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Vanderbilt University

A Linkage Driven Variable

Displacement Pump

Shawn Wilhelm, Post-doctoral Associate

University of Minnesota

Advisor: James Van de Ven

Industry/University Engagement Summit

June 6 – 8, 2016

photo

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Hydraulic Systems are

Inefficient• Low Efficiency of Fluid

Power Flow Control

– 50% Industrial

– 20% Mobile

• $20B wasted annually

• 150 MMT of CO2

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Axial Piston

Bent Axis

Losses In Existing Pumps

Do Not Scale

• Port plates lead to

high constant

leakage rates at a

given pressure

independent of

speed

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Variable Displacement

Mechanism

• Vary the stroke of a piston with no other

sliding joints

• Eliminate Port Plate

Pouliot, H. N., Delameter, W. R., and Robinson, C. W., 1977, "A Variable Displacment Spark-Ignition Engine," No. 770114, SAE International.

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Advantage of Linkage Pump

• High efficiency at low displacement

• Losses scale with displacement

1800rpm

5000 psi

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Linkage Concept

Input

Crank

Slider Link

Axis of

Slide

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Linkage Concept

Input

Crank

Slider Link

Axis of

Slide

Connecting Rod

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Linkage Concept

Input

Crank

Slider Link

Axis of

Slide

Connecting Rod

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Input

Crank

Slider Link

Axis of

Slide

Connecting Rod

Rocker

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Linkage Concept

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Input

Crank

Slider Link

Axis of

Slide

Connecting Rod

RockerAdjustable

Ground Pivot

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Linkage Concept

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Input

Crank

Coupler

Connecting RodSlider Link

Axis of

Slide

Adjustable

Ground PivotRocker

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Linkage Concept

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Input

Crank

Coupler

Slider Link

TDC

Adjustable

Ground Pivot

12

Linkage Concept

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Input

Crank

Coupler

Rocker

Connecting RodSlider Link

Adjustable

Ground Pivot

Axis of

Slide

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Linkage Concept

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Linkage Pump Prototypes

5 Years of Prototype Development

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Pumping Mechanism

Linkage

Adjustable

Ground

Piston Crosshead

Bearing

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Linkage In Motion

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First Prototype Pump

500 psi, 180rpm, 8.75cc/rev

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Model Agrees with Experiment

Displacement (%)Crank Angle (rad)

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Second Generation Prototype

• Three cylinder

• 21MPa (3000 psi)

• 5kW

• 30Hz operating

speed

• Bearings in joints

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Renderingkj

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Prototype is Smooth & Quiet

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Pump Model: Pressure/Flow

Dynamics

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Experimental Results

10 Hz Operation

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Third Generation Pump

3500 psi, 1800 rpm, 11.5cc/rev, Multi-Fluid

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New Pump Mechanism

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Radial Cam Adjustable Linkage Pump

Same Benefits as Crankshaft:

• Constant Top Dead Center

• True Zero Displacement

• High Efficiency Joints

• Insignificant Leakage

Added Benefits:

• Control Ripple with Cam Profile

• Multi-Lobe

• Compact, Stiff, Lightweight

• Cam Drives Link, Not Piston

– Low Piston Side Load

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Cam Pump First Gen Prototype

Five Cylinder, 3 Lobe 66cc/rev 5000psi

80-120 RPM

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Efficiency Curves

• Even at low speed

operation, high

efficiencies are

achieved

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Double Shear Design

Complete

• Displacement

– 0-15cc/rev

• RPM

– Nominal 280 rpm

– Max 550 rpm

• Pressure

– Max 350 Bar

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Current Activities

• Creating a startup to bring the pump to

market

• Targeting low speed applications where

efficiency is key.

• Looking for funding sources

• Applying for June SBIR Solicitation

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How can industry help?

• The goal is commercialization

• Flexible to many methods of doing so

• Looking for industry assistance,

partnership, or direct licensure

• Trying to development a model for

commercialization of academic research in

the fluid power industry

– How might you envision this?

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Thank You