考虑转动副特性的发动机静叶调节机构动态性能分析

DYNAMIC PERFORMANCE ANALYSIS OF ENGINE VSV ADJUSTMENT MECHANISM CONSIDERING THE CHARACTERISTICS OF REVOLUTE JOINT

发动机静叶调节机构空间运动复杂,前人的研究并未涉及整机的动力学方程,运动副特性及驱动方式对调节机构动态性能的影响尚不明晰.本文通过将第一类拉格朗日方程与改进的接触模型和LuGre摩擦模型相结合,建立了考虑转动副间隙和摩擦特性的静叶调节机构动力学模型,并探究驱动方式对调节机构动态性能的影响.针对做空间转动的连杆的质量矩阵随时间不断变化这一问题,本文给出详细推导公式.将数值模拟结果与Adams仿真进行了比较,验证结果的正确性.通过对比匀速驱动、简谐驱动及梯形驱动方式表明,简谐驱动有助于减小运动过程中的阻滞力,提高摇臂的动态稳定性,分析驱动方式对间隙运动副耗能的影响后发现简谐驱动更节能.此外,考虑摩擦后,各驱动方式的阻滞力增幅明显,摩擦会加剧阻滞力.

The previous studies did not involve the dynamic equation of the whole VSV adjustment mechanism.The influence of the joint’s characteristics and driving mode on the dynamic performance of the VSV adjustment mechanism is still unclear.In this paper,by combining the Lagrange equation with the improved contact model and LuGre friction model,a dynamic model of the VSV adjustment mechanism considering clearance and friction is established.The influence of the driving mode on the adjustment mechanism’s dynamic performance is explored.In order to solve the problem that the mass matrix of the link rotating in space changes with time,this paper derives a formula with detail.The numerical results are verified by comparison with Adams simulation results.The comparison of uniform speed,harmonic drive and trapezoidal drive shows that harmonic drive can help to reduce the blocking force and improve the dynamic stability of the adjustment mechanism.After analyzing the influence of driving mode on the energy consumption of clearance joint,it is found that the harmonic driving is more energy-saving.Besides,the blocking force of each driving mode increases significantly with friction,and friction will increase the blocking force.