Compact design is suitable for compact passenger cars

Compact design is suitable for compact passenger cars

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Soon after announcing a second huge order for eight-speed automatics plus a 'hybridised' eight-speed automatic for 2022, ZF has launched an electric two speed drive for passenger cars.

This integrates an electric motor with a shift element and power electronics.

ZF said the improvement in energy conversion efficiency compared to previous e-drives extends the driving range for each battery charge while compact design is suitable for compact passenger cars.

The modular design can tuned and scaled up for sports and performance vehicles.

"For electric vehicles in everyday use, it is important to obtain as much range as possible from each battery charge", said Bert Hellwig at ZF's E-Mobility division.

"Every percent of improvement in energy conversion efficiency translates into 2% more range."

To increase the performance rating, ZF used its expertise in systems to develop a new electric motor with a maximum power rating of 140kW paired with a two-stage shift element.

ZF claims vehicles with the new drive consume less energy which extends range by up to 5% when compared to a one-speed unit.

Shifts take place at 70km/h (about 40mph). By connecting to the vehicle's CAN communication it is also possible to devise other shift strategies, possibly linked to digital map material and GPS.

The vehicle could identify from the GPS route programming how far it is to the next charging station, enabling it to respond predictively by switching into Eco-mode. More effective shifts would also be possible in accounting for topography on motorways and on inter-city journeys. The software in the drive can also be updated by a network link to cloud services via over the air updates.

The new drive offers automakers two options for using improved energy conversion efficiency. An OEM could go either for an extended range while retaining the same size of accumulator or use a smaller one.

Modular approach

The design optimises installation space so the two speed system is suitable for compact passenger cars where interior space is at a premium.

It also offers benefits for OEMs who are pursuing performance.

"Until now, with electric motors, vehicle manufacturers have had to choose between high initial torque and a high top speed", said Hellwig.

"We are now resolving this conflict and the new drive will be compatible for performance and heavier vehicles – for example for passenger cars towing a trailer."

ZF's modular approach combines the gearbox with more powerful electric motors rated for up to 250 kW. This provides faster acceleration and, potentially, faster top speeds. With its modular concept, the new drive can meet a variety of requirements, the Tier One supplier said.