Patent ID: 7500490

Claim:
A rotary valve comprising: (a) a rotor having a rotor face rotatable about an axis perpendicular to the rotor face, wherein the rotor face has a plurality of openings, and wherein the rotor includes at least one passage connecting at least one pair of the plurality of openings; (b) a stator having a stator face in sealing contact with the rotor face to form a planar rotary valve seal having an outer periphery, wherein the stator face has a plurality of openings in which at least two openings are adapted to register sequentially with openings in the rotor face as the rotor rotates, wherein each opening in the stator face is connected to a respective passage through the stator, and wherein at least one of the passages through the stator is a stator vacuum passage directly connected to a vacuum pump; (c) a sealed valve chamber having an interior volume contiguous with the outer periphery of the rotary valve seal, which chamber is sealed from the atmosphere surrounding the rotary valve; and (d) a vacuum vent passage connected to the sealed valve chamber.