Tier 4 Interim Emissions Technology

Cummins Diesel Oxidation Catalyst - A "Fit & Forget" Solution

Cummins Compact CatalystCummins 6-cylinder, QSB6.7 engine with ratings up to 173 hp (129 kW) and 4-cylinder, QSB4.5 and QSB3.3 engines ranging from 85-hp to 163-hp (63-126 kW) will meet the 2012 low emissions standards with an integrated Cummins Diesel Oxidation Catalyst exhaust aftertreatment and a cooled exhaust gas recirculation (EGR) system incorporated with the engine.

The cooled EGR system enables more fuel efficient, clean combustion to reduce Oxides of Nitrogen, while the Diesel Compact Catalyst reduces particulate matter (PM) from engine exhaust by simple, flow-through passive oxidation.

Particulate aftertreatment technology is new to the off-highway equipment industry – but it is not new to Cummins. The Diesel Oxidation Catalyst represents the latest evolution of aftertreatment, manufactured by Cummins Emission Solutions for over fifteen years. The maintenance-free catalyst provides the installation simplicity needed for Tier 4 Interim engines below 174-hp (130 kW). The catalyst removes PM by a process of simple, passive oxidation.  

Cummins Diesel Particulate Filter - Meeting Low Emissions With The Right Technology

Cummins Particulate Filter cutaway
Cummins QSX15, QSX11.9, QSL9 and QSB6.7 engines ranging from 174-hp to 600-hp (130-447 kW) will meet the 2011 low emissions standards with an integrated Diesel Particulate Filter (DPF) exhaust aftertreatment and a cooled exhaust gas recirculation (EGR) system incorporated with the engine.

The cooled EGR system enables clean combustion with NOx reduced by 45% compared to Tier 3, while the DPF exhaust aftertreatment system reduces particulate matter by over 90% from engine exhaust.    

Exhaust flows out of the engine and into the DPF. It passes through the DOC and then into the DPF where PM is collected on the walls of the DPF. The PM collected is then oxidized to remove it from the DPF. This is known as regeneration.

When operating conditions maintain sufficient exhaust temperatures, the DPF is continually self-regenerating. This is known as passive regeneration and results in clean exhaust out of the tailpipe. On very infrequent occasions, an active self-regeneration is required to remove a build-up of PM in the DPF, due to insufficient exhaust temperatures.

Cummins Diesel Particulate Filter replaces the Tier 3 muffler and provides equivalent or better sound reduction.  The Diesel Particulate Filter consists of four sections: an inlet, a Diesel Oxidation Catalyst (DOC), the DPF, and an outlet.

Cummins VGT Variable Geometry Turbocharger

VGT Turbocharger
In order to control both NOx and particulate emissions accurately, the amount of recirculated exhaust gas and air has to be precisely metered into the engine under all operating conditions.

For Cummins Tier 4/Stage IIIB 174-751 hp (130-560 kW) products, this has driven the use of variable geometry turbochargers. The Cummins VGT™ Turbocharger is used in concert with an EGR control valve to accurately meter the cooled exhaust gas into the intake system, increasing performance and improving fuel economy. Cummins VGT™ Variable Geometry Turbocharger, with a unique patented one-piece sliding-nozzle design, precisely adjusts the airflow delivered to the engine. This combines the benefits of a small and a large turbocharger in a single unit.

The sliding nozzle varies the exhaust gas flow into the turbine wheel to provide rapid boost at low engine rpm and then maintain high boost at higher rpm.

Benefits of Cummins VGT Turbocharger
  • Excellent transient response
  • Improved fuel economy
  • Increased useful engine operating speed range
  • Proven durable design
  • Reduced engine swept volume and package size for a given rating
  • Helps control Exhaust Gas Recirculation (EGR) to meet emissions regulations