JP2003264946A - Stator iron core of motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stator iron core of a motor which reduces iron loss by specifying a depth of a groove of a unidirectional electromagnetic 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 unidirectional electromagnetic steel plates being divided and die-cut in circumferential direction. Further, the iron core is constituted of the unidirectional electromagnetic steel plates in each of which the depth of the optimum groove in each of the case where it has fine grains within the structure of the steel plates at the bottoms of the grooves drawn up periodically, and the case where it does not have fine grains is decided and controlled, according to the design density of magnetic fluxes. <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 electromagnetic motors for which efficiency is improved, and more specifically, a unidirectional electromagnetic steel sheet having a structure with a narrow domain wall interval is used for a motor stator. Regarding technology.

[0002]

2. Description of the Related Art Conventionally, a stator of a motor of this type, for example, 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
A "variable reluctance motor" disclosed in Japanese Patent Application Laid-Open No. 2-119561 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. As described above, the magnetic flux directions of the teeth and the yoke are different by almost 90 degrees, and even if the teeth are adjacent to each other, the magnetic flux direction of each tooth is different by the central angle between the teeth. become. In a stator with different magnetic flux directions,
In order to reduce the iron loss as a whole, in the unidirectional electrical steel sheet where there is a direction of easy magnetization, the combination of efficiently flowing the iron loss and magnetic flux requires advanced technology, so use the non-oriented electrical steel sheet. Has been adopted.

On the other hand, in the stator structure of the motor, at least one of the tooth piece and the yoke piece which are separate bodies is formed of a unidirectional electromagnetic steel sheet, and the easy magnetization direction of the unidirectional electromagnetic steel sheet is set in the radial direction. This is disclosed in JP-A-7-067272. It is disclosed that the iron loss in the teeth can be greatly reduced 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. . The above problems are common not only to synchronous motors, but also to synchronous generators, etc., but further iron loss reduction is an issue for further size reduction and high efficiency of motors,
This is also the subject of the present invention.

[0006]

The concrete means of the present invention are as follows. (1) In a stator core of a motor, which is formed by dividing a yoke and a tooth and further laminating a unidirectional electromagnetic steel sheet punched by dividing the yoke in the circumferential direction, the yoke piece or the tooth piece is provided on the surface thereof. A stator core of a motor having grooves arranged periodically at an angle close to a right angle with respect to the length direction of the yoke pieces or the teeth pieces. (2) When the steel sheet structure at the bottom of the periodically arranged grooves has fine grains, when the groove depth is D _m (μm) and the design magnetic flux density is Bd (T), -12. 5Bd + 26.25 < _Dm <-12.5Bd +
36.25 is satisfied, The stator core of the motor of (1) characterized by the above-mentioned. (3) When fine grains do not exist in the steel sheet structure at the bottom of the above-mentioned periodically arranged grooves, when the groove depth is D _g (μm) and the design magnetic flux density is Bd (T), −12 _{.5Bd + 36.25 <D g <-12.5Bd} +
46.25 is satisfied, The stator core of the motor of (1) characterized by the above-mentioned. (4) The rolling direction of the unidirectional electrical steel sheet on the yoke piece or the teeth piece is set in the range of 0 ° to 60 ° with respect to the length direction of the yoke piece or the teeth piece (1) A stator core of the motor according to any one of (1) to (3). (5) The tooth pieces have protrusions on both sides of an end portion connected to the yoke piece (1) to (4).
The stator core of the motor according to any one of 1.

[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, 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 developed a unidirectional electrical steel sheet in which a groove having a depth of several tens of microns is periodically formed in a yoke piece or a tooth piece at an angle that is closer to a right angle to the pressure direction of the steel sheet than in conventional unidirectional electrical steel sheets. When a stator was constructed by using it, it was confirmed that the iron loss was reduced as compared with the conventional stator made of a magnetic steel sheet without grooves.

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 so that NSs are reversed, and this is called a magnetic domain, and the boundary is called a domain wall. The domain wall moves so that the area of the magnetic domain having the magnetization in the same direction as the 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. When the groove is formed at an angle close to a right angle, the magnetic domain becomes finer, so that the eddy current becomes smaller and the iron loss decreases (Fig. 2).

Next, the reasons for limitation of the present invention will be described. The reason why the unidirectional electrical steel sheet is used for the teeth and the yoke is that the iron loss in the rolling direction is 1/3 that in the case of using the non-oriented electrical steel sheet. Further, by providing grooves that are periodically arranged at an angle close to a right angle to the easy magnetization direction, it is possible to further reduce iron loss by about 7%.

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 iron loss is observed, and when the glass coating 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.

When the designed magnetic flux density is Bd, the depth D _m (μm) of fine grooves having a fine grain size of about 0.1 mm at the bottom of the above-mentioned periodically arranged grooves is -12.5Bd + 26. 0.25 <D _m <-12.5 Bd +
The reason defined by the formula of 36.25 is based on the experimental result.
At Bd = 1.3T, a depth of 15 μm (FIG. 3), Bd = 1.
This is because at 7T, the iron loss reduction was great at a depth of 10 μm (FIG. 4).

Further, the depth D _g (μm) of the groove having no fine particles is -12.5 Bd + 36.25 <D _g <-12.5 Bd +
The reason defined by the equation of 46.25 is also based on the experimental result.
= 1.3T, depth of 25 μm (Fig. 5), Bd = 1.7T
This is because the reduction of iron loss was large at a depth of 20 μm (FIG. 6).

Here, the conditions are individually defined for the presence or absence of fine particles, but this is because each manufacturing process is different. For example, a method of mechanically applying strain to a steel sheet to form a groove is a step in which when annealing is performed at 700 to 800 ° C., fine crystal grains are generated due to the strain in the vicinity of the groove. The method of chemically forming a groove by etching without applying strain is a process in which fine crystal grains are not generated because there is no strain. Therefore, the optimum groove depth is defined here for both processes.

The reason why the rolling direction of the unidirectional electrical steel sheet and the longitudinal direction of the yoke pieces and the teeth pieces are in the angular range of 0 to 60 ° is as follows. 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, in the stator composed of the yoke pieces whose angles are changed, since the magnetic flux has a property of flowing to the side having a higher magnetic permeability, when the magnetic flux entering the yoke from the air gap is bent 90 °, the magnetic permeability is at an angle at which it easily bends. The magnetic flux easily passes when the direction of high is oriented. When this angle was in the range of 0 to 60 °, the effect of reducing iron loss was exhibited. When rotating to the left or right like a servo motor, it is better to change the sign of the angle between the odd numbered sheet and the even numbered sheet. Although the effect is halved compared to the case of one-way rotation, the iron loss is low.

Further, for example, as shown in FIG. 8, the reason why the tooth piece 1 has projections on both sides of the end portion connected to the yoke piece 2 is that the flow of magnetic flux from the tooth piece to the yoke piece is made gentle. 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.

[0018]

EXAMPLES The present invention will be described below based on examples. [Embodiment 1] FIG. 7 is a sectional view of a stator of a permanent magnet motor to which the present invention is applied. In FIG. 7, the iron core of the motor is divided into the same number of laminated iron core pieces as the number of magnetic poles by the dividing surface 5, and the laminated iron core pieces are made of unidirectional magnetic steel sheet. A winding portion 4 is wound around the laminated core piece through an insulating portion 3. As shown in FIG. 7, the unidirectional electrical steel sheet is used so that the direction of easy magnetization is parallel to the radial direction in the teeth and to the circumferential direction in the yoke. In addition, the laminated core pieces are laminated such that the easy magnetization directions of the unidirectional electrical steel sheets are all in the same arrow direction. Also, the average groove depth of 1 on the teeth and yoke
A unidirectional electrical steel sheet having fine particles of 2 μm is used.

In the iron core of the motor having the above structure, the iron loss of the stator has been reduced more than ever before with the design magnetic flux density of 1.7 T for both the teeth and the yoke. Further, the magnetic flux passing through the individual laminated core pieces always flows in the direction of easy magnetization of the unidirectional 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 laminated core piece, magnetic flux is bent to the teeth portion of the laminated core piece, and the magnetic flux flowing from the void portion into the teeth can be concentrated in a certain direction in the easy magnetization direction. It was 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.

[Second Embodiment] A second embodiment of the present invention will be described below with reference to the drawings. FIG. 8 is a cross-sectional view of the laminated iron core piece 7, which is configured by laminating a predetermined number of iron core pieces 6 made of unidirectional electrical steel sheet 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 in the range of 0 degrees to 60 degrees.

In the above structure, by using the grain-oriented electrical steel sheet having an average groove depth of 20 μm and having no fine grains for both the teeth and the yoke, the iron loss of the stator can be reduced more than ever before at the designed magnetic flux density of 1.3T. . Since the magnetic flux has the property of flowing toward the higher magnetic permeability, the magnetic flux entering the laminated iron core pieces from the voids easily flows to the odd-numbered electromagnetic steel sheets on the right side and to the even-numbered electromagnetic steel sheets on the left side. .

According to such an embodiment of the present invention, the effect of the first embodiment can be obtained in the case of rotating to the left or right 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.

[0024]

As described above, according to the present invention, the unidirectional electromagnetic wave in which the iron core of the motor is divided and the groove having the depth corresponding to the designed magnetic flux density is located at an angle close to a right angle with respect to the rolling direction. By stacking steel sheets, the iron loss is low, the induced voltage is increased while the cogging torque and induced voltage distortion are reduced, and a small motor with high torque output and small torque ripple and rotation unevenness can be obtained. . 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.

Further, by aligning the easy magnetization direction of the unidirectional magnetic steel sheet with the magnetic flux flowing direction in the iron core, the magnetic flux flowing direction can be fixed more easily than in the case of the non-oriented magnetic steel sheet, and 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 in an iron core piece of a conventional invention.

FIG. 2 is a diagram showing an iron core piece and its magnetic domain pattern when a groove of the present invention is formed.

FIG. 3 is a diagram showing the relationship between groove depth with fine particles and iron loss at Bd = 1.3T.

FIG. 4 is a diagram showing a relationship between a groove depth with fine particles and iron loss at Bd = 1.7T.

FIG. 5 is a diagram showing a relationship between groove depth without fine particles and iron loss at Bd = 1.3T.

FIG. 6 is a diagram showing the relationship between groove depth without fine particles and iron loss at Bd = 1.7T.

FIG. 7 is a diagram in which a stator is formed by combining the laminated iron core pieces in the example.

FIG. 8 is a view showing a method of forming a laminated iron core piece.

[Explanation of symbols]

1 tooth piece 2 yoke piece 3 Insulation part 4 Winding part 5 Dividing surface 6 Iron core piece 7 Laminated iron core pieces

   ─────────────────────────────────────────────────── ─── 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 AB04 AC02 AC04                       AC08

Claims (5)

[Claims] 1. In a stator core of a motor, which is formed by dividing a yoke and a tooth, and further by stacking unidirectional electrical steel sheets punched by dividing the yoke in the circumferential direction, the yoke piece or the tooth piece has a surface thereof. A stator core of a motor, wherein the stator core of the motor has grooves arranged periodically at an angle close to a right angle with respect to the length direction of the yoke piece or the teeth piece. 2. When the steel sheet structure at the bottom of the periodically arranged grooves has fine grains, when the groove depth is D _m (μm) and the design magnetic flux density is Bd (T): 12.5Bd + 26.25 < _Dm <-12.5Bd +
36.25 is satisfied, The stator iron core of the motor of Claim 1 characterized by the above-mentioned. 3. When no fine grains are present in the steel sheet structure at the bottom of the periodically arranged grooves, the groove depth is set to D _g (μ
m), when the design magnetic flux density is Bd (T), -12.5Bd + 36.25 <D _g <-12.5Bd +
The stator core of the motor according to claim 1, wherein the stator core satisfies 46.25. 4. The rolling direction of the unidirectional electrical steel sheet on the yoke piece or the teeth piece is set in the range of 0 ° to 60 ° with respect to the length direction of the yoke piece or the teeth piece. Item 4. A stator core of a motor according to any one of items 1 to 3. 5. The stator core of a motor according to claim 1, wherein the teeth piece has protrusions on both sides of an end portion connected to the yoke piece.