The Improvement of Lean Mixture Combustion in the Spark Ignition Engine by Stratified Charge in Large Prechamber

The object of this study is to investigate a principle of obtaining stratified charge in spark ignition engine.

The stratification is obtaining in a large prechamber which comprises 50% of the compression volume and which is connected to the main combustion chamber through a relatively large flow transfer passage. The fuel is injected (at any load) into the transfer flow passage, during the compression stroke and the air-fuel mixture is carried toward the spark plug.

The control of mixture stratification and emissions can be achieved by the injection timing variation. The values of the specific fuel consumption and specific NO_X emission are of the same level comparing to the values obtained for a Diesel engine with divided combustion chamber. While combustion stability at very lean operation is guaranteed intake air throttling in the part load range is necessary to keep combustion temperature high enough for effective oxidation of CO and HC.

This stratification and combustion principle can be use on two or four stroke spark ignition engine, especially on two stroke spark ignition engine.