GB916150A - Improvements in glands for shafts rotatable at high peripheral speeds - Google Patents

Abstract

916,150. Stuffing-box substitutes. GENERAL ELECTRIC CO. Ltd., and LE ROSSIGNOL, R. June 22, 1948 [June 23, 1947], No. 16515/47. Class 122 (5). A gland for a shaft member rotatable at a high peripheral speed comprises two like surfaces of revolution (one being that of the shaft member) arranged with a small clearance between them, one of the surfaces being provided with helical or spiral grooves extending from a central region to connect with the two sides of the gland between which substantial sealing is required, the central region being sealed from the outside ends of the gland excepting through the grooves and the clearance between the surfaces; the senses of the helices or spirals and the arrangement being such that when the shaft member is rotated in the appropriate direction at a suitable speed a vacuum is produced in the central region. In Fig. 1 a shaft member 10 coupled to the main shaft 15 by a bellows device 16 runs within a cylindrical outer gland member 11 in which are formed two helical grooves 12, 13 of opposite hand extending from a central region where a ring 14 separates the two grooves. When the shaft member 10 rotates it operates like a Holweck pump, gas in-the region of ring 14 being pumped outwards along the grooves 12, 13 respectively to the space to the left of members 10 and 11 and through a threaded hole 21 in the wall 20 across which the seal is desired. When the pressure to the right of wall 20 is atmospheric, a rough vacuum may be produced by an auxiliary pump connected with the hole 21. To provide a seal when the shaft is not rotating a rubbing gland 23 of metal or graphite may be pressed against the right-hand ends of members 10 and 11 and is preferably actuated automatically when the speed of the shaft drops below a predetermined value. A cup-leather gland 22 prevents oil flowing from the journal bearing and through the ball bearing to the low pressure space. In another arrangement, Fig. 2, the cylindrical member 10 is replaced by two discs 26, 27 which run in passages formed in ports connected to the wall 20 and provided with spiral grooves 28, 29, 30 and 31. A close clearance ring is provided at 32. The directions of the spirals and of rotation are such that gas in the space 33 is pumped outwards along groove 29 and inwards along groove 28 to emerge at 36 on the left of wall 20; similarly gas in space 34 is pumped along grooves 30, 31 to the hole 21.