At present, the eROT setup is only available for the rear wheels. The prototype system ditches the usual upright shock absorbers in favour of a lever arm connected to a series of gears and a compact horizontal electric motor.
Stefan Knirsch, head of technical development at Audi, sums up the premise of the system: "Every pothole, every bump, every curve induces kinetic energy in the car. Today’s dampers absorb this energy, which is lost in the form of heat. With the new electromechanical damper system in the 48-volt electrical system, we put this energy to use."
To do this, the eROT's two electric motors convert the kinetic energy from both the compression and rebound stages into electricity that's stored in a lithium-ion battery pack that's a part of a 48V electrical system.
Audi says that during testing on German roads, the eROT system recuperates on average between 100 to 150 watts. The amount varies wildly depending on the type of road, with freshly paved autobahns generating just three watts, while a rougher secondary road produces up to 613W.
The luxury marque claims that "under customer driving conditions", the current eROT setup would see CO2 output reduced by up to three grams per kilometre. It's not clear if this figure is meant for diesel or petrol engined cars.
In a diesel vehicle, 3g/km would translate to a fuel saving of 0.11L/100km, while in a petrol car that would be a saving of 0.13L/100km.
According to Audi, the actively controlled eROT system also "eliminates the mutual dependence of the rebound and compression strokes", which forces today's engineers into compromising ride for handling, or vice versa.
The company says that "initial test results for the eROT technology are promising", and that inclusion in a production model "is certainly plausible", although it doesn't speculate about when this might happen.
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