JP2007053867A - Permanent-magnet motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a slotless winding-type permanent-magnet motor wherein the same gap flux density as in a slot winding-type motor and as a result, high-torque and low-loss characteristics are maintained and its structure is simplified. <P>SOLUTION: The permanent-magnet motor includes: a stator 11 constructed of a cylindrical hollow stator core 14 without a slot and a concentrated winding coil 15 that is installed on the inner radius side of the stator core 14 and formed in an annular shape; and a rotor 12 that is opposed to the stator 11 with a gap in-between and has a field magnet 21 placed on the surface of its shaft 22. The stator 11 has a soft magnetic powder molding material 13 fit in a hole 15a positioned in the center of the annularly molded concentrated winding coil 15. The soft magnetic powder molding material 13 is obtained by molding individual iron particulates having an insulating film on their surfaces with resin, and is in such a shape that it is fit in the hole 15a without no space between them. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a permanent magnet type electric motor in which a field magnet is installed on a rotor.

Conventionally, in a permanent magnet type electric motor including a stator core having a slot and a rotor provided with a field magnet, torque has been improved and loss has been reduced. In particular, in a small permanent magnet type electric motor, the first factor of loss is copper loss. Therefore, a method of dividing the stator core to reduce copper loss has been proposed. This method can increase the space factor of the winding because the stator is formed after the winding wound in advance on the bobbin is mounted on the divided stator core.
Against this background, a slotless winding type permanent magnet motor having a simple stator structure has been proposed for further miniaturization of the motor (see, for example, Patent Document 1).
FIG. 5 is a front sectional view of a conventional slotless winding type permanent magnet motor. In FIG. 5, 1 is a soft magnetic layer, 2 is a concentrated winding coil, 3 is a stator core, 4 is a permanent magnet, 5 is a rotor yoke, 6 is an insulating layer, and 7 is a gap.
The stator core 3 has a hollow cylindrical shape, has no slots on the inner diameter side, and is arranged with concentrated winding coils 2 formed in an annular shape on the inner diameter side. A hole located between adjacent concentrated winding coils 2 or in the center of the concentrated winding coil 2 is formed of an insulating layer 6. A soft magnetic layer 1 is provided on the surface of the concentrated winding coil 2 facing the air gap 7 for the purpose of increasing the armature inductance and reducing loss due to a decrease in current ripple during PWM driving.
As described above, the conventional slotless winding type permanent magnet electric motor has a simple structure that is smaller and easier to manufacture than the slot winding type in which a winding is wound around a tooth.

Another example of an electric motor having a simple structure is one in which a stator core is molded by taking advantage of the high flexibility of the soft magnetic powder molding material (see, for example, Patent Document 2).
JP 2002-159152 A (Specification, page 4, FIG. 1) JP 2001-128405 A (Specification, page 3, FIG. 1)

However, in the conventional slotless winding type permanent magnet electric motor shown in Patent Document 1, the structure is simple and suitable for a small motor, but the coil space is directly used as a gap, and the magnetic path for the field magnet is used. There was a tendency that the resistance increased and the gap magnetic flux density decreased. Therefore, there is a problem that the torque is reduced and the number of windings is increased due to the necessity of designing to a desired characteristic, and the copper loss is increased.
On the other hand, in the motor that manufactures the stator core using the conventional soft magnetic powder molding material shown in Patent Document 2, a method of mounting a pre-wound winding on the stator core cannot be performed. There was a problem that the product ratio could not be increased.
The present invention has been made in view of such problems, and can obtain a gap magnetic flux density equivalent to that of a slot winding type electric motor. As a result, it has a high torque and low loss characteristics, and is simple. An object of the present invention is to provide a slotless winding type permanent magnet electric motor having a structure.

In order to solve the above problems, the present invention is configured as follows.
The invention according to claim 1 is a stator constituted by a hollow cylindrical stator core without slots, a concentrated winding coil mounted on the inner diameter side of the stator core and formed in an annular shape, and the stator In a permanent magnet type electric motor provided with a rotor disposed opposite to each other through a gap and having a field magnet disposed on the surface, the stator is a hole located at the center of the annular concentrated coil. It is characterized in that a soft magnetic powder molding material is fitted to the part.
According to a second aspect of the present invention, there is provided the permanent magnet type electric motor according to the first aspect, wherein the soft magnetic powder molding material is formed by molding individual iron powder having an insulating film on the surface thereof. .
Further, the invention according to claim 3 is the permanent magnet type electric motor according to claim 1 or 2, wherein the soft magnetic powder molding material has a thickness equivalent to that of the concentrated winding coil in a radial direction, and the soft magnetic powder The outer surface of the molding material is in close contact with the inner surface of the stator iron core, and the inner surface of the soft magnetic powder molding material is formed with a cylindrical surface so as to face the rotor together with the concentrated winding coil.
According to a fourth aspect of the present invention, in the permanent magnet type electric motor according to the first or second aspect, the concentrated winding coil into which the soft magnetic powder molding material is fitted closely contacts the inner surface of the stator core. It is characterized by being fixed without overlapping in the circumferential direction.

According to the first aspect of the present invention, the soft magnetic powder molding material fitted in the hole located in the center of the annular concentrated winding coil becomes a part of the magnetic path, and the gap magnetic flux density equivalent to that of the slot winding type electric motor Thus, it is possible to provide a slotless winding type permanent magnet electric motor having a simple structure and high torque and low loss characteristics.
According to the second aspect of the present invention, a soft magnetic powder molded material having a large electric resistance can be formed, and an increase in eddy current loss can be kept low.
According to the invention described in claim 3, the magnetic path resistance with respect to the field magnet can be reduced, and the gap magnetic flux density can be increased.
According to the fourth aspect of the present invention, the coil space can be kept to a minimum, and the magnetic path resistance with respect to the field magnet can be reduced.

  Embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a side sectional view of a permanent magnet type electric motor according to an embodiment of the present invention, and FIG. 2 is a front sectional view taken along line AA of FIG.
In the figure, 11 is a stator, 12 is a rotor, 13 is a soft magnetic powder molding material, 14 is a stator core, 15 is a concentrated winding coil, 15a is a hole, 16 is a load side plate, and 17 is an anti-load side plate. , 18 is a coil connection part, 19 is a frame, 20 is a bearing, 21 is a field magnet, 22 is a shaft, and 23 is a resin member. In addition, about the structure of this invention, a permanent magnet type | mold electric motor is comprised from the hollow cylindrical stator iron core 14 without a slot, and the concentrated winding coil 15 with which it attached to the internal diameter side of the stator iron core 14, and was shape | molded cyclically | annularly. Basically, Patent Document 1 discloses that the stator 11 and the rotor 12 that are disposed so as to face the stator 11 with a gap and have the field magnet 21 disposed on the surface of the shaft 22 are provided. Are the same.
The features of the present invention are as follows.
That is, the stator 11 is a point in which the soft magnetic powder molding material 13 is fitted into the hole 15a located in the center of the concentrated winding coil 15 formed in an annular shape. The soft magnetic powder molding material 13 is formed by molding individual iron powders having an insulating film on the surface with a resin, and has a shape that fits into the hole 15a without a gap.
The soft magnetic powder molding material 13 has the same thickness as the concentrated winding coil 15 in the radial direction. The outer surface of the soft magnetic powder molding material 13 is in close contact with the inner surface of the stator core 14, and the soft magnetic powder molding material 13. A cylindrical surface is formed so as to face the rotor 12 together with the concentrated winding coil 15.
Furthermore, the concentrated winding coil 15 into which the soft magnetic powder molding material 13 is fitted is in close contact with the inner surface of the stator core 14 and is fixed with an adhesive or the like without overlapping in the circumferential direction.

FIG. 3 is a perspective view for explaining an assembling procedure of the stator used in the permanent magnet type electric motor of this embodiment.
In FIG. 3, a concentrated winding coil 15 is formed by fitting a necessary number of concentrated winding coils 15 and a soft magnetic powder molding material 13 to be fitted into a hole 15a located in the center of the concentrated winding coil 15. The soft magnetic powder molding material 13 fitted to 15 is brought into close contact with the inner surface of the stator core 14, and the inner surface is bonded together with the concentrated winding coil 15 so as to form a cylindrical surface of an air gap, thereby forming a stator. . At this time, the coil connection part 18 shown in FIG. 1 is also fixed integrally.

  In this way, in the first embodiment, the stator 11 has a configuration in which the soft magnetic powder molding material 13 is fitted into the hole 15a located in the center of the concentrated winding coil 15 formed in an annular shape. The soft magnetic powder molding material fitted into the hole 15a becomes a part of the magnetic path, and a gap magnetic flux density equivalent to that of the slot winding type electric motor can be obtained, and a permanent magnet electric motor with high torque and low loss can be obtained. be able to. In addition, since a similar manufacturing method is used with a simple structure equivalent to that of a normal slotless winding type electric motor, an inexpensive electric motor can be manufactured.

FIG. 4 is a front sectional view of a stator of a permanent magnet type electric motor showing a second embodiment of the present invention.
In the figure, reference numeral 23 denotes a resin member.
In the second embodiment, as in the first embodiment, the soft magnetic powder molding material 13 is formed by molding individual iron powder having an insulating film on the surface with a resin so that a hole located at the center of the concentrated winding coil 15 is formed. The point which comprises the shape fitted to 15a without a gap, and the point that the soft magnetic powder molding material 13 has the thickness equivalent to the concentrated winding coil 15 in the radial direction are the same.
The difference is that when the outer surface of the concentrated winding coil 15 formed by fitting the soft magnetic powder molding material 13 is brought into close contact with the inner surface of the stator core 14, it is held by the resin member 23 so as not to overlap in the circumferential direction. This is the point.
Since the second embodiment has the above-described configuration, the soft magnetic powder molding material fitted into the hole located at the center of the concentrated winding coil becomes a part of the magnetic path, and the gap magnetic flux density equivalent to that of the slot winding type electric motor. Thus, a permanent magnet motor with high torque and low loss can be provided. In addition, since a similar manufacturing method is used with a simple structure equivalent to that of a normal slotless winding type electric motor, an inexpensive electric motor can be manufactured.

The electric motor of the present invention is used for a motor with a reduction gear that is small and requires high torque, such as a finger joint of a humanoid robot. In order to effectively use the limited space, sensorless driving is used, and the space necessary for position detection is used as a space for increasing torque. Although sensorless driving by feedback control based on position estimation may be performed as necessary, in this embodiment, driving is performed using rectangular wave driving with an electrical angle of 150 ° energization and sequential driving with a cycle of 12 steps.
Further, since the electric motor of this embodiment is provided with a two-stage harmonic reduction gear (not shown) on the load side and performs a reduction of 1500: 1, it is possible to position at least 36000 steps with respect to one rotation of the output shaft. Yes, the maximum torque of a single motor can be increased by 500 times or more including efficiency reduction.
Furthermore, the electric motor of the present invention contributes to an increase in torque and a reduction in loss, but conversely, the cogging torque tends to increase, which increases the torque ripple in the driving state. On the other hand, torque ripple can be smoothed by setting the rotation speed of the electric motor in a normal use state to 10,000 rotations per minute or more. Therefore, the present invention is effective for increasing torque and reducing loss even with a normal motor. However, when a motor with a reduction gear with a high speed reduction is used, the drawback is eliminated and its usefulness becomes remarkable.

Side sectional view of a permanent magnet type motor showing an embodiment of the present invention, FIG. 1 is a front sectional view taken along line AA in FIG. The perspective view for demonstrating the assembly procedure of the stator used for the permanent magnet type electric motor of a present Example, Front sectional view of a stator of a permanent magnet type electric motor showing a second embodiment of the present invention, Front sectional view of a conventional slotless winding type permanent magnet motor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Soft magnetic layer 2 Concentrated winding coil 3 Stator core 4 Permanent magnet 5 Rotor yoke 6 Insulating layer 7 Gap 11 Stator 12 Rotor 13 Soft magnetic powder molding material 14 Stator core 15 Concentrated winding coil 15a Hole 16 Load side plate 17 Anti-load side plate 18 Coil connection portion 19 Frame 20 Bearing 21 Field magnet 22 Shaft 23 Resin member

Claims (4)

A stator composed of a hollow cylindrical stator core without slots, and a concentrated winding coil that is attached to the inner diameter side of the stator core and formed into an annular shape;
In a permanent magnet type electric motor provided with a rotor arranged opposite to the stator via a gap and having a field magnet disposed on the surface,
The stator is a permanent magnet type electric motor characterized in that a soft magnetic powder molding material is fitted into a hole located in the center of the annular concentrated coil.   2. The permanent magnet type electric motor according to claim 1, wherein the soft magnetic powder molding material is formed by molding individual iron powder having an insulating film on a surface thereof.   The soft magnetic powder molding material has a radial thickness equivalent to that of the concentrated winding coil, the outer surface of the soft magnetic powder molding material is in close contact with the inner surface of the stator core, and the inner surface of the soft magnetic powder molding material The permanent magnet motor according to claim 1 or 2, wherein a cylindrical surface is formed so as to face the rotor together with the concentrated winding coil.   3. The permanent magnet according to claim 1, wherein the concentrated winding coil into which the soft magnetic powder molding material is fitted is fixed to the inner surface of the stator core without being overlapped in the circumferential direction. Magnet motor.

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