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Gentlemen, start your engines!

Text
Johannes Köbler

Photos
Ulrike Myrzik

TDI, TFSI and g-tron – Audi has a broad base when it comes to the drive technologies of the future. Board Member for Technical Development Prof. Dr. Ulrich Hackenberg and his team explain the strategy.

STRATEGY

CO2 reduction remains an obligation we are very happy to fulfill. But our free program is to inspire customers with our new technologies, emotion and driving fun. That’s the Audi way – in which we want to become even stronger.

Prof. Dr. Ulrich Hackenberg
Audi Board Member for Technical Development

Dr. Hackenberg, 2020 will see the introduction in the EU of the fleet emissions limit of 95 grams CO2 per kilometer. What driveline measures does Audi intend to use in order to achieve this?

Dr. Hackenberg: We’re pushing forward with development in three areas. The first of them is the further optimization of conventional drives, i.e. gasoline and diesel engines, the transmission and the rest of the driveline. In all engines, we are concentrating on the further development of the combustion process, forced induction and injection technologies and thermal management as well as friction reduction. In transmissions, we’re working hard on measures to improve efficiency, by which I mean on-demand lubrication or new lowfriction oils.

The second area is the development of our model lineup. This is where we see great potential for our TDI engines in the USA – our clean diesel offensive is bearing substantial fruit. In China, too, we are already introducing the first clean diesel models and watching developments there very closely. We also expect a great deal from g-tron technology, the most sustainable type of gas drive.

Prof. Dr. Ulrich Hackenberg, 64, came to Audi in 1985. From 1998 until 2002 and from 2007 until 2013 he worked for Volkswagen, most recently as Board Member for Technical Development. In 2013 he returned to Ingolstadt in the same function. Prof. Dr. Hackenberg is also responsible for guiding cross-brand development for the Volkswagen Group.

The third area is surely electrification?

Dr. Hackenberg: Yes, and this is very important indeed. Even by 2020, it will contribute around 30 percent to fuel savings. We will realize electrification across the breadth of our product portfolio, from so-called mild hybrid systems all the way to purely battery-electric drives. The bottom line is that the drive contributes two thirds of the CO2 savings. The rest is on the vehicle side, where we will reduce aerodynamic drag even further.

You are pursuing two avenues in electrification – with electric-only drives and with plug-in hybrids. Which route promises the most success in the long term?

Dr. Hackenberg: The plug-in hybrid, i.e. PHEV technology, is the main contender as things currently stand, because it combines the benefits and also the complexity of the internal combustion engine and electric drive. It enables zero-local-emissions driving, while solving the range problem at the same time.

How much range does a fully electric car need in order to be accepted by customers?

Dr. Knirsch: Customers today are used to being able to drive around 500 kilometers on one tank. They apply the same expectations to a battery-electric vehicle – a BEV. The further development of battery technology will be a decisive factor in achieving this objective. Once the issue of recharging has also been addressed – through a sufficient charging infrastructure and inductive charging, which we’re working on – we can very quickly reach the turning point at which customer behavior changes and electromobility takes off. When that will happen, however, nobody can predict right now.

How great is the range on the R8 e-tron, the all-electric sports car?

Enzinger: We are making really big development steps with the R8 e-tron 2.0 compared with the last version. The range was previously 215 kilometers in the NEDC, and now we are talking about considerably more than double that distance. This is thanks to the optimization of drive and drag, but first and foremost the new battery technology.

And what does that look like?

Kötz: The package – the geometry, the cooling, the weight and the chassis integration – is practically the same. But we have switched to a further developed technology for the cells that is specifically adapted for BEV applications. It can therefore be used just as well in the automotive sector as in consumer devices, where it’s already well established. Power is slightly lower in the new generation of cells, but the energy is considerably greater. Because of the size of our battery, the slightly lower power is not a problem, while the added energy brings the longer range.

Are consumer cells the standard for the future?

Hudi: Right now, the module of round cells delivers around 360 watt hours of energy per liter of volume, which is already very attractive. But development is progressing quickly with prismatic cells and so-called pouch cells. Within the foreseeable future, automotive cells will achieve a far higher volumetric energy density than round cells due to their module-based packaging benefits.

E-DRIVE

With the R8 e-tron, we have more than doubled the range compared with the last version. We have developed all the drive components and switched the battery to a new cell technology.

Markus Enzinger
Head of Development Drive Electrification

Kötz: We are experiencing rapid development. In the PHEV segment, energy densities have grown by 30 percent in the last four years, while costs have fallen significantly. PHEVs also demand the most from the battery, because they call for long range as well as high performance.

Does Audi build the batteries for the R8 e-tron itself?

Hudi: Yes, at our High-Voltage Battery Technical Center next to the factory. It’s a perfect example of in-house production that helps us to understand and penetrate the process chain from start to finish. Using the expertise we are building up here, we’ll be able to achieve optimum solutions with parts we subsequently outsource.

And what is the situation as far as series production is concerned?

Hudi: We have produced all the batteries for the R8 e-tron in our project house. When it comes to larger volumes for future models, we will take the decision when the time comes. I should add that we opened a new project house just a few weeks ago, which is dealing exclusively with BEV technology. All the departments and disciplines from Technical Development and the rest of the company are working close together here in one location.

What other advances are there with the R8 e-tron 2.0?

Enzinger: We have developed all the drive components – the power electronics, the transmission and, of course, the two high-performance electric motors. We have now reached a very high level in terms of power density and efficiency.

After the R8 e-tron, what will be Audi’s second all-electric car?

Dr. Knirsch: We can envisage putting a long-distance BEV on the road in the 2017/2018 timeframe. It will be a model with its own highly distinctive architecture and an amazing drive that fits perfectly with the Audi character.

At the Los Angeles Auto Show, Audi presented the h-tron show car – an A7 Sportback with fuel cell drive. What is the series-production potential of this technology?

Kutschera: It’s very interesting, because it in no way restricts the customer in terms of its range and the time taken to fill the tank. As a premium manufacturer, we feel it is our technological obligation to push forward Audi-typical interpretations of such innovations – although there is still no hydrogen infrastructure..

We are developing the fuel cell to the point that we can put it into production when the customer wants it. For us, the h-tron is not only a customer-friendly zero-emissions vehicle for long distances, i.e. a fulfillment of CO2 requirements; its performance data well in excess of its competitors means it’s far more a determined step toward sporty emotionality, making it a perfect fit for our brand identity.

DRIVE

We demonstrated with the RS 5 TDI technology showcase the kind of potential offered by the electric turbocharger in combination with the TDI engine. But this technology would also make sense with gasoline engines.

Dr. Stefan Knirsch
Head of Development Complete Engines

What is the roadmap for the plug-in hybrid models?

Dr. Hackenberg: It began this year with the launch of the A3 Sportback e-tron. The Q7 e-tron will follow in 2015, after which we will bring a rapid succession of further plug-in hybrid models to market – one per year. They are based on the MLB evo, the second-generation Modular Longitudinal Platform, although their drives will differ considerably. The MLB evo is well prepared for the new technologies. We can basically envisage all interpretations of an electrified vehicle – from the electric motor integrated into the drivetrain to concepts that put the motors at the front and rear axles. This kind of thing would be particular interesting in the performance sector.

Is an Audi R8 with hybrid drive also conceivable?

Dr. Knirsch: This is something we certainly can envisage, because it’s here in particular that the two worlds combine very well with one another. The interaction of an electric motor – which delivers high torque at low revs and can provide added boost under high load – with the great emotion of an internal combustion engine could be a decidedly appealing combination.

HIGH-VOLTAGE SYSTEMS

We produce the batteries for the R8 e-tron ourselves in our High-Voltage Battery Technical Center. It’s a perfect example of in-house production that helps us to understand and penetrate the process chain from start to finish.

Ricky Hudi
Head of Development Electric/Electronics

Enzinger: Electrification doesn’t mean that we are restricting ourselves to BEVs or PHEVs. We are developing a broad technology platform that covers all variants from mild hybrids based on 12 and 48 volts, through to high-performance electrification concepts.

Hudi: The 48-volt partial network is a highly significant technology. The step from 12 to 48 volts is overdue. It’s the only way we will be able to realize the new, dynamic high-performance consumers such as the electric turbocharger.

Dr. Knirsch: Or the integrated starter/generator that we’ll shortly be putting into production. We are achieving recuperation powers of more than 10 kW with it – which will bring considerably greater benefits in reallife customer use than in the NEDC. We’re also raising comfort with the partial 48-volt network, as our customers barely notice that the engine is switching on and off, enabling them to coast with the engine turned off. And we also have the option of introducing the electrically assisted turbocharger, as Ricky Hudi just said.

When will it enter series production?

Dr. Knirsch: I assume that the next five years will see a succession of production models with this new technology. We demonstrated with the RS 5 TDI technology showcase the kind of potential offered by the electric turbocharger in combination with the TDI engine. It would also make sense with gasoline engines, particularly those with high specific output.

Audi celebrated a major triumph at the 24 Hours of Le Mans with hybrid technology. How can motorsport help series development?

BATTERY SYSTEMS

We are experiencing rapid development. The energy density of PHEV batteries has grown by 30 percent in recent years, while costs have fallen.

Jens Kötz
Head of Networking and Energy Systems at Audi

Baretzky: At Audi Sport, we have learned a great deal over the last couple of years about the way the two drives work together. Their management helps us not only to reduce consumption considerably, but also to improve longitudinal and transverse dynamics – although the regulations unfortunately set very tight limitations. In principle, though, what proves itself at Le Mans is also good for our customers. In many cases, we are able to open doors within the company for our series-production colleagues.

How closely do you work together with them?

Baretzky: The interaction is so fruitful that it is the envy of our competitors. We want to learn as much as possible about forthcoming challenges in series production in order to drive forward the motorsport regulations appropriately. Back in 2011, we were already talking to the organizers in Le Mans about the efficiency regulations that subsequently came into force in 2014. It gives all the teams a great deal of freedom – and I think we’ve used that very well. We reduced fuel consumption by around 22 percent compared with the previous year and won the race once again.

What important ideas from race engine development have so far flowed into series production?

Baretzky: A perfect example is surely TFSI, the gasoline engine with forced induction and direct injection. We used it for the first time at Le Mans in 2001 and three years later it went into series production. We’re providing important impetus for the TDI engines, too, such as steel pistons. In combination with the new cylinder architecture, they permit us to use incredibly high ignition pressures, which lead to extreme efficiency – and all of that in a lightweight aluminum engine. Our maximum injection pressures are above 2,800 bar.

Kutschera: In series TDI engines, we are currently achieving 2,000 bar. The models with 2,500 bar will enter series production next year and we are looking at 3,000 bar for 2020. The higher the injection pressure the more precise the mixture formation.

Baretzky: I would also like to mention that, years ago, our external common-rail system partner was of the opinion that the issue of injection pressure ended at 2,000 bar. We applied a lot of persistence to break through this barrier, becoming a development driver in the process.

Hudi: When it comes to engine management, the discussion always surrounds the processors. In production, we’re benefiting significantly from our Progressive Semi-Conductor Program, by cultivating strategic partnerships with the world’s most important semi-conductor manufacturers. We are in direct discussions with them and not just with the system suppliers. The PSCP is a major contributor to being able to recognize innovative solutions at an early stage.

Another important field of technology in combustion engines is forced induction. What do you have up your sleeves there?

Kutschera: We’re very interested in new, lighter materials, especially on the turbine side. They further improve transient behavior, allowing high dynamics and more precise adaptation of the operating points in dynamic cycles. They’re indispensible for the forthcoming emissions legislation. And the electric turbocharger presents a whole new approach to charging technology.

MOTORSPORT

In principle, a technology that proves itself at Le Mans is also good for Audi customers. In many cases, we are able to open doors within the company for our series-production colleagues.

Ulrich Baretzky
Head of Audi Sport Engine Development

Over the next few years, where will Audi engines be in terms of consumption, power and torque?

Dr. Knirsch: We will be able to reduce the fuel consumption of our engines by roughly another 15 percent by 2020. The next few years will bring a specific output of 100 kW per liter for our TDI engines. When it comes to torque, we are already at around the 250 Nm per liter mark, and we will be able to improve on this, too. We showed what can be achieved with the TFSI with the TT quattro sport concept – 155 kW of power per liter and a maximum torque of 450 Nm from a displacement of two liters.

What is the role played here by the five-cylinder engine, the 2.5 TFSI from the compact RS models?

Dr. Hackenberg: It’s an engine with all the attributes you need to trigger goose bumps. The turbocharged five-cylinder is a highly emotional piece of Audi heritage and we will continue its success story. The A3 clubsport quattro concept that we presented this year at Wörthersee is an impressive display of its potential.

Speaking of legends: If you were to present a new version of the Audi Ur quattro, what drive concept would it have to have?

Dr. Knirsch: One that carried forward the emotionality and superiority of the original drive. Our modular engine programs have a lot to offer – prepare for a surprise!

How can new driver assistance systems contribute to efficiency?

Dr. Knirsch: The predictive efficiency assistant that we’ll soon be putting into series production can select the optimum operating point for the drive with the aid of extremely precise navigation data and other parameters. For instance, if it is obvious that the current incline is followed by a decline, you can empty the battery of a mild hybrid in order to use up the energy – it can then be regenerated immediately afterward to fully recharge the battery. In real-life customer usage, the predictive efficiency assistant delivers CO2 savings of up to ten percent, and even more in some cases.

ADVANCE DEVELOPMENT

We will be able to achieve a specific output of more than 100 kW per liter for the TDI. When it comes to torque, we are already at around the 250 Nm per liter mark and aiming for 300 Nm.

Immanuel Kutschera
Advance Development V Diesel Engines/Fuel Cells

What advances is Audi planning in power transmission?

Dr. Knirsch: We’ve pulled out all the stops with the new seven-speed S tronic, the DL 382, including a quasi dry sump concept with electric oil pumps and plate separation of the clutches. We’ve achieved targeted reductions in friction losses and achieved a whole new level of efficiency. We intend to continue on this path. In the quattro drive, too, we want to use intelligent systems to reduce friction even further.

What transmissions will Audi use in future?

Dr. Knirsch: We are continuing to develop the converter automatic for use in the big models. It’s still unsurpassed in terms of comfort. Nevertheless, the S tronic has now reached an almost comparable level and, when it comes to performance and efficiency, remains unbeatable. The competition between the different concepts serves as motivation for both sides, as well as our suppliers of converter automatics.

The road to efficiency and performance – Dr. Hackenberg, how would you sum up the Audi driveline strategy?

Dr. Hackenberg: For me, the issue is to resolve former contradictions. Refined power, sporty performance and low consumption do not stand in opposition at Audi. This is also evident from our highly efficient ultra models – a lineup that we will continue to expand rapidly. CO2 reduction remains an obligation we are very happy to fulfill. But at the same time, our target – our free program, you might say – is to inspire customers with our new technologies, deliver them emotion and driving fun. That’s the Audi way – one in which we are already very strong and want to become even better.