Smart Engine Control Strategy for the Fuel Efficiency Improvement via Understanding the Unique Behavior of TWC 2019-01-1406
The worldwide fuel economy compliance level has been tightening, at the same time, regulations on the emission of NMOG and NOx are also strengthened due to the introduction of LEV-III/Euro-6d/China-6/BS-6 regulations.
Therefore, intensive research effort has been conducted in order to improve the fuel efficiency of passenger cars and reduce exhaust emission. By responding to these demands, turbocharged gasoline direct injection (TGDI) engine is being introduced for gasoline vehicles in consideration of fuel efficiency improvement, high output and driving performance compared to naturally aspirated (NA) engine. However, due to its larger thermal mass with the turbo hardware in the exhaust, it suffers from the cold-start emission.
The main hazardous gases emitted from gasoline vehicles are CO, HC and NOx, and a three-way catalyst (TWC) is installed for the purification of these harmful emissions. But vehicle-mounted TWC converters gradually reduce the ability to purify hazardous emissions as vehicle mileage increases. Here, the degradation of the TWC is caused by chemical and thermal mechanisms.
The performance index of the TWC (three-way catalytic converter) is generally closely related to Oxygen Storage Capacity (OSC), and OSC also decreases as the performance of the TWC decreases. So the relevant parameter to monitor the decreasing performance of the TWC over its lifetime is believed to be its OSC.
In this study, we investigated the change of tailpipe emissions according to the performance degradation of TWC used in the 1.4 TGDI Elantra. For example, during transient conditions such as cold-start, fuel-cut, and O2 purge events, , the tailpipe emission performance are quite sensitive to the status of TWC properties such as the dispersion of active metals and OSC. Therefore, overall aftertreatment performance of TWC are determined by the exhaust composition (lambda) as well as its temperature controlled by the enginecontrols. We will propose smart engine control strategies to improve the fuel efficiency by understanding the relationship between the emission control performance and the properties of TWC.
Jin Woo Choung, Soo Min Lee, Sung Jae Kim, Dong Hoon Lee, Kiyoung Kwon
Hyundai Motor Company, Hyundai Kefico Corporation