US Patent 8418723 Electromagnetic proportional flow rate control valve

An electromagnetic proportional flow rate control valve capable of performing precise flow rate control in a low flow rate side of an operating region is provided. In an electromagnetic proportional flow rate control valve 32, in which a valve member 2 is driven in a valve closing direction in accordance with the increase in a driving current I of a solenoid coil 15, a solenoid driving force F is set such that it decreases accompanying the displacement of the valve member 2 in the valve closing direction with respect to an identical driving current in the solenoid coil 15. Thus, an amount of change in an area of a valve opening with respect to unit changes in the driving current I becomes smaller in a region at which the stroke is small compared to a case of having flat characteristics, whereby the flow rate control precision in the low flow rate region can be improved.