MOOG 631 Series Electrohydraulic Servo valve

MOOG 631 Series Electrohydraulic Servo valve

G631 SERIES SERVOVALVES

The G631 Series flow control servovalves are throttle valves for 3- and preferably 4-way applications.They are a medium performance, two-stage design that covers the range of rated flows from 1.0 to 20 gpm at 1,000 psi valve drop.The output stage is a closed center, four-way sliding spool.The pilot stage is a symmetrical doublenozzle and flapper, driven by a double air gap, dry torque motor. Mechanical feedback of the spool position is provided by a cantilever spring.The valve design is simple and rugged for dependable, long life operation.These valves are suitable for electrohydraulic position, speed, pressure or force control systems with high dynamic response requirements.

VALVE FEATURES

➣ 2-stage design with dry torque motor 

➣ Low friction double nozzle pilot stage 

➣ High spool driving forces 

➣ ISO 4401 port pattern for 4-ports (external pilot supply is not per ISO 4401 location)

➣ Rugged, long-life design 

➣ High resolution, low hysteresis 

➣ Completely set-up at the factory 

➣ Field configurable fifth port for separate pilot supply 

➣ Field replaceable first stage disc filter

Key Features

Structure and design:

Dry torque motor and two-stage hydraulic amplifier structure: this design ensures high accuracy and fast response of the servo valve.

The pilot stage is a low friction double nozzle flapper valve: the low friction design improves the sensitivity and service life of the valve.

High spool actuation force: capable of meeting a variety of demanding application scenarios.

Rugged design: ensures long-term stable operation under harsh working conditions.

Performance parameters:

Rated flow rate under rated pressure drop: under 7Mpa rated pressure drop, the rated flow rate is from 5L/min to 75L/min, which meets the applications with different flow rate requirements.

High resolution and low hysteresis: improves the precision and stability of servo control.

High dynamic response: suitable for servo control system of position, speed, force (or pressure), able to respond quickly to changes in the control signal.

Installation and Maintenance:

Mounting dimensions comply with ISO4401 (but external oil control ports do not): easy integration with standard systems.

Optional fifth port for independent pilot valve control: provides additional control flexibility and application scenarios.

Pilot valve disc oil filter is field replaceable: simplifies maintenance and reduces maintenance costs.

Principle of operation:

Inputting a current command signal to the torque motor coil generates an electromagnetic force acting on both ends of the armature, which deflects the baffle in the spring tube.

The deflection of the baffle plate reduces the flow rate of a certain nozzle, which in turn changes the pressure on the side of the spool connected to this nozzle and pushes the spool to move to one side.

The spool's displacement also creates a force on the spring-loaded rod, creating a restoring torque on the armature baffle assembly. When the restoring torque is balanced by the electromagnetic force, the stopper returns to zero position and the slide spool remains in the open position until the given input signal changes.

Application Areas

MOOG 631 Series Electrohydraulic Servo Valve is widely used in fields requiring high precision and high response speed servo control, such as:

Control systems for civil aircraft cockpits

Hydraulic control systems for power generation fans

Hydraulic drive systems for Formula 1 racing cars

Precision flow control for medical infusion systems

Servo control systems for industrial automation