Hydraulic Drives:How to Combine Dynamics and Efficiency

Bert Brahmer, 2011-04-21

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Hydraulic Drives: Dynamics and Efficiency

Contents

1. Introduction

2. Benefits of Hydraulics in Industrial Drives

3. Challenges for Hydraulics

4. HPPC: Highly Dynamic Drive for Punch Press

5. PSH: Energy Efficient Drive for Servo Press

6. CLDP: Compact and Efficient Linear Drive

7. Conclusion

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Hydraulic Drives: Dynamics and Efficiency

1. IntroductionSpeaker:

Bert Brahmer, 1964Company:

Voith Turbo H+L HydraulicEmployees: 180Turnover: 50 M€ (approx.)Member of VOITH Group:Employees: 40.000Turnover: 5.2 B€Products:- Internal gear pump- Special valves and components- Electronics

-> Complete hydraulic drive solutionsMarkets:Machine tools, energy, automotive

Engineering degree (Electronics)R&D / µC Tools and SystemsR&D / automation hw / swR&D management(hydraulics and electronics)Member of Board of Management(Voith Turbo H+L hydraulic)

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Hydraulic Drives: Dynamics and Efficiency

2. Benefits of Hydraulics in Industrial Drives

Rugged against external stress

Linear force without gear or spindle

Highly dynamic for high forces

Extreme power density at actuator

HPPC: 330 kN @ 0,4 m/sPeak output: 132 kWPeak input: 17 kWReaction time: 5 msMotor: external

Servo: Peak output: 132 kWPeak input: 132 kWReaction time: 100 msSpindle: huge

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CLDP: Integrated Drive

No external motor

or power pack !

Hydraulic Drives: Dynamics and Efficiency

3. Challenges for Hydraulics

Facts or hearsay about hydraulics:

Low efficiencyExtra space for power packDirty (oil leakage)Complex / non-linear control loops

Challenges for hydraulic drive solutions:

Clean systems – no leakage !Integrated drives – no power pack !Efficient systems – no energy wasting !

HS4 hydraulic controller:

Plug ´n play !

Simple control scheme or plug‘n play controllers !

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Hydraulic Drives: Dynamics and Efficiency

4. HPPC High Dynamic Punch System

Requirements for punch press drive:

High speed = productivityCompact – must fit into frameEnergy budget: 7,5 .. 17 KWAccurate: 0.01 .. 0.05 mm

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Hydraulic Drives: Dynamics and Efficiency

4. HPPC High Dynamic Punch System

Key features to respond to challenges:

Compact drive unit, includes cylinder, valves.Separate power packDual pressure operation for high efficiencyServo-hydraulics for high speed and accuracyDedicated controller HS4 with read to use firmware / PC software

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Hydraulic Drives: Dynamics and Efficiency

4. HPPC High Dynamic Punch SystemHydraulic Schematic (simplified)

Dual-Pressure:80 bar: high-speed nibbling

285 bar: high-load punching/formingAutomatic switchoverHigh precision servo valveValve direct drive by highlydynamic servo motorMax. force: 330 kNMax. speed: 0.8 m/sNibbling rate: > 1.500 h/minMarking: > 3.500 h/minResolution: 0.01 mmRated power: 17 kWAverage consumption: 7..8 kW(typical production mode)

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Hydraulic Drives: Dynamics and Efficiency

4. HPPC High Dynamic Punch SystemEvaluation of energy consumption

Theoretical minimum energy Energy for single pressure system

HPPC energy consumption:

Close to theoretical minimum !

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Hydraulic Drives: Dynamics and Efficiency

5. PSH: Energy Efficient Drive for Servo Press

Requirements for servo press:

Easy scaling: 500 kN ... 10.000 kN (50..1000 to)Few components: easy installation, trouble shooting, retro fitAccurate: 0.01 .. 0.05 mmFull servo programmability of profile/speedEnergy efficiency – as always !

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Hydraulic Drives: Dynamics and Efficiency

5. PSH: Energy Efficient Drive for Servo Press

Key features to respond to challenges:

Operation purely by servo pumps – no directional valvesSeparate pumps for down stroke / up strokeRapid feed using suction valveModular design: easy machine integration, even for retro-fitDedicated controller PCU with read to use firmware / PC software

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Hydraulic Drives: Dynamics and Efficiency

5. PSH: Energy Efficient Drive for Servo Press

Principle of PSH: Mechanical equivalent:

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Hydraulic Drives: Dynamics and Efficiency

5. PSH: Energy Efficient Drive for Servo Press

Modular Design:

A side pump B side pump

Aux. valves

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Hydraulic Drives: Dynamics and Efficiency

5. PSH: Energy Efficient Drive for Servo Press

Why is PSH so power efficient ?

Classical throttle control Servo displacement control

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Hydraulic Drives: Dynamics and Efficiency

6. CLDP: Compact and Efficient Linear DrivesSolving the drive requirements´ equation:

Servo:

Plug ´n playEnergy efficiencyNo hydraulics !

Hydraulics:

Easy scaling:5 kN ...100 kN

Linear movementRugged againstwear and tear

+ = ?

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Hydraulic Drives: Dynamics and Efficiency

6. CLDP: Compact and Efficient Linear Drives

Key features to solve the equation:

Operation purely by servo pump – no directional valvesClosed Loop system – no tank, no directional valvesCompact design – no hydraulic connectionsNo hydraulic related electronics: servo interface plug ´n playRugged, „crash proof“ actuator

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Hydraulic Drives: Dynamics and Efficiency

6. CLDP: Compact and Efficient Linear Drives

Principle of CLDP: Mechanical equivalent:

CLDP function is thatof a hydrostatic spindle.

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Hydraulic Drives: Dynamics and Efficiency

6. CLDP: Compact and Efficient Linear Drives

Control loops:„Classic“ servo(electromechanical):

CLDP: hybridservo / hydraulic:

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Hydraulic Drives: Dynamics and Efficiency

6. CLDP: Compact and Efficient Linear Drives

How about CLDP energy efficiency ?

Throttle control Displacement control

Hydraulically speaking, CLDP has the same advantages like PSH !

Servo + Gear/Spindle: gear/spindle frictionCLDP: pump efficiency (>95%), cylinder friction

Comparison: CLDP vs. Servo + gear/spindle

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Hydraulic Drives: Dynamics and Efficiency

6. CLDP: Compact and Efficient Linear Drives

Summary:

No hydraulics: purely electrical interface.

No hydraulics: no external hydraulic connections.

Modular design: can easily scale speed / force of actuator

Easy control: no hydraulic-specific hardware / software

Rugged against wear and tear

No spindle / gear for linear movement

Suitable for 5 kN..100kN, up to 1 m/s

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Hydraulic Drives: Dynamics and Efficiency

7. ConclusionElectromechanical (servo) drives are competing hydraulics in more and more applications.Servo drives are fashionable: clean, energy efficient, easy to use (?)

Hydraulics have built-in advantages:Suitable for high forcesLinear movement without gear / spindleRugged aggainst crash or wear and tear

Modern hydraulics can offer many user benefits:Long lifetime – lower lifetime costEnergy saving through application concepts:- Dual pressure systems- Servo pump applicationEasy application and machine integration

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Hydraulic Drives: Dynamics and Efficiency

7. ConclusionContact information:

Voith Germany:

R & D Mr. Bert Brahmer Bert.Brahmer(at)voith.com

Int‘l sales Mr. Bernd Schreiber Bernd.Schreiber(at)voith.com

Voith Taiwan:

Sales Mr. Angus Lai Angus.Lai(at)voith.com

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