GB2256238A

GB2256238A - Sealing rotating shafts particularly ship propeller shafts

Info

Publication number: GB2256238A
Application number: GB9211108A
Authority: GB
Inventors: Guenter Pietsch; Bergen Ernst-Peter Van
Original assignee: Blohm and Voss GmbH
Current assignee: Blohm and Voss GmbH
Priority date: 1991-05-25
Filing date: 1992-05-26
Publication date: 1992-12-02
Anticipated expiration: 2012-05-26
Also published as: RU2041133C1; KR100227524B1; GB2256238B; KR920021903A; DE4117097C2; SE505762C2; JPH0694139A; SE9201586L; CN1032714C; SE9201586D0; DE4117097A1; GB9211108D0; CN1067300A

Description

1 -) 23 b -Z -3 3 Sealing AiDparatus for Rotating Shafts, in Particular

Stern Tube Seal for Ship's Propeller shafts The invention relates to a sealing apparatus for rotating shafts, in particular a stern tube seal for ship's propeller shafts, with the features of the preamble of claim 1.

In the sealing devices of this kind which have become known from DE-OS 40 28 048 (German patent application P 40 28 048.9 equivalent to UK 9118103. 2) the hollow space system comprises a single annular inflatable body which is inserted flush into a ring space between the guide body and the stuffing box ring.

With these seal devices the danger exists of the entire reserve seal failing in the event of a leak occurring at the single pressure body.

The invention is based on the object of overcoming this difficulty and solves this object in that the single pressure body is replaced by a plurality of individual pressure bodies uniformly distributed over a circle concentric to the shaft axis and thus to the stuffing box ring, with each pressure body being formed as an individual piston-in-cylinder unit with which there is 2- in case associated a respective branch flow of the hydraulic or pneumatic pressure medium.

Through this subdivision of the single pressure body into a plurality of independent pressure bodies the operation of the reserve seal continues even when one or other of the individual pressure bodies becomes leaky, for example by failure of the ring seal between the piston and cylinder of the piston-in-cylinder unit.

The subject of the invention is illustrated in the drawing with reference to an embodiment. There are shown:

Fig. 1 a seal device in accordance with the invention in longitudinal section, Fig. 2 a cross-section along A-A in Fig. 1.

2 designates a part of the outer skin of a ship's hull which contains an opening 3 for the passage of a ship's shaft 4 which leads from the propulsion engine to the propeller, with a running sleeve 4a being attached to the ship's shaft. A seal arrangement 5 with a multi-part carrier system 5, Sa, 5b secured to the outer skin 2 and containing a main seal 6 and also a reserve seal 8 serves for the sealing of the ship's shaft 4 or of the running sleeve 4a relative to the external water W.

The main seal 6 is formed as a slide ring seal and is accordingly equipped in customary manner with a slide ring 6c which is clamped between a ring 6a connected to the running sleeve 4a and a counter-ring 6b connected to the carrier system. In addition, in the illustrated embodiment, the main seal 6 is equipped with an inflatable static auxiliary seal 7 which can be activated when required by a pressure medium. The reserve seal 8 serves on failure of the main seal 6 as an emergency seal and is equipped as a stuffing box seal with a stuffing box ring 13 and with soft packings 14. The stuffing box ring 13 is axially displaceable relative to a ring-like guide body 11 which is rigidly connected via a distance piece 10 with the carrier system Sa, 5b. The distance piece in the present case is formed as a threaded bolt fixed at one end by a thread in the part 5b and fixed at its other end by a further thread in a nut 9a. In practice two or three or more preferably distributed uniformly around the axis of the propeller shaft 4. The stuffing box ring 13 is provided at the outside with a ring flange 13a in which a plurality of cylindrical recesses 13b is expediently formed, in the present embodiment eight cylindrical recess 13b, with the recesses being distributed uniformly around a circular line. The guide body 11 is provided with a corresponding number of pistons lib inserted into cylindrical recesses lla, thus in the present case with eight pistons lib which cooperate with the recesses 13b in the form of piston-cylinder units.

A branch line 17a of a pressure line 17 is in each case introduced into the cylinder spaces of these piston-in-cylinder units and the pressure line 17 is connected to a pressure source 18 for a hydraulic or pneumatic pressure medium. The pressure line 17 is furthermore attached to a pressure line 19 which opens in the external water W and into which a pressure control member 15 is inserted which operates in such a way that with increasing pressure of the external water W the pressure of the pressure medium rises accordingly and vice versa. A resetting device 16 is furthermore inserted between the carrier system 5a, 5b and the ring flange 13a of the stuffing box ring 13 and consists of at least one coil spring 16a and a push rod 16b which cooperates therewith, with the coil spring 16a being journalled in the carrier system 5a, 5b and with the push rod 16b being connected at its free end to the ring flange 13a. The resetting force of the coil spring 16a is so dimensioned, that on a reduction of the pressure of the pressure medium it in each case moves the stuffing box ring 13 into the release position and thus relieves its soft packings 14. Furthermore, a positioning device 9 is present which is inserted between the guide body 11 and the distance piece 10 and which consists of a threaded nut 9a which is rotatably but axially non-displaceably mounted in a recess of the guide body 11 and cooperates with the distance piece 10 by means of a thread 10a.

:i This manually actuatable positioning device serves, on the one hand, as a security if the inflation body becomes leaky or on failure of the pressure source, but, on the other hand, also as an adjusting device for the basic position of the entire reserve seal system.

4 P a t e n t

Claims

C 1 a i m

Sealing device for rotating shafts, in particular a stern tube seal for ship's propeller shafts with or without a shaft sleeve comprising sealing rings aligned with and contacting the shaft and arranged in a stationary carrier system, preferably a slide ring seal, and with a reserve seal arranged in the carrier system, the reserve seal being formed as a stuffing box seal with soft packings and a stuffing box ring displaceable in the axial direction in a guide body connected to the carrier system, with a hollow space system being inserted between the guide body and the stuffing box ring into which a hydraulic or pneumatic pressure medium can be introduced on failure of the main seal, which activates the reserve seal, characterised in that the hollow space system comprises a plurality of individual piston-in-cylinder units (11, 11b, 13) uniformly distributed around a circle concentric to the shaft axis and with each of which there is associated a respective branch flow (17a) of the hydraulic or pneumatic pressure medium.
2. Sealing device in accordance with claim 1, wherein said piston-incylinder units are formed in a carrier member (11) spaced from a housing (5b) of said main seal (6) via spacer means (10) of adjustable length.
3. Sealing device in accordance with claim 2, wherein said spacer means (10) comprises at least one threaded bolt fixed at one end to said housing (5b) and engaging at the other end in a thread in a nut member, said nut member being rotatable relative to said carrier member (11) but substantially nondisplaceable relative thereto in an axial direction.

A 1 1
4. Sealing device in accordance with any one of the preceding claims wherein spring means is provided for returning the axial position of the stuffing ring on venting of the piston-in-cylinder units.
5. Sealing device in accordance with any one of the preceding claims wherein means is provided for varying the pressure which can be applied to said piston-in-cylinder units in dependence on the external water pressure at the level of the propeller shaft.
6. Sealing device substantially as herein described with reference to and as illustrated in the accompanying drawings.