液压阀U形阀口位移—面积变化曲线，将阀口开度与过流面积之间的关系生成曲线图，可作为控制信号输入amesim,进行系统仿真(The u-shaped valve outlet displacement of hydraulic valve, the curve of area change, generates the curve diagram of the relationship between the opening of the valve and the over-current ar