2-Stroke Multipurpose Externally Scavenged Hi Efficiency Engines

Enrico Mattarelli, Carlo Alberto Rinaldini
University of Modena and Reggio Emilia

Luca Morfino

This work is related to debate on potential of the 2-Stroke concept applied to Range Extender engines, proposing 3 different configurations: 1) Supercharged, Compression Ignition; 2) Turbocharged, Compression Ignition; 3) Supercharged, Gasoline Direct Injection. All the engines feature a single power cylinder of 0.49l, external air feed by piston pump and an innovative induction system. The scavenging is of the Loop type, without poppet valves, and with a 4-Stroke like lubrication system (no crankcase pump). Engine design has been supported by CFD simulations, both 1D (engine cycle analysis) and 3D (scavenging, injection and combustion calculations). The strong points found for this family of engines are: high power density (up to 122 kW/l) and power to weight ratio; low raw emissions; compactness (design integrated with the electric motor); low production costs (no valvetrain, no EGR system); excellent balance of inertia forces (thanks to the piston pump installed on the same crankshaft, at 90° from the power cylinder); mechanical reliability (no exotic solutions, effective lubrication system); low noise (low engine speed thanks to the double frequency of the cycle); low specific fuel consumption. All those characteristics would be suitable for different application: steady generator, automotive, aviation, etc.