The vehicles of the future will require higher voltages than current models. New electrically conductive lubricants will help protect electric motors and alternators from wear. Thanks to the joint efforts of basic and industrial researchers in Germany, the new substances required to achieve this have already been developed.
Stuttgart – In the future, electrically conductive lubricants will protect electric motors from the surface damage that can result from electrical discharging in the bearings. With these findings, which are the result of a joint research project, a group of German basic and industrial engineers have taken an important step toward achieving the sustainable electromobility of the future. The project is funded by the German Federal Ministry for Education and Research.
The initiative was launched to prepare for the vehicles of the future, which will require higher voltages than current models. At present, 12 volts are required to provide all automotive electric systems – from lights and radios to air conditioners – with sufficient power. Within the next few years, the figure is expected to rise to 48 volts, as electric power is required for a growing number of functions. The voltage levels of electric and hybrid vehicles are even higher: these vehicles can require as much as 400 volts.
Stronger alternating electric fields “In alternators and electric motors, higher volage levels mean that alternating electric fields are stronger than they once were,” says Dr. Gerd Dornhöfer, one of the Bosch associates taking part in the “SchmiRmaL” project (Switchable intelligent tribological systems with minimal friction losses and maximum lifespan). This can cause, for instance, electrical discharge in the ball bearings of motors and alternators. When this occurs, sparks may fly that can melt tiny areas of the metal’s surface. This, in turn, leads to uneven raceways. As a result of this, the ball bearings first begin to make noise, and then to malfunction too soon. “We can already prevent this from happening reliably with the lubricants we have developed,” says Dornhöfer as he looks at the measurement results on his computer. The chief expert for lubrication technology works for the corporate research department in Gerlingen, close to Stuttgart.
Anyone who has ever gotten a small electric shock from a doorknob is familiar with static charges. When the finger is just a few millimeters from the doorknob, an electric spark jumps between the two. The higher the electric tension, the further the spark travels. The air between the door handle and the finger acts as an insulator until the finger is close enough to the knob.
Lubricant film acts as an insulator The same thing can also happen when a current is generated between the shaft and housing of an electric motor, as the lubricant coating in the bearing acts as an insulator. As rotation speed increases, the lubricant greases in the ball bearings separate the bearings from the raceway. This is comparable to hydroplaning on wet roads. Unlike on roads, however, this phenomenon is desirable in ball bearings, as it minimizes the friction generated by the bearings as well as the surface damage. However, this can also lead the bearings to recharge when the lubricant film is intact, similar to a capacitor. When the built-up voltage is sufficient, it can penetrate the insulating lubricant grease. This energy suffices to briefly melt a tiny area of metal on the bearing’s surface. If this happens repeatedly, tiny imperfections eventually appear on the bearing. “We want to prevent this at all costs, as it can result in greater damage to these spots over time,” says the Bosch scientist. Engineers refer to this as electrical pitting. The process results in damaged areas on the raceway that are comparable to potholes. In the future, the energy of these discharges may become greater as the power density and voltages of automotive electric systems increase.
In light of this potential problem, the SchmiRmal project’s strategy focuses on developing new lubricants, whose substances remain conductive even at higher voltage levels. As a result, these lubricants do not act as insulators to begin with. Voltage levels no longer build up, nor does potentially destructive electrostatic discharge.
“This can be achieved in several ways,” said Dornhöfer. “One could, for instance, add fine metal particles to the grease to conduct the current. But this would mean that the lubricant grease would also act as an abrasive, and of course we want to avoid this.” Here, ionic fluids are more suitable. In chemical terms, these comprise molecules known as ions that conduct an electrical charge. “Ionic fluids conduct electricity, and this is why we add these substances to our lubricants,” said Dornhöfer.
Resistance reduced by a factor of ten million Following countless tests, the scientists have now come up with greases that are less and less resistant to electricity. In other words: the lubricant conducts electrons as desired in the ball bearing and thus prevents the dreaded electrical flashovers. The initial material was a commercially available industrial lubricant. “By using the right ionic fluids combined with conductive carbon, its resistance can be reduced by a factor of ten million,” says the Bosch scientist. This is enough to prevent the unwanted electrical discharges.
While the new grease is black, it otherwise largely resembles its predecessor. At present, Dornhöfer is focusing in part on investigating all of the grease’s characteristics. To ensure a long life cycle, ball bearings must be heat resistant and have cold flow properties. Moreover, the new additives should not compromise the grease’s corrosion protection properties. And it goes without saying that the new grease should not pose a hazard to human health or the environment. All of this is currently being tested as part of the BMBF project. “So far, our findings have been very promising”, Dornhöfer says.
Many scientists from a broad range of disciplines and sectors have contributed to this success. “No one can find these solutions alone. We are all contributing and learning from one another,” Dornhöfer says. The project is set to run until April 2015. “Chances are high that the new lubricants will find industrial application after the project.”
A longer service life for many machine components The benefits of the project’s work go well beyond applications for electric motors. The new lubricants can also increase the service life and reliability of machine elements that experience high levels of strain, especially roller and plain bearings and transmission components. Moreover, performance can be improved for motors of the same size, or maintained if motors are smaller. At the same time, the lubricants contribute to reducing energy consumption and to increasing efficiency.
The project participants Klüber Lubrication SE & Co. KG (Munich) is one of the world’s leading and most innovative specialty lubricant manufacturers. IoLiTec-Ionic Liquids Technologies GmbH (Heilbronn) develops ionic fluids. Schaeffler Technologies GmbH & Co. KG (Herzogenaurach) is an automotive supplier that develops and manufactures rolling bearings. The company’s role in the project is to assess how new types of oil can improve the service life of bearings. Inprotec AG (Heitersheim) develops highly effective coatings that protect against abrasion. Over the course of the project, SCHUNK GmbH & Co. KG (Lauffen/Neckar) is working on improving the durability of a valve. Using computer models, the Fraunhofer Institute for Algorithms and Scientific Computing SCAI (Sankt Augustin) is making forecasts about the potential environmental impact of new ionic fluids. Over the course of the project, the Fraunhofer Institute for Mechanics of Materials IWM (Freiburg im Breisgau) is focusing mainly on the potential lubricating effect of ionic fluids. Bosch is applying these new lubricants and testing their suitability under real-world conditions.
CoCoS project to bolster German manufacturing with support of German Federal Ministry for Economic Affairs and Energy
Development of an infrastructure for cyber-physical production systems in smart factories
Flexible communication instead of fixed, hierarchical levels
Stuttgart – In the future, cyber-physical production systems (CPPS) will allow industry to manufacture more flexibly and efficiently. Made up of intelligent machines, storage systems, and operating resources, these systems can autonomously exchange information, trigger processes, and control each other. An important foundation still missing for CPPS, however, is an integrated information and communication infrastructure that connects the entire system and other CPPS to each other, even between companies. A research team has set itself the task of developing this infrastructure. Supported by the German Federal Ministry for Economic Affairs and Energy, the CoCoS (Context-Aware Connectivity and Service Infrastructure for Cyber-Physical Production Systems) project kicked off at the beginning of this year and is set to run through the end of 2016.
Shifting away from the automation pyramid Present-day production systems are organized hierarchically. In line with the classic automation pyramid, each process is assigned to a level. The fact that each level has its own function and sometimes even its own communications technology can lead to data discontinuity. As a result, changes in the production process – especially at interfaces – are cumbersome, time-consuming, and consequently expensive. In contrast, CPPS can promptly respond to a changed need. Because all technical production processes are closely linked to the business processes, they can be easily and flexibly controlled or modified to allow optimum use of resources. CPPS relies on cooperative network architectures, not hierarchical ones; this means the entire CPPS is connected, including all sensors and actuators. Moreover, it is designed to connect to several CPPS and also integrate isolated solutions. This allows companies to control the entire production process uniformly and across locations, from management to logistics.
Networking and services platform Working in what is known as a multi-layer approach. CoCoS project researchers want to use standardized software to integrate the individual production components into the overall system – merging what were previously separate levels to create a flexible structure. The CPPS landscape is based on two platforms. First, the networking platform, which is scalable and hence easily expanded, determines the way in which the manufacturing components as well as the embedded sensors and actuators communicate with each other. Building on this networking platform, the services platform comprises software for controlling the entire modular system and includes smart applications such as software agents, knowledge databases, and business apps. This structure supports the development of new electronic services and makes modern manufacturing facilities more autonomous. Cloud computing can be used to integrate and couple together different cyber-physical production systems.
Research collaboration A consortium of industrial companies and academic partners are working on the CoCoS project. Heading up the project is Robert Bosch GmbH in Stuttgart. Additional partners are the German Research Center for Artificial Intelligence GmbH (DFKI) in Kaiserslautern, DMG Electronics GmbH in Pfronten, Technische Universität Berlin, trustsec IT-Solutions GmbH in Stuttgart, and XETICS GmbH in Stuttgart. To document the performance capacity of the new platform philosophy, three of the partners – Bosch, DFKI, and DMG – are each building a demonstrator. These individual demonstrators will then be coupled together and evaluated.
Contribution to Industry 4.0 The CoCoS findings will lend themselves to application wherever production is split into several steps, such as the delivery of raw materials, the manufacture of components, or finished products – even when the production steps take place in different companies or at different locations belonging to a single company. CoCoS is thus helping to establish CPPS, which in turn will form the core of smart factories. Industry will be able to use the structures and functions of the internet of things to create smart, flexible production systems, making them a vanguard of the so-called fourth industrial revolution (Industry 4.0). This could give Germany a distinct competitive advantage both as a manufacturing location and as a leading global provider of plant equipment. Part of the “Autonomics for Industry 4.0” technology program, CoCoS is receiving some 2.4 million euros of funding from the German Federal Ministry of Economic Affairs and Energy (BMWi), following a decision in the German Bundestag.
Sustainable mobility and manufacturing operations of the future
Supported by federal and state government
The ARENA2036 project marks the start of a new research partnership. Scientists from the University of Stuttgart, independent research institutes, and industry are joining forces on a brand new campus to work on ideas for the mobility of the future.
Stuttgart – A joint project for the vehicles of the future: on the new ARENA2036 research campus, universities and companies will be working to develop the flexible factory for the car of the future and its new lightweight components. The project aims to develop new and competitive production models by 2036, when the car celebrates its 150th anniversary.
“We are pleased to be taking part in this promising project, in which scientists from a broad range of disciplines are cooperating, often beyond the boundaries of their respective areas of expertise,” says Dr. Volkmar Denner, chairman of the Bosch board of management. “In many areas, the mobility of the future cannot be achieved using the means we have today. To make it a reality, experts from all disciplines must come up with new and creative solutions.” ARENA2036 focuses primarily on new fiber composites and flexible manufacturing systems.
To make the factory of the future more flexible, ARENA2036 is researching technologies for new types of robots, for instance. In addition to this, the initiative aims to develop new methods and tools for the planning, configuration, and operation of flexible manufacturing systems. This could be relevant not only in automotive engineering, but also for components in many other industries.
ARENA2036 partners Apart from the University of Stuttgart and Robert Bosch GmbH, the Deutsche Institute für Textil- und Faserforschung Denkendorf (DITF), the German Aerospace Center (DLR), the Fraunhofer Institute (FhG), BASF SE, and Daimler AG are taking part in the ARENA2036 project. The project is the result of a competition organized by the German Federal Ministry of Education and Research (BMBF), over the course of which ten public-private partnerships were selected. Thanks to the judges' positive decision, many new projects will receive funding over the initial five-year project phase. Over a maximum period of 15 years, each selected research campus will receive funding of up to two million euros per year.
Opportunities for Germany as an industrial location “The automotive industry has always been one of the major drivers of German innovation,” Denner says. “The foundations for many technical applications were laid here. Their effect extends to many other sectors and industries. By developing promising materials systems, manufacturing processes, and design principles, we are opening up new and major opportunities for Germany as an industrial and research location. We must seize these opportunities – and ARENA2036 is helping us do so.”
The greatest possible flexibility At present, most automakers manufacture one single product per assembly line. Such factories are generally not very flexible, and changing lines to accommodate different products is time-consuming and expensive. Flexible manufacturing offers a solution to this problem: it marks a move away from line assembly in favor of manufacturing concepts that can be implemented within days rather than months, and this at a low cost. This principle can also be applied to the production of components. A number of current trends make this flexibility necessary. One of them is the growing need to customize mass production. For instance, customers are increasingly demanding vehicles with different powertrain systems, such as gasoline, diesel, natural gas, battery, hybrid, or fuel-cell systems.
Moreover, in the factory of the future, new designs and materials, such as functionally integrated lightweight components, will play a major role. With their specific design and precisely controllable manufacturing process, lightweight fiber composites make it possible to integrate a broad range of functions into individual components. The broad spectrum ranges from sound and heat insulation and thermal, sensory, or electrical functions, to liquid or energy storage.
Three areas of research ARENA 2036 addresses three areas of research. The first focuses mainly on new lightweight materials. The main topic of research in the second area is the simulation of these lightweight materials using digital models and virtual prototypes. The third area of research addresses the design of a flexible research factory for the large-scale series production of vehicles and components. Bosch associates are involved in all three areas.
Creative environment “Tens of thousands of engineers from academia and industry in the Stuttgart region have played a part in pushing research and development in automotive engineering forward. With multifunctional fiber composite plastics and flexible production, two important trends have emerged that require further thought and interdisciplinary cooperation. The knowledge-sharing on the research campus ensures better coordination between basic research and pre-competitive, application-oriented research. This result is a creative environment for new ideas and their rapid transfer to industry,” says Kerstin Mayr. Mayr, who works for the Bosch corporate research sector, supervises the ARENA2036 topic for Bosch.
A completely new building – courtesy of the state The research initiative began its activities on July 1, 2013, at a temporary site. In 2017, the project will be moving to its own large building, constructed especially on the University of Stuttgart's Vaihingen campus. Covering a total surface area of some 7,000 square meters, the building will house offices, laboratories, and production areas. Up to 160 new jobs will be created there, and the total investment for the new building amounts to some 30 million euros. This research factory is being built by the state of Baden-Württemberg, which will be providing the facility to the ARENA2036 research campus free of charge, except for running costs. The project was officially established as an association in May.
The newly established association now counts several companies as its members, including Bär Automation, Faro, and Festo. New partners are always welcome. The participating companies and research institutes will be considered members and expected to pay membership fees.
“PV Home Storage System” (PV-HOST) research project
Optimizing battery systems in 10 kWh size class
Energy storage systems make important contribution to Germany’s move to alternative forms of energy
Stuttgart – The number of single-family homes installing rooftop photovoltaic systems is steadily rising; any extra electricity they generate has to be fed into power grids as required. However, these grids, built up over many years according to historical need, are not always able to absorb all the electricity produced. Especially in areas with a lot of distributed producers, this kind of overloading will only get more acute without outside help. This is where battery storage systems for buildings with solar arrays come in: they store electrical energy until it is either needed within the household or can be absorbed by the grid, smoothing out supply peaks and increasing grid capacity. If stationary storage systems with a capacity of up to ten kilowatt hours are to work cost-effectively and efficiently feed the electricity generated into the grid, what should they look like? The current PV Home Storage System (PV-HOST) research project explores precisely this question. The goal of the project is to optimize distributed battery storage from both technical and economic perspectives. To do this, three research partners are systematically comparing the solar storage technologies currently available from German manufacturers that are potential candidates for use in single-family homes over the next few years.
Better interaction between energy storage systems and the grid At present, less than one percent of German single-family homes with photovoltaic systems have a solar energy storage system despite incentives by the government-owned KfW development bank to invest in this technology. Previous research projects in this area concentrated on further developing a specific storage technology and generally sought to increase the proportion of electricity households used that they themselves had generated with the goal of making them as self-sufficient as possible. In contrast, the PV-HOST project provides an overview of the different technologies. The researchers want to find out what operating strategy allows a household storage system to most effectively serve grid needs. In other words, the storage system should not just cover the household’s own needs, but also reduce supply peaks, ensuring that the grid can absorb more energy from solar installations on the whole.
Comparing different battery types The project partners are evaluating four battery types: lithium-ion, lead-acid, high-temperature, and redox flow batteries. For each type, the researchers are working out the technical and economic potential. On top of this, they are investigating three further issues: the optimum configuration of the entire photovoltaic storage system – effectively, the size and power of the various components – the optimum operating strategy for the battery storage system, and the optimum means of integrating distributed storage systems into the power grid. In particular, the team wants to subject lithium-ion batteries to comprehensive lab and field tests. The goal of the research into high-temperature batteries is to minimize heat loss and thereby improve efficiency.
Optimized technology for lower costs In order to increase renewables’ share of overall power supply, storage technology has to be further developed. PV-HOST is contributing to the success of Germany’s move to alternative forms of energy, because solar energy storage systems have a big role to play here. They allow more photovoltaic systems to be usefully integrated into existing grids, meaning that less power is required from conventional power plants. Compared to central storage systems, battery storage systems have the advantage of presenting a lower investment hurdle. In addition, the self-generated electricity households feed into the grid is very lucrative for them. Another key issue is costs, and here the researchers are seeking to optimize battery storage systems to make them even more cost-effective.
Research collaboration Led by Robert Bosch GmbH, the research project has two other partners – the Institute for Power Electronics and Electrical Drives (ISEA) at RWTH Aachen University and münsterNETZ GmbH, the grid operator for the Münster municipal works. PV-HOST began in July 2013 and will run for four years. The project is part of the German government’s Energy Storage Funding Initiative and has received a grant of three million euros from the German Federal Ministry for Economic Affairs and Energy.