Most people think cars with features like the ones described above are good, but also very expensive. Not if a system like the eAMT goes into volume production in the future. eAMT is short for electrified Automated Manual Transmission and that is exactly what it is. Recently, ZF introduced a prototype vehicle equipped with the eAMT to customers and journalists: “It demonstrates that a full-featured plug-in hybrid drive along with comfortable automated gear shifting can be installed relatively easily in inexpensive vehicles,” explains Norman Schmidt-Winkel. “In addition, eAMT increases flexibility for vehicle manufacturers. It can be installed in existing front-transverse platforms and in both conventional and electrified drives,” adds Schmidt-Winkel, a function developer in Electric Traction Drive Business Unit at ZF, as he lists further advantages.
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Working Together in Harmony
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ZF’s new eAMT axle hybrid concept features an electric motor and an automated manual transmission that work in perfect harmony with the combustion engine. Those who have driven the eAMT test vehicle are impressed by the benefits of this tandem drive.
Intelligently combined drive technologies
Intelligently combined drive technologies
ZF engineers developed the eAMT by combining the internally developed electric axle drive with the automated manual transmission (AMT). In the automated manual transmission, the electronically controlled actuators handle clutch actuation and shifting for the driver. This kind of solution is ideal for vehicle classes that are not considered suitable for converter transmissions due to weight, installation space or for cost reasons. "Another benefit of the eAMT system is that major modifications are not necessary either for existing automated transmissions or for existing front-transverse combustion engines", explains Dr. Florian Mühlfeld, of systems development group manager at ZF. In the compact SUV, which was selected as the test vehicle, engineers aligned both drives and the automated manual transmissions with one another.
The basic concept of eAMT: The electric axle drive is mounted on the rear axle and the AMT actuators on the transmission. This new eAMT concept does not affect the existing combustion engine (yellow). ZF software manages the interaction between the systems.
Driving comfort just like the “big guys”
Driving comfort just like the “big guys”
The electric motor solves a typical problem in automated manual transmissions very elegantly: It bridges the unavoidable thrust interruptions that occur in the AMT when shifting gears and ensures strong and smooth acceleration. “To install a powerful electric motor that delivers the desired thrust in the shifting pauses for that reason alone would be too expensive,” says Mühlfeld and adds: “With the eAMT, we have now developed a hybrid drive with all the functionalities, including all-wheel drive and purely electric driving. At the same time, we are achieving a level of comfort and performance when shifting that is on par with that of converter or dual clutch transmissions.”
To date, more than 300 people have test-driven the compact SUV prototype vehicle equipped with the eAMT. The vehicle itself is based on a volume-produced vehicle for the Indian market. The feedback from these drivers was very similar: “From shifting comfort and acceleration to the unnoticeable transition between combustion engine and electric motor, everyone said after their test drives that the eAMT exceeded their expectations,” adds Mühlfeld with a smile in response to the general consensus. However, development is not yet completed. The team is working on additional features.
Today, the eAMT features
Today, the eAMT features
- Electric driving
Only the electric motor (eVD) is in operation. - Traction Torque Support
The combustion engine is the primary drive. When shifting, the electric motor intervenes with thrust. - Intelligent all-wheel drive
If needed, the electric drive becomes active instantly to support the combustion engine-powered front-wheel drive. - Boosting
The electric engine provides support if additional power is needed, when overtaking, for example. - Sailing
Combustion engine and electric motor do not deliver thrust in this mode. The vehicle glides with little energy consumption. - Recuperation
Power regeneration: When braking, the electric motor functions like a generator and charges the battery. - Automated shifting
Electronically controlled actuators assume transmission and clutch actuation for the driver. - Creep mode
When traffic is moving slow and there is frequent stop and start, the electric motor takes over and the combustion engine switches off.
ZF