JP2023115717A - Spindle motor and hard disk driving device - Google Patents

Abstract

To provide a technique of preventing the shaft rigidity of a spindle motor from lowering.SOLUTION: A spindle motor 3 includes: a shaft 21 fixed to a base plate 10; a fixation unit 20 having a lower circular cone bearing member 22 and an upper circular cone bearing member 23 fixed to the outer periphery surface of the shaft 21; a cylindrical rotor 30 having a shaft insertion hole 310 in which the fixation unit 20 is inserted and rotatably supported with respect to the fixation unit 20; and a separator unit 60 located between the lower circular cone bearing member 22 and the upper circular cone bearing 23 between the outer periphery surface of the shaft 21 and the inner periphery surface of the bearing insertion hole 310 facing the outer periphery surface, the separator unit 60 holding a gas layer of a helium gas. The rotor 30 forms a space S2 between the rotor and the base plate 10 and has a ventilatory hole 61 for making the space S2 and the separator unit 60 communicated with each other.SELECTED DRAWING: Figure 2

Description

The present invention relates to spindle motors and hard disk drives.

Some hard disk drives are equipped with a spindle motor of a type in which the shaft is fixed to a base plate and the rotating portion is supported by fluid dynamic bearings. This type of spindle motor requires a structure for equalizing air pressure between the bearing portion and the outside of the bearing in order to retain the lubricating oil inside the fluid dynamic pressure bearing in the bearing portion.

For example, Patent Literature 1 discloses a technique of providing a communicating portion on a shaft.

JP 2012-152098 A

However, in the technique disclosed in Patent Document 1, since a hole is provided in the shaft as a communicating portion, the rigidity of the shaft is lowered.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a technique that does not reduce the shaft rigidity of a spindle motor.

In order to solve the above problems, a spindle motor has a fixed portion having a shaft fixed to a base plate and two bearing members fixed to the outer peripheral surface of the shaft; A cylindrical rotating portion having a hole and rotatably supported with respect to the fixed portion, and the two bearings between the outer peripheral surface of the shaft and the inner peripheral surface of the through hole facing the outer peripheral surface. a separator section provided between members and holding a gas layer of a gas having a density lower than that of air, wherein the rotating section forms a space between the base plate and the space and the separator section. It has a ventilation hole that communicates with

According to the spindle motor of the present invention, shaft rigidity does not decrease.

1 is a perspective view of a hard disk drive 1; FIG. 3 is a cross-sectional view of the spindle motor 3; FIG. 3 is a cross-sectional view of the base plate 10; FIG. 4 is a front view of the shaft 21; FIG. 4 is a cross-sectional view of the spindle motor 3 in which the ventilation holes 61 are slanted with respect to the radial direction; FIG. 3 is a cross-sectional view of a spindle motor 3 in which a rotor 30 is one component; FIG. 4 is a cross-sectional view of the spindle motor 3 in which the sleeve 31 is divided into upper and lower parts; FIG. It is a top view of sleeve 31L.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, although various technically preferable limitations are attached to the embodiments described below in order to carry out the present invention, the scope of the present invention is not limited to the following embodiments and illustrated examples.

<Hard disk drive>
FIG. 1 is a perspective view showing the configuration of the hard disk drive 1. As shown in FIG. A hard disk drive device 1 includes a case 2 , a spindle motor 3 , a recording disk 4 , a bearing device 5 and a cover 6 .

The case 2 has a substantially rectangular parallelepiped box-like shape with one side open. A spindle motor 3 , a recording disk 4 , and a bearing device 5 are arranged inside the case 2 . A spindle motor 3 rotatably supports a plurality of recording disks 4 . A plurality of recording disks 4 are supported by the spindle motor 3 so that their disk surfaces face each other. A gap is formed between each recording disk 4 . The bearing device 5 swingably supports a plurality of swing arms 7 arranged in gaps between the respective recording disks 4 . A magnetic head 8 is provided at the tip of the swing arm 7 . The magnetic head 8 is a member that applies magnetism to the recording disk 4 or reads magnetism from the recording disk 4 . The cover 6 is a plate-like member that closes the open surface of the case 2 . The cover 6 is sealed together with the case 2 by sealing means to form a housing 9 . An internal space S1 is formed inside the housing 9 . The internal space S1 is filled with helium gas having a density lower than that of air. In addition to the helium gas, the internal space S1 may be filled with, for example, nitrogen gas or a mixed gas of helium and nitrogen.

When the spindle motor 3 rotates, the recording disk 4 also rotates. When the swing arm 7 swings in this state, the magnetic head 8 moves above the rotating recording disk 4 . The magnetic head 8 applies magnetism to the recording disk 4 or reads magnetism from the recording disk 4 . In this manner, the hard disk drive 1 can record information on the recording disk 4 and read information recorded on the recording disk 4 .

<Spindle motor>
Next, the detailed structure of the spindle motor 3 will be described. FIG. 2 is a sectional view showing the configuration of the spindle motor 3. As shown in FIG. The spindle motor 3 has a base plate 10 , a fixed portion 20 , a rotor 30 and a stator core 40 .

Here, as shown in FIG. 2 and the like, the direction parallel to the central axis of the shaft 21 described later is defined as the axial direction, the direction around the central axis of the shaft 21 is defined as the circumferential direction, and the direction perpendicular to the axial direction is defined as the radial direction. For the sake of explanation, the axial direction is defined as the vertical direction, the rotor 30 side with respect to the shaft 21 is defined as the upper side, and the base plate 10 side is defined as the lower side.

A base plate 10 (an example of a base portion) is a metal member and a bottom portion of the case 2 . As shown in FIG. 3, the base plate 10 is formed with a through hole 11 and a circumferential wall portion 12 . The through hole 11 is a hole for inserting and fixing the end of the shaft 21 , and is provided so as to axially penetrate the base plate 10 . The circumferential wall portion 12 is formed in an annular shape when viewed in the axial direction so as to be concentric with the through hole 11 . The diameter of the circumferential wall portion 12 is larger than the diameter of the through hole 11 .

The fixed part 20 has a shaft 21 , a lower conical bearing member 22 and an upper conical bearing member 23 .

The shaft 21 is a cylindrical rod-shaped metal member. 4 is a side view of the shaft 21. FIG. A through-hole insertion portion 201, a first mounting portion 202, a concave portion 204, and a second mounting portion 203 are formed in the shaft 21 in order from the end portion (lower side in FIG. 4). Each portion is axially spaced apart.

The through-hole inserting portion 201 is inserted and fitted so that the outer peripheral surface of the through-hole inserting portion 201 and the inner peripheral surface 11A (see FIG. 3) of the through-hole 11 face each other (see FIG. 2). Since the outer diameter of the through-hole inserting portion 201 is larger than the inner diameter of the through-hole 11, the through-hole inserting portion 201 is fitted into the through-hole 11 by press fitting.

A lower conical bearing member 22 is fixed to the first mounting portion 202, and an upper conical bearing member 23 is fixed to the second mounting portion 203 (see FIG. 2). The lower conical bearing member 22 and the upper conical bearing member 23 have conical outer surfaces that face radially outward.

Fitting is a form of joining, and when the outer diameter of the through-hole inserting portion 201 is smaller than the inner diameter of the through-hole 11, the through-hole inserting portion 201 is attached to the through-hole 11 by using a method such as adhesion. may be joined to.

The concave portion 204 is provided between the first mounting portion 202 and the second mounting portion 203 and is a portion of the shaft 21 having a smaller outer diameter than the first mounting portion 202 and the second mounting portion 203 . The recess 204 is provided at a position facing a recess 314 of the sleeve 31, which will be described later.

A rotor 30 (an example of a rotating portion) is a member attached to the shaft 21 . Rotor 30 has sleeve 31 and hub 32 .

The sleeve 31 has a shaft insertion hole 310 through which the shaft 21 is inserted. The shaft insertion hole 310 (an example of a through hole) has a lower conical inner surface 312 at its lower end and an upper conical inner surface 313 at its upper end. A recess 314 is also provided between the lower conical inner surface 312 and the upper conical inner surface 313 . The inner diameter of the shaft insertion hole 310 faces the shaft 21 with a minute gap therebetween. The lower conical inner surface 312 faces the lower conical bearing member 22 with a minute gap therebetween. The upper conical inner surface 313 faces the upper conical bearing member 23 with a minute gap therebetween. The lower side of the minute gap between the shaft insertion hole 310 and the shaft 21 communicates with the minute gap between the lower conical bearing member 22 and the lower conical inner surface 312, and the gap between the shaft insertion hole 310 and the shaft 21 The upper side of the microgap communicates with the microgap between the upper conical bearing member 23 and the upper conical inner surface 313 . A hub 32 is fixed to the radially outer side of the sleeve 31 . In addition, communicating refers to connecting two spaces.

A minute gap between the lower conical bearing member 22 and the lower conical inner surface 312 and a minute gap between the upper conical bearing member 23 and the upper conical inner surface 313 are filled with lubricating oil. Further, at least one of the lower conical inner surface 312 and the lower conical outer surface of the lower conical bearing member 22 and at least one of the upper conical inner surface 313 and the upper conical outer surface of the upper conical bearing member 23 have dynamic pressure generating grooves. (not shown) are formed. Thereby, the fluid dynamic pressure bearing 50 is formed.

The recessed portion 314 is a groove that is annularly provided in the shaft insertion hole 310 when viewed in the axial direction. The concave portion 314 has a hole inner diameter larger than that of other portions in the shaft insertion hole 310 . The position of the recess 314 is a position facing the recess 204 in the axial direction. The axial length of the recess 314 is substantially equal to the axial length of the recess 204 of the shaft 21 . A space formed by the recess 314 and the recess 204 is the separator portion 60 . The separator portion 60 is formed in an annular shape when viewed in the axial direction between the shaft insertion hole 310 and the shaft 21 . The separator part 60 forms a gas layer of helium gas to prevent the lubricating oil from leaking out from the fluid dynamic pressure bearing 50 . The separator portion 60 communicates with the external space of the sleeve 31 via a ventilation hole 61 which will be described later.

The ventilation hole 61 is provided from the recess 314 to the outer peripheral surface of the sleeve 31 . The ventilation hole 61 extends parallel to the radial direction and penetrates the sleeve 31 . The ventilation hole 61 is connected to the notch 39 of the hub 32 on the outer peripheral surface side of the sleeve 31 . In this embodiment, the sleeve 31 is provided with one ventilation hole 61 , but two or more ventilation holes 61 may be provided in the sleeve 31 .

The hub 32 has a disk portion 33 , a cylindrical portion 34 and an outer edge portion 35 . The disk portion 33 is a disk-shaped member, and has a through hole 36 at the center in the radial direction. The inner diameter of the through hole 36 is approximately equal to the outer diameter of the sleeve 31 . The sleeve 31 is inserted into the through hole 36 so that the inner peripheral surface of the through hole 36 and the outer peripheral surface of the sleeve 31 face each other, and the hub 32 is fixed to the sleeve 31 . A notch portion 39 is provided in the disc portion 33 so as to be continuous with the lower end of the through hole 36 . The cutout portion 39 is provided in an annular shape when viewed in the axial direction, and is connected to the ventilation hole 61 . The cylindrical portion 34 is a cylindrical member having a constant thickness in the radial direction, and extends vertically from the outer edge of the disk portion 33 . An outer edge portion 35 is provided at the lower end portion of the lower cylindrical portion 34 . The outer edge portion 35 is a member that protrudes radially outward from the lower end portion of the cylindrical portion 34 and extends in a flange shape over the entire circumference in the circumferential direction. A plurality of recording disks 4 are installed above the outer edge portion 35 and along the outer peripheral surface of the cylindrical portion 34 (see FIG. 1).

A space S2 is formed between the sleeve 31 and the hub 32 and the base plate 10 . The space S2 communicates with the internal space S1 and is separated from the internal space S1 by the cylindrical portion 34 .

A yoke 37 and a ring magnet 38 are attached to the inner peripheral surface of the lower cylindrical portion 34 . The yoke 37 is a cylindrical member and suppresses magnetic flux leakage from the ring magnet 38 . The yoke 37 is attached to the inner circumferential surface of the cylindrical portion 34 over the entire circumference in the circumferential direction. The ring magnet 38 is a cylindrical member, and is a permanent magnet magnetized in a state in which the polarities are reversed to N, S, N, S . . . in the circumferential direction. The ring magnet 38 is attached to the inner circumferential surface of the yoke 37 over the entire circumference in the circumferential direction. The ring magnet 38 faces a stator core 40 around which a coil 41 (to be described later) is wound with a gap in the radial direction.

The stator core 40 is a member in which a plurality of annular electromagnetic steel plates are laminated in the axial direction. The stator core 40 extends along the outer peripheral surface of the circumferential wall portion 12 and is fixed to the outer peripheral surface of the circumferential wall portion 12 by a method such as adhesion. In addition, the stator core 40 has pole teeth (salient poles) extending radially outward and arranged in a plurality along the circumferential direction. A coil 41 is wound around the pole teeth. The stator core 40 generates magnetic flux by the current flowing through the coil 41 .

<Operation of the spindle motor>
By applying a current to the coil 41 and switching its polarity, the magnetic attractive force and the magnetic repulsive force generated between the ring magnet 38 and the pole teeth of the stator core 40 are switched. As a result, rotor 30 rotates around shaft 21 .

As the rotor 30 rotates at high speed, lubrication is filled in the micro gap between the lower conical bearing member 22 and the lower conical inner surface 312 and the micro gap between the upper conical bearing member 23 and the upper conical inner surface 313. The oil is pressurized by the hydrodynamic grooves. As a result, dynamic pressure is generated in the fluid dynamic pressure bearing 50 . The generated dynamic pressure rotates the sleeve 31 while being supported by the shaft 21 , the lower conical bearing member 22 and the upper conical bearing member 23 in a non-contact state. That is, the rotor 30 rotates while being supported by the shaft 21 in a non-contact state.

<effect>
In the above-described embodiment, the spindle motor 3 includes a fixed portion 20 having a shaft 21 fixed to the base plate 10, a lower conical bearing member 22 and an upper conical bearing member 23 fixed to the outer peripheral surface of the shaft 21; A cylindrical rotor 30 that has a shaft insertion hole 310 into which the portion 20 is inserted and is rotatably supported with respect to the fixed portion 20; a separator portion 60 that is provided between the lower conical bearing member 22 and the upper conical bearing member 23 between the inner peripheral surfaces and holds a gas layer of helium gas, and the rotor 30 is provided between the base plate 10 and the separator portion 60. A space S2 is formed, and a ventilation hole 61 is provided for communicating the space S2 and the separator portion 60 .

According to such a configuration, since the ventilation holes 61 are provided in the rotor 30 , there is no need to provide ventilation holes in the shaft 21 . As a result, shaft rigidity does not decrease.

Further, in order to provide the ventilation holes in the shaft 21, the shaft 21 must be cut. In addition, since one axial hole and two radial holes are formed in the shaft 21 by cutting, and the ventilation holes are formed by connecting these holes, the processing cost is high. However, in this embodiment, a vent hole 61 is provided in the rotor 30 . One ventilation hole 61 may be provided in the rotor 30 so as to connect the separator portion 60 and the space S2 with a straight line. As a result, the machining cost of the ventilation hole 61 is low, and the spindle motor 3 can be manufactured at low cost.

Further, when a ventilation hole is provided in the shaft 21, it is necessary to close the end of the hole in the axial direction with a sealing member. However, by providing the ventilation holes in the rotor 30, this sealing member becomes unnecessary. As a result, the spindle motor 3 can be manufactured inexpensively.

The lubricating oil filled in the fluid dynamic pressure bearing 50 may evaporate little by little over time and adhere to members other than the spindle motor 3 . However, in the spindle motor 3 of the present embodiment, since the ventilation hole 61 is connected to the space S2 formed by the rotor 30 and the base plate 10, the lubricating oil flows through the space S2 into another space. Spread. Therefore, the lubricating oil is less likely to diffuse into the space around the spindle motor 3 and is less likely to adhere to other members.

Further, the ventilation hole 61 of the spindle motor 3 according to this embodiment extends parallel to the radial direction of the shaft 21 .

According to such a configuration, the ventilation hole 61 is formed in the sleeve 31 constituting the rotor 30 so as to extend in parallel with the radial direction. . As a result, the machining cost of the ventilation hole 61 is low, and the spindle motor 3 can be manufactured at low cost.

Further, the rotor 30 of the spindle motor 3 according to this embodiment has a sleeve 31 formed with a shaft insertion hole 310 into which the shaft 21 is inserted, and a hub 32 fixed to the outside of the sleeve 31. 32 forms a space S2 with the base plate 10, and a vent hole 61 is provided in the sleeve 31. As shown in FIG.

With such a configuration, the sleeve 31 and the hub 32 can be processed separately. That is, since the ventilation hole 61 can be machined in the state of the sleeve 31 alone, the machining of the ventilation hole 61 is easy.

Further, the hard disk drive device 1 according to this embodiment includes the spindle motor 3 described above.

According to such a configuration, since the hard disk drive device 1 includes the spindle motor 3 having a high shaft rigidity, the vibration of the recording disk 4 supported by the spindle motor 3 is reduced. As a result, the sound generated during operation of the hard disk drive 1 is small.

In addition, the increased rigidity of the shaft increases the weight that the shaft 21 can support. As a result, the number of recording disks 4 supported by the spindle motor 3 can be increased. That is, the storage capacity of the hard disk drive 1 can be increased. Further, since the rigidity of the shaft is high, the height of the housing 9 can be increased to increase the length of the shaft 21 in the axial direction. As a result, a larger number of recording disks 4 can be installed in the hard disk drive 1 with the housing 9 having a height of 3.81 cm (1.5 inches) or more and 5.08 cm (2.0 inches) or less. can do.

Moreover, since the manufacturing cost of the spindle motor 3 is lower than that of the conventional one, the manufacturing cost of the hard disk drive device 1 can be reduced.

Lubricating oil filled in the fluid dynamic pressure bearing 50 causes contamination when it adheres to the recording disk 4 . If the ventilation hole 61 is provided near the recording disk 4 mounted on the outer surface of the rotor 30 , the evaporated lubricating oil tends to adhere to the recording disk 4 . However, in this embodiment, the ventilation hole 61 is connected to the space S2 formed by the rotor 30 and the base plate 10, so the ventilation hole 61 is far from the recording disk 4. FIG. As a result, the evaporated lubricating oil is less likely to adhere to the recording disk 4 .

The hard disk drive 1 according to the present embodiment further includes a housing 9, the spindle motor 3 is arranged in the housing 9, and the housing 9 and the space S2 are filled with helium gas.

According to such a configuration, the air resistance in the internal space S1 formed inside the housing 9 is reduced, so that the rotation unevenness and vibration of the recording disk 4 are reduced. As a result, since the recording disk 4 can be operated with higher accuracy, the number of recording disks 4 mounted on the hard disk drive 1 can be increased. As a result, the storage capacity of the hard disk drive 1 can be increased.

<Modification>
The modifications described below may be applied in combination.

(1) Modification 1
As shown in FIG. 5, the ventilation holes 61 may be slanted with respect to the radial direction.

By slanting the vent hole 61 with respect to the radial direction, the vent hole 61 can be formed so that the length of the vent hole 61 is shortened. As a result, a decrease in rigidity of the rotor 30 caused by forming the ventilation holes 61 can be reduced.

(2) Modification 2
As shown in FIG. 6, the rotor 30 may be configured by a hub 32 with which a sleeve 31 is integrated.

Such a hub 32 is made of a stainless material. A ring magnet 38 is directly attached to the inner peripheral surface of the cylindrical portion 34 . In this case, the yoke 37 is unnecessary because the cylindrical portion 34 suppresses leakage of magnetic flux from the ring magnet 38 .

Since the rotor 30 is composed of one part, the number of parts of the spindle motor 3 is reduced. As a result, the spindle motor 3 can be manufactured inexpensively.

(3) Modification 3
Hub 32 may be a forging.

The hub 32 is made of low-carbon steel with a carbon content of 0.23 mass % or less, for example, 0.07 mass % or more and 0.23 mass % or less, preferably 0.08 mass % or more and 0.23 mass % or less. It is a forged product with Hub 32 is preferably formed from S20C. S20C is mass %, carbon: 0.18% or more and 0.23% or less, silicon: 0.15% or more and 0.35% or less, manganese: 0.3% or more and 0.6% or less, phosphorus: 0.3% or more. 03%, sulfur: less than 0.035%, balance: iron and inevitable impurities.

It should be noted that the hub 32 is more preferably made of S10C. S10C is superior to S20C in cold forgeability. S10C is, in mass %, carbon: 0.08% or more and 0.13% or less, silicon: 0.15% or more and 0.35% or less, manganese: 0.3% or more and 0.6% or less, phosphorus: 0.3% or more; 03%, sulfur: less than 0.035%, balance: iron and inevitable impurities.

Materials other than S20C or S10C forming the hub 32 include S12C (carbon: 0.10% by mass or more and 0.15% by mass or less), S15C (carbon: 0.13% by mass or more and 0.18% by mass or less). ), S17C (carbon: 0.15% by mass or more and 0.20% by mass or less), S09CK (carbon: 0.07% by mass or more and 0.12% by mass or less), S15CK (carbon: 0.13% by mass or more and 0.12% by mass or less) 18% by mass or less), S20CK (carbon: 0.18% by mass or more and 0.23% by mass or less), etc. can also be used.

Since the low carbon steel is excellent in cold forgeability, the hub 32 made of the low carbon steel is cold forged. The hub 32, which is formed as a cold forged product, has increased rigidity due to work hardening and the fact that the metal flow is not cut. As a result, the axial length of the hub 32 can be made longer, so that the spindle motor 3 can mount more recording disks 4 .

A recording disk 4 made of metal such as aluminum or glass is mounted on the hub 32 (see FIG. 1). Here, since the coefficient of thermal expansion of glass is close to that of low-carbon steel, by combining the recording disc 4 made of glass and the hub 32 made of low-carbon steel, the accuracy of mounting the recording disc 4 on the hub 32 is improved. do.

Further, since the hub 32 is a forged product, cutting work can be reduced, so the hub 32 can be manufactured at low cost. As a result, the spindle motor 3 can be manufactured inexpensively.

(4) Modification 4
As shown in FIG. 7, the rotor 30 is composed of a hub 32 in which a sleeve 31 is divided into upper and lower parts, and the upper half of the sleeve 31 is integrated with the lower half of the sleeve 31 (hereinafter referred to as sleeve 31L). good too.

The hub 32 has a shaft insertion hole 310U, an upper conical inner surface 313, and a recess 314U, which are elements that the upper half of the sleeve 31 has. The shaft insertion hole 310U is the upper half of the shaft insertion hole 310, and forms the shaft insertion hole 310 together with the shaft insertion hole 310L, which will be described later. The recessed portion 314U is the upper half of the recessed portion 314, and forms the recessed portion 314 together with the recessed portion 314L, which will be described later. The upper conical inner surface 313 is provided at the upper end of the shaft insertion hole 310U. The upper conical inner surface 313 faces the upper conical bearing member 23 . An annular concave portion 390 is provided on the lower surface side of the disc portion 33 . The annular recess 390 is provided in an annular shape on the lower surface of the disk portion 33 when viewed in the axial direction, and is formed by recessing the lower surface of the disk portion 33 upward. The outer diameter of the annular recess 390 is larger than the outer diameter of the sleeve 31L.

The sleeve 31L has a shaft insertion hole 310L, a lower conical inner surface 312, and a recess 314L, which are elements that the lower half of the sleeve 31 has. The shaft insertion hole 310L is the lower half of the shaft insertion hole 310. As shown in FIG. Recess 314L is the lower half of recess 314 . A lower conical inner surface 312 is provided at the lower end of the shaft insertion hole 310L. Lower conical inner surface 312 faces lower conical bearing member 22 . The sleeve 31L has a flange portion 391 and a notch portion 392 at its upper end, as shown in FIG. The flange portion 391 is annularly provided on the sleeve 31L when viewed in the axial direction. The outer diameter of the flange portion 391 is approximately equal to the outer diameter of the annular recess 390 . The cutout portion 392 is a cutout that extends linearly outward from the center of the sleeve 31L in the radial direction. The notch portion 392 forms a downward recessed groove in the upper end portion of the sleeve 31L and a portion of the flange portion 391 .

The sleeve 31L is joined to the hub 32 by a method such as adhesion so that the upper surface having the flange portion 391 and the upper surface of the annular recess 390 of the hub 32 face each other. At this time, the recess 314L of the sleeve 31L and the recess 314U of the hub 32 are joined to form the recess 314. As shown in FIG. The recess 314 forms the separator portion 60 with the recess 204 of the shaft 21 . In addition, by joining the sleeve 31L to the hub 32, the notch 392 forms the ventilation hole 61 at the joint between the sleeve 31L and the hub 32. As shown in FIG. The ventilation hole 61 has one end connected to the separator portion 60 and the other end connected to the space S2. As a result, the separator portion 60 communicates with the space S2 through the ventilation holes 61 .

By axially dividing the rotor 30 into the sleeve 31L and the hub 32 and providing the vent hole 61 at the junction of the two members, the sleeve 31L and the hub 32 can be manufactured separately. As a result, the manufacture of the sleeve 31L and the hub 32 is facilitated.

Also, by providing the sleeve 31L or the hub 32 with a configuration such as the notch 392, when the sleeve 31L is joined to the hub 32, a vent hole 61 is formed at the joint between the two members. As a result, it becomes unnecessary to process the ventilation hole 61 after joining the two members, and the rotor 30 can be manufactured easily.

DESCRIPTION OF SYMBOLS 1... Hard disk drive, 3... Spindle motor, 9... Case, 10... Base plate (base part), 20... Fixed part, 21... Shaft, 22... Lower conical bearing member (bearing member), 23... Upper conical bearing Member (bearing member) 30 Rotor (rotating portion) 31 Sleeve 32 Hub 60 Separator 61 Ventilation hole 310 Shaft insertion hole (through hole) S2 Space

Claims (9)

a fixed part having a shaft fixed to the base plate and two bearing members fixed to the outer peripheral surface of the shaft;
a cylindrical rotating part having a through hole into which the fixing part is inserted and rotatably supported with respect to the fixing part;
a separator part provided between the two bearing members between the outer peripheral surface of the shaft and the inner peripheral surface of the through hole facing the outer peripheral surface and holding a gas layer of a gas having a density lower than that of air;
with
The spindle motor, wherein the rotating section forms a space with the base plate, and has a ventilation hole that communicates the space with the separator section. 2. The spindle motor according to claim 1, wherein said ventilation hole extends parallel to the radial direction of said shaft. 2. The spindle motor according to claim 1, wherein said ventilation holes intersect with the radial direction of said shaft. The rotating part has a sleeve formed with the through hole into which the shaft is inserted, and a hub fixed to the outside of the sleeve,
4. The spindle motor according to claim 1, wherein said hub forms said space with said base plate, and said vent hole is provided in said sleeve. 5. The spindle motor according to claim 4, wherein said hub is a forging. 4. The spindle motor according to any one of claims 1 to 3, wherein said rotating portion is divided into two members in the axial direction of said shaft, and said ventilation hole is provided at a joint portion of said two members. A hard disk drive comprising the spindle motor according to any one of claims 1 to 6. The hard disk drive further comprises a housing,
8. The hard disk drive according to claim 7, wherein said spindle motor is arranged within said housing, and said gas is filled in said housing and said space. 9. The hard disk drive according to claim 8, wherein the housing has a height of 3.81 centimeters or more and 5.08 centimeters or less.

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