Gas sensor for determining the concentration of gas components in gas mixtures and use thereof

• US 20040104114A1
• Filed: 09/30/2002
• Published: 06/03/2004
• Est. Priority Date: 12/15/1999
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Mueller, Bernd, Wahl, Thomas, Schulte, Thomas
• Granted Patent: US 7,052,595 B2
• Time in Patent Office: Days
• US Class Current: 204/426
• CPC Class Codes: G01N 27/4074 for detection of gases other than oxygen

Abstract

A gas sensor for determining the concentration of gas components in gas mixtures is used in particular to measure the concentration of nitrogen oxides in exhaust gases of internal combustion engines or in the interiors of motor vehicles. It contains an electrochemical measuring cell which includes a first electrode (31) situated on a solid electrolyte and an additional electrode (32). The electrode (31) is made of an oxide material containing lanthanum which at least catalytically decomposes nitrogen oxides. The pump current flowing between the electrodes (31, 32) is used as a measure of the nitrogen oxide concentration in the gas mixture.

Claims

1. A gas sensor for determining the concentration of gas components in gas mixtures, of NO_x in particular, having at least one electrochemical measuring cell, the measurement signal of which is used to determine the concentration of the gas component and which includes a first and at least one additional electrode applied to a solid electrolyte, at least one of the electrodes containing a material that at least catalytically decomposes nitrogen oxides, wherein the material that at least catalytically decomposes nitrogen oxides includes an oxide.

2. The gas sensor according to claim 1,

wherein the material that at least catalytically decomposes nitrogen oxides includes an oxide of at least one of the elements belonging to the lanthanoide group.

3. The gas sensor according to claim 1 and 2,

wherein the material that at least catalytically decomposes nitrogen oxides includes an oxide of lanthanum.

4. The gas sensor according to at least one of claims 1 through 3,

wherein the material that at least catalytically decomposes nitrogen oxides is an oxide of the composition La₁₋

x Sr_x CO<sub>1−

y</sub> Cu_y O<sub>3−

δ</sub>

.

5. The gas sensor according to at least one of claims 1 through 4, wherein the first electrode (31) and the additional electrode (32) are interconnected as a pump cell and the measured pump current is a measure of the concentration of the nitrogen oxides present in the gas mixture.

6. The gas sensor according to at least one of claims 1 through 5,

wherein the first electrode (31) is situated in a measuring gas space (13) integrated in a sensor element (10), the measuring gas space being in contact with the gas mixture via a gas inlet (21), and the first electrode (31) contains the material that at least catalytically decomposes nitrogen oxides.

7. The gas sensor according to at least one of claims 1 through 5,

wherein the first electrode (31) is situated on a wide surface area of a sensor element (10) exposed to the gas mixture, and the first electrode (31) contains the material that at least catalytically decomposes nitrogen oxides.

8. The gas sensor according to claim 7,

wherein the additional electrode (32) is also situated on the wide surface area of the sensor element exposed to the gas mixture.

9. The gas sensor according to at least one of claims 1 through 5,

wherein the first electrode (31) and the additional electrode (32) are situated on a wide surface area of a sensor element (10) exposed to the gas mixture;

the first electrode (31) contains the material that at least catalytically decomposes nitrogen oxides; and

the sensor element has a reference gas channel (19) having a reference electrode situated (33) within it, which is connected with the first electrode (31) to form a concentration cell.

10. The gas sensor according to claim 9,

wherein a solid electrolyte layer (37) is applied to the additional electrode (32), and the first electrode (31) is applied to the solid electrolyte layer (37).

11. Use of the gas sensor according to at least one of the preceding claims as an air quality sensor for determining the concentration of nitrogen oxides, in particular in the interior of motor vehicles.

12. Use of the gas sensor according to at least one of the preceding claims for determining gas components, in particular NO_x, in exhaust gases of internal combustion engines.