Design and Benefits of Dynamic Skip Fire Strategies for Cylinder Deactivated Engines

Wilcutts, Mark; Switkes, Joshua P.; Shost, Mark; Tripathi, Adya

doi:10.4271/2013-01-0359

Cited by 75 publications

(40 citation statements)

References 7 publications

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“…The obvious benefit of CDA is fuel economy as the result of reduced pumping losses. There are further benefits due to increased exhaust temperature under partial loading, yielding improved after-treatment efficiency for diesel engines which helps the three-way catalyst technology [3,4].…”

Section: -Introductionmentioning

confidence: 99%

Effect of cylinder deactivation on the tribo-dynamics and acoustic emission of overlay big end bearings

Mohammadpour

Rahmani

Rahnejat

2014

Proceedings of the Institution of Mechanical Engineers, Part K:

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The paper presents an integrated tribo-dynamics analysis of elliptic bore overlay big end bearings of internal combustion engines. The analysis focuses on bearing stability, frictional power loss and acoustic emission from these bearings, particularly with cylinder deactivation (CDA) with larger fluctuations in engine loading. The integrated approach represents a multiphysics analysis, not hitherto reported in literature, particularly under CDA. The analysis shows that CDA makes marginal differences in parasitic frictional losses in engine bearing performance and any significant gain would depend on the brake specific fuel consumption. It is also shown that sufficient swept volume with retained residual exhaust gas charge within the deactivated cylinders can ensure bearing whirl stability. Partially deactivated engine configurations exhibit a lower average steady noise emission, but with a higher degree of transient content. This suggests that there would be a greater contribution to engine rumble with deactivated cylinders. Measures along the semi-major and semi-minor directions of elliptic bore KeywordsCentre of mass of the connecting rodContact clearance along the semi-major axis Contact clearance along the semi-minor axis

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Section: -Introductionmentioning

confidence: 99%

Effect of cylinder deactivation on the tribo-dynamics and acoustic emission of overlay big end bearings

Mohammadpour

Rahmani

Rahnejat

2014

Proceedings of the Institution of Mechanical Engineers, Part K:

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“…These often contradictory attributes have led to the downsizing concept and higher output power-to-weight ratio engines. Additionally, there is a growing trend towards the use of emerging technologies such as variable valve actuation and cylinder deactivation (CDA) [1][2][3]. There is also progressively an interest in the concept of stop-start in congested urban environments.…”

Section: Introductionmentioning

confidence: 99%

Big End Bearing Losses with Thermal Cavitation Flow Under Cylinder Deactivation

et al. 2015

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The paper presents a mixed thermo-hydrodynamic analysis of elliptic bore bearings using combined solution of Navier-Stokes, continuity and energy equations for multi-phase flow conditions. A vapour transport equation is also included to ensure continuity of flow in the cavitation region for the multiple phases as well as Rayleigh-Plesset to take into account the growth and collapse of cavitation bubbles. This approach removes the need to impose artificial outlet boundary conditions in the form of various cavitation algorithms which are often employed to deal with lubricant film rupture and reformation. The predictions show closer conformance to experimental measurements than have hitherto been reported in the literature. The validated model is then used for the prediction of frictional power losses in big end bearings of modern engines under realistic urban driving conditions. In particular, the effect of cylinder deactivation (CDA) upon engine bearing efficiency is studied. It is shown that bigend bearings losses contribute to an increase in the brake specific fuel consumption with application of CDA contrary to the gains made in fuel pumping losses to the cylinders. The study concludes that implications arising from application of new technologies such as CDA should also include their effect on tribological performance.

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“…DSF incorporates any-time, any-cylinder deactivation and can continuously vary the number of cylinders firing, along with cylinder load to provide for flexible control of acoustic and vibrational excitations from the engine. The fuel economy benefits of DSF are shown to be 14-17% composite fuel economy improvement over standard V8 operation [1]. Figure 2.…”

Section: Introductionmentioning

confidence: 97%

Methods of Evaluating and Mitigating NVH when Operating an Engine in Dynamic Skip Fire

Serrano

Routledge

et al. 2014

SAE Int. J. Engines

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Cylinder deactivation technology has been demonstrated as a durable and reliable means to achieve improved fuel economy in spark ignited gasoline engines. Notable current production systems include GM's Active Fuel Management (AFM) [2] and Chrysler's Multi-Displacement System (MDS) [3], both deployed on production V8 engines. Recently increased Corporate Average Fuel Economy standards in the US and CO 2 targets in Europe have driven application of cylinder deactivation to smaller displacement and lower cylinder count engines. This can be seen with Volkswagen's application of Active Cylinder Technology (ACT) in its new 1.4L turbo GDi engine in 2013.Cylinder deactivation achieves fuel economy improvement by operating a reduced number of cylinders at a higher operating load per cylinder to produce the same engine torque output. These systems are examples of two-mode deactivation where either full cylinder count or half cylinder count is provided, V8 or V4 mode and L4 or L2 mode as shown in Figure 1. Such systems are even firing, which means a skipped cylinder event follows a firing cylinder and the firing sequence or pattern is completed with each engine cycle. ABSTRACTCylinder deactivation is a technology seeing increased automotive deployment in light of more demanding fuel economy and emissions requirements. Examples of current production systems include GM's Active Fuel Management and Chrysler's Multi-Displacement System, both of which provide one fixed level of deactivation. Dynamic Skip Fire (DSF), in which the number of fired cylinders is continuously varied to match the torque demand, offers significantly increased fuel savings over a wider operating range than the current production systems. One of the biggest challenges in implementing cylinder deactivation is developing strategies to provide acceptable Noise, Vibration and Harshness (NVH); this paper discusses those challenges and the methodologies developed. This work covers theoretical root causes; proposed metrics to quantify the NVH level; algorithmic and physical mitigation methods; and both subjective and objective evaluation results. CITATION:Serrano, J., Routledge, G., Lo, N., Shost, M. et al., "Methods of Evaluating and Mitigating NVH when Operating an Engine in Dynamic Skip Fire," SAE Int. J. Engines 7(3):2014,

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Design and Benefits of Dynamic Skip Fire Strategies for Cylinder Deactivated Engines

Cited by 75 publications

References 7 publications

Effect of cylinder deactivation on the tribo-dynamics and acoustic emission of overlay big end bearings

Effect of cylinder deactivation on the tribo-dynamics and acoustic emission of overlay big end bearings

Big End Bearing Losses with Thermal Cavitation Flow Under Cylinder Deactivation

Methods of Evaluating and Mitigating NVH when Operating an Engine in Dynamic Skip Fire

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