Direct injection system for a two stroke engine

Abstract

Direct injection is becoming an important option to further optimize internal combustion engines. In the case of two stroke engines, the opportunity of dramatically reducing the HC emissions by almost eliminating short circuit while scavenging, makes this system even more attractive. For small two stroke engines, like the ones used to power chain saw tools, the need of a high pressure fuel pump (its size and electricity needs) makes that the use of direct injection becomes not feasible. By using a self pressurized (boosted) direct injector, the opportunity of using direct injection opens for these small engines since a high pressure pump is not needed. The Evinrude E-TEC™ outboard engine uses a direct injection system which makes use of this kind of injectors. The Evinrude E-TEC™ outboard engine is analyzed in a test rig to find out the characteristics of the injector and the combustion modes the engine runs at different speeds and loads. The emissions of the engine are measured, along with the power, speed, combustion chamber pressure trace, bsfc, and voltage and current developed by the injector.