JPH10248223A - Spindle motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to firmly fix a stator to a shaft without allowing the stator to scratch the surface of the shaft and, at the same time, to proceed to the next process without waiting for the curing of the adhesive used for fixing the stator to the shaft. SOLUTION: In the case of fixing the stator 32 of a separate-bearing type spindle motor to a shaft 24 between a front bearing 26 and a rear bearing 28, a core holder 48 for fixing the stator 32 to the shaft 24 is used. While the core holder 48 is originally attached to the shaft 24 through a hollow hole 48d having a diameter d4 larger than that 31 of the shaft 24, the stator 32 is fixed to the shaft 24 through the holder 48, because the holder 48 is fixed to the shaft 24 in a tightly fitted state when the stator 32 is fit-inserted into the holder 48.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor, and more particularly to a spindle motor of a separate bearing type. More specifically, the present invention relates to a spindle motor that does not generate noise during operation and can be assembled in a short time and at low cost.

[0002]

2. Description of the Related Art Various types of separate bearing type spindle motors have been disclosed. For example, FIG.
Japanese Patent Application Laid-Open No. Hei 7-286619 as shown in FIG. In this spindle motor 1, a rotor hub 6 is rotatably supported via a pair of bearings 4, 5 which are vertically separated and arranged on a shaft 3 having a lower end fixedly held at the center of a bracket 2, Further, a stator 7 is fixed between the bearings 4 and 5 with respect to the shaft 3, and a rotor magnet 8 is provided on the inner peripheral surface of the rotor hub 6 so as to face the stator at a small interval on the outer periphery of the stator 7. Is fixed.

In the spindle motor 1, a stepped portion 3a is formed below the shaft 3, and a rear bearing 5 and a stator 7 are positioned with respect to a lower surface and an upper surface of the stepped portion 3a. In the process of assembling the stator 7, the stator 7 is inserted into the shaft 3 from above, and an adhesive is interposed between the outer peripheral surface of the shaft 3 and the inner peripheral surface of the stator 7 to attach the stator 7 to the shaft 3. After fixing, the front bearing 4 is fixed to the outer peripheral surface of the upper part of the shaft 3 with an adhesive.

A spindle motor as shown in FIG. 5 is also known as another separate bearing type spindle motor (Japanese Patent Laid-Open No. 7-336977).
In this spindle motor 10, a shaft 11 whose lower end is fixedly held to a base of a hard disk device or the like is provided.
, A rotor hub 15 is rotatably supported via a front bearing 12, a rear bearing 13 and an annular bush 14 fixed thereto.
13, a stator 17 is fixed via a core holder 16 fixed to the shaft 11.
The rotor magnet 18 is fixed to the inner peripheral surface of the rotor hub 15 so as to face the rotor hub 15. Here, the core holder 16 includes a circular flat plate portion 16a extending from the shaft 11 radially outward to the vicinity of the outer peripheral portion of the stator 17 and a shaft flat plate 16a extending from the inner peripheral portion of the flat plate portion 16a. And a cylindrical portion 16b extending to an intermediate position of the stator 17 along an outer peripheral surface of the stator 17. The inner diameter of the cylindrical portion 16b is a size that is tightly fitted to the shaft 11, while the outer diameter of the cylindrical portion 16b is a size that is tightly fitted to the inner peripheral portion of the stator 17. ing.

In this spindle motor 10, a stepped portion 1 supporting a core holder 16 is provided below a shaft 11.
1a and a stepped portion 11b supporting the rear bearing 13
Are formed, thereby positioning the core holder 16 and the rear bearing 13. In the assembling process, first, the rear bearing 13 is bonded and held to the stepped portion 11b on the lower outer peripheral surface of the shaft 11, and then the core holder 16 is attached to the stepped portion 11a on the intermediate outer peripheral surface of the shaft 11, or The core holder 16 to which the stator 17 is adhered and held is inserted from above the shaft 11, and an adhesive is interposed between the outer peripheral surface of the shaft 11 and the inner peripheral surface of the cylindrical portion 16 b of the core holder 16, and the core holder 16 is inserted. After fixing to the shaft 11, the front bearing 12 and the rotor hub 15, which previously fixes the rotor magnet 18 to the inner peripheral surface, are fixed to the outer peripheral surface of the upper portion of the shaft 11 with an adhesive.

[0006]

However, in the first spindle motor 1 shown in FIG. 4, when the stator 7 is mounted on the shaft 3, after the stator 7 is inserted into the shaft 3, the stator 7 is It must be slid along the outer peripheral surface of the shaft 3 until it reaches the attachment portion 3a. However, during the sliding movement, the stator 7 may cause scratches on the outer peripheral surface of the shaft 3. If the scratch occurs on the mounting surface of the front bearing 4 of the shaft 3, the mounting state of the front bearing 4 is likely to fluctuate, making it difficult to obtain stable rotation of the rotor hub 6 and causing noise. There was a problem that could be the cause. In order to prevent such damage beforehand, it is necessary to increase the accuracy of the stator 7 itself and the accuracy of the assembly device of the spindle motor 1, which is a major problem in terms of cost. Furthermore, in the spindle motor 1 having such a configuration, during the assembling process,
After fixing the stator 7 to the shaft 3 via an adhesive, the front bearing 4 is fixed to the shaft 3. To prevent displacement of the stator 7, an adhesive for fixing the stator 7 to the shaft 3 is used. It is necessary to wait for the curing to be completed before proceeding to the next step, which causes a problem that the assembling time is prolonged by the curing time of the adhesive. Further, in forming the shaft 3, it is necessary to form the stepped portion 3a at a position below the shaft 3, so that there is a problem that the processing is more difficult than the processing of a shaft having the same diameter as a whole.

Furthermore, in the second spindle motor 10 shown in FIG. 5, when the core holder 16 is mounted on the shaft 11, the core holder 16 scratches the outer peripheral surface of the shaft 11 instead of the stator 7 shown in FIG. Scratching is the same. As a result, the same problem as in the case of the spindle motor shown in FIG. 4 remains. Also,
In the spindle motor 10, the front bearing 12 is fixed to the shaft 11 after the core holder 16 is fixed to the shaft 11 via an adhesive during the assembling process, similarly to the spindle motor 1 shown in FIG. ,
It is necessary to wait for the adhesive for fixing the core holder 16 to the shaft 11 to be completely cured before proceeding to the next step. Therefore, the assembling time becomes longer by the curing time of the adhesive, and further, the shaft 11 In the forming process of
It is necessary to form two stepped portions 11a and 11b at the lower position, and it is difficult to machine the whole compared with the machining of the shaft having the same diameter as in the case of the embodiment shown in FIG. is there.

It is an object of the present invention to completely solve the problems of these known spindle motors by extremely simple means.

[0009]

According to the present invention, a housing 22 and a shaft 24 having a lower end fixedly held near a center of the housing 22 are provided.
A rotor hub 30 rotatably mounted on the shaft 24 via a front bearing 26 and a rear bearing 28; and a shaft between the rotor hub 30 and the shaft 24 and between the pair of bearings 26, 28. Stator 32 fixed to 24
And a rotor magnet 36 attached to the inner peripheral surface side of the rotor hub 30 and fixed at a small interval radially outward of the stator 32. Although initially mounted on the shaft 24 via a hollow hole 48d having a diameter d4 larger than the diameter d1 of the shaft 24, when the stator 32 is inserted into the core holder 48, the core holder 48 The stator 32 is fixed to the shaft 24 via the core holder 48 by being fixed in an interference fit state.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. 1 which discloses a preferred embodiment of the present invention. A separate bearing type spindle motor 20 shown in FIG. 1 includes a bracket or housing 22, a shaft 24 having a lower end fixedly held near a center of the housing 22, and a shaft 24.
A rotor hub 30 made of a non-magnetic material such as aluminum, which is rotatably mounted via a front bearing 26 at an upper position in the drawing and a rear bearing 28 at a lower position in the drawing, and the pair of bearings 26, 28. The stator 3 fixed to the shaft 24
2, a yoke 34 attached to the inner peripheral surface side of the rotor hub 30, and fixed to the yoke 34 at a small interval radially outward of the stator 32 between the yoke 34 and the stator 32. And the rotor magnet 36 that is provided. When the rotor hub is made of a magnetic material, the rotor hub functions as a yoke, and the rotor magnet is mounted directly on the inner peripheral surface of the rotor hub.

The housing 22 according to the present invention has an opening 22a near the center thereof for receiving the lower end of the shaft 24, and a rising portion 2 rising upward at the outer periphery.
2b are integrally provided.

The shaft 24 used in the present invention has a columnar shape having the same diameter d1 over the entire length. A hole 24a is provided at the center of the shaft 24 and extends upward from the lower end thereof to the vicinity of the intermediate portion along the axial direction. A flexible printed circuit (FPC) having one end in contact with the stator 32 and the other end adhered to the housing 22 is formed in the hole 24a.
A lead wire 40 to 38 is inserted. The intermediate portion of the lead wire 40 is sealed by a sealing member 42 as necessary.
4a, it is sealed and held.

The lower end of the shaft 24 is fixed to the housing 22 using an adhesive or the like known per se. Further, an inner ring of a rear bearing 28 is fitted and held, preferably also using an adhesive, at a portion immediately above the lower end portion fixed to the housing 22. The rear bearing 28 is positioned with respect to the upper surface of the housing.

A bearing holder 44 is preferably fixed to the outer ring of the rear bearing 28. The bearing holder 44 includes a vertical rising portion 44a rising from the outer ring of the rear bearing 28 toward the front bearing 26, and a radially outwardly expanding upper portion of the vertical rising portion 44a. Diameter 44
b. The inner peripheral portion of the enlarged diameter portion 44b presses and holds the rear bearing 28 toward the housing 22, thereby holding the rear bearing 28 at a predetermined position. The outer peripheral portion of the enlarged diameter portion 44b is
Is closely supported. Here, the inner peripheral surface of the vertical upright portion 44a is fixed to the outer ring of the rear bearing 28 using an adhesive as necessary. On the other hand, the vertical rising portion 44a
Is arranged opposite to the inner peripheral surface of the rising portion 22b of the housing 22, and a labyrinth seal is formed by a minute gap formed on the opposed surface. This prevents oil mist components that may be generated from the rear bearing 28 from scattering outside the spindle motor 20.

An inner race of a front bearing 26 is fixed to the upper portion of the shaft 24 by substantially the same means as the rear bearing 28. A rotor hub 30 is attached to the outer ring of the front bearing 26.

The rotor hub 30 has an upper wall portion 30a extending radially outward from the front bearing 26,
A hanging part 30b hanging from an outer peripheral part of the upper wall part 30a.
And a lower wall portion 30c connected to the lower end portion of the hanging portion 30b and closely supported by the enlarged diameter portion 44b of the bearing holder 44, preferably integrally.

On the inner peripheral portion of the upper wall portion 30a, a projection for supporting the front bearing 26 from below and holding the front bearing 26 at a predetermined position, and an outer ring of the front bearing as necessary. It has a vertical wall fixed by an adhesive or the like, and an extension extending further upward from the vertical wall along the axial direction. A labyrinth cap 46 is provided on the radially inner surface of the extension and outside the front bearing 26, that is, on the upper surface in the drawing.
Are fixed, for example, by press fitting. At the center of the labyrinth cap 46, a hole through which the shaft 24 passes is formed. A small gap is formed between the hole and the outer surface of the shaft 24, and the small gap forms a virulence seal. This prevents oil mist components generated from the front bearing 26 from scattering outside the spindle motor 20.

A yoke 34 is fixed to the inner surface of the hanging portion 30b by a known means. Further, an enlarged diameter portion 44b of the bearing holder 44 is fixed to the inner surface of the lower wall portion 30c by using an adhesive or the like as necessary, and is radially outwardly attached to the outer surface of the lower wall portion 30c. An overhanging step is formed. The step has a function of holding a disk (not shown).

The shaft 24 has
The stator 32 is fixed in a space between the front bearing 26 and the rear bearing 28 in a space between the front bearing 26 and the inner surface of the hanging portion 30 b constituting the rotor hub 30. In order to fix the stator 32 to the shaft 24, the present invention uses a core holder 48.

As shown in FIG. 2, the core holder 48 includes an upper portion 48a and a lower portion 48b. The outer diameter d2 of the upper part 48a is smaller than the outer diameter d3 of the lower part 48b, and the two parts are connected by a step part 48c, and are preferably integrally formed, for example, of an aluminum material. Furthermore, this core holder 48
Has a hollow hole 48d having a constant inner diameter d4 penetrating vertically from the upper portion 48a to the lower portion 48b. The hollow hole 48d has an inner diameter slightly larger than the outer diameter d1 of the shaft 24 by, for example, about several μm. Therefore, there is no danger of the core holder 48 scratching the surface of the shaft 24 when the core holder 48 is inserted into the shaft 24. Here, as shown by a two-dot chain line in FIG. 2, a groove 48e extending in the vertical direction may be formed in the upper portion 48a to absorb radially inward deformation of the upper portion. . This groove 48
The number of e is not limited to one, but a plurality of e can be provided, but preferably three, and they are arranged at intervals of 120 °. In the case where a plurality of grooves are provided, it is desirable that they are arranged at an equal angle from each other.
This is because the entire upper portion 48a is uniformly deformed. Such a groove 48e is less necessary when the core holder 48 is made of a soft material such as aluminum, but is preferably provided when the core holder 48 is made of another hard material. Of course, it can be provided also in the case of aluminum or the like. Further, the upper end corner 48f of the upper portion 48a is chamfered sufficiently smoothly. This is because the stator 32 is smoothly and surely secured during assembly as described later.
In order to be able to enter the upper part 48a.

The lower end 48h of the lower portion 48b of the core holder 48 is disposed in contact with the rear bearing 28.
As described above, the dimension d4 of the hollow hole 48d of the core holder 48
Is slightly larger than the dimension d1 of the shaft 24, it is easy to insert the core holder 48 into the shaft 24, and at this time, the core holder 48 does not scratch the shaft 24.

The stator 32 is mounted on the upper portion 48a of the core holder 48 from above. Here, the stator 32
Is larger than the outer diameter d1 of the shaft 24 (d6> d1), but the upper part 4 of the core holder 48
For example, the outer diameter dimension d2 is set to be slightly smaller than the outer diameter dimension d2 by several tens μm (d2> d6). That is, each dimension is
d3>d2>d6>d4> d1.

Thus, the upper portion 48a of the core holder 48, which is slightly loosely inserted through the shaft 24,
When the stator 32 is forcibly pushed in from above in order to dispose the stator 32, the stator 32 is inserted into the upper portion 48a of the core holder 48 via the chamfered portion of the upper end corner 48f of the core holder 48, Further, the stator 32 reaches the step portion 48c of the core holder while forcing the stator 32 downward to push the upper portion 48a of the core holder 48 inward in the radial direction. At this time, the upper portion 48a is forcibly pressed to the shaft 24 side to tighten the shaft 24 because of the above dimensions. As a result, the stator 32 is immovably fixed to the shaft 24 via the core holder 48. That is, the stator 32 is press-fitted and fixed to the core holder 48, and the upper portion 48a of the core holder 48 contracts inward in the radial direction and is tightly fitted to the outer peripheral surface of the shaft 24. The inner peripheral edge lower surface of the stator 32 abuts against the step portion 48c of the core holder 48, and is appropriately positioned.
An adhesive is applied in advance to the portion of the shaft 24 where the core holder 48 is to be positioned, and the outer surface and the step portion 48c of the upper portion 48a of the core holder 48, and the core holder 48 is It is preferable that the stators 32 are respectively adhered and fixed to each other.

FIG. 3 shows another embodiment of the core holder. In the core holder 48 shown in FIGS. 1 and 2, the upper portion 48a is configured to have a constant wall thickness from the step portion 48c to the upper end portion 48g. However, in the core holder 48A shown in this embodiment, Shaft 24
The upper portion 48a has a hollow hole 48d having a certain dimension d4 which penetrates vertically to receive the upper portion 48a. The outer diameter of the upper portion 48a is reduced so that the wall thickness becomes thinner as the upper portion 48a approaches the upper end portion 48g from the step portion 48c. Are different in that they gradually decrease. That is, the outer peripheral edge diameter of the step portion 48c is the same as the outer diameter dimension d3 of the lower portion 48b, and
The inner peripheral edge diameter of 8c is the same as the outer diameter dimension d2 of the upper part 48a shown in FIG. 2, but the outer diameter dimension of the upper end part 48g of the core holder 48A shown in FIG. 3 is the upper end part 48g of the core holder 48 shown in FIG. Has a diameter d5 smaller than the outer diameter dimension d2. Here, the dimension d of the core holder
2, d3, d4, d5 and the inner diameter d6 of the stator 32
And the outer diameter dimension d1 of the shaft 24 is d3>d2> d
6>d5>d4> d1. Also in this case, it is preferable that the upper end corner portion 48f is chamfered and a predetermined number of grooves 48e are provided as necessary similarly to the previous embodiment.

In this embodiment, since the dimensions are in the relationship described above, the operation for mounting the stator 32 on the core holder 48 can be more easily achieved.

A rotor magnet 36 is arranged at a small interval radially outward of the stator 32. The rotor magnet 36 is fixed to the inner surface of the yoke 34 with an adhesive or the like.

Hereinafter, the spindle motor 20 of the present invention will be described.
The procedure for assembling the components will be described. First, the lower end of the shaft 24 is fixed to the housing 22 by using an adhesive if necessary. After that, the inner ring of the rear bearing 28 with the bearing holder 44 attached to the outer ring is bonded and fixed to the shaft 24. When mounting the rear bearing 28 on the shaft 24, the rear bearing 28
By pressing the lower end surface of the inner ring on the upper surface of the housing 22, the position of the rear bearing 28 with respect to the housing 22 is reliably specified. Further, before fixing the shaft 24 to the housing 22, it is also possible to mount the rear bearing 28 and / or the bearing holder 44 on the shaft 24 in advance, and then fix the shaft 24 to the housing 28. In this case, since the rear bearing 28 can be inserted from below the shaft 24, the operation is easy.

Next, the core holder 48 is inserted into the shaft 24. Since the inner diameter d4 of the core holder 48 is slightly larger than the outer diameter d1 of the shaft 24, the
There is no worry that the surface 8 will scratch the surface of the shaft 24. Preferably, an adhesive is applied in advance to the portion of the shaft 24 to which the core holder 48 is fixed, and if the core holder 48 is arranged at a predetermined position, it is preferable that the adhesive is securely fixed at that position.

Thereafter, the lead wire 40 of the stator 32 formed by winding a coil around the core in advance is inserted into the hole 24a of the shaft 24, and the lead wire 40 is inserted into the hole 24a.
After sealing and fixing the inside thereof with a sealing member 42, the stator 32
Into the outer peripheral surface of the upper portion 48a of the core holder 48. At this time, it is preferable to apply an adhesive in advance to the outer peripheral surface of the upper portion 48a of the core holder 48. If the stator 32 is arranged at a predetermined position on the core holder 48, it is to be surely fixed by the adhesive at that position. Diameter d of inner circumferential surface of stator 32
6 is slightly smaller than the diameter d2 of the outer peripheral surface of the upper portion 48a of the core holder 48, so that the inner peripheral surface of the stator 32 is difficult to fit into the outer peripheral surface of the upper portion 48a of the core holder 48. By chamfering the upper end corner portion 48f sufficiently, the chamfered portion provides a means for introducing the stator 32. For this reason, it is preferable to perform the chamfering operation until the diameter of the chamfered upper end portion 48g is substantially equal to or slightly smaller than the dimension d6. Further, as shown in FIG. 3, the outer diameter of the upper portion 48a is gradually reduced as going upward, and the outer diameter d5 of the outer peripheral surface at the upper end of the upper portion 48a is made larger than the diameter d6 of the inner peripheral surface of the stator 32. By making the configuration smaller, the stator 32 can be more easily fitted and inserted.

Next, the outer ring of the front bearing 26 is fixed to the rotor hub 30 in which the yoke 34 and the rotor magnet 36 have been previously incorporated into the hanging portion 30b of the rotor hub 30. Thereafter, the inner ring of the front bearing 26 is inserted into the shaft 24, and the front bearing 26 is bonded and fixed to the shaft 24. At the same time, the outer peripheral portion of the enlarged diameter portion 44b of the bearing holder 44 is fitted to the lower end portion 30c of the rotor hub 30. At this time, it is preferable to apply an adhesive to the outer ring positioning portion of the shaft 24 and the lower end portion 30c of the rotor hub 30. This is because if each member is positioned at a predetermined position, it is securely fixed by the adhesive at that position.

Finally, the tip of the lead wire 40 is soldered to the FPC 38 attached to the housing 22, and the labyrinth cap 46 is adhesively fixed on the upper part of the rotor hub 30.

[0032]

The spindle motor 20 according to the present invention
In, the stator 32 is fixed to the shaft 24 via the core holder 48. For this reason, the inner diameter of the stator 32 can be made sufficiently larger than the outer diameter of the shaft 24, and the bearing holding surface of the shaft 24 is not damaged when the stator 32 is inserted into the shaft 24.
Displacement of the front bearing 26 can be prevented, and problems such as noise and heat generation can be completely solved. Also,
Since the core holder 48 can be loosely arranged on the shaft 24 when the core holder 48 is inserted, the core holder 48 does not damage the surface of the shaft 24.

The core holder 48 is fixed to the shaft 24 and the stator 32 is fixed to the core holder 48 by adhesive. However, the stator 32 is firmly fixed to the shaft 24 via the core holder 48 by tight fitting, so that the adhesive is hardened. The process can be immediately shifted to the next process without waiting, and the assembling time can be greatly reduced.

When the adhesive between the shaft 24, the core holder 48, and the stator 32 is hardened, they are firmly fixed to each other more than the interference fit, the fixing strength is increased, and noise prevention can be more reliably achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a spindle motor according to the present invention.

FIG. 2 is a perspective view showing an example of a core holder used for the spindle motor according to the present invention.

FIG. 3 is a sectional view showing another example of the core holder used in the spindle motor according to the present invention.

FIG. 4 is a sectional view showing an example of a known spindle motor.

FIG. 5 is a sectional view showing an example of another known spindle motor.

[Explanation of symbols]

 Reference Signs List 20 spindle motor 22 soldering 24 shaft 26 front bearing 28 rear bearing 30 rotor hub 32 stator 36 rotor magnet 48 core holder 48a upper portion 48b lower portion 48c step portion 48d hollow hole 48e groove

Claims (7)

[Claims] 1. A housing 22, and a shaft 24 having a lower end fixedly held near a center of the housing 22.
A rotor hub 30 rotatably mounted on the shaft 24 via a front bearing 26 and a rear bearing 28; and a rotor hub 30 between the rotor hub 30 and the shaft 24 and between the pair of bearings 26, 28. A rotor 32 is provided between the stator 32 fixed to the shaft 24 and the stator 32 attached to the inner peripheral surface side of the rotor hub 30 and has a slight space radially outward of the stator 32. In the spindle motor constituted by the magnet 36, core holders 48 and 48A are used for fixing the stator 32 to the shaft 24.
8A is initially mounted on the shaft 24 via a hollow hole 48d having a diameter d4 larger than the diameter d1 of the shaft 24, but the stator 32 is
When the core holder 48 and 48A are fitted into the shaft 24, the stator 32 is fixed to the shaft 24 via the core holders 48 and 48A by being tightly fitted to the shaft 24 in a tightly fitted state. Spindle motor. 2. The spindle motor according to claim 1, wherein the shaft has a constant outside diameter over the entire length. 3. The core holder 48 comprises an upper portion 48a and a lower portion 48b, both of which are stepped portions 48c.
And has a hollow hole 48d having an inner diameter d4 penetrating vertically to receive the shaft 24, the outer diameter d2 of the upper portion 48a is smaller than the outer diameter d3 of the lower portion 48b, and 3. The spindle motor according to claim 1, wherein before assembly, an inner diameter d6 of the stator 32 mounted on the core holder 48 is smaller than an outer diameter d2 of the upper portion 48a. 4. The inner diameter d6 of the stator 32 is
4 is larger than the outer diameter d1 (d6> d1), but slightly larger than the outer diameter d2 of the upper part 48a of the core holder, for example, by several tens.
The spindle motor according to claim 1, wherein (d2> d6) is set to be smaller by about μm. 5. An upper end corner 48f of the upper portion 48a is chamfered sufficiently smoothly, and an upper end 48a of the upper portion 48a is formed.
5. The spindle motor according to claim 1, wherein the diameter of the g is substantially equal to or slightly smaller than the inner diameter d6 of the stator 32. 6. An upper portion 48a of the core holder 48 includes:
The spindle motor according to claim 1, wherein one or a plurality of grooves 48 e extending in a vertical direction are formed. 7. The core holder 48A includes an upper part 48a.
And a lower portion 48b, both of which are connected by a step portion 48c.
Hollow hole 48 of inner diameter d4 penetrating up and down to receive
d, and the outer diameter of the upper portion 48a is
b is smaller than the outer diameter d3, and the upper portion 48a is
The outer diameter of the upper portion 48a is gradually reduced so that the wall thickness becomes thinner as approaching the upper end portion 48g from c.
The outer peripheral edge diameter of the step portion 48c is the same as the outer diameter d3 of the lower portion 48b, and the inner peripheral edge size of the step portion 48c is larger than the inner diameter d6 of the stator 32, but the outer diameter d5 of the upper end portion 48g is The spindle motor according to claim 1, wherein the inner diameter is smaller than an inner diameter d <b> 6 of the stator 32.