Design For Six Sigma For Engine Valvetrain System Design

As the government requirement for automobile energy saving and emission reduction is increasing,fuel consumption and emissions have become the most important factors of engine performance.Variable valve timing system(VVT)will play a very important role for fuel economy.It can reduce the pumping loss and achieve a good mixture of gas in cylinder,also can change the compression ratio and residual gas,use Atkinson/Miller cycle at some conditions,so as to improve the engine fuel economy and emissions,improve engine performance and market competitiveness.The strategy of the camshaft phasing adjustment plays an important role in the engine cold starting,catalytic converter heating,and the sweeping of the residual gas,also for using the Atkinson / Miller cycle.DFSS(design for six sigma)is a new design concept based on improving the robustness of the design,which has been widely used in various fields in recent years.It is to optimize the design,reduce the timing and cost by a series of quality control tools and methods.Finally improve our design process to be more efficiency and meet our customer's requirements.In this paper,it is to develop and optimize the engine valvetrain system design by using DFSS design process and tools.Define the design targets through the analysis of the customer's requirements.Use Pugh concept selection to complete the valvetrain system concept design.Optimize the valvetrain system design parameters by DFSS design tools to improve the engine WOT performance.Utilize Atkinson/Miller Cycle to improve the engine fuel consumption at engine part load condition.Finally verify the results by using GT-Power simulation and engine bench test.The results of this paper show that combining DFSS with valvetrain system design process can improve the valvetrain system design more robust,using DFSS tools to optimize the VVT design can improve engine performance,and application of Atkinson/Miller Cycle can improve the engine fuel consumption at engine part load conditions.