Electric hydraulic actuators integrate electronic control with hydraulic power tightly. It plays a crucial role in applications such as remote valve control of oil and gas pipelines, automated systems on offshore platforms, and industrial assembly lines. This article will cover everything you want to know about electric hydraulic actuators.
What is an Electric Hydraulic Actuator？
The electric hydraulic actuator combines electric power with hydraulic drive. It integrates the motor, hydraulic unit, actuator and control system into an integrated unit.
Components of the Electric Hydraulic Actuator
Motor
The motor is the power source of the electric hydraulic actuator. It converts electrical energy into mechanical energy to drive the hydraulic pump directly. Modern advanced electric hydraulic actuators commonly use servo motors. It can precisely cooperate with the controller to achieve high-precision speed and torque control.
Hydraulic Unit
The hydraulic unit is mainly composed of hydraulic pumps, control valve groups, and necessary auxiliary components.
- The hydraulic pump converts mechanical energy into hydraulic energy. In electric hydraulic actuators, hydraulic gear pumpsand hydraulic piston pumps are commonly used.
The hydraulic gear pump uses the rotation of two or more meshing gears to push the hydraulic oil and generate pressure and flow. The structure is simple and compact. It is suitable for applications with medium pressure and flow. You can choose the bi-directional gear pump as the internal pump.
Hydraulic piston pumps are typically used in hydraulic systems that require higher pressure and more stable flow rates. Axial piston pumps are commonly employed in such systems. Compared to gear pumps, hydraulic piston pumps usually provide higher pressure, greater efficiency and more stable hydraulic output.
- A series of control valve groups also works in conjunction with hydraulic pumps. For example, direction control valvesare used to guide directions, relief valves to stabilize pressure, and flow control valves for regulating speed.
- In addition, auxiliary components such as the hydraulic tank, oil filter, and accumulator jointly ensure the clean and stable circulation of hydraulic oil.
Actuator
The pressurized hydraulic oil from the hydraulic pump is introduced into the actuator. For situations requiring linear pushing or pulling, hydraulic cylinders are usually employed. The piston or rod inside the cylinder produces linear motion under the push of high-pressure oil, thereby achieving linear output.
The hydraulic motor can generate continuous rotational motion and torque. It converts hydraulic energy into rotational motion through structures such as gears, blades or pistons.
Control and Feedback System
In order to achieve precise control and quickly respond to various commands such as switches, positioning, and speed, electric hydraulic actuators integrate precision control and feedback systems.
The control unit is responsible for receiving external electrical signal instructions and thereby driving the motor and hydraulic pump to operate. Meanwhile, the system monitors its operating status continuously through a series of sensors.
For example, there are position sensors used to detect the extension length of the piston rod, pressure sensors for monitoring system pressure, flow sensors for sensing the flow of oil, and temperature sensors for measuring oil temperature.
The control unit will compare the actual data fed back by the sensors with the preset target values in real time. Based on this comparison, the system will decide whether to start, stop, or adjust the flow rate and output of the hydraulic pump. This forms a precise closed-loop control. This ensures that the final output of the actuator can meet your set requirements stably and accurately.
How does an Electric Hydraulic Actuator Work?
After receiving external command signals, the control unit drives the motor to rotate at a specific speed and direction. The rotation of the motor directly drives the connected hydraulic pump and outputs controlled high-pressure oil.
The high pressure oil is precisely guided to the actuator through the hydraulic control valve group. For linear motion, pressure oil pushes the piston inside the hydraulic cylinder and causes its piston rod to extend or retract. For rotational motion, the shaft of the hydraulic motor is driven to rotate.
During this process, the system will continuously detect the current position or status of the actuator and compare it with the target value. When the deviation exceeds the set threshold, the controller will adjust the speed of the motor or the displacement of the hydraulic pump. Then, the flow rate of the output oil can be controlled to achieve smooth and precise adjustment of the actuator movement.
When the actuator reaches the target position, the system can enter an efficient energy-saving maintenance state. At this point, the control unit will issue instructions to shut down the hydraulic pump and motor, as well as the internal oil circuit valves of the system. The entire hydraulic circuit forms a closed system.
Under this closed condition, the hydraulic oil is completely sealed within the hydraulic cylinder and the system pipelines. The sealed oil has a strong static holding force, which can firmly lock the actuator in the current mechanical position.
This means that the system does not consume additional energy during the stationary phase and can remain in a stable position.
Types of Electric Hydraulic Actuators
Electric Hydraulic Linear Actuator
The linear electric hydraulic actuator is the most common type. It can produce linear motion and provide strong linear thrust or pull force. It drives hydraulic oil through a hydraulic pump, pushing the piston inside the hydraulic cylinder to make linear motion and generating the required thrust or traction force.
You can apply it to situations that require high thrust, large load, long stroke, or high load linear motion.
Rotary Electric Hydraulic Actuator
A rotary electric hydraulic actuator is also known as a torque electric hydraulic actuator. It is designed specifically for situations that require rotational motion, torque output, or angle adjustment, such as driving valves, rotating equipment, or various rotating mechanisms.
The rotary electric hydraulic actuator outputs rotational action or torque through a hydraulic motor. Or it can be achieved by using a hydraulic cylinder in conjunction with a crank and other conversion mechanisms to convert linear motion into rotational motion.
The Advantages of the Electric Hydraulic Actuator
High Positioning Accuracy
The electric hydraulic actuator can achieve very precise motion control and is suitable for applications where extremely high accuracy in position is required. With the help of precision sensors and closed-loop control circuits, the system can control deviations within a very small range.
It can perform actions with precision down to the micrometer level or even closer, meeting the requirements of your valve regulation, precise clamping and testing equipment.
Closed Loop Control
Modern electric hydraulic actuators integrate closed loop feedback and proportional control technologies. By sampling position, pressure, and flow signals in real time and adjusting the output dynamically, it achieves stable speed and torque control. This ability to adjust on demand enables the device to maintain stable performance at different operating points.
Intelligent Flow and Pressure Distribution
By using proportional valves, pressure compensation, the control system can allocate oil flow and pressure reasonably when the load changes, and maintain a stable output. This adaptive hydraulic distribution method allows you to achieve reliable and controlled motion performance even when dealing with complex or unbalanced loads.
Strong Output Capacity
Compared with electric actuators, electric hydraulic actuators are more likely to generate large thrust and high torque within the same volume. The electric hydraulic actuators can stably handle loads up to 4800 pounds. You can use it in scenarios where space is limited but tasks need to be overloaded.
Respond Promptly
The internal circuit of the electric hydraulic actuator is centralized, and the transmission path is shorter. With the addition of electronic control, it can adjust the output force and position within milliseconds or nearly in real time.
This fast response feature is suitable for automated sorting, dynamic suspension, or other systems that require rapid adjustment of force and displacement. It can achieve automatic adjustment and stable control under changing working conditions.
Easy Installation
The electric hydraulic actuator adopts a self-contained design. It integrates the core components such as the motor, pump, oil tank, actuator and control unit into one unit.
It does not need to rely on external hydraulic power sources or central pumping stations, and also eliminates a large number of oil pipe connections. This self-contained design is convenient for installation in remote, narrow space, or difficult to lay pipes.
Low Maintenance
The integrated structure of the electric hydraulic actuator reduces the number of pipes and connectors. At the same time, in combination with a reliable sealing unit, it can reduce the risk of oil leakage and maintenance requirements. This can help you reduce unplanned downtime losses and long-term maintenance costs.
Energy Conservation
In modern electric hydraulic actuators, the pump and motor only start to operate when action or power output is required. This avoids the traditional hydraulic system from continuously consuming power to maintain high-pressure operation.
Intelligentize
Modern electric hydraulic actuators have standardized electrical interfaces. It can easily connect with PLCs, automation control systems and the Industrial Internet of Things (IIoT) framework.
Through functions such as remote monitoring, real-time diagnosis, and predictive maintenance alerts, you can achieve full visualization management of the equipment’s operating status.
The Application of Electric Hydraulic Actuators
Industrial Valve Control
In the petroleum, natural gas, chemical and power industries, electric hydraulic actuators are suitable for controlling large ball valves, butterfly valves and regulating valves. Its output thrust is usually higher than that of electric actuators of the same specification.
At the same time, the integrated design reduces external hydraulic pipelines and minimizes the risk of leakage and installation complexity. You can install it in remote factory areas or dangerous zones, and it supports remote automated control.
Ships and Marine Engineering
In the environment of marine corrosion, salt spray, and continuous vibration, the reliability of equipment is being tested. The fully enclosed structure of the electric hydraulic actuator enhances its tolerance in harsh environments. Its compact structure can provide you with output torque suitable for servo, deck machinery, and hatch operations in a limited space.
Heavy Machinery
For cranes, excavators, and heavy handling equipment, electric hydraulic actuators can provide a large output force within a compact volume and can withstand the impact loads during system operation.
Automatic Production Line
During the stamping, mounting, forming or assembly processes, electric hydraulic actuators can provide programmable force and speed control. Its output is stable and suitable for work points that require repeated force application or precise position control. And the integrated design makes it easy for you to connect to the production line control system.
Aerospace
The development of electric hydraulic actuators initially originated from the demand for high power density and reliable drive solutions in aircraft. There are strict standards for the power density, reliability, and response speed of actuators in key systems such as flight control and landing gear.
The highly integrated design of electric hydraulic actuators reduces scattered hydraulic pipelines, which is beneficial for improving system response speed and control accuracy. At the same time, it reduces the potential risk of medium leakage.
Electric Hydraulic Actuators VS Hydraulic Actuators: A Simple Comparison
Structure
This is the most fundamental difference between these two types of actuators.
- The electric hydraulic actuator is a self-contained intelligent power unit. It integrates all the key components and packages them together, which makes it a complete system when it leaves the factory. When using it, you only need to connect the power supply and the signal cable to start working.
- The traditional hydraulic actuator itself is just a terminal, such as a hydraulic cylinder or a hydraulic motor. It requires the use of an external hydraulic power unitto provide the power.
Installation
- The electric hydraulic actuator is of an integrated design. It does not require an external hydraulic pump station or long-distance pipeline connections. You only need to fix the body and connect the power and signal lines during installation. This helps you significantly save installation space and time.
- The installation of traditional hydraulic actuators is relatively limited. You need to fix the external hydraulic power unit and lay the hydraulic pipelines. Its system has a large overall area and low flexibility in layout. It is more suitable for use in fixed and centralized places such as factory workshops.
Efficiency and Cost
- The electric hydraulic actuator operates in a demand-based energy supply mode. The internal motors and pumps only start when they are required to drive the load. During the process of maintaining position or in standby mode, it consumes almost no energy.
This mode can save up to 80% of energy compared to traditional continuous running hydraulic systems. It can significantly reduce your long term operating costs.
- The hydraulic actuator needs to be connected to an external power source. It requires continuous operation to maintain the system pressure. Even if no action is taken, it will still generate no-load energy consumption, pipeline pressure loss, and heat generation. The long term operating costs are relatively high.
Control Accuracy and Intelligent Potential
- The electric hydraulic actuator is essentially an electrically controlled device. It has a built-in controller that can directly receive digital instructions, making it easy to achieve high-precision closed-loop control of position and speed.
Through standardized industrial interfaces, it can be seamlessly integrated into your automation system or industrial Internet of Things. This helps you achieve remote monitoring, predictive maintenance and data analysis.
- The control accuracy and response speed of hydraulic actuators mainly depend on the external servo valve and the control system. Achieving the same level of precision control and digital integration typically requires more complex solutions.
Maintenance and Reliability
- The integrated design of electric hydraulic actuators significantly reduces leakage points. It also uses less hydraulic oil than traditional systems. This means you will have less maintenance work and a cleaner working environment.
- The reliability of the hydraulic actuator system depends on the integrity of the pipeline joints and seals. Leakage in the high-pressure piping and joints is a common fault. Its maintenance and troubleshooting require professional knowledge and skills in hydraulic systems.
FAQs
What should be Considered when Choosing an Electric Hydraulic Actuator?
The selection should match the actual requirements. You need to consider factors such as output thrust or torque, stroke, working voltage, types of control and feedback signals. These are the basis for determining whether the product is suitable for your working conditions.
Under what Environmental Conditions can the Electric Hydraulic Actuator Operate Reliably?
The design of electric hydraulic actuators takes into account the strictness of the operating environment. The typical operating temperature range covers from -40℃ to +70℃, and the protection level is usually IP65.
What are the Special Precautions for Installing the Electric Hydraulic Actuator?
Some models of electric hydraulic actuators are equipped with highly compressed springs for fault-safe reset. It is strictly prohibited to disassemble the actuator housing while the valve is under pressure, as this may cause components to fly off and pose a danger. When connecting, it is necessary to strictly follow the instructions in the manual.
How to Troubleshoot if the Electric Hydraulic Actuator does not Move at all after being Powered on?
First, you need to check whether the power supply is normal and make sure that the control signal has been delivered correctly. Then you can try using the manual operation mechanism provided by the device to test and determine whether it is a mechanical jam.
If all of the above are normal, it may indicate a fault with the internal motor or control module. We recommend that you contact a professional.
What Maintenance is Required for the Electric Hydraulic Actuator during its Daily Operation?
Due to the characteristics of integration and fewer pipelines, the maintenance of electric hydraulic actuators is relatively simple.
You need to check the appearance of the seal regularly and replenish or replace the internal hydraulic oil according to the operating duration. At the same time, conducting regular calibration of the routes and verification of the signals can ensure the accuracy of long-term operation.
Final Thoughts
Electric hydraulic actuators have demonstrated significant advantages in modern automation systems due to their high power density, compact structure, and precise control capabilities. We are well aware that the requirements of each project are different, so we provide customized services. Please feel free to contact us for product inquiries, technical support or to discuss customized solutions!
