In order to increase the attractiveness of the electric mobility, neither the comfort nor the driving range of the vehicle may suffer under extreme ambient temperatures. Optimized thermal management helps to meet customer comfort requirements, while at the same time reduces energy demand . In this article, the structure and the validation of a new developed simulation model are explained. Based on the model, measures to reduce the energy demand with regard to cabin temperature control are investigated. Finally, the results, as well as a summary of the energy saving potentials are presented.
The generated vehicle simulation model consists of several modular components, as depicted in Figure 1. Each of these objects represents a subsystem of the electric vehicle. With this model, it is possible to simulate different driving profiles, as well as ambient conditions. Thus, various thermal management measures can be assessed regarding their influence on system efficiency [2, 3]. For the validation of the simulation model, measurements were carried out on both, the component and system level.
Various cabin measures are investigated regarding their energy saving potentials with the created simulation model. All simulations were conducted during the WLTP driving cycle for 30 minutes at an ambient temperature range from -20 to +20 °C. At the same time, the cabin is heated from the respective ambient temperature to an average cabin temperature of 20 °C and the total energy demand is determined. In addition, to the energy savings for a particular ambient temperature, the energy saving potential in annual means is calculated. Therefore, climatic data from Europe is used . The results, which are referred to as Reference in the following, show the energy consumption of the electric vehicle when the cabin is heated up only with the PTC-air heater. Under these conditions, the vehicle has an energy demand of 31.4 kWh/100 km at an ambient temperature of -20 °C. This result is also used as a reference point for the calculation of the energy savings. Furthermore, the energy consumption of the vehicle without heating the cabin is shown in all diagrams. It is 22.2 kWh/100 km at an ambient temperature of -20 °C and is therefore, significantly below that of the heated vehicle, as seen in Figure 2.
>> AS A FURTHER MEASURE TO REDUCE HEATING ENERGY DEMAND DURING WINTER OPERATION, RADIATION SURFACES ARE CONSIDERED
A promising approach for saving heat energy is a reduction of the fresh air rate in the air conditioning of the cabin. In contrast to fresh-air operation, a large proportion of the required heating energy can be saved in recirculation mode. At an ambient temperature of -20 °C, the total energy demand is reduced from 31.4 kWh/ 100 km to 27.9 kWh/100 km, which corresponds to a saving of 11.1 percent, as seen in Figure 2. Averaged over the year, this results in a saving of 3.1 percent. As a further measure to reduce heating energy demand during winter operation, radiation surfaces are considered, as seen in Figure 3.
Through the use of radiation heat surfaces, the air temperature inside the cabin can be lowered with a comparable sensation of comfort of the occupants. For the corresponding comfort tests, six electric radiation surfaces were installed in the driver and passenger foot wells (three on each side). In the simulation, the result of the previous measurements were confirmed. The energy demand at -20 °C can be reduced from 31.4 kWh/100 km to 30.1 kWh/100 km by the use of radiation surfaces. This corresponds to an improvement of 4.1 percent, as seen in Figure 2. Averaged over the year, an energy savings potential of 3.8 percent can be realized. The generated heat is sufficient to heat the cabin completely without the PTC-air heater from an ambient temperature of 10 °C or higher and without reducing the comfort for the occupants. In order to reduce the heating energy demand even further, targeted heating of the driver is chosen as another measure. The total energy demand at -20 °C can be reduced to 30.8 kWh/100 km or by 1.9 percent from 31.4 kWh/100 km, as noted in Figure 2. Averaged over the entire year, a savings of 0.5 percent is achieved. By integrating a heat pump into the vehicle, the energy demand can be reduced additionally. With the heat pump, heat can be absorbed at lower temperature levels and discharged at higher temperature levels. The amount of heat emitted is thereby much higher than the work expended . For an ambient temperature of -10 °C, the energy requirement can be reduced from 27.5 kWh/100 km to 23.7 kWh/100 km or by 13.8 percent, as depicted in Figure 2. The energy savings potential is reduced for rising ambient temperatures. The heat generated is not sufficient to heat the cabin to 20 °C at an ambient temperature of -20 °C due to the integrated compressor. For this reason, Figure 2 shows only the energy demand at ambient temperatures from -10 to +20 °C.
>> THROUGH THE USE OF RADIATION HEAT SURFACES, THE AIR TEMPERATURE INSIDE THE CABIN CAN BE LOWERED WITH A COMPARABLE SENSATION OF COMFORT OF THE OCCUPANTS
In addition, combinations of the individual measures were also considered, as noted in Figure 4. By combining the individual measures, the energy saving potential can be increased even further. The starting point for the comparison of the different combinations is the energy consumption of the vehicle in recirculation mode. Combination 1 describes the expansion of the recirculation mode with the use of radiation surfaces. The energy demand at an ambient temperature of -20 °C can be reduced from 31.4 to 27.1 kWh/100 km. This corresponds to a saving of 13.7 percent. The average energy consumption over the year can be reduced by 5.6 percent. If the system is extended by targeted heating of the driver (combination 2), 2.3 percent of the energy can additionally be saved at an ambient temperature of -20 °C. This results in an energy consumption of 26.4.kWh/100 km and thus a saving of 15.9 percent. For the targeted heating of the driver synergy, effects with other individual measures can be seen. Over the entire year, 6.4 percent of the required energy can be saved. Finally, combination 3, an expansion of combination 2 by a heat pump operation, is considered. The simulation shows that a total of 22.9 percent of the energy can be saved at an ambient temperature of -20 °C compared to reference operation. The energy demand is reduced from 31.4 kWh/100 km to 24.2 kWh/100 km. Averaged over the year, an energy savings of 7.2 percent can be determined. Using combination 3, the energy demand at -20 °C of 24.2 kWh/100 km is only 9.0 percent higher than that of the vehicle without cabin heating. Without any measures, the energy consumption with cabin heating was 41.4 percent higher than without, as seen in Figure 4.
>> A TOTAL OF 22.9 PERCENT OF THE ENERGY CAN BE SAVED AT AN AMBIENT TEMPERATURE OF -20 °C COMPARED TO REFERENCE OPERATION
Summary and Conclusion
In this article, various measures for the cabin air-conditioning have been introduced using a vehicle simulation model that reduces the energy demand of the electric vehicle at low ambient temperatures. By combining the individual measures, the shown energy savings potential can be increased even further. Throughout the year, 7.2 percent of the total energy can be saved. This saved energy can be used to increase the range and thus directly contribute to an improvement in the acceptance of electric vehicles. Intelligent operating strategies for the individual components of the thermal management system could result in a significantly higher saving potential. These operating strategies and the use of the heat pump as a refrigerating machine at high ambient temperatures will therefore be the subject of further research.
 Prokop, G.; Lewerenz, P.: Thermal Management – Solutions for New and Old Challenges. In: ATZworldwide 113 (2011), No. 11, pp. 4–9
 Haupt, C.: Ein multiphysikalisches Simulationsmodell zur Bewertung von Antriebs- und Wärme-managementkonzepten im Kraftfahrzeug. Munich, dissertation, 2012
 Lund, C.; Maister, W.; Lange, C.; Beyer, B.: Innovation durch Co-Simulation, Wärmemanagement des Kraftfahrzeugs VI. Berlin: Expert-Verlag, 2008
 Strupp, N. C.; Lemke, N.: Klimatische Daten und Pkw-Nutzung: Klimadaten und Nutzungsverhalten zu Auslegung, Versuch und Simulation an Kraftfahrzeug-Kälte-/Heizanlagen in Europa, USA, China und Indien. Forschungsvereinigung Automobiltechnik e.V., FAT-Schriftenreihe 224, 2009
 Lucas, K.: Thermodynamik: Die Grundgesetze der Energie- und Stoffumwandlungen. 5. korrigierte und erweiterte Auflage. Berlin, Heidelberg: Springer-Verlag, 2006
FEV France operates two test centers in Paris and Rouen (Normandie). In addition to the development of innovative test bench technology, one of the focal points in France is the development of electric mobility solutions. FEV is currently expanding its battery test center in Paris in order to meet stricter requirements and to expand the services offered in the Electronics and Electrification business area.
The nearly 600 square meter facility is expected to start operations this year. It will be equipped for state-of-the-art technological requirements and includes four walkable test cells for large traction batteries and four test cells for battery packs with a power supply of up to 1,200 V. Additionally, there will be up to 300 channels for testing battery cells and modules, and all test cells will be equipped with air- conditioning.
Beyond that, the new FEV Test Center will rely on extensive real-time simulation tools, which have the ability to put batteries through a simulation of streets, vehicles, and powertrains in their respective individual application scenarios. An additional test bench for e-drives will enable the complete examination of electric powertrains. The number of test benches at the two test centers operated in France will now increase to 18.
Since its foundation in France in 2004, FEV has already made a name for itself with the development of devices and software for test benches, in addition to solutions for powertrains. MORPHEE, one of the most famous automation systems on the market, is an example of widely circulated software in this context.
In the future, FEV France and its more than 700 employees will be increasingly involved in the aviation and space travel sector. Among other things, an office in Toulouse was opened in 2017.
Located in the Motor City, the heart of the American automotive industry, FEV North America has been a driving force for technical innovation in the mobility industry for more than 30 years.
Employing more than 450 experts at three technical facilities in Auburn Hills, MI and an office in Silicon Valley (California), FEV is partnering with OEMs and Tiered suppliers to create intelligent and more efficient future mobility solutions. Originally founded in California in 1985, FEV North America moved operations to Michigan in 1997, and in 2016, the thriving electronics industry and customer demands on the West Coast ultimately brought FEV back to its roots, and let it open an additional office in Silicon Valley.
The FEV North America campus is now even further expanding to include an all-new Vehicle Test Center, strengthening our vehicle development capabilities. Slated to open at the end of 2018, FEV North America will become a complete, one-stop shop for powertrain and vehicle development, and position FEV as the preferred supplier to offer these capabilities.
The new facility will house a state-of-the-art vehicle emissions chassis dynamometer, with high-precision exhaust emissions measurement technology, and an advanced vehicle lab with a low-temperature condition hall. This will complement the 26 already existing powertrain test benches and 6 engine and component test benches, all capable of testing electrified powertrains, engines and axles.
Automated driving and connectivity have become the next big focus for the mobility industry, and the required hardware and software advancements will bring an increasingly diversified development process for OEMs and service providers. To meet these challenges, FEV developed a global Center of Excellence (CoE) in 2017, which focuses on connectivity and smart vehicle development. This is not limited to autonomous driving functions, but also includes infotainment and telematics systems, cybersecurity and V2X communication.
The CoE is built on a connected system thinking approach, a practice that takes the entire ecosystem into consideration during each stage of the smart vehicle development. This approach to engineering is critical due to the exponential growth of new functions, providers and development tasks. Connected systems thinking allows for shorter development time despite increasing system complexity and stricter requirements for hardware and software. With the CoE, FEV is building safe and secure Smart Vehicles, free of cyber-attacks.
The automotive industry is undergoing what is likely to be its greatest transformation. Not only is the concept of mobility evolving due to increasing digitalization and urbanization through advances such as car sharing and autonomous driving using various electric assistance systems, but a healthy competition among powertrains is also prevalent due to global accountability for climate protection, particularly in the transport sector. Car manufacturers and suppliers are thus looking for productive advances with a view to CO2-neutral mobility. There is still no consensus on the one right solution, instead, there is growing competition among a wide variety of technologies
Electrification is an important resource in this context, although contrary to popular belief, it is not the only one. Rather, it is important to raise awareness of the fact that it is not enough to replace a conventional combustion engine with an electric powertrain. The future of vehicle powertrains will be characterized by electric combustion engines, such as HEVs and PHEVs, alongside BEV powertrains. The goal is to promote the development of needs-based powertrain solutions instead of copying a single approach.
Combustion engines – like the modern diesel engine – are a key component in this regard. They not only have the highest level of thermal efficiency for powertrains, but also a very long range. It is possible to produce combustion engines with marginal pollutant emissions thanks to increasingly modern technologies,such as the adjustable compression ratio recently implemented in production for gasoline engines, further optimization of turbochargers, and the efficient use of residual heat from exhaust.
From well to wheel, CO2 emissions can be reduced to nearly zero by using e-fuels, i.e. synthetic fuels obtainable from renewable sources. Unfortunately, this type of CO2 reduction has not received political support. A smart way to reduce fuel consumption and emissions is to also electrify conventional powertrains, e.g. using cost-effective 48V systems that also improve mileage and comfort at the same time.
Fuel cells can solve the problem of range for e-vehicles by using a large hydrogen tank.
In addition, by using hydrogen in fuel cells to generate power for electric vehicles the electric surplus from regenerative energies can also be usefully stored. There is still a lack of infrastructure for fuel cell vehicle use to be marketed to the masses, although a large number of hydrogen stations are currently being planned.
The future of powertrains will certainly be dominated by sustainability. It is not productive, however, to ban certain powertrain technologies. Instead, it is crucial to have the right combination. Whether this means electric powertrains, fuel cells, or optimized combustion engines that use e-fuels, it is important to find and support the right, most sensible, and cleanest solution for each application.
Since its creation, FEV has continuously faced the challenges of the time and developed solutions that made powertrains more efficient and mobility safer and more sustainable. Many of these innovations later made it to serial production and are here to stay. That’s reason enough to present a few here.
Three-Way Catalyst – Since the Early 1980s
The three-way catalyst is a technology for gasoline engines that enables an effective purification of the exhaust, and FEV has made significant contributions to its development. The three-way catalyst got its name from its simultaneous transformation of the three pollutant groups – carbon monoxide, hydrocarbons, and nitrogen oxides transform into carbon dioxide, nitrogen, and water. This is made possible through a coating with a washcoat and precious metals, such as palladium and rhodium. While palladium promotes the oxidation process, rhodium reduces nitrogen oxides, and pollutant emissions are reduced by more than 90 percent.
Variable Valve Control – End of the 1980s
The use of variable valve control enables the dosing of the respective quantities of air or fuel mixture present in combustion engines. This, depending on the amount of power needed, optimizes combustion and saves fuel. This opens up completely new possibilities with regard to performance and costs. FEV has successfully developed and implemented many various concepts, from simple hub switching to fully variable mechanical and electro-mechanical valve gears for different displacement categories and cylinder numbers for gasoline and diesel engines.
Diesel Direct Injection – 1995/1996
FEV was significantly involved in the development of piezoelectrically controlled common rail injectors. For instance, two years before the serial introduction of common rail systems (1997), the first directly controlled common rail piezo injectors were developed and used on one-cylinder research engines.
Spray Guided Turbo
The 4-cylinder gasoline engine with turbocharger and direct injection developed by FEV produces 160 kW/90 kW/ l and develops its maximum torque of 320 Nm from 1,800 rpm. The engine is designed for operation with ethanol fuel and has a peak pressure capability of 140 bar. In addition to a combustion process specifically designed for enthanol, modifications to the inlet valve, seat ring, ignition system and crankcase breather are major adjustments made to the engine. The engine can be started at -10 ° C without additional cold-starting aids.
Diesel Particle Filter – Presented in 1999
FEV developed and patented the world’s first serially produced Diesel Particulate Filter (DPF) together with Peugeot. The DPF is capable of reducing 99 percent of particle emissions. FEV not only impressively demonstrated the development potential of combustion engines, at the same time, it was able to raise general awareness of exhaust purification. Particulate filters are now used in all passenger cars and utility vehicles and have been constantly improved with regard to size and efficiency over the past 20 years. Initially designed for diesel engines, they are now also used in gasoline engines as gasoline particulate filters.
Two-Level VCR Connecting Rod – Since 2002
The Variable Compression Ratio (VCR) technology in gasoline and diesel engines meets the challenges of future emissions legislation through the expanded operating ranges facilitated by the ability to optimally adjust the compression ratio at any time. This approach considerably reduces CO2 emissions and significantly mitigates exhaust emissions in real operation.
Its efficient design makes it possible to use this system in compact powertrains of the future without having to significantly modify the basic engine.
7- to 10-Speed Dual-Clutch Transmission FEV xDCT
With the extremely compact xDCT transmission range, FEV encountered available 7-speed dual-clutch transmissions pushing the limits with regard to size, weight, and costs. These power-shifting, compact solutions from FEV enable more speeds with the same or an even lower complexity of the transmission, which translates into cost-effective production costs. The short first speeds along with a small 1-2 speed step also enable the provision of a very comfortable start-up and creep behavior.
To counter the fears regarding range for electrically powered vehicles, FEV, as part of the joint project “BREEZE!”, has integrated a fuel cell range extender into an already-existing battery-powered vehicle belonging to the subcompact category (Fiat 500). In view of the limited installation space, this was a particular challenge.
The maximum speed of the vehicle is 120 km/h and is independent of the state of charge of the battery. Due to installation space, the range of the battery is 80 km and the additional range of approx.
200 km provided by the fuel cell module is limited by the hydrogen tank. Hydrogen refueling can be done within a few minutes.
48 V Electrical Charging
One example of powertrain electrification, suitable for series production, is the AMG A45 concept vehicle: FEV engineers have integrated a belt-driven starter generator and an E-Charger into the powertrain. Both are connected with a specially developed 48V Li-ion battery, while a hybrid control unit regulates the energy flows. At low speeds and highly dynamic load changes, the electrically operated E-Charger and BSG support the twin scroll turbocharger, which is designed for maximum performance. This means that the maximum torque is available much earlier than in the standard version. The result: elasticity and response of the already very sporty AMG A45 increase noticeably and the number of gears shifts can be minimized with simultaneous reduction of fuel consumption.
Smart Vehicle Engineering
Since 2016, FEV has been bundling all of the steps associated with advanced, fully networked, automated vehicles in its “Smart Vehicle” Center of Excellence. Smart Vehicles include a number of development fields in a rapidly progressing, highly complex environment – from sensor technologies to software algorithms all the way to electrical/electronic architectures and connectivity. In this context, FEV develops innovative solutions for advanced driver assistance systems (ADAS), autonomous driving, connectivity, cyber security, infotainment, and driver-vehicle interaction.
…with the founder of FEV, Professor Franz Pischinger, and the chairman of the board and managing partner of FEV Group, Professor Stefan Pischinger.
FEV – A Real Success Story. What was your vision when you founded the company?
Prof. Franz Pischinger: My vision was to carry engine development research results from theory to practice. I knew that combustion engines had a lot of potential and the demand from the automotive industry for more efficient engines with lower pollutant emissions was very high, even forty years ago. We had the knowledge to drive developments and create solutions for mobility.
FEV was founded by four committed colleagues, including yourself. What were the biggest challenges in the beginning?
Prof. Franz Pischinger: The beginning of any start-up, as our project at the time would probably be called now, presents challenges that are similar, by and large. We had made a name for ourselves with the research results at the RWTH, but of course we had to first convince customers that our developments offered real added value in practice. Fortunately, we managed to do this very quickly.
With increasing development orders and a growing number of employees, we were also confronted with very mundane challenges: our office space on Augustinergasse gradually became too small and we urgently needed to increase our number of test benches in order to be capable of testing the research results.
Your son, Professor Stefan Pischinger, now occupies your former position as Chairman of the Board of FEV – and has done so for almost 15 years. Do you drop by the Neuenhofstraße every now and then?
Prof. Franz Pischinger: Absolutely, but not to monitor the employees – merely to observe. The development of the company shows that excellent work is being done.
I am extremely interested in seeing which projects are currently being worked on and what this vibrant company is planning next.
On the subject of planning and since its creation, FEV has grown continuously. This can also be seen in the building expansion of the headquarters on Neuenhofstraße since you moved there in 1990. Is an end to the expansion planned?
Prof. Stefan Pischinger: Certainly not. Our customers appreciate the local proximity and the capacities that we can offer regionally. As an internationally active company, we now have more than forty locations worldwide. We are expanding continuously – on the one hand through opening new locations, and on the other hand through the expansion of existing test centers – for example, Auburn Hills (USA) or in our durability test center in Brehna (Germany), where we are currently expanding our offering with seven test benches designed strictly for e-drives. This naturally also increases our number of specialists, who are ultimately the drivers of our success.
What are the key drivers of this growth and how does FEV deal with them?
Prof. Stefan Pischinger: The demand for development services from OEMs and Tier 1 suppliers has been increasing steadily, along with the complexity of the development tasks, and is therefore a key reason for the growth we have experienced during the past few decades. To meet this demand, FEV strategically realigned itself by establishing a Group GmbH in 2014. To better address the volume of international customer inquiries, our central business units have been given more responsibility for their operations. At the same time, these structures allow FEV to manage its international resources more efficiently, while the business units can focus more than ever on their respective operational areas of responsibility. Customer feedback shows that this was the right step.
What are the most important trends and topics that will shape the automotive industry of tomorrow?
Prof. Stefan Pischinger: The core topics have been the same for years; the two most important that should be mentioned here are fuel consumption and emissions, both in the context of the powertrain and the overall vehicle. Naturally, e-mobility is also an essential topic. In the meantime, however, there is increasing consensus that the future will not exclusively belong to electric vehicles. Although they will certainly play an important role, they will share the market with hybrid vehicles. The cost efficiency of hybridization and 48-volt technology is a significant topic, as is the continuous improvement of diesel and gasoline engines.
One of the key tasks of the powertrain will be the reduction of fuel consumption and pollutant emissions. There are also classic topics, such as aerodynamics, exhaust heat recovery, and onboard network optimization that must be considered. The Car2Infrastructure / Car2Car communication and connection, as well as autonomous driving, must also be taken into account as influential factors for efficient mobility concepts.
How can diesel and gasoline engines combustion engines still be optimized?
Prof. Stefan Pischinger: In the development of the passenger car Diesel engine, once the nitrogen oxide issue is resolved, we will still see a much stronger focus on increased fuel efficiency in the future, both on the conventional side with improved mechanics and optimized thermodynamics, as well as in connection with electrical support systems. The modular design of the future engine generation will enable a targeted configuration of the powertrain for the respective application. Thus, modern Diesel engines will remain an essential element in the drive system portfolio for heavy vehicle categories or applications with high driving power over the next few decades.
Friction reduction is an important powertrain subject and will remain a big trend. Developments in roller bearings will contribute to reducing friction significantly, as we are already seeing this in the case of turbo chargers. In the future, camshafts and balance shafts will also be optimized to this end, and this is also possible for crankshafts. Beyond that, innovations will continue to reduce CO2 emissions. The variable compression ratio will play a role in some applications. For this, FEV has developed a simple solution with a two-level connecting rod.
The use of e-fuels in the powertrains can also have a significant impact and lead to the further reduction of CO2 emissions for combustion engines.
FEV is associated with many innovations. Have you become especially proud of a specific development in recent decades and, if so, why that one?
Prof. Franz Pischinger: Spontaneously, I would say the Diesel particle filter that we developed together with Peugeot. Ultimately, it contributed significantly to establishing the excellent reputation that compression ignition systems in the passenger car segment now enjoy.
40 years of FEV – we also have to look to the future. What do you expect from the coming years?
Prof. Stefan Pischinger: As much as the automotive industry and the understanding of mobility in the context of the digital revolution are changing, that is how much our mobility will change. Electrified drives, autonomous driving and connected vehicles are a few forward-looking topics in this regard.
With its innovations over the past 40 years, FEV has decisively shaped mobility. Our goal is to continue supporting our customers as a reliable partner in the coming decades with the same care and dedication, despite the increasingly complex overall mobility concepts with development cycles that are becoming increasingly shorter at the same time.
The success story of FEV began four decades ago, as an extension of the Rheinisch-Westfälische Technische Hochschule (RWTH) in Aachen, Germany. Since 1970, Professor Franz Pischinger had been the owner of the Institute for Applied Thermodynamics at the RWTH where he researched methods for cleaner, more economical, and quieter Diesel and gasoline engines. Soon, the Institute developed into a think tank for more efficient combustion engines, and Pischinger came up with the vision of carrying the ideas from research and development into business.
However, many challenges had to be won before the “Forschungsgesellschaft für Energietechnik und Verbrennungsmotoren” (FEV) company was founded. After all, the prevailing opinion at the time was that universities and businesses should be strictly separate from each other. Today, in contrast, that is long gone and application-oriented research and market supply has established itself as the Aachen model for success. Even at that time, FEV was described as a forerunner and a pioneer – long before the company’s first groundbreaking innovations.
The advantages of the close collaboration between FEV and RWTH were obvious. FEV was able enrich the teaching and engineer training at the university through a very strong practical exchange, and RWTH developed into a talent factory for drive development and expanded its first-class reputation. FEV, in turn, could attract graduates through its research orientation. Aachen also hugely benefited as an economic center from the synergy of education and business.
The initial doubts of a few skeptics who claimed the academic work of Professor Pischinger would suffer from his business commitments were laid to rest. Until his departure from the Institute in 1997, Professor Franz Pischinger shared his knowledge with nearly 9,000 students and supervised the research work of more than 200 engineers as they obtained their doctorates. During his 26 years at the RWTH as Dean and Proctor, and in addition to his insightful lecturers, he connected the RWTH with leading global technological institutions for the purpose of efficient, expertise-bundling research.
As the recipient of significant awards, such as the Aachener Ingenieurpreis, and his induction into German Research Hall of Fame, Professor Franz Pischinger is living proof that education and business inspire and drive each other. This model was also followed by his son, Professor Stefan Pischinger, who took over the Institute for Thermodynamics at the RWTH from his father in 1997 and serving as Chairman of the FEV Board since 2003, is in charge of leading FEV toward cleaner and sustainable mobility.
The FEV Group headquarters are located in the geographical heart of Europe. Founded in 1978 in the imperial city of Aachen, FEV is one of today’s leading engineering service providers. Started by Professor Franz Pischinger and three employees in a small rented apartment near the university, it was at this time that people had access to 20 test benches at the Institute of Applied Thermodynamics and RWTH Aachen from which FEV emerged as a complementary company. In the 1980s – operating then from Jülicher Straße – the number of inspection opportunities operated in-house had been rising steadily and by 1990, it was necessary to expand office and test bench capacities within Aachen as a result of a need for more inspection and development capacities. The company premises on Neuenhofstraße are still being used today and offer sufficient space to meet customer requirements in the future.
After 28 years and numerous stages of expansion in the testing environment, including the addition of state-of-the-art testing equipment, FEV has now also invested in a significant expansion of office space in order to meet the continuously growing number of engineers. The number of FEV’s own engine test benches in Aachen is now 27, with 28 additional engine test benches that can be rented from RWTH. FEV also has two turbo and various transmission, friction, burner, and chassis dynamometers on site. And, this is ever-increasing.
A stone’s throw from Aachen, in Alsdorf, lies a developmental focus for FEV in terms of electrified drive units, battery development and ADAS systems for autonomous driving. It is also home to an FEV transmission development center. Currently, around 2,000 employees work in Aachen and Alsdorf.
Also just a short distance from the headquarters is the Aldenhoven Testing Center (ATC), operated by RWTH and the district of Düren. For customers in the immediate vicinity, FEV can rent an extensive and ideally complementary test offering to develop and test both powertrain and vehicle technology.
The ATC currently has an oval and dynamic driving area, braking course, course with poor road conditions, handling course and slope hills, as well as the adjacent highway section. The site is expanding into a full-fledged urban setting that offers the best conditions for testing automated and autonomous driving.
Battery electric vehicles (BEVs) will play a major role in achieving future vehicle fleet targets for emissions such as CO2, NOx, and particulate matter. Especially in big cities, these vehicles may contribute significantly to keeping the air clean. Hybrid electric vehicles (HEVs) will also do their part in major cities, provided drivers charge their batteries via the power grid and not using the internal combustion engine. FEV has already developed transmissions for passenger cars and light commercial vehicles configured as BEVs as well as HEVs.
>> THE PRODUCT DEVELOPER’S TASK IS TO LIMIT THE COMPLEXITY AND THE RISING PRODUCT COSTS ASSOCIATED WITH IT TO AN ABSOLUTE MINIMUM
Transmissions for battery electric vehicles are becoming more complex as the demands placed on them increase. The maximum driving speed attainable using the battery is rising continuously while demands on starting performance remain constant. These conflicting goals can be solved using high-speed electric engines or two-speed transmissions, but experience shows that such transmissions need to be power-shifting. Besides recuperation, there is a new requirement to have a neutral feature for disconnecting the electric engine from the drive wheels. Particularly at high revolutions and with P4 hybrids, the drag torque of perpetually energized electric engines has a noticeably negative effect. In other applications, the parking lock switches from the transmission to the vehicle braking system. Highly demanding vehicle installation spaces require coaxial construction of the electric drive. The product developer’s task is to limit this complexity and the rising product costs associated with it to an absolute minimum. It helps significantly to adopt subsystems from transmissions used in conventional powertrains. FEV takes this approach.
In addition to the one-speed transmissions already in production for BEVs and P4-HEVs, FEV also develops power-shifting, two-speed systems. Figure 1 shows a first-generation drive unit with a continuous output of 70 kW as well as a peak output of 90 kW using a 400-volt battery. The transmission was developed in-house by FEV. Our development partner, YASA, supplied the P400S electric engine, and the inverter was manufactured by SEVCON. Alternatively, the setup can make use of FEV’s own electric engine and inverter. The component that limits the torque is the mass-produced dry dual clutch. The corresponding electromechanical actuator also comes from mass-produced dual clutch transmissions for the powertrains of purely internal combustion engines. Using these commercially available subsystems makes development short and efficient, enabling market launch to take place quickly. The rotational speed at which the clutches rupture and their torque capacity, however, limit the applicability to the ranges indicated. The demand for higher driving performance is leading to a new solution, as illustrated in Figure 2. A planetary transmission with a Ravigneaux gear set is used to allow the electric engine to rotate at higher speeds and provide higher torque. These transmissions are quite common, with corresponding production facilities and equipment already available. In connection with this simple, reduced clutch transmission, two brakes are sufficient for generating two speeds. The exclusive use of brakes was an important criterion in selecting a design because, unlike ordinary clutches, they avoid the use of rotary transmission feedthroughs or slave cylinders to engage the gears, making them significantly more economical. Figure 2 also shows the oil pump and heat exchanger, which not only aid the gears but also help cool both the electric engine’s stator and the inverter. The electric engine with a built-in inverter belongs to a new generation of products developed by our partner YASA. The compact axial flow electric engine is also suitable for vehicles that have a narrow track width, such as relatively small construction vehicles and municipal fleets.
>> ON THE WAY TO THE LARGE-SCALE INTRODUCTION OF BATTERY ELECTRIC VEHICLE POWERTRAINS, HYBRID DRIVE SYSTEM TECHNOLOGY IS CRUCIAL TO BRIDGING THE GAP
On the way to the large-scale introduction of battery electric vehicle powertrains, hybrid drive system technology is crucial to bridging the gap. The section below introduces two solutions offered by FEV for transversely mounted engines.
Transmissions for P2 and Combined Hybrids
>> FOR FULL HYBRIDS, A POWER-ON-DEMAND ACTUATOR IS THE MOST IMPORTANT PREREQUISITE FOR OPERATING THE TRANSMISSION INDEPENDENTLY OF THE INTERNAL COMBUSTION ENGINE
The P2 hybrid transmission (parallel hybrid) illustrated in Figure 3 expands FEV’s dual-clutch transmission kit to include variations for input torques of 150, 250, and 350 Nm for the transverse engine. Every transmission uses wet dual clutches and exclusively needs-based actuators. For full hybrids, a power-on-demand actuator is the most important prerequisite for operating the transmission independently of the internal combustion engine. FEV’s experience shows that the P2 hybrid with its numerous functions represents a very good solution. The model shown here, based on the 350-Nm version of our dual-clutch transmission kit, also makes use of transmission subcomponents readily available on the market. The electric engine being used delivers 50 kW of continuous power, plus 100 kW for a maximum duration of 30 seconds. The length of the transmission, extremely important for a transverse engine, is 440 mm. For a six-speed version, the length can be reduced to 415 mm. Six speeds are sufficient for most vehicles because the torque of the electric engine is essentially available from a standstill, enabling selected gear ratios to be higher. However, even a six-speed version is not a solution for vehicles with extremely tight installation space. That is why FEV has devised another concept that combines the advantages of a P2.5 and a P3 hybrid. These types of hybrids have an electric engine mounted parallel to the electric engine, a big advantage for the package (Fig. 4). With a P2.5 hybrid, the electric engine is coupled with one of the dual-clutch subtransmissions, but it has the disadvantage that the rotor’s inertia needs to be synced up by the gear synchronizers during shifting. The electric engine must be actively synchronized each time the corresponding subtransmission shifts gears. To avoid that, on this kind of hybrid, the electric engine can be disconnected from the subtransmission and connected to the transmission output as a P3 hybrid. This takes place by way of an additional gear shaft with a shifting mechanism. Compared to the P2 hybrid, this combined P2.5/P3 hybrid, with total torque of 350 Nm, is 50 mm shorter that a six-speed, P2 hybrid.
Shared mobility and its influence on the automotive industry