Inherent Advantages and Fuel Efficiency Gains by Eliminating the Crankshaft: 1-D Simulation of a Novel Engine Design

Brad R. Tillock; Brad Raether

doi:10.4271/2010-01-0316

A new engine design is evaluated using 1-D engine cycle simulation. The new design changes how force on the piston is transferred to useful torque at the output shaft. The coupling design brings with it many possible advantages including custom piston motion, variable compression ratio, extended power stroke, and reduced friction. Each of these benefits is explored individually and collectively.

The actual engine exists today only in a compressed air version. A development plan is in place to build and test a fuel burning prototype in 2010. Lacking data from a firing engine, some assumptions are required in the analysis and these are documented.

The engine is evaluated in this work in two forms; 1) a power stroke for every two output shaft revolutions and 2) a power stroke for every output shaft revolution. Both of these engine variations are in the development plan and both are needed to address different applications that the engine may be designed for. The new engine concept is modeled in GT-POWER which is capable of handling the non-conventional piston motion and non-conventional transfer of cylinder pressure to useful torque. The engine is compared to traditional SI engines in terms of brake thermal efficiency.

Engine analysis is made in steps to specifically account for each aspect of the engine; rapid piston motion around TDC for knock resistance, combustion variations, reduced friction, variable compression, extended power stroke, and lean operation. Initial results suggest that drive cycle efficiencies could increase as much as 40% if the engine is fully developed and optimized.

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Inherent Advantages and Fuel Efficiency Gains by Eliminating the Crankshaft: 1-D Simulation of a Novel Engine Design 2010-01-0316

SAE MOBILUS