JP2003264942A - Stator iron core of motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stator iron core for a motor which reduces iron loss by stipulating crystal grain diameter of a unidirectional electromagnetic steel plate so as to materialize magnetic zone structure narrow in interval between magnetic walls in the stator of the motor. <P>SOLUTION: In the stator iron core of the motor, a yoke and teeth are divided and further the yoke is made by stacking divided unidirectional electromagnetic plates and die-cut in circumferential direction. The iron core is constituted by the unidirectional electromagnetic plates where length of a yoke piece or a tooth piece is made 60 mm or less, and the crystal grain diameter in the direction of rolling is controlled to be not more than 20 mm. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stator iron core, a tooth piece, and a yoke piece of various motors for which efficiency is improved, and more particularly to a technique for realizing a magnetic domain structure having a narrow domain wall spacing in the stator of the motor.

[0002]

2. Description of the Related Art Conventionally, for example, a stator of a three-phase synchronous motor is constructed by laminating thin electromagnetic steel plates in the axial direction of a rotary shaft. The steel sheets to be laminated have an insulating layer and an adhesive layer formed on a part of the surface, and are mechanically caulked after assembly or are laminated and fixed by heating and melting the adhesive layer. An example of such a motor is disclosed in Japanese Patent Laid-Open No. 2-119.
A "variable reluctance motor" shown in Japanese Patent No. 561 is known.

As a material for such a stator, a non-oriented electrical steel sheet is usually adopted. This is for the following reason. Considering the magnetic flux formed on the stator side, the magnetic flux is in the radial direction of the motor at the tooth portion and is in the circumferential direction at the yoke portion. In this way, the directions of the magnetic flux between the teeth and the yoke differ by almost 90 °, and even if the teeth that are adjacent to each other are compared, the direction of the magnetic flux differs between the teeth by the central angle between the teeth. become. In a stator with different magnetic flux directions,
When trying to reduce iron loss as a whole, it is not easy to efficiently combine iron loss and magnetic flux in a unidirectional electrical steel sheet where there is a direction in which magnetization is easy.Therefore, it is common to use a non-oriented electrical steel sheet. Has been adopted.

On the other hand, in the stator structure of the motor, at least the teeth of the separate teeth and yoke are made of unidirectional magnetic steel sheet, and the easy magnetization direction of the unidirectional electromagnetic steel sheet is in the radial direction. Is disclosed in Japanese Patent Application Laid-Open No. 7-067272. It is disclosed that this stator structure can greatly reduce the iron loss in the teeth as compared with the case of being formed of a non-oriented electrical steel sheet.

[0005]

In order to improve the efficiency of the electromagnetic motor, for example, to increase the output torque of the three-phase synchronous motor and to reduce the size of the motor, the iron loss in the teeth and the yoke must be further reduced. I have to. By the way, focusing on teeth, for example, the direction of magnetic flux is limited to the radial direction, so it is known that unidirectional electrical steel sheets can be used so that the radial direction is the direction of easy magnetization, and iron loss can be considerably reduced. . These problems are common not only to the synchronous motor but also to the synchronous generator and the like. However, further reduction in iron loss is a subject for further size reduction and higher efficiency of the motor, and this is also a subject of the present invention.

[0006]

The concrete means of the present invention are as follows. (1) In a stator core of a motor in which a yoke and a tooth are divided, and further, the yoke is divided in the circumferential direction and punched and laminated to form a unidirectional electromagnetic steel sheet, the length of the yoke piece or the teeth piece is small. A stator core for a motor, which is 60 mm or less and is punched from a grain-oriented electrical steel sheet having a grain size in the rolling direction of 20 mm or less. (2) The rolling direction of the unidirectional electrical steel sheet is made up of punched yoke pieces or teeth pieces that are aligned with the longitudinal direction of the yoke pieces or teeth pieces or set within an angle range of 60 °. The stator core of the motor according to (1). (3) The stator core of a motor according to (1) or (2), characterized in that the teeth have protrusions on both sides of an end connected to the yoke.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, in order to improve the efficiency of the motor, increase the output torque, and reduce the size of the motor, the iron loss in the teeth and the yoke has been reduced. The present inventors paid attention to the material of these parts and conducted earnest research to effectively realize a method of reducing iron loss.

Description will be given below based on experiments. The present inventors have constructed a stator using a steel sheet having a grain size smaller than that found in the conventional unidirectional electrical steel sheet for the yoke and the teeth, and as a stator, it has been confirmed that the iron loss is lower than that of the conventional stator. It was

FIG. 1 shows a core block in which the tooth 1 and the yoke 2 are integrated. In the crystal grains of the grain-oriented electrical steel sheet, bar magnets with a width of 0.2 to 2 mm are arranged side by side so that the NSs are reversed. This is called a magnetic domain, and the boundary is called a domain wall. When is large, the domain wall moves so that the area of the magnetic domain having the same magnetization direction as the magnetic flux flow increases. When the interval between the domain walls is wide, the moving speed of the domain wall becomes fast, so that a large amount of eddy current flows around the domain wall, and the iron loss increases. If the particle size is small, this magnetic domain becomes finer, so the eddy current becomes smaller and iron loss decreases (Fig. 2). Therefore, the smaller the particle size, the better.

Next, the reasons for limitation of the present invention will be described. The average grain size in the rolling direction of unidirectional electrical steel sheet is 10-
Although it is about 50 mm, in the present invention, the grain size in the rolling direction of the grain-oriented electrical steel sheet used for the teeth and yoke pieces is 20.
Limited to mm or less. This is to reduce the iron loss by making the size of the magnetic domain in the tooth piece and the yoke piece as small as possible, and is based on the fact that the magnetic domain size cannot be made sufficiently smaller than 20 mm. The reason why the length of the tooth piece is defined to be 60 mm or less is that the object of the present invention is a medium-sized motor to a small motor, and this effect is not noticeable in a large motor.

FIG. 3 shows the relationship between the magnetic flux density at a magnetizing force of 800 A / m and the iron loss at a magnetic flux density of 1.7T. In the characteristics of the grain-oriented electrical steel sheets with plate thicknesses of 0.30 mm and 0.35 mm, the iron loss tends to be lower as the crystal grain size is smaller. The 180 ° domain wall spacing becomes narrower as the crystal grain size becomes finer. The relationship between the 180 ° domain wall spacing and iron loss is shown in FIG. The 180 ° domain wall spacing becomes narrower by applying tension in the steel sheet rolling direction. From this figure, it is seen that the iron loss tends to decrease as the domain wall spacing becomes narrower.

The relationship between the rolling direction of the unidirectional electrical steel sheet and the longitudinal direction of the yoke pieces and the teeth pieces is set to the angle range of 0 to 60 ° for the following reason. When the cogging torque was measured in the stator composed of the teeth pieces with different angles, it was the smallest in the vicinity of the inclination angle of 30 °. This is because, when these ranges are examined in detail, it has been found that the cogging torque can be reduced by 40% within the range of 0 to 60 °.

Further, for example, as shown in FIG. 6, the reason why the tooth piece 1 has protrusions on both sides of the end portion connected to the yoke piece 2 is that the magnetic flux flows gently from the tooth piece to the yoke piece. This is for reducing the rotating iron loss.

The steel sheet used here may or may not have a glass coating. The reason is that when the glass coating is provided, the effect of further reducing the iron loss is observed, and when it is not provided, the punching property is good and the die manufacturing cost is reduced. The manufacturer can appropriately decide which advantage should be taken in manufacturing the stator core.

[0015]

EXAMPLES The present invention will be described below based on examples. [Embodiment 1] FIG. 5 shows a sectional view of a stator of a permanent magnet motor to which the present invention is applied. In FIG. 5, the stator iron core of the motor is divided into the same number of yoke pieces 2 of the stator as the number of teeth 1 by the dividing surface 5, and is formed by punching out a unidirectional electromagnetic steel plate. A winding wire 4 is wound around the tooth piece 1 via an insulating portion 3. As shown in FIG. 5, the unidirectional electrical steel sheet is used such that the teeth piece is parallel to the radial direction and the yoke piece is parallel to the circumferential direction. Further, the yoke piece 2 and the tooth piece 1 are laminated such that the easy magnetization directions of the unidirectional electromagnetic steel sheets are all in the same direction as the arrow in the figure. Also,
A unidirectional electrical steel sheet having a grain size of 12 mm in the rolling direction, which satisfies the conditions described in claim 1, is used for the tooth piece and the yoke piece.

In the stator core of the motor having the above-mentioned structure, the iron core loss of the stator is realized by using the unidirectional electrical steel sheet having a smaller grain size than the conventional one for both the teeth piece and the yoke piece. Further, the magnetic flux passing through the stator core always flows in the direction of easy magnetization of the grain-oriented electrical steel sheet having a high magnetic permeability, so that the magnetic flux density can be increased and the induced voltage is increased.

Further, in the vicinity of the teeth end portion of the stator core, the magnetic flux is bent to the tooth portion, and the magnetic flux flowing from the void portion into the tooth can be concentrated in a certain direction of easy magnetization. Even if the position of the magnetic pole of the permanent magnet changes, the direction of easy magnetization is such that the magnetic flux in the gap flows in the direction of easy magnetization of the unidirectional electrical steel sheet, so it is less affected by the slot opening and cogging torque and induced It had the effect of reducing voltage distortion and torque ripple. The iron loss generated in the teeth and the yoke is low when the material under the conditions described in claim 1 is used, and the iron loss is 15% by the thermoviewer observing the heat distribution generated by the iron loss.
It was confirmed to be low.

[Second Embodiment] A second embodiment of the present invention will be described below with reference to the drawings. FIG. 6 is a cross-sectional view of the stator piece 6, which is formed by laminating a predetermined number of pieces of the stator core made of a unidirectional electromagnetic steel plate material. The iron core pieces are laminated so that the easy magnetization directions of the odd-numbered pieces and the even-numbered pieces are orthogonal to each other. However, the tilt angle is 0 ° or more and 60
° The range is below.

In the above structure, the iron loss of the stator is reduced by using the grain-oriented electrical steel sheets having a smaller grain size than the conventional ones for both the teeth and the yoke. Since the magnetic flux has the property of flowing toward the higher magnetic permeability, it becomes easier for the magnetic flux entering the stator core pieces from the void to flow to the odd-numbered electromagnetic steel sheets on the right side and to the even-numbered electromagnetic steel sheets on the left side. . Further, in the stator constructed under the conditions set forth in claim 1, heat generation due to iron loss was small, and the field could be strengthened so that it could be used with high torque.

According to the embodiment of the present invention as described above, the effect of the first embodiment can be obtained in the case of rotating leftward or rightward like a servomotor. The present invention can be applied regardless of whether the motor structure is an inner rotor type or an outer rotor type.

[0021]

As described above, according to the present invention, the iron core of the motor is divided and laminated by using the unidirectional magnetic steel sheets, and the grain size of the steel sheets is regulated, so that the iron loss is low and the cogging torque is low. And increase the induced voltage while reducing the induced voltage distortion,
Further, it is possible to obtain a small-sized and high-output motor with less torque ripple and uneven rotation. Further, by determining the easy magnetization direction of the unidirectional electrical steel sheet in accordance with the direction of the magnetic flux in the iron core, the exciting current can be suppressed, the iron loss in the iron core can be reduced, and high efficiency can be achieved.

Aligning the easy magnetization direction of the unidirectional magnetic steel sheet with the magnetic flux flowing direction in the iron core makes it easier to fix the magnetic flux flowing direction than in the case of the non-oriented magnetic steel sheet, and thus even in mass production. It is easy to manufacture a device that always forms a constant magnetic circuit, and this has the effect of suppressing variations in product characteristics. Further, the division and subdivision of the laminated core reduces the size of the press equipment, which has the effect of significantly improving the production efficiency.

[Brief description of drawings]

FIG. 1 is a diagram showing a magnetic domain pattern on a stator piece.

FIG. 2 is a diagram showing a stator piece and its magnetic domain pattern when the crystal grain size of the present invention is specified.

FIG. 3 is a diagram showing the relationship between crystal grain size and iron loss.

FIG. 4 is a diagram showing the relationship between 180 ° domain wall spacing and iron loss.

FIG. 5 is a diagram in which a stator is formed by combining the laminated iron core pieces in the example.

FIG. 6 is a diagram showing a method of forming a laminated iron core piece.

[Explanation of symbols]

1 tooth piece 2 yoke piece 3 Insulation part 4 Winding 5 split surface 6 stator piece

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor openness             20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel shares             Company Technology Development Division (72) Inventor Masao Utanimoto             20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel shares             Company Technology Development Division F-term (reference) 5H002 AA03 AB01 AC06 AC08 AE07                       AE08

Claims (3)

[Claims] 1. In a stator core of a motor, wherein a yoke and a tooth are divided, and further, the yoke is divided in the circumferential direction and punched and laminated to form a unidirectional electrical steel sheet. A stator core for a motor, characterized in that the grain size is 60 mm or less and the grain size in the rolling direction is 20 mm or less punched from a grain-oriented electrical steel sheet. 2. A yoke piece or a teeth piece punched by matching the rolling direction of the unidirectional electrical steel sheet with the longitudinal direction of the yoke piece or the teeth piece or by setting the angle within 60 °. Claim 1 characterized by
The stator core of the described motor. 3. The stator core of a motor according to claim 1, wherein the teeth have protrusions on both sides of an end portion connected to the yoke.