Sensor arrangement for determining gas components and/or gas concentrations of gas mixtures

• US 5,505,837 A
• Filed: 12/12/1994
• Issued: 04/09/1996
• Est. Priority Date: 04/10/1993
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Neumann, Harald, Schumann, Bernd, Gruenwald, Werner, Friese, Karl-Hermann, Riegel, Johann, Hoetzel, Gerhard, Dietz, Hermann
• Primary Examiner(s): Bell, Bruce F.
• Application Number:
  US08/290,704
• Time in Patent Office: 484 Days
• Field of Search: 204/425, 204/426, 204/427, 204/429, 204/424, 204/408
• 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

A sensor arrangement for determining at least one of gas components and gas concentrations of gas mixtures including CO, NO_x and HC in exhaust gases of internal combustion engines, includes a measuring element which has a sensitive region; and a pump cell that includes a solid electrolyte and inner and outer pump electrodes which are opposingly disposed at least on the solid electrolyte and which effect an oxygen transfer to the measuring element, wherein the pump cell and the measuring element are spatially separated from one another, are located in different temperature zones during operation of the sensor arrangement, and are connected to one another by a diffusion segment through which oxygen can diffuse from the pump cell to the measuring element.

Claims

1. A sensor arrangement for determining at least one of gas components and gas concentrations of gas mixtures including CO, NO_x and HC in exhaust gases of internal combustion engines, comprising:

a measuring element which has a sensitive region; and

a pump cell that includes a solid electrolyte and inner and outer pump electrodes which are opposingly disposed at least on the solid electrolyte and which effect an oxygen transfer to the measuring element,

wherein the pump cell and the measuring element are spatially separated from one another, in a lateral arrangement and are located in different temperature zones during operation of the sensor arrangement, and are connected to one another by a diffusion segment through which oxygen diffuses from the pump cell to the measuring element during operation of the sensor arrangement.

2. The sensor arrangement according to claim 1, wherein the sensor arrangement is a layer system in which the solid electrolyte is at least one oxygen-ion-conducting, solid electrolyte ceramic, wherein the diffusion segment is integrated into the layer system, and wherein oxygen pumped by the pump cell is supplied to the measuring element via the diffusion segment and via a diffusion opening provided, near the measuring element.

3. The sensor arrangement according to claim 2, further comprising a cover film, wherein the diffusion opening is a recess defined in the cover film, and wherein the measuring element including the sensitive region is disposed in the diffusion opening.

4. The sensor arrangement according to claim 3, wherein the measuring element is a semiconducting gas sensor.

5. The sensor arrangement according to claim 2, further comprising a cover layer which surrounds the diffusion segment in a gas-tight manner, wherein the diffusion opening is defined in the cover layer, and wherein a porous insulating layer is provided above the diffusion opening and onto which porous insulating layer is disposed the measuring element with the sensitive region.

6. The sensor arrangement according to claim 2, further comprising a cover layer surrounding the diffusion segment in a gas tight manner, wherein a diffusion opening is defined in the cover layer, and wherein the measuring element is an electrochemical measuring cell that is positioned with the sensitive region in the diffusion opening.

7. The sensor arrangement according to claim 6, further comprising a measuring electrode which is inserted into the diffusion opening, and wherein the inner pump electrode serves as a reference electrode for the measuring cell.

8. The sensor arrangement according to claim 7, further comprising a gas-tight cover which covers the sensitive region of the measuring cell and in which are defined recesses which define at least one measured gas opening, wherein the diffusion layer extends into the recesses defined in the gas-tight cover layer whereby measured gas is supplied to the sensitive region via the diffusion layer, and wherein the diffusion layer is in contact with the measured gas via the at least one measured gas opening.

9. The sensor arrangement according to claim 8, wherein the at least one measured gas opening is located in a temperature zone of the sensor arrangement in which the measured gas is exposed to a minimum pre-catalysis.

10. The sensor arrangement according to claim 8, wherein the diffusion segment is a porous diffusion layer.

11. The sensor arrangement according to claim 1, wherein the diffusion segment is a diffusion conduit.

12. The sensor arrangement according to claim 1, wherein the measuring element, the diffusion segment, and the pump cell are positioned so that an oxygen surplus is present at the sensitive region of the measuring element during operation of the sensor arrangement.

13. The sensor arrangement according to claim 1, wherein the pump cell and the measuring element respectively employ separate heating elements, each heating element having a respective heat output, which respective heat outputs provide respective operating temperatures.

14. The sensor arrangement according to claim 1, wherein the pump cell and the measuring element have respective temperature zones, each respective temperature zone having a temperature, and wherein the temperature of the temperature zone of the pump cell is about 700°

C. and the temperature of the temperature zone of the measuring element is about 500°

C.

15. The sensor arrangement according to claim 1, wherein the sensor arrangement further comprises at least one heating device for establishing respective operating temperatures for the pump cell and the measuring element and providing the different temperature zones.

16. The sensor arrangement according to claim 15, wherein the sensor arrangement is an assembly of layers having a ceramic substrate within which the at least one heating device is embedded.

17. The sensor arrangement according to claim 15,

wherein the sensor arrangement is an assembly of layers extending in a lateral direction parallel to the surface and in a vertical direction perpendicular to the surface,

wherein at least the pump cell and the measuring element are integrated within the assembly of layers, and are respectively disposed in the lateral direction so that the pump cell and the measuring cell are spatially separated from one another and whereby the pump cell and the measuring element are located in the different temperature zones during operation of the sensor arrangement, and

wherein the diffusion segment extends in the lateral direction from the pump cell to the measuring element.

18. The sensor arrangement according to claim 17, wherein the pump cell and the measuring element have respective temperature zones, each respective temperature zone having a temperature, and wherein the temperature of the temperature zone of the pump cell is about 700°

C. and the temperature of the temperature zone of the measuring element is about 500°

C.