NFPA Research Supplement Update: High Efficiency Hydraulic Pump-Motors Employing Partial Stroke Piston Pressurization

By Eric Lanke
NFPA President/CEO

I recently attended the October 2018 Summit of the Center for Compact and Efficient Fluid Power (CCEFP) at the University of Minnesota. This is one of the meetings this fiscal year where the fluid power research projects supported by our new NFPA Research Supplement Program were presented.

In our efforts to increase the number of university students educated in fluid power, the NFPA Education and Technology Foundation has provided ten $10,000 research supplements to ten academic faculty members working on fluid power research at six universities. This helps to engage current and build the careers of future university faculty who are and will be in a position to teach fluid power to undergraduate engineers on their campuses. The research supplements provide travel support so that each faculty member and one of their graduate students can attend to present their research at designated industry conferences and research summits like the one hosted by the CCEFP.

One such faculty member is Professor Thomas Chase of the University of Minnesota, whose graduate student, Alissa Montzka, presented on their project, “High Efficiency Hydraulic Pump-Motors Employing Partial Stroke Piston Pressurization,” at the CCEFP Summit. The goal here, as I understand it, is to use a mechanical control function, in the form of specially-designed spool valve instead of an electronically-controlled swashplate, to gain greater hydraulic pump efficiencies from the use of partial stroke piston pressurization. Working with funding provided by the National Science Foundation, Montzka and her team have been able to:

• Build an appropriate test stand and data acquisition system to test the hypothesis.
• Demonstrate that piston control using mechanical valving has advantages of simplicity and ruggedness.

Their initial tests have not demonstrated the efficiency gains they seek, but the same tests have revealed several improvements that could be made to the test stand apparatus, including the removal of pilot valve leakage and appropriate setting of the timing angle for the spool valve.

A copy of Montzka’s presentation slides can be accessed here.

Collectively, the research projects supported by NFPA Research Supplements represent more than $4.9 million in funding from a variety of organizations, including the U.S. Department of Energy, the National Science Foundation, and the Center for Compact and Efficient Fluid Power (CCEFP). They are an excellent sample of the growing body of fluid power research being funded by the federal government and other research organizations.