New VW EA288 diesel to debut in 2H 2014 in the MY 2015 Golf, Jetta, Passat and Beetle; MDB comes to the US (updated with diagrams)
|Main modules of development of the EA288 diesel. Click to enlarge.|
Volkswagen of America announced that the new 2.0-liter EA288 diesel engine will power the 2015 Golf, Beetle, Beetle Convertible, Passat, and Jetta, all of which are set to arrive in dealer showrooms in the second half of 2014. The EA288 is based on the Volkswagen MDB, its modular diesel engine toolkit (Modularen Diesel Baukasten) (earlier post).
The new EA288 engine will eventually replace all the 2.0-liter diesels currently fitted in Audi and Volkswagen TDI Clean Diesel models. This turbocharged, common-rail, direct-injection four-cylinder engine makes 150 hp (112 kW)—an increase of 10 hp over the current engine—and 236 lb-ft (320 N·m) of torque. This powerplant shares only the bore spacing with the previous diesel engine that had the same designation.
In a briefing last week at Volkswagen’s annual media conference, Dr. Johannes Arning, of Volkswagen’s Powertrain Product Management group, noted that the new MDB offers five major features:
Improved basic engine. Volkswagen improved the crank gear with reduced piston friction and increased piston-to-wall clearance. The engineers integrated the oil and vacuum pump in one module; it is designed as a compact dual pump. An new integrated valve train module also runs with reduced friction.
Integrated thermal management. There are three different cooling circuits. The first is a microcircuit, with very small volume with three major parts: the cylinder head, the EGR cooler, and the heat exchanger. With the small circuit, the water warms up very quickly. This offers advantages such as quickly warming up the interior and the engine. Once the engine is in a warm mode, it is more fuel efficient, with improved emissions.
The three cooling circuits. Click to enlarge.
Once the engine is warm, the cylinder head management opens the next circuit and draws the water through the crankcase. Speed is variable; if the engine is idling, for example, there is reduced need to draw away heat, and thus no need for higher speed water flow.
The third circuit cools the charge air for more efficient combustion. Unlike many air coolers, this is not cooled by ambient air, but by water. This enables more precise control of the air temperature—e.g., warming if necessary.
The charge air intercooler is integrated into the intake manifold. Click to enlarge.
Charge air cooling. The charge air intercooler is integrated into the intake manifold; the intercooler is very compact because it is water-cooled.
The MDB is thus also able to use a very short air path, which helps improve the throttle response.
Exhaust gas aftertreatment module close to engine. The compact unit is mounted very close to the engine, helping to lower heat and pressure losses. To meet increasing stringent emissions requirements, aftertreatment systems need to start as soon as possible, Dr. Arning noted, as most emissions are formed within the first 45 seconds of start. Thus, you want the system to heat up as soon as possible. In the MDB, the exhaust gas treatment systems starts right after the turbocharger.
The system is modular. It can use an SCR system, or NOx storage, or oxy cat—essentially whatever the engine needs, without affecting the rest of the engine.
Low-pressure EGR. Volkswagen improved the pressure losses in the system by some 90%, bringing it down from 200 to 20-25 millibars.
The flexibility of the MDB will allow the engines to meet the coming EPA Tier 3, California LEV III emissions standards, Volkswagen said, in addition to meeting current Bin 5 and Euro 6 specifications.
Overall, the new MDB and EA288 are delivering a decrease in friction by about 15%; power and torque up over a wider range of operation; improved heating performance, a reduction of charge air volume of about 40%; and a reduction in raw emissions (engine out) of about 40%.
While the EA288 coming to the US is a 2.0-liter model, the MDB supports a displacement range of 1.4-liters to 2.0 liters, with the low end represented by a 3-cylinder unit in Europe.
The modularity and flexibility of the MDB also provides a path for evolution; for example, new injection systems and controls could enable the use of an advanced combustion regime such as one of the variants of Low Temperature Combustion.
|The modular diesel system. Click to enlarge.|
Volkswagen Group of America (VWGOA) has had continued success with diesel technology: In 2013, VWGOA sold 105,899 TDI Clean Diesel vehicles from the Volkswagen and Audi brands. This was the first time it passed the 100,000 sales milestone in a calendar year, representing nearly 75% of the diesel sales for passenger cars and SUVs in the United States in 2013. Volkswagen and Audi currently offer 12 different TDI Clean Diesel powered models in the United States.