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:
Apr. 10, 2001
Filed:
Nov. 06, 1997
NGK Spark Plug Co., Ltd., Aichi, JP;
Abstract
Using a sole Nox sensor Nox concentration and oxygen concentration are measured accurately. A measurement device for measuring NOx concentration and oxygen concentration comprises an NOx sensor,having a first measurement chamber,communicating via a diffusion rate regulating layer,with the gas under measurement and a second measurement chamber,communicating with the first measurement chamber,via diffusion rate regulating layers,. A first pump cell,and an oxygen concentration measurement Vs cell,are formed on the first measurement chamber,, while a second pump cell,is formed on the second measurement chamber,. Inside of the first measurement chamber,is controlled to a constant low oxygen concentration by controlling the first pump current IP,so that output of Vs cell,will equal a reference voltage VC,. By applying a constant voltage across the second pump cell,NOx in the second measurement chamber,is decomposed to pump out oxygen. Thus NOx concentration and oxygen concentration are measured from the second pump current IP,and from the first pump current IP,, respectively. During measurement, sensor temperature is detected from the internal resistance of the Vs cell for controlling heater current supplied to heaters,to maintain a constant sensor temperature.