Improvement of oil-hydraulic polymer slippers using a physically based transient design method

• Applicant: Professorin Dr.-Ing. Katharina Schmitz
• Subject Area: Engineering Design, Machine Elements, Product Development
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 531424256

Oil-hydraulic drives are central to industry, mobile machinery and aviation, as they convert high forces and torques with outstanding power density and dynamics, which is currently unmatched by electromechanical drives. A core component of hydraulic drives are displacement machines that serve as pumps and motors. The performance, efficiency and lifetime of the most commonly used type, the piston machine, is largely determined by the tribological slipper-swashplate-contact. Slippers are typically made from lead-containing non-ferrous metals. In addition to accelerated oil ageing due to the copper contained in the non-ferrous metal, these alloys are at risk of being banned by the EU REACH Regulation due to the toxicity of the lead. The aim of the project is therefore to evaluate the potential of high-performance polymers as an alternative material for the use in piston pump slippers. In addition, the necessary fundamentals for the design and testing of polymer-slippers will be developed and evaluated. This should contribute to improving sustainability as well as environmental and health protection in hydraulics. In the previous project (proj.-no.: 531424256), model tests showed that polymers significantly reduce the friction of slippers. However, increased wear requires geometric adjustments. The basic functionality of a quasi-static elasto-hydrodynamic-lubrication method was therefore developed for the design of polymer-slippers. This was validated quasi-statically on a component test bench. In the continuation of the project, the method and the component test bench are to be transiently dynamically expanded to fully map the operating conditions of slippers. By increasing the performance of the method for tuning slippers their lifetime is to be increased. To evaluate the potential of polymer-slippers and to validate the full functionality of the design method, polymer-slipper functional samples will also be tested in a pump. Based on this, an influence analysis and evaluation of the models of the design method and the tribological test chain under investigation is carried out.

• DFG Programme: Research Grants