# US 2010/0166348 A1 · Motor with aerodynamic pressure bearing mechanism

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- Number: US 2010/0166348 A1
- Document ID: US20100166348A1
- Status: Published application
- Kind: A1
- Application number: 12/451,665
- Filed: 2008-05-21
- Published: 2010-07-01
- Earliest claimed: 2007-05-25
- Assignees: Nidec Copal Electronics Corporation
- Inventors: Akiyoshi Takahashi; Toshiya Uchida
- Web page: https://patentgrep.com/patent/US20100166348A1

## CPC

- F16C 17/10: for both radial and axial load
- F16C 17/026: {with helical grooves in the bearing surface to generate hydrodynamic pressure, e.g. herringbone grooves}
- F16C 17/045: {with grooves in the bearing surface to generate hydrodynamic pressure, e.g. spiral groove thrust bearings}
- F16C 33/1015: {Pressure generating grooves}
- F16C 33/107: {Grooves for generating pressure}
- F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS

## Abstract

In a gas dynamic pressure bearing mechanism (1) for smoothing rotary motion of a shaft (10) by feeding gas to the bearing clearance between the shaft (10) and a fixed sleeve (20) for supporting the shaft (10) through a herring bone groove (10a), the herring bone groove (10a) is provided in the shaft (10) such that pressure distribution generated in the bearing clearance moves at a high speed. The herring bone groove (10a) consists of N grooves such that N minimal pressure values appearing alternately with maximal pressure values at the positions where the maximal pressure values of dynamic pressure variation appear in the bearing clearance when the shaft (10) rotates have such an interval as it becomes lower than the condensation pressure value.

## Claims

### Claim 1

A motor provided with an aerodynamic pressure bearing mechanism, the mechanism comprising: a rotating axis; a fixed member having a surface facing the surface of the rotating axis with a predetermined bearing clearance; and herring bone grooves composed of N number of grooves placed on the surface of the rotating axis at regular intervals in the rotational direction and configured to generate dynamic pressure within said bearing clearance during rotation,
wherein said herring bone grooves are composed of N number of grooves at positions where maximal pressure values of dynamic pressure variation in said bearing clearance caused during rotation of said rotating axis appears, and at intervals such that N number of minimal pressure values appearing in alternation with said maximal pressure values are lower than the condensation pressure value.

### Claim 2 (depends on 1)

The motor according to claim 1, wherein the N number of grooves composing said herring bone grooves are disposed at a predetermined intake angle β (0<β≦90°) towards the center in the axial direction of the rotating axis with the edge of one end part in the axial direction of said rotating axis as one end of the grooves, and at a ratio between the length of said grooves in the axial direction and the axial diameter of the rotating axis being α (0.2<α<0.8), wherein
said grooves are composed of N number of grooves at intervals such that when rotating at a rotation frequency of M (40<M≦60: krpm for units) in an environment in which the ambient humidity is approximately 60% RH, at least said minimal pressure values become equal to or lower than 1.7 atm.

### Claim 3 (depends on 1)

The motor according to claim 1, wherein said N is any integer from 3 to 5 when said rotating axis rotates with said M being approximately 60 (krpm).

### Claim 4

A motor that is used for rotating a scanning member for scanning with a laser light or a fan for blowing wind, the motor being attached to a rotating axis and provided with an aerodynamic pressure bearing mechanism, the mechanism comprising: said rotating axis; a fixed member having a surface facing the surface of the rotating axis with a predetermined bearing clearance; and herring bone grooves composed of N number of grooves placed on the surface of the rotating axis at regular intervals in the rotational direction and configured to generate dynamic pressure within said bearing clearance during rotation,
wherein said herring bone grooves are composed of N number of grooves, and the respective grooves are disposed at an intake angle β (0<β≦90°) towards the center in the axial direction of the rotating axis with the edge of one end part in the axial direction of said rotating axis as one end of the grooves and at a ratio α between the length of said grooves in the axial direction and the axial diameter of the rotating axis being in the range of approximately 0.2 to 0.8, wherein said grooves are composed of N number of grooves at positions where maximal pressure values of dynamic pressure variation in said bearing clearance caused during rotation at a rotation frequency of M (40<M≦60: krpm for units) in an environment in which the ambient temperature is approximately 60° C. or less and the ambient humidity is approximately 60% RH appear, and at intervals such that N number of minimal pressure values appearing in alternation with said maximal pressure values are equal to or lower than 1.7 atm.

### Claim 5 (depends on 4)

The motor according to claim 4, wherein the total of the lengths of circumferential components of said respective grooves placed at regular intervals in said circumferential direction is shorter than the circumferential length of said rotating axis.

### Claim 6 (depends on 4)

The motor according to claim 4, wherein said N is any integer from 3 to 5 when said rotating axis rotates with said M being approximately 60 (krpm).

### Claim 7 (depends on 2)

The motor according to claim 2, wherein said N is any integer from 3 to 5 when said rotating axis rotates with said M being approximately 60 (krpm).

### Claim 8 (depends on 5)

The motor according to claim 5, wherein said N is any integer from 3 to 5 when said rotating axis rotates with said M being approximately 60 (krpm).