Design And Research On The Fuel System Of A Passenger Car Meeting The China 6 Emission Limits

In recent years,automotive hydrocarbon emissions have become the main and growing source of VOC emissions.Controlling the volatile organic compound pollution from automotive emissions is critical to controlling air pollution in major cities in China.With the release and implementation of the Limit and measurement methods for emissions from lightduty vehicles(CHINA 6),gasoline vehicles must be equipped with an ORVR(Onboard Refueling Vapor Recovery)fuel systems that meet the China 6 evaporation and refueling emission limit.The ORVR fuel system can effectively recover the fuel vapor generated during the refueling process of automobiles and reduce the environmental pollution caused by VOC emissions.This article undertakes the development project of a China 6 fuel system for a certain passenger car model of Dai Sheng Automotive Technology(Suzhou)Co.,Ltd.Through the research in this article,master the design method of the core components of the fuel system,and design the fuel system for a passenger car to meet the China 6 evaporation and refueling emission limits,also provide a reference for domestic component and vehicle manufacturers to independently develop fuel system that meets the China 6 emission limits.Firstly,find out the reasons for the high HC emissions in the refueling process of the current fuel system of the car,redesign and match the ORVR fuel system that meets the China 6 evaporation and refueling emission limits for the passenger car: according to the performance requirements of the china 6 standard for fuel system,allocation of evaporative emission limits and the 3D boundary constraints of the body structure of the passenger car,redesigned fuel cap,fuel filler pipe assembly,fuel tank assembly including control valve,redesign the vent pipe,design the material of each component,estimate the amount of diurnal vapor generation and refueling vapor generation and calculate the working volume of the activated carbon canister that needs to be matched.Secondly,perform simulation research on the refueling performance of the ORVR system,establish the refueling model of the fuel system in this paper,and use Fluent fluid simulation to analyze the refueling performance under different refueling conditions and different fuel filler pipe design parameters.The simulation results show that the filler pipe designed for the passenger car can form a good liquid seal under the conditions of refueling speed of 37L/min and 45L/min;the angle A between the first section and the vertical section of the fuel filler pipe has an effect on both of the liquid seal and the smoothness of refueling.As the angle A decreases,the performance of the liquid seal deteriorates and the pressure drop in the fuel filler pipe increases;the length L of the first section of the filler pipe has a greater effect on the smoothness of refueling.As the length L decreases,the risk of reverse flow and premature shut off increases;the angle B between the end of the fuel filler pipe and the vertical section has a greater impact on smoothness of refueling.As the angle B decreases,the pressure drop in the filler pipe increases.Finally,the experimental soft model of the fuel tank assembly,the transparent 3D printing of the fuel filler pipe,the combined valve with two different size of FLVV(Filling Limit Venting Valve)and GVV(Grade Venting Valve)vent are made,and the liquid seal performance and the refueling smoothness performance of the fuel system is verified through the refueling experiment.The experimental results show that the fuel system designed in this paper meets the refueling smoothness requirements at 37L/min and 45L/min.It is concluded that the GVV vent size is the key factor for controlling the refueling reverse flow during the second refueling.For the fuel system designed in this paper,when the vent size of GVV is 2.5mm,the refueling smoothness is better.In addition,the fuel system refueling emissions test(Type ? test)was carried out.It is found out that the final emission result was 0.0013g/L,which meet the emission limit requirements of the China6 Type ? test.