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Development trends for heavy engines

  • Magazine Feature Article
  • 15OFHP04_04
Published April 01, 2015 by SAE International in United States
Language:
  • English

Downsizing engine displacement, new materials, friction reduction, and advanced boosting and fuel-injection technologies have demonstrated potential in light-duty vehicles, and implementation is under way. FEV experts provide an outlook of how these technologies can improve the base engine for commercial applications with regard to future emissions and fuel-efficiency requirements.

Compliance to today's emission legislations for heavy-duty (HD) diesel engines in commercial vehicles (CVs) demands a reduction of NOx and particulate matter emissions in the entire engine operating range including high load points. A very effective way to reduce the raw NOx emissions at high loads is to operate the engine with high exhaust gas recirculation (EGR) rates. At the same time, the air fuel ratio (AFR) must be kept constant to a level needed to hold the particulate emissions under the allowed limit. An increase of fuel injection pressure also aids in lowering of particulate emissions.

Meeting these and future emissions legislation requirements while maintaining or even increasing the specific torque and power output of the engine presents challenging requirements to the base engine design, according to experts at FEV. Increased EGR and boost result in an increased peak cylinder pressure (PCP) to as high as 250 bar (3.6 ksi), increasing the forces experienced by the cylinder head, crankcase, and the cranktrain components, requiring the designs and materials to be upgraded. Higher fuel-injection pressure requires the fuel pump and its drive mechanism to withstand the increased torque and forces.