From Editor

Richard Oberem

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Robert Rahmfeld

In this work a new displacement controlled linear actuator technology for mobile machines and robots working hydraulics based on single rod cylinder is investigated. The new actuator concept uses a constant low pressure source for the compensation of the difference between the in and outgoing flow of the cylinder chambers. Two simple pilot operated check valves make sure that the cylinder low pressure side is always connected to the pressurized low pressure line. Great advantages according to the component expenditure are obtained with this new actuator concept, especially when several linear drives with differential cylinder are coupled on the low pressure side. Furthermore, the coupling with other hydraulic drives e.g. rotary drives working as hydrostatic transmission simplifies the system once more compared to today’s valve controlled working hydraulics systems.
This new displacement controlled linear actuator type can work in open and closed control loop and allows a complex automatic machine motion control. Robust position and velocity control strategies based on LQG/LTR method are described. Furthermore, a quasi integrator prevents effects like integrator limit cycles or wind-up. Due to the use of one final control element (servo pump) for one actuator, decoupled actuators on the high pressure side and a nearly load independent system behaviour, it could be shown that this actuator type is easier to control as valve controlled actuators.
Measurement results with today’s standard closed circuit servo pumps and standard control hardware prove the functionality of this actuator. The energy saving potential of the new actuator type mainly due to recovery of load and brake energy is analyzed with the help of typical working cycles. In fact, the recovered energy part needs not to be cooled as in valve controlled systems what can reduce the component expenditure for the machine system additionally. For analyzing of the thermal behaviour a mathematical simulation model is developed and investigated for these working cycles, and by this, the potential of this actuator type for mobile machine working hydraulics is indicated once more.

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Awards in 2002/2003

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Principles of Hydraulic System Design

by P. J. Chapple

First Edition 2003, 250 pages
Publisher: Coxmoor Publishing Co. in association with BFPA
ISBN: 1901892158

The book contains 250 pages of the latest information concerning the basic types of components and their operational principles, explains the way in which circuits can be arranged using available components to provide a range of functional outputs, and details the analytical methods that are used in system design and performance prediction.
 

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Industrial Servo Control Systems: Fundamentals and Applications (Fluid Power and Control)

by G. W. Younkin, T. L. Albu

384 pages
Publisher: Marcel Dekker
ISBN: 0824708369

This reference details hardware specifications and drive classifications related to the operation of machine service drives. It also outlines troubleshooting methods for problems concerning machine non-linearities, inertia, drive stiffness, and friction. Particular attention is given to recently developed simulation methods used to predict, assess, and improve the performance of service systems and their components. Case studies illustrate key topics.
 

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Einführung in die Ölhydraulik

by H. J. Matthies

Fourth Edition 2003, 271 pages
Publisher: Teubner
ISBN: 3-519-36318-6
 

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Oil Hydraulic Systems : Principles and Maintenance

Edited by S. R. Majumdar

548 pages
Publisher: McGraw-Hill Professional
ISBN: 0071406697

Install, operate, and maintain hydraulic equipment as efficiently and cost-efficiently as possible. Here in a single definitive vol-ume is everything you need to understand the fundamental operating principles of as well as the latest maintenance, repair, and re-conditioning techniques for industrial oil hydraulic systems.
Written by an expert with more than twenty-five years' teaching experience, this comprehensive resource provides clearly writ-ten, authoritative coverage of:

• System design principles
• The basic components of hydraulic systems, including pipes, pumps, strainers, oil reservoir filters, pressure gauges, relief valves, and gear boxes
• Compatibility issues
• Methods to reduce heat generation and dissipation to optimize thermal stability
• Operational and constructional features of fluid power components, illustrated via sketches and circuit diagrams
• Maintenance and troubleshooting techniques
• Seals and packing

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