This study is on reciprocating elastomeric seals for use in aircraft linear hydraulic actuator assemblies where reliability of operation is of critical importance. Experiments have been carried out using a novel optical rig that provides images of a gland seal in contact with a glass tube while simultaneously providing 2-D images of the contact itself. When the actuator is left standing the seals natural tendency is to squeeze fluid out of the contact. Such almost dry contact conditions are encountered right when the actuator is started after a rest period. Seal friction in these cases can be expected to be maximum since surface adhesion forces have to be overcome to get relative motion. The flow of lubricant and leakage in the seal contact zone is very complex. The conditions are not homogenous and thicker films and patches can occur at different regions in the seal. Moreover fluid that has already been entrained out of the contact can play a role in the overall lubrication process by helping motoring stroke lubrication. The overall lubrication is a result of many localised flows. The system is made more complex when wear particles are introduced. From the friction results with varying pressure and speeds it is obvious that mixed/boundary lubrication is encountered for the range of pressures and speeds used. It has shown by other work that full film lubrication is possible using favourable conditions but the effects encountered in these experiments dominate the behaviour of the actuator seals particularly when the speeds concerned are low. Such low speeds are encountered when the actuator starts up and slows down within one cycle. Lubrication is generally better at higher pressures so high pressure systems would give rise to a better film much better than low pressure conditions. Wear is easy to instigate and the majority of it takes place during the relatively slow speeds encountered in these experiments. To reduce wear conditions encouraging good lubrication must be designed in to the overall actuator system.
An experimental study on the friction behaviour of aircraft hydraulic actuator elastomeric reciprocating seals
Experimentelle Untersuchung des Reibungsverhaltens der Elastomer-Kolbendichtungen in Hydrozylindern von Luftfahrzeugen
2005
9 Seiten, 7 Bilder, 1 Tabelle, 8 Quellen
Aufsatz (Konferenz)
Englisch
STATIC AND RECIPROCATING ELASTOMERIC TRANSMISSION SEALS
SAE Technical Papers | 1993
Static and Reciprocating Elastomeric Transmission Seals
SAE Technical Papers | 2002
Non-Elastomeric Rod Seals for Advanced Hydraulic Systems
SAE Technical Papers | 1976
|Engineering Index Backfile | 1949
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