JPH0360355A - Motor - Google Patents

Abstract

PURPOSE:To prevent a rotary body having a rotor from moving in the axial direction by fitting a magnetic body to one of the frame or the rotary body and fitting a magnet, facing with the magnetic body in the axial direction, to the other. CONSTITUTION:A magnet 25 is fitted to the inner face of a rotary body 16 through a yoke 26 so as to face with a magnetic body 15 in the axial direction. Besides, magnetic fluid 27 is filled between the yoke 26 and the magnetic body 15. And, a magnetic path PHI shown on the figure is formed through the magnet 25, the yoke 26, the magnetic fluid 27, and the magnetic body 15. Here, when a rotor 20 rotates together with the rotary body 16, a dynamic pressure fluid flow is formed through rotation of a shaft 17, and the shaft 17 is supported by the bearing action of this dynamic pressure fluid. On this occasion, the magnet 25 produces magnetic attraction force to the magnetic body 15 in the axial direction. Accordingly, the movement of the rotary body 16 with respect to a frame 11 in the axial directions is regulated. Consequently, the motor operates well even when it is installed laterally.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a system in which a rotating body including a rotor is supported by a hydrodynamic bearing against a frame including a stator. Regarding motors.

(Prior Art) A motor whose rotor is supported by a hydrodynamic bearing is used, for example, as a hard disk drive motor. As this kind of motor, Japanese Patent Application Laid-Open No. 61-1125
What is shown in Publication No. 44 (see Figure 3), JP-A-61
- What is shown in Publication No. 112547 (see Figure 4),
Or Utility Model Application No. 62-48147 (see Figure 5)
There are only those shown in . Each of these motors has a fixed cylinder formed with, for example, a herringbone-shaped groove 4 on the rotating shafts 1, 3 or the fixed shaft 2, and fitted with the rotating shafts 1, 3 or the fixed shaft 2 through a small gap. A dynamic pressure fluid flow, such as an oil flow, is formed between the rotary cylinder 6 and the rotary cylinder 6.

(Problem to be Solved by the Invention) In any of the above conventional examples, when the hard disk is driven in a horizontal state, that is, when the motor is arranged vertically, the rotating body shifts in the axial direction. However, if the motor is used with a horizontal shaft arrangement, if vibration occurs in the axial direction, the rotating body including the rotor may shift in the axial direction.
There is a risk that the disk will move in the axial direction, making it impossible to read or write correctly. In particular, JP-A-61-1 shown in FIG.
In the one shown in Japanese Patent Application Laid-Open No. 12544-12544 and the one shown in Japanese Patent Application Laid-Open No. 112547-1983 shown in FIG. There was a risk that the magnetic head would be damaged by the moving disk and the disk moving with it.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a motor that can prevent a rotating body including a rotor from moving in the axial direction.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a system in which a rotating body including a rotor is supported by a hydrodynamic bearing on a frame including a stator. It is characterized in that one of the frame and the rotating body is provided with a magnetic body, and the other is provided with a magnet that faces the magnetic body in the axial direction.

In this case, the yoke may be magnetically coupled to the magnet, and a magnetic fluid may be filled between the yoke and the magnetic body.

(Operation) A magnet exerts a magnetic attraction force on a magnetic body in the axial direction. Therefore, the movement of the frame and the rotating body in the axial direction is restricted.

In this case, if the magnetic fluid is filled between the yoke and the magnetic material that are magnetically coupled to the magnet, the seal between the frame and the rotating body can be created by using the magnet and the magnetic material for movement regulation. You can use it to achieve your goals.

(Embodiment) An embodiment in which the present invention is applied to a spindle motor in a hard disk drive will be described below with reference to FIGS. 1 and 2.

Reference numeral 11 denotes a frame made of a non-magnetic material, on which a cylindrical sleeve 12 is protruded, and a bearing sleeve 13 is fitted into the inner circumference of this sleeve 12. 14 is sleeve 1
Iron core 14a and stator coil 14 fitted on the outer periphery of 2
This stator is made up of a stator ba, which is clamped and fixed by a step 12a formed on the sleeve 12 and an annular fixing member 15 made of a magnetic material. 16 is a spindle hub which is a rotating body, and in its center there is a herringbone groove 17a;
A shaft 17 having an outer peripheral portion 17a is attached.

This shaft 17 is rotatably fitted into the bearing sleeve 13, and the tip of the shaft 17 is adapted to be received by one thrust receiver attached to the frame 11 with a screw 18. A spiral groove 19a is formed in this thrust receiver 19. Lubricating oil is filled between the shaft 17, the bearing sleeve 13, and the thrust receiver 19. 20 is the rotor, which is the spindle hub 1
A cylindrical yoke 21 is disposed on the inner circumference of the yoke 6, and a cylindrical rotor magnet 2 is attached to the inner circumference of the yoke 21.
It consists of 2. Note that 23 is the base 12b of the sleeve 12.
24 is a position detection element.

Now, 25 is an annular magnet with one surface magnetized as a single pole, and 26 is an annular yoke. The magnet 25 is attached to the inner surface of the spindle hub 16 via the yoke 26 so as to face the fixture 15, which is a magnetic material, in the axial direction. The yoke 26 is magnetically coupled to the magnet 25, and its tip wraps around the outer periphery of the fixture 15 in the circumferential direction. A magnetic fluid 2
7 is filled. However, magnet 25. York 26. Magnetic fluid27. A magnetic path Φ shown in FIG. 2 is formed between the fixtures 15. As shown in FIG.

As a result, the magnet 25 on the spindle hub 16 side is magnetically attracted to the fixture 15 side on the frame 11 side. In this case, a portion of the bearing is isolated or sealed from other portions by the magnetic fluid 27, thereby preventing leakage of oil mist. Note that a plurality of hard disks (not shown) can be attached to the outer periphery of the spindle hub 16.

In the above configuration, when the rotor 20 is rotated together with the rotating body 16, a dynamic pressure fluid flow is formed as the shaft 17 rotates, and the shaft 17 is supported by this dynamic pressure fluid bearing action. In this case, the magnet 25 applies a magnetic attraction force to the fixture 15 in the axial direction. Therefore frame 11
The movement of the spindle hub 16 in the axial direction, particularly in the direction of ejection and removal, is restricted, and even when this motor is used in a horizontal shaft type or is handled slightly upside down, there is no problem during use.

Further, according to the above embodiment, since the magnetic fluid 27 is filled between the yoke 26 and the fixture 15, the seal between the frame 11 and the spindle hub 1 is secured by the magnet 25 for regulating movement and the fixture 15. The bearing can achieve this while reducing the number of parts by preventing oil mist from leaking from the bearing.

Further, since the existing fixture 15 is used as the magnetic body that pairs with the magnet 25, an increase in the number of parts can be prevented, unlike when a dedicated magnetic body is newly provided.

Furthermore, since the magnet 25 is a unipolar magnet, no eddy current is generated in the fixture 15, and an increase in iron loss can be prevented.

In the above embodiments, the present invention was explained as being applied to a spindle motor in a hard disk drive, but the present invention is not limited thereto and can be broadly applied to other motors in general.

[Effects of the Invention] As is clear from the above description, the present invention can obtain the following effects.

According to the motor of claim 1, it is possible to restrict the movement of the rotating body in the axial direction, and as a result, even when this motor is used in a horizontal shaft type or when it is handled slightly upside down, no problems occur during use. Nor.

According to the motor of claim 2, the seal between the frame and the rotating body can be achieved by using a magnet and a magnetic material for regulating movement, and leakage of oil mist from the shaft portion can be prevented. This can be achieved while reducing the number of parts.

[Brief explanation of drawings]

1 and 2 show an embodiment of the present invention, with FIG. 1 being a longitudinal sectional side view and FIG. 2 being an enlarged longitudinal sectional side view of the main parts. Figures 3 to 5 show the first example, each showing a different conventional example.
It is a figure equivalent figure. In the figure, 11 is a frame, 14 is a stator, and 15 is a fixture (
16 is a spindle hub (rotating body), 20 is a rotor, 25 is a magnet, 26 is a yoke, and 27 is a magnetic fluid.

Claims (1)

[Claims] 1. In a frame including a stator, a rotating body including a rotor is supported by a dynamic pressure fluid bearing, in which one of the frame and the rotating body is supported by a dynamic pressure fluid bearing. A motor comprising a magnetic body and a magnet facing the magnetic body in the axial direction. 2. The yoke is magnetically coupled to the magnet,
2. The motor according to claim 1, wherein a magnetic fluid is filled between the yoke and the magnetic material.