Patent GB-774087-A (GB)
Title: Starter control system
IPC: F02C7/277
Filed: 1953-10-27
Abstract: 774,087. Gas turbine plant. BENDIX AVIATION CORPORATION. Oct. 27, 1953 [Dec. 31, 1952], No. 29685/53. Class 110 (3). [Also in Group XI] An engine starter comprising a turbine powered by burning a mixture of fuel and compressed air has electrically-operated air and fuel control means which are initially energized by a starter switch and a second electric circuit energized by pressure-responsive means responsive to the fuel pressure in the fuel line to take over the energization of the air and fuel control means when the fuel pressure reaches a predetermined value and to de-energize the system when the pressure falls below the 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 valve 9, conduit 10 and nozzle 11. A fuel accumulator 12 is connected to the chamber 5 through a conduit 13, solenoid valve 14 and conduit 15. The compressed air bottle 7 is also connected to the accumulator 12 through a conduit 18, pressure reducer 19, conduit 20, solenoid valve 21 and conduit 22. The accumulator 12 is divided by an elastic diaphragm 26 into an air section 25 and a fuel section 24. The fuel section is connected to the aircraft fuel system through a conduit 13 and non-return valve 28. When it is desired to start the turbine starter, the switch 35 is closed and the control winding 47 of the relay 48 energized. The relay then actuates the switch arms 50, 51. The switch arm 51 closes the circuit of the solenoid valves 21, 14, which are then opened, and energizes the spark coil 58. Air then passes from the air bottle 7 to the space 25 and forces fuel from the space 24 into the combustion chamber through the valve 14. 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 fuel pressure in the conduit 15 reaches a pre-determined value the pressure operated switch 30 is actuated. Switch arms 31, 32 then engage contacts 33, 34 and thereby by-pass the switch 35 and energize the winding 63 which actuates the switch member 41 into engagement with the contact 65, thus rendering the starting switch 35 ineffective. When all of the fuel in the space 24 has been expended, the fuel pressure in conduit 15 will fall and the switch 30 will return to its open position. Relay 48 will be de-energized and the circuits of the solenoid valves 14, 21 opened. The valves 14, 21 then return to the closed position. When the valve 21 is closed it vents the conduit 22 to atmosphere which allows the valve 9 to return to the closed position and the accumulator 12 to be refilled from the aircraft fuel system through the conduit 29 and valve 28. The solenoid valves 14, 21 and spark coil 58 may be arranged in parallel instead of as in series, as shown. A centrifugal switch 44 is opened when the turbine exceeds a predetermined speed to de-energize the relay 48 and so de-energize the valves 14, 21 and spark coil 48.