DE102020131948B3 - Hard disk drive - Google Patents

Abstract

The invention relates to a spindle motor with a stationary motor component (10, 12, 14, 114) and a rotatable motor component (16, 36, 18, 118), which is rotatably mounted relative to the stationary motor component by means of a fluid dynamic bearing system and is driven by an electromagnetic drive system (34 , 36) is rotatably driven, the rotatable motor component comprising a hub (16), the ratio between the axial height h of the hub (16) measured from a lower bearing surface (16a) to an upper edge (16b) of the hub (16) and the mass m of the hub (16) without attachments is greater than 0.47 mm/g.

Description

The invention relates to a hard disk drive having a housing filled with helium and a plurality of storage disks arranged therein, which are rotatably driven by a spindle motor.

The data sheet from NMB Technologies Corporation, 39830 Grand River Avenue, Suite B-1, Novi, Mi 48375, USA describes a spindle motor of the type BLCD FDB SP2B, Brushless 3, phase DC motor from MinebeaMitsumi, see URL https: // www.datasheetarchive.com/whats_new/aa4ffb5921a34a38efee19fa328da3 ce.html. This spindle motor comprises a stationary motor component and a rotatable motor component which is rotatably mounted relative to the stationary motor component by means of a fluid dynamic bearing system and is rotatably driven by an electromagnetic drive system, the rotatable motor component including a hub, and wherein the ratio between the axial height of the hub, measured from a lower contact surface to an upper edge of the hub, and the mass of the hub without attachments is greater than 0.47 mm / g.

The publications DE 10 2012 006 021 A1 , DE 10 2018 124 286 A1 and DE 10 2011 101 827 A1 disclose spindle motors for driving hard disk drives.

Hard disk drives are still one of the cheapest mass storage media. In the meantime, hard disk drives have a storage capacity of up to a few tens of terabytes, with up to ten storage disks being attached to the spindle motor in a stacked manner in hard disk drives.

Due to the large number of storage disks and the height of the hub of the spindle motor required for this, the rotating motor component has a considerable mass, especially since the hub of the spindle motor is usually made of steel and the storage disks are made of glass.

A large rotor mass is synonymous with a high moment of inertia, which on the one hand increases the power consumption of the hard disk drive and on the other hand worsens the behavior of the hard disk drive in the event of shock.

It is therefore the object of the invention to improve a hard disk drive with regard to its energy consumption and its shock resistance.

According to the invention, this object is achieved by a hard disk drive with the features of claim 1.

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

The hard disk drive according to the invention comprises a housing filled with helium and eight to ten storage disks arranged therein, which are rotatably driven by a spindle motor, the spindle motor comprising a stationary motor component and a rotatable motor component which is rotatably mounted relative to the stationary motor component by means of a fluid dynamic bearing system and is supported by a electromagnetic drive system is rotatably driven, wherein the rotatable motor component comprises a hub. The ratio between the axial height of the hub, measured from a lower support surface of the storage disks to an upper edge of the hub, and the mass of the hub without attachments is greater than 0.47 mm / g.

The ratio between the axial height of the hub and the mass of the hub is particularly preferably more than 0.50 mm / g.

In an even more preferred embodiment, the ratio between the axial height of the hub and the mass of the hub is greater than 0.55 mm / g.

The maximum height of the hub is essentially given due to the standardized form factors for hard disk drives. Known form factors are e.g. B. 3.5 "and 2.5".

The mass of the hub is particularly dependent on the material used for the hub, in particular steel here.

According to the invention, the aim is therefore to keep the mass of the hub low or to reduce it, so that the ratio between the height and the mass of the hub is as large as possible.

For this purpose, it is provided in particular that, in addition to the existing recesses and bores in the hub, further bores or recesses are provided to reduce mass.

These bores and recesses for reducing the mass of the hub are preferably placed in such a way that the structural rigidity of the hub is impaired as little as possible.

Previously, the hub of a spindle motor used to drive a 3.5-inch hard disk drive was typically between 42 and 43 grams.

The Reduce the mass of the hub to, for example, 34 to 37 grams without noticeably impairing the structural rigidity. This corresponds to a mass reduction in the range of 20%.

The typical height of a hub of a spindle motor for a 3.5 inch hard disk drive is between 18 mm and 20 mm.

The weight-relieved bores and recesses can be designed, for example, from the top of the hub as blind bores or as through bores from the top to the bottom.

Furthermore, in the approximately bell-shaped or pot-shaped hub, the annular cavity for receiving the electrical stator can be enlarged upward in the axial direction.

Hard disk drives are filled with helium or a light inert gas to minimize drag from the rotating storage disks.

The invention is described in more detail below on the basis of exemplary embodiments with reference to the drawings.

• 1 zeigt einen Schnitt durch eine erste Ausgestaltung eines Spindelmotors eines erfindungsgemäßen Festplattenlaufwerks mit auf der Nabe befestigten Speicherplatten.
• 2 zeigt einen Schnitt durch eine zweite Ausgestaltung des Rotorbauteils eines Spindelmotors mit darauf befestigten Speicherplatten.
• 3 zeigt einen Schnitt durch eine dritte Ausgestaltung des Rotorbauteils eines Spindelmotors mit darauf befestigten Speicherplatten.
• 4 zeigt einen Schnitt durch das Rotorbauteil des Spindelmotors von 1.

This results in further features and advantages of the invention.

• 1 shows a section through a first embodiment of a spindle motor of a hard disk drive according to the invention with storage disks attached to the hub.
• 2 shows a section through a second embodiment of the rotor component of a spindle motor with storage disks fastened thereon.
• 3 shows a section through a third embodiment of the rotor component of a spindle motor with storage disks fastened thereon.
• 4th FIG. 13 shows a section through the rotor component of the spindle motor of FIG 1 .

1 shows a section through a spindle motor of a hard disk drive according to the invention with a fluid dynamic bearing system. The spindle motor for driving the hard disk drive comprises a fluid dynamic bearing system with two conical fluid dynamic bearings which are constructed essentially identically. The invention is not limited to spindle motors with two conical fluid dynamic bearings. Rather, other known designs of fluid dynamic bearings or roller bearings can just as well be used for the rotary bearing of the spindle motor.

The spindle motor includes a base plate 10 with a hole in which a shaft 12th is rotatably received. The wave 12th is preferably by means of an interference fit and / or by means of adhesive in the base plate 10 attached.

The bearing system is designed as a conical fluid dynamic bearing system with two conical fluid dynamic bearings acting against one another. On the wave 12th are two bearing cones of the same type at a mutual axial distance 14th , 114 attached. Every bearing cone 14th , 114 has an annular, oblique to the axis of rotation 38 trained storage area. The base plate 10 , the wave 12th and the two bearing cones 14th , 114 form the fixed component of the bearing system or in connection with an electrical stator arrangement 34 they form the stationary motor component of the spindle motor.

The rotatable engine component includes a hub 16 relative to the shaft 12th and to the bearing cones 14th , 114 around an axis of rotation 38 is rotatably arranged. The hub 16 includes a central bearing bore with two conical recesses for receiving the bearing cones 14th , 114 . The recesses form two annular conical bearing surfaces that form the bearing surfaces of the bearing cones 14th , 114 each face opposite. Due to the conical design of the bearing surfaces, the conical bearings work at the same time as radial and axial bearings.

When assembling the bearing system, for example, the shaft 12th in the base plate 10 attached. Then the lower bearing cone 114 at the intended position on the shaft 12th assembled. After that the hub 16 over the wave 12th inserted and finally the upper bearing cone 14th at a specified axial distance from the lower bearing cone 114 on the wave 12th assembled. The mounting of the bearing system takes place in such a way that there is a defined axial bearing play between the bearing surfaces, the bearing play being dimensioned in such a way that, when the bearing rotates, the bearing surfaces of the bearing cones lying opposite one another 14th , 114 and the hub 16 each through an annular bearing gap 20th , 120 are separated from each other by a defined width. The camp crevice 20th , 120 usually have a width of a few micrometers and are filled with a bearing fluid, for example a bearing oil.

The camp crevice 20th , 120 the two conical bearings do not have a common fluid circuit, ie they are not connected to one another in a fluid-conducting manner. Instead, the two bearing gaps point 20th , 120 each has an outer and an inner open end, which are sealed by means of seals. Capillary seals in the form of capillary sealing gaps are preferably used as seals 22nd , 122 and 28 , 128 used. The capillary sealing gap 22nd , 122 and 28 , 128 are with the Bearing columns 20th , 120 connected and partially filled with bearing fluid. The fill level of the sealing gap 22nd , 122 and 28 , 128 varies with bearing fluid and is dependent on the operating status of the storage system.

The respective outer ends of the bearing gap 20th , 120 are through outer sealing gaps 22nd , 122 sealed, which are preferably designed as conical capillary seals. The outer sealing gaps 22nd , 122 form a fluid reservoir for the bearing fluid, which compensates for the temperature expansion of the bearing fluid and serves as a storage volume for the bearing fluid. The outer sealing gaps 22nd , 122 are each limited by an outer sealing surface of the bearing cone 14th , 114 and an opposing inner sealing surface of the hub 16 . The outer sealing gaps 22nd , 122 are each of a cover 18th , 118 covered that with the hub 16 are firmly connected. Between an inner edge of the respective cover 18th , 118 and a small gap remains in the shaft.

The ends of the bearing column lying inside the bearing system 20th , 120 are through internal sealing gaps 28 , 128 sealed by the outer circumference of the shaft 12th and an inner peripheral surface of the bearing bore of the hub 16 are limited. Along the inner sealing gap 28 , 128 can preferably use dynamic pump seals 30th , 130 be arranged. The dynamic pump seals 30th , 130 include groove structures that are on the surface of the shaft 12th and / or the opposite surface of the hub 16 are arranged. The groove structures act on that in the inner sealing gaps 28 , 128 Storage fluid located has a pumping action in the direction of the respective bearing gap 20th , 120 out. The respective outer sealing gaps 22nd , 122 open in the direction of the lower or upper end of the shaft 12th , while the internal sealing gaps 28 , 128 inside the warehouse in a free space 32 open out between the outer circumference of the shaft 12th and an inner periphery of the hub 16 is arranged. The free space 32 is for example by one on the outer circumference of the shaft 12th and / or on the inner circumference of the hub 16 provided groove or groove formed.

The bearing surfaces of the bearing cones 14th , 114 and / or the bearing surfaces of the hub 16 have bearing groove structures 26th , 126 on when the hub rotates 16 relative to the bearing cones 14th , 114 a pumping effect on that in the respective bearing gap 20th , 120 Exercise located bearing fluid. This arises in the respective bearing gap 20th , 120 a fluid dynamic pressure that makes the conical bearing in question load-bearing. The conical bearing surfaces have, for example, herringbone-like bearing groove structures 26th , 126 on that in the direction of the outer sealing gap 22nd , 122 have a larger number of branches than in the direction of the inner sealing gap 28 , 128 . Due to the larger number of branches on the outside of the bearing and the larger diameter of the associated conical bearing surface, the branches on the outside of the bearing produce the bearing groove structures 26th , 126 a greater pumping effect than the internal branches. This results in a total of each conical bearing in the interior of the bearing in the direction of the inner sealing gap 28 , 128 directed pumping action.

The two conical fluid bearings act against one another to the extent that they move the bearing fluid in the direction of the respectively assigned pump seal 30th , 130 pump so that the storage system as a whole is in equilibrium.

To allow the bearing fluid to circulate in the bearing gaps 20th , 120 ensure are in the bearing cones 14th , 114 so-called recirculation channels 24 , 124 intended. Through the bearing grooves 26th , 126 that will be in the camp crevices 20th , 120 located bearing fluid starting from the outer sealing gaps 22nd , 122 in the direction of the inner, second sealing gap 28 , 128 and the pump seals 30th , 130 promoted. The pump seals 30th , 130 pump the bearing fluid back into the interior of the bearing, and this flows through the recirculation channels 24 , 124 back to the outer sealing gaps 22nd , 122 . The recirculation channels 24, 124 initially run between the outer circumference of the shaft 12th and the inner circumference of the bearing cones 14th , 114 and then as bores radially outwards through the bearing cones 14th , 114 up to the transition area between the bearing gaps 20th , 120 and the outer sealing gaps 22nd , 122 .

The hub 16 is opposed to the stationary engine components by means of an electromagnetic drive system 10 , 12th , 14th , 114 driven in rotation. The spindle motor is an electronically commutated direct current motor, the drive system of which is an annular stator arrangement 34 includes multiple phase windings attached to the base plate 10 is attached. The stator assembly 34 is within a recess in the hub 16 on the base plate 10 arranged and lies a rotor magnet 36 directly opposite. The rotor magnet 36 is on an inner peripheral surface of the hub 16 arranged and through an air gap from the stator assembly 34 separated. By appropriately energizing the phase windings of the stator arrangement 34 an alternating electromagnetic field is generated, which acts on the rotor magnet 36 acts and the hub 16 and thus set the rotor rotating. On a separate component as a magnetic return path for the rotor magnet 36 can be omitted in the example shown because the hub 16 consists of steel and forms the magnetic return itself. The outer peripheral surface of the rotor magnet 36 located directly on an inner peripheral surface of the hub 16 on.

On the inner circumference of the hub 16 a step is preferably arranged which has a stop for the end face of the rotor magnet 36 forms and the face of the rotor magnet 36 partially covered. This stop facilitates the axial positioning of the rotor magnet 36 and the entry of the magnetic field lines into the hub serving as a magnetic return path 16 .

In the illustrated storage system with two separate conical bearings and each bearing gaps 20th , 120 with two open ends it is important that there is free space 32 and the openings of the sealing gaps which open into the interior of the bearing 28 , 128 as well as the sealing gap 22nd , 122 be ventilated so that on the border between that in the sealing gaps 28 , 128 , 22nd , 122 The storage fluid located and the surrounding air is at ambient pressure. The interior of the bearing is preferably ventilated through an axial blind hole arranged in the shaft 12a extending from the lower face of the shaft 12th over more than half the length of the shaft 12th up to the height of the free space 32 extends.

The axial blind hole 12a is via a first transverse bore 12b with a free space 40 below the inner cover 118 connected. This free space 40 is about the annular recess 48 in the hub 16 , in which the stator assembly 34 and a gap between the base plate 10 and the bottom of the hub 16 connected to the outside environment. Furthermore, there is the axial blind hole 12a at its closed end via a second transverse bore 12c with the free space 32 connected inside the warehouse. Thus there is free space 32 atmospheric pressure as well as in free space 40 and on the outside of the bearing in the area of the outer sealing gap 22nd .

Since the hard disk drive is filled with helium, the housing of the hard disk drive must have the necessary helium tightness. Hence the opening of the blind hole 12a in the wave 12th by means of a welded-in metal pin 44 hermetically sealed.

The upper free end of the shaft 12th has a threaded hole 42 and can be inserted into the threaded hole by means of a 42 screwed-in screw can be connected to a stationary component (not shown), which can, for example, be a housing component of the hard disk drive.

According to the invention measures are provided to the mass m the hub, which is preferably made of steel 16 to reduce, whereby the total mass of the rotor component is reduced or its total mass remains the same, while a greater load in the form of several storage disks 50 is mounted. The storage disks 50 preferably consist of a glass substrate and have a thickness of, for example, 0.5 to 0.6 mm.

To reduce their mass m owns the hub 16 one or preferably several blind bores 46 coming from the top of the hub 16 are introduced. Furthermore, the annular recess 48 in the hub 16 that are used to accommodate the stator assembly 34 serves to be enlarged in the axial direction upwards. This makes it possible to measure the mass of the hub without any add-on parts such as the rotor magnet 36 who have favourited covers 18th , 118 , the retaining clip 54 , the screws 56 who have favourited spacers 52 and the storage disks 50 for example to reduce from approx. 43 g by approx. 20% to 36 g.

Instead of blind holes 46 can in the hub 16 through bores may also be provided leading from the top of the hub 16 up to the area of the recess 48 pass. Furthermore, freely shaped recesses can be provided on the top of the hub. The holes 46 and the recesses 48 are in the places of the hub 16 provided which the structural rigidity of the hub 16 not affect.

With the spindle motor from 1 are a total of ten storage disks 50 on the hub 16 assembled. The lowest storage disk 50 lies on a horizontal support surface 16a the hub 16 on. The subsequent storage disks 50 are each through annular spacers 52 separately and parallel to the storage disk below 50 on the hub 16 assembled. The stack of storage disk 50 is held by a retaining clip 54 held that by means of screws 56 on the hub 16 is attached and on the top storage disk 50 of the stack pushes.

2 shows a section through another embodiment of a rotor component of a spindle motor.

The rotor component consists of the hub 16 , one on the inner circumference of the hub in the area of the recess 48 arranged rotor magnets 36 as well as from the covers covering the outer sealing gaps 18th , 118 .

The hub has a bearing surface on its lower circumferential surface 16a for supporting several storage disks 50 on which each by spacers 52 are separated from each other. In this embodiment, the stack of storage disks 50 a total of eight storage disks 50 on.

On top of the hub 16 is a retaining clip 54 attached to the top storage disk 50 of the stack presses and fixes the storage disk stack. The retaining clip 54 is by means of screw 56 on the hub 16 attached.

The height H the hub 16 , measured from the top of the support surface 16a up to an upper edge 16b the hub 16 , is 18.479 mm in this configuration.

The crowd m the hub 16 without attachments is, for example, 35 g. The relationship between the height H the hub 16 and their mass m is therefore h / m = 0.53 mm / g.

3 FIG. 11 shows another embodiment of a rotor component which has the same attachment parts as in FIG 2 are described. However, the stack consists of storage disks 50 a total of nine storage disks 50 that by means of the retaining clip 54 on the hub 16 are mounted.

The height H the hub 16 is, compared to 2 , slightly larger as the number of storage disks 50 is larger, for example 19.202 mm. The crowd m the hub without attachments is 35.5 g, for example.

The relationship between the height H the hub and the mass m the hub in this case is H / m = 0.54 mm / g.

4th shows the rotor component of 1, d . H. the hub 16 with all attachments, namely the rotor magnets 36 , the covers 18th , 118 , a total of ten storage disks 50 with spacers 52 and the retaining clip 54 that with the screw 56 on the hub 16 is fixed.

The height H the hub 16 in this exemplary embodiment is 19.837 mm. The crowd m the hub without attachments is 35.91 g, for example.

The relationship between the height H the hub 16 and the crowd m the hub 16 is in this embodiment H / m = 0.55 mm / g.

List of reference symbols

10

Base plate

12th

wave

12a, b, c

Drilling

14, 114

Bearing cone

16

hub

16a

Support surface

16b

upper edge

18.118

cover

20, 120

Bearing gap

22, 122

outer sealing gap

24, 124

Recirculation channel

26, 126

Bearing grooves

28, 128

inner sealing gap

30, 130

Pump seal

32

free space

34

Stator assembly

36

Rotor magnet

38

Axis of rotation

40

free space

42

Threaded hole

44

Metal pin

46

Blind hole

48

Recess

50

Storage disk

52

Spacers

54

Retaining clip

56

screw

H

Height of the hub

m

Mass of the hub

Claims (6)

Hard disk drive with a housing filled with helium and eight to ten storage disks (50) arranged therein, which are rotatably driven by a spindle motor, the spindle motor having a fixed motor component (10, 12, 14, 114) and a rotatable motor component (16, 36, 18, 118), which is rotatably mounted relative to the stationary motor component (10, 12, 14, 114) by means of a fluid dynamic bearing system and is rotatably driven by an electromagnetic drive system (34, 36), the rotatable motor component (16, 36, 18 , 118) comprises a hub (16), the ratio between the axial height h of the hub (16), measured from a lower support surface (16a) for the storage disks (50) to an upper edge (16b) of the hub (16), and the mass m of the hub (16) without attachments is greater than 0.47 mm / g. Hard disk drive according to Claim 1 , characterized in that the ratio between the axial height h of the hub (16) and the mass m of the hub (16) is greater than 0.50 mm / g. Hard disk drive according to one of the Claims 1 or 2 , characterized in that the ratio between the axial height h of the hub (16) and the mass m of the hub (16) is greater than 0.55 mm / g. Hard disk drive according to one of the Claims 1 until 3 , characterized in that one or more bores (46) and / or one or more recesses (48) are provided in the hub (16) for mass reduction. Hard disk drive according to one of the Claims 1 until 4th , characterized in that the height h of the hub (16) is between 18 and 20 mm. Hard disk drive according to one of the Claims 1 until 5 , characterized in that the hub (16) consists of steel and its mass m is between 34 and 37 g.

Images