Fluid control spool valve

A spool valve for controlling the flow of fluid therethrough comprising a valve block with a bore extending therethrough with a counterbore portion at one end thereof and with an upper cylindrical inlet port, a central cylindrical outlet port, and a lower cylindrical exhaust port spaced apart axially along said bore and communicating said bore with the outside of said valve block, said ports having predetermined cross-sectional dimensions, said valve including an elongated spool slidable axially within said bore with close tolerances therebetween, said spool having an upper free end and a lower end with said lower end being attached to elements for manually controlling the movement of said spool in said valve block, and said free end being located within the confines of said valve block and adjacent said counterbore portion, a removable cover for closing said counterbore portion to the outside atmosphere, said spool having a right cylindrical portion of a length of a reduced diameter, an upper end, a lower end, an O-ring seal carried by said spool and spaced axially away from, but closely adjacent to respective said upper end and lower end of said spool, and a third O-ring seal positioned between said inlet port and said outlet port and adjacent to said inlet port, said valve block including means to equalize the pressure in said outlet port with the pressure in said counterbore portion, and a compression spring located in said counterbore portion to bias said spool to move to a closed position when no fluid flow between said inlet and outlet ports is permitted, and means for throttling the fluid as said spool moves axially with respect to said inlet and exhaust ports, said means for throttling including small lands of a predetermined length less than the cross sectional dimensions of said inlet and outlet ports and of a diameter substantially equal to the spool diameter being located closely adjacent to upper and lower ends of said lengthwise portion of reduced diameter to provide a controlled throttling action on fluid during spool movement axially during initial opening and closed of said inlet and exhaust ports.

A fluid control spool valve comprising a valve block with an elongated valve spool bore extending through said block, an elongated stem slidable lengthwise in said bore, said valve block further including an upper cylindrical inlet port, a central cylindrical outlet port, and a lower cylindrical exhaust port with a first, second and third passageway communicating between said bore and outside of said valve block, said ports having predetermined cross-sectional dimensions, said valve spool having a lengthwise portion of reduced diameter to provide fluid communication between two of said three ports at selected axial positions of said spool within said bore, said spool having three spaced O-ring seals carried by said spool to prevent leakage of fluid between said two of said three ports, means to equalize fluid pressure in said outlet port with such pressure being exerted axially on said spool and to move said spool to a closed position, and spring means biased to maintain said spool in a closed position, means for throttling the fluid as said spool moves axially with respect to said inlet and exhaust ports, said means for throttling including small lands of a predetermined length less than the cross sectional dimensions of said inlet and outlet ports and of a diameter substantially equal to the spool diameter being located closely adjacent to upper and lower ends of said lengthwise portion of reduced diameter to provide a controlled throttling action on fluid during spool movement axially during initial opening and closing of said inlet and exhaust ports.