How to adjust the speed of proportional solenoid valve?

The principle of proportional valve speed regulation is to control the main valve flow through the pilot valve. The most common way: the pilot valve spool is conical with position feedback coil, which is generally converted from mA signal to the corresponding driving distance of the pilot valve spool. When the conical valve core is in different positions, the clearance between it and the oil pipe is different, the flow rate changes, and the proportional valve also produces different speeds.