Actuators Flashcards
(50 cards)
What are the three main sources of energy for actuators?
- Hydraulic (Pressurized Liquid)
- Pneumatic (Compressed Gas)
- Electrical
What is the term we can use to group Hydraulic and Pneumatic actuators?
Fluid Power Systems
What are the two types of Actuators motion?
- Linear - Generating a Translation or Applying a Force
- Rotary - Inducing a Rotation or Applying a Torque
What are the main characteristics we need to consider when characterising fluid power actuators?
- Bore - Cylinder Diameter
- Stroke - How far they can move
What is a common pressure operation range for hydraulic power?
Why is this?
0-6 bar because you will begin to experience leakages at higher pressures
What are the advantages and disadvantages of a hydraulic system?
Advantages:
* We can operate at high pressures (200 bar)
* Hydraulic actuators are stiff due to the fluids incompressibility
* Easy to control in position and speed
Disadvantages:
* Noisy
* High Friction
* Thermal effect (non-linear)
* “Messy” - Leakages of oil and fluids can occur at high pressure, which is why it’s uncommon for useage in the food industry
What are the two main differences between a hydraulic actuator and a pneumatic actuator?
- The fluid for a pneumatic is compressible because we are using gases compared to water
- In the industrial context, we don’t need to have a specific location where we reject the gases used since they are already cleanly in the atmosphere
What are the advantages and disadvantages of a pneumatic system?
Advantages:
* Quick (Fast answer)
* Excellent power to weight ratio
* No return lines needed
* Simple design and control (cheap)
* Fireproof
* Shock absorbant
Disadvantages
* Low working pressure: 5-10 bar
* Difficult to control in position or speed (due to the compressibility of the gas)
* Variation of the pressure due to temperature (PV=nRT)
* Delay (Dependent on the length of the tubing)
What is a pump used for and what type of system is it involved in?
Pumps are used to generate a flow of fluid
They are featured within a hydraulic system
What is a compressor used for and what type of system is it involved in?
Compressors are used to pressurize a gas
They are featured within a pneumatic system
What colours are the arrows for Pneumatic and Hydraulic Systems in a Fluid Power Diagram?
White arrows are used for Pneumatic systems
Black arrows are used for Hydraulic systems
What does a filter do?
Remove debris from the system
What does a lubricator do?
Reduce the friction in the system using a liquid, which is why they aren’t often used in a pneumatic system
What does an air dryer do?
Remove moisture from the air
What does a pressure regulator do?
They maintain a constant pressure in the system. They can do this before or after the system
What is a FRL Unit?
Filter Regulator Lubricator Unit
How do we collect multiple components into one in a fluid power diagram?
We draw a dotted line around the system to collapse it into a subsystem
What are valves used for?
- Change flow direction
- Change flow rate
- Change fluid pressure
What are the types of Spool Valve Actuators?
- Button
- Lever
- Solenoid
What are the 4 things DCV (Directional Control Valves) symbols show?
- The number of ports and the number of switching positions (Inlets and outlets ports are shown by lines)
- The flow path and arrows in the direction of flow
- The shutoff positions indicated by lines drawn at right angles (T)
- The actuation and return actuation method
What is the neutral resting positions of x/2 and x/3 DCV’s when x can be any number?
x/2 = Right
x/3 = Middle
What electrical component is similar to the functionality of a check valve?
Diode
How does a check valve work?
There is a ball that can be pushed to allow flow, but only in one direction. In one way, the ball will be pushed over the valve so no flow can pass, whereas in the other direction, the ball will be pushed out of the way, which will allow flow to pass
What type of logic gate is a shuttle valve similar to?
OR
