GAS SENSOR WITH PUMP CELL AND ADDITIONAL OUTER ELECTRODE

• US 20100000864A1
• Filed: 02/09/2007
• Published: 01/07/2010
• Est. Priority Date: 03/13/2006
• Status: Abandoned Application

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Diehl, Lothar, Seiler, Thomas
• Application Number:
  US12/282,114
• Publication Number:
  US 20100000864A1
• Time in Patent Office: Days
• US Class Current: 204/425
• CPC Class Codes: G01N 27/419 Measuring voltages or currents with a combination of oxygen pumping cells and oxygen concentration cells

Abstract

The invention relates to a gas sensor, especially a lambda probe, for determining the oxygen concentration in the exhaust gas of an internal combustion engine that is operated with a fuel/air mixture. Said gas sensor comprises a pump cell arranged in or on a sensor element, said pump cell having a first electrode and a second electrode that are separated from the exhaust gas by at least one layer, and an electronic circuit for producing a voltage applied between the first electrode and the second electrode and for measuring and evaluating a pump current thereby produced in order to make it possible to draw conclusions therefrom on the composition of the fuel/air mixture. The invention is characterized in that an additional outer electrode is arranged on the sensor element. Said additional electrode is exposed to the exhaust gas and supplied with a negative current.

Claims

1-12. -12. (canceled)

13. A gas sensor, especially a lambda sensor, that determines an oxygen content in an exhaust gas of a combustion engine operated by a fuel-air mixture, the gas sensor comprising:

a pump cell formed with a sensor element, wherein the pump cell includes a first electrode and a second electrode, and wherein the first and second electrode are separated by at least one protective layer; and

an electronic circuit for the production of a voltage between the first electrode and the second electrode and for measurement and evaluation of a pump current in order to imply the composition of the fuel-air mixture;

wherein an additional outer electrode formed with the sensor element is exposed to the exhaust gas and impinged with a negative current.

14. A gas sensor according to claim 13, wherein the first electrode is arranged on a solid electrolyte that is formed with the sensor element and separated from the exhaust gas by at least one protective layer, and wherein the second electrode is positioned in a measuring volume that is formed in the solid electrolyte and separated from the exhaust gas by a diffusion barrier.

15. A gas sensor according to claim 13, wherein the first electrode and the second electrode are arranged on a solid electrolyte that is formed with the sensor element and are separated from the exhaust gas by at least one collective protective layer.

16. A gas sensor according to claim 13, wherein first electrode and the second electrode are arranged on a solid electrolyte that is formed with the sensor element and are separated from the exhaust gas by a plurality of separated protective layers.

17. A gas sensor according to claim 14, wherein the additional outer electrode is arranged on the solid electrolyte on a side that is opposite of the first electrode.

18. A gas sensor according to claim 13, wherein the additional outer electrode is covered by a protective layer.

19. A gas sensor according to claim 14, wherein the additional outer electrode is arranged on the solid electrolyte on a same side as the first electrode and the second electrode.

20. A gas sensor according to claim 19, wherein the additional outer electrode is separated from the exhaust gas by:

a. a protective layer that additionally covers the first electrode and the second electrode are also covered;

or

b. a protective layer that does not cover the first electrode and the second electrode.

21. A gas sensor according to claim 13, wherein the negative current is of a constant magnitude.

22. A gas sensor according to claim 13, wherein the additional outer electrode is provided with a unique signal line.

23. A gas sensor according to claim 13, wherein the additional outer electrode is electrically-conducting connected to the ground connection of a heating device.

24. A gas sensor according to claim 13, wherein the electronic circuit is an engine control unit or a part of an engine control unit.