Application and Potential of an Ultra Lean, Low NOₓ Combustion to Reduce Emissions of Nitrogen Oxides and Fuel Consumption

Authors

Dr.-Ing. B. Mahr, MAHLE Powertrain Ltd., Northampton; H. Blaxill, Dr. W. Attard, MAHLE Powertrain LLC, Novi, MI, USA

Year

2012

Print Info

Fortschritt-Berichte VDI, Reihe 12, Nr. 735

Summary

In order to meet future global emissions goals, in the short to medium term it will be necessary to continue to improve the fuel consumption of the spark ignited gasoline engine. Gasoline engine downsizing is the dominant technology being implemented in both the EU and US. In addition technologies such as variable valvetrains and stratified lean combustion have been implemented by some manufacturers. This paper considers the application of a homogenous ultra lean combustion system to current and future engine technologies. The ultra lean combustion system is achieved via a high energy Turbulent Jet Ignition system. Turbulent Jet Ignition is an advanced spark initiated prechamber combustion system. The ultra lean combustion system has been shown to achieve stable part load, lambda = 2 operation resulting in good BSFC (brake specific fuel consumption), high thermal efficiencies and low NOx emissions. Furthermore the improved knock resistance of the system allows, due to the distributed ignition sites, improvements in the compression ratio or a synergy with boosted applications. The design of the system will be presented and the application to demonstrator engines shown. Detailed test results from naturally aspirated engines will be presented and the application to boosted engines demonstrated.

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