The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 31, 1992
Filed:
Sep. 12, 1990
Richard A Benson, Bedford, MA (US);
Steven M King, North Grafton, MA (US);
MKS Instruments, Inc., Andover, MA (US);
Abstract
An improved control and shut off valve assembly is disclosed. The preferred valve assembly provides sufficient forces to overcome biasing forces so as to provide adequate shut off at a leakage rate of less than 10.sup.-9 std cc/sec of He with an atmospheric differential of Helium applied across the valve seat of the assembly, and precise control of the flow rate, all as a function of a single electrical control signal. In accordance with another aspect the valve seat is made from a material softer than the valve seat engagement means so that the seat is coined by the valve seat engagement means when first used so as to insure tight tolerances for sealing the valve passageway during the shut off mode. Finally, in accordance with yet another aspect of the invention, the valve assembly is constructed with no separate parts within the flow path so as to maintain a clean passageway.