Variables Ventiltriebkonzept  zur Erfüllung zukünftiger Emissionsstandards  von Dieselfahrzeugen

Elicker, Michael; Christgen, Wolfgang; Kiyanni, Jahaazeb; Brauer, Maximilian

doi:10.1007/s35146-020-0608-y

Cited by 4 publications

(4 citation statements)

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“…The three main effects of the Miller cycle are a reduction in fresh charge, a reduction in pumping loss, and a reduced compression ratio. The effect of an early IVC on the fresh charge is already included in the formulation of equations ( 19) and (20). Hence, no additional Figure 9.…”

Section: Miller Cyclementioning

confidence: 99%

“…Most of the strategies mentioned increase the engineout enthalpy at the expense of increased fuel consumption. 3,6,7,[17][18][19][20][21][22][23] Alternatively, various cylinder deactivation strategies can also be used to increase exhaust enthalpy. 7,8,[24][25][26][27][28] In comparison to the valve timing strategies mentioned, cylinder deactivation results in a higher engine-out temperature, but it also lowers engine mass flow and is therefore better suited for stay-warm operation.…”

Section: Introductionmentioning

confidence: 99%

“…To the best of the authors' knowledge no simple methodology exists that allows to quantify the advantages of including a VVT on an existing engine layout. Most experimental publications 2,3,6,7,17,[20][21][22][24][25][26][27][28] assess the advantages gained on a specific engine, which are not directly transferable to other engines. Other publications 2,5,11,19 use complex CFD simulation tools that require proprietary software and in-depth knowledge of fluid dynamics.…”

Section: Introductionmentioning

confidence: 99%

“…24 Several authors have already demonstrated that VVT strategies offer advantages for the complete engine system during various transient cycles. 19,20,24,25 However, to the best of our knowledge no author has compared early IVC, early EVO, and cylinder deactivation simultaneously. The advantages mentioned above focus on CI engines with conventional heterogeneous combustion only.…”

Section: Introductionmentioning

confidence: 99%

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A method to quantify the advantages of a variable valve train for CI engines

Moretto,

Hänggi,

Omanovic

et al. 2023

International Journal of Engine Research

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Today’s CI engines are subject to strict regulations of pollutant emissions and ambitious fuel consumption targets. Therefore, the interaction between the engine and the exhaust aftertreatment system (ATS) has become increasingly important. Numerous studies have shown that a variable valve train (VVT) improves the interaction between engine and ATS. However, most of these studies either quantify the advantage on a specific engine or only present complex CFD models, such that the results are not easily transferable to different engines. Thus, engine manufacturers cannot directly use these results to assess the advantage of various VVT strategies for their engines. In this paper, we propose a cycle-discrete cylinder model based on first principles which allows to simulate various VVT strategies. In contrast to present methods based on CFD, the proposed cylinder model can be realized with the equations presented. Furthermore, the model is identified with measurement data of an engine without a VVT. A separate engine, which is retrofitted with a fully VVT, is used to validate the proposed modeling approach. Using the identified model in combination with a mean-value model of the air path, we are able to simulate the effects of early intake valve closing, early exhaust valve opening, and cylinder deactivation for a complete CI engine that has no VVT installed. The model is then used to highlight the advantage of a VVT for two scenarios at part-load operation. At cold start, where the temperature of the ATS must be increased quickly, variable valve timing achieves higher enthalpy flows to the ATS while also lowering engine-out NOx emissions when compared to a standard engine strategy. If the ATS is at the operating temperature, cylinder deactivation achieves significantly higher enthalpy flows which prevents the ATS from cooling down. In addition, cylinder deactivation also lowers fuel consumption and engine-out NOx emissions.

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Section: Miller Cyclementioning

confidence: 99%