JP2875497B2 - Motor stator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor stator, and more particularly to a motor stator suitable for a rotating magnetic field type motor such as a brushless motor.

[0002]

2. Description of the Related Art In a motor, for example, a rotating magnetic field type motor such as a brushless motor, a winding is applied to a plurality of iron cores formed in a stator, and an electric current flows through the windings to generate a rotating magnetic field. The magnet-equipped rotor, which is arranged inside, is rotated.

In order to prevent power loss and heat generation due to eddy current, such a stator for a rotating magnetic field type motor is made of a thin magnetic material such as a silicon steel plate whose surface is subjected to insulation treatment such as an insulation film. It is formed by laminating core sheets.

[0004] Such a core sheet is provided with an outer core sheet part formed in a ring shape, and a plurality of iron core parts serving as winding axes of the windings are provided inside the outer core sheet part. It is fixed radially inward in the direction. A ring-shaped bridging portion is formed integrally with the radially inner ends of these iron core portions, whereby the radially inner ends of the iron core portions are connected to each other. That is, the plurality of iron cores are integrally formed radially by the bridge.

In such a stator in which core sheets are laminated, since a plurality of iron cores are connected by a bridging portion, the core sheets can be mass-produced by press working or the like, and lamination is easy. There are advantages. In addition, since the iron core portion is linked by the bridging portion, the iron core portion and the outer core sheet can be separately formed, whereby the slot portion for applying the winding (between the adjacent iron core portions) can be formed. Is open outward in the radial direction, so that there is an advantage that winding is easy and the winding process can be automated.

On the other hand, in the stator having the above-described structure, since the iron core portion is connected by the bridging portion, a part of the magnetic flux generated from the magnet of the rotor becomes a leakage magnetic flux flowing in the bridging portion. Such leakage magnetic flux does not pass through the iron core portion, and thus does not affect the rotation of the rotor at all.

[0007] A similar problem also occurs when the core sheet having the above structure is used for the stator of an induction motor. In this case, a part of the magnetic flux generated by the current flowing through the winding wound around the iron core becomes the ineffective magnetic flux flowing in the bridge. Such an ineffective magnetic flux does not pass through the rotor disposed inside the stator and does not affect the rotation of the rotor.

[0008] Such a leakage magnetic flux and an ineffective magnetic flux do not act on the rotation of the rotor, and it is necessary to generate an effective magnetic flux sufficient to compensate for them. Has become.

One example of a stator for solving such a drawback is disclosed in JP-A-2-7839 and JP-A-2-280.
No. 641.

In the stator disclosed in Japanese Patent Application Laid-Open No. 2-7839, a concave portion opened radially outward is provided on the outer peripheral surface of the bridge portion, and the width of the bridge portion is reduced to thereby reduce the width of the bridge portion. Is to reduce the effective cross-sectional area. As a result, the magnetic resistance of the bridging portion is increased, so that the ineffective magnetic flux flowing through the bridging portion can be reduced and the effective magnetic flux can be increased. In addition, a recess is formed in the stator manufacturing process up to that time. Without the need for additional manufacturing processes.
It can be implemented at low cost.

On the other hand, in the stator disclosed in Japanese Patent Application Laid-Open No. Hei 2-280641, the bridge portion is subjected to a thermal treatment to change the metal structure of the bridge portion and reduce the magnetic permeability of the bridge portion. Things. This increases the reluctance of the bridge, reducing the ineffective magnetic flux flowing through the bridge and increasing the effective magnetic flux. In addition, by changing the metal structure of the bridge, the bridge The mechanical strength of the part can be improved.

[0012]

However, the stator disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 2-7839 can be manufactured at a low cost because it is only necessary to provide a recess in the bridging portion. Since the strength in the width direction of the bridging part is reduced by providing, the bridging part may be deformed in the radial direction due to the force when winding the iron core part, and the width of the bridging part is sufficiently reduced. There was a drawback that the width could not be reduced and a sufficient effect could not be obtained.

On the other hand, in the stator disclosed in JP-A-2-280641, the mechanical structure can be improved by changing the metal structure of the bridging portion by thermal treatment. Since it is necessary to perform a thermal treatment on the part, a heat treatment step must be added to the stator manufacturing process up to that point, which increases the number of steps and increases the cost.

[0014] In consideration of the above fact, the present invention can effectively reduce the leakage flux or the ineffective flux flowing through the bridge without lowering the mechanical strength. It is an object of the present invention to obtain a motor stator that can be output and reduced in size.

[0015]

According to a first aspect of the present invention, there is provided a stator for an electric motor, wherein an outer core sheet portion is formed in a thin and ring-like shape, and radially inward in an inner peripheral surface of the core sheet portion. A plurality of iron core portions provided with windings provided so as to protrude, and a bridging portion connecting the radially inner ends of the plurality of iron core portions to each other,
A stator for an electric motor configured by laminating a plurality of sheets, wherein a thickness of the bridging portion along the axial direction of the stator is formed smaller than other portions of the core sheet.

[0016]

According to the first aspect of the present invention, the thickness of the bridging portion of the core sheet in the axial direction is formed thinner than other portions of the core sheet. Here, the magnitude of the magnetic resistance of the magnetic body is inversely proportional to the magnitude of the effective sectional area of the magnetic path. Therefore, by reducing the thickness, the bridging portion has a smaller effective cross-sectional area than other portions, and the magnetoresistance is increased. As a result, the leakage flux or the ineffective magnetic flux unrelated to the operation of the motor flowing through the bridge portion is reduced, and the effective magnetic flux effective for the operation of the motor is increased. Therefore, it is possible to increase the output and reduce the size of the electric motor.

Further, since only the thickness of the bridge portion in the axial direction is reduced, the mechanical strength of the bridge portion, particularly the strength against radial force, can be ensured.

[0018]

FIG. 1 is a perspective view of a stator 10 (hereinafter simply referred to as "stator 10") of an electric motor according to a first embodiment of the present invention. FIG. 2 is a plan view when the stator 10 is applied to the brushless motor 11.

As shown in these figures, the stator 1
0 is constituted by a plurality of core sheets 12.

The core sheet 12 is made of a thin magnetic material such as a silicon steel plate having a surface coated with an insulating film (not shown), and is formed into a predetermined shape by press working or the like. The core sheet 12 is provided with a ring-shaped outer core sheet portion 14, and fitting portions 16 are formed on the inner peripheral surface at predetermined intervals.

Further, the core sheet 12 is provided with a plurality of iron core portions 18. These iron core portions 18 are provided inside the outer core sheet portion 14 and are arranged radially inward in the radial direction. These iron cores 18
A dovetail portion 20 is formed at a radially outer end of the outer core sheet portion 14.
And is integrally fixed.

On the other hand, the radially inner ends of the iron core portions 18 are adjacently connected to each other integrally by a bridging portion 24. Therefore, the radially inner ends of the iron core portions 18 are connected to each other. The end portion and the bridging portion 24 are formed in a ring shape in plan view as a whole.

As shown in FIG. 3, these bridging portions 24 are thinner than other portions of the core sheet 12 such as the iron core portion 18. That is, the bridging portion 24 has a predetermined step with respect to one surface in the thickness direction of the adjacent iron core portion 18 (the surface in the direction of arrow A in FIGS. 1 and 3), and has a concave opening. It has been.

The stator 10 is a core sheet 1 having the above-described structure.
2 and is formed by laminating a plurality of core sheets 12 coaxially. Therefore, a portion corresponding to the bridging portion 24 of the stator 10 is cut off intermittently in the axial direction (the direction of the arrow A in FIG. 1). Therefore, the substantial thickness at this portion (the thickness of the magnetic material portion) is smaller than the substantial thickness of the other portions of the stator 10.

Further, the stator 10 is provided with a winding (not shown) on the laminated iron core 18. FIG.
As shown in FIG.
Is arranged. A plurality of magnets 25 having different magnetic poles adjacent to each other are arranged on the outer periphery of the rotor 26.

Next, the operation of this embodiment will be described. In the stator 10 having the above-described configuration, the thickness of the bridging portion 24 is smaller than the thickness of the other portions of the core sheet 12. Is reduced according to the ratio of the thickness of the bridge portion 24 to the thickness of the other portions. Here, the magnitude of the magnetic resistance of the magnetic body such as the stator 10 is inversely proportional to the magnitude of the effective sectional area of the magnetic path through which the magnetic flux flows. Therefore, in the stator 10, the effective thickness in this portion is reduced by reducing the substantial thickness in the axial direction at the bridging portion 24, so that the magnetic resistance is reduced. Is increased more than the other parts. Thereby, the magnet 25 of the rotor 26
Out of the magnetic fluxes generated in the stator 10 and flowing in the direction of the adjacent magnet 25 through the bridge portion 24, the effective magnetic flux flowing in the iron core portion 18 can be increased. .

FIG. 4 shows a graph obtained by analyzing the relationship between the thickness of the bridging portion 24 and the effective magnetic flux in the brushless motor 11 by FEM analysis. In this figure, both the thickness and the effective magnetic flux of the bridging portion 24 are relative values when the state where the thickness of the bridging portion 24 is not reduced as in the related art is set to 1. As shown in FIG.
The effective magnetic flux can be increased by about 15% by reducing the effective cross-sectional area by reducing the thickness of the effective magnetic flux to about 1/2%.
It can be increased by 5%.

As described above, in the stator 10 having the above-described structure, by reducing the thickness of the bridging portion 24 of the core sheet 12, the leakage magnetic flux flowing through the bridging portion 24 is reduced, and the rotation of the rotor 26 is reduced. The effective magnetic flux that acts can be effectively increased, and the size and the output of the electric motor can be reduced.

Further, in the stator 10 having the above structure, only the thickness of the bridging portion 24 of the core sheet 12 is reduced.
Since the width of the bridging portion 24 is equivalent to that of the conventional stator, the mechanical strength of the stator 10, particularly the strength against the radial force, can be secured, and the force at the time of winding the iron core portion 18 is reduced. Even if it acts, the stator 10 will not be deformed.

Further, since the bridging portion 24 can be made thin by the pressure at the time of forming the core sheet 12 by pressing or the like, the conventional stator manufacturing process can be diverted, and the manufacturing process is not changed and the cost is reduced. It can be manufactured at a low cost. In addition, the metal structure of the bridging portion 24 is changed by the action of the pressure at the time of the press working.
Can be increased, and the leakage magnetic flux flowing through the bridge portion 24 can be further effectively reduced by the synergistic effect of the effect of reducing the effective area and the effect of changing the metal structure. .

In this embodiment, a plurality of bridging portions 24 are provided.
Had the same thickness, and had a concave shape opened in the same direction (the direction of arrow A in FIGS. 1 and 3).
The present invention is not limited to this. For example, the bridging portion 24 is directed to the opposite side to the above-described embodiment (that is, the direction of the arrow A in FIGS. 1 and 3).
The opening 24 may be formed in a concave shape, and the bridging portions 24 having different opening directions (step directions) may be confused. Furthermore, in consideration of the strength after lamination, the thickness of each bridging portion 24 may be individually made different, or the thickness of the bridging portion 24 may be changed for each core sheet 12. . In these cases, the same effects as in the above embodiment can be obtained.

Next, a second embodiment of the present invention will be described. The same parts as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and description thereof is omitted.

FIG. 5 is a perspective view of a stator 40 (hereinafter, simply referred to as "stator 40") of the electric motor according to the first embodiment of the present invention.

As shown in FIG.
Is constituted by a plurality of core sheets 42. These core sheets 42 are provided with a plurality of iron core portions 18, and the inner ends of these iron core portions 18 in the radial direction are integrally connected to each other by a bridging portion 46. For this reason, the radially inner end of the iron core portion 18 and the bridging portion 46 are formed in a ring shape in plan view as a whole.

As shown in FIG. 6, these bridging portions 46 are thinner than other portions of the core sheet 42 such as the iron core portion 18. That is, the bridging portion 46 has a predetermined step on both sides in the thickness direction of the adjacent iron core portion 18 and has a shape that is concavely opened in both the thickness directions.

The stator 40 is provided with the core sheet 4 having the above structure.
2, and is formed by laminating a plurality of core sheets 42 coaxially. For this reason, the portion corresponding to the bridging portion 46 of the stator 40 is cut off intermittently in the axial direction (the direction of the arrow A in FIG. 5). Accordingly, the substantial thickness at this portion (the thickness of the magnetic material portion) is smaller than the substantial thickness of the other portions of the stator 40.

In the stator 40 having the above structure, the bridging portion 46
Is thinner than other portions of the core sheet 42, the effective cross-sectional area at this portion is smaller than at other portions, and the magnetic resistance is lower than at other portions of the stator 40. Be increased.

As a result, of the magnetic flux generated from the magnet 25, the leakage magnetic flux passing through the bridging portion 46 in the direction of the adjacent magnet 25 is reduced, and the effective magnetic flux flowing to the iron core 18 is increased. it can.

As described above, in the stator 40 having the above-described structure, by reducing the thickness of the bridging portion 46 of the core sheet 42, the leakage magnetic flux flowing through the bridging portion 46 is reduced, and the rotation of the rotor 26 is reduced. The same effect as in the first embodiment can be obtained, for example, the effective magnetic flux that acts can be effectively increased, and the motor can be reduced in size and output can be increased.

In this embodiment, a plurality of bridge portions 46 are provided.
Have the same thickness, but are not limited to this. For example, each of the bridging portions 4
The thickness of the bridging portion 46 may be changed for each core sheet 42. In these cases, the same effects as in the present embodiment can be obtained.

Further, in the first and second embodiments, the core sheets 12 and 42 are formed by the iron core 18 and the bridge 2.
4 and 46 are integrally formed, and the dovetail portion 20 of the iron core portion 18 is fitted and fixed to the fitting portion 16 of the outer core sheet portion 14, but the present invention is not limited to this. The core portion 18 is integrally formed inside the seat portion 14, and the bridging portions 24, 46 are formed in a ring shape thinner than the outer core seat portion 14, so that the bridging portions 24, 46 and the core portion 18 are formed. You may comprise so that it may be integrally connected. In this case, the same effect as in the above embodiment can be obtained.

Further, in the first embodiment and the second embodiment, the stators 10 and 40 are applied to the brushless motor 11. However, the present invention is not limited to this.
40 may be applied to an induction motor. In this case, of the magnetic flux generated by the current flowing through the winding applied to the iron core portion 18, the ineffective magnetic flux flowing in the direction of the adjacent iron core portion 18 after passing through the bridging portion 46 is reduced. The effective magnetic flux that flows inside the entangled portion 46 and acts on the rotation of the rotor can be effectively increased.

[0043]

As described above, in the electric motor stator according to the present invention, the thickness of the bridge portion of the core sheet is made thinner in the axial direction of the stator than in other portions of the core sheet. Thereby, the magnetic resistance of the bridge portion can be effectively increased. For this reason, it is possible to effectively reduce the leakage magnetic flux or the ineffective magnetic flux flowing through the bridge portion, and it is possible to increase the output and reduce the size of the motor.

Further, since only the thickness of the bridging portion is reduced, the mechanical strength in the radial direction of the core sheet can be maintained, and the force at the time of winding the iron core portion acts. Also, the bridge portion is not distorted in the radial direction.

Further, since the thickness of the bridging portion can be reduced by press working or the like, it can be manufactured by the same manufacturing process as before, and can be manufactured at low cost without changing the process.

[Brief description of the drawings]

FIG. 1 is a perspective view of a stator of an electric motor according to a first embodiment of the present invention.

FIG. 2 is a plan view when the stator of the electric motor according to the first embodiment of the present invention is applied to a brushless motor.

FIG. 3 is an enlarged front view of a bridging portion shown in FIG. 1;

4 is a graph showing the relationship between the thickness of a bridging portion and the effective magnetic flux showing the effect of the stator of the electric motor shown in FIG. 1;

FIG. 5 is a perspective view of a stator of an electric motor according to a second embodiment of the present invention.

FIG. 6 is an enlarged front view of a bridge portion shown in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Stator of motor 12 Core sheet 14 Outer core sheet part 18 Iron core part 24 Bridge part 40 Stator of motor 42 Core sheet 46 Bridge part

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-136046 (JP, A) JP-A-1-238442 (JP, A) JP-A-1-303029 (JP, A) JP-A 63-136 174531 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) H02K 1/18

Claims (1)

(57) [Claims] 1. An outer core sheet portion formed in a thin ring shape and a plurality of iron cores provided radially inward on an inner peripheral surface of the core sheet portion and radially inwardly provided with a winding. And a bridging portion that connects radially inner ends of the plurality of iron core portions to each other. A stator of an electric motor configured by stacking a plurality of core sheets, the bridging portion comprising: The thickness of the part along the direction of the stator axis is formed thinner than other parts of the core sheet.