GB1309350A - Labyrinth sealing devices for drilling turbines and to drilling turbines fitted therewith - Google Patents

Abstract

1309350 Shaft seals SOC GENERALE DE CONSTRUCTIONS ELECTRIQUES ET MECHANIQUES (ALSTHOM) 24 Sept 1971 [13 Oct 1970] 44686/71 Heading F2B [Also in Divisions E1 and F1] A labyrinth sealing device for ensuring a fixed amount of leakage of drilling mud from a space 6 to lubricate the bearing 3 in a drilling turbine comprises annular discs 10, Fig. 1, which are either free to rotate about, or keyed to rotate with, the turbine shaft 2 and are pressed axially against the associated faces of labyrinth rings 9 by the pressure of the drilling mud, communieating passages being provided in the annular discs or labyrinth rings to provide the leakage. The main flow of drilling mud passes from the space 6 through orifices 7 into the bore 8 of the shaft to the drilling bit. Each annular disc 10 may consist of a metallic ring 11, Fig. 2, surrounded by an elastomer 12 and arranged to be a clearance fit on the turbine shaft 2, the leakage past the end face of the disc being controlled by radial grooves 13 on the downstream side of the disc. In Fig. 6 (not shown); each disc is made of an elastomer reinforced with canvas (17) on the upstream side, the downstream side being provided with radial grooves (13). In Fig. 7 (not shown), each disc (23) is made of steel and presses against a labyrinth ring formed in two parts, a distance piece (20) and a ring (19) covered on its upstream face by an elastomer (21) in which radial grooves (22) are formed. Fig. 8 shows discs 24, 26 of brass pressed against labyrinth rings 9 of steel, the leakage past the discs being controlled either by axial orifices 16 or grooves 25.