is installed in the drive line of the connecting shaft 15, it is loaded only by the very low restoring force of the axially elastic coupling 14 in addition to the normal load of the gear forces.

If the introduction of additional load takes place from the opposite side, i.e. the connecting shaft 1 or 18 respectively, the same relief of the gear coupling 7 results.

The inventive arrangement of the gear coupling 7 with overload protection requires little additional axial construction space due to its very compact structure. The additional radial bearing 20/21 in the Fig. 2 embodiment brings about a further saving in axial space.

Furthermore, the diaphragm coupling 14 permits the mounting hub 21 of the intermediate element 30 in the Fig. 2 embodiment to be disposed within the coupling member 22, resulting in further space-saving.

The synchronous gear coupling, on which the illustration of the invention is based, is a known construction of Messrs. SSS Gears Limited, Great Britain. However, other alternative synchronous switchable gear couplings embodying the present invention can be constructed. Furthermore, the bearings 16, 20/21, which in the illustrated embodiments are sliding bearings, can alternatively consist of roller bearings.

SJL161090 The illustrated embodiments specifically relate to a ship's drive. However, the invention is equally applicable to couplings between gas turbines and generators to allow phaseshift operation, to rotary devices for turning jet engines, or for use in hydro-power plants between turbine and generator to perform a pumping operation.

The present invention offers in an advantageous way a switchable gear coupling with overload protection, whereby the compact construction of a coupling of this type is fully maintained.

r SJL161090

Claims

1. A switchable gear coupling between two connecting shafts, namely a drive shaft and an output shaft, comprising two axially non-displaceable coupling members, which are connected to the respective connecting shafts and are connectable to each other by way of gearing via at least one axially displaceable coupling element, characterised in that one of the non-displaceable coupling members is mounted upon the other nondisplaceable coupling member via at least one radial/axial bearing portion, and the first mentioned non-displaceable coupling member is connected to the adjacent connecting shaft via an axially resilient coupling.

2. A gear coupling according to claim 1 wherein the first nondisplaceable coupling member is connected to a mounting flange, which at one side is integral with the radial/axial bearing and at the other side is connected to the axially resilient coupling.

3. A gear coupling according to claim 2 wherein a doublemounted connecting shaft is connected to that one of the nondisplaceable coupling members which includes the other part of the radial/axial bearing portion.

4. A gear coupling according to claim 2 wherein a singlemounted connecting shaft is connected to that one of the nondisplaceable coupling members which includes the other part of the radial/axial bearing portion, said coupling member also providing a part of a second bearing mount for the connecting shaft, the other part of the second bearing mount being connected to the axially resilient coupling.

5. A gear coupling according to claim 4 wherein the axially nondisplaceable coupling member has a shaft extension serving as part of the second bearing mount, and the other part of the SJL161090 - second bearing mount is formed by a mounting hub of an intermediate element which is connected at one side, via a mounting flange, to the axially resilient coupling and at the other side to the adjacent connecting shaft.

6. A gear coupling according to any one of claims 1 to 3 wherein the first non-displaceable coupling member is additionally supported relative to the other non-displaceable coupling member via a further bearing and the displaceable coupling element.

7. A gear coupling according to claim 6 wherein the first nondisplaceable coupling member is connected to a mounting member which is supported, via an extension of the displaceable coupling element, relative to a support area of the other nondisplaceable coupling member.

8. A gear coupling according to any of claims 2 to 5 wherein the distance between the one connecting shaft or the intermediate element on the one hand and the mounting flange on the other hand equals the length of the axially resilient coupling.

g. A gear coupling according to any of claims 2 to 5 wherein the distance between the one connecting shaft or the intermediate element on the one hand and the mounting flange on the other hand is greater than the length of the axially resilient coupling.

10. A gear coupling according to any of claims 2 to 5 wherein the distance between the one connecting shaft or the intermediate element on the one hand and the mounting flange on the other hand is smaller than the length of the axially resilient coupling.

11. A gear coupling according to claim 2 or any claim dependant 7 1 SJL161090 - 11 thereon wherein the axially resilient coupling is a diaphragm coupling having one web portion connected to the mounting flange and another web portion connected to the adjacent connecting shaft, directly or via an intermediate element.

12. A gear coupling according to claim 5 wherein the mounting hub of the intermediate element is arranged within the area defined by an inner section of the diaphragm coupling.

13. A gear coupling substantially as herein described with reference to and as illustrated by any of the accompanying drawings.

Published 1991 at The Patent Office. Concept House. Cardiff Road, Newport, Gwent NP9 I RH. Further copies may be obtained from Sales Branch, Unit 6. Nine Mile Point. Cwmfelinfach, Cross Keys, Newport. NPI 7HZ. Printed by Multiplex techniques ltd, St Mary Cray, Kent.