There is a lot of news coming from Audi: not only have they introduced recently the new Q2 and A5 range, of which we will soon tell you more, but they a also coming up with very interesting technologies. This time, they focused on the suspension front. Indeed, everybody knows that a lot of kinetic energy is being lost by the suspension of a car. So it was written in the stars that someone would come with a new technology to convert this into electric energy…
Hans Knol ten Bensel
The Audi engineers developed a new electromechanical damper system for the rear wheels, coupled to a 48-volt electrical system. They dubbed it the eROT, and it responds quickly and with minimal inertia.
Ideally suited to every road…
As an actively controlled suspension, it adapts ideally to irregularities in the road surface and the driver’s driving style. A damper characteristic that is virtually freely definable via software opens new possibilities. It eliminates for instance the mutual dependence of the rebound and compression strokes that is inherent to conventional hydraulic dampers.
With eROT, Audi configures the compression stroke to be comfortably soft without compromising the taut damping of the rebound stroke. Another advantage of the new damper system is its geometry. The horizontally arranged electric motors in the rear axle area replace the upright telescopic shock absorbers, which allows for additional space in the luggage compartment.
Here one sees a prototype, being set up and measured on the test bench…
… And producing e-power…
The eROT system enables a second function besides the freely programmable damper characteristic: It can convert the kinetic energy during compression and rebound into electricity.
To do this, a lever arm absorbs the motion of the wheel carrier. The lever arm transmits this force via a series of gears to an electric motor, which converts it into electricity.
The recuperation output is 100 to 150 watts on average during testing on German roads – from 3 watts on a freshly paved freeway to 613 watts on a rough secondary road. Under customer driving conditions, this corresponds to a CO2 savings of up to three grams per kilometer (4.8 g/mi).
The new eROT technology is based on a high-output 48-volt electrical system.
In the current configuration, its lithium-ion battery offers an energy capacity of 0.5 kilowatt hours and peak output of 13 kilowatts. A DC converter connects the 48-volt electrical subsystem to the 12-volt primary electrical system, which includes a high-efficiency, enhanced output generator.
Initial test results for the eROT technology are promising, and its use in future Audi production models is plausible, as the manufacturer states.
A technical prerequisite for this is the 48-volt electrical system, which is a central component of Audi’s electrification strategy.
In the next version planned for 2017, the 48-volt system will serve as the primary electrical system in a new Audi model and feed a high-performance mild hybrid drive. It will offer potential fuel savings of up to 0.7 liters per 100 kilometers.
Again an important step towards more mobile efficiency, and interesting enough to merit our attention. Stay tuned for more high-tech news!
Hans Knol ten Bensel