Cummins cleans up bus gas engine to ‘close to zero’ emissions18 October 2019

Cummins says its L9N natural gas bus engine can now achieve “close to zero emission levels” of NOx and particulate matter, following a number of design enhancements.

The manufacturer says the latest version can lower NOx emissions by 80% below that of the Euro VI standard of 0.46 grams per kilowatt hour (g/kWh), with PM emissions reduction of 90% lower than the 0.01 g/kWh standard.

The design improvements, says Cummins, enable the L9N to reach the ideal stoichiometric combustion point faster than before, and maintain that point more consistently across the engine operating speed range.

New features include strengthened steel pistons, an upgraded electronic control module with a faster processing speed, high precision sensors and a more efficient ignition module.

The three-way catalyst (TWC) aftertreatment has also been upgraded with a larger catalytic surface area and smarter logic for better low temperature control, helping to eliminate emissions during idle, cold starts or frequent stop-start operations.

The aftertreatment is a fully passive ‘fit and forget’ design without the need for active regeneration and requires no AdBlue injection, cleaning or scheduled maintenance intervention.

“The enhancements made to the L9N align with effect date for the stricter phase D requirement of the Euro VI regulations, but we were able to go significantly beyond that to reduce emissions to exceptionally low levels,” confirms Ashley Watton, Cummins’ director for on-highway business Europe.

The L9N can also operate on biomethane without any modifications.

It is available with a 276bhp and 316bhp rating, and has a maximum torque of 1,356 Nm at 1,300rpm.

The engine is installed in several buses on show at this week’s Busworld Europe event, in Brussels.

Laura Cork

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