Method for quickly rendering a MOS gas sensor operational, MOS gas sensor system, and fuel cell system

• US 6,467,334 B2
• Filed: 05/11/2001
• Issued: 10/22/2002
• Est. Priority Date: 05/17/2000
• Status: Expired due to Term

• Current Assignee: Emergent Power Inc. (Plug Power Inc.)
• Original Assignee: Avista Laboratories Inc. (Plug Power Inc.)
• Inventors: Fuglevand, William A., Lloyd, Greg A.
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US09/854,056
• Publication Number:
  US 20010045118A1
• Time in Patent Office: 529 Days
• Field of Search: 73/310.6
• US Class Current: 73/31.06
• CPC Class Codes: H01M 8/0247 characterised by the form characterised by a channel configuration H01M8/0258
• CPC Class Codes: H01M 8/0258 characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
• CPC Class Codes: H01M 8/04007 related to heat exchange
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• CPC Class Codes: H01M 8/1004 characterised by membrane-electrode assemblies [MEA] H01M8/12 takes precedence
• CPC Class Codes: H01M 8/247 Arrangements for tightening a stack, for accommodation of a stack in a tank or for assembling different tanks
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y10S 429/90 Fuel cell including means for power conditioning, e.g. Conversion to ac

Abstract

A method of speeding startup of a MOS gas sensor having a sensor element for sensing a target gas, and a heater configured to heat the sensor element, and which is responsive to a voltage applied thereto. The heater has an operating temperature which is selectively maintained by applying a first voltage thereto, and the heater further has a maximum recommended temperature which is selectively maintained by applying a second voltage thereto. The maximum recommended temperature is higher than the operating temperature, and the second voltage is higher than the first voltage. The method includes providing a third voltage to the heater which is greater than the second voltage for a predetermined amount of time which is selected to increase the temperature to a level not greater than the maximum recommended temperature in a shorter time period than if the second voltage is applied and maintained. A MOS gas sensor system and a fuel cell system also employ such a method.

Claims

1. A method for quickly rendering a MOS gas sensor operational and which has a sensor element for sensing a target gas, and a heater configured to heat the sensor element when a voltage is applied thereto, the heater having an operating temperature which is selectively maintained by applying a first voltage thereto, and wherein the heater has a maximum recommended temperature which is selectively maintained by applying a second voltage thereto, the maximum recommended temperature being higher than the operating temperature, and the second voltage being higher than the first voltage, the method comprising:

providing a third voltage to the heater, which is greater than the second voltage for a predetermined amount of time which is selected to increase the temperature to, but not above, the maximum recommended temperature in a shorter time period than if the second voltage is applied and maintained;

causing the heater to cool in a shorter time period than if the first voltage is applied; and

providing the first voltage after causing the heater to cool.

2. A method for quickly rendering a MOS gas sensor operational in accordance with claim 1, wherein causing the heater to cool further comprises reducing the voltage provided to the heater from the third voltage, to a fourth voltage which is less than the first voltage.

3. A method for quickly rendering a MOS gas sensor operational in accordance with claim 2, wherein reducing the voltage comprises cutting off the voltage provided to the heater.

4. A method for quickly rendering a MOS gas sensor operational in accordance with claim 3, wherein the first voltage is provided to the heater after cutting off the voltage provided to the heater.

5. A method for quickly rendering a MOS gas sensor operational in accordance with claim 4 wherein the MOS gas sensor senses a target gas comprising hydrogen.

6. A method for quickly rendering a MOS gas sensor operational and which has a sensor element for sensing a target gas, and a heater configured to heat the sensor element and which is responsive to a voltage applied thereto, and wherein the heater has an operating temperature which is selectively maintained by applying a first voltage thereto, and the heater further has a maximum recommended temperature which is selectively maintained by applying a second voltage thereto, and wherein the maximum recommended temperature is higher than the operating temperature, and the second voltage is higher than the first voltage, the method comprising:

providing a third voltage to the heater which is greater than the second voltage, and which increases the temperature toward the maximum recommended temperature in a shorter time period than if the second voltage is applied and maintained;

reducing the voltage provided to the heater from the third voltage, to a fourth voltage which is less than the first voltage to reduce the temperature of the heater in a shorter time period than if the first voltage is applied and maintained; and

providing the first voltage to the heater after reducing the voltage to the fourth voltage.

7. A method for quickly rendering a MOS gas sensor operational in accordance with claim 6, wherein the third voltage is provided for a predetermined amount of time.

8. A method for quickly rendering a MOS gas sensor operational in accordance with claim 6, wherein the third voltage is provided for a predetermined amount of time which is not greater than the time required to reach the maximum recommended temperature.

9. A method for quickly rendering a MOS gas sensor operational in accordance with claim 6, wherein the third voltage is provided for an amount of time which causes the heater to reach but not exceed the maximum recommended temperature.

10. A method for quickly rendering a MOS gas sensor operational in accordance with claim 6, wherein reducing the voltage comprises reducing the voltage for a predetermined amount of time.

11. A method for quickly rendering a MOS gas sensor operational in accordance with claim 6, wherein reducing the voltage comprises providing no voltage to the heater.

12. A method for quickly rendering a MOS gas sensor operational in accordance with claim 6, wherein reducing the voltage comprises reducing the voltage applied to the heater for an amount of time selected to bring the temperature of the heater down to the operating temperature.

13. A method for quickly rendering a MOS gas sensor operational in accordance with claim 6, wherein the gas sensor senses a target gas comprising hydrogen.

14. A method for quickly rendering a MOS hydrogen gas sensor operational, and which has a sensor element for sensing hydrogen gas, and a heater configured to heat the hydrogen gas in response to a voltage applied thereto, the heater having a pre-use temperature, an operating temperature which is selectively maintained by applying a first voltage thereto, and a maximum recommended temperature which is selectively maintained by applying a second voltage thereto, and wherein the maximum recommended temperature is higher than the operating temperature, and the second voltage is higher than the first voltage, the method comprising:

providing a voltage to the heater which is greater than the second voltage for a predetermined amount of time to increase the temperature of the heater from the pre-use temperature toward the maximum recommended temperature in a shorter time period than if the second voltage was applied;

reducing the voltage provided to the heater to a voltage less than the first voltage for a predetermined amount of time to reduce the temperature of the heater in a shorter period of time than if the first voltage was applied; and

providing the first voltage to the heater.

15. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 14, wherein the voltage which is greater than the second voltage is provided for an amount of time selected such that the heater reaches the maximum recommended temperature from the pre-use temperature in an amount of time less than half of the time required if the second voltage is applied and maintained.

16. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 14, wherein the voltage which is greater than the second voltage is provided for a predetermined amount of time selected such that the heater reaches, but does not exceed, the maximum recommended temperature.

17. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 14, wherein the voltage which is greater than the second voltage is provided for a predetermined amount of time which is not greater than the time period required to reach the maximum recommended temperature.

18. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 14, wherein reducing the voltage comprises reducing the voltage for a predetermined amount of time.

19. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 14, wherein reducing the voltage comprises providing no voltage to the heater.

20. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 14, wherein reducing the voltage comprises cutting the voltage applied to the heater for an amount of time selected to bring the temperature of the heater down to the operating temperature.

21. A method for quickly rendering a MOS hydrogen gas sensor operational and which has a sensor element for sensing a target gas, and a heater configured to heat the sensor element, and which is responsive to a voltage applied thereto, the heater having a pre-use temperature, and an operating temperature which is selectively maintained by applying a first voltage thereto, the heater further having a maximum recommended temperature which is selectively maintained by applying a second voltage thereto, the maximum recommended temperature being higher than the operating temperature, and the second voltage being higher than the first voltage, the method comprising:

providing a third voltage to the heater which is greater than the second voltage, for a first predetermined period of time, the first predetermined period of time being selected based upon the value of the third voltage, and the amount of time necessary at the third voltage value to increase the temperature of the heater from the pre-use temperature to the maximum recommended temperature;

eliminating the application of voltage to the heater for a second predetermined period of time, the second predetermined period of time being selected based upon the amount of time required to reduce the temperature of the heater from the maximum recommended temperature to the operating temperature when no voltage is applied to the heater;

after eliminating the application of voltage to the heater, providing the first voltage to the heater; and

using the sensor, after providing the first voltage to the heater.

22. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 21, wherein the third voltage is provided for an amount of time which is selected such that the heater reaches the maximum recommended temperature from the pre-use temperature in an amount of time less than half of the time required if the second voltage is applied and maintained.

23. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 21, wherein the third voltage is provided for a predetermined amount of time which causes the heater to reach, but not exceed, the maximum recommended temperature.

24. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 21, wherein the third voltage is provided for a predetermined amount of time which is not greater than the time required to reach the maximum recommended temperature.

25. A method of speeding startup of a MOS hydrogen gas sensor in accordance with claim 21 wherein the third voltage is between 5 and 7.5 volts.

26. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 21, wherein the third voltage value is about 7.5 volts.

27. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 26, wherein the first predetermined period of time is less than about 60 seconds.

28. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 26, wherein the first predetermined period of time is less than about 30 seconds.

29. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 26, wherein the first predetermined period of time is less than about 15 seconds.

30. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 26, wherein the first predetermined amount of time is about 10 seconds.

31. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 30, wherein the second predetermined period of time is between about 1.4 to about 3.4 seconds.

32. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 30, wherein the second predetermined period of time is between about 1.9 to about 2.9 seconds.

33. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 30, wherein the second predetermined period of time is about 2.4 seconds.

34. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 21, wherein the sensor is rendered operational in less than about 30 seconds.

35. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 30, wherein the sensor is rendered operational in less than about 15 seconds.

36. A method for quickly rendering a MOS hydrogen gas sensor operational in accordance with claim 21, wherein the sensor is rendered operational in about 12.4 seconds.

37. A method for quickly rendering a MOS hydrogen gas sensor operational, and which has a sensor element for sensing a target gas, and a heater configured to heat the sensor element following the application of a voltage thereto, and wherein the heater has a pre-use temperature;

and an operating temperature of about 500 degrees Celsius which is selectively maintained by applying a voltage of about 5.0 Volts thereto, and wherein the heater further has a maximum recommended temperature of about 600 degrees Celsius which is selectively maintained by applying a voltage of about 6.0 Volts thereto, the method comprising;

providing a voltage of about 7.5 Volts to the heater for about 10 seconds;

eliminating the application of the voltage to the heater for about 2.4 seconds after first providing the voltage of about 7.5 Volts; and

providing about 5.0 Volts to the heater after eliminating the application of the voltage.

38. A method for quickly rendering a MOS gas sensor operational, and which has a sensor element for sensing a target gas, and a heater configured to heat the sensor element following the application of a voltage thereto, the heater having a pre-use temperature;

and an operating temperature of about 500 degrees Celsius which is selectively maintained by applying a voltage of 5.0 Volts thereto, and wherein the heater has a maximum recommended temperature of about 600 degrees Celsius which is selectively maintained by applying a voltage of 6.0 Volts thereto, the method comprising;

providing a voltage of 7.5 Volts to the heater for about 10 seconds;

eliminating the voltage to the heater for about 2.4 seconds after providing the voltage of 7.5 Volts; and

providing 5.0 Volts to the heater after eliminating the voltage.

39. A MOS gas sensor system comprising:

a MOS gas sensor having a sensor element for sensing a target gas, and a heater configured to heat the sensor element and which is responsive when a voltage is applied thereto, and wherein the heater has an operating temperature which is selectively maintained by applying a first voltage thereto, and the heater further has a maximum recommended temperature which is selectively maintained by applying a second voltage thereto, and wherein the maximum recommended temperature is higher than the operating temperature, and the second voltage is higher than the first voltage; and

circuitry configured to provide a third voltage to the heater which is greater than the second voltage for a predetermined amount of time which is selected to increase the temperature to a level which is not above the maximum recommended temperature in a time period which is less than if the second voltage is applied and maintained, the circuitry being further configured to, after providing the third voltage, reduce the voltage provided to the heater from the third voltage, to a fourth voltage, which is less than the first voltage and to further reduce the temperature of the heater in a shorter time period than if the first voltage is applied and maintained.

40. A MOS gas sensor system in accordance with claim 39 wherein the fourth voltage is zero.

41. A MOS gas sensor system in accordance with claim 40 wherein the circuitry is further configured to provide the first voltage to the heater for a predetermined amount of time after the fourth voltage is provided to the heater.

42. A MOS gas sensor system in accordance with claim 40 wherein the circuitry is further configured to maintain provision of the first voltage to the heater for a predetermined amount of time, after the fourth voltage is provided to the heater.

43. A fuel cell system comprising:

a housing, the housing having a fuel gas inlet and an exhaust outlet;

at least one ion exchange fuel cell membrane within the housing;

a MOS gas sensor including a sensor element for sensing a target gas and a heater configured to heat the sensor element and which is energized when a voltage is applied thereto, and wherein the heater has an operating temperature which is selectively maintained by applying a first voltage thereto, and the heater further has a maximum recommended temperature which is selectively maintained by applying a second voltage thereto, the maximum recommended temperature being higher than the operating temperature, and wherein the second voltage is higher than the first voltage; and

a controller coupled in controlling relation relative to the ion exchange fuel cell membrane and to the MOS gas sensor and which provides a third voltage to the heater, which is greater than the second voltage for a predetermined amount of time which is selected to increase the temperature to a level to, but not greater than, the maximum recommended temperature in a shorter time period than if the second voltage is applied and maintained.

45. A fuel cell system in accordance with claim 43, wherein the fuel supply comprises hydrogen gas, and wherein the MOS sensor of the MOS gas sensor system is configured to sense the concentration of hydrogen gas.

44. A fuel cell system in accordance with claim 44, and further comprising a fuel supply coupled to the fuel supply inlet of the housing.