液压起重机过载自动控制及稳定性研究

Research of Overload Automatic Control and Stability for Hydraulic Crane

为提高起重机变幅系统过载制动的平稳性和快速性,保护起重机臂架安全,提出了一种应用电液比例方向阀平缓切断变幅系统油路的过载自动控制新方法。分析了液压起重机过载控制方式,基于键合图理论建立了变幅系统下降工况的机液耦合模型。应用数学分析软件Matlab对模型进行了数值解析,计算了在30°、45°、60°吊臂仰角、电液比例阀不同关闭时间下,变幅油缸活塞杆的速度响应。得出了变幅系统制动时兼顾平稳性和灵敏性要求,比例方向阀最优关闭时间为0.2s的结论。试验结果验证了仿真模型和优化参数的正确性,为液压起重机过载自动控制系统性能的提高提供了理论依据。

To improve the stability and sensitivity of hydraulic overload luffing braking system of the crane,this paper proposes a new method for automatic overload control, by using the electro - hydraulic proportional directional valve to cut off the oil circuit smoothly and gently. After analyzed the overload control principle, the machine and flu- id coupling model of the luffing system under the descend condition is established, based on the power bond graph theory. A mathematical analysis to the model is made with the software MATLAB, and the velocity responses of the boom cylinder piston rod are studied when the electro - hydraulic proportional directional valve under different closing time at 30° ,45°and 60° boom elevation. It shows that the optimal proportional valve close time is 0. 2s and the sys- tem meets the requirements of stability and sensitivity. The test results verifies the correctness of the system model and optimize the parameters. The research provides a theoretical basis to improve the performance of hydraulic crane overload automatic control.