Patent ID: 9488163
Filing Date: 2016-11-08
CPC Classification: F04B

Claim Text:
1. A fluid system comprising: a. a source of hydraulic fluid under pressure, said source producing in use a varying flow comprising a plurality of local flow maxima and local flow minima, wherein adjacent maxima and minima are separated by at least a minimum time (Ta); b. a controller for controlling said source; c. a hydraulic fluid consumer; d. a valve passing fluid between said source and said fluid consumer, wherein the valve comprises a valve body having an aperture and an edge portion and a spool axially displaceable within said aperture; e. a first fluid compliance between said source and said valve; f. the spool being a variable restrictor for smoothly and continuously varying a cross sectional area available for flow of fluid through said valve and movable between a first position with a larger said area and a second position with a smaller said area, said spool having a tapered portion including a plurality of tapered fluted segments each having a tapered opening forming an orifice between itself and the edge portion of the body and each orifice having a cross-sectional area which varies according to the axial displacement of the spool; g. a bias means for biasing said restrictor towards said second position, said bias means providing a substantially constant biasing force; h. an opening means for urging said restrictor against said bias means when fluid flows through said valve, such that under steady flow, a pressure drop across said valve is low and varies little with changing flow; and i. a damping means for damping movement of said restrictor between said first and second positions and providing a resistance which increases with a velocity of displacement of said restrictor, characterized in that a time constant (Tr) of the damped movement of said restrictor is longer than said minimum time (Ta).