Through the desert with solar power

From Darwin to Adelaide. Once across the Australian desert, past breathtaking national parks, the solar-powered cars have to cover 3,022 kilometres in the World Solar Challenge. They have exactly one week to do so. The participants' cars are only allowed to travel with the power of the sun. The student teams from all over the world are developing different vehicle concepts that differ greatly from one another in terms of aerodynamic design, choice of solar cell technology, height and width. The students thus demonstrate the colourful diversity of sustainable technologies. One of this year's participants in the race comes from Aachen. Team Sonnenwagen took part in the biennial competition for the second time. While they were able to learn a lot during their first participation, the 2019 team was able to master the entire route through the desert.
Team Sonnenwagen opted for a completely different concept than in 2017, using solar cells made of gallium arsenide instead of the standard silicon cells on just 2.6 square metres instead of the previous 4 square metres. The new cells are much more efficient than the previous technology. Due to the regulations of the competition, only a smaller area could therefore be installed. Another innovation can be seen in the bearings. The bearings are immensely important because they hold the car together. If a bearing fails, the repair is extremely costly. In addition, the bearings used must be wear-resistant and lightweight. This is because the lighter the sun carriage, the more efficiently it can be driven and the sooner it can cover a greater distance. polymer plain bearings from igus® therefore appeared to the team to be the optimum solution.

Our lightweight plain bearing technology can be found in countless places in the Sonnenwagen. Self-adjusting igubal® clevis joints made of iglidur® J are used in the telescopic mechanism for the solar cover and in the steering wheel. And iglidur ® J bearings can be found in the wheel suspension of the rear wheels and in the steering gear. The wear-resistant bearing has a very low coefficient of friction on all shafts, especially in dry operation, and is vibration-damping. An advantage above all for the steering feel. iglidur® J is - like all iglidur® materials - lubricant- and maintenance-free, as solid lubricants are embedded in the bearings. In the hinges of the cover lock there are also plain bearings made of the material iglidur® G. The tribo-polymer is cost-effective and has a high wear resistance.
A robolink® gearbox - actually intended for robot articulated arms - is used with polymer sliding elements in the steering system. Unusual, but efficient and lightweight. The four tyres are steered using four cable pulls. Thanks to the robolink® gearbox, the flex shaft and the hand wheel, the two rear tyres can be optimally aligned with the wind when driving, allowing the additional drive force to be used. This enables speeds of 140 kilometres per hour and more.
Finally, bearings are also used on the solar car lid. As the driver has to open and close the lid with the 25-kilogram solar cells themselves when getting in and out of the car, the sluggish self-printed bearings made from a standard plastic used to be a problem. iglidur ® i3 bearings, which are characterised by their low coefficient of friction and insensitivity to dust and dirt, are now used. This means it only takes a few seconds to get in and out of the car.