Method for improving the efficiency of direct fuel injection IC engine by a two stage burn with a rich mixture followed by a lean mixture

摘要

A method for improving the efficiency of a direct fuel injection IC engine has an initial burn with a rich mixture followed by a second burn with a lean mixture to burn any residual fuel. The initial burn has a lambda ratio of less than 0.7, preferably about 0.5 while the second burn has a lambda ratio of more than 1.3. The second burn has air added prior to the burn or during the burn and prepares the cylinder for the next fuel injection pulse. The two stage burn reduces the nitrous oxide content in the exhaust gasses and can use a stepped piston.