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:
Jul. 25, 1995
Filed:
Nov. 02, 1993
Gordon P Sharp, Newton, MA (US);
Eric Desrochers, Nashua, NH (US);
Phoenix Controls Corporation, Newton, MA (US);
Abstract
Precision gas flow control is provided utilizing a first coarse gas flow control element and a second fine gas flow control element. The second element is selected and operated to pass only a fraction of the flow passed by the first element. The elements may be connected either in series or in parallel so that at least a portion of the gas flow passes through each flow control element. Control circuitry is also provided which may be responsive at least in part to an indication of desired gas flow through the device for controlling the first element to provide a coarse gas flow adjustment and for controlling the second element to provide a fine gas flow adjustment. In some applications, only fine flow adjustment may be provided. Where the elements are being utilized for example as the tracking flow control elements for a sealed enclosure, either the fine flow control element or both elements may also be made responsive to pressure errors in the enclosure.