一种伺服电机驱动的比例换向阀结构设计与特性分析

针对传统的电动伺服比例换向阀存在结构复杂、动态特性差的不足,提出一种伺服电机驱动的大流量比例换向阀,采用定差减压阀进行压力补偿,直流电机作为动力元件,通过丝杠螺母机构连接阀芯轴,以此控制主阀芯的位置。设计双闭环控制系统提高阀芯控制精度。运用动力学原理建立比例换向阀数学模型,对比例换向阀稳态性能进行理论分析,研究其动态性能。进一步利用MATLAB/Simulink软件搭建了比例换向阀控制系统仿真模型,并进行了稳态与瞬态特性仿真。结果表明：比例换向阀阶跃响应速度达到36 ms,验证了所提出的比例换向阀具有较好的响应速度和稳定性;通过瞬态特性仿真得到比例换向阀的阀口流量随电机转角的变化曲线,获得电机转角和阀口流量特性控制函数;验证了采用定差减压阀方案可以在负载变化时进行较为理想的压力补偿,比例换向阀的控制精度达到98%。

Structure Design and Characteristic Analysis of Proportional Directional Valve Driven by Servo Motor

The traditional motor-driven servo proportional directional valve has the shortcomings of complex structure and poor dynamic characteristics.A large flow proportional directional valve driven by servo motor was designed,and constant differential pressure reducing valve was used to compensate pressure.The DC motor was used as the power component,and the valve core shaft was connected through the lead-screw nut mechanism to control the position of the main valve core.Double closed-loop control system was designed to improve the control accuracy of the valve core.The mathematical model of proportional directional valve was established based on the principle of dynamics.The steady-state and dynamic performance of proportional directional valve was theoretically analyzed.Furthermore,utilizing MATLAB/Simulink,the simulation model of proportional directional valve control system was established,and the steady-state and transient characteristics were simulated.The results show that the step response speed of the proportional directional valve reaches 36 ms.It is verified that the proposed proportional directional valve has good response speed and stability;through transient characteristic simulation,the curve of valve port flow of proportional directional valve changing with motor angle is obtained,and the control functions of motor angle and valve port flow characteristics are derived.It is verified that the constant differential pressure reducing valve can be used to compensate the pressure when the load changes,and the control accuracy of proportional directional valve can reach 98%.