JPH10304606A - Permanent magnet-type motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-torque, high-accuracy permanent magnet-type motor which involves smaller torque ripples and allows reduction in air-gap magnetic flux to be prevented. SOLUTION: A motor is provided with an annular armature core 1 having a plurality of iron core teeth 2 projected inwards, armature coils 4 installed in slots 3 formed between the adjacent iron core teeth 2, and a rotor 5 provided with permanent magnets 6 which are opposed to the inside of the iron core teeth 2 with an air gap in-between and form magnetic fields. In this case, spaces 7 are formed in positions back from the surface of the inside of the plurality of the iron core teeth 2, where the slot pitch angle of the slots 3 are divided into a plurality of angles. As a result, reduction in induced voltage is prevented, and the frequency of cogging torque is increased. Thus, torque ripples can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor using a permanent magnet as a magnetic field, and more particularly to an armature core for reducing torque ripple.

[0002]

2. Description of the Related Art Conventionally, an electric motor using a permanent magnet as a field has only one slot provided in an armature core for inserting an armature coil in order to reduce torque ripple caused by cogging torque. Although there is skew, there are problems that the process of skewing the armature core is complicated and that the work of inserting the armature coil is troublesome. Therefore, as a method of easily reducing the torque ripple, there is a method in which the number of slots is artificially increased and the frequency of the cogging torque is increased so that the torque is not substantially affected. 1
No. 40635). For example, when the number of magnetic poles is six and the number of slots for inserting an armature coil is nine, nine core teeth 2 are protruded inside a ring-shaped armature core 1 as shown in FIG. 9 slots 3 between matching core teeth 2
Is formed. An armature coil 4 is mounted in the slot 3. A recess 21 is provided at the tip of each iron core tooth 2. Inside the iron core teeth 2, a rotor 5 facing through a gap is provided.
, And a permanent magnet 6 forming six magnetic poles is mounted on the surface of the rotor 5. With such a 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]

However, in the above prior art, the recess 21 provided at the tip of the iron core teeth 2 is
And the armature core 1, the operating point of the permanent magnet 6 in the recess 21 is lowered, the magnetomotive force is reduced, and the magnetic flux is reduced. As a result, the same result as an increase in the gap length is obtained as a whole, and the induced voltage is reduced, and there is a problem that the motor characteristics are deteriorated as compared with the case where the concave portion 21 is not provided. SUMMARY OF THE INVENTION An object of the present invention is to provide a high-torque, high-accuracy permanent magnet type electric motor in which torque ripple due to cogging torque is small and a decrease in air gap magnetic flux can be prevented.

[0004]

In order to solve the above-mentioned problems, the present invention provides a ring-shaped armature core having a plurality of inwardly protruding iron core teeth formed between adjacent iron core teeth. In a permanent magnet type electric motor including an armature coil mounted in a slot and a rotor provided with a permanent magnet that forms a magnetic field, facing the inside of the iron core teeth via a gap, A space is provided at a position that enters the inside from the inner surface and at a position obtained by dividing the slot pitch angle of the slot into a plurality. The space portions are provided at positions obtained by dividing the slot pitch angle into a plurality. Further, one space portion is provided at a position shifted in the circumferential direction from each other for each of the iron core teeth by a shift angle obtained by dividing the slot pitch angle into a plurality. Further, the armature core includes an inner core in which the inner sides of the adjacent iron core teeth are connected,
A ring-shaped outer core fitted on the outer side of the inner core. Further, of the space, a space set at a position close to the side surface of the iron core tooth has a shape that is more deformed than the shape of the space at another position. Further, the space portion is formed in a spindle shape so that an outer peripheral direction becomes thinner, and is arranged radially from a vicinity of an inner surface of the iron core tooth.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings. FIG. 1 is a front sectional view showing a first embodiment of the present invention, and shows a case where the number of magnetic poles is six and the number of slots for inserting an armature coil is nine as an example. In the figure, 1 is a ring-shaped armature core, and 2 is an iron core tooth protruding inside the armature core 1. Reference numeral 3 denotes a slot formed between adjacent iron core teeth 2, and 4 denotes an armature coil mounted in the slot 3. A rotor 5 is provided inside the iron core teeth 3 with a gap therebetween, and a permanent magnet 6 forming six magnetic poles is mounted on the outer peripheral surface of the rotor 5.
Each of the core teeth 2 is positioned at a position obtained by equally dividing the circumferential slot pitch angle Θ by three so as not to be connected to a gap.
Two elliptical spaces 7 at the position inside the surface
Is provided. Therefore, the space portion 7 does not open on the surface of the iron core teeth 2, and a thin connecting portion 71 is formed and closed between the space portion 7 and the surface of the iron core teeth 2.

[0006] With this configuration, the magnetic flux from the permanent magnet 6 passes through both sides of the space 7, which is the same as increasing the number of slots to 27 times. Therefore, the cycle of cogging is three times the 18 peaks, which is the least common multiple of the number of slots and the number of magnetic poles, ie, 54 peaks. From this,
The frequency of the cogging torque increases, and the change in the magnetic force due to the relative position between the magnetic pole and the slot due to the rotation of the rotor 5 is suppressed to a small value, thereby reducing the torque ripple.
In addition, since the surface of the iron core teeth 2 has no concave portions and is smooth, the change in magnetic flux in the air gap is small, and a decrease in induced voltage can be prevented. The number of divisions of the slot pitch angle Θ is not limited to three.

FIG. 2 is a front sectional view showing a second embodiment of the present invention, in which the number of magnetic poles is six and the number of slots for inserting an armature coil is nine as an example. In this case, only one space portion 7 provided in the iron core teeth 2 is provided at a position entering from the surface of each iron core tooth 2 and the number of slots is n.
The slot pitch angle Θ is provided at positions shifted from each other in the circumferential direction by a shift angle θ obtained by equally dividing the slot pitch angle Θ by (n + 1). For example, in the case of 9 slots, Θ = 360/9 = 40 ° θ = 40 ° / (9 + 1) = 4 °. The nine core teeth 2 are numbered counterclockwise from 2a, 2b to 2i to determine the position of the space 7. The space 7a of the iron core teeth 2a is provided on the center line A, and the space 7b of the iron core teeth 2b is provided at a position deviated by 4 ° counterclockwise from the center line B. Iron core teeth 2c,
2d and 2e are 8 ° from the center lines C, D and E, respectively, 1
Spaces 7c, 7d, 7e are provided at positions shifted by 2 ° and 16 °. Since the angle of deviation of the iron core teeth 2f is 20 ° and corresponds to the slot 3, there is no need to provide them. The iron core teeth 2g are provided at positions 12 ° clockwise from the center line G, and the iron core teeth 2h and 2i are provided at positions 8 ° and 4 ° clockwise shifted from the center lines H and I, respectively.

With such a configuration, the magnetic core has the same air gap magnetic distribution as in the state where the slots 3 are skewed by one slot, the frequency of the cogging torque is increased, and the torque ripple is reduced. In the above embodiment, the shift angle θ is increased in the order of the circumferential arrangement of the core teeth 2. However, it is not necessary to determine the shift angle θ in order, and the shift angle θ is randomly shifted from the center line of each core tooth 2. It may be shifted by the angle θ. FIG. 3 is a front sectional view showing a third embodiment of the present invention. When a circular space 7 having a constant diameter is provided in each core tooth 2, the space 7 may be set at a position close to the side surface of the iron core tooth 2 and break through the side surface. in this case,
A circular space 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 portion 7y is provided so as not to break through the side surface of the iron core teeth 2.

FIG. 5 is a front sectional view showing a fifth embodiment of the present invention. In this case, the armature core 1 is formed such that the inner core 11 where the inner sides of the adjacent iron core teeth 2 are connected to each other and the outer side between the adjacent iron core teeth 2 are opened to insert the armature coil. It comprises a ring-shaped outer core 12 fitted to the outside. The space portion 7z is formed in a spindle shape so that the outer peripheral direction becomes thin in order to reduce the resistance of the flow of the magnetic flux generated from the permanent magnet 6, and is arranged radially from the vicinity of the inner surface of the iron core teeth 2. . Therefore, since no slot is opened inside the iron core teeth 2, the air gap magnetic flux density can be maintained high,
The cogging torque is small, and the provision of the space 7z can further reduce the torque ripple. The position of the space 7z can be determined by the method shown in the first and second embodiments. In the above embodiment, a motor having nine slots and six magnetic poles has been described. However, for example, a motor having six slots and four magnetic poles, or a motor having twelve slots and magnetic poles having twelve slots. The same effect is obtained when the cogging torque is large in other combinations, such as when the number of poles is eight.

[0010]

As described above, according to the present invention, the inner surface of the iron core teeth of the armature core is smoothed, and the space is formed in the vicinity of the inner surface of the iron core teeth at a position where the slot pitch is divided into a plurality. Since the frequency of the cogging torque is increased by the provision, the induced voltage can be prevented from lowering, the torque ripple can be reduced, and there is an effect that a permanent magnet type motor with high torque and high accuracy can be provided.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a first embodiment of the present invention.

FIG. 2 is a plan sectional view showing a second embodiment of the present invention.

FIG. 3 is a plan sectional view showing a third embodiment of the present invention.

FIG. 4 is a plan sectional view showing a fourth embodiment of the present invention.

FIG. 5 is a plan sectional 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 to 2i): iron core teeth, 3: slot, 4: armature coil, 5: rotor, 6: permanent magnet,
7 (7a-7i), 7x, 7y, 7z: space part

Claims (6)

[Claims] 1. A ring-shaped armature core having a plurality of core teeth protruding inward, an armature coil mounted in a slot formed between adjacent core teeth, and an inner side of the core teeth. And a rotor provided with a permanent magnet that forms a magnetic field, the rotor being provided with a permanent magnet that forms a magnetic field.
And a space portion is provided at a position obtained by dividing the slot pitch angle of the slot into a plurality. 2. The permanent magnet electric motor according to claim 1, wherein the space is provided at a position obtained by dividing the slot pitch angle into a plurality. 3. The permanent magnet according to claim 1, wherein one of the space portions is provided at a position which is circumferentially shifted from each other for each of the iron core teeth by a shift angle obtained by dividing the slot pitch angle into a plurality. Shaped motor. 4. The armature core according to claim 1, wherein the inner core of the adjacent iron core teeth is connected to each other, and a ring-shaped outer core fitted outside the inner core.
The permanent magnet type electric motor according to any one of the above. 5. The space portion of the space portion set at a position close to the side surface of the iron core tooth has a shape that is more deformed than the shape of a space portion at another position. Permanent magnet type electric motor. 6. The space according to claim 1, wherein the space is formed in a spindle shape so that an outer peripheral direction becomes thinner, and is arranged radially from a vicinity of an inner surface of the iron core teeth. A permanent magnet type electric motor as described.