Patent ID: 8561630

Claim:
A dual gas source changeover valve comprising: a valve body having a Tee housing with a T-shaped cavity, which comprises a first inlet port, a second inlet port axially disposed opposite to the first inlet port, and an outlet port perpendicularly disposed in middle of the axially disposed first inlet port and second inlet port, where the first inlet port, the second inlet port and the outlet port are in fluid communication; a spool having a structure relative to an axial passage of the cavity of the valve body between the first inlet port and the second inlet port, and which is slidably disposed within the valve body; characterized in that the cavity of the valve body comprises a large-section cavity in middle, a first valve body contraction segment, and a second valve body contraction segment axially disposed opposite to the first valve body contraction segment, where the first valve body contraction segment and the second valve body contraction segment are small-section cavities which are co-axially disposed at and outwardly protrude from two ends of the large-section cavity respectively; the spool comprises a large-section cylindrical body in middle which has a cross section relative to the large-section cavity and axial dimensions smaller than axial dimensions of the large-section cavity; a first small-section segment and a second small-section segment which are co-axially disposed at and outwardly protrude from two ends of the large-section cylindrical body respectively have cross sections relative to the first valve body contraction segment and the second valve body contraction segment and axial dimensions which allow them to be disposed within the first valve body contraction segment and the second valve body contraction segment at any position inside the axial passage of the cavity; characterized in that end surfaces of the cavity of the valve body and the large-section cylindrical body of the spool form a first transition cavity between the first inlet port and the outlet port and a second transition cavity opposite to the first transition cavity and between the second inlet port and the outlet port; delivered gas is introduced into or discharged from the first transition cavity or the second transition cavity in order to control pressures of the two transition cavities, thereby selectively connecting or disconnecting the first inlet port, the first transition cavity and the outlet port or the second inlet port, the second transition cavity and the outlet port; characterized in that at least one outlet connection channel is disposed between the outlet port and the first transition cavity and between the outlet port and the second transition cavity.