Search Results

Emission regulations and fuel economy regulations are becoming more severe simultaneously, and they give much issue for automotive diesel R&D society. Moreover, emission test cycles are getting more tough transient conditions, like as WLTP. To meet the emission regulations in this trend, in-cylinder combustion requires more precise control. Designing hardware robustly and improving controllable are possible solutions to accomplish the precise combustion control. On the other hand, combustion control based on in-cylinder pressure signal is helpful to control in-cylinder combustion directly. Combustion control using in-cylinder pressure signal is also known to be useful to reducing engine-by-engine exhaust emissions variation due to the manufacturing tolerance, variation of fuel specification and deterioration of engine component during the whole lifetime.

More emissions are produced when Diesel engines operate in the transient state than in the steady state. This discrepancy is due to mismatching between the air-charging system and the fueling system. Moreover, the difference in the response time between the intake pressure and the exhaust pressure caused by turbo-lag leads to an excess supply of EGR. In this study, a model that can calculate the EGR rate of the intake gas was developed. In the model, temperatures of the air, the EGR gas and the mixture gas were measured with thermocouples which have a fast response. The EGR rate was calculated through the energy balance equation considering heat transfer. Moreover, the estimated EGR rate was applied to a closed-loop control system that receives feedback from 50 % of the mass fraction burned (MFB50) by a 2.2 L Diesel engine. When there is a difference between the target EGR rate and the estimated EGR rate, the target MFB50 can be modified.

Emissions regulations are becoming more severe, and they remain a principal issue for vehicle manufacturers. Many engine subsystems and control technologies have been introduced to meet the demands of these regulations. For diesel engines, combustion control is one of the most effective approaches to reducing not only engine exhaust emissions but also cylinder-by-cylinder variation. However, the high cost of the pressure sensor and the complex engine head design for the extra equipment are stressful for the manufacturers. In this paper, a cylinder-pressure-based engine control logic is introduced for a multi-cylinder high speed direct injection (HSDI) diesel engine. The time for 50% of the mass fraction to burn (MFB50) and the IMEP are valuable for identifying combustion status. These two in-cylinder quantities are measured and applied to the engine control logic.