Dynamic Skip Fire: New Technologies for Innovative Propulsion Systems

Authors

M. Younkins PhD, E. Ortiz-Soto PhD, M. Wilcutts PhD, J. Fuerst BSME MBA, Tula Technology, San Jose, USA; A. Rayl MSEE, General Motors, Milford, USA

Year

2018

Print Info

Fortschritt-Berichte VDI, Series 12, No 807

Summary

General Motors leverages Tula’s Dynamic Skip Fire (DSF®) technology to introduce an industry first Dynamic Fuel Management (DFM) cylinder deactivation system that combines millisecond-accurate torque control with cylinder deactivation to optimize fuel consumption of spark ignited engines. This digitized control of every cylinder event optimizes engine operation such that peak efficiency is obtained throughout the range of engine operation. General Motors is launching Dynamic Fuel Management in the 2019 MY. Building on Active Fuel Management (AFM) that was introduced commercially in 2005, DFM extends cylinder deactivation to all cylinders in 5.3L and 6.2L V8 engines which allows for a large variety of firing sequences. In this application of DFM, 29 firing sequences are used in steady driving conditions. Transitions between firing densities are done in a continuous fashion. A method was developed and implemented to reduce required time to deactivate cylinders. Emissions limits of ULEV 50 were targeted and achieved. With production levels of noise and vibration, significant fuel economy improvement was achieved. Final fuel consumption numbers will be communicated later this year. Furthermore, continuing improvements to Tula’s DSF are being achieved as the automotive industry is focused on reducing the fuel consumption of the worldwide fleet. Across the industry, additional fuel economy technologies being pursued include electrification and improvements in combustion and combustion strategy. Tula’s DSF is synergistic with these strategies and more. For instance, eDSF™, realizes the synergies between DSF and hybridization. Development taking place over a four vehicle eDSF fleet have indicated that eDSF improves the baseline 48V hybrid performance by 8% on the WLTC. Tula has also developed mDSF™, coupling DSF with multiple cam profiles and Miller cycle strategies. Based on engine dynamometer experiments, Tula is projecting a 6-8% vehicle fuel consumption reduction in certification drive cycles over a production 2-step Miller engine. As Tula’s Dynamic Skip Fire technology is further developed with electrification, innovative combustion strategies and autonomous technologies, significant synergistic benefits are being realized and will be introduced.