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Vanderbilt University
Project 16ST1:
Variable AC Hydraulic Pump/Motor
Jim Van de Ven, University of Minnesota
Eric Barth, Vanderbilt University
Kim Stelson, University of Minnesota
Doug Adams, Vanderbilt University
Industry/University Engagement Summit
June 6 – 8, 2016
photo
What is AC Hydraulics?
Transmission of Power with
Pressure Waves
Classification:
• Standing Wave
George Constantinesco, 1913
• Alternating Flow
2
What is an AC Hydraulic Pump?
• Vary Displacement via Piston Phase
to Load
Piston
A
Piston
B
Phase Shift, Φ = π
Fractional Displacement
1
0.8
0.6
0.4
0.2
0
0
pi/4
pi/2
3pi/4
pi
Phase Shift,  (radians)
6
Multiple Cylinders via Radial
Architecture
7
Benefits of AC Hydraulic Pump
• Highly Efficient Architecture
– No port or swash plate
• High Pressure Capabilities
• Infinitely Variable
Source: http://www.harken.com
Source: http://http://www.boschrexroth.com/
8
Good Potential for
Displacement Control
• Mount Multiple Pumps on Common Shaft
– Axially Short
– Through Shaft
Source: http://http://www.boschrexroth.com/
9
Cam Provides
Flexibility
• Tunable Displacement
Profile
• Multi-Lobe Cam
Fraction of Maximum Flow Rate
– Displacement Density
– Balance Axle Forces
– Small Case Rotation
1
0.8
0.6





0.4
0.2
0
0
pi/2
pi
3pi/2
Crankshaft Angle (rad)
=0
= /4
= /2
= 3/4
=
2pi
10
Research Plan
Tasks:
1. Develop dynamic pump model
–
6 months
Focus on AC hydraulics dynamics
2. Parameter study
3. Design prototype pump
–
Time (months)
3 months
4 months
Utilize off-the-shelf components
4. Fabricate pump and characterize
–
Efficiency map
5. Design for motoring
6. Demonstrate displacement control
–
4 months
6 months
3 months
Single actuator
11
Support Requested from
Industry
• Feedback on Concept & Approach
• Component Donations:
– Radial Pumps
– Disc Check Valves
12
Major
Objectives/Deliverables
AC Hydraulic Pump/Motor
•
•
Research goal:
Model, design, and develop AC hydraulic
pump for the application of displacement
control.
Alignment with CCEFP’s research strategy:
Design of a pump that is efficient across a
wide range of operating conditions and is
compact.
•
Original contribution of the project: Applying
alternating flow AC hydraulics to create a
variable displacement pump/motor
•
Competing research: Multiple variable
displacement pump architectures exist. The
AC pump is highly efficient and axially short,
making it a good fit for multi-actuator
displacement control.
•
•
•
•
•
•
•
Construct dynamic pump model [month 6]
Conduct parameter study [month 9]
Detail design of prototype pump [month 13]
Prototype pump operational [month 15]
Experimental testing of pump efficiency and flow
ripple [month 17]
Design for motor operation (active valves)
[month 21]
Demonstrate displacement control [month 24]
Next Steps
•
In the next six months a dynamic model
will be constructed and used to explore
the influence of parameters on pump
performance and guide prototype design.
•
Industry contribution: Seeking donation
of radial piston pumps and check valves
13