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Future light, medium and heavy duty diesel engines will need to satisfy the more stringent emission levels (US 2014, Euro 6, etc.) without compromising their current performance and fuel economy, while still maintaining a competitive cost. In order to achieve this, the Fuel Injection Equipment (FIE) together with the pressure charging, cooling system, exhaust after treatment and other engine sub-systems will each play a key role. The FIE has to offer a range of flexible injection characteristics, e.g. a multiple injection train with or without separation, modulated injection pressures and rates for every injection, higher specific power output from the same injector envelope, and close control of very small fuel injection quantities. The aim of this paper is to present Delphi's developments in fuel injection strategies for light and medium duty diesel engines that will comply with future emission legislation, whilst providing higher power density and uncompromised fuel economy.

A very flexible choice of fuel injection characteristics can be obtained with an advanced electronic unit injector that has been developed with two electronically controlled valves. Single-cylinder engine tests have demonstrated the potential of this advanced EUI system for a heavy-duty diesel engine. Substantial increases in injection pressure can be programmed electronically at individual engine speed/load conditions, compared with a baseline EUI system, to provide much faster rates of air/fuel mixing. Simulated US and European emissions cycle results, with the optimised two-actuator EUI and EGR, show substantially improved soot particulate versus NOx results and lower BSFC compared with a baseline EUI result. A high-pressure post injection has the potential to give further soot reduction.