Abstract
The diesel engine with its high thermal efficiency is considered to be more advantageous than the gasoline engine with regard to the issue of global warming (reduction of CO2 emissions), but technology for the after-treatment of emission gases in the diesel engine is still being developed and the diesel engine clearly requires work to match the gasoline engine in terms of emission gases from the tail pipe. However, many new concepts about combustion have been proposed and are being developed for mass production for combustion technology that simultaneously maintains the current high thermal efficiency and reduces particulate matter (PM) and nitrogen oxide (NOx) emissions, including premixed charge compression ignition (PCCI) and low-temperature combustion(1)(2). However, with these combustion technologies, there is the issue that the heat release is unstable compared with that of conventional combustion, thus easily affected by fuel properties and operation conditions. This is because the high rate of premixed combustion is generated due to further retarding ignition through changes in the fuel injection timing, increasing the exhaust gas recirculation (EGR) ratio and removing the need for the pilot injection, as compared to conventional combustion with diffusive combustion as the main characteristic.
This study concerns a system that addresses these issues by detecting the ignition timing with In-cylinder pressure sensors and by controlling the fuel injection timing and the amount of EGR for optimum combustion onboard. This system was able to attain both cleaner emission gases and stable combustion without being affected by external factors such as the cetane number of the fuel, even with PCCI where combustion is relatively unstable.
Keywords:In-cylinder sensor, Fuel, Cetane number, Diesel, Ignition timing,