Rochester Institute of Technology
Load Application Analysis:Hydraulic Cylinders
October 5, 2013 1
Benefits: Load Accuracy Required Analysis (Incompressible Fluid)
Drawbacks: Safety Maintenance
From PRP and Markus’s Thesis: Up to 900lbs (4000N) applied force Up to 2000 rom shaft speed (33Hz) Journal to sleeve clearance: 35 to 95 microns Compressor Operating Rpm: 360rpm (Dr. Kolodziej)
Rochester Institute of Technology
Load Application Analysis:Hydraulic Cylinders
October 5, 2013 2
Parker Electro-Hydraulic Actuator (EHA) Hybrid combining benefits of hydraulic cylinder and electric servo Self-contained unit Speed and Load Range Size
Rochester Institute of Technology
Load Application Analysis:Hydraulic Cylinders
October 5, 2013 3
Calculations for Parker EHA (w/ Motor B and 0.327 gear): Distance for Piston to move (conservative):
95µm=0.00374"; 0.00374"*2=0.00748“ ≈ 0.01" (cushion)
Piston Speed from Graph ≈ 1.8in/s Cycle time:
(0.01in)/(1.8 in/s)*2(extend & retract)=0.011secs/cycle
Actuator Frequency:1/(0.011 secs/cycle)=
90 cycles/second = 90Hz
Rochester Institute of Technology
Load Application Analysis:Hydraulic Cylinders
October 5, 2013 4
0 50 100 150 200 250 300 350 400-8000
-6000
-4000
-2000
0
2000
4000
6000
8000
10000
Load History for Main Crank Bearing
Force XForce Y
Crank Angle (degrees)
Forc
e (N
)
Rochester Institute of Technology
Load Application Analysis:Hydraulic Cylinders
October 5, 2013 5
Shaft Operating RPM 360RPM
Shaft Cycle Time 0.1667s
Shaft Frequency 6Hz
EHA Piston Velocity 1.8 in/s
EHA Piston Displacement 0.01 in
EHA Displacement Time 0.0056s
EHA Cycle Time 0.0111s
EHA Frequency 90Hz
EHA X-Direction Force Cycles 2cycles/rotation
EHA X-Direction Force Frequency 12Hz
EHA Y-Direction Force Cycles 4cycles/rotation
EHA Y-Direction Force Frequency 24Hz
Challenges:• Are EHA’s load input based or displacement input based?• Response time to inputs• Piston Velocity varies with load• Extension load, as opposed to retract (Additional actuator(s)?){$$$}
