Primary and Secondary Emissions Reduction Using Cylinder Deactivation Strategies for Gasoline Direct Injection Engines in Hybrid Vehicles.

Abstract

Stricter CO₂ and local air quality targets are increasing the demand for electrified powertrains including hybrid electric vehicles (HEVs). The impact of an electrified vehicle powertrain on the catalytic performance of the emissions control system presents the challenge of multiple cold/warm starts during vehicle operation. This work investigates advanced energy efficient technologies to understand and enhance the catalytic reduction of primary and secondary emissions under challenging HEV operation conditions. A novel strategy based on the concept of engine cylinder deactivation is experimentally studied at various starting catalyst temperatures aiming to reduce the time required to reach catalyst light-off temperature and thus tailpipe emissions. Unregulated secondary emissions (NH₃ and N₂O) are also investigated, which are expected to become more pertinent in the future. This work demonstrates that operating under the studied strategy for a short period of time increased TWC temperature by up to 300 °C and reduced mass-based emissions of CO, NO, HCs, N₂O and NH₃. These findings are significant to inform the optimization of energy efficient catalyst heating strategies for HEVs in order to reduce both primary and secondary emissions.