Cummins Inc.’s heavy-duty QSX engine will be available with a fully integrated air intake to exhaust aftertreatment system to meet U.S. EPA Tier IV Interim and European Stage IIIB off-highway emissions regulations in January 2011.
The Tier IV QSX increases displacement to 16 L and incorporates the XPI high pressure common rail fuel system to enhance power output and engine response.
Very low emissions levels are achieved with Cummins particulate filter exhaust aftertreatment that reduces particulate matter (PM) emissions by 90 percent and cooled exhaust gas recirculation that reduces nitrous oxide (NOx) by 45 percent.
The Tier IV QSX also features a Cummins crankcase filter to eliminate blowby gas emissions.
Tier IV technology brings a significant increase in QSX power output with an unrestricted top rating of 650 hp (485 kW) compared to 600 hp (447 kW) for the current Tier III QSX. Ratings will extend down to 400 hp (298 kW) to cover a broad range of heavy-duty applications.
Peak torque is increased by 12 percent to 2,150 lb-ft (2,915 N.m) with faster torque delivery available across the engine rpm range.
“The next-generation Tier IV QSX goes beyond meeting very low emissions levels to also offer higher levels of heavy-duty productivity than the Tier III QSX,” said Ric Kleine, vice president of 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 IV 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 IV QSX compared to Tier III, depending on rating and duty cycle,” Kleine added.
Cummins XPI fuel system enables multiple injection events with very 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.
Particulate Filter Aftertreatment
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 using the XPI fuel system and variable geometry turbocharger.
Cummins ability to design, build and integrate the complete Tier IV QSX engine system from air intake to exhaust aftertreatment offers substantial packaging efficiencies for equipment manufacturers.
“Reducing Tier IV installation complexity for the equipment manufacturer has been a key aim of our QSX development program and we have been focused on keeping the engine and particulate filter envelope as space efficient as possible,” said Susan Harrison, executive director of Cummins Industrial Engineering.
“A further benefit of Cummins integration capability is that we can electronically manage the engine and aftertreatment as a single system driven by the electronic control module. The engine ECM will integrate with equipment electronics, including CANbus common area networks for J1939 and ISO multiplexing. This allows electronic systems to talk to each other along a serial data link and is set to become a more significant feature as we look ahead to equipment designs for 2011.”
The QSX is available with the new Cummins direct flow air filtration system by Fleetguard, specifically developed for Tier IV applications.
Direct Flow offers a 35 percent smaller installation profile than typical Tier III air filtration systems while maintaining the same filtration efficiency. This is accomplished by creating a direct-flow path through the filter media which is packaged in a rectangular configuration rather than a conventional cylindrical shape. The direct flow housing includes a sensor to monitor temperature and pressure which sends data to the engine electronic control module to ensure optimum airflow operation.