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. 09, 2008
Filed:
Dec. 27, 2002
Shigeru Miyata, Aichi, JP;
Noriaki Kondo, Aichi, JP;
Hiroshi Inagaki, Aichi, JP;
NGK Spark Plug Co., Ltd., Aichi, JP;
Abstract
Apparatus for detecting the NOx concentration includes a first measurement chambercommunicating with the gas under measurement via a diffusion rate defining layerand a second measurement chambercommunicating with the first measurement chambervia diffusion limiting layers. A first pump current IPis controlled so that an output of a Vs cellwill be equal to the reference voltage VCO for controlling the oxygen concentration in the first measurement chamberto a pre-set low value. A constant voltage is applied across the second pump cellfor decomposing the NOx component in the second measurement chamberfor 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 IPis corrected depending on an offset of the detected sensor temperature from the target temperature assuring detection of the NOx concentration to high accuracy.