JPH0331063Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a current-controlled variable inductor that can reduce the control current for adjusting inductance.

[Prior art and its problems]

FIG. 9 is a front view of a conventional variable inductor of this type, in which a first core 1 made of a toroidal core without an open part and a U-shaped second core 2 are combined,
A tuning coil 3 is wound around the core 1, and a control coil 4 is wound around the core 2, respectively. Core 1 is fitted into the open portion of core 2. By applying a direct current to the control coil 4, the magnetic flux 5 extends from the core 2 into the core 1, changing the effective magnetic permeability of the core 1 and adjusting the inductance of the tuning coil 3. As shown in the characteristic diagram of FIG. 10, the relationship between the control current I and the inductance L is such that the inductance L is large when the control current I is small, and decreases as the value increases.

However, in this variable inductor, there is a range in which adjustment by the control current is not effective due to the characteristics of the core and the leakage of the magnetic flux 5 in the magnetic circuit. 10th
In the figure, there is no adjustment effect when the control current is in the range of 0 to _I1 . Therefore, this extra current increases the control current, generates heat, and increases the capacity of the power supply, which limits its applications.

Further, the conventional variable inductor shown in FIG. 1 has a first core 11 made of a toroidal core without an open part.
A tuning coil 13 is wound around the U-shaped second
A control coil 14 is wound around the core 12 of.
The cross section of the core 12 is a rectangle close to a square, and the core 11 and a rod-shaped permanent magnet 16 are fitted into an open portion 15 of the core 12 . A magnet 16 having the same cross-sectional shape as the core 12 is magnetized in the illustrated direction and is in contact with the cores 11 and 12.

In the current-controlled variable inductor shown in FIG. 1, the magnetic flux 17 from the control coil 14, together with the magnetic flux from the magnet 16, extends into the core 11 to change its effective magnetic permeability. The magnetic flux density of the magnet 16 is made approximately equal to the magnetic flux density produced by the maximum value of the control current without the effect of adjusting the inductance. The control current I ₁ in FIG. 10 corresponds to this control current. By magnetically biasing the magnetic flux of the magnet 16 in a direction that strengthens the magnetic flux 17 of the control coil 14, the relationship between the inductance L and the control current I becomes as shown in the characteristic diagram of FIG. That is, the magnetic flux of the magnet 16 serves as a bias component, and the control current I is within a range where the adjustment of the inductance L is not effective.
Therefore, the zero position of the control current I moves to the right by the bias amount, producing the effect of adjusting the inductance L from a small value.

Furthermore, FIG. 3 is a front view of another conventional variable inductor.

Unlike FIG. 1, three of the first cores 21 made of toroidal cores are fitted into the open portion 25 of the U-shaped second core 22 together with a permanent magnet 26. A tuning coil 23 is wound around each of the first cores 21 having the same shape, and a control coil 2 is wound around the second core 22.
4 is wound. As in FIG. 1, the magnetization direction of the magnet 26 is in a direction that strengthens the magnetic flux 27 caused by the control coil 24.

The current-controlled variable inductor shown in FIG. 3 extends within the three first cores 21 with the magnetic flux 27 from the control coil 24 added to the magnetic flux from the magnet 26.
By changing the effective magnetic permeability, the inductances of the three tuned coils 23 can be adjusted simultaneously.

However, the variable inductors shown in Figures 1 and 3 are
Since a toroidal core or U-shaped core is used, it is inconvenient when winding the coil. Furthermore, since the coil cannot be wound with high precision, the inductance cannot be adjusted with high precision.

〔the purpose〕

An object of the present invention is to provide a current-controlled variable inductor that is easy to assemble by using high-frequency coil winding technology.

[Technical means to solve problems]

The current-controlled variable inductor of the present invention has a hollow portion in the winding portion of a first core of a drum-shaped magnetic material around which a control coil or a tuning coil is wound.
A second core made of a drum-shaped magnetic material around which the remaining coils are wound is inserted into the hollow part so that the winding part of the second core is parallel to the winding part of the first core. The core has a third winding part made of a pot-shaped magnetic material.
The control coil is inserted into the third core so as to be perpendicular to the bottom surface of the core, and a permanent magnet is placed at a position where the magnetic flux of the control coil passes through to magnetically bias the magnetic flux. shall be.

〔Example〕

Hereinafter, an embodiment of the current controlled variable inductor of the present invention will be described with reference to FIGS. 4 and 5. FIG. 4 is an explanatory diagram, and FIG. 5 is an exploded perspective view. In FIG. 5, illustration of the coil is omitted.

In FIGS. 4 and 5, 30 and 31 are drum-shaped first and second cores, respectively, and 32 is a pot-shaped third core.
The core 33 is a base, the first core 30,
Both the second core 31 and the third core 32 are made of ferrite. The base 33 is made of synthetic resin. The winding portion 34 of the second core 31 having circular flanges at both ends is provided with a hollow portion 35 having a circular cross section, the opening of which is located in the lower collar 36 . A control coil 37 is wound around the winding portion 34 . A tuning coil 39 is wound around the winding part 38 of the first core 30 , and the winding part 38 is inserted into the hollow part 35 so as to be parallel to the winding part 34 of the second core 31 . The upper flange 40 of the first core 30 has a hollow portion 35
the bottom surface 41 of. A permanent magnet 42 is located below the lower flange 49. The magnet 42 is in contact with the inner surface of the hollow portion 35 and the lower flange 49, and is magnetized in the thickness direction. Furthermore, although the second core 31 is inserted into the third core 32, the winding portion 34 is perpendicular to the bottom surface 43 of the third core 32, and the upper flange 44 contacts the bottom surface 43.

magnet 42, first core 30, second core 31,
The third core 32 is fixed on a central circular protrusion 45 on the upper surface of the base 33. Also base 33
is fixed to the inner surface 47 of the third core 32 . A terminal pin 46 for connecting the lead wires of the control coil 37 and the tuning coil 39 is implanted on the lower surface of the base 33.

The magnetic flux 48 generated by the control coil 37 of the variable inductor configured in this manner extends into the winding portion 38 of the first core 30 with the magnetic flux of the magnet 42 added thereto, thereby changing the effective magnetic permeability. Tuning coil 39
The inductance can be adjusted. third core 32
serves to prevent the magnetic flux 48 of the second core 31 from dispersing.

FIGS. 6 and 7 are explanatory diagrams showing different embodiments of the variable inductor of the present invention.

In FIG. 6, a hole is provided in the bottom surface 51 of the third core 50, and a permanent magnet 52 is fitted into this hole. 5
3 is a tuning coil wound around the first core 54, and 55 is a control coil wound around the second core 56. In this embodiment, the magnet 52 is the fourth
Since the magnet 52 is exposed on the outer surface compared to the case shown in FIG. In FIG. 7, the winding portion of the second core 61 around which the control coil 60 is wound is shown as follows.
A permanent magnet 68 is located between the upper flange 65 of the first core 64 around which the tuning coil 63 is wound and the bottom surface 67 of the third core 66 .

The variable inductor of the present invention can be configured in various ways using the drum core. In both embodiments, the tuning coil is located inside the control coil, but this may be reversed. The permanent magnet 52 in FIG.
It is also possible to screw it into a hole in the bottom surface 21 of the third core 50 and move it up and down. Furthermore, in any of the embodiments, the directions of the magnetic fluxes of the permanent magnet and the control coil can be reversed and added together. Although this goes against the original purpose of the present invention, for example, if the magnetic flux density of the permanent magnet is made much higher than the magnetic flux density of the control coil, the relationship between the inductance L and the control current I can be changed to the characteristic diagram shown in FIG. As shown, the shape can be reversed to that shown in FIG. In FIG. 8, at the maximum value of the inductance L, the magnetic flux caused by the control coil in the first core cancels out the magnetic flux of the magnet and is in a substantially zero state. Such characteristics are incidentally obtained by the present invention.

〔effect〕

As described above, the current-controlled variable inductor of the present invention is easy to assemble because it can be wound sequentially from the inner drum-shaped core to the outer drum-shaped core using high-frequency coil winding technology. . Since an automatic machine can be used, the coil winding accuracy can be increased. Furthermore, it has a permanent magnet to magnetically bias and strengthen the magnetic flux generated by the control coil, and the inductance of the tuning coil can be adjusted with a small amount of current of the control coil. Therefore, power dissipation can be reduced, and since the wire can be made thinner, the structure can be made more compact. Also, the capacity of the power supply becomes smaller. Of course, it is desirable from the viewpoint of reliability as it generates less heat. In this way, the current controlled variable inductor of the present invention can greatly improve its practicality and expand its applications.

[Brief explanation of the drawing]

Figure 1 is a front view of a conventional current-controlled variable inductor, Figure 2 is a characteristic diagram of Figure 1, Figure 3 is a front view of another conventional current-controlled variable inductor, and Figures 4 and 5. 6 and 7 are an explanatory diagram and an exploded perspective view showing an embodiment of the current controlled variable inductor of the present invention.
The figure is an explanatory diagram showing yet another embodiment, and FIG. 8 is another characteristic diagram of the current controlled variable inductor of the present invention.
FIG. 9 is a front view of a conventional current-controlled variable inductor, and FIG. 10 is a characteristic diagram of FIG. 9. 11, 21, 30...first core, 12, 2
2, 31... second core, 13, 23, 39...
Tuning coil, 14, 24, 37... control coil,
16,26,42...Permanent magnet, 17,27,4
8...Magnetic flux.

Claims (1)

[Scope of utility model registration request] A hollow part is provided in the winding part of the first core of the drum-shaped magnetic material around which the control coil or the tuning coil is wound, and the remaining coils are wound in the hollow part of the drum-shaped magnetic material. The winding part of the second core is
The first core is inserted so that it is parallel to the winding part of the third core, and the first core is inserted into the third core so that its winding part is perpendicular to the bottom surface of the third core, which is made of a pot-shaped magnetic material. A current-controlled variable inductor characterized in that a permanent magnet is inserted into the core and arranged at a position where the magnetic flux of a control coil passes through to magnetically bias the magnetic flux.