An Analysis of the Three-Way Underlapped Hydraulic Spool Servovalve

Abstract

A flow model of a three-way underlapped hydraulic servovalve is presented and used to derive a mathematical description of the flow momentum forces acting on the valve spool. The effect of these forces on valve performance is investigated by examining both the linearized system differential equations and digital computer solutions of the system nonlinear differential equations, and by experimental measurements. A three-dimensional phase space is used to display computer simulation results. Because of the oscillatory nature of system response, projections on a plane illustrate system dynamic response forms. The effects of system parameters on system stability are discussed.