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Optimized Damping in Cylinder Drives Using the Meter-out Orifice: Design and Experimental Verification
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.
Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
2012 (English)In: 8th International Fluid Power Conference Dresden: "Fluid Power Drives!", 2012, Vol. 1, 579-591 p.Conference paper, Oral presentation only (Other academic)
Abstract [en]

This paper analyses the damping of a flow controlled cylinder with a mass load and an outlet orifice. By using linear models, a mathematical expression for the damping is derived. It is shown that the volumes on each side of the piston have a high impact on the damping. In case of a small volume on the inlet side, the damping becomes low. However, the most important thing is to design the outlet orifice area properly. There exists an optimal orifice dimension; both smaller and larger orifice areas give low damping independently of the size of the volumes. In this paper a design is proposed of the outlet orifice area that optimizes the damping of the system. Experimental results which confirm the theoretical expectations are also presented. The conclusions are that without an outlet orifice, the hydraulic system will not contribute with any damping at all. Furthermore, large dead volumes in the cylinder will increase the damping, but at the expense of the system’s efficiency.

Place, publisher, year, edition, pages
2012. Vol. 1, 579-591 p.
Keyword [en]
Damping, compensator, outlet orifice, efficiency
National Category
Mechanical Engineering
Identifiers
URN: urn:nbn:se:liu:diva-76878OAI: oai:DiVA.org:liu-76878DiVA: diva2:517270
Conference
8th International Fluid Power Conference, March 26 - 28, 2012, Dresden
Available from: 2012-04-23 Created: 2012-04-23 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, MikaelPalmberg, Jan-OveKrus, Petter

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