Study On Multi-body System Dynamics Of Engine Valve Train

As one of the most important motion parts of engine, valve train is used to open and close the valve on time in order to intake fresh gas or discharge the exhaust gas according to the requirement of engine. The characteristic of valve train has great effect on the performance of engine, including the power output, the fuel consumption, the emission and vibration, etc. Valve train have to meet more requirement when the speed of modern engine become higher and higher, so researching and developing a valve train with good dynamic characteristic is a very meaningful work.This paper focus on study the dynamics characteristic of valve train in one type of diesel engine, the main task are:1) Create the three dimension model of valve train according to the drawing released by the factory, and build up the multi-rigid body dynamic model of the valve train by using ADAMS software. Test the model and get some dynamics parameters ,such as the valve displacement , valve acceleration, valve seating force, etc, by which can we do some estimation of the valve train.2) Because the deformation will happen when valve train is running, this paper build a model which can correctly describe the dynamic characteristic of valve train. The model is hybrid rigid-flexible multi-body system, form which can we get more parameters of valve train, such as the stress and strain of the part in the model. The model is build based on the multi-rigid body system .In the hybrid rigid-flexible multi-body system, the rocker arm and push rod are created as flexible body.3) Compare the simulation result of the two model mentioned above ,we find that: The valve train run smoothly, its seating velocity and seating force do not violate the limitation of the material. Because the speed range of prototype engine is not so wide , there is not so much difference between the simulation results get from multi-rigid body model and hybrid rigid-flexible multi body model .4) Establish a test bench for valve train dynamics test, and propose some new test methods for valve train test .The methods of equipment installation is also introduced in this paper.5) Build a test bench which can be used for steady state stress calibration test and valve train stiffness measurement.