Cummins Heavy-Duty Engine Boasts Low Emissions

Cummins Inc., Columbus, Ind., announced at ConExpo that the Heavy-Duty QSX engine will be available with a fully integrated air intake to exhaust aftertreatment system to meet U.S. EPA Tier 4 Interim and European Stage IIIB off-highway emissions regulations in January 2011. The Tier 4 QSX increases displacement to 16 liters and incorporates the XPI high pressure common rail fuel system to enhance power output and engine response.

Low emissions levels are achieved with Cummins' particulate filter exhaust aftertreatment, which reduces Particulate Matter (PM) emissions by 90 percent, and cooled exhaust gas recirculation, which reduces oxides of nitrogen (NOx) by 45 percent. The Tier 4 QSX also features a Cummins crankcase filter to eliminate blowby gas emissions.

Performance-enhancing Tier 4 technology brings an increase in QSX power output with an unrestricted top rating of 650 hp compared to 600 hp for the current Tier 3 QSX. Ratings will extend down to 400 hp to cover a broad range of heavy-duty applications. Peak torque is increased by 12 percent to 2,150 foot-pounds with faster torque delivery available across the engine rpm range.

“The next-generation Tier 4 QSX goes beyond meeting very low emissions levels to also offer higher levels of heavy-duty productivity than the Tier 3 QSX,” said Ric Kleine, vice president, Cummins off-highway business. “The QSX will continue to be the heavy-duty engine of choice for high-power equipment with very demanding duty cycles. We have been able to increase engine power and improve engine response for Tier 4 by increasing displacement and incorporating high-performance technologies such as Cummins XPI high pressure common rail fuel system, a variable geometry turbocharger and the new direct flow air filtration system. These subsystems are designed to offer an equivalent level of dependability to match that of the proven heavy-duty QSX base engine platform.

“While cooled EGR is primarily employed to reduce NOx emissions, we can also utilize this process to influence the combustion formula and realize fuel efficiency improvements. This will achieve up to 5 percent higher fuel efficiency for the Tier 4 QSX compared to Tier 3, depending on rating and duty cycle,” added Kleine.

Cummins XPI fuel system enables multiple injection events with high fuel injection pressure across all engine rpm speeds to enable both cleaner combustion and improved engine response. The XPI fuel system is complemented by a Cummins variable geometry turbocharger with a sliding-nozzle design. The nozzle continuously varies the airflow boost to precisely match engine rpm and load demands.

The Cummins particulate filter replaces the muffler in the exhaust stream and offers equivalent noise reduction qualities. The filter is especially strengthened against shock loads and vibration to meet the most severe off-highway operating conditions.

The particulate matter collects on the filter and is gradually oxidized by catalytic passive regeneration. With some duty cycles, PM accumulation rate may eventually exceed oxidation rate, and a short active regeneration is initiated by the engine electronic control module utilizing the XPI fuel system and Variable Geometry Turbocharger.

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