No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Mitigating Vibration for a Heavy-Duty Diesel Cylinder Deactivation Truck
... However, the maximum achievable boost level is limited by the characteristics of turbocharger. Despite of noise, vibration and harshness arising from unbalanced cylinder firing in CDA and CCO, it can be effectively mitigated in diesel engines [59,60]. Equally, it has been demonstrated that smooth transient performance can be achieved without severe torque variations during the switching phase [61,62]. ...
... Noise, vibration and harshness (NVH) arising from unbalanced cylinder firing is a common barrier for CDA and CCO. However, it can be effectively mitigated in diesel engines [45]- [47]. Equally, it has been demonstrated that smooth transient performance can be achieved without severe torque variations during the switching phase [3], [48]- [50]. ...
... Engine calibration updates included changes to VGT position, intake throttling, EGR rates, multiple injection, and combustion phasing Neely et al., 2020). One notable hardware update to the engine included the integration of a cylinder deactivation system (CDA), which provided critical thermal management and GHG control characteristics Neely et al., 2019;ECFR, 2022;Pieczko et al., 2021;Reinhart et al., 2020;Morris and McCarthy, 2020;McCarthy, 2019a;McCarthy, 2019b;McCarthy, 2017b;Joshi et al., 2018). CDA also enabled flexibility in increasing turbine outlet temperatures for specialized operation like LO-SCR de-sulfation (deSO X ) (McCarthy, 2017a). ...
Commercial vehicles require fast aftertreatment heat-up to move the SCR catalyst into the most efficient temperature range to meet upcoming NOX regulations while minimizing CO2. One solution to this challenge is to add a fuel burner upstream of the con`ventional heavy-duty diesel aftertreatment system. The focus of this paper is to optimize a burner based thermal management approach. The objective included complying with CARB’s 2027 low NOX emissions standards for on-road heavy duty diesel engines. This was accomplished by pairing the burner system with cylinder de-activation on the engine and/or a light-off SCR sub-system. A system solution is demonstrated using a heavy-duty diesel engine with an aged aftertreatment system targeted for 2027 emission levels using various levels of controls. The baseline layer of controls includes cylinder deactivation to raise the exhaust temperature more than 100°C in combination with elevated idle speed to increase the mass flowrate through the aftertreatment system. The combination of operating the fuel burner, cylinder deactivation and elevated idle speed (during cold start) allows the aftertreatment system to heat up in a small fraction of the time demonstrated by today’s systems. Performance was quantified over the cold FTP, hot FTP, low load cycle (LLC) and the U.S. beverage cycle. The improvement in NOX reduction and the CO2 savings over these cycles are highlighted.
... This work is complemented with other facets of CDA for seamless operation Lu et al., 2015;Halbe et al., 2017;Roberts et al., 2020). Finally, CDA has shown that noise, vibration, and harshness (NVH) on diesel is proven to be manageable (Archer and McCarthy, 2018;Reinhart et al., 2020;Pieczko et al., 2021), and there were no observable oil consumption issues over the 4 years of running this engine. ...
Commercial vehicles require fast aftertreatment heat-up in order to move the selective catalytic reduction catalyst into the most efficient temperature range to meet upcoming NOX regulations while minimizing CO2. This study is a follow-up study using an electric heater upstream of a LO-SCR followed by a primary aftertreatment system having an engine equipped with cylinder deactivation. The focus of this study is to minimize the maximum power input to the e-heater without compromising tailpipe NOX and CO2. A system solution is demonstrated using a heavy-duty diesel engine with an end-of-life aged aftertreatment system targeted for 2027 emission levels using various levels of controls. The baseline layer of controls includes cylinder deactivation to raise the exhaust temperature more than 100°C in combination with elevated idle speed to increase the exhaust mass flow rate through the aftertreatment system. The engine load is adjusted to compensate for generating electrical power on the engine. The combination of electrical heat, added load, cylinder deactivation, and elevated idle speed allows the aftertreatment system to heat up in a small fraction of the time required by today’s systems. This work was quantified over the cold federal test procedure, hot FTP, low load cycle (LLC), and the U.S. beverage cycle showing improved NOX and CO2 emissions. The improvement in NOX reduction and the CO2 savings over these cycles are highlighted.
div class="section abstract"> The commercial vehicle industry continues to move in the direction of improving brake thermal efficiency while meeting more stringent diesel engine emission requirements. This study focused on demonstrating future emissions by using an exhaust burner upstream of a conventional aftertreatment system. This work highlights system results over the low load cycle (LLC) and many other pertinent cycles (Beverage Cycle, and Stay Hot Cycle, New York Bus Cycle). These efforts complement previous works showing system performance over the Heavy-Duty FTP and World Harmonized Transient Cycle (WHTC). The exhaust burner is used to raise and maintain the Selective Catalytic Reduction (SCR) catalyst at its optimal temperature over these cycles for efficient NOX reduction. This work showed that tailpipe NOX is significantly improved over these cycles with the exhaust burner. In certain cases, the improvements resulted in tailpipe NOX values well below the adopted 2027 LLC NOX standard of 0.05 g/hp-hr, providing significant margin. In fact, near zero NOX was measured on some of these cycles, which goes beyond future regulation requirements. However, burner operation on the tested cycles also resulted in a CO2 increase, indicating that a different burner calibration strategy, or possibly an additional technology, will be needed to achieve lower CO2 emissions.
</div
Modern on-road diesel engine systems incorporate flexible fuel injection, variable geometry turbocharging, high pressure exhaust gas recirculation, oxidation catalysts, particulate filters, and selective catalytic reduction systems in order to comply with strict tailpipe-out NOx and soot limits. Fuel consuming strategies, including late injections and turbine-based engine exhaust throttling, are typically used to increase turbine-outlet temperature and flow rate in order to reach the aftertreatment component temperatures required for efficient reduction of NOx and soot. The same strategies are used at low load operating conditions to maintain aftertreatment temperatures. This paper demonstrates that cylinder deactivation (CDA) can be used to maintain aftertreatment temperatures in a more fuel-efficient manner through reductions in airflow and pumping work. The incorporation of CDA to maintain desired aftertreatment temperatures during idle conditions is experimentally demonstrated to result in fuel savings of 3.0% over the HD-FTP drive cycle. Implementation of CDA at non-idle portions of the HD-FTP where BMEP is below 3 bar is demonstrated to reduce fuel consumption further by an additional 0.4%, thereby resulting in 3.4% fuel savings over the drive cycle.
Cylinder deactivation (CDA) is a technology that can improve the fuel economy and exhaust thermal management of compression ignition engines (diesel and natural gas), especially at low loads and engine idling conditions. The reduction in engine displacement during CDA improves fuel efficiency at low loads primarily through a reduction in pumping work. During deactivation of a given cylinder, the drop in pressure inside the cylinder could possibly lead to the transport of oil from the crankcase into the cylinder owing to the reduced pressure difference between the crankcase and the cylinder. In addition, CDA might inhibit the first fire readiness of a reactivating cylinder as a result of reduced wall, head, and piston temperatures. Both of these potential issues are quantitatively studied in this article. This article describes a strategy to estimate in-cylinder oil accumulation during CDA, and first fire readiness following CDA, through comparison of individual heat release profiles before and after CDA. Cylinder cool-down and oil accumulation during deactivation could possibly result in misfire or degraded combustion upon an attempt to reactivate a given cylinder. Fortunately, experiments described in this article demonstrate no cases of misfire at any speed/load conditions for the CDA durations tested, specifically 100 ft-lb load at 800 rpm and 1,200 rpm with deactivation intervals of 0.5, 5, 10, and 20 min. Although pilot heat release in the reactivated cylinders was delayed by approximately 1 CAD after 5 min of CDA, the main heat release was very similar to the heat release of a continuously activated cylinder. As such, results show no first fire readiness issues at the conditions tested. The duration of time the engine could be operated in CDA mode without significant oil accumulation and other methods to minimize oil accumulation during CDA have also been proposed.
Cylinder deactivation can be implemented at low loads in diesel engines to improve efficiency and aftertreatment thermal management through reductions in pumping work and airflow, respectively. The rate of increase of torque/power during diesel engine transients is limited by the engine’s ability to increase the airflow quickly enough to allow sufficient fuel addition to meet the desired torque/power. The reduced airflow during cylinder deactivation needs to be managed properly so as to not slow the torque/power response. This paper demonstrates that it is possible to operate a diesel engine at low loads in cylinder deactivation without compromising its transient torque/power capabilities, a key finding in enabling the practical implementation of cylinder deactivation in diesel engines.
Abstract—Heavy-duty over-the-road trucks require periodic active diesel particulate filter regeneration to clean the filter of stored particulate matter. These events require sustained temperatures between 500 and 600□C to complete the regeneration process. Engine operation during typical 65 mile/hour highway cruise conditions (1200 rpm/7.6 bar) results in temperatures of approximately 350□C, and can reach approximately 420□C with late fuel injection. This necessitates hydrocarbon fueling of a diesel oxidation catalyst or burner located upstream of the diesel particulate filter to reach the required regeneration temperatures. These strategies require increased fuel consumption, and the presence of a fuel-dosed oxidation catalyst (or burner) between the engine and particulate filter. This paper experimentally demonstrates that, at the highway cruise condition, deactivation of valve motions and fuel injection for two or three (of six) cylinders can instead be used to reach engine outlet temperatures of 520-570□C, a 170-220□C increase compared to normal operation. This is primarily a result of a reduction in the air-to-fuel ratio realized by reducing the displaced cylinder volume through cylinder deactivation.
The 2010 Environmental Protection Agency (EPA) Emission Standard for heavy-duty engines required 0.2 g/bhp-hr over certification cycles (cold and hot Federal Test Procedure [FTP]), and the California Air Resources Board (CARB) standards require upto 90% reduction of overall oxides of nitrogen (NOx) emissions. Similar reductions may be considered by the EPA through its Cleaner Trucks Initiative program. In this article, aftertreatment system components consisting of a diesel oxidation catalyst (DOC); a selective catalytic reduction catalyst on a diesel particulate filter (DPF), or SCR-F; a second DOC (DOC2); and a SCR along with two urea injectors have been analyzed, which could be part of an aftertreatment system that can achieve the 0.02 g/bhp-hr standard. The system performance was evaluated using validated one-dimensional (1D) DOC, two-dimensional (2D) SCR-F, and 1D SCR models at various combinations of inlet ammonia (NH3)-to-NOx ratio (ANR) values for the SCR-F and the SCR to determine the injection rates required to achieve an optimum nitrogen dioxide (NO2)/NOx ratio at the inlets of both the SCR-F and the SCR. A strategy was developed that yielded 99.5% NOx conversion at inlet temperatures from 203° to 450°C, while maximizing particulate matter (PM) oxidation rate in the SCR-F and minimizing the urea consumption rate. These system components have the potential to be robust to variations in the inlet NOx and NH3 concentrations and the NOx conversion performance of the system components. NOx conversions greater than 95% in the SCR-F and SCR were determined to be primarily due to the fast SCR reaction. The two urea injectors were used to maximize NOx reduction in both devices and SCR-F PM oxidation. For the case with ANR1 = 0, a 90%-100% increase in NO2-assisted PM oxidation in the SCR-F was determined compared to a system without the second DOC and urea injector. Further development of the system components should be pursued in terms of catalyst type, catalyst loading, and external heating along with a close-coupled SCR/DOC or passive NOx adsorbers (PNA) to reduce the light-off time for cold-start emissions control.
Fuel-efficient aftertreatment thermal management in modern diesel engines is a difficult challenge, especially during low-load operation. This study explores the performance of cylinder deactivation in a diesel engine during low-load operation following highway cruise through experimental evaluation of two drive cycles, specifically extended idle and repeated heavy heavy-duty diesel truck creep cycles. Cylinder deactivation operations are shown to maintain comparable aftertreatment thermal management performance to conventional thermal management operation while reducing fuel up to 40% during extended idle operation. This fuel efficiency improvement coincides with engine-out emission reductions of 72% for soot and 52% for NOx. Cylinder deactivation also shows improved thermal management compared to a more fuel-efficient conventional operation.
Cylinder deactivation has been recently demonstrated to have fuel savings and aftertreatment thermal management benefits at low to moderate loads compared to conventional operation in diesel engines. This study discusses dynamic cylinder activation as an effective variant to fixed diesel engine cylinder deactivation. The set of inactive and active cylinders varies on a cycle-by-cycle basis during dynamic cylinder activation. This enables greater control over forcing frequencies of the engine, thereby allowing the engine to operate away from the drivetrain resonant frequency at all engine speeds, while maintaining similar fuel savings, thermal management, and emission characteristics as fixed cylinder deactivation. Additional benefits of dynamic cylinder activation include a reduction in the consecutive number of cycles a given cylinder is deactivated, and more even cylinder usage. Enablement of engine operation without exciting drivetrain resonant frequencies at similar fuel efficiency and emissions as fixed cylinder deactivation makes dynamic cylinder activation a strong candidate to augment the benefits already demonstrated for fixed cylinder deactivation.
Cylinder deactivation is an effective strategy to improve diesel engine fuel efficiency and aftertreatment thermal management when implemented through deactivation of both fueling and valve motion for a set of cylinders. Brake power is maintained by injecting additional fuel into the remaining activated cylinders. The initial deactivation of cylinders can be accomplished in various ways, the two most common options being to trap freshly inducted charge in the deactivated cylinders or to trap combusted gases in the deactivated cylinders. The choice of trapping strategy dictates the in-cylinder pressure characteristics of the deactivated cylinders and has potential to affect torque, oil consumption, and emissions upon reactivation. The effort described here compares these trapping strategies through examination of in-cylinder pressures following deactivation. Proponents of each trapping strategy exist; however, the results discussed here suggest no significant performance differences. As an example, the in-cylinder pressures of both trapping strategies converge as quickly as seven cycles, less than 1 s, after deactivation at curb idle conditions.
Commercial vehicles require continual improvements in order to
meet fuel emission standards, improve diesel aftertreatment system performance and optimize vehicle fuel economy. Aftertreatment systems, used to remove engine NOx, are temperature dependent. Variable valve actuation in the form of cylinder deactivation (CDA) has been shown to manage exhaust temperatures to the aftertreatment system during low load operation (i.e., under 3 - 4 bar BMEP). During cylinder deactivation mode, a diesel engine can have higher
vibration levels when compared to normal six cylinder operation.
The viability of CDA needs to be implemented in a way to manage
noise, vibration and harshness (NVH) within acceptable ranges for
today’s commercial vehicles and drivelines. A heavy duty diesel
engine (inline 6 cylinder) was instrumented to collect vibration data in a dynamometer test cell. Three degrees of linear vibration and one degree of rotational vibration were measured using accelerometers and rotational speed sensors. Historical data analysis showed that the remaining two rotational degrees of freedom were insignificant when considering driveline vibration. The engine was tested using a combination of deactivating two, three and four cylinders (of the six) up to engine loads of approximately 4 bar BMEP in order to quantify system vibration and resonance frequencies. These results were compared to driveline NVH standards to determine the modes of operation that were acceptable over the engine speed and load operating range. A variable CDA implantation strategy for operating the engine over transient engine operation is recommended for this dynamometer operation. Additionally, a theory is provided for operating cylinder deactivation in a commercial diesel vehicle.
Commercial vehicles require continual improvements in greenhouse gas emissions to meet upcoming emission regulations and fleet fuel economy needs. Challenges for future emission standards require technologies for engine exhaust temperature management to deal with low engine load operation for optimal aftertreatment performance. The proposed ultra-low NOx emission standards of 10% of today’s US level (0.2 g/hp-hr) is challenging and requires significant temperature management strategies including heat-up strategies during the cold part of the emission cycle. Heavy duty commercial vehicle applications requires a heat source on the order of 30 kW to achieve aftertreatment temperatures for sufficient NOx reduction. There are technologies that can provide such high heat loads in a short period of time. A diesel exhaust burner is an option for fast heat-up at the expense of fuel economy. Variable valve actuation (VVA) solutions are effective for aftertreatment temperature management including early exhaust valve opening, intake valve closing modulation and cylinder deactivation. Further steps of emission legislation focus on in-service operation, including NOx emission reduction during low load operation. Such low engine load operation may result in exhaust temperatures between 100°C and 250°C, where NOx aftertreatment systems are not effective. Thus, technologies are needed to raise the exhaust temperature under such conditions. The use of VVA to vary the air-excess ratio in the cylinder is a fuel efficient method to increase exhaust temperature under low load conditions. Methods of intake air throttling are capable measures such as cylinder deactivation and Miller cycle. Cylinder deactivation during low load engine operation shows a marked increase in exhaust temperature by approximately 100°C which moves aftertreatment systems to a more optimal region, typically significantly above 250°C while also offering fuel economy benefits. The addition of a high efficiency boosting system enables Miller cycle operation to improve fuel economy. Thus, the use of VVA is a leading technology combining the future requirements to simultaneously reduce NOx and fuel consumption. This paper will show the benefits of variable exhaust valve opening, intake valve closing modulation with and without boosting, and cylinder deactivation for meeting future emission regulations and fuel economy needs. Finally, solutions combining VVA and engine braking are provided.
The most recent 2010 emissions standards for heavy-duty engines have established a tailpipe limit of oxides of nitrogen (NOX) emissions of 0.20 g/bhp-hr. However, it is projected that even when the entire on-road fleet of heavy-duty vehicles operating in California is compliant with 2010 emission standards, the National Ambient Air Quality Standards (NAAQS) requirement for ambient particulate matter and Ozone will not be achieved without further reduction in NOX emissions. The California Air Resources Board (CARB) funded a research program to explore the feasibility of achieving 0.02 g/bhp-hr NOX emissions. This paper details the thermal management strategies employed by the engine and supplemental exhaust heat addition device as was needed to achieve Ultra-Low NOX levels on a heavy-duty diesel engine with an advanced technology aftertreatment solution Further development is necessary for optimizing vocational test cycle emissions, but the results presented here demonstrate a potential pathway to achieving ultra-low NOX emissions on future heavy duty vehicles.
The 2010 emissions standards for heavy-duty engines have established a limit of oxides of nitrogen (NOX) emissions of 0.20 g/bhp-hr. However, the California Air Resource Board (ARB) projects that even when the entire on-road fleet of heavy-duty vehicles operating in California is compliant with 2010 emission standards, the National Ambient Air Quality Standards (NAAQS) requirement for ambient particulate matter (PM) and Ozone will not be achieved without further reduction in NOX emissions. The California Air Resources Board (CARB) funded a research program to explore the feasibility of achieving 0.02 g/bhp-hr NOX emissions. This paper details the work performed on a heavy-duty diesel engine to explore the feasibility of various configurations of Traditional Technology (diesel oxidation catalyst-diesel particulate filter-selective catalytic reduction (SCR)) and Advanced Technology (passive NOX adsorber or diesel oxidation catalyst - SCR on Filter - SCR) to demonstrate ultra-low NOX emissions. Active and passive performance modifiers were also evaluated to demonstrate low NOX emissions, including heated dosing, gaseous dosing, and supplemental heat addition devices. The proposed Ultra Low NOX emission levels of 0.02 g/hp-hr require a significant shift in technology application to address cold start NOX emissions. Data are presented showing comparison in NOX reduction capability of the various configurations. All testing was conducted on the FOCAS-HGTR® system, which is a full flow, transient gas reactor bench for testing full sized catalyst systems.
Recent 2010 emissions standards for heavy-duty engines have established a limit of oxides of nitrogen (NOX) emissions of 0.20 g/bhp-hr. However, CARB has projected that even when the entire on-road fleet of heavy-duty vehicles operating in California is compliant with 2010 emission standards, the National Ambient Air Quality Standards (NAAQS) requirement for ambient particulate matter and Ozone will not be achieved without further reduction in NOX emissions. The California Air Resources Board (ARB) funded a research program to explore the feasibility of achieving 0.02 g/bhp-hr NOX emissions. This paper details engine and aftertreatment NOX management requirements and model based control considerations for achieving Ultra-Low NOX (ULN) levels with a heavy-duty diesel engine. Data are presented for several Advanced Technology aftertreatment solutions and the integration of these solutions with the engine calibration. Further development is necessary for optimizing vocational test cycle emissions, but the results presented here demonstrate a potential pathway to achieving ultra-low NOX emissions on future heavy duty vehicles.
Commercial vehicles require continual improvements for meeting fuel emission standards, improving diesel aftertreatment systems and optimizing vehicle fuel economy. Aftertreatment systems are temperature sensitive for removing engine out NOx. Most diesel aftertreatment systems show a marked efficiency improvement above 250°C while efficiency generally improves above 300°C. This poses an efficiency issue for vehicles operated at low load. All commercial vehicles operate in low load operation for a portion of the vehicle duty cycle. Idle temperatures reside in the 100°C to 150°C range while engine torque ratings below 200 Nm (150 ft-lbs) have temperatures below 250°C where the aftertreatment system is below its peak efficiency. Vehicles that spend more time in low load operation need a means to increase the exhaust temperature to enable efficient NOx reduction in the aftertreatment system. Cylinder deactivation (CDA) has been shown to increase diesel engine exhaust temperature by approximately 100°C when operating in half engine mode and more than 100°C with less cylinders. The higher temperature improves aftertreatment NOx reduction performance which offers the potential to save vehicle fuel by increasing engine out NOx levels where the engine operates more fuel efficiently. Additionally, there are inherent fuel economy benefits up to 140 to 180 Nm (100 to 130 ft-lbs) of torque which is independent of the aftertreatment benefits. These benefits can range between 25% and 40% at near idle conditions while slightly higher speeds showed benefits up to 49%. The benefits converge to nominal fuel economy values for normal engine conditions (all cylinders firing) at or around 180 Nm (130 ft-lbs) of torque. Implementing technologies such as CDA for diesel can be used to improve exhaust thermal management during low load operation, World Harmonized Transient Cycle and US Heavy Duty transient emission cycles. This paper will show the benefits of cylinder deactivation for meeting future emission regulations and improving vehicle fuel economy.
Fuel efficient thermal management of diesel engine aftertreatment is a significant challenge, particularly during cold start, extended idle, urban driving, and vehicle operation in cold ambient conditions. Aftertreatment systems incorporating NOx-mitigating selective catalytic reduction and diesel oxidation catalysts must reach ∼250 °C to be effective. The primary engine-out condition that affects the ability to keep the aftertreatment components hot is the turbine outlet temperature; however, it is a combination of exhaust flow rate and turbine outlet temperature that impact the warm-up of the aftertreatment components via convective heat transfer. This article demonstrates that cylinder deactivation improves exhaust thermal management during both loaded and lightly loaded idle conditions. Coupling cylinder deactivation with flexible valve motions results in additional benefits during lightly loaded idle operation. Specifically, this article illustrates that at loaded idle, valve motion and fuel injection deactivation in three of the six cylinders enables the following: (1) a turbine outlet temperature increases from ∼190 °C to 310 °C with only a 2% fuel economy penalty compared to the most efficient six-cylinder operation and (2) a 39% reduction in fuel consumption compared to six-cylinder operation achieving the same ∼310 °C turbine out temperature. Similarly, at lightly loaded idle, the combination of valve motion and fuel injection deactivation in three of the six cylinders, intake/exhaust valve throttling, and intake valve closure modulation enables the following: (1) a turbine outlet temperature increases from ∼120 °C to 200 °C with no fuel consumption penalty compared to the most efficient six-cylinder operation and (2) turbine outlet temperatures in excess of 250 °C when internal exhaust gas recirculation is also implemented. These variable valve actuation-based strategies also outperform six-cylinder operation for aftertreatment warm-up at all catalyst bed temperatures. These benefits are primarily realized by reducing the air flow through the engine, directly resulting in higher exhaust temperatures and lower pumping penalties compared to conventional six-cylinder operation. The elevated exhaust temperatures offset exhaust flow reductions, increasing exhaust gas-to-catalyst heat transfer rates, resulting in superior aftertreatment thermal management performance.
Simultaneous CO2 and NOx Reduction for Medium & Heavy-Duty Diesel Engines Using Cylinder Deactivation
- J E Mccarthy
Enabled Improved Vehicle Fuel Economy and Emissions
- J Mccarthy
Update on the Path to 2027 Emissions Stage 3 Low NOx Program Results,” Global Automotive Management Council
- C Sharp
Impact of Cylinder Deactivation on Diesel Engine Aftertreatment Thermal Management and Efficiency at Highway Cruise Conditions
- X Lu
- C Ding
- A K Ramesh
- G M Shaver
Impact of Cylinder Deactivation at Idle on Thermal Management and Efficiency
- L Roberts
- M Magee
- D Fain
- G Shaver
- E Holloway
- J Mccarthy
- D Nielsen
- E Koeberlein
- R Shute
- D Koeberlein