Patent GB-807541-A (GB)
Title: Improvements in or relating to packings for relatively rotatable members
IPC: F16J15/38
Filed: 1954-05-22
Abstract: 807,541. Stuffing-box substitutes. UNITED STATES METALLIC PACKING CO. Ltd., and STEPHENS, J. May 19, 1955 [May 22, 1954], No. 15141/54. Addition to 733,430. Class 122 (5). In a shaft-sealing device comprising a rotatable packing ring 7 sealed to the shaft 1 by a resilient sealing ring 15 and having a sealing face 9 adapted to engage a. sealing face 10 of a non-rotatable packing ring 2, the sealing faces are urged into contact with one another by the fluid pressure differential across the seal, irrespective of its direction, and by spring means producing a normal spring force when no pressure difference exists across the seal, which force is insufficient to hold the sealing faces together when the pressures at the opposite sides of the packing are atmospheric and nil respectively. The rings 2 and 7 have a clearance with the shaft and the ring 7 is counterbored from its end adjacent a clamping ring 11 fixed to the shaft 1 to provide a recess 8 in which the rubber sealing ring 15, of tubular form, is axially displaceable. Follower rings 17 and 18 are disposed on opposite sides of the ring 15 and circumferentially spaced springs 19 and 20 are arranged between the rings 17 and 11 and between the ring 18 and the bottom of the recess 8 respectively. The ring 2 is sealed to the shaft casing 3 by a packing ring 4. The rings 2, 7, 11 and 17 are formed in halves secured together by bolts 12, 13, 14 and a garter spring 21 respectively. The follower 18 is preferably also formed in halves secured together by a garter spring. In operation, when the pressure inside the casing 3 is positive, the ring 15 is moved to the left and when a certain pressure is reached the springs 20 become fully extended and the sealing contact between the packing rings 2 and 7 is then entirely due to the fluid pressure acting on the end face of the recess 8. When a vacuum exists inside the casing the sealing ring 15 is moved to the right by the atmospheric pressure and the springs 19 become ineffective when the vacuum reaches a given value. In a modification, Fig. 2 (not shown), the springs 20 and follower ring 18 are replaced by a stepped spacing ring formed in halves held together by a garter spring and abutting the bottom of the groove 8. In another modification, Fig. 3, a rotatable packing ring 37 is disposed between the clamping ring 11 and a non-rotatable packing riiig 42 which extends into a stuffing-box 33 provided in a machine part 34. The packing rings 37 and 42 are urged into facial sealing contact by compression springs 36 and 47 provided between the rings 11 and 37 and between the ring 42 and a face 48 of the part 34 respectively. The rings 37 and 42 are sealed by sealing rings 41 and 45 to the shaft 32 and the stuffing-box 33 respectively. The rings 11, 37 and 42 are formed in halves connected by bolts 51, 52 and 53 respectively and are drivingly connected by pins 38, and the ring 42 is prevented from rotating by a peg 50 secured to the wall 48 and entering a slot 49 in the ring. When the fluid pressure in the box 33 is positive the rings 37 and 42 move together to the left until the ring 37 abuts the clamping ring 11 and when a vacuum exists in the box the rings move to the right until the ring 42 abuts the wall 48. One set of springs either 36 or 47 only may be used. To prevent sealing contact between rings 11 and 37 and between the ring 42 and the wall 48 respectively, a projection 54 may be provided on the ring 11 and the face of ring 42 adjacent the wall 48 may be slightly dished. In a modification, Fig. 4 (not shown), the ring 42 extends further into the stuffing-box and the springs 47 are arranged between the end of the ring 42 and the bottom of the stuffing-box.