Patent GB-269885-A (GB)
Title: Improvements in and relating to regulating mechanism for elastic fluid turbines
IPC: F01D17/00
Filed: 1927-04-06
Abstract: 269,885. British Thomson-Houston Co., Ltd., (Assignees of Standerwick, R. G.). April 23, 1926,. [Convention date]. Fluid governors; fluid relays.-Extraction turbines, mixed-pressure turbines, turbo-compressor sets, and the like are regulated by devices responsive to two operating conditions of the turbine, for example, the extraction pressure and the speed. An extraction turbine is provided with inlet valves 6, 7 opened successively by a cam shaft 14, and with a ring valve or overflow valve 30 controlling the flow from the extraction stage to the next lower stage, as described in Specification 7697/13, [Class 110 (iii), Turbines &c.]. A pump 135 driven by the turbine supplies oil continuously through orifices 141, 144 to pipes 143, 55. From the pipe 143 the oil flows through a branch pipe 146 to an annular chamber 72, whence it flows over the end of a pilot valve 74 and down through it back to the oil tank 136. Pilot valve 74 builds-up a pressure in the pipes 143, 146 and hence under a piston 25 actuating the inlet valves 6, 7. From the pipe 55 the oil flows to an annular chamber 54, whence it flows through a pilot valve 49 back to the tank 136, the valve 49 maintaining a pressure in the pipe 55 and casing 118 so as to operate a bellows 117 to hold a lever 113 in a predetermined position when the turbine runs at the desired speed. With increasing turbine speed, a speed governor 46 lowers the pilot valve 49 relatively to its restoring bushing 52, permitting oil to escape more rapidly from pipe 55, whereupon a spring 119a distends the bellows 117 and turns the lever 113, thereby pulling down a three-arm lever 110, 111, 112 and compressing bellows 121, 131. Bellows 121 by its compression draws fluid from a casing 124 and distends bellows 125, turning a bell-crank lever 41 so as to move a lever 37 and a pilot valve 36 to the left, whereupon a piston 34 is moved to the right to close somewhat the ring valve 30. Bellows 131 by its compression draws fuid from a casing 79, thereby distending bellows 78 and lowering the pilot valve 74 to permit oil to escape more rapidly from the pipe 146. This lowers the pressure under the piston 25, which moves downwards and closes somewhat the inlet yalves 6, 7. A follow-up device 84, 82 restores pilot valve 74 and prevents overtravel of the piston 25. Upward movement of the bellows 117 draws liquid from a casing 64, distending bellows 63 and moving by means of a lever 59 the restoring bushing 52 downwards to prevent overtravel of the governing mechanism. With a decreasing turbine speed, the ring valve 30 and the inlet valves 6, 7 are given an opening movement. If the pressure in the extraction conduit 29 decreases, a pipe 148 communicates the decrease in pressure to a casing 94; this distends a bellows 95 and turns a lever 101, moving a link 109 and the lever arm 110 to the left and thereby lowering the outer end of lever 111 and raising the outer end of lever 112, which through the medium of the bellows 121, 131 results in a closing movement of the ring valve 30 and an opening movement of the valves 6, 7. The relation between the operation of ring valve 30 and the valves 6, 7 may be adjusted by adjusting lever arms 111, 112 relative to the lever arm 110 by means of a slot 112b. The bushing 52, Fig. 5, may be adjusted relatively to the pilot valve casing 51 either manually, by a handwheel 57, or by means of an electric motor 58, as described in Specification 265,398. One end of lever 59 is fulcrumed on the upper end of a rod 60, the position of the fulcrum point being adjustable by using the holes 61. An inverted elastic connection 108, as described in Specification 269,887, serves to modify the characteristic of the simple elastic connection comprising bellows 95 and spring 99 to the desired extent. The major portion of the control apparatus is carried by a pedestal 90, and has only pipe connections with the turbine, thus avoiding the necessity of mounting a large number of levers and rods on the turbine.