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:
Mar. 18, 2003
Filed:
Dec. 18, 2000
NGK Spark Plug Co., Ltd., Aichi, JP;
Abstract
Apparatus for detecting the NOx concentration includes a first measurement chamber communicating with the gas under measurement via a diffusion rate defining layer and a second measurement chamber communicating with the first measurement chamber via diffusion limiting layers A first pump current IP is controlled so that an output of a Vs cell will be equal to the reference voltage VCO for controlling the oxygen concentration in the first measurement chamber to a pre-set low value. A constant voltage is applied across the second pump cell for decomposing the NOx component in the second measurement chamber for pumping out oxygen for detecting the NOx concentration from a second pump current IP The sensor temperature is detected from the internal resistance of the Vs cell for controlling the current supplied to the heaters If the temperature of the gas under measurement is changed rapidly, the sensor temperature is changed. The detected second pump current IP is corrected depending on an offset of the detected sensor temperature from the target temperature assuring detection of the NOx concentration to high accuracy.