JP7313239B2 - Stator of inner rotor type motor - Google Patents

Description

The present invention relates to a stator for an inner rotor type motor.

2. Description of the Related Art Some stator cores of inner rotor type motors employ so-called split cores that are divided in advance in the circumferential direction (see, for example, Patent Document 1). A coil bobbin around which a coil is wound is attached to the tooth portion of the split core, and then the split cores are joined together to manufacture the stator core.

JP 2017-022971 A

On the other hand, instead of split cores as described above, cores that are integrally formed without being split in the circumferential direction are known. In such a case, the work of inserting the coil bobbin into the tooth portion becomes complicated, and the assembly process may become complicated.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a stator for an inner rotor type motor that can be easily assembled.

The above object is provided with a stator core including first and second coil bobbins around which first and second coils are respectively wound, an annular portion, a first tooth portion protruding from the inside of the annular portion in a predetermined direction and into which the first coil bobbin is inserted, and a second tooth portion protruding from the inside of the annular portion in a direction opposite to the predetermined direction and facing the first tooth portion and into which the second coil bobbin is inserted, wherein the stator core is divided in the circumferential direction. The first tooth portion has a first tip surface, the second tooth portion has a second tip surface facing the first tip surface, the shortest distance between the first tip surface and the second tip surface in the predetermined direction is X1, the shortest length of each of the first and second teeth portions in the predetermined direction is X2, and the inner diameter of the annular portion is DO, where DO>X1≧X2 is established. It can be achieved by the stator of a rotor-type motor.

It is possible to provide a stator for an inner rotor type motor whose assembly is simplified.

FIG. 1 is an external perspective view of the stator of this embodiment. FIG. 2 is an exploded perspective view of the stator of this embodiment. FIG. 3 is an external view of the stator core viewed from the Z direction.

FIG. 1 is an external perspective view of a stator 1 of this embodiment, and FIG. 2 is an exploded perspective view of the stator 1 of this embodiment. A stator 1 is employed in an inner rotor type motor. The stator 1 includes a stator core 10, two coil bobbins 20, two holders 30, and two coils C. A rotor (not shown) magnetized with different polarities in the circumferential direction is rotatably arranged in the stator core 10 . By controlling the energization of the two coils C, a magnetic attraction force and a magnetic repulsion force are generated between the stator core 10 and the rotor, thereby rotating the rotor. 1 and 2 show an X direction, a Y direction, and a Z direction that are orthogonal to each other. The two coil bobbins 20 are arranged side by side in the X direction, and the two holders 30 are arranged side by side in the Y direction. Moreover, the central axis of the stator core 10 is parallel to the Z direction. The center axis of this stator core 10 coincides with the rotation axis of the rotor (not shown).

The stator core 10 is made of metal and includes an annular portion 12 and two tooth portions 14 as shown in FIG. The two tooth portions 14 protrude from the inside of the annular portion 12 toward the center of the annular portion 12 and are arranged in the X direction. The YZ plane cross section of the tooth portion 14 is substantially rectangular. Tip surfaces of the tooth portions 14 are curved in an arc around the center of the stator core 10 . It faces a rotor (not shown). The stator core 10 is not composed of so-called divided stator cores divided in the circumferential direction, but integrally molded in the circumferential direction. Specifically, the stator core 10 is formed by laminating a plurality of plate-shaped metal members such as soft magnetic steel plates such as silicon steel plates and electromagnetic steel plates in the Z direction. Moreover, the thing integrally molded by metal members, such as soft magnetic powder, may be used.

The coil bobbin 20 is made of insulating synthetic resin and includes a cylindrical portion 22, an outer flange portion 24, and an inner flange portion 26 as shown in FIG. The tubular portion 22 extends in the X direction, and has an outer flange portion 24 formed at one end and an inner flange portion 26 formed at the other end. The coil C is wound around the outer peripheral portion of the tubular portion 22 between the outer flange portion 24 and the inner flange portion 26 . The inner flange portion 26 is formed larger than the outer flange portion 24, but is not limited to this, and may have the same size.

Cylindrical portion 22 defines a hole 23 into which tooth portion 14 of stator core 10 is inserted. Coil bobbin 20 is assembled to stator core 10 by inserting tooth portions 14 of stator core 10 into holes 23 such that inner flange portion 26 is located closer to the center of stator core 10 than outer flange portion 24 . Therefore, as shown in FIG. 1, the two coil bobbins 20 are assembled to the stator core 10 so that the inner flange portions 26 of the two coil bobbins 20 face each other. Here, the inner diameter of the hole 23 and the outer diameter of the tooth portion 14 are substantially the same in size and shape, and the tooth portion 14 can be easily inserted into the hole 23 without the need of press-fitting. Therefore, the coil bobbin 20 can be easily assembled to the stator core 10, simplifying the assembly process. Note that the phrase "no need to press-fit" means that when the tooth portion 14 is inserted into the hole 23, the hole 23 is not elastically deformed so as to expand.

Here, the direction in which the two coil bobbins 20 are inserted into one of the tooth portions 14 is the +X direction, and the direction in which they are inserted into the other tooth portion 14 is the -X direction. Therefore, the extraction direction from one tooth portion 14 of the two coil bobbins 20 is the -X direction, and the extraction direction from the other tooth portion 14 is the +X direction. In other words, these withdrawal directions are also the direction in which the tooth portions 14 extend and the direction toward the center of the stator core 10 .

The holder 30 is made of an insulating synthetic resin, and includes a covering portion 32, a collar portion 34, and a restricting protrusion 36 as shown in FIG. The covering portion 32 has substantially the same height as the stator core 10 in the Z direction, and is curved in an arc with substantially the same curvature as the inner surface of the annular portion 12 of the stator core 10 . The restricting protrusion 36 has substantially the same height in the Z direction as the covering portion 32 and protrudes from the inner side of the covering portion 32 . The holders 30 are assembled to one side (+Y direction side) and the other side (−Y direction side) of the annular portion 12 defined by the two tooth portions 14 of the stator core 10, respectively. Specifically, the holder 30 is assembled to the stator core 10 such that the covering portion 32 is positioned inside the annular portion 12 between the two teeth portions 14, the collar portion 34 contacts the upper surface of the annular portion 12 of the stator core 10, and the restricting protrusions 36 protrude toward the center of the stator core 10. The position of the holder 30 in the Z direction with respect to the stator core 10 is defined by the contact of the collar portion 34 with the upper surface of the annular portion 12 . The two holders 30 are assembled to the stator core 10 after the two coil bobbins 20 around which the coils C are wound in advance are assembled to the stator core 10 .

As shown in FIG. 1 , the restricting protrusions 36 are in contact with the inner flange portions 26 of the two coil bobbins 20 respectively inserted into the two teeth portions 14 . That is, the restricting protrusion 36 of the holder 30 protrudes between the two coil bobbins 20 and restricts the movement of the two coil bobbins 20 in the removal direction described above. This prevents the coil bobbin 20 from coming off the tooth portion 14 .

Moreover, the covering portion 32 covers the inside of the annular portion 12 of the stator core 10 . Therefore, the coil C is prevented from contacting the inside of the annular portion 12 of the stator core 10, and the insulation between the stator core 10 and the coil C is ensured. Further, the coil C is in contact with the covering portion 32, and the coil C has a large wire diameter, thereby securing the torque of the rotor. Even if the coil C has a small wire diameter, it is possible to secure the torque of the rotor by securing ampere-turns by securing a large number of turns to the extent that the coil C contacts the covering portion 32 .

Further, since the holder 30 restricts the movement of the two coil bobbins 20 in the removal direction, the circumferential movement of the holder 30 with respect to the annular portion 12 of the stator core 10 is restricted. This also prevents the holder 30 from rattling.

In addition, since the two holders 30 are assembled to the stator core 10 so as to separate the two coil bobbins 20 from each other, the two coil bobbins 20 and the two holders 30 are stably assembled to the stator core 10, and rattling of these members is prevented.

In this embodiment, the two holders 30 are not limited to preventing the two coil bobbins 20 from falling off. For example, only one holder 30 can prevent the two coil bobbins 20 from falling off. Also, the two holders 30 may be integrally formed in advance. For example, the collar portions 34 of the two holders 30 may be formed continuously so as to circulate on the upper surface of the stator core 10 .

In this embodiment, the Z-direction length of the covering portion 32 of the holder 30 is not limited to substantially the same as the Z-direction length of the annular portion 12, and may be shorter than the Z-direction length of the annular portion 12. However, from the viewpoint of avoiding contact between the coil C and the stator core 10, it is preferably substantially the same as the Z-direction length of the annular portion 12 or longer than the annular portion 12.

FIG. 3 is an external view of the stator core 10 viewed from the Z direction. In FIG. 3 , reference numerals are given to tip end surfaces 16 of teeth 14 and central axis A of stator core 10 is indicated. The tip surfaces 16 of the two teeth 14 face each other. Moreover, each of the two tip surfaces 16 is formed in an arc shape centering on the center axis A when viewed from the Z direction. X1 is the shortest distance between the tip surfaces 16 in the +X direction in which one of the two tooth portions 14 extends from the annular portion 12 . In other words, X1 is the shortest distance between the end of one tip surface 16 and the end of the other tip surface 16 . X2 is the shortest length of each of the two teeth portions 14 in the +X direction. In other words, X2 is the shortest distance from the root portion of the tooth portion 14 that is continuous with the inner surface of the annular portion 12 to the center of the tip surface 16 that is formed in an arc shape. DO is the inner diameter of the annular portion 12 . Here, DO>X1≧X2 is established. DO>X1 is a condition that the tooth portion 14 extends from the inner side of the annular portion 12 . X1≧X2 is a condition that makes it easy to insert the coil bobbin 20 into one tooth portion 14 from between the tip surfaces 16 .

In this embodiment, X1=X2 is set. As a result, the coil bobbin 20 can be easily inserted into the tooth portion 14, and the space occupied by the coil C wound around the coil bobbin 20 inserted into the tooth portion 14 inside the annular portion 12 is ensured. Since the space occupied by the coil C is secured, it is also possible to increase the number of turns of the coil C and adopt a coil with a large wire diameter. As a result, both the easiness of assembly of the coil bobbin 20 to the stator core 10 and the improvement of the output of the rotor can be achieved.

Furthermore, in this embodiment, 0.15×DO≦X1=X2≦0.3×DO is established. As long as X1 and X2 satisfy this range, more magnetic flux of the rotor magnet can be taken into the stator core 10 and the space occupied by the coil C can be secured. Therefore, the output of the rotor is further improved.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and modifications and changes can be made within the scope of the gist of the present invention described in the claims.

The relationship between X1, X2, and DO is not limited to the case described above, and may be 0.15×DO≦X2≦X1≦0.3×DO. In this case, the coil bobbin 20 can be easily inserted into the tooth portion 14 and more of the magnetic flux of the rotor magnet can be taken into the stator core 10 .

The tip surface 16 has an arc shape centered on the central axis A, but is not limited to this. For example, the tip surface may have an arc shape centered on a point other than the central axis A, an elliptical arc shape, a curved surface shape in which the distance from the outer peripheral surface of the rotor varies depending on the position, or a planar shape.

Although the holder 30 is made of synthetic resin in the above embodiment, it may be made of rubber having a certain degree of rigidity. Moreover, the holder 30 may be made of a non-insulating metal as long as the coil C does not come into contact with it.

REFERENCE SIGNS LIST 1 stator 10 stator core 12 annular portion 14 tooth portion 20 coil bobbin 23 hole 30 holder 32 covering portion 34 collar portion 36 restricting protrusion C coil

Claims (2)

first and second coil bobbins around which the first and second coils are respectively wound;
a stator core including: an annular portion; a first tooth portion protruding from the inside of the annular portion in a predetermined direction and into which the first coil bobbin is inserted;
first and second holders that restrict movement of the first coil bobbin from the first tooth portion in the removal direction and restrict movement of the second coil bobbin from the second tooth portion in the removal direction;
The stator core is integrally formed without being divided in the circumferential direction,
The stator core is provided with no tooth portions other than the first and second tooth portions,
The first and second coil bobbins are arranged side by side in the predetermined direction,
The first and second holders are arranged side by side in a direction orthogonal to the center axis of the stator core and the predetermined direction,
The first holder is assembled inside the annular portion between the first tooth portion and the second tooth portion,
The second holder is assembled inside the annular portion between the first tooth portion and the second tooth portion on the opposite side of the first holder,
The first tooth portion has a first tip surface,
The second tooth portion has a second tip surface facing the first tip surface,
X1 is the shortest distance between the first tip surface and the second tip surface in the predetermined direction,
X2 is the shortest length of each of the first and second teeth in the predetermined direction,
Assuming that the inner diameter of the annular portion is DO,
DO>X1≧X2 holds,
A stator for an inner-rotor motor that satisfies 0.15×DO≦X2≦X1≦0.3×DO . 2. The stator of an inner rotor type motor according to claim 1 , wherein X1=X2.

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