Laser detection system for oxygen concentration in tail gas of vehicle-mounted type motor vehicle

Abstract

The invention relates to a laser detection system for oxygen concentration in tail gas of a vehicle-mounted type motor vehicle. The laser detection system comprises an optical absorption tank and a tunable semiconductor laser absorption spectrum detection device, and is characterized in that the optical absorption tank is a diffuse reflection optical absorption tank; laser beams output by the tunable semiconductor laser absorption spectrum detection device are transmitted to an optical fiber flange through optical fibers and penetrate through a window mirror to be reflected into a diffuse reflection tank; in the diffuse reflection tank, the laser beams are diffusedly reflected to a focusing lens through a diffuse reflection mirror and then are transmitted into the tunable semiconductor laser absorption spectrum detection device through a photoelectric detector to carry out optical intensity normalization treatment on a second harmonic signal by a direct-current component; then an L-M algorithm is used for carrying out least square fit on a fitting function model; and a fitted second harmonic signal sequence is subjected to temperature correction to directly calculate the oxygen concentration in the tail gas of the vehicle-mounted type motor vehicle.

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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