Diesel engine maker Cummins Inc. and engine control software company Tula Technology, Inc. have announced that a collaborative project has demonstrated a form of advanced cylinder deactivation called Dynamic Skip Fire (dDSF). By using dDSF software to control cylinder deactivation, Cummins and Tula have demonstrated significant reductions in emissions and fuel consumption.
“At Cummins, it’s our mission to power a more prosperous world. We do this by helping customers succeed through innovative and dependable products that are good for the customer and the environment. We will continue to innovate the diesel engine system to make it lighter, more reliable, powerful and fuel-efficient, and we are encouraged by the progress demonstrated in this collaboration and what it could mean for future diesel technology,” said Lisa Farrell, Director, Advanced System Integration, Cummins Inc.
The project started in early 2019 with the goal of optimizing cylinder deactivation strategies for diesel engines, which could result in emission reduction benefits. Advancements through the project are expected to help address future, more stringent NOx regulations.
The reduction of tailpipe NOx is achieved primarily by optimized exhaust temperature control, resulting in dramatically improved conversion efficiency of the aftertreatment system. NOx is a difficult problem to solve in internal combustion engines…high combustion chamber temperatures boost efficiency, but air is mostly nitrogen and the high temperatures and pressures in a modern ICE cylinder form many oxides of nitrogen, a major contributor to photochemical smog. Early remediation technology used exhaust gas recirculation, later with cooling, but tighter emissions control standards forced urea injection aftertreatment and tighter injection event control. And NOx is just one regulated exhaust product. Today, CO2 is in play, and the only way to reduce it is by improved overall engine efficiency—including high combustion temperatures. The new technology achieves CO2 reductions through improvements in combustion and reductions in pumping losses. dDSF is also claimed to deliver improved tailpipe emissions while simultaneously reducing fuel consumption.
The collaboration work was carried out on a Cummins X15 Efficiency Series 6-cylinder diesel engine, which the joint development team modified to integrate Tula’s Dynamic Skip Fire (DSF®) control algorithms to command combustion or deactivation on a cylinder event basis. On the challenging low-load cycle being proposed by the California Air Resources Board, modeling of dDSF technology predicted reductions in tailpipe NOx (oxides of nitrogen) emissions while simultaneously reducing CO2 (carbon dioxide).
“Our partnership with Cummins has given us the opportunity to expand our DSF technology beyond its success in gasoline engines. Demonstrating the capability to improve fuel efficiency while also achieving very effective emissions control is extremely important for all diesel engine applications in the future,” said R. Scott Bailey, president and CEO of Tula Technology.
Cummins and Tula have released a joint paper titled, “Diesel Dynamic Skip Fire (dDSF): Simultaneous CO2 and NOx Reduction” for the 2020 Vienna Motor Symposium, which presented and quantified the success of dDSF in increasing efficiency and reducing CO2 and NOx. The collaboration continues with next steps involving more system optimization to control noise, vibration, and harshness in commercial vehicle applications.