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Dynamic Analysis of Single Pump, Flow Controlled Mobile Systems
Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.ORCID iD: 0000-0002-6371-1390
Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
2011 (English)In: The Twelfth Scandinavian International Conference on Fluid Power, SICFP'11: Volume 2 / [ed] Harri Sairiala & Kari T. Koskinen, 2011, 223-238 p.Conference paper, Published paper (Refereed)
Abstract [en]

Interest has increased in flow controlled systems in the field of mobile fluid power. The capital distinction between traditional load-sensing (LS) systems and flow controlled systems is that the pump is controlled based on the operator’s total flow demand rather than maintaining a certain pressure margin over the maximum load pressure. One of the main advantages of flow controlled systems is the absence of the feedback of the highest load pressure to the pump controller. In this paper, a dynamic analysis is performed where flow controlled and LS systems are compared. It is shown how instability can occur in LS systems due to the pump controller and proven that no such instability properties are present in flow controlled systems. A drawback with one type of flow controlled system is that the highest load dynamically will disturb the lighter loads. This paper shows a novel way to optimize the damping in such systems by controlling the opening position of the directional valve independently of the flow. The mentioned disturbance between the highest load to the others can thereby be reduced.

Place, publisher, year, edition, pages
2011. 223-238 p.
Keyword [en]
Flow control, load sensing, dynamic analysis, stability, damping
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-68636ISBN: 978-952-15-2519-3 (print)OAI: oai:DiVA.org:liu-68636DiVA: diva2:419024
Conference
The Twelfth Scandinavian International Conference on Fluid Power, SICFP'11, May 18-20, 2011 Tampere, Finland
Available from: 2011-05-25 Created: 2011-05-25 Last updated: 2015-09-07
In thesis
1. Fluid Power Systems for Mobile Applications: with a Focus on Energy Efficiency and Dynamic Characteristics
Open this publication in new window or tab >>Fluid Power Systems for Mobile Applications: with a Focus on Energy Efficiency and Dynamic Characteristics
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis studies an innovative working hydraulic system design for mobile applications. The purpose is to improve the energy efficiency and the dynamic characteristics compared to load sensing systems without increasing the complexity or adding additional components.

The system analysed in this thesis is referred to as flow control. The fundamental difference compared to load sensing systems is that the pump is controlled based on the operator’s command signals rather than feedback signals from the loads. This control approach enables higher energy efficiency since the pressure difference between pump and load is given by the system resistance rather than a prescribed pump pressure margin. High power savings are possible especially at medium flow rates.

Furthermore, load sensing systems suffer from poor dynamic characteristics since the pump is operated in a closed loop control mode. This might result in an oscillatory behaviour. Flow control systems have no stability issues attached to the load pressure feedback since there is none.

Pressure compensators are key components in flow control systems. This thesis addresses the flow matching problem which occurs when using conventional compensators in combination with a flow controlled pump. Flow sharing pressure compensators solve this problem since the pump flow will be distributed between all active functions. A novel control approach where the directional valve is controlled without affecting the cylinder velocity with the objective of optimizing the damping is proposed.

In this research, both theoretical studies and practical implementations demonstrate the capability of flow control systems. Experiments show a reduced pump pressure margin and energy saving possibilities in a short loading cycle for a wheel loader application.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2013. 59 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1595
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:liu:diva-92578 (URN)LIU-TEK-LIC-2013:29 (Local ID)978-91-7519-600-8 (ISBN)LIU-TEK-LIC-2013:29 (Archive number)LIU-TEK-LIC-2013:29 (OAI)
Presentation
2013-05-17, ACAS, A-huset, Campus Valla, Linköpings universitet, Linköping, 10:15 (Swedish)
Opponent
Supervisors
Available from: 2013-05-22 Created: 2013-05-13 Last updated: 2013-06-25Bibliographically approved
2. Mobile Working Hydraulic System Dynamics
Open this publication in new window or tab >>Mobile Working Hydraulic System Dynamics
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis deals with innovative working hydraulic systems for mobile machines. Flow control systems are studied as an alternative to load sensing. The fundamental difference is that the pump is controlled based on the operator’s command signals rather than feedback signals from the loads. This control approach enables higher energy efficiency and there is no load pressure feedback causing stability issues. Experimental results show a reduced pump pressure margin and energy saving potential for a wheel loader application.

The damping contribution from the inlet and outlet orifice in directional valves is studied. Design rules are developed and verified by experiments.

A novel system architecture is proposed where flow control, load sensing and open-centre are merged into a generalized system description. The proposed system is configurable and the operator can realize the characteristics of any of the standard systems without compromising energy efficiency. This can be done non-discretely on-the-fly. Experiments show that it is possible to avoid unnecessary energy losses while improving system response and increasing stability margins compared to load sensing. Static and dynamic differences between different control modes are also demonstrated experimentally.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2015. 85 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1697
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:liu:diva-121070 (URN)10.3384/diss.diva-121070 (DOI)978-91-7685-971-1 (ISBN)
Public defence
2015-10-02, A35, A-huset, Campus Valla, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2015-09-07 Created: 2015-09-04 Last updated: 2015-09-08Bibliographically approved

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Axin, MikaelEriksson, BjörnPalmberg, Jan-OveKrus, Petter

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