Zero Emission Drive Unit – Generation 1 (ZEDU-1)

The benefits at a glance

• Mitigation of particulate matter and microplastic emissions
• Development of innovative vehicle components
• Fine dust-free brake system without loss of performance
• Reduction of tyre wear emissions to the lowest feasible levels
• High efficiency energy management
• Reduction of environmental pollution resulting from road transport
• Improvement of air quality
• Reduction of particulate matter, ultrafine particulate matter and microplastic-related health risks caused by road transport
• Contribution towards attaining forthcoming mandatory emission standards
• Demonstration and metrological proof of the technology at Technology Readiness Level (TRL) 7
• Scaling series / transfer for use in passenger cars, commercial vehicles, rail, ...
• Strengthening Baden-Württemberg as a hub for technology and business

Background and research approach

Tyre abrasion on roads is responsible for more than a quarter of microplastic emissions worldwide. When it rains, these tiny particles make their way into the drainage system and thus into the water cycle. In Germany alone, this amounts to approximately 110,000 tonnes of matter a year. Braking also causes the abrasion of brake discs and brake pads. Over 90 percent of the resulting debris (5,500-8,000 tonnes per year) takes the form of ultrafine particles. These particles are considered to be particularly harmful to the environment and human health, as they can penetrate deep into our respiratory systems and become lodged there before entering the bloodstream. Transport-related abrasion thus contributes to poor air quality in cities as well as the health risk associated with road transport.

The project centres on advancing drive-relevant components that have been relatively overlooked in prior initiatives, yet hold intrinsic significance as emission sources across various forms of energy generation and operation: Brake units and tyre abrasion. Through the mitigation of emissions from these origins, mobility, when coupled with energy derived from renewable sources and electric propulsion, has the potential to achieve near-complete emission neutrality.

Together with the companies HWA, which was subcontracted with the design of the first-generation ZEDU-1 as the drive axle and the construction of the test vehicle, and Frenoza, which manufactures hard metal coatings for brakes, the project was successfully executed.

Rethinking the brake system and housing of the wheels

Technologically, the project represents a significant advancement. The braking system undergoes a fundamental shift, transitioning from the wheel carrier to the drive unit, where it is integrated. Through a synergistic combination of finely-tuned high-performance electronics, a power battery and a BBW system (Break-by-wire), the majority of braking energy can be effectively recuperated, thereby minimising reliance on mechanical braking components. This innovation facilitates the construction of an exceptionally compact drive unit, integrated into the transmission brake unit, while entirely eliminating brake wear emissions.

Various brake concepts were analysed and combined for this purpose. Two innovative systems were realised and investigated. Firstly, a specially developed multi-disc brake; operating mechanically as a closed system. The low level of brake abrasion is transported by the oil, which is also used for cooling and lubrication, into a filter and contained there. Secondly, an induction brake; exhibiting nearly negligible wear even down to a standstill, it harnesses magnetic fields to generate braking force.