Actuators are motors responsible for controlling or moving a system or mechanism. In order to operate, an actuator needs an energy source, which is usually hydraulic fluid pressure, electric current or pneumatic pressure, which works by converting energy into motion.
Applications for Actuators
Actuators are commonly used in engineering as a means of introducing motion. However, they can also be clamped onto an option in an effort to stop motion. There are several different applications for which actuators are used to include:
- Comb drive
- Hydraulic piston
- Electric motor
- Thermal bimorph
- Digital micromirror device
- Piezoelectric actuator
- Electroactive polymer
Three Commonly Used Types
A hydraulic actuator is comprised of a fluid motor or cylinder that to produce mechanical operation uses hydraulic power. The mechanical motion generated creates linear, oscillatory, or rotary motion. An actuator of this type has the ability to exert tremendous force because liquid is almost impossible to compress. However, for speed and acceleration there are some limitations.
Hydraulic actuators are also designed with a hollow cylindrical tube, making it possible for a piston to easily slide. When pressure is applied to just one side of the piston, it is called “single acting”. With this, the piston moves in just one direction and for the return stroke, a spring is often used. Pressure can also be applied to both sides, which is known as “double acting”. Pressure variance between the two sides is what causes piston motion on either side.
Pneumatic actuators are also commonly used. In this case, energy formed from high-pressure compressed air or vacuum is converted into rotary or linear motion. For main engine controls, this is the preferred choice because this actuator responds quickly in both starting and stopping since operation does not depend on reserved power.
With a pneumatic actuator, significant forces can be produced using slight pressure changes. Typically, the forces involve valves used to move diaphragms whereby the flow of liquid through the valve is affected.
For an electric actuator, a motor is used as power to convert electrical energy into mechanical torque. It is this energy that actuates equipment. Of all the different types, an electrical actuator is the most available and cost-efficient due to not using oil.