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FLUID POWER!. SEE SPLASH 2008 FOLDER. TODAY. Learn some fluid power basics Hands-on project with pneumatic components Some possibilities for your FIRST robot. What is fluid power?. Uses : Heavy equipment Construction industry Off-road vehicles Manufacturing. WHY FLUID POWER?.
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FLUID POWER! SEE SPLASH 2008 FOLDER
TODAY • Learn some fluid power basics • Hands-on project with pneumatic components • Some possibilities for your FIRST robot
What is fluid power? • Uses: • Heavy equipment • Construction industry • Off-road vehicles • Manufacturing
WHY FLUID POWER? STRONG! LIGHT! EASY!
Fluid 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 = 10:1 Reference: I. L. Krivts and G. V. Krejnin, Pneumatic Actuating Systems for Automatic Equipment, Taylor and Francis, 2006.
CENTER FOR COMPACT AND EFFICIENT FLUID POWER • 100 mpg automobile • Efficient off-road equipment • Compact and portable
CCEFP 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
Master Pneumatic National Tube Supply Company Ralph Rivera HIGH COUNTRY TEK Member of the Schaeffler Group
Pneumatics 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!
Pressure 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
Getting 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
Assume constant temperature: Energy: P = pressure in tank (absolute) V = volume of tank Patm= atmospheric pressure = 101,325 Pa or 14.7 psi How much energy is in a tank filled with compressed air?
How 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?
How much energy in your tankcan you use? • Line losses:Pressure drop proportional to flow • Throttling losses:Pressure drop proportional to flow squared • Cylinder friction:Coulomb plus viscous friction, depends on seals
Force 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
The 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