A Compound Technology for HCCI Combustion in a DI Diesel Engine Based on the Multi-Pulse Injection and the BUMP Combustion Chamber

This paper presents a compound combustion technology of Premixed Combustion and “Lean Diffusion Combustion” for realizing the concept of HCCI combustion in a D I diesel engine. The premixed combustion is achieved by the technology of multi-pulse fuel injection. The start of pulse injection, injection-pulse number, injection period of each pulse and the dwell time between the injection pulses are controlled. The objective of controlling the pulse injection is to limit the spray penetration of the pulse injection so that the fuel will not impinge on the cylinder liner, and to enhance the mixing rate of each fuel parcel by promoting the disturbance to the fuel parcels. The last or main injection pulse is set around TDC. A flash mixing technology is developed from the development of a so-called BUMP combustion chamber, which is designed with some special bump rings. The combustion of fuel injected in the main injection proceeds under the effect of the BUMP combustion chamber at much higher air/fuel mixing rate than does in a conventional DI diesel engine, which leads to “lean diffusion combustion”. The effects of multi-pulse injection and BUMP combustion chamber on auto-ignition, rate of heat release and engine emissions are discussed.