Patent GB-722065-A (GB)
Title: Improvements relating to fuel supply systems
IPC: H02P5/69
Filed: 1952-08-05
Abstract: 722,065. Gas-turbine plant. GENERAL MOTORS CORPORATION. Aug. 5, 1952 [Aug. 10, 1951], No. 19646/52. Class 110 (3). [Also in Groups XXIX and XXXVII] A power plant comprising two independently operable gas-turbine engines having a fuel control for each engine and a conduit for each fuel control to the corresponding engine has means for interconnecting the fuel conduits so that fuel can be supplied to both engines jointly by the two fuel controls. The power plant shown comprises two gas turbines A, A<SP>1</SP> connected through clutches B, B<SP>1</SP> to the reduction gear C of a propeller D. The fuel-supply systems to the units are identical and each comprises anengine fuel pump 14 which discharges through a throttle valve 21, non-return valve 23 and a shut-off valve 26 to the engine. The pressure drop across the valves 21, 23 and 26 is maintained substantially constant by a by-pass valve 34 so that the fuel flow through the valve 21 is proportional to the opening of the valve. The shut-off valve 26 is operated by a solenoid 46 energized from the bus-bar 47 through a speed-responsive switch 48 and a manually operated switch 49. The arrangement is such that when the switch 49 is closed, the valve 26 is opened when the switch 48 is closed by the governor 51 when the gas turbine reaches a predetermined speed. The switch 49 is used to put the engine out of operation. The fuel-supply systems of the two engines are interconnected through conduits 52, 52<SP>1</SP> and normally closed solenoid-operated valve 53. The operating solenoid 54 is energized from the bus-bar 47 through a manually operated switch 56 and speed-responsive switches 57, 571 arranged in series. The switches 57, 57<SP>1</SP> are of the make-before-break type and are actuated by the speed-responsive devices 51, 51<SP>1</SP>. The intermediate number 58 of the switch 57 engages the contact 59 until the engine reaches the upper limit of the normal speed range and engages the contact 61 when the engine reaches the lower limit of the normal speed range so that during the normal speed range a circuit is completed through the contacts 59, 61. Thus the valve 53 is opened only when the switch 56 is closed and both engines 'are in the normal speed range. If either engine is not operating in this range the valve 53 is closed and cannot be opened by operation of the switch 56. The valves 26 and 53 can normally be opened and closed by a suitable arrangement of the circuits. It is not essential that the fuel pumps 14 be driven by the engines or that separate fuel pumps be provided. In a modification, the valves 26, 26<SP>1</SP> and 53 are replaced by two three-position valves driven by electric motors. The valves are arranged after the check-valve 23 so that in one position the lines 24, 27 and 52 are all closed at the valve, in the second position the lines 24, 27 are connected and line 52 shut off and in the third position all three lines are connected together. The electrical circuit for controlling the motors driving the valves is described. The throttles 21 may be connected to common throttle-operating lever 28 or may be independent, in which case the throttles should be at approximately the same position before the fuel systems are interconnected. The power plants may drive any type of load and need not be connected to a common load.