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Fluid Power Introduction

• Video: – Fluid Power: A Force for Change

Class #1Introductions & Fluid Power Fundamentals

ME 8243: TOPICS IN DESIGN:ADVANCED FLUID POWER

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Professor: Jim Van de Ven• Research in Energy Conversion & Storage

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Active Learning

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Source: https://learningsciences.utexas.edu

• Pre-Class: Knowledge transfer via readings & videos• In-Class: Guided engagement in the material • Lab: Apply and extend the content

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Goal: Move to Higher Levels of Learning

Course Goal: Enable students to construct dynamic models of hydraulic components and systems and use those models to design the components and systems to achieve specific objectives.

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Class Agenda

• Introductions• Design Process Applied to Fluid Power

– Design Process– Building Blocks– Examples

• Syllabus• Simple Modeling Exercise• Course Goals

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Peer Introductions

• Name Cards

• Meet Neighbor – Groups of 2– Name– Where they are from– Research interests / thesis project

• Introduce Neighbor to the Class

NAME

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Design Process Applied to Fluid Power Components/Systems

Problem Definition

Background Research

Goal Statement

Task Specifications

Concept Development Analysis

Solution Selection

Detailed Design

Prototyping, Testing,

Validation

Production

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Problem Definition

Background Research

Goal Statement

Task Specifications

Concept Development

Analysis Solution Selection

Detailed Design

Prototyping, Testing,

ValidationProduction

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Course Focus: Model Driven Design of Fluid Power Components/Systems

Building Blocks: (knowledge/skills needed for model driven design of FP systems)

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Fluid Power Modeling Examples

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Phase-Shift Variable Displacement Pump

Piston 1Piston 2 (phase adjusting)

Combined Waveform

Piston Stroke

14FPMC2017

Phase-Shift Variable Displacement Pump ModelA Dynamic Model using first principles captures • Piston kinematics and dynamics• Cylinder pressure• Flows between pairs of cylinders• Net inlet and outlet flowsas functions of the pump’s phase shift angle.

The model also captures• Hydraulic check valve dynamics• The effective bulk modulus• Leakage flows• Viscous friction• Input motor torque

Input: Downstream Pressure, Motor Speed, Phase Shift AngleOutput: Cylinder Pressure, Flowrates*, Energy*.

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• The model captures piston kinematics and cylinder pressure as functions of the pump’s phase shift angle.

• The model captures flows between pairs of cylinders as functions of the pump’s phase shift angle

𝑄

𝑃 , 𝑃 ,𝑅, 𝐼

𝑃 , 𝑃 , ∆𝑃 ∆𝑃

⟹ 𝑄1𝐼 𝑃 , 𝑃 , ∆𝑃

• The model also captures check valve dynamics†

† Knutson, A. L., Van de Ven, J. D. (2016). Modelling and experimental validation of the displacement of a check valve in a hydraulic piston pump. International Journal of Fluid Power, 17(2), 114-124.

• The model also captures input motor torque• The model also considers(1). Leakage

(2). Viscous friction

(3). Effective bulk modulus

Phase-Shift Variable Displacement Pump Model

16FPMC2017

Phase-Shift Variable Displacement Pump Model

17FPMC2017

AFH VDP Prototype 1

(1) CAT®Pump1, (2) CAT®Pump2, (3) Connecting Pipes, (4) Cylinder Pressure Transducers, (5) Inlet Pressure Transducer, (6) Outlet Pressure Transducer, (7).Outlet Flow Rate Transducer, (8) Hydraulic Motor Emulating A Prime Mover, (9) Torque Transducer, (10) Rotary Encoder.

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Linear Electromagnetic Piston Pump

PistonS

S N

N

N S

N S

X

X

LP Manifold

HP Manifold

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Coupled Model Construction• Goal: computationally inexpensive

with reasonable accuracy• Assumptions:

– Square-wave electrical current input– Quasi-steady state linear actuator

performance– Instantaneous check valve transitions– Constant tank and rail pressure

Evaluate Magnetic Equivalent Circuit

Calculate Actuator Force vs Displacement

Solve Pump Model to Steady State

Calculate Power Density and Efficiency

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Actuator Model• Magnetic Equivalent Circuit (MEC)

– Model actuator as reluctance network for flow of magnetic flux– Calculate the force and inductance vs actuator displacement– Significantly less computationally expensive than FEA

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Actuator Model• Magnetic Equivalent Circuit (MEC)

– Model actuator as reluctance network for flow of magnetic flux– Calculate the force and inductance vs actuator displacement– Significantly less computationally expensive than FEA

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Coupled Model Construction

S

S N

N

N S

N S

X

X

𝑃

𝑃

𝑃 𝑃

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Coupled Model Construction

S

S N

N

N S

N S

X

X

𝑃

𝑃

𝑃 𝑃𝑚𝑥

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Coupled Model Construction

S

S N

N

N S

N S

X

X

𝑃

𝑃

𝑃 𝑃

𝐹

𝑚𝑥

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Coupled Model Construction

S

S N

N

N S

N S

X

X

𝑃

𝑃

𝑃 𝑃

𝐹

𝑚𝑥 𝐹 𝐹𝐹

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Virtually Variable Displacement Pump Circuit

Transitional Throttling Energy Loss: ~ 60%

H. Tu and M. Rannow et. al. “High Speed Rotary Pulse Width Modulated On/Off Valve,” Proceedings of the 2007 ASME-IMECE, Paper No. IMECE2007-42559.

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Soft Switch Concept

Rannow, M.B., and Li, P.Y., 2009, “Soft Switching Approach to Reducing Transition Losses in an On/Off Hydraulic Valve,” Proc. Dynamical Systems and Controls Conference, ASME.

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Illustrating Soft Switch Operation

Animation Control

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Modeling Dynamics & Energy Losses• Pressure Dynamics

– Switched Volume– Back of Soft Switch

• Spring-Mass-Damper Dynamics– Soft Switch Piston– Check Valves

• Flow Resistances• Leakage

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Syllabus & Course Website

• www.me.umn.edu/courses/me8243• Site will be continually updated

• schedule and topics will change without notice

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Syllabus Highlights• Textbook• Homework• Project• Late Work & Re-grades• Course Outline (Major Topics):

– Introduction to Fluid Power 1 week– Basics of Simulation 1 week– Fundamentals of Fluid Power 2 weeks– Operation and Modeling of Components 4 weeks– Operation and Modeling of Systems, Including Emerging Technologies

6 weeks

• Office Hours: Thurs 2:15-3:00pm or by appointment

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Model driven design of a simple system

1. Circuit Diagram2. Component Sizing3. Power Requirement4. Reservoir Sizing5. Cycle Efficiency