Audi Electromechanical rotary damper
Audi might not be the leader in electrical vehicles but the company is thinking outside of the box about ways to recover energy from driving. Today, the company announced a new “Electromechanical rotary damper” that would recover energy from vertical bumps in the road and turn that into an admittedly small amount of electricity to be used later.
Dubbed eROT, the system works a little bit like one of those kinetic watches that charges from the movement of the wearers arm. Vertical bumps basically move an arm that connects through a series of gears to a small alternator that generates electricity which is then stored in a very small 500W battery (this is 1/120th the size of Tesla’s smallest battery pack)
How much energy are we talking here? (Keep in mind a typical 3’x5′ rooftop solar panel is around 300W)
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. As currently configured, 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.
So we’re talking a trivial amount of energy for motoring but a nice recovery mechanism for some lost energy and enough to keep the lights on so to speak. It appears that Audi is thinking of using this as a 12V replacement for a car’s alternator which would be a novel use.
Perhaps more notable is that the suspension will be adjustable by the driver and perhaps eventually by computer in the car on the fly. In the future, sensors and cameras could detect road conditions ahead and adjust suspension accordingly.
Every little bit helps?
In the mobility of the future, the recuperation of energy plays an increasingly important role, including in a car’s suspension. Audi is working on a prototype called “eROT,” in which electromechanical rotary dampers replace the hydraulic dampers used today for an even more comfortable ride.
The principle behind eROT is easily explained: “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,” said Dr.-Ing. Stefan Knirsch, Board Member for Technical Development at AUDI AG. “With the new electromechanical damper system in the 48-volt electrical system, we put this energy to use. It also presents us and our customers with entirely new possibilities for adjusting the suspension.”
The eROT system responds quickly and with minimal inertia. 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 increases the functional scope. It eliminates the mutual dependence of the rebound and compression strokes that limits 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.
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. As currently configured, 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, thus its use in future Audi production models is certainly plausible. A 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.
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