Digital Interface Valve

Series D941 Digital Interface Valve with Integrated Microprocessor and Fieldbus Communications

Here is the new digital servovalve that we have been writing about in the stories above. Moog has developed this new Digital Interface Valve hydraulic valve platform, with microprocessor based electronics and a CANopen fieldbus. It is truly a "game-changer" because it brings the capabilities of the electromechanical world to the high-force applications that have traditionally been the province of hydraulics.

This servo-proportional valve can be used in large, complex machines, like the Metso Super Calender paper making machine, that call for large numbers of axes and high volumes of wiring. Series D941 is offered in flow capacities of up to 80lpm (21.1 gpm) at pressures to 5 bar (75 psi).

These new valves can replace analog technology and offer configurable functions that enable customers to define the dynamic behavior of the valve and adapt its characteristics to particular application requirements, while providing high-precision digital flow and pressure control. These valves are central to implementing a distributed control concept in a machine because tasks can be assigned to local devices rather than the main control device, providing our customer's machines with increased flexibility and functionality.

The ability to bring digital control to such high flow capacities is critical, because it enable users, for the first time, to configure these valves through software, rather than through changes in mechanical parts or through passive electronic components. It simply makes life easier for users as you do not have to stock a lot of custom valves and, in many cases, it means that we don't need to send an engineer to tune the valve.

Key benefits of Digital Interface Valve products for customers are:

  • CANBus Communication: Diagnostic capabilities, integrated monitoring of key environmental and internal characteristics, and valve parameter modifications can be accessed on-site or remotely.
  • Flexibility: The ability to download parameters via the fieldbus connection or directly from the upper PLC program enables optimum tuning of valve parameters during the machine cycle, even while the machine is operating. The Windows®-based graphical user interface is easy to learn and convenient to use.
  • Cost Savings: Since the pressure control loop is tunable via software, rather than passive electronic components, it is now possible to stock a single valve for multiple applications reducing the need for several valve models.
  • Lower Installation Costs: A serial wiring scheme reduces the amount of wiring and improves noise immunity.
  • Superior Control: The improved frequency response of the design allows high spool position loop gain, providing excellent static and dynamic response for superior control system performance. The improved valve dynamic performance is due to the extremely high natural frequency of the ServoJet® pilot stage (500 Hz) and the implementation of advanced current control algorithms, which are only possible via digital electronics.
  • Energy Savings: Considerably improved flow recovery (more than 90% of the pilot stage internal leakage flow) contributes to energy savings, especially for machines with multiple valves.
  • Reliability: The high-pressure recovery of the ServoJet pilot stage (more than 80% delta p at 100% command signal) provides higher spool driving forces and ensures enhanced spool position repeatability.
  • Safety: Fail-safe versions with defined safe spool position using a spring, a poppet valve or by external supply cut off ensure operator safety.

This product continues Moog's technological leadership by extending the implementation of digital intelligence across our product lines that results in improved performance, cost, and ease of use for our customers.

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