CDA combined with flexible valve motion at steady-state lightly loaded and loaded idle conditions further improves the tradeoff between fuel economy and thermal management in comparison to conventional thermal management strategies ( Ding et al., 2015 Lu et al., 2015). demonstrated 3% fuel savings when CDA is implemented at idle during the heavy-duty federal test procedure (HDFTP) ( Joshi et al., 2017). Previous work by several of the co-authors, and others, has shown that diesel engine CDA exhibits a beneficial thermal impact on the aftertreatment system ( Leone and Pozar, 2001 Zammit et al., 2014 Ding et al., 2015 Garg et al., 2016 Joshi et al., 2017). Production diesel engines do not currently implement CDA. CDA is a well studied and implemented strategy in the gasoline market, for which fuel benefits are realized by enabling stoichiometric combustion with reduced intake air throttling ( Leone and Pozar, 2001 Radulescu et al., 2013). Effective exhaust aftertreatment operation requires elevated temperatures, generally exceeding 250° C ( Charlton et al., 2010 Hou et al., 2010 Gehrke et al., 2013 Song et al., 2013 Stadlbauer et al., 2013 Chen and Wang, 2014, 2016).Ĭylinder deactivation (CDA) involves deactivating the fuel injection and valve motion for a sub-set of cylinders ( Archer and McCarthy, 2018). The DPF functions as a filter to capture PM that is produced during combustion and the SCR reduces NO x. The DOC oxidizes engine-out UHC and carbon monoxide (CO). Modern diesel engine aftertreatment systems include a diesel oxidation catalyst (DOC), diesel particulate filter (DPF), and selective catalytic reduction (SCR) system. Aftertreatment systems are also required ( Stanton, 2013).
On-engine emissions control strategies include varying the injection timing, amount, and pressure exhaust gas re-circulation (EGR) intake air valve throttling and exhaust manifold pressure control via a valve or variable geometry turbine (VGT) ( Johnson, 2012 Stanton, 2013 Joshi et al., 2017). to 0.2 g/hp-hr oxides of nitrogen (NOx), 0.01 g/hp-hr particulate matter (PM), and 0.14 g/hp-hr unburnt hydrocarbons (UHC) ( United States Environmental Protection Agency, 2010). Furthermore, the thermal merits of cylinder cutout require high exhaust manifold pressures, and are subject to the configuration of the exhaust manifold and the exhaust gas recirculation (EGR) path.ĭiesel engine emissions are strictly regulated in the U.S. As a result, CDA is more efficient than cylinder cutout. CDA reduces the air flow rate by deactivating cylinders, which reduces the charge flow rate and enables a small delta pressure between the intake and exhaust manifolds, resulting in less pumping work by the cylinders. Cylinder cutout reduces the air flow rate via elevated amounts of recirculated gases which are also required to regulate engine-out NOx, resulting in a larger delta pressure across the engine and consequently more pumping work than CDA. These fuel efficiency improvements primarily result from reductions in pumping work via reduced air flow through the engine. Cylinder cutout demonstrates 17% fuel savings, while CDA demonstrates 40% fuel savings, over the stock six-cylinder thermal calibration. In addition to achieving engine-out NOx levels no higher than the stock thermal calibration, both cylinder cutout and CDA enable up to 55 and 80% reductions in particulate matter (PM), respectively. The study described here demonstrates that CDA does not require an elevated exhaust manifold pressure for thermal management or EGR delivery control, whereas cylinder cutout does. At curb idle, this stock calibration depends on elevated exhaust manifold pressure to increase the required fueling (for thermal management) and to drive EGR. Experiments and analysis demonstrated that both CDA and cylinder cutout enable improved fuel efficient “stay warm” thermal management compared to a stock thermal calibration on a Clean Idle Certified engine. This study compares diesel engine aftertreatment thermal management improvements possible via CDA and cylinder cutout at curb idle operation (800 RPM and 1.3 bar BMEP). CDA includes the deactivation of both the valve motions and the fuel injection of select cylinders, while cylinder cutout incorporates only fuel injection deactivation in select cylinders. 2Eaton Vehicle Group, Galesburg, MI, United StatesĬylinder deactivation (CDA) and cylinder cutout are different operating strategies for diesel engines.
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