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:
Feb. 14, 1995
Filed:
Jul. 01, 1993
Robert E Hetrick, Dearborn Heights, MI (US);
Ford Motor Company, Dearborn, MI (US);
Abstract
A sensor for determining the stoichiometric air to fuel ratio (A/F) at the intake of an internal combustion engine is based on a capacitive device in the exhaust stream which can be used to measure the change in the workfunction of an appropriate material which occurs at the stoichiometric point and which forms one of the two interacting elements of the capacitor. To measure A/F over an extended range about stoichiometry the material whose workfunction changes is made the working electrode of an oxygen concentration cell using a solid electrolyte. Oxygen pumping to and from that surface can change the magnitude of the workfunction allowing for a feedback control method for keeping the workfunction constant despite changes in the A/F so that the required pump current becomes a measure of the A/F.