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The Dynamic Properties of a Poppet Type Hydraulic Flow Amplifier
Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems . Linköping University, The Institute of Technology.ORCID iD: 0000-0002-6371-1390
Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems . Linköping University, The Institute of Technology.
Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems . Linköping University, The Institute of Technology.
2007 (English)In: 10th Scandinavian International Conference on Fluid Power, SICFP´07 / [ed] J. Vilenius and K. T. Koskinen, Tampere, Finland: Tampere University of Technology , 2007, 161-178 p.Conference paper, Published paper (Refereed)
Abstract [en]

This paper examines the dynamic properties of a two-stage flow control valve of the "Valvistor" brand. There are several benefits to this: the valve ha a high closed loop bandwidth, the design allows big flow capacities etc. An attractive feature of this two-stage valve is that the pilot flow contributes to the total flow giving higher steady state flow efficiency. This paper presents an analythical model of this particular type of valve. A simplified model with relevant approximations is also presented. Measurements on the valve were made to validate the valve model. The paper also includes a further discussion about the pros and cons of the valve in open and closed loop applications.

Place, publisher, year, edition, pages
Tampere, Finland: Tampere University of Technology , 2007. 161-178 p.
Keyword [en]
Fluid power, Valvistor, dynamic model
National Category
Information Science
Identifiers
URN: urn:nbn:se:liu:diva-12538OAI: oai:DiVA.org:liu-12538DiVA: diva2:440
Conference
10th Scandinavian International Conference on Fluid Power, SICFP´07, 21st–23rd May, Tampere, Finland
Available from: 2008-09-12 Created: 2008-09-12 Last updated: 2015-08-31
In thesis
1. Control Strategy for Energy Efficient Fluid Power Actuators: Utilizing Individual Metering
Open this publication in new window or tab >>Control Strategy for Energy Efficient Fluid Power Actuators: Utilizing Individual Metering
2007 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents a solution enabling lower losses in hydraulic actuator systems. A mobile fluid power system often contains several different actuators supplied with a single load sensing pump. One of the main advantages is the need of only one system pump. This makes the fluid power system compact and cost-effective.

A hydraulic load often consists of two ports, e.g. motors and cylinders. Such loads have traditionally been controlled by a valve that controls these ports by one single control signal, namely the position of the spool in a control valve. In this kind of valve, the inlet (meter-in) and outlet (meter-out) orifices are mechanically connected. The mechanical connection makes the system robust and easy to control, at the same time as the system lacks flexibility. Some of the main drawbacks are

The fixed relation between the inlet and outlet orifices in most applications produce too much throttling at the outlet orifice under most operating conditions. This makes the system inefficient.

The flow directions are fixed for a given spool position; therefore, no energy recuperation and/or regeneration ability is available.

In this thesis a novel system idea enabling, for example, recuperation and regeneration is presented. Recuperation is when flow is taken from a tank, pressurized by external loads, and then fed back into the pump line. Regeneration is when either cylinder chambers (or motor ports) are connected to the pump line. Only one system pump is needed. Pressure compensated (load independent), bidirectional, poppet valves are proposed and utilized.

The novel system presented in this thesis needs only a position sensor on each compensator spool. This simple sensor is also suitable for identification of mode switches, e.g. between normal, differential and regenerative modes. Patent pending.

The balance of where to put the functionality (hardware and/or software) makes it possible to manoeuvre the system with maintained speed control in the case of sensor failure. The main reason is that the novel system does not need pressure transducers for flow determination. Some features of the novel system:

Mode switches The mode switches are accomplished without knowledge about the pressures in the system

Throttle losses With the new system approach, choice of control and measure signals, the throttle losses at the control valves are reduced

Smooth mode switches The system will switch to regenerative mode automatically in a smooth manner when possible

Use energy stored in the loads The load, e.g. a cylinder, is able to be used as a motor when possible, enabling the system to recuperate overrun loads

The system and its components are described together with the control algorithms that enable energy efficient operation. Measurements from a real application are also presented in the thesis.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2007. 60 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1341
Keyword
Fluid power, mode switch, energy efficient, independent metering, split spool, poppet
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:liu:diva-12540 (URN)LIU-TEK-LIC-2007:50 (Local ID)978-91-85895-06-9 (ISBN)LIU-TEK-LIC-2007:50 (Archive number)LIU-TEK-LIC-2007:50 (OAI)
Presentation
2007-12-20, A35, Hus A, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2008-09-12 Created: 2008-09-12 Last updated: 2015-08-31Bibliographically approved
2. Mobile Fluid Power Systems Design: with a Focus on Energy Efficiency
Open this publication in new window or tab >>Mobile Fluid Power Systems Design: with a Focus on Energy Efficiency
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This work deals with innovative energy efficient fluid power systems for mobile applications. The subjects taken up concern to what extent and how energy losses can be reduced in mobile working hydraulics systems. Various measures are available for increasing energy efficiency in these kinds of systems. Examples include:

Flow controlled systems The pump controller is switched from a load sensing toa displacement controlled one. The displacement is controlled in an open loopfashion directly from the operator’s demand signals. This reduces energy consumptionat the same time as dynamic issues that are attached to LS systemscan be avoided.

Individual metering valve systems Flexibility is increased by removing the mechanicalcoupling between the meter-in and meter-out orifices in directionalvalves. An overview of this kind of system is given in the thesis. A designproposal that has been implemented is also presented. Initial test results areshown. Patents for this particular system have been applied for.

Displacement control Metering losses are reduced by removing the directional valves.One pump is used for each load in such systems. This hardware layout involvesconsiderable changes compared to conventional systems. Displacementcontrolled systems are not studied in this work.

In mobile applications, overall efficiency is often poor and losses are substantial. The measures listed above can help improve this significantly in such applications. A flow dividing system can decrease energy consumption by about 10% and an individual metering system by about 20%. Losses in pump controlled systems are difficult to give a figure for; the losses are rather attached to the pumps and motors and not to the system layout. However, the losses for these systems are presumably even lower than for individual metering systems. The main focus in this work is on individual metering systems but questions about which components and so on are also treated. For example, the Valvistor valve concept has been studied as part of this work.

 

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2010. 77 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1339
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-61362 (URN)978-91-7393-304-9 (ISBN)
Public defence
2010-11-19, Planck, Fysikhuset, ing°ang 57, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2010-11-16 Created: 2010-11-16 Last updated: 2015-08-31Bibliographically approved

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