The Balance Analysis And Balance Optimization Design Of Engine

The vibration problem of engine is always the negative factor that influence the working performance of engine and vehicle. In recent years,as the raising demands of light-Weighted vehicle body and high power engine,the vibration problem of vehicle caused by engine is more and more obvious.The vibration of engine is caused mainly by the unbalanced inertial force of piston and crank link mechanism.So it is an important measure for the vibration source contol of engine to design the balance mechanism.The balance analysis and balance mechanism optimization design of engine is studied in this paper.Firstly,MATLAB and ADAMS softwares are used to complete the balance analysis of engine,and the main vibration sources are obtained. Then the balance methods of inner equilibrium and outer balance of engine are studied.The design of balance shaft and the balance methods of the overturning moment are mainly studied.at last,balance weight and balance shaft mechanism is designed to achieve inner equilibrium and outer balance of the engine.The main contents of the paper are as follows:(1)The traditional modeling concept based on the pivot force system is studied,and with the concept,using MATLAB program,a suite of quick balance analysis method which is suitable for any common engine is achieved.(2)The crank link mechanism model with flexible crankshaft is achieved in ADAMS,and using the model,the balance analysis of engine is done.(3)The goal of inner balance of engine is studied,and two kinds of balance weight distribution schemes are designed,then the influence of the balance weight distribution schemes to the internal moment of crankshaft and bearing forces are studied. (4)As the working curve of the balance shaft mechanism is sine curve or cosine curve,the design plan that optimizing the best working curve of balance shaft firstly and then designing the balance shaft with the best working curve is raised.(5)A method that can make the installation position of balance shaft change freely is studied, which can adapt to different engine inner space,and can avoid the interference effctively.(6)Based on the frequency analysis of the overturning moment,a method of founding an approximate mathematical function of the overturning moment is studied,and using the mathematical function,the balance shaft installation parameters can be directly obtained without too much calculation.As the vibration components of overturning moment are mainly located at several frequencys,a method that design several balance shaft with different speeds to balance the main vibration components is obtained.Based on the theories above,using a certain 60°V8 engine as an example,the balance analysis and balance mechanism optimization design of the engine is completed.The simulation of the mechanism design is done in ADAMS,and all the simulation results achieve the expected balance effects,which verify the validity of the theories obtained in this paper.