Investigation of a 2-step Valve Train and its Influence on Combustion by Means of Coupled CFD Simulation 2005-01-0690
A 2-step valve train offers a cost effective alternative to fully variable valve trains. Using the small valve lift, which is usually combined with an early intake closing strategy, reduced pumping losses are opposite to decreasing combustion efficiency due to lower charge motion. To work out the trade off between these two effects an extensive coupled CFD investigation is performed. The 1-D engine model delivering the pumping losses is complemented by an empirical combustion model, that relates combustion duration with residual trapped gas content. The model ensures right prediction of fuel economy. Additionally the influence of a small intake valve event on charge motion can also be demonstrated by 3-D in-cylinder flow simulation.
Citation: Heinrich, C., Scharrer, O., Gebhard, P., and Pucher, H., "Investigation of a 2-step Valve Train and its Influence on Combustion by Means of Coupled CFD Simulation," SAE Technical Paper 2005-01-0690, 2005, https://doi.org/10.4271/2005-01-0690. Download Citation
Christoph Heinrich, Otmar Scharrer, Peter Gebhard, Helmut Pucher
FIAT-GM Powertrain, Technische Universität Berlin
SAE 2005 World Congress & Exhibition
Modeling of SI and Diesel Engines 2005-SP-1969