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:
Sep. 05, 1989
Filed:
May. 04, 1988
NGK Spark Plug Co., Ltd., Aichi, JP;
Abstract
An apparatus for sensing air-fuel ratio of the present invention is capable of measuring an air-fuel ratio of the air-fuel combustion mixture by sensing a partial pressure of oxygen in the exhaust gas. This apparatus forms a gas regulation chamber by arranging oxygen ion conductive solid electrolytes opposite to each other through a gap. In the gas regulation chamber, diffusion of exhaust gas is regulated. Porous electrodes are formed on both sides of the solid electrolytes. One sensor element formed by one of the solid electrolytes is operated as an oxygen concentration cell element, while the other sensor element formed by the other solid electrolyte is operated as an oxygen pump element. Moreover, the sensor elements are heated in order to activate such elements by heaters provided separately. A constant current is supplied to the oxygen concentration cell element in such a direction as pumping the oxygen into the gas regulation chamber. Supply of a constant current to the oxygen concentration cell element allows existence of a fixed output voltage from the oxygen concentration cell element even when the heater voltage changes. Accordingly, an air-fuel ration can be sensed accurately, independent of change in heater voltage which has been considered as a cause of problem, by controlling a supply current to the oxygen pump element so that an output voltage of the oxygen concentration cell element becomes the fixed voltage and then sensing the air-fuel ratio from such current value.