Hydraulic Drives:
How to Combine Dynamics and Efficiency
Bert Brahmer, 2011-04-21
Hydraulic Drives: Dynamics and Efficiency
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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
Hydraulic Drives: Dynamics and Efficiency
1. Introduction
Speaker:
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Bert Brahmer, 1964

Engineering degree (Electronics)
R&D / µC Tools and Systems
R&D / automation hw / sw
R&D management
(hydraulics and electronics)
Member of Board of Management
(Voith Turbo H+L hydraulic)
Company:
Voith Turbo H+L Hydraulic
Employees: 180
Turnover: 50 M€ (approx.)
Member of VOITH Group:
Employees: 40.000
Turnover: 5.2 B€
Products:
- Internal gear pump
- Special valves and components
- Electronics
-> Complete hydraulic drive solutions
Markets:
Machine tools, energy, automotive
Hydraulic Drives: Dynamics and Efficiency
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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/s
Peak output: 132 kW
Peak input: 17 kW
Reaction time: 5 ms
Motor: external
Servo: Peak output: 132 kW
Peak input: 132 kW
Reaction time: 100 ms
Spindle: huge
Hydraulic Drives: Dynamics and Efficiency
3. Challenges for Hydraulics
CLDP: Integrated Drive
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Facts or hearsay about hydraulics:

Low efficiency

Extra space for power pack

Dirty (oil leakage)

Complex / non-linear control loops
No external motor
or power pack !
Challenges for hydraulic drive solutions:
HS4 hydraulic controller:

Clean systems – no leakage !

Integrated drives – no power pack !

Efficient systems – no energy wasting !

Simple control scheme or plug‘n play controllers !
Plug ´n play !
Hydraulic Drives: Dynamics and Efficiency
4. HPPC High Dynamic Punch System
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Requirements for punch press drive:

High speed = productivity

Compact – must fit into frame

Energy budget: 7,5 .. 17 KW

Accurate: 0.01 .. 0.05 mm
Hydraulic Drives: Dynamics and Efficiency
4. HPPC High Dynamic Punch System
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Key features to respond to challenges:

Compact drive unit, includes cylinder, valves.

Separate power pack

Dual pressure operation for high efficiency

Servo-hydraulics for high speed and accuracy

Dedicated controller HS4 with read to use firmware / PC software
Hydraulic Drives: Dynamics and Efficiency
4. HPPC High Dynamic Punch System
Hydraulic Schematic (simplified)

Dual-Pressure:
80 bar: high-speed nibbling
285 bar: high-load punching/forming
Automatic switchover

High precision servo valve

Valve direct drive by highly
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dynamic servo motor

Max. force: 330 kN

Max. speed: 0.8 m/s

Nibbling rate: > 1.500 h/min

Marking: > 3.500 h/min

Resolution: 0.01 mm

Rated power: 17 kW

Average consumption: 7..8 kW
(typical production mode)
Hydraulic Drives: Dynamics and Efficiency
4. HPPC High Dynamic Punch System
Evaluation of energy consumption
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Theoretical minimum energy
Energy for single pressure system
HPPC energy consumption:
Close to theoretical minimum !
Hydraulic Drives: Dynamics and Efficiency
5. PSH: Energy Efficient Drive for Servo Press
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Requirements for servo press:

Easy scaling: 500 kN ... 10.000 kN (50..1000 to)

Few components: easy installation, trouble shooting, retro fit

Accurate: 0.01 .. 0.05 mm

Full servo programmability of profile/speed

Energy efficiency – as always !
Hydraulic Drives: Dynamics and Efficiency
5. PSH: Energy Efficient Drive for Servo Press
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Key features to respond to challenges:

Operation purely by servo pumps – no directional valves

Separate pumps for down stroke / up stroke

Rapid feed using suction valve

Modular design: easy machine integration, even for retro-fit

Dedicated controller PCU with read to use firmware / PC software
Hydraulic Drives: Dynamics and Efficiency
5. PSH: Energy Efficient Drive for Servo Press
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Principle of PSH:
Mechanical equivalent:
Hydraulic Drives: Dynamics and Efficiency
5. PSH: Energy Efficient Drive for Servo Press
Aux. valves
Modular Design:
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A side pump
B side pump
Hydraulic Drives: Dynamics and Efficiency
5. PSH: Energy Efficient Drive for Servo Press
Why is PSH so power efficient ?
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Classical throttle control
Servo displacement control
Hydraulic Drives: Dynamics and Efficiency
6. CLDP: Compact and Efficient Linear Drives
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Solving the drive requirements´ equation:
Servo:
Hydraulics:

Plug ´n play

Energy efficiency

No hydraulics !
+
Easy scaling:
5 kN ...100 kN

Linear movement

Rugged against
wear and tear
=
?
Hydraulic Drives: Dynamics and Efficiency
6. CLDP: Compact and Efficient Linear Drives
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Key features to solve the equation:

Operation purely by servo pump – no directional valves

Closed Loop system – no tank, no directional valves

Compact design – no hydraulic connections

No hydraulic related electronics: servo interface plug ´n play

Rugged, „crash proof“ actuator
Hydraulic Drives: Dynamics and Efficiency
6. CLDP: Compact and Efficient Linear Drives
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Principle of CLDP:
Mechanical equivalent:
CLDP function is that
of a hydrostatic spindle.
Hydraulic Drives: Dynamics and Efficiency
6. CLDP: Compact and Efficient Linear Drives
Control loops:
„Classic“ servo
(electromechanical):
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CLDP: hybrid
servo / hydraulic:
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
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advantages like PSH !
Comparison: CLDP vs. Servo + gear/spindle
Servo + Gear/Spindle:
gear/spindle friction
CLDP:
pump efficiency (>95%), cylinder friction
Hydraulic Drives: Dynamics and Efficiency
6. CLDP: Compact and Efficient Linear Drives
Summary:
No hydraulics: purely electrical interface.
No hydraulics: no external hydraulic connections.
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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
Hydraulic Drives: Dynamics and Efficiency
7. Conclusion
Electromechanical (servo) drives are competing hydraulics in more and
more applications.
Servo drives are fashionable: clean, energy efficient, easy to use (?)
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Hydraulics have built-in advantages:
Suitable for high forces
Linear movement without gear / spindle
Rugged aggainst crash or wear and tear
Modern hydraulics can offer many user benefits:
Long lifetime – lower lifetime cost
Energy saving through application concepts:
-
Dual pressure systems
-
Servo pump application
Easy application and machine integration
Hydraulic Drives: Dynamics and Efficiency
7. Conclusion
Contact information:
Voith Germany:
R&D
Mr. Bert Brahmer
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Int‘l sales Mr. Bernd Schreiber
Bert.Brahmer(at)voith.com
Bernd.Schreiber(at)voith.com
Voith Taiwan:
Sales
Mr. Angus Lai
Angus.Lai(at)voith.com
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