Study On Test Methods And Standards For Exhaust Pollutants From In-use Gasoline Vehicles

With the development of automobile industry and a sharp increase of vehicles'quantity, vehicle exhaust emission has become a main source of atmosphere pollution. Hereby,countries all over the world established relevant regulations,standards and rules to improve atmosphere environment deteriorated gradually and protect human health. Control of exhaust emission of in-use vehicles is one of most effective means to decrease the atmosphere pollution. Test methods of exhaust emission of in-use vehicles have been developed from idle mode to double idle mode and simplified loaded mode gradually at home and abroad. There are many kinds of test methods of exhaust emission of in-use vehicles. These test methods in circulation test,the principle of gas analysis,the test cost,application area and test accuracy grade are different. Hence, study of exhaust inspection methods and emission standards for in-use vehicles are required urgently in environment protection.This paper introduces the generation and harm of exhaust emission of vehicles and test methods of exhaust emission for in-use gasoline vehicles, and compares the test methods, and analyzes the implementation situation of test standards based on the survey of control of exhaust emission for in-use gasoline vehicles all over the country.This paper studies the exhaust emissions of flexible fuel taxies by the means of following test modes:idle mode,double idle mode,Acceleration Simulation Mode (ASM) steady mode and Instantaneous Mode (IM) 195. Firstly, based on the results of the tests,it compares the different test results under different test modes and calculates the vehicle emissions effective recognition ratios of idle mode,double idle mode and ASM mode, relatively to IM 195. Secondly, it compares emission characteristics of taxies under different test modes and analyzes the relationships between the emission levels of CO,HC,NOx and vehicles'driving mileages, which provides scientific basis for drawing up the exhaust pollutants standard of in-use vehicles in various provinces. Thirdly, in order to show intuitively the influence of vehicles'driving mileages on emission values,it not only studies the relationships between driving mileages and emission pollutants,but also sets up parabola regression equations between exhaust emission values and vehicles'driving mileages , and identifies the significances of the equations. Fourthly, it carries out the exhaust emission tests to flexible fuel taxies by the method of Instantaneous Mode (IM) 195,which is close to the real operating conditions of vehicles, and compares emission characteristics of gasoline and CNG under IM195,the relationships between the exhaust emission levels and vehicles'driving mileages,and the influence of burning different fules on exhaust emissions. Lastly, it carries out a lot of tests on real in-use gasoline vehicles under idle mode,double idle mode and ASM, studies the pollutants limits for in-use vehicles under different modes, and concludes the inspecting association rule of ASM5025 and ASM2540.Based on lots of inspection tests,this paper has established test standards of exhaust emission of in-use gasoline vehicles and natural gas vehicles according to development status of automobile and related industries and actual situation of controlling exhaust emissions of vehicles of Shaanxi Province.