| 摘要 |
<p>915,083. Fluid-pressure servomotor-control systems. GARRETT CORPORATION. May 12, 1960 [May 18, 1959], No. 16862/60. Class 135. [Also in Group XXVI] Bleed control apparatus for a compressor 10 includes a passage 15 incorporating a valve 16 and on-off control means responsive to the ratio of the pressures in two stages of the compressor to control the valve 16 and is characterized in that as the pressure ratio rises the control means close the valve at a lower ratio than that at which they open it as the ratio falls. As the speed of the compressor increases the pressure in a conduit 43 rises causing a plug-lift valve 48 to descend until a needle 45 has retracted sufficiently from a nozzle 42 to balance the pressures acting on diaphragms 36 connected with the needle and the valve. The latter first closes the upper part of a bore 47 forming a vent to atmosphere from a passage 50 so that the latter is pressurized by the conduit 43 to lift a spring-loaded piston 54 which opens a ball-valve 25 to allow air from a conduit 60 to act on a piston 21 and close the valve 16. Continued movement of the valve 48 closes the lower part of the bore 47 to pressurize a passage 51, lift a spring-loaded ball valve 70 and raise a piston 64 carrying a piston valve 65 which is supplied through a passage 71 to maintain the air supply to piston 64 after the valve 70 has closed. The upward movement of the piston 64 lifts a ball valve 68 which allows the piston 54 to descend as soon as the valve 48 clears the lower part of the bore 47 during deceleration of the turbine, the valve 16 thus being re-opened at a higher pressure ratio than that at which it was closed. The valve 68 is held off its seat to prevent re-closure of the valve 16 by the action of the piston valve 65. Temperatureresponsive means 79 in the compressor inlet act through bellows 74, 75 and a lever 80 to adjust the position of the bore 47 in relation to the valve 48. The bellows act in opposition and are rigidly connected by a link 76 so that ambient temperature changes do not affect the lever 80. A screw 84 permits manual adjustment of the position of the bore 47. The diaphragms 36 include a relief valve 40.</p> |
