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Actuators

This is a PPT for Actuators

Soubhagya
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Actuators

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  1. 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

  2. Unmodulate Energy source Control signal Power Energy conversion amplification & modulation A Output Actuator

  3. Linear actuator: solenoid, Hydraulic/Pneumatic. Rotary actuator: motor, Hydraulic/Pneumatic.

  4. 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.

  5. Pneumatic valve. Car door openers. Hydraulic cylinder Single pressure line

  6. Hydraulic systems are used to control & transmit power. A pump driven by prime mover (electric motor) creates flow of fluid 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.

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

  8. Pneumatic actuator Pneumatic actuator It convert energy formed by compressed air at high pressure into ether linear or rotary motion. Quickly respond in operation.

  9. Hydraulic & pneumatic actuators: cylinders Hydraulic & pneumatic actuators: cylinders Double acting piston: Single acting: work can be done only in one direction Work is done in both directions Plunger Piston rod on both sides Piston Tandem Telescopic Telescopic 10

  10. Non cushioned cylinders are suitable for full stroke working at slow speed. Higher speeds with external cushions.

  11. Rotary hydraulic actuators 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° 12

  12. Mechanical linear actuators typically operate by conversion of rotary motion into linear motion. Screw Wheel and axle Cam

  13. 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

  14. 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

  15. 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).

  16.  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.

  17. Piezoelectric Stack Actuators Produce linear motion.

  18. 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.

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