Electrified Dynamic Skip Fire (eDSF): Design and Benefits

Wilcutts, Mark; Nagashima, Masaki; Eisazadeh-Far, Kian; Younkins, Matthew; Confer, Keith

doi:10.4271/2018-01-0864

Cited by 18 publications

(6 citation statements)

References 4 publications

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“…This also leads to an engine fuel consumption reduction, however, a sophisticated control algorithm is required to minimize vibrations induced by the uneven firing order. With the addition of an electric motor to the power train, vibrations induced by dynamic skip fire are reduced by almost 50%, as reported in [45]. Another benefit of the skip-cycle strategy is the increased exhaust gas temperature, which supports the exhaust aftertreatment system to reach and keep optimal operating conditions in situations such as cold-start or elongated low-load operations.…”

Section: Introductionmentioning

confidence: 82%

Increased Internal Combustion Engine Efficiency with Optimized Valve Timings in Extended Stroke Operation

et al. 2021

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Spark-ignited internal combustion engines are known to exhibit a decreased brake efficiency in part-load operation. Similarly to cylinder deactivation, the x-stroke operation presented in this paper is an adjustable form of skip-cycle operation. It is an effective measure to increase the efficiency of an internal combustion engine, which has to be equipped with a variable valve train to enable this feature. This paper presents an optimization procedure for the exhaust valve timings applicable to any valid stroke operation number greater than four. In the first part, the gas spring operation, during which all gas exchange valves are closed, is explained, as well as how it affects the indicated efficiency and the blow-by mass flow. In the second part, a simulation model with variable valve timings, parameterized with measurement data obtained on the engine test, is used to find the optimal valve timings. We show that in 12-stroke operation and with a cylinder load of 5 Nm, an indicated efficiency of 34.3% is achieved. Preloading the gas spring with residual gas prevents oil suction and thus helps to reduce hydrocarbon emissions. Measurements of load variations in 4-, 8-, and 12-stroke operations show that by applying an x-stroke operation, the indicated efficiency remains high and the center of combustion remains optimal in the range of significantly lower torque outputs.

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Section: Introductionmentioning

confidence: 82%

Increased Internal Combustion Engine Efficiency with Optimized Valve Timings in Extended Stroke Operation

et al. 2021

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“…They unveiled their specific cylinder deactivation strategy in 2013. 12 This was followed by other publications on this topic in Chien et al 13 (air flow dynamics during DSF), 14 (fuel saving of 18% in a drive cycle for a SI engine), 15 (hybridization of DSF for fuel saving and NVH improvement), 16 (experimental investigation of cylinder volumetric efficiency during DSF), 17 and (valve timing optimization during DSF). Their control system decides whether to fire or skip a cylinder immediately prior to each firing event.…”

Section: Introductionmentioning

confidence: 93%

Dynamic cylinder deactivation: Thermodynamic mapping for the case of stoichiometric SI ICE

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Mares

2022

International Journal of Engine Research

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Conventional cylinder deactivation has been improving internal combustion efficiency for decades. It provides benefits for any internal combustion engine, particularly engines with high number of cylinders. The level of engine displacement reduction depends on the number of cylinders that may be deactivated during operation. This limits the potential benefit. Theoretically, maximum benefit of cylinder deactivation would require assignment of specific displacement reduction to each engine operating point. Dynamic cylinder deactivation is a new approach, which does not continuously deactivate cylinders, but deactivates selected engine cycles. This allows to dynamically reduce engine displacement and to assign optimum displacement reduction to each operating point. The paper deals with the one-dimensional thermodynamic simulation of the dynamic cylinder deactivation applied to a small displacement four-cylinder gasoline engine, points out crucial attributes of this new approach and compares it with baseline engine layouts and with the conventional cylinder deactivation as well. The research concludes that the dynamic cylinder deactivation improves the fuel consumption for engines loads BMEP < 5 bar. Deactivation strategy with the lowest trapped mass value in the deactivated cycle shows the most benefit.

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“…The deactivation of individual cylinders for extended periods of time is avoided. One of the advantages of having switchable elements on all cylinders is a reduction in the oxygen saturation of the catalyst during deceleration fuel cut events [86]. Because of the highpressure oscillations, it is not possible to trap exhaust gases inside the cylinder.…”

Section: One Cyclementioning

confidence: 99%