KR19980083326A - Permanent magnet embedded rotor structure - Google Patents

Abstract

The present invention relates to a rotor structure of a motor, and more particularly, to a structure for improving the electrical efficiency while ensuring the structural stability of the permanent magnet embedded rotor for placing a permanent magnet inside the rotor, A first permanent magnet buried portion formed of a plurality of mutually symmetrically grooved grooves perpendicular to the radial direction of the outer side, and a V-shaped outwardly directed toward the first permanent magnet buried portion between the first permanent magnet buried portion and the rotating shaft; Permanent magnets are embedded in the second permanent magnet buried portions of the shape.

Description

Permanent magnet embedded rotor structure

The present invention relates to a rotor structure of a motor, and more particularly, to a structure for improving the electrical efficiency while stabilizing the structure of the permanent magnet buried rotor for placing a permanent magnet inside the rotor.

Motors are an essential electric device for obtaining rotational force, and various motors have been researched and developed. However, according to the propensity of research on small and light-weighted electric and electronic devices applying and adopting these motors, compared to the overall volume and weight Small motors and lightweight researches were mainly focused on the motors which occupy a considerable proportion.

AC motors that generate a rotating magnetic field by applying an alternating current voltage to the stator and obtain a rotational force by mutual electromagnetic force acting between the currents derived from the rotating field are general motor types used in various home appliances. In the case of AC motors, various electrical losses due to the current flowing through the rotor have to be taken into consideration, and the difficulty of miniaturization of the motor is due to the difficulties in the process of installing an electric passage coil in the core of the motor rotor.

In addition, in the device requiring the constant torque characteristics, the demand of the DC motor has increased greatly. Although the research and development has been done, the commutator, which is an essential device for the DC motor, must be installed, and the mechanical damage occurring in the commutator should be considered. In addition, the service life did not last long due to the friction between the commutator and the rotating shaft.

Therefore, motors that can install a permanent magnet on the rotor and obtain torque without a commutator have been researched and developed. A representative achievement of this effort was to change the direction of the magnetic field by changing the direction of current electronically instead of the commutator, and to develop a brushless motor that installs permanent magnets in the rotor, applying alternating current voltage to the stator, and rotating the rotor. By installing a permanent magnet in the rotor, a switched reluctance motor has been developed in which the rotor rotates due to a change in the reluctance of the magnetic field generated by interrupting the energizing current flowing through the permanent magnet of the rotor and the windings of each phase installed in the stator.

Since these brushless motors or switched reluctance motors operate at high speed rotation, the permanent magnet rotor structure employed in these motors should be configured to rotate without electrical loss and vibration during high speed rotation.

Rotors that are commonly used up to now can be divided into permanent magnet external motor and permanent magnet embedded motor.

1 is a perspective view of a rotor of a conventional permanent magnet exterior type.

2 is a cross-sectional view of a rotor of a conventional permanent magnet buried type.

As shown in FIG. 1, the permanent magnet exterior type has an iron core 3 laminated with a rotor iron plate 2 made of a thin silicon steel sheet to form a body, and bonded to an adhesive 4 on an outer circumferential surface of the core. It consists of a permanent magnet 5 of the circular body to be mounted. Reference numeral 1 is a pressing hole for pressing the rotary shaft (not shown) formed in the center of rotation of the rotor.

The rotor of this external type has a loss of adhesive force due to the change of adhesive and segregation of the iron core 3 and the permanent magnet 5, which may cause a breakdown. Due to the difference in centrifugal force received by the iron core 3, the phenomenon that the permanent magnet 5 is separated from the iron core 3 may occur.

Therefore, in the high speed rotary motor, the embedded type as shown in FIG. 2 is mainly used.

As shown in Fig. 2, the embedded rotor forms symmetrically formed linear grooves 21 of a predetermined length at a right angle with respect to the radial direction from the center of the rotor iron plate 2.

These straight part grooves 21 form a trough in the longitudinal direction of the rotating shaft when the rotor plate 2 is stacked. The permanent magnet 30 as shown in FIG. 3 is inserted into the trough to generate a magnetic field.

However, such a rotor structure may be damaged due to more stress applied to the end portion 22 in the longitudinal direction of each of the linear grooves 21, and such a non-uniform stress distribution may cause damage during high-speed rotation of the motor. There is a fear of rotor damage due to vibration.

As a result of various studies and developments to improve this point, Japanese Laid-Open Patent Publication No. 5-236685 (published date: September 10, 1993) is the result of this effort.

The contents described in the above publication are uniform by extending the end of the magnet-embedded groove portion having a predetermined length in a direction perpendicular to the radial direction of the rotor in order to equalize the stress distribution of the embedded rotor by a predetermined length in the radial direction of the rotor. One stress distribution was obtained.

4 is a plan view of an iron plate of a buried rotor with a conventional radially extending groove.

As shown in FIG. 4, the permanent magnet embedded rotor iron plate 2 is symmetrically formed with a magnet buried straight part groove 21 having a predetermined length in a direction perpendicular to the radial direction of the rotor. An end of the 21 forms an extension groove 42 extending outwardly by a predetermined length in the radial direction of the rotor. The extension groove 42 formed as described above is formed in parallel with the extension grooves 42 'of the other magnet embedding linear groove 21. Since the extension grooves 42 and 42 'are disposed in the rotor iron plate 2, the stress distribution becomes uniform, and this stress distribution prevents the vibration of the motor.

However, the arrangement of the extension grooves 42 of the rotor iron plate 2 can uniformly distribute the stress, but since the voids are formed in a direction substantially perpendicular to the flow of the magnetic flux, the magnetic flux is lost, resulting in inefficient energy. It is used.

Fig. 5A is a plan view of the rotor iron core for showing the magnetic flux distribution generated by the stator. FIG. 5B is an enlarged view of portion A of FIG. 5A.

By energizing the coil wound on the stator 51, the magnetic flux to be excited flows in the rotor 52 through the gap between the rotor 52 and the stator 51, but the extension groove 42 of the rotor 52. ), The magnetic flux is disturbed by the smooth flow. As shown in FIG. 5 (b), the extension groove 42 forms a low permeability gap, so that the magnetic flux is concentrated along the extension groove 42, which leads to energy loss.

The present invention has been made in view of these problems, to maintain the magnetic flux flow of the extension grooves to prevent the loss of magnetic flux, to reduce the leakage magnetic flux to prevent energy loss, to obtain a greater torque There is a purpose.

1 is a perspective view of a rotor of a conventional permanent magnet exterior type.

2 is a cross-sectional view of a rotor of a conventional permanent magnet buried type.

3 is a perspective view of a permanent magnet embedded in a buried groove shown in FIG.

4 is a plan view of an iron plate of a buried rotor with a conventional radially extending groove.

FIG. 5 (a) is a plan view of a rotor iron core for showing the magnetic flux distribution generated by the stator, and FIG. 5 (b) is an enlarged view of the portion A of FIG. 5 (a).

6 is a plan view of a rotor iron plate used in an embodiment of the present invention.

7 is a flux distribution diagram passing through the stator and the rotor of the present invention.

8A is a graph measuring torque for an embodiment of the present invention, and FIG. 8B is a graph measuring torque for the embodiment of FIG. 2 according to the prior art.

* Explanation of symbols for the main parts of the drawings *

100: rotor plate 121, 122, 123, 124: first permanent magnet buried parts

131, 132, 133, 134: second permanent magnet buried portion 180, 190: permanent magnet

In order to achieve the above object, the present invention is a buried rotor structure for embedding a permanent magnet in the rotor, the first permanent magnet formed of a plurality of mutually symmetrical grooves of a predetermined length perpendicular to the radial direction of the rotor The buried parts, the permanent magnet is embedded in the second permanent magnet buried portion of the V-shape (V) shape that is outward toward the first permanent magnet buried portion between the first permanent magnet buried portion and the rotation axis.

In addition, the V-shaped corner of the present invention is characterized in that the second permanent magnet buried portion is symmetric with each other coinciding with the center of the first permanent magnet.

Hereinafter, the above objects and features of the present invention will be described in detail with reference to the accompanying drawings.

6 is a plan view of a rotor iron plate used in an embodiment of the present invention. 7 is a flux distribution diagram passing through the stator and the rotor of the present invention.

As shown in FIG. 6, a rotation shaft indentation hole 110 through which a rotation shaft can be pressed is formed at the center of the rotor iron plate 100, and has a predetermined length in a vertical direction with respect to the radial direction of the rotor iron plate 100. As many first permanent magnet buried portions 121, 122, 123, 124 are formed. The first permanent magnet buried portions 121, 122, 123, and 124 may be formed by being punched from the rotor iron plate 100 by a mold. In addition, the second permanent magnet having a V shape toward the first permanent magnet buried portion 121 between the first permanent magnet buried portions 121, 122, 123, and 124 and the rotary shaft indentation hole 110. The buried portion 131 is formed.

Here, the connecting portion 140 which is the central portion of the second permanent magnet buried parts 131, 132, 133, and 134 is formed to be narrower than other parts so that there is no flow of permanent magnets, and the second permanent magnet buried part 131 is The second permanent magnet buried portion 132 is formed to be inclined closer to the end portion so that the magnetic flux density is uniformly distributed.

Reference numeral 150 indicates a rivet welding part for stacking the rotor iron plates 100 or bolts inserted into the fastening hole and the fastening hole for fixing and fastening each iron plate to form one iron core.

As shown in FIG. 7, when a current is applied to the stator winding of the stator 160 and a magnetic field is applied, the magnetic flux lines forming the magnetic field pass through the gap formed between the stator 160 and the rotor 170, and The electrons 170 flows into the inside, and the magnetic flux lines generated from the permanent magnets 180 and 190 embedded in the rotor 170 are rotated to be most smoothly flowing to the stator 160. do. However, when the magnetic flux lines generated by the stator windings flow inside the rotor 170, the first permanent magnet buried parts 121, 122, 123, 124 and the second permanent magnet buried parts 131, 132, Magnetic flux lines flowing between 133 and 134 are guided by the buried portions to maintain a magnetic flux line shape that is approximately circular. In addition, the strength of the magnetic field is inversely proportional to the length of the magnetic flux line, that is, the length of the magnetic path, thereby generating a larger magnetic field. In addition, the loss due to the magnetic field increases in proportion to the magnetic flux density B, but in the rotor of such a structure, the magnetic flux lines induce a gentle flow to prevent the magnetic flux lines from being concentrated in a specific portion, thereby preventing the loss. .

As shown in FIG. 7, the magnetic flux lines generated by the permanent magnets 180 are affected by the magnetic flux lines from the permanent magnets 190. That is, since only one magnetic flux line passing through an arbitrary point should exist, the magnetic flux lines generated from the permanent magnets 180 are guided toward the voids under the repulsive force of the permanent magnets 190, and thus simply within the rotor 170. Circulating leakage flux is small. Therefore, the magnetic flux lines generated from the permanent magnet embedded in the rotor 170 increases the effective rate directed to the gap between the rotor 170 and the stator 160 to generate a greater torque.

In addition, since the magnetic flux lines generated from the two permanent magnets 180 and 190 are mutually reinforced, it is possible to make a larger torque than the rotor generated from one permanent magnet.

8A is a graph measuring torque for an embodiment of the present invention, and FIG. 8B is a graph measuring torque for the embodiment of FIG.

As shown in FIG. 8B, when the mechanical angle with respect to the rotational direction of the motor is referenced, a ripple that can cause vibration is sharply formed between the maximum value and the minimum value, so that mechanical vibration and noise occur, and the unit It can be seen that the average torque per stack is approximately 3 kg-cm.

However, the torque of an embodiment of the present invention measured at the same power consumption and magnetic amount as in FIG. 8B has a very small ripple formation as shown in FIG. 8A, thereby reducing vibration and noise. In addition, the average torque per unit stacking is approximately 6kg-cm, it is possible to obtain a torque more than twice the conventional average torque. Therefore, high output can be obtained even at small power consumption.

According to the object and configuration of the present invention as described above, the rotor of the present invention creates a smooth flow of the magnetic flux, and when a constant voltage is applied, it shows a better efficiency than the rotor of the other structure, the magnetic flux with a uniform magnetic flux distribution This exhibits an effect of suppressing vibration more than when it is biased. In addition, high torque can be obtained at the same magnetic amount, and energy can be efficiently used.

Claims (2)

In the embedded rotor structure for embedding the permanent magnet in the rotor, the first permanent magnet buried portion formed of a plurality of mutually symmetrical grooves of a predetermined length perpendicular to the radial direction of the rotor, the first permanent magnet buried portion And a permanent magnet embedded in the second permanent magnet buried portions having a V-shape facing outward toward the first permanent magnet buried portion between the rotary shaft and the rotary shaft. The permanent magnet buried rotor structure according to claim 1, wherein the first permanent magnet buried portion and the second permanent magnet buried portion are mutually symmetric with respect to the radial direction of the rotor.