DE102015009167A1 - Conical fluid dynamic bearing system - Google Patents

Abstract

The invention relates to a conical fluid-dynamic bearing system comprising a first conical fluid dynamic bearing and a second conical fluid dynamic bearing counteracting the first conical bearing, the first and second conical fluid dynamic bearings being arranged along a shaft (10) and each having a conical bearing surface (12, 12). 16) and a conical abutment surface (28, 36) separated by a bearing fluid filled with a bearing gap (40), wherein the two conical bearing surfaces (12, 16) are formed as part of the shaft (10), and first conical abutment surface (28) on a first bearing component (24; 124) and the second conical abutment surface (28) on a second bearing component (32) is arranged. According to the invention, the two bearing components (24, 32, 124) are designed and mountable in such a way that they align themselves radially and axially relative to one another.

Description

Field of the invention

The invention relates to a conical fluid dynamic bearing system, which can be used in particular for the rotary mounting of a spindle motor. Spindle motors with such conical fluid dynamic bearings are used for example for driving hard disk drives.

State of the art

The US 2004/0005101 A1 discloses a fluid dynamic bearing system with two conical bearings whose bearing forces act against each other. Each conical bearing has a bearing cone arranged on a fixed shaft, which cooperates with an abutment which is arranged in a rotor component. The bearing surfaces of each conical bearing are separated by a separate, filled with a bearing fluid bearing gap. The bearing gaps of the two conical bearings each have two open ends, each open end being sealed by a conical sealing gap partially filled with bearing fluid.

In conical fluid dynamic bearings, it is known that the two bearing cones are connected by means of a press connection with the shaft. In this case, a relatively strong press fit must be provided so that the required extrusion forces between shaft and bearing cones are achieved. Due to the so-called stick-slip effect, it is relatively difficult and technically complicated to set the exact axial distance between the two bearing cones on the shaft and thus the axial play of the bearing. The distance between the two bearing cones on the shaft determines the axial play and the width of the bearing gaps of the two bearings and must be set very precisely.

For pressing the bearing cones on the shaft large forces must be exerted on the bearing cones, so that it can lead to a deformation of the bearing cones, and in particular a deformation of the bearing surfaces of the Lagerkonusse. Furthermore, when the bearing cones are pressed onto the shaft, frictional effects may occur, resulting in metal particles which, if they enter the bearing gap, may damage the bearing. In addition, particles in the bearing gap create undesirable bearing friction.

However, when the bearing cones are pressed onto the shaft, micro-fine scratches and grooves also occur at the bearing cones, which run parallel to the axis of rotation and through which bearing oil can escape from the bearing to the outside. Another problem arises from the fact that channels and grooves on the inner circumference of the bearing cones are preferably eroded by means of electrochemical removal. These channels and grooves are needed for a circulation of the bearing fluid in the bearing. Due to these surface abrasions, less joining surface remains for the press connection between the shaft and the bearing cones, which reduces the pressing force. In the case of electrochemical erosion, unwanted erosion also occurs due to the relatively deep and wide channels, which can also unfavorably influence the achievable extrusion forces of the press connection. This unwanted erosion can also lead to undesirable migration of the bearing fluid between the bearing cone and the respective end of the shaft.

In addition, the ECM process requires a relatively large process time because the width and depth of the channels and grooves are much larger compared to bearing groove structures that are also generated by ECM.

The US 2007/0252461 A1 discloses a conical fluid dynamic bearing system having a first conical fluid dynamic bearing and a second conical fluid dynamic bearing opposing the first conical bearing, wherein the first and second conical fluid dynamic bearings are arranged along a shaft and each comprise a conical bearing surface and a conical abutment surface are separated from each other by a bearing gap filled with a bearing fluid. The two conical bearing surfaces are formed as part of the shaft, wherein the first conical abutment surface is arranged on a first bearing component and the second conical abutment surface on a second bearing component.

Disclosure of the invention

The object of the invention is to provide a conical fluid dynamic bearing of the type described above, which can be mounted easier and more accurate and has greater holding forces and less leakage problems.

This object is achieved by a fluid dynamic bearing with the features of claim 1.

Preferred embodiments of the invention and advantageous features are indicated in the dependent claims.

The conical fluid dynamic bearing system comprises a first conical fluid dynamic bearing and a second conical fluid dynamic bearing counteracting the first conical bearing, the first and second conical fluid dynamic bearings are arranged along a shaft and each comprise a conical bearing surface and a conical abutment surface, which are separated by a bearing fluid filled with a bearing gap, wherein the two conical bearing surfaces are formed as part of the shaft, and the first conical abutment surface at a first Bearing member and the second conical abutment surface is arranged on a second bearing component.

According to the invention, the two bearing components are designed and installed so that they align themselves radially and axially to each other.

The two bearing surfaces of the conical bearings are arranged directly on the shaft and formed integrally with the shaft. As a result, the bearing surfaces can be processed very accurately with respect to each other, in particular, the axial distance of the bearing surfaces can be maintained very accurately.

In the prior art, the bearing surfaces were arranged on separate bearing cones, wherein the bearing cones were fastened by means of a joint connection on the shaft.

It was necessary in a special joining device to press the first bearing cone to a defined extent on the shaft, and then to press the second bearing cone at a defined axial distance from the first bearing cone on the shaft.

Due to the axial distance between the two bearing cones, the axial clearance of the bearing system was determined, so that a high-precision joining device had to be used in order to obtain a reproducible axial clearance in series production of such conical bearing systems.

Another advantage of the present invention is that the two bearing components, which form the abutment surfaces to the bearing surfaces of the shaft, are formed so that they independently radially and axially align with each other and thus a highly accurate concentric alignment with respect to the shaft and the arranged on the shaft bearing surfaces is possible.

The axial clearance of the bearing system is inventively determined by the two bearing components or the mutual position of the two bearing components.

For this purpose, the two bearing components on determining surfaces that allow a highly accurate mutual alignment and alignment with respect to the shaft so that the bearing components can be mounted on the one hand concentric to the shaft and on the other hand, a defined axial clearance of the bearing is maintained.

Preferably, the two determining surfaces are formed by oblique mating surfaces, which are arranged on the facing sides of the two bearing components.

According to the invention, the mating surfaces need not be formed obliquely, but they may also be formed at right angles to the axis of rotation of the bearing and have corresponding positioning means to obtain a concentric positioning of the two bearing components and a defined axial play.

The bearing surfaces of the shaft or the abutment surfaces of the bearing components or the bearing surfaces and the abutment surfaces have corresponding Lagerrillenstrukturen that characterize the fluid dynamic bearing.

According to a first embodiment of the invention, the first and the second conical fluid dynamic bearing can be directly connected to one another via a gap filled with bearing fluid.

In another embodiment of the invention, the first and second conical bearings may be separated by a non-bearing fluid filled area.

In a preferred embodiment of the invention, at least one pumping seal can be arranged on the smallest diameter of the shaft, which conveys the bearing fluid in the direction of the conical bearings.

Furthermore, preferably at least one pumping seal can be arranged on the largest diameter of the shaft, which conveys the bearing fluid in the direction of the directly adjacent conical bearing.

The invention will be described in more detail below with reference to preferred embodiments with reference to the drawings.

Brief description of the drawings

1 schematically shows a section through the conical fluid dynamic bearing system in a first embodiment of the invention

2 schematically shows a section of the conical fluid dynamic bearing in a second embodiment of the invention

Description of preferred embodiments of the invention

1 shows a cross section of a schematic representation of a conical fluid dynamic bearing system according to the invention.

The bearing includes a shaft 10 , which may be formed as a fixed shaft or rotating shaft. The wave 10 is concentric with a rotation axis 50 of the warehouse.

The wave 10 includes a first cylindrical end portion 10a , an adjoining conical section 10b , a cylindrical middle section 10c , an adjoining conical section 10d and a second cylindrical end portion 10e ,

Starting from the cylindrical end sections 10a . 10e the diameter of the shaft increases 10 along the conical sections 10b and 10d up to a maximum outside diameter, which in the middle cylindrical section 10c is reached.

The conical sections 10b and 10d the shaft are directed away from each other, that is, their radially outward surface normal do not intersect.

The storage system comprises two bearing components 24 . 32 , each one bearing bore 26 . 34 include. The bearing components 24 . 32 are arranged so that they wave 10 in the bearing bores 26 . 34 such that between the outer peripheral surfaces of the shaft 10 and the inner peripheral surfaces of the bearing components 24 . 32 A gap 40 is formed, which is filled with a bearing fluid.

Here is the outer diameter of the shaft 10 in all sections 10a to 10e slightly smaller than the inner diameter of the bearing bores 26 . 34 the two bearing components 24 . 32 ,

The end section 10a the wave 10 forms with an opposite cylindrical portion of the bearing bore 26 of the first bearing component 24 a first sealing gap 40a ,

The conical section 10b the wave 10 forms with an opposite conical portion of the bearing bore 26 of the first bearing component 24 a conical bearing gap 40b ,

The cylindrical middle section 10c the wave 10 forms with an opposite cylindrical portion of the bearing bore 26 of the first bearing component 24 a separator gap 40c ,

Accordingly, the cylindrical end portion forms 10e the wave 10 with an opposite cylindrical portion of the bearing bore 34 of the second bearing component 32 a sealing gap 40e , and the conical section 10d the wave 10 forms with an opposite conical portion of the bearing bore 34 of the second bearing component 32 a conical bearing gap 40d ,

On the conical sections 10b and 10d the wave 10 are storage areas 12 . 16 formed while on the opposite conical sections of the bearing bore 26 of the first bearing component 24 an abutment surface 28 is formed, that of the storage area 12 is assigned, and on the conical portion of the bearing bore 34 of the second bearing component 32 another counter bearing surface 36 , which is the storage area 16 assigned.

The storage area 12 includes bearing groove structures 14 , which are preferably formed asymmetrically and first bearing grooves 14a as well as second bearing grooves 14b include.

The first bearing grooves 14a are so on the storage area 12 arranged that during operation of the storage system, a pumping action on the in the bearing gap 40b bearing fluid in the direction of Separatorspalts 40c produce.

The second bearing grooves 14b are so on the storage area 12 arranged that during operation of the camp a pumping action on the in the bearing gap 40b located bearing fluid in the direction of the first sealing gap 40a produce.

Preferably, the bearing grooves 14a formed longer or wider or deeper than the bearing grooves 14b , so that the hydrodynamic effect of the bearing grooves 14a predominates and the bearing groove structures 14 Overall, a predominantly in the direction of Separatorspalts 40c directed pumping action on the in the bearing gap 40b produce bearing fluid.

The bearing groove structures 14 can either be on the storage area 12 the wave 10 be arranged or according to the counter bearing surface 28 of the first bearing component 24 or on the storage area 12 and the counter bearing surface 28 ,

The conical section 10d The shaft also forms a storage area 16 , which with bearing groove structures 18 is provided.

The bearing groove structures 18 preferably consist of groove structures 18a and groove structures 18b that are asymmetrical to each other.

The first bearing grooves 18a are so on the storage area 16 arranged that during operation of the storage system, a pumping action on the in the bearing gap 40d bearing fluid in the direction of Separatorspalts 40c produce.

The second bearing grooves 18b are so on the storage area 16 arranged that during operation of the camp a pumping action on the in the bearing gap 40d located bearing fluid in the direction of the second sealing gap 40e produce.

Preferably, the bearing grooves 18a formed longer or wider or deeper than the bearing grooves 18b , so that the hydrodynamic effect of the bearing grooves 18a predominates and the bearing groove structures 18 Overall, a predominantly in the direction of Separatorspalts 40c directed pumping action on the in the bearing gap 40d produce bearing fluid.

The bearing groove structures 18 can either be on the storage area 16 the wave 10 be arranged or according to the counter bearing surface 36 of the first bearing component 32 or on the storage area 16 and the counter bearing surface 36 ,

Preferably, the conical bearing system may be a miniature bearing, wherein the dimensions of the bearing components may be a few millimeters to a few centimeters. Such a conical bearing system can be used for pivotal mounting of a spindle motor.

The two sealing gaps 40a and 40e For example, they have a typical gap width of xxx microns.

The two storage columns 40b and 40d have a typical gap width of, for example, xxx microns.

The separator gap 40c has a typical gap width of, for example, xxx microns.

Along the first and second sealing gaps 40a and 40e can pump groove structures 20 respectively. 22 be arranged, which the sealing effect in the sealing gaps 40a and 40e support.

The pump groove structures 20 and 22 are designed such that they have a pumping action in the direction of the respective bearing gaps during operation of the bearing system 40b and 40e generate and thus keep the bearing fluid active in the storage system.

The pump groove structures 20 respectively. 22 can both on the sections 10a . 10e the wave 10 as well as on the corresponding sections of the first bearing component 24 or the second bearing component 32 be arranged or both on the shaft 10 as well as on the two bearing components 24 . 32 ,

When mounting the storage system, the two bearing components 24 . 32 each slipped over the shaft and connected to each other at their contact surfaces, for example by welding or gluing.

For the axial and radial positioning of the bearing components with respect to the axis of rotation 50 the while 10 has the first bearing component 24 a determining surface 30 and the second bearing component 32 a determining surface 38 on.

These determining surfaces 30 . 32 are highly accurately machined and adapted to each other and determine both the concentricity of Lagerbautele 24 . 32 as well as the axial play of the shaft 10 within the interconnected bearing components 24 . 32 ,

For exact definition of the two bearing components 24 . 32 can also be a cylindrical housing surrounding the bearing components 44 be used.

The housing 44 is on both sides by appropriate cover plates 46 . 48 locked.

In the storage system according to 1 Both conical fluid dynamic bearings use a common bearing fluid system, with the bearing only at the end sections 10a and 10e the wave 10 by means of sealing gaps 40a and 40e is sealed.

2 shows a modified embodiment of the invention, in which the same components are designated by the same reference numerals.

In contrast to 1 are in 2 the two conical fluid dynamic bearings separated from each other and each have their own storage fluid system.

The bearing component 124 has a circumferential groove 52 which is not filled with bearing fluid and thus separates fluid circuit of the upper bearing from the lower bearing.

Here, the Separatorspalt 40c divided into two sections, each section as a sealing gap 40c1 and 40c2 is trained.

Along this sealing gap 40c1 and 40c2 can corresponding pump groove structures 54 . 56 be arranged, which the sealing effect of the sealing gaps 40c1 and 40c2 support.

In the groove 52 no bearing fluid is arranged, but the groove is to avoid negative pressure preferably ventilated and connected to the outside atmosphere. For example, in the wave 10 an axial bore 58 is arranged, the height of the groove 52 a transverse bore 160 having the groove 52 with the axial bore 58 and thus the outside atmosphere connects.

A great advantage of the storage system according to the invention is the ease of assembly and the simple adjustment of the bearing clearance, which is independent by appropriate accurate machining and alignment of the bearing components 24 . 32 results.

When assembling therefore no high-precision device for pressing on bearing cones in a corresponding distance on the shaft is necessary, but the two bearing components 24 . 32 the present bearing have corresponding fits that ensure the specified bearing clearance after joining the bearing components.

LIST OF REFERENCE NUMBERS

10

wave

10a

end

10b

conical section

10c

middle section

10d

conical section

10e

end

12

storage area

14

Bearing groove structures

14a

raceways

14b

raceways

16

storage area

18

Bearing groove structures

18a

raceways

18b

raceways

20

Pumping groove structure

22

Pumping groove structure

24, 124

first bearing component

26

bearing bore

28

Thrust face

30

Bestimmfläche

32

second bearing component

34

bearing bore

36

Thrust face

38

Bestimmfläche

40

gap

40a

seal gap

40b

bearing gap

40c

separator gap

40d

bearing gap

40e

seal gap

40c1

seal gap

40c2

seal gap

44

casing

46

cover disc

48

cover disc

50

axis of rotation

52

groove

54

Pumping groove structure

56

Pumping groove structure

58

drilling

60

drilling

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2004/0005101 A1 [0002]
• US 2007/0252461 A1 [0007]

Claims (11)

A conical fluid dynamic bearing system comprising a first conical fluid dynamic bearing and a second conical fluid dynamic bearing counteracting the first conical bearing, wherein the first and second conical fluid dynamic bearings are disposed along a shaft (Fig. 10 ) are arranged and in each case a conical bearing surface ( 12 ; 16 ) and a conical abutment surface ( 28 ; 36 ) defined by a bearing gap filled with a bearing fluid ( 40 ) are separated, wherein the two conical bearing surfaces ( 12 ; 16 ) as part of the wave ( 10 ) are formed, and the first conical abutment surface ( 28 ) on a first bearing component ( 24 ; 124 ) and the second conical abutment surface ( 36 ) on a second bearing component ( 32 ), characterized in that the two bearing components ( 24 . 32 ; 124 ) are designed and mounted so that they align themselves radially and axially to each other. Conical fluid dynamic bearing system according to claim 1, characterized in that the two bearing components ( 24 ; 32 ; 124 ) Determining surfaces ( 30 . 38 ) for mutual alignment. Conical fluid dynamic bearing system according to claim 1 or 2, characterized in that the two bearing components ( 24 ; 32 ; 124 ) inclined surfaces ( 30 . 38 ) for mutual alignment. Conical fluid dynamic bearing system according to one of claims 1 to 3, characterized in that on the bearing surfaces ( 12 . 16 ) and / or the abutment surfaces ( 28 . 36 ) Bearing groove structures ( 14 . 18 ) are arranged. Conical fluid dynamic bearing system according to one of claims 1 to 4, characterized in that the first and the second conical fluid dynamic bearing are fluid-dynamically connected to each other by a gap filled with a bearing fluid. Conical fluid dynamic bearing system according to one of claims 1 to 4, characterized in that the first and the second conical fluid dynamic bearing are fluid-dynamically separated from each other by a gap filled with air. Conical fluid dynamic bearing system according to one of claims 1 to 6, characterized in that on the smallest diameter of the shaft ( 10 ) at least one pumping seal ( 20 . 22 ) is arranged, which conveys the bearing fluid in the direction of the conical bearing. Conical fluid dynamic bearing system according to one of claims 1 to 7, characterized in that on the largest diameter of the shaft ( 10 ) at least one pumping seal ( 54 . 56 ) is arranged, which conveys the bearing fluid in the direction of the directly adjacent conical bearing. Spindle motor with a conical fluid-dynamic bearing system according to one of claims 1 to 6. Hard disk drive with a spindle motor according to claim 7. Fan with a spindle motor according to claim 7.

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