Electromechanical Actuators
Electromechanical actuators are devices that provide mechanical force through the conversion of electrical power. Becoming increasingly popular for industrial applications, electromechanical actuators offer several advantages over traditional hydraulic and mechanical linear actuators, such as increased mechanical efficiency, compactness, ruggedness, high load capacity, a minimum number of parts, and easy assembly. Additional benefits of electromechanical actuators include decreased energy consumption, long service lives, and increased power density.
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Applications of Electromechanical Actuators
Industries that utilize electromechanical actuators include:
- Military
- For armored ground vehicles and aircrafts.
- Medical
- For medical infusion systems, medical bed positioners, dental chairs, and additional medical and dental equipment.
- Aerospace
- To open and close cargo doors, move flight surfaces, stabilize rotating devices, and other movement control applications.
- Agriculture
- For use in tractor engines, cultivators, and additional farming machinery and applications.
Electromechanical Actuator Design and Function
Electromechanical actuators may differ in terms of what materials they are constructed from; such as metals like aluminum, steel, and zinc, as well as having plastic parts at times for noise reduction purposes. The power source could include DC, AC, stepper, and servo motors, and screw types may be lead or ball screws. Electromechanical actuators have a fairly simple design: they consist of an electric motor, a screw, a nut, and possibly gears. The electric motor, also referred to as the driver, is mechanically connected to a screw. Thus, when the motor rotates, the screw will also rotate. A nut is threaded onto the screw through matching helical threads onto a non-rotating part of the screw; as a result, the nut is prevented from rotating along with the screw. Instead of rotating, the nut will be driven along the threads of the screw in a linear movement in the corresponding direction to the screw’s rotational movement. As a result, it is through the nut’s movement that the electrical energy is converted into usable mechanical energy.
In terms of electromechanical actuators that utilize gear sets, the general purpose is for use in smaller motors. Not only smaller, but weaker as well, these motors spin at a high rpm. They must be geared down to provide the necessary torque required to spin the screw in applications in which the load would be too heavy for the motor to handle without additional support. Typical gears used for this application include worm gears, which are industrial gears that have a curved and recessed throat, or planetary gears, which consist of three or more outer gears that revolve around one central gear.