GB2045875A - Seals - Google Patents

Abstract

A rotatable seal arrangement of the radial face type for the outboard end of a ship's propeller shaft is an improvement of the kind described in British Patent Specification No. 1 522 739. The improvement comprises replacement of a single resilient cushion ring of complex design by a plurality of simple rings 6, 7 such as O-rings. The combination of springs 9 and resilient rings 6, 7 urging the seal faces into contact may be carried alternatively by the propeller hub or the ship's structure. <IMAGE>

Description

SPECIFICATION Improvements in or relating to propeller shaft seals The present invention relates to rotatable seal arrangements of the radial face type suitable for the outboard end of a ship's propeller shaft to prevent shaft bearing lubricant from escaping to outboard and outboard water from entering the bearing and of the kind comprising at least two concentric seals, one for the bearing lubricant and one for the outboard water, these radial face type seals separated by an annular channel with a drain connection into the ship, the sliding sealing contact between the seal faces being maintained by pressure in an axial direction from a combination of at least one resilient cushion ring and a plurality of springs.

Such a seal arrangement is herein referred to as of the kind specified and one particular form is described in British Specification No. 1 522 739.

The particular seal arrangement as described in the said Patent Specification contains one resilient cushion ring the shape of which is of some complexity giving rise to manufacturing problems. In the said Specification the combination of cushion ring and springs is located adjacent to the propeller hub non-rotatable in relation thereto.

It is an object of this invention to alleviate the said manufacturing problems by providing a shaft seal arrangement of the kind specified in which cushion rings are of a less complex design such as the O-ring type and in which there is an alternative location for the said combination.

The present invention consists in a shaft seal arrangement of the kind specified in which resilient cushion rings are of the O-ring type or similar and the combination of cushion rings and springs is located adjacent to the propeller hub or alternativeiy to the ship's structure.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 shows an axial section of the shaft seal arrangement of the kind specified with O-ring type cushion rings according to this invention, the said combination of cushion rings and springs connected to the propeller hub.

Figure2 shows an axial section of the shaft seal arrangement of Figure 1 according to this invention with the combination of the cushion rings and springs connected to the ship's structure.

Referring to Figure 1, the drawing shows part of the propeller shaft 1 with an axial section of the propeller hub 2 and a sectional elevation of part of the shaft bearing closing plate 3 which is nonrotatable secured to the ship's hull structure.

Secured fluid-tight to plate 3 is a stationary seal element 4 which contains two concentric seal face rings.

Facing element 4 is a rotatable seal element 5 containing two concentric seal face rings the faces of which are in sliding sealing contact with the seal faces of element 4.

The rotatable seal element 5 is resiliently supported and pressed in axial direction towards element 4 by a combination consisting conveniently of two O-ring type cushion rings 6 and 7, a spring carrier ring 8 and a plurality of springs 9, the springs being accommodated in pockets arranged in ring 8.

The said combination is allowed axial movement in the annular recess between a ring 10 and the radially split ring 11 whereby the cushion rings 6 and 7 prevent water or bearing lubricant from entering space 12.

Space 12 has communication by way of the orifices 13 and 14 with a drain connection 15 leading into the ship.

A driving pin 16 ensures that the seal element 5 rotates with the propeller and the shaft 1.

An opening 17 in the carrier ring 8 is provided for every spring for securing by insertion of locking pins the springs when required for installation or servicing the seal arrangement without having to remove the propeller from the shaft.

The seal face rings, cushion rings 6 and 7 and the carrier ring 8 may be radially split in order to facilitate installation or servicing of the seal arrangement without having to remove the propeller.

The flange on ring 10 gives a radial support to the springs and provides accurate concentric location for ring 11.

Referring to Figure 2, the drawing shows the combination of O-rings and springs non-rotatable connected to the ship's hull structure.

Parts having essentially the same function as those in the arrangement of Figure 1 are provided with the same reference numerals in Figure 2 but the latter have one apostrophe.

The rings 10' and 11' are now secured to the shaft bearing closing plate 3' and seal element 4' to the propeller hub 2'.

Leakage from the seal faces will drain through the orifices 13' and 14' and the drain connection 15' into the ship.

The pin 16' renders seal element 5' and the combination of the cushion rings and springs nonrotatable.

1. A shaft seal arrangement of the kind specified in which resilient cushion rings are of the O-ring type or similar.

2. A shaft seal arrangement according to claim 1 in which the combination of resilient cushion rings and springs is located adjacent to the propeller hub or alternatively to the ship's structure.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (2)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in or relating to propeller shaft seals The present invention relates to rotatable seal arrangements of the radial face type suitable for the outboard end of a ship's propeller shaft to prevent shaft bearing lubricant from escaping to outboard and outboard water from entering the bearing and of the kind comprising at least two concentric seals, one for the bearing lubricant and one for the outboard water, these radial face type seals separated by an annular channel with a drain connection into the ship, the sliding sealing contact between the seal faces being maintained by pressure in an axial direction from a combination of at least one resilient cushion ring and a plurality of springs. Such a seal arrangement is herein referred to as of the kind specified and one particular form is described in British Specification No. 1 522 739. The particular seal arrangement as described in the said Patent Specification contains one resilient cushion ring the shape of which is of some complexity giving rise to manufacturing problems. In the said Specification the combination of cushion ring and springs is located adjacent to the propeller hub non-rotatable in relation thereto. It is an object of this invention to alleviate the said manufacturing problems by providing a shaft seal arrangement of the kind specified in which cushion rings are of a less complex design such as the O-ring type and in which there is an alternative location for the said combination. The present invention consists in a shaft seal arrangement of the kind specified in which resilient cushion rings are of the O-ring type or similar and the combination of cushion rings and springs is located adjacent to the propeller hub or alternativeiy to the ship's structure. An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 shows an axial section of the shaft seal arrangement of the kind specified with O-ring type cushion rings according to this invention, the said combination of cushion rings and springs connected to the propeller hub. Figure2 shows an axial section of the shaft seal arrangement of Figure 1 according to this invention with the combination of the cushion rings and springs connected to the ship's structure. Referring to Figure 1, the drawing shows part of the propeller shaft 1 with an axial section of the propeller hub 2 and a sectional elevation of part of the shaft bearing closing plate 3 which is nonrotatable secured to the ship's hull structure. Secured fluid-tight to plate 3 is a stationary seal element 4 which contains two concentric seal face rings. Facing element 4 is a rotatable seal element 5 containing two concentric seal face rings the faces of which are in sliding sealing contact with the seal faces of element 4. The rotatable seal element 5 is resiliently supported and pressed in axial direction towards element 4 by a combination consisting conveniently of two O-ring type cushion rings 6 and 7, a spring carrier ring 8 and a plurality of springs 9, the springs being accommodated in pockets arranged in ring 8. The said combination is allowed axial movement in the annular recess between a ring 10 and the radially split ring 11 whereby the cushion rings 6 and 7 prevent water or bearing lubricant from entering space 12. Space 12 has communication by way of the orifices 13 and 14 with a drain connection 15 leading into the ship. A driving pin 16 ensures that the seal element 5 rotates with the propeller and the shaft 1. An opening 17 in the carrier ring 8 is provided for every spring for securing by insertion of locking pins the springs when required for installation or servicing the seal arrangement without having to remove the propeller from the shaft. The seal face rings, cushion rings 6 and 7 and the carrier ring 8 may be radially split in order to facilitate installation or servicing of the seal arrangement without having to remove the propeller. The flange on ring 10 gives a radial support to the springs and provides accurate concentric location for ring 11. Referring to Figure 2, the drawing shows the combination of O-rings and springs non-rotatable connected to the ship's hull structure. Parts having essentially the same function as those in the arrangement of Figure 1 are provided with the same reference numerals in Figure 2 but the latter have one apostrophe. The rings 10' and 11' are now secured to the shaft bearing closing plate 3' and seal element 4' to the propeller hub 2'. Leakage from the seal faces will drain through the orifices 13' and 14' and the drain connection 15' into the ship. The pin 16' renders seal element 5' and the combination of the cushion rings and springs nonrotatable. CLAIMS

1. A shaft seal arrangement of the kind specified in which resilient cushion rings are of the O-ring type or similar.

2. A shaft seal arrangement according to claim 1 in which the combination of resilient cushion rings and springs is located adjacent to the propeller hub or alternatively to the ship's structure.