Title: FLUID POWER
1FLUID POWER!
2TODAY
- Learn some fluid power basics
- Some possibilities for your FIRST robot
- Hands-on project with pneumatic components
3What is fluid power?
- Uses
- Heavy equipment
- Construction industry
- Off-road vehicles
- Manufacturing
4WHY FLUID POWER?
STRONG!
LIGHT!
EASY!
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17Fluid Power is Unique Unparalleled torque,
power and bandwidth for the same weight or
volume. Example Power/Weight (kW/kg) Pneumatic
Motor 0.3-0.4 Hydraulic Motor 0.5-1.0 Electric
Motor 0.03-0.1 Fluid power weight advantage
101 Reference I. L. Krivts and G. V. Krejnin,
Pneumatic Actuating Systems for Automatic
Equipment, Taylor and Francis, 2006.
18CENTER FOR COMPACT AND EFFICIENT FLUID POWER
- 100 mpg automobile
- Efficient off-road equipment
- Compact and portable
19CCEFP testbeds
TB1 Excavator
TB2 Injection molding machine
Existing FP applications
TB3 small Urban Vehicle (sUV)
TB5 FP assisted hand tools
FP enabled breakthroughs in transportation
TB4 Compact Rescue Crawler
TB6 FP assisted orthoses prostheses
Reduced or delayed funding
New industries applications
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22Pneumatics compared to hydraulics
- No problems of a spills
- Compressibility stores energy
- Available for your use
- Dangerous if excessivevolumes or pressures
- Difficult to control precisely
- Fluid is readily available
- Should be filtered, dry
- Usually lower forces
Safety Must Always Be Considered!
23Pressure of an ideal Gas
- Pressure of a gas is due to the force of gas
molecules bouncing off the walls. - Pressure increases when molecules are moving
faster, heavier, or if there are more molecules. - Molecules move faster when they are hot.
- mR depends on molecule.
Pressure P
24Getting Work out of Air
- Work is force acting over a distance, ft-lbs.
- Put air in a container under pressure
- Allow part of the container to expand
- The expanding part does work
25How much energy is in a tank filled with
compressed air?
26How much energy is in a small air tank?
- Tank Volume 150 ml or 9.154 in3
- Pressure 413,700 Pa or 60 psi (over Patm)
- Patm 101,325 Pa or 14.7 psi
Answer Energy PV ln(P/Patm) 0.15 x
515025 x ln(74.7/14.7) 125 kJ
Challenge question How high could the instructor
be lifted using the energy in one tank?
27How much energy in your tankcan you use?
- Line lossesPressure drop proportional to flow
- Throttling lossesPressure drop proportional to
flow squared - Cylinder frictionCoulomb plus viscous friction,
depends on seals
28Force available
- Pressure x Area Force
- Area pi x Bore2 / 4
- For example cylinder
- Bore 10 mm .394 in. ? Area .122 in2
- Force PxA 60 psi x .122 in2 7 lbs
Pressure P
Area AP
Force F
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30The Effect of Different Areas
Pressure P
Area AR
Area AP
Pressure P
Force F
How much force F is necessary to hold the rod
still?
Pressure Patmosphere
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38Pneumatic components seen in the FIRST Robotics
competition
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48LET'S BUILD!
49Full Circuit
CYLINDER
CYLINDER
RELIEFVALVE
PGAUGE
VALVE
PUMP
VALVE
TANK
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