Research of Median-Nonlinear Flow of Proportional Valve

Abstract

In the traditional proportional valve mathematical model, the nonlinear flow characteristics induced by the geometrical features in various flow areas were often ignored. To overcome this problem, the uniform nonlinear flow mathematical model for the electro-hydraulic proportional valve is constructed. The relational expression between the orifice flow of the proportional valve and the geometrical future and physical characteristics of spool is constructed to obtain a series continuous nonlinear flow equations of median positive overlap, negative overlap and zero overlap proportional valve. The experiment validates that, for positive overlap, the flow input into the hydraulic tank is proportional to the displacement of the spool in the dead zone. For negative overlap, even though the spool located at the median, the flow output also exists, and induces the piston movement of hydraulic tank. This situation is consistent with the non-matching overlap response of actual negative proportional valve.