# US 5,700,092 A · Integrated shaft self-compensating hydrostatic bearing

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- Number: US 5,700,092 A
- Document ID: US5700092A
- Status: Granted
- Kind: A
- Application number: 08/518,265
- Filed: 1995-08-23
- Granted: 1997-12-23
- Earliest claimed: 1994-05-04
- Assignees: AESOP, Inc.
- Inventors: Kevin Lee Wasson; Alexander Henry Slocum
- Web page: https://patentgrep.com/patent/US5700092A

## CPC

- F16C 32/0648: {by sensors or pressure-responsive control devices in or near the bearings}
- F16C 32/0659: {of pockets or grooves}
- F16C 32/0685: {for radial load only}
- F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS

## Abstract

An integrated spindle shaft and the like and self-compensating hydrostatic bearing assembly, obviating the need for external bearing sleeve constructions, in which a cylindrical bearing bore is so provided having circumferential grooves connected to pressure supply and drain systems, and in which collection space pressure supply and fluid drain grooves are provided that cooperate with circumferential collector grooves and pockets, such that when fluid flows axially from the pressure groove areas across the shaft into the collector grooves, in proportion to the radial clearance between the shaft surface and the bore, in conjunction to the pocket opposite to the collector groove, to provide a restoring force in proportion to the radial displacement of the shaft.

## Claims

### Claim 1

A self compensating hydrostatic bearing for shafts having, in combination, a cylindrical bearing bore provided with a plurality of circumferential grooves, each connected by radial hole means to pressure supply and drain systems; said grooves comprising pressure supply grooves and drain grooves axially spaced from the pressure supply grooves, and arranged in said bearing bore to serve as fluid supply and fluid drain grooves; a bearing shaft fitted into said bearing bore with a radial clearance that allows for normal shaft deflection and for a radial bearing gap for hydrostatic support action between the said bore and the said shaft; circumferential collector groove means on the surface of said shaft, comprising a plurality of grooves equally spaced around the shaft, such that when the shaft is placed in the bore, the collector grooves in the shaft are axially adjacent to the pressure supply grooves; pockets circumferentially spaced and equal in number, and axially displaced from said collector grooves such that the pockets are located between the drain grooves in said bore when said shaft is inserted therein; flow channels traversing the shaft to connect the collector grooves to the pockets and route the fluid therealong, such that when the fluid flows axially from said pressure grooves across the shaft into said collector grooves, in proportion to the radial clearance between the surface of said shaft and said bore, it can flow to the pocket opposite to the collector, and thus act to provide a restoring force in proportion to the radial displacement of the shaft.

### Claim 2 (depends on 1)

The bearing of claim 1 and in which the shaft comprises a spindle rotatable within the cylindrical bearing bore.

### Claim 3 (depends on 2)

The bearing of claim 2 and in which the flow channels are formed internally of the shaft to connect the collector grooves to the pockets and route the fluid therebetween.

### Claim 4 (depends on 3)

The bearing of claim 3 and in which the flow channels are along chords of the shaft.

### Claim 5 (depends on 2)

The bearing of claim 2 and in which the flow channels are formed as routing grooves along the external surface of the shaft to connect the collector grooves to the pockets and route the fluid therebetween.

### Claim 6 (depends on 5)

The bearing of claim 5 and in which depths of the routing grooves is large compared to said bearing gap.

### Claim 7 (depends on 6)

The bearing of claim 6 and in which the groove depth is at least five times the dimensions of the said gap.

### Claim 8 (depends on 5)

The bearing of claim 5 and in which the pockets are of width substantially comparable to that of the routing grooves.

### Claim 9 (depends on 8)

The bearing of claim 8 and in which a plurality of pocket-routing grooves are employed.

### Claim 10 (depends on 9)

The bearing of claim 9 and in which the routing grooves extend at an obtuse angle to the product grooves.

### Claim 11 (depends on 10)

The bearing of claim 10 and in which the pocket-routing grooves are substantially parallel to one another.

### Claim 12 (depends on 5)

The bearing of claim 5 and in which the pockets and the routing grooves are formed in the inner surface of the cylindrical bearing bore.

### Claim 13 (depends on 5)

The bearing of claim 5 and in which drainage grooves are disposed extending between adjacent pockets.

### Claim 14 (depends on 2)

The bearing of claim 2 and in which the circumferential collector grooves at the ends of the surface of the shaft are of circumferential arc length on the order of 60 degrees.

### Claim 15 (depends on 2)

The bearing of claim 2 and in which the grooves of the plurality of circumferential grooves comprise a pair of spaced pressure supply grooves and a pair of drain grooves axially spaced from the pressure supply grooves.

### Claim 16 (depends on 15)

The bearing of claim 15 and in which the collector grooves in the shaft are axially located between the pair of pressure supply grooves.

### Claim 17 (depends on 2)

The bearing of claim 2 and in which said pocket is comprised of a groove in the shape of a rectangle or a rhombus that surrounds a central land region at the same diameter as the shaft.

### Claim 18 (depends on 2)

The bearing of claim 2 and in which said flow channel from said collector to said pocket intersects said pocket at its leading edge with respect to the direction of fluid flow induced by shaft rotation, such that the fluid flow is carried across the circumferential width of said pocket as the shaft rotates, thereby ensuring that cavitation, foaming, and erosion are minimized, and the pocket receives a more even distribution of pressure.

### Claim 19 (depends on 2)

The bearing of claim 2 and in which said pockets are separated circumferentially by axial drain grooves between the pockets, formed into the surface of said shaft and with the ends of said drain grooves having short circumferential regions that circumferentially taper off of the end of the grooves, better to couple the flow of said grooves into the circumferential drain grooves in the said bore.

### Claim 20 (depends on 2)

The bearing of claim 2 and in which the collector grooves taper from a fraction of about a mm starting depth, to a depth of several millimeters.

### Claim 21 (depends on 1)

The bearing of claim 1 and in which the shaft is movable axially within and along the cylindrical beating bore.