Single axis three way selector valve for endoscopes

Claim 1

A single axis three way selector valve for connecting a common channel to one or the other of two sources, or to neither source, comprising: a valve body having said common channel, and a valve bore having a linear axis and a cylindrical wall; a common port interconnecting said valve bore and said common channel, a first source port and a second source port both passing into the body and opening into said valve bore, one on each axial side of the common port; a first valve spool on the same axial side of the common port as the first source port, a pair of peripheral sliding seals around said first valve spool axially spaced apart so as to span said first source port in the rest position of said first valve spool, first spring bias means pressing said first valve spool toward said rest position, and stop means on said body and said first valve spool limiting the movement of said first valve spool toward said common port to said rest position, and contact means on said first valve spool; a second valve spool on the same side of the common port as the second source port, two pairs of peripheral sliding seals around said second valve spool axially spaced apart from one another, a peripheral inlet relief in the surface of said second valve spool between the adjacent seals, one from each pair, said seals being so disposed and arranged that adjacent ones of said seals can span said second source port, a flow passage in said second valve spool interconnecting said peripheral inlet relief and the valve bore, by-passing one of said pairs of seals, a second spring bias means pressing said second valve body toward a rest position farthest removed from said common port where it closes said second source port, and stop means on said body and said second valve spool limiting the movement of said second valve spool away from said common port to said rest position, and contact means on said second valve spool, said contact means being spaced apart sufficiently to permit said second valve spool to more from its rest position to open said second source port, thereafter to engage and upon further axial movement also to move said first valve spool to open said first source port and close said second source port, said common port always being open.