An improved foil thrust bearing having a thrust runner and a thrust plate includes an underspring element positioned adjacent to the thrust plate. The underspring element comprises, in one embodiment, a plurality of alternating first apertures and spring portions, with at least one spring portion having a periodic configuration and comprising a leading edge and a trailing edge. The periodic configuration is defined by a plurality of pitches that vary between the leading and trailing edges. Also defining the periodic configuration is a plurality of periodic elements that vary in longitudinal length between the leading and trailing edges. A thrust bearing disk is disposed intermediate the underspring element and the thrust runner. The disk comprises a plurality of transition areas that provide a stepped configuration to the disk. The transition areas match a plurality of circumferential positions of the first apertures in the underspring.
An improved foil thrust bearing includes a cooling fluid flow turbulence generating disk placed between other foil thrust bearing elements, such as thrust bearing elements and underspring elements. The inventive turbulence generating disk generally provides improved transfer of heat through the foil and into the cooling fluid of foil thrust bearings that may be used for high rotor speed applications. It accomplishes this by improving the transfer of heat through the foil and into the cooling fluid by generating turbulent cooling flow adjacent to the back of the top foil. The turbulent flow is generated primarily by a series of turns or protrusions introduced into the cooling flow stream. Alternate embodiments are disclosed that provide the turbulence generating elements as part of the underside of thrust bearing elements.
A high load capacity hydrodynamic journal foil bearing system is disclosed, which comprises a top foil and a plurality of undersprings. Preload forces are transferred from the undersprings to internal circumferential compressive forces within a top foil, resulting in low preload forces against the shaft, allowing the shaft to expand at high speeds without increasing the preload forces or overloading the fluid film. One underspring may have a different spring rate than another underspring. The top foil may be normalized to shaft shape and dimensions. These features may be accomplished with using less mechanical parts than other journal foil bearing system designs.
