Advances in Dynamic Skip Fire: eDSF and mDSF

Autoren

Dr. Matthew Younkins, Dr. Elliott Ortiz-Soto, Dr. Mark Wilcutts, John Fuerst, Tula Technology, San Jose, CA, USA;
Dr. John Kirwan, Keith Confer, Karim Aggoune, Delphi Technologies, Troy, MI, USA

Zusammenfassung

Global CO₂ mandates require a substantial increase in vehicle fuel efficiency over the next several years. Electrification will clearly play an increasing role for the vehicle propulsion system. An important segment of electrified powertrains are mild hybrid vehicles, which are expected to comprise the majority of electrified vehicles produced globally in 2025. However, efficiency improvements to the internal combustion engine must continue, since the majority of vehicles will continue to have engines for many years to come.

Delphi Technologies and Tula Technology have built and tested a demonstration vehicle that combines Dynamic Skip Fire (DSF) with 48V mild hybridization (which when coupled together is called eDSF) in a 4-cylinder turbocharged gasoline direct injection vehicle. DSF is an advanced cylinder deactivation strategy providing independent control for each cylinder on a cylinder-by-cylinder and cycle-by-cycle basis. The reduction in pumping losses provided by DSF offers a hybrid system additional available kinetic energy for recovery through regenerative braking. Test results show greater than 15 % fuel consumption reduction with DSF and mild
hybridization in the demonstration vehicle.

Tula Technology is also developing a novel concept designated as mDSF, which integrates Dynamic Skip Fire and Miller cycle engines, and is projected to reduce drive cycle CO₂ emissions by 10-12 %. In mDSF, individual cylinders dynamically switch among three operating states: high charge firing (high cylinder load), low charge firing (with aggressive Miller cycle) and deactivation. The mDSF concept provides enhanced control over engine firing frequency and torque waveform compared with DSF, which helps to mitigate NVH issues that currently limit its efficiency improvement potential. mDSF also minimizes the efficiency-power tradeoff commonly required in Miller cycle engines and maximizes the best fuel consumption area through cylinder deactivation.

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