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	Comparison of piston speed vs. stroke for FPE and a comparable crankshaft engine. Velocity is measured at a fixed location in the stroke.
	Exceptional stroke control: +/- 0.7 compression ratios, cycle-to-cycle, cylinder-to-cylinder. This is a controllable means of achieving variable compression ratio.

Controlling a free-piston engine in a four-stroke mode was the goal of this program at Southwest Research Institute (SwRI). 

SwRI's RPECS™ was used in this study, along with a field programmable gate array (FPGA) for a magnetostrictive sensor. The flexibility of RPECS' FPGA allowed engineers to implement high-resolution position measurement of a free-piston engine’s shuttle.

A magnetostrictive sensor was interrogated every 100 us to determine absolute position. Twenty-four digital outputs, synchronous with shuttle position, coordinated fuel, intake, exhaust, and power extraction valves to control the shuttle turn-around position to within +/- 1mm.

For more information about our powertrain control capabilities, or how you can contract with SwRI, please contact Jayant Sarlashkar at jsarlashkar@swri.org or (210) 522-5506.

powertraincontroltech.swri.org

| Engine and Vehicle R&D Department | Engine, Emissions & Vehicle Research Division | SwRI Home |

Southwest Research Institute^® (SwRI^®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 11 technical divisions.

December 28, 2012