JP2003092213A - Magnetic field forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a magnetic field having large inclination of strength by using a magnet. SOLUTION: The magnetic field forming device has a yoke material 10, a pair of first magnets 12a, 12b which are fixed to the yoke material 10 and form a magnetic circuit, and generate a first magnetic flux proceeding from the N pole of one magnet of the pair of first magnets toward the S pole of the other magnet of the pair of first magnets and a pair of second magnets 14a, 14b which are fixed to the yoke material 10 disposed parallel to the pair of first magnets near the pair of first magnets and form a magnetic circuit, and generate a second magnetic flux proceeding from the N pole of one magnet of the pair of second magnets toward the S pole of the other magnet of the pair of second magnets. In a prescribed surface, the direction A1 of the first magnetic flux and the direction A2 of the second magnetic flux are in reverse directions.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an apparatus for forming a magnetic field using a permanent magnet.

[0002]

2. Description of the Related Art In recent years, permanent magnets having high magnetic properties have been developed and used in various devices such as motors. Such permanent magnets include, for example, rare earth magnets. Among them, neodymium / iron / boron magnets show high magnetic energy products and their prices are relatively low, so many applications are expected. There is.

When a permanent magnet is used in a device, it is important to form a desired magnetic field by appropriately selecting the size and arrangement of the magnet. For example, it may be desirable to create a magnetic field in which the magnitude of the magnetic flux density in a given direction changes abruptly.

[0004]

For example, a magnetic refrigeration system cools a ferromagnetic material or a paramagnetic material by repeatedly applying and not applying a magnetic field, but in a region where a strong magnetic field is generated. It is desirable that the magnetic field and the region where almost no magnetic field is generated are provided close to each other. In this case, it is desirable to form a magnetic field whose strength changes rapidly as described above. However, when attempting to form such a magnetic field using a permanent magnet, a strong magnet is used to form a strong magnetic field. Then, the magnetic field strength of the region in the vicinity also becomes high. Therefore, it is difficult to provide a region where a strong magnetic field is formed and a region where a magnetic field is hardly formed close to each other.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a magnetic field forming apparatus capable of forming a magnetic field in which a magnetic flux density rapidly changes at a predetermined location. .

[0006]

A magnetic field forming apparatus according to the present invention comprises a yoke material, and a first pair of magnets each having an N pole and an S pole and fixed to the yoke material to form a magnetic circuit. And a first pair that generates a first magnetic flux from the N pole of one magnet of the first pair of magnets to the S pole of the other magnet of the first pair of magnets. Fixed to the yoke member so as to be arranged in parallel with the first pair of magnets in the vicinity of the first pair of magnets. A second pair of magnets forming a magnetic circuit, from the north pole of one magnet of the second pair of magnets to the south pole of the other magnet of the second pair of magnets A second pair of magnets that generate a second magnetic flux that is directed, and the direction of the first magnetic flux on a predetermined surface. , Said second magnetic flux orientations are opposite.

The predetermined surface is typically a surface facing the north and south poles of the first pair of magnets and the north and south poles of the second pair of magnets.

In a preferred embodiment, the respective magnetization directions of the first pair of magnets are substantially perpendicular to the surfaces on which the first pair of magnets are fixed to the yoke member. The magnetization direction of each of the second pair of magnets is substantially perpendicular to each of the surfaces on which each of the second pair of magnets is fixed to the yoke member.

In a preferred embodiment, a third pair of magnets is provided so as to be opposed to the first pair of magnets.
Further includes a pair of magnets, and the first pair of magnets,
Magnetic fields that repel each other are formed by the third pair of magnets.

In a preferred embodiment, a fourth gap provided so as to face the second pair of magnets.
The pair of magnets is further provided, and the second pair of magnets and the fourth pair of magnets form magnetic fields that repel each other.

In a preferred embodiment, the volume of each of the first pair of magnets is at least twice the volume of each of the second pair of magnets.

In a preferred embodiment, the first pair of magnets is provided between one magnet of the first pair of magnets and the other magnet of the first pair of magnets. Further has a fifth magnet having a magnetization direction in a direction parallel to the first magnetic flux formed by.

In a preferred embodiment, the fifth magnet is an N-pole portion of one magnet of the first pair of magnets and an S-pole portion of the other magnet of the first pair of magnets. And the N pole of the fifth magnet faces the N pole portion of the one magnet, and the S pole of the fifth magnet faces the S pole portion of the other magnet. .

In a preferred embodiment, the fifth magnet has a coercive force higher than that of the first pair of magnets.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a perspective view showing the structure of a magnetic field forming apparatus 100 of the first embodiment. The magnetic field forming device 100 includes a yoke material 10 having a U-shaped cross section formed of a magnetic material having a high magnetic permeability such as carbon steel, and a pair of main magnets 1 fixed on a lower inner side surface 10L of the yoke material 10.
2a and 12b, and a pair of sub magnets 14a and 14b that are also fixed on the lower inner surface 10L. Generally, it is preferable that the volumes of the main magnets 12a and 12b are larger than the volumes of the sub magnets 14a and 14b.

Although FIG. 1 shows a form in which a gap is provided between the main magnets 12a and 12b and the sub magnets 14a and 14b, they may be arranged so as to be in contact with each other. Further, the main magnet 12a and the main magnet 12b, and the sub magnet 14a and the sub magnet 14b may not be in close contact with each other.

Further, a pair of opposed main magnets 16a and 16b provided so as to face the pair of main magnets 12a and 12b with a gap therebetween are fixed to the upper inner surface 10U of the yoke member 10. Further, a pair of opposed sub magnets 18a and 18b provided so as to face the pair of sub magnets 14a and 14b with a gap therebetween are also fixed to the upper inner surface 10U. Main magnets 12a and 12b and opposing main magnets 16a and 1
A space 20 is provided between the sub magnets 6b and 6b and between the sub magnets 14a and 14b and the facing sub magnets 18a and 18b.

The main magnets 12a and 12b and the main magnets 16a and 16b correspond to a first pair of magnets or a third pair of magnets, respectively. Further, the sub magnets 14a and 14b and the sub magnets 18a and 18b are respectively the second pair of magnets or the fourth pair of magnets.
Equivalent to a pair of magnets.

As these magnets, rare earth sintered magnets whose surfaces are covered with aluminum, nickel or the like can be used, and they are fixed to the yoke material 10 with an adhesive. The main magnets 12a and 12b and the facing main magnets 16a and 16b are, for example, NEOMAX-44H (H _cJ : 1273, manufactured by Sumitomo Special Metals Co., Ltd.).
kA / m) can be used, and NEOMAX-50 can be used as the sub magnets 14a and 14b and the facing sub magnets 18a and 18b.

Further, the yoke material 10 has an upper inner surface 10U.
It is sufficient that the portion including the lower inner surface 10L and the lower inner surface 10L is formed of a magnetic material, and the entire structure does not necessarily need to be integrally formed of a magnetic material.

The pair of main magnets 12a and 12b are
A direction perpendicular to the lower inner surface 10L of the yoke 10 (z
In the axial direction), they are magnetized in opposite directions to each other and form a magnetic circuit. As a result, a magnetic flux is formed from the north pole of one main magnet 12a toward the south pole of the other main magnet 12b. The projection (direction of magnetic flux) of this magnetic flux on the xy plane is the direction indicated by arrow A1.

Further, each of the pair of opposed main magnets 16a and 16b is magnetized in the opposite direction to each other in the direction perpendicular to the upper inner surface 10U (z-axis direction), and forms a magnetic circuit. ing. Further, each of the opposed main magnets 16a and 16b is connected to the main magnet 1
Each of 2a and 12b is magnetized so that the same poles face each other. That is, the main magnet 1
The north pole of 2a and the north pole of the facing main magnet 16a face each other,
The south pole of the main magnet 12b and the south pole of the facing main magnet 16b face each other. As a result, a repulsive magnetic field is formed between the main magnets 12a and 12b and the facing main magnets 16a and 16b.

In this way, in the space 20 between the main magnets 12a and 12b and the opposing main magnets 16a and 16b, x in the xy plane (horizontal plane) shown in the figure.
A magnetic field mainly composed of the magnetic flux A1 generated in the axial direction is formed.

The sub magnets 14a and 14b are arranged in a direction perpendicular to the lower inner surface 10L of the yoke 10 (z-axis direction).
, They are magnetized in opposite directions to each other, forming a magnetic circuit. However, these magnets 14a and 14b are magnetized so as to generate a magnetic flux in the opposite direction to the magnetic flux generated by the main magnets 12a and 12b. Thereby, from the N pole of one of the sub magnets 14b,
A magnetic flux is formed toward the south pole of the other sub-magnet 14a, the projection of which on the xy plane proceeds in the direction indicated by the arrow A2. Main magnets 12a, 12b and sub magnets 14a,
It is preferable to set the interval (distance in the Y-axis direction) between the surfaces of the magnets 14b facing each other in the range of 0.5 mm to 5 mm.

Opposing sub magnets 18a and 18b are magnetized so that the same poles face each other with respect to sub magnets 14a and 14b, respectively, and a repulsive magnetic field is formed by these magnets. This gives xy
In the plane (horizontal plane), a magnetic field having a magnetic flux A2 generated in the opposite direction to the magnetic flux A1 is formed.

Thus, the horizontal plane (x
(-Y plane), the main magnets 12a and 12b are x
A strong magnetic field is formed in the first direction along the axial direction, and the sub magnets 14a and 14b are formed along the first direction along the x-axis direction.
By forming a magnet having a certain strength in the second direction opposite to the direction of, the magnetic flux density in the x-axis direction is A rapidly changing magnetic field is formed along the direction (almost orthogonal). That is, the magnetic flux density in the x-axis direction is large on the back side of the main magnets 12a and 12b in the y-axis direction, but these magnets form at the positions between the main magnets 12a and 12b and the sub magnets 14a and 14b. The magnetic fields interfere (cancel each other), so that the magnetic flux density in the x-axis direction decreases. This gives y
A magnetic field with a strong gradient is formed along the axial direction.

When magnet materials having substantially equal residual magnetic flux densities are used, the volumes of the main magnets 12a and 12b are
It is desirable that the volume is at least twice the volume of the sub magnets 14a and 14b. This is the main magnets 12a and 12b
Of the magnetic field formed by the sub magnets 14a and 14b.
This is because the strength of the magnetic field is sufficiently higher than that of the magnetic field. In order to form a magnetic field that is sufficiently strong in a predetermined region and very weak in a region near it, as described above, the main magnets 12a and 12b and the sub magnet 14a are formed.
It is desirable to set the volume difference between the above and 14b to a certain degree.

The arrangement of the main magnets 12a and 12b and the sub magnets 14a and 14b on the lower inner surface 10L may be such that all the magnets are in contact with each other as shown in FIG. All may be spaced apart, as shown in b). Also, FIG.
As shown in (c), the end surface of the magnet may be formed using a circular magnet (that is, a columnar magnet).

Further, the lower inner surface 10L and the upper inner surface 10U of the yoke do not have to be one flat surface,
As shown in FIG. 2D, it may have a step. Further, it may be a curved surface.

(Second Embodiment) FIG. 3 shows the magnetic field of the second embodiment.
3 is a perspective view showing the configuration of the forming apparatus 200. FIG. Magnetic field forming equipment
The device 200 is different from the magnetic field forming device 100 of the first embodiment.
Main points are one main magnet 12a and the other main magnet
An additional sub magnet 22 is provided at a position between 12b and 12b.
That is the point. As a further sub magnet 22,
Sumitomo Special Gold with higher coercive force than in-magnets 12a and 12b
NEOMAX-39SH (H _cJ: 1671kA
/ M) can be used. This further sub magnet
22 corresponds to a fifth magnet.

FIG. 4 shows the lower main magnets 12a and 1a.
2B is a perspective view showing a sub magnet 22 and FIG. As shown in the figure, the sub magnet 22 is provided only in the upper half of the cutout portion 12c in the cutout portion 12c formed at the boundary between the main magnet 12a and the main magnet 12b. It is sandwiched by the magnet 12b. In addition, the magnetization direction of the sub magnet 22 is such that the main magnets 12a and 1a in the horizontal plane (xy plane).
2b is a direction substantially parallel to the direction A1 of the magnetic flux formed by 2b, and the N pole portion of the main magnet 12a and the sub magnet 22.
Of the main magnet 12b and the S pole of the sub magnet 22 face each other. In this case, in the magnet having the north pole and the south pole,
A portion closer to the pole is called an N pole portion, and a portion closer to the S pole than the N pole is called an S pole portion. Further, although the drawing shows the case where the sub magnet 22 is composed of two magnets, the sub magnet 22 may be composed of one magnet. If the sub magnet 22 is composed of two magnets, there is an advantage that it is easy to form a left-right symmetrical magnetic field.

Next, the function of the sub magnet 22 will be described with reference to FIGS. 5 (a) and 5 (b). Figure 5 (a)
Is the main magnets 12a and 12b (and the opposing main magnets 16a and 16) when the sub magnet 22 is not provided.
FIG. 5 (b) shows magnetic force lines representing the magnetic flux formed by b).
Shows the lines of magnetic force when the sub magnet 22 is provided.

As shown in FIG. 5A, when the sub magnet 22 is not provided, the magnetic flux (magnetic force line M1) generated away from the central portion C of the main magnets 12a and 12b is
While passing through the central portion 20 ′ in the z-axis direction (height direction) of the space 20, the magnetic flux generated near the central portion C (the magnetic force line M
2) will pass through a region in the space 20 close to the magnet surface. When such a magnetic field is formed, the space 2
It is difficult to improve the magnetic flux density in the central portion 20 ′ of 0.

On the other hand, when the sub magnet 22 is provided,
Since the N pole of the sub magnet 22 and the N pole portion of the main magnet 12a (or the opposing main magnet 16a) repel each other, a magnetic flux (a magnetic force line M1) generated away from the central portion C is generated.
Not only the magnetic flux generated near the central portion C (the magnetic force line M
2) also comes to pass through the central portion 20 'of the space 20. Thereby, the magnetic flux density in the central portion 20 'of the space 20 can be particularly improved.

When the sub magnet 22 is provided in this way, in order to form a magnetic field that repels the main magnet 12a as described above, the sub magnet 22 is cut out.
It is desirable to provide it only in the upper half of c (that is, the portion corresponding to the N pole portion of the main magnet 12a). Therefore, the height h2 of the sub magnet 22 is preferably 50% or less of the height h1 of the main magnet 12a. However, in order to obtain the effect of collecting the magnetic flux in the central portion 20 ′ of the space 20, the sub magnet 22 needs to have a certain volume, which is 10% or more of the height h1 of the main magnet 12a. Is desirable. The height of the sub magnet 22 is
If the height h1 of the main magnet 12a is about 10% to 66%, it effectively functions as a magnet for strengthening the magnetic flux. Further, the sub magnets 22 allow the main magnets 12a and 1
In order to effectively use the magnetic flux near the center of 2b, it is desirable to set the width W2 of the sub magnet to 1% to 30% of the width W1 of the entire main magnet.

The magnetic field forming device 20 configured as described above.
The magnetic field formed by 0 is shown in FIG. As shown in the figure, since the magnetic field formed by the main magnets 12a and 12b in the x-axis direction is strengthened by the sub magnet 22, a relatively high magnetic field can be formed at this portion, and the magnetic fields of the sub magnets 14a and 14b can be increased. In the vicinity,
Since the magnetic fields interfere with each other, almost no magnetic field is formed in the x-axis direction. Therefore, it becomes possible to form a magnetic field whose strength changes rapidly.

The sub magnet 22 is the main magnet 12a.
It is desirable that the coercive force is higher than that of the magnetic recording medium and 12b. Since the sub magnet 22 has a relatively small volume and the strength of the magnetic field formed is small, the sub magnet 22 is strongly influenced by the magnetic fields from the main magnets 12a and 12b, but this influence prevents the demagnetization of the sub magnet 22 from occurring. This is because

(Examples and Comparative Examples) FIG. 7 shows a magnetic field forming apparatus having no sub magnets 14a and 14b or 22 (Comparative Example), a magnetic field forming apparatus 100 of Example 1 (Example 1) and Embodiment 2. 6 is a graph when the magnetic flux density in the x-axis direction is measured at different positions along the y-axis direction when the magnetic field forming devices 200 (Example 2) are used. The position P1 shown in the graph corresponds to the end faces of the main magnets 12a and 12b on the sub magnet 14 side. Further, the position P2 shown in the graph indicates that the sub magnet 14
This corresponds to the position where a and 14b are provided. In the graph, the right side of the graph represents the main magnets 12a and 12b side, and the left side of the graph represents the sub magnets 14a and 14b side. Further, as shown in FIG. 3, the measurement of the magnetic flux density passes through the centers of the main magnets 12a and 12b, and at the height of the central portion in the height direction of the space 20, y is measured.
The direction indicated by the broken line Br is measured along the direction. The magnetic flux density was measured using a Gauss meter manufactured by Bell.

As can be seen from the graph, in the comparative example, a strong magnetic flux density is obtained by the main magnet, but a relatively strong magnetic flux density is observed even at a point away from the main magnet, and the magnetic flux density is sufficiently lowered. I can't. In this comparative example, 1 m at the end of the main magnet
Only a magnetic field with a small inclination such that a decrease of 0.04 T per m could be formed.

On the other hand, in the first embodiment, the sub magnet 14
Due to the influence of a and 14b, the main magnets 12a and 12
Even if it is relatively close to b, the magnetic flux density can be made almost zero.

Further, in the second embodiment, due to the influence of the sub-magnet 22, the magnetic flux density on the main magnets 12a and 12b side can be made relatively high, and the magnetic flux density is also relatively high near the position where the sub-magnet 22 is provided. Is obtained. Further, due to the influence of the sub magnets 14a and 14b, the magnetic flux density can be sufficiently reduced at a position slightly apart from the sub magnet 22. As a result of the measurement, in Example 2, the ends of the main magnets 12a and 12b (that is,
1 m in the vicinity of the portion where the sub magnet 22 is provided)
It was possible to form a magnetic field with a large gradient such that a decrease of 0.08 T per m was generated. In this way, a region having a strong magnetic flux density and a region having a weak magnetic flux density can be provided close to each other.

[0043]

According to the magnetic field forming device of the present invention, a magnetic field having a high magnetic flux density in a predetermined region and a very small magnetic flux density in a region near the predetermined region and having a large intensity gradient is formed. Is possible.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a magnetic field forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing another configuration of the magnetic field forming device according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing a configuration of a magnetic field forming apparatus according to a second embodiment of the present invention.

FIG. 4 is a perspective view showing a partial configuration of a magnetic field forming apparatus according to a second embodiment of the present invention.

FIG. 5 is a side view for explaining a magnetic field formed in the magnetic field forming device according to the second embodiment of the present invention.

FIG. 6 is a plan view showing a magnetic field formed in the magnetic field forming device according to the second embodiment of the present invention.

FIG. 7 is a graph showing measured magnetic flux densities in Comparative Example, Example 1, and Example 2.

[Explanation of symbols]

100, 200 Magnetic field forming device 10 Yoke material 12a and 12b main magnet 14a and 14b sub magnets 16a and 16b opposing main magnet 18a and 18b Opposing sub magnets 20 spaces 22 Further sub magnets

Claims (8)

[Claims] 1. A first pair of magnets each having a yoke material and having an N pole and an S pole and fixed to the yoke material to form a magnetic circuit. A first magnet from the north pole of one of the magnets to the south pole of the other magnet of the first pair of magnets;
A first pair of magnets that generate a magnetic flux, and each have an N pole and an S pole, and are arranged in parallel with the first pair of magnets in the vicinity of the first pair of magnets. And a second pair of magnets fixed to the yoke member to form a magnetic circuit, the N pole of one magnet of the second pair of magnets to the second pair of magnets. A second pair of magnets that generate a second magnetic flux toward the S pole of the other magnet, and the direction of the first magnetic flux and the direction of the second magnetic flux on a predetermined surface are opposite to each other. Orientation magnetic field shaping device. 2. The magnetization direction of each of the first pair of magnets is substantially perpendicular to each of the surfaces of the first pair of magnets fixed to the yoke member. The magnetization direction of each of the second pair of magnets is substantially perpendicular to each of the surfaces of the second pair of magnets fixed to the yoke member.
The magnetic field forming device according to. 3. A third pair of magnets provided at intervals so as to be opposed to the first pair of magnets, the first pair of magnets and the third pair of magnets. The magnetic field forming device according to claim 1 or 2, wherein magnetic fields that repel each other are formed by and. 4. A fourth pair of magnets provided at intervals so as to be opposed to the second pair of magnets, the second pair of magnets and the fourth pair of magnets. The magnetic field forming apparatus according to claim 3, wherein the magnetic fields form magnetic fields that repel each other. 5. The volume of each of the first pair of magnets is
The magnetic field forming device according to any one of claims 1 to 4, wherein the volume is at least twice the volume of each of the second pair of magnets. 6. The magnet is provided between one magnet of the first pair of magnets and the other magnet of the first pair of magnets, and is formed by the first pair of magnets. The first
6. The magnetic field forming apparatus according to claim 1, further comprising a fifth magnet having a magnetization direction parallel to the magnetic flux of. 7. The fifth magnet is located between an N-pole portion of one magnet of the first pair of magnets and an S-pole portion of the other magnet of the first pair of magnets. 7. The N pole of the fifth magnet faces the N pole portion of the one magnet, and the S pole of the fifth magnet faces the S pole portion of the other magnet. The magnetic field forming device according to. 8. The magnetic field forming apparatus according to claim 6, wherein the fifth magnet has a coercive force higher than that of the first pair of magnets.