Cylinder deactivation is a fuel consumption and CO2 reduction technology for internal combustion engines that deactivates cylinders at light to moderate loads, allowing the remaining firing cylinders to operate near optimum efficiency. Dynamic Skip Fire (DSF) uses full-authority cylinder deactivation that allows any cylinder of the engine to be deactivated in sequence. In previous SAE papers, both DSF technology and the synergies between DSF and electrification (eDSF) have been described.
Recent engine technology includes deactivation mechanisms that do not effectively incorporate individual cylinder control. Nevertheless, it is still quite possible to improve the efficiency of engines equipped with these ganged-deactivation mechanisms. By grouping all cylinders into a deactivation mode, no air is pumped through the cylinders as it would be during the corresponding conventional operation that deactivates fuel alone. The engine equipped with deactivating cylinders can eliminate pumping work and provide more opportunity to recuperate electrical energy from the vehicle, as well as prevent oxygen saturation of the exhaust aftertreatment system.
This paper presents the substantial benefits of this approach, showing both simulated and experimental fuel economy improvements for a C-segment vehicle exceeding 5% in the WLTC class 3 drive cycle. It discusses control strategies for managing transitions in and out of deactivation to achieve customer-pleasing NVH and drivability. Finally, the value proposition is presented for this electrified deceleration cylinder cutoff (eDCCO) system, also known as Hybrid++.
