49 - 74 Horsepower Engines
Cummins 49 – 74 horsepower QSF2.8 engine achieve EPA Tier 4 Final and EU Stage IV emissions standards with the Cummins Diesel Oxidation Catalyst (DOC). The DOC enables a smaller, easier and more flexible equipment installation than Diesel Particulate Filters (DPF) typically used by many other engines below 75 hp looking to meet the Tier 4 Final/Stage IIIB requirement for near-zero Particulate Matter (PM) emissions. The catalyst is a flow-through device requiring no ash-cleaning service, no sensors and no operational lamps in the equipment cab.
Efficient, fully passive PM reduction is achieved with catalytic coating, substrate and sizing that are uniquely tailored for the QSF2.8 engine. The catalyst can be close-coupled to the engine or mounted off-engine for a highly flexible installation solution.
75 – 400 Horsepower Engines
Cummins QSF2.8 and QSF3.8 engines achieve 2014 EPA Tier 4 Final and EU Stage IV standards by combining Cummins Diesel Oxidation Catalyst with Selective Catalytic Reduction (DOC-SCR). The DOC-SCR system will be utilized by the QSF3.8, QSB4.5, QSB6.7, and QSL9 engines to offer a common aftertreatment solution from 75 hp to 400 hp (56 kW to 298 kW). For certain applications, Cummins QSF3.8 can also be paired with an SCR-only aftertreatment system.
The SCR system developed by Cummins for Tier 4 Final, incorporates a copper zeolite-based catalyst capable of up to 95 percent NOx conversion and able to operate more efficiently at lower temperatures. The system features advanced sensors to provide full closed-loop control. Diesel Exhaust Fluid (DEF) dosing levels are minimized with enhanced mixing in the decomposition pipe.
The DOC is positioned in front of the SCR in the exhaust stream, and provides easier and more flexible installation options. The DOC-SCR aftertreatment will be available in multiple configurations, including switchback, horizontal and vertical. Optimization work will continue to refine aftertreatment packaging and evaluate innovative solutions to further enhance installation flexibility. Efficient PM reduction is achieved with a catalytic coating, substrate and sizing that are uniquely tailored for the Cummins engine platform. By passively oxidizing PM from the exhaust stream, the DOC is a maintenance-free "fit and forget" device offering an inherent operational simplicity ideally suited for rental equipment applications.
400 – 751 Horsepower Engines
Cummins QSG12 and QSX15 Heavy-Duty products meet EPA Tier 4 Final and EU Stage IV emissions with an ultra-clean aftertreatment system combining Cummins Diesel Particulate Filter with Selective Catalytic Reduction (DPF-SCR). The DPF incorporates both a diesel oxidation catalyst and the wall-flow filter, providing an additional margin of PM emissions control at the higher engine loads and power outputs of heavy-duty engines. With this higher PM filtration efficiency, the engine combustion can be formulated to increase power density and lower fuel consumption. The integration of SCR into the exhaust aftertreatment allows the DPF to reduce the frequency and duration of active regenerations below 1 percent of equipment operating time, creating a virtually full-time passive device.
>751 Horsepower Engines
The Cummins QSK Series of high horsepower 19-liter to 78-liter engines move forward to meet the EPA Tier 4 Final 2015 off-highway emissions with a combination of clean in-cylinder combustion and integrated Selective Catalytic Reduction (SCR) aftertreatment. Highly efficient PM reduction in-cylinder eliminates the need for either a diesel oxidation catalyst or diesel particulate filter aftertreatment in the exhaust stream.
The QSK high-horsepower engines with the new SCR clean exhaust system achieve very low emissions while retaining the exceptional power output and in-service dependability of the current QSK engines - proven in the highest load factor duty cycles. Cummins clean in-cylinder combustion for Tier 4 Final realizes significantly lower overall cost of operation, with fuel efficiency improved by up to 5 percent over Tier 2 engines, depending on the equipment duty cycle.
Our next-generation QSK engines with integrated SCR aftertreatment are designed as a drop-in replacement for simpler machine installation and assembly. Designed and manufactured by Cummins Emission Solutions, the SCR clean exhaust system further demonstrates the added value of our single source, integration capability. By focusing NOx reduction within the exhaust rather than during in-cylinder combustion, Cummins avoids the need to make any major change to the external engine platform. Using SCR also leaves a much higher performance threshold in-cylinder in order to focus on Particulate Matter (PM) reduction and improve fuel-efficiency.
The SCR aftertreatment operates as a fully passive, flow-through system and is capable of high NOx conversion with low backpressure, enabling enhanced fuel economy. SCR logic control is driven by the QSK electronic engine management system, upgraded with extra processing power for Tier 4 Final so that the engine and SCR aftertreatment operate as a single, integrated system.