Recovering electrical energy from braking is common in hybrids and electric cars, but brake force isn't the only energy that can be harvested while a car is on the move.
We've already written about thermoelectric technology, which recovers energy from hot surfaces such as those of the exhaust, and now we have a look at a new technology from Audi that recovers energy normally lost through a vehicle's suspension.
The technology, which is still in the prototype phase, is called eROT. It relies on electromechanical rotary dampers that replace the hydraulic dampers found in most suspension shock absorbers.
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As shown in the diagram, an arm from the wheel support is connected to a gear unit that converts the up (compression) and down (rebound) movements of the wheel into spinning motion. This motion can then be converted into electricity via a generator. An earlier version of the technology featured a generator integrated with a shock absorber.
“Every pothole, every bump, every curve induces kinetic energy in the car,” Audi R&D boss Stefan Knirsch explains. “Today’s dampers absorb this energy, which is lost in the form of heat… we put this energy to use.”
The bumpier the road, the more electricity that can be generated. Audi says the system generates as much as 613 watts on bumpy roads. Any recovered energy would be stored in batteries and used to power a hybrid's electric motor, or to power electrical accessories in a conventional car. This would lessen the workload of an internal combustion engine, improving fuel economy in a way similar to Mazda's i-ELOOP regenerative braking system.
Crucially, the system can work in reverse, enabling the suspension to adapt to irregularities in the road surface. It would essentially be a new, much more controllable type of adjustable suspension, and a potential boon to future performance cars.
There’s one final advantage. Because the technology eliminates the tall and bulky shock absorbers, it takes up less room than current systems which can mean additional storage space or lower, sleeker cars.
Audi did not confirm when the regenerative suspension system would make its public debut, but with the company poised to launch a slew of electrified vehicles, don't be surprised to see it at an auto show in the near future.