2018 EPFL / Controllable Lubrication
IGM Colloquium: Controllable Fluid Film Bearings–Theory & Experiments
Prof. Ilmar Ferreira Santos, Laboratory for Electro-Mechanical Machine Elements (Mechatronics) / Section of Solid Mechanics / Technical University of Denmark.
Industry 4.0 embraces a set of technologies enabling smart products. Smart products are characterized by the capability of performing computations, storing data, communicating and interacting with their environment. Fluid film bearing technology is nowadays witnessing an explosive expansion of active magnetic bearing technology, a typical so-called smart product.
Some of the limitations and drawbacks associated to fluid film bearing technology could be overcome by combining fluid film bearings with sensing, control and signal processing techniques, lending them “smartness”, “multi-functionality” and “higher reliability”. In such a framework, it is important to evaluate the state-of-the-art of controllable fluid film bearings, which fit perfectly within Industry 4.0 and have been investigated over the last two decades but have not yet found their space in industrial applications, despite several promising theoretical and experimental achievements.
With the aim of monitoring, predicting and controlling sliding bearings’ thermal, static and dynamic characteristics several types of sensing systems and electro-mechanical actuators—hydraulic, pneumatic, piezoelectric or magnetic, among others—have been coupled to such bearings allowing for different regulation and control strategies of pressure, lubricant flow and bearing clearance. Depending on (i) the actuator type; (ii) the actuation principle, i.e., hydraulic, pneumatic, piezoelectric or magnetic among others; and (iii) how such an actuator is coupled to the sliding bearings, different regulation and control actions of fluid film pressure and lubricant flow can be obtained. The most common actions are: (a) the control of the injection pressure to modify the fluid film pressure statically as well as dynamically; (b) the adjustment of the angle and direction of injection flow (mostly passive action); (c) the control of the sliding bearing gap and its preload via moveable and compliant sliding surfaces; and (d) the control of the lubricant viscosity. All four parameters, i.e., pressure, flow (velocity profiles), gap and viscosity, are explicit parameters in the modified form of Reynolds’ equations for active lubrication. In this framework, this work gives one main original contribution to the state-of-the-art of radial fluid film bearings and controllable lubrication: a comprehensive overview about the different types of controllable sliding bearings and principles. Some conclusive remarks about advantages and drawbacks of the different design solutions for controllable sliding bearings are given and the main challenges to be overcome towards industrial applications are addressed.
source: The Ecole polytechnique fédérale de Lausanne (EPFL)