Fluid flow regulating apparatus

Claim 1

In a fluid flow regulating apparatus, a combination comprising a master valve having a body provided with a fluid admitting inlet opening and a fluid discharging outlet opening, the pressure of fluid in one of said openings being variable, said master valve including further a valve member movable in said body between a plurality of positions to thereby change the rate of fluid flow between said openings and means for biasing said valve member in a first direction, said valve member having a first surface which is subjected to fluid pressure in said one opening so that the fluid in said one opening tends to move said valve member in a second direction counter said first direction, said biasing means including a plenum chamber and said valve member having a second surface which is subjected to the pressure of fluid in said chamber; first channel means connecting said one opening with said chamber; a tank; second channel means connecting said chamber with said tank; first adjustable flow restrictor means provided in said first channel means and comprising a portion which is movable between a plurality of positions to thereby change the rate of fluid flow in said first channel means; adjustable pilot valve means provided in said second channel means and comprising a portion which is movable between a plurality of positions including a closed position to thereby change the rate of fluid flow in said second channel means; and second flow restrictor means provided in said second channel means between said chamber and said pilot valve means, and comprising a first portion and a second portion movable with respect to said first portion to thereby change the rate of fluid flow through said second flow restrictor means, said second portion of said second flow restrictor mans being arranged to move said portion of said first flow restrictor means in response to movement of said portion of said pilot valve means and vice versa, said second flow restrictor means providing a maximum throttling action and said first flow restrictor means a minimum throttling action when said pilot valve means is in said closed position and said second portion of said second flow restrictor means being constructed and arranged to increase the throttling action of said first flow restrictor means at a first rate and simultaneously reduce the throttling action of said second flow restrictor means at a lower second rate when said pilot valve means moves away from said closed position in response to variations of fluid pressure in said one opening.