ABSTRACT
The proportional solenoid, incorporated in some rather complex cartridge valve designs, and partnered with microprocessor technology, provides tremendous control options for a fluid power circuit. Circuits can respond automatically to a range of external disturbances, thus freeing the operator to respond to true emergencies. In an industrial setting, automatic control often decreases cycle time, improves accuracy, and thus increases productivity with a subsequent increase in profit.
The proportional solenoid moves the armature in the valve. An increase in current to the coil increases the armature movement, which can open and close an orifice to set a pilot pressure, or it can change a spring setting. Valve operation is defined by the force balance for three forces, pressure, spring, and magnetic.
Most proportional valves are cartridge style. These cartridges mount in a manifold with passages machined to direct flow to ports where line (tubing or hose) connections are made.
