Device for analyzing exhaust emissions from motor vehicles

• US 6,439,040 B1
• Filed: 02/25/2000
• Issued: 08/27/2002
• Est. Priority Date: 08/25/1997
• Status: Expired due to Fees

• Current Assignee: Wissenschaftliche Werkstatt Fur Umweltmesstechnik GmbH
• Original Assignee: Wissenschaftliche Werkstatt Fur Umweltmesstechnik GmbH
• Inventors: Schroll, Stefan, Garms, Stefan, Palocz-Andresen, Michael
• Primary Examiner(s): DOMBROSKE, GEORGE M
• Application Number:
  US09/486,579
• Time in Patent Office: 914 Days
• Field of Search: 73/233.1, 73/233.2, 731/181, 731/182, 602/76, 602/77
• US Class Current: 73/114.71
• CPC Class Codes: G01M 15/108 using optical methods
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis

Abstract

This description refers to a device for analyzing the most important environmentally relevant substances, such as CO, HC and NO, that are present in vehicle exhaust emissions. It is based on the principle of IR gas absorption. This involves producing measuring signals and a reference signal in a measured optical length (stainless steel tube), with the aid of an infrared source and detector. The production of a ratio then gives a reading and a warning signal is produced whenever a certain limit value is exceeded. The OBM system is made up of modular components, such as a sampling device, exhaust gas processing unit, analyzing device and evaluation unit, which are built into the vehicle. The fluctuating conditions present in the vehicle are compensated for by robust construction and correction of temperature drift by means of production of the first derivation and readjustment of signal strength using an electronically regulated amplification control. Further correction possibilities are: calibration of the zero line using ambient air via a switchover system, and the establishment of a tolerance limit around the noise signals in the detector. The measuring system should in future be installed in all motor vehicles as an extension to using OBD (on board diagnosis) systems. Modification kits are available for older vehicles.

Claims

1. A device to analyze environmentally relevant substances comprising at least one carbon monoxide (CO), hydrocarbons (HC), and nitrogen monoxide (NO) sensor located in a working section, separated from the exhaust gas system, wherein a pump system alternately delivers exhaust gas from the exhaust gas system and clean ambient air from the atmosphere through the working section.

2. The device according to claim 1, wherein the sensor works with the infrared gas absorption.

3. The device according to claim 2, wherein the working section consists of steel and has an optical distance of a minimum of 50 cm.

4. The device according to any one of claims 2 or 3, wherein the sensor has a halogen micro radiator that is surrounded with a transparent piston.

5. The device according to any one of claims 2 or 3, wherein the sensor receives light of a radiation source with a meter flume/reference channel at the same time and makes a quotient from the signals to explore the measurement values.

6. A device to analyze environmentally relevant substances such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen monoxide (NO) in exhaust gas, with at least one sensor located in a working section, separated from the exhaust gas system, wherein a pump system alternately delivers exhaust gas from the exhaust gas system and clean ambient air from the atmosphere through the working section, wherein the pump system comprises an exhaust gas filter, adapted to be regenerated by heating, a solenoid valve and a measuring gas pump.

7. The device according to claim 6, further comprising a reducing regulator, and a flow meter.

8. A device to analyze environmentally relevant substances such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen monoxide (NO) in exhaust gas, with at least one sensor located in a working section, separated from the exhaust gas system, wherein a pump system alternately delivers exhaust gas from the exhaust gas system and clean ambient air from the atmosphere through the working section, wherein divergent signal courses of two infrared sensitive detector cells (reference—

and flow-measuring flume), caused by drifts in temperature, are superposed in measuring periods between zero phases.

9. The device according to claim 8, wherein signal height is adjusted in relation to a reference signal by an electronic adjustable gain control.

10. The device according to claim 9, wherein signal course drifts caused by temperature will be adjusted according to rapid concentration changes in normal vehicle usage by taking a first differential derivation of a concentrated course.

11. The device according to claim 10, wherein adjustment of the delicacy is performed by consideration of natural CO₂-concentration in clean ambient air (340 ppm normal value) or by consideration of a CO₂-part in the exhaust gas (14 Vol. %).

12. The device according to claim 11, wherein the device is placed at an underbody of the vehicle, in a luggage boot, in body of the vehicle or at other suitable places of the vehicle.

13. The device according to claim 12, wherein the device is integrated in the construction of the vehicle comprising a heated tapping place, exhaust gas preparation, analysis device, data line and display unit, whereby the single components are exchangeable by the modular construction and may be installable later.

14. The device according to claim 13, wherein the device is switched on with a seat loading sensor or an ignition lock sensor that measures a cold start from the beginning.

15. The device according to 14, wherein the measuring signal controls combustion procedures in an engine connected to the system and is a catalyst to recognize defects.