An Electro-Hydraulic Servo Valve or EHSV is an electrically operated valve that controls how hydraulic fluid is ported to an actuator. Servo valves and Servo-Proportional Valves are electro-hydraulic operate by transforming a changing analogue or digital input signal into a smooth set of movement in a hydraulic cylinder. Servo valves can provide precise control of position, velocity, pressure and force with good post movement damping characteristics.

Control

A low voltage is used to control the servo valve. The control voltage is passed into an amplifier which provides the power to alter the valve's position. The valve will then deliver a measured amount of fluid power to an actuator. The use of a feedback transducer on the actuator returns an electrical signal to the amplifier to condition the strength of the voltage to the servo valve.[1]

Moog servo valves

File:Deformable blow molding die.jpg
The twin Moog servo valves are used to deform the shape of the die on this blow molding accessory designed by BMC Limited

Many of the servo valves in use today are manufactured by Moog Inc. A typical example of a servo valve is the Moog servo valve D631 series. An example of servo valve use is in blow molding where the servo valve controls the wall thickness of extruded plastic making up the bottle or container by use of a deformable die.[2]

References

  1. Description of a Servo valve
  2. Deformable die fitted with Moog servo valves


pl:Serwozawór elektrohydrauliczny