GB996546A - Improvements in or relating to sealing devices - Google Patents

Abstract

996,546. Mechanical seals. ROLLS-ROYCE Ltd. July 19, 1963, No. 28650/63. Heading F2B. A sealing device for sealing between relativelyrotatable members 18, 19, Fig. 2, comprises a U-shaped seal part 56 which separates high and low pressure gas zones P 5 , P 6 , is sealingly mounted on one of the members (the member 19 as shown) with provision for axial movement thereon, and has two sealing projections 54, 55 on the limbs 63, 62 for coaction with the opposite faces of an annular part 61 projecting from the other member (the member 18 as shown), the intermediate gas pressure P 7 existing between the two projections being applied to at least one face of the seal part to maintain the latter in normal operation in an equilibrium axial position with each of the faces of the projections at a steady gap from the annular part 51. The members 18, 19 shown constitute respectively the shroud at the periphery of the blades 50 of a gas turbine and the casing. The projection 51 has flat annular faces 52, 53 for coaction with the faces of the projections 54, 55 of the U-shaped part 56 which is shown as being formed of two annular parts 62, 63 secured by bolts 64 and connected to the casing 19 by splines 66; the part 63 bears against a sealing ring 60 in a groove in a flange 57 projecting from the casing. The equilibrium position of the part 56 depends on the relative areas A5, A6 on opposite faces of the part. Movement of the part to the right from its normal position causes the pressure P 7 to fall, and movement to the left causes the pressure to increase, so that in either case the part tends to move back to its equilibrium position. In the modification shown in Fig. 3, the part 56 comprises a main part and an axially-movable sub-part 70 which is sealed to it by a ring 71, carries the projection 54, and has a labyrinth sealing face 72 coacting with an axially-extending face 73 on the part 18. In the further modification shown in Fig. 4, the part 18 has two annular projections 80, 81 co-operating with projections on the limbs of the U-shaped part 82 which has sealing engagement at 88 with a projection 89 on the casing 19 and bleed holes 90 connecting the intermediate pressure space with the low pressure side; in this arrangement, the U-shaped part 82 is provided with an axial split allowing it to be expanded for assembly over the projections 80, 81 where it is embraced by a continuous ring 94.