Low Pressure Direct Injection, a breakthrough to conventional High Pressure Direct Injection towards EU6c and LEV3

This technical breakthrough to conventional High Pressure Direct Injection (HPDI) system addresses new upcoming emission regulations with strong focus on particulate matter/number (PM/PN) as on CO2, but also under stringent cost constraint reduction, targeting EMEA region (i.e. EU6c) and allowing introduction to the NAFTA market (i.e. LEV3). The limitation of emitted particulates avoiding the use of Gasoline Particulates Filter (GPF) and the maximization of the fuel efficiency on heavily downsized engine required significant engineering effort on combustion, hydraulic and control systems.
The innovation lead was the reduction of the fuel rail operating pressure of a direct injection system, as much as possible, operating swirl nozzle side injection with a new pump concept (patented), together with the elimination of the rail pressure sensor and in compliance with combustion design pre-requisites. The idea was to run constant rail pressure over engine operating range, minimizing the level of fuel pressure while addressing functional requirements like optimum atomization, limited spray penetration and broader fuel flow metering.
The last two years of this concept development allowed to respect the EU6c emission targets, to improve fuel economy and to attain without restrictions of the engine performance.
Enhanced control system with a modeling approach brought the possibility of cancelling the physical rail pressure sensor (patented). The model is developed based on specific electrical signature of each injector at each stroke. But the removal of that sensor with direct injection impacts many functions of the engine control system and this is why modeling design needs to be verified with experiments following fuel injection system identification in order to guarantee proper and accurate fuel metering.
Furthermore, the behavior of the embedded diagnosis for functional components is necessary, all within a regulatory framework as OBD and a comprehensive system FMEA.