JP2565977Y2 - Rotor of flat brushless motor - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a rotor of a flat brushless motor, and more particularly to a rotor of a flat brushless motor having a large inertia.

[0002]

2. Description of the Related Art Conventionally, a flat brushless motor, particularly one having a thin iron core type stator by directly driving an FDD device has been known as shown in FIG.

[0003] More specifically, reference numeral 1 denotes a stator base formed of a printed wiring iron substrate, and a stator holder 4 serving as a metal housing in which a ball bearing 2 and an oil-impregnated metal 3 are fitted is attached at the center, and several silicon sheets are further mounted on the outer periphery thereof. A core 5 on which a steel plate is laminated is fitted, and a stator coil 6 is wound around the core 5 via a core cover 7.

On the other hand, the rotor case 8 has the core 5 inside.
A main magnet 9 made of a rare earth plastic in a ring shape facing the outer periphery of the main body through a gap is held, an FG magnet 10 is integrally formed on a flange 8a on the outer periphery, and a chuck magnet 11 is mounted on the upper surface. It is secured to the shaft 13 via a rotor holder 12, the shaft 13 of the ball bearing 2 and the oil-containing Metall 3
As a whole, it is made thin by rotatably supporting it.

[0005] Recent FDD devices have become very thin, and a flat brushless motor utilizing the FDD device has been required to be as thin as possible. When a total thickness of about 5 mm is required, the inertia of the rotor is reduced. It is not possible to take a large amount, and uneven rotation at low rotation has become a problem.

[0006]

[Problems to be Solved by the Invention] As a countermeasure against the rotation unevenness, in order to increase the inertia, it is conceivable to form an FG magnet larger than necessary or to swing out a flange, but the density of the FG magnet is small. In addition, the head cannot be made too large because the head comes on the upper surface of the flange, and if the flange is swung out too much, the motor diameter becomes large and cannot be adopted.

[0007] This invention has been solved by focusing on the fact that a recess is formed on the upper surface of the flange when the FG magnet is integrally formed. The inertia can be increased without increasing the motor diameter, and therefore, when the rotation speed is low, An object of the present invention is to provide a flat brushless motor rotor with improved rotational unevenness.

[0008]

SUMMARY OF THE INVENTION The present invention provides a printed wiring board.
A stator is made up of a core with a coil wound around a plate.
It is rotatably supported via a receiver and has a cylindrical opening with a bottom.
A case extending radially outward to form a flange,
A predetermined gap is provided in the core disposed on the inner periphery of the cylindrical portion of the case.
And the main magnet
Flat brushless brushless FG magnet
A rotor of Sumota, the FG Ma Gunetto is pre
Face the printed wiring board and close the upper surface of the flange.
Part from the bottom to the top of the flange
FG magnet on the upper surface of this flange
The weight is placed in the recess formed by the
There is .

[0009]

[Function] Is the FG magnet facing the printed wiring board?
First, expose a part of the top surface of the flange to
The flange is integrally molded from the lower surface to the upper surface.
In the recess formed by the FG magnet on the upper surface,
The main magnet and the weight
Is divided by the case, and the weight is
The rotor diameter is not affected by the restrictions on the magnetic properties of the in-magnet.
Easily increase the inertia without increasing the
Can be .

In addition, the weight is connected to the outer periphery of the rotor case and the FG.
It intended to fit in the recess between the magnets, since negligible containing space of the head, depending on the configuration of the FG magnet
The resulting dead space can be used effectively to achieve a very low profile.

[0011]

DETAILED DESCRIPTION FIG. 1 is a piece sectional view of the flat brushless motor using the rotor of this invention, reference numeral 1 denotes a sign
Stator base consisting of printed wiring iron board, ball in the center
Metal housing with bearing 2 and oil-impregnated metal 3 fitted
The stator holder 4 which also serves as
Core 5 laminated with several silicon steel plates
The stator coil 6 is attached to this core.
It is wound via a bar 7 .

On the other hand, the rotor case 8 has a bottomed cylindrical opening.
Part extends radially outward to form a flange.
The inner circumference of the cylindrical portion of the case 8 is provided with a gap on the outer circumference of the core 5
Of ring-shaped rare earth plastic
The in-magnet 9 is held, and its outer peripheral flange 8a
It is integrally molded FG magnet 10, the switch catcher on the upper surface
The magnet 11 is placed on the
And is fixed to the shaft 13.
Ball bearing 2 and oil-impregnated metal 3
By doing so, the overall structure is reduced .

The feature of this invention is that the FG magnet 10 composed of a ferrite plastic magnet integrally formed with the flange 8a of the rotor case 8 is mounted on the printed wiring iron substrate 1.
And expose a part of the upper surface of the flange 8a.
Formed from the lower surface to the upper surface of the flange 8a.
On the outer periphery of the rotor case 8 and the upper surface of the flange 8a.
A ring-shaped weight 14 made of a zinc-plated iron plate is fitted into a recess formed by the FG magnet 10 .

The weight may be a lead plate or copper tungsten, and of course, other members may be used if the density is 6 or more.

[0015]

[Effects of the Invention] As described above, according to the present invention, FG
With the magnet facing the printed circuit board and the flange
From the lower surface of the flange, expose a part of the upper surface
Integrally molded over the upper surface, F
Place the weight in the recess formed by the G magnet
The main magnet and weight depend on the case.
And the weight is the main magnet
And no restrictions on the magnetic flux characteristics. So the way
When attaching the magnet, the relationship with the main magnet
Increase the rotor diameter because it can be completely ignored
The inertia can be easily increased without any increase .

The rotational jitter value was as follows in the experimental results. Without weight 2.67% With iron plate weight 2.13% With lead plate weight 1.15%

In particular, in the present invention, the configuration of the FG magnet
The effective use of dead space created by
As the motor becomes smaller and thinner,
This makes it possible to efficiently utilize the space, and does not interfere with the head , thereby providing an extremely thin flat brushless motor.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one embodiment of a flat brushless motor using a rotor of the present invention.

FIG. 2 is a cross-sectional view of the same conventional art.

[Explanation of symbols]

 8 Rotor case 8a Flange 9 Main magnet 10 FG magnet 14 Weight

Claims (1)

(57) [Scope of request for utility model registration] 1. A coil wound around a printed wiring board
The stator with the core is rotatably supported via a bearing.
And extend radially outward through the bottomed cylindrical opening.
The case with the flange formed and the inner circumference of the cylinder of this case
And a main machine that faces the core through a predetermined gap.
Gnet and FG magnet provided on the flange
The rotor of a flat brushless motor comprising:
The FG magnet faces the printed wiring board.
And a part of the upper surface of the flange is exposed.
From the lower surface to the upper surface of the flange.
A recess formed by the FG magnet on the upper surface of the lunge
A flat brushless motor rotor characterized in that a weight is placed on the rotor.