Research On Pulley Misalignment And Noise Of Accessory Drive System

Engine front end accessory drive system is an important system in automobile.The system transmits the power output from the engine crankshaft to the accessory pulleys of air conditioning compressor,generator,steering pump,water pump and fan through belt.At present,the engine front end accessory drive system is widely used,because it has the advantages of large contact area,large transmission power,wedge and back drive,compact arrangement and convenient maintenance.However,there are some problems in the transmission process of the accessory drive system,such as sliding,offset and wear of the accessory pulleys.Therefore,the vibration and pulley misalignment and noise of engine front end accessory drive system will be taken as the research object,and the following work will be carried out:(1)The principle of layout design of engine front end accessory drive system and the design method of static and dynamic characteristics of the system are discussed.The calculation methods of static characteristics such as installation tension,natural frequency of belt section and performance parameters of automatic tensioner are summarized.(2)This paper defines the pulley misalignment of the engine front end accessory drive system,introduces the main static characteristic parameters of the poly V-belt accessory drive system,analyzes the influence and manifestation of the misalignment error,and builds the model of two forms of pulley misalignment.The axial installation offset of the pulleys of the system is modeled,and the model is used to analyze the abnormal noise of the front end accessary drive system in practice.At the same time,the allowable axial installation offset of each pulley in the system is optimized by particle swarm optimization algorithm.Through MATLAB software programming,the non-uniformity calculation and axial installation offset optimization of the front end accessory drive system of any engine can be carried out.(3)Two kinds of measurement methods of misalignment are described.The mathematical model of the spatial deflection of each pulley in the front end accessory drive system of the engine is established.The finite element simulation of the pulley misalignment is carried out with the rigid flexible coupling model of belt-pulley transmission.The influence of the spatial deviation and deflection of the pulley on the actual belt pulley misalignment is studied.At the same time,the four-pulley multi-body dynamic model is established,and the influence of the wheel unevenness on the dynamic characteristics of the system is studied.(4)This paper discusses the noise source of engine front end accessory drive system,introduces and explains the noise test bench and related test equipment,analyzes the influence of different influencing factors on the noise through bench test,and summarizes the test and analysis methods of engine front end accessory drive system noise.