Volkswagen introducing new EA288 diesel engine
12 August 2012
The Volkswagen Group of America confirmed the timing of the company's newest TDI Clean Diesel engine, designated EA288—the new engine will power the 2015 Golf, Beetle, Passat, and Jetta, which are scheduled to arrive in dealer showrooms in the second half of 2014.
The new EA288 will eventually replace all the 2.0-liter TDI engines in Audi and Volkswagen TDI Clean Diesel models in the North American market. The engine is a turbocharged, common-rail, direct-injection 4-cylinder engine with a 150 hp (112 kW) power rating—an increase of 10 hp over the current engine—and 236 lb-ft (320 Nm) of torque.
The engine has been designed under the modular transverse matrix (MQB) strategy of the Volkswagen Group that enables the use of uniform processes within vehicle platforms during vehicle development and production. In the new modular diesel engine system (MDB), the same base module will be used to implement both the performance and the emission versions for Euro 4 through Euro 6, as well as the US EPA Tier 2 and presumably Tier 3 emission standards. Thus, the new EA288 is the first diesel engine to share most of its common design features between the North American and European versions. In the Volkswagen MDB set, the new EA288 will be available with engine displacements of 1.6 and 2.0 liters.
The new engine shares only the bore spacing with the previous diesel engine that had the same designation. A number of advanced features have been introduced to help reduce emissions—specifically in the Euro 6 and/or the North American versions—including:
- A dual-loop EGR system, with high pressure EGR and a cooled low-pressure EGR loops. While this architecture is similar to the EGR system in the current Tier 2 Bin 5 2.0 TDI, in the new engine the water-cooled intercooler and the high pressure EGR valve are integrated with the intake manifold, which also improves throttle response.
- Variable valve train (VVT) with a camshaft adjuster. The VVT system—a key component to reduce emissions in the cylinder—enables high effective compression during cold start and warm-up, and low emissions with very good soot/NOx trade-off at partial loads.
- A 2000 bar common rail injection system: CRS 2-20 by Bosch.
- Cylinder pressure control. A number of combustion characteristics such as average and peak pressure and the maximum pressure increase are calculated in real time based on pressure measurement in one cylinder. The cylinder pressure control, which occurs via adjustment of fuel injection parameters, provides better sensitivity for fuel quality.
The engine utilizes a modular, close-coupled aftertreatment system that includes a flow-through catalyst followed by a wall-flow diesel particulate filter (DPF). These components can be coated with different catalysts and use different control strategies to meet different emission requirements. For example, oxidation catalyst coatings would be used in Euro 5 applications. Consistently with their prior diesel engine technology, Volkswagen will use two approaches for applications that require NOx aftertreatment—Euro 6 and US Tier 2:
- A NOx adsorber-based system will be used on smaller size vehicles. In this configuration, the flow-through substrate is coated with the NOx adsorber catalyst (Ba/Pt/Pd/Rh), while the wall-flow filter is coated with an oxidation catalyst (Pt/Pd/Al2O3) and with a base metal “H2S trap” catalyst.
- A urea-SCR system is used on larger vehicles. In this case, the flow-through substrate is coated with an oxidation catalyst, and the particulate filter includes a Cu-zeolite SCR coating in an SCR-on-filter configuration. The EA288 will be one of the world’s first (possibly, the first) commercial application of the SCR-on-DPF technology.
The engine also has a number of modifications to help minimize friction and optimize fuel economy: low-friction bearings for the camshaft and balancer shafts, piston rings that have less pre-tension, and a two-stage oil pump with volumetric flow control. The new engine would have a better fuel economy than the current unit, said Volkswagen, but no details were provided.
Year-to-date the Volkswagen Group of America has sold more than 47,000 diesel vehicles, including more than 10,000 in the month of July alone. This represents nearly 78% market share for diesel passenger cars in the United States this year.
Source: Volkswagen (Press release | MTZ June 2013)