Homogeneous charge compression Ignition Engine

Recent technology in automobile- HCCI Engine
In HCCI engine the fuel and air are mixed together and injected into the cylinder. The engine compresses the mixture until spontaneous combustion occurs. The engine thus combines fuel-air-premixing(as in an SI engine) with spontaneous ignition(as in diesel engine). In this engine there is no need for a quickly spreading flame because combustion occurs throughout the combustion chamber.As a result combustion temperatures are lower, so emissions of nitrogen pollutants are negligible.However it is very difficult to control exactly when ignition occurs in HCCI engine.