Dynamic analysis and preliminary design of twin-cylinder engines for clean propulsion systems

Facing environmental and energy challenges, automotive industry has to improve the fuel economy of vehicles and to reduce their polluting emissions. In this particular context, small twin-cylinder engines regain interest for using in urban cars or as prime movers in hybrid electric cars. One difficulty with engine having few cylinders (three or less) comes from the balancing of the inertia forces created by the moving parts. Several models (from simple analytical model to complex flexible multibody simulation) of different configurations of twin-cylinder engine are developed. These models allow computing the inertia forces and moments generated by the engines and computing the strains and stresses of engine components. An important step is the engine balancing by modification of the crankshaft counterweights or by addition of balance shafts. The effect of the gas pressure on the balancing and on the component’s strains and stresses is also modelled. At the end, a comparison of the different configurations of twin-cylinder engine is provided