Air bearing

None.

None.

1. Field of the Invention

The present invention relates generally to an air bearing, and more specifically to a dynamic air bearing with corrugated surfaces on the rotating journal.

2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98

Air or ideal gas bearings are used to rotatably support a rotor shaft in which a fluid cushion is used to support the rotating part. Fluid bearings are non-contact bearings that produce less friction that roller bearings and can be operated at very high rotational speeds. The air bearing is not favored for dynamic engine applications due to low bearing stiffness that may result in undesired contact between the rotor and the static parts. Various prior art air bearings include a corrugated structure in the static lands and separate this surface from the rotating journals with a cylindrical rub surface.

It is an object of the present invention to provide for an air bearing with a relatively high bearing stiffness compared to the cited prior art references.

It is another object of the present invention to provide for an air bearing with a surface that adds pumping capability to increase the hydrodynamic squeeze pressure.

It is another object of the present invention to provide for an air bearing with a corrugated surface on the rotor section of the air bearing.

These objectives and more are achieved in the air bearing of the present invention in which a section of the rotating part of the air bearing includes corrugations that form a surface that produces a pumping motion to increase the hydrodynamic squeeze pressure of the air bearing and therefore increases the stiffness of the air bearing. The corrugations are concave dimples like on a golf ball that open outward and face an inner surface of the static part of the air bearing. Sundry seals are positioned on both sides of the dimples of the air bearing to form a seal for pressurized air delivered to the air bearing through a supply channel formed in the rotor shaft.

FIG. 1 shows a cross section view of the air bearing with the rotating corrugations of the present invention.

FIG. 2 shows a cross section front view of a section of the bearing inner race with the hemispherical pockets of FIG. 1 .

FIG. 3 shows a surface view of the hemispherical pockets on the bearing inner race of FIG. 1 .

The present invention is an air bearing with corrugations formed on the rotating surface of the air bearing and function to increase the hydrodynamic pressure of the air bearing and thus increase the air bearing stiffness so that the air bearing can be used in a dynamic engine application. Air or vapor or another compressible fluid can be used for the air bearing. FIG. 1 shows the air bearing assembly and includes a rotor 11 , an air or vapor supply channel 12 , a sundry seal arrangement 21 on a static land 21 with another seal arrangement 13 on the rotor 11 , a retaining ring and seals 14 , an anti-rotation lock 15 , a bearing inner race 16 , a high pressure reservoir 17 formed on an inner surface of the bearing inner race, and a plurality of supply channels 18 formed in the inner race 16 that open into a plurality of face hemispherical pockets 19 opening on an outer surface of the inner race 16 . A clearance gap 20 is formed between the rotor 11 and the land 21 of around 0.001 inches (0.0254 mm).

FIG. 2 shows a cross section view along the axis of the rotor 11 of the bearing inner race 16 with the arrangement of the pockets 19 opening outward. FIG. 3 shows a section of the outer surface of the inner race 16 with the arrangement of the pockets 19 that form pumping action to increase the hydrodynamic squeeze pressure of the air bearing.

In operation, high pressure air (or vapor) or another compressed fluid is supplied through the channels 12 and into the reservoir 17 , which is then routed through the plurality of supply channels or orifices 18 and into the pockets 19 . The supply channels or orifices 18 function as centrifugal pumps for the high pressure air passing through. The air or vapor in the damper cavity is at a higher pressure than in the supply due to the centrifugal pumping action. As the rotor eccentricity (displacement over the clearance) increases, a pressure gradient forms due to the squeeze effect of the proximal surface and aided by an irregular surface. Also, the air or vapor is displaced around the rotor lower pressure regions, and the air or vapor trapped in the pockets 19 cannot be displaced but will increase the local pressure due to volumetric compression. If the medium used is a saturated vapor, the hydrostatic pressure—due to a large eccentricity—in the pockets 19 may introduce a phase change from vapor to a saturated liquid that will increase the bearing stiffness to asymptotic infinity.