Envirotest Systems Corporation

Colorado Seminary

Environmental Systems Products Holdings Inc.

Dennis L Smith

James Johnson

Kenneth W Michaels

Donald Hugh Stedman

Jason K Webster

John D Didomenico

Peter S Shifflett

John DiDomenico

A method and apparatus for measuring particulates in vehicle emissions. An ultraviolet light beam having a predetermined wavelength, and an infrared light beam having a predetermined wavelength are propagated through the exhaust plume of a vehicle that has passed on the road. The reduction in intensities of the light beams are measured. The reduction in intensity of the ultraviolet light is due to scattering of the light by particles in the exhaust. A portion of the reduction in intensity of the infrared light is due to absorption of the light by carbon dioxide in the exhaust and a portion of the reduction in intensity is due to the scattering of light by the particles in the exhaust. To distinguish between the two, a portion of the infrared light is run through a test cell with a known amount of carbon dioxide. The reduction in intensity is measured and compared with the reduction in intensity of the infrared light passing through the exhaust plume. As one measure of particulate content, the ratio of the particles in the exhaust whose diameter is greater than said predetermined wavelength of ultraviolet light to the density of the carbon dioxide in the exhaust plume is calculated. Another measure of particulate content is the ratio of the particles in the exhaust whose diameter is greater than said predetermined wavelength of infrared light to the density of the carbon dioxide in the exhaust plume. The average size of the particles is calculated from the ratio of the particles whose diameter is greater than the predetermined wavelength of ultraviolet light to the particles whose diameter is greater that the predetermined wavelength of infrared light is calculated. The average particle size is determined from the Mie efficiency using Mie scattering and absorption theory.

Method and apparatus for measuring particulates in vehicle emissions

A mechanical optical system scans a light beam that has passed through an automobile exhaust plume onto a plurality of detectors by using fiber optic tubes in an array that is mounted close to a rotating mirror. First ends of the fiber optic tubes are in an array adjacent the mirror and second ends of the fiber optic tubes feed the scanned light beam onto respective detectors that detect various gaseous components in the vehicle exhaust. Using the fiber optic tubes eliminates the need for secondary mirrors and reduces the requirement for highly accurate optical alignment among the components of the system.

Remote vehicle emission analyzer with light conveyance to detectors

Apparatus for detecting and measuring relative concentrations of pollutants such as HC, CO and CO.sub.2 in the exhaust emissions from passing vehicles includes an infrared (IR) beam source for directing an IR beam through a vehicle's exhaust plume and a detector disposed on one side of a roadway and a lateral transfer mirror (LTM) disposed on the other side of the roadway for lateral reflecting of the IR beam back through the vehicle's exhaust plume and onto the detector. The LTM allows for close spacing and precise alignment between the emitted and reflected beam paths and permits the IR beam source and detector to be disposed in a single module. Compensation for variation in a range of vehicle operating conditions is provided by adjustable, computer-controlled potentiometers, while audio and/or visible light feedback of the detected IR signal allows a single operator to precisely align the optical components of the apparatus. The IR detector module includes a rotating mirror arrangement for directing the reflected IR beam in a pulsed manner onto a plurality of spaced detector elements, each adapted for detecting a specific pollutant, with the detector elements calibrated with each detected IR pulse to reduce errors arising from circuit drift.

Remote sensor device for monitoring motor vehicle exhaust systems

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Tucson, AZ, United States of America

Dennis L Smith