Electrochemical measuring sensor for determining nitrogen oxides in gas mixtures

US5879526A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Hermann Dietz · Gerlingen, DE
• Werner Gruenwald · Gerlingen, DE

Key dates

• Filing date: Mar 24, 1997
• Grant date: Mar 9, 1999
• Expiry date: Mar 24, 2017

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02A50/20
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

An electrochemical measuring sensor for selectively determining nitrogen oxides in a gas mixture including oxygen and nitrogen oxides, includes a solid electrolyte layer; a cover layer; and a diffusion channel which is defined between the solid electrolyte layer and the cover layer, and through which the gas mixture diffuses in a diffusion direction. The solid electrolyte layer has provided on a surface thereof a first cathode and a second cathode disposed one after the other in the diffusion direction of the gas mixture within the diffusion channel and exposed to the gas mixture in the order recited, and has provided on an opposite surface thereof at least one anode. The diffusion channel forms a diffusion barrier for the second cathode. The first and second cathodes and the at least one anode are gas permeable and consist of one of a precious metal or a precious metal alloy. The first cathode is provided with a coating which completely covers same, which is impermeable to nitrogen oxides (NO.sub.x), and which is permeable to oxygen. The first cathode, a portion of the solid electrolyte, and the at least one anode form a first pumping cell. The second cathode, another portion of t…