A New Firing Concept for Internal Combustion Engines: “I'APIR” 1999-01-0621
The paper presents a new firing concept for internal combustion engines. This concept attempts to merge the best of both Spark Ignition and Compression Ignition engine worlds. The concept is called APIR in French, standing for ‘Auto-inflammation Pilotée par Injection de Radicaux’, meaning Self-ignition Triggered by Radical Injection.
The application of this concept to a standard SI engine, leads to a consequent improvement of the firing and combustion performances. A dramatic cycle variability decrease is pointed out. Initiation and combustion develop with a speed and a repeatability incomparable with the spark plug firing case.
The use of the APIR device leads to an increase of the engine operating range in terms of Lean Operating Limit and thus Lean Burn Torque Range. An interesting gain on fuel consumption for idle and low load operating points is pointed out.
The main drawback to be eliminated is the unburned hydrocarbon emission largely higher than in the conventional firing case. Contrary to the pollution due to partial burning and misfire the UHC pollutant emission due to the APIR device is localized and so may be easier to eradicate.