Cummins Powers Up for Tier 4 Final
Cummins’ next-generation QSB4.5 engine is designed to meet Tier 4 Final near-zero emissions standards with power increased to 173 hp. and a higher peak torque of 520 lb-ft. The 4-cylinder, 4.5-liter engine is performance-enhanced with a Cummins Variable Geometry Turbocharger (VGT), enabling the higher ratings of the QSB4.5 to reach performance levels previously associated with a larger 6-cylinder engine.
For the QSB4.5 lower ratings – down to 121 hp. – the VGT technology improves transient response on a fuel-efficient basis. For equipment operation, this means a stronger, faster response to increasing load demands compared with Tier 4 Interim engines.
The cooled Exhaust Gas Recirculation (EGR) and the Cummins Compact Catalyst (CCC) after treatment on the Tier 4 Interim engines were retained on the new engines. The VGT used on the QSB4.5 is a smaller version of the VGT on Cummins 6-cylinder engines. The VGT features a unique, one-piece sliding nozzle to precisely adjust the airflow delivered to the engine. This combines the advantages of a small and a large turbocharger in a single unit, so that rapid boost is provided at a low rpm and high boost is maintained at a higher rpm.
To remove particulate matter from the exhaust, the CCC after treatment moves forward to Tier 4 Final with the same “fit and forget” advantage used for Tier 4 Interim applications, with a smaller space claim than a Diesel Particulate Filter.
The very low nitrogen oxide emissions levels required for final standards are achieved by incorporating Cummins Selective Catalytic Reduction (SCR) after treatment in the exhaust system, configured for compact 4-cylinder applications. The SCR is able to operate more efficiently at lower temperatures and features advanced sensors to provide full closed-loop control. Diesel Exhaust Fluid (DEF) dosing levels are minimized due to an enhanced mixing technique. The CCC-SCR after treatment is available in multiple configurations, including switchback, horizontal, and vertical formats.
The QSB4.5 will be ready for Tier 4 Final emissions regulations taking effect Jan. 1, 2015.