JPH0965614A - Small-sized motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cool the stator of a small-sized motor by generating an air current in the axial direction while the rotor of the motor rotates by providing spaces extended in the axial direction and a plurality of blades in a hub section which couples the permanent magnets of the rotor with the shaft of the rotor. SOLUTION: In the rotor 7 of a PM type motor which is faced to the internal peripheral surface of the stator of the motor with a gap in between, spaces A and B extended in the axial direction and a plurality of blades 9 are provided in a hub section which couples the permanent magnets 8 of the rotor 7 with the shaft 5 of the rotor 7. The blades 9 are integrally formed with a boss section 19 by using the same member as that of the magnets 8 and the blades 9 are spirally formed in the axial direction so that the axial spaces A and B can be formed between each blade 9. Consequently, an air current is generated by the blades 9 in the axial direction through the rotor 7 when the rotor 7 rotates and the stator can be cooled effectively. Therefore, a small-size motor which has a simple constitution and the temperature of which does not rise much can be obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a small electric motor, and more particularly to the structure of a PM electric motor having a rotor with a permanent magnet, which is used in office machines, labor-saving equipment, amusement equipment and the like.

[Prior art]

FIG. 11 is a cross-sectional view of a conventional small-sized electric motor, in which 1 is a front cover, 2 is a cup-shaped casing, 3 is a stator core, 4 is a stator winding, and 5 is a rotor shaft. , 6 is a bearing, 7 is a rotor, and 8 is a permanent magnet. FIG.
In the small electric motor shown in FIG. 1, a stator winding 4 is wound around a stator core 3 surrounded by a front cover 1 and a cup-shaped casing 2 and formed in an annular shape and provided with a plurality of magnetic poles on the inner circumference. A rotor 7 including a permanent magnet 8 is rotatably arranged so as to face the child and an inner peripheral surface of the stator via a gap. As shown in FIGS. 12, 13 and 14, the rotor 7 is composed of an annular permanent magnet 8, a rotor shaft 5, and a hub portion 7 ′ connecting the permanent magnet 8 and the rotor shaft 5. The permanent magnet 8 and the hub portion 7'are integrally formed of the same member as the permanent magnet 8, and the hub portion 7'is not provided with a space penetrating in the axial direction. The small electric motor shown in FIG. 11 operates as an electric motor when the stator winding 4 is energized for a predetermined amount of time, a magnetic field is generated in the stator to rotate the rotor in a predetermined direction.

[Problems to be solved by the invention]

The small electric motor shown in FIG. 11 is used by being incorporated in equipment such as office machines. However, as the equipment of the other party to be incorporated becomes smaller, the small electric motor is also required to be smaller, and the output is small. There is a growing demand for larger ones. As a means to increase the output in a small size, use a high-performance magnet as a permanent magnet of the rotor,
It has been dealt with by increasing the input of the stator winding,
There is a problem that the temperature increases as the input increases.
It is an object of the present invention to obtain a small electric motor that can reduce the temperature without changing the external dimensions.

BEST MODE FOR CARRYING OUT THE INVENTION

In the small electric motor according to the present invention, a hub portion connecting the permanent magnet of the rotor and the rotor shaft is provided with a space penetrating in the axial direction and a plurality of blades, and the hub portion is provided when the rotor rotates. The blades generate an air flow in the axial direction of the rotor to cool the stator. Furthermore, if holes are provided in the front cover and the cup-shaped case so as to face the blades provided on the rotor so as to communicate with the outside air, the effect of lowering the temperature is enhanced.

【Example】

FIG. 3 shows a rotor 7 of a small electric motor according to the present invention.
1 is a front view of the first embodiment, FIG. 4 is a sectional view, FIG. 5 is a rear view, and FIG. 6 is a perspective view. 3, FIG. 4, FIG. 5 and FIG. 6, 8 is a permanent magnet, 9 is a blade, 10 is a boss portion, 5 is a rotor shaft, and A and B are axially penetrating spaces which are the permanent magnet 8 and the blade 9. And the boss portion 10 are all integrally formed of the same member as the permanent magnet 8. The blade 9 is formed in a spiral shape in the axial direction as shown in the sectional views and the perspective views in FIG. 6, and spaces A and B penetrating in the axial direction are formed between the blades.

FIG. 7 shows a rotor 7 of a small electric motor according to the present invention.
8 is a front view of the second embodiment, FIG. 8 is a sectional view, and FIG. 9 is a rear view. In FIGS. 7, 8 and 9, 8 is a permanent magnet,
11 is a holding member for holding the permanent magnet 8, 12 is a blade, 1
Reference numeral 3 is a boss portion, and A and B are spaces penetrating in the axial direction.
In the rotor of FIGS. 7, 8 and 9, the holding member 11 that holds the permanent magnet 8, the blade 12 and the boss portion 13 are integrally formed of the same member, and the blade 12 is the first member shown in FIG. Like the example, it is formed in a spiral shape in the axial direction and is formed of a member different from the permanent magnet 8.

The first embodiment of the present invention is shown in FIG. 3 or FIG.
When the rotor 7 shown in FIG. 10 is mounted on the small electric motor shown in FIG. 10 and the stator winding is energized, the rotor rotates, and the blades 9 or 12 provided on the rotor penetrate the rotor to rotate the shaft. An air flow is generated in the direction to cool the stator.

Further, in the second embodiment, as shown in FIGS. 1 and 2, a ventilation hole 15 is provided at a position opposed to the blades provided on the front cover 1 and the cup-shaped case 2 of the small electric motor. And the airflow generated by the rotation of the blades communicates with the outside air to enhance the cooling effect. FIG. 15 shows temperature rise test data comparing the cooling effects of a small electric motor according to the present invention, where a is a conventional one, b is a rotor provided with blades of the present invention, and c is a front cover. Also, the effect of the present invention is shown by providing a ventilation hole in the cup-shaped case.

[0010]

Since the small electric motor according to the present invention has the above-mentioned structure, there is an effect that a small electric motor having a simple structure and a small temperature rise can be obtained.

[Brief description of drawings]

FIG. 1 is a front view showing the structure of a second embodiment of a small electric motor according to the present invention.

FIG. 2 is a sectional view showing a structure of a second embodiment of a small electric motor according to the present invention.

FIG. 3 is a front view of the first embodiment of the rotor of the small electric motor according to the present invention.

FIG. 4 is a sectional view of a first embodiment of a rotor of a small electric motor according to the present invention.

FIG. 5 is a rear view of the first embodiment of the rotor of the small electric motor according to the present invention.

FIG. 6 is a perspective view of a first embodiment of a rotor of a small electric motor according to the present invention.

FIG. 7 is a front view of a second embodiment of the rotor of the small electric motor according to the present invention.

FIG. 8 is a sectional view of a second embodiment of the rotor of the small electric motor according to the present invention.

FIG. 9 is a rear view of the second embodiment of the rotor of the small electric motor according to the present invention.

FIG. 10 is a front view showing the structure of the first embodiment of the small electric motor according to the present invention.

FIG. 11 is a cross-sectional view showing the structure of a conventional small-sized electric motor.

FIG. 12 is a front view showing a structure of a rotor of a small electric motor according to a conventional technique.

FIG. 13 is a cross-sectional view showing a structure of a rotor of a small electric motor according to a conventional technique.

FIG. 14 is a rear view showing a structure of a rotor of a small electric motor according to a conventional technique.

FIG. 15 is comparative data of temperature rise showing the effect of the small electric motor according to the present invention.

[Explanation of symbols]

 1 Front Cover 2 Cup-shaped Case 3 Stator Magnetic Pole 4 Stator Winding 5 Rotor Shaft 7 Rotor 7'Rotor Hub 8 Permanent Magnet 9 Blade 10 Boss 11 Permanent Magnet Holding Member 12 Blade 13 Boss 14 Cup-shaped case according to the present invention 15 Ventilation holes A, B Spaces penetrating in the axial direction

Claims (4)

[Claims] 1. A stator iron core, which is surrounded by a cup-shaped casing and a front cover, is formed in an annular shape and has a plurality of magnetic poles formed on its inner peripheral surface, and an annular winding is formed on the stator iron core. A small electric motor having a wound stator and a rotor provided with a permanent magnet that is rotatably supported by an inner peripheral surface of the stator with a gap therebetween. A small electric motor comprising a hub portion connecting the shaft with a space penetrating in the axial direction and a plurality of blades. 2. The small electric motor according to claim 1, wherein the permanent magnet and the hub portion connecting the rotor shaft are integrally formed of the same member as the permanent magnet. 3. The small electric motor according to claim 1, wherein the hub portion connecting the permanent magnet and the rotor shaft is formed of a member different from the permanent magnet. 4. The small electric motor according to claim 1, wherein holes are provided at positions facing the blades of the rotor of the cup-shaped casing and the front cover.