US 4,719,938 A · Self-cleaning valve and cryopump utilizing the same

Abstract

The pressure relief valve is debris resistant, self-cleaning, and self-actuating in a cryopump. It includes an o-ring carried by a valve member within a valve cylinder. In opening, the valve member moves away from an end port to open vent ports in the side of the valve cylinder while withdrawing the o-ring to a debris free and protected region of the valve. As the valve member is moved into the closed position in response to an atmospherical pressure differential, a wiper ring cleans debris from the inner surface of the valve cylinder. A taper is provided on the inner surface of the cylinder to release compression on the vacuum sealing o-ring upon opening and to compress the o-ring as the valve member moves to the closed position. The wiper ring is expansible in order to provide a wiping action along the entire taper and prevent debris from reaching the o-ring. The end of the valve cylinder opposite to the end port serves as a shock absorber as the valve is opened. An outer connecting flange is provided for connection of an exhaust housing.

Claims12

Dependent claims

A cryopump having a pressure relief valve, the valve comprising:

a valve cylinder having at least one inlet port in communication with a cryopump chamber and at least one exhaust port;
a valve member within the cylinder having a seal ring for pressing against the inner surface of the cylinder to close the end port from the exhaust port, the valve member further comprising a wiper ring having a tapered outer periphery for preceding the seal ring along the inner surface of the valve cylinder as the valve member is moved to the closed position to wipe debris from the inner surface of the valve cylinder.

Dependencies are inferred from the claim text.

Self-cleaning valve and cryopump utilizing the same

Life of this patent

Self-cleaning valve and cryopump utilizing the same

Life of this patent

Abstract

Claims12