DE10315222B3 - Method and device for introducing lubricant in a hydrodynamic bearing - Google Patents

Abstract

Method for the optimized introduction of lubricant into the bearing gap between the shaft and shaft receiving a hydrodynamic bearing, wherein a bearing gap area between the shaft and shaft receiving and / or a region which is in fluidly effective communication with the bearing gap, controlled with lubricant drops is applied.

Description

The The invention relates to a method and a device for introduction of lubricant in the bearing gap between shaft and shaft mount a hydrodynamic bearing.

Hydrodynamic Bearings (fluid bearings) are used, for example, for the rotary mounting of high-precision spindle motors used, as they are used in hard disk drives. Hydrodynamic bearings have in comparison with ball bearings a high running accuracy (low Eccentricity) and smoothness at much higher Shock resistance (robustness) on. They work almost noiselessly and wear-free, there while operating at rated speed no direct body contact with solid state friction exists between the relatively rotating bearing parts.

Between The shaft and the shaft mount is doing a thin layer of lubricant for example, a lubricating oil.

From the US 5,778,948 A For example, there is known a method of introducing a fluid into a bearing, wherein the bearing has a fixed part and a rotating part. In a low pressure environment, the bearing fluid is introduced into a space between the fixed part and the rotating part.

From the US 6,305,439 B1 For example, an oil introduction method to a bearing is known in which a measured amount of oil is placed in a shaft receiver and then the shaft is inserted.

The US 5,862,841 A and US 5,601,125 disclose devices for filling hydrodynamic bearings with fluid.

Of the Invention is based on the object, a method and an apparatus to create, by means of which an optimized introduction of lubricant allowed in the bearing gap becomes.

These The object is achieved according to the invention in the method mentioned solved that a bearing gap area between wave and wave recording and / or an area which with the bearing gap in fluidly effective connection is controlled with lubricant drops is applied, wherein the lubricant drop generation regarding the Drop size and / or the drop velocity and / or the drop generation rate and / or the Drop quantity is controlled.

By the controlled application of lubricant drops can be Fill the bearing gap with lubricant without contact between the loading area and a lubricant source is present. This will cause the backflow of lubricant and an associated contamination of the lubricant in the Lubricant source due to refluxing lubricant avoided.

About the Controlled admission by means of lubricant drops can be the filling process in time, spatial and volumetrically control with high reproducibility and a filling of the Storage gaps up to a desired reach defined level. Furthermore, air pockets in the Avoid introducing lubricant into the bearing gap. Thereby Again, the properties of a suitably filled warehouse optimized.

The inventive method is clean room suitable, so that the filling of the warehouse can take place in the clean room.

The Lubricant drops can be generated individually and in succession emit. This can be done minimize contamination of a working space by lubricant.

Especially it is envisaged that the lubricant drop generation in a spatial distance to the affected area. This allows a targeted non-contact Schmiermittelbeaufschlagung to reach. Furthermore, a contamination of lubricant by return prevented by lubricant, since such a reflux connection is eliminated.

preferably, The lubricant drops from a lubricant drop generator in directed to the applied area. That way you can Also fill the bearing gap with a very small hydraulic diameter. By Control of the number of drops can be a defined level reach in the bearing gap.

Especially it is envisaged that the applied area not in fluidly effective contact with a Lubricant source is so as to contamination of lubricant in the lubricant source by refluxing lubricant to prevent.

It is particularly advantageous if the lubricant drop generation is controlled with respect to the droplet size, so as to achieve a filling even with bearing gaps with a small hydraulic diameter. It can then be a suitably selected drop size a lubricant film in a defined range on the shaft and the Forming wave recording, on the turn then optimal filling of the bearing gap is reached.

Especially In the process, microdroplets are produced whose mean droplet diameter in the range between 50 μm and 150 μm is and in particular in the range between 75 microns and 95 microns, if, for example Ester oil as a lubricating oil is used.

Farther it is advantageous if the loading region of the lubricant drops spatial is given. It can be so in particular to achieve that forms a lubricant film, which the bearing gap between shaft and wave recording covered; This lubricant film is then pressurized, for example can be brought into the bearing gap. This can be synonymous with very small Bearing gaps (with a low hydraulic diameter) reach a filling, without that directly into the bearing gap or at least deep into the bearing gap a drop injection performed must become.

Especially It is advantageous if taken care of that will happen forms a closed lubricant layer around the shaft, which the bearing gap to the outside covering. This is the area of the storage gap, which is below the lubricant film is located, gas-tight from an outside space separated. Will then, for example, under the influence of atmospheric pressure the lubricant is pressed into the bearing gap, then it is ensured that no Air in the bearing gap is sucked in, so that air bubbles in the lubricant be avoided in the bearing gap. Furthermore, can be in this way related Form lubricant film whose volume is such that the desired filling level is reached in the bearing gap. By controlling the amount of drops let yourself Adjust the lubricant volume of the lubricant film.

It can also be provided that the lubricant drop generation in terms of the drop speed is controlled. This can be a set the optimal value of the speed; this is set up that the Drop the desired one Reach the loading area, without affecting the lubricant layer impinging drops, for example, interrupt the lubricant film or tear open.

Farther is it cheap when the lubricant drop generation with respect to the drop generation rate is controlled. This can be done achieve a volumetric control of the drop application, d. H. it can be done achieve a quantity control of the drops, which on the loading area to meet. This in turn can be a desired one filling level adjust the lubricant in the bearing gap.

to In particular, it is volumetric control of the drop action provided that the Number of generated drops counted becomes. This can be done electronically and / or optically respectively. At the optical count In particular, the number of drops, which the desired Be reached.

All It is particularly advantageous if the application of drops in a working space under vacuum conditions, in particular the Pressure is at least temporarily below 1 mbar. In these conditions let yourself also a one-sided closed bearing, the bearing gap of only one end face of the shaft receptacle is accessible, while avoiding of air bubbles fill with lubricant; the bearing gap is evacuated for this purpose before filling. This air-free filling can be achieve this by ensuring that that yourself in a throat area between shaft and shaft intake first a grease buildup from which lubricant flows around the shaft and then forms a self-contained lubricant ring, which in turn the Covering the bearing gap and therefore also seals. Subsequently, will the working space ventilated, so that the outer air pressure the lubricant from the lubricant ring in the bearing gap presses and thereby the filling of the storage gap takes place. This filling process can be also for Apply bearing gaps with a very small hydraulic diameter, without that Risk of air bubbles consists.

It So there is an admission with a quantity of lubricant (before ventilation the working space) according to the desired degree of filling of the storage gap.

The The object mentioned above is further in the aforementioned Device according to the invention thereby solved, that the Lubricant generator is designed so that generated drops of lubricant such a kinetic impulse is given that the defined loading area is covered with lubricant drops.

The Advantages of the device according to the invention were already in connection with the method according to the invention explained.

Further advantageous embodiments have also already been related with the method according to the invention explained.

Especially is an evacuable work space for receiving the camp provided so under vacuum conditions a lubricant drop connection to be able to produce taking then for ventilation by atmospheric pressure lubricant penetrates into the bearing gap and this completely without air bubbles up to the desired Water level fills.

Farther is it cheap when the bearing and the lubricant drop generator relative to each other are positionable and in particular are mutually movable. This can be done by means of the lubricant drop generator, over which a spatially defined Can set admission area with high reproducibility, a defined filling reach the storage gap. In particular, it is possible a closed lubricant film around the shaft at the bearing gap to produce, which is then brought into the bearing gap.

Farther is it cheap when the lubricant drop generator at a distance from the Bearing is positioned so as to avoid in particular a lubricant return, which in turn avoids the risk of lubricant contamination is.

at an embodiment comprises the lubricant drop generator a nozzle head with a piezo actuator. About one such piezo actuator can be in a lubricant fluid column Generate impulse, which the liquid accelerated; By means of this acceleration, the constriction of a Microdrop, for example, the drop generation controllable in terms of drop size is. The drop production can be also timed. Furthermore, can be control the drop speed and by appropriate positioning the dosing head to the bearing gap can be the lubricant drop direction for loading the bearing to adjust.

Cheap is it if a means of counting provided by generated lubricant drops. This can be done a quantity control (volumetric control) of the lubricant drop application via determination reach the drop number. The count can be done electronically and / or optically, for example.

For example can a counter the Be associated with lubricant drop generator. It can be to an electronic count (for example, about count the droplet-producing Pulses from a piezoactuator) or an optical count.

at an optical count In particular, a camera is provided, for example a CCD camera (Which can also be arranged at a distance from the generator).

Further it is advantageous if a control and / or regulating device proceed by means of which the lubricant drop generation and Lubricant dropping of the bearing controllable and / or is controllable. additionally Cheap it is when this control and / or regulating device a controlled and / or regulated change allows the pressure in the working space in which the lubricant filling process takes place. Such, preferably automatically running lubricant filling the hydrodynamic bearing ensures that the desired filling level on reproducible Way is maintained without it to air pockets comes.

Cheap is it if a source of lubricant in an evacuated room and is arranged in particular in the working space. This will degas the gas of the liquid Promoted lubricant and thereby in turn ensures that the Drop production does not stop.

The The following description of a preferred embodiment is used in conjunction with the drawing of the closer explanation the invention. Show it:

1 a schematic view of an embodiment of an inventive device for introducing lubricant in the bearing gap between the shaft and shaft receiving a fluid dynamic bearing;

2 a perspective sectional view of an embodiment of a dosing of a lubricant drop generator and

3 (a) to 3 (d) enlarged view of the area A according to 1 as snapshots of the procedure during the introduction of the lubricant in chronological order.

at hydrodynamic bearings (also referred to as fluid bearings) is in the bearing gap between the shaft and shaft mount (bearing sleeve) Introduced lubricant film. This lubricant film allows a Floating of the rotating bearing part (the shaft, if this rotatably is connected to a rotor, or the bearing sleeve, if this rotatably with the rotor is connected) when starting up, for example, an electric motor. The appropriate pressure generation is non-contact, that is it is no solid friction in front.

Turbulence structures that correspond by Chen ripple patterns are formed and are arranged on corresponding surfaces of the shaft and / or the bearing sleeve, can arise in the lubricant film zones of hydrodynamic pressure. The local pressure gradients are substantially inversely proportional to the gap thickness of the bearing gap, so that shifts between waves and shaft recording are compensated for immediately self-regulating. It can thereby ensure a stable concentric alignment between the shaft and shaft recording.

Hydrodynamic Bearings have for this reason a particularly high running accuracy and rotational accuracy. They work almost wear-free. she characterized by low noise and Shock resistance.

fluid Dynamic Bearings are preferred for rotary bearing of high precision spindle motors for hard drives used.

at the production of a hydrodynamic bearing of the bearing gap after assembly of the Components are filled with the lubricant. A typical example for a Lubricant is ester oil.

An embodiment of a device according to the invention for introducing lubricant into the bearing gap 10 between a wave 12 and a wave recording 14 (Bearing sleeve) of a hydrodynamic bearing 16 is in 1 shown schematically and there as a whole with 18 designated.

The device 18 includes an airtight sealable capsule 20 in which a working space 22 for receiving the warehouse to be filled 16 is formed. The workroom 22 is evacuable, so that a filling process can be carried out under vacuum conditions.

This is the work space 22 via a controllable valve 24 with a pump 26 connected by means of which a negative pressure relative to the external atmospheric pressure in the working space 22 can be generated. In particular, a pressure can be less than 1 mbar in the working space 22 to reach.

Furthermore, a controllable valve 28 provided, over which the working space 22 ventilated in a timely manner, in particular in the workspace 22 To produce atmospheric pressure conditions.

The warehouse to be filled 16 which is in the workroom 22 is positioned at one end 30 the wave recording 14 through an abutment 31 sealed gas-tight.

At the opposite end is a widening 33 provided by the there the width of the storage gap 10 is enlarged. The expansion 33 may be formed on the shaft receiving, for example, by this includes a hollow truncated cone-shaped recess and / or is by a constriction on the shaft 12 educated.

The filling of the storage gap 10 takes place via the open side of the shaft mount 14 , Within the storage gap 10 forms a thin coherent lubricant film. The capillary forces acting in this lubricant film and the adhesion forces between lubricant and metallic bearing surfaces (on the shaft 12 and on the shaft 12 facing inner surface of the shaft mount 14 ) ensure the stability of the lubricant film. These forces also prevent leakage of the lubricant film from the bearing gap 10 ,

In the workroom 22 is for filling the storage gap 10 with lubricant a lubricant drop generator 32 (Drop dispenser) arranged, with the controlled lubricant drops can be generated and controlled on the bearing gap 10 to be judged.

Due to their kinetic momentum, the drops of lubricant fly onto the bearing gap 10 to, so that they are shot to this as it were.

The lubricant drop generator 32 is with a lubricant source 34 connected, so that the lubricant supply is ensured. The lubricant drop generator 32 itself is to the camp 16 spaced and in particular is not in fluidly effective contact with the bearing 16 , This is also the lubricant source 34 not in fluid contact with the bearing 16 , So there is no reflux connection between the bearing 16 and the source of lubricant 34 so that contamination by recirculating lubricant is excluded. According to the invention, only as much lubricant is conveyed as for filling the bearing gap 10 is needed.

The lubricant source 34 is preferably in an evacuated room and for example in the work space 22 arranged. If a vacuum at the lubricant source 34 arises, then the degassing is promoted there. This in turn ensures the functionality of the drop generation.

The lubricant drop generator 32 includes, as exemplified in 2 shown a dosing 36 with a nozzle 38 , by means of which targeted lubricant drops to the bearing gap 10 rich let it go. The dosing head 36 is relative to the camp 16 positionable, so as to be able to occupy a defined loading area with lubricant drops.

In particular, while the dosing 36 and the camp 16 movable relative to each other. It is also possible that these are rotatable relative to each other, so that the bearing gap 10 can be filled via a circumferential direction.

In Practice has shown that one a uniform filling around reaches the circumference without relative movement, since the flow properties of the lubricating oil suffice.

In one embodiment of the dosing 36 is a piezoactuator 40 provided, which in a housing 42 is arranged. The piezoactuator 40 is above a fluid line 44 with the lubricant source 34 in connection.

The nozzle 38 sits at a capillary tube 46 or is formed integrally with this. In the capillary tube 46 There is a liquid column of the liquid lubricant. Due to the training as a capillary tube occurs with inactive piezoelectric actuator 40 no liquid from the nozzle 38 out.

When activating the piezoactuator 40 this liquid column receives a mechanical impulse which accelerates the liquid. This results in the pinch-off of a single drop against the surface tension at the nozzle-side end of the liquid column, and this drop then leaves the metering head 36 ,

Via the piezoactuator 40 can affect the formation of droplets in a wide range. About the dosing head 36 it is possible to control the formation of droplets in terms of drop volume (volumetric control) and temporal and local droplet application. Emitted drops of lubricant can be deposited with high reproducibility in a desired loading area on the bearing 16 place, so that a targeted filling process of the storage gap 10 is possible.

It can still have a nozzle heater 48 be provided by the heating of the viscosity of the lubricant can be reduced, so as to influence the lubricant drop generation can.

For controlling the formation of droplets and droplets, a control and / or regulating device 50 be provided ( 1 ), over which in particular the piezoactuator 40 is controllable and which also on the control valves 24 and 28 can act.

About the control and / or regulating device 50 can be electronically via the pulsing of the piezo actuator 40 the amount of lubricant with which the bearing 16 is determined. It may additionally or alternatively a counter 52 be provided, by means of which the Schmiermitteltropfenbeaufschlagung the camp 16 is determined optically. This counter 52 can on the dosing head 36 be arranged or at a distance to this. For example, the counter comprises 52 a CCD camera.

In a variant of an embodiment, the dosing comprises 36 an integrated stroboscopic light-emitting diode to make the emission of drops observable and with a counting device 52 to register the drop application.

In particular, the counter stands 52 in connection with the control and / or regulating device 50 so as a targeted control or regulation of the lubricant filling of the bearing 16 to reach.

The inventive method for introducing lubricant into the bearing gap 10 between wave 12 and wave recording 14 works as follows:
In the workroom 22 become the dosing head 36 and the warehouse to be filled 16 , which at the bearing gap 10 is open to one side, with the dosing head 36 is aligned to this open page ( 3 (a) ).

The workroom 22 is evacuated and brought in particular below a pressure of 1 mbar.

About the dosing head 36 Then, under vacuum conditions, drops of lubricant become the bearing gap 10 emitted ("shot"). The diameter of these micro-lubricant drops depends, inter alia, on the viscosity of the lubricant. When using ester oil, the diameter is typically between about 75 microns and 95 microns.

The lubricant drop generator 32 is activated and from the to the bearing gap 10 spaced nozzle 38 The drops of lubricant come out at high speed and fly in the direction of the bearing gap 10 , They meet in the bearing gap area 54 on and / or in a throat area 56 between the wave 12 and a front side 57 the wave recording 14 , It forms then especially in this throat area 56 a lubricant accumulation, which with sufficient Schmierropfenropfenbeaufschlagung to the formation of a bearing gap 10 covering liquid ring 58 that leads to the wave in this area 12 surrounds ( 3 (b) ).

Due to the fact that due to the orientation of the nozzle 38 on the bearing gap 10 all the drops of lubricant in the bearing gap area 54 or in the throat area 56 it is ensured that essentially the complete, on the admission areas 54 . 56 directed amount of lubricant for filling the bearing gap 10 is being used.

It has been shown that the lubricant ring 58 self-training. But it can also be provided that the dosing 36 and the warehouse to be filled 16 be moved relative to each other, in which the shaft 12 surrounding throat area 56 a self-contained liquid ring 58 which in turn forms the bearing gap area 54 completely covered.

It may also be advantageous to have a plurality of around the shaft 12 distributed dosing heads 36 provided.

The control of the loading of the bearing to be filled 16 with lubricant drops takes place in such a way that in the throat area 56 around the shaft 12 the closed liquid ring 58 can train; this lubricant ring 58 in turn forms a meniscus, the convex surface of the bearing gap 10 completely covered ( 3 (b) ). The bearing gap 10 below this lubricant ring 58 is in accordance with the vacuum conditions in the work area 22 evacuated, with the lubricant ring 58 at least partially in the area 54 of the storage gap 10 can reach into it.

The drop application is controlled in quantity such that the volume of the lubricant ring 58 so dimensioned that the bearing gap 10 is filled to a desired filling level.

After completion of the drop transfer from the nozzle 38 to the bearing gap 10 becomes the workroom 22 ventilated ( 3 (c) and 3 (d) ). This will be the lubricant ring 58 forming lubricant quantity due to the pressure increase in the working space 22 in the storage gap 10 executed suppressed. Since the lubricant ring 58 the bearing gap 10 completely covered, the inclusion of air bubbles in the penetration of the lubricant in the bearing gap 10 safely prevented.

Under atmospheric conditions, ie at atmospheric pressure, the entire bearing gap 10 completely filled. Also the bearing gap area 33 is up to the desired level, as in 3 (d) indicated, filled.

By the device according to the invention and the method according to the invention, which can be carried out with this device, can also be bearing column defined with very small hydraulic diameter without air inclusions fill.

10

bearing gap

12

wave

14

shaft mount

16

hydrodynamic camp

18

contraption

20

capsule

22

working space

24

Valve

26

pump

28

Valve

30

The End

31

abutment

32

Lubricant drop generator

33

widening

34

lubricant source

36

dosing

38

jet

40

piezo actuator

42

casing

44

liquid line

46

capillary

48

nozzle heater

50

control and / or regulating device

52

counting

54

Bearing gap area

56

Kehlbereich

57

front

58

liquid ring

Claims (24)

A method for introducing lubricant into a bearing gap between the shaft and shaft receiving a hydrodynamic bearing, characterized in that a bearing gap area between shaft and shaft receiving and / or a region which is in fluidly effective connection with the bearing gap, controlled with lubricant drops, wherein the lubricant drop generation is controlled with respect to the drop size and / or the drop speed and / or the drop generation rate and / or the drop quantity. Method according to claim 1, characterized in that that the Lubricant drop generation at a distance to the acted upon Area is done. Method according to claim 1 or 2, characterized that lubricant drops from a lubricant drop generator in the applied area be directed. Method according to one of the preceding claims, characterized in that the beauf impacted area is not in fluidly effective contact with a lubricant source. Method according to one of the preceding claims, characterized characterized in that to be filled Storage gap is closed to one side. Method according to one of the preceding claims, characterized characterized in that a average droplet diameter is in the range between 50 microns and 150 microns. Method according to one of the preceding claims, characterized characterized in that Beaufschlagungsbereich the lubricant drops spatially specified becomes. Method according to one of the preceding claims, characterized characterized in that it is ensured that yourself forms a closed lubricant layer around the shaft, which the bearing gap to the outside covering. Method according to one of the preceding claims, characterized characterized in that Number of drops that are generated is counted. Method according to one of the preceding claims, characterized characterized in that Dropletting in a working space under vacuum conditions he follows. Method according to claim 10, characterized in that that the Pressure in the working space is at least temporarily below 1 mbar. Method according to claim 10 or 11, characterized that the Working space is vented after Tropfenbeaufschlagung the camp. Method according to one of the preceding claims, characterized characterized in that a Loading with a lubricant quantity corresponding to a filling level the gap is made. Device for introducing lubricant into the bearing gap ( 10 ) between a wave ( 12 ) and a wave recording ( 14 ) of a hydrodynamic bearing ( 16 ) comprising a lubricant drop generator ( 32 ) with a dosing head ( 36 ), by means of which lubricant drop into a bearing gap area ( 54 . 10 ) and / or in one with the bearing gap ( 10 ) in a fluidically active area ( 56 ) are directionable, wherein the lubricant generator ( 32 ) is formed so that generated drops of lubricant is given such a kinetic pulse that the defined loading area ( 54 ; 10 ) is covered with lubricant drops. Apparatus according to claim 14, characterized in that an evacuable working space ( 22 ) for receiving the camp ( 16 ) is provided. Device according to claim 14 or 15, characterized in that the bearing ( 16 ) and the lubricant drop generator ( 32 ) are positionable relative to each other. Device according to one of claims 14 to 16, characterized in that the lubricant drop generator ( 32 ) at a distance to the bearing ( 16 ) is positioned. Device according to one of claims 14 to 17, characterized in that the lubricant drop generator ( 32 ) a dosing head ( 36 ) with a piezo actuator ( 40 ) having. Device according to one of claims 14 to 18, characterized in that a device ( 52 ) is provided for counting generated drops of lubricant. Apparatus according to claim 19, characterized in that a counter means the lubricant drop generator ( 32 ) assigned. Device according to claim 19 or 20, characterized that one counting a camera covers. Device according to one of claims 14 to 21, characterized in that a control and / or regulating device ( 50 ) is provided, by means of which the lubricant drop generation and Schmiermitteltropfenbeaufschlagung the camp ( 16 ) is controllable and / or controllable. Apparatus according to claim 20, characterized in that by means of the control and / or regulating device ( 50 ) ventilation of the working space ( 22 ) is controllable and / or controllable. Method according to one of claims 14 to 23, characterized in that a lubricant source ( 34 ) in an evacuated room ( 22 ) is arranged.