Schaeffler all charged up on full spectrum drivetrain electrification

Against a backdrop of increasingly stringent statutory emissions targets and the increasing demand for mobility throughout the world, every road is leading towards drivetrain electrification. Whether for private or commercial use, it is just not possible to imagine the global vehicle fleet in the context of emissions reductions without an increase in hybrid and electric vehicles.

Prof. Dr. Peter Gutzmer, deputy CEO and Chief Technology Officer at Schaeffler, is convinced this will happen: "Look into the not-too-distant future and it is possible to imagine that by 2020, 20% of all vehicles will have some form of electrification. Assuming 120 million vehicles will be produced in 2030, we can envisage a good 10 million of them being fully electric. That represents 9% of the total vehicle market."

The need for drivetrain electrification solutions is also increasing in North America and Schaeffler offers a full range of technologies to meet this demand. With its expertise and experience in electric mobility as well as its broad product portfolio, the company says it is the perfect partner for the challenges presented by the mobility of tomorrow. Whether hybrid modules, the electric axle, or wheel hub drives, Schaeffler says its products can be integrated into hybrid or fully electric vehicles, including 48V and high-voltage variations.

New solutions for drivetrain electrification
The P2 high-voltage hybrid module from Schaeffler is an exciting approach to drivetrain electrification that can be matched to a large number of drive concepts on a modular basis. This P2 hybrid module consists of an automated disconnect clutch and an electric machine. The disconnect clutch is actuated by means of an electromechanical central release mechanism that actuates the clutch mechanically via a ball screw drive without the need for a hydraulic transmission line. This means that, apart from the module itself, no extra space is required for the actuator technology. A one-way clutch is used to transmit the traction torques from the engine to the transmission, while torques are transmitted towards the engine via the clutch. This allows the clutch to have a compact design despite the high torques, with the corresponding benefits in terms of space utilization and cost.

Due to its high variability and its broad torque range of up to 800 Nm, the P2 hybrid module can be used in both 48V architectures and very high performance high-voltage drive concepts. It therefore makes a significant contribution to reductions in consumption and emissions in hybrid vehicles. In a further exciting development, a damper has been added in front of the electric machine in the hybrid module. If the mechanical damper reaches its limits in terms of vibration while operating at demanding speeds, the electric motor takes over and the active damping ensures that acoustic demands are met. This new hybrid module will be put into volume production for the first time at the start of 2017.

Schaeffler has developed a variation on the P2 hybrid module for the American market with an integrated torque converter. In this instance, the mobility supplier is combining its core expertise in torque converters with hybrid modules, resulting in further improvements in space utilization. This high-voltage solution is expected to be in use in a North American light-duty truck by 2020.

Further technologies for hybrid and fully electric vehicles
The electric axle: Schaeffler's electric axle provides a solution for both hybrid and fully electric vehicles. Schaeffler has developed a modular range of components based on customers’ requirements and their various preferences in terms of the target vehicle's driving characteristics. The company's most structurally straightforward solution is the electric axle with single-speed ratio in a coaxial or parallel axis design. These transmissions are extremely compact due to the planetary design of the differential (combination of single or two-stage planetary gear sets) and provide a great deal of space for the electric machine, which can be designed as either a permanently excited synchronous machine (PSM) or an asynchronous motor (ASM) with or without power electronics.

The basic configuration can be extended by adding functional elements. For example, it is possible to integrate the parking lock, which is a necessity on many vehicles. A second gear is often required, particularly in plug-in hybrid vehicles where dynamic, fully electric operation up to 120 km/h is required, as well as a high top speed. The most recent generation of the two-speed axle developed by Schaeffler has a shift actuator. The lateral dynamics can be improved using a torque vectoring element. This function is made possible by adding a suitable transmission and a small electric machine in the region of 7 kW.

The wheel hub drive: Fully electric driving means CO2-free mobility. Schaeffler’s E-Wheel Drive electric wheel hub drive is an innovative technical solution for tomorrow’s mobility. In this highly integrated wheel hub drive, all components required for drive, deceleration, and driving safety – such as the electric motor, power electronics, controller, brake, and cooling system – are contained within the wheel rim. As part of the test program, a development vehicle based on a Ford Fiesta was created in a collaborative project with Ford Motor Co., where the technology is currently achieving up to 40 kW per drive or a continuous power of 2 x 33 kW. In traditional terms, this means 110 horsepower.

In addition to optimum use of space, highly integrated wheel hub drives also offer significant benefits in terms of maneuverability, driving dynamics, and active safety.

“This can have a significant role to play in the future, particularly when combined with autonomous driving,” explains Schaeffler CTO Prof. Dr. Gutzmer. “The electric wheel hub drive could become the drive of the future and an invaluable addition to the drivetrain.”

Betting big on 48V on-board electric system
While the current range of hybrid vehicles operate at over 300 volts, Schaeffler is putting its trust in a 48V on-board electric system in order to produce electric driving at low speeds.

“This means, on the one hand, the driver makes considerable savings on fuel while, on the other, benefiting from a more enjoyable driving experience at only slightly greater expense,” explains Prof. Dr. Gutzmer, the mobility supplier’s CTO.

Schaeffler is testing and demonstrating the performance capabilities of 48V hybridization in a range of concept vehicles. The “Gasoline Technology Car” (GTC), co-developed with Ford and Continental, uses a 48V architecture like that of the “Schaeffler Efficient Future Mobility North America” vehicle that was launched at the 2015 North American International Auto Show (NAIAS). This vehicle demonstrates how the company is already meeting the 2025 statutory consumption requirements in the form of a mid-range SUV.
Currently Schaeffler has developed a transmission driven accessory drive (TDA). Essentially, the TDA module is a parallel hybrid system which incorporates a selectable power flow between the transmission and the 48 V MGU equipped accessory chain. The conventional belt drive can be eliminated, the TDA is linked to the powertrain in front of the transmission (P2- position), and operation of the accessories and energy recovery are possible independent from the combustion engine. Further innovative functionalities like boosting or electric supported sailing are possible. The TDA system enables significant CO2- savings as well as new packaging possibilities.

Another technology standard bearer for the supplier is the ’Schaeffler System 48V’ concept vehicle, based on an Audi TT. The drive is based around an electrified rear axle that complements the front-wheel drive engine. An additional belt-driven starter generator is connected to the engine, which also operates at 48V. The 48V on-board electric subsystem uses a lithium-ion battery as its energy store. It is connected via a voltage transformer to the 12V on-board electric system, which powers the various electrical components in the vehicle, such as headlamps and seat adjusters.

“With the 48V concept car, we wanted to show that it is possible to produce a noticeable improvement in consumption despite the very low voltage compared to standard hybrid vehicles,” says Uwe Wagner, Vice President Research and Development Automotive at Schaeffler. “In the future, other electromechanical systems in Schaeffler's development or volume production plans will also benefit from the 48V technology.”

The electromechanical active roll control from Schaeffler, which represents a new phase in chassis technology, demonstrates this well. This innovative system replaces the hydraulically controlled anti-roll bars in current general use, helping to reduce fuel consumption and emissions and making vehicle assembly more straightforward. The electromechanical active roll control is initially being used in a luxury limousine and a top-end SUV. The latter is also running a 48V system.