摘要发动机在运行时，其内部机构的不平衡质量会在运动中产生振动与噪声，而这些振动和噪声会带来各种各样的危害，包括环境污染与降低发动机的使用寿命等等。而针对发动机内部不平衡的激励源运用相应的平衡机构能够很好的对其进行平衡，从而达到降低振动的目的。因此，关于发动机的平衡性能的研究与平衡机构的设计改进从未停止。84570

本文主要以平面曲轴式8V280柴油机为研究对象，对其进行平衡性能分析并根据其不平衡情况设计出相应的平衡机构对其进行平衡。主要工作如下：

（1）学习了柴油机传统平衡计算的两种2种方法（解析法与图解法），并对两种方法进行了分析比较，确定8V280柴油机平衡计算的方法。

（2）对采用45°、50°、60°、90°的不同气缸夹角的情况进行了平衡性能分析，计算出柴油机的旋转惯性力、旋转惯性力矩，一阶往复惯性力、一阶往复惯性力矩，二阶往复惯性力、二阶往复惯性力矩，得出各力和力矩的平衡情况。

（3）通过计算出的惯性力及气缸中的气压力求得柴油机的倾覆力矩，结合MATLAB软件的曲线拟合功能得到倾覆力矩随曲轴转角的变化曲线图及傅里叶级数的拟合方程，提取出倾覆力矩的二阶谐波分量。

（4）针对造成柴油机振动的二阶往复惯性力与倾覆力矩，提出一种双轴平衡机构，该平衡机构完全平衡了不平衡的二阶往复惯性力，并尽量抵消了倾覆力矩，实现了对柴油机的平衡。

根据以上的研究工作表明：对柴油机进行平衡性能分析并针对分析结果采用相应的平衡机构能有效的降低柴油机的振动，提升其工作性能。

毕业论文关键词：柴油机；平衡分析；平衡机构；优化设计

Abstract When the engine is in operation, the unbalance mass of internal mechanism will produce vibration and noise in motion and these vibration and noise will bring a variety of hazards, including environmental pollution and reduce the service life of the engine and so on。For internal engine unbalance excitation source with the corresponding balance mechanism can very good the balance, so as to achieve the purpose to reduce the vibration。 Therefore, on the engine balance performance research and balancing mechanism design improved never stops。

In this paper, the plane crankshaft type 8V280 diesel engine as the research object, its balance performance analysis and according to the imbalance of the design of the corresponding balance mechanism for its balance。 The main work is as follows:

(1)2 kinds of two methods (analytical method and graphic method) to study the traditional balance calculation of diesel engine, and the two methods are analyzed and compared, and the method of calculating the balance of 8V280 diesel engine is determined。

(2) on the 45 degree, 50 degrees, 60 degrees, cylinders of different angle of 90 DEG were balanced performance analysis, the rotary inertia of diesel engine is calculated, rotation inertia moment, first-order reciprocating inertia force, first-order reciprocating inertia moment, second order reciprocating inertial force, second order reciprocating inertia moment that the force and moment equilibrium。

(3) through the calculation of inertia force and cylinder gas pressure for overturning moment of the diesel engine, combined with the software of MATLAB curve fitting function by overturning moment with the crank angle curves and Fourier series fitting equations extracted overturning moment of second order harmonic component。

(4)in view of the causes of diesel engine vibration of the second order reciprocating inertia force and the overturning moment, and puts forward a biaxial balance mechanism, the balance mechanism is properly balanced unbalanced second order reciprocating inertia force and try to offset the overturning moment, to achieve a balance of diesel engine。