Touareg BlueTDI - World Premiere of the Clean High-Tech Diesel
Onrnits new Touareg Volkswagen is introducing one of the cleanest dieselrnengines in the world: The BlueTDI with SCR catalytic converter. Thisrnconverter reduces nitrogen dioxide (NOx) emissions by up to 90 percent.rnThe Touareg BlueTDI, that delivers 165 kW / 225 PS, meets even the mostrnchallenging exhaust emissions standards. Currently, the lowest limitsrnare set in the US states California, Massachusetts, New York, Vermontrnand Maine: In the "Tier2 Bin5" standard. The Touareg BlueTDI beingrnpresented in Geneva is one of the first vehicles with a diesel enginernthat can clear this hurdle too. Especially in the USA, economicalrnturbo-diesels like the V6 BlueTDI can contribute, more than any otherrncurrent powertrain technology, toward reducing oil consumption and therngeneration of climate-impacting greenhouse gases.
Therefore,rnVolkswagen will be offering the Touareg with SCR catalytic converterrnstarting in 2008, initially in the USA, as part of the BlueTec Alliancernstarted together with Audi and DaimlerChrysler at the end of last year.rnAlso slated for 2008: The company for smaller vehicles like the Jettarnwill introduce, in America, a NOx storage catalytic converter thatrneliminates up to 90 percent of nitrogen oxides. The two technicallyrnchallenging systems are scheduled to debut in Europe a short time later.
ThernEuro-4 standard currently specifies a NOx limit of 0.25 g/km here. ThernUS standard, which the Touareg BlueTDI satisfies, specifies among otherrnthings a NOx limit of 0.043 g/km (0.07 g/mile).
SCR (SELECTIVE CATALYTIC REDUCTION) CATALYTIC CONVERTER
SCRrnis the usual international acronym for "Selective Catalytic Reduction".rn"Selective" refers to the fact that this catalytic converter has a veryrnspecial task. Its purpose is to selectively convert the nitrogen oxidern(NOx) exhaust components to nitrogen and water without generating anyrnundesirable side products. It was developed precisely for this highlyrnspecialized task. Therefore, in the future vehicles such as the TouaregrnBlueTDI, being shown for the first time in Geneva, will also bernequipped with an oxidation catalytic converter and a diesel particulaternfilter.
The nitrogen oxides are converted utilizing arnsynthetically produced, water-based urea solution, e.g. AdBlue, whichrnis stored in an auxiliary tank on the Touareg BlueTDI. The substance,rnconsisting of 32.5 percent urea, is continuously sprayed into thernexhaust stream before the SCR catalytic converter. It is metered basedrnon the mass flow of the exhaust. Engine management ensures precisernregulation, based on information from a NOx sensor located after thernSCR catalytic converter.
Atomized into a fine spray by a screen,rnthe urea is transformed in the hot exhaust gas stream upstream of therncatalytic converter. In the SCR catalytic converter this reacts withrnthe nitrogen oxides and splits them, as described, into nitrogen andrnwater. The water-based additive AdBlue is non-toxic, odorless andrnbiodegradable.
AdBlue is consumed at an average rate of about 0.1rnliter per 100 kilometers. Consumption and tank size are sized so thatrnthe AdBlue supply does not need to be replenished until the nextrnscheduled service.
INTERNAL ENGINE MODIFICATIONS
Besidesrnintroducing the SCR catalytic converter, the engineers at VolkswagenrnAutomotive Group have put together an entire bundle of innovativernmodifications. Combustion chamber sensors are being implemented for thernfirst time; they monitor pressure conditions in the cylinders. And arnnew common rail system with 2,000 bar injection pressure atomizes thernfuel even finer. The ideal combustion achieved by these measuresrnenhances smooth engine running and lowers overall raw emissions.
Inrnthe effort to reduce emissions, especially NOx raw emissions, effortsrnbeing made in internal engine modifications include measures to lowerrnmaximum temperatures in the combustion chambers and to reduce oxygenrnconcentration by exhaust gas recirculation. Nitrogen oxides generatedrndespite these measures are fed to the new SCR catalytic converter andrnare removed, as outlined above.
COMBUSTION CHAMBER SENSOR AND COMMON RAIL IN DETAIL
Asrnengineers began to develop the BlueTDI, their first goal was to achievernfurther overall combustion optimization in the engine. The worldrnpremiere of such an innovation is being celebrated in the BlueTDI - therncombustion chamber sensor. Integrated in the glow plug, the sensorrncontinuously measures pressure conditions in the cylinder and reportsrnthe data to engine management.
This enables perfect control ofrninjection and combustion in each cylinder; it is even possible torncompensate for fluctuating qualities of fuel. Ideal combustion helps tornreduce raw emissions. It also optimizes smooth running and noisernbehavior.
The intensively refined common rail injection systemrnserves the same purposes. With a newly designed pump, the system buildsrnup 2,000 bar of pressure - also an innovation. The piezo injectors havernbeen significantly modified too. Their smaller eight-hole nozzlesrninject miniscule spray volumes into the combustion chambers. This,rntogether with the higher pressure combine to produce an injection thatrnis even more precise and dynamic - detailed work that as a whole hasrnresulted in one of the most economical and cleanest six-cylinder dieselrnengines in the world.
VOLKSWAGEN BLUEMOTION PARK
Tornpoint out its activities in the area of environmental protection,rnVolkswagen has set up a BlueMotion Park at the 2007 Geneva Motor Show.rnAt numerous exhibits and interactive information terminals onrntechnological highlights visitors can experience how Volkswagenrntechnologies are preserving the mobility of today and tomorrow. Keyrntopics addressed here are engines, transmissions, synthetic fuels,rnlightweight construction and aerodynamics. Exhibits relating to BlueTDIrnsystems are another focal point: The SCR catalytic converter for largerrnvehicles like the Touareg, and the NOx storage catalytic converter suchrnas the one Volkswagen introduced for the first time in a Jetta test car.