JP3796609B2 - Permanent magnet motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric motor using a permanent magnet as a field, and more particularly to an armature core for reducing torque ripple.
[0002]
[Prior art]
Conventionally, some electric motors using permanent magnets as field magnets skew the slot provided in the armature core by one slot in order to insert the armature coil in order to reduce torque ripple caused by cogging torque. However, there is a problem that the process of skewing the armature core becomes complicated, and the work of inserting the armature coil takes time.
Therefore, as a simple method for reducing the torque ripple, there is a method in which a pseudo multi-slot is used and the frequency of the cogging torque is increased so that the torque is not substantially affected (for example, Japanese Patent Laid-Open No. Sho 63-63). No. 140635).
For example, when the number of magnetic poles is 6 and the number of slots in which armature coils are inserted is 9, as shown in FIG. 6, nine core teeth 2 are projected inside the ring-shaped armature core 1 and adjacent to each other. Nine slots 3 are formed between the matching core teeth 2. An armature coil 4 is attached to the slot 3.
A recess 21 is provided at the tip of each iron core tooth 2. A rotor 5 is provided inside the iron core tooth 2 via a gap, and a permanent magnet 6 that forms six magnetic poles is attached to the surface of the rotor 5.
With this configuration, the pseudo slot is doubled and the period of the cogging torque is doubled, so that the amplitude of the actually generated torque ripple is reduced.
[0003]
[Problems to be solved by the invention]
However, in the above prior art, the concave portion 21 provided at the tip of the iron core tooth 2 is connected to the gap between the rotor 4 and the armature core 1, so that the operating point of the permanent magnet 6 in the concave portion 21 is lowered. The magnetomotive force decreases and the magnetic flux decreases.
As a result, the overall result is the same as the increase in the gap length, the induced voltage is reduced, and the motor characteristics are deteriorated as compared with the case where there is no recess 21.
SUMMARY OF THE INVENTION An object of the present invention is to provide a high-torque high-precision permanent magnet motor that has a small torque ripple due to cogging torque and can prevent a decrease in air gap magnetic flux.
[0004]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a ring-shaped armature core having a plurality of core teeth protruding inward, and an armature coil mounted in a slot formed between the adjacent core teeth. A permanent magnet type electric motor including a rotor provided with a permanent magnet that forms a magnetic field and is opposed to the inside of the iron core tooth through a gap, and the armature core is arranged between inner sides of the adjacent iron core teeth. A slot- shaped outer core that is connected to the outer side of the inner core, and that is located inside from the inner surface of the plurality of core teeth, and the slot pitch angle of the slot A space portion is provided at a plurality of divided positions, and the space portion is formed in a spindle shape so that the outer circumferential direction is thin, and the space portion of the iron core tooth portion is a portion near the inner surface of the iron core tooth. Radially from Is, the space portion of the portion connecting the inner to each other in said core is to narrow part of spindle-shaped are arranged to face the circumferential direction.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to embodiments shown in the drawings.
FIG. 1 is a front sectional view showing a first embodiment of the present invention. As an example, FIG. 1 shows a case where there are 6 magnetic poles and 9 armature coils are inserted.
In the figure, reference numeral 1 denotes a ring-shaped armature core, and 2 denotes an iron core tooth protruding inside the armature core 1. 3 is a slot formed between adjacent iron core teeth 2, and 4 is an armature coil mounted in the slot 3.
A rotor 5 is provided inside the iron core teeth 3 so as to face each other through a gap. A permanent magnet 6 that forms six magnetic poles is attached to the outer peripheral surface of the rotor 5.
In the core tooth 2, two elliptical space portions 7 are provided at positions where the slot pitch angle Θ in the circumferential direction is divided into three equal parts so as not to be connected to the air gap from the surface of the core tooth 2. Is provided. Therefore, the space portion 7 does not open on the surface of the iron core tooth 2, and a thin connecting portion 71 is formed between the space portion 7 and the surface of the iron core tooth 2 to be closed.
[0006]
With such a configuration, since the magnetic flux generated from the permanent magnet 6 passes through both sides of the space portion 7, it is the same as the number of slots increased to 27, which is three times.
Therefore, the period of cogging is three times 18 peaks, which is the least common multiple of the number of slots and the number of magnetic poles, that is, 54 peaks.
Thus, the frequency of the cogging torque is increased, the change in magnetic force due to the relative position of the magnetic pole and the slot due to the rotation of the rotor 5 is suppressed, and the torque ripple can be reduced.
Moreover, since the surface of the iron core tooth 2 has no recess and is smooth, there is little change in the magnetic flux in the air gap, and the induced voltage can be prevented from lowering.
Note that the number of dividing the slot pitch angle Θ is not limited to three.
[0007]
FIG. 2 is a front sectional view showing a second embodiment of the present invention. As an example, FIG. 2 shows a case where the number of magnetic poles is 6 and the number of slots into which armature coils are inserted is 9.
In this case, only one space portion 7 provided in the iron core teeth 2 is provided at a position entering the inside from the surface of each iron core tooth 2, and assuming that the number of slots is n, a deviation angle obtained by dividing the slot pitch angle Θ into (n + 1) equal parts. They are provided at positions shifted in the circumferential direction by θ.
For example, in the case of 9 slots, Θ = 360/9 = 40 °
θ = 40 ° / (9 + 1) = 4 °.
Nine core teeth 2 to 2a counterclockwise to position the space portion 7 by Ke with the number to 2B～2i.
The space portion 7a of the iron core tooth 2a is provided on the center line A, and the space portion 7b of the iron core tooth 2b is provided at a position shifted by 4 ° counterclockwise from the center line B. Space portions 7c, 7d, and 7e are provided on the iron core teeth 2c, 2d, and 2e at positions shifted by 8 °, 12 °, and 16 ° from the center lines C, D, and E, respectively. Since the deviation angle of the iron core teeth 2f is 20 °, which corresponds to the slot 3, there is no need to provide it. The iron core teeth 2g are provided at 12 ° clockwise from the center line G, and the iron core teeth 2h and 2i are provided at positions offset by 8 ° and 4 ° clockwise from the center lines H and I, respectively.
[0008]
With such a configuration, the entire core teeth have the same air gap magnetic distribution as the slot 3 is skewed by one slot, the frequency of cogging torque is increased, and torque ripple is reduced.
Although as order deviation angle theta circumferential array of core teeth 2 is increased in the above embodiment, orderly it is not necessary to determine the deviation angle theta, the center line or Lara random for each core teeth 2 The shift angle θ may be shifted.
FIG. 3 is a front sectional view showing a third embodiment of the present invention.
When circular space portions 7 having a constant diameter are provided in each iron core tooth 2, the space portion 7 is set at a position close to the side surface of the iron core tooth 2 and may break through the side surface.
In this case, a circular space portion 7x having a small diameter is provided so as not to break through the side surface.
FIG. 4 is a front sectional view showing a fourth embodiment of the present invention.
In this case, a deformed space 7y is provided so as not to break through the side surface of the iron core tooth 2.
[0009]
FIG. 5 is a front sectional view showing a fifth embodiment of the present invention.
In this case, the armature core 1 is arranged such that the inner core 11 where the inner sides of the adjacent core teeth 2 are connected to each other and the outer side between the adjacent core teeth 2 is opened to insert the armature coil. It is comprised by the ring-shaped outer core 12 fitted on the outer side.
Space 7z, as shown in FIG. 5, in order to reduce the resistance of the flow of the magnetic flux generated from the permanent magnet 6, Rutotomoni formed in spindle so that the outer circumference becomes narrower, the space portion of the core teeth portions, Spindle-shaped thin portions are arranged radially from the vicinity of the inner surface of the iron core teeth, and the space portion connecting the inner cores of the inner core is arranged so that the spindle-shaped thin portions are directed in the circumferential direction. .
Therefore, since the slot is not opened inside the iron core tooth 2, the air gap magnetic flux density can be kept high, the cogging torque is small, and the torque ripple can be further reduced by providing the space portion 7z. it can.
The position of the space 7z can be determined by the method shown in the first and second embodiments.
In the above embodiment, the motor has nine slots and six magnetic poles. However, for example, when the number of slots is six and the number of magnetic poles is four, or when the number of magnetic poles is twelve and the number of magnetic poles is twelve. The same effect is obtained when the cogging torque is large in other combinations such as 8-pole.
[0010]
【The invention's effect】
As described above, according to the present invention, the inner surface of the iron core tooth of the armature core is smoothed, and the space portion is provided at a position where the slot pitch is divided into a plurality of positions in the vicinity of the inner surface of the iron core tooth, thereby cogging torque. Therefore, the induced voltage can be prevented from being lowered and the torque ripple can be reduced, thereby providing an effect of providing a high-torque high-precision permanent magnet motor.
[Brief description of the drawings]
FIG. 1 is a front sectional view showing a first embodiment of the present invention.
FIG. 2 is a cross-sectional plan view showing a second embodiment of the present invention.
FIG. 3 is a cross-sectional plan view showing a third embodiment of the present invention.
FIG. 4 is a cross-sectional plan view showing a fourth embodiment of the present invention.
FIG. 5 is a cross-sectional plan view showing a fifth embodiment of the present invention.
FIG. 6 is a plan sectional view showing a conventional example.
[Explanation of symbols]
1: Armature core, 2 (2a-2i): Iron core teeth, 3: Slot, 4: Armature coil, 5: Rotor, 6: Permanent magnet, 7 (7a-7i), 7x, 7y, 7z: Space part

Claims (1)

A ring-shaped armature core having a plurality of core teeth protruding inward, an armature coil mounted in a slot formed between the adjacent core teeth, and a gap inside the core teeth In a permanent magnet type electric motor provided with a rotor provided with a permanent magnet facing and forming a field,
The armature core is composed of an inner core in which the inner sides of the adjacent core teeth are connected to each other, and a ring-shaped outer core fitted on the outer side of the inner core, and from the inner surfaces of the plurality of core teeth. A space portion is provided at a position inside the slot and at a position obtained by dividing the slot pitch angle of the slot into a plurality of parts ,
The space portion is formed in a spindle shape so that the outer circumferential direction is narrowed, and the space portion of the iron core tooth portion is arranged such that the spindle-shaped thin portion is radially arranged from the vicinity of the inner surface of the iron core tooth. A permanent magnet type electric motor characterized in that the space portion of the portion connecting the inner sides is arranged such that a thin spindle-shaped portion faces the circumferential direction .

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