Patent GB-958057-A (GB)
Title: Valve assembly
Inventor: COLLEY ROWAN HERBERT
IPC: F04D27/02
Filed: 1961-09-25
Abstract: 958,057. Valves. ROLLS-ROYCE Ltd. Sept. 18, 1962 [Sept. 25, 1961], No. 34327/61. Heading F2V. [Also in Divisions F1 and H2] A valve assembly, which may be arranged in a gas turbine engine to control the flow through a duct of part of the air compressed by the compressor of the engine, has two parallel fluid paths respectively controlled by a normally open and a normally closed flow control valve, which valves are respectively provided with closing means and opening means operated by the same power source, whereby both flow control valves may be maintained simultaneously open or closed and if the power supply should fail the normally open valve remains open to permit fluid flow through the valve assembly. In an aircraft gas turbine jet propulsion engine (not shown) a valve assembly 22a, Fig. 3, is mounted on the compressor 11 of the engine to receive some of the air compressed thereby and to pass it to any parts of the aircraft where ice may form. The flow of compressed air from the compressor 11 through passages 23a, 24a is controlled by piston valves 30a, 31a carrying carbon ring seals 63, 64 and sliding in cylinders 61, 62 associated with liners 65, 66 provided with carbon bushes 67 for valve stems 70, 71, Figs. 3 and 4. The positions of the valves 30a, 31a are respectively dependant on the position of a valve 48a and a valve 52a, each controlled preferably by a solenoid, to open a vent 42a or 43a to atmosphere, or a conduit 44a or 45a connected to a conduit 46a supplied with compressed air. The valve 48a is biased by a spring 49a to close the conduit 44a but instead closes the vent 42a when the solenoid 50a is energized, whereas the valve 52a is biased by the pressure of the air in conduit 45a to open the latter but closes it when the solenoid 53a is energized. Opening of the vent valve 42a or 43a vents the space above the piston 30a or 31a through a conduit 40a or 41a to atmosphere and thereby causes the compressed air to lift the valve 30a or 31a and pass through a conduit (not shown) to hollow guide vanes at the inlet of the engine for de-icing purposes. Opening, instead, the conduit 44a or 45a allows compressed air to pass through conduit 40a or 41a to the space above the valve 30a or 31a, thereby causing the particular valve to close. Springs 74, 75 are provided to assist the closing of the valves at high altitudes. In an electrical control circuit, Fig. 7, supplied as by a battery (not shown); the energization of the solenoids is controlled through a pilot's switch 94 and a switch 104. The switches 94, 104, when in the positions shown, allow only the solenoid 50a to be energized and thereby cause both valves 30a and 31a to assume the closed position. By connecting the switch 94 instead with terminal 106 the solenoid 50a is de-energized and the valve 30a opens and, if then, the switch 104 is instead connected to the terminal 103 the solenoid 53a is energized and thereby opens the valve 31a, thus both valves 30a and 31a are then open. A switch (not shown) may be provided between contacts 98 and 102, the closure of which switch, with both switch arms 93 and 105 in their upper or lower positions, causes both solenoids 50a and 53a to be energized. The valve stems 70, 71 each carry a conductor sleeve 83, Fig. 6, which is associated with three sprung electrical contacts, the lower two of which are electrically connected when the respective valve 30a or 31a is in its closed position and the upper two of which are electrically connected when the respective valve is in its open position. These contacts 84-89 are connected across an electrical supply, such as a battery (not shown), as seen in the lower half of Fig. 7 and are associated with solenoids 112 and 113. When both valves 30a, 31a are closed the contacts will be connected as shown in Fig. 7 to energize the solenoid 113 and cause an indicator (not shown) to register " shut." When one or both valves 30a, 31a is or are open the solenoid 112 is instead energized and the indicator registers " Open." Each group of contacts 84-86 and 87-89 is so arranged about its respective valve stem 70 and 71 as to ensure that on movement of the latter, one electrical circuit is broken before the next is made. Thus, during each change of position of either of the stems 70 or 71 there is a period where both solenoids 112 and 113 are de-energized which is registered by the indicator by cross-hatching or by the word " Mid." This enables the pilot to check that the second valve opens when one valve is already open since the indicator will move to the " Mid " and return to the " Open " position. Preferably the control circuit and indicator circuit are separate as shown. Figs. 5 and 8 show how the conductor sleeve is formed on each stem 70, 71. A groove 80, Fig. 5, is provided with a bonding coating 81 on which is sprayed ceramic insulating sleeve 82 which receives centrally, by spraying, the conductor sleeve 83. The conductor sleeve 125, Fig. 8, of sufficient length to enable two contacts to touch it simultaneously, is similarly formed and is between separate shorter conductor sleeves 124 and 126 which are bounded by annular recesses 130-133 in one of which the contact out of circuit rests, thereby reducing wear.