JP2016100410A - Variable inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable inductor that has low power consumption and is capable of changing an inductance value.SOLUTION: A variable inductor 1 includes: a first inductor 10 including a first core 11 made from magnetic material and a first coil 12 formed by winding a wire material around the first core 11; a second inductor 20 including a second core 21 formed by encapsulating a non-magnetic fluid 24 and magnetic fluid 25 in a closed vessel 23 and a second coil 22 formed by winding a wire material around the second core 21, where the first core 11 and second core 21 are magnetically coupled when the first coil 12 has been energized; and an energization control unit 30 for controlling energization to the first coil 12 to set an inductance value of the second inductor 20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a variable inductor capable of changing an inductance.

  Conventionally, inductors have been widely used in electronic circuits. In such an inductor, when the current flowing through the inductor is equal to or less than a predetermined current value, the inductance value (so-called “L value”) maintains a substantially constant value, and the inductance value can be changed regardless of the current flowing through the inductor. There is a thing. These inductors are generally used properly depending on the application, but there is a technique described in Patent Document 1, for example, as a technique related to an inductor whose inductance value can be changed.

  The variable inductor described in Patent Document 1 includes an inductor made of a first magnetic body around which a coil to which a signal is applied (corresponding to the “wire material” of the present application) is wound, and a magnetic circuit at both ends of the first magnetic body. A second magnetic body provided so as to be formed, a control coil wound around the second magnetic body, and a current control circuit that controls a current flowing through the control coil. . In this variable inductor, a current is passed through the control coil to generate a magnetic field around the second magnetic body, and the magnetic permeability of the first magnetic body is changed by this magnetic field to change the inductance value of the inductor. . That is, the inductance value of the inductor can be changed by changing the current flowing through the control coil by the current control circuit.

JP-A-8-55733

  In the technique described in Patent Document 1, the amount of change in the magnetic permeability of the first magnetic body is about the hysteresis in the “magnetic hysteresis curve”. For example, when a large current is to be output from the coil, the second magnetic body It is necessary to increase the strength of the magnetic field generated around the. In order to increase the strength of the magnetic field generated around the second magnetic body, it is necessary to increase the current flowing through the control coil, resulting in increased power consumption and increased power loss due to Joule heat or the like. .

  In view of the above problems, an object of the present invention is to provide a variable inductor capable of changing an inductance value with low power consumption.

  In order to achieve the above object, the variable inductor according to the present invention is characterized by a first inductor having a first core made of a magnetic material and a first coil formed by winding a wire around the first core. And a second core formed by enclosing a magnetic fluid together with a nonmagnetic fluid in a sealed container, and a second coil formed by winding a wire around the second core, A second inductor in which the first core and the second core are magnetically coupled when the first coil is energized, and an inductance value of the second inductor by controlling the energization of the first coil. And an energization control unit for setting.

  With such a characteristic configuration, a magnetic field can be generated at both ends of the first core by flowing a current through the first coil, and the distribution of the magnetic fluid in the sealed container is changed according to the magnetic field. be able to. For this reason, since the magnetic permeability of the second core can be greatly changed, the inductance value of the second inductor can be greatly changed without increasing the current flowing through the first coil. Therefore, the inductance value can be changed with low power consumption.

  Further, the first core is an annular core having an opening in a part in a circumferential direction, and the second core is arranged so that a magnetic flux generated in the opening penetrates the inside of the second coil. It is preferable that

  With such a configuration, the magnetic resistance of the magnetic circuit formed by the first core and the second core can be reduced. Therefore, since the magnetic flux generated in the opening of the first core can be efficiently passed through the second core, the inductance value of the second inductor can be changed without increasing the current flowing through the first coil. Can be.

  In addition, the second coil is configured such that when the first coil is energized, the second coil and the magnetic fluid do not overlap when the second coil is viewed in the radial direction. It is preferable that

  With such a configuration, when the first coil is energized, the second coil can be made into an air-core coil. Therefore, when the first coil is energized and when it is not energized, The amount of change in the inductance value of the inductor 2 can be set large. Therefore, the setting range of the inductance value of the variable inductor can be increased.

It is the figure which showed the structure of the variable inductor typically. It is the figure which showed the state of the 2nd core before supplying with electricity to a 1st inductor. It is the figure which showed the state of the 2nd core at the time of supplying with electricity to a 1st inductor. It is a figure which shows the relationship between the inductance value of a 2nd inductor, and the electric current which flows into a 1st inductor. It is the figure which showed typically the structure of the variable inductor which concerns on other embodiment.

  The variable inductor according to the present invention is configured so that the inductance value can be changed greatly even with low power consumption. Hereinafter, the variable inductor 1 according to the present embodiment will be described. FIG. 1 is a diagram schematically showing the configuration of the variable inductor 1. The variable inductor 1 includes a first inductor 10, a second inductor 20, and an energization control unit 30.

Here, if the inductance value is L (H), the number of turns of the coil is N (T), the magnetic flux is φ (wb), and the current flowing through the coil is I (A),
L = N × φ / I (1)
The following formula is established.

On the other hand, when the magnetic flux density is B (T), the magnetic permeability is μ (H / m), the magnetic field strength is H (A / m), and the magnetic path area is S (m2), the magnetic flux φ is
φ = B × S = μ × H × S (2)
It becomes.

From the equations (1) and (2), the inductance value L is
L = N × μ × H × S / I (3)
It becomes. As shown in the equation (3), the inductance value is proportional to the magnetic permeability μ. Therefore, if the magnetic permeability μ is increased, the inductance value can be increased, and if the magnetic permeability μ is decreased, the inductance value can be decreased.

  The variable inductor 1 according to the present embodiment is configured to change the inductance value by changing the magnetic permeability.

  The first inductor 10 includes a first core 11 and a first coil 12. The first core 11 is made of a magnetic material. A magnetic substance is a substance that is magnetized when placed in a magnetic field, and examples thereof include iron oxide, chromium oxide, cobalt, and ferrite. The first core 11 is formed using such a material.

  The first core 11 of the present embodiment is constituted by an annular core having an opening 13 in a part in the circumferential direction. The annular core is not particularly limited to an annular shape, and may be configured to have a polygonal shape when viewed from the top, or may be configured such that the corners of the polygon are rounded in an arc shape. The opening 13 is a portion that is open such that a part of the annular core is cut off. In the present embodiment, as shown in FIG. 1, the first core 11 is formed in a U shape when viewed from the top, and the side facing the bottom 14 of the U groove in the U shape corresponds to the opening 13.

  The first coil 12 is formed by winding a wire around the first core 11. As the wire, a conductor coated with an insulating material is used. What wound such a wire around the first core 11 corresponds to the first coil 12. In the present embodiment, the first coil 12 is formed by winding a wire around the bottom 14 of the first core 11.

  The second inductor 20 includes a second core 21 and a second coil 22. The second core 21 is formed by enclosing a magnetic fluid 25 together with a nonmagnetic fluid 24 in a sealed container 23. The nonmagnetic fluid 24 is a substance that is not magnetized when placed in a magnetic field, and may be a gas or a liquid. As such a non-magnetic fluid 24, a fluid that does not mix with the magnetic fluid 25 and does not react may be used. In this embodiment, nitrogen gas is used as the nonmagnetic fluid 24. The magnetic fluid 25 is a fluid that is magnetized when placed in a magnetic field. In the present embodiment, a liquid is used as the magnetic fluid 25.

  In the present embodiment, the sealed container 23 is made of resin, and is sealed in a state where the above-described nonmagnetic fluid 24 and magnetic fluid 25 are filled in the container. Therefore, the sealed container 23 is not in a state where only the magnetic fluid 25 is filled. In the present embodiment, as shown in FIG. 1, the second core 21 is formed in a bar shape when viewed from above, and is disposed in the opening 13 of the first core 11.

  The second coil 22 is formed by winding a wire around the second core 21. As for the wire of the second coil 22, as in the first coil 12, a conductor coated with an insulating material is used. What wound such a wire around the second core 21 corresponds to the second coil 22. As shown in FIG. 1, the second coil 22 is formed by winding a wire such that the second coil 22 is positioned at the center of the opening 13 in the opening width direction when placed in the opening 13.

  The second core 21 is disposed so as to be magnetically coupled to the first core 11. Here, as will be described later, the first coil 12 is energized by the energization control unit 30. At this time, a magnetic field is generated around the first coil 12. The first core 11 collects the magnetic flux generated by the magnetic field generated around the first coil 12. The second core 21 is disposed in the opening 13 of the first core 11 and collects magnetic flux generated in the opening 13 of the first core 11. As described above, the first core 11 and the second core 21 are magnetically coupled, and the first core 11 and the second core 21 form a magnetic circuit.

  Further, as described above, a second coil 22 is formed by winding a wire around the second core 21. Therefore, the second core 21 is arranged so that the magnetic flux generated in the opening 13 penetrates the inside of the second coil 22. Thereby, the magnetic flux from the first core 11 can be passed through the second core 21.

  The energization control unit 30 controls the energization of the first coil 12 and sets the inductance value of the second inductor 20. When the energization control unit 30 controls the predetermined current to flow through the first coil 12, a magnetic flux corresponding to the current is generated around the first coil 12, and the magnetic flux is collected in the first core 11. Is done. At this time, the magnetic poles appearing at the open end portions 13A and 13B of the first core 11 change according to the direction of the current flowing through the first coil 12. Further, the magnetic flux density appearing at the open end portions 13A and 13B also changes according to the magnitude of the current flowing through the first coil 12.

  At this time, the distribution of the magnetic fluid 25 in the second core 21 changes according to the magnetic pole and magnetic flux density. Specifically, as the current flowing through the first coil 12 increases, the magnetic fluid 25 is gradually collected at each of both axial ends of the second core 21. That is, when attention is paid to the inside of the sealed container 23 of the second core 21, the magnetic fluid 25 is polarized at each of both axial end portions of the second core 21. Thereby, the magnetic permeability of the second core 21 changes. As described above, since the inductance value of the coil is proportional to the magnetic permeability, the inductance value of the second inductor 20 can be changed by changing the magnetic permeability of the second core 21.

  FIG. 2 shows a state before the energization control unit 30 energizes the first coil 12. The energization control unit 30 is indicated by a switch SW and a current source I for easy understanding. As shown in FIG. 2, before the first coil 12 is energized, the magnetic fluid 25 in the second core 21 stays without being polarized according to the gravity acting on the second core 21. ing.

  When the first coil 12 is energized, a magnetic pole corresponding to the direction of the current flowing through the first coil 12 is generated at the opening ends 13A and 13B of the first core 11, and the second core is generated according to the magnetic pole. The magnetic fluid 25 in 21 is polarized. When the current flowing through the first coil 12 is increased, the magnetic fluid 25 is finally collected only at both ends of the sealed container 23 as shown in FIG.

  Thus, when the current flowing through the first coil 12 is changed, the magnitude of the current and the inductance value of the second inductor 20 are in a proportional relationship. Such a relationship is shown in FIG. In FIG. 4, the vertical axis represents the inductance value (L value), and the horizontal axis represents the current flowing through the first coil 12. As shown in FIG. 4, the inductance value of the second inductor 20 decreases as the current flowing through the first coil 12 increases. The inductance value of the variable inductor 1 can be changed by adjusting the current flowing through the first coil 12 based on such characteristics.

  Here, in FIG. 3, when the first coil 12 is energized, the second coil 22 overlaps the second coil 22 and the magnetic fluid 25 when viewed in the radial direction. It is configured not to. As a result, the permeability of the second core 21 can be variously changed according to the energization of the first coil 12, so that the variable range of the inductance value of the second inductor 20 can be set large. It becomes.

[Other Embodiments]
In the above embodiment, the first core 11 is an annular core having the opening 13 and the second core 21 is disposed in the opening 13. However, the first core 11 is a rod-shaped core. It is also possible to configure by using. Such an embodiment is shown in FIG. In this case, the first core 11 and the second core 21 may be arranged side by side on the coaxial core. Even with such a configuration, the magnetic permeability of the second core 21 can be changed in accordance with the current flowing through the first coil 12, and the inductance value of the second inductor 20 can be changed.

  In the above embodiment, when the first coil 12 is energized, the second coil 22 looks at the second coil 22 in the radial direction so that the second coil 22 and the magnetic fluid 25 do not overlap. However, when the first coil 12 is energized, the second coil 22 is viewed in the radial direction when viewed from the second coil 22 and the magnetic fluid 25. It is also possible to configure so as to overlap.

  The present invention can be used for a variable inductor whose inductance can be changed.

1: Variable inductor 10: 1st inductor 11: 1st core 12: 1st coil 13: Opening part 20: 2nd inductor 21: 2nd core 22: 2nd coil 23: Airtight container 24: Non-magnetic fluid 25: Magnetic fluid 30: Current controller

Claims (3)

A first inductor having a first core made of a magnetic material, and a first coil formed by winding a wire around the first core;
A second core formed by sealing a magnetic fluid together with a non-magnetic fluid in a sealed container; and a second coil formed by winding a wire around the second core, and the first coil includes A second inductor in which the first core and the second core are magnetically coupled when energized;
An energization controller that controls energization of the first coil and sets an inductance value of the second inductor;
A variable inductor comprising: The first core is an annular core having an opening in a part of the circumferential direction;
2. The variable inductor according to claim 1, wherein the second core is disposed such that a magnetic flux generated in the opening penetrates the inside of the second coil.   The second coil is configured such that when the first coil is energized, the second coil and the magnetic fluid do not overlap when the second coil is viewed in the radial direction. The variable inductor according to claim 1 or 2.

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