JP2004274860A - Rotor and brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotor in which a magnetizing position can be easily magnetized without limiting the magnetizing position while improving a fixing force by providing an engaging part on the inner peripheral surface of the fixing surface of a ring magnet. <P>SOLUTION: The ring magnet 6 made of a pole orienting magnet magnetized so that poles appear only on the outer peripheral surface 6a of the ring magnet 6 is fixed to a collar 5 provided so as to be rotated integrally with a rotating shaft 4 in the rotor 3. The collar 5 has an outer peripheral surface 5b of substantially circular shape as seen from an axial direction and an engaging recess part 5c on the outer peripheral surface 5b. The ring magnet 6 has an inner peripheral surface 6b of substantially circular shape as seen from the axial direction to be fixed to the outer peripheral surface 5b of the collar 5 and an engaging protrusion part 6c engaged with the engaging recess part 5c of the collar 5 on the inner peripheral surface 6b. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rotor provided with a ring magnet composed of a poled magnet and a brushless motor provided with the rotor.
[0002]
[Prior art]
As a rotor of a brushless motor, for example, as shown in Patent Document 1 (FIG. 6 (b)), a cylindrical magnet (ring magnet) composed of a polar oriented magnet such as a polar anisotropic magnet is used. There are things to be done. This rotor is configured such that a cylindrical magnet made of a poled magnet is externally fitted and fixed to a substantially cylindrical rotor core. Cylindrical magnets composed of polar-oriented magnets are magnetized such that N-poles and S-poles appear at equal intervals only on the outer peripheral surface, which is the surface facing the stator. The magnetic flux density at the center of the contributing magnetic pole is high. Therefore, as compared with a known radially oriented magnet (FIG. 6 (a) of Patent Document 1) in which the N and S magnetic poles are magnetized so as to appear on both the outer circumferential surface and the inner circumferential surface, the motor has the same size. If the torque is high and the motor torque is the same, the size of the magnet can be reduced, and the size of the motor can be reduced.
[0003]
By the way, when the rotor rotates, a force acts on the cylindrical magnet so as to shift in the rotational direction with respect to the rotor core. Therefore, an adhesive is generally used between the core and the magnet in order to improve the fixing force of the cylindrical magnet to the core, particularly the engaging force in the rotational direction. However, there is a problem that the operation using the adhesive is not only time-consuming, but also the fixing with the adhesive has low reliability.
[0004]
Here, as shown in FIG. 2 of Patent Document 2, the inner peripheral surface shape of the cylindrical magnet is a regular octagon (regular polygon), and an elastic member (the rotor core) fitted inside the cylindrical magnet. Similarly, the outer peripheral surface shape is also a regular octagon, so that the cylindrical magnet and the elastic member are engaged in the rotational direction.
[0005]
Such a technique is used in Patent Document 1 described above, and the outer peripheral surface of the rotor core and the inner peripheral surface of the cylindrical magnet are formed in a regular polygonal shape so that the cylindrical magnet and the rotor core are engaged in the rotation direction. In this case, the engaging force in the same direction is improved, and the fixing force of the cylindrical magnet to the core is improved, so that the adhesive can be omitted.
[0006]
[Patent Document 1]
JP-A-11-146618 [Patent Document 2]
JP-A-8-65932
[Problems to be solved by the invention]
By the way, the cylindrical magnet shown in Patent Document 1 is composed of a pole-oriented magnet that is magnetized so that magnetic poles appear only on the outer peripheral surface. , And then form an arc toward the inner peripheral surface side and then toward the center of the adjacent magnetic pole.
[0008]
On the other hand, when the inner peripheral surface of the cylindrical magnet is formed in a regular polygonal shape as described above, the corners of the polygon have a shape that bites into the magnet (toward the outside in the radial direction). The radial width of the formed portion becomes smaller than that of the other portions, and becomes a magnetic resistance portion that blocks the flow of the magnetic flux that straddles the corner portion. Therefore, unless the position of the magnetic pole of the cylindrical magnet is set in consideration of the position of the corner, the magnetic efficiency of the magnet is reduced.
[0009]
The present invention has been made to solve the above problems, and an object of the present invention is to provide an engaging portion on an inner peripheral surface, which is a fixing surface of a ring magnet, to improve a fixing force while improving a fixing force. It is an object of the present invention to provide a rotor capable of easily performing magnetization without limiting the position, and a brushless motor including the rotor.
[0010]
[Means for Solving the Problems]
In order to solve the above problem, the invention according to claim 1 is configured such that a rotating shaft, a collar provided to rotate integrally with the rotating shaft, and a magnetic pole that is fixed to the collar and appears only on the outer peripheral surface. A ring magnet made of a poled magnet to be magnetized, wherein the collar has a substantially circular outer peripheral surface as viewed from the axial direction and has an engaging recess on the outer peripheral surface, The ring magnet has a substantially circular inner peripheral surface as viewed from the axial direction to be fixed to the outer peripheral surface of the collar, and has an engaging convex portion on the inner peripheral surface for engaging with the engaging concave portion of the collar. are doing.
[0011]
According to a second aspect of the present invention, in the rotor according to the first aspect, the ring magnet is arranged such that the engagement projection is located on a radial straight line passing through a magnetic pole center portion appearing on an outer peripheral surface thereof. It is magnetized.
[0012]
According to a third aspect of the present invention, in the rotor according to the first or second aspect, the magnetic poles of the ring magnet are provided at equal intervals, and the plurality of engaging concave portions and the plurality of engaging convex portions are provided. They are provided and arranged at equal intervals.
[0013]
According to a fourth aspect of the present invention, in the rotor according to the third aspect, the number of the engaging concave portions and the number of the engaging convex portions are equal to the number of poles of the ring magnet.
A fifth aspect of the present invention is a brushless motor including the rotor according to any one of the first to fourth aspects, and a stator that generates a rotating magnetic field to rotate the rotor.
[0014]
(Action)
According to the first aspect of the present invention, the rotor has a ring magnet made of a pole-oriented magnet that is magnetized so that a magnetic pole appears only on the outer peripheral surface with respect to a collar provided so as to rotate integrally with the rotation shaft. It is fixed. The collar has a substantially circular outer peripheral surface as viewed from the axial direction, and has an engagement recess on the outer peripheral surface. The ring magnet has a substantially circular outer shape as viewed from the axial direction to be fixed to the outer peripheral surface of the collar. It has a peripheral surface and has an engaging convex portion on the inner peripheral surface for engaging with the engaging concave portion of the collar. The ring magnet is firmly fixed to the collar by the engagement of the engagement protrusion provided on the inner peripheral surface with the engagement recess provided on the outer peripheral surface of the collar in the rotation direction. Moreover, in this ring magnet, the magnetic flux inside the ring forms an arc shape from the center of the magnetic pole on the outer peripheral surface of the magnet to the inner peripheral surface once, and then toward the center of the adjacent magnetic pole. Since the engaging projections provided on the inner peripheral surface to improve the contact force do not bite into the magnet (toward the outside in the radial direction), the portions provided with the engaging projections are magnetic resistances which obstruct the flow of magnetic flux. Does not. That is, regardless of the position of the engaging projection at any position in the circumferential direction of the inner peripheral surface, the influence on the magnetic flux in the ring magnet is extremely small. Therefore, the ring magnet can be easily magnetized without limiting the magnetizing position.
[0015]
According to the second aspect of the present invention, the ring magnet is magnetized such that the engaging projection is located on a radial straight line passing through the center of the magnetic pole appearing on the outer peripheral surface. That is, from the flow of the magnetic flux in the ring magnet composed of the poled magnet, the vicinity of the engagement convex portion on the inner peripheral surface is a portion where the magnetic flux density is low. Therefore, even if the ring magnet is slightly affected by the provision of the engagement protrusion, the influence can be reduced more reliably.
[0016]
According to the third aspect of the invention, the magnetic poles of the ring magnet are provided at equal intervals, and a plurality of engaging concave portions and engaging convex portions are provided and arranged at equal intervals. That is, since the collar and the ring magnet are engaged at equal intervals in the rotation direction, they can be stably engaged with each other in the rotation direction. Even if the ring magnet is slightly affected by the provision of the engaging projection, the influence on the magnet can be distributed at equal intervals in the rotation direction.
[0017]
According to the fourth aspect of the present invention, the number of the engaging concave portions and the engaging convex portions is equal to the number of poles of the ring magnet. That is, in the ring magnet, one engagement projection corresponds to one magnetic pole, and the position of each engagement projection is arranged at the same position with respect to each magnetic pole. Therefore, it is possible to prevent a difference from occurring for each magnetic pole.
[0018]
According to the fifth aspect of the present invention, since the fixing force of the ring magnet is improved, it is possible to reliably prevent the magnet from falling off, and it is possible to contribute to extending the life of the brushless motor. In addition, since it is possible to easily magnetize the ring magnet without limiting the magnetizing position, it is possible to contribute to facilitating the manufacture of the ring magnet and, consequently, the manufacture of the brushless motor.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram of the brushless motor 1. The brushless motor 1 includes an annular stator 2 and a rotor 3 rotatably housed inside the stator 2. Although not shown, the stator 2 is configured such that a winding is wound around teeth of a stator core, and a driving current is supplied to the winding to generate a rotating magnetic field for rotating the rotor 3.
[0020]
The rotor 3 includes a rotating shaft 4, a collar 5, and a ring magnet 6, as shown in FIGS. The collar 5 is formed in a substantially disk shape using a metal material such as iron. A circular through-hole 5a is formed in the center of the collar 5 when viewed from the axial direction, and the rotary shaft 4 is press-fitted and fixed in the through-hole 5a. The outer peripheral surface 5b of the collar 5 is a fixing surface of the ring magnet 6, and is formed in a substantially circular shape when viewed from the axial direction. On the outer peripheral surface 5b, eight engaging concave portions 5c having the same shape are formed at equal intervals in the circumferential direction (rotation direction). The engagement recess 5c has a semicircular cross section and penetrates in the axial direction. The ring magnet 6 is press-fitted and fixed to the outer peripheral surface 5b of the collar 5.
[0021]
The ring magnet 6 has a ring shape (annular shape). The outer peripheral surface 6a of the ring magnet 6, that is, the surface facing the stator 2 has a circular shape when viewed from the axial direction. The inner peripheral surface 6b of the ring magnet 6 is a fixing surface of the collar 5, and has a shape corresponding to the outer peripheral surface 5b so as to be externally fitted (press-fitted) to the outer peripheral surface 5b of the collar 5. That is, the inner peripheral surface 6b of the ring magnet 6 is formed in a substantially circular shape when viewed from the axial direction, and eight engaging projections 6c having the same shape are formed on the inner peripheral surface 6b in the circumferential direction (rotation direction). They are formed at equal intervals. The engaging projection 6c has a semicircular cross section and is continuous in the axial direction. Incidentally, the number of engaging projections 6c provided on the inner peripheral surface 6b of the ring magnet 6 and the number of engaging concave portions 5c provided on the outer peripheral surface 5b of the collar 5 are the same as the number of poles "8" of the ring magnet 6 described later. And The ring magnet 6 rotates relative to the collar 5 by engaging the engaging protrusion 6c provided on the inner peripheral surface 6b with the engaging recess 5c provided on the outer peripheral surface 5b of the collar 5 in the rotational direction. It is firmly fixed.
[0022]
Further, the ring magnet 6 is formed of a polar orientation magnet in which a magnetic pole (N pole S pole) appears only on the outer peripheral surface 6a which is a polar anisotropic magnet or a polar isotropic magnet. By the way, the polar anisotropic magnet is arranged in the direction in which it is desired to magnetize by applying an external magnetic field to a magnetic powder having a uniform magnetic direction, and after being manufactured by compression or injection molding, polar orientation is performed in accordance with the previous direction. It is a magnet that is completed by magnetization and is a powerful magnet. On the other hand, a polar isotropic magnet is a magnet that is manufactured by compressing or injection-molding a magnetic powder having a non-uniform magnetic direction and then magnetizing it in an arbitrary polar orientation, which is relatively easy to manufacture. it can. Neodymium iron boron or samarium iron nitrogen is used for both magnets as the material of the magnetic powder.
[0023]
In the ring magnet 6, the magnetic poles are arranged at equal intervals and the number of poles is "8" so as to be separated by a boundary line L0 of the magnetic poles shown by a broken line in FIG. In the ring magnet 6, the flow of the magnetic flux A inside (indicated by the arrow in FIG. 1) is once directed from the magnetic pole central portion 6d of the outer peripheral surface 6a to the inner peripheral surface 6b and then toward the adjacent magnetic pole central portion 6d. It is magnetized so as to form an arc shape, and magnetized so that a magnetic pole appears only on the outer peripheral surface 6a. In this case, the magnetizing is performed such that the engaging projection 6c is located on the radial straight line L1 passing through the magnetic pole center portion 6d appearing on the outer peripheral surface 6a.
[0024]
Here, since the engaging projection 6c provided on the inner peripheral surface 6b to improve the fixing force of the ring magnet 6 does not bite into the magnet 6 (toward the outside in the radial direction), the engaging projection 6c is formed. Is not a magnetic resistance that hinders the flow of the magnetic flux A. That is, even if the engaging projection 6c is provided at any position in the circumferential direction of the inner peripheral surface 6b, the influence on the magnetic flux A in the ring magnet 6 is extremely small. Therefore, the ring magnet 6 can be easily magnetized without limiting the magnetizing position.
[0025]
Further, as described above, the engaging projection 6c is located on the radial straight line L1 that passes through the magnetic pole center portion 6d that appears on the outer peripheral surface 6a. That is, from the flow of the magnetic flux A in the ring magnet 6 composed of the polar orientation magnet, the vicinity of the engagement convex portion 6c on the inner peripheral surface 6b is a portion where the magnetic flux density is low. For this reason, even if the ring magnet 6 is slightly affected by the provision of the engagement protrusion 6c, the influence is more reliably reduced.
[0026]
Incidentally, in the rotor 3 configured as described above, the ring magnet 6 before magnetization is first pressed into the collar 5 and fixed thereto, and then the ring magnet 6 is magnetized by the magnetizing device (not shown) as described above. Then, the rotating shaft 4 is press-fitted into the collar 5 and completed.
[0027]
Next, the characteristic operation and effect of the present embodiment will be described below.
(1) The rotor 3 is provided with a ring magnet 6 made of a pole-oriented magnet which is magnetized so that a magnetic pole appears only on an outer peripheral surface 6a with respect to a collar 5 provided so as to rotate integrally with the rotating shaft 4. Become. The collar 5 has a substantially circular outer peripheral surface 5b as viewed from the axial direction, and has an engaging recess 5c on the outer peripheral surface 5b. The ring magnet 6 has a substantially circular inner peripheral surface 6b viewed from the axial direction to be fixed to the outer peripheral surface 5b of the collar 5, and engages with the engaging concave portion 5c of the collar 5 on the inner peripheral surface 6b. It has a convex part 6c. The ring magnet 6 rotates relative to the collar 5 by engaging the engaging protrusion 6c provided on the inner peripheral surface 6b with the engaging recess 5c provided on the outer peripheral surface 5b of the collar 5 in the rotational direction. It is firmly fixed. In addition, the ring magnet 6 has an inner magnetic flux A that forms an arc shape from the magnetic pole central portion 6d of the outer peripheral surface 6a of the magnet 6 to the inner peripheral surface 6b and then to the adjacent magnetic pole central portion 6d. However, since the engaging projection 6c provided on the inner peripheral surface 6b for improving the fixing force of the magnet 6 does not bite into the magnet 6 (toward the outside in the radial direction), the engaging projection 6c Is not a magnetic resistance that hinders the flow of the magnetic flux A. That is, even if the engaging projection 6c is provided at any position in the circumferential direction of the inner peripheral surface 6b, the influence on the magnetic flux A in the ring magnet 6 is extremely small. Therefore, the ring magnet 6 can be easily magnetized without limiting the magnetizing position.
[0028]
(2) Since the fixing force of the ring magnet 6 is improved, it is possible to reliably prevent the magnet 6 from falling off, and it is possible to contribute to extending the life of the brushless motor 1. In addition, since it is possible to easily magnetize the ring magnet 6 without limiting the magnetizing position, it is possible to contribute to facilitating the manufacture of the ring magnet 6 and the manufacturing of the brushless motor 1. .
[0029]
(3) The ring magnet 6 is magnetized such that the engaging projection 6c is located on a radial straight line L1 passing through the magnetic pole center portion 6d that appears on the outer peripheral surface 6a. That is, from the flow of the magnetic flux A in the ring magnet 6 composed of the polar orientation magnet, the vicinity of the engagement convex portion 6c on the inner peripheral surface 6b is a portion where the magnetic flux density is low. For this reason, even if the ring magnet 6 is slightly affected by the provision of the engagement convex portion 6c, the influence can be reduced more reliably.
[0030]
(4) The magnetic poles of the ring magnet 6 are provided at equal intervals, and a plurality of (eight as many as the number of magnetic poles “8”) engaging recesses 5c and engaging protrusions 6c are provided and arranged at equal intervals. Have been. That is, since the collar 5 and the ring magnet 6 are engaged at equal intervals in the rotational direction, they can be stably engaged with each other in the rotational direction. Further, even if the ring magnet 6 is slightly affected by providing the engagement convex portion 6c, the influence on the magnet 6 can be dispersed at equal intervals in the rotation direction.
[0031]
(5) The number of engaging projections 6c (engaging recesses 5c) is equal to the number of poles of the ring magnet 6. In other words, in the ring magnet 6, one engagement projection 6c corresponds to one magnetic pole, and the position of each engagement projection 6c is arranged at the same position for each magnetic pole. . Therefore, it is possible to prevent a difference from occurring for each magnetic pole.
[0032]
(6) The ring magnet 6 is fitted around the collar 5 and fixed to the collar 5. Therefore, since the ring magnet 6 and the collar 5 can be formed separately, they can be easily formed.
[0033]
Note that the embodiment of the present invention may be modified as follows.
In the above embodiment, the number of poles of the ring magnet 6 is “8”, but the number of poles is not limited to this, and may be changed as appropriate. Although the magnetic poles are provided at equal intervals, the magnetic poles need not be at equal intervals.
[0034]
In the above-described embodiment, the number of the engagement protrusions 6c of the ring magnet 6 and the number of the engagement recesses 5c of the collar 5 are eight, which is the same as the number of poles “8” of the magnet 6, but the engagement protrusion 6c and the engagement recess The number of 5c may not be the same as the number of poles of the magnet 6. In addition, although the engaging projections 6c and the engaging recesses 5c are arranged at equal intervals, they may not be at equal intervals. In addition, the engaging protrusion 6c is arranged on the radial straight line L1 passing through the magnetic pole center portion 6d appearing on the outer peripheral surface 6a. For example, as shown in FIG. 6c may be arranged. Further, although the engaging convex portion 6c and the engaging concave portion 5c have a semicircular cross section, they are not limited to this shape, and may be changed to, for example, a triangular cross section or a quadrangular cross section.
[0035]
In the above-described embodiment, the ring magnet 6 is fixed to the collar 5 by externally fitting the ring magnet 6 to the collar 5. However, the ring magnet 6 is fixed to the collar 5 by integrally molding the ring magnet 6 with the collar 5. You may make it. By doing so, the number of components of the rotor 3 and thus the motor 1 can be reduced.
[0036]
In the above-described embodiment, the ring magnet 6 is magnetized after being fixed to the collar 5, but may be magnetized beforehand before being fixed to the collar 5.
[0037]
In the above embodiment, the collar 5 is made of a metal material such as iron, but may be changed to a magnetic metal material other than iron, a non-magnetic metal material, a resin material, or the like. In this case, since the ring magnet 6 is a polar orientation magnet in which the magnetic flux A flows from the outer peripheral surface 6a to the outer peripheral surface 6a, even if the collar 5 is changed to a non-magnetic material, it does not affect the output of the motor 1. . Alternatively, the collar 5 may be made of a metal material on the inner diameter side (the rotating shaft 4 side) and a resin material on the outer diameter side (the outer peripheral surface 5b side). Further, although the rotating shaft 4 is press-fitted into the collar 5 and the collar 5 rotates integrally with the rotating shaft 4, the rotating shaft 4 may be integrally formed with the collar 5.
[0038]
The ring magnet 6 of the above embodiment may be used for a rotor having a configuration other than the rotor 3.
In the above embodiment, the present invention is applied to the rotor 3 of the brushless motor 1, but may be applied to the rotor of a motor other than the brushless motor 1.
[0039]
The technical ideas that can be grasped from the above embodiments are described below.
(B) In the rotor according to any one of claims 1 to 4,
The rotor according to claim 1, wherein the ring magnet is fitted over the collar and fixed to the collar.
[0040]
With this configuration, the ring magnet and the collar can be formed separately, so that they can be easily formed.
(B) The rotor according to any one of claims 1 to 4,
The rotor, wherein the ring magnet is formed integrally with the collar and is fixed to the collar.
[0041]
By doing so, the number of parts of the rotor can be reduced.
(C) a ring magnet that is provided on the rotor and is made of a pole-oriented magnet that is magnetized so that magnetic poles appear only on the outer peripheral surface,
The rotor has a substantially circular outer peripheral surface as viewed from the axial direction and has a collar having an engagement recess on the outer peripheral surface,
A substantially circular inner peripheral surface as viewed from the axial direction is provided as a fixing surface to be fixed to the outer peripheral surface of the collar, and the inner peripheral surface has an engaging projection that engages with the engaging concave portion of the collar. A ring magnet.
[0042]
With this configuration, the ring magnet is firmly fixed to the collar by the engagement convex portion provided on the inner peripheral surface and the engagement concave portion provided on the outer peripheral surface of the collar being engaged in the rotational direction. Is done. Moreover, in this ring magnet, the magnetic flux inside the ring forms an arc shape from the center of the magnetic pole on the outer peripheral surface of the magnet to the inner peripheral surface once, and then toward the center of the adjacent magnetic pole. Since the engaging projections provided on the inner peripheral surface to improve the contact force do not bite into the magnet (toward the outside in the radial direction), the portions provided with the engaging projections are magnetic resistances which obstruct the flow of magnetic flux. Does not. That is, regardless of the position of the engaging projection at any position in the circumferential direction of the inner peripheral surface, the influence on the magnetic flux in the ring magnet is extremely small. Therefore, the ring magnet can be easily magnetized without limiting the magnetizing position.
[0043]
【The invention's effect】
As described in detail above, according to the present invention, the magnetizing portion can be easily magnetized without limiting the magnetizing position while providing the engaging portion on the inner peripheral surface which is the fixing surface of the ring magnet to improve the fixing force. And a brushless motor provided with the rotor.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a brushless motor having a rotor according to an embodiment.
FIG. 2 is a perspective view of a collar and a ring magnet constituting a rotor.
FIG. 3 is a schematic configuration diagram of another example of a rotor.
[Explanation of symbols]
2 stator, 3 rotor, 4 rotating shaft, 5 collar, 5b outer peripheral surface, 5c engagement recess, 6 ring magnet, 6a outer peripheral surface, 6b inner peripheral surface, 6c engagement convex portion , 6d: magnetic pole center portion, L1: straight line.

Claims (5)

A rotation axis,
A collar provided to rotate integrally with the rotation shaft,
A ring magnet consisting of a pole-oriented magnet fixed to the collar and magnetized so that a magnetic pole appears only on the outer peripheral surface;
A rotor with
The collar has a substantially circular outer peripheral surface as viewed from the axial direction and has an engaging recess on the outer peripheral surface,
The ring magnet has a substantially circular inner peripheral surface as viewed from the axial direction to be fixed to the outer peripheral surface of the collar, and has an engaging convex portion on the inner peripheral surface for engaging with the engaging concave portion of the collar. A rotor characterized in that: The rotor according to claim 1,
The ring magnet is characterized in that the ring magnet is magnetized such that the engaging projection is located on a radial straight line passing through a magnetic pole center portion appearing on an outer peripheral surface thereof. The rotor according to claim 1 or 2,
The magnetic poles of the ring magnet are provided at equal intervals,
A plurality of the engaging concave portions and the engaging convex portions are provided and arranged at equal intervals. The rotor according to claim 3,
The rotor according to claim 1, wherein the number of the engaging concave portions and the number of the engaging convex portions are equal to the number of poles of the ring magnet. A rotor according to any one of claims 1 to 4,
A stator for generating a rotating magnetic field to rotate the rotor,
A brushless motor comprising:

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