Competitively priced hydraulic proportional control valves feature a patented Voice Coil Drive technology and offer exceptionally fast response times, with precise flow, speed and pressure control.Parker Hannifin, the leading global manufacturer and supplier of motion and control technology, has launched a new generation of hydraulic proportional control valves. Called the DFplus series, the new valves feature Parker's patented Voice Coil Drive (VCD) technology and have been developed to offer exceptionally fast response times, with precise flow, speed and pressure control, yet at a extremely competitive cost. Typical applications include machine tools, injection and blow moulding equipment, and process, power generation and marine systems.
To date, manufacturers and end users of hydraulics systems have generally used either electro-hydraulically operated, torque motor servo valves, or electro-mechanically operated solenoid valves, to control the flow and applied pressure of the hydraulic media.
Although these devices can be effective in many applications they are rarely an ideal solution, as servo-valves tend to be expensive, while electro-mechanical valves offer only limited performance, especially in terms of force displacement characteristics.
By comparison, the new DFplus valve uses Parker's unique VCD technology, with sophisticated electronics, to actuate and control the movement of the valve spool.
This system produces extremely fast response times, of less than 3.5ms for the CETOP 3 valve, exceptional resolution, low hysteresis of under 0.05% and high flow rates, which enable smaller valves than normal to be used in most applications; for example, the CETOP 3 version of the DPplus provides the same flow rates as a conventional CETOP 5 valve.
VCD technology is similar to that used for loudspeakers to produce extremely high frequencies, with a current-carrying coil being moved over a permanent magnetic cylinder.
The coil is wound onto a bearer, which is directly connected to the spool in such a way that transverse forces that would normally affect the spool coil or bearing points are eliminated; the exact position of the spool is monitored by an integrated displacement measuring system, combined with the electronics package.
Unlike conventional valve technology, this construction produces true linearity between the current applied and the force output and can give an operating force for the CETOP 3 valve of up to 100N.
This can be applied equally in both directions, simply by reversing the polarity of the coil, and is around 200% greater than that available from standard dual stroke solenoids.
The latest DFplus is suitable for use with all industry standard plant and process control systems and is currently available in CETOP sizes three and five.