Presentation on Actuators

What is an actuator? Actuators are devices used to produce action or motion. Input(mainly electrical signal , air, fluids) Electrical signal can be low power or high power. Actuators output can be position or rate i. e. linear displacement or velocity. Actuation can be from few microns to few meters

Actuator functional diagram Unmodulate Energy source A Power amplification & modulation Control signal Energy conversion Output Actuator

Hydraulic actuator. Pneumatic actuator. Mechanical actuator. Types of actuators: Hydraulic actuator. Pneumatic actuator. Mechanical actuator. Electrical actuator Linear actuator: solenoid, Hydraulic/Pneumatic. Rotary actuator: motor, Hydraulic/Pneumatic.

Solenoid: A solenoid is a coil wound into a tightly packed helix. In physics, the term solenoid refers to a long, thin loop of wire, and wrapped around a metallic core. which produces a magnetic field when an electric current is passed through it.

Solenoids controlled valves Application Pneumatic valve. Car door openers. Solenoids controlled valves Hydraulic cylinder Single pressure line

Types of hydraulic actuator Hydraulic systems are used to control & transmit power. A pump driven by prime mover (electric motor) creates flow of fluid Types of hydraulic actuator Linear actuator (hydraulic cylinder)- Provides motion in straight line. Linear displacement depends on stroke length. Usually referred to as cylinders, rams (single acting cylinders) or jacks. Rotary actuators (Hydraulic motors)- Produces continuous rotational motion. Pump shaft is rotated to generate flow. A motor shaft is caused to rotate by fluid being forced into the driving chambers.

Applications Semi rotary actuators- Produces non-continuous rotational motion. Limited to less than one revolution (<360°). Used to produce oscillatory motions in mechanisms. Applications Hydraulic jack. Hydraulic brake. Hydraulic ram. Used as sensor. Close loop velocity controlling. Highly precise positioning for heavy loads.

Pneumatic actuator CONSTRUCTIONAL FEATURES OF CYLINDER It convert energy formed by compressed air at high pressure into ether linear or rotary motion. Quickly respond in operation. CONSTRUCTIONAL FEATURES OF CYLINDER

Hydraulic & pneumatic actuators: cylinders Single acting: work can be done only in one direction Double acting piston: Work is done in both directions Plunger Piston rod on both sides Piston Tandem Telescopic Telescopic

Double acting cylinder with & without cushioning Non cushioned cylinders are suitable for full stroke working at slow speed. Higher speeds with external cushions.

Rotary hydraulic actuators Vane rotary actuator: Parallel piston rotary actuator Limited angle in both directions. Maximum angle always smaller than 360° The same torque in both directions. Limited angle rotary actuator Limited angle rotary actuator Piston rotary actuator: With rack and gear coupling. Here maximum angle may be larger than 360°

Mechanical actuator Types of mechanics Mechanical linear actuators typically operate by conversion of rotary motion into linear motion. Types of mechanics Screw Wheel and axle Cam

Electrical actuator Electrically actuated system are very widely used in control system Working Principle of motor Every motor works on the principle that when a current-carrying conductor is placed in a magnetic field, it experiences a mechanical force. There are three types of motor used in control system D.C. motor A.C. motor Stepper motor

A.C. motor Stepper motor A stepper motor is an electromechanical device which converts electrical pulses into discrete mechanical movements. Permanent magnet type Variable reluctance type Hybrid type

Piezoelectric actuators Pierre and Jacques Curie discovered the piezoelectric effect in 1880. The application of an electric field to a piezoelectric crystal leads to a physical deformation of the crystal. Piezoelectric materials are: Quartz, Ceramics, PZT(lead zirconate titanade). Advantages short response time. An ability to create high forces. A high efficiency and a high mechanical durability. Disadvantage Have small strains. (0.1-.2%) High supply voltage needed.(60-1000V) Large hysteresis.(actuator doesn’t go back to exactly where it started).

Configuration A piezo ceramic crystal is coated with silver on both sides. Glued to a brass, nickel alloy, or stainless steel disk. Brass: Commercial & industrial use.(not subjected to environment ) Nickel alloy: Use where it subjected to environment. Stainless steel: Uses where it subjected to solvent, corrosive chemical, Underwater . Medical fields.

Types of piezoelectric actuators Piezoelectric Stack Actuators Produce linear motion. Linear motor Piezoelectric bender actuator

Other type of actuator Heaters - used with temperature sensors And temperature controller to control the temperature in automated moulding Equipment and in soldering operation. Lights - Lights are used on almost all machines to indicate the machine state and provide feedback to the operator. LED LCD’s Gas plasma display CRT Sirens/Horns - Sirens or horns can be useful for unattended or dangerous machines to make conditions well known.