System, apparatus, and method for measuring an oxygen concentration of a gas
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IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
G01N-027/02
G01R-027/02
출원번호
US-0699182
(2003-11-01)
발명자
/ 주소
Allmendinger, Klaus K.
출원인 / 주소
Innovate! Technology, Inc.
대리인 / 주소
Gavrilovich, Dodd &
인용정보
피인용 횟수 :
3인용 특허 :
2
초록▼
An apparatus, system and method maximizes efficiency and accuracy of measuring an oxygen concentration of a measured gas by varying a flow of oxygen ions within a measuring cell (202) in accordance with an output signal of an oxygen sensor cell (206). The pump current (208) through a pump cell (204)
An apparatus, system and method maximizes efficiency and accuracy of measuring an oxygen concentration of a measured gas by varying a flow of oxygen ions within a measuring cell (202) in accordance with an output signal of an oxygen sensor cell (206). The pump current (208) through a pump cell (204) is switched between a constant positive current and a constant negative current when upper and lower thresholds of the output signal are reached. The pulse width ratio of the square wave produced by the varying current is compared to a pulse width ratio function derived from a calibration procedure to determine the oxygen concentration of the measured gas.
대표청구항▼
1. An apparatus comprising:an oxygen sensor cell for providing an output signal in accordance with an oxygen concentration of a gas within a measuring cell;a pump cell for adjusting an oxygen ion flow between the measuring cell and ambient air in accordance with a pump current flowing through the pu
1. An apparatus comprising:an oxygen sensor cell for providing an output signal in accordance with an oxygen concentration of a gas within a measuring cell;a pump cell for adjusting an oxygen ion flow between the measuring cell and ambient air in accordance with a pump current flowing through the pump cell; anda current managing unit for varying the pump current between a first constant current and a second constant current in accordance with the output signal.2. An apparatus in accordance with claim 1, further comprising:a computing device configured to determine an oxygen concentration of the gas based on a pulse width ratio of a square wave of the pump current.3. An apparatus in accordance with claim 2, wherein the current managing unit is configured to vary the pump current by maintaining the first constant current in a first direction until a first output signal threshold is detected and maintaining the second constant current in a second direction until a second output signal threshold is detected.4. An apparatus in accordance with claim 3, wherein the current managing unit comprises:an analog comparator circuit configured to provide a comparator output signal based on the output of the oxygen sensor cell, the comparator output signal indicating when the first output signal threshold is reached and when the second output signal threshold is reached; andan inverting amplifier circuit connected between the analog comparator circuit and the oxygen sensor cell, the inverting amplifier circuit configured to change the direction of the pump current in response to the comparator output signal.5. An apparatus in accordance with claim 4, wherein the computing device is configured to determine the pulse width ratio by:measuring a first time period corresponding to the first constant current;measuring a second time period corresponding to the second constant current;determining the pulse width ratio based on the first time period and the second time period; anddetermining the oxygen concentration of the gas by comparing the pulse width ratio to a pulse width ratio function for the measuring cell.6. An apparatus in accordance with claim 5, wherein the computing device is connected to the comparator circuit, the computing device configured to measure the first time period and the second time period based on the comparator output signal.7. An apparatus in accordance with claim 6, wherein the computing device is configured to determine at least some values of the pulse width ratio function by determining a pulse width ratio for free air, PWMAIR, when the measuring cell is exposed to free air and the first constant current is a positive pump current and the second constant current is a negative pump current.8. An apparatus in accordance with claim 7, wherein the computing device is further configured to determine at least some of the values of the pulse width ratio function by determining a stoichiometric pulse width ratio, PWMST, based on a pulse width ratio for free air when the first constant current is a positive pump current and the second constant current is zero.9. An apparatus in accordance with claim 8, wherein the computing device establishes the second pump current by opening an analog switch connected between the inverting amplifier circuit and the pump cell in accordance with a negative current cycle.10. An apparatus in accordance with claim 9, wherein the oxygen sensor cell is a Nernst cell.11. An apparatus in accordance with claim 2, wherein the computing device is configured to determine the oxygen concentration based on a frequency of the square wave.12. An apparatus in accordance with claim 11, wherein the computing device is configured to apply a pressure compensation factor based on the frequency to determine the oxygen concentration.13. An apparatus in accordance with claim 2, further comprising:a user interface connected to the computing device.14. An apparatus in accordance with claim 2, wherein the apparatus is configured to connect to a fuel system for a combustion engine.15. An apparatus configured to connect to a measuring cell, the apparatus comprising:a current managing unit configured to receive an output signal based on an oxygen concentration of a gas within the measuring cell and to adjust an oxygen ion flow between the measuring cell and ambient air by varying, in accordance with the output signal, a pump current flowing through a pump cell of the measuring cell between a first constant current and a second constant current.16. An apparatus in accordance with claim 15, wherein the output signal is produced by an oxygen sensor cell of the measuring cell.17. An apparatus in accordance with claim 15, further comprising:a computing device configured to determine an oxygen concentration of the gas based on a pulse width ratio of a square wave of the pump current.18. An apparatus in accordance with claim 17, further comprising:a user interface connected to the computing device.19. An apparatus in accordance with claim 15, wherein the apparatus is configured to connect to a fuel system for a combustion engine.20. An apparatus in accordance with claim 17, wherein the current managing unit is configured to vary the pump current by maintaining the first constant current in a first direction until a first output signal threshold is detected and maintaining the second constant current in a second direction until a second output signal threshold is detected.21. An apparatus in accordance with claim 20, wherein the current managing unit comprises:an analog comparator circuit configured to provide a comparator output signal based on the output of the measuring cell, the comparator output signal indicating when the first output signal threshold is reached and when the second output signal threshold is reached; andan inverting amplifier circuit connected between the analog comparator circuit and the measuring cell, the inverting amplifier circuit configured to change the direction of the pump current in response to the comparator output signal.22. An apparatus in accordance with claim 21, wherein the computing device is configured to determine the pulse width ratio by:measuring a first time period corresponding to the first constant current;measuring a second time period corresponding to the second constant current;determining the pulse width ratio based on the first time period and the second time period; anddetermining the oxygen concentration of the gas by comparing the pulse width ratio to a pulse width ratio function for the measuring cell.23. An apparatus in accordance with claim 22, wherein the computing device is connected to the comparator circuit, the computing device configured to measure the first time period and the second time period based on the comparator output signal.24. An apparatus in accordance with claim 23, wherein the computing device is configured to determine at least some values of the pulse width ratio function by determining a pulse width ratio for free air, PWMAIR, when the measuring cell is exposed to free air and the first constant current is a positive pump current and the second constant current is a negative pump current.25. An apparatus in accordance with claim 24, wherein the computing device is further configured to determine at least some of the values of the pulse width ratio function by determining a stoichiometric pulse width ratio, PWMST, based on a pulse width ratio for free air when the first constant current is a positive pump current and the second constant current is zero.26. An apparatus in accordance with claim 25, wherein the computing device establishes the second pump current by opening an analog switch connected between the inverting amplifier circuit and the pump cell in accordance with a negative current cycle.27. An apparatus in accordance with claim 26, wherein the oxygen sensor cell is a Nernst cell.28. An apparatus in accordance with claim 17, wherein the computing device is configured to determine the oxygen concentration based on a frequency of the square wave.29. An apparatus in accordance with claim 28, wherein the computing device is configured to apply a pressure compensation factor based on the frequency to determine the oxygen concentration.30. An apparatus in accordance with claim 22, wherein the computing device is further configured to perform a calibration procedure by determining at least some factors of the pulse width function.31. An apparatus in accordance with claim 30, wherein the computing device is configured to determine at least some of the factors by determining a corresponding oxygen ion flow for a constant pump current when the measuring cell is exposed to a known gas with a known oxygen concentration.32. An apparatus in accordance with claim 31, wherein the computing device is configured to determine the corresponding oxygen ion flow by determining a relationship between a Lambda coefficient of the oxygen sensor cell and the pulse width ratio.33. An apparatus in accordance with claim 32, wherein the computing device is configured to determine the relationship between the Lambda coefficient of the oxygen sensor cell and the pulse width ratio by determining at least two points on a line representing the relationship between Lambda and the pulse width ratio.34. An apparatus in accordance with claim 33, wherein the computing device is configured to determine at least two points on the line representing the relationship between Lambda and the pulse width ratio by observing a calibration pulse width ratio occurring when the current managing unit directs the pump current in the positive direction until an upper threshold is reached and directs no pump current until a lower threshold is reached.35. An apparatus in accordance with claim 30, wherein the computing device is configured to perform the calibration procedure by determining a positive corresponding oxygen ion flow for a positive constant pump current and determining a negative corresponding oxygen ion flow for the a negative constant pump current when the measuring cell is exposed to a first known gas with a known oxygen concentration.36. An apparatus comprising:a sensor connector configured to connect to a measuring cell and receive an output signal based on an oxygen concentration of a gas within a measuring cell, the output signal produced by an oxygen sensor cell of the measuring cell; anda current managing unit configured to adjust an oxygen ion flow between the measuring cell and ambient air by varying, in accordance with the output signal, a pump current flowing through a pump cell of the measuring cell between a first constant current and a second constant current.37. An apparatus in accordance with claim 36, wherein the current managing unit is configured to vary the pump current by maintaining the first constant current in a first direction until the output signal reaches a first output signal threshold and maintaining the second constant current in a second direction until the output signal reaches a second output signal threshold, the apparatus further comprising:a computing device configured to determine an oxygen concentration of the gas based on a pulse width ratio of a square wave of the pump current resulting from the varying of the pump current.38. An apparatus in accordance with claim 37, wherein the current managing unit comprises:an analog comparator circuit configured to provide a comparator output signal based on the output of the oxygen sensor cell, the comparator output signal indicating when the first output signal threshold is reached and when the second output signal threshold is reached; andan inverting amplifier circuit connected between the analog comparator circuit and the oxygen sensor cell, the inverting amplifier circuit configured to change the direction of the pump current in response to the comparator output signal.39. An apparatus configured to connect to a measuring cell, the apparatus comprising:a current managing unit configured to receive an output signal based on an oxygen concentration of a gas within the measuring cell and to adjust an oxygen ion flow between the measuring cell and ambient air by varying, in accordance with the output signal, a pump current flowing through a pump cell of the measuring cell between a first constant current and a second constant current, the output signal produced by an oxygen sensor cell of the measuring cell; anda computing device configured to determine an oxygen concentration of the gas based on a pulse width ratio of a square wave of the pump current.40. An apparatus in accordance with claim 39, wherein the current managing unit is configured to vary the pump current by maintaining the first constant current in a first direction until a first output signal threshold is detected and maintaining the second constant current in a second direction until a second output signal threshold is detected and wherein the computing device is configured to determine the pulse width ratio by:measuring a first time period corresponding to the first constant current;measuring a second time period corresponding to the second constant current;determining the pulse width ratio based on the first time period and the second time period; anddetermining the oxygen concentration of the gas by comparing the pulse width ratio to a pulse width ratio function for the measuring cell.41. An apparatus configured to connect to a measuring cell and to determine an oxygen concentration of a gas within the measuring cell, the apparatus comprising:a current managing unit configured to vary a pump current flowing through a pump cell of the measuring cell by maintaining a first constant pump current in a first direction until an output signal of an oxygen sensor cell of the measuring cell reaches a first output signal threshold and maintaining a second constant current in a second direction until the output signal reaches a second output signal threshold; anda computing device configured to:measure a first time period corresponding to the first constant pump current;measure a second time period corresponding to the second constant pump current;determine a pulse width ratio of a square wave of the pump current based on the first time period and the second time period; anddetermine the oxygen concentration of the gas by comparing the pulse width ratio to a pulse width ratio function for the measuring cell.
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이 특허에 인용된 특허 (2)
Dekoninck Christophe,FRX ; Delgrange Louis,FRX ; Herbin Luc,FRX ; Neyrat Pierre,FRX ; Aimard Frederic,FRX ; Taupin Jean-Marie,FRX, Device for measuring oxygen content in a gas medium.
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