JPH11262201A - Stator core of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the stator core of a motor which enables increase in volumes of coil windings applied to teeth. SOLUTION: A stator core 12 consists of an annular back yoke 25 and a plurality of teeth 26, which are integrally arranged on the inner circumference of the back yoke in a circumferential direction. Expansion parts 27, where the diameter of the back yoke 25 is expanded to make the distance between the adjacent teeth expanded, are formed in the back yoke 25 at positions between adjacent teeth. The expansion part 27 consists of two narrow tablet members 29a and 29b defined by slits 28a-28c which are cut straight into the back yoke 25 in radial directions and arranged in a circumferential direction at predetermined intervals. By having the narrow tablet members 29a and 29b opened into a V-shape, the inner diameter of the expansion part 27 is increased, and hence the distance between the adjacent teeth 26 can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stator core of an electric motor formed by punching out a magnetic steel plate in a ring shape.

[0002]

2. Description of the Related Art For example, an electric motor such as a brushless DC motor has an annular stator core in which a rotor is housed. This rotor is rotatably supported by a motor frame holding the stator core. The stator core is formed by punching a magnetic steel plate and laminating a plurality of the steel plates.

As shown in FIGS. 10 (a) and 10 (b), the stator core 1 has an annular back yoke 2 and a plurality of circumferentially protrudingly provided on the inner peripheral surface of the back yoke 2. Teeth 3.

A coil 5 is wound around the teeth 3 by a nozzle 4. That is, when the coil 5 is passed through the inside of the nozzle 4 and the tip of the coil 5 is fixed at a predetermined position, the coil 5 is wound around the tooth 3 by rotating the nozzle 4 around the tooth 3. Like that.

[0005] In such a stator core 1, one of the factors for improving the performance of the electric motor is a winding amount of the coil 5 wound around the teeth 3, that is, a slot 6 which is a space between the adjacent teeth 3. It is known to improve the space factor, which is the ratio of the coil 5 to the area.

However, if the stator core 1 is previously punched in an annular shape, the nozzle 4 is wound around the adjacent teeth 3 because the nozzle 4 is inserted into the slot 6 and the coil 5 is wound. A space that does not interfere with the coil 5 must be left in the slot 6. Therefore, there is a case where there is a limitation in increasing the space factor of the coil 5 in the slot 6. That is, it is necessary to secure a space in which the nozzle 4 can be rotated along the periphery of the teeth 3, so that the winding amount of the coil 5 around the teeth 3 is limited.

[0007] Further, a locking portion 3a for holding the coil 5 wound therearound is provided at the tip of the tooth 3 along the radial direction. For this reason, the frontage 6a of the slot 6 is narrowed by the locking portion 3a.
The degree of freedom was limited and the space factor could not be increased.

[0008]

As described above, in a conventional stator core formed by punching out a steel plate in an annular shape, the coil is wound around the above-mentioned teeth by the size and opening of the slot, which is a space between adjacent teeth. Due to the limited amount, the space factor could not be increased.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a stator core of an electric motor in which when winding a coil around a tooth, a slot between the teeth is enlarged to increase a winding amount of the coil around the tooth.

[0010]

According to a first aspect of the present invention, an annular back yoke and a plurality of teeth arranged at predetermined intervals in a circumferential direction on an inner peripheral surface of the back yoke are integrally formed. In the stator core of the electric motor, a portion between the adjacent teeth of the back yoke is formed with a telescopic portion for expanding the diameter of the back yoke to increase the interval between the adjacent teeth.

According to a second aspect of the present invention, in the first aspect of the invention, the extendable portion comprises a plurality of slits formed in parallel on the inner and outer peripheral sides of the back yoke except for thin portions. It is characterized by the following.

According to a third aspect of the present invention, in the second aspect of the present invention, a pair of side surfaces of the expansion and contraction portion opposed to each other with the slit interposed therebetween are formed with uneven portions that engage with each other. .

According to the first aspect of the present invention, when winding the coil around the teeth, the slots, which are spaces between adjacent teeth, can be enlarged by expanding the diameter of the stator core by the expandable and contractible portions. The amount of winding of the coil around can be increased.

According to the second aspect of the present invention, since the expandable portion is formed by the plurality of slits, the expandable portion can be easily provided on the stator core. According to the third aspect of the present invention, a pair of side surfaces facing each other with the slit interposed therebetween,
By forming the concavo-convex portions to be engaged with each other, even when an external force is applied to the stator core in a state where the expandable portion is reduced, the annular shape is less likely to be deformed.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show a first embodiment of the present invention.
An embodiment will be described. FIG. 4 shows a motor 11 having a stator core 12,
Are held in the motor case 13. This motor case 13 is made by molding resin or premix,
By inserting the stator core 12 at the time of molding, they are integrated.

A hollow portion 14 is formed on one side of the motor case 13 and an opening 15 is formed on the other side. A first bearing 16 is housed and held in the hollow portion 14, and the opening 15 is closed by a bracket 18 holding a second bearing 17 on the inner surface thereof.

A rotor 19 is accommodated in the internal space of the stator core 12. The rotating shaft 21 provided on the rotor 19 has one end rotatably supported by the first bearing 16 and protrudes from the hollow shaft 14 to the outside of the motor case 13. It is rotatably supported by a bearing 17.

The stator core 12 is formed by laminating a plurality of stator members 20 shown in FIGS.
That is, the stator member 20 has a back yoke 25 formed in an annular shape by punching out a magnetic steel plate, and a plurality of stator members 20 projecting from the inner peripheral surface of the back yoke 25 at equal intervals in the circumferential direction. And nine T-shaped teeth 26 having locking portions 26a.

As shown in FIGS. 1 to 3, an elastic portion 27 capable of expanding the annular shape of the back yoke 25 is formed at a portion between the adjacent teeth 26 of the back yoke 25. The elastic portion 27 is formed by a plurality of slits cut linearly along the radial direction of the back yoke 25 at predetermined intervals along the circumferential direction of the back yoke 25, and in this embodiment, three slits 28a to 28c. It consists of the two strip members 29a and 29b formed.

That is, as shown in FIGS. 3 (a) and 3 (b), the slit 28b
One end is open to the outer periphery of the back yoke 25, and the other end communicates with a small hole 31b formed on the inner periphery of the back yoke 25 while leaving a thin portion 30b. The remaining two slits 28
a and 28c have one end open to the inner periphery of the back yoke 25 and the other end formed on the outer periphery of the back yoke 25 at a thin portion 30a, 3c.
It communicates with the small holes 31a, 31c formed leaving 0c.

Accordingly, as shown in FIG. 3 (a), the back yoke 25 formed in an annular shape deforms the three thin portions 30a to 30c of each of the expansion and contraction portions 27 to form the two strip portions 29a and 29b into V-shaped portions. By opening in a letter shape, the inner diameter dimension can be enlarged, and the interval between adjacent teeth 26 can be enlarged.

Note that the expansion and contraction portion 27 is provided on the back yoke 2.
5 can be punched and formed at the same time, and the slits 28a to 28c can be processed by laser light or a blade (grinding stone). However, other means such as slits 28a to 28c
And both the small holes 31a to 31c may be processed by laser light. Further, as another means, the stator member 20 having the slits 28a to 28c and the small holes 31a to 31c may be punched from a predetermined steel plate so that the slits 28a to 28c are opened. In this case, the stator core 12 is punched in a state where the inner diameter is enlarged.

A coil 33 is wound around each tooth 26 via an insulating layer 32. That is, when the coil 33 is wound, the telescopic portion 27 of the back yoke 25 is extended,
The distance between adjacent teeth 26 is increased. After the tip of the coil 33 passed through the nozzle 4 (shown in FIG. 10) is fixed in place, the coil 4 is wound around the tooth 26 by rotating the nozzle 4 along the periphery of the tooth 26. Turned.

When the coil 33 is wound, the expansion and contraction portion 27 is extended, so that the distance between a pair of adjacent teeth 26 is reduced.
That is, the width dimension of the slot 34 and the frontage 35 thereof are enlarged. Thereby, the winding amount of the coil 33 can be increased by an amount corresponding to the enlargement of the slot 34 and the frontage 35, so that the performance of the electric motor 11 can be improved by increasing the winding amount.

When the coil 33 has been wound around each tooth 26, the diameter of the back yoke 25 is reduced to reduce the expansion and contraction portion 27 so that no gap is formed in the circumferential direction of the back yoke 25 by the expansion and contraction portion 27. Thereby, even if the elastic portion 27 is formed on the back yoke 25, it is possible to prevent the magnetic resistance from increasing.

The reduced diameter stator core 12 is insert-molded when the motor case 13 shown in FIG. 4 is molded, so that the reduced diameter state is reliably maintained. The diameter of the stator core 12 may be reduced by press-fitting the stator core 12 into a motor case (not shown) formed in a tubular shape in advance.

FIG. 5 shows a modification of the winding around the teeth 26. In this embodiment, the teeth 2 are attached to the stator core 12.
6 shows a lap winding in which 12 coils are formed and the coil 33 is wound over three teeth 26. Also in this case, when the coil 33 is wound, the frontage 35 between the adjacent teeth 26 can be widened by expanding the expansion and contraction portion 27 and expanding the diameter of the back yoke 25 of the stator core 12. The amount of winding of the coil 33 over the teeth 26 can be increased.

When the winding of the coil 33 has been completed,
7, it is inevitable that the coil 33 wound over the plurality of teeth 26 will be loosened.
As long as it does not come off from the locking portion 26a, there is no practical problem.

FIGS. 6 to 9 show second to fifth embodiments of the present invention. These embodiments are modifications of the expandable portion. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

That is, the second type shown in FIGS.
The expansion and contraction portion 27A of the embodiment has three slits 41a.
41c are formed to be inclined at a predetermined angle with respect to the circumferential direction of the back yoke 25.

By inclining the slits 41a to 41c, the joining surface of each slit is inclined with respect to the radial direction of the back yoke 25. Thus, even if an external force is applied to the back yoke 25 whose diameter has been reduced, each of the slits 41a to 41
Since the joint surface of c is hard to slide in the radial direction, the back yoke 2
5 is less likely to be deformed. That is, the slit 41
By inclining a to 41c, the elastic portion 27A is an engaging portion that is not easily deformed by an external force.

FIGS. 7A and 7B show a third embodiment of the present invention.
In the embodiment, three slits 42a-
42c has an arc shape. That is, one of the side surfaces joined to each other across the three slits 42a to 42c is a concave curved surface 43a, and the other is a convex curved surface 4 that engages with the concave curved surface 43a.
3b. That is, the concave curved surface 43a and the convex curved surface 43b form an engaging portion.

Thus, even when an external force is applied to the back yoke 25 in a state where the elastic portion 27B is contracted, the joint surface between the slits 42a to 42c of the elastic portion 27B is formed by joining the concave curved surface 43a and the convex curved surface 43b. Can be prevented from being deformed by slipping, so that the circular shape of the back yoke 25 can be prevented from being damaged.

In the fourth embodiment of the present invention shown in FIGS. 7A and 7B, three slits 44a to
An engagement portion was formed by forming a semicircular concave portion 45a on one side of the side surface joined to each other with the 44c interposed therebetween and a semicircular convex portion 45b engaging with the concave portion 45a on the other side.

According to such a configuration, even when an external force is applied to the back yoke 25 in a state where the extendable portion 27C is reduced, the joint surface of the slits 44a to 44c is formed by the engagement between the concave portion 45a and the convex portion 45b. Slides and stretches 27
Since the deformation of B is prevented, the circular shape of the back yoke 25 can be accurately maintained.

FIGS. 9A and 9B show a fifth embodiment of the present invention.
The embodiment is similar to the above third embodiment,
The difference is that the three slits 46a to 46c of the expansion and contraction portion 27D are not in the shape of an arc but in the shape of a letter. In other words, one of the side surfaces joined to each other across the three slits 46a to 46c has a triangular concave portion 47a, and the other has the same triangular convex portion 4 engaging with the concave portion 47a.
The engaging portion was formed by forming 7b.

Accordingly, even when an external force is applied to the back yoke 25 in a state where the elastic portion 27D is reduced,
The engagement between the concave portions 47a and the convex portions 47b prevents the joint surfaces of the slits 46a to 46c from slipping and preventing the elastic portion 27D from being deformed, so that the circular shape of the back yoke 25 can be maintained accurately. it can.

In the above embodiments, the expansion and contraction portion is formed by three slits. However, the expansion and contraction portion may be formed by two or four or more slits. Or any structure that can be made smaller.

[0039]

According to the first aspect of the present invention, when a coil is wound around a tooth, the expansion and contraction portion is extended to expand the diameter of the stator core, thereby forming a slot as a space between adjacent teeth and a frontage thereof. Can be increased.

Thus, the amount of winding of the coil around the teeth can be increased, so that the performance of the motor can be improved. According to the second aspect of the present invention, a plurality of slits are cut in the back yoke to form the expansion and contraction portions.

Therefore, it is possible to easily provide the above-mentioned expansion and contraction portion on the stator core. According to the third aspect of the present invention, the concave and convex portions engaging with each other are formed on the pair of side surfaces facing each other across the slit.

Therefore, even if an external force is applied to the stator core in a state where the above-mentioned expansion and contraction portion is reduced, its annular shape is less likely to be deformed. By forming the expansion and contraction portion on the stator core, it is possible to prevent the shape accuracy from being reduced. can do.

[Brief description of the drawings]

FIG. 1 is a plan view of a stator core according to a first embodiment of the present invention, in which an expansion and contraction portion is reduced.

FIG. 2 is a plan view of the stator core in a state where the expansion and contraction portion is extended.

FIG. 3 is an enlarged view of a tooth portion before and after winding a coil.

FIG. 4 is a schematic configuration diagram of the electric motor.

FIG. 5 is an explanatory view showing a modification of the winding around the teeth.

FIG. 6A is a plan view of a stator core according to a second embodiment of the present invention, and FIG.

FIG. 7A is a plan view of a stator core showing a third embodiment of the present invention, and FIG.

FIG. 8A is a plan view of a stator core according to a fourth embodiment of the present invention, and FIG.

FIG. 9A is a plan view of a stator core according to a fifth embodiment of the present invention, and FIG.

10A is an explanatory diagram illustrating a state in which a coil is wound around teeth of a stator core having a conventional structure, and FIG. 10B is an explanatory diagram illustrating a state in which a coil is wound around teeth.

[Explanation of symbols]

 12 ... stator core 25 ... back yoke 26 ... teeth 27 ... expansion and contraction parts 27A to 27D ... expansion and contraction parts 28a to 28c ... slits 41a to 41c ... slits 42a to 42c ... slits 44a to 44c ... slits 46a ... 46c ... slits

Claims (3)

[Claims] 1. A stator core of an electric motor in which an annular back yoke and a plurality of teeth arranged at predetermined intervals in a circumferential direction on an inner peripheral surface of the back yoke are integrally formed, and the back yoke is adjacent to the stator yoke. A stator core for an electric motor, wherein a stretchable portion is formed at a portion between the teeth so as to expand the back yoke to increase the distance between adjacent teeth. 2. The electric motor according to claim 1, wherein the expansion and contraction portion comprises a plurality of slits formed in parallel on the inner and outer peripheral sides of the back yoke except for thin portions. Stator core. 3. A stator core for an electric motor according to claim 2, wherein the pair of side faces of the expansion and contraction section opposed to each other with the slit interposed therebetween are formed with projections and depressions engaging with each other.