CONDUIT COUPLING

Abstract: Sealing between two parts (1,2) of a conduit coupling which are rotatable with respect to each other and between which there exists a small clearance and in which the medium flowing through the conduits is sealed with respect to the environments by means of sealing rings (12,13) present in grooves (10,11) on both sides of the medium to be sealed, said sealing having on each side of the medium conduit a groove (10,11) with two sealing rings (12,13), said groove having a width which is larger than the space taken by the two sealing rings, which sealing rings are U-shaped in cross-section and placed inside each groove with the openings towards each other, the space (16) between said rings (12,13) being filled with a liquid under pressure which pressure is higher than the pressure of the medium to be sealed, which liquid can have a higher viscosity than the viscosity of the medium.

Description: Seal between two parts of a conduit coupling which are rotatable with respect to each other. The invention relates to a seal between two parts of a con duit coupling which are rotatable with respect to each other, which parts have surfaces movable with respect to each other and between which there exists a small clearance which is sealed by means of one or more sealings which are placed inside a groove in one of the surfaces or in both surfaces of the mutually rotatable parts, which seal is present at both sides of a channel through which the medium flows which has to be sealed. A seal of this type is known from many publications such as published NL-A-7812499 (= EU-A-79200794,0), French patent specification 2,298,757 or US patent specification 3,698,433. In all said known sealings rings of flexible material are clamped between said parts. Rotatable conduit couplings such as, e.g. used in mooring devices, very often have to allow the passage of media having a relatively high pressure. If the medium is a gas under high pressure the known seals are not satisfactory and there is a large risk of leakage Purpose of the invention is to provide a seal which gives an excellent sealing of the medium under high pressure with respect to the environment within which the conduit coupling functions. According to the invention this purpose is achieved in that each groove contains two sealing rings and has a width which is larger than the width taken by the two sealing rings inside the groove and the space between the two sealing rings is connected to a source of liquid the pressure of which is larger than the pressure of the medium which has to be sealed, said sealing rings in principle having a U-shaped cross-section and are placed within the groove with the openings turned twoards each other. The seal according to the invention is based upon the principle that the medium of the channel that has to be sealed and which through one of the sealing rings tries to enter the space between the two sealing rings in which space there is a higher liquid pressure meets said liquid of higher pressure, which liquid prevents the medium from entering as a result of its higher pressure and eventually higher viscosity. Said liquid, moreover, operates as a lubricant for the sealing rings. The consideration holds true in this respect that it is not disadvantageous if a little bit of the liquid from the seal enters the medium guided by the conduit, but that on the contrary nothing of said medium may reach the environment. Preferably the liquid in the groove of the seal has a larger viscosity than the medium to be sealed. This improves the sealing. By the U-shaped cross-section of the sealing rings placed inside the grooves such that they face each other with their openings the liquid will press the legs of said U-shaped sealing rings against the walls of the groove and against the surface to be sealed. Another cross-sectional shape having lips engaging the surfaces to be sealed has the same effect. It is observed that inflatable seals or seals which can be filled by means of a pump are known in many forms e.g. from UK specification 257,688 or US patent specification 3,642,291. With all known inflatable seals the seal engages the surface to be sealed by means of a closed wall. A seal comprising an inflatable endless hose has, however, the disadvantage that if applied in sealing against a gas under high pressure a leakage once occurred remains until the pressure is blown off sufficiently, whereas this cannot happen with-the seal according to the invention. According to the invention a ridge can be present inside the space between the two sealing rings in each groove, said ridge having the supplied channel for the supply of liquid under high pressure to the space and dividing the groove into two chambers one for each sealing ring. This always ensures the proper position of the sealing rings. The invention now will be furthr elucidated with reference to the drawings. Fig. 1 shows in cross section one embodiment of the seal according to the invention. Fig. 2, 3 and 4 in cross-section show different locations of the seal according to the invention. The conduit coupling shown in Fig. 1 comprises a stationary part 1 and a rotatable part 2. The parts 1 and 2 are supported upon each other by means of non-shown axial radial bearings. Both parts 1 and 2 are provided in the opposite cylindrical surfaces 3 and 4 respectively with circumferentially extending recesses 5 and 6 respectively which form a circumferentially extending channel 7. Part 1 has a conduit connection 8 extending through the center of the coupling and part 2 has a radially outwardly extending conduit connection 9. At both sides of the conduit connection 8, 9 the rotatable part 2 has been provided with a groove 10 and 11 respectively of rectangular cross-section. In both grooves there are sealing rings 12 and 13 respectively of U-shaped cross-section, which with one leg 14 engage the inner wall of the rectangular groove and with the other leg 15, eventually extending a little bit outside the groove, lie against the outer cylindrical surface 3 of the stationary part 1. Said sealing rings 12, 13 form a closed chamber 16 with the wall 3 against which the outer ends 15 are in contact, which chamber is connected to a conduit 17 which is connected to a not-shown source of liquid under pressure. This liquid under pressure inside the chamber 16 presses the sealing rings 12 and 13 respectively at their place and with the outer ends 14 and 15 against the inner wall 10 and against the wall 3 respectively against which the sealing has to take place. Between the outer ends of the lips 15 this liquid, such as oil or water, is in contact with the outer surface 3 of part 1 against which sealing has to take place. The embodiment shown in figure 2 comprises a stationary tube 19 having a flange 20 and a tube 21 with flange 22 rotatable with respect to said stationary tube. Flange 22 has been provided with a circumferentially extending groove 23 in which are provided two U-shaped sealing rings 24 and 25. The space 26 between the two sealing rings is filled with liquid under high pressure by means of conduits 27 connected to a source of pressure. With the embodiment shown in Fig. 1 and 2 the sealing rings are mounted in the rotatable part. Said sealing rings, however, also can be mounted in the stationary part 1 or 19 respectively and it is possible as well to apply seals in which the sealing rings extend into a groove of the stationary part as well as into an opposite groove of the rotatable part.

Claims: CLAIMS: 1. Seal between two parts (1,2) of a conduit coupling which are rotatable with respect to each other, which parts have surfaces (3,4) movable with respect to each other and between which there exists a small clearance (18) which is sealed by means of one or more sealings (12,13) which are placed inside a groove (10,11) in one of the surfaces or in both surfaces of the mutually rotatable parts, which seal is present at both sides of a channel (7) through which the medium flows which has to be sealed, characterized in that each groove (10,11) contains two sealing rings (12,13) and has a width which is larger than the width taken by the two sealing rings (12,13) inside the groove 10,11) and the space (16) between the two sealing rings is connected to a source (17) of liquid the pressure of which is larger than the pressure of the medium which has to be sealed, said sealing rings (12,13) in principle having an U-shaped cross-section and are placed within the groove with the openings turned towards each other. 2. Seal as claimed in claim 1, characterized in that the liquid inside the groove has a viscosity which is larger than the viscosity of the medium to be sealed. 3. Seal as claimed in claim 1 or 2, characterized in that the sealing rings (12,13) are made from resilient material. 4. Seal as claimed in claim 1, 2 or 3, characterized in that each groove (10,11) has a ridge (23,28,34) inside the space between the two sealing rings (24,25,32,33,35,38) which ridge comprises a supply channel (27,31) for the supply of liquid under higher pressure into said space, said ridge dividing the groove into two chambers (29,30) one for each sealing ring.

Inventors: ADANG, FRANCOIS MARIE JACQUES, FRANKEN, WOUTER ADRIAAN GERARDUS, Adang, François Marie Jacques
Applicants: SINGLE BUOY MOORINGS INC.
Application year: 1984
Main classification: F16L17
IPC codes: F16L27, F16L23, F16L17, F16J15