Gasoline HCCI - from Thermodynamic Potential to Real World Fuel Economy - Results from Multi-Cylinder Testing

Authors

Dr. Matthias Alt, Prof. Dr. Uwe Grebe, Paul Najt, Dr. Nicole Wermuth, Mark Huebler, Dr. David Reuss, General Motors

Year

2007

Summary

Homogeneous Charge Compression Ignition, HCCI, has been acknowledged as the gasoline engine technology with a high potential for reducing both fuel consumption and exhaust gas emissions. Transferring HCCI technology from single-cylinder stead-state engine operation in the laboratory to a modern passenger car has been a significant challenge for many years. However, fast-transient HCCI operation is now possible using a combination of variable valvetrain, central direct injection, cylinder-pressure sensing, and cycle-to-cycle engine controls. The variable valve train is required to control the in-cylinder temperature with residual-gas and the central, direct injection is required for cylinder balancing and per-cycle fueling response. Cylinder-pressure sensing with robust, closedloop engine controls is necessary to compensate for the influences of fuels, ambient pressure and humidity. In combination, these enabling technologies are shown here to provide HCCI operation over a large speed-load range. General Motors (GM) has achieved low-load and idle operation using “Mixed Mode Combustion”, which was developed with the aid of advanced simulation and optical engine techniques. The next step in the development of a robust HCCI combustion system will be the transfer of the dynamometer results into a vehicle application.

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