A New HCCI Combustion System for Diesel Engines Based On the Technologies of Multi-pulse Fuel Injection And the BUMP Combustion Chamber

摘要

This paper presents a compound combustion technology of "Premixed Homogenous Combustion" And "Lean Diffusion Combustion" for the purpose of realizing the concept of HCCI combustion in a D I diesel engine. The premixed homogenous combustion is realized by the technology of multi-pulse fuel injection. The start of pulse injection, injection-pulse numbers, injection period of each pulse and the dwell time between injection pulses are fairly controlled. The principle of control of pulse injection is to limit the penetration of the pulse injection so that the fuel would not touch the cylinder linear, and to enhance the mixing rate of each of fuel package by enhancement of disturbing of each to another. The last or main injection pulse is set around TDC. It can only mix with air in a short time period, because of short ignition delay. A flash mixing technology is developed from the development of a so-called BUMP combustion chamber. The lean diffusion combustion of the fuel injected in the last injection pulse conducts at a much higher equivalence air/fuel ratio, comparing to that in a conventional diesei engine. The measured rate of heat release reveals gentle and single peak curve. Obviously, reduction of both soot and NOx emissions has been obtained. Results from fundamental study are also given in this paper for understanding of the mixing and combustion process.