Partners Developing Opposed-Piston Engine for Hybrids


Achates Power has been awarded $2 million in funding from the U.S. Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E) for the development of a new single-cylinder, opposed-piston (OP) engine for hybrid vehicles.

Achates Power has partnered with the University of Michigan and Nissan Motor Company. Ltd. for the initiative.

The Hybrid OP Engine project will develop a single-cylinder OP engine design with a goal to minimize energy losses typical in conventional internal combustion engines. A motor-generator integrated on each engine crankshaft will provide independent control to each piston and eliminate all torque transmitted across the mechanical crankshaft connection, thus reducing engine size, mass, cost, friction and noise.

The application of high-bandwidth-power electronics will further improve engine efficiency through the real-time control of the piston motion and combustion process, says Achates Power.

“The project builds on the successful development of the OP engine and expands our research and development into the hybrid and range-extender market,” says Fabien Redon, chief technical officer at Achates Power. “The inherent balance and power characteristics of the OP engine makes it an ideal powertrain in a hybrid solution, providing vehicle manufacturers a cost-effective solution to improve vehicle fuel efficiency and reduce carbon dioxide emissions.”

The University of Michigan Energy Institute will contribute engineering resources in the design and testing of the engine, and Nissan Motor Company. Ltd. will provide experience in hybrid engine development.

“I am excited to design and optimize the controls that will free this opposed-piston engine from the mechanical constraints of the crank and gear mechanism through the electric motors; it is like breaking the shackles and unleashing its true potential,” adds Anna G. Stefanopoulou, Energy Institute director and professor of mechanical engineering at the University of Michigan. “Along with the freedom, though, comes the responsibility of highly precise control and coordination of the piston motions to maximize efficiency and ensure a smoother operation.”

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