Exhaust gas probe

• US 6,676,818 B1
• Filed: 03/30/2001
• Issued: 01/13/2004
• Est. Priority Date: 07/30/1998
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Renz, Hans-Joerg, Schneider, Jens Stefan, Neumann, Harald, Diehl, Lothar, Schumann, Bernd, Heimann, Detlef
• Primary Examiner(s): Tung, T.
• Application Number:
  US09/744,842
• Time in Patent Office: 1,019 Days
• Field of Search: 204/421-429, 204/408
• US Class Current: 204/424
• CPC Class Codes: G01N 27/407 for investigating or analysing gases G01N27/411 takes precedence

Abstract

For the reduction of internal stresses and formation of cracks caused thereby, an exhaust gas probe includes two measuring electrodes separated by a solid electrolyte layer made substantially of ZrO₂ and a circuit-board conductor layer for electrically heating the solid electrolyte layer. The circuit-board conductor layer is firmly connected to the solid electrolyte layer via a first sealingly sintered insulating layer made of an Al₂O₃-containing material. A pore-forming material is added to the Al₂O₃-containing material before. sintering.

Claims

1. An exhaust gas probe, comprising:

a measuring electrode;

a reference electrode;

a solid electrolyte layer separating the electrodes, the solid electrolyte layer being formed substantially of ZrO₂;

a first sealingly sintered layer formed of an Al₂O₃-containing material, the Al₂O₃-containing material containing less than 50 ppm of sodium, the first sealingly sintered layer including pores, wherein the pores are formed by a pore-forming material added to the Al₂O₃-containing material before sintering and wherein the pore-forming material is not present after the sintering; and

a circuit-board conductor layer configured to electrically heat the solid electrolyte layer, the circuit-board conductor layer being firmly connected to the solid electrolyte layer via the first sealingly sintered layer.

2. The exhaust gas probe according to claim 1, wherein an average particle size of the Al₂O₃-containing material is approximately 0.3 μ

m.

3.The exhaust gas probe according to claim 2, wherein the pore-forming material includes finely divided carbon.

5. The exhaust gas probe according to claim 1, wherein an average particle size of the pore-forming material is approximately 1 to 10 μ

m.

6. The exhaust gas probe according to claim 1, wherein the Al₂O₃-containing material includes up to 10% of ZrO₂.

7. The exhaust gas probe according to claim 1, wherein the Al₂O₃-containing material includes a fluxing agent, wherein the fluxing agent as recited is only present prior to sintering.

3. The exhaust gas probe according to claim 3, wherein the finely divided carbon includes glassy carbon.

4. The exhaust gas probe according to claim 4, further comprising:

a second sealingly sintered layer made of the Al₂O₃-containing material, wherein the first and second sealingly sintered layers have a carbon content up to 10% on a mass basis of the first and second sealingly sintered layers, wherein the carbon content as recited is only present prior to sintering.

8. The exhaust gas probe according to claim 8, wherein the fluxing agent includes one of barium fluoride, lithium fluoride, ammonium fluoride, and an organically bound fluorine.

9. An exhaust gas probe, comprising:

a measuring electrode;

a reference electrode;

a solid electrolyte layer separating the electrodes, the solid electrolyte layer being formed substantially of ZrO₂;

a first layer formed of an Al₂O₃-containing material, the Al₂O₃ of the Al₂O₃-containing material includes, in an unsintered condition, at least 80% α

-Al₂O₃, the Al₂O₃-containing material containing less than 50 ppm of sodium, the first layer including a pore forming material;

a circuit-board conductor layer configured to electrically heat the solid electrolyte layer, the circuit-board conductor layer being firmly connected to the solid electrolyte layer via the first layer.