Electric Instead Of Hydraulic - Machines Should Be Environmentally Friendly

"If we want to advance the energy transition, we need innovations that are suitable for everyday use," said Lower Saxony's Environment Minister Stefan Wenzel. And such innovations should not only be electric drives, they should go beyond them. As an example of this, a project funded by the DBU presented a fully electric sweeper - not only the drive of the vehicle is electrically driven, but also the forward, sideways and backward movements of the brooms. So far, these swiveling movements have been controlled by hydraulic drives. This type of drive is comparatively loud, the required hydraulic oil can damage the environment and, in the partial load range, the hydraulic system should also waste considerable energy due to poor efficiency.

Reduce energy consumption by more than 75%

"Fully electrified machines save energy and are particularly environmentally friendly when used in conjunction with electricity from renewable sources," explains Environment Minister Wenzel. "The difficulty lies in the fact that the linear swivel movements require large forces, have to be fast and the drives also have to be compact," explains Prof. Dr. Ludger Frerichs from the Technical University of Braunschweig took up the challenge. Compared to a sweeper with an internal combustion engine and hydraulic drives, the machine's energy consumption can be reduced by more than 75%. This result results from computer simulation models of the project.

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Electric drives have so far only been used for rotary movements such as vehicle drives, explains Frerichs. The first phase of the research project showed that complete electrification was possible - which would have resulted in a CO ₂ saving of 55%. The use of today's electricity mix was also taken into account in this calculation. If the share of electricity from renewable energies continues to grow in the future, the CO ₂ savings should increase accordingly.

Operate everyday work machines electrically

On February 13, the Environment Minister and Frerichs initiated the second phase of the project at the TU Braunschweig. "Now it will be a matter of optimizing the new drives and testing a test vehicle," says Johannes Oswald, owner of the company of the same name. The sweeper is only an example. Initially, the focus of the project was on attachments such as brooms and bar mowers that are used in the municipal area. In the long term, the results could be used in many everyday machines.

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"Against the background of the energy transition, the project results are very important," says Dr. Heinrich Bottermann, DBU general secretary. Reducing final energy consumption by around 10% by 2020 and by around 40% by 2050 compared to 2005 is one of the core objectives of the transport sector. Bottermann continued: "Therefore, realistic and sustainable future concepts have to be developed not only for the drives, but also for the mobile machines." The project is part of various DBU projects that would make innovative contributions to the development of sustainable future concepts for mobile machines.

The project is being funded by the DBU with a total of 873,000 euros. Project participants are the institutes for mobile machines and commercial vehicles (IMN) and electrical machines, drives and trains (IMAB) of the TU Braunschweig in cooperation with the companies Oswald Elektromotoren in Miltenberg, Bavaria, and Hako in Bad Oldesloe, Schleswig-Holstein. (kj)