How does an Electro-Hydraulic Linear Actuator Work?

In previous articles, we’ve talked about the benefits of using an electro-hydraulic linear actuator compared with other actuation choices including roller screw and ball screw electro-mechanical actuators or traditional hydraulic cylinder actuators. But how do electro-hydraulic actuators actually work? We will explore that topic in this article.

Electro-hydraulic linear actuators are sometimes referred to as electro hydrostatic actuators. One of the earliest uses of this technology was on aircraft to transition from centralized hydraulic systems to “fly-by-wire” technology where control signals are connected electrically to standalone hydraulic actuators positioned at various locations on the aircraft.

Operating Concept

Kyntronics electro-hydraulic actuators aka electric hydraulic cylinders are either AC or DC powered.  They are a linear actuator with a totally sealed design that incorporates an integral cylinder driven by an attached motor and pump operating on a closed circuit using a small volume of fluid that is not exposed to the environment, preventing contamination. The fluid does not require replenishment or replacement.

Hydraulic fluid
Position Sensor

The linear motion produced by Kyntronics electro-hydraulic actuator is simple, the actuator extends the piston rod by the motor rotating the pump in one direction. Retracting the piston rod is accomplished by reversing the motor direction.  Kyntronics electrohydraulic actuators are often used to provide precise linear motion control. A position sensor or limit switches provide feedback to the actuator controller to determine when the actuator motor starts and stops and can be controlled to precisely move to programmable positions. An optional pressure transducer is used to measure the force exerted by the piston rod. This allows measurement and closed-loop control of the applied force.

Kyntronics electro-hydraulic actuator design provides unique benefits not available with other actuation technologies:

  • Significant energy savings using power-on-demand.
  • Low maintenance: with its totally sealed design, the actuator does not require fluid changes, or filter changes unlike hydraulic cylinders.
  • No metal-to-metal wear: does not require regular lubrication required by ball screw or roller screw type actuators.
  • The integral cylinder provides high tolerance for shock loads, side-loading and end stop crashes that cause damage and premature failure with ball screw and roller screw actuators.
  • A totally sealed design with no hoses avoids risk of leaks unlike traditional hydraulic cylinders.

Smart Linear Actuators that are Robust

Kyntronics electro-hydraulic linear actuators are a smart device providing precise control of the process and IoT connectivity through the actuator controller to meet the needs of smart manufacturing. In addition, these industrial actuators are robust handling high duty cycle applications in rugged environments.

Kyntronics actuators are available in a wide range of sizes:

  • Force Ratings: from <100 lbs. (0.4 kN) to 150,000 lbs. (667 kN)
  • Speed: up to 34.5 in/s (877 mm/s)
  • Stroke Length: any increment up to 120 in. (3,048 mm)
  • Input Power: 24 – 80 VDC or 120 – 480 VAC
Hydraulic fluidKyntronics electro-hydraulic actuator w/attached Control. 100 lbs. rated force.
Position SensorKyntronics electro-hydraulic actuators. 150,000 lbs. rated force

 

Find Solutions to Your Actuation Problems

Our engineers work closely with each customer to select the optimal actuation solution to address your unique application requirements. If you’d like to learn more about the actuation solutions Kyntronics has to offer, contact a member of our team today! We look forward to solving your actuation challenges.