CH670323A5 - - Google Patents

Description

DESCRIPTION

The invention relates to a disk storage drive with a collectorless drive motor, which has a stator provided with a winding and an outer rotor coaxially encompassing the stator with the formation of an essentially cylindrical air gap with a permanent magnetic motor magnet and a soft magnetic yoke, as well as with a concentric with the yoke the yoke, which is connected in a rotationally fixed manner and which is provided with a disk carrier section which can be inserted through the central opening of the disk for the purpose of accommodating at least one storage disk arranged in a clean room.

In a known disk storage drive of this type (FIGS. 3 and 4 of DE-OS 31 35 385), a relatively solid body is provided as a hub for receiving the storage disk or storage disks, which has bearing webs running in the axial direction in the region of the disk support section, with a shaft is connected in a rotationally fixed manner via a bearing bush pressed or cast into the hub and with the plate carrier section a smaller part of the axial dimension of the magnetically active stator and rotor parts, ie the stator winding and the motor magnet interacting therewith.

With disk storage, there is an increasing need to reduce the space requirement of the storage. The invention is accordingly based on the object of creating a disk storage drive which takes up particularly little space and thus permits minimization of the disk storage dimensions, in particular in the axial direction.

According to the invention, this object is achieved in that the stator winding and the motor magnet interacting therewith are accommodated at least half of their axial dimension within the space enclosed by the plate carrier section of the hub. In this construction, the magnetically active parts of the drive motor largely lie within the space which is used to hold the storage disks, in particular magnetic hard storage disks, but also other types of storage disks, e.g. optical disks, is needed anyway.

The stator winding and the motor magnet interacting therewith are preferably accommodated at least to two thirds of their axial dimension within the space enclosed by the plate carrier section. A particularly space-saving overall arrangement is obtained if the ma5

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magnetically active stator and rotor parts sit essentially completely within this space.

The diameter of the central opening of storage disks, for example magnetic hard storage disks, is standardized and its size is therefore limited to a fixed value. On the other hand, the application of the drive energy requires a certain motor size. The conditions are particularly critical in known small storage disks with a central opening diameter of e.g. only 25 mm. In order to provide as much space as possible for the magnetically active motor parts in the diameter-limited space of the disk center opening, in a further embodiment of the invention the wall thickness of the disk carrier section of the hub is minimized as much as is possible with regard to the mechanical strength. The wall thickness of the plate carrier section is expediently at most equal to and preferably less than the wall thickness of the part of the magnetic yoke which is concentric with it.

Preferably, the plate support section further has a cylindrical outer peripheral surface, i.e. a circumferential surface free of the known bearing webs or ribs, because this also contributes to providing a maximum cross section, taking into account the fixed predetermined diameter of the central opening of the storage disks and the necessary mechanical strength of the hub for the magnetically active motor parts.

At least the surface parts of the hub lying in the clean room must have no or practically no dirt particles, e.g. in long-term use of the disk storage drive, e.g. release into the clean room due to oxidation processes. The hub preferably consists of a material which is suitable for clean rooms even after machining, i.e. a material that, even after machining and without subsequent corrosion-inhibiting after-treatment, meets the strict cleanliness conditions required for disk storage in the clean room that holds the disk. Such a design of the hub allows the outer circumferential surface of the plate carrier section to be machined for centricity with the axis of rotation after assembly of the hub with the drive motor, e.g. to grind or overturn. Such fine machining of the fully assembled hub is often necessary in order to meet the extreme demands on concentricity in disk storage or the minimization of the impact of the hub. A hub made of light metal, preferably aluminum or an aluminum alloy, has proven particularly expedient. Alloy hubs remain clean-room compatible even after machining without further treatment. They can be overturned, for example by means of a diamond tool, while maintaining the required accuracy, which is less expensive than grinding, in particular in the case of a plate carrier section with a cylindrical outer circumferential surface. The hub is preferably extruded or cast and hot pressed onto the magnetic yoke. In principle, other options for connecting the hub and the yoke are also possible, e.g. a mutual gluing of these parts.

The magnetic yoke can be cup-shaped in a manner known per se. It is more advantageous to provide an annular magnetic yoke, in which case a magnetic shielding ring is expediently inserted in the hub, which extends radially inward essentially from the axial end of the annular magnetic yoke on the clean room side. In this way, the necessary guidance of the magnetic flux as well as an effective magnetic shielding of the storage disks from the drive motor are achieved. The combination of return ring and shielding ring can be manufactured more cost-effectively than a pot. The shielding ring can be kept relatively thin, as a result of which the overall axial dimension of the drive can be further reduced or, with the axial dimension remaining the same, more space is available for an end wall of the hub at the closed end of the assembly consisting of the hub, magnetic yoke and motor magnet. The magnetic yoke can expediently be designed as a rolled ring, in particular a steel ring, or as a tube section.

The rotor and the hub can be firmly connected to a shaft which is supported in a bearing arrangement which is accommodated at least partially within the stator of the drive motor. In this case, a bearing bush receiving the shaft can expediently be integrally formed on the yoke, if this is pot-shaped, or preferably on the hub. There is therefore no need for a separate component for the socket. According to a modified further development, the rotor and the hub can also be rotatably mounted on a fixed shaft via a bearing arrangement, the supply line of the stator winding being expediently guided through the fixed shaft to the outside of the drive.

With the unit consisting of rotor and hub, a control magnet, e.g. in the form of a control magnetic ring, which interacts with a stationary magnetic field-sensitive rotary position sensor arrangement, the task of which is to provide commutation control signals and, if appropriate, additional control signals, e.g. generate a pulse for a predetermined reference position of the rotor. The control magnet is expediently located on the axially open side of the unit consisting of rotor and hub. It can be axially aligned with the motor magnet. If necessary, the motor magnet itself can also be used as a control magnet. The rotational position sensor arrangement is advantageously mounted on a printed circuit board which axially faces the side of the unit consisting of rotor and hub which is open in the axial direction.

The invention is explained in more detail below on the basis of preferred exemplary embodiments. In the accompanying drawings:

1 shows a section through a disk storage drive according to the invention along the line I-I of FIG. 2,

2 shows a schematic section along the line II-II of FIG. 1,

3 shows a section similar to FIG. 2 for a modified embodiment,

4 shows an axial section through a disk storage drive according to a further modified embodiment of the invention,

5 is a partial axial section for a further modified embodiment,

6 shows an axial partial section for an embodiment with a magnetic yoke ring and a separate axial shielding ring,

Fig. 7 is a partial axial section through a further away. delte embodiment of the disk drive with a fixed shaft, and

Fig. 8 is a partial section similar to Fig. 7 for an embodiment with a fixed shaft.

1 and 2, the drive motor, designated as a whole by 18, has a stator 19 with a stator laminated core 10. The stator core 10 is radially symmetrical with respect to a central axis of rotation 10A and is provided with an annular central portion 10B. The stator laminated core 10 forms six stator poles IIA to 11F which, in the plan view according to FIG. 1, are essentially T-shaped and are arranged at a mutual angular distance of 60 °. Instead of a laminated core, for example, a sintered iron core can also be provided. Pole shoes 12A to 12F of the stator poles determine5

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together with a permanent magnetic motor magnet 13, an essentially cylindrical air gap 14. The motor magnet 13 is radially magnetized in the circumferential direction in the circumferential direction, as indicated in FIG. it has four sections 13A to 13D, and on the inside of the ring-shaped motor magnet 13 facing the air gap 14 there are alternately two magnetic north and two magnetic south poles 15 and 16. The poles 15, 16 have a width in the exemplary embodiment shown of essentially 180 ° egg (corresponding to 90 ° physically). In this way, an approximately rectangular or trapezoidal magnetization is obtained in the circumferential direction of the air gap 14.

The motor magnet 13 is mounted in an outer rotor pot 17, which serves as a magnetic yoke and serves as a magnetic shield, made of soft magnetic material, e.g. glued into the pot. The pot 17 and the magnet 13 together form an outer rotor 30. The outer rotor pot 17 has an end wall 17A and a cylindrical peripheral wall 17B. The motor magnet 13 can in particular be a rubber magnet or a plastic-bonded magnet. Instead of a one-piece magnetic ring, cup-shaped magnetic segments can also be glued into the pot 17 or fixed there in some other way. Particularly suitable materials for the magnetic ring or the magnetic segments are magnetic material in a synthetic binder, a mixture of hard ferrite and elastomeric material, ceramic magnetic material or samarium cobalt. While each of the poles extends over practically 180 ° egg in the illustrated embodiment, it is also possible to work with narrower poles. In the interest of high motor power, the rotor pole width should be at least 120 ° ei.

The stator poles IIA to 11F limit a total of six stator slots 20A to 20F. A three-strand stator winding is inserted into these slots. Each of the three strands comprises two 120 ° ci-longed coils 21, 22; 23, 24 and 25, 26, each of which is wound around one of the stator poles 11A to 11F. As shown in FIG. 1, the two coils of each strand connected in series lie diametrically opposite one another. The coils are preferably bifilar wound in a manner not shown. As can be seen from the schematic illustration in FIG. 1, any overlap between the coils 21 to 26 is avoided. Particularly short end windings 27 (FIG. 2) are obtained in this way. The slot openings 28A to 28F can be between 3 ° egg and 30 ° egg wide. If the stator windings are provided, the slots 20A to 20F can be filled excellently. Closures for the slot openings 28A to 28F are generally not necessary.

The present motor structure enables a relatively large stator inner hole 29 to be achieved because the depth of the stator grooves 20A to 20F can be kept comparatively small. Relationships between the diameter I of the inner hole 29 and the stator outer diameter E in the region of the pole shoes 12 of at least 0.35 can easily be achieved. The value of I / E is preferably in the range from 0.4 to 0.7. The ratio L / E between the axial length L of the stator iron and the stator outer diameter E is preferably equal to or less than 1. These dimensional relationships are of particular importance with regard to stable mounting of the rotor. Such storage is of great importance in the case of drives for disk storage systems. In addition, the total resistance of the stator winding is kept particularly low.

To mount the rotor 30, a stub shaft 32 is fastened in the middle of the outer rotor pot 17 via a bearing bush 31 formed on the pot 17, which is axially. spaced ball bearings 33 is supported in a cylindrical sleeve 34 which the stator core

10 carries and is attached to a mounting flange 35.

A hub 37 of a hard disk memory, preferably made of light metal, is placed on the outer rotor pot 17, not shown in FIG. 1, provided with a cylindrical plate carrier section 36, for example shrunk on. One or more permanent storage disks 39, preferably magnetic permanent storage disks, are placed on the disk carrier section 36, the disk carrier section 36 reaching through a central opening 40 of the storage disks 39, which are kept at a mutual axial distance via appropriate spacers 41 and by means of a clamping device, not shown, known per se With respect to the hub 37 are set. In the embodiment illustrated in Fig. 2, the magnetically active stator and rotor parts of the drive motor 18, i.e. the motor magnet 13 and the stator winding 21 to 26, to a little more than two thirds of their axial dimension in the space 46 which is enclosed by the plate support section 36. The wall thickness of the plate carrier section 36 of the hub 37 is smaller than the wall thickness of the cylindrical circumferential wall 17B of the pot 17 which forms the magnetic yoke, as a result of which a maximum cross section is provided for the motor parts 13, 17, 19 in the fixed predetermined central opening 40. In particular, the wall thickness of the plate carrier section 36 is dimensioned as small as is still possible with regard to the mechanical strength. In order to increase the dimensional stability of the hub 37, in the region of the open end of the unit consisting of the hub 37, the outer rotor cup 17 and the motor magnet 13, it carries a thickened flange 47 projecting radially outwards, which at the same time serves to axially support the hard disk 39 closest to the flange.

The hub 37 lies together with the storage disks 39 supported on it in a clean room 49 which is delimited from housing parts of the disk storage in a manner which is not known per se and which is known per se. The mounting flange 35 forms part of the clean room boundary towards the lower side in FIG. 2. The upper bearing 33 in FIG. 2 sits between a shoulder 51 of the sleeve 34 and a spacer ring 52, the side of which, facing away from the bearing 33, bears against the underside of the bearing bush 31. The stub shaft 32 is spherical at its lower end 53 and expediently mounted in an axial bearing, not shown. A retaining ring 55 is arranged in an annular groove 54 of the shaft 32 near the lower end 53, against the top of which two plate springs 56 are supported. The plate springs 56 rest on an intermediate ring 57. The lower ball bearing 33 sits between the intermediate ring 57 and a further shoulder 58 of the sleeve 34.

The mounting flange 35 carries a circuit board 38, on which the commutation electronics and / or other circuit components, for example for speed control, can be accommodated if necessary. In particular, three rotary position sensors 42, 43, 44 are located on the printed circuit board 38, which in the exemplary embodiment shown are magnetic field sensors, for example Hall generators, field plates, magnetic diodes and the like. Bistable switching Hall ICs are particularly advantageous. The use of 180 ° egg-wide rotor poles 15, 16 allows the motor magnet 13 to be used directly as a control magnet for the position sensors 42, 43, 44. In the embodiment according to FIG. 2, the rotary position sensors 42, 43, 44 are axially opposite the magnet 13 controlling them. However, it is also possible, for example, to arrange the rotary position sensors in the manner indicated by dashed lines in FIG. 2 in such a way that they are radially opposite the controlling magnet 13. The rotational position sensors 42, 43, 44 are expediently positioned in the circumferential direction with respect to the coils 21 to 26 such that the changes in the sensor switching states essentially coincide with the zero crossings of the associated coil voltages. This

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1 is achieved in that the rotary position sensors are offset by 15 ° with respect to the center of the slot openings 28A, 28B and 28C.

The embodiment according to FIG. 3 differs from that according to FIG. 2 essentially in that a control magnet 45 separate from the motor magnet 13 is provided for actuating the rotary position sensors 42, 43, 44. The control magnet 45 is located radially outside the motor magnet 13 on the underside of a flange 17C which projects radially outward from the peripheral wall 17B of the outer rotor cup 17 at its open end. In the embodiment according to FIG. 3, the outer rotor pot 17 and the hub 37 'are flush with one another at the open end. At 59 a connection of one of the coils 21, 26 to a contact of the printed circuit board 38 is indicated. A connecting cable 60 extends outward from the printed circuit board 38 via an opening 61 in the mounting flange 35.

FIG. 4 illustrates a further embodiment of the disk storage drive, in which, in deviation from the embodiment according to FIGS. 2 and 3, the hub 64 corresponding in function to the previously explained hub 37 has an end wall 64A resting against the end wall 17A of the outer rotor pot 17, on which one Bearing bush 65 is formed for the shaft 32. At the end of the plate carrier section 66 of the hub 64 remote from the end wall 64A there is a radially outwardly angled flange 67 which merges into a peripheral wall 68 which is concentric with the plate carrier section 66 and has a larger diameter than the plate carrier section 66. The peripheral wall 68 surrounds the flange 17C of the pot 17 radially on the outside. The meeting point of the flange 17C and the peripheral wall 68 is sealed by means of lacquer, adhesive or the like in the manner indicated at 69. As in the case of FIG. 3, this prevents dirt particles from being flung radially outward from the flange 17C and penetrating into the clean room 49. The control magnet 45 which interacts with the rotational position sensors (only the sensor 42 of which is illustrated in FIG. 4) is axially aligned with the motor magnet 13 and is attached to the side of the magnet 13 which is remote from the end wall 17A. The outer rotor pot 17 has been pulled down so far in FIG. 4 that it also encompasses the control magnet 45. The space which remains free between the end wall 17A and the end of the magnet 13 facing this end wall is filled with an adhesive or another filler material 70. The bearing arrangement of the shaft 32 formed by the two ball bearings 33 is sealed off from the motor interior and thus also from the clean room 49 by means of a magnetic fluid seal 72. The magnetic fluid seal 72 consists of two annular pole pieces 73, 74, a permanent magnet ring 75 between these two pole pieces and a magnetic liquid (not shown) which is introduced into an annular gap 76 between the magnetic ring 75 and a section 77 of the shaft 32. Seals of this type are known under the name “Ferrofluidic Seal”. The seal 72 particularly effectively prevents the passage of dirt particles from the bearing arrangement into the clean room 49. The seal 72 is located adjacent but axially at a distance from the bearing bush 65. This prevents magnetic liquid from being pulled out of the seal 72 by capillary action.

As can be seen from FIG. 4, the magnetically active stator and rotor parts are housed essentially completely within the space 46 enclosed by the plate carrier section 66. 4, an axial bearing 79 for the shaft 32 is also illustrated. The bearing 79 is seated on a spring clip 80 which in turn is attached to a cover 81 which is inserted into the end of a sleeve 82 which is remote from the clean room 49. Similar to the sleeve 34 of the embodiment according to FIGS. 2 and 3, the sleeve 82 receives the bearings 33, but is integrally connected to the mounting flange 83 corresponding to the mounting flange 35.

The axial bearing 79, like the spring clip 80, is preferably electrically conductive. This makes it possible to discharge electrostatic charges on the shaft 32 via the bearing 79 and the bracket 80.

The printed circuit board 38 is connected to the mounting flange 83 via an adhesive layer 84 which lies in a groove 85 in the mounting flange 83. In order to further reduce the axial overall height of the disk storage drive, the printed circuit board 38 is provided with openings 86 in the region of the rotational position sensors, and the rotational position sensors are immersed in the groove 85 and these openings 86. In the area of the contact point between the upper pole piece 73 and the inner circumferential wall 87 of the sleeve 82, an additional seal, indicated at 88, is provided by means of a coating lacquer or the like.

5 is largely similar to that of FIG. 4. Deviating from there, in this case the bearing bush 31 is integrally formed on the end wall 17A of the external rotor pot 17 which acts as a magnetic shield. In the end wall 17A, three threaded holes 90 are provided which are offset from one another in the circumferential direction by 120 °. The threaded holes 90 are used to attach the non-illustrated clamping device for the hard disk 39 (FIG. 2). Under the end wall 17A there is a cover ring 91 which seals the engine interior from the clean room 49 in the area of the threaded holes 90. Again, the magnetically active stator and rotor parts of the drive motor are for the most part their axial length in the space 46, which is enclosed by the plate carrier section 36 'of the hub 37', which in this case corresponds to that according to FIG. 3.

6 shows a further modified embodiment of the invention, which essentially differs from the previously explained embodiments in that a soft magnetic return ring 94 and a separate, likewise soft magnetic shielding ring 95 are provided instead of the outer rotor pot 17. The shielding ring 95 extends radially inward from the axial end 96 of the yoke ring 94 on the clean room side. The wall thickness of the shielding ring 95 can be kept considerably smaller than that of the yoke ring 94. The threaded holes 97 corresponding to the function of the threaded holes 90 in FIG. 5 are formed in the end wall 98 of a hub 99, on which the bearing bush 100 for the shaft 32 is molded. The shielding ring

95 is provided in the area of the threaded holes 97 with depressions 101, which allow the use of the full thread length of the threaded holes 97. Filling material 70 is in the area between the upper end of the motor magnet 13 in FIG. 6, the end

96 of the inference 94 and the radially outer part of the shield ring 95 are provided. The magnetically active rotor and stator parts lie more than two thirds in the space which the cylindrical plate carrier section 102 of the hub 99 encloses.

The yoke ring 94 can be a rolled ring, in particular a steel ring, or a pipe section. The production is simplified compared to the use of the outer rotor pot 17. In addition, axial length is additionally saved because, on the one hand, the wall thickness of the shielding ring 95 can be kept small and, on the other hand, no space is lost, as is the case when using the pot 17 for its inevitable radius r (FIG. 5) at the transition point between the Circumferential wall 17B and the end wall 17A is required. The axial installation space that has become available can also be used to cover the end wall 98

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to give greater wall thickness and thus to increase the length of the threaded holes 97.

While the shaft 32 rotates in operation in the embodiments according to FIGS. 1 to 6, FIGS. 7 and 8 show embodiments with a standing shaft. The standing shaft 105 according to FIG. 7 is mounted in the disk storage in a manner not shown in detail. A hub 107 is rotatably mounted on the shaft 105 via a first ball bearing 106. The hub 107 has an end wall 108 with a molded-on bearing bush 109, a plate carrier section 110 and, on the side remote from the end wall 108, a radially outwardly projecting reinforcing flange 111. The hub 107 is connected to the soft magnetic yoke ring 94. The soft magnetic shielding ring 95 rests on the inside of the end wall 108. In this case, the printed circuit board 38 with the rotational position sensors, of which only the sensor 42 is illustrated in FIG. 7, is suspended on the stator laminated core 10 via supports 112 (FIG. 8). A motor cover 114 is mounted on the shaft 105 via a second ball bearing 113, which tightly closes the motor at the axial end remote from the end wall 108. To the

On the outside of the bearings 106, 113 there is in each case a magnetic fluid seal 72 or 72 'of the type explained in detail with reference to FIG. 4. The magnetic fluid seals 72, 72' ensure that the bearing arrangement 5 is sealed off from the clean room 49, the drive motor as a whole can sit in the clean room. The connections of the stator winding and / or of the electronic components mounted on the printed circuit board 38 are led out via a cable indicated at 115, which is inserted into an axial groove 116 of the shaft 105.

The embodiment according to FIG. 8 differs from that according to FIG. 7 essentially in that, instead of the yoke ring 94 and the shielding ring 95, a one-piece pot 117, corresponding to the pot 17, made of soft magnetic material with a front wall 117A and a peripheral wall 117B is provided.

In both embodiments of FIGS. 7 and 8, the magnetically active stator and rotor parts of the drive motor are located within the space enclosed by the plate carrier section 110.

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Claims (13)

670 323 1. Disk storage drive with a brushless drive motor, which has a stator provided with a winding and an outer rotor coaxially encompassing the stator with the formation of an essentially cylindrical air gap with a permanent magnetic motor magnet and a soft magnetic yoke, as well as one concentric with the yoke and with the yoke Non-rotatably connected hub which is provided with a plate carrier section which can be inserted through a central opening of the storage plate for the purpose of accommodating at least one storage plate arranged in a clean room, characterized in that the stator winding (21 to 26) and the motor magnet (13) interacting therewith at least half of its axial longitudinal dimension is accommodated within the space (46) enclosed by the plate carrier section (36, 36 ', 66, 102, 110) of the hub (37, 37', 64, 99, 107). 2. Disk storage drive according to claim 1, characterized in that the stator winding (21 to 26) and the cooperating motor magnet (13) substantially completely within that of the plate support section (36 ', 66, 110) enclosed space (46) are housed. 2nd PATENT CLAIMS 3. Disk storage drive according to one of the preceding claims, characterized in that the wall thickness of the disk support section (36, 36 ', 66, 102, 110) is at most equal to and preferably less than the wall thickness of the part (17B, 94, 117B) concentric therewith magnetic inference. 4. Disk storage drive according to one of the preceding claims, characterized in that the disk support section (36, 36 ', 66, 102, 110) has a cylindrical outer peripheral surface. 5. Disk storage drive according to one of the preceding claims, characterized in that the hub (37, 37 ', 64, 99, 107) consists of a material, preferably light metal, which is also suitable for clean rooms after machining. 6. Disk storage drive according to one of the preceding claims, characterized in that the outer peripheral surface of the disk support section (36, 36 ', 66, 102, 110) after assembly of the hub (37, 37', 64, 99, 107) with the drive motor (18) is machined to centricity with the axis of rotation (10A), preferably ground or turned. 7. Disk storage drive according to one of the preceding claims, characterized in that the hub (37, 37 ', 64, 99, 107) is extruded or cast and preferably hot-pressed onto the magnetic yoke (17, 94, 117). 8. Disk storage drive according to one of the preceding claims, characterized in that the magnetic yoke (94) is ring-shaped and preferably in the hub (99, 107) a magnetic shielding ring (95) is used, which is substantially from the clean room-side axial end of the annular inference (94) extending radially inwards. 9. Disk storage drive according to one of the preceding claims, characterized in that the rotor (30) and the hub (37, 37 ', 64, 99) are fixedly connected to a shaft (32) which is in an at least partially inside the stator ( 19) of the drive motor (18) accommodating the bearing arrangement (33) is rotatably supported and preferably a bearing bush (31, 65, 100) receiving the shaft (32) is integrally formed on the hub (64, 99) or the magnetic yoke (17). 10. Disk storage drive according to one of claims 1 to 8, characterized in that the rotor (94, 107) and the hub (110) via a bearing arrangement (106, 113) rotatably mounted on a fixed shaft (105) and preferably the feed lines ( 115) the stator winding (21 to 26) are guided through the fixed shaft (105) to the outside of the drive. 11. Disk storage drive according to one of claims 9 or 10, characterized in that the bearing arrangement (33, 106, 113) is sealed off from the clean room (49) by means of at least one magnetic fluid seal (72, 72 '). 12. turntable player drive according to one of the preceding claims, characterized in that a control magnet (45) is connected to the unit consisting of rotor and hub, which cooperates with a stationary, magnetic field-sensitive rotary position sensor arrangement (42, 43, 44) which is mounted on a printed circuit board (38) which axially faces the side of the unit consisting of rotor and hub which is open in the axial direction. 13. Disk storage drive according to one of the preceding claims, characterized in that the stator winding (21 to 26) and the cooperating motor magnet (13) at least two thirds of its axial length dimension within that of the plate carrier section (36, 36 ', 66, 102, 110) of the hub (37, 37 ', 64, 99, 107) of the enclosed space (46).