Patent GB-859980-A (GB)
Title: Pneumatic engine starter
IPC: F02C7/277
Filed: 1958-05-09
Abstract: 859,980. Gas turbine type engine starters. BENDIX CORPORATION, [formerly BENDIX AVIATION CORPORATION]. May 9, 1958 [June 12, 1957], No. 14954/58. Class 110 (3). [Also in Group XXIX] A turbine-type engine starter comprises a turbine wheel which is caused to rotate by gases discharged from nozzles, and is adapted to be drivingly connected to the engine, means being provided for controlling the amount of gases delivered by the nozzles on to the turbine rotor blades, the controlling means comprising a cut-off device interposed between the nozzle and the rotor blades and actuated by a pneumatic device connected to the turbine gas supply, and a device responsive to turbine speed to control actuation of the pneumatic device so as to move the cut-off device to the cut-off position when the turbine rotates at a predetermined speed. In the embodiment shown, a solid fuel cartridge contained in a chamber 11 is fired by means of an igniter 13 and the combustion gases flow through duct 39 to a nozzle chamber 40 from which gases flow through nozzles 29 to impinge on the blades of the turbine rotor wheel 14, the gases passing to exhaust chamber 33 and outlet 35. The turbine shaft 20 is connected to the engine by conventional means 16, 17 which include a speed-responsive device 18. The flow of gases from the nozzles 29 is controlled by means of a rotatable plate 27 formed with a series of open ings 28 which may be moved into or out of alignment with the nozzles. The plate 27 is movable by means of a piston 46 acting through linkage 48, the piston being normally urged downwardly by means of the spring 47 so that the plate 27 is in the position in which the nozzles 29 are covered by the plate. The lower side of the piston 46 is placed in communication with the cartridge chamber 11, so that when the cartridge is fired, low-pressure gases act on the lower side of the piston 46, thereby causing the piston to rise and the plate 27 to rotate so that the openings 28 therein are in alignment with the nozzles 29, so that higher pressure gases can then impinge on the rotor blades to rotate the engine to be started. A dump valve 73 is disposed in the duct 39, being normally held open by means of the spring 75, but moved to the closed position when the cartridge is fired by means of low pressure gas acting on the piston 76. When the starting switch 81 is closed, the solenoid of the speed-control valve 55 is energized, whereby the valve 56 closes. When the cut-off speed is reached, the overspeed device 18 acts to open the switch 19 whereby the solenoid of the valve 55 is de-energized causing the valve to open. Combustion gases then pass from the chamber 11 through ducts 43, 51, 54 and 61 to act on the upper sides of the pistons 76 and 46, whereby the dump valve 73 is opened and the nozzleplate 27 is moved to the cut-off position and the gases then pass to the outlet 35. Similarly, if the pressure of the gases rises above a predetermined value, the spring-loaded piston 66 of the pressure control valve 53 is moved downwardly so as to open the valve 67 and the gases then pass through ducts 43, 51, 69 and 61 to act on the upper sides of the pistons 76 and 46 whereby the gases are again diverted.