The potential of an advanced GPF concept for low pressure drop and low CO2 emission

Gasoline Direct Injection (GDI) concepts are the key technology of gasoline engine development to reduce CO

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emissions while improving torque and power output. However there is a side effect of increasing particle number emissions of GDI engines compared with conventional Multi Port Injection (MPI). The Particle Number (PN) limit for compression ignition (diesel) engines of 6×10

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/km was introduced with the enforcement of Euro 5b (09/2011). Then in 2012 a PN limit for GDI engines was decided to be effective from 09/2014 with the implementation of Euro 6b. Within the first three years of this introduction it is allowed to apply a higher limit value of 6×10

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/km at the manufacturer’s request. Eventually it will be mandatory for all to apply 6×10

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/km effective from 09/2017 (Euro 6c).

Since most of GDI particles are formulated during cold start phase as well as during catalyst heating mode, the injection system including injection operating program (e.g. number of injections, timing and amount), has been further developed in order to improve air fuel mixture at cold start phase. As a result, currently some of the latest GDI vehicles can achieve 6×10

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/km during NEDC by internal engine measures such as improved mixture homogenization and minimized amount of injected fuel striking the walls to avoid the formulation of particles during the combustion.