Hybrid hydro (air) static multi-recess journal bearing
Multi-recess hydrostatic journal bearings support a rotating shaft and have inclined surfaces, each inclined surface forming a variable radial gap with the surface of the shaft, the variable gaps converging in the direction of rotation of the shaft to increase hydrodynamic forces, reduce a turbulent component of shear friction, and improve the thermal stability of the journal bearing. The inclined surfaces can be formed in one or more of portions of recess bottoms in recesses, portions of gap lands surrounding recesses, and portions of an inner surface of a bushing.
1. A multi-recess hydrostatic journal bearing comprising:
a rotatable shaft having an outer surface;
a bearing housing that surrounds the rotatable shaft, the bearing housing having an inner surface facing the outer surface of the rotatable shaft;
a plurality of recesses located in the internal surface of the bearing housing, each recess of the plurality of recesses having a corresponding recess bottom;
pressurized liquid media between the inner surface of the bearing housing and the outer surface of the rotatable shaft;
inlet restrictors for the plurality of recesses, the inlet restrictors being connected through openings in the bearing housing to an external source of the pressurized liquid media; and
gap lands surrounding each of the plurality of recesses, the gap lands separating the plurality of recesses from chambers connected to atmosphere pressure and separating the plurality of recesses from one another, said recess bottoms being inclined to form variable gaps with the outer surface of the rotatable shaft, the variable gaps decreasing in width, as measured in a radial direction from a rotational axis of the bearing, in a direction of rotation of the rotatable shaft,
wherein, during operation of the bearing, the inclined recess bottoms generate hydrodynamic forces, and
the hydrodynamic forces have both a component in a direction opposite to an applied force and a component in a direction perpendicular to the applied force, and
wherein both the recess bottoms and the gap lands surrounding every recess of the plurality of recesses are inclined to form variable gaps with the outer surface of the rotatable shaft, the variable naps decreasing in width, as measured in the radial direction from the rotational axis of the bearing, in the direction of rotation of the rotatable shaft.
2. The multi-recess hydrostatic journal bearing according to claim 1 , wherein the gap lands surrounding every recess of the plurality of recesses are inclined.
3. The multi-recess hydrostatic journal bearing according to claim 1 , wherein the gap lands surrounding every recess of the plurality of recesses each define portions of a cylindrical surface.
4. The multi-recess hydrostatic journal bearing according to claim 1 , wherein the bottom surfaces of the plurality of recesses each contain a slot portion to accept pressurized liquid media from the corresponding inlet restrictor.
5. The multi-recess hydrostatic journal bearing according to claim 1 ,
wherein the plurality of recesses each have an elevated middle portion provided inside each recess and a groove that surrounds the elevated middle portion to accept pressurized liquid media from the corresponding inlet restrictor, each elevated middle portion having an inclined surface that forms a variable gap with the outer surface of the rotatable shaft, the variable gap decreasing in width in the direction of rotation of the rotatable shaft as measured in the radial direction from the rotational axis of the bearing,
the gap lands each define portions of cylindrical surface, and
the elevated middle portions and the gap lands, during operation of the bearing, generate second hydrodynamic forces.
6. A multi-recess hydrostatic journal bearing comprising:
a rotatable shaft having an outer surface;
a bearing housing that surrounds the rotatable shaft, the bearing housing having an inner surface facing the outer surface of the rotatable shaft;
a plurality of recesses located in the internal surface of the bearing housing, each recess of the plurality of recesses having a corresponding elevated middle portion provided inside each recess, each elevated middle portion having a top surface that is inclined to form a variable gap with the outer surface of the rotatable shaft, the variable gaps decreasing in width, as measured in a radial direction from a rotational axis of the bearing, in a direction of rotation of the rotatable shaft;
pressurized liquid media between the inner surface of the bearing housing and the outer surface of the rotatable shaft;
inlet restrictors for the plurality of recesses, the inlet restrictors being connected through openings in the bearing housing to an external source of the pressurized liquid media; and
gap lands surrounding each of the plurality of recesses, the gap lands separating the plurality of recesses from chambers connected to atmosphere pressure and separating the plurality of recesses from one another,
wherein, during operation of the bearing, the inclined surfaces generate hydrodynamic forces,
the hydrodynamic forces have both a component in a direction opposite to an applied load and a component in a direction perpendicular to the applied load, and
a groove surrounds each elevated middle portion to accept pressurized liquid media from a corresponding inlet restrictor of the plurality of recesses.