JP2023130094A - Spindle motor and hard disk drive unit - Google Patents

Abstract

To provide a technique for strongly joining a member that closes an opening to a bearing sleeve of a spindle motor.SOLUTION: A spindle motor 3 comprises: a columnar shaft 60 extending in an axial direction; an annular thrust plate 43 attached to one end of the shaft 60; a cylindrical bearing sleeve 40 for rotatably supporting the shaft 60 and having a circumferential direction and a radial direction orthogonal to the circumferential direction, the bearing sleeve 40 having a lower end part 40E in the axial direction, and an external peripheral recess 42 extending in the circumferential direction and having a depth in the axial direction formed on the radially outer side of the lower end part 40E; and a counter plate 44 having a lid part 44S for covering the lower end part 40E, and a protrusion 44P protruding toward the external peripheral recess 42 from the lid part 44S and joined to the lower end part 40E. The bearing sleeve 40 and the counter plate 44 are joined to each other with an adhesive.SELECTED DRAWING: Figure 2

Description

The present invention relates to a spindle motor and a hard disk drive.

In a type of spindle motor in which the shaft is supported by a bearing sleeve, it is necessary to close an opening at one end of the bearing sleeve so that the shaft is held inside the bearing sleeve. Since an axial force is applied to the shaft, the member that closes the opening needs to be firmly joined to the bearing sleeve.

For example, Patent Document 1 discloses a technique for joining a cup-shaped member to a bearing sleeve using an adhesive.

Japanese Patent Application Publication No. 2004-108549

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique for firmly joining a member that closes an opening to a bearing sleeve of a spindle motor.

In order to solve the above problems, a spindle motor includes a columnar shaft extending in the axial direction, an annular thrust plate attached to one end of the shaft, rotatably supporting the shaft, A cylindrical bearing sleeve having a radial direction orthogonal to the circumferential direction, the sleeve having an end in the axial direction, and a recess extending along the circumferential direction and having a depth in the axial direction. a counter plate having a bearing sleeve formed on the radially outward side of the bearing sleeve, a lid portion that covers the end portion, and a protrusion that protrudes from the lid portion into the recess and joins the end portion. , the bearing sleeve and the counter plate are joined by adhesive.

According to the present invention, the member that closes the opening can be firmly joined to the bearing sleeve.

1 is a perspective view of a hard disk drive device 1. FIG. 3 is a sectional view of a spindle motor 3. FIG. 3 is an enlarged view of section III in FIG. 2. FIG. FIG. 3 is an enlarged cross-sectional view of the spindle motor 3 in which a gap 145 is formed. FIG. 3 is an enlarged cross-sectional view of the spindle motor 3 in which a gap 147 is formed. FIG. 3 is an enlarged cross-sectional view of the spindle motor 3 in which a gap 247 is formed.

Embodiments of the present invention will be described below with reference to the drawings. However, although various limitations that are technically preferable for carrying out the present invention are attached to the embodiments described below, 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 a hard disk drive device 1. As shown in FIG. The 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 the shape of a substantially rectangular parallelepiped box with an open bottom on one side. Inside the case 2, a spindle motor 3, a recording disk 4, and a bearing device 5 are arranged. The spindle motor 3 rotatably supports a plurality of recording disks 4. The plurality of recording disks 4 are supported by the spindle motor 3 so that their respective 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 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-shaped member that closes the open surface of the case 2. The cover 6 is sealed together with the case 2 by a sealing means to form a housing 9. An internal space S is formed inside the housing 9 . The internal space S is filled with air or helium gas, which has a lower density than air. Note that, in addition to air and helium gas, the internal space S 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 way, the hard disk drive device 1 can record information on the recording disk 4 and read information recorded on the recording disk 4.

<Spindle motor>
Next, the detailed configuration of the spindle motor 3 will be explained. FIG. 2 is a sectional view showing the configuration of the spindle motor 3. As shown in FIG. The spindle motor 3 includes a stationary part 10 and a rotating part 20 that rotates with respect to the stationary part 10 via a bearing mechanism.

Here, as shown in FIG. 2 and the like, the direction parallel to the central axis of the shaft 60, which will be described later, is the axial direction, the direction around the central axis of the shaft 60 is the circumferential direction, and the direction perpendicular to the axial direction is the radial direction. Further, for the sake of explanation, the axial direction is taken as the vertical direction, and the rotating part 20 side with respect to the stationary part 10 is taken as the top, and the stationary part 10 side is taken as the bottom.

<Stationary part>
The stationary part 10 includes a base plate 30, a bearing sleeve 40, and a stator core 50.

The base plate 30 is a metal member. As shown in FIG. 2, the base plate 30 is formed with a through hole 31, a circumferential groove portion 32, and a circumferential wall portion 33. The through hole 31 is a hole for fixing the bearing sleeve 40, and is provided so as to penetrate the base plate 30 in the axial direction. Further, the through hole 31 has a cylindrical shape, and the inner diameter of the cylinder is approximately the same as or larger than the outer diameter of the bearing sleeve 40 . The circumferential groove portion 32 is formed on the radially outer side of the through hole 31 . The circumferential groove portion 32 is an annular groove provided so as to be coaxial with the central axis of the through hole 31 when viewed in the axial direction. The circumferential wall portion 33 is formed as an annular wall portion that protrudes upward in the axial direction from the bottom surface of the circumferential groove portion 32 along the through hole 31 when viewed in the axial direction. The circumferential wall portion 33 partitions the through hole 31 and the circumferential groove portion 32.

The bearing sleeve 40 is a cylindrical member made of copper alloy, such as brass, that rotatably supports the shaft 60. The bearing sleeve 40 is inserted into the through hole 31 (see FIG. 2). In the state shown in FIG. 2, the outer peripheral surface 40B of the bearing sleeve 40 faces the inner peripheral surface 31A of the through hole 31. The bearing sleeve 40 is fixed to the through hole 31 by an adhesive applied between the outer peripheral surface 40B of the bearing sleeve 40 and the inner peripheral surface 31A of the through hole 31.

A shaft 60 is disposed inside the bearing sleeve 40 . The inner circumferential surface 40A of the bearing sleeve 40 surrounds the outer circumferential surface 60B of the shaft 60, and the inner circumferential surface 40A and the outer circumferential surface 60B face each other with a small gap in between. This minute gap is filled with lubricating oil (not shown). A radial dynamic pressure generating groove 61 is provided on at least one of the inner peripheral surface 40A and the outer peripheral surface 60B. In the embodiment shown in FIG. 2, the radial dynamic pressure generating grooves 61 are formed in a continuous row in the circumferential direction on the inner circumferential surface 40A, and are formed in two rows spaced apart in the axial direction.

The bearing sleeve 40 is formed with a lower end 40E (an example of an end) in the vertical direction. As shown in FIGS. 2 and 3, the bearing sleeve 40 is formed with an inner recess 41 that opens downward in the radial direction of the lower end 40E and is recessed upward. Further, the bearing sleeve 40 is formed with an outer recess 42 (an example of a recess) that extends along the circumferential direction radially outward of the lower end portion 40E and is recessed upward. In this embodiment, the outer recess 42 is formed along the outer periphery of the bearing sleeve 40, but may be formed radially inward than the outer periphery.

The lower end portion 40E has a tapered cross section whose radial thickness becomes thinner toward the vertical end surface 40S of the lower end portion 40E. Since the outer diameter of the lower end portion 40E becomes smaller toward the bottom, a gap 45 (an example of a first gap) is formed between the lower end portion 40E and a counter plate 44, which will be described later.

A thrust plate 43 is arranged in the inner recess 41 . The thrust plate 43 is an annular flange member fixed to the lower end of the shaft 60 and expanding in the radial direction when viewed in the axial direction. The thrust plate 43 is fixed to the shaft 60 by being press-fitted into the shaft 60 or bonded with an adhesive. By disposing the thrust plate 43 between a lower surface 40C of the bearing sleeve 40 formed in the inner recess 41 and a counter plate 44 described later, movement of the thrust plate 43 and the shaft 60 in the axial direction is prevented. The outer diameter of the thrust plate 43 is smaller than the inner diameter of the inner recess 41. Further, the thickness of the thrust plate 43 in the axial direction is thinner than the depth of the inner recess 41 in the axial direction.

A counter plate 44 is attached to the outer recess 42 . The counter plate 44 is a lid that closes the inner recess 41 of the bearing sleeve 40. The counter plate 44 is made of metal such as iron or copper alloy, and in this embodiment is made of iron such as stainless steel. The counter plate 44 prevents the thrust plate 43 disposed in the inner recess 41 from moving downward and from coming out of the bearing sleeve 40 . The counter plate 44 includes a lid portion 44S that is a disc-shaped member when viewed in the axial direction, and a protrusion 44P that extends along the outer periphery of the lid portion 44S and projects upward from the lid portion 44S. In the state shown in FIG. 2, the lid portion 44S is in contact with the end surface 40S. The diameter of the lid portion 44S is smaller than the outermost diameter of the bearing sleeve 40. The protrusion height of the protrusion 44P from the lid 44S is approximately equal to the axial depth of the outer recess 42. The inner diameter of the protrusion 44P is smaller than the outer diameter of the lower end 40E. The radial thickness t1 of the protrusion 44P is thinner than the radial thickness t2 of the lower end 40E (that is, the thickness t2 of the lower end 40E is thicker than the thickness t1 of the protrusion 44P).

The counter plate 44 is press-fitted below the bearing sleeve 40 with adhesive applied to the outer peripheral surface of the lower end portion 40E. At this time, the protrusion 44P is fitted into the outer recess 42, and the protrusion 44P and the lower end 40E are joined. Furthermore, since the inner diameter of the protrusion 44P is smaller than the outer diameter of the lower end 40E, a portion of the adhesive applied to the lower end 40E comes into contact with the inner peripheral surface of the protrusion 44P and is pushed out toward the end surface 40S. It will be done. A portion of the extruded adhesive accumulates in the gap 45 to form an adhesive pool. That is, the adhesive is held in the gap 45. Note that the counter plate 44 may be press-fitted below the bearing sleeve 40 with adhesive applied to the upper surface of the protrusion 44P and the inner circumference of the protrusion 44P in addition to the outer circumferential surface of the lower end portion 40E. good.

In the state shown in FIG. 3, the upper surface of the thrust plate 43 and the lower surface 40C of the bearing sleeve 40 face each other with a small gap in between. Further, the lower surface of the thrust plate 43 and the upper surface of the lid portion 44S of the counter plate 44 face each other with a small gap in between. These minute gaps are filled with lubricating oil (not shown).

A thrust dynamic pressure generating groove is provided on at least one of the upper surface of the thrust plate 43 and the lower surface 40C of the bearing sleeve 40 (in the present embodiment, the upper surface of the thrust plate 43). Furthermore, a thrust dynamic pressure generating groove is provided at a portion of the upper surface of the lid portion 44S that faces the thrust plate 43. Note that a thrust dynamic pressure generating groove may be provided on the lower surface of the thrust plate 43 that faces the upper surface of the lid portion 44S.

The stator core 50 is a member in which a plurality of annular electromagnetic steel plates are laminated in the axial direction when viewed in the axial direction. The stator core 50 is disposed inside the circumferential groove 32 and fixed to the outer circumferential surface of the circumferential wall 33 by a method such as adhesion. Further, the stator core 50 has a plurality of pole teeth (salient poles) extending radially outward and arranged along the circumferential direction. A coil 51 is wound around the pole teeth. When current flows through the coil 51, the stator core 50 generates magnetic flux.

<Rotating part>
The rotating section 20 includes a shaft 60, a rotor hub 70, and a rotor magnet 80.

The shaft 60 is a columnar iron member made of stainless steel or the like and serves as a rotation axis of the spindle motor 3, and is arranged inside the bearing sleeve 40. Further, the upper end of the shaft 60 protrudes from the bearing sleeve 40. Note that the radial dynamic pressure generating groove 61 may be provided not on the inner circumferential surface 40A of the bearing sleeve 40 but on a portion of the outer circumferential surface 60B of the shaft 60 that faces the inner circumferential surface 40A.

The rotor hub 70 is attached to the upper end of the shaft 60 and rotates together with the shaft 60. The rotor hub 70 has a disk portion 71, a cylindrical portion 72, and an outer edge portion 73. The disc portion 71 is a disc-shaped member that is disposed above the bearing sleeve 40 and is coaxial with the central axis of the shaft 60 when viewed in the axial direction. A through hole 74 is provided in the center of the disc portion 71. The disk portion 71 is fixed to the shaft 60 by fixing the upper end of the shaft 60 to the through hole 74 by a method such as press fitting or adhesion. Note that the lower surface of the disc portion 71 and the upper surface of the bearing sleeve 40 face each other with a gap between them. The cylindrical part 72 is a cylindrical member having a constant thickness in the radial direction, and extends downward from the outer edge of the lower surface of the disc part 71. The inner diameter of the cylindrical portion 72 is larger than the outer diameter of the bearing sleeve 40, and the inner circumferential surface and the outer circumferential surface 40B of the cylindrical portion 72 face each other with a gap between them. The outer diameter of the cylindrical portion 72 is the same as the outer diameter of the disk portion 71. The outer edge portion 73 is a member that protrudes radially outward at the lower end of the cylindrical portion 72 when viewed in the axial direction, and extends in a flange shape over the entire circumference in the circumferential direction.

The rotor magnet 80 is an annular member having a magnetic pole structure in which the polarity is reversed as N, S, N, S, etc. along the circumferential direction when viewed in the axial direction. In the embodiment shown in FIG. 2, the rotor magnet 80 is attached to the inner peripheral surface of an annular yoke 81 attached to the lower end of the outer edge 73. The rotor magnet 80 is located at approximately the same position as the stator core 50 in the axial direction, and is located between the stator core 50 and the inner peripheral surface of the circumferential groove portion 32 in the radial direction. Yoke 81 suppresses leakage of magnetic flux from rotor magnet 80. The cylindrical portion 72 or the outer edge portion 73 is disposed between the stator core 50 and the inner circumferential surface of the circumferential groove portion 32, and the annular yoke 81 is disposed between the inner circumferential surface of the cylindrical portion 72 or the inner circumferential surface of the outer edge portion 73. It may be attached. In that case, rotor magnet 80 is attached to the inner peripheral surface of yoke 81 so as to face stator core 50 .

<Spindle motor operation>
When the coil 51 is energized, the magnetic attraction force and the magnetic repulsion force generated between the magnetic poles of the rotor magnet 80 and the pole teeth of the stator core 50 are switched. As a result, the rotating section 20 rotates with respect to the stationary section 10 using the shaft 60 as the rotation axis.

Shaft 60 rotates relative to bearing sleeve 40 . At this time, dynamic pressure is generated by pressurizing the lubricating oil by the radial dynamic pressure generating groove 61. Due to the generated dynamic pressure, the shaft 60 is supported in a radial direction with respect to the bearing sleeve 40 in a non-contact state.

As shaft 60 rotates, thrust plate 43 rotates relative to bearing sleeve 40 and counterplate 44. At this time, a thrust dynamic pressure generating groove provided on at least one of the upper surface of the thrust plate 43 or the lower surface 40C of the bearing sleeve 40, and a thrust dynamic pressure generating groove provided on the upper surface of the cover portion 44S of the counter plate 44 Dynamic pressure is generated by pressurizing the lubricating oil. Due to the generated dynamic pressure, the thrust plate 43 is supported in the axial direction with respect to the bearing sleeve 40 and the counter plate 44 in a non-contact state. Note that even when a thrust dynamic pressure generation groove is provided on the lower surface of the thrust plate 43, the above operation allows the thrust plate 43 to be supported in an axially non-contact state with respect to the bearing sleeve 40 and the counter plate 44. .

<Effect>
In the above embodiment, the spindle motor 3 includes a columnar shaft 60 extending in the axial direction, an annular thrust plate 43 attached to one end of the shaft 60, and rotatably supporting the shaft 60. A cylindrical bearing sleeve 40 with orthogonal radial directions has a lower end 40E in the axial direction, and an outer recess 42 that extends along the circumferential direction and has a depth in the axial direction. A counter plate 44 includes a bearing sleeve 40 formed outward in the direction, a lid 44S that covers a lower end 40E, and a protrusion 44P that projects from the lid 44S to the outer recess 42 and joins the lower end 40E. , the bearing sleeve 40 and the counter plate 44 are joined with adhesive.

According to such a configuration, an outer recess 42 that extends along the circumferential direction and has a depth in the axial direction is formed radially outward of the lower end portion 40E, and the protrusion 44P of the counter plate 44 is formed in the outer recess 42. is inserted and joined to the lower end portion 40E, so that the axial length of the joined portion can be made longer than the thickness of the counter plate 44. Since the lower end portion 40E and the protrusion 44P are bonded using an adhesive, the longer the length of the bonded portion, the more firmly the bond can be made. In other words, the counter plate 44 that closes the opening can be firmly joined to the bearing sleeve 40.

Furthermore, in such a spindle motor 3, since the counter plate 44 is firmly joined to the bearing sleeve 40, the shaft 60 can support a larger axial load.

Furthermore, since the inner recess 41 is filled with lubricating oil, it is preferable that the adhesive does not enter the inner recess 41 when the counter plate 44 is joined to the bearing sleeve 40 . According to the above configuration, the outer circumferential surface of the lower end portion 40E serving as the joint surface is separated from the inner recess 41. As a result, it is difficult for the adhesive to enter the inner recess 41.

Conventionally, the counter plate 44 made of iron is difficult to weld to the bearing sleeve 40 made of copper alloy instead of iron, so an iron sleeve case is attached to the outer periphery of the bearing sleeve 40, and the counter plate 44 and the sleeve case are joined by welding. Was. According to the above configuration, the counter plate 44 and the bearing sleeve 40 are directly joined by joining the lower end portion 40E and the protrusion 44P with an adhesive. As a result, the number of parts of the spindle motor 3 is reduced and a welding process is no longer necessary, so that the manufacturing cost of the spindle motor 3 is reduced.

Further, in the counter plate 44 of the spindle motor 3 according to the present embodiment, a thrust dynamic pressure generating groove is formed in a portion facing the thrust plate 43 of the lid portion 44S.

According to this configuration, since the thrust dynamic pressure generating groove is formed in the portion of the lid portion 44S that faces the thrust plate 43, there is no need to provide the thrust dynamic pressure generating groove on the lower surface of the thrust plate 43. As a result, it is not necessary to form thrust dynamic pressure generating grooves on the lower surface of the thrust plate 43, so that the thrust plate 43 can be manufactured easily.

Further, the bearing sleeve 40 of the spindle motor 3 according to the present embodiment has a lower end 40E having an end surface 40S in the axial direction, forming a tapered cross section that becomes thinner toward the end surface 40S, and the adhesive is applied to the lower end. It is held in a gap 45 formed between 40E and the counter plate 44.

According to such a configuration, a gap 45 is formed between the bearing sleeve 40 and the counter plate 44. When joining the counter plate 44 to the bearing sleeve 40, a part of the adhesive applied to the outer peripheral surface of the lower end 40E comes into contact with the inner peripheral surface of the protrusion 44P and is pushed out toward the end surface 40S. . The extruded adhesive collects in the gap 45 and forms an adhesive pool. As a result, the bearing sleeve 40 and the counter plate 44 are more firmly joined.

Further, the counter plate 44 of the spindle motor 3 according to this embodiment is joined to the bearing sleeve 40 by press fitting.

According to such a configuration, the counter plate 44 is joined to the bearing sleeve 40 not only by adhesive bonding but also by press fitting. As a result, the bearing sleeve 40 and the counter plate 44 are bonded more firmly than with adhesive alone.

Further, in the spindle motor 3 according to the present embodiment, the thickness t2 of the lower end portion 40E is thicker than the thickness t1 of the protrusion 44P in the radial direction of the shaft 60.

According to such a configuration, since the thickness t2 of the lower end portion 40E is thicker than the thickness t1 of the protrusion 44P in the radial direction, it is difficult to deform when a radially inward force is applied to the lower end portion 40E. As a result, when the counter plate 44 is press-fitted into the bearing sleeve 40, the lower end portion 40E is not easily deformed radially inward, so that the spindle motor 3 can be assembled with high precision.

Furthermore, the bearing sleeve 40 of the spindle motor 3 according to this embodiment is made of copper alloy.

According to such a configuration, since the bearing sleeve 40 is made of a copper alloy, the bearing sleeve 40 has high wear resistance against the iron shaft 60. As a result, the life of the spindle motor 3 is extended.

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

According to this configuration, the hard disk drive device 1 includes the spindle motor 3 that can support a larger axial load, so the number of recording disks 4 supported by the spindle motor 3 can be increased. In other words, the recording capacity of the hard disk drive 1 can be increased.

Further, the hard disk drive device 1 according to the present embodiment further includes a housing 9, the spindle motor 3 is disposed within the housing 9, and the inside of the housing 9 is sealed.

According to such a configuration, the inside of the casing 9 is sealed and the spindle motor 3 is disposed in the internal space S, so that foreign substances such as dust are difficult to enter from the outside of the casing 9. As a result, the spindle motor 3 is less likely to fail.

Further, when the internal space S is filled with helium gas or the like having a lower density than air, the gas resistance in the internal space S is reduced, so that uneven rotation and vibration of the recording disk 4 are reduced. As a result, the recording disks 4 can be operated with higher precision, so the number of recording disks 4 mounted on the hard disk drive device 1 can be increased. In other words, the recording capacity of the hard disk drive 1 can be increased.

<Modified example>
You may apply the changes described below in combination.

(1) Modification example 1
In the embodiment described above, the lower end portion 40E is formed with a tapered cross section in which the thickness in the radial direction becomes thinner toward the end surface 40S in the vertical direction. However, the shaft end recess 46 may be formed in the lower end 40E instead of the tapered cross section.

As shown in FIG. 4, the shaft end recess 46 is formed in the lower end 40E so as to extend along the circumferential direction and to be recessed upward. In the embodiment shown in FIG. 4, the shaft end recess 46 is formed at the radially outer edge of the lower end 40E, which is radially inward than the outer recess 42. Since the shaft end recess 46 has a square cross section, a square gap 145 is formed between the lower end 40E and the counter plate 44.

When the counter plate 44 is joined below the bearing sleeve 40 with adhesive, the adhesive is applied to the outer peripheral surface of the lower end portion 40E. When the counter plate 44 is fitted into the bearing sleeve 40 from below, a portion of the applied adhesive is pushed out toward the end surface 40S. A portion of the extruded adhesive collects in the gap 145 and forms an adhesive pool. That is, the adhesive is retained in the gap 145. Note that the adhesive may be applied not only to the outer circumferential surface of the lower end portion 40E but also to the upper surface of the protrusion 44P and the inner circumferential surface of the protrusion 44P.

According to such a configuration, since an adhesive pool is formed in the gap 145, the bearing sleeve 40 and the counter plate 44 are more firmly joined.

Note that the above-described tapered cross section and shaft end recess 46 may not be formed in the lower end portion 40E.

(2) Modification 2
In the above embodiment, the inner diameter of the protrusion 44P is smaller than the outer diameter of the lower end 40E, and the counter plate 44 is joined to the bearing sleeve 40 by press fitting and bonding with an adhesive. However, the counter plate 44 may be joined to the bearing sleeve 40 only by adhesive bonding by making the inner diameter of the protrusion 44P larger than the outer diameter of the lower end portion 40E.

(3) Modification example 3
In the above embodiment, the radial thickness t2 of the lower end portion 40E is thicker than the radial thickness t1 of the protrusion 44P. However, the radial thickness t2 of the lower end portion 40E may be the same as or thinner than the radial thickness t1 of the protrusion 44P.

(4) Modification example 4
In the above embodiment, the height of the protrusion 44P protruding from the lid 44S is approximately equal to the axial depth of the outer recess 42. However, as shown in FIG. 5, the protrusion 44P may be a protrusion 144P in which the protrusion height of the protrusion 44P from the lid 44S is shorter than the axial depth of the outer recess 42.

Since the protrusion height of the protrusion 144P from the lid 44S is shorter than the axial depth of the outer recess 42, a gap 147 (an example of a second gap) is formed between the upper surface of the protrusion 144P and the lower surface of the outer recess 42. is formed.

When the counter plate 44 is joined below the bearing sleeve 40 with adhesive, the adhesive is applied to the outer peripheral surface of the lower end portion 40E. When the counter plate 44 is fitted into the bearing sleeve 40 from below, the upper surface of the protrusion 144P and the lower surface of the outer recess 42 do not come into contact with each other, and a gap 147 is formed. A portion of the applied adhesive accumulates in the gap 147 to form an adhesive pool. That is, the adhesive is retained in the gap 147. Note that the adhesive may be applied not only to the outer circumferential surface of the lower end portion 40E but also to the upper surface of the protrusion 44P and the inner circumferential surface of the protrusion 44P. Also, adhesive may be sealed in the gap 147 after the counter plate 44 is fitted into the bearing sleeve 40.

According to such a configuration, since the adhesive is held in the gap 147, the bearing sleeve 40 and the counter plate 44 are more firmly joined.

Further, as shown in FIG. 6, the protrusion 144P is a protrusion 244P in which the upper surface of the protrusion 144P is inclined in the radial direction, and the protrusion height from the lid part 44S increases toward the radial inward side. It's okay.

Since the protrusion height of the protrusion 244P from the lid part 44S is shorter than the axial depth of the outer recess 42, the upper surface of the protrusion 244P is inclined in the radial direction, and is higher toward the radial inside. A gap 247 is formed between the upper surface of the protrusion 244P and the lower surface of the outer recess 42. The height of the gap 247 in the axial direction becomes shorter toward the inner side in the radial direction.

Like the gap 147, the gap 247 retains the adhesive accumulated on the upper side of the protrusion 244P or the adhesive sealed in the gap 247 after the counter plate 44 is fitted into the bearing sleeve 40. Here, since the height of the gap 247 in the axial direction becomes shorter toward the inner side in the radial direction, a capillary force acts on the adhesive held in the gap 247 in the inner direction in the radial direction. As a result, the adhesive is easily held in the gap 247, so that the bearing sleeve 40 and the counter plate 44 are more firmly joined.

DESCRIPTION OF SYMBOLS 1...Hard disk drive device, 3...Spindle motor, 9...Casing, 40...Bearing sleeve, 40E...Lower end (end), 40S...End face, 42...Outer recess (recess), 43...Thrust plate, 44...Counter Plate, 44P, 144P, 244P... Protrusion, 44S... Lid, 45... Gap (first gap), 60... Shaft, 147, 247... Gap (second gap) t1... Thickness of protrusion 44P, t2... Thickness of lower end 40E

Claims (9)

a columnar shaft extending in the axial direction;
an annular thrust plate attached to one end of the shaft;
A cylindrical bearing sleeve that rotatably supports the shaft, has a circumferential direction and a radial direction perpendicular to the circumferential direction, has an end in the axial direction, extends along the circumferential direction, and has a radial direction perpendicular to the circumferential direction. a bearing sleeve in which the axially deep recess is formed on the radially outward side of the end portion;
a counter plate having a lid portion that covers the end portion; and a protrusion that protrudes from the lid portion into the recess and joins the end portion;
Equipped with
A spindle motor in which the bearing sleeve and the counter plate are joined via an adhesive. The spindle motor according to claim 1, wherein a dynamic pressure groove is formed in a portion of the lid portion that faces the thrust plate. The end portion has an end surface in the axial direction, and a tapered cross section that becomes thinner toward the end surface, and the adhesive is formed between the end portion and the counter plate. The spindle motor according to claim 1 or 2, wherein the spindle motor is held in a gap. The spindle motor according to any one of claims 1 to 3, wherein the adhesive is held in a second gap formed between the recess and the protrusion. The spindle motor according to any one of claims 1 to 4, wherein the counter plate is joined to the bearing sleeve by press fitting. The spindle motor according to claim 5, wherein the thickness of the end portion is thicker than the thickness of the protrusion in the radial direction of the shaft. The spindle motor according to any one of claims 1 to 6, wherein the bearing sleeve is made of a copper alloy. A hard disk drive device comprising the spindle motor according to any one of claims 1 to 7. The hard disk drive further includes a housing,
The hard disk drive according to claim 8, wherein the spindle motor is disposed within the casing, and the inside of the casing is sealed.

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