Adjustment of Proportional Control Valve Characteristics via Pressure Compensation Using Flow Forces

This article concerns flow analysis through a multi-section proportional control valve. In valves of this type, the flow rate is adjusted through an electromagnet current. However, for a fixed control signal value, the flow rate changes as the pressure in the system increases, which is an unfavorable phenomenon. Compensation for pressure influence is usually achieved using additional valves. In this work, the valve characteristics were modified to achieve a possibly steady flow rate by compensating for the pressure using flow forces without the necessity of correction valves. For this purpose, the geometry of the spool throttling slots was designed by making precise cuts. Moreover, the parameters of the return springs were adjusted accordingly. The changes were introduced in such a way as to adjust the direction of the fluid stream and thus influence the balance of forces acting on the spool. Simulation tests were performed using the CFD method. In turn, laboratory experiments were carried out using the PONAR WREM10 valve with a prototype spool in two neutral position flow configurations: closed (E) and open (W). The results confirmed the valve's ability to maintain a quasi-constant flow rate in a wide pressure range. The maximum obtained non-uniformity in the flow rate for the fixed control signal in the whole studied pressure range, p = 5-30 MPa, was 6.3% except for the lowest current intensity, I=0.6 A, when it raised to 13.6%. Moreover, high consistency between simulation results and laboratory experiments was achieved. The difference in the obtained flow rate did not exceed 8-10% in the case of low current intensity values I=0.6-0.75 A, and it fell below 5% at higher ones.