January 5, 2007
Volkswagen unveils cleanest-ever TDI engine
Wolfsburg, Germany – Volkswagen has unveiled its cleanest TDI engine ever, with first test drives demonstrating that a Jetta equipped with a 2.0-litre Common Rail diesel engine with nitrogen oxide reservoir catalytic converter complied with the Californian emission standard Tier 2/Bin 5. These requirements are considered the most stringent worldwide, and apply to California, Massachusetts, New York, Vermont and Maine.
The first production run of the “Clean TDI” with nitrogen oxide post-treatment system will be made in the U.S. during 2008.
Engineers reached the reduction of nitrogen oxide through internal development of the motor and the use of new emission post-treatment technology, with a result of up to 90 per cent less nitrogen oxide emissions (NOx). Volkswagen has developed two systems connected to the oxidation catalytic converter and the particle filter in the exhaust system.
New NOx reservoir catalytic converter technology is currently being tested for car models below the Passat class. Nitrogen oxide is absorbed like a sponge, and the system is regularly cleaned without the driver noticing. Larger, heavier models feature the Selective Catalytic Reduction (SCR) catalytic converter. The central element is an aqueous solution, comprised of 32.5 per cent urea, continuously injected into the exhaust system in front of the SCR converter using a metering valve. The solution is converted into ammonia, which reacts with the nitrogen oxide and separates it into nitrogen and water. Volkswagen intends to install the additional tank so that a garage can refill the tank at inspections, with no maintenance required in between. According to American regulations, the complete system must be fully functional for at least 150,000 miles (241,401 km).
The engines are part of the BlueTec initiative, a joint project of Volkswagen, Audi and DaimlerChrysler, intended to establish the diesel engine further in the American car market. Each of the manufacturers is working on individual technical solutions and plans to market these independently.