OEM&Lieferant Ausgabe 1/2018

96 Due to increasingly stringent emissions regu- lations and current trends like autonomous driving and e-mobility, the number of new mobility concepts such as hybrid electric vehicles (HEV) and electric vehicles (EV) is set to grow rapidly. There are different hybrid architectures available for electric motors. Amongst them, the so-called P2 arrangement, in which the electric motor is placed between the internal combustion en- gine (ICE) and the transmission, is currently receiving a great deal of attention. With their innovative on- and off-axis P 2 hybrid modules (Figure 1), BorgWarner supports automakers around the globe in mastering the challenges lying ahead. A choice of architectures In P 2 arrangements, two architectures are feasible. When an on-axis configuration is used, the motor is located directly on the main axis. The off-axis design, on the other hand, places the motor parallel to the main axis, ideally with a chain handling torque and speed transmission between the two compo- nents (Figure 2). Easy Hybridization with BorgWarner P2 Modules By Eckart Gold, Senior Manager Advanced Engineering, BorgWarner Transmission Systems To pave the way for simple and cost-effective hybridization, BorgWarner has developed on- and off-axis modules for P2-type hybrid vehicles. Delivering hybrid functionalities such as stop/start, regenerative braking, boosting and pure electric driving, they are designed for easy integration into existing drivetrain architectures. Future Technologies Images/Graphics: © BorgWarner This difference in motor placement means that the main distinction between the two config- urations is the packaging space. The on-axis arrangement is well-suited for all longitudinal drivetrains, whose axial space is not very constrained, as well as for dual-clutch transmission (DCT) ap- plications. Conversely, the off-axis arrange- ment is the prime choice for transversely po- sitioned internal combustion engines, where axial built-in space is typically extremely lim- ited. While the electric machine doesn’t need supplementary torque transfer hardware or additional space adjacent to the transmis- sion in the on-axis arrangement, the off-axis solution provides benefits such as an appli- cable gear ratio or the potential for further chain-driven assembly integration as well as high positional flexibility. Electric motor concepts A key component allowing different module setups is the electric motor. Packaging, oper- ating level, cooling system and winding type must be taken into consideration here. In an off-axis solution, an electric machine with a smaller diameter and a higher speed can be installed alongside the engine more easily. The on-axis configuration, on the other hand, facilitates using a larger e-mo- tor with lower speed and higher torque gen- eration. Meanwhile, a low-voltage system offers a cost-effective solution for good CO2 reduc- tions, whereas a high-voltage solution can provide a power output of over 100 kW for substantial fuel economy improvements by allowing the vehicle to operate in full electric mode (Figure 3). Figure 1: BorgWarner’s P2 modules offer hybrid functionalities such as pure electric driving while increasing fuel efficiency and performance. Figure 2: Electric motor placement in the two configurations: on-axis (left) and off-axis (right).