The Daimler Board of Management has approved a comprehensive plan for diesel engines consisting of a substantial expansion of the current service action for vehicles in customers’ hands as well as a rapid market launch of the completely new OM 654 diesel engine family (earlier post).
Since March, Mercedes-Benz has offered its customers of compact-class cars an improvement in NOx emissions for one engine version. Approximately 45% of those cars have since been updated. A voluntary service action is also being carried out for V-Class customers—so far with approximately 75% of the vehicles in Germany. To improve the emissions of additional model series, Daimler has now decided to extend the service action to include more than three million Mercedes-Benz vehicles.
The public debate about diesel engines is creating uncertainty—especially for our customers. We have therefore decided on additional measures to reassure drivers of diesel cars and to strengthen confidence in diesel technology. We are convinced that diesel engines will continue to be a fixed element of the drive-system mix, not least due to their low CO2 emissions.—Dr. Dieter Zetsche, Chairman of the Board of Management of Daimler AG and Head of Mercedes-Benz Cars
For this purpose, the company’s engineers are making use of latest knowledge gained during the development of the new OM 654 family of diesel engines.
The measures to be taken for nearly all EU5 and EU6 vehicles in Europe will be carried out in close cooperation with the German regulatory authorities. The company is investing about €220 million (US$254 million). The service actions involve no costs for the customers. The implementation of the measures will be starting in the next weeks. Due to the large number of vehicles this will continue over a longer period of time.
In this way, Daimler says it will makea significant contribution to the reduction of nitrogen-oxide emissions from diesel vehicles in European inner cities.
New engine family. Mercedes-Benz has already proven that diesel engines can meet the stricter EU emission regulations to come in the future with a completely new engine family. With an investment of approximately €3 billion (US$3.5 billion), the company has developed a new generation of engines the exemplary emissions of which have been confirmed by measurements carried out by independent institutes.
Following the market launch of the new four-cylinder OM 654 engine in the new E-Class in 2016, the launch of the modular engine family will now be implemented rapidly across the entire model portfolio.
The new OM 654 for the E-Class delivers around 13% lower fuel consumption and CO2 emissions along with a further increase in output (143 kW instead of 125 kW) compared to its predecessor, the OM 651.
The new diesel engine is designed to meet future emissions legislation (RDE – Real Driving Emissions). In contrast to the current NEDC measurement cycle, the WLTP (Worldwide harmonized Light vehicles Test Procedure) cycle is aimed at ensuring that the figures for standard and real-world consumption are close together in future.
All components of relevance for efficient emissions reduction are installed directly on the engine. With support from insulation and improved catalyst coatings, there is no need for engine temperature management during cold starting or at low load. In addition to the advantages in terms of emissions, this results in fuel savings, especially on short journeys. Due to the near-engine configuration, exhaust aftertreatment has a low heat loss and optimal operating conditions.
The new engine is equipped with multiway exhaust gas recirculation (EGR). This combines cooled high-pressure and low-pressure EGR. It makes it possible to significantly further reduce the untreated emissions from the engine across the entire engine map, with the center of combustion being optimized for fuel economy.
The exhaust gas from the turbocharger is sent first to a diesel oxidation catalyst. It next passes the downdraft mixer, in which AdBlue is added by means of a water-cooled dosing module. Using a specially developed mixing area, the AdBlue evaporates over the shortest possible distance in the exhaust gas stream and is distributed very uniformly on the surface of the downstream sDPF (particulate filter with coating to reduce nitrogen oxides). Positioned behind the sDPF is an SCR catalyst for further catalytic reduction of the nitrogen oxides. Only then does the treated exhaust gas enter the exhaust system.
Daimler will continue to work on the systematic electrification of its vehicles, support mobility services such as moovel and car2go, and develop increasingly clean combustion engines. Daimler says that diesel engines will continue to play an important role for a long time yet due to their significantly higher efficiency than gasoline engines.