JPH0247093B2 - DENRYUSEIGYOGATAKAHENINDAKUTA - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a current-controlled variable inductor used in an electronic tuning circuit such as a car tuner.

[Prior art and its problems]

FIG. 3 is an explanatory diagram of a conventional current controlled variable inductor, which has already been filed by the present applicant as Japanese Patent Application No. 14822/1983.

A control coil 2 is wound around the first core 1, and a second core 5 around which a tuning coil 4 is wound is inserted into a hollow portion 3 provided in the winding portion. Furthermore, the first core 1 is covered with a pot-shaped third core 6. 7 is a base on which the first core 1 and the second core 5 are placed and the third core 6 is fitted, and 8 is a terminal pin. control coil 2
The magnetic path by the tuned coil 4 extends from the first core 1 to the third core 6 as represented by the dotted line 9, and the magnetic path by the tuned coil 4 extends from the second core 5 to the first core as represented by the dotted line 10. 1, but both magnetic paths 9 and 1
0 overlaps the most in the winding portion 11 of the second core 5. Then, the second
It is possible to control the effective magnetic permeability of the core 5 and change the inductance of the tuning coil 4. The variable ratio of inductance, that is, the value obtained by dividing the maximum value by the minimum value, increases when a first core for low frequencies and with a high magnetic flux density is used. On the other hand, since a high frequency current flows through the tuning coil 4, the second core 5 must be used for high frequencies and have a low magnetic flux density to reduce loss.

However, in the structure shown in FIG. 3, the magnetic path 10 by the tuned coil 4 also extends into the first core 1, and the loss in that part of the first core 1, which is a core for low frequencies, increases. There is a limit to increasing the inductance and Q value of the tuning coil 4, as well as the variable ratio.

〔the purpose〕

The object of the invention is to eliminate the above-mentioned drawbacks by ensuring that the main magnetic path of the tuning coil does not extend into the core around which the control coil is wound.

[Technical means to solve problems]

In the present invention, a hollow part is provided in the winding part of the first core, and the second core is inserted into the hollow part so that the winding part of the first core is provided with a hollow part.
The first core is inserted so that it is parallel to the winding part of the third core, and the first core is inserted so that its winding part is perpendicular to the bottom surface of the pot-shaped third core. The magnetic path of the control coil wound around the first core and the tuning coil wound around the second core is the second magnetic path.
In the current-controlled variable inductor whose core windings overlap, the second core in the hollow portion is covered with at least one other core.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a current controlled variable inductor of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is an explanatory longitudinal cross-sectional view, and FIG. 2 is an exploded perspective view showing the coils removed.

In FIGS. 1 and 2, 20 and 21 are a first core and a second core, respectively, 22 is a pot-shaped third core, 23 is a pot-shaped fourth core, and 24 is a base. The first core 20 and third core 22 are ferrite cores for low frequencies, and the second core 21 and fourth core 23 are ferrite cores for high frequencies suitable for use at the frequency of the current flowing through the tuning coil 30. . The base 24 is made of synthetic resin.

The winding portion 25 of the first core 20 having circular flanges at both ends is provided with a hollow portion 26 having a circular cross section, the opening of which is located in the lower collar 27 . Winding part 25
A control coil 28 is wound around. The fourth core 23 is fitted into the hollow portion 26.

A tuning coil 30 is wound around the winding portion 29 of the second core 21, which has circular flanges at both ends.
The winding portion 29 is inserted into the fourth core 23 so as to be parallel to the winding portion 25 of the first core 20 . The second core 21 is entirely covered by the fourth core 23.

Furthermore, the first core 20 is inserted into the third core 22 , and the winding portion 25 is perpendicular to the bottom surface 32 of the third core 22 . The third core 22 has a magnetic path 33 of the control coil 28 formed therein, and serves to prevent its divergence.

The base 24 has a circular protrusion 34 in the center of its upper surface, and the protrusion 3 of the second core 21 is inserted into the hole 35.
6 is fitted. A terminal pin 41 for connecting the lead wires of the control coil 28 and the tuning coil 30 is implanted on the lower surface. The upper flange 38 of the first core 20 and the bottom surface 32 of the third core 22, the hollow part 26 and the fourth core 23, the bottom surface 44 of the fourth core 23 and the upper flange 37 of the second core 21 are Although there is a slight gap between the inner surfaces 45 of the first core 20 and the third core 22 and between the inner surfaces 46 of the second core 21 and the fourth core 23, the characteristics are stable. Mylar film or the like may be sandwiched between the contact areas and the gaps in order to improve the properties and physical strength. The groove 42 of the second core 21 and the groove 43 of the base 24 are grooves for passing the lead wire. If the fourth core 23 is made of metal, its dimensional accuracy can be improved. In the variable inductor of the present invention configured in this way, the magnetic path 33 by the control coil 28 is connected to the second core 21 as shown by the dotted line.
The winding portion 29 and upper flange 37, the fourth core 23, the first
upper collar 38 of the core 20, third core 22, lower collar 27 of the first core 20, lower collar 39 of the second core 21
and extends. The other magnetic path 40 by the tuned coil 30
are the winding portion 29 of the second core 21, the upper collar 37, and the fourth
The core 23 extends to the lower flange 39 of the second core 21. The magnetic path 33 and the magnetic path 40 are connected to the second core 21
The most overlap occurs in the winding portion 29 of the control coil 28.
By changing the magnetic flux density, the effective magnetic permeability of the second core 21 can be controlled and the inductance and Q of the tuning coil 30 can be adjusted. Furthermore, the magnetic path 40 of the tuned coil 30 is mainly located within the core for high frequency, both of the fourth core 23 and the second core 21, so that high frequency loss can be reduced. Furthermore, the magnetic path 33 formed by the control coil 28 is located mostly within the first core 20 and the third core 22, which are cores for low frequencies, so that changes in magnetic flux density due to current can be increased. And the inductance of the tuning coil 30 and Q
, and their changes can be increased.

4 to 6 are cross-sectional views showing different embodiments of the current controlled variable inductor of the present invention.

In FIG. 4, 50 is a first core, 51 is a second core, 52 is a third core, and 53 is a fourth core.
A tuning coil 55 is wound around the core 51 of. The hollow portion 56 of the first core 50 passes through the winding portion 57, and the fourth core 53 fits into this hollow portion 56. Furthermore, a second core 51 is inserted into the fourth core 53.
has been inserted. The magnetic path of the tuned coil 55 is within the second core 51 and the fourth core 53 for high frequency, and the magnetic path of the control coil 54 is within the second core 51 and the fourth core 53.
They are located in the first core 50 and third core 52 for low frequency, but the magnetic path in the core for low frequency is shorter than in the embodiments shown in FIGS. 1 and 2, and the magnetic path in the core for high frequency is The magnetic path inside the core becomes longer. Therefore, the inductance and Q become large, but the variable ratio becomes somewhat small.

In FIG. 5, a cylindrical fifth core 62 is fitted into the hollow portion 61 of the first core 60, and a pot-shaped fourth core 63 is fitted into the fifth core 62. The second core 64 and the fourth core 63 are for high frequencies, the first core 60 and the third core 65 are for low frequencies, and the fifth core is for low frequencies.
The above-mentioned characteristics can be finely adjusted by using a core 62 in between.

FIG. 6 shows a fourth core 72 that covers the second core 75 in order to more completely fit the fourth core 72 into the hollow part 71 of the first core 70 and to obtain stability of characteristics. A lower tsuba 73 is provided on the core 72 of 4, and the lower tsuba 7
3 and the lower collar 74 of the first core 70 from below.

〔effect〕

As described above, in the current controlled variable inductor of the present invention, at least one core that covers the second core around which the tuning coil is wound is arranged in the hollow part of the first core around which the control coil is wound. By doing so, inductance, Q, and variable ratio can be improved. Specifically, these values can be increased and, moreover, these values can be maintained up to a higher frequency range than in the past. Furthermore, the characteristics of the core covering the second core, the fourth core and the fifth core in the embodiment, can be varied to provide a variety of characteristics of the variable inductor. The practical frequency range has been increased from the conventional 2M
It can be expanded from about Hz to about 120MHz.

[Brief explanation of the drawing]

Fig. 1 is an explanatory longitudinal cross-sectional view showing an embodiment of the current-controlled variable inductor of the present invention, Fig. 2 is an exploded perspective view, Fig. 3 is a longitudinal cross-sectional view of a conventional current-controlled variable inductor, and Fig. 4. to FIG. 6 are longitudinal sectional views showing other embodiments of the current controlled variable inductor of the present invention. 20, 50, 60, 70: first core, 21,
51, 64, 75: second core, 22, 52, 6
5: 3rd core, 23, 53, 63, 72: 4th
Core, 24: Base, 25, 29: Winding part, 2
6, 56, 61, 71: Hollow part, 27, 39, 7
3, 74: Lower tsuba, 28, 54: Control coil, 3
0,55: Tuning coil, 32,44: Bottom, 3
3, 40: Magnetic path, 37, 38: Upper guard, 42, 4
3: groove, 45, 46: inner surface, 62: fifth core.

Claims (1)

[Claims] 1 A hollow part is provided in the winding part of the first core,
A second core is inserted into the hollow portion so that its winding portion is parallel to the winding portion of the first core,
Furthermore, the first core has a pot-shaped third winding portion.
It is inserted perpendicular to the bottom of the core.
In a current-controlled variable inductor in which magnetic paths of a control coil wound around a first core and a tuning coil wound around a second core overlap at a winding portion of the second core, a second A current-controlled variable inductor, characterized in that the core is covered with at least one other core.