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Cummins unveils new QSM12 without EGR at BAUMA

15 April 2013

At the BAUMA show in Munich, Cummins revealed their new QSM12 with up to 512 hp (382 kW) output for heavy-duty applications. The 6-cylinder, 12-liter engine has been designed to meet US Environmental Protection Agency (EPA) Tier 4 final and EU Stage IV emission regulations. The engine meets the Tier 4/Stage IV standards without the use of cooled exhaust gas recirculation (EGR) and relies on selective catalytic reduction (SCR) technology for NOx reduction.

Through the elimination of EGR, the new QSM12 restored the envelope size of the QSM11, Tier 3/Stage IIIA predecessor and returned to the simplicity of a wastegated turbocharger. The heat rejection has been reduced by over 40% compared with engines using cooled EGR.

The elimination of EGR combined with light-weight design—a sculptured block and composite materials for the oil pan and valve cover—enabled a low engine weight of 1,900 lb (862 kg) and a high power-to-weight ratio of 0.27 hp per lb (0.44 kW per kg).

Elimination of EGR is a new trend and cost-saving opportunity in heavy-duty engines that may be extended onto highway truck engines in the future. The technology has been introduced first on nonroad engines because nonroad emission regulations include no OBD requirements. Highway engine applications with OBD requirements put higher demands on the SCR aftertreatment, including high conversion efficiency and low system-to-system variability.

With ratings from 335 hp to 512 hp (250-382 kW), the QSM12 is intended for such applications as wheel loaders, excavators, cranes and material handling, road building equipment, compressors, screening and crushing machines. The engine incorporates Cummins Xtra-High Pressure Injection (XPI) fuel system, derived from the larger QSX15 Tier 4 final engine, which contributes to a high peak torque of 1700 lb-ft (2305 Nm).

The exhaust aftertreatment of the QSM12 includes a diesel particulate filter (DPF) and an SCR system. The SCR system, developed by Cummins, is a next-generation design with a Cu-zeolite based catalyst capable of over 95% NOx conversion. The system uses “advanced sensors providing full closed-loop control”, said Cummins, suggesting that the system may be using both NOx and NH3 sensors. The system utilizes the Ecofit™ UL2 urea doser supplied by Cummins Emission Solutions (CES). The combined fuel + urea (DEF) operating cost is lower than that of the previous QSX11.9 engine at Tier 4 interim.

The DPF operates as a near passive device, with automatic active regeneration occurring less than 1% of engine running time. The “heavy-duty DPF” has no impact on equipment operation, with the machine continuing to work as normal during active regeneration. The DPF provides an additional margin of PM emission control at higher engine loads, to realize better transient response, said Cummins.

Also at BAUMA, Cummins introduced the new Tier 4/Stage IV, 3.8 liter QSF3.8 engine, with a power output extending from 85 hp to 132 hp (63-98 kW). The engine uses an SCR-only aftertreatment system, with no DOC or DPF. While the QSF3.8 uses EGR, the EGR rates have been reduced. The engine uses a wastegated turbocharger.

Source: Cummins