Patent GB-790030-A (GB)
Title: Pneumatic turbine drive control system
IPC: F01D17/20
Filed: 1955-12-08
Abstract: 790,030. Elastic fluid turbines. BENDIX AVIATION CORPORATION. Dec. 8, 1955 [Jan. 20, 1955], No. 35286/55. Class 110 (3). [Also in Group XXIX] The turbine rotor 2, Fig. 2, is driven by air from a control unit 6, Fig. 3, comprising a cylindrical member 10 with inflow ports 11 and outflow ports 12 connecting the inlet and outlet scrolls 14 and 15, respectively, the area of the outflow ports 12 being controlled by a sleeve 29 loaded by a compression spring 28 into the position shown wherein the ports 12 are unrestricted. The sleeve 29 is moved leftwards, to more or less cover the ports 12, by a piston 36 supplied through a fitting 39 with oil from a gear pump 41, Fig. 2, driven from the turbine shaft 3, under the control of a valve 43 only responsive to turbine speeds in excess of normal. The valve 43 comprises a hollow shaft 48 driven by the turbine shaft 3 and having lateral ports, the shaft 48 running in a bearing 50 embodying corresponding ports 55 and 63, leading to the pump and fitting 39, respectively; within the shaft 48 is a closure 64 with a tapered portion 51 provided with an adjustable loading spring 53 and operated by a number of bellcrank levers 57 with fly-arms 61. Upon the turbine exceeding its normal speed the valve 43 is moved to supply oil to the piston 36, Fig. 3, which urges the sleeve 29 to reduce the air supply to the turbine whereupon the turbine decelerates and spring 28 progressively restores the sleeve 29 and piston 36 as the valve 43 returns to its inoperative position, this action continuing in an oscillating manner to effect a controlled flow of air to the turbine; the oil from behind the piston 36 is drained via a passage 65, which latter communicates with a space around the cylinder 35, in which the piston 36 moves, and an end closure plug 25 thereof to cool these parts. The area of the inflow ports 11 is governed by a sleeve 77 loaded to the open position shown by a spring 74 and closed more or less by incoming air passing through apertures 94 and 96 and the hollow rod 91 of a cup-head piston 90 working in an extension 86 of another piston 85 urged to the position shown by a spring 87. When the air pressure exceeds the opposing force of the spring 74 the air acting on the piston 90 forces the sleeve 77 to the right to progressively close the ports 11 until the diminished inflow pressure is balanced by the spring 74; such pressure variations will cause the sleeve 77 to oscillate to provide a constant air flow pressure supply to the turbine. The piston 85 is associated with an emergency over speed arrangement consisting of a ball valve 106, Fig. 5, urged by a spring-loaded plunger 104 to cover an opening 107 into the inlet scroll 14, the plunger cylinder being connected by a line 103 to the piston 108, Fig. 2, of a dump valve 97 that is pressurized to the closed position by air which leaks from opening 107, Fig. 5, into the line 103 so enabling the valve 106 to close a conduit 99 leading to the piston 85. Upon the turbine over-speeding fly-balls 120, Fig. 2, in an extension of the turbine shaft 3, move outwardly and cause a mushroom headed rod.in the latter to move the piston 108 and open the dump valve 97 so that pressure in the line 103 is released and air from the scroll 14 passing through the opening 107 moves the ball 106 away from the end of conduit 99 to enable air to actuate the piston 85 and move the sleeve 77 to reduce the area of the ports 11.