Date post: | 21-Jan-2015 |
Category: |
Technology |
Upload: | jason-kefover |
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Hydraulic Motors
Brought to you by:
Demetri Preonas
Greg Unverferth
Overview of Lesson
• How they work
• Types of Motors
• Performance
• Applications
How a hydraulic motor works
• High pressure fluid is used to turn a shaft.
• This is done in many different ways.
• Much like a cylinder the power comes from the pressure acting over a large area and creating a large force.
Types of Hydraulic Motors
• Gear Motors
• Vane Motors
• Piston Motors
• Limited Rotation Actuator
Gear Motors
• External Gear Motor– 2 rotating gears, the
area of the gear teeth is where the pressure acts to create force
– Both gears turn simultaneously
– One gear is connected to the output shaft and the other is an idler.
Model 21300 “B1 Series” Gear MotorEaton® Heavy Duty Series 1 Variable Motor
Gear Motors
• Internal Gear Motors• Two categories
– Direct drive gerotor, works much like a rotary engine.
– Two gears, an inner and an outer.
– The pressure pushes them around a center point, turning a shaft
Vane Motors
• Spring loaded vanes are connected to a rotor
• The rotor turns inside a cam ring (elliptical hole)
• The vanes slide in and out of the slots in the rotor to make contact with the cam wall.
Piston Motors
• Many different types of piston motors
• All of them use the same basic principles
• Much like a cylinder, only turns a shaft like the cylinders in your car engine.
• Generally the most efficient
• High power, high speed, high pressure
Piston Motors
• Most efficient • Often used in
aerospace applications due to high power to weight ratio
In-line Piston Motors
• Simple construction• Low cost• Used in low torque
high speed applications, such as machine tools
Radial Piston Motors
• High Torque• Low speed• Possible application
could be a roller.
Bent Axis Piston Motor
• Is one example of variable displacement motor.
• The angle is altered to change the displacement.
Limited Rotation Actuator
• Also sometimes called a oscillator.
• Has limited movement • High torque
Performance
• Efficiency• Two factors• Internal leakage
– Volumetric efficiency and speed decrease due to leakage.
• Internal friction– Mechanical efficiency
loss due to torque loss
• Effv= (rpmact/rpmtheo) * 100
• Effv= volumetric efficiency
• Effm= (Tact/Ttheo) * 100
• Effm= Mechanical efficiency
• Effoa=(Effv/100)*(Effm/100)*100
• Effoa= Over All Efficiency
Performance
• The mechanical torque desired must be specified in order to find required working pressure.
• Pin= (T*2)/Disp.
• The rpm desired must be specified in order to find required flow rate.
• Q= (rpm * Disp.)/231
Power
• Hpout= (Tlb-ft * rpm)/5252
• Effoa= (Hpout * 100)/ Hpin
You just learned:
• How a hydraulic motor works
• The basics of the different types of motors
• Some possible applications for hydraulic motors
• How to calculate power
• How to find efficiency