The present invention relates to a clutch for coupling two shaft sections of a drive shaft, in particular of the drive shaft of a marine screw propeller which is alternativelydrivable by a main engine which is preferably embodied by a two-stroke large diesel engine or an auxiliary engine which is preferably embodied by an electric motor, wherein the shaft sections support an inner and an outer clutch ring coplanar thereto and wherein the clutch rings are provided with notches in the area of the facing circumferential surfaces which in a congruent position complement one another to preferably conical bores into which hydraulically moveable, preferably conical clutch bolts, which are actuatable by means of a common annular servopiston, can be inserted for fixedly connecting the clutch rings to one another for common rotation.
A clutch of this kind is disclosed in published German patent application 197 56 420. In this arrangement, the clutch bolts are not only hydraulically inserted and retracted but also held in the inserted position by hydraulic oil. During the entire time of insertion, it is therefore required to supply hydraulic oil. Due to the simultaneously occurring rotational movement of the shaft, leakage losses cannot be prevented in this context. Therefore, a comparatively large expenditure is required in order to maintain a sufficient pressure and to compensate the leakage losses. Moreover, the leaking oil results in contamination of the environment.
Based on this it is therefore an object of the present invention to improve a clutch of the aforementioned kind with simple and cost-efficient means such that the clutch bolts can be mechanically locked in the inserted position.
This object is solved according to the present invention in that a support ring bridging the gap between the two clutch rings is provided on the side of the clutch rings positioned opposite the bolts, from which tie rods, which can be extended by a second annular servopiston and cooperate with a locking ring assigned to the clutch bolts, project offset to the clutch bolts, wherein the locking ring, in the extended position of the tie rods, can be brought from a position in which it secures the clutch bolts in the inserted position into a position releasing the clutch bolts, and in that the two servopistons, which are movable hydraulically away from one another and toward one another, are arranged in an annular chamber of a housing connected to one of the shaft sections and engaged from behind by the locking ring.
With these measures, the disadvantages described at the outset are eliminated in a simple and inexpensive manner. With the aid of the locking ring the clutch bolts can be locked in the inserted position which ensures high reliability. After locking, the hydraulic oil loading is no longer necessary. Only a lubricant oil loading is required. Leakage losses are therefore not to be expected. This ensures in a simple manner a long disruption-free operation. For rotating the locking ring, the tie rods bearing it are simply tensioned by the corresponding servopiston and thus extended. The tie rods function accordingly as springs which hold together the locking ring and the support ring oppositely positioned thereto with the force exerted by these springs. The support ring resting with this force against the two clutch rings furthermore ensures that the two clutch flanges are exactly aligned so that the clutch bolts are effective over their entire length. Moreover, in the case of a conical configuration of the clutch bolts, it is ensured that in the desired congruent position precise conical bores correlated with the clutch bolts result into which the conical clutch bolts can be reliably inserted. The measures according to the present invention ensure accordingly also a high user-friendliness and operational safety.
The clutch bolts can have advantageously a respective shaft, that is fastened to the correlated servopiston, penetrates the second servopiston with a degree of freedom of movement, extends from the housing to the rear, and cooperates with the locking ring being provided with bores correlated with the shafts of the clutch bolts and being provided with arcuate slots correlated with the tie rods that penetrate the first servopiston with a degree of freedom of movement, project from the housing, and penetrate the arcuate slots. These measures ensure that the externally positioned locking ring can be rotated only when the tie rods are tensioned and, at the same time, the shafts of the clutch bolts are retracted therefrom, i.e., the clutch bolts are in the inserted position, which ensures especially high safety and clear operation.
A further advantageous measure can reside in that the tie rods penetrating the first servopiston with a degree of freedom of movement have a respective rearwardly arranged threaded portion on which at least one securing nut can be received that can be brought into contact at the locking ring. In this way, the spacing of the locking ring from the second servopiston and thus the effective tension and the achievable movement play can be adjusted in a simple manner.
Expediently, the second servopiston serving to tension the tie rods can be provided with a groove which can be closed off by a cover and in which follower nuts respectively screwable onto a correlated threaded portion of the tie rods are received. This allows in a simple manner an adjustment of the desired extension length of the tie rods and thus of the achievable securing forces.
In a further development of the primary measures the second servopiston for tensioning the tie rods can be lifted from a stop arranged between the two servopistons counter to a return spring arrangement. The return spring arrangement provides even in the pressureless state a certain lifting of the support ring relative to the clutch rings which can have a favorable effect with regard to preventing wear.
Further advantageous embodiments and expedient developments of the primary measures are disclosed and can be taken in more detail from the following description of an embodiment with the aid of the drawings.