JPH031809B2 - - Google Patents

Description

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

FIG. 1 is a side view of a conventional variable inductor of this type, in which a U-shaped core 1 and an I-shaped core 2 of magnetic material are combined, and a control coil 3 and a tuning coil 4 are wound around the core 1. . Tuned coil 4 is core 1
The wire is wound through the groove 5 provided at the tip of the wire. Then, by passing a direct current or low frequency current through the control coil 3, a closed magnetic path is formed between the cores 1 and 2 as shown by the dotted line 6, and by changing the magnetic flux density with the current, a closed magnetic path is formed in the tuned coil 4. The effective magnetic permeability of the core 1 is controlled and its inductance is changed. The dotted line 7 is a magnetic path by the tuning coil 4, and the groove 5 is provided mainly for structurally adjusting the magnetic flux density of the control coil 3 passing through the tuning coil 4.

However, in such a structure in which the magnetic path between the control coil 3 and the tuning coil 4 is completely closed, the inductance and temperature characteristics, which are the characteristics of the tuning coil 4, tend to vary depending on the contact state of the core 1 and the core 2. . In other words, slight variations in the mirror-finished state and dimensions of the surface of the contact portion 8 of the core 2 of the recoa 1 affect various characteristics. Since the cores 1 and 2 are usually fixed together with an adhesive, the state of contact may change due to the adhesive entering the contact portion 8. Furthermore, since the control coil 3 and the tuning coil 4 cannot be directly wound around the U-shaped core 1, they must be wound separately and fitted into the core 1. Furthermore, as described above, bonding work between the core 1 and the core 2 is also required.

As described above, the conventional structure requires high assembly precision between the cores, especially precision at the contact portion, so it is difficult to reduce variations in characteristics and the assembly work is troublesome.

An object of the present invention is to provide a highly practical variable inductor by improving the conventional decision points.

The current controlled variable inductor of the present invention has a hollow part in the winding part of the first core of the magnetic material around which the control coil is wound, and the first core of the magnetic material around which the tuning coil is wound in the hollow part. A second core is inserted so that its winding part is parallel to the winding part of the first core, and the first core is inserted into a third core made of a pot-shaped magnetic material. The third core is inserted perpendicularly to the bottom surface of the third core, and the respective magnetic paths generated by the control coil and the tuning coil overlap at the winding portion of the second core.

Embodiments of the current controlled variable inductor of the present invention will be described below with reference to FIGS. 2 and 3. FIG. 2 is an exploded perspective view showing only the core, and FIG. 3 is an explanatory view in a longitudinal section at the center when FIG. 2 is assembled.

In FIGS. 2 and 3, 10 and 11 are drum-shaped first and second cores, 12 is a pot-shaped third core, 13 is a base, and the first core 1 is
0, the second core 11, and the third core 12 are all made of ferrite, which is a magnetic material. The base 13 is made of synthetic resin.

The winding portion 14 of the first core 10 having circular flanges at both ends is provided with a hollow portion 15 having a circular cross section, the opening of which is located in the lower collar 20 . A control coil 17 is wound around the winding portion 14 .

A tuning coil 19 is wound around the winding part 18 of the second core 11, which has circular flanges at both ends, and is hollow so that the winding part 18 is parallel to the winding part 14 of the first core 10. It is inserted into the section 15. The upper flange 21 of the second core 11 contacts the lower surface 22 of the hollow part 15.

Further, 23 is a groove for drawing out the lead wire of the tuning coil 19. Further, the first core 10 is inserted into the third core 12, and the winding portion 14 is inserted into the third core 12.
is perpendicular to the bottom surface 24 of the core 12. The upper flange 25 contacts the bottom surface 24. The circular base 13 has a circular protrusion 26 in the center of its upper surface, and a terminal pin 27 for connecting the lead wires of the control coil 17 and the tuning coil 19 is implanted in its lower surface. The second core 11 is fixed onto the protrusion 26, and the first core 10 is fixed around the second core 11, respectively. Further, the side surface of the base 13 is fixed to the inner surface 16 of the third core 12. The protrusion 26 facilitates positioning of the first core 10 and the second core 11 on the base 13.
And the lower tsuba 20 of the first core 10 and the third core 1
between the inner surface 16 of the second core 11 and the lower flange 2 of the second core 11;
8 and the inner surface of the hollow portion 15 of the first core 10 are slightly apart from each other. Note that the second core 11
The contact portion between the upper flange 21 and the bottom surface 22 of the hollow portion 15, the upper flange 25 of the first core 10 and the third core 12
The contact portion with the bottom surface 24 may be brought into contact with a Mylar film or adhesive to prevent damage due to vibration.

In the variable inductor of the present invention configured in this manner, the magnetic path by the control coil 17 is connected to the winding portion 14 of the first core 10 and the third core 1 as shown by the dotted line 29.
2. Lower collar 20 of first core 10, second core 11
The lower flange 28 mainly extends to the winding portion 18 of the second core 11 . On the other hand, the tuned coil 19 creates a magnetic path that connects the winding portion 18 of the second core 11 as indicated by a dotted line 30.
It mainly extends to the winding portion 14 of the first core 10 , the lower collar 20 of the first core 10 , and the lower collar 28 of the second core 11 . The magnetic path 29 caused by the control coil 17 and the magnetic path 30 caused by the tuning coil 19 overlap most in the winding part 18 of the second core 11, and by changing the magnetic flux density by the control coil 17, the magnetic path 30 caused by the tuning coil 19
It is possible to control the effective magnetic permeability of 1 and change the inductance of the tuning coil 19.

4 to 7 are longitudinal sectional views showing different embodiments of the variable inductor of the present invention.

In FIG. 4, 40 is a first core, 41 is a second core, 42 is a third core, 43 is a base, 4
Reference numeral 4 denotes a hollow portion, in which a control coil 45 is wound around the first core 40 and a tuning coil 46 is wound around the second core 41 . The second core 41 has a lower flange 47 formed in two stages, a winding part 49 is formed between the upper tier and the upper flange 48, and the lower tier is in contact with the bottom of the lower flange 50 of the first core 40. This is different from the embodiments shown in FIGS. 2 and 3. In FIG. 4, the lower flange 50 of the first core 40 and the lower flange 47 of the second core 41 are in contact with each other, so the second
Compared to the cases shown in FIGS. 3 and 3, the magnetic path caused by the tuned coil 46 is closer to a closed magnetic path. Therefore, the influence of changes in magnetic flux density caused by the control coil 45 within the winding portion 49 can be reduced, and the inductance of the tuning coil 46 can be precisely controlled.

In FIG. 5, 60 is a first core, 61 is a second core, 62 is a third core, 63 is a base, 6
4 is a hollow part, a control coil 65 is wound around a first core 60 without a lower flange, and a tuning coil 6 is wound around a second core 61 whose lower flange 66 is larger than the upper flange.
7 is wound. Between the lower collar 66 of the first core 60 and the second core 61, between the lower collar 66 and the third core 62
The inner surfaces 69 of the two are separated from each other. Since the lower flange of the first core 60 does not exist, the magnetic path caused by the control coil 65 directly extends to the winding portion 68 through the lower flange 66 of the second core 61. Therefore, the magnetic flux density changes due to the control coil 65. The inductance of the tuning coil 67 can be controlled by increasing the influence of .

In FIG. 6, 70 is a first core through which a hollow portion 71 passes, 72 is a second core, and 73 is a third core.
74 is the base. The second core 72 and the inner surface 76 of the hollow portion 71 are separated from each other, and the lower flange 75 of the first core 70 and the inner surface 77 of the third core 73 are separated from each other. Since the hollow part 71 penetrates, the control coil 7
8. The magnetic path of the tuning coil 79 is close to an open magnetic path, which is suitable for use at high frequencies.
FIG. 7 shows a state in which the hollow portion 71 in FIG. 6 is closed with a core 80 made of a different material from the first core 70.

As described above, the current-controlled variable inductor of the present invention has a second core with a tuning coil wound inside, a first core with a control coil wound around the outside, and a pot-shaped third core. It is placed and fixed to the base. During manufacturing, a tuning coil may be wound around a second core fixed to the base, then a control coil may be wound around the outer first core, and finally a third core may be placed over the core. The structure can be modified in various ways within the scope of the present invention, as shown in FIGS. 4 to 7. Furthermore, the magnetic path caused by the control coil and the tuning coil is not a completely closed magnetic path, but there is a space in the middle. Therefore, compared to the conventional structure in which a plurality of cores are brought into contact with each other to form a closed magnetic circuit structure as shown in FIG. 1, there is no need for mirror finishing of the contact portion, and variations in characteristics can be reduced. Furthermore, since high-frequency coil winding technology can be used, assembly is easy.

Thus, according to the present invention, a highly practical current-controlled variable inductor can be provided.

[Brief explanation of the drawing]

Fig. 1 is a side view of a conventional current-controlled variable inductor, Fig. 2 is an exploded perspective view showing an embodiment of the current-controlled variable inductor of the present invention, and Fig. 3 is an explanatory diagram when Fig. 2 is assembled. , FIG. 4 to FIG. 7 are longitudinal sectional views showing different embodiments of the current controlled variable inductor of the present invention. 10, 40, 60, 70: first core, 11,
41, 61, 72: second core, 12, 42, 6
2,73: Third core, 13,43,63,7
4: Base, 14, 18, 49, 68: Winding part,
15, 44, 64, 71: Hollow part, 16, 69,
76, 77: Inner surface, 17, 45, 65, 78:
Control coil, 19, 46, 67, 79: Tuning coil, 20, 28, 47, 50, 66, 75: Lower tsuba, 21, 25, 48: Upper tsuba, 22, 24: Bottom surface, 26: Projection, 29 , 30: magnetic path, 80: core.

Claims (1)

[Claims] 1 A hollow part is provided in the winding part of the first core made of magnetic material around which the control coil is wound, and the second core made of magnetic material around which the tuning coil is wound in the hollow part is inserted into the winding part. is inserted so that it is parallel to the winding part of the first 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 coil is inserted into the third core, and a space is provided in the middle of at least one of the magnetic paths generated by the control coil and the tuning coil, and each magnetic path overlaps at the winding part of the second core. A current controlled variable inductor featuring: