计及活塞销间隙的内燃机曲柄连杆机构动力学分析

摘要

Basing on the theory of impact-function for clearance between piston-pin and bushing and the computational dynamics of multibody system, the effect of piston-pin clearance on the dynamic characteristics of a piston-connecting rod-crankshaft system in an internal combustion engine was investigated. The clearance between piston-pin and bushing was described with the impact function method. The three dimensional solid models for piston, connecting rod and crankshaft of a certain internal combustion engine with a single cylinder and the multibody dynamic model for the piston-connectingrod-crankshaft system were established. Considering the mechanism with both rigid and flexible connecting rods, the acceleration and velocity of the piston and the orbit of the piston-pin were analyzed. The influences of the piston-pin clearance on the dynamic behavior of the system were investigated. The results showed that the mechanism responses are greatly influenced by the clearance; there are many sharp peaks on the piston acceleration curves when the piston reaches top dead center (TDC) and bottom dead center ( BDC).%基于活塞销与衬套间隙的冲击函数模型和计算多体动力学的方法,研究了活塞销间隙对内燃机活塞-连杆-曲轴运动系统动力学特性的影响.使用冲击函数方法构建了活塞销与衬套的间隙碰撞模型,建立了某单缸内燃机活塞、连杆和曲轴的三维实体模型及内燃机活塞-连杆-曲轴的多体动力学模型.在刚性和弹性两种不同连杆模型下,通过分析活塞运动的速度和加速度,以及活塞销的运动轨迹等研究了活塞销间隙产生的碰撞特性对系统动力学行为的影响.结果表明,间隙的存在对该运动机构有显著影响,在上下止点附近活塞的加速度出现许多由碰撞产生的峰值.