Patent GB-917505-A (GB)
Title: Improvements in or relating to speed governor devices
Inventor: BASFORD KENNETH ARNOLD
IPC: F02K3/00
Filed: 1958-07-15
Abstract: 917,505. Fluid-pressure servomotor-control systems. ROLLS-ROYCE Ltd. June 18, 1959 [June 15, 1958], No. 22726/58. Class 135. [Also in Group XXVI] Fuel system-general arrangement.-A gasturbine engine 11 driving a variable pitch propeller 18, has separate or combined pilot and main fuel injectors 14 connected to manifolds 19, 20 respectively, supplied from a tank 21 by a booster pump 23, a low-pressure line 24, a main swash-plate fuel pump 25, a highpressure line 26, a throttle and control unit 27 and lines 28, 29. The fuel system includes a low-pressure governor 30 driven by the lowpressure compressor 11 and a high-pressure governor 32 driven via the pump 25 from the high-pressure compressor 12. Fuel pump.-The swash plate 35 of the pump 25 is controlled by a piston 36, both sides of which are connected to the pump delivery, one side 38 being supplied through a restrictor 41 and having two pipes 43, 44 leading therefrom to the governors 30, 32 respectively. Throttle and control unit.-The unit 27 has an inlet duct 45 connected to line 26 and leading to a throttling device downstream of which is a plunger 46 operated by a lever 46b and controlling flow to both a duct 47 that opens to line 28 and a duct 48 leading to line 29; the duct 48 houses a valve 50 actuated by the fuel therein and the valve is carried by a piston 52 having its opposite sides interconnected, the piston being urged upwardly by a spring 51 and pump inlet pressure led through ducts 53 from line 24. At starting an electrically-actuated plunger 62 closes a passage 63 so that fuel from line 26 only reaches line 28 via an adjustable by-pass 58, a plunger 54 and a passage 55. At a given engine speed the plunger 62 is opened so that fuel may additionally reach the passage 55 via a plunger 67, an adjustable by-pass 71 and a passage 68. Upon moving the pilots lever 73 from the idling position shown to an increased forward thrust position the plunger 54 is moved to increase the flow into passage 55 and the plunger 67 is positioned to prevent flow into passage 68. When the lever 73 is moved into the reverse pitch range the plunger 67 increases the flow to passage 68 and plunger 54 prevents flow into passage 55. Speed governors. The governor 30 includes chambers 81, 92 separated by a diaphragm 80, chamber 81 being connected to both line 26 through a restrictor 82 and to a chamber 86 via a restrictor 84, which latter chamber has an outlet 89 through a rotor 87 and a chamber 90 therein which is connected by a pipe 91 to line 24, the chamber 92 being also connected to the line 24. The rotor 87 houses a hinged member 88 and a diaphragm 88a which is loaded by the pressure-drop across the outlet 89, the member 88 co-operating with the outlet 89 to vary the area thereof; the centrifugal load on the lever 88 is balanced by the hydraulic load on the diaphragm 88a so that the pressure drop across the outlet 89 and hence the pressure in the chamber 86 is dependent upon rotational speed of the low-pressure compressor. The governor 30 is also responsive to the rate of fuel flow to the engine due to restrictor 84 since any change in the latter whilst not affecting the speed-pressure relationship in chamber 86 will bring about a net change in the pressure drop across the diaphragm 80, thus effecting a degree of speed anticipation and governor stability. The restrictor 84 may be replaced by a spring-loaded valve, not shown, through which fuel flows to create a pressure drop thereacross opposing its spring loading. The diaphragm 80, which operates a hinged valve 103 controlling the pipe 43, is connected by an adjustable spring 94 to a lever 95 having a cam track 99 engaged by a roller 97 on an arm 98 connected to the pilot's lever 73, movement of which adjusts the tension in the spring 94. To reduce the load between the roller 97 and the track 99 the loading due to spring 94 is opposed by a spring 101. The governor 32 prevents over-speeding of the high-pressure compressor and embodies a chamber 105 connected to the line 26 via a restrictor 107 and having an outlet 108 through a rotor 109 under the control of a hinged speedresponsive member 110; the interior of the rotor 109 is connected by ducts 112 to a chamber 113 having a connection 114 to the line 24. Chamber 113 is divided by a spring-loaded diaphragm 115 from a chamber 116 leading to chamber 105, the diaphragm 115 actuates a hinged valve 119 controlling pipe 44 when the speed reaches a given value. Air intake pressure control.-In the unit 27 is a pair of capsules 121, 122, the former being evacuated and the latter being subjected to engine air intake pressure, the capsules being of equal area and connected to a hinged valve 125 controlling a further outlet from pipe 44; the valve 125 is also loaded by a spring- urged piston 129 the top of which is open to line 26 and the underside to passage 55 so that changes in air intake pressure result in corresponding changes of pressure drop across the throttling device and hence for a given setting of the latter the fuel flow to the engine is varied. Specifications 849,131 and 850,037 are referred to.