A Homogeneous Charge Compression Ignition runs on gasoline but ignites its fuel using compression like a diesel. The result is an engine that gives you the best of both worlds.The biggest challenge with an HCCI engine is that it can only control that combustion when its internal temperature is kept within a small window. Otherwise, you have knock problems and fuel detonation issues.
This technology has been underdevelopment for many years, hopefully they will eventually solve the management problems.
The following video does a great job of explaining it.
Steps Toward Practical Application of HCCI
- 3D HCCI Simulation Technology
As the ignition mechanism for HCCI combustion does not depend on spark plugs, it is necessary to control the auto-ignition timing and combustion duration. Nissan has newly developed technology to accurately simulate HCCI three-dimensionally.
- Utilization of VVEL
To control the gas temperature inside the combustion chamber, it is necessary to change the amount of residual exhaust gas accordingly to driving conditions. Nissan uses VVEL, which allows free-control of the valve timing and lift, for both intake and exhaust valves, to control temperature by effectively using internal EGR.
This is another interesting video talking about the software and management issues