OPTICAL SENSING IN AN ADVERSE ENVIRONMENT

• US 20110185786A1
• Filed: 02/02/2011
• Published: 08/04/2011
• Est. Priority Date: 10/31/2008
• Status: Active Grant

• Current Assignee: Cummins Incorporated
• Original Assignee: Cummins Incorporated
• Inventors: Lindner, Frederick H., Wong, Jacob Y.
• Granted Patent: US 8,648,322 B2
• Time in Patent Office: Days
• US Class Current: 73/23.31
• CPC Class Codes: G01N 15/10 Investigating individual particles
• CPC Class Codes: G01N 21/15 Preventing contamination of the components of the optical system or obstruction of the light path

Abstract

A method includes flowing gases including combustion byproducts past an exposed face of an optical element in an engine fluid conduit, and depositing debris on the exposed face of the optical element. The debris may be soot, unburned hydrocarbons, sulfates, and/or a reductant precipitate. The method further includes passing electromagnetic (EM) radiation through the optical element and the flowing gases and interrogating the EM radiation after passing through the optical element and the flowing gases to determine an amount of debris accumulated on the exposed face of the optical element. The method further includes heating a resistive wire thermally coupled to the optical element sufficiently to remove accumulated debris from the exposed face in response to the amount of debris exceeding a threshold.

Claims

1. An apparatus, comprising:

an optical element structured to transmit electromagnetic radiation of one or more selected wavelengths therethrough, the optical element including having an exposed face to an engine fluid conduit having combustion byproduct gases therein;

an electric heating element thermally coupled to the optical element, wherein the electric heating element is structured to heat the optical element sufficiently to remove accumulated debris; and

wherein the accumulated debris comprises at least one member from the group consisting of;

soot, unburned hydrocarbons, sulfates, and reductant precipitate.

2. The apparatus of claim 1, wherein the electric heating element comprises one of nickel and a nickel alloy.

3. The apparatus of claim 1, wherein the electric heating element comprises a portion of an electrical circuit, the electrical circuit including a casing for an optical sensor defining the optical element, and a metal tube that conveys electromagnetic (EM) radiation to the optical element from an EM source.

4. The apparatus of claim 3, wherein the exposed face cooperates with the casing to seal the optical sensor from the engine fluid conduit.

5. The apparatus of claim 3, wherein the exposed face cooperates with the casing and a filler material to seal the optical sensor from the engine fluid conduit.

6. The apparatus of claim 5, wherein the filler material comprises one of mineral wool and ceramic filler.

7. The apparatus of claim 5, wherein the filler material electrically isolates the electric heating element from the casing except at a point of intentional contact.

8. The apparatus of claim 1, wherein the exposed face cooperates with a metal tube to seal the optical sensor from the engine fluid conduit, wherein the metal tube conveys electromagnetic (EM) radiation to the optical element from an EM source.

9. The apparatus of claim 1, wherein the electric heating element comprises an electrically resistive wire.

10. The apparatus of claim 1, further comprising a means for removing accumulated debris from the optical element.

11. A method, comprising:

flowing gases including combustion byproducts past an exposed face of an optical element in an engine fluid conduit;

depositing debris on the exposed face of the optical element, the debris comprising at least one member from the group consisting of soot, unburned hydrocarbons, sulfates, and reductant precipitate; and

heating a resistive wire thermally coupled to the optical element sufficiently to remove accumulated debris from the exposed face.

12. The method of claim 11, further comprising performing the heating periodically.

13. The method of claim 11, further comprising optically detecting an amount of accumulated debris, and performing the heating in response to determining the amount of accumulated debris is greater than a threshold.

14. The method of claim 11, further comprising providing an electrical circuit comprising a metal tube conveying electromagnetic (EM) radiation to the optical element, the resistive wire, and a casing for an optical sensor defining the optical element.

15. A method, comprising:

flowing gases including combustion byproducts past an exposed face of an optical element in an engine fluid conduit;

depositing debris on the exposed face of the optical element, the debris comprising at least one member from the group consisting of soot, unburned hydrocarbons, sulfates, and reductant precipitate;

passing electromagnetic (EM) radiation through the optical element and the flowing gases;

interrogating the EM radiation after passing through the optical element and the flowing gases to determine an amount of debris accumulated on the exposed face of the optical element; and

heating a resistive wire thermally coupled to the optical element sufficiently to remove accumulated debris from the exposed face in response to the amount of debris exceeding a threshold.

16. The method of claim 15, further comprising heating the resistive wire in response to an elapsed time since a previous heating event exceeding a time threshold.

17. The method of claim 15, wherein the EM radiation is responsive to soot and debris and substantially non-responsive to other constituents of the flowing gases, wherein the interrogating comprises one of:

determining a baseline observed EM radiation response comprising a lowest observed EM radiation response over a recent time period, and determining the amount of debris in response to the baseline observed EM radiation response; and

tracking a fast observed EM radiation response and a slow observed EM radiation response, and determining the amount of debris according to the slow observed EM radiation response and an amount of soot according to the slow observed EM radiation response subtracted from the fast observed EM radiation response.

18. A system, comprising:

an internal combustion engine having an engine fluid conduit having exhaust combustion byproduct gases therein;

an optical element having an exposed face to the engine fluid conduit;

a resistive wire thermally coupled to the optical element such that the resistive wire, when heated, heats the exposed face sufficiently to remove accumulated debris; and

wherein the accumulated debris comprises at least one member from the group consisting of;

soot, unburned hydrocarbons, sulfates, and reductant precipitate.

19. The system of claim 18, wherein the engine fluid conduit comprises a conduit selected from the group consisting of an intake port for a cylinder, an exhaust port for a cylinder, an individual cylinder combustion chamber, an exhaust gas recirculation loop, an exhaust conduit, an intake manifold, and an exhaust manifold.

20. The system of claim 18, further comprising a metal tube that conveys electromagnetic (EM) radiation to the optical element from an EM source.

21. The system of claim 18, wherein the metal tube comprises at least one metal selected from the metals consisting of extruded aluminum, extruded stainless steel, a polished metal, and a machined metal.

22. The system of claim 18, wherein the optical element comprises a material selected from the materials consisting of sapphire, diamond, and glass.

23. An apparatus, comprising:

an internal combustion engine including;

a sensor responsive to one or more wavelengths of electromagnetic radiation to detect one or more selected constituents of a working fluid in the engine;

an optical element structured to transmit the one or more wavelengths of electromagnetic radiation therethrough, the optical element including a face in fluid communication with the working fluid, the face being susceptible to accumulation of debris that at least partially occludes transmission of the one or more wavelengths therethrough; and

a heating element thermally coupled to the optical element, the heating element being structured to heat the optical element sufficiently to at least partially remove the debris.

24. The apparatus of claim 23, wherein the debris includes at least one debris constituent selected from the debris constituents consisting of:

soot, unburned hydrocarbons, sulfates, and reductant precipitate.

25. The apparatus of claim 23, wherein the heating element is an electrically resistive device.

26. The apparatus of claim 25, wherein the device includes a wire.

27. The apparatus of claim 23, wherein the optical element includes sapphire.

28. The apparatus of claim 23, wherein the one or more selected constituents include at least one constituent selected from the constituents consisting of:

carbon dioxide, carbon monoxide, an oxide of nitrogen, an oxide of sulfur, and a gaseous alkane.

29. The method of claim 28, wherein the optical window includes sapphire.

30. The method of claim 29, wherein the debris includes at least one debris constituent selected from the debris constituents consisting of:

soot, unburned hydrocarbons, sulfates, and reductant precipitate.

31. The method of claim 29, wherein the one or more selected constituents include at least one constituent selected from the constituents consisting of:

carbon dioxide, carbon monoxide, an oxide of nitrogen, an oxide of sulfur, and a gaseous alkane.

28-1. A method, comprising:

operating an internal combustion engine that includes passage of a working fluid along a pathway therethrough;

during the operating of the engine, sensing one or more wavelengths of electromagnetic radiation to detect one or more selected constituents of the working fluid;

transmitting the one or more wavelengths through an optical window that includes a face exposed to the working fluid;

during the operating of the engine, the face accumulating debris that at least partially occludes transmission of the one or more wavelengths therethrough; and

heating the optical window to at least partially remove the debris.