Three Cylinder Gasoline Engine Balance Strategy Research

Three cylinder small engine in terms of cost,weight,friction power(fuel consumption)has obvious advantages,so the development and application of three cylinder small displacement gasoline engine is the main direction of the development of gasoline engine at the present stage.However three cylinder reciprocating internal combustion engine,due to the inherent system of first-order and second-order moment imbalance,in passenger cars using three cylinder engine to replace the original four cylinder engine and still maintain original user comfort,this is the key point in an engine development project,especial for the project which without balance shaft is under the biggest challenges.So three cylinder gasoline engine balancing strategy research is the key to the application of the three cylinder engine without balance shaft.By establishing the relationship between three cylinder machine balancing strategy and vehicle driving comfort,and based on CAE simulation analysis and experimental evaluation of combined to confirm the actual choice of the balancing strategy,and then taking the batch manufacturing capability and the vehicle configuration match probability into account,finally we got a decision to implement the equilibrium strategy design.This paper relied on an actual project,it states the balance strategy selection,how it optimized and applied.It includes the following research projects:Using the Welch method,an automatic program is programmed to analyze and solve the cylinder pressure of the three cylinder engine.Based on a study on the relationship from vehicle level vibration to engine cylinder pressure and its speed fluctuation rate,it sets up a comprehensive and systematic analysis and evaluation methods.It includes two parts,in the whole point of view,it uses CAE tools for the moment of inertia analysis,load calculation,dynamic assembly bending modal analysis,speed fluctuation rate calculation and other research work.In the view of vehicle,with the aid of data acquisition equipment,it uses the idle noise from right ear,idle steering vibration and idle seat vibration and other status of automobile vibration index,to establish the vehicle level evaluation model.Finally the balance samples was retrofitted to the vehicle,did the vehicle vibration measurement and evaluation.To make the balance product strategy more robust,it develops a unbalance robustness check method,which is introduced with the specified physical meaning of the polar coordinate system,a statistical calculation through the graphical representation to reflect the actual distribution,so as to guide to design the optimization direction.Based on the method which listed above the actual project was successfully got an appropriate balancing strategy,and also got an optimized product design from the original crankshaft unbalance design,it helped a scrap rate of 17% to be close to a zero waste rate,saving approximately 400 thousand a year.