A laser detection system for oxygen concentration in vehicle exhaust

Abstract

The invention relates to a vehicle-mounted laser detection system for oxygen concentration in motor vehicle exhaust. The laser detection system includes an optical absorption pool and a tunable semiconductor laser absorption spectrum detection device; it is characterized in that: the optical absorption pool is diffuse reflection optical Absorption pool; the laser beam output by the tunable semiconductor laser absorption spectrum detection device is transmitted to the fiber flange through the optical fiber, and enters the diffuse reflection pool through the window mirror; in the diffuse reflection pool, the laser beam is diffusely reflected by the diffuse reflection mirror to the After the focusing lens is focused, the photodetector is sent to the tunable semiconductor laser absorption spectrum detection device to normalize the light intensity of the DC component to the second harmonic signal; The least squares fitting is carried out, and then the temperature correction is performed on the fitted second harmonic signal sequence to directly calculate the oxygen concentration in the motor vehicle exhaust.

Description

technical field [0001] The present invention relates to the testing of materials by means of determining their chemical or physical properties, and in particular to the detection of gas concentrations using laser spectroscopy. Background technique [0002] At present, the problem of air pollution is becoming more and more serious. With the continuous increase of the number of motor vehicles in my country, the emission of motor vehicle exhaust is also increasing. Carbon monoxide, hydrocarbons, and nitrogen oxides in motor vehicle exhaust have become the main sources of atmospheric gaseous pollutants. Oxygen is a combustion aid in the combustion process of motor vehicle internal combustion engines. By detecting the oxygen concentration in motor vehicle exhaust in real time, it is possible to diagnose the combustion process of motor vehicle internal combustion engines, optimize the combustion process, and reduce the emission level of gaseous pollutants. [0003] Existing detect...

AI Technical Summary

Problems solved by technology

Although the method described in the above-mentioned patent application detects the oxygen concentration, the method is used to detect the oxygen in the motor vehicle exhaust, and there are the following deficiencies: 1. Because the concentration of oxygen in the motor vehicle exhaust is very low, and the situation is complicated during driving , not only the mechanical vibration is severe, but also the oxygen concentration in the exhaust gas changes rapidly and frequently, and the target surface of the laser detector is small, so it is easy to cause the laser beam to be out of adjustment, and it cannot work stably for a long time

2. Use the measurement spectrum to perform least squares fitting on the calibration spectrum obtained by the known concentration of standard oxygen, and the calibration spectrum used in it cannot be obtained during the driving of the motor vehicle, which will inevitably lead to the acquisition of the detection spectrum and the acquisition of quasi-standard The conditions of the spectrum are inconsistent, so the fitting and inversion results are not accurate

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