GB774089A - Starter control system - Google Patents

Abstract

774,089. Gas turbine plant. BENDIX AVIATION CORPORATION. Oct. 29, 1953 [Dec. 31, 1952], No. 29939/53. Addition to 774,087 and 774,088. Class 110 (3). [Also in Group XI] An engine starter as claimed in Specification 774,088 comprising a turbine powered by burning a mixture of fuel and compressed air having electrically-operated air and fuel control means which are initially energized by a starter switch and which are energized by a second circuit having a switch responsive to the combustion chamber pressure to take over the energization of the control means when the combustion chamber pressures reaches a predetermined value and to de-energize the system when the pressure falls below the predetermined value, has ignition means in the combustion chamber energized by the starting switch and the switch responsive to combustion chamber pressure is arranged to de-energize the ignition means when the pressure exceeds a predetermined value. The turbine 2 connected through reduction gearing 3 to a starter jaw 4, is supplied with working fluid by a combustion chamber 5. A compressed air bottle 7 is connected to the combustion chamber 5 through a conduit 8, pressure-responsive and reducing valve 9, conduit 10 and nozzle 11. The air bottle 7 is also connected to a fuel accumulator 12 through a conduit 18, pressure reducer 19, solenoid-operated valve 21 and conduit 22. The accumulator 12, which is connected to the combustion chamber 5 through a conduit 13, solenoid-operated valve 14 and conduit 15, is divided by an elastic diaphragm 26 into an air section 25 and a fuel section 24. The fuel section is also connected to the aircraft fuel system through a conduit 29 and a check-valve 28. When it is desired to start the turbine starter, the switch 36 is closed and the ignition coil 48 and the winding 55 of the relay 56 energized. The relay 56 actuates the switch members 58, 59. The switch member 58 energizes the solenoid-operated valves 14, 21 which are then opened. Air then flows from the bottle 7 to the space 25 and forces fuel from the space 24 through the valve 14 into the combustion chamber 5. At the same time, air from the conduit 22 opens the valve 9 and allows air to flow from the bottle 7 to the combustion chamber 5. When the pressure in the combustion chamber due to the ignition of the fuel and compressed air reaches a predetermined value the pressure-operated switch 30 is actuated. Switch arms 31, 32 engage contacts 33, 34, this shunts the switch 36 and energizes the winding 55 through the centrifugal switch 52. The winding 72 of the relay 44 is also energized, causing the switch 42, 43 to be opened and the spark coil 48 to be de-energized. Actuation of the switch arm 43 renders the starting switch 36 ineffective. A restart of the starter cannot be initiated without first releasing the switch 36. When the pressure in the combustion chamber falls or the switch 52 is opened by the turbine 2 overspeeding, the relay 56 is deenergized and returns to the open position. The solenoid-operated valves 14 and 21 are consequently de-energized and return to the closed position. The valve 21, when closed, vents the conduit 22 to atmosphere. The valve 9 then closes and shuts off the air supply to the combustion chamber. The accumulator will also be refilled through the conduit 29 and valve 28.