DE102016003269A1 - Fluid dynamic storage system - Google Patents

Abstract

The invention relates to a fluid-dynamic bearing system comprising a stationary bearing component comprising at least one shaft (12), a bearing component rotatable relative to the stationary bearing component about a rotation axis (16), comprising a hub (20) with at least one bearing bush (18). at least one bearing gap (26) which is open on both sides and filled with a bearing fluid and which separates the fixed and the rotatable position component, at least one capillary seal (28, 30) which is arranged at the ends of the bearing gap (26), at least one covering cap (26). 42) having an opening in the center, which has a radially extending portion (42 a) and an axially extending portion (42 b), wherein the inner periphery of the axially extending portion (42 b) on the outer periphery of the position sleeve (18) is fixed, wherein the radial extending portion (42a) of the cap (42) on its the capillary seal (28) facing side has a recess (44). According to the invention, it is provided that the opening of the capillary seal (28) and the recess (44) at least partially do not overlap in the radial direction. A variant of the recess (144 ') is arranged completely radially inwardly, so that the opening of the capillary seal (28) and the recess (144') do not overlap in the radial direction.

Description

Field of the invention

The invention relates to a fluid-dynamic bearing system, in particular a fluid-dynamic bearing system for pivotally mounting a spindle motor.

State of the art

Fluid dynamic bearing systems can be used for the rotational mounting of spindle motors, which drive for example hard disk drives or fans. The fluid dynamic bearing systems comprise at least one fixed and at least one rotatable bearing component. The two bearing components comprise bearing surfaces that are characterized by bearing groove structures and are separated by a bearing gap filled with a bearing fluid. Depending on the design, the bearing gap is open on one or both sides and, for example, sealed with capillary seals. In order to protect the openings of the capillary seals from contamination and to prevent leakage of bearing fluid from the bearing gap or the Kapillardichtungen, the openings may be additionally covered by a cap which is attached to either the fixed or rotatable motor component.

Upon rotation of the rotatable about the fixed bearing member, the bearing groove structures generate a pumping action on the bearing fluid in the bearing gap, whereby a hydrodynamic pressure is built up in the bearing gap, which makes the fluid dynamic bearing system sustainable. There are fluid dynamic radial bearings, fluid dynamic thrust bearings and fluid dynamic conical bearings. While in radial bearings, the bearing surface is parallel and axial bearing the bearing surface is aligned perpendicular to a rotation axis, the bearing surface is aligned obliquely to the axis of rotation in conical bearings. As a result, conical bearings can simultaneously absorb forces in the radial and axial directions.

The DE 10 2013 009 491 A1 discloses two spindle motors of different types and with different fluid dynamic storage systems for a hard disk drive. One variant shows a spindle motor with an ironic fluid dynamic bearing system. Here, two conical bearing components are arranged on a fixed shaft at an axial distance from each other, which form two conical bearings together with a rotating hub. In the region of each conical bearing component, a bearing gap opened on both sides is arranged, which is sealed at both ends by conical capillary seals. The capillary seals are covered by caps.

The other variant shows a spindle motor in which two fluid-dynamic radial bearings and a fluid-dynamic axial bearing are provided instead of the two conical bearings. A hub is rotatably mounted and disposed about a fixed shaft which is held in a fixed bearing member. Along the shaft, the two radial bearings are arranged at a distance from each other. The thrust bearing is disposed between the fixed bearing member and the hub. Between the rotating and the stationary components a bearing gap open on both sides is provided, which is sealed at both ends by conical capillary seals. On one side of the bearing, the capillary seals are covered by a cap. Shown are also different versions of caps. However, the space between the caps and the capillary seals is very low, so under shock, vibration or pressure differences bearing fluid escape from the capillary directions and can get directly through gaps between the caps and the shaft in the engine compartment.

The US 201310320793 A1 discloses a spindle motor of the above type, but with a bearing gap open on one side, which is sealed by a conical capillary seal. Over the axially extending capillary seal a cover is arranged. The cover has directly above the opening of the capillary seal on a recess in which collect from the capillary leaking bearing fluid and can flow back into the sealing gap. Beyond the recess, the gap between cover and the opposite bearing component narrows again, so that it can be assumed that bearing fluid emerging from the capillary seal into the recess is drawn by capillary action into the narrow gap and remains there, instead of flowing back into the capillary seal ,

Disclosure of the invention

It is the object of the invention to specify a fluid-dynamic bearing system in which leakage of bearing fluid from the region of the capillary seals due to external shock, vibrations or pressure differences is prevented or at least made more difficult.

This object is achieved by a fluid dynamic bearing system having the features of the independent claim.

The fluid-dynamic bearing system comprises a stationary bearing component, comprising at least one shaft, a bearing component rotatable about a rotation axis relative to the stationary bearing component, consisting of a hub with at least one a bearing bush, at least one with a bearing fluid filled, open on both sides bearing gap, which separates the fixed and the rotatable support member, at least one capillary seal, which is arranged at the ends of the bearing gap, and at least one cap with an opening in the middle, the one radially extending portion and having an axially extending portion, wherein the inner periphery of the axially extending portion is fixed to the outer periphery of the insertion sleeve, wherein the radially extending portion of the cap on the conical capillary seal facing side has a recess.

According to the invention, the recess is arranged such that the opening of the capillary seal and the recess in the radial direction at least partially do not overlap.

This recess minimizes the risk of bearing fluid escaping from the capillary seal under shock, pressure differentials or vibrations and entering the engine compartment directly through the gap between the cap and the shaft, as any escape of bearing fluid from the capillary seal will trap it in the recess , The stored in the recess bearing fluid can then flow back into the capillary seal.

In an advantageous embodiment of the invention, the recess is arranged at least partially radially further inward lying to the opening of the capillary seal, so extends radially further inward in the direction of the axis of rotation than the opening of the capillary seal. This prevents bearing fluid from getting caught between the top of the rotatable bearing member and the underside of the cap and will not flow back into the capillary seal.

Preferably, the surfaces of the rotatable bearing component, in particular the surfaces of the cap, which are not to be wetted by bearing fluid, coated with a suitable oil stop or barrier film.

According to another preferred embodiment of the invention, the recess is arranged completely radially inwardly to the opening of the capillary seal, so that the opening of the capillary seal and the recess do not overlap in the radial direction.

The region of the opening of the capillary seal is connected in this case only by a radially inwardly extending gap with the recess.

The cap covers the opening of the capillary seal at a small distance. The annular gap forms a constriction between the opening of the capillary seal and the recess of the cap. Due to the gap as constriction, it is difficult for the bearing fluid emerging from the capillary seal to reach the region of the recess at all. Rather, the bearing fluid will largely immediately flow back into the capillary seal. This is further supported by the fact that preferably the mutually facing surfaces of the fixed bearing component and / or the cap are coated with a barrier film or an oil stopper. As a result, the bearing fluid can not adhere to these surfaces and flows more easily again.

In a preferred embodiment, the recess is rectangular in cross section.

In another preferred embodiment, the recess is approximately triangular in cross-section and has a slope on the wall facing the shaft, while the wall facing away from the shaft of the recess extends parallel to the axis of rotation. As a result, a relatively large clearance is created above the capillary seal, which can absorb escaping bearing fluid.

In a further embodiment of the invention, the recess in cross-section is approximately triangular. Here, the wall facing away from the shaft of the recess may have a slope, while the wall facing the shaft of the recess is parallel to the axis of rotation. The triangular cross-section and the radially outwardly sloping wall of the recess promote backflow of the bearing fluid from the recess into the capillary seal by means of the centrifugal force acting radially outwardly on the bearing fluid which rotates together with the cap. The centrifugal force conveys the bearing fluid adhering to the cap along the slope of the recess radially outward, where it can then run back into the capillary seal. Furthermore, the triangular cross-section acts as a capillary seal which conveys the bearing fluid radially outward even when the engine is at a standstill.

In a further embodiment, the recess may have a bevel on the side facing the shaft and on the side facing the bearing bush, so that a trapezoidal, wedge-shaped or triangular cross-section of the recess results.

Preferably, an axially extending portion is disposed on the radially inner side of the radially extending portion of the cap, which extends opposite to the direction of the axially extending portion of the cap. The inner circumference of this axially extending portion runs at a small distance along and parallel to Shaft or the fixed bearing component and forms a gap seal. Between the inner circumference of the cap and the outer periphery of the shaft, a narrow, axially extending air gap in the form of a gap seal is preferably arranged, which ensures that evaporated bearing fluid can not or only very difficult to escape from the camp.

Preferably, the fixed position component next to the shaft on a first and a second bearing component, both of which are arranged on the shaft.

In a preferred embodiment of the invention, at least one fluid-dynamic radial bearing between the shaft and the bearing bush and at least one fluid-dynamic thrust bearing between the bearing bush and one of the bearing components is provided.

In another preferred embodiment of the invention, the outer circumference of the first and second bearing component is conical, wherein the two bearing components together with respective opposite bearing bushes form two fluid-dynamic conical bearings.

The fluid-dynamic bearing system according to the invention can preferably be used for the rotary mounting of a spindle motor, which can be used by means of an electromagnetic drive system for driving, for example, hard disk drives, optical drives, fans or laser scanners.

The invention will be described in more detail below with reference to preferred embodiments with reference to the drawing figures. This results in further features and advantages of the invention.

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 through the spindle motor 1 with another embodiment of the caps.

3 shows a section through a spindle motor in a different type, as the spindle motor 1 ,

4 shows an enlarged section of the spindle motor of 1 in a modified embodiment of the invention.

5 shows an enlarged section of the spindle motor of 2 in a modified embodiment of the invention.

Description of preferred embodiments of the invention

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

A base plate 10 has a blind hole in which a fixed shaft 12 is arranged. The wave 12 For example, in the base plate 10 be pressed. For a lubricant in the inner diameter of the blind hole of the base plate 10 applied and then the shaft 12 pressed. As a lubricant, for example, IPA or adhesive can be used. Adhesive has the advantage over IPA that the dosage can be very accurate and the connection of shaft 12 and base plate 10 is stronger, because in addition to the press connection still exists an adhesive bond. At the wave 12 are bearing components 14 arranged with conical bearing surfaces at an axial distance from each other. The base plate 10 , the wave 12 and the two bearing components 14 form the stationary component of the spindle motor. Opposite the bearing components 14 are about a rotation axis 16 rotatable bearing bushes 18 arranged, which can be made for example of steel and have a bore and in each case an end-side hollow-cone-shaped recess in which the shaft 12 and the two bearing components 14 are included. The axial relative movement of the bearing bushes 18 to the fixed component, the so-called axial play, can be between 10 and 20 microns, for example 14 microns. A hub 20 may be made of aluminum, for example, and is with the bushings 18 rotatably connected. Between the bushings 18 is a gasket 22 arranged, which may for example be made of hard rubber, which protects the bearing from external influences and also serves as a compensating element for axial movements due to thermal expansion. The bearing bushes 18 , the hub 20 and the sealing washer 22 together form the rotating component of the spindle motor. The bearing surfaces of the bearing components 14 form together with opposite bearing surfaces of the bearing bushes 18 the conical bearings 24 ,

The bearing components 14 extend in the region of the conical bearing surfaces viewed from their side facing the center of the bearing in the direction of the bearing outer at an acute angle, for example, 30 ° obliquely outwards. This surface has a very large radius of, for example, 250 millimeters, which is referred to as "crowning" and thereby ensuring that the surfaces of the bearing bushes 18 and the bearing components 14 can not get stuck in this area. Alternatively or additionally, this radius can also be in the respective opposite surfaces of the bearing bushes 18 be provided. The bearing bushes 18 and / or the bearing components 14 have herringbone-shaped Lagerrillenstrukturen on exercise of the storage system pumping action on the bearing fluid in the direction of the apex, ie about the central region of the bearing grooves exert, so that the conical bearing 24 become sustainable. Since the bearing outer facing branches of herringbone-shaped bearing grooves that exert a pumping action in the direction of the bearing interior on the bearing fluid during rotation of the bearing, are designed to be longer than the inside of the bearing facing branches of herringbone bearing grooves that carry the bearing fluid toward the bearing outer, and above In addition, the branches facing the bearing outer are arranged on a relatively larger radius, the pumping action predominates on the bearing fluid, which is directed into the bearing interior. This results in a resulting pumping direction in the direction of the bearing center.

Opposing surfaces of the bearing bushes 18 and the wave 12 as well as the bearing components 14 , which can touch at a standstill or low speeds, are filled with a bearing fluid bearing gap 26 separated from each other. The ends of the bearing column 26 are by with at least partially filled with bearing fluid Kapillardichtungen 28 . 30 sealed. An axial section of the bearing gap 26 runs between the shaft 12 and the bushings 18 while a sloping section between the bearing components 14 and the bushings 18 runs.

The outer capillary seals 28 are at the end of the bearing column 26 arranged facing the bearing exterior, and are limited by outer peripheral surfaces of the bearing components 14 and inner peripheral surfaces of the bushings 18 , The capillary seals 28 delimiting surfaces extend slightly inwardly in the direction of the bearing outer to the axis of rotation 16 , The angle of inclination of the surfaces of the bearing bushes 18 is less than that of the bearing components 14 , resulting in a conical cross section.

The inner capillary seals 30 are at the end of the camp column 26 arranged facing the bearing interior, and are limited by the outer peripheral surface of the shaft 12 and inner peripheral surfaces of the bushings 18 , The capillary seals 30 delimiting surfaces extend to the bearing interior initially parallel to the axis of rotation 16 and then have a slope away from the axis of rotation 16 on, making the end of the capillary seals 30 has a conical cross section. The gap width of the capillary section of the capillary seals 30 is equal to the gap width of the radial bearing gaps 26 , Along this section are pump seals 32 arranged, which include pumping structures which have a pumping action on the bearing fluid in the direction of the conical bearing 24 produce.

Between the camp columns 26 and the outer capillary seals 28 are annular grooves 34 provided perpendicular to the axis of rotation 16 are arranged, which serve as additional reservoirs for the bearing fluid, whereby the life of the bearing is increased. In addition, these grooves protect 34 the bearing in front of the capillary seals 28 penetrating air. The grooves 34 For example, in the inner peripheral surfaces of the bushings 18 maschiniert.

Between the inner capillary seals 30 there remains an air gap 36 from the outer circumference of the shaft 12 , the inner peripheral surfaces of the bushings 18 as well as the inner circumference of the sealing disc 22 is limited. A balancing hole in the shaft 12 longitudinally parallel to the axis of rotation (not shown in the drawing), in conjunction with perpendicular compensation marks 38 for a pressure equalization between this air gap 36 and the environment and ensures that during the crimping of the shaft 12 in the base plate 10 the air in the blind hole can escape.

To the circulation of the bearing fluid in the bearing gaps 26 ensure are in the bearing components 14 at least one, but preferably two opposing recirculation channels 40 intended. The ends of the recirculation channels 40 open on one side in the areas of the camp column 26 in which the axial sections merge into the oblique sections. From there, the recirculation channels run 40 as axial extensions of the axially extending portions of the bearing gaps 26 between the bearing components 14 and the wave 12 , then bend obliquely outwards and run at an angle less than 90 ° to the axis of rotation 16 through the bearing components 14 , Their ends open into the grooves on this side 34 , The axially extending parts of the recirculation channels 40 that between the shaft 12 and the bearing components 14 run, for example, by means of ECM in the bearing components 14 and / or the wave 12 be incorporated.

At the bearing bushes 18 are on the outside of the bearing caps 42 attached, which together with the bearing bushes 18 around the shaft 12 rotate and the outer capillary seals 28 cover. The caps 42 each have a radially extending portion 42a and an axially extending portion 42b on. The inner circumference of the axially extending portion 42b of the caps 42 lies on the outer circumference of the bearing bushes 18 on, and a part of the radially extending portion 42b the caps 42 lies with his capillary seal 28 facing side on the front side of the bearing bushes 18 on. In the capillary seal 28 facing side of the radially extending portion 42a the caps 42 are recesses 44 arranged in the form of an annular groove. The recesses 44 have a rectangular cross-section and the the recesses 42 delimiting surfaces are parallel or perpendicular to the axis of rotation 16 , The recesses 44 propagate outward in the radial direction to approximately the outer boundary surfaces of the outer capillary seals 28 out. Between the outer peripheral surface of the shaft 12 and the inner peripheral surfaces of the cover caps 42 remain narrow air gaps, the so-called gap seals 46 forming and evaporating the bearing fluid from the bearing gaps 26 or the outer capillary seals 28 minimize. The recesses 44 In the event of shock, vibration or pressure differences, they may be used in the capillary seals 28 catch escaping bearing fluid, so this does not have the gap seals 46 gets into the engine compartment.

The radial section 42a the cap 42 on the side of the base plate 10 is arranged, can be made smaller in axial extent than the radial portion 42a the cap 42 on the other side of the camp.

The hub 20 is preferably made of aluminum and has an edge, at the inner diameter of a magnetic yoke 48 for a rotor magnet 50 is attached. The rotor magnet 50 encloses a stator assembly 52 concentric to the base plate 10 is attached. The at the base plate 10 fixed stator arrangement 52 forms with the rotor magnet 50 and the magnetic inference 48 the electromagnetic drive system of the spindle motor.

In the embodiment shown here, hub and bearing bush are two separate components made of different materials. Hub and bearing bush can also be integrally formed (not shown in the drawing) and be made for example of steel. In this case, can be dispensed with the magnetic return of the electromagnetic drive system.

2 shows a section through the engine 1 with another embodiment of the caps 142 , Like the caps 42 out 1 show a radial section 142a , an axial section 142b and an annular recess 144 on. The recess 144 is on the side of the radial section 142a arranged the outer capillary seals 28 opposite. The recess 144 has no rectangular, but a trapezoidal cross-section. The radially outer boundary surface runs parallel to the axis of rotation 16 while the radially inner boundary surface has a slope. The slope may be an angle between 20 ° and 60 °, for example 35 °, perpendicular to the axis of rotation 16 exhibit.

The radial section 142a the cap 142 which is located on the side of the bearing farther from the base plate 10 is, can be made larger in the axial direction than the radial portion 142a the cap 142 lying on the side of the bearing near the base plate 10 is arranged.

Furthermore, on the radially inner side of the radial section 142a an axial attachment 142c provided opposite to the direction of the axial section 142b runs. Through the essay 142c becomes the gap seal 46 that between wave 12 and cap 142 is formed, extended in the axial direction, which improves their function.

3 shows a spindle motor with a fluid dynamic bearing system of another type without tapered bearings.

The spindle motor comprises a base plate 110 having a substantially central cylindrical opening in which a fixed first bearing member 116 is included. The bearing component 116 can with the base plate 110 be electrically connected by means of an electrically conductive adhesive. The first bearing component 116 is approximately pot-shaped and comprises a central opening in which the shaft 112 is pressed. As a lubricant for the joining process, for example, adhesive can be used, whereby the press connection is additionally strengthened by the adhesive bond. At the free end of the fixed shaft 112 is an annular second bearing component 118 Arranged on the shaft 112 attached or in one piece with the shaft 112 is trained. The named components 110 . 112 . 118 and 118 form the fixed bearing component of the spindle motor. The wave 112 has at its upper end preferably a threaded bore (not shown in the drawing), which is used to attach the shaft 112 on a housing cover of the spindle motor or the hard disk drive is used.

The fluid dynamic bearing system comprises a hub 114 with a one-piece integrated bearing bush 114a in one by the shaft 112 and the two bearing components 116 . 118 formed intermediate space is rotatably arranged relative to these components. The upper bearing component 118 is in one annular recess of the bearing bush 114a arranged at the radially outer edge of a peripheral circumferential groove 117 is arranged, which improves the adhesion of the fluid dynamic bearing under vibration. Adjacent surfaces of the shaft 112 , the bearing bush 114a and the two bearing components 116 . 118 , which can touch each other at standstill, low speeds or vibrations, are characterized by a bearing gap open on both sides 120 separated from each other, which is filled with a bearing fluid, such as a bearing oil. The electromagnetic drive system of the spindle motor is formed in a known manner by a on the base plate 110 arranged stator arrangement 146 and a stator assembly 146 at a distance concentrically surrounding, annular permanent magnet 148 attached to an inner circumferential surface of the hub 114 is arranged.

The bearing bush 114a has a cylindrical bore, on whose inner circumference two cylindrical radial bearing surfaces are formed, which through an intermediate separator gap 126 are separated. The bearing surfaces enclose the standing shaft 112 at a distance of a few microns to form an axially extending portion of the bearing gap 120 and form with each opposite bearing surfaces of the shaft 112 two fluid dynamic radial bearings 122 . 124 characterized by sinus, chevron, herringbone or parabolic bearing groove structures. The separator gap 126 has a larger gap width than the bearing gap 120 in the area of radial bearings 122 . 124 and can be in the bushing 114a and / or the wave 112 be educated.

The bearing structures of the radial bearings 122 . 124 are on the surface of the shaft 112 and / or the bearing bush 114a applied and practice during rotation of the bearing pumping action on the in the bearing gap 120 located bearing fluid. As a result, a hydrodynamic pressure is built up, the radial bearings 122 . 214 makes it workable. The upper radial bearing 122 is formed largely symmetrical, which means that the bearing groove structures above and below the apex are of equal length. Due to the symmetrical design of the bearing grooves, there is no resulting directional pumping action which acts on the bearing fluid. In contrast, the lower radial bearing 124 asymmetrical in that the portion of the bearing groove structures disposed below the apex is made longer than the portion located above. This results in a resulting, directed pumping action, the bearing fluid axially upwards in the direction of the upper radial bearing 122 promoted.

To the lower radial bearing 124 closes a radially extending portion of the bearing gap 120 on, by radially extending bearing surfaces of the bearing bush 114a and corresponding opposite bearing surfaces of the fixed bearing component 116 is formed. These bearing surfaces are considered to the axis of rotation 140 formed perpendicular circular rings and form a fluid dynamic thrust bearing 128 , The first fluid dynamic thrust bearing 128 is characterized in a known manner by, for example, spiral or fishbone-shaped bearing groove structures, which have a pumping action in the direction of the bearing interior, that is to say the lower radial bearing 124 , exert on the bearing fluid.

At the radial portion of the bearing gap 120 in the area of the thrust bearing 128 closes a proportionally filled with bearing fluid capillary seal 136 on, by opposing surfaces of the bearing bush 114a and the first bearing component 116 is formed and the bearing gap 120 of the storage system on this side seals. The capillary seal 136 includes one opposite the bearing gap 120 widened radially extending portion radially outward of the thrust bearing 128 is arranged. The radial section of the capillary seal 136 merges into a conically opening nearly axially extending portion extending from an outer peripheral surface of the bearing bush 114a and an inner peripheral surface of the first bearing member 118 is limited. In addition to the function as a capillary seal, the capillary seal is used 136 as a fluid reservoir and provides the required for the life of the storage system fluid amount. Furthermore, filling tolerances and a possible thermal expansion of the bearing fluid can be compensated. The two of the conical section of the capillary seal 136 limiting surfaces of the bearing bush 114a and the bearing component 116 can each be between 0 ° and 5 ° relative to the axis of rotation 140 inclined inwardly, the outer peripheral surface of the bearing bush 114a is inclined more inwardly than the inner peripheral surface of the fixed bearing component 116 , This creates the conical cross section of the capillary seal 136 , And the bearing fluid is in rotation of the bearing due to the centrifugal force inward toward the bearing gap 120 pressed.

Above the lower capillary seal 136 joins an air space, which initially extends axially upwards, then kinks in the radial direction and finally kinks back in the axial direction. This airspace forms a labyrinth seal 137 which is an excessive evaporation of the bearing fluid from the capillary seal 136 prevented.

A recirculation channel 130 extends from a radial portion of the bearing gap 120 between an end face of the recess of the bearing bush 114a and an opposite end surface of the second bearing member 118 obliquely down through the bushing 114a and opens radially outside the thrust bearing 128 in the radially extending portion of the capillary seal 136 ,

Along the radial section of the bearing gap 120 between the recess of the bearing bush 114a and the second bearing component 118 an optional second fluid dynamic thrust bearing (not shown in the drawing) can be arranged. This section is followed by a capillary seal 134 on, the bearing gap 120 the bearing system seals at this end. The capillary seal 134 is limited by the outer peripheral surface of the annular bearing member 118 and the inner peripheral surface of the bearing bush 114a , The capillary seal 134 limiting surface of the bearing bush 114a runs to the bearing outer parallel to the axis of rotation 140 while the surface of the annular bearing component 118 initially also parallel to the axis of rotation 140 runs and then has a slope to the outside, causing the end of the capillary seal 134 has a conical cross section. Along the axis of rotation 140 parallel section is preferably a dynamic pumping seal 138 arranged, which is characterized by pump groove structures, which on the inner peripheral surface of the bearing bush 114a and / or the outer peripheral surface of the annular bearing member 118 are arranged and generate a pumping action in the direction of the bearing interior. Between the pumping seal 138 and the radially extending portion of the bearing gap 120 is arranged in the axial direction of a so-called quiet zone, which prevents air from entering the camp.

The capillary seal 134 is from the in 2 shown cap 142 on the side of the bearing farther away from the base plate 10 is arranged and the axial attachment 142c has covered. The cap 142 is over the edge of the bearing bush 114a slipped over and is fixed there, for example by means of a press and / or adhesive connection.

Surfaces, especially the cover 142 which are not to be wetted by bearing fluid may be coated with a suitable oil stopper or the like.

Between the outer peripheral surface of a cylindrical end portion of the annular bearing member 118 and the inner circumference of the cap 142 is an axially extending air gap in the form of a gap seal 132 arranged, which ensures the pressure equalization, reduces the risk that escaped bearing fluid escapes from the camp and the capillary seal 134 connects with the outside environment.

If the storage system only a single fluid dynamic thrust bearing 128 that points to the hub 114 an axially directed force in the direction of the second bearing component 118 exerts a corresponding counterforce or biasing force on the hub 114 be exercised, which holds the storage system axially in equilibrium. This can be done on the base plate 110 a ferromagnetic ring 150 be arranged, the rotor magnet 148 axially opposite and is magnetically attracted by this. This magnetic attraction counteracts the force of the fluid dynamic thrust bearing 128 and keeps the bearing axially stable. Alternatively or in addition to this solution, the stator assembly 146 and the rotor magnet 148 axially offset from each other, in such a way that the magnetic center of the rotor magnet 148 axially further away from the base plate 110 is arranged as the center of the stator assembly 146 , Also, an axial force is built up by the magnet system of the motor, which is opposite to the thrust bearing 128 acts.

4 shows an enlarged section of the spindle motor of 1 in a modified embodiment of the invention. In contrast to 1 where the recess 44 the cap 42 mostly directly over the capillary seal 28 is arranged, the recess is 44 ' in 4 completely radially inward of the opening of the capillary seal 28 arranged. The opening of the capillary seal 28 and the recess 44 ' therefore do not overlap in the radial direction. The recess 44 ' has a rectangular cross section, with the lateral walls parallel to the axis of rotation 16 , and the top wall perpendicular to it.

The area of the opening of the capillary seal 28 is only by a radially inwardly extending gap 45 connected to the recess. The underside of the cap 42 covers the opening of the capillary seal 28 completely and in close proximity. The annular gap 45 forms a constriction between the upper opening of the capillary seal 28 and the recess 44 ' the cap 42 , The gap 45 formed constriction prevents from the capillary seal 28 leaking bearing fluid enters the region of the recess. Instead, the capillary seal is being used 28 escaping bearing fluid at the bottom of the cap 42 rejected and mostly immediately back into the capillary seal 28 flow. The recess 44 ' forms a second safety zone and absorbs the bearing fluid, which nevertheless passes through the gap 45 in the recess 44 ' arrives.

In order to prevent wetting with bearing fluid, suitable surfaces are provided with a barrier film or an oil stopper. Preferably, a barrier film 54 on the cover 42 , in particular on the surfaces of the recess 44 and above the opening of the capillary seal 28 and the inner circumference of the cover. Further, a barrier film 56 on the upper face of the storage cone 14 and the outer peripheral surface of the shaft 12 arranged. As a result, the bearing fluid can not adhere to these coated surfaces and flows off easily.

5 shows an enlarged section of the spindle motor of 2 in a modified embodiment of the invention. In contrast to 2 , where the approximately wedge-shaped recess in cross section 144 the cap 142 for the most part directly above the capillary seal 28 is arranged, the recess is 144 ' in 5 completely radially inward of the opening of the capillary seal 28 arranged. The opening of the capillary seal 28 does not overlap in the radial direction with the recess 144 ' , The recess 144 ' has a triangular cross section, wherein the radially outer side wall is formed as a slope and the radially inner, the shaft 12 facing wall of the recess 144 ' parallel to the axis of rotation 16 runs.

The area of the opening of the capillary seal 28 is only by a radially inwardly extending gap 45 connected to the recess. The underside of the cap 142 covers the opening of the capillary seal 28 completely and in close proximity. The annular gap 45 forms a constriction between the upper opening of the capillary seal 28 and the recess 144 ' the cap 142 , Starting from the gap 45 The cross-section of the recess widens continuously in the direction of the shaft 12 , The gap 45 formed constriction prevents from the capillary seal 28 escaping bearing fluid passes directly into the region of the recess. Instead, the capillary seal is being used 28 escaping bearing fluid at the bottom of the cap 142 rejected and mostly immediately back into the capillary seal 28 flow. The recess 144 ' forms a second safety zone and absorbs bearing fluid, yet through the gap 45 in the recess 144 ' should arrive.

The triangular cross section and the radially outer oblique wall of the recess 144 ' facilitate backflow of the bearing fluid from the recess into the capillary seal. This is further assisted by the centrifugal force which acts radially outward on the bearing fluid which coalesces with the cap 142 rotates. The centrifugal force carries this within the recess 144 ' the cap 142 adhering bearing fluid along the oblique wall of the recess 144 ' radially outward, where it is then in the capillary seal 28 can drip off.

In order to prevent wetting with bearing fluid, suitable surfaces are provided with a barrier film or an oil stopper. Preferably, a barrier film 54 on the cover 142 provided, in particular on the surfaces of the recess 144 ' and above the opening of the capillary seal 28 and the inner circumference of the axial section 142c the cover 142 , Further, a barrier film 56 on the upper face of the storage cone 14 and the outer peripheral surface of the shaft 12 arranged. As a result, the bearing fluid does not adhere to these coated surfaces and flows off easily.

Especially the wave 12 is in a designated hole in the base plate 10 pressed. As a lubricant for easier pressing, isopropanolamine (IPA) is preferably used. The base plate 10 is preferably made of aluminum while the shaft 12 Made of hardened steel. In 1 is the hole in the base plate 10 designed as a blind hole. Will be before pressing the shaft 10 in the blind hole of the base plate 10 If too much IPA is applied, the excess IPA is pushed out of the blind bore when the shaft is pressed in and reaches the inside of the bearing, where it can cause damage. Advantageously, it can therefore be provided to use adhesive as the lubricant for all press-fit connections which are provided in the spindle motors shown here. Due to the consistency of the adhesive, the amount of applied adhesive lubricant can be very precisely metered, and further the compression bond is additionally strengthened by the adhesive bond.

The spindle motors shown here can be used to drive a hard disk drive. For this purpose, one or more storage disks (not shown in the drawing) can be fastened to the hub. Furthermore, the spindle motor can also be used to drive a fan wheel or a laser scanner.

LIST OF REFERENCE NUMBERS

10, 110

baseplate

12, 112

wave

14, 116, 118

bearing component

16, 140

the rotation axis

18, 114a

bearing bush

20, 114

hub

22

sealing washer

24

conical bearing

26, 120

bearing gap

28, 30, 134, 136

capillary

32, 138

pump seal

34

groove

36

air gap

38

compensating bore

40, 130

recirculation

42, 142

cap

42a, 142a

radial section

42b, 142b

axial section

142c

axial attachment

44, 144

recess

44 ', 144'

recess

45

gap

46, 132

gap seals

48

magnetic inference

50, 148

rotor magnet

52, 146

stator

54

barrier film

56

barrier films

117

circumferential groove

122, 124

radial bearings

126

separator gap

128

thrust

137

labyrinth seal

150

ferromagnetic ring

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

• DE 102013009491 A1 [0004]
• US 201310320793 A1 [0006]

Claims (18)

A fluid dynamic bearing system, comprising: a fixed bearing component consisting of at least one shaft ( 12 . 112 ), a relative to the fixed bearing member about a rotation axis ( 16 . 140 ) rotatable bearing component, consisting of a hub ( 20 . 114 ) with at least one bearing bush ( 18 . 114a ), at least one filled with a bearing fluid, on both sides open bearing gap ( 26 . 120 ), which separates the fixed and the rotatable bearing component from each other, at least one capillary seal ( 28 . 30 . 134 . 136 ) at the ends of the storage gap ( 26 . 120 ) is arranged, at least one cap ( 42 . 142 ) having an opening in the middle, which has a radially extending portion ( 42a . 142a ) and an axially extending portion ( 42b . 142b ), wherein the inner circumference of the axially extending portion ( 42b . 142b ) on the outer circumference of the position bushing ( 18 . 114a ), wherein the radially extending portion ( 42a . 142a ) of the cap ( 42 . 142 ) on the capillary seal ( 28 . 136 ) facing side a recess ( 44 . 44 ' 144 . 144 ' ), characterized in that the opening of the capillary seal ( 28 . 136 ) and the recess ( 44 . 44 ' . 144 . 144 ' ) in the radial direction at least partially do not overlap. Fluid dynamic bearing system according to claim 1, characterized in that the recess ( 44 ' . 144 ' ) completely radially inward of the opening of the capillary seal ( 28 . 136 ) is arranged so that the opening of the capillary seal ( 28 . 136 ) and the recess ( 44 ' . 144 ' ) do not overlap in the radial direction. Fluid dynamic bearing system according to claim 2, characterized in that the area of the capillary seal ( 28 . 136 ) by a radially inwardly extending gap ( 45 ) with the recess ( 44 ' . 144 ' ) connected is. Fluid dynamic bearing system according to claim 2, characterized in that mutually facing surfaces of the fixed bearing component ( 12 . 14 ) and / or the cap ( 44 . 44 ' . 144 . 144 ' ) with a barrier film ( 54 . 56 ) or an oil stopper. Fluid dynamic storage system according to one of claims 1 to 4, characterized in that the recess ( 44 . 44 ' ) is rectangular in cross-section. Fluid dynamic storage system according to one of claims 1 to 4, characterized in that the recess ( 144 ' ) is triangular in cross section, wherein the cross section in radially inwardly in the direction of the axis of rotation ( 16 ) expands. Fluid dynamic bearing system according to claim 6, characterized in that the radially outer wall of the recess ( 144 ' ) has a slope, and the radially inner wall of the recess ( 144 ' ) parallel to the axis of rotation ( 16 ) runs. Fluid dynamic storage system according to one of claims 1 to 4, characterized in that the recess ( 144 ) is wedge-shaped or triangular in cross-section, the cross-section being radially outward in the direction of the axis of rotation ( 16 . 140 ) narrowed. Fluid dynamic bearing system according to claim 8, characterized in that the radially inner wall of the recess ( 144 ' ) parallel to the axis of rotation ( 16 . 140 ), and the radially outer wall of the recess ( 44 . 144 ) has a slope. Fluid dynamic bearing system according to one of claims 1 to 9, characterized in that on the radially inner side of the radially extending portion ( 142a ) of the cap ( 142 ) an axially extending attachment ( 142c ), which is opposite to the direction of the axially extending portion (FIG. 142b ) of the cap ( 142 ) runs. Fluid dynamic bearing system according to one of claims 1 to 10, characterized in that the inner circumference of the radial portion ( 42a . 142a ) of the cap ( 42 . 142 ) with the outer circumference of the shaft ( 12 . 112 ) has a narrow, axially extending air gap in the form of a gap seal ( 46 . 132 ) trains. Fluid dynamic bearing system according to one of claims 1 to 11, characterized in that the fixed bearing component at least one bearing component ( 14 . 116 . 118 ), which on the shaft ( 12 . 112 ) is arranged. Fluid dynamic bearing system according to one of claims 1 to 12, characterized in that at least one fluid dynamic radial bearing ( 122 . 124 ) between the shaft ( 112 ) and the bearing bush ( 114a ) and at least one fluid dynamic thrust bearing ( 128 ) between the bearing bush ( 114a ) and the bearing component ( 116 ) is arranged. Fluid dynamic bearing system according to one of claims 1 to 12, characterized in that the outer periphery of the bearing component ( 14 ) is conical and two bearing components ( 14 ) together with respective opposite bushes ( 18 ) two conical bearings ( 24 ) form. Spindle motor with a fluid dynamic bearing system according to one of claims 1 to 14 and an electromagnetic drive system consisting of a stator arrangement ( 52 . 146 ) and a rotor magnet ( 50 . 148 ). Spindle motor according to claim 15 for driving a hard disk drive. Spindle motor according to claim 15 for driving a fan. Spindle motor according to claim 15 for driving a laser scanner.

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