New Touareg V6 TDI – World premiere with innovative Clean Diesel
Touareg V6 TDI is one of the most fuel efficient and cleanest SUVs in the world
New Volkswagen SUV reduces fuel costs drastically
Wolfsburg / Los Angeles, 19 November 2008
In early 2009, Volkswagen will already be bringing a new Clean Diesel to the American market in the form of the Touareg. Never before was a Touareg more fuel efficient, never before so clean in emissions and never before so inexpensive to refuel. The 165 kW / 225 PS (at 4,000 rpm) strong Touareg V6 TDI fulfills the strictest emissions standards in the world, including the BIN5 of the states of California, Massachusetts, New York, Vermont and Maine. So just like the Jetta TDI already, the new Touareg V6 TDI will be available in all 50 states of the USA.
The high-tech engine of the all-wheel drive Touareg is making its debut with a fuel economy of 18 mpg (City). On the highway it even attains 25 mpg. The Touareg V6 TDI defines a completely new generation of extremely fuel efficient and low-emission SUVs. One of its technical trademarks: the SCR catalytic converter. The Touareg V6 TDI is one of the first SUVs in the world to have this type of catalytic converter on board. It reduces nitrogen oxide (NOx) emissions by up to 90 percent! An oxidation catalytic converter and a particulate filter are integrated in the emissions system too. So if anyone wishes to hold the infamous white handkerchief in front of the Touareg’s tailpipe, they will find that it stays white.
The fact is that more any other of today’s affordable drive technologies, especially in America, economical turbo-diesels like the V6 TDI are making a bigger contribution toward reducing oil consumption and reducing the generation of climate-damaging greenhouse gases. Compared to an SUV with a gasoline engine, overall fuel costs are significantly lower too.
In parallel, the V6 TDI satisfies even the highest expectations when it comes to dynamic response and comfort: the turbo-charged V6 TDI is about as quiet as a gasoline engine, yet it is far more powerful. It develops a torque of 550 Newton-meters starting at a low 1,750 rpm. So it is no wonder that despite its fuel economy, the Touareg V6 TDI – shifted by a six-speed automatic – accelerates from 0 to 60 mph in just 8.5 seconds. Its top speed is electronically limited to 130 mph (210 km/h).
The sensationally good ratio of power and dynamic response to fuel economy and low emissions is enabled by a technological concept that is the most advanced of its kind in the world. The car is built around a 3.0 liter displacement V6 turbo-diesel with exceptionally efficient third generation common rail injection. This type of injection and a special noise damping package ensure that the V6 TDI will impress as a whisper-quiet diesel; acoustically, it is hardly possible to differentiate it from a gasoline engine in the interior. A key component on the quest toward extremely low emissions and fuel consumption values – besides the high-end exhaust gas recirculation system (AGR) – is the SCR catalytic converter. The powertrain and emissions control technology of the new Touareg V6 TDI in detail:
SCR catalytic converter converts nitrogen oxides into nitrogen and water
The acronym SCR stands for the internationally recognized term "Selective Catalytic Reduction". "Selective" refers to the fact that this catalytic converter performs a very special task. Its job is to convert nitrogen oxide (NOx) components of the exhaust gas into nitrogen and water without forming any undesirable side products. It was developed precisely for this highly specialized task. That is why the new Touareg V6 TDI is also equipped with an oxidation catalytic converter and a diesel particulate filter to reduce the entire bandwidth of emissions. First, exhaust gases flow through the oxidation catalytic converter, then the particulate filter and finally the SCR catalytic converter.
The nitrogen oxides are converted in the SCR catalytic converter using a synthetically produced aqueous solution of urea (AdBlue) that is transported on the Touareg V6 TDI in a 4.0 gal. (17.5 liter) auxiliary tank. To protect against freezing of the AdBlue solution, the tank is heated in the winter (starting at 12.2 degrees Fahrenheit / -11 degrees Celsius), and to save space it is located under the spare wheel. AdBlue consists of 32.5 percent urea and is continually sprayed into the exhaust gas stream upstream of the SCR catalytic converter. It is metered according to the mass flow rate of the exhaust gas; the engine management system provides for precise control based on information from a NOx sensor downstream of the SCR catalytic converter.
Finely atomized by a screen, the urea is transformed in the hot exhaust gases upstream of the catalytic converter. In the SCR catalytic converter, it reacts with the nitrogen oxides and splits them into nitrogen and water. The aqueous AdBlue additive is nontoxic, odorless and biodegradable. On average, AdBlue consumption is about 1.0 liter per 620 miles (1,000 kilometers). Service garages can easily handle refilling of the very inexpensive AdBlue. As an alternative, the driver can refill small quantities of AdBlue solution underway without any great difficulties using a practical drip-free spare bottle.
Internal engine modifications
Beyond the SCR catalytic converter, Volkswagen engineers have come up with an entire bundle of innovative modifications. Combustion chamber sensors are being implemented for the first time, which monitor pressure conditions in the cylinders. Meanwhile, a new third generation common rail system with 2,000 bar injection pressure atomizes the fuel so that it is exceptionally fine. The targeted ideal combustion enhances quiet running and reduces raw emissions in general. Another technical highlight is the integrated intercooler for the turbocharger. A total of two intercoolers are used here. When the engine is cold, an automatic bypass door isolates the coolers from the system to ensure that the V6 TDI reaches its ideal operating temperature even quicker and attains optimal efficiency.
In general, however, reducing emissions, especially NOx raw emissions, takes the form of internal engine modifications such as lower maximum temperatures in the combustion chambers and reduced oxygen concentration by exhaust gas recirculation. The nitrogen oxides that are still produced despite these modifications reach the new SCR catalytic converter where they are removed, as already described.
Combustion chamber sensor and common rail injection
As engineers began to develop the V6 TDI, their first goal was to further optimize all aspects of combustion. The result is that a world’s first is celebrating its entry into high-volume production in the Clean Diesel: the combustion chamber sensor. Integrated in the glow pencil, the sensor continually measures pressure conditions in the cylinder and reports the data to engine management.
This enables perfect control of injection and combustion for each cylinder; it is even possible to compensate for fluctuating fuel qualities. Ideal combustion helps to reduce raw emissions. It also optimizes quiet running and noise behavior.
The common rail injection system that has undergone intensive advanced development serves the same purposes. With a new high pressure pump design (CP 4.2), the system builds up a pressure of 2,000 bar – this is new too. The piezo injectors also appear in a significantly modified form. Their smaller eight-hole nozzles inject fuel into the combustion chambers in miniscule volumes. This new design and its higher pressure make injection even more precise and dynamic – detailed work that in sum has produced one of the most fuel efficient and cleanest six-cylinder diesel engines in the world.
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