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:
Oct. 09, 2001
Filed:
Feb. 24, 2000
Tim Walde, Regensburg, DE;
Eric Chemisky, Haar, DE;
Siemens Aktiengesellschaft, Munich, DE;
Abstract
A circuit for a NOx concentration sensor includes two connected measurement cells disposed in a solid-state electrolyte, a first circuit configuration that, by tapping off a first Nernst voltage (first reference variable), establishes in the cell an oxygen concentration that differs from that in a measured gas, a second circuit configuration that, by tapping off a second Nernst voltage (second reference variable), establishes in the cell an oxygen concentration that differs from that in the first cell, a third circuit configuration that, by tapping off a third Nernst voltage (third reference variable), drives a pump current of oxygen ions that originate from NOx, out of the second cell, a conditioning circuit, and a digital controller. The Nernst voltage is fed to the controller through the conditioning circuit, which shifts and amplifies the voltage such that the reference variable lies in a range around the control point of the controller, and a reference potential of a conditioned Nernst voltage equals that of the controller. The Nernst voltages, being previously preprocessed by the conditioning circuit, are used as a reference variable for regulating the oxygen ion pump current, which amplifies and shifts the Nernst voltages. As a result, a microcontroller with an 8-bit A/D converter can be employed, and A/D ports are saved.