METHOD FOR CAPTURING MEASUREMENT VALUES AND DISPLAYING MEASUREMENT VALUES

• US 20110165692A1
• Filed: 09/03/2008
• Published: 07/07/2011
• Est. Priority Date: 09/03/2008
• Status: Active Grant

• Current Assignee: Testo AG
• Original Assignee: Testo AG
• Inventors: Munch, Reinhold, Kaufmann, Andreas, Springmann, Thomas, Hoyer, Knut
• Granted Patent: US 8,852,950 B2
• Time in Patent Office: Days
• US Class Current: 436/116
• CPC Class Codes: G01N 33/0037 for NOx
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y10T 436/177692 Oxides of nitrogen
• CPC Class Codes: Y10T 436/178459 Only nitrogen dioxide
• CPC Class Codes: Y10T 436/179228 Both nitrogen oxide and dioxide
• CPC Class Codes: Y10T 436/207497 Molecular oxygen

Abstract

A method for determining an NO_x concentration in a measurement gas is provided, where a measurement value for the NO_x concentration is determined from the sensor signal of a gas sensor and a measurement value for the concentration of a second component in the measurement gas is determined. A corrected value for the NO_x in the measurement gas is determined from the measurement values, and the measurement value and the corrected measurement value for the NO_x concentration are displayed and/or output.

Claims

1. Method for determining a NO_x concentration in a measurement gas, comprising providing a sensor signal from a first gas sensor that is sensitive for NO_x and that is brought into contact with the measurement gas and determining a measurement value for the NO_x concentration from the sensor signal, determining a measurement value for a concentration of a second component in the measurement gas and a determining numerical value for the NO_x concentration in the measurement gas from the measurement value for the concentration of the second component in the measurement gas.

2. Method according to claim 1, wherein the second component is oxygen or an oxygen compound.

3. Method according to claim 1, further comprising displaying the measurement value and the numerical value for the NO_x concentration in the measurement gas.

4. Method according to claim 1, further comprising removing the measurement gas from exhaust gases of a combustion engine.

5. Method according to claim 1, wherein a second gas sensor is provided for determining the concentration of the other component in the measurement gas.

6. Method according to claim 5, wherein the measurement value for the NO_x concentration in the measurement gas is determined with reference to a stored first characteristic line (19, 20, 21) from the sensor signal of the first gas sensor.

7. Method according to claim 6, wherein the numerical value for the NO_x concentration in the measurement gas is determined with reference to a stored second characteristic line from the sensor signal of at least one of the first or the second gas sensor.

8. Method according to claim 7, wherein at least one of the first characteristic line (19, 20, 21) or the second characteristic line is formed by interpolation or extrapolation of calibration or support points each of a characteristic line curve.

9. Method according to claim 7, wherein at least one of the first characteristic line (19, 20, 21) or the second characteristic line is stored as a data series.

10. Method according to claim 7, wherein the first characteristic line (19, 20, 21) is the characteristic line of an infrared sensor, UV sensor, electrochemical sensor, or semiconductor sensor or a chemiluminescence detector.

11. Method according to claim 7, wherein the second characteristic line maps deviations of the characteristic line of a NO_x sensitive electrochemical sensor, infrared sensor, UV sensor, or semiconductor sensor or a chemiluminescence detector from the first characteristic line for different values of a concentration of the other component in the measurement gas.

12. Method according to claim 1, further comprising separately signaling at least one of exceeding or falling below limit values for the measurement value and numerical value for the NO_x concentration in the measurement gas.

13. Method according to claim 1, wherein the difference between the measurement value and numerical value for the NO_x concentration in the measurement gas increases or decreases with increasing concentration of the second component in the measurement gas.

14. Method according to claim 1, wherein at least one additional measurement or characteristic value for a concentration of another component in the measurement gas is at least one of determined or input and a correction value for the NO_x concentration in the measurement gas is determined from at least one of the additional measurement or characteristic value.

15. Method according to claim 14, wherein the determination of the numerical value for the NO_x concentration in the measurement gas is carried out from the measurement value for the concentration of at least one of the second component or the other component as a function of a moisture content of the measurement gas.

16. Method according to claim 1, wherein the measurement gas is an exhaust gas of a combustion engine and for chemical substances, fed to the combustion engine, a concentration of elementary components, including at least one of H or C, or a moisture content of air fed to the combustion engine are determined by an elementary analysis or the moisture content of the measurement gas is calculated, especially from determined concentrations of the elementary components or a moisture content of air fed to the combustion engine.

17. Method according to claim 16, wherein the moisture content in the measurement gas is captured.

18. Device for determining a NO_x concentration in a measurement gas, comprising a first gas sensor that is sensitive to NO_x and can be brought into contact with the measurement gas and an evaluation unit (8) for determining a measurement value for the NO_x concentration in the measurement gas (3) from a sensor signal from the gas sensor, a second gas sensor is provided that is constructed for determining a concentration of a second component in the measurement gas (3) and the evaluation unit (8) a numerical value for the NO_x concentration in the measurement gas (3) from the measurement value determined with the first gas sensor for the NO_x concentration in the measurement gas and from the sensor signal of the second gas sensor.

19. Device according to claim 18, wherein a storage device are provided in which a first characteristic line (19, 20, 21) for evaluation of the sensor signal of the first gas sensor and a second characteristic line for evaluation of a second sensor signal are stored, and the evaluation unit determines a difference value or factor by which a numerical value deviates from the measurement value for the NO_x concentration in the measurement gas using the second characteristic line.

20. Device according to claim 18, further comprising an input device for at least one of input (11) or determination of a concentration of another component in the measurement gas and for different numerical values of the concentration of the other component, different characteristic lines (19, 20, 21) are stored from which a difference value or factor can be taken by which the numerical value deviates from the measurement value for the NO_x concentration in the measurement gas.

21. Device according to claim 18, further comprising a gas cooler or a condensate trap is arranged in the gas flow of the measurement gas.

22. Device according to claim 21, further comprising an identification device that at least one of identifies a presence of the gas cooler or the condensate trap in the gas flow of the measurement gas, allows identification or input of an operating temperature of the gas cooler or the condensate trap, or determines the moisture content in the measurement gas, especially before entry into a gas cooler, are provided.

23. Device according to claim 18, wherein the second gas sensor is an O₂ sensor.

24. Device according to claim 18, wherein the device (2) has a portable construction.