Skip cycle method with a valve-control mechanism for spark ignition engines

Cemal Baykara, O. Akin Kutlar*, Baris Dogru, Hikmet Arslan

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13 Atıf (Scopus)


The efficiency decrease of spark ignition (SI) engines under part-load conditions is a considerable issue. Changing the effective stroke volume based on the load level is one of the methods using to improve the part-load efficiency. In this study, a novel alternative engine valve control technique in order to perform a cycle without gas exchange (skip cycle), is examined. The goal of skip cycle strategy is to reduce the effective stroke volume of an engine under part load conditions by skipping several of the four stroke cycles by cutting off the fuel injection and simultaneously deactivating the inlet and exhaust valves. To achieve the same power level in the skip cycle, the cylinder pressure level reaches higher values compared to those in a normal four stroke cycle operation, but inherently not higher than the maximum one at full load of normal cycle. According to the experimental results, the break specific fuel consumption (BSFC) was reduced by 14–26% at a 1–3 bar break mean effective pressure (BMEP) and a 1200–1800 rpm engine speed of skip cycle operation, in comparison to normal engine operation. The significant decrease in the pumping work from the gas exchange is one of the primary factors for an increase in efficiency under part load conditions. As expected, the fuel consumption reduction rate at lower load conditions was higher. These experimental results indicate a promising potential of the skip cycle system for reducing the fuel consumption under part load conditions.

Orijinal dilİngilizce
Sayfa (başlangıç-bitiş)134-146
Sayfa sayısı13
DergiEnergy Conversion and Management
Yayın durumuYayınlandı - 2017

Bibliyografik not

Publisher Copyright:
© 2017 Elsevier Ltd


The frictional mean effective pressure (FMEP) increased with the engine speed in both the N- and NS-modes. In the normal mode of operation, the FMEP was not significantly affected by the load. Conversely, in the skip cycle mode of operation, the FMEP was significantly reduced by the load increase.

FinansörlerFinansör numarası
Foundation for Middle East Peace

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