DE102013015576A1 - Spindle motor for driving fan, has electromagnetic drive unit for rotating the rotatable motor component, and axial force generating unit for generating an aerodynamic force to fan wheel - Google Patents

Abstract

The spindle motor has a rotatable motor component (24) that is arranged relative to the fixed motor components (10,12) by a fluid dynamic bearing system. An axial force generating unit is arranged to bias the fluid dynamic thrust bearing (26). An electromagnetic drive unit is equipped to rotate the rotatable motor component, and is provided with a stator assembly (32) at fixed motor component and rotor magnet (34) at rotatable motor component. The axial force generating unit is provided for generating an aerodynamic force to the fan wheel (40).

Description

Field of the invention

The invention relates to a spindle motor, in particular a fan motor, with a fluid dynamic bearing system according to the preamble of claim 1.

State of the art

Spindle motors for use in fans are known in a variety of designs. In modern fans in particular spindle motors are used with fluid dynamic storage systems. Such a spindle motor is for example in the published patent application DE 10 2007 036 790 A1 disclosed.

The spindle motor comprises a stationary motor component which comprises base plate and a bearing bush arranged therein, and a rotatable motor component which has a shaft rotatably mounted in the bearing bush and a rotor component fixed on the shaft which carries a fan wheel or is designed directly as a fan wheel. The fan motor comprises a fluid-dynamic bearing system for rotational mounting of the rotatable engine component relative to the stationary engine component. The fluid dynamic bearing system preferably comprises two spaced apart fluid dynamic radial bearings and a fluid dynamic thrust bearing biased by magnetic means, i. H. is maintained in axial equilibrium. The rotatable motor component is driven by means of an electromagnetic drive system, which in a known manner comprises a stator arrangement, which is preferably arranged on the base plate, and a rotor magnet, which is arranged on an inner circumference of the rotor opposite the stator arrangement.

The fluid-dynamic thrust bearing generates a bearing force in a defined direction, which, as stated above, is compensated in a known manner by magnetic means.

When using the spindle motor to drive a fan, an aerodynamic force acting on the rotor component is generated as a result of the air flow. This aerodynamic force is in the axial direction with an axial fan, i. H. directed parallel to the axis of rotation of the rotor member and counteracts the air flow generated by the fan.

This axial direction of the aerodynamic force influences the function of the fluid-dynamic thrust bearing. In particular, this affects the width of the bearing gap in the region of the axial bearing, and in particular the so-called flying height of the rotor relative to the opposite bearing surface. In the worst case, the flying height of the rotor can be too large or too small, and it comes as a result to contact bearing surfaces and thus increased wear of the thrust bearing surfaces or the action surfaces of a stopper component, which prevents excessive axial displacement of the bearing.

Increased friction in the bearing, d. H. increased bearing wear will affect the reliability and life of the bearing and the entire fan.

Disclosure of the invention

It is the object of the invention to improve a spindle motor of the type described above, in particular for driving a fan, in terms of its reliability and service life.

This object is achieved by a spindle motor with the features of claim 1.

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

The spindle motor according to the invention for driving a fan comprises a fixed motor component, a motor component rotatable relative to the stationary motor component, a fluid dynamic bearing system for pivotally mounting the rotatable motor component relative to the stationary engine component, wherein the fluid dynamic bearing system comprises at least one fluid dynamic radial bearing and at least one fluid dynamic thrust bearing, means for Generation of an axial force for biasing the fluid dynamic thrust bearing and an electromagnetic drive system for rotary drive of the rotatable engine component.

The spindle motor is characterized in that the means for generating the axial force comprise both means for generating a magnetic force and means for generating an aerodynamic force.

In other words, the counterforce to the fluid dynamic thrust bearing is generated by both magnetic means and aerodynamic means. However, the aerodynamic force can also act in the direction of the fluid-dynamic force and thereby be used for adjusting the forces acting in the axial direction of the bearing forces.

All forces acting in the axial direction on the rotating component of the engine must be in equilibrium.

On the rotating motor component acts on the one hand, the axial force of the fluid dynamic thrust bearing. This force of the fluid dynamic thrust bearing counteracts the one hand, the weight of the rotating motor component and magnetic forces for biasing the fluid dynamic thrust bearing and aerodynamic forces that are generated in particular by the air flow of the fan.

The sum of all the forces acting on the rotating engine component forces must be adjusted so that the axial flying height of the rotating engine component with respect to the opposite bearing surface of the stationary engine component in the region of the thrust bearing between 4 to 100 microns and that in each operating position and under each operating condition of the engine.

The means for generating the magnetic force preferably comprise the stator assembly and the rotor magnet of the electromagnetic drive system, both of which are arranged axially offset from each other, so that an axial magnetic force component results, which counteracts the axial force of the fluid dynamic thrust bearing. The axial offset refers here and below in each case to the axial position of the magnetic centers.

Alternatively or in addition to this axial displacement of the electromagnetic drive system, the magnetic force can be generated by means of a ferromagnetic pull ring, which is arranged below the end face of the rotor magnet. The pull ring is magnetically attracted to the rotor magnet and generates an axial force which counteracts the axial force of the fluid dynamic thrust bearing.

As already mentioned above, the two possibilities of generating a magnetic axial counterforce F _mag to the fluid dynamic thrust bearing can be combined or used independently. Typically, the sum of these magnetic forces F _{mag is} about 0.25 N to 2 N, preferably between 0.5 N and 1 N.

In addition to the generation of the magnetic force, an aerodynamic force is generated according to the invention by a fan wheel arranged on the rotor component. The fan generates an axial aerodynamic force F _aero , which preferably counteracts the axial force of the fluid dynamic bearing F _fluid . Alternatively, however, the axial aerodynamic force F _aero can also act in the same direction as the axial force of the fluid dynamic bearing F _fluid .

In addition, the weight force F _G which, depending on the operating position, ie installation position of the motor, either adds to or subtracts from the axial force of the fluid-dynamic thrust bearing acts on the rotating engine component.

The axial forces, which are formed by the fluid dynamic thrust bearing, the weight of the rotor component, the magnetic axial forces and the aerodynamic axial force must be adjusted so that in the region of the thrust bearing an altitude of the rotor component in the range between 4 to 5 microns results , This altitude thus sets in an equilibrium of the axial forces, if ± F _G + F _mag ± F _aero = F _fluid applies, the sign of the weight F _G depends on the installation position of the engine and the sign of the axial aerodynamic force F _aero depends on the direction of the fan generated airflow. The amount of the axial aerodynamic force is usually smaller than the amount of the axial magnetic force, at least not much larger than this, so that the balancing of the forces is possible.

The invention may also be applied to radially extending airflows, such as those generated by a radial fan. In this case, the radial air flow may further comprise an axial component which may be used to adjust the axial forces as previously described.

However, it may also be advantageous to use the radial component of the force generated by the air flow of an axial fan or in particular a radial fan to support the radial bearing of the spindle motor.

It is in the adjustment of the axial and radial bearing forces of advantage to achieve a largely symmetrical distribution of the aerodynamic force. In the case of an axial fan, it is advantageous if the air flow strikes a plane surface arranged perpendicular to the axis of rotation of the spindle motor. In a radial fan, for example, a radially spaced, circular and concentric with the axis of rotation trained border may be beneficial to achieve a symmetrical distribution of the aerodynamic force.

The invention equally relates to a fan with a spindle motor according to the above features for driving the fan wheel.

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 fan motor with fluid dynamic storage system according to a preferred embodiment of the invention.

2 shows a section through another embodiment of a fan motor with fluid dynamic storage system.

Description of preferred embodiments of the invention

The 1 shows a section through a spindle motor with a fluid dynamic bearing system, as used for example for driving a miniature fan. The spindle motor comprises a base plate 10 on which a fixed bushing 12 is arranged. The bearing bush 12 has a central bearing bore and forms together with the base plate 10 the fixed component of the spindle motor. In the bearing bore of the bearing bush 12 is a wave 14 used, whose diameter is slightly, ie only smaller by a few microns, than the diameter of the bearing bore. Between the surfaces of the bearing bush 12 and the wave 14 there remains a bearing gap 16 a few microns wide. The bearing gap 16 is filled with a suitable bearing fluid, such as a bearing oil. The opposite surfaces of the shaft 14 and the bearing bush 12 form two fluid dynamic radial bearings 20 . 22 out, by means of which the shaft 14 around a rotation axis 18 rotatable in the bearing bush 12 is stored. The radial bearings 20 . 22 are through bearing groove structures 20a . 22a marked on the surface of the shaft 14 and / or the bearing bush 12 are applied. The bearing groove structures 20a . 22a practice with rotation of the shaft 14 a pumping action on the in the bearing gap 16 between wave 14 and bearing bush 12 located bearing fluid, so that in the bearing gap 16 a hydrodynamic pressure is built up, which is the radial bearings 20 . 22 makes it workable. The upper radial bearing 20 preferably has asymmetrically formed Lagerrillenstrukturen 20a that the bearing fluid predominantly toward the lower radial bearing 22 pump. The lower radial bearing 22 preferably comprises symmetrically formed bearing groove structures 22a which provides a uniform pumping action in both directions of the bearing gap 14 to the middle (apex) of the lower radial bearing 22 create.

A free end of the wave 14 is with a rotor component 24 connected, which has a cylindrical approach 24a which has the bearing bush 12 partially surrounds. A lower, planar surface of the rotor component 24 forms together with an adjacent end face of the bearing bush 12 a fluid dynamic thrust bearing 26 out. Here, the end face of the bearing bush 12 and / or the opposite surface of the rotor component 24 provided with preferably spiral-shaped Lagerrillenstrukturen (not shown), the rotation of the shaft 14 a radially inward toward the radial bearing 20 directed pumping action on the in the bearing gap 16 between the rotor component 24 and the upper end of the bearing bush 12 located bearing fluid exerts, so that the thrust bearing 26 becomes sustainable. But it can also be advantageous, the thrust bearing 26 to provide herringbone bearing groove structures. The bearing force of the fluid dynamic thrust bearing acts in the direction 42 , wherein the bearing surface of the rotor component 24 from the opposite bearing surface of the bearing bush 12 lifts and forms a radial bearing gap of several to several tens of microns wide. This radially extending bearing gap is also used as the flying height of the rotor component 24 designated. At the rotor component 24 is a fan 40 attached. Preferably, the rotor component itself may be formed as a fan.

In the bearing bush 12 is preferably a recirculation channel 28 arranged, one at the radially outer edge of the thrust bearing 26 located section of the storage gap 16 with one below the lower radial bearing 20 located section of the storage gap 16 directly connects and supports a circulation of the bearing fluid in the storage system. The recirculation channel 28 is preferably oblique in the bearing bush 12 arranged and completely filled with bearing fluid.

The bearing gap 16 includes an axial section extending along the shaft 14 and the two radial bearings 20 . 22 extends, and a radial portion extending along the end face of the bearing bush 12 and the thrust bearing 26 extends. At the radially outer end of its radial portion of the bearing gap is 16 into a gap with a greater gap distance, which in turn merges into an axial section which extends along the outer circumference of the bearing bush 12 between the bearing bush 12 and the cylindrical approach 24a of the rotor component 24 extends and a sealing gap 36 forms. The outer surface of the bearing bush 12 and the inner circumferential surface of the cylindrical extension 24a are largely cylindrical, but preferably slightly tapered and form the boundary of the sealing gap 36 ,

At the in the base plate 10 fixed side has the bearing bush 12 a recess whose diameter is significantly larger than the diameter of the bearing bore. The bearing bush 12 is on this side by a cover plate 30 locked. Inside the recess of the bearing bush 12 is a stopper member in the form of one with the shaft 14 one-piece connected stop locking 14a arranged, which has an enlarged outer diameter in the Comparison to the diameter of the shaft 14 having. The recess in the bearing bush 12 in which the stopper ring 14a is arranged, is with the bearing gap 16 and the recirculation channel 28 connected and completely filled with bearing fluid. In case of excessive axial movement of the shaft 14 the stopper ring hits 14a at a stage of the bearing bush, which is formed by the transition between the bearing bore and the recess. The stopper ring 14a prevents falling out of the shaft 14 from the bore of the bearing bush 12 , On the opposite surfaces of the stop locking 14a and the bearing bush 12 and / or the cover plate 30 It is also possible to introduce bearing groove structures which bring about additional, fluid-dynamic, axial bearing. These bearing groove structures may be formed, for example, fishbone-like or spiral.

The spindle motor has an electromagnetic drive system consisting of a stator assembly 32 that exists at the base plate 10 is attached. Radially opposite the stator assembly 32 is on an inner peripheral surface of a rim 24b of the rotor component 24 a rotor magnet 34 arranged. The rotor magnet 34 surrounds the stator assembly 32 concentric in the radial direction to form an air gap. Shown is an external rotor motor.

Since the fluid dynamic thrust bearing 26 only an axial force F _fluid in one direction, namely direction 42 , Generated, it is necessary to provide a corresponding bias, ie counterforce, so that the bearing is in axial balance.

The axial preload of the fluid dynamic thrust bearing 26 is achieved on the one hand in a magnetic manner by the stator assembly 32 and the rotor magnet 34 axially offset from each other, so that there is a magnetic force F _mag in the axial direction, the bearing force of the fluid dynamic thrust bearing 26 counteracts.

This axial offset d of the respective magnetic centers of the stator assembly 32 or the rotor magnet 34 is in 1 shown.

Furthermore, a magnetic axial force F _mag by the arrangement of a pull ring 38 on the base plate 10 be achieved.

The pull ring 38 is axially below the end face of the rotor magnet 34 arranged and used by the rotor magnet 34 magnetically attracted, so that a magnetic force F _mag in the direction 44 results in the axial force of the fluid dynamic thrust bearing F _fluid in the direction 42 counteracts.

The two possibilities of magnetic preload can be used individually as well as in combination with each other.

Further, according to the invention, a bias for the fluid dynamic thrust bearing 26 achieved by generating an aerodynamic force. This aerodynamic force is provided by a fan 40 generated, which in an advantageous embodiment, an air flow in the direction 42 generated.

As a result, one on the rotor component 24 acting aerodynamic force F _aero towards 44 generates, which counteracts the force F _{fluid of} the fluid dynamic thrust bearing.

Alternatively, the aerodynamic force F _aero can also act in the direction of the fluid-dynamic force and thus be used to adjust the bearing forces acting in the axial direction. This may be the case, for example, in one embodiment of the invention, in which the fan wheel an air flow in the direction 44 generated. In this case, therefore, one on the rotor component 24 acting aerodynamic force F _aero generated in the direction of the fluid dynamic force, both forces acting against the magnetic force F _mag .

It may be advantageous if the base plate 10 in the radial direction to the outer periphery of the fan 40 or beyond. This can be done in the area of the fan 40 a plane surface perpendicular to the axis of rotation to be able to hit the generated air flow, so that the aerodynamic force F _aero towards 44 is maximized. But it can also be advantageous if, as in the 1 shown, the base plate 10 in the radial direction only up to the area of the edge 24b of the rotor component extends. Thus, for example, a space-saving design and low material consumption can be achieved. Furthermore, this can be the surface of the blades of the fan 40 be maximized and thus an efficient fan can be made.

Also, the weight F _{G of} the rotating engine component including fan 40 is taken into account. Depending on the installation position of the spindle motor, this weight force F _G counteracts the bearing force of the fluid dynamic thrust bearing 26 or in the same direction of the bearing force of the fluid dynamic thrust bearing 26 ,

According to the invention, the axial forces of the fluid-dynamic thrust bearing 26 (F _fluid ), the magnetic means for generating a magnetic axial force F _mag and the aerodynamic means for generating an aerodynamic axial force F _aero and the weight F _G determined so that in the axial bearing an altitude, ie a Bearing gap width in the area of the thrust bearing 26 , between 4 to 100 microns. This should apply to all operating conditions of the spindle motor or the fan.

2 shows one opposite 1 modified embodiment of a spindle motor with fluid dynamic storage system.

Regarding 1 are in 2 identical components with identical or similar shape and function denoted by the same reference numerals, but in 2 the reference numerals in each case a "1" has been prefixed. For example, the shaft corresponds 114 in 2 the wave 14 in 1 ,

The spindle motor of 2 points opposite to the spindle motor of 1 a larger height, which is particularly recognizable by the fact that the bearing bush 112 long stretched and the two fluid dynamic radial bearings 120 . 122 compared to 1 have a significantly greater axial distance from each other.

In 2 is compared to 1 no base plate shown, but the spindle motor in 1 Can with a free end of the bearing bush 112 can be mounted as desired in a holder or holder. In the illustrated form, the spindle motor is mounted ready for use.

In this embodiment of the invention, the stator assembly 132 directly on the bearing bush 112 arranged and through an air gap from the rotor magnet 134 separated, at an inner edge 124b of the rotor component 124 is arranged.

The rotor component 124 itself is on a free end of the wave 114 mounted, wherein a lower surface of the rotor member 124 together with an upper end face of the bearing bush 112 a fluid dynamic thrust bearing 126 formed.

The lower end of the bearing in the area of the stop locking 114a is through a cover plate 130 closed, while the upper end of the bearing or the bearing gap 116 radially outside of the thrust bearing 126 in a sealing gap 136 passes, which, as related to 1 described, is formed.

The fluid dynamic thrust bearing 126 generates an axial force F _fluid in the direction during operation 142 , ie, the underside of the rotor component 124 floats on a fluid film through the bearing gap 126 separated over the upper end face of the bearing bush 112 , The distance between the end face of the bearing bush 112 and the underside of the rotor component 124 during operation of the warehouse is referred to as so-called altitude and can be between 4 and 100 microns.

To set this altitude in the appropriate limits, it is necessary, a counterforce to the axial bearing force (F _fluid ) of the thrust bearing 126 to generate, so that an axial equilibrium is established.

This axial preload for the fluid dynamic thrust bearing 126 According to the invention achieved on the one hand in a magnetic manner by the stator assembly 132 and the rotor magnet 134 axially offset from one another.

In other words, the magnetic center of the rotor magnet is located 134 in the direction 142 offset to the magnetic center of the stator assembly 132 , namely by a so-called axial offset d.

This results in an axially directed magnetic force F _mag in the direction 144 , the bearing force F _{fluid of} the fluid dynamic thrust bearing 126 counteracts and prevents the altitude of the thrust bearing, ie the width of the bearing gap 116 in the area of the thrust bearing, gets too big.

In addition, according to the invention, a bias for the fluid dynamic thrust bearing 126 achieved by aerodynamic means.

Since the spindle motor is preferably for driving a fan wheel 140 can be used by the fan 140 generated aerodynamic force to generate an aerodynamic bias for the fluid dynamic thrust bearing 126 be used.

The fan wheel 140 generated in a preferred embodiment of the invention, for example, an air flow in the direction 142 , As a result, one on the rotor component 124 acting aerodynamic force F _aero towards 144 generated, the force F _{fluid of} the fluid dynamic thrust bearing 126 counteracts.

The weight F _{G of} the rotating engine component 124 and the fan wheel mounted thereon 140 is also to be considered.

Depending on the installation position of the spindle motor, this weight force F _G acts either counter to the bearing force F _{fluid of} the fluid-dynamic thrust bearing 126 or in the same direction of the bearing force F _{fluid of} the fluid dynamic thrust bearing 126 or remains neutral when the spindle motor is in lateral mounting position.

The axial force F _{fluid of} the fluid dynamic thrust bearing 126 that _likes magnetic axial force F as well as the aerodynamic axial force F _aero and the weight F _G are determined so that during operation of the thrust bearing an altitude, ie an axial bearing gap width in the region of the thrust bearing 126 between 4 to 100 microns. The typical forces move in a fan in the range of, for example, 0.5 to 1 Newton. For interpretation of the magnetic axial force F _mag can also in the embodiment of 2 a pull ring, according to the pull ring 38 of the 1 , below the front of the rotor magnet 134 be arranged.

The rotor component 124 can according to the invention also in one piece with the fan 140 be formed and made of light metal or plastic, for example.

This applies to all described embodiments of the invention.

The spindle motor according to 2 has the advantage that it is ready to use even without installation in a flange or a base plate and can be used flexibly for any application by the bushing 112 mounted and attached at its lower end accordingly. In particular, the design of the bearing bush 112 with a long extension in the axial direction and a relatively high-lying stator arrangement allows the spindle motor to secure secure. The spindle motor can be designed so that in the axial direction up to 70% of the bearing bush 112 over the stator arrangement 132 protrude and thus can be used to attach the spindle motor.

LIST OF REFERENCE NUMBERS

10

baseplate

12, 112

bearing bush

14, 114

wave

14a, 144a

stop member

16, 116

bearing gap

18, 118

axis of rotation

20, 120

radial bearings

20a, 120a

Bearing groove structures

22, 122

radial bearings

22a, 122a

Bearing groove structures

24, 124

Rotor component (hub)

24a, 124a

approach

24b, 124b

edge

26, 126

thrust

28, 128

recirculation

30, 130

cover

32, 132

stator

34, 134

rotor magnet

36, 136

seal gap

38

pull ring

40, 140

fan

42, 142

direction

44, 144

direction

_Feroero

Aerodynamic axial force

F _fluid

Fluid dynamic axial force

F _G

weight force

F _likes

Magnetic axial force

d

axial offset

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 102007036790 A1 [0002]

Claims (7)

Spindle motor, in particular for driving a fan, comprising: a stationary engine component ( 10 . 12 ; 112 ), a rotatable relative to the stationary engine component engine component ( 24 ; 124 ), a fluid dynamic storage system ( 20 . 22 . 26 ; 120 . 122 . 126 ) for the rotary mounting of the rotatable engine component ( 24 ; 124 ) relative to the stationary engine component ( 10 . 12 ; 112 ), wherein the fluid dynamic bearing system at least one fluid dynamic radial bearing ( 20 . 22 ; 120 . 122 ) and at least one fluid dynamic thrust bearing ( 26 ; 126 ), means for generating an axial force for biasing the fluid dynamic thrust bearing ( 26 ; 126 ), and an electromagnetic drive system ( 32 . 34 ; 132 . 134 ) for the rotary drive of the rotatable engine component, which comprises a stationary motor component arranged on the stator assembly ( 32 ; 132 ) and arranged on the rotatable motor component rotor magnet ( 34 ; 134 ), characterized in that the means for generating the axial force comprises means for generating an aerodynamic force ( 40 ; 140 ). Spindle motor according to claim 1, characterized in that the means for generating the axial force means for generating a magnetic force ( 32 . 34 . 28 ; 132 . 134 ). Spindle motor according to claim 1 or 2, characterized in that the means for generating the magnetic force, the stator assembly ( 32 ; 132 ) and the rotor magnet ( 34 ; 134 ) of the electromagnetic drive system axially spaced apart by an offset (d) and generating an axial magnetic force (F _mag ) corresponding to the axial force (F _fluid ) of the fluid dynamic thrust bearing (FIG. 26 ; 126 ) counteracts. Spindle motor according to one of claims 1 to 3, characterized in that the means for generating the magnetic force the rotor magnet ( 34 ) of the electromagnetic drive system and a ferromagnetic pull ring ( 38 ), wherein the pull ring on the stationary engine component ( 10 ) axially below the rotor magnet ( 34 ) and together with the rotor magnet ( 34 ) generates an axial magnetic force (F _mag ) which corresponds to the axial force of the fluid dynamic thrust bearing (F) ( 26 ) counteracts. Spindle motor according to one of claims 1 to 4, characterized in that the means for generating the aerodynamic force a fan ( 40 ; 140 ), which on the rotatable engine component ( 24 ; 124 ) and generates an axial aerodynamic force which corresponds to the axial force (F _fluid ) of the fluid-dynamic thrust bearing ( 26 ; 126 ) counteracts. Spindle motor according to one of claims 1 to 5, characterized in that on the rotatable engine component ( 24 ; 124 ) axial forces (F _aero , F _fluid , F _G , F _mag ) are tuned so that in the region of the fluid dynamic thrust bearing ( 26 ; 126 ) an altitude of the rotatable engine component ( 24 ; 124 ) relative to the stationary engine component ( 12 . 112 ) of 4-100 micrometers. Fan with a spindle motor according to one of claims 1 to 6 for driving a fan wheel ( 40 ; 140 ).

Images