May 29, 2024

Electro Hydraulic Servo Valves or EHSV play a crucial role in modern hydraulic systems

by controlling hydraulic flow precisely in response to an electric input signal. They are used in applications that require precise control of fluid power like industrial machines, aircraft systems and other advanced equipment.

Working of an EHSV

An EHSV works on the principle of converting an electrical signal into a hydraulic flow signal. It has a spool inside a bore which acts as a flow control element. When an electric current is passed through the solenoid coil surrounding the spool, a magnetic field is generated. This magnetic field exerts a force on the spool, displacing it from the center position. The displacement of the spool regulates the flow of hydraulic fluid passing through metering slots, thus achieving precise flow control. In a nutshell, an electric current command is converted into a hydraulic flow command through the displacement of the spool inside the EHSV.

Types of EHSVs
There are mainly two types of EHSVs based on their design and performance characteristics:

Proportional Valves: Proportional EHSVs provide a hydraulic flow that is directly proportional to the electric signal. They are used in applications requiring linear control such as hydraulic actuators for analog machine movements.

Switching Valves: Switching valves have only two positions – fully on or fully off. They are designed to provide an all-or-nothing flow and are used for switching high power hydraulic loads like hydraulic motors.

Within these types, valves can be further classified based on spool design, bore size, pressure rating etc. Dependening on application requirements, the right EHSV is selected.

Applications of EHSVs
Due to their precision control capabilities, EHSVs have widespread applications in industries:

Aerospace: EHSVs are extensively used in flight control actuators and landing gear systems of aircraft. Their high performance is crucial for safety.

Construction Equipment: Hydraulic systems of heavy earth moving equipment rely on EHSVs to precisely control attachments, angles and speeds.

Marine Vessels: EHSVs steer rudders, adjust stabilizers and control other shipboard hydraulic functions with precision.

Machine Tools: CNC machines, metal forming presses and other production machines use EHSVs for speed and motion control of mechanical movements.

Robots: The motion of robot joints and grippers is controlled through EHSVs to achieve intricate and repeatable movements.

Advantages of EHSVs
Compared to conventional hydraulic valves, EHSVs provide the following advantages:

– Higher Precision: EHSVs can control flow within 1-2% of commanded value, enabling precise position/motion control.

– Fast Response: Response time of EHSVs is less than 20 milliseconds, much faster than traditional valves.

– Programmable: Their electrical interface allows digital control through PLC/computers for flexible programming.

– Compact Size: Miniaturization of parts has made modern EHSVs very small for their performance.

– Reliability: When properly applied and maintained, EHSVs have long operational life exceeding 50,000 hours.

Future Trends in EHSVs
Research is ongoing to improve EHSV technology for emerging applications:

– New Materials: Use of specialized alloys and composites aims to reduce weight and improve durability.

– Integrated Designs: Multiple functional components are being integrated into a single compact package.

– Digital Valves: Advanced chips and software algorithms will further increase precision and controllability.

– Clean Designs: Efforts focus on minimizing internal leakage and frictional losses for energy efficiency.

– Wireless Models: Wireless interfaces may make EHSVs programmable via industrial networks without hard-wiring.

To summarize, EHSVs play a critical role in modern hydraulic systems by precisely controlling fluid power regulation, motion and mechanics. Their high performance capabilities have resulted in widespread usage across industries. Ongoing advancements aim at making EHSVs smarter, greener and more integrated for the futuristic applications.

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