JPH1012432A - Variable magnetic field type magnetic circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the intensity of magnetic field variable in a wide range by being comprised of a permanent magnet which is provided rotatably or movably and a magnetic yoke which has a linear part with a permanent magnet in its midway and an air gap at other predetermined position and allowing the permanent magnet to rotate or move so as to make a magnetic field in the air gap of the magnetic yoke to be vaiable. SOLUTION: A columnar permanent magnet 2 is rotated and driven on a columnar axis as a center, and a magnetic yoke 1 is provided with a linear part 1a with the magnet interposed in its midway and an air gap 4 with a predetermined spacing in the other part. Then, a magnetic flux generating from the magnet 2 at the time when the magnetizing direction of the magnet 2 is clockwise, passes through the yoke 1 and leaks to the air gap 4 of the yoke 1, forming a closed magnetic circuit for returning to the counter pole of the magnet 2. At this point, the intensity of magnetic field of the air gap 4 becomes the maximum. Further, as the magnet 2 is rotated gradually in its magnetizing direction, the flow of magnetic flux in the closed magnetic circuit becomes small gradually, and when the magnetizing direction becomes at 90 degrees against the closed magnetic circuit, the intensity thereof becomes zero.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a variable magnetic field type magnetic circuit. More specifically, the present invention relates to a variable magnetic field type magnetic circuit using a permanent magnet, which is optimally used when the magnetic field strength is 1T or less and is applicable to a magnetic field measuring device, magnetic field orientation, discharge plasma generation, iron material suction, and the like.

[0002]

2. Description of the Related Art Generally, in a permanent magnet magnetic circuit composed of a permanent magnet and a magnetic material, a magnetic field generated in a gap in the circuit has a constant strength and direction and cannot be changed. In the use of the permanent magnet magnetic circuit, the fact that the magnetic field is not fixed and not variable is one of the points lacking in versatility, which sometimes hinders the use. Also, when workers need to contact the permanent magnet magnetic circuit due to the presence of a magnetic field, it is necessary to work, and it is impossible to bring iron materials and tools made of iron close, and there is a concern that the magnetic field may affect the body. There was a problem.

On the other hand, in an electromagnet, the magnetic field can be varied by changing the value of a current flowing through a coil. Further, if the current is reversed, the direction of the magnetic field can be reversed, and the magnetic field strength can be changed or a strong magnetic field (up to about 2T) can be obtained.
Is easily obtained.

However, in order to obtain a sufficient magnetomotive force with an electromagnet, it is necessary to increase the number of coils and increase the magnetomotive force. Because of the coil, the volume of the electromagnet circuit becomes large, and in the case where the size of the working space is limited, the electromagnet cannot be used in many cases. Also, when the required magnetic field generation space is large or the required magnetic field strength is large, the current flowing through the coil increases, so the heat generation and power consumption of the coil cannot be ignored.
The capacity of the coil power supply is large and expensive.

An electromagnet is formed by winding a coil around a pole piece. However, since a magnetic field is generated in a direction perpendicular to the pole piece, it cannot be applied when a magnetic field is required in the axial direction of the inner cylinder space. In such a case, an air-core coil can be applied, but it is not easy to generate a strong magnetic field. For example, it is difficult, if not impossible, to generate a magnetic field of 100 mT or more in a large space with the air-core coil. In addition, when the magnetic field strength and the generated magnetic field space are increased, the coil current must be increased, which causes the same problems as ordinary electromagnets such as coil heat generation and power consumption.

As described above, since there are various problems in the electromagnet, a variable magnetic field magnetic circuit using a permanent magnet has been devised. For example, as shown in FIG. 5, the magnetic field can be made variable by changing the gap distance between the pair of opposed permanent magnets 51 and 52. In the magnetic circuit, the magnetic field strength decreases as the gap distance increases, and the magnetic field strength increases as the gap distance decreases. The change in the magnetic field strength is not proportional to the air gap distance, but as shown in FIG. 6, the magnetic field strength sharply increases as the air gap distance decreases, and the magnetic field strength decreases gradually as the air gap distance increases, and exceeds a certain level. Even if the air gap distance is increased, the magnetic field intensity does not decrease so much.

However, in the above-mentioned variable magnetic field magnetic circuit, it is impossible to reverse the magnetic field generation direction. When the gap distance is increased, the uniformity of the magnetic field in the gap decreases. Therefore, the variable magnetic field magnetic circuit is good when the magnetic field variable range is small, but unsuitable when the magnetic field variable range is large.

FIG. 7 shows a double dipole ring magnetic circuit in which dipole rings are combined in a double structure. The present magnetic circuit is configured such that the radial magnetic field strength generated in the internal space by the inner cylinder dipole ring circuit 71 and the radial magnetic field strength generated in the internal space by the outer cylinder dipole ring circuit 72 are the same, and the inner magnetic field is formed in the outer cylindrical space. Insert and install the tube. When the inner cylinder and the outer cylinder are rotated in opposite directions, the magnetic field strength can be changed from + to-without changing the magnetic field direction. In the magnetic circuit, since the magnetic field strengths of the inner cylinder and the outer cylinder are added, the variable magnetic field strength range is widened.

However, in the magnetic circuit, it is necessary to insert the inner cylinder into the outer cylinder, so that the inner diameter of the outer cylinder becomes large, the whole magnetic circuit becomes large, and the weight of the magnet used increases. In particular, since the magnet portion of the dipole ring circuit is complicated, it is difficult to form a structure using only magnets.
Since the yoke structure holding the magnet portion is arranged on the outer surface, the outer diameter is likely to be large.

Therefore, it is necessary to increase the inner diameter of the outer cylinder more than necessary. In addition, since the inner cylinder is inserted into the outer cylinder and rotated, the rotation mechanism is complicated and the scale becomes large. Further, when the magnetic field strength is zero, the opposite magnetic fields of the inner cylinder and the outer cylinder are internally opposed to each other, so that the repulsion force increases, the strength of the circuit holding structure increases, and the rotation torque must also increase.
Therefore, although the magnetic field variable range can be widened, there are various problems in structure and mechanism.

[0011]

As described above, there is a need for a permanent magnet magnetic circuit having a relatively simple structure and drive capable of varying the magnetic field strength and changing the polarity over a wide range. Accordingly, the present invention provides a variable magnetic field magnetic circuit using a permanent magnet having a simple structure, in which the direction of magnetic field generation is constant, the magnetic field strength can be varied in a wide range from + to-, and the polarity can be changed. With the goal.

[0012]

The invention according to claim 1 of the present application has a permanent magnet rotatably or movably provided, a linear portion sandwiching the permanent magnet in the middle, and is provided at another predetermined position. A variable magnetic field type magnetic circuit, comprising: a magnetic yoke having an air gap, wherein the magnetic field generated in the air gap of the magnetic yoke is made variable by rotating or moving the permanent magnet.

According to a second aspect of the present invention, the magnetic yoke has a plurality of linear portions sandwiching a plurality of permanent magnets in parallel, and the rotational position or the moving position of each of the permanent magnets is adjusted to adjust the gap. 2. A variable magnetic field type magnetic circuit according to claim 1, wherein the magnetic field generated in said variable magnetic field is variable.

According to the invention of claim 3 of the present application, the permanent magnet has a cylindrical shape, the magnetization direction is perpendicular to the cylindrical axis, and the permanent magnet has a cylindrical axis perpendicular to the linear portion of the magnetic yoke. 3. The variable magnetic field type magnetic circuit according to claim 1, wherein the variable magnetic field type magnetic circuit is provided so as to be rotatable about a center.

According to a fourth aspect of the present invention, the permanent magnet is magnetized in a direction parallel to the linear portion of the magnetic yoke, and is provided so as to be movable in a direction perpendicular to the linear portion. A variable magnetic field type magnetic circuit according to claim 1 or 2, is provided.

In the variable magnetic field type magnetic circuit according to the present invention, the magnetic field strength of the air gap provided in the magnetic yoke is made variable by rotating or moving a permanent magnet sandwiched between the magnetic yokes.

[0017]

FIG. 1 shows an embodiment of a variable magnetic field type magnetic circuit according to the present invention. The permanent magnet 2 has a columnar shape, and is magnetized in a direction perpendicular to the column axis. Permanent magnet 2
Is driven to rotate about the horizontal cylindrical axis by a rotation driving means (not shown). The magnetic yoke 1 is made of iron, for example, and has a linear portion 1a that sandwiches the permanent magnet 2 in the middle, and has a gap 4 at a predetermined interval in other places. The magnetic yoke 1 forms a square closed magnetic path via the permanent magnet 2 and the air gap 4.

Next, the variable operation of the magnetic field in the variable magnetic field type magnetic circuit will be described with reference to the schematic diagram of FIG. First, the magnetization direction of the permanent magnet 2 is first set to the right (FIG. 2A). At this time, the magnetic flux generated from the permanent magnet 2 passes through the magnetic yoke 1, seeps into the space 4 of the magnetic yoke 1, enters the opposite yoke again, and returns to the opposite magnetic pole of the permanent magnet 2. Form. At this time, the magnetic field generated in the air gap 4 is parallel to the closed magnetic circuit and directed leftward, and the magnetic field intensity becomes maximum.

By rotating the permanent magnet 2 from the above direction to gradually rotate the magnetization direction, the flow of the magnetic flux forming the closed magnetic path through the magnetic yoke 1 is determined by the magnetization direction of the permanent magnet 2 and the direction of the closed magnetic path. And gradually decreases as the deviation from (Fig. 2 (b)) increases. When the magnetization direction of the permanent magnet 2 is perpendicular to the closed magnetic path at 90 °,
Since the amount of magnetic flux flowing in the left and right yokes of the permanent magnet 2 becomes equal, the intensity of the magnetic field generated in the gap 4 becomes “0” (FIG. 2C).

When the permanent magnet 2 is further rotated, the magnetic field in the gap 4 is reversed, and the magnetic field strength in the opposite direction (right side) gradually increases. When the permanent magnet 2 rotates 180 ° from the initial position and turns leftward, the reverse magnetic field strength in the gap 4 becomes maximum (FIG. 2D).

As described above, the strength of the magnetic field in the air gap 4 can be changed and the direction can be reversed in accordance with the rotation of the permanent magnet. Further, in the magnetic circuit, since a magnetic field is generated in the gap of the yoke, the direction of the magnetic field is always constant,
Only its direction is reversed.

FIG. 3 shows another embodiment of the variable magnetic field type magnetic circuit according to the present invention. This variable magnetic field type magnetic circuit has basically the same configuration as the magnetic circuit shown in FIG. 1, but has permanent magnets 12 and 13 having substantially the same characteristics, and a magnetic yoke 11 is a straight line sandwiching both permanent magnets in parallel. Parts 11a, 11
b, and a gap 14 is provided at another predetermined position.

The variable magnetic field type magnetic circuit can change the magnetic field strength in the air gap 14 by rotating each of the permanent magnets having substantially the same characteristics. The relationship between the rotational position of each permanent magnet in the magnetic circuit and the direction and strength of the magnetic field generated in the air gap 14 is more complicated than when there is only one permanent magnet.

Next, the variable operation of the magnetic field in the variable magnetic field type magnetic circuit will be described with reference to the schematic diagram of FIG. First, both the permanent magnets 12 and 13 are directed rightward in a direction parallel to the linear portions 11a and 11b of the magnetic yoke (FIG. 4A). At this time, both magnetic fluxes generated from both permanent magnets rotate in the direction of the magnetic path including the air gap 14 to form a closed magnetic path. At this time, a maximum magnetic field is obtained in the gap 14 in the leftward direction.

Next, for example, when the permanent magnet 13 is fixed and the permanent magnet 12 is rotated, the permanent magnets 12 and 13 are rotated.
Of the magnetic fluxes generated, the magnetic flux passing through the closed magnetic path including the air gap 14 gradually decreases, and the magnetic flux passing through the closed magnetic path from the linear portion 11a to the linear portion 11b increases (FIG. 4B). Because, as the permanent magnet 12 rotates, the magnetic flux
This is because it is easier to flow a to the left and the magnetic path including the air gap 14 has a higher magnetic resistance. And the permanent magnet 1
When the direction of magnetization is turned 180 ° and turned to the left in the direction parallel to the linear portion 11a, the magnetic field generated in the gap 14 becomes substantially “0” (FIG. 4C). Thereafter, when the permanent magnet 12 is further rotated in the same direction, the leftward magnetic field gradually increases in the gap 14, and when the rotor rotates 360 ° and returns to the initial position, the gap 14 has the leftward direction again. A maximum magnetic field is obtained.

Next, from the state shown in FIG. 4C, the permanent magnet 12 which has been rotated until now is rotated by 180 ° from the initial position, that is, the magnetization direction is fixed to the left parallel to the linear portion 11a. Then, the permanent magnet 13 fixed so far is rotated (FIG. 4D). Then, a magnetic field in the opposite direction (rightward direction) is generated in the gap 14, and the permanent magnet 1
The rotation of 3 gradually increases the magnetic field strength. Permanent magnet 1
When the direction of the magnetic field is turned to the left in the direction parallel to the straight line portion 11b by rotating 3 by 180 °, a magnetic field having the same absolute value as the initial direction is obtained in the air gap.

In the case of the variable magnetic field type magnetic circuit shown in FIG. 3, there is another method of rotating the magnet, and even if the upper and lower two magnets are simultaneously rotated in the same or opposite directions, the magnetic field in the air gap 14 can be changed. Can be.

An advantage of using two magnets as shown in FIG. 3 is that the influence of the leakage magnetic field of the permanent magnet on the yoke gap can be reduced. In the case of one magnet shown in FIG. 1, when the permanent magnet is oriented at 90 ° with respect to the axial direction, the air gap magnetic field strength becomes zero. However, since the magnetic pole surface of the magnet faces the gap direction, if the distance between the magnet and the gap space is short, a leak magnetic field from the permanent magnet is generated in the gap space, and the magnetic field may not be completely zero. .

In order to prevent this, it is necessary to increase the distance between the permanent magnet and the gap space. However, in this case, the weight of the used yoke increases, and the magnetic circuit becomes large. On the other hand, in a magnetic circuit using two magnets, the movement of the magnet is slightly complicated, but when rotating one of the magnets, there is always a magnetic path between the magnet and the magnet. Magnetic flux is less likely to leak in the direction of high.

Therefore, even when the magnet is oriented in the 90 ° direction, direct leakage of the magnetic flux from the magnet to the gap is small, and the magnetic field intensity in the gap space can be reliably reduced to zero. When two magnets are used, there are basically three rotation modes as described above. However, rotating the magnets simultaneously in the same direction is not preferable for the above-described reason.

The number of magnets has been disclosed for one and two magnets, but may be three or more.

In addition to making the magnetomotive force variable by rotating the permanent magnet as described above, the magnetomotive force may be changed by inserting and removing the permanent magnet in a direction substantially perpendicular to the yoke axis. For example, in the variable magnetic field type magnetic circuit shown in FIG. 1, the direction of the magnetic field of the permanent magnet 2 is fixed to the direction parallel to the linear portion 1a to the right or to the left, and can be moved in the direction perpendicular to the linear portion 1a. I just need.

However, when there is only one magnet, the magnetic field strength can be changed only by inserting and removing the magnet in which the entire magnet is magnetized in one direction, but it is difficult to change the magnetic field direction (polarity). In this case, it is possible to change the magnetic field strength and the polarity by magnetizing one magnet in two poles in the right and left directions, and inserting and extracting the magnet and changing the magnet linearly. When there are two or more magnets, several drive modes are conceivable as in the case of rotary magnets.However, it is possible to change the magnetic field strength and magnetic field polarity by moving each magnet simultaneously or individually. It is possible.

The rotation and movement of the permanent magnet may be driven by a motor or the like, and the drive source is not particularly limited, such as electric, hydraulic, or pneumatic. In the case of driving by a motor, the magnet may be driven directly by the motor, or a reduction gear may be provided to reduce the required torque of the motor. When a plurality of magnets are used, it is possible to rotate them with one motor. However, it is preferable to rotate each magnet with a plurality of motors because the rotation of each magnet can be precisely controlled.

When viewed as a magnetic circuit, the variable magnetic field type magnetic circuit has basically the same configuration as the electromagnet except that the magnetomotive force generating source is not a coil but a permanent magnet. Therefore, the same usage as the electromagnet is possible. When the generated magnetic field is the same, the size of the magnetic circuit can be reduced by using a permanent magnet as the magnetomotive force source. In addition, since power is not consumed, there is no need to worry about heat generation, which is economically excellent. However, the magnetic field intensity that can be normally generated in the air gap depends on the air gap distance, but is generally at most about 1T.

[0036]

As described above, according to the present invention, a variable magnetic field type magnetic circuit capable of changing the magnetic field intensity and inverting the direction of the magnetic field and inverting the polarity can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a variable magnetic field type magnetic circuit of the present invention.

FIG. 2 is an explanatory diagram showing a magnetic field variable operation of the variable magnetic field type magnetic circuit of FIG. 1;

FIG. 3 is a perspective view showing another embodiment of the variable magnetic field type magnetic circuit of the present invention.

FIG. 4 is an explanatory diagram showing a magnetic field variable operation of the variable magnetic field type magnetic circuit of FIG. 3;

FIG. 5 is an explanatory diagram showing an example of a conventional variable magnetic field type magnetic circuit.

6 is a graph showing a relationship between a gap distance and a magnetic field strength in the variable magnetic field type magnetic circuit of FIG. 5;

FIG. 7 is a perspective view showing an example of a double dipole ring magnetic circuit.

[Explanation of symbols]

 1,11 Magnetic yokes 1a, 11a, 11b Linear part 2,12,13 Permanent magnet 4,14 Air gap

Claims (4)

[Claims] 1. A permanent magnet rotatably or movably provided, and a magnetic yoke having a linear portion sandwiching the permanent magnet in the middle and having a gap at another predetermined position, and rotating the permanent magnet. Alternatively, the variable magnetic field type magnetic circuit is characterized in that a magnetic field generated in the gap of the magnetic yoke is changed by moving the magnetic field. 2. The magnetic yoke has a plurality of linear portions sandwiching a plurality of permanent magnets in parallel, and adjusts a rotation position or a movement position of each permanent magnet to change a magnetic field generated in the gap. The variable magnetic field type magnetic circuit according to claim 1, wherein: 3. The permanent magnet has a cylindrical shape, a magnetization direction is perpendicular to a cylindrical axis, and is provided rotatably about a cylindrical axis perpendicular to the linear portion of the magnetic yoke. 3. The variable magnetic field type magnetic circuit according to claim 1, wherein: 4. The magnetic yoke according to claim 1, wherein the permanent magnet is magnetized in a direction parallel to the linear portion of the magnetic yoke and is movable in a direction perpendicular to the linear portion. Or the variable magnetic field type magnetic circuit according to 2.