A New Elastic Non Contacting Sealing Concept for Valves

Authors

  • Scherrer Matthias Institute for Machine Design and Hydraulic Drives, Johannes Kepler University, Linz, Austria
  • Scheidl Rudolf Institute for Machine Design and Hydraulic Drives, Johannes Kepler University, Linz, Austria
  • Luckachev Evgeny Institute for Machine Design and Hydraulic Drives, Johannes Kepler University, Linz, Austria

DOI:

https://doi.org/10.13052/ijfp1439-9776.2339

Keywords:

Digital hydraulic cylinder drives, exoskeleton, new sealing concept, elastic sealing

Abstract

The hydraulic binary counter concept was proposed as a means to realize compact and lightweight digital hydraulic cylinder drives for exoskeleton actuation. This counter principle is based on hydraulically actuated switching valves which have a hysteretic response with respect to the pilot pressure. Manufacturing tolerances of the tiny components caused unexpected high leakage which, in turn, led to a malfunction of the system.

In this paper a new sealing concept, is introduced to solve this problem. It is based on a non-contact seal (sealing gap), which exploits a self-regulating, elasto-hydrodynamic effect to reduce a rather large initial gap h0 – to allow a rough tolerance – into a very small sealing gap h(x) to avoid dry friction of valve spool movement on the one hand but have very small leakage on the other hand.

As sealing, an annular flexible ring made, e.g. of PTFE, is used which combines sufficient flexibility to allow this self adapting mechanism to a sufficient extent and to stay the high pressure loads.

For the mathematical analysis of the concept, an approximate elasto-hydrodynamic analytical model is used. It sets the gap pressure, obtained from the Reynold’s equation for the sealing gap, the elastic restoring forces of the sealing ring, and the imparting pressure in equilibrium.

The sealing concept is then simulated with a numerical model built with the finite element code ABAQUS, this results are compared with the one of the analytical model.

It solves the Reynolds equation by a user defined subroutine. The simulation results indicate that this sealing principle delivers way better results than standard gap seals despite its rough manufacturing tolerances with one order of magnitude higher tolerance ranges. The application of this concept is not limited to small valves as needed for exoskeleton hydraulics but can be transferred to conventional type of hydraulics as well.

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Author Biographies

Scherrer Matthias, Institute for Machine Design and Hydraulic Drives, Johannes Kepler University, Linz, Austria

Scherrer Matthias received his master degree in Mechatronics from JKU Linz, Austria in 2018. Currently he is a PhD student at Institute of Machine Design and Hydraulic Drives in JKU and his Research fields are simulations and experimental study of hydraulic components and system, especially for exoskeleton actuations. He also gained industrial experiences in the hydraulic field at Hainzl Industriesysteme.

Scheidl Rudolf, Institute for Machine Design and Hydraulic Drives, Johannes Kepler University, Linz, Austria

Scheidl Rudolf received his M.Sc. of Mechanical Engineering and Doctor of Engineering Sciences degrees at Vienna University of Technology. He has research and development experience in agricultural machinery (Epple Buxbaum Werke), continuous casting technology (Voest-Alpine Industrieanlagenbau) and paper mills (Voith). Since 1990, he is a full Professor of Mechanical Engineering at Johannes Kepler University, Austria. His research topics include hydraulic drive technology and mechatronic design.

Luckachev Evgeny, Institute for Machine Design and Hydraulic Drives, Johannes Kepler University, Linz, Austria

Lukachev Evgeny graduated in 2007 from Bauman Moscow State Technical University in Kaluga, Russia. He worked as an engineer in the power plant turbine industry and in the development of electric drives. He started as a PhD student at the JKU Linz in 2012 and graduated in 2019. The topic of his research is hydraulic drives with fast switching valve control.

References

Holl E., Scheidl R., Eshkabilov S. (2017). Simulation Study of a Digital Hydraulic Drive for a Knee Joint Exoskeleton. In Proceedings of the 2017 ASME/BATH Symposium on Fluid Power and Motion Control FPMC2017, October 16–20, 2017, Sarasota, FL, USA. Paper No. FPMC2017-4220.

Scheidl R. (2017). Digital Fluid Power for Exoskeleton Actuation – Guidelines, Opportunities, Challenges. In DFP17; Proceedings of the 9th Workshop on Digital Fluid Power (DFP17), 7–8 September, 2017, Aalborg, Denmark.

Scheidl R., Mittlböck S.: A Hydraulic Piloting Concept of a Digital Cylinder Drive for Exoskeletons: Proceedings of Bath/ASME Symposium on Fluid Power and Motion Control, FPMC 2018, 12–14 September 2018, University of Bath, Bath, UK, no. FPMC2018-8875, 2018.

Scherrer M., Scheidl R., Mittlböck S. (2019) Embodymentdesign of a hydraulic binary counter for exoskeleton use – problems and new solutions. In Proceedings of the 10th Workshop on Digital Fluid Power, February 28–March 1, 2019, Linz, Austria.

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Winkler B., Mikota G., Scheidl R., Manhartsgruber B.: Modelling and Simulation of the Elasto-Hydrodynamic Behavior of Sealing Gaps, in Australian Journal of Mechanical Engineering (formerly Transaction of Mechanical Engineering), vol. 2, no. 1, 2005.

Gradl C. and Scheidl R. A Combined Hydrostatic Hydrodynamic Bearing Based on Elastic Deformation. Proceedings of the Proceedings of the 9th FPNI Ph. D. Symposium on Fluid Power: October 26–28, 2016, Florianoìpolis, SC, Brazil. 2016.

Gradl C. Hydraulic Stepper Drive, Conceptual Study, Design and Experiments. Dissertation. Johannes Kepler University Linz. February 2017

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Published

2022-09-28

How to Cite

Matthias, S. ., Rudolf, S. ., & Evgeny, L. . (2022). A New Elastic Non Contacting Sealing Concept for Valves. International Journal of Fluid Power, 23(03), 433–452. https://doi.org/10.13052/ijfp1439-9776.2339

Issue

Section

GFPS 2020