Abstract
Environmental protection and efficient energy utilization have been always important issues in the automotive industry, but have gained significant momentum with the growing demand for mobility around the world and its impact on the global environment. Towards this scope, many improvements in automobile technology have been accomplished over the past decades. However, fuel economy with improvements in vehicle, powertrain technology have been penalized by customer preferences. Automotive industry faces the challenge of producing vehicles that meet future fuel economy and emissions requirements which are priced to meet the desired customer value. As hybrid vehicles, due to the high cost of the electrification they introduce, in next years will not impact the OEM fleet-averaged CO2 figures in a significant way, it is beneficial to introduce new cost-oriented CO2 features able to optimize engine operations, as they offer a very favourable cost/benefit ratio. According to market trend, the increasing interest on automated transmission (i.e. MTA,DCT, e-Clutch) plays a key-role towards the optimization of engine operation. The basic principle of shutting the engine off at idle to remove engine’s drag torque could be adopted at vehicle in motion, extending the distance covered by the vehicle rolling in neutral, when no traction is required, by opening the clutch automatically. Literature calls such operation sailing: represents a low cost control feature, as it does not introduce new components, able to enhance Start & Stop technology. The paper will assess the impact on fuel economy of opportune strategies to enable sailing both over real world driving and on relevant regulatory schedules. The study will focus on a Diesel engine powertrain, as its higher efficiency than gasoline reduces the space for improvement, it offers greater opportunity by removing engine’s drag to extend ICE shut-off periods and, due to its higher diffusion in the European market, it impacts CO2 figures in significantly.
KEYWORDS – CO2, Sailing, Stop & Start, Control, Powertrain