JP2003088007A - Core sheet, stator, and rotating field type motor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a core sheet, a stator using the core sheet, and an inner rotor type rotating field type motor using the stator which can reduce cogging torque effectively and suppress the reduction of effective fluxes. SOLUTION: This plate-shaped core sheet 31 has a ring, a plurality of iron cores 34 protruding radially inward from the inner circumferential surface of the ring, and bridging parts 35 which connect the radially inside ends of the plurality of iron cores 34 with each other. Each bridging part 35 has a thin part 35a with a thickness thinner than the thickness of the core sheet 31 and, if the thickness of the core sheet 31 is denoted by t and the thickness of the thin part 35a is denoted by T, the inequalities 0.2t<=T<t are satisfied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core sheet, a stator, and a rotating magnetic field type electric motor using the stator, and more particularly, to a core sheet in which inner ends of iron cores to which windings are applied are connected. The present invention relates to a stator using a core sheet and a rotating magnetic field type electric motor using the stator.

[0002]

2. Description of the Related Art Conventionally, in a brushless motor 1 which is a rotating magnetic field type electric motor as shown in FIG. 9, a plurality of T-shaped iron core portions 34 formed on a stator 30 are provided with windings 33, and the windings 33 are provided. A rotor 20 rotatably supported inside the stator 30 is rotated by passing an electric current through 33 to generate a rotating magnetic field.

The rotor 20 comprises a magnet 21, a back yoke 22 and a shaft 23. The shaft 23 is inserted into and attached to a cylindrical back yoke 22, and a plurality of magnets 21 are arranged on the outer periphery of the back yoke 22 so that adjacent magnets have different magnetic poles. Further, the stator 30 is formed by laminating core sheets 31 made of a thin magnetic material such as a silicon steel plate, and in order to prevent power loss and heat generation due to eddy current, the core sheet 3 is formed.
The surface of 1 is subjected to an insulation treatment such as an insulation film.

As shown in FIG. 10, a core sheet 31 used in the brushless motor 1 of FIG. 9 is formed with T-shaped iron core portions 34 radially protruding from the inner side in the radial direction of the outer annular portion. There is. Slots 32 are formed between adjacent iron core portions 34, and slot openings 32a are formed inside the slots 32 in the radial direction.

The brushless motor 1 using the core sheet 31 having the slot openings 32a has a core sheet having no slot openings 32a because the inner ends of the adjacent iron core portions 34 are connected to each other. In comparison with the brushless motor used, since there is no leakage magnetic flux due to the magnetic flux flowing between the inner end portions of the adjacent iron core portions 34 during operation, the effective magnetic flux flowing through the iron core portion 34 is not reduced. The efficient brushless motor 1 can be manufactured.

Further, such a core sheet 31 can be easily formed by pressing a thin metal plate.

[0007]

However, in the brushless motor 1 having the stator 30 having the slot openings 32a as described above, the stator 30 and the rotor 2 are not provided.
There is a problem that a change in torque due to a magnetic attraction force generated during 0 is large with respect to a rotation angle, that is, a so-called cogging torque is large. This cogging torque has been a cause of generation of vibration and noise during operation of the brushless motor 1.

An object of the present invention is to effectively reduce the cogging torque and suppress the reduction of the effective magnetic flux in the inner rotor type rotating field type electric motor by eliminating the slot opening of the stator. (EN) Provided are a core sheet, a stator using the core sheet, and a rotating field type electric motor.

[0009]

According to the core sheet as set forth in claim 1, the above-mentioned problem is provided in the annular portion and the inner peripheral surface of the annular portion radially protruding inward in the radial direction. A plurality of iron core portions, and a bridging portion connecting the radially inner ends of the plurality of iron core portions to each other, a plate-shaped core sheet, wherein the bridging portion is, When the thickness of the core sheet is t and the thickness of the thin portion is T, the thickness T of the thin portion is 0. .2t ≦ T <t is solved.

Since the plate thickness T of the thin portion of the bridging portion is formed thinner than the other portions of the core sheet, the cogging torque can be suppressed small and the leakage magnetic flux can be reduced, so that the effective magnetic flux can be reduced. Is expected to be suppressed.
And, more specifically, as shown in the embodiment, 0.2t
When ≦ T <t, the cogging torque is reduced by 60% or more as compared with the case of T = 0, which is preferable.

Further, as described in claim 2, since the plate thickness T of the thin portion is 0.2t≤T≤0.5t, the effective magnetic flux is reduced while the cogging torque is suppressed small. It is expected to be further suppressed. Then, more specifically, as shown in the embodiment, 0.2t ≦ T ≦ 0.
5t is preferable because the cogging torque is reduced by 60% or more as compared with the case of T = 0, and the effective magnetic flux is increased by 10% or more as compared with the case of T = 1.

[0012] According to the stator of claim 3, the above-mentioned problem is obtained by laminating a plurality of plate-shaped core sheets.
A stator including windings, wherein the core sheet includes an annular portion, a plurality of iron core portions provided on an inner peripheral surface of the annular portion so as to protrude radially inward, A bridging portion connecting the radially inner ends of the plurality of iron core portions to each other, the bridging portion having a thin portion formed to be thinner than the plate thickness t of the core sheet, When the thickness of the core sheet is t and the thickness of the thin portion is T, the thickness T of the thin portion is T
Is solved by 0.2t ≦ T <t.

The thickness T of the thin portion of the bridge portion of the core sheet is
Since the core sheet is formed thinner than the other parts, the cross-sectional area of the bridging portion of the stator in which the core sheets are laminated is smaller than that of the other parts. Therefore, the magnetic resistance in the bridge portion is increased, the cogging torque is suppressed to be small, and the leakage magnetic flux is reduced, so that the reduction of the effective magnetic flux can also be suppressed, and an efficient electric motor is expected to be constructed. To be done.

Further, as described in claim 4, since the plate thickness T of the thin portion is 0.2t≤T≤0.5t, the effective magnetic flux is reduced while the cogging torque is suppressed small. Since it can be further suppressed, it is expected that a more efficient electric motor will be constructed.

Further, as described in claim 5, since the windings are wound around the iron core portions separated from each other, the winding method for the stator can be selected according to the application. Become. Further, since the plate thickness T of the thin portion is 0.2 t or more, the iron core portion is less likely to bend even when the separated iron core portions receive a force in a direction in which the iron core portions are pulled by each other during winding. The stator is suitable because it does not deform.

Further, as described in claim 6, since the winding is formed in a rectangular shape in cross section, the plurality of electric wires inserted into the respective slots can be arranged in the slot without any gap therebetween. This enables the conductor occupancy in the slot to be improved.

Further, according to the rotating magnetic field type electric motor of claim 7, since the cogging torque and the leakage magnetic flux can be suppressed to be low by using any one of the stators, the rotating magnetic field type motor having a high efficiency can be achieved. It becomes possible to obtain a model electric motor. In addition, the winding method can be selected, and the occupation ratio of the winding in the slot can be increased.
It is possible to reduce the size and increase the output.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings, taking a brushless motor 1 as an example. The same elements as those of the conventional example will be described with the same reference numerals. Further, the arrangement, shape, etc. described below are not intended to limit the present invention, and it goes without saying that various modifications can be made in accordance with the spirit of the present invention.

FIG. 1 is a sectional view of the brushless motor of the embodiment, FIG. 2 is a sectional view of the stator and rotor of FIG. 1, FIG. 3 is a partially enlarged view of the core sheet of the embodiment, and FIG. 4 is of the brushless motor of FIG. FIG. 5 is a graph showing the relationship between the bridging portion thickness and the effective magnetic flux and cogging torque, FIG. 5 is a development view showing the winding state of the one-phase winding used in the brushless motor of FIG. 1, and FIG. FIG. 7 is a perspective view of a pine needle-shaped wire portion of another embodiment, and FIG. 8 is a sectional view of a stator and a rotor of another embodiment.

The structure of a brushless motor 1 according to an embodiment of the present invention will be described with reference to FIG. Brushless motor 1
Is a rotor 2 rotatably supported by bearings 41, 42.
0, a stator 30 having three-phase windings 33, a rotor housing 20 and a yoke housing 40 housing the stator 30
With.

The stator 30 has a three-phase winding 33.
In addition, a rotating magnetic field for rotating the rotor 20 is generated by a current flowing from an external power supply device (not shown).

Although not shown in the drawings, the brushless motor 1 is provided with a well-known position detector composed of a hall element, a rectifying element, a position detecting magnet and the like, and a control circuit, and the rotor 20 is provided by these. The position is detected during rotation. A desired pulse current is applied to the winding 33 from the control circuit based on the signal obtained by the position detection and the speed setting value, so that the rotor 20 can rotate stably.

FIG. 2 shows a sectional view of the rotor 20 and the stator 30. The rotor 20 has a structure in which a shaft 23 is attached to a cylindrical back yoke 22 and a plurality of magnets 21 having different magnetic poles are arranged adjacent to each other on the outer circumference of the back yoke 22.

The stator 30 is formed by coaxially stacking a plurality of core sheets 31. These core sheets 31 are made of a thin magnetic material such as a silicon steel plate whose surface is provided with an insulating film (not shown). The core sheet 31 includes a ring-shaped outer ring portion, a plurality of T-shaped iron core portions 34 radially formed inward from the outer ring portion, and inner end portions of adjacent iron core portions 34. And a bridge portion 35 that connects the two.

As shown in FIG. 3, the bridging portion 35 has a thin portion 35a which is thinner than other portions of the core sheet 31 including the iron core portion 34 and the like. That is, the thin portion 35
The a is formed in a flat plate shape having a predetermined step with respect to one surface in the thickness direction of the adjacent iron core portions 34. The core sheet 31 as described above is formed into a predetermined shape by pressing or the like.

Since the stator 30 is formed by laminating the core sheets 31 as described above, the portion of the stator 30 corresponding to the bridging portion 35 is intermittently thinned in the axial direction. Has become. Therefore, the substantial thickness of this portion is smaller than the substantial thickness of other portions of the stator 30.

Since the magnetic resistance is inversely proportional to the size of the effective sectional area of the magnetic path through which the magnetic flux flows, the bridging portion 3 of the stator 30 is used.
The magnetic resistance of the portion corresponding to 5 is larger than that of the other portions. Therefore, it is possible to reduce the leakage magnetic flux leaking to the bridging portion 35 during the operation of the brushless motor 1, and it is possible to suppress the reduction of the effective magnetic flux flowing in the iron core portion 34.

Next, FIG. 4 shows the results of FEM analysis of the relationship between the wall thickness of the thin portion 35a of the bridging portion 35 and the effective magnetic flux and cogging torque in the brushless motor 1. Figure 4
In, the change of the effective magnetic flux is shown by the solid line, and the change of the cogging torque is shown by the broken line.

In this figure, both the effective magnetic flux and the cogging torque are represented by relative values with respect to the brushless motor 1 having no bridging portion 35 shown in FIG. Also,
The thickness of the bridging portion is the core sheet 3 other than the thin portion 35a.
It is a relative value when the thickness of 1 is 1. That is, when the bridging portion thickness is “0” (corresponding to the brushless motor 1 in FIG. 9), both the effective magnetic flux and the cogging torque are “1”.

As is apparent from FIG. 4, the effective magnetic flux decreases in inverse proportion to the thickness of the bridging portion. For example, when the bridging portion thickness is “1”, that is, when the bridging portion thickness is the same as the other portions of the core sheet 31, the effective magnetic flux is about 20% as compared with the case where the bridging portion thickness is “0”. Reduce.

On the other hand, the cogging torque has a bridge thickness of 0.
In the range from about 0.2 to about 0.2, the thickness decreases sharply in inverse proportion to the thickness of the bridge portion, and the thickness of the bridge portion is 0.2, which is reduced by 60% or more. Specifically, 75% at a bridge thickness of about 0.25
The degree is reduced. And, when the bridging portion thickness is in the range of about 0.25 to 1.0, no remarkable reduction is observed, and it is reduced by about 80%.

From the above analysis, the brushless motor 1 shown in FIG.
The bridging portion thickness T of the thin portion 35a of the core sheet 31 used for
It can be seen that the cogging torque is effectively reduced when it is set in the range of 0.2t to 1.0t.

In order to suppress the reduction of the effective magnetic flux and the reduction effect of the cogging torque, the bridging portion thickness T of the thin portion 35a is set in the range of 0.2t to 0.5t. It is more suitable. That is, the cogging torque is 80 when the bridging portion thickness T of the thin portion 35a is 0.5t.
%, But it is almost the same as when the bridging portion thickness T of the thin portion 35a is 1.0t, while on the other hand, when the bridging portion thickness T of the thin portion 35a is 0.5t. The reduction of the effective magnetic flux is about 10%, and the reduction of the effective magnetic flux can be suppressed to half as compared with the case where the bridging portion thickness T of the thin portion 35a is 1.0t.

Next, the winding 33 of the brushless motor 1 will be described. As shown in FIG. 2, the brushless motor 1 constitutes a winding 33 having three phases of U phase, V phase, and W phase and four poles. The three-phase winding 33 is electrically connected to a power supply terminal (not shown) via a lead wire.

FIG. 5 is a view showing a U-phase winding state. The U-phase winding 33 is composed of two power supply lines, has two power supply terminals 33a and two neutral points 33b, and is connected at each end. Although not shown, the V-phase and W-phase are also used for the iron core portion 34 and the slot 3.
It is wound in the same manner as the U-phase, offset by 2.

Only four power supply lines are inserted into each slot 32, and the power supply line has a large cross section of a conductor portion so as to allow a sufficient current. This power supply line is, for example, a polyimide-coated nickel-plated copper wire.

In the stator 30 of this embodiment, the slot opening is not formed, but the winding 33 can be assembled efficiently by the following structure. The power supply line is obtained by welding the pine needle-shaped wire portion 50 as shown in FIG. 6 at the point X in FIG. The pine needle-shaped line portion 50 is formed with a folded portion 50a and a straight portion 50b that is inserted into the slot 32. Such a pine needle-shaped wire portion 50 cuts the power supply line into a predetermined length,
It is formed by bending 0a.

In order to form the winding 33, first, both ends of the pine needle-shaped wire portion 50 are inserted through one of the predetermined slots 32, and the linear portion 50b is arranged in the slot 32.
Both ends protruding from the other side of the slot 32 are appropriately bent near the opening of the slot 32. Then, the respective ends are welded in a predetermined combination (for example, spot welding, brazing, etc.). Furthermore, by connecting the power supply terminal 33a and the neutral point 33b, respectively, U-phase, V-phase, and W-phase windings are formed.

The U-phase, V-phase, and W-phase windings 33 are all wired across a plurality of slots 32, but the plurality of slots 32 used in each phase are equidistant in the stator 30. It is arranged. Therefore, the folded portion 5
0a can be formed to have the same length, and the pine needle-shaped line portion 50 can be used as a common component.

As described above, according to this embodiment,
It has the following effects. (1) In the brushless motor 1 in which the radially inner portion of the slot 32 of the stator 30 is not opened, the iron core portion 34 of the stacked core sheets 31 forming the stator 30 is formed.
The bridging portion thickness T of the thin portion 35 that connects the inner ends of the
0.2t with respect to the thickness t of the other part of the core sheet 31
To 1.0t.

As a result, when the conventional slot 32 is opened inward in the radial direction (the thickness T of the bridging portion corresponds to 0t).
The cogging torque is 4 compared to the brushless motor 1 of
It can be significantly reduced to 0% or less.

(2) In particular, the bridging portion thickness T of the thin portion 35 is different from the thickness t of other portions of the core sheet 31.
By setting from 0.2t to 0.5t, the cogging torque is compared to that of the brushless motor 1 when the conventional slot 32 is opened inward in the radial direction (the bridge thickness T is equivalent to 0t). And can be reduced to 40% or less,
The effective magnetic flux is as compared with the brushless motor 1 when the bridging portion thickness T is equal to the wall thickness t of the other portion of the core sheet 31,
It can be increased by 10% or more.

(3) Further, the stator 30 of the present invention includes
Although the slot opening for winding the winding wire 33 is not formed, the winding wire 33 is divided by using the pine needle-shaped wire portion 50 and is arranged in the slot 32. The winding 33 can be efficiently assembled by connecting the ends by welding or the like.

(4) Further, the pine needle-shaped wire portion 50 is used that has a larger cross-sectional area and a larger current capacity than the power supply line used for a normal winding. That is, the pine needle-shaped wire portion 50 has an allowable current amount for a plurality of normally used power supply lines, and thus the number of power supply lines inserted into the slots 32 can be significantly reduced. Therefore, it is preferable that the cross-sectional area conventionally occupied by the coating in the slot 32 is reduced due to the reduction in the number of power supply lines arranged in the slot 32.

(5) Further, conventionally, in the stator 30 as shown in FIG. 9, the slot opening 32a is formed for winding the winding wire 33, but this slot opening 32 is formed.
a causes cogging torque, and
Since it is open to the inner peripheral side of the
Applying No. 3 is difficult in workability and difficult to install. As a result, the conductor occupancy in the slot 32 is reduced.

However, in the stator 30 according to the embodiment, the pine needle-shaped wire portion 50 is used, and the pine needle-shaped wire portion 50 is inserted into one end of the slot 32 and the other end thereof is inserted into the slot 32. So slot 3
It is possible to reduce the unused space in 2 and increase the conductor occupancy in the slot 32.

(6) Therefore, the brushless motor 1 can be downsized and the output can be increased.

The embodiment of the present invention may be modified as follows. In the above embodiment, the pine needle-shaped wire portion 50 shown in FIG. 6 was used, but by using the pine needle-shaped wire portion 51 as shown in FIG. 7, the conductor occupation ratio in the slot 32 can be further increased. Is possible. Since the pine needle-shaped line portion 51 is formed in a rectangular shape in cross section, by sequentially arranging the pine needle-shaped line portion 51 in the radial direction in the slot 32, the space in the slot 32 can be effectively utilized.

In the above embodiment, the stator 30 having three phases and four poles is taken as an example, but a stator having a large number of poles such as three phases and six poles may be used. In this case, the slot 32 becomes narrower in the circumferential direction as the number of poles increases, and the stator 30 having the conventional slot opening 32a as shown in FIG.
In the above, since it is more difficult to apply the winding 33, the conductor occupancy rate is further reduced.

However, by using the pine needle-shaped wire portions 50 and 51, even when the number of poles is increased and the slot 32 is narrowed, the conductor occupancy rate can be set large, and the brushless motor 1 can be miniaturized. It is possible to increase the output.

Further, in the above embodiment, the pine needle-shaped line portion 5
Although 0 and 51 show the example wound as shown in FIG. 5, the winding method can be used for ordinary distributed winding, concentrated winding, and the like.

Further, in the above embodiment, the ring-shaped outer ring portion, the T-shaped iron core portion 34 and the bridging portion 35 are integrally formed, but only the iron core portion 34 and the bridging portion 35 are formed. May be integrally formed, separated from the outer ring portion, and then integrally fixed by the engaging portions formed in each. If molded in this way, the pine needle-shaped line portions 50, 5
A normal power supply line can be wound from the outside of the inner part in which the iron core part 34 and the bridging part 35 are stacked without using 1, and then the inner part and the stacked outer ring part. And can be integrally fixed.

In this case, in addition to using a normal power supply line,
The feeder line having a large cross-sectional area used in the pine needle-shaped wire portions 50 and 51 may be wound like an ordinary feeder line without being divided. In particular, the conductor occupancy can be increased if the feeder line has a rectangular cross section used in the pine needle-shaped wire portion 51.

The technical ideas other than the claims that can be understood from the above embodiment will be described below. (1) The stator according to any one of claims 3 to 5, wherein the winding is composed of a plurality of electric wires, and the plurality of electric wires are inserted between predetermined iron core portions to form a predetermined electric wire. A stator characterized in that ends thereof are electrically connected so as to form electric wiring.

Thus, even if the stator does not have the slot opening, a predetermined electric wiring can be obtained by inserting the electric wire into the slot and electrically connecting the end of the electric wire. is there.

[0056]

As described above, according to the core sheet, the stator and the rotating magnetic field type electric motor using the stator of the present invention, the core sheet does not have the slot opening portion which causes the cogging torque. The bridging portion connecting the inner end portions of the iron core portion has a thinner portion that is thinner than other portions of the core sheet. The thickness of the thin wall portion was set appropriately from the relationship between the thickness of the thin wall portion and the effective magnetic flux and the generated cogging torque, so that the cogging torque can be effectively reduced and an efficient rotating magnetic field type motor can be obtained. It becomes possible.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a brushless motor according to an embodiment.

2 is a cross-sectional view of the stator and rotor of FIG.

FIG. 3 is a partially enlarged view of a core sheet of an example.

FIG. 4 is a graph showing the relationship between the bridging portion thickness of the brushless motor of FIG. 1, effective magnetic flux, and cogging torque.

5 is a development view showing a winding state of a one-phase winding used in the brushless motor of FIG. 1. FIG.

FIG. 6 is a perspective view of a pine needle-shaped line portion.

FIG. 7 is a perspective view of a pine needle-shaped line portion according to another embodiment.

FIG. 8 is a sectional view of a stator and a rotor according to another embodiment.

FIG. 9 is a cross-sectional view of a conventional stator and rotor.

FIG. 10 is a partially enlarged view of a core sheet of a conventional example.

[Explanation of symbols]

1 brushless motor, 20 rotor, 21 magnet, 22 back yoke, 23 shaft,
30 stator, 31 core sheet, 32 slot, 32a slot opening, 33 winding, 33
a power supply terminal, 33b neutral point, 34 iron core part, 3
5 bridging part, 35a thin part, 40 yoke housing, 50, 51 pine needle-shaped wire part, 50a, 51a
Folded part, 50b, 51b Straight part

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takanori Ozawa             Asumo Stock Association, 390 Umeda, Kosai City, Shizuoka Prefecture             In-house (72) Inventor Mitsuhiko Matsushita             Asumo Stock Association, 390 Umeda, Kosai City, Shizuoka Prefecture             In-house F-term (reference) 5H002 AA02 AA04 AB06 AC02 AE06                       AE07                 5H621 AA02 GA01 GA04 GA12 GA18                       JK02 JK05

Claims (7)

[Claims] 1. An annular portion, a plurality of iron core portions provided on an inner peripheral surface of the annular portion so as to protrude inward in the radial direction, and end portions of the plurality of iron core portions inward in the radial direction. A bridging portion connecting to each other, and a plate-shaped core sheet comprising, wherein the bridging portion has a thin portion formed thinner than the plate thickness of the core sheet, A core sheet, wherein the plate thickness T of the thin portion is 0.2t ≦ T <t, where t is the plate thickness and T is the plate thickness of the thin portion. 2. The core sheet according to claim 1, wherein the plate thickness T of the thin portion is 0.2t ≦ T ≦ 0.5t. 3. A plurality of laminated plate-like core sheets,
A stator comprising a winding, wherein the core sheet has an annular portion, and a plurality of iron core portions provided on the inner peripheral surface of the annular portion so as to protrude radially inward,
A bridging portion connecting the radially inner ends of the plurality of iron core portions to each other, the bridging portion having a thin portion formed to be thinner than the plate thickness of the core sheet, A stator characterized in that the thickness T of the thin portion is 0.2t ≦ T <t, where t is the thickness of the core sheet and T is the thickness of the thin portion. 4. The stator according to claim 3, wherein the plate thickness T of the thin portion is 0.2t ≦ T ≦ 0.5t. 5. The stator according to claim 3 or 4, wherein the windings are wound around iron core portions that are separated from each other. 6. The stator according to claim 3, wherein the winding has a rectangular cross section. 7. A rotating magnetic field type electric motor using the stator according to claim 3.