Research On Experimental And Modeling Methods For Engine Front End Accessory Drive System

The Engine Front End Accessory Drive(FEAD)system is a part of the vehicle engine which is one of the most important applications for belt drives.Optimizing the FEAD system can not only improve the transmission efficiency,reduce vibration and noise,but also increase the fatigue life of the belt and save maintenance costs.Therefore,in the FEAD system development process,modeling and analyzing are particularly important.The research topic is "Research on experimental and modeling methods for engine front end accessory drive system".The purpose of this study is to propose the generic modeling and analyzing methods for FEAD systems,which can be applied to model the systems with different components and layouts by using modular modeling methods.The test methods are purposed to obtain the model parameters and verify the validity of the model.This article carried out and completed the following four aspects of research works:(1)The generic modeling methods for FEAD systemsThe generic coordinate methods for the representation of the FEAD systems’ layout is proposed.The advantage of the generic coordinate method is that the layouts of the FEAD systems can be represented by the coordinates of pulleys’ centers,radii and the directions of the belt spans.In the generic modeling method,the components of the FEAD systems are classified into three models: pulleys,tensioners and belt spans.The equations of motion of each model is presented respectively.(2)The methods of solving the generic model of the FEAD systemsThe dynamic methods for solving the models are proposed.Runge-Kutta numerical method is used to solve dynamic response of FEAD systems.The static analysis methods of FEAD systems are proposed.The calculation methods of the tensioners balance positions,the average tension,the initial tension and the tensioner spring stiffness are proposed respectively.(3)Testing methods of the FEAD systemsThe testing methods of the speed fluctuation of each pulley and the oscillation of the tensioner arms are presented.The time and spectrum analysis of the measured data are carried out.The variation of the vibration amplitude with the crankshaft speed are analyzed emphatically.Moreover,the testing methods of the stiffness and damping of the tensioners are presented.The Young’s modulus and the viscous coefficient of the belt are measured,which provide the input parameters for the generic models of the FEAD systems.(4)The results and analysis are verified by experimentsTaking the FEAD system with five pulleys as an example,the speed fluctuation of each pulley and the oscillation of the tensioner arm are calculated.And the results of the generic model are compared with the test results.The validity of the generic modeling and solving methods is verified by comparing the measuring data with calculation results.Taking the FEAD system with nine pulleys as an example,the results verify the versatility of the general modeling and solving methods for FEAD systems.Taking the FEAD system with ISG and twin-arms tensioner as an example,the speed fluctuation of the ISG pulley,the tension of the belt spans and the angle of the tensioner arms are calculated.The crankshaft vibration excitation with the average speed rising is used.Moreover,the speed of each pulley,the tension of the belt and the oscillation of the tension arms are calculated when the ISG pulley drives the crankshaft to rotate.Comparing calculation results with the experiment data,it is proved that the general modeling and solving methods can be used to analyze and calculate any kinds of FEAD systems with different components and layouts.