The basic control model of an active foil bearing

  • Łukasz Breńkacz
  • Natalia Szewczuk-Krypa
  • Łukasz Witanowski
  • Marta Drosińska-Komor
The article presents the conception of a foil bearing control system, in which a feedback loop is used. The purpose of this system is to improve the dynamic properties of the active foil bearing by changing its geometry. In the system presented, the change in the geometry relates to the size of the lubrication gap and the bearing foils. The system consists of a shaft driven by an electro spindle and radial foil bearings with variable geometry. The system whose main task is to optimise the dynamic properties of a bearing consists of three integrated subsystems. The first subsystem is used to measure the position of the bearing and consists of displacement sensors which are arranged in pairs, perpendicularly to the rotor axis. This arrangement of the sensors makes it possible to determine the displacements of the bearing bush in two directions perpendicular to each other. This subsystem also enables signal processing, which allows to calculate the maximum vibration amplitude (based on measured displacements) in two mutually perpendicular directions. A properly processed signal is analysed by the control subsystem to determine the displacements of the bearing components, which can ensure the change of the dynamic properties of the rotor-bearing system during operation. At the initial stage of the research, it was assumed that the control system would be implemented through the appropriate type of controller. The change of the bearing bush is carried out by the executive subsystem that uses actuators. The changes introduced indirectly, by changing the dynamic properties of the gas film and the supporting foils of the foil bearing, make it possible, among other things, to reduce the vibration level and eliminate resonance vibrations.
Type of Publication:
active bearing; control system; foil bearing; gas bearing; mathematical model
Paper 1055