Smart Hybridization with a 48 V Low-Voltage System

48 V System - Schaeffler Presents Components for Modular Hybrid Systems with 48 Volts

Smart Hybridization with a 48 V Low-Voltage System

Schaeffler has a wide range of ideas for future vehicles equipped with a high-performance 48-volt on-board electric system, and these are bundled together in the company's transparent vehicle trade show exhibit with technical solutions for 48-volt electrification.

The central element is a compact 48-volt electric drive module that includes a clutch and planetary transmission, and can be placed either on the front or rear axle. This drive module paves the way for economical hybridization. The low-voltage design of the solution reduces the cost and outlay compared to high-voltage solutions with their associated requirements. Even so, this economical hybridization allows significant advances to be made in terms of drive efficiency, as the use of a 48-volt electric system opens up operational possibilities that were previously the exclusive domain of vehicles with high-voltage hybrid components: These include so-called crawling in traffic jams - electrically powered driving in dense inner-city traffic, i.e. moving off, driving at low speeds, and parking using electric power. in addition to electric boosting during starting and so-called electric sailing - a driving mode in which the electric motor ensures constant speed while the internal combustion engine is switched off - and energy recuperation, i.e. the recovery and storage of energy during deceleration, which is very important in terms of fuel consumption.

The electric drive, which has an output of up to twelve kilowatts, acts as the hybrid vehicle s sole source of power when crawling , i.e. in stop-and-go traffic. The electrically generated propulsion of Schaeffler s 48-volt drive module is also sufficient for driving in residential areas, parking garages, and other low-speed driving situations. This is also true of the comfortable driving mode known as sailing , in which the electric motor ensures virtually constant speed across a wide operating range while the internal combustion engine is switched off. The electric drive assists the internal combustion engine by providing additional torque, e.g. when moving off from the traffic lights; this is referred to as boosting . The high performance of the 48-volt system also means that the drive element opens up new potential for energy recovery. Due to the higher recuperation capability, the kinetic energy released during deceleration is now no longer converted into heat that subsequently dissipates - as was previously the norm - but is instead fed back into the on-board electric system in the form of electrical energy. Therefore, a hybride solution with combustion engine and 48-volt system proves to be advatageous also when generating electricity through braking energy.

Using a 48-volt solution makes it possible today to achieve outputs of up to twelve kilowatts , summarizes Prof. Peter Gutzmer, CTO at Schaeffler. This entry-level form of hybridization thus already offers the essential advantages of a hybrid vehicle and, at the same time, is an economically attractive, low-cost option that allows CO2 emissions to be reduced by up to 15 percent.

The fact that the drive unit is connected directly to the propshaft in vehicles with rear-wheel drive means that drag losses by the internal combustion engine are prevented. We can thus achieve maximum efficiency and make driving situations possible that were previously only offered by hybrid vehicles with significantly more complex designs , explains Dr. Tomas Smetana, Vice President Product Group Electric Axle Systems at Schaeffler. Our combination of an electric motor and transmission also allows the flow of force to be distributed selectively, drive torques can be superimposed, and even torque vectoring - the variable distribution of torque that serves to increase driving safety - is possible.

In its current configuration, the cylindrical component is 235 mm long with a diameter of 165 mm. Its compact design means that it can easily be integrated into the drive train, so it can be integrated into the architecture of the vehicle without any space having to be sacrificed by the trunk or the fuel tank.

Automobile manufacturers who decide to install a second low-voltage on-board electric system (48 volts in addition to the standard 12-volt system) can also integrate other suitable high-performance innovations into the vehicle. These include high-performance, rapid-reaction actuators for the chassis that allow the ground clearance to be regulated according to the situation during driving, which has a positive effect on the vehicle s aerodynamics and thus on its fuel consumption. In addition to the high performance due to the higher voltage range, the second on-board electric system also offers the advantage of smaller cable cross-sections. This saves weight and facilitates the integration and installation of the cable harnesses in the vehicle.

A range of other functions that push today's standard 12-volt systems to their limit of performance can be practically integrated into the architecture of a 48-volt system. These range from mechanical tensioning elements for 48-volt belt-driven starter generators to a number of electromechanical adjusting elements for the clutch, steering, roll stabilization or self-leveling suspension through to hybrid modules, axle drive solutions, and electromechanical torque vectoring units. We have combined a large number of conceivable products together in this trade show exhibit , explains Prof. Peter Gutzmer. Our aim is to show the wide range of possible solutions and demonstrate Schaeffler's systemic approach.

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