JP2002124414A - Method of magnetizing rare-earth magnet and method of manufacturing rotating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of magnetizing a rare-earth magnet by which a plurality of rare-earth magnets fixed to a rotor can be magnetized strongly. SOLUTION: The method for magnetizing the rare-earth magnets 22 fixed to the rotor 20 includes a first step of successively performing first magnetization on the magnets 22 with a relatively weak first magnetic field and a second step of performing second magnetization on the magnets 22 with a second magnetic field which is oriented in the same direction as that of and stronger than the magnetic field used in the first step.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of magnetizing a rare earth magnet fixed to a rotor and a method of manufacturing a rotating machine.

[0002]

2. Description of the Related Art At present, two types of rare earth sintered magnets, samarium / cobalt magnets and neodymium / iron / boron magnets, are widely used in various fields. Among them, neodymium-iron-boron magnets (hereinafter referred to as "RT- (M) -B magnets". R is a rare earth element containing Y, T is iron, or iron and part of iron are Co, etc. Is a transition metal element, M is an additive element, and B is boron.) Shows the highest magnetic energy product among various magnets and is relatively inexpensive, so it is actively used in various electronic devices. Have been.
Recently, in order to obtain high energy efficiency, rare earth magnets are also used in rotating machines such as large motors and large generators for elevators and escalators.

In a large-sized rotating machine (ie, a motor or a generator), a plurality of thin-plate-shaped rare-earth magnets, such as an arc-shaped, a cam-shaped, or a flat plate, are formed along the circumferential direction on the outer peripheral surface of the rotor. Some use a fixed rotor assembly. In such a rotor assembly, rare-earth magnets having a relatively large size are often arranged close to each other with a small space therebetween. These rare earth magnets are arranged such that N poles and S poles are alternately formed along the circumferential direction of the rotor.

In manufacturing such a large-sized rotor assembly, if a rare-earth magnet magnetized in advance is to be bonded to the rotor, a strong repulsive force or attractive force acts between the rare-earth magnets, so that the bonding is performed with high positional accuracy. Will be difficult to do. Further, when fixing the rare earth magnet, the magnet may suddenly move due to being repelled or attracted by a strong force, which often involves danger. For this reason, it is desirable that the rare earth magnet be fixed to the rotor in a non-magnetized state, and thereafter, the magnetized be applied by applying a magnetic field to each fixed magnet in a predetermined direction.

As a method of magnetizing a rare earth magnet fixed to a rotor, a predetermined magnetic field is simultaneously applied to all the rare earth magnets by using a coil or the like provided so as to face each magnet, and all magnets are applied at once. Magnetizing rare earth magnets. Such an approach is appropriate for small rotor assemblies. However, in a large-sized rotor assembly, since the number of magnets is large and the size of the rare-earth magnet is large, it is difficult to magnetize these at the same time due to the capacity of a magnetizing power supply. For this reason, for a large rotor assembly, it is necessary to perform the magnetization of the rare earth magnet in a plurality of times.

FIG. 12 shows an example of a large rotor assembly. As shown in the figure, a large number of flat rare earth magnets 22 are fixed to the outer peripheral surface of the large rotor 20 by an adhesive or the like. The rare-earth magnets 22 are arranged along the circumferential direction of the rotor so as to form 32 poles (magnetic poles) at predetermined intervals. One magnetic pole is formed by arranging a plurality of rare earth magnets along the axial direction of the rotor.

Hereinafter, a magnetizing device for magnetizing a plurality of magnets fixed to the rotor 20 in a predetermined number will be described with reference to FIGS.

The magnetizing device 1 shown in FIG. 1 includes a magnetizing yoke 10 provided with a space (hole) 10a for accommodating a rotor 20, and a plurality of rare earth magnets 22 are provided in the space 10a. The bonded rotor 20 is inserted. The magnetizing yoke 10 of the magnetizing device 1 is provided with a plurality of magnetic field generators 12 arranged to face each of the plurality of rare earth magnets 22. As shown in FIG. 2, the magnetic field generation unit 12
The recess 14 provided in the magnetized yoke 10 is constituted by a coil 16 formed by winding a conductive wire having a diameter of, for example, 2.2 mm. Each of the magnetic field generators 12 configured as described above can generate a magnetic field H along the radial direction of the rotor 20. By controlling the direction of the magnetic field H, each magnet 22 is turned to the N pole side. Alternatively, it can be magnetized on the S pole side. In the present specification, “to be magnetized on the N pole side” means that the outer surface of the rare earth magnet 22 (the surface opposite to the rotor side) is N
This means that magnetization is performed so as to form a magnetic pole. Similarly, “to be magnetized on the S pole side” means to perform magnetization such that the outer surface of the rare earth magnet 22 forms an S pole magnetic pole after the magnetization.

FIG. 3 shows an example of a circuit for driving the magnetic field generator 12. In the drive circuit shown, the diode 3
1a, a power supply for magnetization (DC
Four coils (corresponding to four poles) are connected in series to the power supply 30 and four of the 32 magnetic field generators 12 (see FIG. 1) can be driven simultaneously. For example, the first, ninth, seventeenth, and twenty-fifth rare earth magnets can be simultaneously driven in the circumferential direction of the rotor to simultaneously drive the magnetic field generators 12, and selectively turn on the switch S1. By doing so, the electric charge accumulated in the capacitor 31b instantaneously flows through each coil connected to the switch S1. Switch the switch,
By sequentially applying current eight times while changing the rare earth magnet to be magnetized, it is possible to magnetize all magnets. If the magnetization is performed in this manner, the power required for each operation can be reduced.

[0010] In order to make the poles of adjacent magnets opposite, it is necessary to control the direction of generation of the magnetic field in each of the magnetic field generators. This can be easily achieved by reversing the winding direction of the coil in the magnetic field generating section where the opposite magnetic field is to be formed, or by wiring such that the direction of the current flowing through the coil is reversed. can do.

[0011]

In the magnetizing method using the magnetizing device 1, in order to sufficiently magnetize each rare-earth magnet 22, typically, the magnetic field generating unit 12 controls the magnetism to about 3T.
(Tesla) or a relatively strong magnetic field was generated. The magnetic field applied to the end of the plate-shaped magnet is smaller than the magnetic field applied to the center of the magnet. However, if such a relatively large magnetic field is generated, the saturation magnetization of the entire rare-earth magnet is reduced. Can be applied.

However, when the magnetization is performed in this manner, the magnetic field generated by the magnetic field generating unit 12 shown in FIG.
There is a problem that magnets on both sides of the magnet to be magnetized are also magnetized. When the N pole and the S pole of the magnet are alternately formed along the circumferential direction of the rotor, when a magnetic field is sequentially applied to the magnet by using the above-described method, at least a part of the magnet is formed. A magnetic field in the opposite direction to the direction that should be applied for magnetization (such a magnetic field is referred to as “reverse magnetic field” in this specification. The magnetic field is called "forward magnetic field".)
Is applied.

FIGS. 4 and 5 are diagrams showing what kind of magnetic field is applied to magnets around a certain magnet when the magnet is magnetized. As shown in FIG. 4, the magnetic flux generated by the magnetic field generator 12 penetrates the rare-earth magnet M <b> 1 to be magnetized in the radial direction of the rotor, and then flows in a ring. When the rare earth magnet M1 is magnetized by such a magnetic field, as shown in an enlarged view in FIG. 5, the ends of the magnets M2 and M3 on both sides are originally magnetized by the magnetic field applied to the magnet M1. Therefore, a reverse magnetic field in a direction opposite to the direction of the magnetic field to be applied is applied. According to the experiment of the present inventor, when the magnitude of the magnetic field applied to the center of the magnet M1 is set to about 5T, a forward magnetic field of about 2 to 3T is applied to both ends of the magnet M1, and It was found that a reverse magnetic field exceeding about 1T was applied to the ends of the magnets M2 and M3 on both sides. As shown in FIG. 4, the reverse magnetic field can be applied to magnets other than the magnets on both sides, but the magnitude of the reverse magnetic field is smaller than that for the magnets on both sides.
Hereinafter, the influence of the reverse magnetic field on the magnets on both sides will be mainly described.

When such a reverse magnetic field is applied, next,
By applying a forward magnetic field of about 5 T to the magnet M2 in a direction opposite to that applied to the magnet M1, even when the magnet is magnetized in the original magnetizing direction, the end of the magnet M2 has Proper magnetization is not performed due to the influence of the reverse magnetic field applied before that. As a result, a portion that is not subjected to saturation magnetization occurs particularly at the end of the magnet. When a rotor assembly is used for a rotating machine that has not been magnetized sufficiently, problems such as torque ripple, electromagnetic vibration, low efficiency, and demagnetization occur, and the performance of the rotating machine is significantly reduced. .

The present invention has been made in view of the above circumstances, and a main object thereof is to provide a method for appropriately magnetizing a plurality of rare earth magnets fixed to a rotor.

Another object of the present invention is to provide a method for manufacturing a suitable rotor assembly and rotating machine by using the above-mentioned magnetizing method.

[0017]

A method of magnetizing a rare earth magnet according to the present invention is a method of magnetizing a plurality of rare earth magnets fixed to a rotor. A first step of sequentially performing a first magnetization with a relatively weak first magnetic field, and sequentially having substantially the same orientation as the first magnetic field with respect to the plurality of rare earth magnets, Performing a second magnetization with a second magnetic field that is stronger than the second magnetic field.

In one embodiment, when the first magnetization is performed on a selected one of the plurality of rare-earth magnets, another rare-earth magnet adjacent to the selected one of the rare-earth magnets is used. Applying a first reverse magnetic field having a direction substantially opposite to the original magnetization direction to at least an end of the magnet, and applying a first reverse magnetic field to another rare earth magnet adjacent to the selected rare earth magnet. When performing the first magnetization, the portion to which the first reverse magnetic field is applied is magnetized in the original magnetization direction, so that the first magnetization in the same direction as the original magnetization direction is performed.
Giving a magnetization of

In a preferred embodiment, the strength of the inverse magnetic field at the end of another rare earth magnet adjacent to the selected rare earth magnet is adjusted to 1.0 Tesla or less.
In a more preferred embodiment, the strength of the reverse magnetic field is adjusted to 0.5 Tesla or less.

In a preferred embodiment, when the second magnetization is performed on a selected one of the plurality of rare-earth magnets, another rare-earth magnet adjacent to the selected one of the rare-earth magnets is used. At least to the end of the magnet, having a strength not to reverse the first magnetization;
Applying a second reverse magnetic field having a direction substantially opposite to the original magnetization direction, and performing the second magnetization on another rare earth magnet adjacent to the selected rare earth magnet A step of magnetizing the portion to which the second reverse magnetic field has been applied in the original magnetizing direction.

In a preferred embodiment, a direction in which the first magnetization and the second magnetization are performed on the selected rare earth magnet and another direction adjacent to the selected rare earth magnet are determined. The directions in which the first magnetization and the second magnetization are performed on the rare-earth magnet are substantially opposite to each other.

In a preferred embodiment, the first magnetization and the second magnetization are performed by a magnetic field formed by a plurality of magnetic field generating units provided to face each of the plurality of rare earth magnets, After the second step, the method further includes a third step in which the positions of the rare earth magnet and the magnetic field generating unit are shifted and then the magnetization is performed.

In a preferred embodiment, the magnetic field generator includes a coil, and the third step is performed in a state where an inner surface of the coil and an end of the rare earth magnet are substantially aligned in a radial direction of the rotor. .

In a preferred embodiment, the plurality of rare earth magnets are fixed on the outer peripheral surface of the rotor, and the thickness of the end of each rare earth magnet is smaller than the thickness of the center of the rare earth magnet. .

[0025] In a preferred embodiment, a protective cover is formed to cover outer surfaces of the plurality of rare earth magnets.

Alternatively, the method of magnetizing a rare earth magnet according to the present invention is a method of magnetizing a plurality of rare earth magnets fixed along the outer peripheral surface of a rotor, wherein A first step of applying a first magnetic field in a predetermined direction to each of the plurality of rare-earth magnets such that the magnetization directions of adjacent rare-earth magnets are substantially opposite to each other; A second step of applying a second magnetic field in a predetermined direction in the same direction as the direction in which the first magnetic field was applied, for each of the plurality of rare earth magnets to which the magnetic field has been applied, In the first step, before applying the first magnetic field to at least a part of the plurality of rare earth magnets, a first step having a magnitude corresponding to the magnitude of the first magnetic field is performed. Applying a reverse magnetic field of the first magnetic field The magnitude of the first inverse magnetic field is controlled to be smaller than a predetermined magnitude by adjusting the magnitude, so that the first magnetic field is applied after the first inverse magnetic field is applied. The magnetization direction of the entire rare earth magnet is oriented in the predetermined direction.

[0027] In a preferred embodiment, the second step is performed before the second magnetic field is applied to at least a part of the plurality of rare earth magnets.
Applying a second inverse magnetic field having a magnitude corresponding to the magnitude of the magnetic field of the rare earth magnet to which the first magnetic field has been applied after the first inverse magnetic field has been applied. The magnetization direction does not reverse even when the second reverse magnetic field is applied.

In a preferred embodiment, the magnitude of the first inverse magnetic field is controlled to 1 Tesla or less by controlling the magnitude of the first magnetic field. In a more preferred embodiment, the magnitude of the reverse magnetic field is controlled to 0.5 Tesla or less.

[0029] In a preferred embodiment, the first magnetic field and the second magnetic field are formed by a plurality of magnetic field generating portions provided to face each of the plurality of rare earth magnets, and after the second step, A third step of shifting the positions of the rare earth magnet and the magnetic field generating unit and then magnetizing the magnet.

In a preferred embodiment, the magnetic field generator includes a coil, and the third step is performed in a state where the inner peripheral surface of the coil and the end of the rare earth magnet are substantially aligned in the rotor radial direction. .

In a preferred embodiment, the plurality of rare earth magnets are fixed on the outer peripheral surface of the rotor, and the thickness of the end of each rare earth magnet is smaller than the thickness of the center of the rare earth magnet. .

[0032] In a preferred embodiment, a protective cover for covering the outer peripheral surfaces of the plurality of rare earth magnets is formed.

[0033] The method of manufacturing a rotor assembly according to the present invention includes a step of preparing a plurality of rare earth magnets, a step of fixing the plurality of rare earth magnets to a rotor, and a step of fixing the plurality of rare earth magnets fixed to the rotor. And magnetizing using any of the above magnetizing methods.

A method of manufacturing a rotating machine according to the present invention includes a step of manufacturing a rotor assembly using the above-described method of manufacturing a rotor assembly, and a step of providing a current path around the rotor assembly.

A magnetizing device according to the present invention is a magnetizing device for magnetizing a plurality of rare earth magnets fixed to an outer peripheral surface of a rotor, wherein each of the plurality of rare earth magnets faces the outer peripheral surface of the rotor. And a control device capable of switching the intensity of the magnetic field formed by the plurality of magnetic field generators at least at two levels when performing the magnetization.

[0036] In a preferred embodiment, the apparatus further comprises a moving device capable of relatively moving the plurality of magnetic field generating units and the plurality of rare earth magnets when performing the magnetization.

In a preferred embodiment, the apparatus further comprises a position control device for controlling a relative position between the plurality of magnetic field generating units and the plurality of rare earth magnets, wherein the position control device includes at least one of the plurality of rare earth magnets. The moving device is controlled so that the ends of the two rare earth magnets are aligned with the ends of the magnetic field generating sections corresponding to the at least one rare earth magnet.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, when a plurality of rare earth magnets fixed to the outer peripheral surface of a large rotor are magnetized separately, an N pole and an S pole are arranged along the circumferential direction of the rotor. When the rare-earth magnets are magnetized so that are alternately arranged, a relatively large reverse magnetic field is applied to the magnets adjacent to the magnets to be magnetized. This makes it difficult to perform saturation magnetization, especially at the end of the magnet. Such a problem does not occur when all the magnets are magnetized at once.

On the other hand, the present inventors have studied in detail the influence of the above-mentioned reverse magnetic field. FIG. 6 shows a magnetizing step conventionally performed by the inventor. 6, among the first to 32nd rare earth magnets 22 forming 32 poles fixed to the outer peripheral surface of the rotor 20 shown in FIG.
It shows schematically what magnetic field is applied in each of the magnetizing steps to the fourth to 32nd rare earth magnets. In each of FIGS. 6A to 6C,
In order from the left to the right, the 32nd rare earth magnet, the first rare earth magnet, the second rare earth magnet, the third rare earth magnet, and the fourth rare earth magnet are set in the original magnetization direction ( (Either the N pole side or the S pole side). The center of the n-th rare earth magnet is indicated by nC (for example, 1C, 2C, etc.), the left end is indicated by nL, and the right end is indicated by nR. Although FIG. 6 shows a state in which the magnets are arranged in a horizontal row, these magnets are actually arranged in an arc along the outer peripheral surface of the rotor.

As shown in FIG. 6A, when the first rare earth magnet (the second rare earth magnet from the left in the figure) is magnetized to the N pole side, the magnetic field generating unit 12 (see FIG. 1) About 5 to the outside of the rotor along the radial direction of the rotor.
A forward magnetic field of T is formed. As a result, a forward magnetic field of about 5.02T is applied to the center 1C of the first rare earth magnet, and a forward magnetic field of about 2.29T is applied to both ends 1R and 1L. The unmagnetized rare-earth magnet having no magnetization reaches the saturation magnetization sufficiently when a magnetic field of about 2.29 T or more is applied, so that the entire first magnet (1
L, 1C, 1R) can be appropriately magnetized on the N pole side.

However, in the step of magnetizing the first rare earth magnet, the magnetic field applied to the first rare earth magnet causes the left end 2L and the third end of the second magnet to move away from the second magnet.
A reverse magnetic field of about 1.2T is applied to the right end 32R of the second magnet. As a result, the left end 2 of the second magnet
The L and the right end 32R of the 32nd magnet are magnetized so as to have a magnetization opposite to the original magnetization direction (S pole side). In this step, a relatively weak reverse magnetic field is also applied to the third magnet. As a result, the third magnet is also magnetized so as to have a magnetization opposite to the original magnetization direction (N-pole side).

Next, as shown in FIG. 6B, the second rare earth magnet is magnetized. Since the second magnet is a magnet to be magnetized on the south pole side, the direction of the applied magnetic field is opposite to the direction of the magnetic field shown in FIG. By this magnetizing step, a magnetic field of about 5.02T is applied to the center 2C of the second magnet, and about 2.29 weaker than the center 2C at both ends 2R and 2L.
A magnetic field of T is applied.

At this time, the end 2L of the second magnet is
Since the magnet was already magnetized to the N pole side by the reverse magnetic field of about 1.2 T received when the first magnet shown in FIG. 6A was magnetized, a magnetic field of about 2.29 T was applied. Also S
Not sufficiently magnetized on the pole side. Therefore, at least the end of the second magnet does not reach the saturation magnetization, and the magnetizability is deteriorated as a whole.

In the step of magnetizing the second magnet, a reverse magnetic field of about 1.2T is applied to the ends 1R and 3L of the first and third magnets located on both sides. Since the end portion 1R of the first magnet is already magnetized to the saturation magnetization, even if such a reverse magnetic field is applied, it is not so affected. However, since the end 3L of the third magnet is almost unmagnetized (or magnetized in a slightly opposite direction) (hereinafter, such a state is also referred to as “unmagnetized” in the present specification). "Non-magnetized" means that the surface magnetic flux density is 2
0%).
Magnetization is relatively large in an undesired direction (S-pole side). Therefore, even after the third magnet is magnetized next as shown in FIG. 6C, the magnet end 3L cannot be sufficiently magnetized in the original direction.

Thereafter, steps similar to those shown in FIGS. 6A to 6C are repeated to magnetize the first to 32nd rare earth magnets. In such a magnetizing method, at least a part (end) of the predetermined rare earth magnet is not subjected to the saturation magnetization, and the magnetizing rate is reduced as a whole.

Next, the influence of the reverse magnetic field in the step shown in FIG. 6 will be described more quantitatively with reference to FIGS. FIG. 7 is a graph showing the influence of a reverse magnetic field, obtained by an experiment performed by the present inventors. This graph shows a rare earth magnet (NEOMA manufactured by Sumitomo Special Metals Co., Ltd.) magnetized in advance in a direction opposite to a predetermined direction (ie, having a negative magnetization rate).
The relationship between the magnitude of the applied magnetic field and the magnetization rate when a magnetic field is applied in a predetermined direction (forward direction) with respect to (X-30SH).

As can be seen from the graph shown by the white circle, NE
Assuming that OMAX-30SH is used as the magnet, in the step shown in FIG.
When a reverse magnetic field of about 1.2T is applied to L, the end 2L is magnetized to about 60% in the direction of the reverse magnetic field. As can be seen from the graph shown by the white square, the portion which is largely magnetized in the opposite direction as described above, when the magnetization is performed in the forward direction in the step shown in FIG.
Unless a magnetic field having a magnitude exceeding 5T is applied, it cannot even be magnetized in the forward direction. Further, in order to obtain magnetization near the saturation magnetization (magnetization rate of 90% or more), it is necessary to apply a magnetic field exceeding about 4T.

As shown in FIG. 6B, in the magnetizing method, only a forward magnetic field of about 2.29 T is applied to the end 2L of the magnet. Therefore, it is understood that appropriate magnetization is not performed in this portion.

FIG. 8 shows a magnetization curve at the end 2L of the second magnet. As shown in FIG. 8 (a), when the first rare earth magnet is magnetized, a reverse magnetic field of about 1.2T is applied to the end 2L.
Are relatively large in the opposite direction. In this case, FIG.
As shown in (b), even when a forward magnetic field of about 2.29 T is applied in a subsequent step, the magnetization in the opposite direction remains at the end 2L.

The cause of such a phenomenon is that when the magnet has a relatively large magnetization rate in the negative direction, the magnetization rate is unlikely to increase unless a considerably strong magnetic field is applied (see FIG. 7). ). For example, when the magnetization rate is 0% (open circle graph) or about -10% (open triangle graph), the magnetization rate sharply increases by applying a magnetic field exceeding about 1T, and is relatively easily increased. While the magnetization rate can be obtained (in the graph, a region with a steep slope), the magnetization rate is about -60% (open square graph) and about -98%.
In the graph (black square), even when a magnetic field of about 2T is applied, the magnetization rate does not increase so much (in the graph, the slope is gentle). Therefore, a relatively strong reverse magnetic field is applied to the unmagnetized rare earth magnet, and once this rare earth magnet is strongly magnetized in the direction of the reverse magnetic field,
It can be seen that it is difficult to magnetize in the original direction even if a considerably large forward magnetic field is applied.

Further, as can be seen from the graph of FIG. 7, when a magnetic field of about 2.5 T is applied to a rare-earth magnet having a magnetizability of 0% (open circle graph), almost 100% of magnetism can be obtained. On the other hand, when a magnetic field of about 2.5 T is applied to a rare earth magnet having a magnetization rate of about -10% (open triangle graph), only a magnetization rate of about 80% is obtained, and sufficient magnetic properties are obtained. Can not. That is, when the forward magnetic field applied at the time of magnetization is relatively weak (for example, about 3 T or less), if the magnet is already magnetized in the opposite direction by a reverse magnetic field, saturation magnetization may occur. It turns out that it becomes difficult to magnetize.

From these facts, the inventor of the present invention pre-magnetizes the magnet in a desired direction (magnetization) so as not to be affected by the reverse magnetic field before magnetizing with a relatively large magnetic field (main magnetizing). (Temporary magnetization). If a certain degree of magnetization (for example, about 20%) is previously performed in a desired direction by temporary magnetization, then it is assumed that a reverse magnetic field of about 1.2 T is applied during the main magnetization. Are not magnetized in the opposite direction (see FIG. 7). Therefore, in this magnetization, the entire magnet can be appropriately magnetized, and high magnetic characteristics can be obtained.

Such temporary magnetization can be performed, for example, before fixing the magnet to the rotor. However, when a magnet that has been temporarily magnetized in advance is bonded to the rotor, as described above, it is difficult to perform bonding with high positional accuracy. In addition, since the magnets attract each other at the time of bonding, there is a problem that the operation involves danger. Further, a temporary magnetizing step needs to be separately performed on the rare-earth magnet before being fixed to the rotor, so that the number of rotor assembly manufacturing steps increases and the manufacturing cost increases.

Therefore, the present inventor has considered a method of performing the above-described temporary magnetization on an unmagnetized magnet fixed to the rotor without performing the magnetization. If the temporary magnetization can be performed while being fixed to the rotor, it is possible to appropriately magnetize the fixed magnet with high positional accuracy without complicating the manufacturing process of the rotor assembly.

However, in this case, there is a problem that the magnetic field applied at the time of the temporary magnetization forms a reverse magnetic field with respect to the adjacent magnet, and the rare earth magnet is magnetized in a direction opposite to the original direction. . The present inventor also studied the influence of the reverse magnetic field formed in the temporary magnetization. As a result, by adjusting the magnitude of the magnetic field applied to the magnet at the time of the temporary magnetization, it is possible to magnetize the entire rare earth magnet with a certain size in a predetermined direction after the temporary magnetization. all right.

Hereinafter, the effect of the reverse magnetic field generated during the temporary magnetization will be described with reference to FIG. 7 again. As can be seen from FIG. 7, the rare earth magnet has such a property that when a magnetic field exceeding a predetermined magnitude is applied, the magnetization rate sharply increases. Therefore, in order to suppress the magnetization in the opposite direction due to the reverse magnetic field, it is desirable that the reverse magnetic field does not exceed the above-mentioned predetermined magnitude as much as possible. For example, if the magnitude of the reverse magnetic field applied to the rare earth magnet when not magnetized (magnetization rate 0%) can be kept to about 0.5 T or less, the magnitude of magnetization in the opposite direction (magnetization rate) Can be suppressed to less than about 10%. Since this reverse magnetic field has a magnitude corresponding to the magnitude of the forward magnetic field applied to the magnet to be magnetized, controlling the magnitude of the applied magnetic field (forward magnetic field) to each magnet also reduces the magnitude of the reverse magnetic field. Controlled.

Thereafter, a forward magnetic field is applied to the magnet to which the reverse magnetic field has been applied in the temporary magnetizing step. At this time, as described above, the magnetization by the reverse magnetic
%, The magnetization rate is about 2 even if the strength of the forward magnetic field is about 1T, as shown in the black circle graph.
Magnetization can be performed in a desired direction at a size of about 0%. In this way, if the magnet can be magnetized in a desired direction at a certain magnetization rate in the temporary magnetizing step, when a reverse magnetic field is applied in the subsequent main magnetizing step, the reverse It can be prevented from being magnetized in the direction. For example, if magnetizing in a predetermined direction at a magnetizing rate of about 20% by temporary magnetizing, in the subsequent main magnetizing step,
Even if a reverse magnetic field of about 1.2 T is applied, the magnet is prevented from being magnetized in the opposite direction.

As described above, in order to magnetize the entire magnet in a predetermined direction (forward direction) at a certain magnetization rate in the state after the temporary magnetization, the magnetic field applied in the temporary magnetization is required. It is important to properly select the size of. At this time,
By generating a magnetic field of an appropriate magnitude, the strength of the reverse magnetic field applied to the magnet is set within a range in which the magnet is not easily magnetized (a range in which the gradient in the graph is gentle), and is applied to the magnet. It is desirable to set the strength of the forward magnetic field within a range in which the magnet is easily magnetized (a range with a steep slope in the graph). By performing the temporary magnetization in this way,
The whole magnet can be magnetized to some extent (preferably about 10% or more) in a desired direction. This allows
Since it is possible to prevent the magnets from being magnetized in the opposite direction by the reverse magnetic field applied when the adjacent magnets are fully magnetized, it is necessary to perform appropriate magnetization close to 100% on the entire magnets. Can be.

Based on these facts, according to the magnetizing method of the present invention, the plurality of rare earth magnets fixed to the rotor are firstly temporarily magnetized with a relatively weak magnetic field.
Next, main magnetization is performed in the same direction as the temporary magnetization with a magnetic field that is relatively stronger than the magnetic field at the time of the temporary magnetization.
It is desirable that the strength of the reverse magnetic field applied at the end of another rare earth magnet adjacent to the rare earth magnet to be magnetized be adjusted to be smaller than a predetermined value. Preferably, the magnitude of the magnetic field applied during the temporary magnetization is set so that the magnetization direction of the magnet is not reversed by the reverse magnetic field applied during the main magnetization. According to the experiment of the present inventor, in the rare earth magnet fixed to the rotor, it is desirable to adjust the strength of the reverse magnetic field applied at the end of the rare earth magnet to 1.0 Tesla or less, and to 0.5 Tesla or less. Adjustment has been found to be more desirable.

Hereinafter, embodiments of the present invention will be described.

(Embodiment 1) In this embodiment, the form of the rotor assembly and the magnetizing device can be substantially the same as those described with reference to FIGS. In the present embodiment, the rotor 20 is configured as shown in FIG.
2), diameter of 200 to 300 mm and axial length of 5
It is a large one having a size of 00 to 600 mm, and a large number of rare earth magnets 22 are fixed to the outer peripheral surface of the rotor 20 by an adhesive or the like. The rare-earth magnets 22 are arranged along the circumferential direction of the rotor so as to form 32 poles (magnetic poles) at predetermined intervals. Rare earth magnets
For example, it has a size of 22 mm in width × 6 mm in thickness × 50 mm in length, and one magnetic pole is formed by arranging ten pieces along the axial direction of the rotor.

As shown in FIG. 1, a plurality of rare earth magnets 22
Is fixed to the rotor 10 in the hole 10a of the magnetized yoke 10.
In this state, the magnetizing device 1 is used to magnetize each magnet 22. When performing magnetization,
It is desirable that the magnetic field generating part 12 of the magnetized yoke 10 and the rare earth magnet 22 are arranged so as to face each other, and their center lines coincide with each other. When the rare earth magnet 22 and the magnetic field generating unit 12 are arranged in this way and magnetized, the magnetic field generating unit 1
2 can be effectively applied to the entire rare earth magnet 22. Therefore, the magnetization rate of the rare earth magnet 22 can be improved.

In this embodiment, a two-stage magnetizing process of temporary magnetizing and main magnetizing is executed. For this reason, the magnetizing device 1 is provided with means for controlling the magnitude of the magnetic field generated by the magnetic field generator 12. The control of the magnitude of the magnetic field is preferably performed by controlling the magnitude of the current flowing through the coil of the magnetic field generator 12. For this purpose, the magnetizing device of the present embodiment includes a voltage controller (not shown) that can automatically control the supply voltage in the circuit shown in FIG.

Hereinafter, the magnetizing method of this embodiment will be described with reference to FIGS.

FIGS. 9 and 10 show the first to 32nd magnets forming the 32 poles shown in FIG.
The magnetic fields applied to the fourth and 32nd magnets in the magnetizing process (temporary magnetizing process and main magnetizing process) are schematically shown. Also in these figures, as in FIG. 6, in order from the left side to the right side, the 32nd rare earth magnet, the first rare earth magnet, the second rare earth magnet, the third rare earth magnet, the fourth The second rare earth magnet is shown with the original magnetization direction. 9 and 10 show a state in which the magnets are arranged in a horizontal line, but these magnets are actually arranged in an arc along the outer peripheral surface of the rotor.

First, referring to FIGS. 9A to 9C,
The temporary magnetizing step will be described.

As shown in FIG. 9A, when the first magnet is provisionally magnetized to the N pole side, the magnetic field in the radial direction of the rotor is used by using the magnetic field generator 12 (see FIG. 1). Is generated, a forward magnetic field of about 3.32T is applied to the center 1C of the first magnet, and a forward magnetic field of about 1.12T is applied to both ends 1R and 1L.

In the temporary magnetizing step for the first magnet, the second magnetic field is applied by the magnetic field applied to the first magnet.
A reverse magnetic field of about 0.45T is applied to the left end 2L of the 32nd magnet and the right end 32R of the 32nd magnet. As a result, the left end 2L of the second magnet and the right end 32R of the 32nd magnet are magnetized so as to have weak but opposite magnetization to the original magnetization direction (S-pole side). You.

Next, as shown in FIG. 9B, the second magnet is magnetized. Since the second magnet needs to be magnetized on the S pole side, the direction of the applied magnetic field is opposite to the direction of the magnetic field shown in FIG. By this magnetizing step, the central portion 2C of the second magnet has:
A magnetic field of about 3.32T is applied, and a magnetic field of about 1.12T is applied to both ends 2R and 2L.

At this time, one end 2 of the second magnet
L is already slightly magnetized to the N-pole side by the reverse magnetic field received at the time of magnetizing the first magnet shown in FIG. 9A, but its magnetization rate is small. .12
When a forward magnetic field of T is applied, it is magnetized to the S pole side.

In the step of magnetizing the second magnet, a reverse magnetic field of about 0.45T is applied to the ends 1R and 3L of the first and third magnets located on both sides. Since the end portion 1R of the first magnet is already magnetized relatively large in the forward direction, even if such a reverse magnetic field is applied, it is not so affected. On the other hand, the end 3L of the third magnet is affected by the reverse magnetic field,
Slightly magnetizes in an undesired direction (S-pole side).

Next, as shown in FIG. 9C, the third magnet is magnetized. In this step, a magnetic field of about 1.12 T is applied to the end 3L of the third magnet that has been slightly magnetized on the S pole side, and is magnetized to a certain extent on the N pole side. .

Here, FIG. 7 is referred to again. When the magnet ends 2L and 3L are magnetized in the opposite direction with a magnitude of about 6 to 7% by applying a reverse magnetic field of about 0.45T (open circle graph), 1.12T
It can be seen that the application of the forward magnetic field results in magnetization in a desired direction with a magnitude exceeding about 20%. In addition,
In other parts (for example, 1R, 2C, 2R, etc.)
Since the influence of the reverse magnetic field is smaller, the magnetization is larger in the desired direction.

Referring back to FIG. 9 (a) to 9 (c)
Through the steps similar to those shown in (1), all the magnets for 32 poles are provisionally magnetized. This allows all magnets to
It is magnetized in a desired direction. In the temporary magnetizing step of the present embodiment, the magnet can be magnetized in a desired direction even at the end of the magnet which is particularly susceptible to the reverse magnetic field, and the entire magnetization direction of the rare-earth magnet is oriented in the desired direction. ing.

Next, the main magnetizing step will be described with reference to FIG. After the temporary magnetizing step is completed, FIG.
As shown in (a), the first magnetizing step is performed on the first magnet. When the first magnet is magnetized on the N pole side, the magnetic field generator 12 (see FIG. 1) generates a magnetic field in the radial direction of the rotor, so that the magnetic field is generated at the center 1C of the first magnet. Is applied with a forward magnetic field of about 5.02T, and at both ends 1R and 1L, about 2.2
A 9T forward magnetic field is applied. Thereby, the entire first magnet is magnetized to approximately 100%.

In the step of temporarily magnetizing the first magnet, the second magnetic field is applied by the magnetic field applied to the first magnet.
A reverse magnetic field of about 1.2T is applied to the left end 2L of the second magnet and the right end 32R of the 32nd magnet.

However, the ends 2L and 32R of the magnet are
By the temporary magnetization step shown in FIG. 9, the desired direction (S
(N pole side) because it is magnetized to some extent in the opposite direction (N pole side) even if a reverse magnetic field of about 1.2T is applied.
Is not magnetized. Therefore, as shown in FIG. 10B, the second magnet is magnetized to the S pole side, and a forward magnetic field of about 2.29T is applied to the end 2L of the magnet. , Saturation magnetization close to 100% can be performed.

FIG. 11 shows a magnetization curve at the end 2L of the magnet when the magnetization is performed by the magnetization method of the present embodiment. As shown in FIG. 11A, first, in the temporary magnetization step, when the first magnet is temporarily magnetized,
A reverse magnetic field of about 0.45T is applied to the end 2L of the magnet. However, since the magnitude of the magnetization due to the reverse magnetic field is small, as shown in FIG. 11B, when a forward magnetic field of about 1.12 T is applied in the subsequent temporary magnetizing step for the second magnet, The end 2L is magnetized in a desired direction.

Next, as shown in FIG. 11 (c), when the main magnetizing is performed on the first magnet in the main magnetizing step, a reverse magnetic field of about 1.2T is applied to the end 2L of the magnet. Applied. However, since the end portion 2L of the magnet has a certain amount of magnetization in a desired direction, the magnetization direction does not change even by a reverse magnetic field of about 1.2T, and the magnitude of the magnetization slightly decreases. Only. Thereafter, as shown in FIG. 10D, in the main magnetizing step for the second magnet, about 2.
When a forward magnetic field of 29T is applied, the end 2L almost reaches saturation magnetization.

Table 1 below shows the degree of magnetization of the rare earth magnet according to the magnetizing method of this embodiment in comparison with the case where full magnetizing was performed. The table shows that the current flowing through the coil during the temporary magnetization was 10 kA, and the current flowing through the coil during the main magnetization was 2 kA.
When the current is 0 kA, the current flowing through the coil during the temporary magnetization is 8 kA, and the current flowing through the coil during the main magnetization is 20 kA.
and kA. In the table, the results of measuring the magnetic flux density on the surface of the magnet after magnetization for eight test pieces (TP1 to 8) arranged along the peripheral surface of the rotor are shown. Note that full magnetization is performed by applying a sufficiently strong magnetic field to the magnet alone in the air-core coil, and it is considered that the magnet at this time has almost reached saturation magnetization.

[0081]

[Table 1]

As can be seen from Table 1 above, according to the magnetizing method of the present embodiment, the case where the full magnetizing is performed is 96 times.
% Could be achieved. Although not shown in the table, when the magnitude of the magnetic field at the time of the temporary magnetization is set to 40% to 70% of the magnitude of the magnetic field at the time of the main magnetization, the magnet is appropriately magnetized at a high magnetization rate. It turned out that it could be magnetized.

(Embodiment 2) In Embodiment 2, after the provisional magnetization step and the main magnetization step described in Embodiment 1 are performed, as shown in FIGS. 13 and 14, the center C1 of the rare earth magnet 22 is A further magnetizing step (staggered magnetizing) is performed with the center C2 of the magnetic field generating unit 12 shifted.
Thereby, the magnetization rate at the end of the rare earth magnet can be further improved.

First, referring to FIG.
The magnetizing step performed in a state where the rare-earth magnet 22 is shifted to the left with respect to the magnetic field generating unit 12 provided in the above will be described.

As shown, in this embodiment, the outer surface of the rare earth magnet 22 fixed to the outer peripheral surface of the rotor 20 is covered with a protective cover (or protective tape) 26. The protective cover 26 is used to cover the rare earth magnet 2 when the rotor assembly is rotating in a rotating machine such as a motor.
2 is damaged by accidental contact or the like, and this
It is provided to prevent falling off. If the protective cover 26 is not provided, the rotating machine may suddenly stop due to the damaged magnet, and thus there is a high risk.

However, if such a protective cover 26 is provided, there arises a problem that it is difficult to increase the magnetization rate of the rare earth magnet. The protective cover 26 is formed of a tape material containing a glass material or a non-magnetic material such as a thermosetting tape. If a magnet is used, the protective cover 26 and the magnet end 22
A gap 28 is formed between L and 22R. In this case, it has been difficult to apply a magnetic field having sufficient strength in a desired magnetization direction to the magnet ends 22L and 22R. If the protective cover 26 is not provided, the shape of the pole piece 11 of the yoke 10 is designed so as to conform to the surface shape of the magnet, and a desired direction (rotor radial direction) with respect to the magnet end from a closer position. It is possible to apply a strong magnetic field, but this is not possible if the protective cover 26 is provided.

To apply a desired magnetic field at the magnet ends 22L and 22R, the width of the magnetic field generator 12 may be designed to be larger than the width of the magnet 22, but in this case, the width is applied to the adjacent magnet. The strength of the reverse magnetic field is increased, and the magnetizability is rather reduced. Further, in a magnetizing device for a large rotor, a coil 16 formed by winding a hollow thick conductive wire through which cooling water flows (in the figure, a cross section of the wound conductive wire is shown). In this case, it is necessary to increase the size of the recess 14 as a space for the coil, so that the width of the pole piece 11 of the yoke 10 must be narrower than the width of the magnet. Was. For this reason, it was difficult to saturate the magnet ends 22L and 22R in a desired magnetization direction.

On the other hand, as shown in the figure, if the magnetization is performed with the center C1 of the rare-earth magnet shifted to the left with respect to the center C2 of the magnetic field generator 12 (or the coil 16), the right end of the magnet can be obtained. A strong forward magnetic field containing a large amount of components in the rotor radial direction (direction perpendicular to the surface of the magnet) can be applied to 22R. Thereby, the magnetization rate at the end 22R can be further improved. In this magnetizing step, the center C1 of the magnetic field generator 12 (or the coil 16) and the center C2 of the rare earth magnet are shifted by, for example, about 3 mm.
Preferably, the magnetization is performed in a state where the magnet end portion 22R and the inner surface of the coil 16 (that is, the outer surface of the ball piece 11) are substantially aligned in the rotor radial direction.
That is, the inner surface of the coil 16 is located on an extension of the line connecting the center of the rotor and the magnet end 22R. Thereby, the magnet end 22R to be magnetized can be appropriately magnetized, and the influence of the reverse magnetic field applied to the end 23L of the adjacent magnet 23 can be suppressed relatively low.

According to the experiment conducted by the present inventor, as shown in FIG. 13, in the state where the magnetic field generating portion 12 and the rare earth magnet 22 are shifted, the same as the main magnetization performed in the first embodiment described above with the magnets facing each other. When a magnetic field having a strength of is generated, a forward magnetic field of about 4.43T is applied to the magnet end 22R,
A forward magnetic field of 2.23T was applied to the opposite magnet end 22L. Also, on the left end 23L of the magnet 23 on the right,
A reverse magnetic field of about 1,27T is applied, and the magnet 2 on the left is
4, a sequential field of about 0.70T was applied to the right end 24R.

Note that the left end 23L of the magnet 23 on the right side is
Is applied with a reverse magnetic field of 1.27 T. In the present embodiment, however, the shift magnetization is performed after the main magnetization performed by directly facing the magnet and the magnetic field generating unit. The effect is small. The end portion 23L of the magnet 23 on the right side is largely magnetized in the forward direction before the reverse magnetic field is applied in the shift magnetizing step. Little change in direction (see Fig. 7)
Because. For this reason, it becomes possible to magnetize each magnet at a high magnetization rate in a predetermined direction.

With the rare-earth magnet 22 shifted to the left with respect to the magnetic field generator 12 in this way, the magnetization is shifted to each of the 32 magnets fixed to the outer peripheral surface of the rotor. As shown in (1), the magnetization is performed with the rare-earth magnet 22 shifted to the right to improve the magnetization rate of the left end portion 22L of the magnet. By doing so, the magnet both ends 22
The magnetization ratio of R and 22L can be improved, and the magnetization ratio of the entire magnet can be further improved.

In the magnetizing apparatus of the present embodiment, it is necessary to relatively move the magnetic field generator 12 and the rare earth magnet 22 in order to perform the above-described staggered magnetizing. Such a magnetizing device includes, for example, a turntable that supports a rotor,
This can be realized by providing a control device that can be controlled to rotate by a desired angle in a desired direction.

Tables 2 to 6 below show the degree of magnetization of the rare earth magnet when different magnetizing steps were performed, as compared with the case where full magnetization was performed. Table 2 shows that, after provisional magnetization, the magnetization (main magnetization) performed by facing directly without performing the shift magnetization is 3
Table 3 shows that, after performing the temporary magnetizing and the magnetizing performed while facing each other, and performing the magnetizing once by shifting 2.5 mm to the left and right, Table 4 shows the temporary magnetizing. Table 5 shows that, after performing magnetizing and magnetizing by directly facing each other, and then performing magnetizing once by shifting 3.0 mm to the left and right, respectively, temporary magnetizing and magnetizing performed by facing directly are performed. Table 6 shows that when magnetizing was performed once each time after shifting by 3.5 mm to the left and right, the magnetizing was performed by shifting 3.5 mm to the left and right without performing the magnetizing performed by facing directly after the temporary magnetization. The case where magnetization is performed once each is shown. In the temporary magnetization step, the current flowing through the coil was set to 10 kA.
It was set to 0 kA.

In Tables 2 to 6, for eight magnets 1 to 8 arranged along the peripheral surface of the rotor, the results of measuring the number of magnetic fluxes of the magnets magnetized in a state fixed to the rotor (2 from the left) are shown. Column) and the result of measuring the number of magnetic fluxes of the magnets that are considered to have reached saturation magnetization by full magnetization (third column from the left)
And their ratios (the first column from the right).
The full magnetization was performed by applying a sufficiently strong magnetic field to the magnet alone in the air-core coil. Further, the number of magnetic fluxes is measured using a known flux meter (manufactured by Nippon Electromagnetic Instruments Co., Ltd.), and the table shows the measured number of magnetic fluxes (unit:
Kilomaxwell (kMx)) is multiplied by the number of turns (T) of the search coil of the flux meter, which is a constant.

[0095]

[Table 2]

[0096]

[Table 3]

[0097]

[Table 4]

[0098]

[Table 5]

[0099]

[Table 6]

As can be seen from a comparison between Table 2 and Tables 3 to 5, after magnetizing the rare-earth magnet and the magnetic field generating portion while facing each other, these magnets are shifted left and right to perform magnetizing. The magnetization ratio can be further improved as compared with the case where the offset magnetization is not performed. In particular, in the form shown in Table 4, 3 mm
By shifting the magnet, the magnetization is performed in a state where the end of the magnet is aligned with the inner peripheral surface of the coil. In this case, the highest magnetization rate was obtained.

As can be seen from a comparison of Tables 3 to 5 with Table 6, if the shift magnetization is performed after the main magnetization is performed with the rare-earth magnet and the magnetic field generating portion facing each other, the shift is fixed. The magnetization rate can be further improved as compared with the case where only magnetism is performed.

As described above, according to the magnetizing methods of the first and second embodiments, the rare-earth magnet fixed to the rotor is magnetized in two stages, so that the rare-earth magnet has a near saturation magnetization. It can be magnetized up to. In particular, as shown in the second embodiment, a very high magnetization rate can be obtained by further performing a shift magnetization in which the positions of the rare earth magnet and the magnetic field generating portion are shifted after the two-stage magnetization. Since the rotor assembly (see FIG. 12) manufactured in this manner can generate a strong magnetic field, when used in a rotating machine, it efficiently converts electrical energy and rotational motion (mechanical energy). can do. In order to manufacture a rotating machine, a stator is provided around the rotor assembly. A current path such as a coil is provided in the stator, and a current flows through the current path to generate a magnetic field around the rotor assembly, thereby rotating the rotor assembly (motor). Also, by rotating the rotor assembly mechanically, the direction of the magnetic field formed by the rare earth magnetic field fixed to the rotor can be changed, and power can be generated in the current path by the change in the direction of the magnetic field (generator). .

[0103]

According to the magnetizing method of the present invention, after the non-magnetized rare earth magnet is fixed to the outer peripheral surface of the rotor, the magnet is appropriately magnetized so that the whole of the rare earth magnet almost reaches the saturation magnetization. Can be magnetized. With this configuration, the rare-earth magnet can be easily fixed to the rotor with high positional accuracy, and a rotor assembly having high magnetic characteristics can be manufactured. By using the rotor assembly manufactured in this way, a high-performance rotating machine can be manufactured.

[Brief description of the drawings]

FIG. 1 is a top view of a magnetizing device with a rotor assembly inserted therein.

FIG. 2 is an enlarged cross-sectional view showing a magnetic field generating portion of the magnetizing device.

FIG. 3 shows a drive circuit of the magnetizing device.

FIG. 4 is a top view schematically showing a magnetic field formed by a magnetic field generating unit.

FIG. 5 is an enlarged top view showing a magnetic field to be applied to a magnet to be magnetized and magnets on both sides thereof.

6A and 6B are schematic diagrams for explaining a magnetizing method conventionally performed by the inventor, wherein FIG. 6A shows a magnetizing step for a first magnet, and FIG. 6B shows a second magnet. And (c) shows a magnetizing step for the third magnet.

FIG. 7 shows the magnitude of an applied magnetic field when a magnetic field is applied in a predetermined direction (forward direction) to a rare-earth magnet magnetized in a direction opposite to a predetermined direction (ie, having a negative magnetization rate) in advance. 6 is a graph showing the relationship between the magnetic field and the magnetization ratio.

FIG. 8 shows a magnetization curve at the end of the second magnet when the magnetization method shown in FIG. 6 is used.

FIG. 9 is a schematic diagram for explaining a temporary magnetizing step in the magnetizing method according to the first embodiment of the present invention, wherein FIG.
7B illustrates a magnetizing process for the second magnet, FIG. 7B illustrates a magnetizing process for the second magnet, and FIG. 7C illustrates a magnetizing process for the third magnet.

FIGS. 10A and 10B are schematic diagrams for explaining a main magnetizing step in the magnetizing method according to the first embodiment of the present invention, wherein FIG. 10A shows a magnetizing step for a first magnet, and FIG. 3 shows a magnetizing step for the second magnet.

FIG. 11 shows a magnetization curve at the end of the second magnet when the magnetization method shown in FIGS. 9 and 10 is used.

FIG. 12 is a perspective view showing a rotor assembly capable of magnetizing a magnet using the magnetizing method of the present invention.

FIG. 13 is a cross-sectional view illustrating a left-shift magnetizing step according to the second embodiment of the present invention.

FIG. 14 is a cross-sectional view illustrating a right-shift magnetizing step according to the second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetization apparatus 10 Magnetization yoke 12 Magnetic field generation part 20 Rotor 22 Rare earth magnet

Claims (23)

[Claims] 1. A method of magnetizing a plurality of rare earth magnets fixed to a rotor, the first magnet being sequentially applied to the plurality of rare earth magnets by a relatively weak first magnetic field. A first step of performing magnetism, and a second step in which the plurality of rare-earth magnets sequentially have substantially the same orientation as the first magnetic field and are stronger than the first magnetic field.
A second step of performing a second magnetization with a magnetic field of the type described above. 2. When the first magnetization is performed on a selected rare earth magnet among the plurality of rare earth magnets, at least an end portion of another rare earth magnet adjacent to the selected rare earth magnet. Applying a first reverse magnetic field having a direction substantially opposite to the original magnetization direction; and performing a first magnetization on another rare earth magnet adjacent to the selected rare earth magnet. Performing the first step of magnetizing the portion to which the first reverse magnetic field has been applied in the original magnetization direction to thereby provide the first magnetization in the same direction as the original magnetization direction. The method for magnetizing a rare earth magnet according to claim 1. 3. The method for magnetizing a rare earth magnet according to claim 2, wherein the strength of the reverse magnetic field at an end of another rare earth magnet adjacent to the selected rare earth magnet is adjusted to 1.0 tesla or less. . 4. The method according to claim 3, wherein the strength of the reverse magnetic field is adjusted to 0.5 Tesla or less. 5. When performing the second magnetization on a selected one of the plurality of rare earth magnets, at least one of the other rare earth magnets adjacent to the selected one of the rare earth magnets. Applying a second reverse magnetic field having a strength not to reverse the first magnetization and having a direction substantially opposite to the original magnetization direction to the end; Performing a second magnetization on another rare-earth magnet adjacent to the rare-earth magnet to be magnetized in a direction in which the second reverse magnetic field is applied. Item 5. The method for magnetizing a rare earth magnet according to any one of Items 2 to 4. 6. A magnetizing direction when the first magnetizing and the second magnetizing are performed on the selected rare earth magnet, and a magnetizing direction adjacent to the selected rare earth magnet. The rare-earth magnet according to any one of claims 2 to 5, wherein the magnetization directions when the first magnetization and the second magnetization are performed on the rare-earth magnet are substantially opposite to each other. Magnetization method. 7. The first magnetization and the second magnetization are performed by a magnetic field formed by a plurality of magnetic field generators provided to face each of the plurality of rare earth magnets, and The method according to any one of claims 1 to 6, further comprising, after the step, a third step of shifting the positions of the rare earth magnet and the magnetic field generating portion and then performing magnetization. 8. The magnetic field generating unit includes a coil, and the third step is performed in a state where an inner surface of the coil and an end of the rare earth magnet are substantially aligned in a rotor radial direction. 3. The method for magnetizing a rare earth magnet according to item 1. 9. The rare earth magnet is fixed on an outer peripheral surface of the rotor, and a thickness of an end portion of each rare earth magnet is smaller than a thickness of a central portion of the rare earth magnet. 3. The method for magnetizing a rare earth magnet according to item 1. 10. The method for magnetizing a rare earth magnet according to claim 7, wherein a protective cover is formed to cover outer surfaces of the plurality of rare earth magnets. 11. A method of magnetizing a plurality of rare earth magnets fixed along the outer peripheral surface of a rotor, wherein the magnetizing directions of adjacent rare earth magnets among the plurality of rare earth magnets are relative to each other. A first step of applying a first magnetic field in a predetermined direction to each of the plurality of rare-earth magnets so that the plurality of rare-earth magnets are substantially opposite to each other. A second step of applying a second magnetic field having a direction substantially the same as the direction in which the first magnetic field is applied in a predetermined direction to each of the plurality of rare earth magnets. Applying a first inverse magnetic field having a magnitude corresponding to the magnitude of the first magnetic field before applying the first magnetic field to at least a part of the first magnetic field. Adjusting the magnitude of the first magnetic field, The magnitude of the reverse magnetic field is controlled to be smaller than a predetermined magnitude, thereby changing the magnetization direction of the entire rare earth magnet to which the first magnetic field is applied after the first reverse magnetic field is applied. A method for magnetizing a rare earth magnet oriented in the predetermined direction. 12. The second step according to a magnitude of the second magnetic field before applying the second magnetic field to at least a part of the plurality of rare earth magnets. Applying a second inverse magnetic field having a magnitude, wherein the entire magnetization direction of the rare earth magnet to which the first magnetic field has been applied after the first inverse magnetic field has been applied is the second magnetization direction. The method for magnetizing a rare earth magnet according to claim 11, wherein the magnet is not inverted even when a reverse magnetic field is applied. 13. The magnetization according to claim 11, wherein the magnitude of the first inverse magnetic field is controlled to 1 Tesla or less by controlling the magnitude of the first magnetic field. Method. 14. The magnetization according to claim 13, wherein the magnitude of the first inverse magnetic field is controlled to 0.5 Tesla or less by controlling the magnitude of the first magnetic field. Method. 15. The method according to claim 15, wherein the first magnetic field and the second magnetic field are formed by a plurality of magnetic field generators provided to face each of the plurality of rare earth magnets. The method for magnetizing a rare-earth magnet according to any one of claims 11 to 14, further comprising a third step of performing magnetizing after shifting the position of the magnet and the magnetic field generating unit. 16. The magnetic field generating section includes a coil, and the third step is performed in a state where an inner peripheral surface of the coil and an end of the rare earth magnet are substantially aligned in a rotor radial direction. 3. The method for magnetizing a rare earth magnet according to item 1. 17. The rare earth magnet is fixed on an outer peripheral surface of the rotor, and a thickness of an end portion of each rare earth magnet is smaller than a thickness of a central portion of the rare earth magnet. 3. The method for magnetizing a rare earth magnet according to item 1. 18. The rare earth magnet magnetizing method according to claim 15, wherein a protective cover is formed to cover outer peripheral surfaces of the plurality of rare earth magnets. 19. The method according to claim 1, wherein a step of preparing a plurality of rare earth magnets; a step of fixing the plurality of rare earth magnets to a rotor; and the step of fixing the plurality of rare earth magnets fixed to the rotor. A magnetizing method using the magnetizing method according to any one of (1) to (5). 20. A step of manufacturing a rotor assembly using the manufacturing method according to claim 19; and a step of providing a current path around the rotor assembly.
A method for manufacturing a rotating machine including: 21. A magnetizing device for magnetizing a plurality of rare earth magnets fixed to an outer peripheral surface of a rotor, wherein the magnetizing device faces the outer peripheral surface of the rotor and is provided to face each of the plurality of rare earth magnets. A magnetizing device, comprising: a plurality of magnetic field generating units; and a control device capable of switching the intensity of a magnetic field formed by the plurality of magnetic field generating units at at least two levels when performing the magnetizing. 22. The magnetizing apparatus according to claim 21, further comprising a moving device that can relatively move the plurality of magnetic field generating units and the plurality of rare earth magnets when performing the magnetizing. 23. A position control device for controlling a relative position between the plurality of magnetic field generators and the plurality of rare earth magnets, wherein the position control device includes at least one rare earth magnet among the plurality of rare earth magnets. 23. The magnetizing device according to claim 22, wherein the moving device is controlled such that an end of the moving device and an end of a magnetic field generating portion provided corresponding to the at least one rare earth magnet are aligned.