Patent GB-770430-A (GB)
Title: Improvements in or relating to braked turbines
Inventor: THEED WILLIAM DENIS LEAROYD
IPC: F16C33/78
Filed: 1951-08-25
Abstract: 770,430. Turbine plant; stuffing-box substitutes. GODFREY (HANWORTH), Ltd., [formerly GODFREY & PARTNERS (HOLDINGS), Ltd., Sir G.]. Nov. 25, 1952 [Aug. 25,1951], No. 20067/51. Classes 110 (3) and 122 (5). [Also in Group XXXIV] A turbine plant comprises a turbine rotor and a compressor rotor axially spaced on a common shaft and mounted on anti-friction bearings which are lubricated by lubricant pumped from an external source to one of the bearings through which it passes in a direction longitudinal of the shaft and then passes longitudinally of the shaft to tne other bearing, then returning to the external source of supply. In the construction shown in Fig. 1 a compressor rotor 10 and a turbine rotor 11 are secured to a shaft 14 which is mounted in spaced ball bearings 15, 16. The bearings are carried by a cylindrical member 24 surrounded by a sleeve 26 formed of two portions 26a, 26b. Channels 29, 30 are formed between the sleeve and the member 24, these channels terminating at one end in annular recesses 31, 32 which receive the upper ends of vertical stack pipes 33, 34. The pipes form flow and return channels for oil supplied from an oil reservoir 36 by an electrically-driven pump. The oil is fed by way of pipe 33, channel 29, and annular space 41 to the bearing 15, and along the member 24 to the bearing 16, returning to the reservoir by way of annular space 41a, channel 30 and pipe 34. The switch 42, Fig. 2, for starting and stopping the pump motor 35 has a diaphragm 43 subjected to the differential pressure between the inlet 44 of the compressor 21 and the outlet 45 of the turbine 22, the diaphragm dividing the body of the switch into two chambers 47, 48 communicating respectively by pipes 49, 48a with the inlet 44 and the outlet 45. As soon as air is fed to the inlet 44 the diaphragm 43 flexes towards the chamber 48 and engages a plunger 51 to operate a snap-action make and brake mechanism 50 whereby an annular disc 56 bridges two contacts 54, 55 to close the motor circuit. As soon as the air supply is shut off from the compressor the diaphragm returns to its unflexed position and the plunger 51 and disc 56 return to the positions shown, so that the motor circuit is opened and the pump stops. Contamination of the air passing through the compressor and turbine by oil from the bearings is prevented by setting up an air flow between the periphery of each rotor and its adjacent shaft bearing and causing the air to flow in the opposite direction to that which would have to be taken by the contaminating oil. This air flows over the backs 10a, 11a, Fig. 1, of the rotors and along a plurality of labyrinth-like sealing devices to vents 62 leading to the atmosphere. The labyrinths are formed by annularly flanged sleeves 55, 56 and a sleeve 57 which are clamped between each rotor and the respective adjacent bearing. The outer and inner surfaces of the flanges 55a, 56a of the sleeves 55, 56 and the outer cylindrical surface of each of the sleeves 56, 57 are circumferentially grooved to form a restricted path for the air flow, which prevents lubricant from flowing in the reverse direction and contaminating the air to the turbine and compressor. A further seal is provided by bushes 63 carried by the sleeve 26 and provided with annular flanges 63a co-operating with surfaces on the sleeves 56, 57 to prevent air passing the vents 62 towards the bearings.