GB190803979A - Improvements in or relating to the Valves of Mixed Pressure Turbines. - Google Patents

Abstract

3979. Fraser & Chalmers, and Whitmore, F. L. Feb. 21. Elastic-fluid turbines.-Low and high pressure admission valves for a mixed - pressure turbine driven by fluid pressure are connected together by link-work, so that as the low-pressure valve automatically opens or closes in accordance with the pressure of the fluid, the high-pressure valve closes or opens to a corresponding extent. Apparatus is provided whereby the governor also controls both valves through an auxiliary piston and cylinder, and the apparatus is especially applicable to turbines driven by exhaust steam from other engines, where supplementary high-pressure steam is introduced when the pressure of the exhaust steam falls too low. The stem B' of the low-pressure valve B carries a piston b moving in a cylinder b<1>, which is open to a constant low pressure and contains a spring b<2>. The valve B is thus automatically opened to an extent corresponding to the pressure of the exhaust steam, and is connected by link-work through a floating lever H to the high - pressure valve A. Both valves are controlled by a governor C through link-work and the lever H, which is pivoted to the stem D<1> of a piston D moving in a cylinder which is supplied with fluid from any source through a slide valve E and ports F<1>, F'. As the governor moves, it operates the valve E through a link K, and admits fluid through an inlet F<3> to one side of the piston D, which moves and then again shuts the valve E. The piston D thus follows the movements of the governor, and controls both valves A, B while its position is independent of the pressure of the fluid, and the lever H remains with its fulcrum point fixed. A cataract piston J is provided to steady the motion of the lever H, to which it is connected. A hand-wheel M is provided for screwing-down the valve B into the closed position when necessary.