Discussion: Is the future of fluid power digital?

Linköping Electronic Conference Proceedings

This is the proceedings of the th Scandinavian International Conference on Fluid Power held at Linköping University in Sweden on-June. The theme of the conference was "Fluid Power in the Digital Age". The contributions are well aligned with this theme, and are indeed reflecting the great developments. We are very grateful to the effort put in by the authors to produce such high quality papers, and also to those taking time to review papers to further enhance the quality. The contributions clearly shows that the fluid power industry, and academia, have both challenges as well as opportunities in keeping up with the evolving capabilities provided by the digitalization. It was with great joy to see old and new colleagues and friends attending our conference and the division of Fluid and mechatronic systems, at Linköping University. The conference is a biannual event, with alternating localization between Linköping in Sweden and Tampere in Finland. The process of hosting such an event is a great effort for our organization and I would like to thank all those involved in organizing this conference, and wish good luck with the next one to our Finnish colleagues. Thank you! Prof. Petter Krus Head of Division Fluid and Mechatronic Systems. Review Process Each author attending the conference days had the opportunity to select from three different ways of presenting their contribution. Firstly, a reviewed process with at least two international reviewers of each contribution. The process resulted in most cases with feedback from the reviewers with comments spanning everything between diagram legends to scientific methods. Some proposed papers where rejected upon recommendations from reviewers. Secondly contributions where also presented in industry sessions where the review process where internal only by the staff of the division. A third extended abstract presentation format where also presented during the conference. This proceedings contain all presented contributions from the reviewed papers in the first section and thereafter the non-reviewed papers in second section. All reviewed papers are marked in the footer by the acceptance date.

Mechanics, 2014

Energies, 2018

Processes, 2020

The switched inertance hydraulic converter (SIHC) is a new technology providing an alternative to conventional proportional or servo-valve-controlled systems in the area of fluid power. SIHCs can adjust or control flow and pressure by means of using digital control signals that do not rely on throttling the flow and dissipation of power, and provide hydraulic systems with high-energy efficiency, flexible control, and insensitivity to contamination. In this article, the analytical models of an SIHC in a three-port flow-booster configuration were used and validated at high operating pressure, with the low-and high-pressure supplies of 30 and 90 bar and a high delivery flow rate of 21 L/min. The system dynamics, flow responses, and power consumption were investigated and theoretically and experimentally validated. Results were compared to previous results achieved using low operating pressures, where low-and high-pressure supplies were 20 and 30 bar, and the delivery flow rate was 7 L/min. We concluded that the analytical models could effectively predict SIHC performance, and higher operating pressures and flow rates could result in system uncertainties that need to be understood well. As high operating pressure or flow rate is a common requirement in hydraulic systems, this constitutes an important contribution to the development of newly switched inertance hydraulic converters and the improvement of fluid-power energy efficiency.

2017

Despite the evolution of electric drives and their undeniable advantages, hydraulic systems play an important role in today's technologies. Due to the ability to operate enormous power densities, industrial hydraulics are irreplaceable when large forces and binaries are required. Its importance can be characterized by the economy it represents and by the development potential associated with scientific interest. This paper summarizes the technologies used in the production of oil-hydraulic power, seeking to identify the trends of development and the research opportunities that come from the demands of the current developments.

International Journal of Fluid Power, 2012

Conventional variable displacement pumps are being used instead of throttle controls if energy consumption of hydrostatic drives needs to be reduced. A new promising approach is the substitution of conventional "analog" pumps by digital pumps. A digital pump is composed of several parallel constant pumps and a number of switching valves. Digital pumps tend to have better efficiencies in partial load operation than conventional pumps. In addition, digital pumps offer new concepts to supply several actuators in parallel without requiring throttle controls. The shared use of a digital pump for several actuators at once, compared to separate digital pumps for each actuator, tends to further reduce energy losses because of smaller installed total power and reduced partial load operation. A study of digital pumps in a velocity control circuit is presented here with simulation results, comparing separate analog and digital pumps for each actuator vs. shared use of one digital pump for several actuators.

Digital hydraulics is a forthcoming field which, in spite of the fact that being connected in a few routes since long, brings some new thoughts, ideas and answers for fluid power. The focal and unavoidable segments of digital hydraulic systems are on-off valves. This paper talks about the likelihood to utilize minimal price on/off valves rather than servo valves indeed, even in requiring servo applications. Different on/off control procedures are first checked on and examined. Digital hydraulics makes additionally many challenging issues for component improvement, control, modelling, simulation and treatment of dynamical impacts. These difficulties are differentiated by the potential points of interest of digital hydraulics which are complex: robustness, reliability and cost savings. In any case, other genuinely digital segments, as digital displacement pumps, digital cylinders and transformers were created to improve digital hydraulics. The Digital hydraulic principles used here involves digital valves only. In light of these basic parts, various ideas have been proposed. Results demonstrate that energy efficient and speed control is conceivable with basic and minimal cost on/off valves. In this manner, the digital hydraulics potential option for conventional servo systems.

Course lecturer: Dr. Tom Burks