Method and a measuring system for determining and monitoring exhaust gas emissions from a vehicle

• US 20040104345A1
• Filed: 10/09/2003
• Published: 06/03/2004
• Est. Priority Date: 04/09/2001
• Status: Active Grant

• Current Assignee: Valtion Teknillinen Tutkimuskeskus
• Original Assignee: Valtion Teknillinen Tutkimuskeskus
• Inventors: Niemela, Pentti, Kansakoski, Markku
• Granted Patent: US 7,049,595 B2
• Time in Patent Office: Days
• US Class Current: 250/338.5
• CPC Class Codes: G01N 2021/1795 Atmospheric mapping of gases
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis

Abstract

The invention relates to a method and a measuring system for determining exhaust gas emissions from a moving vehicle (20) by a remote optical measuring technique. According to the invention, the model and/or type of the vehicle (20) under examination is identified, and the driving situation of the vehicle (20) in question is determined at the moment of measurement. A calculatory vehicle model (211, 212) is used to determine a case-specific estimate for the carbon dioxide concentration (CO2) of the exhaust gas plume (40) depending on the vehicle in question and its driving situation. Invention improves the accuracy of determining the concentrations of the actual emission gases (NO, HC, CO) by eliminating the inaccuracy of the carbon dioxide concentration (CO2) values.

Claims

1. A method for determining and monitoring exhaust gas emissions of a moving vehicle (20) or a corresponding object by a remote measuring technique, which method comprises the steps of

forming a measuring beam (50) of infrared radiation, which measuring beam (50) is directed once or several times through an exhaust gas plume (40) emitted by the vehicle (20),

determining, by means of the measuring beam (50), an optical measuring value, such as transmission, for carbon dioxide (CO₂), said measuring value indicating the optical absorption caused by carbon dioxide (CO₂) contained in the exhaust gas plume (40) in the measuring beam (50),

determining, by means of the measuring beam (50), an optical measuring value, such as transmission, for one or more actual emission gases (NO, CO, HC) each, said measuring value indicating the absorption caused by said emission gas (NO, HC, CO) contained in the exhaust gas plume (40) in the measuring beam (50),

proportioning the optical measuring values determined for the actual emission gases (NO, HC, CO) each with the optical measuring value determined for carbon dioxide (CO₂), and

solving, by means of an estimate determined for the carbon dioxide concentration (CO₂) of the exhaust gas plume (40), the concentrations of the actual emission gases (NO, HC, CO) in the exhaust gas plume (40) by means of said optical measuring values,

characterized in that for the more precise determination of the actual emission gases (NO, HC, CO) in the exhaust gas plume (40), the method also comprises the steps of

identifying the model and/or type of the vehicle (20) under examination,

determining the driving situation of said vehicle (20) at the moment of measurement, and further

forming a calculatory vehicle model (211, 212) for determining a case-specific estimate for the carbon dioxide concentration (CO₂) of the exhaust gas plume (40) depending on the vehicle in question and its driving situation.

2. The method according to claim 1, characterized in that the optical measuring value, such as transmission, determined for carbon dioxide (CO₂) and the case-specific concentration estimate determined for carbon dioxide (CO₂) by means of the calculatory vehicle model (211, 212) are used to determine the effective absorption length of the measuring beam (50) in the exhaust gas plume (40), which is further used to determine the concentrations of the actual emission gases (NO, HC, CO).

3. The method according to claim 1 or 2, characterized in that said optical measuring values are determined for all the measured gases (NO, CO, HC, CO₂) substantially at the same time and at the same point in the exhaust gas plume (40).

4. The method according to any of the preceding claims, characterized in that the vehicle (20) is identified on the basis of the registration plate of the vehicle.

5. The method according to claim 4, characterized in that the data contained in the registration plate of the vehicle (20) are used to retrieve the exact type and/or model data of the vehicle (20) from a register database.

6. The method according to claim 5, characterized in that the type and/or model data of the vehicle (20) are used to retrieve more detailed information about the vehicle model in question, such as dead weight, engine type, and properties of the transmission apparatus.

7. The method according to any of the preceding claims, characterized in that to determine the driving situation at the moment of measuring the vehicle (20), the speed and/or acceleration of the vehicle (20) are determined.

8. The method according to claim 7, characterized in that the total weight of the vehicle (20) and/or the weather conditions at the measurement site and time, and/or the profile of the surface of the road (10) in the driving direction at the measurement site, and/or the roughness of the surface of the road (10) prevailing at the measurement site and time are also measured to determine the driving situation at the moment of the measurement of the vehicle (20).

9. The method according to any of the preceding claims, characterized in that the optical measuring value for nitrogen oxide (NO) is determined in the infrared range in the vicinity of the wavelength of 5.26 μ

m by using, for wavelength filtering or as part of the wavelength filtering in reference and/or measuring channels (702, 703;

802, 803) intended for NO, a filtering means (701;

800, 801) whose transmission as a function of the wavelength correlates with the comb-like structure of the spectral lines of the absorption spectrum present in the vicinity of 5.25 μ

m of nitrogen oxide (NO).

10. The method according to claim 9, characterized in that in each of the reference and measuring channels (802, 803) intended for NO, Fabry-Perot comb filters (800, 801) are used for the wavelength filtering or as part of the wavelength filtering.

11. The method according to claim 9, characterized in that in the measuring channel intended for NO, a scanning Fabry-Perot comb filter is used for the wavelength filtering or as part of the wavelength filtering.

12. The method according to claim 9, characterized in that in the reference channel (702) intended for NO, an NO gas cell cell filter (701) is used for the wavelength filtering or as part of the wavelength filtering, and, if necessary, a corresponding so-called dummy filter is used in the measuring channel (703), to balance the optical properties of said channels (701, 702).

13. The method according to any of the preceding claims, characterized in that a calculatory vehicle model (211, 216) is used to determine an estimate for the fuel consumption of the vehicle (20) at the moment of measuring, which is used to convert the measured emission values (NO, CO, HC, CO₂) to emission coefficients in the form of g/km and/or g/s and/or g/kWh.

14. The method according to any of the preceding claims, characterized in that measurements are made for benzene and/or 1,3-butadiene and/or N₂O.

15. A measuring system for determining and monitoring exhaust gas emissions (NO, CO, HC, CO₂) from a moving vehicle (20) or a corresponding object by a remote technique, which system comprises

means (60, 70) for forming a measuring beam (50) of infrared radiation and for directing the measuring beam (50) once or several times through an exhaust gas plume (40) emitted by the vehicle (20),

means (60, 30) for determining, by means of the measuring beam (50), an optical measuring value, such as transmission, for carbon dioxide (CO₂), said measuring value indicating the optical absorption caused by carbon dioxide (CO₂) contained in the exhaust gas plume (40) in the measuring beam (50),

means (60, 30) for determining, by means of the measuring beam (50), an optical measuring value, such as transmission, for one or more actual emission gases (NO, CO, HC) each, said measuring value indicating the absorption caused by said emission gas (NO, HC, CO) contained in the exhaust gas plume (40) in the measuring beam (50),

means (60, 30) for proportioning the optical measuring values determined for the actual emission gases (NO, HC, CO) to the optical measuring value determined for carbon dioxide (CO₂), and

means (60, 30) for solving the concentrations of the actual emission gases (NO, HC, CO) of the exhaust gas plume (40) on the basis of the estimate determined for the carbon dioxide concentration (CO₂) of the exhaust gas plume (40) and said optical measuring values,

characterized in that for the more precise determination of the actual emission gases (NO, HC, CO) in the exhaust gas plume (40), the measuring system also comprises at least

means (30, 110, 130, 140) for identifying the model and/or type of the vehicle (20) under examination,

means (30, 80, 81, 90, 100, 120) for determining the driving situation of the vehicle (20) at the moment of measuring, and further

means (30) for forming a calculatory vehicle model (211, 212) for determining a case-specific estimate for the carbon dioxide concentration (CO₂) of the exhaust gas plume (40) depending on the vehicle (20) in question and its driving situation.

16. The measuring system according to claim 15, characterized in that the measuring system comprises means (213) for determining the effective absorption length of the measuring beam (50) in the exhaust gas plume (40) by using an optical measuring value, such as transmission, determined for carbon dioxide (CO₂) and a case-specific concentration estimate determined for carbon dioxide (CO₂) on the basis of a calculatory vehicle model (211, 212), as well as means (214) for determining the concentrations of the actual emission gases (NO, HC, CO) by means of said effective absorption length.

17. The measuring system according to claim 15 or 16, characterized in that the measuring system comprises means (30, 60, 70) for determining said optical measuring values for all the measured gases (NO, CO, HC, CO₂) substantially at the same time and at the same point in the exhaust gas plume (40).

18. The measuring system according to any of the preceding claims 15 to 17, characterized in that the measuring system comprises means (30, 110, 130, 140) for identifying the vehicle (20) on the basis of the registration plate of the vehicle.

19. The measuring system according to claim 18, characterized in that the measuring system comprises means (30, 130, 140) for retrieving the exact type and/or model data of the vehicle (20) from a register database by means of the data contained in the registration plate of the vehicle (30,130,140).

20. The measuring system according to claim 19, characterized in that the measuring system comprises means (30, 130, 140) for retrieving more detailed information about the vehicle model in question, such as dead weight, engine type, and properties of the transmission apparatus by means of said type and/or model data of the vehicle from a separate type database.

21. The measuring system according to any of the preceding claims 15 to 20, characterized in that the measuring system comprises means (30, 80, 81) for determining the speed and/or acceleration of the vehicle (20) in the driving situation at the moment of measuring.

22. The method according to claim 21, characterized in that the measuring system also comprises means (30, 90, 100, 120) for measuring the total weight of the vehicle (20) and/or the weather conditions at the measurement site and time, and/or the profile of the surface of the road (10) in the driving direction at the measurement site, and/or the roughness of the surface of the road (10) prevailing at the measurement site and time.

23. The measuring system according to any of the preceding claims 15 to 22, characterized in that the measuring system comprises means (60) for determining the optical measuring value for nitrogen oxide (NO) at the infrared range in the vicinity of the wavelength of 5.26 μ

m in such a way that, for wavelength filtering or as part of the wavelength filtering in reference and/or measuring channels (702, 703;

802, 803) intended for NO, a filtering means (701;

800, 801) is used, whose transmission as a function of the wavelength correlates with the comblike structure of the spectral lines of the absorption spectrum present in the vicinity of 5.25 μ

m of nitrogen oxide (NO).

24. The measuring system according to claim 23, characterized in that the measuring system comprises, in each of the reference and measuring channels (802, 803) intended for NO, a Fabry-Perot comb filter (800, 801) with substantially fixed tuning for the wavelength filtering or as part of the wavelength filtering.

25. The measuring system according to claim 23, characterized in that the measuring system comprises, in the measuring channel intended for NO, a scanning Fabry-Perot comb filter for the wavelength filtering or as part of the wavelength filtering.

26. The measuring system according to claim 23, characterized in that the measuring system comprises, in the reference channel (702) intended for NO, an NO gas cell filter (701) for the wavelength filtering or as part of the wavelength filtering, and, if necessary, a corresponding so-called dummy filter in the measuring channel (703), to balance the optical properties of said channels (701, 702).

27. The measuring system according to any of the preceding claims 15 to 26, characterized in that the measuring system comprises means (30) for determining, by means of a calculatory vehicle model (211, 216), an estimate for the fuel consumption of the vehicle (20) under examination at the moment of measuring, and means (30) for indicating the measured emission values (NO, CO, HC, CO₂) as emission coefficients in the form of g/km and/or g/s and/or g/kWh by means of said estimate for the fuel consumption.

28. The measuring system according to any of the preceding claims 15 to 27, characterized in that the measuring system comprises means (30) for setting up a data transmission connection and for data transmission between the measuring system and one or more external systems (130, 140).

29. The method according to any of the preceding claims 15 to 28, characterized in that the measuring system also comprises means (30, 60, 70) for taking measurements for benzene and/or 1,3-butadiene and/or N₂O.