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:
May. 05, 1987
Filed:
Jan. 28, 1985
William J Riordan, Shrewsbury, MA (US);
Other;
Abstract
A control system including a valve for controlling the flow of fuel to a burner, a resistive heater element connected between first and second terminals and disposed for igniting fuel emanating from the burner, an isolation transformer comprising a heater secondary winding connected to the first and second terminals so as to provide heating current to the heater element, and an electrode spaced from the heater element in a zone occupied by flame emanating from the burner. Also included is a start-up circuit for opening the valve to provide fuel to the burner for ignition by the heater element and a flame sensing circuit comprising an ac source, coupling means connecting the ac source means between the electrode and one of the first and second terminals with the secondary winding connected to the first and second terminals, and a detector circuit for detecting the flow between the electrode and the heater element of current conducted by flame in the zone. Finally, a valve control circuit maintains the valve open in response to an output signal provided by the detector.