Daimler HighTechReport: The Fascination of Technology - Issue 02/2008 - PART VII


Stuttgart, Nov 25, 2008

DRIVE SYSTEMS: Driving Forces

Drive technologies made to measure: Daimler believes that individual solutions hold the key to achieving sustainable mobility.

I The future of mobility is a complex and, above all, global issue. That’s because the world’s population is rising dramatically, and this is increasing demand for individual mobility. Natural resources are becoming scarcer and more expensive, while growing urbanization is resulting in higher traffic volumes, deteriorating air quality, and increasing noise pollution. All of these developments are reflected in new legislation that particularly impacts Daimler as a manufacturer of premium automobiles. New technological solutions are required to meet the complex and sometimes conflicting demands that are being made on automobiles with regard to safety, individualization, and environmental protection.

“We are committed to addressing these challenges and have therefore drawn up a road map for sustainable mobility,” says Thomas Weber, Daimler Board of Management member responsible for Group Research and Mercedes-Benz Cars Development. The idea is to ensure that individual mobility remains attractive and affordable over the long term, while at the same time designing automobiles to be as environmentally sound as possible, and less dependent on petroleum. “We therefore develop customized individual solutions for various mobility needs,” says Weber. “Nevertheless, we make no sacrifices in terms of typical brand characteristics related to the safety, comfort, superior driving performance, and emotional appeal of our vehicles. In other words, driving pleasure and energy conservation need not be mutually exclusive.”

Think tanks and alliances Those who pursue such ambitious goals need to effectively consolidate their expertise. “To this end, we’ve very closely networked our research and development activities,” Weber reports. “Our researchers develop fundamental new technologies and processes, and our development engineers introduce viable technologies into our production vehicles. Both groups work hand-in-hand to ensure that new technologies are brought to market as quickly and effectively as possible. We also have internal centers of competence in the form of think tanks that focus on things like hybrid technologies, fuel cell systems, and zero-emission commercial vehicles. Finally, we tap into external expertise through strategic alliances and joint ventures, such as the one we’ve established with Continental.”

Three drive concepts Daimler’s strategy focuses on three approaches to individualized vehicle concepts, with the “Road Map for Sustainable Mobility” pointing the way forward. The first approach involves consistent optimization of vehicles equipped with state-of-the-art combustion engines. Activities in the second area seek to achieve further efficiency gains through hybrid systems that include gasoline or diesel engines. Thirdly, there is the goal of zero-emission driving with fuel cell and battery-powered vehicles. “Emission-free driving will be a key mobility issue in the future, and we will be on the cutting edge of developments,” says Weber.
Does this mean that the traditional combustion engine will soon be a thing of the past?

Internal combustion engines

II “No,” says Erhard Rau, head of Research and Advanced Engineering Combustion Engine Drive Systems at Daimler. “There’s still a lot that can be done with combustion engines, which is why we’re working hard to make gasoline engines as efficient as diesels, and diesels as clean as gasoline engines.” Researchers in Rau’s unit are working closely with Mercedes-Benz development departments to come up with new ways of optimizing cars with combustion engines to the greatest extent possible using measures such as BlueTEC, downsizing, supercharging, and direct injection.

“Our gasoline-engine development focus is on optimizing fuel economy and weight,” says Peter Lückert, head of Basic Engine Development at Mercedes-Benz Cars. “This approach enables us to conserve resources and improve environmental protection in line with our strategy for sustainable mobility.”

An important contribution is made here by spray-guided direct injection for gasoline engines, which was introduced through the joint efforts of research and development departments. Series production of this injection system was launched in April 2006 in the CLS 350 CGI. It is now also available in the E-Class, and will be introduced to the C-Class at the end of 2008. “This combustion technique, which was devised by our research colleagues, utilizes injection valves that open outwards and piezo injectors,” says Lückert. “The procedure enables us to achieve a stratified charge that results in substantial fuel savings even at high engine loads.”

Less is more Fuel consumption can also be lowered by downsizing the number of cylinders from six to four and reducing displacement to below two liters - even in premium vehicles. Because the reduction in displacement lowers output, downsized engines are also equipped with a turbocharger. “We decided to utilize turbochargers with the new direct injection system,” Rau reports. “The turbochargers are driven by the hot exhaust gas and have lower fuel consumption than mechanically driven compressors.” That’s because modern direct injection enables dynamic driving performance without “turbo lag”: “The charge changing process can be regulated to offset the typical disadvantages of a turbocharger.”

The most recent example of intelligent downsizing is offered by the OM 651 diesel engine that premiered in the C 250 CDI at the end of 2008, and which will gradually be installed in models worldwide. “This engine’s two-stage turbocharging system, common-rail injection with a directly activated piezo actuator, and numerous friction-reducing features make it the highest-torque four-cylinder diesel engine ever installed in a car,” says Joachim Schommers, head of Passenger Car Diesel Engine Development. “The OM 651 delivers 204 hp and 500 Nm of torque with just 2.2 liters displacement - something you won’t find anywhere else.” Still, the C 250 CDI consumes only 5.2 liters of fuel per 100 kilometers, and the vehicle also meets the EU 5 emission requirements without any further measures.

Clean diesel The use of selective catalytic reduction (SCR) in conjunction with the urea solution AdBlue enables Mercedes-Benz to build the world’s cleanest diesel engines. “We were the first diesel engine manufacturer to receive a certificate for the U.S. Bin 5 standard, which stipulates extremely low emission values,” says Schommers.

A perfect example of the huge potential still to be tapped in the near future with combustion engines is offered by the innovative DIESOTTO drive that was presented in the F 700 research vehicle at the 2007 IAA Motor Show in Frankfurt. DIESOTTO combines the strengths of low-emission gasoline engines with the fuel economy of state-of-the-art diesels. Thanks to its integrated hybrid module, this completely new type of engine delivers 258 hp from only 1.8 liters displacement and accelerates from 0–100 kilometers per hour in 7.5 seconds, while consuming only 5.3 liters of gasoline per 100 kilometers.

Flexible: Hybrid drives

III Hybrid technology represents the second solution approach on the “Road to the Future,” says Neil Armstrong, who has been managing the Hybrid Systems and Component Center at Mercedes-Benz in Stuttgart, Germany, since the beginning of 2008. Armstrong is also director of the Hybrid Development Center (HDC) in Troy, Michigan. “Basically, we already have expandable components and concepts for fuel-efficient and environmentally friendly drive systems,” Armstrong explains. “We’ve got combustion engines, a generator that converts kinetic energy to electrical energy, and electric motors for a zero-emission drive. Linking these intelligently and, if possible, integrating them with other powertrain components significantly reduces overall consumption.”

Those looking for effective solutions can’t afford to shy away from cooperation with other automakers, which is why Daimler has developed optimized hybrid systems at the HDC in cooperation with BMW, Chrysler, and GM. These systems will be introduced to Mercedes-Benz vehicles as early as next year. “This type of cooperation benefits all parties - not to mention our customers,” says Armstrong.

Two strategies Mercedes-Benz is pursuing two different strategies for hybrid drive concepts. “On the one hand, we plan to keep alterations to body designs to a minimum so as to be able to install new hybrid components with just a few adjustments in existing model series as well,” says Jürgen Schenk, who is responsible for Electric Powertrains at the Mercedes Technology Center in Sindelfingen. “The other concept involves getting as much out of hybrid technology as possible in certain vehicles. And that will require more extensive alterations to the vehicle structure.”

A simple and effective method is to use a starter-generator such as the one employed in the smart fortwo mhd (micro hybrid drive). Here, an intelligent stop/start feature shuts off the gasoline engine when the vehicle brakes for a traffic light, after which the starter-generator briskly sets the car in motion when the light turns green, and then continues working as a generator. This system can reduce fuel consumption in city driving by as much as 19 percent.

Various solutions The mild hybrid concept, which goes a step further, will be implemented in the Mercedes-Benz S 400 BlueHYBRID in 2009. In this system, the stop/ start feature is supplemented by additional hybrid components, including a disk-shaped electric motor mounted between the combustion engine and the transmission. Depending on the situation, it can serve as a starter motor or an acceleration booster. During braking, the motor acts as a generator, providing power to the vehicle’s lithium-ion battery (regeneration). This setup substantially reduces fuel consumption when starting off and accelerating.

A current result of the HDC partnership is the two-mode hybrid installed in the Mercedes-Benz ML 450 BlueHYBRID. This full hybrid system attains the maximum degree of hybridization possible - a feat that requires significant changes to the vehicle structure and drive system controls. With the two-mode hybrid, the combustion engine, two electric motors, and transmission work together so intelligently that the overall drive unit is able to determine and engage the most fuel-efficient mode for a given situation, such as stop-and-go traffic or highway driving.

“We thus now have the complete range of concepts in our program - everything from the simplest to the full hybrid systems,” says Schenk. This is important, as the mobility needs of customers worldwide vary and will continue to change. “Today we build cars that can handle many different tasks,” says Schenk. “It’s likely that customers will demand specialized drives in the future, such as combustion engines for long distances, hybrids for universal city-highway applications, and fuel cells and battery-powered vehicles for cities.”

Zero emissions: electric drives

IV One thing is certain: Zero-emission electric vehicles powered by fuel cells or batteries will be a part of the future drive system mix at Daimler. The battery is the key here: “We’re working on special high-energy cells for pure battery vehicles,” says Christian Mohrdieck, head of Fuel Cell and Battery Drive System Development at Daimler Corporate Research and Advanced Engineering. “Obviously, given the physical restrictions, we can’t expect miracles. Nevertheless, we will soon be seeing battery-powered vehicles that are roughly the same size as the smart or the B-Class. Their batteries will have charging times of several hours and a range of perhaps 150 kilometers.” They will thus be ideal vehicles for city driving and daily commuting. After all, it will be possible to charge the batteries at home overnight, as is the case with the 100 smart fortwo ed (electric drive) models being operated in a test series in London, UK.

Moving forward with hydrogen Fuel cells aren’t subject to the same significant limitations as batteries. The B-Class F-CELL, for example, can travel 400 kilometers without refueling. This range could be extended, and refueling only takes a few minutes. “Fuel cell systems can also supply larger vehicles like the C and E-Class with sufficient energy,” says Mohrdieck. “Our stated objective is to develop reliable premium vehicles equipped with fuel cell technology.”

Optimizing components This will require more or less hidden components to perform new tasks, says Bernd Hense, head of the Advanced Development Center Powertrain and Interior E/E: “If you want to put fuel cells in those kinds of cars, you have to alter the vehicles’ power electronics, their control systems, and the relays for various drive system elements to accommodate 600 volts or more, as opposed to the 120 volts they run on today. The components would also have to work in a much smaller space and at the high temperatures experienced by automotive drive systems.”
The key aspect here involves “developing a set of components and modules that enables the most simplified electronics scalability possible for different performance classes and vehicles.” According to Hense, vehicle range is essentially determined by the performance of the battery - but, as he says: “The only way to get the most out of the powertrain is through an optimal arrangement of the power electronics and its interaction with batteries and electric motors.”

Intelligent combinations Development engineers in a team headed by Klaus Badenhausen, the chief engineer A/B-Class and smart, are also seeking to combine modular drive system components in the most effective manner in different types of vehicles. “We want to put together technology kits in which components for different types of drives can be combined in line with vehicle requirements,” says Badenhausen. “This involves the lithium-ion batteries used in hybrids and fuel cell and battery-powered vehicles, as well as electric motors.”

Still, Badenhausen says, such “green” cars must be affordable: “That’s why we consider economic considerations when developing zero-emission vehicles.” Safety is also always a priority: “Our fuel cell cars undergo the safety tests designed for our normal production vehicles. And here, we pay special attention to the complete hydrogen system.”

The growing need for mobility worldwide and ever-scarcer resources are accelerating the pace of innovation. “Today, we already have technological solutions that would have been unthinkable for mass production just a few years ago,” says Badenhausen. In other words, the future of the automobile has long since begun at Daimler.
“We invented the automobile, and we therefore feel obligated to ensure that it enjoys a sustainable future.”

“Major progress is conceivable in injection hydraulics, supercharging, exhaust gas recirculation, and combustion.”

“Hybrid technology must be integrated in the design to such an extent that no compromises need to be made with the final product.”

“The only thing you need to be able to drive a fuel cell car is a driver’s license.”

Faster, smaller, cleaner

Combustion engines

Daimler engine technology sets standards in these fields

DIESOTTO technology

The world’s first gasoline engine featuring diesel-style controlled self-ignition. Highlights: Variable valve drive, rapid adjustable camshafts, variable compression.


First series production in a large premium car - an E-Class model - in 2002. Just 1.8-liter displacement (instead of 2.3 or 2.0 liters) with compressor supercharging.

Spray-guided gasoline direct injection

Series production launch in 2006 in the CLS 350 CGI; more efficient combustion and significantly enhanced fuel economy under all conditions.

Compressor technology

Major series production launch in 1997 in the 2-liter M 111 K engine used in the C 200 Kompressor.

Exhaust gas aftertreatment for diesel engines

Daimler’s particulate filter without an additive is now the industry standard. The SCR technology (BlueTEC) using the urea solution AdBlue sets the standard for NO emission reduction in cars and commercial vehicles.

Natural gas engines

The E 200 NGT bivalent model (CNG and gasoline) has been in Daimler’s portfolio since 2004. Its M 271 NGT engine remains the most powerful unit of its type today.

Key Data

S 400 BlueHYBRID

Combustion engine
Gasoline engine V6
Rated power 205 kW / 279 hp
Max. torque 338 Nm
Hybrid module
Electric motor Disk-shaped
Rated power 15 kW as a motor
20 kW as a generator
Max. torque 160 Nm
Overall drive system
Rated power 220 kW
Max. torque 375 Nm
Overall fuel consumption
Consumption (NEDC) 7.9 l/100 km
CO2 emissions 190 g/km
Highlights from both worlds
Hybrid drives

Daimler hybrid technology sets standards in these fields

Lithium-ion batteries

High-performance batteries are the key to hybrid drives that operate reliably under everyday conditions. Daimler cooperated with the German automotive supplier Continental to bring lithium-ion batteries to the series production stage. In 2009, these batteries will celebrate their world premiere in a premium production car - the Mercedes-Benz S 400 BlueHYBRID. Daimler holds 25 patents for this technology.

Modular hybrid concepts

Daimler offers the broadest range of hybrid solutions, including everything from the stop/start function in the smart and A and B-Class to hybrid modules with booster functions, braking regeneration systems, and electric two-mode hybrid vehicles. Along with the S 400 BlueHYBRID, Mercedes-Benz will also launch the ML 450 BlueHYBRID - the world’s most fuel-efficient gasoline-hybrid SUV.

Zero-Emission Driving

Electric Drives

Daimler electric drive system technology sets standards in these fields

Fuel cell experience

Daimler has fitted more than 100 vehicles with fuel cell systems since the Mercedes-Benz NECAR 1 (New Electric Car) was built on the basis of the MB 100 D in 1994.

Fuel cells in practice

With more than three million kilometers clocked up, Mercedes-Benz has the most extensive experience with fuel cell vehicles used by customers in everyday operations.

Fuel cell reliability

The fuel cell reliability record - more than 150,000 kilometers driven with the same fuel cell - is currently held by an A-Class F-Cell model.

Lithium-ion batteries

Electric cars must have powerful batteries to function properly. The first high-performance battery research projects were launched by Daimler in 1994. In 2009, Daimler will become the world’s first automaker to install a lithium-ion battery (developed in cooperation with the automotive supplier Continental) in a production car.

Electric drives

A total of 100 first-generation smart fortwo ed (electric drive) models are now on the road in London. As part of the e-mobility project, Daimler will put more than 100 new-generation smart fortwo ed vehicles and new battery-electric vehicles from Mercedes-Benz on the road by the end of 2009. The cars will recharge at RWE stations.


HTR online contains a historical review of the drive concepts presented here, plus five informative video clips, including an interview with Herbert Kohler, Vice President Group Research and Advanced Engineering at Mercedes-Benz Cars and Environmental Officer of Daimler AG.
The DIESOTTO concept
Fuel cell drive systems
Natural gas drive (NGT)
The Mercedes-Benz S 400 BlueHYBRID
The future potential of alternative drive systems
110 years of drive innovations


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