Application Of Non-dispersive Infrared Detection Technology In Engine Air-fuel Ratio Control

In recent years,vehicle emission standards have become increasingly strict,and for the engine control system has put higher requirements.The key to improving engine emissions is the precise control of the air-fuel ratio of the engine.This paper proposes an air-fuel ratio control method based on the bat algorithm to adjust the PID parameters,and corrects the engine fuel injection by detecting the engine exhaust gas concentration by non-dispersive infrared technology.The control accuracy of the engine transient air-fuel ratio is further improved.Firstly,the paper systematically expounds the structure of the engine air-fuel ratio control system.The main content of this paper is to maintain the actual air-fuel ratio near the target air-fuel ratio under the transient conditions of the engine.The paper uses closed-loop control and open-loop control to control the air-fuel ratio.The closed-loop control uses the PID controller based on the bat algorithm to control the air-fuel ratio.The open-loop control is combined with the non-spectral infrared method.The concentration calculation calculates the optimal intake manifold pressure to correct the fuel injection amount and achieve precise control of the air-fuel ratio.The paper focuses on the principle of non-spectral infrared detection technology,and designs a set of non-dispersive infrared detection systems,including the design of infrared light source,air chamber,filter and infrared detector,and the design of high-precision amplification and filtering signal processing circuit..Compared with the traditional nondispersive infrared detection technology,this paper uses the two-channel method to measure the concentration of various component gases in the engine exhaust,and converts the light intensity information into a voltage signal that can be measured visually,which realizes the engine exhaust.Simultaneous and precise detection of three components of carbon monoxide(CO),carbon dioxide(CO2)and hydrocarbon gas(HC).The paper also completed the calibration of the non-spectral infrared detection system.The standard concentration of the gas to be tested was detected by the non-dispersive infrared system,and the voltage ratio of the measurement path and the reference path was obtained.The gas concentration and the ratio were fitted to the data to obtain their Functional relationship between.Through the experiments at different temperatures,the influence of different temperature values on the gas concentration was measured,and the temperature compensation of the system was completed.Calibration and temperature compensation provide a functional basis for accurate measurement of the concentration of the three components in the engine exhaust.Considering the operational difficulty of the control system on the actual engine,the engine average model is established according to the physical characteristics of the engine.For the transient characteristics of the engine,this paper proposes a PID controller based on the bat algorithm tuning parameters,and further passes the The concentration of three gases in the engine exhaust gas is detected,the optimal intake manifold pressure is calculated,the fuel injection amount is corrected,the engine air-fuel ratio control strategy is established,and the strategy is applied to the engine model to complete Simulation test.It can be seen from the simulation results that the control strategy effectively shortens the control time when the air-fuel ratio reaches steady state compared with the traditional control method.Moreover,the control accuracy of the air-fuel ratio of the engine under transient conditions is improved,and the fuel economy and exhaust emission of the engine are greatly improved.