Patents by Inventor Marshall J. Smith

Marshall J. Smith has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • High pressure stepped clearance seal valve in a cryogenic refrigeration system
    Patent number: 4708165
    Abstract: In an expansion engine used in cryogenic refrigeration, a stepped inlet valve 10 and a stepped exhaust valve 11 are fluid activated to control high pressure gas such as helium into and out of the engine. Clearance seals in the stepped valve are achieved by sizing a small diameter of a stepped piston to a small bore and by sizing a sleeve 16 to a larger diameter of the stepped piston. The sleeve 16 fits loosely within a large bore, and is fixed into position by placing a wire of soft metal 9 between the sleeve and the wall of the cylinder.
    Type: Grant
    Filed: April 29, 1986
    Date of Patent: November 24, 1987
    Assignee: Helix Technology Corporation
    Inventors: Philip A. Lessard, Marshall J. Smith