Development and performance assessment of the new-generation CF fuel injection system for diesel passenger cars

An innovative hydraulic layout for high-pressure fuel injection systems has been developed. The rail has been removed from the high-pressure circuit of standard Common Rail injection apparatus in order to have: reduced production costs, easy installation on the engine and a fast dynamic response of the injection system during engine transients. The innovative high-pressure pump has been machined with extra delivery ports in order to obtain direct connection with each of the injector feeding pipes. A special pump delivery-chamber, featuring an adequate volume, was designed to provide the minimum hydraulic capacitance required for a proper control of the high-pressure in the system.A prototype of the new-concept Common Feeding (CF) injection system was set up at the Politecnico di Torino laboratory and subjected to an extensive experimental campaign on an advanced hydraulic test rig. The hydraulic performance of the new apparatus was compared with that of standard Common Rail system, in terms of injected flow-rate time histories, cycle-to-cycle dispersion and multiple injection dependence on dwell time.Finally, the new-generation system was installed on a Euro 5 diesel engine and tested in a dynamometer-cell. Pollutant emissions were measured at some reference working conditions as well as along the NEDC and compared to analogous data obtained for the same engine, but set up applying the standard Common Rail.

► The innovative CF injection system without rail is proposed for diesel engines.
► The capacitance and the inertial effects of the rail are examined.
► The hydraulic performance of the CF system has been compared with that of the CR system.
► The CF system has been installed on the engine and tested at a dynamometer cell.
► The CF system has reduced manufacturing costs and easy installation on engine.