Pad type hydrodynamic thrust bearings having a modular construction

DETAILED DESCRIPTION The present invention relates to improvements in hydrodynamic thrust and journal bearings of the type which includes a plurality of discrete bearing pads mounted in a carrier in a circumferentially spaced relation.
Generally, the present invention relates to improvements in pad and carrier design.
Conceptually, the bearing pads and carriers of the present invention are designed by treating the pads and carriers as a solid piece of material and then selectively removing or adding material to the solid to cause it to deflect in a desired way under design loads.
It can be readily appreciated that myriad designs are possible.
Thus, it should be kept in mind that the structural features disclosed herein are generally applicable to any other bearing pad if structural conditions make this possible.
This can be done by modifying the pad shape, the support structure or both.
Specifically, the pad can be modified to include grooves, cuts, rails and recesses to achieve desired deformations under load.
The support structure can be designed to support the pads for movement in the six degrees of freedom (i.
e.
, translation or movement in the +x, -x, +y, -y, +z and -z directions) and rotation about the X, Y, and Z axes so as to optimize formation of the hydrodynamic wedge, but this is not always necessary to achieve desired results.
When desired, the bearings of the present invention designed in three dimensions to provide deflection with six degrees of freedom so as to ensure optimum wedge formation at all times.
It has been discovered that a hydrodynamic bearing operates most effectively when the hydrodynamic wedge has several characteristics.
The wedge should extend across the entire pad surface; the wedge should have an appropriate thickness at all times; the wedge should be shaped so as to minimize fluid leakage; the wedge should accommodate misalignment such that the major axis of the bearing is colinear or substantially parallel to the axis of the shaft; and the wedge should be formed at the lowest speed possible to prevent damage to the wedge forming surface which generally occurs as a result of shaft to pad surface contact at low speeds