Mixing valve

Claim 1

A mixing valve for mixing two fluids in any desired proportion in accordance with the movement of a portion of said valve, comprising: a first member having a smooth face and a second member having a smooth face; means to relatively and rectilinearly move said first and second members with respect to each other in a longitudinal direction through a limited operating range, with the said smooth faces sliding on each other in fluid-tight contact; first, second, third and fourth metering ports in the smooth face of said first member, each of said metering ports being of tapered shape, and extending in the longitudinal direction and having, along an operating extent, a width, measured in a direction transverse to said longitudinal direction, which varies monotonically along said longitudinal direction, the sense of variation of said first and third metering ports being identical and the sense of variation of said second and fourth ports being opposite to the sense of variation of said first and third ports; scanning port means in said second member for cooperating with each of said metering ports, said scanning port means comprising plural, narrow slits extending transversely of said longitudinal direction, and being so located that each of the metering ports is concommitantly scanned over its said operating extent by its cooperating slit as the first and second members move relatively and rectilinearly with respect to each other over said limited operating range; each of said first, second, third and fourth metering ports and its cooperating narrow slit respectively defining first, second, third and fourth variable throttling valves, the hydraulic resistance of each of which varies monotonically with relative movement of said first and second members over said limited range, the hydraulic resistance of said first and third variable throttling valves varying in one sense, and that of the second and fourth variable throttling valves varying in the opposite sense with said relative movement.