Diesel engine optimization and exhaust thermal management by means of variable valve train strategies

Due to the need to achieve a fast warm-up of the after-treatment system in order to fulfill the pollutant emission regulations, a growing interest has arisen to adopt variable valve timing technology for automotive engines. Several variable valve timing strategies can be used to achieve an increment...

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Bibliographic Details
Published in:International journal of engine research 2021-04, Vol.22 (4), p.1196-1213
Main Authors: Arnau, Francisco J, Martín, Jaime, Pla, Benjamín, Auñón, Ángel
Format: Article
Language:English
Subjects:
Actuation
Automobiles
Automotive engines
Diesel engines
Emission analysis
Engine valves
Fuel economy
Gas dynamics
Light duty vehicles
Low speed
Nitrogen oxides
Optimization
Pollutants
Residual gas
Thermal management
Tradeoffs
Valve trains
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Summary:Due to the need to achieve a fast warm-up of the after-treatment system in order to fulfill the pollutant emission regulations, a growing interest has arisen to adopt variable valve timing technology for automotive engines. Several variable valve timing strategies can be used to achieve an increment in the after-treatment upstream temperature by increasing the residual gas amount. In this study, a one-dimensional gas dynamics engine model has been used to carry out a simulation study comparing several exhaust variable valve actuation strategies. A steady-state analysis has been done in order to evaluate the potential of the different strategies at different operating points. Finally, the effect on the after-treatment warm-up, fuel economy and pollutant emission levels was evaluated over the worldwide harmonized light vehicles test cycle. As a conclusion, the combination of an advanced exhaust (early exhaust valve opening and early exhaust valve closing) and a delayed intake (late intake valve opening and late intake valve closing) presented the best trade-off between exhaust temperature increment and fuel consumption, which achieved a mean temperature increment during low-speed phase of the worldwide harmonized light vehicles test cycle of 27 °C with a fuel penalty of 6%. The exhaust valve re-opening technique offers a worse trade-off. However, the exhaust valve re-opening leads to lower nitrogen oxide (29% less) and carbon monoxide (11% less) pollutant emissions.
ISSN:1468-0874
2041-3149
DOI:10.1177/1468087419894804