JP2005020874A - Motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To offer a motor which is suited for raising its rotation by enabling itself to lessen the eddy current loss of a rotor without losing the manufacturability of a rotor. <P>SOLUTION: This is premised on an inner rotor type motor which is equipped with a rotor where rotor magnets 24 are arranged individually in each magnet mounting hole provided at the periphery of a rotor core. Each rotor magnet 24 has one or more slits 24a, a plurality of magnet regions 24b, and extensions 24c. The slit 24a extends in the rotational direction or the axial direction of the rotor and the direction crossing these directions, with at least its one end blocked, thereby dividing the rotor magnet 24 into a plurality of magnet regions 24b. The extension 24c is a section which is extended oppositely to the direction where the slit 24a is extended from the blocking end 24ae of the slit 24a, and it is provided by yoking magnet regions 24b neighboring each other across the slit 24a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inner rotor type motor, and more particularly to a motor including a rotor having a rotor magnet made of a permanent magnet.
[0002]
[Prior art]
Conventionally, a brushless motor is known in which a permanent magnet (rotor magnet) is fitted into each of a plurality of magnet mounting holes provided in a peripheral portion of a rotor core provided in a rotor (for example, see Patent Document 1). ).
[0003]
[Patent Document 1]
JP 2002-165393 A (paragraphs 0002-0003, FIGS. 5 to 7)
[0004]
[Problems to be solved by the invention]
In the motor of Patent Document 1, the rotor magnet is provided by filling the magnet mounting hole by injection molding and solidifying. For this reason, the rotor magnet is a single plate that matches the shape of the magnet mounting hole and is curved in the rotational direction of the rotor.
[0005]
During the operation of the motor, the rotor is rotated while traversing the magnetic field generated by the stator. Therefore, a current (eddy current) flows through the rotor magnet due to a voltage induced according to the change in the magnetic flux. In this case, since the entire rotor magnet having a size corresponding to the magnet mounting hole is a single eddy current generation region, the value of the generated eddy current is large. This eddy current increases as the motor speed increases by increasing the strength of the magnetic field.
[0006]
When the eddy current loss increases, the motor efficiency is reduced, and the rotor magnet temperature rises due to the surreal heat caused by the eddy current, and the magnetic force of the rotor magnet may decrease (demagnetize). Therefore, in order to increase the rotation of the motor, a device for reducing the eddy current loss of the rotor magnet is required.
[0007]
Therefore, the present inventors have developed a rotor that can divide a rotor magnet of a predetermined size into a plurality of magnet pieces and reduce the value of eddy current generated in each magnet piece.
[0008]
However, this method requires a lot of labor to arrange each of the divided magnet pieces at a predetermined position of the magnet mounting hole, and magnetically separates adjacent magnet pieces with a magnetic insulator. Since it is necessary to consider not connecting, it has been found that there is a problem that it is difficult to manufacture the rotor.
[0009]
The problem to be solved by the present invention is to provide a motor which can reduce the eddy current loss of the rotor without impairing the manufacturability of the rotor and is suitable for increasing the rotation.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a rotor magnet arranged individually in each magnet mounting hole provided in the peripheral portion of the rotor core in the rotational direction or axial direction of the rotor or in a direction intersecting with these directions. It is divided into a plurality of magnet regions by one or more slits extending and closed at least at one end, and the magnet regions adjacent to the slits are opposite to the direction in which the slits extend from the closed ends of the slits. It is characterized by being continuously integrated with an extended portion consisting of an extended portion.
[0011]
In the present invention, the eddy current generated in each of the plurality of magnet areas subdivided by the slits of the rotor magnet can be reduced in accordance with the size of the area, and adjacent magnet areas are continuously connected to each other by the extension. Therefore, it can be handled as a single rotor magnet in assembling regardless of the subdivision.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
[0013]
Reference numeral 1 in FIG. 1 indicates an electric blower. The electric blower 1 is used by being incorporated in a vacuum cleaner body of an electric vacuum cleaner, for example. The electric blower 1 includes a motor 2 and a fan unit 32 having a centrifugal blower fan 31 driven by the motor 2.
[0014]
The motor 2 includes a motor frame 5. The motor frame 5 includes, for example, a bottomed cylindrical motor case 6 and an end plate 7 attached to cover the opening of the motor case 6. Each of the motor case 6 and the end plate 7 is provided with a ventilation portion (not shown) of a hole through which air blown from the fan portion 32 is circulated. A bearing 8 is attached to the motor case 6, and a bearing 9 is also attached to the end plate 7 corresponding to the bearing 8.
[0015]
The motor 2 includes a stator 11. The stator 11 is formed by attaching an exciting coil 13 to a stator core 12 in which a large number of stator core plates are laminated. The stator core 12 has a rotor through-hole 12a and has an annular shape, and has a plurality of salient poles protruding into the rotor through-hole 12a, and an exciting coil 13 is insulated and wound around each salient pole. ing. The exciting coil 13 forms a magnetic field when energized. The stator 11 is built in the motor case 6 and fixed by screws 14.
[0016]
The motor 2 has a rotor 21 arranged through the rotor through hole 12a. As shown in FIGS. 1 to 3, the rotor 21 includes a rotor core 22, a rotor shaft (rotating shaft) 23, and a plurality of rotor magnets 24.
[0017]
The rotor core 22 is formed by laminating a large number of rotor core plates having a circular outer peripheral shape. A plurality of, for example, four magnet mounting holes 22 a are provided in the peripheral portion of the rotor core 22 so as to penetrate the rotor core 22 in the stacking direction (the axial direction of the rotor 21). In the case of this embodiment, each magnet attachment hole 22 a has an arc shape along the peripheral surface of the rotor core 22. The rotor shaft 23 is attached through the center of the rotor core 22.
[0018]
As shown in FIG. 1, the rotor 21 is attached to the motor frame 5 with its rotor shaft 23 rotatably supported by bearings 8 and 9. In this supported state, the outer peripheral surface of the rotor core 22 and the tip end surface of the salient pole of the stator 11 are opposed to each other with a slight gap therebetween. The end of the rotor shaft 23 on the bearing 9 side projects through the end plate 7 and the bearing 9 and protrudes out of the motor frame 5.
[0019]
Each rotor magnet 24 fills the magnet mounting hole 22a and is disposed in the peripheral portion of the rotor core 22, and has a shape corresponding to the shape of the magnet mounting hole 22a, for example, a circular arc shape. Each rotor magnet 24 is magnetized along the thickness direction (the radial direction of the rotor 21), and the polarities of the convex curved surfaces of the rotor magnets 24 adjacent in the circumferential direction of the rotor 21 are different. 2 and 3, reference numeral 22b denotes a cover peripheral wall of the rotor core 22 that covers the convex curved surface of the rotor magnet 24. The cover peripheral wall 22b supports the centrifugal force acting on the rotor magnet 24 during high-speed rotation. It has become.
[0020]
A plastic magnet can be suitably used for each rotor magnet 24. As the plastic magnet, for example, a rare earth magnet formed by using a magnet material obtained by mixing a neodymium / iron / boron magnet powder having a large coercive force and a synthetic resin powder such as 12 nylon can be used.
[0021]
The rotor magnet 24 is formed in a predetermined shape in advance and is fixed to the magnet mounting hole 22a using an adhesive (not shown). As shown in FIGS. 4A and 4B, each rotor magnet 24 has a substantially square shape in front view and an arc shape in plan view corresponding to the shape of the magnet mounting hole 22a. Further, the rotor magnet 24 is divided into a plurality of magnet regions 24b by providing one or more slits 24a, for example. In the case of this embodiment, the slit 24a is provided to extend in the axial direction of the rotor 21, one end of which is divided into one side of the rotor magnet 24 and opened to this one side, and the other end is closed. . The magnet regions 24b adjacent to each other with the slit 24a as a boundary are extended portions 24c composed of portions extending in the direction opposite to the direction in which the slits extend from the closed end 24ae of the slits 24a, in other words, from the closed end 24ae to the rotor magnet 24. It is continuously integrated in the region of the shortest distance over the other side 24d. The length of the extension 24c is preferably equal to or shorter than the width of each magnet region 24b extending in the axial direction of the rotor 21 (the dimension in the direction perpendicular to the extending direction).
[0022]
For example, the rotor magnet 24 having the above-described configuration is press-fitted into the magnet attachment hole 22a with one side opened by the slit 24a in a state in which an uncured adhesive is supplied to the magnet attachment hole 22a. It is tightly inserted into and bonded. In this case, since the slit 24a can be used as an adhesive reservoir, the amount of adhesive used can be easily managed. Further, when an aversive adhesive is used, an object in which the rotor magnet 24 is fitted in the magnet mounting hole 22a in advance is placed under a negative pressure environment, and the apathetic adhesive is supplied to the magnet mounting hole 22a. By doing so, it can be bonded.
[0023]
As shown in FIG. 1, the fan portion 32 includes the rectifying plate 33 screwed to the end plate 7 and the air blower attached to the end portion of the rotor shaft 23 protruding from the motor frame 5 using a nut 30. A fan 31 and a fan cover 34 that covers the blower fan 31 and the current plate 33 and is fitted on the outer periphery of the opening end of the motor case 6 are provided. The fan cover 34 has an air inlet 34a at the center.
[0024]
Reference numeral 35 in FIG. 1 denotes a ring-shaped printed wiring board built in the motor frame 5, to which a position sensor such as a hall element (not shown) facing the end surface of the rotor magnet 24 is attached. The rotational position of the rotor 21 is detected by this sensor.
[0025]
The inner rotor type brushless motor 2 having the above configuration controls the rotation of the rotor 21 by controlling the current applied to the exciting coil 13 by a motor driver (not shown) based on the detection signal of the position sensor. It has become. By driving the motor 2, in the electric blower 1, the blower fan 31 is rotated together with the rotor 21, so that air discharged from the blower fan 31 is sucked into the blower fan 31 through the air inlet 34 a. Then, after being introduced into the motor frame 5 through the rectifying plate 33, it is possible to perform an air blowing operation in which the stator 11 and the rotor 21 and the like are cooled and discharged to the outside from the ventilation portion of the motor frame 5.
[0026]
Incidentally, since the rotor 21 crosses the magnetic field created by the exciting coil 13 as the motor 2 is driven, an eddy current is generated in the rotor magnet 24.
[0027]
However, since the rotor magnet 24 is divided into a plurality of magnet regions 24b by the slits 24a, the entire rotor magnet does not become a single eddy current generation region, and each of the magnet regions 24b subdivided by the slits 24a. It becomes the eddy current generation region.
[0028]
Thereby, since the value of the eddy current generated in each magnet region 24b can be reduced, the eddy current loss is reduced and the reduction in motor efficiency can be suppressed. Furthermore, since the generation of Joule heat in each magnet region 24b is suppressed as the eddy current becomes smaller, it is possible to suppress the temperature of the rotor magnet 24 from rising excessively. As a result, the possibility of demagnetizing the rotor magnet 24 due to heat can be eliminated, and even if the rotor magnet 24 is a plastic magnet, the possibility of being softened by heat can be eliminated. Since the eddy current loss of the rotor magnet 24 can be reduced as described above, it is suitable for increasing the speed of the motor 2 by increasing the strength of the magnetic field.
[0029]
In the vacuum cleaner in which the electric blower 1 is incorporated, if the outside air temperature is high and the filter in the dust collecting part is clogged, the air sucked into the intake port 34a is continued. As a result, the air cooling performance of the motor 2 is lowered, and thus the temperature of the rotor magnet 24 is also increased. Even in such a usage state, as described above, the heat generation of the rotor magnet 24 due to the eddy current loss is suppressed, so that the temperature of the rotor magnet 24 can be suppressed from being excessively increased.
[0030]
In addition, although the rotor magnet 24 is subdivided into a plurality of magnet regions 24b, the adjacent magnet regions 24b are integrally continuous via the extension 24c. With this configuration, the rotor magnet 24 can be handled as a single component, and adjacent magnet regions 24b can be held so as not to contact each other by the slit 24a.
[0031]
For this reason, in the manufacture of the rotor 21, not only the magnet mounting hole 22a can be easily fitted into the rotor magnet 24, but also the need to keep the adjacent magnet regions 24b away from each other by a magnetic insulator is not necessary. Therefore, it is easy to manufacture the rotor 21.
[0032]
Hereinafter, second to fourth embodiments of the present invention will be described. Since these embodiments basically have the same configuration as the first embodiment, the same components are denoted by the same reference numerals as those of the first embodiment, description of the configuration and operation thereof is omitted, and different portions are described. To do.
[0033]
5 and 6 show a second embodiment. In the second embodiment, when a rotor magnet 24 provided with slits 24a extending in the rotation direction of the rotor 21 is used and the rotor 21 is viewed from the side surface, the subdivided magnet regions 24b are formed in the rotor 21. The magnet 24 is disposed in the magnet mounting hole 22a using an adhesive or the like in a posture orthogonal to the axial direction. Except for this configuration, the configuration is the same as that of the first embodiment including the configuration not shown in FIGS. 5 and 6.
[0034]
Therefore, also in the second embodiment, since the rotor magnet 24 having the slit 24a, the magnet region 24b, and the extension 24c is used, the same operation as the first embodiment is obtained, and the problem of the present invention Can be solved.
[0035]
7 and 8 show a third embodiment. In the third embodiment, a flat rotor magnet 24 having slits 24a extending in the axial direction of the rotor 21 is used. Accordingly, the magnet mounting hole 22a of the rotor core 22 has a hole structure without being curved. The rotor magnet 24 is provided by injection molding in the magnet mounting hole 22a.
[0036]
In this injection molding, the rotor core 22 is inserted into a mold of the injection molding machine and the mold is clamped. By this clamping, a molding space corresponding to the shape of the rotor magnet 24 shown in FIG. 8 is formed in the magnet mounting hole 22a. Thereafter, a molten magnet material is injected into the molding space and filled in each magnet mounting hole 22a. Next, the mold is cooled to solidify the magnet material filled in the magnet mounting hole 22a.
[0037]
Thus, the rotor magnet 24 having the shape shown in FIG. 8 is formed by extending the slit 24a and each magnet region 24b in the stacking direction of the rotor core 22 (in other words, the axial direction of the rotor 21). Bonded to the magnet mounting hole 22a. Except for the configuration described above, the configuration is the same as that of the first embodiment including the configuration not shown in FIGS. 7 and 8.
[0038]
Accordingly, also in the third embodiment, the rotor magnet 24 injection-molded in the magnet mounting hole 22a has the slit 24a, the magnet region 24b, and the extension portion 24c, and thus is the same as in the first embodiment. Thus, the problems of the present invention can be solved.
[0039]
FIG. 9 shows a fourth embodiment. In this embodiment, the rotor magnet 24 having slits 24a extending in a direction intersecting the axial direction or the rotation direction of the rotor, for example, diagonal slits 24a extending in a diagonal direction of the rotor magnet 24 and intersecting each other is used. ing. Both ends of the slit 24a are closed. Each extension 24c is formed by a region extending from the closed end 24ae of the slit 24a to the corner 24e of the rotor magnet 24 having the shortest distance from the closed end 24ae. Except for the configuration described above, the configuration is the same as that of the first embodiment, including the configuration not shown in FIG.
[0040]
Therefore, also in the fourth embodiment, since the rotor magnet 24 has a configuration including the slit 24a, the magnet region 24b, and the extension portion 24c, the same operation as the first embodiment is obtained, and the problem of the present invention Can be solved.
[0041]
The present invention is not limited to the above embodiments. The rotor magnet shown in the first embodiment can also be provided in the magnet mounting hole by injection molding, and the rotor magnet shown in the third embodiment is molded in advance by outsert molding, It is also possible to fix the adhesive using an adhesive. The rotor magnet may be arcuate or flat.
[0042]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the eddy current loss of a rotor can be made small without impairing the manufacturability of a rotor, and the motor suitable for improving rotation can be provided.
[Brief description of the drawings]
FIG. 1 is a side view showing a partial cross section of an electric blower including a motor according to a first embodiment of the present invention.
FIG. 2 is a side view showing a partial cross section of a rotor included in the motor of FIG. 1;
3 is a front view showing the rotor of FIG. 2 with a partial cross section. FIG.
4A is a front view showing a rotor magnet included in the rotor of FIG. 2; FIG. FIG. 5B is a bottom view showing the rotor magnet of FIG.
FIG. 5 is a front view showing a partial cross section of a rotor included in a motor according to a second embodiment of the present invention.
6A is a front view showing a rotor magnet included in the rotor of FIG. 5; FIG. FIG. 7B is a bottom view showing the rotor magnet of FIG.
FIG. 7 is a front view showing a partial cross section of a rotor included in a motor according to a third embodiment of the present invention.
8 is a front view showing a rotor magnet included in the rotor of FIG. 7;
FIG. 9 is a front view showing a rotor magnet of a rotor provided in a motor according to a fourth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 2 ... Motor, 5 ... Motor frame, 11 ... Stator, 12 ... Stator core, 12a ... Rotor through-hole, 13 ... Excitation coil, 21 ... Rotor, 22 ... Rotor core, 22a ... Magnet mounting hole, 23 ... Rotor shaft (rotary shaft) 24a rotor magnet 24a slit 24ae closed end 24b magnet region 24c extension

Claims (1)

A stator core having a rotor through hole in the center, an excitation coil mounted on the stator core, a motor frame that supports the stator, a rotor core having a plurality of magnet mounting holes in the periphery, and each of the magnet net mounting holes A rotor magnet individually disposed on the motor frame, and a rotor that is passed through the rotor through-hole and rotatably supported by the motor frame.
Each rotor magnet is
One or more slits extending in the rotational direction or axial direction of the rotor or in a direction crossing these directions and closed at least at one end;
A plurality of magnet areas separated by the slits;
A motor having a portion that extends in a direction opposite to the direction in which the slit extends from the closed end of the slit, and that extends adjacent magnet regions integrally with the slit as a boundary. .

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