JPH0622494A - Spindle motor - Google Patents

Abstract

PURPOSE:To provide a spindle motor which can surely prevent the outflow of grease, etc., to the outside of a motor. CONSTITUTION:In first and second gaps 24 and 27, which are made by a holddown member 12 and a rotating member 12 and connect the inside of a motor with the outside, the dimension T2 of the second gap 27 is set to be larger than the dimension T1 of the first gap 24. The second gap 27 is lined with a chemical adsorbent 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor.

[0002]

2. Description of the Related Art When a motor rotates at a high speed, mist-like grease or the like is generated due to a pressure difference generated inside or outside the motor.
Attempt to flow from the inside of the motor to the outside. Therefore, the recording medium mounted outside the motor is affected,
Causes read / write errors. In order to prevent this, conventionally, a labyrinth having various structures as a seal member is provided in a gap formed by a fixing member such as a bracket and a rotating member such as a hub (which communicates the inside and the outside of the motor). It was

[0003]

However, in the labyrinth in the conventional spindle motor, it is difficult to reliably prevent the grease and the like from flowing out to the outside of the motor.

Therefore, an object of the present invention is to provide a spindle motor that solves the above-mentioned conventional problems.

[0005]

In order to achieve the above object, a spindle motor of the present invention comprises a fixed member and a rotating member, which communicates the inside and the outside of the motor and is adjacent to each other. In the portion and the second gap portion, the gap dimension of the second gap portion is set to be larger than the gap dimension of the first gap portion, and a chemical adsorbent is incorporated in the second gap portion.

[0006]

When the motor rotates at a high speed, the air containing the atomized grease and the like flows out from the inside of the motor to the outside, and flows into the first gap portion and the second gap portion. Since the size is larger than the size of the first gap part, the air that has passed through the first gap part is rapidly reduced in flow velocity and stays in the second gap part, and fine particles such as grease are chemically adsorbed. Adsorbed by the agent.

As described above, since the air containing grease or the like is retained and the grease or the like is adsorbed to the chemical adsorbent, the adsorption rejection rate is extremely high, and it is possible to reliably prevent the grease or the like from flowing out of the motor. .

[0008]

The present invention will be described in detail below with reference to the drawings showing the embodiments.

FIG. 1 shows an embodiment of a spindle motor according to the present invention, in which 1 is a fixing member generally called a bracket, and a shaft 3 is provided in a hole 2 of the fixing member 1.
Is fixed.

A stator 4 composed of a stator core and a stator coil is fixed to the outer peripheral surface of the shaft 3 (at the center of the drawing).

Reference numeral 5 denotes a stator coil lead wire 6 of the stator 4.
Is an insertion hole formed in the shaft 3 to guide the outside of the motor.

Reference numeral 7 denotes a hub, which is a thin-walled intermediate peripheral wall portion 8 of the hub 7.
An annular rotor magnet 10 is fixed to the inner peripheral surface of the rotor via an annular yoke 9, and the outer peripheral surface of the stator 4 and the inner peripheral surface of the rotor magnet 10 face each other with a minute predetermined distance.

A ring-shaped rotating member 12 is fixed to the inner peripheral edge of the collar portion 11 of the hub 7, and the rotating member 12 and the hub 7 form a bearing.
The stator 4 is excited by a control current that is rotatably pivotally attached to the shaft 3 via 13 and 14 and is sent via the stator coil lead wire 6, and the hub 7 rotates in a predetermined direction.

Ring-shaped shield plates 15a and 15b are attached to the outer ring inner peripheral surfaces 13a and 14a of the bearings 13 and 14 by fitting or the like.

A magnetic fluid seal device 16 is provided at the inner peripheral edge of one end (upper side in the figure) of the hub 7 in order to prevent grease and the like in the bearing 13 from flowing out of the motor.

On the other hand, as shown in FIG. 2, the outer ring end surface 14b of the bearing 14 and the one end surface 17 of the rotating member 12 (inner peripheral side thereof) are thin annular flat plate-like cover members 18 made of plastic or the like.
Are affixed (or adhered), and the inner peripheral edge of the cover member 18 is projected radially inward (leftward in FIG. 2) with respect to the outer ring inner peripheral surface 14a of the bearing 14.

By the way, the bearing 14 is provided with a shield plate 15b so that grease and the like inside does not easily flow out of the bearing. However, when the hub 7 side (the hub 7, the rotating member 12 and the outer ring of the bearing 14 and the like) rotates, the grease and the like in the bearing 14 are urged toward the outer ring inner peripheral surface 14a side by centrifugal force. Therefore, the shield plate mounting part on the inner surface 14a of the outer ring
Grease or the like may bleed toward the outer ring end face 14b side and leak out through a minute gap between the shield plate 15b and the shield plate 15b.

The leaked grease or the like is removed from the cover member.
By sealing with 18, it is possible to prevent outflow to the outside of the motor.

That is, of the cover member 18 adhered to the outer ring end surface 14b of the bearing 14, the portion whose inner peripheral edge projects radially inward from the outer ring inner peripheral surface 14a of the bearing 14 and the shield which faces this portion. A void 40 is created by the plate 15b.

Then, the grease or the like that has leaked into the space 40 is retained and retained. Moreover, the centrifugal force associated with the rotation of the hub 7 acts so that the grease or the like accumulated in the void 40 is pushed (to the right in FIG. 2).

Therefore, the inner peripheral edge of the cover member 18 is fixed to the bearing 14
The sealing performance can be improved by bringing the inner ring side of the vehicle as close as possible.

By attaching (or adhering) the cover member 18 to the one end surface 17 of the rotating member 12, the attaching (or adhering) strength of the cover member 18 is enhanced, and the bearing 14 and the rotating member 12 are attached. The mating part with and is covered to improve the sealing performance.

Therefore, the concave circumferential groove 20 is formed on the one end surface 17 side of the rotating member 12 with the axial center of the shaft 3 as the center, and the concave circumferential groove 20 has a rectangular sectional shape in the illustrated example. It

Corresponding to the concave circumferential groove 20, an annular convex portion 21 projecting inward in the axial direction is formed on the surface 33 of the fixing member 1 with the axial center of the shaft 3 as the center. Further, the sectional shape of the annular convex portion 21 is formed to be substantially the same as the sectional shape of the concave circumferential groove 20.

The concave circumferential groove 20 and the annular convex portion 21 are opposed to each other at a predetermined interval, and the inner peripheral surface 22 of the annular convex portion 21 and the outer peripheral surface 23 of the concave circumferential groove 20 have a clearance dimension T ₁ . The first gap portion 24 is formed, and further, the end surface 25 of the annular convex portion 21 and the groove bottom corresponding surface 26 of the concave circumferential groove 20.
At, a second gap portion 27 having a gap dimension T ₂ is formed.

The gap size T ₁ and the gap size T ₂ are T ₁
<T ₂ (for example, about T ₂ = 0.17 mm with respect to T ₁ = 0.1 mm) is set.

Further, the outer peripheral surface 28 of the annular convex portion 21 and the concave peripheral groove 20
At an inner circumferential surface 29 of the gap the third gap section 30 of the dimension T ₃ is formed, the gap dimension T ₃ is, T ₃ <T ₂ (e.g., T ₃ = 0.1
mm).

In this way, the fixed member 1 and the rotating member 12
At, a first gap portion 24, a second gap portion 27, and a third gap portion 30 that communicate the inside and the outside of the motor are formed.

Reference numeral 31 is a sheet-shaped chemical adsorbent that adsorbs various gases (for example, fine particles such as grease), and the second gap 27
And is provided on the groove bottom corresponding surface 26 of the concave circumferential groove 20 in the illustrated example.

The chemical adsorbent 31 is a granular one in which various oxidizing agents, reducing agents and the like are attached to a base having a porous structure (for example, commercially available products such as Pyracor manufactured by Nitta Co., Ltd.).
Is formed into a sheet shape, and various gases are fixed inside the chemical adsorbent 31 by the above-mentioned attached oxidizing agent and the like.

However, when the hub 7 side rotates at a high speed, the fixing member 1 is caused by the wind pressure of the disk or the like mounted on the hub 7.
In the gap between the hub and the hub 7, a suction force in the direction of arrow A from the inside of the motor to the outside is generated, and air containing grease and the like atomized by the high speed rotation of the bearing 14 flows out from the inside of the bearing 14, It flows into the first gap portion 24 and the second gap portion 27.

At this time, the first gap portion 24 and the second gap portion 27
Since the size of the gap is T ₁ <T ₂ , the air containing grease and the like that has passed through the first gap portion 24 is
At 27, the flow velocity sharply decreases and stays, and fine particles such as grease are adsorbed by the chemical adsorbent 31.

As described above, since the air containing the grease or the like is retained and the grease or the like is adsorbed to the chemical adsorbent 31, the adsorption / removal rate is extremely high, and the grease or the like is reliably prevented from flowing out of the motor. it can.

FIG. 3 shows another embodiment, in which a first gap portion 24 and a second gap portion 24 formed by a ring-shaped fixing member 1 having a U-shaped cross section and a ring-shaped rotating member 12 having a T-shaped cross section. Chemical adsorbent to be installed in the gap 27 and the second gap 27
The case where 31 is provided on the bearing 32 side (upper side in FIG. 3) is shown.

In this embodiment, the rotating member 12 is fixed to the inner peripheral surface of the yoke 9, the fixing member 1 is fixed to the outer peripheral surface of the shaft 3, and the concave peripheral groove 20 is further formed in the fixing member 1.
The rotating member 12 is formed around the axis of the shaft 3.
The ring-shaped convex portion 21 protruding outward in the axial direction is attached to the shaft 3
Is formed around the axis of

The annular convex portion 21 and the concave circumferential groove 20 form a first gap portion 24 and a second gap portion 27 having a gap dimension T ₁ <T ₂ , and a gap dimension T ₃ <T _2. The third gap portion 30 is formed.

Also in this case, similarly to the above-mentioned embodiment, the bearing
Air containing grease or the like that is about to flow out from the inside of the motor 32 to the outside of the motor is retained in the second gap portion 27, and fine particles of grease or the like contained in the air can be adsorbed by the chemical adsorbent 31.

Although the chemical adsorbent 31 is provided on the rotary member 12 side in the above-mentioned embodiment, it is provided on the fixed member 1 side, conversely, in the present embodiment.

By the way, as shown in FIG.
The back surface 34 of the bracket is a predetermined depth dimension B--
A reference surface 35 perpendicular to the hole 2 is formed by cutting or the like with a predetermined diameter dimension C, for example, about 0.2 mm. 36 is a relief groove, which is used as a relief for the cutting edge during cutting, and prevents the reference surface 35 from being spoiled.

The reference surface 35 is used, for example, when the shaft 3 is fixed to the hole 2 of the bracket by press fitting or shrink fitting.
It is used to obtain the perpendicularity with respect to the reference plane 35, and is also used when incorporating the rotor.

Here, if the reference surface 35 has a convex shape as shown in FIG. 4, for example, it is likely to hit other objects during transportation or handling, and the reference surface 35 is very likely to be damaged. When the entire back surface 34 is used as the reference surface 35 as shown in FIG. 5, not only the processing time becomes long (that is, the cost becomes high), but also the flatness and the squareness are difficult to be obtained, and Similar to FIG. 4, the reference surface 35 is likely to be damaged.

However, in the embodiment of FIG. 1, since the reference surface 35 of only the necessary range is recessed in the back surface 34, the problem in the comparative example shown in FIGS. 4 and 5 does not occur.

The present invention is not limited to the above-mentioned embodiments, but can be applied to various spindle motors, for example, motors of the type in which the shaft side rotates.

In addition to this, with respect to the gap generated by the opposed arrangement of the concave circumferential groove 20 and the annular convex portion 21, for example, the gap size T
The relationship between ₂ and T ₃ can be T ₂ <T ₃ . In this case, the flow velocity of the passing air decreases
The chemical adsorbent 31 can be attached to the gap 30, that is, to the outer peripheral surface 28 of the annular convex portion 21 (shown in FIG. 2) or the inner peripheral surface 29 of the concave circumferential groove 20.

Furthermore, the gap between the surface 33 of the fixing member 1 and the cover member 18 may be smaller than T ₁ of the first gap portion 24, and the chemical adsorbent 31 may be provided in the first gap portion 24. In this case, the inner peripheral surface 22 of the annular convex portion 21 or the outer peripheral surface of the concave circumferential groove 20.
A chemical adsorbent 31 can be attached to 23.

[0046]

Since the present invention is constructed as described above, it has the following great effects.

When the motor rotates at a high speed, air containing grease or the like, which tends to flow out from the inside of the motor to the outside, is retained in the second gap portion 27, and fine particles such as grease are adsorbed by the chemical adsorbent 31. You can

Therefore, the rate of adsorption and removal of grease and the like by the chemical adsorbent 31 becomes extremely high, and it is possible to reliably prevent the grease and the like from flowing out of the motor.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part.

FIG. 3 is an enlarged sectional view of an essential part showing another embodiment.

FIG. 4 is a cross-sectional view of an essential part showing a comparative example.

FIG. 5 is a cross-sectional view of a main part showing a comparative example.

[Explanation of symbols]

1 Fixed Member 12 Rotating Member 24 First Gap 27 Second Gap 31 Chemical Adsorbent T ₁ Gap T ₂ Gap

Claims (1)

[Claims] 1. A fixed member 1 and a rotating member 12 are formed,
In the first gap portion 24 and the second gap portion 27 which communicate with the inside and outside of the motor and are adjacent to each other, the gap dimension T ₂ of the second gap portion 27 is set to the gap dimension T of the first gap portion 24. A spindle motor characterized by being set to a value larger than _{1 and} having a chemical adsorbent 31 incorporated in the second gap 27.