A pressure accumulative injection rate controllable unit Injector--PAIRCUI is proposed and developed. This unit injector is powered by fuel pressure accumulation, controlled by an electronic control unit and its injection rate is shaped by inner valves of the injector.Inherent advantages of an accumulator type unit injector have been carried out in this new design. Including structural simplicity totally flexible injection timing medium common rail pressure tolerable pump size and flow requirement. A number of decisive features have also been realized that are significant for high efficiency and low emissions of engine combustion. Including higher mean effective injection pressure (MEIP), pilot injection capability and rapid end of injection. The injection pressure is independent of engine speed but regulated upon engine load. These characteristics are beneficial in improving engine performance and fuel consumption. Installing PAIRCUI Fuel System on an engine is convenient since the injector holder is designed as a Standard- I P or S size and a conventional P or S nozzle up is incorporated as a part of the injector

The paper has presented a new reduced chemical kinetic model for the Homogeneous Charge Compression Ignition (HCCI) combustion of n-heptane in an engine, which contains 44 species and 72 reactions. The reduced model includes four sub-models: the first is the low-temperature reaction sub-model, which is established by determining particular aldehydes and small hydrocarbons in the Li-model developed by Li et al. The second is the sub-model for large molecules decomposing directly into small molecules that is developed for linking the low-temperature reaction with high-temperature reaction. The third one is used for high-temperature reaction, which is generated by several modifications to Griffiths-model developed by Griffiths et al., omitting several reactions, adding two oxidization reactions related to CO and CH3O. In addition, the sub-model for NOx formation from the reduced kinetic model presented by Golovitchev is also combined into the reduced model. This reduced model has been used to simulate the cool-flame and hot-flame combustion process of n-heptane as well as NOx formation in HCCI engines, and the calculation results agree well with those of the detailed model proposed by Curran et al. The CPU time of consuming in the reduced model is 1/1,000 that of the detailed model. Thus, the HCCI engine simulations using chemistry with CFD are attainable by using the reduced model.

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.