JPH0787720A - Brushless motor - Google Patents

Abstract

PURPOSE:To improve the positioning accuracy of an air-core coil and to reduce the reluctance between an armature and a rotor magnet by plastically deforming a ferromagnetic material to form a board of a stationary member, and mounting the coil of the armature at a previously formed protrusion. CONSTITUTION:A base plate 1 of a stationary member is plastically deformed to be formed in a predetermined shape by pressing an iron steel plate as a ferromagnetic material. That is, a cylindrical part 30 punched through it is provided at its center, and protrusions 3 radially disposed at the part 30 as a center are stood. A bearing sleeve 8 for rotatably supporting a shaft 7 is mounted at the part 30, and an air-core coil 5 is engaged with the protrusions 3 to be mounted. Thus, positioning accuracy of the coil 5 can be easily improved, and the protrusions 3 of the material are provided at the center of the coil 5, and hence a reluctance between the armature 4 and a rotor magnet 6 is reduced to improve an efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial air gap type brushless motor.

[0002]

2. Description of the Related Art An armature coil provided on a stationary member,
There is a so-called axial air gap type brushless motor in which a rotor magnet mounted on a rotor is arranged so as to face each other in a rotation axis direction. In this type of brushless motor, an air-core coil is used for the armature, and it is difficult to make the gap between the rotor magnet and the armature coil small, so the magnetic flux density is not so high,
Further, the magnetic resistance of these magnetic paths was relatively large, and the utilization efficiency of the rotor magnet was low.

In view of these points, for example, Japanese Patent Publication Sho 60
─23585 gazette and Japanese Patent Publication No. 61-12462, etc., an air core coil is arranged in a stator (stator) yoke.
A configuration is disclosed in which a mounting screw made of a magnetic material is provided in the void of the air-core coil. As a result, the magnetic resistance is homogenized, and thus the magnetic flux density is increased to improve the utilization efficiency of the magnet.

[0004]

However, in the brushless motor having the above-mentioned structure, a mounting screw and a screw hole for screwing the screw and labor are required. Further, it is difficult to position the air-core coil stator for mounting it on the yoke, and it is not possible to mount the core-coil stator accurately, which may reduce the magnetic efficiency.

The present invention has been made in view of the above problems existing in the prior art. The problem is that the assembly can be performed easily and accurately, and the armature and the rotor magnet can be assembled. An object of the present invention is to provide a highly efficient brushless device in which the magnetic resistance between them is reduced and the magnetic flux density is increased.

[0006]

In order to achieve the above object, the brushless motor of the present invention includes a stationary member, an armature provided on the stationary member, a rotating member, and the rotating member. A brushless motor including a rotor magnet, wherein the armature and the rotor magnet are arranged to face each other with a slight gap in a rotation axis direction; the stationary member is formed by plastically deforming a substrate made of a ferromagnetic material. The armature is composed of a plurality of air-core coils, and the air-core coils are provided by being fitted in the protrusions formed on the stationary member.

[0007]

According to the brushless motor of the present invention, the protruding portion of the stationary member into which the air-core coil of the armature is fitted and mounted can be preformed with high precision by plastic deformation processing. Therefore, only by mounting the air-core coil on the protrusion, the air-core coil can be accurately positioned in a predetermined manner. Moreover, in the central part corresponding to the void of the air-core coil,
Since the protrusions made of the ferromagnetic material are present, the magnetic resistance between the armature and the rotor magnet is reduced, the magnetic flux density is increased, and the efficiency is improved.

[0008]

Embodiments of the brushless motor according to the present invention will be described with reference to the accompanying drawings. 1 to 3
Is an embodiment of a brushless motor that rotationally drives a rotary polygonal mirror, for example, and FIG. 1 is a sectional view showing the whole thereof. 2 is a plan view of FIG. 1 looking down from the top of the drawing. Further, FIG. 3 is a plan view showing a state where the rotating member of the brushless motor in FIG. 2 is removed. Note that, in these drawings, the same members and portions are given the same numbers.

In these figures, the member 1 is a base plate as a stationary member, and is provided with a thin steel plate formed in a substantially direction. The base plate 1 is formed into the following required shape by plastic deformation processing such as press working. That is, the four corners of the base plate 1 are provided with holes 22 for attachment to a drive device (not shown), and these parts are slightly bent. Further, a cylindrical portion 3 punched through is provided in a central portion of the base plate 1 which is rotationally supported.
0 is provided. Then, the projecting portions 3 radially arranged around the cylindrical portion 30 are provided upright.

A bearing sleeve 8 for rotatably supporting the shaft 7 is mounted on the cylindrical portion 30. Cylindrical part 30
The inner peripheral portion 14 and the outer peripheral portion 24 of the bearing sleeve 8 are fitted and fixed. The bearing sleeve 8 is made of a material such as lead bronze and is formed in a cup shape, and the lower end portion thereof is closed. The shaft 7 rotatably supported by the bearing sleeve 8 is provided with a herringbone-shaped dynamic pressure forming groove (not shown) at a portion of the outer peripheral portion 27 corresponding to the bearing sleeve. As a result, the shaft 7 is rotatably supported by the bearing sleeve 8. Corresponding to the bottom surface portion 25 of the bearing sleeve 8, the lower end 29 of the shaft 7 is also provided with a spiral dynamic pressure generating groove (not shown), which allows the shaft 7 to move in the rotational axis direction. I support you.

A hub 15 for supporting the rotary polygon mirror 9 and the rotor 2 is fitted and fixed on the upper side of the shaft 7. The hub 15 has a substantially cylindrical shape, and is integrally formed with a flange portion 16 protruding in the outer peripheral direction. The rotary polygon mirror 9 is mounted on the upper surface of the collar portion 16, and the rotor 2 is fixed on the lower surface. The rotary polygon mirror 9 is positioned in the radial direction by the outer peripheral portion 21 of the hub 15, and is positioned by being mounted in the height direction by the upper surface of the flange portion 16. The rotary polygon mirror 9 is fixed to the hub 15 (shaft 7) by the clamp 10 fixed to the upper end of the shaft 7. The clamp 1 is fixed by attaching the retaining ring 12 to the outer peripheral portion 21 of the hub 15. This allows the clamp 1
The bent portion 28 of 0 acts so as to press the upper surface of the rotary polygon mirror 9, so that the rotary polygon mirror 9 is fixed by being clamped by the clamp 1 and the flange portion 28 of the hub 15.

On the lower surface of the collar portion 16 of the hub 15, the rotor 2
The rotor yoke 20 of is fixed. The rotor yoke 20 has an inverted dish shape having a shaft center portion formed therein, and a base portion 19 thereof is formed so as to correspond to the shape of the flange 16 of the hub 15. Base 1
The fixing of 9 and the collar portion 16 can be achieved by spot welding or the like in addition to adhesion and caulking. The rotor yoke 20 is formed of, for example, a thin steel plate by plastic deformation processing such as pressing. The rotor yoke 20 has a stepped shape whose diameter is gradually increased to improve the rotational rigidity. Inside the rotor yoke 20, a thin ring-shaped rotor magnet 6 is attached and provided.

The rotor magnet 6 has a required number of N poles and S poles.
The poles are magnetized alternately in the circumferential direction. The armature 4 is arranged on the base plate 1 so as to face the rotor magnet 6 with a slight gap in the axial direction. The armature 4 is
It is composed of six air core coils 5 (that is, six magnetic poles).
The air-core coil 5 has a substantially ring shape and is attached to the base plate 1. Specifically, the air-core coil 5 is mounted on the upper surface of the printed circuit board 11 laid on the upper surface of the base plate 1 and corresponding to the protruding portions 3. The outer diameter of the protruding portion 3 is set to be slightly smaller according to the inner diameter of the air-core coil 5. The protruding portion 3 is positioned on the base plate 1 so as to face the rotor magnet 6, and is formed in advance by plastic deformation processing with high accuracy.

Therefore, the air-core coil 5 can be accurately positioned and fixed at a predetermined position only by fitting the air-core coil 5 into the protruding portion 3 and mounting it. As is apparent from FIG. 1, the protruding portion 3 is set at substantially the same height as the height position of the air core coil 5. The upper end 32 of the protrusion 3 is provided substantially parallel to the lower end 33 of the rotor magnet 6. That is, the rotor magnet 6, the air-core coil 5 and the protruding portion 3 are arranged to face each other with a slight gap formed at substantially equal intervals. As a result, the magnetic resistance from the rotor magnet 6 can be reduced in combination with the presence of the protrusion 3 made of a ferromagnetic material and the portion corresponding to the air core coil 5 of the base plate 1 integrally formed of the same member. Therefore, the magnetic flux density can be maintained high.

The outer peripheral portion 23 of the projecting portion 3 with which the inner side 13 of the air-core coil 5 abuts is coated with an insulating coating in order to maintain insulation with the air-core coil 5. A coil lead wire (not shown) led out from the air-core coil 5 is electrically connected to a predetermined land portion provided on the printed circuit board 11 by soldering or the like. The part 31 shown in FIG. 3 is a slit having a long hole provided through the base plate 1. The slits 31 are evenly arranged radially between the air core coils 5. This prevents the generation of the eddy current induced in the base plate 1 from the air-core coil 5.

Although one embodiment of the brushless motor of the present invention has been described above, design changes and modifications can be freely made without departing from the spirit of the present invention. That is, in the brushless motor of this embodiment, the printed circuit board 11 is adhered to the base plate 1 made of a ferromagnetic material, but the insulating layer and the conductive layer are directly provided on the base plate made of a ferromagnetic material. It is also desirable to use a metal substrate. In addition, the base plate 1 can be arbitrarily selected as long as the base plate 1 is insulated and the air core coil is mounted thereon. The armature 4 can be freely selected according to the required characteristics of the motor, such as the shape of the air-core coil 5 and the number of air-core coils.

[0017]

Since the brushless motor of the present invention has the above-mentioned structure, it has the following effects. That is, according to the brushless motor of the present invention, the protruding portion of the stationary member into which the air-core coil of the armature is fitted and mounted can be preformed with high precision by plastic deformation processing. Therefore, only by mounting the air-core coil on the protrusion, the air-core coil can be accurately positioned in a predetermined manner. Moreover, since there is a protruding portion made of a ferromagnetic material in the central portion corresponding to the void portion of the air-core coil, the magnetic resistance between the armature and the rotor magnet is reduced, and the magnetic flux density is increased to improve the efficiency. Can be achieved. Therefore, it is possible to obtain a highly efficient brush restor which can be easily assembled with high accuracy and which has a reduced magnetic resistance between the armature and the rotor magnet to increase the magnetic flux density.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an entire brushless motor according to an embodiment of the present invention.

FIG. 2 is a plan view of the brushless motor according to FIG.

FIG. 3 is a plan view of the brushless motor according to FIG. 1 with a part thereof removed.

[Explanation of symbols]

 1 Base Plate 2 Rotor 3 Projection 4 Armature 5 Air Core Coil 6 Rotor Magnet 7 Shaft 8 Bearing Sleeve 9 Rotating Polygonal Mirror 11 Printed Circuit Board

Claims (1)

[Claims] 1. A stationary member, an armature provided on the stationary member, a rotating member, and a rotor magnet provided on the rotating member, wherein the armature and the rotor magnet have a rotation axis. In a brushless motor arranged to face each other with a slight gap in a direction, the stationary member is formed by plastically deforming a substrate made of a ferromagnetic material, and the armature is composed of a plurality of air-core coils, the air-core coil The brushless motor is provided by being fitted into a protrusion formed on the stationary member.