48 Volt Hybrid Technology in Road Tests

2015-09-15 | 000-006-100 DE-EN

SCHAEFFLER AG, FRANKFURT

Innovative concept vehicle from Schaeffler

48 Volt Hybrid Technology in Road Tests

Schaeffler s innovative concept vehicle is pushing the boundaries of 48 volt hybridization. While the current range of hybrid vehicles operates at high voltages of approximately 300 volts, Schaeffler is using a 48 volt on-board electric system in order to produce electric driving at low speeds. This means, on the one hand, the driver makes considerably savings on fuel while benefiting from a more enjoyable driving experience on the other and at only slightly greater expense, explains Prof. Dr. Peter Gutzmer, Chief Technology Officer for the automotive supplier.

Schaeffler is testing and demonstrating the performance capabilities of 48 volt hybridization in a range of concept vehicles. The Gasoline Technology Car (GTC), co-developed with Ford and Continental, using a 48 volt architecture, as does the Schaeffler Efficient Future Mobility North America vehicle, as launched at the 2015 Detroit Motor Show (NAIAS), demonstrate how the company is already meeting the statutory consumption requirements which will be in place in North America in 2025 in the shape of a mid-range SUV. Another technology standard bearer for Schaeffler is the Schaeffler System 48 V concept vehicle, this time based on an Audi TT.

The drive for the Schaeffler System 48 V is based around an electrified rear axle which complements the front-wheel drive internal combustion engine. An additional belt-driven starter generator is connected to the engine which also operates at 48 V. The 48 V on-board electric subsystem uses a lithium-ion battery as its energy store. It is connected via a voltage transformer to the 12 V on-board electric system which powers all the different electrical components in the vehicle, from headlamps to seat adjusters. The way in which the drive elements work together depends on which driving mode the driver has chosen. He can switch between Eco and Sport .

Lower Consumption through Mild Hybridization

In Eco mode, which optimizes fuel consumption, the engine is switched off as often as possible. Driving at lower speeds, in stop/start traffic or when maneuvering into a parking space is all electric. When braking, the electric machines act as a generator and recharge the lithium-ion battery. Active sailing is also possible with the electric rear axle: If, for instance, when driving in town at a constant speed, very little driving power is required, the engine remains switched off and the electric machine takes over. If the engine has to be used, it is quickly and smoothly started by the belt-driven starter generator. Under acceleration, the engine and electric motor work together, increasing the power in the system. Also, when the engine is supported by the electric machine, it can run at operating points which improve fuel consumption. Overall, Schaeffler is anticipating a noticeable reduction in fuel consumption - precise measurements will be made available once the concept vehicle has been fully completed. Selecting the right drive configuration also provides increased driving stability. The electric rear axle can provide all-wheel drive for short periods, for example when setting off on snow or ice.

More Fun when Driving in Sport Mode

The characteristics of the whole drive train change if the driver selects Sport mode. The engine is used all the time. It sends a permanent charge to the battery via the belt-driven starter generator so that sufficient energy is always available to extract maximum performance from the system. In Sport mode, the torque produced by the electric motor is distributed between the two rear wheels via an integral torque vectoring gear stage. This improves vehicle agility considerably when driving round fast corners.

In developing the concept vehicle, the experts in Herzogenaurach work closely with Schaeffler s own in-house development service, Schaeffler Engineering. The software is entered into the PROtroniC prototype control unit which controls and regulates the interaction between the many individual components.

Opportunities for 48 Volt Technology

At the International Motor Show in 2013, Schaeffler demonstrated the opportunities the introduction of a 48 volt on-board electric system provides for economical hybridization. Gutzmer again: With the 48 volt concept car, we wanted to show that it is possible to produce a noticeable improvement in fuel consumption despite the very low voltage compared to standard hybrid vehicles. In the future, other electromechanical systems in Schaeffler's development or volume production plans will also benefit from the 48 volt technology. One example of this is the electromechanical active roll control system which improves driving stability by reducing significant vertical chassis movement when taking corners at speed.

LINK:	http://www.ina.de/content.ina.de/en/press/press-releases/press-details...
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