GB2027500A

GB2027500A - A freewheel clutch

Info

Publication number: GB2027500A
Application number: GB7927732A
Authority: GB
Original assignee: Ringspann Albrecht Maurer KG
Current assignee: Ringspann Albrecht Maurer KG
Priority date: 1978-08-09
Filing date: 1979-08-09
Publication date: 1980-02-20
Also published as: GB2027500B; DE7823742U1

Abstract

An overrunning device for transmitting torque from a driving member 1 to a coaxial take-off member 9 includes a freewheel coupling, of which the outer ring 4, is connected to the driving member 1, the inner ring 6 is disposed on the take-off member 9, and gripping members 5 are urged by centrifugal force to disengage drive between the rings 4 and 6 when the inner ring 6 rotates faster than a predetermined speed. The driving member 1 may have an axial extension containing the outer coupling ring 4, and the driving member and its extension are supported in a stationary casing 3 by bearings 2, 7. The casing 3 and a seal 3.1 on the driving member 1 can form an oil chamber. <IMAGE>

Description

SPECIFICATION Torque transmission device This invention relates to a torque transmission device for transmitting torque from a driving member to a coaxial take-off member by way of a freewheel coupling, of which the outer ring coupling is connected to the driving member, the inner ring is disposed on the take-off member, and the gripping members are lifted from the outer ring by centrifugal force when the inner ring rotates.

Such devices are mostly used where two different drives have to be combined with each other, for example a fast-running main drive and a slow-running vernier drive. As the vernier drive must not be allowed to run with the main drive at the high rotational speed of the latter, it is known to couple the take-off member, which is connected to the main drive, to the driving member of the auxiliary drive by way of a freewheel device acting as an overrunning clutch. When the main drive is engaged, the take-off member is accelerated to a high rotational speed, and runs ahead of the vernier drive shaft, which is then decoupled and stops. Because of the construction of the freewheel gripping members, which are disengaged by centrifugal force, there is no contact in this overriding operating between the outer coupling ring and the gripping members.

A drawback of known constructions is that the bearings for the outer coupling ring are on the take-off member, and therefore have to rotate with the relatively high rotational speed of the take-off member when the take-off member is driven by the main drive. This is the case during about 90% of the operating time, so that the bearings are subjected to continuously high mechanical and thermal stress. In addition, these bearings have to of substantially smaller size than the main bearings for the take-off shaft, mainly because of space limitations. Their life is therefore short.

An object of the present invention is to provide a substantially low-wear design for the bearing arrangement for the outer coupling ring, and at the same time to eliminate previous lubrication and sealing problems.

The present invention provides a freewheel coupling assembly comprising a stationary casing; a take-off member forming or provided with the inner coupling ring of a freewheel coupling; a driving member coaxial with the take-off member, having a portion encircling the inner coupling ring and comprising the outer coupling ring of the freewheel coupling, the driving member being supported solely by the stationary casing; and gripping members between the coupling rings, arranged to be disengaged from the outer coupling ring by centrifugal force on rotation of the take-of member.

In a preferred construction the driving member comprises an axial extension containing the outer coupling ring, and the driving member and its extension are supported exclusively against a stationary coupling casing or against members flanged thereto.

The construction according to the invention has the advantage that the outer coupling ring is no longer supported, as previously, on the fast-rotating take-off shaft, but is instead supported by the stationary casing. This means that when the main drive is engaged, the bearings for the outer coupling ring are stationary, and are no longer subjected to any wear. In addition, there is the possibility of providing an oil screw in the coupling casing, which is easily accessible from the outside, whereas previously it was necessary to provide an oil well in the side of a flange ring of the outer freewheel ring, to which access could only be gained after dismantling other parts.Finally, the sealing arrangement is also simplified, as instead of the previous seal between the outer coupling ring and the fastrotating take-off shaft, only a seal between the slow-running drive shaft and the stationary coupling casing now needs to be used. The coupling casing can in this case be regarded as a single oil chamber.

An arrangement in which the driving member and its extension are supported by two radial bearings disposed at the two ends of the coupling provides a wide bearing base and thus optimum guiding for the driving member and its extension.

In a constructionally particularly simple form of the extension, the axial extension consists of flange rings fixed to the two ends of the outer coupling ring, and at least that flange ring disposed at the end of the coupling distant from the driving member carries a radial bearing. in this, the two flange rings can each comprise a radial bearing for their support against the coupling casing. However, an alternative, in which the driving member is supported directly in the coupling casing by way of a second radial bearing, is possible.

The driving member and take-off member are in most cases in the form of shafts, however hubs or coupling flanges are equally acceptable.

The extension containing the outer coupling ring can be connected to the driving member in any required manner. As a one-piece connection of the flange ring generally leads to a too high manufacturing cost, a screw or welded connection is mostly chosen.

Further details and characteristics of the invention will be apparent from the description of two embodiments given hereinafter with reference to the accompanying drawings, in which: Figure 1 is a longitudinal section through a first device according to the invention, and Figure 2 is a longitudinal section through a modification of the device of Fig. 1.

For easier understanding, like parts in Fig.

1 and 2 are given the same reference numerals. A drive shaft 1 is provided for connection to an auxiliary drive, not shown, and a takeoff shaft 9, coaxial thereto, can be driven at choice either by the drive shaft 1, or by a main drive, now shown. The shaft 1 comprises a hollow axial extension, which consists of a flange ring 4.2, welded at 4.4 to the shaft, a ring 4 forming the outer coupling ring of a freewheel coupling, and a flange ring 4.3. The two flange rings 4.2 and 4.3 are fixed to the ends of the outer coupling ring 4 by screws 4.1.

The shaft 1 and its axial extension are supported in a stationary coupling casing 3, by radial ball bearings 2 and 7. The ball bearing 2 is located directly on the shaft 1, whereas the ball bearing 7 is disposed on the outside of the flange ring 4.3. The coupling casing 3 is for example rigidly connected either to the (gear) casing 8 of the take-off shaft 9, or to the casing of the main drive (not shown) for the drive shaft 1.

The take-off shaft 9 is supported in the casing 8 by main shaft bearings, of which only that indicated by the reference numeral 10 is visible. The inner coupling ring 6 of the freewheel coupling is tightly fitted onto that end of the shaft 9 projecting from the casing 8, inside the hollow extension of the shaft 1 and radially spaced from the ring 4. Between the two rings there are the usual gripping members 5, which run in a gripping member cage 5.1. The gripping members 5 are so formed that above a certain rotational speed they lift from the outer ring 4 owing to the influence of the centrifugal force, and rotate with the inner ring 6 without rubbing.

During operation with the axuxiliary drive, the shaft 1 is driven, and drives the take-off shaft 9 by way of the outer ring 4, the gripping members 5 and the inner ring 6. The bail bearings 2 and 7 run at the relatively low rotational speed of the auxiliary drive. When the main drive is engaged, it accelerates the take-off shaft 9, either directly or by way of gearing not shown, so that the take-off shaft runs faster than the drive shaft 1 of the auxiliary drive. This overrunning is possible because of the operation of the freewheel coupling, which runs as an overrunning clutch. The auxiliary drive can then be decoupled, so that the drive shaft 1 and the members connected thereto stop. As the bearings 2 and 7 are supported, not by the take-off shaft 9, but by the stationary casing 3, the bearings 2 and 7 are not subjected to wear during the main operating time of the installation.

Instead of the previously necessary gasket between the outer coupling ring 4 and the take-off shaft 9, a seal 3.1 is provided between the casing 3 and drive shaft 1. This is subjected only to low wear due to the low rotational speed of the drive shaft 1, and also has the advantage that the casing 3 together with the seal 8.1 of the shaft 9 forms an oil compartment sealed against the housing, so that the bearings can be lubricated in a simple manner by way of an oil screw 11 in the top of the casing.

Fig. 2 differs from Fig. 1 firstly in that two sets of gripping members 5 are disposed adjacent to each other between the outer ring 4 and inner ring 6 of the freewheel coupling so that a higher torque can be transmitted from the auxiliary drive to the take-off shaft 9.

In addition, the auxiliary drive is not by way of a shaft, but by way of a coupling flange 1.1, which is screwed to the left hand flange ring 4.2. Correspondingly, the casing seal 3.1 is disposed against a projecting collar on the coupling flange.

A further difference with respect to Fig. 1 is that support for the driving coupling flange 1.1 is provided not only by the flange ring 4.3, but also by the flange ring 4.2, the ball bearing 2 being disposed between the flange ring 4.2 and the casing 3.

Both embodiments have the substantial advantages that during the main operating time of the installation, i.e. when operated by the main drive, no wear occurs in the coupling bearing system, the bearing lubrication is simplified and the seal arrangement is free from wear.

Claims

1. A freewheel coupling assembly comprising a stationary casing; a take-off member forming or provided with the inner coupling ring of a freewheel coupling; a driving member coaxial with the take-off member, having a portion encircling the inner coupling ring and comprising the outer coupling ring of the freewheel coupling, the driving member being supported solely by the stationary casing; and gripping members between the coupling rings, arranged to be disengaged from the outer coupling ring by centrifugal force on rotation of the take-off member.

2. A device for transmitting torque from a driving member to a coaxial take-off member by way of a freewheel coupling, of which the outer ring is connected to the driving member, the inner ring is disposed on the take-off member, and the gripping members can be lifted from the outer ring by centrifugal force when the inner ring rotates, characterised in that the driving member comprises an axial extension containing the outer coupling ring and the driving member and its extension are supported exclusively against a stationary coupling casing or against members flanged thereto.

3. A device as claimed in claim 2, characterised in that the driving member and its extension are supported by two radial bear ings disposed at the two ends of the coupling.

4. A device as claimed in claim 2 or 3, characterised in that the axial extension consists of flange rings fixed to the two ends of the outer coupling ring, and of which at least that flange ring disposed at that end of the coupling distant from the driving member carries a radial bearing.

5. A device as claimed in any one of the preceding claims 2 to 4, characterised in that the driving member is supported directly in the coupling casing by way of a second radial bearing.

6. A device as claimed in any one of the preceding claims 2 to 5, characterised in that the driving member and take-off member are both shafts.

7. A device as claimed in any one of claims 2 to 5, characterised in that the driving member is a coupling flange.

8. A device as claimed in any one of the preceding claims 2 to 7, characterised in that the coupling casing comprises an oil screw accessible from the outside.

9. A device as claimed in any one of the preceding claims 2 to 8, characterised in that the coupling casing is flanged to a gear casing of the take-off member.

10. A device as claimed in any one of the preceding claims 2 to 9, characterised in that instead of a gasket between the outer ring and take-off member, a gasket is provided between the coupling casing and driving member.

11. A torque-transmitting device substantially as herein described with reference to Fig. 1 or Fig. 2 of the accompanying drawings.