Proportional flow control valve

摘要

A proportional flow control valve is disclosed in which an opening of a variable orifice formed by a proportion solenoid and a pilot spool is varied to vary a flow rate of fluid in a restriction passage by-passing a plunger of a main control portion connected to the variable orifice and hence a pressure difference across the plunger to thereby vary a position of the plunger. The pilot spool is inserted into a sleeve and has one end formed with a poppet portion which is able, with an aid of a spring, to contact with a valve seat formed in one end of the sleeve. The pilot spool is by-passed by a restriction passage and the poppet portion becomes in intimate contact with the valve seat when a force of the proportion solenoid in zero and the variable orifice is opened and connected through the poppet portion and the restriction passage to a drain when the pilot spool is moved by the force of the proportion solenoid.