Patent GB-810826-A (GB)
Title: Control mechanism for a steam turbine for use in ship propulsion
Inventor: ANDO TSUNEO
IPC: F01K15/04
Filed: 1955-06-08
Abstract: 810,826. Turbines. KAWASAKI JUKOGYO KABUSHIKIKAISHA. June 8, 1955, No. 16453/55. Class 110 (3). [Also in Group XXIX] Selection and control of the degree of opening of ahead and astern steam valves for a ship's propulsion turbine is effected by an oil-operated piston under the control of a manually actuated pilot valve, and a second pilot valve, responsive to the difference between. an oil pressure varying with turbine speed and an oil pressure related to the lubricating oil pressure of the turbine interconnects the two sides of the piston to shut down the turbine in the event of overspeeding or reduction of lubricating oil pressure. In an embodiment, the ahead and astern valves 3, 3<SP>1</SP> respectively are loaded by springs 7, 71 towards closure and operated by a piston 20 acting through a lever 9 pivoted at 10 and a link 21, the connection between the lever and the valve stems being a one-way connection whereby movement of the lever to open one of the valves is not hindered by the other valve which remains closed. Movement of the piston in either direction from a central, neutral position in which both valves are closed is effected by pressure oil admitted to the upper or lower side of the piston under the control of a pilot valve 30 coacting with a seating in the piston and operated by a cam 33 connected by gearing &c. to a handle ho. A second pilot valve 57 controlling communication between the two sides of the piston through passages 54, 55 is normally held in a position to prevent such communication by a balance between the force of a spring 60 and pressure in a pipe P2 on the one hand and the pressure in a pipe P3 on the other hand. The pressure in the pipe P2 is derived from impellers IP1, IP2 on high- and low-pressure turbine shafts and is thus speed-responsive whilst the pressure in the pipe P3 is dependent upon the pressure of lubricating oil supplied by a pump P. Hence, in the event of either overspeeding or reduction of lubricating oil pressure the valve 57 is depressed to equalize the pressures on the two sides of the piston 20 to allow it to be centred by the spring 7 or 7<SP>1</SP> of whichever of the valves 3, 3<SP>1</SP> is open. The pipe P2 has a branch connected to an adjustable leakage valve AV. The pump P delivers oil through a filter F, a cooler CL, a header tank HT, and a pipe lo leading to the turbine bearings and also through a pipe P1 leading to the piston 20 in addition to the pipe P3. The pipes P1, P3 lead through valves 72, 71 mounted on a common spindle loaded by a spring 74 so that oil is cut off from the piston 20 and the valve 57 when its pressure is below a predetermined value. An exceptionally low oil pressure in the pipe lo, transmitted through a pipe P4, allows a spring- loaded valve 80 to be opened so that the pump P supplies oil direct to the bearings. The consequential drop in oil pressure acting on the valves 71, 72 causes these valves to close. A valve 91 controlling an outlet from the pipe P3 is adjustable by a handle 97 to determine the speed at which the turbine is caused to be shut down. The valve 91 may be caused to open fully to shut down the turbine in an emergency by release of a catch 99. The valves 3, 3<SP>1</SP> may be operated in an emergency by handles h1, h2 acting through gearing &c. and levers 100, 101.