Patent ID: 8225815

Claim:
A fluid flow regulator comprising: a valve assembly defining a fluid passage, the fluid passage including: a first port a second port; a sleeve defining a bore and a spool disposed in the bore; a sensing orifice disposed in the fluid passage between the first and second ports; a first variable orifice defined by a first annular groove in the sleeve and a first orifice in the spool, the first variable orifice being disposed in the fluid passage between the first port and the sensing orifice, wherein a first flow area of the first variable orifice varies in response to differential pressure across the sensing orifice as fluid flows through the fluid passage in a first direction from the first port to the second port and is fixed as fluid flows through the fluid passage in a second direction from the second port to the first port; a second variable orifice defined by a second annular groove in the sleeve and a second orifice in the spool, the second variable orifice being disposed in the fluid passage between the sensing orifice and the second port, wherein a second flow area of the second variable orifice is fixed as fluid flows through the fluid passage in the first direction and varies in response to differential pressure across the sensing orifice as fluid flows through the fluid passage in the second direction.