GB1142326A - Improvements in rotary mechanical seals - Google Patents

Abstract

1,142,326. Mechanical seals. UNITED STATES METALLIC PACKING CO. Ltd. 19 July, 1966 [24 July, 1956; 12 May, 1966], Nos. 31673/65 and 21108/66. Heading F2B. In a mechanical seal 10 for a rotary shaft 11 comprising a wear ring 17 of self lubricating material split into two or more segments and having a sealing face 24 abutting a sealing face 23 on a metallic packing ring 15, the wear ring is arranged so that in normal use its joint interfaces are urged into sealing engagement with one another by the pressure of the sealed fluid acting on the outer periphery of the ring, and by an encircling spring 20 which also acts to urge the joint interfaces together should the fluid pressure on the inner periphery of the wear ring 17 exceed that on its outer periphery. The ring 15 is secured to the shaft housing 12 by screws 16 and the ring 17 is sealed to the shaft by an 0-ring 18 located in a recess 12 in the ring 17 by a nose 22 of a driving ring 19 clamped to the shaft and having at least one axial pin (not shown) engaging an aperture in the wear ring 17 to thereby drive the latter. The rings 15, 17 and 19 are all split into halves, the halves of the rings 15 and 19 being held together by bolts (not shown) and those of ring 17 being held together by the garter spring 20. In use, the pressure in housing 12 acts on the right hand faces of the rings 17 and 18 to urge the face 23 against the face 24 and also acts on the outer periphery of ring 17 to hold the segment in contact with one another. In a modification, Fig. 2 (not shown), for use when the housing 12 is under vacuum, the wear ring (31) is arranged on the outside of the packing ring (15) and in a further modification, Fig. 3 (not shown), for use with both pressure and vacuum in the housing, the seal comprises both an internal (17) and an external (31) wear ring. Compression springs may be arranged between the wear rings and the driving rings to assist in urging the sealing faces into contact with each other. The driving ring (49) in a still further embodiment, Fig. 1A (not shown), is clamped to the shaft (41) by means of an axial set screw (56) having a conical end (57) engaging a ball (58) housed in a radial bore (59) in the ring and urged against the shaft by axial movement of the screw (56) as described in Specification 1,142,329, and the segments of the wear ring (47) are held together by a circlip (50). The halves of the metallic packing ring may be aligned by locators as described in Specification 1,142,328.