Volkswagen introduced the all-new Passat in 2011 at the Detroit Motor Show in the USA. Itis a new midsize sedan designed exclusively for the American market and will be built at acompletely new plant in Chattanooga, Tennessee.The second-generation 2.0l TDI~? engine familiar from Europe was extensively modifiedand further developed for the new Passat, in order to comply with the AmericanBIN5/ULEV emission limits. For this purpose the engine’s untreated emissions had to belowered and, in combination with exhaust emission control by selective catalytic reduction(SCR), compliance with the emission limits throughout the car’s operating life ensured.An effective measure for lowering the engine’s untreated emissions has proved to be thelow-pressure EGR system (LP EGR) [1] introduced on the first-generation 2.0l TDI~? BIN5engine. In the course of ongoing development of the LP EGR system, work continued onreducing pressure losses in the system, and charge-air cooling was converted from air towater cooling. Water-cooled charge-air cooling enabels intake pipe temperature controlindependent of ambient temperature, and due to the elimination of throttling and theassociated reduction in volume improves road dynamics. Systematic elimination ofthrottling restrictions in the gas system, combined with improved turbocharging, led to asignificant drop in fuel consumption and optimal road performance.As a means of stabilizing untreated emissions in the engine, cylinder-pressure control ofcombustion was carried-over from the first-generation 2.0l TDI BIN5 engine. Thanks to theclosed-loop control of the indicated mean pressure and the centre of combustion with thepressure sensor integrated into the glowplug, it was possible to minimize the influences offluctuating fuel quality and component tolerances.The exhaust system was completely revised in order to achieve maximum NOX conversionin the SCR catalytic converter. The coating of the diesel oxidation catalyst (DOC) / dieselparticulate filter (DPF) module was modified to ensure an optimal NO2-NOX ratio overlifetime. Improved thermal response and an increase in the stationary temperature in theSCR catalytic converter at low loads were achieved by thermal insulation of the exhaustsystem. In order to obtain highly uniform NH3 distribution, a mixer has been integrated intothe SCR system. Optimization of the coating minimized aging and de-activation of theSCR catalytic converter.The SCR system concept was adopted from the Passat ‘BlueTDI’ complying with Euro 6,as introduced in Europe in 2009 [2]. The tank is matched to the vehicle geometrically andlocated in the rear section of the vehicle. The tank and the feed lines to the injector can beheated to ensure the supply of AdBlue even at very low ambient temperatures.The requirements to be satisfied by the OBD system are determined by the tough currentCalifornian standards for the 2013 model year, especially the more stringent exhaust gascorrelatingthreshold diagnoses. New functions were developed as a means of satisfyingthese diagnostic requirements.With the new second-generation 2.0l TDI~? BIN5/ULEV engine for the new Passat, whichhas been matched completely to the needs of the American market, combined with the lowlevel of emissions, Volkswagen sets new standards for road performance and fuelconsumption in a midsize automobile.
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