A classic with a future

RWTH Aachen researches how to optimise internal combustion engines

Whether it be electric or fuel cells - many experts believe alternative powertrains are the future. But until that day comes, petrol and diesel engines will remain the primary foundation of individual and payload traffic.

Tremendous versatility, rationally and efficiently arranged: 
a glimpse inside the test bench building.

Tremendous versatility, rationally and efficiently arranged: a glimpse inside the test bench building.

These two classic standbys still have a lot of potential: the targets are more power with lower fuel consumption and CO2 emissions. Scientists of the Institute for Combustion Engines (VKA) at the Rhineland-Westphalia Technical University (RWTH) Aachen want to make the internal combustion engine even more efficient. However, technologies that go beyond petrol and diesel drive are not neglected. The internal combustion engine has already been in existence for about 150 years-and in this time it has achieved a great deal. Along the way, its technology has been continually refined - it has become more efficient, smaller- in a word, better. Clever scientists are to thank for this, like those found at the Institute for Combustion Engines (VKA) at the RWTH Aachen. The team surrounding Professor Dr-Ing. Stefan Pischinger, who has been leading the Institute since 1997, is primarily dedicated to classical subjects of engine technology, such as the exploration and development of new and more efficient combustion processes. Furthermore, aspects like virtual engine development, hybrid-electric power-train research and onboard electronics are receiving greater focus. This trend was duly acknowledged with the establishment of a Junior Professorship for Mechatronic Systems in Combustion Engines, to which Professor Dr-Ing. Jakob Andert was appointed.

Mechatronics is becoming a dominant discipline

In particular, the importance of mechatronics has grown steadily in recent decades, as Andert reports: "As a lynchpin connecting electronics, mechanics, and computer science, mechatronics has gradually developed from a small niche area to become the dominant discipline in future powertrains. Electronics and software make up an ever-rising share of the added value within the entire vehicle." Many consumption and emission-reducing innovations have been made possible only through the integration of high-performance microprocessors and new automatic control processes. However, growing complexity also increases the effort needed in research and development.

1-Zylinder Heavy duty- Motorenprüfstand.

1-Zylinder Heavy duty- Motorenprüfstand.

Effectively utilising this complexity while safely mastering it is one if the key factors for the trends we will encounter in the coming years

Ancillary units are increasingly electric

The field of mechatronics is currently experiencing a strong trend toward electrification of the ancillary units from the internal combustion engines - for example, the oil and fuel pump or the turbocharger - and their demand-actuated feedback control. "Variabilities in the valve train, electric turbocharging units and innovative concepts for variable compression are only a few examples," explains Andert. The introduction of a higher vehicle voltage combined with stronger application of electrical energy in transient operation also appears to be an interesting alternative to cost-intensive full hybrid electric powertrains. In the process, an engineer must think beyond his traditional academic field, as Andert explains: "The mechanics, the electronics, the higher-level automatic control - all these concepts have a strongly interdisciplinary character.”

Driving behaviour as efficiency factor

Andert believes that we are in the middle of a sea change in mobility. Drivers and their behaviour on the road must also be integrated into an overall concept for lower consumption. At the same time, intelligent assistance systems help the driver mobilise the vehicle more efficiently. "The inter-action of vehicles with their environment and one another is enabling assistance functions that are already making semi-automatic driving a reality today. Intelligent control strategies allow us to achieve impressive benefits in consumption under real driving conditions without sacrificing comfort." Here one goal is also to better transfer the improvements achieved in the test cycle to actual road traffic. "At the moment we are working on linking complex traffic simulations involving several vehicles communicating with one another in real time with real test rigs," explains Andert. "Doing this enables us to realise test scenarios for future applications today - for a networked environment, which still does not yet exist in this form."

Along with conventional test equipment for internal combustion engines,  the VKA has a special E-motor test bench.

Along with conventional test equipment for internal combustion engines, the VKA has a special E-motor test bench.

Think beyond 'either/or'

And how does the Aachen-based researcher evaluate the trend occurring in alternative powertrains? Will they replace the internal combustion engine at some point? "I would like to get away from either/or thinking here," says Andert. "No powertrain is optimal for all requirements and driving profiles. We will certainly experience greater diversification in technologies."

Hybrid vehicles impressively show us how the internal combustion engine can fully utilise its strengths in combination with mechatronics systems

The strengths of the electric powertrain are most apparent in inner-city traffic with short distances and multiple braking applications. However, using storage with high energy density - like diesel or even biofuels - is the most sensible alternative for long-range transportation from both an ecological and economic standpoint.
We have therefore not yet reached the end of the long history of the internal combustion engine.

Source: "Heartbeat" - The magazine of the KSPG Group, Issue 02/2016

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