초록 ▼

A non-dispersive infrared gas analyzer is disclosed that accurately measures the concentration levels of a plurality of gases within a gas mixture. The analyzer includes first and second sample cells and is utilized advantageously for the measurement of NOx and hydrocarbon gas present in the exhaust

A non-dispersive infrared gas analyzer is disclosed that accurately measures the concentration levels of a plurality of gases within a gas mixture. The analyzer includes first and second sample cells and is utilized advantageously for the measurement of NOx and hydrocarbon gas present in the exhaust of an automobile engine. The gas mixture of the exhaust is chilled before entering the first sample cell to remove a substantial amount of the water vapor from that sample cell to facilitate measurement of the NOx gas. The second sample cell receives the gas mixtue in an unchilled state to allow for accurate measurement of the hydrocarbon gas. The analyzer includes processors which are utilized to further correct the NOx measurement and which also interact with each other to provide an output data stream that is representative of the concentration levels of the gases that are being analyzed.

대표청구항 ▼

A non-dispersive gas analyzer comprising: a first sample cell for containing a sample gas mixture to be analyzed for the presence of NOx gas; a second sample cell for containing said gas mixture to be analyzed for the presence of hydrocarbon gas; means for directing infrared energy through said firs

A non-dispersive gas analyzer comprising: a first sample cell for containing a sample gas mixture to be analyzed for the presence of NOx gas; a second sample cell for containing said gas mixture to be analyzed for the presence of hydrocarbon gas; means for directing infrared energy through said first and second sample cells; means for modulating the amplitude of said infrared energy; means for dehumidifying said gas mixture entering said first sample cell; first detector means for detecting the infrared energy passing through the dehumidified gas mixture in said first sample cell at a characteristic absorption wavelength of said NOx gas and producing a first signal representative thereof; second detector means for detecting the infrared energy passing through said second sample cell at a characteristic absorption wavelength of hydrocarbon gas and producing a second signal representative thereof; processor means for processing said first signal of said first detector means to provide an indication of the concentration level of NOx gas in said gas mixture and for processing said second signal of said second detector means to provide an indication of the concentration level of hydrocarbon gas in said gas mixture; and means for measuring a residual amount of water vapor within the dehumidified gas mixture in said first sample cell and for providing a correction signal representative thereof, wherein said processor means utilizes said correction signal to provide a more accurate indication of the concentration level of NOx gas.