JPH09308147A - Rotor of inner magnet-type motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor of an inner magnet-type motor which has a simple structure and has small cogging torque. SOLUTION: A rotor of an inner magnet-type motor has a plurality of installation holes 11 which are vertical to the central axis and are extended in the axis direction and has a square cross sectional shape and are formed at equal pitches in the circumferential direction and permanent magnets 2 which have a square cross sectional shape and are installed in the installation holes 11. Each of the permanent magnets 2 has a parallelogram upper face 21 and a parallelogram lower face 22 which face the center of the rotor and two side faces 23, 24 which face the circumferential direction of a rotor core 1 and are inclined against the axis direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor for an inner magnet type motor having a permanent magnet for forming a field in a cylindrical rotor.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, a rotor of an internal magnet type motor has mounting holes 11 formed in a cylindrical rotor core 1 at an equal pitch in the circumferential direction, and has a rectangular cross section. Japanese Patent Laid-Open No. 5-76146 discloses that the same number of permanent magnets 2 as the number of motor poles are mounted. In order to reduce the cogging torque of the permanent magnet type motor, as shown in FIG. 3, for example, as shown in FIG. The rotor cores 1 are arranged and fixed at equal pitches in the axial direction, and the rotor cores 1 are rotated in the axial direction slightly in sequence to be closely attached to each other. It is disclosed that they are arranged so as to be skewed only (for example, Japanese Utility Model Laid-Open No. 61-202166).

[0003]

However, in the former prior art described above, since the rectangular permanent magnets are mounted in the rectangular mounting holes, it is physically difficult to skew the permanent magnets, and for the windings provided on the stator core. It is necessary to reduce the cogging torque by skewing the slot. However, when the slot is skewed, the slot is slanted, and thus there is a problem that it takes much time and effort to mount the winding. In the latter prior art, since the rotor core is divided into a plurality of pieces, a plurality of permanent magnets are also required,
There is a problem that the number of parts increases and the number of processing steps increases. SUMMARY OF THE INVENTION It is an object of the present invention to provide a rotor for an inner magnet type motor having a small number of parts and processing steps and a simple structure and a small cogging torque.

[0004]

In order to solve the above problems, the present invention provides a plurality of mounting holes having an equal pitch in the circumferential direction and a cross section perpendicular to the central axis extending in the quadrangular axial direction. In the rotor of the inner magnet motor equipped with a permanent magnet having a quadrangular cross section mounted in the mounting hole, the permanent magnet is formed with parallelograms in an upper surface and a lower surface facing in a radial direction of the rotor core, In addition, the two side surfaces facing in the circumferential direction are formed to be inclined with respect to the axial direction. The side surface of one end of the permanent magnet contacts one inner surface of the mounting hole in the circumferential direction, and the side surface of the other end of the permanent magnet contacts the other inner surface of the mounting hole in the circumferential direction. It is installed. The rotor core is composed of a laminated iron core formed by laminating a plurality of thin steel plates. Further, the rotor core has a plurality of slots arranged at equal intervals in a circumferential direction and extending in an axial direction in an arc-shaped outer peripheral core portion surrounded by the mounting hole and an outer periphery of the rotor core, And a damper winding provided in the slot.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to embodiments shown in the drawings. 1 is a front sectional view showing an embodiment of the present invention, and FIG. 2 is a side sectional view taken along the line AA of FIG. In the figure, 1 is a cylindrical rotor core composed of a laminated iron core in which a plurality of thin steel plates are laminated, and 11 is a rectangular cross section of width W ₁ and height H provided in the rotor core 1 at equal pitches in the circumferential direction. It has the same number of mounting holes as the number of motor poles that it has and extends in the axial direction. Reference numeral 12 is a leakage magnetic flux prevention hole provided between the adjacent mounting holes 11. Reference numeral 2 denotes a permanent magnet mounted in each mounting hole 11, the shape of which is a quadrangle in cross section having a width W ₂ and a height H, and the upper surface 21 and the lower surface 22 facing the radial direction of the rotor core 1 are parallel sides. When the rotor core 1 has a length L, the two side surfaces 2 are formed in a circular shape and are oriented in the circumferential direction.
3 and 24 are inclined at an inclination angle θ with respect to the axial direction.
Note that tan θ = (W ₁ −W ₂ ) / L. That is, the permanent magnet 2 has the side surface 23 at one end thereof in the mounting hole 11
Contacting one inner surface 11a in the circumferential direction, and the side surface 24 at the other end of the permanent magnet has the other inner surface 11b in the circumferential direction of the mounting hole 11.
Is in contact with and installed. Permanent magnet 2 and rotor core 1
In the arc-shaped outer peripheral core portion 13 surrounded by the outer periphery of
A plurality of slots 14 extending in the axial direction at equal intervals in the circumferential direction
And the damper winding 3 is provided in the slot 14.

With such a structure, the magnetic flux distribution of the magnetic flux emitted from the upper surface 21 of the permanent magnet 2 is such that the central position of the magnetic flux distribution is inclined with respect to the axial direction of the rotor core 1 according to the shape of the parallelogram of the upper surface 21. Thus, the rotor core 1 is in the same state as the state in which the rotor core 1 is skewed by the skew angle θ relative to the stator facing through the air gap, and the skew effect of reducing the cogging torque is obtained.

[0007]

As described above, according to the present invention, the skew can be obtained by forming the upper and lower surfaces of the permanent magnets mounted in the rotor core, which are oriented in the radial direction, into parallelograms which are easy to manufacture. Since the effect can be obtained, there is an effect that it is possible to provide a rotor for an inner magnet type motor having a small cogging torque and a simple structure, which requires a small number of processing steps without providing a skew groove in the stator or the rotor core.

[Brief description of drawings]

1A is a front view showing an embodiment of the present invention, and FIG. 1B is a plan sectional view taken along the line AA.

FIG. 2 is a front view showing a conventional example.

3A is a side view and FIG. 3B is a front view showing another conventional example.

[Explanation of symbols]

1: rotor core, 11: mounting hole, 11a: one inner surface, 1
1b: inner surface on the other side, 12: leakage flux prevention hole, 13: outer peripheral core portion, 14: slot, 2: permanent magnet, 21: upper surface, 2
2: bottom surface, 23, 24: side surface, 3: damper winding

Claims (4)

[Claims] 1. A plurality of mounting holes, which are arranged at equal pitches in the circumferential direction and have a quadrangular cross section perpendicular to the central axis extending in the axial direction of the quadrangle, and a permanent magnet having a quadrangular cross section mounted in the mounting holes. In the rotor of the inner magnet type motor having the above-mentioned permanent magnet, the upper surface and the lower surface of the permanent magnet facing in the radial direction of the rotor core are formed in parallelogram, and the two side surfaces facing in the circumferential direction are in the axial direction. A rotor for an inner magnet type motor, which is formed to be inclined with respect to the rotor. 2. The permanent magnet has a side surface at one end contacting one inner surface in the circumferential direction of the mounting hole, and a side surface at the other end of the permanent magnet is in another inner surface in the circumferential direction of the mounting hole. The rotor of the inner magnet type motor according to claim 1, which is mounted in contact with the rotor. 3. The rotor of an inner magnet type motor according to claim 1, wherein the rotor core is a laminated iron core formed by laminating a plurality of thin steel plates. 4. The rotor core is provided with a plurality of slots arranged at equal intervals in a circumferential direction and extending in an axial direction in an arc-shaped outer peripheral core portion surrounded by the mounting hole and an outer periphery of the rotor core. And the damper winding provided in the slot, The rotor of the inner magnet type motor according to any one of claims 1 to 3.