12 August 2003
General Motors Europe (GME) said it has developed a diesel particulate filter (DPF) system to be launched on its Vauxhall and Opel diesel cars. The DPF system will be installed early next year on the GME’s Vectra and Signum lines with the new 1.9-liter CDTi Ecotec engine.
The aftertreatment system includes a close-coupled precatalyst, an oxidation catalyst (under the floor), and a monolithic, silicon carbide (SiC) diesel particulate filter catalyzed with a precious metal catalyst. The exhaust gas temperatures needed for filter regeneration are assured through post-injection of fuel in the common-rail injection system, followed by the oxidation of the resulting HC emission in the oxidation catalyst, with an additional heat release.
The DPF-fitted cars will be fully Euro 4 (2005) compliant, including PM, CO, HC, and NOx emissions, and eligible for Euro 4 tax incentives in countries that offer them.
GME is the second German car manufacturer (after Mercedes) to announce DPF technology for diesel cars. First advanced diesel filter system was introduced in May 2000 on Peugeot 607 2.2 HDi. The Peugeot system uses a fuel additive, rather than a catalyst, to facilitate regeneration.
The use of additives involves an extra maintenance effort to periodically replenish the on-vehicle additive tank and wash the filter from additive ash, but allows the use of fuels with sulfur levels currently legislated in the EU (350 ppm). Due to the use of precious metal catalysts which can form sulfate emissions, catalyst-based systems require ultra low sulfur fuels and can be used only in areas where such fuels are available. The first such catalyst-based DPF system was announced by Renault.