Abstract
Diesel vehicles have been attracting consumers with good fuel efficiency and driveability realized by high torque at low speed. The increasingly stringent legislative requirements of exhaust gas and CO2 emissions push for further improvements of the engine and also the aftertreatment system by components such as LNT and SCR. This will lead to difficulty in installation and increase the cost. As a result, reducing the diesel-powered vehicle advantage in cost and make them less attractive compared to gasoline-powered and hybrid vehicles.
On the other hand, in emerging countries where the automobile market is strongly growing, diesel engines are in demand for logistics, national development, industrial progress and other productive activities. Now that diesel engines are more widely used in various regions in the world, it will be impossible to assume a certain level of fuel quality like in the first world countries. Combustion fluctuation, low fuel efficiency, acceleration failure, or other deteriorated driveability aspects may occur due to poor quality fuels.
In order to cope with these problems, DENSO introduced the fourth generation common rail system (CRS) capable of offering ultra high pressure fuel injection of up to 2500 bar into the market in 2013 thus ensuring lower absolute values of emissions, higher fuel efficiency and good driveability. The new CRS, which is robust against foreign material, was built up through fundamental review of the design back to the best form of the system.
Reduced variation in emissions was also achieved by a new air path control which directly controls the engine steady-state emissions. Additionally this control allows for improved transient emissions. The engine out emissions are reduced, thus reduces the aftertreatment workload, resulting in improved packaging and cost reduction of the total engine management system (EMS).
In addition, by using the world's first direct feedback control system (i-ART) which was commercialized in 2012, this system can detect the fuel properties allowing for optimal combustion.
DENSO promotes further diesel developments to contribute to an increased grow of environmental friendly Diesel vehicles.
KEYWORDS – CO2, Emission, Common rail system, Air path control, Diesel engine