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:
Dec. 18, 1979
Filed:
Sep. 05, 1978
Richard J Bremer, Grand Blanc, MI (US);
Daniel J Richardson, Swartz Creek, MI (US);
General Motors Corporation, Detroit, MI (US);
Abstract
A vehicle engine exhaust mounted oxygen sensor of the type producing an internally generated signal voltage and having a variable internal impedance is connected in series with a reference impedance and a semiconductor switch, the semiconductor switch having an impedance which may become large when current therethrough is very low. A constant current source is connected to supply current to the junction of the sensor and reference impedance at one sensor terminal and thus guarantee a minimum current and small switch impedance when the sensor impedance is large. Further apparatus samples the magnitudes of the voltage at the one sensor terminal with the semiconductor switch in its conducting and non-conducting states, the ratio of said magnitudes varying with sensor impedance. The ratio can be compared with one or more references to provide a warm sensor signal or control the operation of a sensor heater.