JP3485887B2 - Brushless motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor, and more particularly to the structure of its stator.

[0002]

2. Description of the Related Art Conventionally, a rotor provided with magnets magnetized in multiple poles at equal intervals along the circumferential direction, and a number different from the number of poles of the rotor and arranged at unequal intervals along the circumferential direction. A brushless motor having a stator provided with teeth is proposed. This type of brushless motor 31
Is shown in FIG. The same one is disclosed in Japanese Patent Laid-Open No. 2000-
It is also disclosed in Japanese Patent No. 152581.

The brushless motor 31 shown in FIG. 11 includes a rotor 32 and a stator 33. The rotor 32 includes a shaft 34 and a magnet 35. The shaft 34 is a housing of the motor 31 (not shown)
It is designed to be rotatably supported by. Further, eight magnets 35 having a central angle of 45 ° and having N and S poles magnetized at equal intervals are fixed to the shaft 34. Therefore, the number of poles of the rotor 32 is “8”.

On the other hand, the stator 33 is an annular outer core 3
6, annular inner core 37 and U-phase, V-phase, W-phase coil 1
It is composed of 5U, 15V and 15W. On the outer peripheral side of the inner core 37, first to ninth teeth 37a to 37i arranged at unequal intervals are projected. Therefore, the number of poles of the stator 33 is “9”. These teeth 3
Windings are provided on the outer circumference of 7a to 37i.

A dovetail portion 41 is provided on the inner peripheral side of the outer core 36.
Are provided, and the teeth 37 a to 3 of the inner core 37 are
A dovetail portion 42 is provided at the tip of 7i.
When the outer core 36 and the inner core 37 are assembled,
The dovetail portions 41, 42 are adapted to engage with each other.

[0006]

However, when the teeth 37a to 37i are arranged at unequal intervals along the circumferential direction of the stator 33 as in the above-mentioned prior art, the dovetail portion 4 is formed.
Similarly, 1 and 42 are also arranged at unequal intervals along the circumferential direction. Therefore, when the outer core 36 is punched out by press working, the outer core 36 is likely to be deformed, and the outer core 36 cannot be manufactured accurately. Also,
Since the dovetail portions 41 of the outer core 36 are unevenly spaced, there is also a problem that the balance of the magnetism flowing from the inner core 37 to the outer core 36 is lost and the cogging torque becomes large.

The present invention has been made in view of the above problems, and an object thereof is to provide a brushless motor which can manufacture an outer core with high accuracy and has a good magnetic balance and which has low cogging.

[0008]

In order to solve the above-mentioned problems, in the invention as set forth in claim 1, a rotor provided with magnets magnetized in multiple poles at equal intervals along the circumferential direction, and the rotor. A stator having teeth that are different in number from the number of poles and are arranged at unequal intervals along the circumferential direction; and a coil wound around the teeth to generate a rotating magnetic field for rotating the rotor. And the stator is
It is composed of an annular outer core and an annular inner core in which a plurality of teeth connected to the inner peripheral side of the outer core are provided in a protruding manner, and a plurality of first engaging members are provided on the inner peripheral side of the outer core. The joining portion is provided, and the first end is provided at the tip of the tooth.
A brushless motor, characterized in that a second engaging portion that engages with the engaging portion is provided, and the first and second engaging portions are arranged at equal intervals along the circumferential direction of the stator. Is the gist.

According to a second aspect of the present invention, the rotor is provided with a magnet that is magnetized in multiple poles, and U-phase, V-phase, and W-phase coils that generate a rotating magnetic field for rotating the rotor are provided on the teeth. The number of poles P of the magnet and the number T of the teeth is P = 8n,
Further, it is configured so as to satisfy T = 9n (where n is an integer of 1 or more), and each of the teeth has three U-phase, V-phase, and W-phase.
The central angle θ1 between the central teeth assigned to each phase sequentially, and each central phase is θ1 = (120 ° / n), and the central angle θ2 of the teeth arranged on both sides with respect to the central tooth is (360 ° / T) <θ2 ≦ (360 ° /
In the brushless motor in which the position of each tooth is determined within the range of P), the stator has an annular outer core and an annular ring in which a plurality of teeth connected to the inner peripheral side of the outer core are projected. A plurality of first engaging portions provided on the inner peripheral side of the outer core, and second engaging portions that engage with the first engaging portions at the tip end portions of the teeth. A brushless motor is characterized in that a portion is provided, and the first and second engaging portions are arranged at equal intervals along the circumferential direction of the stator.

According to a third aspect of the present invention, in the first or second aspect, a straight line connecting the motor center and one side end of the first engaging portion, and the motor center and the other side end of the first engaging portion. The angle between the straight line connecting the motor center and the one end of the teeth and the straight line connecting the motor center and the other end of the teeth is θ4. , Θ3 <θ4, and (θ4−), where θ5 is the shift angle of the teeth that are displaced in the circumferential direction from the equidistant positions that should be originally disposed.
It is assumed that it is configured to satisfy the relationship of θ3) / 2 ≧ θ5.

According to a fourth aspect of the present invention, in the first aspect, the inner core is formed of the same plate material as the outer core by punching out a region that is inside the outer core, and the inner core is formed. Of the first tooth formed on the edge of the slot when the inter-teeth slot is punched out.
The second engaging portion of the inner core is engaged with the engaging portion.

The "action" of the present invention will be described below. According to the invention of claim 1, the first teeth are arranged in spite of being arranged at unequal intervals along the circumferential direction.
Further, the second engaging portions are arranged at equal intervals along the circumferential direction of the stator. Therefore, the outer core is less likely to be deformed during processing, and the outer core can be manufactured accurately. In addition, the balance state of the magnetism flowing from the inner core to the outer core is improved, and as a result, the increase of cogging torque is prevented. Further, since the teeth are arranged at unequal intervals along the circumferential direction, high output can be obtained without increasing the size of the motor.

According to the second aspect of the present invention, both the first and second engaging portions are provided with the peripheral portion of the stator, although the teeth are arranged at substantially non-uniform intervals along the peripheral direction. They are arranged at equal intervals along the direction. Therefore, the outer core is less likely to be deformed during processing, and the outer core can be manufactured accurately. In addition, the balance state of the magnetism flowing from the inner core to the outer core is improved, and as a result, the increase of cogging torque is prevented.

Further, according to the configuration of the present invention, the positional deviation between the center line of each tooth and the center of each pole of the magnet is reduced for each phase. In other words, the phase shift of the induced voltage of the coil wound around each tooth becomes small, and the combined induced voltage of the coils of each phase approaches the maximum value. That is, the conversion loss when converting the drive current supplied to each coil into a rotating magnetic field becomes small. Therefore, high output can be obtained without increasing the size of the motor.

According to the invention of claim 3, θ3, θ
If the relationship between 4 and θ5 is set as described above, the first and second
The position of the engaging portion can be set as a shift amount that does not deviate from the tip portion of the tooth.

According to the invention described in claim 4, as compared with the case where the inner core and the outer core are formed by punching different areas in the plate material, the material loss is surely reduced, and the plate material is effectively used. You can Therefore, the material cost can be reduced and the motor can be made inexpensive.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A brushless motor 11 according to an embodiment of the present invention will be described below with reference to FIG.
~ It demonstrates in detail based on FIG.

As shown in FIG. 1, the brushless motor 11 includes a rotor 12 and a stator 13. The stator 13 is configured by stacking a plurality of plates 24 and 25 obtained by punching the plate material 23 into the same shape. As shown in FIG. 5, in this embodiment, two different plates 24, 25 for forming the stator 13 are formed by punching different regions of one plate member 23 by press working.
Is getting The rotor 12 is composed of a shaft 14 and a magnet 16. The shaft 14 is rotatably supported by a housing (not shown) of the motor 11. Further, eight magnets 16 having a central angle of 45 ° and having N and S poles magnetized at equal intervals are fixed to the shaft 14. Therefore, the rotor 12
The number P of poles of the magnet 16 in is 8.

On the other hand, the stator 13 is an annular outer core 1
7 and an annular inner core 18. On the outer peripheral side of the inner core 18, first to ninth are arranged at unequal intervals.
Teeth 18a to 18i are provided in a protruding manner. That is, the number T of the teeth 18a to 18i is "9", and thus the number of poles of the stator 13 is "9". Windings are provided on the outer circumferences of these teeth 18a to 18i.
As a result, the U-phase, V-phase, and W-phase coils 15 are attached to the inner core 18.
U, 15V and 15W are formed.

Second, fifth and eighth teeth 18b, 18
e and 18h have a central angle of 120 ° and are arranged at equal intervals along the circumferential direction. First and third teeth 18
The a and 18c are arranged on both sides with the center angle of 42.5 ° about the second tooth 18b. The fourth and sixth teeth 18d and 18f have a central angle of 4 on both sides with the fifth tooth 18e as the center.
It is arranged to be at 2.5 °. The seventh and ninth teeth 18g and 18i are arranged on both sides with the central angle of 42.5 ° about the eighth tooth 18h.

That is, in this embodiment, when the center of the N pole of the magnet 16 is arranged on the center line of the second tooth 18b in FIG. 1, the first and third teeth 18a, 1
The center of the S pole of the magnet 16 is arranged close to the center line of 8c. This is the U-phase coil 1
Not limited to 5U, V phase coil 15V and W phase coil 15W
Is also the same.

The first to third teeth 18a to 18c are respectively provided with windings, whereby the U-phase coil 15 is formed.
First to third U-phase coils 15u1 to 15u3 forming U are formed. Windings are provided on the fourth to sixth teeth 18d to 18f, respectively, and the first to third V-phase coils 15v1 to 15v3 constituting the V-phase coil 15V are thereby formed.
Are formed. 7th-9th teeth 18g-18i
Each of the coils has a winding, and the first to third W-phase coils 15w1 to 1 that compose the W-phase coil 15W are thereby formed.
5w3 is formed. The first, third, fourth, sixth, seventh and ninth teeth 18a, 18c, 18d, 18
For f, 18g, and 18i, the windings are wound in the same direction. The remaining second, fifth and eighth teeth 18b,
Regarding 18e and 18h, windings are wound in the opposite direction to the above direction. Each phase coil 15U, 15V, 1
When forming 5 W, it is preferable that both windings having the same cross-sectional area are used and the number of windings is set to the same number.

Then, in this way, each tooth 18a-1
After the winding is applied to 8i, the inner core 18 and the outer core 17 are assembled, whereby the stator 13 is completed. The stator 13 thus configured is fixed to a housing (not shown) of the motor 11. The inner core 1
The configuration relating to the assembling of the outer core 8 and the outer core 17 will be described in detail later.

Brushless motor 1 configured as described above
1, the U-phase, V-phase, and W-phase exciting currents which are 120 ° out of phase with the exciting circuit (not shown) are coils 15 of each phase.
It is supplied to U, 15V and 15W. Then, the coils 15U, 15V, and 15W of the respective phases are excited to generate a rotating magnetic field in the stator 13, and the rotor 12 rotates based on the rotating magnetic field.

In this embodiment, when the center of the N pole of the magnet 16 is arranged on the center line of the second tooth 18b in FIG. 1, the center line of the first and third teeth 18a and 18c and the S pole of the magnet 16 are arranged. The centers of are almost in agreement. This is the first to third teeth 18a to 18c
The induced voltages V1 to V3 of the first to third U-phase coils 15u1 to 15u3 wound around
The phase shift of V3 is almost eliminated. That is, the entire curve of V3 drawn in the graph of FIG. 3 shifts slightly to the left in the figure. Further, the entire curve of V1 is slightly shifted to the right in the figure.

That is, when the plus side peak value of each induced voltage V1 to V3 is set to "1", each induced voltage V1 to V3
Induced voltage V0 of the entire U-phase coil 15U
Has a peak value on the plus side close to the maximum value "3" (see FIG. 4). Therefore, the motor 1 of this embodiment
In No. 1, the conversion loss when converting the drive current supplied to the coils 15U to 15W of each phase into the rotating magnetic field can be suppressed to be small. Incidentally, in the conventional motor, each induced voltage V1
Combined induced voltage V of the entire U-phase coil 15U composed of V3
0 means that the peak value on the plus side is at most "2.87".
It will be about 9 ".

Next, the above configuration will be applied to a general brushless motor. When the number of poles of the magnet is “P” and the number of teeth is “T”, P = 8n and T = 9n (where n is an integer of 1 or more) are satisfied. In such a brushless motor, first, "n" is arbitrarily set to determine the number P of poles of the magnet and the number of teeth.

Next, three teeth each are U phase → V phase → W.
Phase → U phase → V phase → W phase ... At this time, the central angle θ1 between the central teeth assigned to each phase is determined by the following equation.

Θ1 = (120 ° / n) Then, the position of the central tooth assigned to each phase is determined based on the obtained “θ1”.

Next, the central angle θ2 of the teeth arranged on both sides of the center tooth whose position has been determined is determined by the following equation. (360 ° / T) <θ2 ≦ (360 ° / P) Then, based on the obtained “θ2”, the positions of the teeth on both sides with respect to the center tooth are determined. At this time, as “θ2” becomes (360 ° / P), that is, the closer to the center angle of each pole of the magnet, the positional deviation between the center line of each tooth and the center of each pole of the magnet becomes smaller for each phase. In other words, the phase shift of the induced voltage of the coil wound around each tooth becomes small, and the combined induced voltage of the coils of each phase approaches the maximum value. That is, the conversion loss when converting the drive current supplied to each coil into a rotating magnetic field becomes small.

Further, if θ2 = (360 ° / P), then
The positional deviation between the center line of each tooth and the center of each pole of the magnet becomes extremely small for each phase, and the phase deviation of the induced voltage of the coil wound around each tooth becomes extremely small. Therefore, the combined induced voltage of the coils of each phase becomes closer to the maximum value, and the conversion loss when converting the drive current into the rotating magnetic field becomes extremely small.

Incidentally, in the brushless motor 11 of the above-described embodiment, as described above, n = 1 and the magnet 16 is used.
The number P of the poles is “8”, and the number T of the teeth 18a to 18i is “9”.

Next, three teeth 18a to 18i are assigned in the order of U phase → V phase → W phase, and the central teeth assigned to each phase, that is, the second, fifth, and eighth teeth 18 are assigned.
Since the central angle θ1 between b, 18e, and 18h is n = 1,
θ1 = 120 °, and the position is determined.

Next, the second, fifth and eighth positions are determined.
Teeth arranged on both sides of the teeth 18b, 18e, 18h, that is, the first, third, fourth, sixth, seventh, ninth teeth 18a, 18c, 18d, 18f, 18g,
The central angle θ2 of 18i is 40 ° due to P = 8 and T = 9.
<Θ2 ≦ 45 °. In the present embodiment, θ2 = 42.
Each tooth 18a, 18c, 18d, 18 as 5 °
The positions of f, 18g and 18i are determined.

The stator 13 of the brushless motor 11 of this embodiment further has the following characteristic structure.
As shown in FIGS. 1 and 2, on the inner peripheral side of the outer core 17 of the stator 13, the first plurality of first engaging portions are provided.
The dovetail portion 21 is recessed. In this embodiment,
The number of the first dovetail portions 21 is “18”. In other words, the number of the first dovetail portions 21 is equal to the number of teeth 1.
It is twice the number T of 8a to 18i (the number of poles of the stator 13).

On the other hand, as shown in FIGS. 1 and 3, at the tip portions of the teeth 18a to 18i of the inner core 18, the second dovetail portions as the second engaging portions which engage with the first dovetail portion 21 are formed. 22 are provided so as to project. In this embodiment,
The number of second dovetail portions 22 is “9”. In other words, the number of second dovetail portions 22 is equal to the number of teeth 18
It is equal to the number T of a to 18i (the number of poles of the stator 13). Due to such a number relationship, half of the first dovetail portions 21 are in a state in which the second dovetail portions 22 are engaged (so-called usage state), and the other half are unused. It is in a state.

The first dovetail portion 21 and the second dovetail portion 22 are arranged at equal intervals along the circumferential direction of the stator 13. Specifically, the first dovetail portion 21 is arranged so that the central angle is 360 ° / 18 = 20 °. The second dovetail portion 22 is arranged so that the central angle is 360 ° / 9 = 40 °.

Second, fifth and eighth teeth 18b, 18
In e and 18h, the 2nd dovetail part 22 projected and provided in the front-end | tip part is arrange | positioned on the teeth centerline.
In other words, these teeth 18b, 18e, 18h
The second dovetail portions 22 in are present at equidistant positions where they should be originally arranged, and are not arranged staggered along the circumferential direction.

On the other hand, the second, fifth and eighth teeth 18b,
Teeth other than 18e and 18h, that is, the first, third, fourth, sixth, seventh and ninth teeth 18a, 18c, 18
The situation is different for d, 18f, 18g, and 18i.

Here, for example, the second teeth 18b will be considered as a reference. An angle formed by a straight line connecting the motor center and one end of the first dovetail portion 21 and a straight line connecting the motor center and the other end of the first dovetail portion 21 is defined as θ3.

Further, the angle between the straight line connecting the center of the motor and the one end of the tip of a specific tooth (eg, 18a) and the straight line connecting the center of the motor and the other end of the tip of the tooth 18a is θ4. Define.

Further, the shift angle of the teeth 18a, which are displaced in the circumferential direction from the equidistant positions to be originally disposed, is defined as θ5. In this case, the above six teeth 18a, 18c, 18d, 18f, 18g, 18
It is preferable that i is configured so as to satisfy the relationship of θ3 <θ4 and (θ4−θ3) / 2 ≧ θ5. Specifically, in FIGS. 1 and 3, θ3 = 3 °, θ4 = 12 °, and θ5 = 2 ° are set to satisfy the above relational expressions. From the above relational expression, in this case, the offset angle θ5 is maximum (12 ° -3 °) / 2.
It is known in advance that = 4.5 ° can be set. In addition,
Needless to say, the second, fifth, and eighth teeth 18b, 18e, and 18h are set to θ5 = 0 °.

Therefore, according to this embodiment, the following effects can be obtained. (1) According to the stator 13 structure of the present embodiment, the teeth 18a to 18i are arranged at substantially unequal intervals along the circumferential direction. Nevertheless, both the first and second dovetail portions 21 and 22 are arranged at equal intervals along the circumferential direction of the stator 13. Therefore, the outer core 17 is less likely to be deformed at the time of processing due to the reason that the pressing pressure is evenly applied to the plate material 23 at the time of pressing.
Therefore, the outer core 17 can be accurately manufactured, and the non-defective product rate is surely improved. Moreover, with this configuration, the balance state of the flow of the magnetic flux flowing from the inner core 18 to the outer core 17 is improved. As a result, the increase in cogging torque can be reliably prevented, and the motor 1 with low vibration and high performance is provided.
1 can be realized.

(2) According to the structure of the stator 13 of this embodiment, P, T, θ1 and θ2 satisfy the above relational expression.
Each value of is set. Therefore, the positional deviation between the center lines of the teeth 18a to 18i and the centers of the poles of the magnet 16 is reduced for each phase. In other words, the phase shift of the induced voltage in the coils 15U to 15W wound around the teeth 18a to 18i becomes small, and the coils 15U to 15W in each phase.
The combined induced voltage of 15 W approaches the maximum value. That is, the conversion loss when converting the drive current supplied to each of the coils 15U to 15W into the rotating magnetic field becomes small. Therefore, high output can be obtained without increasing the size of the motor.

(3) According to the structure of the stator 13 of the present embodiment, the relationships of θ3, θ4 and θ5 are set so as to satisfy the above relational expression. Therefore, if designed according to this relational expression, the positions of the first and second dovetail portions 21 and 22 are set to the teeth 18a, 18c, 18d, 18f, 18g, 1
The deviation amount can be set so as not to deviate from the tip of 8i.
Therefore, the motor 11 can be designed and manufactured relatively easily. [Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIGS. Here, the points different from the first embodiment will be mainly described, and the common points will be denoted by the same member numbers and description thereof will be omitted.

In this embodiment, the stator 13 is manufactured by a procedure different from that of the first embodiment. First, one metal plate material (electromagnetic steel sheet) 23 is prepared, and a hole which will later become the center hole 26 in the inner core 18 is punched and formed in the center portion thereof (see FIG. 6). For convenience, in FIGS. 6 to 9, the portions to be punched are shown with diagonal lines.

Next, a plurality of inter-teeth slots 27 are punched out so as to surround the center hole 26 (see FIG. 7). At the same time, a portion that will later become the first dovetail portion 21 is formed on the outer edge portion of the inter-teeth slot 27.

Next, the region inside the outer core 17 is punched out to form the plate 24 which is a constituent member of the inner core 18 (see FIG. 8). At this time, the 2nd dovetail part 22 is formed in the tip part of teeth 18a-18i. The concave portions (dummy first dovetail portions) 25 and the first dovetail portions 21 formed on the plate member 23 side due to the formation of the second dovetail portions 22 are alternately arranged at equal intervals along the circumferential direction. In addition, in order to realize a secure engagement with the second dovetail portion 22, the first
The dovetail portion 21 is formed to be slightly smaller than the recess 25.

Next, the plate 25, which is a constituent material of the outer core 17, is punched and formed (see FIG. 9). It should be noted that a plurality of each of the two types of plates 24 and 25 as described above is prepared and laminated.

After winding the teeth 18a to 18i of the inner core 18 obtained by stacking, the second dovetail portion 22 of the inner core 18 is engaged with the first dovetail portion 21 of the outer core 17. Then, the stator 13 is completed (see FIG. 10). At this time, the inner core 18 is rotated by a predetermined angle, that is, an odd multiple of (360 ° / 18) from the position where the inner core 18 is actually punched.

Therefore, according to this embodiment, as compared with the case where the inner core 18 and the outer core 17 are formed by punching different areas in the plate member 23 as in the first embodiment, the material loss is surely reduced. be able to. Therefore, the plate material 23 can be effectively used. Therefore, the material cost can be reduced, and the inexpensive motor 11 can be obtained.

The embodiment of the present invention may be modified as follows. * Dovetail parts 21 and 22 which are the 1st and 2nd engaging parts
The shape of is not limited to those of the first and second embodiments, and the shapes can be arbitrarily changed as long as they can be engaged with each other.

Instead of projecting the first engaging portion on the outer core 17 side, the second engaging portion may be recessed on the inner core 18 side. The number of poles P of the magnet 16 is set to a number other than "8" (for example, 16, 24, etc.), or the teeth 18a to 18i.
Of course, the number T of may be a number other than "9" (for example, 18, 27, etc.).

In the above embodiment, each tooth 18a
Coils 18u1 to 15u3, 15v1 to 1 wound around ~ 18i
5v3, 15w1 to 15w3 were constructed using windings of the same cross-sectional area and the same number of turns. Instead of this,
The number of turns of the coils 15u2, 15v2, 15w2 wound around the teeth 18b, 18e, 18h at the center of each phase may be increased. With this configuration, the coils 15u2 and 15v
Since the induced voltage of 2, 15w2 increases, the combined induced voltage of the coils 15U, 15V, 15W of each phase can be increased. Therefore, the output of the motor 11 can be further increased.

・ Center teeth 18 b, 18 of each phase
The cross-sectional area of the windings of the coils 15u2, 15v2, 15w2 wound around e and 18h may be increased. According to this structure, the winding resistance of the coils 15u2, 15v2, 15w2 becomes small, so that the power consumption of the motor 11 can be reduced.

Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments will be listed below. (1) A stator having teeth arranged at unequal intervals along a circumferential direction, wherein an annular outer core and a plurality of teeth connected to an inner peripheral side of the outer core are provided in a protruding manner. A plurality of first engaging portions provided on the inner peripheral side of the outer core, and a second end engaging with the first engaging portion at the tip end portion of the tooth. A stator of a brushless motor, wherein engaging portions are provided, and the first and second engaging portions are arranged at equal intervals along the circumferential direction. Therefore, this technical idea 1
According to the invention described in (1), the outer core can be manufactured with high accuracy, and the magnetic balance is good, which is suitable for manufacturing a brushless motor with low cogging.

(2) An inner core structure having a plurality of teeth which are connected to the inner peripheral side of an annular outer core and are arranged at unequal intervals along the circumferential direction. Is an inner core structure for a stator for a brushless motor, wherein engaging portions that can be engaged with the outer core side engaging portions are arranged at equal intervals along the core circumferential direction. Therefore, according to the invention described in the technical idea 2, since the magnetic balance is good, the invention is suitable for manufacturing a brushless motor with low cogging.

[0058]

As described above in detail, according to the inventions described in claims 1 to 4, the outer core can be manufactured with high accuracy, and the magnetic balance is good, so that the brushless motor with low cogging can be provided. .

According to the invention described in claim 3, the motor can be easily manufactured. According to the invention described in claim 4, an inexpensive motor can be provided.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a brushless motor according to a first embodiment that embodies the present invention.

FIG. 2A is a front view of an outer core of the stator of the first embodiment, and FIG. 2B is a front view of an inner core of the stator.

FIG. 3 is a diagram for explaining an induced voltage in a U-phase coil.

FIG. 4 is a diagram for explaining a combined induced voltage of a U-phase coil.

FIG. 5 is a view for explaining the manufacturing procedure of the stator.

FIG. 6 is a view for explaining the manufacturing procedure of the stator.

FIG. 7 is a view for explaining the manufacturing procedure of the stator.

FIG. 8 is a view for explaining the manufacturing procedure of the stator.

FIG. 9 is a view for explaining the manufacturing procedure of the stator.

FIG. 10 is a view for explaining the manufacturing procedure of the stator.

FIG. 11 is a schematic configuration diagram of a conventional brushless motor.

[Explanation of symbols]

11 ... Brushless motor, 12 ... Rotor, 13 ... Stator, 15U, 15V, 15W ... U phase, V phase, W phase coil, 16 ... Magnet, 17 ... Outer core, 18 ... Inner core,
18a-18i ... Teeth, 21 ... 1st dovetail part as a 1st engaging part, 22 ... 2nd dovetail part as a 2nd engaging part, 23 ... Plate material, 27 ... Slot between teeth, (theta),
1 ... central angle between central teeth, θ2 ... central angle of teeth arranged on both sides, θ3 ... angle, θ4 ... angle, θ5 ... angle.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuhiko Matsushita 390 Umeda, Kosai City, Shizuoka Prefecture Asumo Corporation (56) References JP2000-152581 (JP, A) JP2000-350391 (JP, A) ) JP-A-2-254947 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02K 1/18 H02K 1/06 H02K 29/00 H02K 1/16

Claims (4)

(57) [Claims] 1. A rotor comprising magnets magnetized in multiple poles at equal intervals along the circumferential direction, and a number different from the number of poles of the rotor and arranged at unequal intervals along the circumferential direction. A stator having teeth, and a coil wound around the teeth to generate a rotating magnetic field for rotating the rotor, the stator having an annular outer core, and an inner circumference of the outer core. A plurality of teeth connected to the side, and a plurality of first engaging portions are provided on the inner peripheral side of the outer core, and a plurality of teeth are provided at the tip end portions of the teeth. Is provided with a second engagement portion that engages with the first engagement portion, and both the first and second engagement portions are arranged at equal intervals along the circumferential direction of the stator. And brushless motor. 2. A rotor having a multi-pole magnetized magnet, and a stator having U-phase, V-phase, and W-phase coils provided on the teeth for generating a rotating magnetic field for rotating the rotor. , The number of poles P of the magnet and the number T of teeth are configured such that P = 8n and T = 9n (where n is an integer of 1 or more) The U-phase, V-phase, and W-phase are sequentially assigned, and the central angle θ between the central teeth assigned to each phase
1 is θ1 = (120 ° / n), and the central angle θ2 of the teeth arranged on both sides with respect to the central tooth is within the range of (360 ° / T) <θ2 ≦ (360 ° / P) As a brushless motor in which the position of each tooth is determined, the stator includes an annular outer core and an annular inner core provided with a plurality of teeth connected to the inner peripheral side of the outer core. A plurality of first engaging portions are provided on an inner peripheral side of the outer core, and a second engaging portion that engages with the first engaging portion is provided at a tip end portion of the tooth, The brushless motor according to claim 1, wherein the first and second engaging portions are arranged at equal intervals along the circumferential direction of the stator. 3. An angle formed by a straight line connecting the center of the motor and one end of the first engaging portion and a straight line connecting the center of the motor and the other end of the first engaging portion is θ3, and the center of the motor and The angle formed by the straight line connecting the one end of the tooth tip and the straight line connecting the center of the motor and the other end of the tooth is θ4, and is displaced in the circumferential direction from the equidistant position where it should be originally placed. When the shift angle of the teeth arranged in a row is θ5, θ3 <θ4 and (θ4−θ3) / 2 ≧ θ5 are satisfied. Brushless motor described. 4. The inner core is formed of the same plate material as that of the outer core by punching out a region inside the outer core, and the slot between the teeth of the inner core is punched out. The brushless motor according to claim 1, wherein the second engaging portion of the inner core is engaged with the first engaging portion formed on the edge portion of the.