Patent GB-730296-A (GB)
Title: Improvements in or relating to control arrangements for rotary machines
Inventor: GREY JOHN CONSTANTINE
IPC: F01D25/20
Filed: 1952-07-22
Abstract: 730,296. Engine stop-gear; turbines. POWER JETS (RESEARCH & DEVELOPMENT), Ltd. July 14, 1953 [July 22, 1952], No. 18437/52. Classes 110 (3) and 122 (4). A control system for a rotary machine comprises means for producing a fluid pressure in the machine lubrication system substantially proportional to the rotational speed of the machine and an overspeed trip device operable by said pressure. An inward flow turbine 10, having an inlet conduit 56 with a butterfly throttle valve 57 therein, is mounted on one end of a shaft 11 jonrnalled in bearings 13, 14 and carrying at its opposite end a centrifugal impeller 12 which acts as an oil pump or brake. Lubricating oil is supplied by a pump 29 via a unit 30 (detailed in Fig. 2) to the bearings 13 and 14 through conduits 15 and 20 respectively and also to the thrust face of bearing 14 through a conduit 21. Leakage oil from the bearings is returned to the sump 19 through conduit 18 whilst that from the thrust face of bearing 14 is fed through a conduit 23 to the suction chamber 24 of the impeller 12 and discharged through a restrictor valve 26 and conduit 27 to the sump 19. A connection 31 is provided between the sump 19 and the oil inlet to the thrust face of bearing 14 through which oil is drawn by the impeller 12 when its output exceeds the oil supplied through conduit 21. The shaft 32 of the butterfly valve 57 is biased to the closed position by a spring 60 and carries a cam 33 (Fig. 2) having parts co-operable with a detent 36 and a projection 35 on a pivoted lever 34, one end of which is engageable with a ring 37 on a spring-loaded shaft 38 movable by a piston 45 subjected to the oil pressure due to pump 29, and the other end of which coacts with the spindle 39 of a valve 41 seated by a spring 40 against the pressure of the oil delivered by the impeller 12 via a union 48 to a chamber 49 at the lower end of the valve. When the turbine 10 and pump 29 are inoperative the piston 45 is at its lowest position and the ring 37 contacts the end 52 of lever 34 to lock the projection 35 in engagement with the detent of cam 33, the throttle valve 57 then being closed. When the pump 29 is started oil flows through union 42 and beneath the piston 45 and then via union 44 to conduits 15 and 20. As the pressure increases the piston rises to uncover port 46 and allow oil to flow through conduit 21 to prime the impeller 12 and the ring 37 is disengaged from lever 34. The valve 57 may then be opened by the handwheel 59 until the detent 36 in lever 34 engages a corresponding projection on cam 33 and the lever is held in that position, in which the valve 57 is fully open, by a spring 54. If the turbine overspeeds, the corresponding impeller oil pressure causes the valve 41 to rise from its seat to release the detent 36 and allow the butterfly valve 57 to be closed by the spring 60. The detent 36 is also released and the valve 57 closed if the lubricating oil supply pressure fails, the spring 53 then pushing the piston 45 down and causing ring 37 to contact the end 52 of lever 34. It is stated that as an alternative the controlling pressure fluid may be provided by an air pump.