Sensor for determining the concentration of sulphur compounds in a liquid

• US 6,716,336 B2
• Filed: 09/17/2001
• Issued: 04/06/2004
• Est. Priority Date: 09/16/2000
• Status: Expired due to Term

• Current Assignee: Caterpillar Incorporated, Mr. Prof. Dr.-Ing. Ralf Moos
• Original Assignee: Daimler Chrysler Company LLC (Stellantis NV)
• Inventors: Moos, Ralf, Stengel, Thomas, Plog, Carsten, Kemmler, Roland, Hürland, Armin, Voigtländer, Dirk
• Primary Examiner(s): TUNG, TA HSUNG
• Application Number:
  US09/953,193
• Publication Number:
  US 20020079236A1
• Time in Patent Office: 932 Days
• Field of Search: 204/421-429, 205/786.5, 205/775
• US Class Current: 205/786.5
• CPC Class Codes: B01D 53/9495 Controlling the catalytic process
• CPC Class Codes: G01N 27/4166 measuring a particular property of an electrolyte
• CPC Class Codes: G01N 33/287 Sulfur content

Abstract

A sensor for determining the concentration of sulphur compounds in a liquid includes: a working electrode in contact with the liquid to be analyzed; a referenced electrode insulated from the liquid to be analyzed; a liquid-impermeable membrane located between the working electrode and the reference electrode and permeable to an ion that may form a chemical compound with the sulphur compounds in the liquid to be analyzed; and a reference material in contact with the reference electrode or forms the reference electrode.

Claims

1. A sensor for determining a concentration of sulphur compounds in a liquid, comprising:

a working electrode in contact with the liquid;

a reference electrode insulated from the liquid;

a liquid-impermeable membrane located between the working electrode and the reference electrode and permeable to an ion that forms a chemical compound with the sulphur compounds in the liquid; and

a reference material that is one of in contact with the reference electrode and arranged to form the reference electrode;

wherein the liquid includes a fuel.

2. The sensor according to claim 1, wherein

the reference material includes an ion that is identical to the ion to which the membrane is permeable; or

the reference material is oxidizable to an ion that is identical to the ion to which the membrane is permeable.

3. The sensor according to claim 2, wherein the reference material includes one of silver and a silver-containing compound.

4. The sensor according to claim 3, wherein the membrane includes a silver ion conductor.

5. The sensor according to claim 4, wherein the silver ion conductor includes at least one of Ag-β

″

-Al₂O₃, Ag-β

-Al₂O₃, AgCl and AgI.

6. The sensor according to claim 2, wherein the reference material includes gold.

7. The sensor according to claim 1, wherein the reference material includes a sulphur-containing material.

8. The sensor according to claim 7, wherein the reference material includes a liquid having a defined sulphur content.

9. The sensor according to claim 1, wherein the sensor is configured for measurement according to one of a potentiometric principle and an amperometric principle.

10. The sensor according to claim 1, wherein the sensor is coated with an insulating material so that only the working electrode is in contact with the liquid.

11. The sensor according to claim 1, further comprising a third electrode connected via a voltage source to the working electrode and located on the membrane.

12. The sensor according to claim 1, wherein the fuel includes at least one of petrol, diesel fuel, fuel oil, liquified gas, methanol and ethanol.

13. The sensor according to claim 1, further comprising:

a temperature sensor to sense a temperature of the liquid.

14. The sensor according to claim 13, wherein the temperature sensor includes one of a thermocouple, a resistance thermometer, and a semiconductor temperature sensor.

15. The sensor according to claim 1, further comprising:

a heating arrangement to regulate a temperature of the sensor.

16. An apparatus for determining a degree of loading of sulphur adsorber installed in a fuel line, comprising:

a first sensor arranged before the adsorber; and

a second sensor arranged after the adsorber;

wherein each of the first sensor and the second sensor is configured to determine a concentration of sulphur compounds in a liquid, each of the first sensor and the second sensor including;

a working electrode in contact with the liquid;

a reference electrode insulated from the liquid;

a liquid-impermeable membrane located between the working electrode and the reference electrode and permeable to an ion that forms a chemical compound with the sulphur compounds in the liquid; and

a reference material that is one of in contact with the reference electrode and arranged to form the reference electrode; and

wherein the apparatus is configured to determine the degree of loading of the sulphur adsorber in accordance with a comparison of output signals of the first sensor and the second sensor.

17. The apparatus according to claim 16, wherein the reference electrode of the second sensor is in contact with untreated fuel before the adsorber.

18. An apparatus for determining a degree of loading of a sulphur adsorber installed in a fuel line, comprising:

a sensor configured to determine a concentration of sulphur compounds in a liquid, the sensor including;

a working electrode in contact with the liquid;

a reference electrode insulated from the liquid;

a liquid-impermeable membrane located between the working electrode and the reference electrode and permeable to an ion that forms a chemical compound with the sulphur compounds in the liquid; and

a reference material that is one of in contact with the reference electrode and arranged to form the reference electrode;

wherein the working electrode is in contact with the fuel before the adsorber and the reference electrode is in contact with the fuel after the adsorber.

19. A method for determining the degree of sulphur loading of an Nox trap arranged in an exhaust gas purification system of a 4-stroke engine that is run lean, comprising the step of providing a sensor configured to determine a concentration of sulphur compounds in a liquid, the sensor including:

a working electrode in contact with the liquid;

a reference electrode insulated from the liquid;

a liquid-impermeable membrane located between the working electrode and the reference electrode and permeable to an ion that forms a chemical compound with the sulphur compounds in the liquid; and

a reference material that is one of in contact with the reference electrode and arranged to form the reference electrode;

wherein the liquid includes a fuel.