伺服阀滑阀阀口系数影响因素分析

分析电液伺服系统中液压缸活塞位移、液压刚度、阀口开度、外负载刚度及阀芯与阀套间径向间隙对伺服阀阀口系数的影响。采用工作点线性化的处理方法,通过引入液压缸负载力方程,给出零开口电液伺服阀滑阀流量-压力系数和流量增益的计算公式,并对其影响因素进行分析。结果表明,在液压缸全行程中,流量-压力系数会随着液压缸活塞位移、外负载刚度及阀口开度的增加而增大,其中流量-压力系数随液压缸活塞位移的增大呈抛物线增长,其最大值约为最小值的2倍;流量增益随着液压缸活塞位移、外负载刚度的增大而减小,其中流量增益随液压缸活塞位移的增大而近似呈线性规律减小,其最小值约为最大值的1/2;阀芯与阀套间径向间隙对阀口系数随液压缸活塞位移变化率的影响不大;阀口系数在液压刚度取最小值附近时存在突变;同一液压刚度值可对应2个不同的液压缸活塞位移,分别对应的阀口系数值相差非常大。

Factors influencing the orifice coefficients of a servo spool valve

The factors influencing the orifice coefficients of the servo valve including hydraulic cylinder piston displacement, hydraulic rigidity, orifice opening, load rigidity and the radial clearance between spool and sleeve were analyzed. With the introduction of the hydraulic cylinder-load equation, the formulas for flow-pressure coefficient and flow gain of the servo spool valve were obtained by the linearization of the flow equation at the operating point. The numerical calculations show that, in the full hydraulic cylinder stroke, flow-pressure coefficient will increase with the increment of cylinder displacement, load rigidity and orifice opening,exhibiting parabolic trend increase with the piston displacement,and the difference between the maximum and minimum value is about 2 times. Flow gain will decrease with the increase of cylinder piston displacement and load rigidity. The reduction of flow gain is approximately linear with the increase of the piston displacement, and the minimum value is approximately half of the maximum. The rate of change of the hydraulic cylinder pistion displacement has little effect on the radial clearance between the valve core and flat. There are jumps in the orifice coefficients near the minimum hydraulic rigidity. The same hydraulic rigidity value corresponds to two different piston displacements, and the orifice coefficients vary widely.