The Theory And Practice On Indirect Measurement For The Transient Exhaust Emissions Of Gasoline Engine

With the strengthen of people's environment protection consciousness, the emission regulations of world are becoming stricter and stricter. During the city road running, the gasoline engines frequently run under the conditions of transient operation modes such as cold-start, warm-up, acceleration and deceleration, while the velocity of the supply of fuel and gas also instantaneous change. As some compositions of poisonous emissions would distinctly change, so the emissions results under the conditions of steady operation modes can't reflect the true results of gasoline engine emissions. At present some research institutions in the world are exploring the ways of real-time dynamic testing, and domestic transient emissions research lag the developed countries, so it is extremely important to research exhaust emissions and test technologies of transient process.In this paper the indirect measurement method of transient exhaust emissions is adopted, as there are no advanced equipments that can be used to real-time dynamic test in most research institutions. It is practical to build the indirect test system to collect the emissions results, and then analyze results and errors. The research items are follows:(1) The current states of gasoline engine transient emissions test technologies are Summarized, then the mechanism and effect factors of major poisonous gasoline engine exhaust emissions are discussed.(2) According to the gasoline engine run conditions of city road, the major transient operation modes that affect the level of atmosphere are ensured and the gasoline transient emissions indirect test system are built under the existing experimentation conditions.(3) Uncompressible system model and compressible liquid-body model â…¢ are developed to build the model of conventional emission analyser pipeline system, and the two frequency response characteristics are analyzed. The reasons of altitude distortion and time delay of conventional emission analyser are analyzed, as well as the thoughts of correcting the altitude distortion and time delay are brought forward according to the frequency response characteristics and the experiment results.(4) The exhaust emissions of the four different vehicles of cold-start, warm-up...