GB744847A - Seals for preventing the escape of fluid along shafts - Google Patents

Abstract

744,847. Stuffing-box substitutes. NAPIER & SON. Ltd., D. May 3, 1954 [May 8, 1953], No. 12956/53. Class 122(5) A fluid-seal for a shaft 2, Fig. 2, passing through a wall 1 which is subject to a pressure differential on its two sides comprises a sealing ring 10 housed in an annular recess 5 in the wall 1 and restricted to limited radial and axial movements relatively to the wall 1, and a flexible diaphragm 17 arranged to divide the recess 5 into two pressure chambers, one of which is open to the fluid on one side of the wall 1 while the other is sealed and receives sealing fluid, such as oil. at a higher pressure than that of the fluid acting on either side of the wall; the sealing fluid passes through at least one passage 21 and then axially along the working clearance between the ring 10 and the shaft. As applied to sealing the shaft of a hydrogen-cooled electric motor, the open chamber receives hydrogen under higher pressure than that of the atmosphere, from the motor housing and the other chamber is sealed against atmospheric pressure by engagement between a flange 12 on the sealing ring 10 and the flange 3 of the recess 5. The flange 12 is pressed against the flange 3 by the resultant of the pressures in the chambers combined with the spring thrust of the resilient metal diaphragm and that of a spring disc 19 or spring fingers which are clamped with the diaphragm to the sealing ring 10 by bolts 16. When the diaphragm is of resilient material, the spring disc need not be provided. The ring 10 is formed in two parts preferably from the same material as the shaft 2 and coated with white metal in the bore and on the bearing face of the flange 12, the parts of the ring being clamped together by bolts 16 and bridge-pieces 13, 14. Rods or bolts (not shown), supported from the flange 3 engage holes or slots in a flange 15 on the ring 10 to restrict movement of the ring. The ring may be made in two ring elements 23, 24, Fig. 3. each comprising at least two parts and the elements are provided with passages 29 for distributing the oil. A clearance (not shown) for the admission of fluid is provided between the ring and flange 4. The detachable abutment 18 for the diaphragm mav be replaced by others of different contour to adjust the forces on the diaphragm. Antifriction metal may also be provided on either or both of the mutually-contacting faces of the abutment and diaphragm. Alternatively the diaphragm 17 may be attached to the flange 4 of the recess 5, Fig. 5, and bear against an abutment 18 on the sealing ring 23. 24. In this case the sealing oil presses the diaphragm towards the flange 3 and the hydrogen acts in the opposite direction.