March 2, 2024

Electro Hydraulic Servo Valve – The Heart of Modern Precision Control Systems

Electro hydraulic servo valves are one of the most important and crucial components found in modern high precision control systems across many industries. These valves utilize electrical signals to control servo motors, hydraulic cylinders and other hydraulic actuators with extreme accuracy and precision.

Working Principle
An electro hydraulic servo valve works on the principle of proportional control of hydraulic fluid flow. It contains a small pool of hydraulic fluid connected to the output ports through metering slots. A spool at the center precisely controls the flow of fluid to the ports based on the input electrical command signal. An electrical coil placed around the spool applies force proportional to the input current to position the spool accurately. This controls the slots opening and flow of fluid, thereby controlling the motion of hydraulic actuators in precise manner.

Key Components
The main components of an electro hydraulic servo valve include:

– Solenoid coil: It is placed around the spool and applies force to position the spool based on the input electrical signal.

– Spool: It is a precision manufactured cylindrical part which slides inside the valve body to control fluid flow ports. Its accuracy is crucial for valve performance.

– Metering slots: Thin slots machined on the spool determine the amount of flow based on spool position. Finer slots enable higher precision.

– Valve body: It houses all internal components and has fluid inlet and outlet ports connected to actuators.

– Filter: It is installed at fluid inlet to remove any contamination from hydraulic fluid entering the valve.

– Feedback sensor: Some advanced valves contain position sensors to provide feedback about actual spool position.

Applications
Due to their high precision flow control capabilities, electro hydraulic servo valves find applications across many industries for motion and positioning control. Some key application areas include:

Flight Control Systems
Electro hydraulic actuators powered by servo valves are essential for primary and secondary flight control surfaces in aircraft like ailerons, elevators, rudders etc. They provide precise control required for safe flight.

Robotics
Robot joint movements, pick and place operations require accurate motion profileswhich are delivered by servo valves in robotics hydraulic systems.

Material Testing Machines
Servo valves drive hydraulic actuators of material testing machines used for tensile, compression, fatigue testing with PID closed loop force/displacement control.

Metal Forming Presses
Metal stamping presses, forging presses, extrusion presses use electro hydraulic actuation for precise die cushion control, forming force profiles.

Offshore Drilling Rigs
Many functions in offshore rigs like blow out preventer actuation, pipe handling are electohydraulically controlled through servo valves for reliability in harsh conditions.

Future Scope and Developments
With increased demand for precision in various industries, electro hydraulic servo valves market is expected to grow significantly in coming years. Some key technology trends include:

– Miniaturization: Developing micro and nano electro hydraulic valves for portable, medical applications.

– Digital valves: Fully digital design without mechanical parts for improved reliability in harsh environments.

– Proportional-integral-derivative control: Advanced PID algorithms to achieve superior closed loop performance.

– Feedback control: Integration of high resolution position/force sensors for true closed loop control.

– Multi-variable valves: Capability to control multiple hydraulic actuators independently with single valve.

– Integrated electronics: Integrating driver circuits and controllers directly onto the valve body.

electro hydraulic servo valves have become indispensable for high performance motion and force control applications across industries due to their precision flow control capability. With continuous technological advancements, the usage of these valves will further increase in various existing and emerging applications demanding highly accurate movements.

*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it