A Study of Dynamic Combustion Control for High Efficiency Diesel Engine 2020-01-0297
The subject of this paper is to discuss the use of advanced combustion controls of direct injection diesel engines, to achieve simultaneous improvements in thermal efficiency while maintaining minimum pollutant emissions.
In recent years, the emissions produced in the transportation sector are becoming increasingly scrutinized, leading to significantly strengthened emissions legislations with regard to NOx and CO2, especially under Real Driving Emission (RDE) conditions. Therefore, diesel combustion improvements are key to overcoming these challenges. This paper reports the following two innovative Diesel combustion control technologies to realize the objectives mentioned above.
Combustion improvement by accurate Combustion Rate Shaping (CRS), CRS enables direct control of in-cylinder pressure trace and heat release rate. A newly developed DENSO fuel delivery injector with strengthened solenoid magnetic force enables injection flexibility by fast opening and multiple close-coupled injections, resulting in a reduction in soot, nitro-oxides and fuel consumption.
Reduction of calibration effort by Closed Loop Combustion Control (CLCC) with only two control parameters, the target in-cylinder pressure trace is predetermined. The feedforward combustion model calculates the required injection fuel trace to achieve the target pressure trace. The resulting pressure is measured by a cylinder pressure sensor, which is used as feedback to control the target metric.
Those technologies are key features for advanced engine performance. Multi-cylinder Diesel engine experiments confirmed lower in-cylinder temperature in the condition of advanced combustion timing toward Top Dead Center (TDC), and showed remarkable improvement of NOx - CO2 trade-off in transient driving cycle; Worldwide Harmonized Light vehicles Test Cycle (WLTC).