| 摘要 |
<p>772,247. Axial flow compressors; gas turbine plant. ROLLS-ROYCE, Ltd. Oct. 8, 1954 [Sept. 23, 1953], No. 26264/53. Classes 110 (1) and 110 (3). In a compound gas turbine plant comprising a low pressure compressor driven by a low pressure turbine feeding a high pressure compressor driven by a high pressure turbine, a bleed valve, through which air compressed in a compressor is vented to atmosphere to prevent surging of the compressor, is opened by means operable on deceleration of the engine only when surging would otherwise be likely to occur due to the rapidity of deceleration. A bleed valve 16, controlling outlet ports 15 from the discharge duct 10 of a compressor 11 which may be the high or low pressure compressor of a compound gas turbine plant, is connected to a spring-loaded piston 17 contained in a cylinder 18. Fluid under pressure is supplied by a pump 22 through a piston valve 21 to the cylinder 18. The valve 21 controls the supply of pressure fluid to the cylinder 18 or from the cylinder to the drain 26. The valve 21 is actuated by a speed-responsive device 38 comprising a pair of bobweights 42, the tail portions 43 of which lift a rod 44 through a thrust bearing 45 against the action of the spring 46. The speed-responsive device 38 is driven by the hand wheel 28 through the shaft 29, freewheel mechanism 33, 36, 34 and bevel gearing 37, 39. The hand wheel 28 is connected to the throttle 27 through the worm 30, quadrant 31 and linkage 32. The arrangement is such that the speed responsive mechanism 38 is only driven when the hand wheel is rotated in the closing direction of the throttle 27. When the throttle is closed at above a given rate, the bobweights 42 actuate the rod 44 and the valve 21 connects the cylinder 18 to drain. The bleed valve 16 is then opened by the spring 19. The restrictor 25 delays the build up of pressure in the cylinder 18 after the hand wheel has stopped turning so as to give sufficient time for the engine to decelerate before the ports 15 are again closed. In a modification, the freewheel mechanism is replaced by a one-way dashpot mechanism so that the throttle 27 may be closed rapidly, but may only be opened at a rate which is not sufficient to cause opening of the bleed valve. A shut-off cock 49 in the fuel system operated by an overspeed mechanism may be connected to a bleed valve so that the valve 16 is opened when the cock 49 is closed.</p> |
