R-DDV® Servovalve

The Woodward HRT R-DDV® servovalve is a unique, high performance and rugged servovalve. A revolutionary design approach incorporates an electronically controlled, permanent magnet brushless dc motor to drive a single stage spool valve. This innovation results in superior reliability and outstanding servo performance at a price comparable to traditional servovalve designs. The R-DDV® servovalve has been proven in thousands of hydraulic and pneumatic applications.

How It Works
In simplest terms, a limited angle brushless dc torque motor drives a valve spool directly through an "eccentric" built into the motor shaft. Rotary motion of the motor shaft results in motion of the spool, which in turn modulates fluid flow through the valve control ports.

R-DDV® servovalve incorporates an integrated electronic controller with sophisticated control algorithm, which is packaged into the motor enclosure. The controller compares the electronically monitored spool position with the input command signal. The resulting error signal is amplified to produce a current, which drives the motor to the commanded position. The signal is electronically enhanced to give optimum valve performance: hysteresis, linearity and internal leakage are minimized while dynamic performance and stability are optimized.

The R-DDV® servovalves are single stage devices. There are no fluid amplifiers or first stage pilot valves. Therefore, R-DDV® servovalves operate independent of supply pressure -- and there are no orifice assemblies, nozzles, jets or filters which are subject to contamination, wear or maintenance. Robust design features ensure excellent tolerance of pressure spikes as well as mechanical shock and vibration.

The reliability inherent in the R-DDV® servovalve design is evident from the consistent, trouble-free operation in many critical and demanding industrial applications.

Specifications
Four hydraulic models are available. Review the specification information at this web site, then contact your local distributor or Woodward HRT at 888-659-4229 to review your specific application.