变惯量多体曲轴轴系发动机动力学仿真

Dynamic Simulation of Engine Based on Variable Inertia and Multi-body Crankshaft System

基于拉格朗日方程,在考虑曲柄连杆的变惯量、气缸的摩擦扭矩和燃气压力总指示扭矩的基础上建立了发动机曲轴轴系动力学模型。利用ADAMS内置的参数点坐标、参数化方程功能,在ADAMS内二次开发了集曲轴轴系结构参数、摩擦扭矩参数、负载扭矩参数和发动机点火次序选择的参数化软件。通过曲轴柔性处理获得轴系模态中性文件,由ADAMS/FLEX模块导入到ADAMS中建立了柔性曲轴的发动机多体动力学虚拟样机,结合某型车进行了动力学仿真。结果表明,发动机有效输出扭矩受摩擦扭矩和变惯量扭矩的影响较大,柔性曲轴比刚性曲轴能更好地模拟发动机曲轴,为车辆动态性能仿真提供了良好的发动机模型,并可为发动机的轴系设计、曲轴的强度校核和寿命计算提供准确的载荷。

The dynamic model of engine was established by analyzing the inertia of connecting rod, the friction torque of piston and the indicating torque of gas pressure with the Lagrange equation. With the internal point coordinate and equation of ADAS software, the parameterized graphics user interface （GUI） that integrated the crankshaft structure parameters, the friction torque, the load torque and the ignition order was developed. The crankshaft modal neutral file was acquired by the flexible treatment of crankshaft, the multi-body dynamics virtual prototype was built by importing the ADAMS/FLEX module into ADAMS software and finally the dynamic simulation was carried out on an engine. The simulation results show that the engine effective output torque is influenced by the friction torque and variable inertia torque. Compared with the rigid crankshaft, the flexible crankshaft can simulate the actual engine crankshaft more accurately. Accordingly, the model is suitable for the vehicle dynamic performance simulation and its produced accurate load is helpful for the design, strength verification and lifetime calcu lation of crankshaft.