JP2002027722A - Small brushless dc motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a small axial cap brushless DC motor by downsizing a stator yoke. SOLUTION: This brushless motor is provided with a stator, a bearing 6, and a rotor. The stator includes the stator yoke having a ring formed out of a magnetic sheet, and pole teeth 2, 3 cut to be raised in an axial direction on the inner periphery and the outer periphery thereof, and a ring coil 5 disposed so as to be surrounded by the ring part, the pole teeth 2 on the inner periphery, and the pole teeth 3 on the outer periphery. The rotor includes a rotor frame 8 formed out of the magnetic sheet, a disc-like magnet 9 fixed to the rotor frame 8, and a shaft 7 to the rotor frame 8 and supported by the bearing 6. The end surface of the magnet 9, the pole teeth 2 on the inner periphery and the pole teeth part 3 on the outer periphery face axially through a small gap.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial gap type brushless DC motor used for OA equipment, control equipment, electronic equipment, machine tools, AV equipment, mobile communication equipment and the like, particularly, small portable equipment. is there.

[0002]

2. Description of the Related Art An example of a conventional brushless DC motor is disclosed in Japanese Patent Publication No. 7-46896. This is shown in FIG. The metal plate 1 is bent to form the outer peripheral pole teeth 83, and the two stator yokes 84
This is a radial gap type brushless DC motor in which a ring-shaped coil 85 is sandwiched such that the outer peripheral pole teeth 83 face the inner peripheral side of the cylindrical magnet 89. There is an advantage that the structure is simpler and easier to assemble than a brushless DC motor in which magnetic steel sheets are laminated and a coil is wound.

As an example of a brushless DC motor,
There is one described in U.S. Pat. No. 5,831,359, which is shown in FIG. The outer peripheral pole 83 is a trapezoidal radial gap type brushless DC motor. Outer side pole teeth 8
3 is arranged in a trapezoidal shape so that magnetic imbalance occurs on the circumference where the air gap is formed.

As an example of a brushless DC motor,
There is one described in US Pat. No. 4,987,331, which is shown in FIG. The stator yoke 104 is a brushless DC motor of a radial gap type in which the end faces of the pole teeth on the outer peripheral portion of the stator yoke are opposed to the magnet via a slight gap, by punching.

[0005]

However, the configurations disclosed in Japanese Patent Publication No. 7-46896, U.S. Pat. Nos. 5,831,359 and 4,987,331 have a radial gap type structure, in which a magnet 89 and a rotor frame 88 exist in the radial direction. However, the outer diameter and the thickness of the motor are increased, and it may be difficult to reduce the size of the motor.

In the conventional structure, when a general ferromagnetic metal plate, for example, a galvanized steel plate, is used for the stator yoke 84, it may be difficult to further improve the magnetic characteristics of the motor and the motor efficiency. is there.

When the stator yoke 84 is made up of two or more ferromagnetic parts, the joint between those parts is
There is a possibility that a magnetic loss occurs in the magnetic circuit, the motor torque is reduced, and the motor efficiency is deteriorated.

Further, bending and drawing may be difficult depending on the material type of the ferromagnetic metal plate.

Further, there is a possibility that the number of parts increases.

Further, the position detection sensor and the stator yoke are adjacent to each other, and it is difficult to detect the magnetic flux of the magnet, which may cause abnormal noise.

[0011] Further, it is difficult to hold the bearing together, vibration may occur at the connecting portion, and it may be difficult to assemble the bearing.

[0012]

In order to solve the above problems, the present invention employs the following constitution. That is, the pole teeth are cut and raised on the inner peripheral side and the outer peripheral side of the ring-shaped ferromagnetic metal plate to form a stator yoke. A ring-shaped coil is inserted between the inner and outer pole teeth to form a stator. The inside of the stator yoke is coupled to a bearing, and the bearing rotatably supports the shaft. The shaft is coupled to a disk-shaped magnet via a rotor frame to form a rotor. A small brushless D in which the end faces of the magnet and the pole teeth face each other with a slight gap therebetween.
C motor.

With this configuration, the motor can be downsized by reducing the shape of the stator yoke.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The first aspect of the present invention employs the following configuration. That is, a small brushless DC motor including a stator, a bearing, and a rotor, wherein the stator has a ring-shaped portion made of a magnetic plate and pole teeth portions cut and raised in the axial direction on the inner and outer peripheral sides thereof. A stator yoke, the ring-shaped portion, the inner peripheral side pole tooth portion, and a ring-shaped coil arranged so as to be surrounded by the outer peripheral side pole tooth portion, wherein the rotor is made of a magnetic material and a rotor frame; A fixed disk-shaped magnet, and a shaft fixed to the same and supported by the bearing. The end face of the magnet and the inner and outer pole teeth are separated by a slight gap. This is a small brushless DC motor that faces in the axial direction.

According to this structure, the ring-shaped portion of the stator yoke is arranged only on the lower side of the coil, and has the function of reducing the thickness of the stator yoke in the axial direction without sandwiching the upper and lower sides of the coil with the stator yoke. .

A second aspect of the present invention is the small brushless DC motor according to the first aspect, wherein a stator yoke is formed by bending and drawing one silicon steel sheet.

With this configuration, the stator yoke is made of the steel plate 1.
Since it can be formed only with a single sheet, it has an effect of reducing the magnetic resistance generated at the joint of the components in the magnetic path of the stator yoke.

According to a third aspect of the present invention, there is provided the small brushless DC motor according to the first aspect, wherein the stator yoke is made of a silicon steel plate having a silicon content of 2% or less.

With this configuration, the stator yoke is bent and
When drawing, it has the effect of reducing the occurrence of cracks and cracks in the bent part and performing processing with high dimensional accuracy.

According to a fourth aspect of the present invention, there is provided a small brushless DC motor according to the first aspect, wherein a terminal of a position detection sensor for detecting a rotational position of the magnet is directly connected to a wire processing end of the coil.

This configuration has the effect of reducing the number of components by eliminating the printed circuit board.

According to a fifth aspect of the present invention, the rotor position detecting sensor is located between the outer peripheral pole teeth of the stator yoke in the radial direction, and is located between the sensor portion of the position detecting sensor and the magnet in the axial direction. 2. The small brushless DC motor according to claim 1, wherein no pole teeth are present.

With this configuration, the position detecting sensor has an effect of reducing the influence of the magnetic flux leaking from the pole teeth and accurately detecting the magnetic flux of the magnet.

According to a sixth aspect of the present invention, there is provided the small brushless DC motor according to the first aspect, wherein the mechanism for holding the bearing is disposed on the same circumference as the inner peripheral pole teeth of the stator yoke.

According to this structure, the bearing and the stator yoke can be easily assembled.

[0026]

(Embodiment 1) The configuration of a first embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1 and FIG. 2, square-shaped pole teeth are cut and raised at an angle of approximately 90 degrees on the inner peripheral side and the outer peripheral side of the ring-shaped ferromagnetic metal plate 1, and the stator yoke is formed by squeezing. 4 are formed. The number of the inner peripheral side pole teeth 2 and the number of the outer peripheral side pole teeth 3 are equal to each other, and a ring-shaped coil 5 is inserted at a position sandwiched between the inner peripheral side pole teeth 2 and the outer peripheral side pole teeth 3. It is adjacent to the upper side of the ring-shaped ferromagnetic material metal plate 1. The pole teeth of the stator yoke 4 are magnetized by the energized coil 5. The coil 5 and the stator yoke 4 form a stator. And the inside of the stator yoke 4 is connected to the sleeve bearing 6,
A shaft 7 is rotatably supported by the sleeve bearing 6, and the shaft 7 is coupled to a disk-shaped magnet 9 via a rotor frame 8 to form a rotor 12. This magnet 9 and the end face 10 of the magnetized pole teeth
Are arranged at positions facing each other with a slight gap therebetween.

With this configuration, the stator yoke 4 is disposed on the lower side, inside and outside of the coil 5, and there is no stator yoke 4 on the upper side. A brushless DC motor can be realized.

When the rotor 11 is fixed to the rotor to form an axial fan motor, the rotor frame 8 and the magnet 9 do not exist outside the pole teeth 2 and 3 in the radial direction. Axial fan motors can be realized that are widely spread and arranged.

(Embodiment 2) Hereinafter, the configuration of a second embodiment of the present invention will be described with reference to FIG.

In FIG. 3, the point where the end face 10 of the pole teeth and the magnet 9 face each other with a slight gap therebetween is as follows.
This is similar to FIGS. 1 and 2 shown in the first embodiment.

FIG. 3 shows a second embodiment of the present invention.
The stator yoke 41 is formed by bending and drawing two silicon steel plates. Stator yoke 41
When a plurality of magnetic materials are combined to form the stator yoke 41 in a magnetic circuit including the magnet 9 and the rotor frame 8, an air gap may be formed at the joint to increase the magnetic resistance. At this time, according to the configuration of the second embodiment, since the stator yoke 41 is formed of one component, the stator yoke 41 has an operation of reducing magnetic resistance, and a highly efficient brushless DC motor can be realized. In particular, in the case of a small axial fan motor, it is necessary to increase the number of revolutions to obtain the air volume. However, by reducing the magnetic resistance, the number of revolutions can be increased and a high air volume fan can be realized.

Conventionally, inexpensive galvanized steel sheets have been widely used for the stator yoke 41. However, by using silicon steel sheets having higher permeability than galvanized steel sheets, especially when the motor rotation speed is high, high frequency A brushless DC motor having a high responsiveness and a high efficiency at a high rotational speed can be realized.

Further, it is possible to realize an inexpensive and small-sized brushless DC motor by reducing the number of parts.

(Embodiment 3) The configuration of a third embodiment of the present invention will be described below. The point that the end face 10 of the pole tooth and the magnet 9 are in a position facing each other with a slight gap therebetween is the same as in FIGS. 1 and 2 shown in the first embodiment.
In a third embodiment of the present invention, the stator yoke is
It is composed of a silicon steel sheet having a silicon content of 2% or less.

The silicon steel sheet generally has high hardness but is brittle, and it may be difficult to bend and squeeze with high dimensional accuracy. Also, cracks, cracks, etc. may occur to deteriorate the magnetic resistance. At this time, by lowering the silicon content of the silicon steel sheet, these disadvantages are eliminated, and the formation of the pole teeth has the effect of facilitating bending. Then, the stator yoke 4 is formed with good dimensions, and a small-sized brushless DC motor with high productivity can be realized.

As a further example, aluminum is
% Or more. Even in a silicon steel sheet having a silicon content of 2% or more, a silicon steel sheet containing 3% or more of aluminum can be easily bent and drawn and can reduce the occurrence of cracks and cracks.

(Embodiment 4) Hereinafter, the configuration of a fourth embodiment of the present invention will be described with reference to FIG.

In FIG. 4, the point where the end face 10 of the pole teeth and the magnet 9 face each other with a slight gap therebetween is as follows.
This is similar to FIGS. 1 and 2 shown in the first embodiment.

1 and 2 is that the terminal of the position detecting sensor 13 for detecting the rotational position of the magnet 9 and the wire processing end 18 of the coil are directly connected to each other,
4 is excluded.

With this configuration, it is possible to realize an inexpensive and economical small DC brushless fan which has the effect of reducing the number of parts and eliminates the space of the printed circuit board 14.

(Embodiment 5) Hereinafter, a fifth embodiment of the present invention will be described with reference to FIG.

FIG. 5 is similar to FIGS. 1 and 2 shown in the first embodiment in that the end face of the pole teeth and the magnet face each other with a slight gap therebetween. In the embodiment, the position detection sensor 13 is located between the outer peripheral pole teeth 3 in the radial direction, and is arranged so that no pole tooth exists between the sensor portion 17 of the position detection sensor and the magnet in the axial direction. Things. With this configuration,
The position detection sensor 13 has an operation of reducing the influence of the magnetic flux leaking from the pole teeth and detecting the magnetic flux of the magnet. Can be realized.

Embodiment 6 Hereinafter, a fifth embodiment of the present invention will be described with reference to FIGS. 6 and 7. FIG.

6 and 7, the point that the end face of the pole tooth and the magnet face each other with a slight gap therebetween is as follows.
This is similar to FIGS. 1 and 2 shown in the first embodiment. Figure 1,
The difference from FIG. 2 is that the holding unit 1 for fixing the sleeve bearing 6
5 is formed so as to protrude from the housing 16, and the holding portion 15 is disposed on the same circumference as the inner peripheral pole teeth 2 of the stator yoke 4 and between the inner peripheral pole teeth 2.

With this configuration, when assembling the motor, after the sleeve bearing 6 is inserted into and fixed to the holding portion 15 of the housing 16, the holding portion 15 is fitted between the inner peripheral pole teeth 2 of the stator yoke. Since the stator need only be inserted, the sleeve bearing 6 and the stator yoke can be easily assembled. And the inner peripheral side pole teeth 2 of the stator
Are fixedly engaged with each other by the sleeve bearing 6 and the holding portion 15 to reduce electromagnetic vibration of the stator yoke, thereby realizing a small-sized brushless DC motor with low vibration.

[0047]

As is apparent from the above embodiment, the first aspect of the present invention is as follows.
According to the described invention, the poleless end face and the magnet are arranged face-to-face with a slight gap therebetween, so that a thin and compact brushless DC motor without a stator yoke above the coil can be realized. It is.

According to the second aspect of the present invention, the stator yoke is formed by bending and drawing from one silicon steel plate and is formed of one part, so that the magnetic resistance of the coupling portion in the magnetic circuit is reduced. Thus, a small brushless DC motor with high efficiency can be realized.

According to the third aspect of the present invention, since the stator yoke is made of a silicon steel sheet having a silicon content of 2% or less, the pole teeth can be easily bent and drawn, and the poles of the stator yoke can be formed with high dimensional accuracy. A small brushless DC motor with good productivity can be realized by forming teeth.

According to the fourth aspect of the present invention, the terminal of the position detecting sensor and the wire-processing end of the coil are directly connected to each other to eliminate the printed circuit board. An economical small DC brushless fan can be realized.

According to the fifth aspect of the present invention, since the pole teeth do not exist between the sensor portion of the position detection sensor and the magnet in the axial direction, the position detection sensor accurately transfers the magnetic flux of the magnet. It is possible to realize a small brushless DC motor that can detect the rotor position and accurately detect the position of the rotor to reduce electromagnetic noise and abnormal noise.

According to the sixth aspect of the present invention, the mechanism for holding the bearing is arranged on the same circumference as the inner peripheral side pole teeth of the stator yoke, so that the assembly of the bearing and the stator yoke is facilitated and the pole teeth are further improved. Are fixed by two parts, a bearing and a housing holding part, so that vibration of the stator yoke is reduced, and a small brushless DC motor with low vibration can be realized.

[Brief description of the drawings]

FIG. 1 shows a small brushless DC according to a first embodiment of the present invention.
Motor perspective view

FIG. 2 shows a small brushless DC according to the first embodiment of the present invention.
Cross section of motor

FIG. 3 shows a small brushless DC according to a second embodiment of the present invention.
Motor perspective view

FIG. 4 is a small brushless DC according to a fourth embodiment of the present invention.
Motor perspective view

FIG. 5 is a small brushless DC according to a fifth embodiment of the present invention.
Motor perspective view

FIG. 6 shows a small brushless DC according to a sixth embodiment of the present invention.
Motor perspective view

FIG. 7 shows a small brushless DC according to Embodiment 6 of the present invention.
Motor perspective view

FIG. 8 is a perspective view of a conventional brushless DC motor.

FIG. 9 is a perspective view of a conventional brushless DC motor.

FIG. 10 is a perspective view of a conventional brushless DC motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal plate 2 Inner peripheral pole tooth 3 Outer peripheral pole tooth 4 Stator yoke 5 Coil 6 Sleeve bearing 7 Shaft 8 Rotor frame 9 Magnet 10 Polar tooth end face 11 Blade 12 Rotor 13 Position detection sensor 14 Printed circuit board 15 Holder 16 Housing 17 Sensor part 18 Wire processing end of coil

Claims (6)

[Claims] 1. A small brushless DC motor including a stator, a bearing, and a rotor, wherein the stator is made of a magnetic plate and has a ring-shaped portion and pole teeth portions axially cut and raised on inner and outer peripheral sides thereof. A stator yoke having:
A ring-shaped coil disposed so as to be surrounded by the ring-shaped portion, the inner-peripheral-side pole teeth portion, and the outer-peripheral-side pole teeth portion, wherein the rotor is a rotor frame made of a magnetic material and a disk fixed thereto; And a shaft fixed to the shaft and supported by the bearing. The end face of the magnet and the inner and outer pole teeth are axially opposed to each other with a small gap therebetween. Small brushless DC motor. 2. The small brushless DC motor according to claim 1, wherein the stator yoke is formed by bending or drawing one silicon steel plate. 3. The stator yoke has a silicon content of 2%.
2. The small brushless DC motor according to claim 1, wherein the brushless DC motor is made of the following silicon steel sheet. 4. The small brushless DC motor according to claim 1, wherein a terminal of a position detection sensor for detecting a rotational position of the magnet is directly connected to a wire processing end of the coil. 5. The rotor position detection sensor is located between the outer peripheral pole teeth of the stator yoke in the radial direction, and there is no pole tooth between the position detection sensor and the magnet in the axial direction. 2. The small brushless DC motor according to 1. 6. The small brushless DC motor according to claim 1, wherein the mechanism for holding the bearing is arranged on the same circumference as the inner peripheral pole teeth of the stator yoke.