Proportional pressure control valve is an Electro-hydraulic proportionate relief valve designed to regulate the pressure in a hydraulic system, proportional valve is an improvement over the conventional solenoid valve since it can help achieve unlimited number of positions with-in its over all working range, unlike the solenoid valve. In proportional valve the solenoid current can be varied to make the spool move through variable distances. The valve spool moves in proportion to the electrical signal applied.

The proportional pressure control valve incorporates two stages, viz. the pilot stage and the main stage. The pilot stage is small electronically controlled valve while the main stage is a regular relief or reducing valve suitably designed for obtaining the required flow rate. The initial input signal, which controls the proportional solenoid valve, has low power source. In order to operate the spool of the proportional valve. The power is increased to the required level by means of an amplifier, which produces a larger current flow.

The proportional pressure control valves manufactured and marketed by HITECH HYDRAULICS PVT. LTD. is poppet type. It has a poppet and seat design. In this valve the stroke of the proportional solenoid is electronically controlled. An input signal causes the solenoid’s armature to push against spring (proportionate to the input signal). Spring exerts force on the poppet, which in turn determines the setting of the valve pressure. Apart from controlling the position of the spool, the proportional valve can also control the spool speed. Consequently it can control the speed, acceleration or deceleration of the final element, say a cylinder. To achieve this capability a gradually increasing or decreasing signal (a ramp function) is fed to the control amplifier with improved output current. Separate adjustments for ramp increase and decrease are provided and can be set in the range of its working.

Proportional pressure control valve is quite versatile yet simple in design, maintainability and cheaper in cost, as compared to servo valves, minor changes in its electronics card can ensure multiple control applications.