DOUBLE JOINT CLUTCH

BACKGROUND OF THE INVENTION The present invention relates to a new and im¬ proved construction of a double joint clutch having two clutch hubs, a clutch socket or sleeve interconnecting the clutch hubs and transmitting or transmission elements for transmitting a torque which are uniformly distributed over the circumference of the clutch hubs.

For the transmission of large power outputs between rapidly running shafts, it is often necessary to interconnect two shaft ends so as to be elastically bend- able by means of a clutch having a compact construction and, at the same time, to ensure that an axial thrust, such as for instance can arise during switching-in or switchingioff a drive machine, does not lead to destruc¬ tion of the clutch.

In German Patent No. 1,963,755 there are known to the art double joint or universal joint clutches of the above-described species, which are constructed as rotationally rigid double jaw clutches having an internal- ly toothed clutch socket and two externally toothed clutch hubs. According to one constructional embodiment of such type of prior art clutch there are arranged, in¬ stead of individual teeth between the clutch hubs and the clutch socket, elastically structured engagement elements in radial direction, which are under a pre-bias or stress and center the clutch socket or sleeve in relation to the clutch hubs. According to another embodiment the center¬ ing action of the clutch socket in relation to the clutch hubs is realized in that, teeth individually formed at the clutch hubs have, in relation to the related teeth of the clutch socket, an overdimension and the clutch socket is elastically expandible. In both cases the clutch socket can be centered due to its radial pre-bias in relation to the clutch hubs. However, disturbance free operation can only be maintained if such clutches are not loaded with any appreciable axial forces. Greater axial forces and the moments brought about when axially offset¬ ting both of the shafts which are to be coupled with one another, therefore lead rapidly to destruction of the heretofore known species of clutches. Hence, it is absolutely mandatory that such state-of-the-art clutch be load relieved from any appreciable axial force by axial pressure bearings arranged to both sides of such clutch.

Each bearing arrangement however means that when transmitting larger loads at higher rotational speeds.

itZLf there arises a loss in efficiency, and it is for this reason that the number of bearings must be maintained as low as possible.

SUMMARY OF THE INVENTION Therefore, with the foregoing in mind it is a primary object of the present invention to provide a new and improved construction of a double joint clutch of the character described which is not associated with the afore¬ mentioned drawbacks and limitations of the prior art con- structions.

Another and more specific object of the present invention aims at providing a new and improved construction of clutch of the previously described type which, during the transmission of large torque or rotational moments be¬ tween rapidly running shafts, allows for relatively large parallel displacement and other axial shifting of such shafts in relation to one another and is extensively insen¬ sitive to axial forces.

Now in order to implement these and still further objects of the invention, which will become more readily apparent as the description proceeds, the clutch of the present development is manifested by the features that both clutch hubs are additionally interconnected with one another by means of a bending rod arranged within the clutch socket or sleeve.

On the one hand, the bending rod is rotatably yielding such that the total torque or rotational moment can be transmitted, by means of the transmission or trans¬ mitting elements and the clutch socket, from one clutch 1° hub to the other clutch hub. On the other hand, the bending rod is sufficiently buckling resistant or stiff in order to take-up axial thrusts. Such axial thrusts can be periodically and/or surgewise generated, for instance by means of a drive machine or a driven machine.

The inventive double joint clutch is especially contemplated to transmit power outputs exceeding 10,000 kW.

In machine assemblies having a power output of this order of magnitude it is possible that one machine produces an axial thrust of, for instance, 10,000 kp in one direction ' and another machine an axial thrust of 15,000 kp in the opposite direction. The inventive clutch is capable of absorbing such'axial thrusts, so that only a single axial - pressure bearing is needed, which can take-up the resultant axial thrust of, in the example given, for instance 5,000 kp. Hence, the total efficiency of the machine assembly can be appreciably increased in comparison to heretofore known clutch and bearing arrangements, while retaining the other conditions the same.

Depending upon the desired axial rigidity the bending rod can be connected to be buckling resistant and/ or also rotationally fixed with the clutch hubs.

Depending upon the desired torsional rigidity the engagement elements which transmit the torque or rotational moment can be structured as membrane bending rods, lamellae, sleeves, teeth or the like.

With a direct attachment of the bending rod at both clutch hubs there is realized the possibility of assembling and disassembling the entire inventive double joint clutch, without having to take the same apart, be¬ tween both of the shaft ends which are to: be coupled with one another.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and ob¬ jects other than those set forth above will become apparent when consideration is given to the following detailed des¬ cription thereof. Such description makes reference to the annexed drawings wherein:

Figure 1 is an axial sectional view of a first embodiment of double joint clutch showing the same in its normal position:

Figure la is an enlarged partial sectional view of the clutch arrangement of Figure 1, the section being taken along the line A-A thereof; Figure 2 is an axial sectional view of the clutch shown in Figure 1 illustrating the same in strongly exag¬ gerated deflected position; Figure 3 is an axial sectional view of a second embodiment of double joint clutch in its normal position; and Figure 4 is an axial sectional view of the clutch shown, in Figure 3, with markedly exaggerated deflection of the clutch.

DETAILED DESCRIPTION OF THE PREFERRED'EMBODIMENTS Describing now the drawings, both of the exem¬ plary embodiments of double joint or universal joint clutch¬ es shown in Figures 1, la and 2 on the one hand and in Figures 3 and 4 on the other hand, will be initially col¬ lectively described hereinafter to the extent that the lO structure of both embodiments coincides with one another.

In both instances the double joint clutch serves to inter¬ connect two shaft ends 10 and 12 with one another, the axes of which, normally are in alignment with one another, but equally also oould be inclined with respect to one another, or, as shown in Figures 2 and 4 in extremely exaggerated illustration, could be offset parallelly with respect to one another. Both shaft ends 10 and 12 each have a respective flange 14 for the double joint clutch.

The shaft end 12 arranged to the right of the double joint clutch, as shown in Figure 1, is mounted in a bear¬ ing 16 .

115044 Each of the illustrated double joint clutches has as its primary components two clutch hubs 18, a clutch socket or sleeve 20 and a bending rod 22.

Formed at each clutch hub 18 is a radial outer flange 24 which is threadably connected, for instance bolted by means of the threaded bolts with the flange 14 at the neighboring shaft end 10 and 12, respectively.

Additionally, at each clutch hub 18 there is formed a radial inner flange 26 which is threadably connected, again for instance by means of the threaded bolts, with a flange 28 at the neighboring end of the bending rod 22. This bending rod 22 is centered in the flanges 26 of both clutch hubs 18 and furthermore extends, with radial intermediate play or space, through the clutch hubs 18 and the clutch socket 20.

Each of both clutch hubs 18 has teeth or teeth means 30, which according to the embodiment of Figures 1, la and 2, are structured as external teeth, whereas in the embodiment of Figures 3 and 4 they are constructed as inter¬ nal teeth. The teeth 30 of the clutch hubs 18 have opera- tively associated therewith the respective teeth 32 provided at the clutch socket 20, which according to the embodiment of Figures 1, la and 2 are constructed as internal teeth, 115044 while in the embodiment of Figures 3 and 4 on the other hand they are constructed as external teeth.

Now since however the torque or rotational moment which is to be transmitted by the double joint clutch is exclusively taken-up by the clutch hubs, the clutch sockets interconnecting the same and the transmission elements arranged between both of these components, these teeth and 32, with both of the exemplary embodiments, fulfill quite different functions.

With the first-mentioned embodiment of Figures 1, la and 2, the teeth 30 and 32, and as particularly well seen by referring to Figure la, have an appreciable play in radial direction with respect to one another and also a certain play in the circumferential direction. This means that in normal operation they do not participate in the transmission of the torque, quite in contrast to the second exemplary embodiment of Figures 3 and 4. Both of the clutch hubs 18, in the first exemplary embodiment, as best seen by referring to Figures 1 and 2, have membrane- like arranged bending rods 34, whose radial outer ends are clamped between one of the end pieces or members 36 of the clutch socket 20 operatively associated with the related - clutch hub 18 and a protective ring 38 which is threadably connected therewith. The membrane-like bending rods 3 4 are extremely elastic, so that any axial shifting of both shaft ends 10 and 12 can be taken-up by such bending rods 34.

With the embodiment of Figures 3 and 4 such axial shifting is taken-up by the crown configuration of the teeth 32.

In the critical case, that is to say upon exceed- ing the permissible torque, with the embodiment of Figures 1 and 2 the membrane-like bending rods 34 rupture. Hence, the teeth 30 and 32 of Figure la come into play, which in that case enables shutdown of the machine assembly. With the same critical situation for the embodiment of Figures 3 and 4, only one or a number of teeth of the teeth 30 and 32 will become defective.

The bending rod 22 is so slim and correspondingly soft or yieldable that it does not participate in the torque transmission. However, it is sufficiently bending or buckling resistant that it is capable of transmitting all of the arising axial forces directly from one clutch hub 18 SI to the other clutch hub 18, and specifically, also even then when both shaft ends 10 and 12, as shown in Figures 2 and 4, are offset parallelly with respect to one another.

In the event that the bending rod 2 2 should rupture, then with the exemplary embodiment of Figures 1, la and 2, there is formed at the inner surface of each end piece 36 of the clutch socket or sleeve 20 a substantially ring- shaped or annular stop or impact member 40 which engages into an intermediate space between the teeth 30 of the re- lO lated clutch hub 18 and a likewise ring-shaped counterstop 4 2 attached at such clutch hub 18".

In the event of fracture of the bending rod 22 these stops 40 and counterstops 42, together with the ring- shaped constructed ends of the related teeth 30, limit the axial relative shifting of both shaft ' ends 10 and 12, so that the double joint clutch can still run, without suffering any additional damage, until the machine assembly, of which the shaft ends 10 and 12 are a part, can be turned-off and shut down. With the embodiment of Figures 3 and 4, in the event of rupture of the bending rod 2 2 the teeth 30 and 32 assume the function of the stops 40, and the counterstops 4 2 on the one hand, or the clutch hubs, on the other hand, prevent the axial relative displacement or shifting of both shaft ends 10 and 12.

The substantially ring-shaped constructed stops (Figures 1 and 2), and the corresponding counterstops 42 and the end of the teeth 3 2 protruding against the stops are provided with a convex end surface. For reasons of simplicity in illustration such end surface has not been particularly shown in the drawings.

For the exact functionally equivalent purpose there is provided with the second exemplary embodiment of Figures 3 and 4 a convex end surface at the end of the teeth 3 2 directed towards the counterstops or impact members 42.

With the embodiment of Figures'I, la and 2 both of the end pieces or members 36 of the clutch socket are interconnected by a tubular-shaped intermediate piece or element 44. In this case the clutch socket 20 is con¬ structed as a three-part unit or, if there are considered the protective rings 38, then as a five-part unit.

On the other hand, with the embodiment of Figures 3 and 4, the clutch socket or sleeve 20 is con- structed as a one-part unit, however is provided at both of its ends with a respective lubricant chamber or space 46 which is formed within its teeth 32. Prom such chamber 46 it is possible to directly impinge with a suitable lubricant the teeth by means of a type of spray nozzle which consists of small bores at the tooth root or base of the teeth. The teeth 3 2 are crowned and engage with radial pre-bias or stress into the teeth 30 of the clutch hubs 18, so that in this case there is ensured for center¬ ing of both ends of the cltuch socket 20 in relation to the clutch hubs 18.

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

1. A double joint clutch comprising:

two clutch hubs; a clutch socket interconnecting said two clutch hubs; transmission elements for transmitting a torque distributed essentially uniformly about the circumference of each of the clutch hubs; a bending rod arranged within the clutch socket? and means for connecting said bending rod with both of said clutch hubs.

2. The double joint clutch as defined in claim lr wherein:

said connecting means connects said bending rod to be stiff against bending with both of the clutch hubs.

-