Diesel engine cylinder deactivation
Diesel cylinder deactivation (CDA) and early/late intake valve closing (EIVC/LIVC) technologies can be used to reduce fuel consumption between five and 25 percent, increase the rate of aftertreatment warm up, and maintain higher temperatures during low load operation. These can also be used at road loads to achieve active diesel particulate (DPF) regenerations without requiring the traditional method of dosing the diesel oxidation catalyst.
Vehicle acceleration is limited by the engine’s ability to increase the airflow quickly enough to allow the addition of sufficient fuel to meet the desired torque and power. Results show that it is possible to operate a diesel engine at low loads in CDA without compromising its torque and power capabilities, a key finding in enabling the practical implementation of cylinder deactivation in diesel engines, which initial testing shows has no negative effects on engine response.
EIVC/LIVC modulation reduces the effective compression ratio, which decreases nitrogen oxides (NOx) through reductions in in-cylinder temperatures prior to, during and following combustion. EIVC/LIVC enables the engine calibration to be tuned for better engine efficiency, including earlier injection timing.
Selective catalytic reduction (SCR) systems operate most efficiently when temperatures are between 250 and 450 degrees Celsius. Once the aftertreatment has reached this temperature range, it is preferable to maintain turbine outlet temperature (TOT) within this range so that dosing of the diesel oxidation catalyst, which still requires temperatures above 250 degrees Celsius, is not needed to keep SCR temperatures elevated.
Eaton’s CDA and EIVC/LIVC technology can operate at up to 3 to 4 bar BMEP at all speeds, which reduces emissions by improving aftertreatment thermal management while providing the welcome side effect of better fuel economy. These technologies can be used at higher loads for DPF regeneration. Similarly, IVC modulation can be used at higher loads to enable Miller cycle operation to improve engine fuel efficiency.
Other variable valvetrain functions include exhaust valve opening (EEVO) and internal exhaust gas recirculation (iEGR), which help heat the exhaust for improved catalyst efficiency and improved emissions.