DE102015012664A1 - Fluid dynamic storage system - Google Patents

Abstract

Fluid dynamic bearing system with at least one stationary bearing component with conical bearing surfaces and at least one rotating about a rotation axis bearing member with conical bearing surfaces, wherein the bearing surfaces of the two bearing components are separated by at least one bearing fluid filled with a bearing gap, characterized in that the fixed bearing member at least one fixed Bearing bush and the rotatable bearing member having a shaft and at least one attached to the shaft or integrally formed with the shaft bearing component.

Description

Field of the invention

The invention relates to a fluid dynamic bearing system according to the preamble of claim 1. Such a bearing system is used, for example, for the rotary mounting of a spindle motor for driving hard disk drives.

Description of the Prior Art

As a pivot bearing in spindle motors, as z. B. are used to drive the disks in hard drives, mostly fluid dynamic storage systems are used. Fluid dynamic bearing systems are further developed plain bearings. Various types of fluid dynamic bearing systems are known, for example as a combination of fluid dynamic radial bearings and axial bearings or as conical fluid dynamic bearing systems.

Conical fluid dynamic bearing systems can absorb higher forces compared to bearing systems with radial and thrust bearings and are therefore well suited for applications with high load.

A conical fluid dynamic bearing system is in the US 6,911,748 B2 disclosed. There are two contra-rotating conical fluid dynamic bearings provided. The two conical bearings are symmetrical. The bearing described has a fixed shaft. Since the shaft is fixed and thus the bearing or the bearing gap is open on both sides of the bearing, the shaft can be attached to a housing at both ends, which improves the rigidity of the bearing relative to a shaft fixed only on one side. Such a conical fluid dynamic bearing system is very well suited for the pivot bearing of high loads. Each conical bearing has a bearing cone arranged on the 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 ends, each open end being sealed by a sealing gap. If the bearing is used, for example, for the rotary mounting of a spindle motor, a first end of the shaft is usually firmly received in a base plate and a second shaft end in an upper cover of the spindle motor.

In the storage system described above, however, can occur too high differential pressure, for example, when cleaning the engine with pressure or under pressure to loss of oil. To counteract this problem, it is advantageous if a fluid-dynamic bearing system with a rotating shaft and a fixed bearing bush is used for the rotary mounting of the spindle motor. A high load capacity of the storage system is necessary, for example, in hard disk drives with five or more disks, which are mounted on the rotor of the spindle motor and driven by this rotating. So far, such a heavy-duty bearing system with rotating shaft for spindle motors was not available.

Disclosure of the invention

It is the object of the invention to provide a fluid dynamic bearing system with a rotating shaft for pivotal mounting of a spindle motor, which is designed for high loads.

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

Preferred embodiments of the storage system according to the invention and further advantageous features of the invention are specified in the dependent claims.

The fluid-dynamic bearing system comprises at least one stationary bearing component with conical bearing surfaces and at least one bearing component rotatable about an axis of rotation with conical bearing surfaces, the bearing surfaces of the two bearing components being separated from one another by at least one bearing gap filled with a bearing fluid.

According to the invention, the stationary bearing component has at least one stationary bearing bush and the rotatable bearing component has a shaft and at least one bearing component fastened to the shaft or integrally formed with the shaft.

The invention is based on a conical fluid dynamic bearing system with rotating shaft, as it was not previously known.

In a rotating shaft design, there is less risk of pressure differential (inside the bearing) compared to a fixed shaft bearing system.

Preferably, the bearing bush is held in a recess in a base plate.

Due to the closed bottom of the storage system, measures for ventilation of the remaining cavities and spaces are necessary.

For this purpose, the shaft can preferably have a longitudinal bore and at least one transverse bore branching off from it, via which at least one air-filled intermediate space of the bearing is connected to the outside atmosphere.

In a preferred embodiment of the invention, the shaft has a longitudinal bore and two transverse bores branching off therefrom, wherein the longitudinal bore opens into a lower intermediate space, which is partially bounded by the base plate. One of the two transverse bores preferably opens into a central intermediate space, which is delimited by the shaft and the bearing bush, while the other transverse bore preferably opens into an upper intermediate space, which is partially bounded by a hub fixed to the shaft and connected to the outside atmosphere , Thus, the lower and the middle space are connected via the longitudinal bore and the transverse bores with each other and with the upper space and thereby also with the outside atmosphere.

In a further preferred embodiment of the invention, the shaft has a longitudinal bore and a transverse branching off therefrom, wherein the longitudinal bore opens into a lower intermediate space, which is partially bounded by the base plate and the transverse bore opens into a central intermediate space of the shaft and the Bearing bush is limited. The base plate preferably has a bore opening into the lower intermediate space, via which the lower intermediate space is connected to the outer atmosphere. Thus, the lower and the middle space are connected via the longitudinal bore and the transverse bore with each other and via the bore in the base plate also with the outside atmosphere.

In a further preferred embodiment of the invention, the shaft also has a longitudinal bore and a transverse bore branching off from it, via which the lower and the middle intermediate space are connected to one another. Preferably, the bearing bush here has a bore opening into the middle gap, via which the middle space is connected to the outside atmosphere. As a result of the connection between the middle and the lower intermediate space, the lower intermediate space is also connected to the outer atmosphere.

In a further preferred embodiment of the invention, the shaft again on a longitudinal bore and a branching off transverse bore, via which the lower and the middle gap are interconnected. Preferably, a channel opening into the lower intermediate space is arranged between the base plate and the bearing bush, which channel is formed either in the base plate and / or the bearing bush, and via which the lower intermediate space is connected to the outer atmosphere. As a result of the connection between the middle and the lower intermediate space, the lower intermediate space is also connected to the outer atmosphere.

Preferably, the longitudinal bore of the shaft is formed as a blind hole.

Alternatively, the bore may also be formed as a through-hole, whereby the longitudinal bore and all intermediate spaces connected directly or via transverse bores with the longitudinal bore are connected to the outside atmosphere.

All embodiments of the invention described above can also be combined with each other as desired.

Additionally or alternatively, the base plate of the spindle motor and / or the bushing may have suitable holes for ventilation of one or more interconnected spaces.

It can also be provided that the longitudinal and transverse bores in the shaft completely eliminated, and the ventilation of the interstices takes place only through holes in the base plate and / or the bearing bush.

The fluid-dynamic bearing system described can preferably be used for the rotary mounting of a spindle motor, as used for example for driving hard disk drives or fans use.

Further features and advantages of the invention will become apparent from the drawings and the following description of preferred embodiments.

Brief description of the drawings

1 shows a section through a spindle motor with a fluid dynamic bearing system according to the invention.

2 shows a section of the fluid dynamic storage system of 1 according to a first modified embodiment.

3 shows a section of the fluid dynamic storage system of 1 according to a second modified embodiment.

4 shows a section of the fluid dynamic storage system of 1 according to a third modified embodiment.

Description of preferred embodiments of the invention

The 1 shows a section through a spindle motor with a fluid dynamic bearing system consisting of two conical fluid dynamic bearings.

The spindle motor comprises a base plate 10 as a load-bearing structure, which has a cylindrical recess through a raised edge 10a is formed. The base plate 10 is closed in the area of the recess on the bottom side. In the recess of the base plate 10 is a bearing bush 16 arranged. The bearing bush is preferably by means of a press connection and / or adhesive connection in the recess of the base plate 10 fastened, such that the lower end face of the bearing bush 16 the surface of the base plate 10 not touched and a gap 28 between bearing bush 16 and base plate 10 remains. The bearing bush 16 is largely on the surface of the base plate 10 out and forms the fixed bearing component of the storage system.

In a bearing bore of the bearing bush 16 the rotatable bearing component of the storage system is arranged. The rotatable bearing component comprises a rotating shaft 12 , at the two storage cones 14 . 114 are attached. The storage cones 14 . 114 are at an axial distance from each other on the shaft 12 arranged and firmly connected with this. The storage cones 14 . 114 have facing each other, at an acute angle oblique to the axis of rotation 44 extending conical bearing surfaces.

The bearing bore of the bearing bush 16 has corresponding conical bearing surfaces, which are the bearing surfaces of the Lagerkonusse 14 . 114 assigned. The storage areas of the storage cones 14 . 114 and the associated bearing surfaces of the bearing bush 16 are each by a filled with a bearing fluid bearing gap 20 . 120 separated from each other.

Every storage bonus 14 . 114 comprises on its bearing surface distributed over the circumference a number of bearing grooves. The bearing grooves are inclined at an acute angle to the direction of rotation and arranged for example in a known herringbone pattern (herringbone). The bearing grooves do not have to be on the bearing surface of the bearing cones 14 . 114 can be arranged, but also on the opposite conical bearing surfaces of the bearing bush 16 or be arranged on both components. Upon rotation of the shaft 12 and the storage cones 14 . 114 The bearing grooves create a pumping action on the in the bearing columns 20 . 120 located bearing fluid. Both branches of the bearing grooves thereby generate a pumping action, in the direction of the other branch, ie to the center of the conical bearing, whereby the bearing is sustainable. The branch of the bearing grooves, which is arranged closer to the end of the shaft, thereby generates a somewhat stronger pumping action, so that a flow of the bearing fluid in the direction of the shaft center, ie the interior of the storage system adjusts.

The storage cones 14 . 114 are relative to the bearing bush 16 arranged so that the bearing column 20 . 120 at room temperature have a defined gap width of a few micrometers. The load-bearing capacity of the conical bearings depends, among other things, on the gap width of the bearing gaps 20 . 120 and the viscosity of the bearing fluid contained therein.

Every storage gap 20 . 120 has two open ends, which are sealed by sealing gaps. The outer ends of the bearing gaps 20 . 120 are each by outer capillary sealing gaps 22 . 122 sealed by an outer peripheral surface of the associated bearing cone 14 . 114 and an inner peripheral surface of frontal edges 16a the bearing bush 16 be limited. The outer sealing gaps 22 . 122 form with the associated bearing gap 20 . 120 an obtuse angle and with the axis of rotation 44 an acute angle. The sealing column 22 . 122 are partially filled with bearing fluid and acts as a fluid reservoir and compensating volume at temperature expansion of the bearing fluid. Preferably, both are the sealing gaps 22 . 122 delimiting surfaces starting from the bearing gap 20 . 120 to the bearing outer by a small angle of between 0.5 degrees and 20 degrees in the direction of the axis of rotation 44 inclined, wherein the inclination angle of the inner peripheral surface of the edges 16a the bearing bush 16 is smaller by a few degrees than the angle of inclination of the outer peripheral surfaces of the Lagerkonusse 14 . 114 , resulting in a conical cross section of the outer sealing gaps 22 . 122 results.

The storage system interior facing the ends of the bearing column 20 . 120 are through inner sealing gaps 24 . 124 sealed by corresponding portions of the outer peripheral surface of the shaft 12 and the inner peripheral surface of the bearing bush 16 are limited. Along each sealing gap 24 . 124 is preferably a dynamic pumping seal 25 . 125 and a conical capillary seal arranged. The pump seals 25 . 125 include pump groove structures that are either on the shaft 12 and / or on the bearing bush 16 along the sealing gap 24 . 124 are applied, wherein the pump groove structures upon rotation of the shaft 12 a pumping action on the in the sealing gaps 24 . 124 bearing fluid in the direction of the bearing gap 20 . 120 generate, that is opposite to the pumping action generated by the outer branches of the conical bearing. In every storage bonus 14 . 114 is at least one recirculation channel 26 arranged, through which a circulation of the Storage fluids within storage gap 20 . 120 the conical bearing is possible.

The upper sealing gap 22 forms the outer boundary of the fluid dynamic bearing system. So that no impurities in the sealing gap 22 can penetrate and excessive escape of on the surface of the sealing gap 22 evaporating bearing fluid is prevented, the upper conical fluid dynamic bearing beyond the sealing gap 22 through a cover 18 covered.

The cover 18 For example, is formed as a stamped or turned part in the form of a profiled sheet metal ring having an outer edge, which on the upper edge 16a the bearing bush 16 plugged or pressed on and possibly additionally glued there. The cover 18 extends radially inward in the direction of the shaft 12 and forms with the outer circumference of the shaft 12 a narrow air gap, allowing excessive evaporation of bearing fluid from the area of the outer sealing gap 22 is prevented.

The lower end of the bearing, through the lower sealing gap 122 is sealed, lies in the closed recess of the base plate 10 , whereby vaporized bearing fluid can not escape and no particles can penetrate from the outside.

The bearing bush 16 may preferably be made of steel, ceramic or the like, in particular of a material with a small coefficient of thermal expansion, while a hub fixed to the shaft 34 For example, made of aluminum, so a material with a comparatively large coefficient of thermal expansion and is used to hold several storage disks, which also consist of aluminum in this case. Alternatively, the hub 34 be made of steel, especially if the storage plates are made of glass.

The spindle motor is driven by an electromagnetic drive system, which consists of one on the base plate 10 attached stator assembly 36 and one opposite the stator assembly 36 at the hub 34 attached rotor magnet 38 which is located radially from a ferromagnetic inference 40 is surrounded.

Due to the design of the storage system and the open ends of the bearing gaps 20 . 120 or sealing gaps 22 . 122 . 24 . 124 the storage system has several spaces filled with air 28 . 30 . 32 connected to each other as well as to the outside atmosphere to provide pressure equalization between the respective areas of the warehouse and the environment.

Above the cover 18 The upper bearing is a space filled with air 32 between the cover 18 or bearing bush 16 and the hub 34 arranged over the stator space 46 , in which the stator is located, and a gap between the base plate 10 and hub 34 connected to the outside environment.

The wave 12 has a longitudinal bore 12a on, as a blind hole from the bottom of the shaft 12 over much of the length of the shaft 12 goes up. Over an upper cross bore 12b in the wave 12 is the longitudinal bore 12a with the gap 32 and thus connected to the outside atmosphere.

The two conical fluid dynamic bearings are through an air-filled space 30 separated from each other. The gap 30 is between the outer circumference of the shaft 12 and the bearing bush 16 formed and over another transverse bore 12b with the longitudinal bore 12a and thus also connected to the outside atmosphere.

The lower opening of the longitudinal bore 12a connects a lower gap 28 between the top of the base plate 10 and the lower end of the bearing bush 16 , the wave 12 and the lower storage cone 114 with the other spaces 30 . 32 and the outside atmosphere.

The inventive design of the bearing system with rotating shaft 12 makes it possible to realize a spindle motor which can absorb high loads and which reduces the risk of pressure differences within the bearing. Below the hub 34 is sufficient space for the electromagnetic drive system, wherein the stator assembly 36 and the rotor magnet 38 are arranged axially between the two conical fluid dynamic bearings. As a result, the line of action of the driving force of the drive system is close to the center of gravity of the rotating engine component.

The ventilation of the interstices 28 . 30 . 32 In the storage system according to the invention can be solved in a different way than it is in 1 is shown.

For example, according to 2 the wave 12 a longitudinal bore 12a have, from the lower end side to the height of the middle space 30 between the conical bearings, with the middle gap 30 over the cross hole 12b with the longitudinal bore 12a connected is.

The lower space 28 and the longitudinal bore 12a are over an additional hole 48 connected to the outside atmosphere. This additional hole 48 can in the base plate 10 be provided. The upper gap 32 is like in 1 shown over the stator space 46 and the gap between base plate 10 and hub 34 connected to the outside environment. The hole 48 can be closed again after mounting the bearing. This can happen with a so-called Dotseal. For this purpose, for example, an adhesive film on the underside of the base plate 10 attached, which then closes the opening.

Alternatively, according to 3 an additional hole 50 in the bearing bush 16 the middle space 30 with the stator space 46 and thus connect to the outside environment. The lower space is through the cross hole 12b and the longitudinal bore 12a the wave 12 with the middle gap 30 and ultimately connected to the outside environment.

In another embodiment of the invention according to 4 can be at least one channel 52 along the connection between the outer diameter of the bearing bush 16 and the wall of the recess of the base plate 10 be provided from the stator 46 down to the lower space 28 enough. The channel 52 can be used as a groove on the outer circumference of the bearing bush 16 and / or on the inner circumference of the base plate 10 be educated. The middle space 30 is over the cross hole 12b and the longitudinal bore 12a the shaft with the lower gap 28 and thus also with the stator space 46 and the outside environment connected.

The in the 2 to 4 shown methods of ventilation of the bearing have the advantage that the longitudinal bore 12a in the wave 12 compared to 1 can be made much shorter. This reduces production costs and saves costs. Further, the wave becomes 12 not weakened by drilling.

It can also be the methods of ventilation according to the 2 to 4 be combined with each other, so that in the best case, no longitudinal bore 12a and cross holes 12b in the wave 12 necessary.

LIST OF REFERENCE NUMBERS

10

baseplate

10a

edge

12

wave

12a

longitudinal bore

12b

cross hole

14, 114

bearing cone

16

bearing bush

16a

Edge of the bearing bush

18

cover

20, 120

bearing gap

22, 122

seal gap

24, 124

seal gap

25, 125

pump seal

26, 126

recirculation

28

gap

30

gap

32

gap

34

hub

36

stator

38

rotor magnet

40

conclusion

44

axis of rotation

46

stator

48

drilling

50

drilling

52

channel

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 6911748 B2 [0004]

Claims (12)

Fluid dynamic bearing system with at least one fixed bearing component ( 16 ) with conical bearing surfaces and at least one about an axis of rotation ( 44 ) rotatable bearing component ( 12 . 14 . 114 ) with conical bearing surfaces, wherein the bearing surfaces of the two bearing components ( 12 . 14 . 16 114 ) by at least one bearing gap filled with a bearing fluid ( 20 . 120 ) are separated from each other, characterized in that the fixed bearing component at least one stationary bearing bush ( 16 ) and the rotatable bearing component a shaft ( 12 ) and at least one mounted on the shaft or integrally formed with the shaft bearing component ( 14 . 114 ) having. Fluid dynamic bearing system according to claim 1, characterized in that the bearing bush ( 16 ) in a recess in a base plate ( 10 ) is held. Fluid dynamic bearing system according to one of claims 1 or 2, characterized in that the shaft ( 12 ) a longitudinal bore ( 12a ) and at least one transverse bore (FIG. 12b ), over which at least one, filled with air space ( 28 . 30 ) of the bearing is connected to the outside atmosphere. Fluid dynamic bearing system according to one of claims 1 to 3, characterized in that the shaft ( 12 ) a longitudinal bore ( 12a ) and two transverse bores branching off from them ( 12b ), wherein the longitudinal bore ( 12a ) in a lower intermediate space ( 28 ), partially from the base plate ( 10 ) is limited, and wherein the one transverse bore ( 12b ) into a middle space ( 30 ) coming from the wave ( 12 ) and the bearing bush ( 16 ) is limited, and wherein the other transverse bore ( 12b ) into an upper intermediate space ( 32 ), partly from one on the shaft ( 12 ) attached hub ( 34 ) is limited and connected to the outside atmosphere. Fluid dynamic bearing system according to one of claims 1 to 3, characterized in that the shaft ( 12 ) a longitudinal bore ( 12a ) and a transverse bore (FIG. 12b ), wherein the longitudinal bore ( 12a ) in a lower intermediate space ( 28 ), partially from the base plate ( 10 ) is limited and the transverse bore ( 12b ) into a middle space ( 30 ) coming from the wave ( 12 ) and the bearing bush ( 16 ) is limited. Fluid dynamic bearing system according to claim 5, characterized in that the base plate ( 10 ) one in the lower intermediate space ( 28 ) opening bore ( 48 ), over which the lower intermediate space ( 28 ) is connected to the outside atmosphere. Fluid dynamic bearing system according to one of claims 5 or 6, characterized in that the bearing bush ( 16 ) one in the middle space ( 30 ) opening bore ( 50 ), over which the middle space ( 30 ) is connected to the outside atmosphere. Fluid dynamic storage system according to one of claims 5 to 7, characterized in that between the base plate ( 10 ) and the bearing bush ( 16 ) into the lower space ( 28 ) opening channel ( 52 ) arranged either in the base plate ( 10 ) and / or the bearing bush ( 16 ) is formed, and, via which the lower intermediate space ( 28 ) is connected to the outside atmosphere. Fluid dynamic bearing system according to one of claims 1 to 8, characterized in that the longitudinal bore ( 12a ) the wave ( 12 ) is a blind hole. Spindle motor with a fluid dynamic bearing according to the features of claims 1 to 9. Hard disk drive, driven by a spindle motor according to claim 10. Fan driven by a spindle motor according to claim 10.

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