The Balance Shaft Design Of The Four-cylinder In-line Diesel Engine

In order to achieve the more and more strict requirement in acoustics and vibration,people thinks a lot of ways to make engine and vehicle runs smoothly and quiet. The balancershaft technology is an important one of them. From2002, more and more limousine started touse this technology. Through an internal project that add a balancer shaft system to a existedin-line4cylinder diesel engine, this thesis expect to conclude a common design methodologyof the balancer shaft for a common diesel engine. Meanwhile, this thesis focused on the forceof the oscillating masses which was not balanced, made several balance solutions andcompared each other. Then we made an analysis to the initial design of the balancer shaft inintensity, acoustics and vibration, to prove the feasibility of the initial balancer shaft design.This could be a basis for reduce the NVH of this4cylinder in-line diesel engine, and alsocould be a reference for the similar project.At first, we should find out what makes the engine noise and vibrate. So we will analyzethe reason of the2ndinertia force in the4cylinder engine. Meanwhile, for a further research,we compared the2ndinertia force in the offset con-rod engine and the central-located con-rodengine, and found that we can ignore this effect. Secondary, we designed an initial balancershaft system for this engine which can generate the balance force as a design basis. Thirdly,we chose a drive mode from3possible modes, and designed the installation features. Becausethe original engine did not consider the balancer shaft system, there is not too much space forthe drive module. This is a difficult point for this project. Fourthly, we re-designed the oilgallery in the original crankcase. Because of the original engine have no oil gallery for thebalancer shaft system. Fifthly, to reduce the balancer shaft system weight and volume, weoptimized the balancer shaft. Because the less mass of the balancer shaft means the less drivepower requirement and less space needed, this is also a key point in this internal project. Inthe end, we designed a partial bearing balancer shaft which can reduce a lot of masses. At last,we made a CAE analysis for the balancer shaft to prove the feasibility.