Patent ID: 6957666

Claim:
An improved low flow impedance three-way flow control valve for selectively distributing fluid flow entering an input port between first and second output ports, the improved low flow impedance three-way flow control valve generally being of the type having a housing; an axially oriented inlet port located in a first end of the housing; first and second annularly oriented output passages disposed within the housing and fluidly isolated one from another by a central housing bulkhead, the first annularly oriented output passage being located proximate to a first end of the housing and the second annularly oriented output passage being located proximate to the second end of the housing; and an axially moving valve spool, the valve spool being positioned by a valve stem and including an axially oriented flow channel, wherein the improvement comprises: a rolling diaphragm located proximate to the central housing bulkhead for fluidly isolating the output passages one from another and constraining the valve spool for axial movement within the housing; first spring valve means captured between the valve spool and a shoulder located within the first end of the housing for selectively metering a flow of fluid from the inlet port to the first output passage via a round edged helical orifice formed between the open coils of the first spring valve as a function of the instant axial position of the valve spool and the differential pressure therebetween; and second spring valve means captured between the valve spool and the second end of the housing for selectively metering a flow of fluid from the inlet port to the second output passage via the flow channel and a round edged helical orifice formed between the open coils of the second spring valve as a function of the instant axial position of the valve spool and the differential pressure therebetween.