Smart actuator concepts for electromechanical and electrohydraulic drives
The aim of the present project is to investigate the causes of failure of axial piston machines in EHAs (EHA-AKM) in primary flight control, and to develop possible optimization measures.
EHA-pump robustness in primary flight control
Robust linear actuators based on the power-by-wire technology are an essential prerequisite for the development of a (more) electric aircraft. A solution is the use of Electro-Hydrostatic Actuators (EHA). However their application is limited by a comparatively short service life. EHA service life is mostly limited by the robustness of the installed axial piston machines (APM). Therefore this project’s aim is to characterize APM wear. Finally possible optimization methods and strategies can be found.
Condition Monitoring
Due to the currently still limited lifetime of highly dynamic axial piston pumps in the field of aerospace applications, intelligent condition monitoring is required to determine the current wear condition and the remaining lifetime of the pump. In the course of the project, sensors will be integrated into the pump housing to measure temperature, pressure and structure-borne noise for detailed monitoring. In addition, the contamination of the oil will be monitored by sensors at defined points in time as part of the work package, which will allow further conclusions to be drawn about the wear of the pump. To reduce the test duration, a wear matrix will be created and defined wear conditions will be generated manually. The findings obtained are subsequently validated in endurance tests.
Fluid Conditioning and Maintenance
The compactness of highly integrated electrohydraulic drives means that the properties of the hydraulic fluid greatly impacts the overall system behavior. An on target initial fill of the system with hydraulic fluid and precise maintenance are the basis for exceptional reliability and a long operational life. Therefore the goal of this project is to develop the necessary hardware and methodology for initial system fill and maintenance.
The compactness of highly integrated electrohydraulic drives means that the properties of the hydraulic fluid greatly impacts the overall system behavior. An on target initial fill of the system with hydraulic fluid and precise maintenance are the basis for exceptional reliability and a long operational life. Therefore the goal of this project is to develop the necessary hardware and methodology for initial system fill and maintenance.
Autofrettage
Aluminium has lower material strength properties in comparison to steel, a consequence of which is that the tolerable working pressure of the hydraulic system is lower to avoid material fatigue. This can be alleviate by introducing internal stresses in the part through an autofrettage process, however no defined design guidelines currently exist for such parts. Therefore the goal of this project is to investigate the mechanical properties of autofretted hydraulic components made of aluminium and to derive defined design guidelines.
Acknowledgement
This research and development project is funded by the German Federal Ministry for Economic Affairs and Energy (BMWI) within the framework concept "LuFo VI" and is supervised by the Project Management Agency for Aeronautics Research at DLR e.V. (PT-LF). The ifas would like to thank all project participants.
Publications
| Titel | Autor(en) |
|---|---|
| Electro-hydrostatic actuators in primary flight control - lifetime and reliability Contribution to a conference proceedings (2021) | Merkel, Philip Amos Duensing, Yannick Schmitz, Katharina |