Spindle motor and disk drive device equipped with the same

Abstract

To provide a spindle motor capable of preventing deterioration of sealing performance in a sealed through-hole.SOLUTION: A spindle motor includes a base portion 71, a shaft, a stator and a rotor. The shaft is arranged on the base portion 71 and extends vertically. The stator has a coil formed by winding a conductor wire, and is arranged on the upper surface of the base portion 71. The rotor is supported to be rotatable with the shaft as a center axis. The base portion 71 has a through-hole 710 that penetrates from the upper surface to the lower surface, through which the conductor 22a is passed and drawn out to the lower surface side, and that is sealed with a sealing material 100. The through-hole 710 has a column-shaped lower column portion 711 and a column-shaped upper column portion 712. The lower column portion 711 is arranged on the lower surface side of the base portion 71. The cross-sectional area perpendicular to the axial direction of the upper column portion 712 is smaller than the cross-sectional area perpendicular to the axial direction of the lower column portion 711.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a spindle motor and a disk drive device including the same. [Background technology]

[0002] A conventional spindle motor includes a base plate, a shaft, a stator, and a rotor. The stator is disposed on the upper surface of a base portion, and has a coil formed by winding a conductive wire. The base portion has a through hole that penetrates from the upper surface to the lower surface. The conductive wire passes through the inside of the through hole and is drawn out to the lower surface side, and the through hole is sealed with a sealant (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-058217 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the spindle motor disclosed in the above-mentioned patent document, when the sealant is filled into the through hole, air bubbles may be generated in the sealant, which may reduce the sealing performance of the through hole.In addition, the sealant may not be filled up to the end of the through hole, which may reduce the sealing performance of the through hole.

[0005] An object of the present invention is to provide a spindle motor capable of preventing a decrease in the sealing performance of a sealed through hole. [Means for solving the problem]

[0006] An exemplary spindle motor of the present invention includes a base portion, a shaft, a stator, and a rotor. The shaft is disposed on the base portion and extends in the vertical direction. The stator has a coil formed by winding a conductor wire, and is disposed on the upper surface of the base portion. The rotor is supported rotatably around the shaft as a central axis. The base portion has a through hole that penetrates from the upper surface to the lower surface, through which the conductor wire passes through the inside and is drawn to the lower surface side, and is sealed with a sealing material. The through hole has a lower columnar body portion having a columnar shape and an upper columnar body portion having a columnar shape. The lower columnar body portion is disposed on the lower surface side of the base portion. The upper columnar body portion is disposed on the upper surface side of the base portion with respect to the lower columnar body portion. A cross-sectional area perpendicular to the axial direction of the upper columnar body portion is smaller than a cross-sectional area perpendicular to the axial direction of the lower columnar body portion. Effect of the Invention

[0007] According to an exemplary embodiment of the present invention, a spindle motor capable of preventing deterioration of the sealing performance in a sealed through hole can be provided. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a vertical cross-sectional view of a disk drive device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a vertical sectional view of the spindle motor according to the embodiment of the present invention. [Diagram 3] FIG. 3 is an enlarged longitudinal sectional view showing a part of the base portion of the spindle motor according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. In this application, the direction parallel to the central axis C is referred to as the "axial direction", the direction perpendicular to the central axis C is referred to as the "radial direction", and the direction along the arc centered on the central axis C is referred to as the "circumferential direction". In this application, the shape and positional relationship of each part will be described with the axial direction being the up-down direction and the cover side being the top with respect to the base part. However, this definition of the up-down direction is not intended to limit the orientation of the spindle motor and disk drive device according to the present invention when in use.

[0010] (1. Disk Drive Configuration) A disk drive device 1 according to an exemplary embodiment of the present invention will be described below. Fig. 1 is a vertical cross-sectional view of a disk drive device 1 according to an embodiment of the present invention.

[0011] The disk drive device 1 is a hard disk drive and includes a spindle motor 10, a disk 50, an access unit 60, and a housing 70.

[0012] The housing 70 accommodates therein the spindle motor 10, the disk 50, and the access unit 60. The inside of the housing 70 is filled with a gas having a lower density than air. Specifically, the housing 70 is filled with helium gas. Note that hydrogen gas or the like may be filled instead of helium gas.

[0013] The housing 70 is formed by casting a metal die-cast member made of an aluminum alloy, although a metal other than an aluminum alloy may be used for the die-cast member.

[0014] The housing 70 has a base portion 71 and a cover portion 72. Inside the housing 70, the disk 50, the spindle motor 10, and the access portion 60 are arranged on the base portion 71. The base portion 71 has side walls surrounding the sides and is open at the top. The opening at the top of the base portion 71 is closed by the cover portion 72.

[0015] The disks 50 are circular information recording media having a hole in the center. The disks 50 are mounted on the spindle motor 10 and are arranged in parallel to each other in the axial direction with equal intervals between them via spacers 80.

[0016] The access unit 60 has a head 61, an arm 62, and a head moving mechanism 63. The head 61 magnetically reads or writes information from or to the disk 50. The arm 62 supports the head 61. The head moving mechanism 63 moves the arm 62 to move the head 61 relative to the disk 50.

[0017] (2. Spindle motor configuration) 2 is a vertical cross-sectional view of the spindle motor 10. The spindle motor 10 supports a disk 50 and rotates the disk 50 about a central axis C. The spindle motor 10 has a shaft 11, a stator 20, a rotor 30, a bearing portion 40, and a base portion 71.

[0018] The base portion 71 is a part of the housing 70, and is also a part of the spindle motor 10. The base portion 71 has an insertion hole 720 that penetrates in the axial direction, and a through hole 710. The insertion hole 720 is disposed on the central axis C. The through hole 710 will be described in detail later.

[0019] The shaft 11 is a columnar member extending along a central axis C extending in the vertical direction. The lower end of the shaft 11 is press-fitted into the insertion hole 720. This fixes the shaft 11 and the base portion 71 together. That is, the shaft 11 is disposed in the base portion 71 and extends in the vertical direction. The shaft 11 has a screw hole 11a extending axially downward from the upper end. The screw hole 11a and a cover screw hole 72a provided in the cover portion 72 overlap in the axial direction and are screwed in place via a screw 90 (see FIG. 1). This fixes the shaft 11 and the cover portion 72 together. The cover screw hole 72a may be a through hole that is not threaded.

[0020] The stator 20 surrounds the lower part of the shaft 11 and is fixed to the base part 71. The stator 20 has a stator core 21 and a plurality of coils 22. The stator core 21 is an annular laminated structure in which a plurality of magnetic bodies are laminated. The stator core 21 has a plurality of teeth 21a protruding radially outward. The plurality of coils 22 are constituted by conductive wires 22a wound around the teeth 21a. That is, the stator 20 has the coils 22 formed by winding the conductive wires 22a, and is disposed on the upper surface of the base part 71.

[0021] The bearing unit 40 is a conical type fluid dynamic bearing that rotatably supports the rotor 30 about a central axis C. That is, the rotor 30 is supported rotatably with the shaft 11 as the central axis. The bearing unit 40 includes annular members 41a, 41b and a sleeve .

[0022] The annular members 41a, 41b protrude radially outward from the outer circumferential surface of the shaft 11. The annular members 41a, 41b are fixed above and below at a distance from each other in the axial direction to the outer circumferential surface of the shaft 11. The annular members 41a, 41b may be integrally formed with the shaft 11.

[0023] The outer circumferential surfaces of the annular members 41a and 41b facing the sleeve 42 are substantially conical. The lower portion of the annular member 41a has a gradually smaller diameter toward the bottom, and the upper portion of the annular member 41b has a gradually smaller diameter toward the top.

[0024] The sleeve 42 is formed in a substantially cylindrical shape and has first, second, and third inner circumferential surfaces 42a, 42b, and 42c in that order from above. The first inner circumferential surface 42a is inclined upwardly in a direction away from the shaft 11 and faces the annular member 41a. The second inner circumferential surface 42b is formed along the central axis C and faces the outer circumferential surface of the shaft 11. The third inner circumferential surface 42c is inclined downwardly in a direction away from the shaft 11 and faces the annular member 41b.

[0025] Further, the sleeve 42 has a minute gap S between the annular members 41 a and 41 b and the shaft 11 .

[0026] The seal portion 44a is attached to the upper surface of the sleeve 42, and the seal portion 44b is attached to the lower surface of the sleeve 42. The seal portions 44a and 44b seal the lubricating oil 43 in the minute gap S. Note that the minute gap S may be filled with a fluid such as gas instead of the lubricating oil.

[0027] Dynamic pressure grooves (not shown) are formed in the opposing first inner circumferential surface 42a and the annular member 41a. Dynamic pressure grooves (not shown) are also formed in the opposing third inner circumferential surface 42c and the annular member 41b. The dynamic pressure grooves induce fluid dynamic pressure in the lubricating oil 43 when the rotor 30 rotates. Note that the dynamic pressure grooves may be formed in either the first inner circumferential surface 42a or the annular member 41b, or the dynamic pressure grooves may be formed in either the third inner circumferential surface 42c or the annular member 41b.

[0028] The rotor 30 has a hub member 31, a magnet 32, and a yoke 33. The hub member 31 is formed in a cylindrical shape, and a sleeve 42 is fixed inside.

[0029] The yoke 33 is formed in an annular shape and is fixed to the lower inner circumferential surface of the hub member 31. The magnet 32 ​​is attached to the inner circumferential surface of the yoke 33. As a result, the magnet 32 ​​is held in the hub member 31 via the yoke 33. The inner circumferential surface of the magnet 32 ​​forms a magnetic pole surface and faces radially the outer circumferential surfaces of the multiple teeth 21a.

[0030] When a driving current is supplied to the coil 22, magnetic flux is generated in the multiple teeth 21a. Then, the magnetic flux interacts with the teeth 21a and the magnets 32, generating a circumferential torque. As a result, the rotor 30 rotates about the central axis C relative to the stator 20. The disk 50 supported by the hub member 31 rotates together with the rotor 30 about the central axis C.

[0031] At this time, when the sleeve 42 is rotationally driven relative to the annular members 41a, 41b, the dynamic pressure grooves induce fluid dynamic pressure in the lubricating oil 43 filled in the minute gap S by a pumping action. As a result, the sleeve 42 is supported in the radial and axial directions without contacting the annular members 41a, 41b, and can rotate smoothly at high speed relative to the annular members 41a, 41b and the shaft 11.

[0032] (3. Detailed structure of the base part) FIG. 3 is a vertical cross-sectional view showing an enlarged portion of the base portion 71. The base portion 71 has a through hole 710 penetrating from the upper surface to the lower surface. The through hole 710 extends parallel to the central axis C. The conductive wire 22a passes through the inside of the through hole 710 and is drawn out to the lower surface side, and is sealed with the sealing material 100. The conductive wire 22a passes through the inside of the through hole 710 and is drawn out to the lower surface side, and is sealed with the sealing material 100. The sealing material 100 is filled into the through hole 710 from the lower surface side of the base portion 71. The sealing material 100 is, for example, an adhesive. The conductive wire 22a drawn out to the lower surface side of the base portion 71 is connected to a wiring board (not shown) arranged on the lower surface side of the base portion 71.

[0033] Through hole 710 has a lower column body portion 711, an upper column body portion 712, a connecting portion 713, a lower opening 714, and an upper opening 715. Lower column body portion 711 is disposed on the lower surface side of base portion 71. Upper column body portion 712 is disposed on the upper surface side of base portion 71 relative to lower column body portion 711.

[0034] The inner diameter of the upper columnar body 712 is smaller than the inner diameter of the lower columnar body 711. That is, the cross-sectional area of ​​the upper columnar body 712 perpendicular to the axial direction is smaller than the cross-sectional area of ​​the lower columnar body 711 perpendicular to the axial direction. As a result, when the sealing material 100 is filled into the through hole 710, the sealing material 100 smoothly flows from the lower columnar body 711 toward the upper columnar body 712 due to the capillary phenomenon. Therefore, the sealing material 100 can be reliably flowed up to the upper end of the upper columnar body 712. As a result, the sealing material 100 can be filled into the entire through hole 710, and the sealing material 100 can be prevented from being not filled. Therefore, the deterioration of the sealing property in the sealed through hole 710 can be prevented. As a result, the helium gas filled in the housing 70 can be prevented from leaking through the through hole 710.

[0035] Furthermore, since the sealant 100 can be filled up to the upper end of the upper columnar body portion 712 by utilizing the capillary phenomenon, the inner diameter of the upper columnar body portion 712 can be made smaller. This makes it possible to prevent the sealant 100 from being left unfilled, while further preventing the deterioration of the sealing performance in the sealed through-hole 710.

[0036] The lower columnar portion 711 and the upper columnar portion 712 are formed in a cylindrical shape, which allows the sealing material 100 to flow into the entire through-hole 710 more smoothly.

[0037] Moreover, by forming the inner diameter of the lower columnar portion 711 to be large, the filling speed of the sealing material 100 can be increased. This makes it possible to prevent air bubbles from being generated in the sealing material 100. Therefore, it is possible to more effectively prevent a decrease in the sealing performance of the sealed through-hole 710. Furthermore, the manufacturing efficiency of the spindle motor 10 can be improved.

[0038] The filling of the sealing material 100 includes a first filling step and a second filling step. After the first filling step is completed, the second filling step is performed. In the first filling step, the sealing material 100 filled in the upper columnar body portion 712 is filled into the through hole 710. In the second filling step, the sealing material 100 filled in the lower columnar body portion 711 is filled into the through hole 710. The filling speed in the first filling step is slower than the filling speed in the second filling step.

[0039] The connecting portion 713 connects the upper column body portion 712 and the lower column body portion 711. The inner diameter of the connecting portion 713 is formed to become smaller toward the upper surface of the base portion 71. This allows the sealing material 100 to flow more smoothly from the lower column body portion 711 to the upper column body portion 712 via the connecting portion 713.

[0040] The axial length of the lower columnar body portion 711 is longer than the axial length of the upper columnar body portion 712. This allows the filling speed of the sealing material 100 to be increased.

[0041] Specifically, the axial length of the upper columnar body 712 is preferably 2.0 mm or more and 3.0 mm or less. Within this range, a distance is ensured that can adequately prevent leakage of the sealed gas inside the housing 70 due to permeation, and the time required for filling the tip of the upper columnar body 712 can be shortened.

[0042] The cross-sectional area of ​​the upper column perpendicular to the axial direction is 0.28 mm 2 More than 0.80mm 2 Within this range, an area sufficient to prevent leakage of the sealed gas inside the housing 70 due to permeation is ensured, and the time required for filling the tip of the upper columnar portion 712 can be shortened.

[0043] In addition, the axial length of the lower columnar body 711 is preferably 3.0 mm or more. This ensures that the axial length of the lower columnar body 711 is sufficient to smoothly switch the filling speed from low to high when transitioning from the first filling step to the second filling step. This makes it possible to prevent the generation of air bubbles or non-filling caused by a sudden change in filling speed.

[0044] The cross-sectional area of ​​the lower column body 712 perpendicular to the axial direction is 0.78 mm 2 More than 20.00mm 2 Within this range, the filling speed of the sealant 100 can be increased, and the amount of sealant 100 required to fill the lower column body portion 711 can be reduced.

[0045] The lower opening 714 is disposed at the lower end of the base portion 71, and is formed such that its inner diameter becomes smaller toward the upper surface of the base portion 71. By providing the lower opening 714, the sealing material 100 smoothly flows into the lower column portion 711 through the lower opening 714. In addition, the sealing material 100 can be prevented from protruding downward from the lower surface of the base portion 71 and solidifying.

[0046] The upper opening 715 is disposed at the upper end of the base portion 71, and is formed so that its inner diameter becomes larger toward the upper surface of the base portion 71. By providing the lower opening 714, the sealant 100 is more likely to accumulate on the upper opening 715 due to surface tension. This makes it possible to prevent the sealant 100 from overflowing around the through-hole 710 on the upper surface of the base portion 71. It is possible to prevent the sealant 100 from protruding upward from the upper surface of the base portion 71 and solidifying.

[0047] (4. Other) The above-mentioned embodiment is merely an example of the present invention. The configuration of the embodiment may be appropriately changed without departing from the technical spirit of the present invention. Moreover, the embodiments may be combined as far as possible. In this embodiment, the lower columnar body portion 711 and the upper columnar body portion 712 are formed in a cylindrical shape, but one of the lower columnar body portion 711 and the upper columnar body portion 712 may be formed in a cylindrical shape, and the other may be formed in an elliptical columnar shape or a polygonal columnar shape. Moreover, one of the lower columnar body portion 711 or the upper columnar body portion 712 may be formed in a truncated cone shape. In this case, the inner diameter of the lower columnar body portion 711 or the upper columnar body portion 712 is formed to be smaller toward the upper surface of the base portion 71. This allows the sealing material 100 to flow more smoothly from the lower columnar body portion 711 to the upper columnar body portion 712.

[0048] Furthermore, in this embodiment, the spindle motor 10 having a fluid dynamic bearing has been described, but the bearing portion 40 may be, for example, a spindle motor having a bearing such as a ball bearing. [Industrial Applicability]

[0049] The present invention can be used in a housing for a disk drive device such as a hard disk drive. [Explanation of symbols]

[0050] 1 Disk Drive Unit 10 Spindle motor 11 Shaft 11a Screw hole 20 Stator 21 Stator core 21a Teeth 22 Coil 22a conductor 30 rotors 31 Hub parts 32 Magnet 33 York 40 Bearing section 41a, 41b Annular member 42 Sleeve 42a, 42b, 42c 1st, 2nd, 3rd inner peripheral surface 43 Lubricating oil 44a, 44b Seal part 50 discs 60 Access Section 61 Head 62 Arm 63 Head movement mechanism 70 Case 71 Base 72 Cover part 72a Cover screw hole 80 Spacer 90 Screw 100 Encapsulating material 710 Through hole 711 Lower column body part 712 Upper column body part 713 Connection section 714 Lower opening 715 Upper opening 720 Insertion hole C center axis S micro gap

Claims

1. A base portion; A shaft disposed on the base portion and extending in a vertical direction; a stator having a coil formed by winding a conductive wire and disposed on an upper surface of the base; a rotor supported rotatably about the shaft as a central axis, the base portion has a through hole that penetrates from an upper surface to a lower surface, the conductive wire passes through an inside thereof and is drawn out to the lower surface side, and the through hole is sealed with a sealing material; the through hole has a lower columnar portion disposed on a lower surface side of the base portion, and an upper columnar portion disposed on an upper surface side of the base portion relative to the lower columnar portion, A cross-sectional area of ​​the upper columnar body perpendicular to the axial direction is smaller than a cross-sectional area of ​​the lower columnar body perpendicular to the axial direction, The axial length of the lower columnar body portion is equal to or longer than the axial length of the upper columnar body portion, The through hole has a connecting portion that connects the upper columnar body portion and the lower columnar body portion, The inner diameter of the connecting portion is formed so as to become smaller toward the upper surface of the base portion.

2. The spindle motor according to claim 1 , wherein at least one of the upper columnar portion and the lower columnar portion is formed in a cylindrical shape.

3. 3. The spindle motor according to claim 1, wherein the axial length of the upper columnar portion is not less than 2.0 mm and not more than 3.0 mm.

4. The cross-sectional area of ​​the upper columnar body perpendicular to the axial direction is 0.28 mm 2 More than 0.80 mm 2 The spindle motor according to any one of claims 1 to 3, wherein:

5. 5. The spindle motor according to claim 1, wherein the lower column portion has an axial length of 3.0 mm or more.

6. The cross-sectional area of ​​the lower column part perpendicular to the axial direction is 0.78 mm 2 More than 20.00 mm 2 The spindle motor according to any one of claims 1 to 5, wherein:

7. 7. The spindle motor according to claim 1, wherein the through hole has an upper opening disposed at an upper end of the base portion and an inner diameter of the through hole increases toward the upper surface of the base portion.

8. 8. The spindle motor according to claim 1, wherein the through hole has a lower opening disposed at a lower end of the base portion and an inner diameter of the through hole gradually decreases toward an upper surface of the base portion.

9. A spindle motor according to any one of claims 1 to 8, a disk rotated by the spindle motor; an access unit that performs at least one of reading and writing of information from and to the disk; A disk drive device comprising: a housing that houses the spindle motor, the disk, and the access portion, and includes the base portion.

10. 10. The disk drive device according to claim 9, wherein the inside of the housing is filled with a gas having a density lower than that of air.

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