GB2174770A - Bulkhead seal - Google Patents

Abstract

A bulkhead seal for a rotating shaft (1) which can be activated when required contains preferably two radial slide rings (12, 13) composed of segments which can be pressed against the shaft by a pressing element (30). The slide ring segments are held ready in a position in which they are lifted away from the shaft by laterally disposed pressure members (20, 21). The slide rings become broader in the direction towards the outer periphery. The inclined ring surfaces (17, 18) which result from this broadening are contacted by the preferably ring like pressure members (20, 21) with corresponding inclined contact surfaces. The pressure members are urged into contact by springs (22). The pressure members and slide rings are secured against rotation. An inflatable hose is preferably used as the pressing element (30). <IMAGE>

Description

SPECIFICATION Bulkhead seal The invention relates to a bulkhead seal which can be activated when required, with the bulkhead seal being provided for a rotatable shaft which extends through a bulkhead which can be sealed in watertight manner, or through a similarwall between two chambers, in particular in a ship.

The sealing function of a bulkhead seal is normally first required in a special case in which for example water penetrates with a certain pressure into one of the two chambers, while, for example, the drive shaft for the propeller which extends through this chamber can still be turned. In normal operation the bulkhead seal should be inoperative if possible, in order to avoid wear and spare lubrication, servicing etc.

The invention is thus based on the problem of providing a bulkhead seal which can be activated when required to seal against the shaft against medium flowing from one side or the other of the bulkhead wall along the shaft.

A seal arrangement with a radial slide ring which consists of partially overlapping segments which are pressed against the shaft by a distendible body which surrounds the segments is known from German laying open print DE-OS 31 43866.

In accordance with the invention at least one radial slide ring of this kind composed of segments which can be pressed by radially acting pressing elements against the shaft is used as the bulkhead seal. In addition however provision is made for arranging pressure members in the housing which act on the segments from the side and which hold the segments back in a position of readiness in which they do not have any contact with the shaft and from which they can only displaced radially inwardly when the need arises. The pressure members are preferably movable approximately parallel to the shaft and are resiliently pressed against the segments.The force exerted by the pressure members on the segments, which holds the segments back out of contact with the shaft, is counteracted when the pressing element or elements acting on the segments are actuated to press them into contact with the periphery of the shaft.

In preferred embodiments the radial slide ring becomes broader in the direction towards its outer periphery so that, at the side, at least one inclined ring surface at the radial end face of the segments has an angle of inclination and the pressure memberms which act at the sides have inclined contact surfaces in the same manner. If the segments are pressed against the shaft they are able to push back the pressure members which are resiliently pressed into contact with the segments. If the pressing force exerted by the actuable pressing element or elements is counteracted or removed, for example after a functional check, then the pressure members push the segments outwardly again.

Two radial slide rings which contact one another and are jointly radially displaceable are preferably used. With this arrangement inclined ring surfaces and corresponding pressure members are expediently provided on both sides of the slide ring pair.

A pneumatic or hydraulically inflatable hose-like distendible body which surrounds the segments at their outer periphery is preferred at the pressing element.

In other embodiments of the invention a permanently present pressing force can also be present, for example prestressed springs, and the pressure members are drawn apart mechanically to activate the seal in order to make the displacement of the segments possible.

Further particulars will be described with reference to the preferred embodiments which are shown in simplified form in the drawings.

Figure 1 shows a section through a part of a bulkhead seal in the position of readiness, Figure 2 shows a section which is however somewhat displaced relative to Figure 1 of a similar bulkhead seal with the radial slide rings in the sealing position.

The shaft 1,which can for example be a drive shaft (propeller shaft) of a ship, and which can have a diameter which amounts to between 50 and 1500 mm, extends through an opening in the bulkhead wall 2. The bulkhead seal is inserted into the opening and secured to the wall 2.

The housing of the seal consists of a flange ring 10 and a housing ring 11. The seal contains two radial slide rings 12,13 in an annular chamber 14 which are composed of a plurality of segments which respectively overlapped the inner periphery. Moreover, the separating joints for the two slide rings are expediently displaced relative to one another. Despite the separating joints which are necessary for the radial contraction no liquid can seep between the segments when they are acted on by pressure on one side. The slide rings 12, 13 are formed of carbon or synthetic material (plastic). They have parallel radial end surfaces 15, 16 which are adjoined by inclined ring surfaces 17,18 which project towards the outer periphery 19. The side surfaces 15, 16 are guided during the radial displacement of the segments by parallel housing surfaces 14a of the annular chamber 14.Pressure members 20, 21 are pressed against the inclined ring surfaces 17, 18 and have a correspondingly inclined surface. The inclination of the ring surfaces 17, l8amountsto 10to30and are preferably to 15 relative to the plane of the radial surfaces 15,16.

Pressure springs 22 are provided at the pressure members 20, 21 as has been shown for the pressure member 21 in Figure 1. The pressure members 20, 21 can be of annular shape and accommodated in annular grooves 23,24 so that they are displaceable in the axial direction. The annular grooves 23,24 are so constructed that they enlarge the outer part of the annular cavity l4to such an extent that the slide rings 12, 13 which are broader in their outer region can be displaced inwardly to an adequate degree.

The pressure members and slide rings are secured against rotation in the annular housing chamber 14.

For this purpose at least one screw 25 can be screwed into place inwardly in the housing ring 11 so that it penetrates into a groove 26 of the pressure member 20. Moreover, as shown in Figure 2, the pressure members 20, 21 are connected by pins 27 which extends through elongated slots 28 in the slide rings 12, 13. The pins 27 do not permit any movement of the segments in the peripheral direction. The elongate holes are however so arranged that the segments remain radially displaceable.

In the illustrated preferred embodiment a hose-like resilient inflatable body 30 which can be expanded against the outer periphery 19 of the slide rings is used as the pressing element. The inflatable body 30 is arranged in an outer peripheral groove of the annular chamber 14 and is held by an inserted ring 31. A hydraulic or pneumatic medium is introduced into the inner chamber 32 of the inflatable body 30 via a feed line 33 (Figure 1) when it is desired to activate the bulkhead seal. If the inflatable body 30 is subjected to internal pressure it displaces the segments radially inwardly with the inclined surfaces 17,18 pushing the pressure members 20,21 apart like a wedge. During this the slide ring segments are guided by the parallel sides 14a of the annular chamber 14.A seal between the chambers on the two sides of the bulkhead wall 2 along the shaft is generated by the contact of the inner periphery of the slide ring segments against the shaft. In this arrangement the chamber into which for example water has penetrated, so that the use of the seal was necessary, is immaterial. Should a deformation have occurred, for example of the bulkhead wall, due to a pressure difference between the chambers or due to other causes which lead to the shaft no longer extending centrally through the seal housing then this eccentricity and also any radial oscillations are compensated for the by inflatable body without the sealing action being impaired. Moreover, the inflatable body also leads to a seal at the outer periphery 19 of the slide rings.

Small endless spiral springs 36 can be arranged in grooves at the outer periphery 19 of the slide rings 12, 13 as shown in Figure 1. These springs merely facilitate the assembly of the composite slide rings.

Their force is in no way sufficient to press the pressure members apart and to retain the slide rings in a sealed position.

Round ring seals can be inserted into grooves in the parallel walls 14a of the annular chamber 14 as seals between the housing parts 10, 11 and the radially outer surfaces 15, 16. These seals seal the outer part of the annular chamber 14 in particular in the position of readiness. They have no real signifi canoe when the bulkhead seal has been activated.

All parts of the bulkhead seal which surround the shaft 1 expediently consist of two or more parts so that assembly of a seal arrangement can also take place after installation of the shaft.

Although an arrangement is shown in Figures 1 and 2 which embodies two contractible and expandible segmented slide rings it will be understood that it is possible to use a single radially contractible and expansible segmented slide ring. With one such slide ring pressure members are preferably, but not, necessarily arranged at both sides thereof.

Claims (8)

1. Bulkhead seal for a shaft, the seal consisting of at least one radial slide ring composed of overlapping segments and a pressing element which surrounds the segments and presses them, when required, radially against the shaft, with the radial slide ring and the pressing element being arranged in a housing, characterised in that pressure members (20, 21) which act on the segments at the side and which hereby hold them in a position of readiness lifted away from the shaft (1) are arranged at at least one side of the radial slide ring (12, 13).

2. Bulkhead seal in accordance with claim 1,characterised in that the radial slide ring (12, 13) becomes broader in the direction towards its outer periphery (19), with inclined ring faces (17,18) adjoining parallel radial side faces (15,16); and in that these inclined ring faces (17, 18) are contacted by spring loaded pressure members (20, 21)which are displaceable parallel to the shaft (1) and have correspondingly inclined contact surfaces.

3. Bulkhead seal in accordance with claim 2, characterised in that the spring force at the pressure members (20,21) and the inclination of the ring surfaces (17, 18) are so designed that the pressure member (20,21) are pushed backwardly by the force of the pressing element (30) acting on the periphery of the radial slide ring (12, 13).

4. Bulkhead seal in accordance with claim 3, characterised in that two radial slide rings (12,13) are arranged directly alongside one another in an annular chamber (14).

5. Bulkhead seal in accordance with claim 3 or claim 4, characterised in that inclined ring surfaces (17, 18) and pressure members (20,21) are arranged at both sides of the radial slide rings (12, 13).

6. Bulkhead seal in accordance with one of the claims 2 to 5, characterised in that the annular chamber (14) for receiving the radial slide rings (12, 13) has parallel housing surfaces (14a) in the housing (10, 11) for guiding the radial end faces (15, 16) and becomes broader in the outward direction so that a radial movement of the ring surfaces (17, 18) which make the slide rings wider is possible.

7. Bulkhead seal in accordance with one of the claims 1 to 5, characterised in that a resilient distendable body (30) which can be inflated in the radially inward direction of a medium is arranged as the pressing element in an annular groove surrounding the radial slide ring (12, 13).

8. Bulkhead seal substantially as herein described with reference to and as illustrated in the accompanying drawings.