Free Piston Engine Project Offers Enhanced Efficiency and Control

The fluid power research projects coming out of the Center for Compact and Efficient Fluid Power (CCEFP) have continued to progress, and all ten of the newly funded projects were presented at the CCEFP Industry-University Summit in April 2017. The Free Piston Engine Based Off-Road Vehicles project was presented by Keyan Liu, a research assistant at the University of Minnesota. The progress made on this project shows enhanced efficiency and control for free piston engines in mobile applications.

Project Premise: This project has focused on the design, control, and testing of free piston engine pumps for off-road vehicles, a potentially transformational architecture. It has differentiated itself from existing technology approaches by controlling the hydraulic engine, in lieu of variable pumps, to generate the required pressure and flow for the vehicle’s hydraulic actuation systems, including both linear and rotary motions. Solutions to improve vehicle fuel efficiency and energy storage while reducing emissions and environmental impact have also been investigated.

Recent Progress and Next Steps: The researchers used dynamic simulations to determine that the independent pressure and flow control of the free piston engine design was both feasible and performed as expected. Engine thermal efficiency and pump mechanical efficiency have also been analyzed. Next steps to further refine the project include:

  • Testing the supercharging system with the free piston engine to improve combustion performance.
  • Investigating off-road vehicle applications for independent pressure and flow control.
  • Exploring free piston engine performance as a power source in an actual hydraulic circuit simulation.

See the presentation slides from the summit below:

Watch for project updates as the project progresses.

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