Audi developing electromechanical rotary dampers; potential for energy recuperation from suspension; 48V
10 August 2016
Audi is developing a prototype electromechanical rotary dampening system called “eROT,” in which electromechanical rotary dampers replace the hydraulic dampers used today for an even more comfortable ride. The eROT system also offers the potential for energy recuperation from the suspension.
Every pothole, bump, and curve in the road induces kinetic energy during compression and rebound of the car’s suspension, observes Dr.-Ing. Stefan Knirsch, Board Member for Technical Development at AUDI AG. “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. It also presents us and our customers with entirely new possibilities for adjusting the suspension.”
|Audi’s prototype eROT system. Click to enlarge.|
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.
To convert the kinetic energy during compression and rebound into electricity, eROT uses a lever arm to absorb 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.
Audi said that initial test results for the eROT technology are promising, and 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.
Some 15 + years ago an Italian sports car maker (i can't recall the brand but they also made helicopters Ferrari?Lambo? Maserati?) had an active suspension system with forward facing 3D sensors scanning the road. If an obstacle was in the path it pulled the relevant wheel clear or adjusted the damping
Today's, 'on the fly' technology and computing would be a good fit with active suspension and energy recuperation.
of course for mass production cost and the development of simple reliable design is the first step.
The wheel need not
Posted by: Arnold | 10 August 2016 at 03:33 PM
Arnold, MB has that system, they call it "Magic body control".
I do question the amount of energy that is wasted through dampers, I mean if it was that much energy then today dampers would be smoking hot.
Posted by: GasperG | 11 August 2016 at 12:50 AM
GasperG; Belive me, they get hot... But this we seldom notice in a car, because the dampers are mounted where we never touch them.
I've raced quite much motorcycle enduro racing, and sometimes the damper get so hot you cannot touch it.
Also, consider the figures; at maximum 600 watt. On four wheels. 150 watt per wheel. That is not really so much.
Posted by: bjogen | 11 August 2016 at 07:10 AM
600watt may not be much available, though the competition pushbike platoon? know how important suspension losses can be when the power is limited.
Not to suggest that hydraulic and sticktion / friction is the only or even main problem they face.
We saw concepts for rail car energy recuperation and an active electric damping design allowing wheel motors to be mounted to the body corner without need for conventional suspension arrangement.
These examples may return limited useful energy but the primary benefit could be from the suspension tuning ability.
Hovercraft can travel at speed over irregular surface.
There should be a pay off in shorter travel times and reduced body loading ( hence weight reduction possibilities) as well as reducing road or rail damage.
Posted by: Arnold | 11 August 2016 at 02:19 PM
Checked out the MB Magic.
The design I referred to was active suspension - the wheel was mechanically withdrawn clear of the impending contact.
Magic ride only controls the the damping.
Posted by: Arnold | 11 August 2016 at 04:07 PM
No, it's exactly that, scanning the road surface and changing suspension height, before wheel hits the obstacle.
Posted by: GasperG | 12 August 2016 at 04:30 AM
Regarding MB:s system; Imagine when these cars get 15 years old, and something mess up the calibration of this system. I mean, when/if the system "decides wrong" distance to an upcoming bump. Could become an interesting ride...
Posted by: bjogen | 12 August 2016 at 04:41 AM
I can see why one might think that the MB suspension retracts but there is no 'specific confirmation' on that link .
"the suspension is prepped"for the road surface still reads as a damping adjustment to me. Why read more into it?
I think the final word will come from a tech familiar with the system.
Posted by: Arnold | 12 August 2016 at 06:27 PM