Under power: electro cars

From 0 to 100 km/h in 1.513 seconds – that’s a new world record for electrically powered vehicles. It was set in AMZ’s “grimsel” race car in June 2016. Their latest machine bears the name “gotthard.”

The project is backed by the Academic Motor Sports Club Zurich, founded in 2006 by students of ETH Zurich. Every year, the club develops a prototype for the various Formula Student events all over Europe. 130 teams from over 30 countries attended this year’s contest on the Silverstone racetrack.

After three cars with combustion engines, AMZ has been building fully electric cars since 2010. Seven of the zippy vehicles have been built to date, each named after a famous Swiss mountain pass. This year’s car, the 10th from the AMZ workshop, bears the name of the Gotthard pass. “gotthard” weighs a mere 172 kilograms. With 216 horsepower, the power-to-weight ratio is 1.26 HP/kg, a value that exceeds even supercars and gives the car its enormous acceleration.

maxon drive for DRS

maxon drive systems play a small, but important, role in “gotthard’s” efficiency. They are used in what’s called the Drag Reduction System (DRS). As the name says, the DRS’s job is to reduce the drag on the car’s rear wing and improve its efficiency.

The rearmost element of the wing is controlled by a lever system. A brushless maxon EC 22 motor, combined with a GP 22 HP planetary gearhead and an encoder, is used to adjust the wing. The drive unit is hidden inside the main element of the rear wing.

The DRS can have two different states. The flap is either open or closed, depending on which section of the circuit the car is currently on. The closed position is used on most of the track, especially in the turns where the rear wing exerts the most downforce. The higher downforce increases the grip of the tires, which allows the car to go faster in the turns. On the straights, the goal is to reduce air drag as far as possible to enable a higher top speed. Here the second, open state of the DRS is used. By minimizing the drag, the car also requires less energy on the straights.

0.2 seconds to turn

According to Philip Dalla Palma, a focus student in the project and in charge of the front and rear wings, the maxon drive system met the requirements perfectly. “Our requirements on the power train are quite simple really: The DRS flap needs to be turned within 0.2 seconds. The shaft of the planetary gearhead is exposed to a maximum torque of 1.7 Nm, and the shaft must be able to rotate by 165 degrees.” There are no obstacles to future victories and world records. 

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