Study On Dynamic Behavior Of Timing Roller Chain Drive

With the development of engine technology, roller chain drive is applied increasingly to the automobile engine timing drive. However, polygon effect and meshing impact make it impossible for the classical chain-drive to meet the requirement of automobile engine. So it is urgent for us to study new chain-drive mechanism furtherly and explore new chain-drive technology which gear to timing drive system.Firstly, structure FEA and contact FEA are utilized to study elastic deformation on outer-link, inner-link , driving-sprocket and driven-sprocket. Some results can be achived arising from the study. Elastic deformation of links follow Hooke's law basically. Outer link experiences greater deformation than inner link. The deformation of outer link will has a bad effect on the timing roller chain drive. All these data can be used as a reference when a shape optimization on chain will be made.Secondly, dynamic simulation was carried out on a timing roller-chain drive system through engine simulation software based on multi-body dynamics. Some results can be achieved from the study. Dynamic tension between two links is greater than static tension. Dynamic load could not be ignored in the chain dynamic tension. When a link engages and disengages with other transmission components, there is a greater contact force between the link and other components. It can be seen that on parts of trajectory, which are free of support(between sprockets and guides), transversal vibrations occur. Angular velocicy of camshaft sprocket varies from time to time. A resonance area of the timing roller-chain drive can be recongnized; The resonance frequency is approximately 400Hz. So some properties about chain drive can be get through the simulation which can be applied when some components need be improved.Lastly, under the help of classical chain-drive theory and CAE ,a method is proposed which will be used to modify tooth profile of a sprocket in a directional way based on GB/T 1243. Comparative study show that the drive system using the nonstandard sprocket is improved in many ways such as chain tension, contact force and friction force between chain and transmission components, tension force provided by tensioner, angular velocity of camshaft sprocket. So by applying the nonstandard sprocket , the carrying capacity of the chain is increased ; transmission efficiency is improved; system life is extended; engagement impact is reduced; noise is reduced and polygonal effect is decreased. Therefore,the new sprocket can adapt to engine timing drive.