JPS61294805A - External temperature compensation type inductor - Google Patents

Abstract

PURPOSE:To obtain the inductor whose inductance changes smaller with the external air temperature, by inserting several kinds of temperature-sensitive magnetic materials having different low Curie temperature in a part of magnetic circuit of the magnetic core made of high Curie temperature magnetic material. CONSTITUTION:Several kinds of temperature-sensitive magnetic materials having different low Curie temperature are inserted in a part of the magnetic core 2 made of high Curie temperature magnetic material, and thus a closed magnetic circuit is formed. The winding 4 is wound around this magnetic core 2, and forms the external temperature compensation type inductor whose inductance L is stable to the changes of the external air temperature (t). According as the external air temperature (t) rises, the several kinds of temperature-sensitive magnetic materials change their Curie temperature and permeability to the direction of large variation, and reduce the variation of the inductance L.

Description

[Detailed description of the invention] [Industrial application field] The present invention is a resonant circuit in combination with a capacitor.

This invention relates to temperature compensated inductors used in electronic circuits such as filter circuits and matching circuits.

[Conventional technology]

The resonant frequency f (Hz) of a resonant circuit used in filter circuits, matching circuits, etc. is adjusted.In order for the resonant frequency f of this resonant circuit to remain constant and stable, the capacitance C and inductance L must be constant. Conventionally used inductors form a closed magnetic path with a magnetic core 2 made of a magnetic material, as shown in FIG.

It is formed by winding a winding 4 around a magnetic core 2 in the closed magnetic path. This kind of inductance is the shape of the magnetic material,
If the cross-sectional area S of a magnetic core made of a magnetic material with an AC initial permeability μiac is determined by the material and the number of turns N of the winding, and the magnetic path length is t, it can be expressed as L=μS/1XN2. In this equation, the inductance L tends to increase as the outside temperature [°C] changes, as shown in Figure 5, and the reason for this is the change in the magnetic permeability μiac of the magnetic material. . That is, as shown in FIG. 6, the change in magnetic permeability μiac with respect to the change in outside temperature t increases as the temperature rises, and sharply decreases when the Curie temperature is reached. Therefore, the temperature range in which it can be used as an inductor is up to the Curie temperature, and the inductance has a positive temperature coefficient.

[Problem that the invention seeks to solve]

Conventional inductors have inductance L that changes depending on the outside temperature, so they cannot be used in places where the outside temperature changes because the resonance frequency is unstable, and they cannot be used in places where the outside temperature changes little. In order to maintain the resonant frequency f accurately and stably, such as means for keeping the outside air temperature constant, or means for correcting it by changing the temperature coefficient of the capacitor C, the electronic circuitry is extremely expensive.

[Means for solving problems]

The present invention eliminates such drawbacks of the conventional technology and forms a closed magnetic path by inserting a plurality of types of temperature-sensitive magnetic materials with different low Curie temperatures into a part of the magnetic core 2 made of a magnetic material with a high Curie temperature. This is an outside temperature compensated inductor in which a winding 4 is wound around a core 2 and the inductance L value is stable against changes in outside temperature t.

[Effect]

A plurality of types of temperature-sensitive magnetic materials having a low Curie temperature move and change the Curie temperature and magnetic permeability in the direction of a larger change each time the outside air temperature rises, thereby reducing a change in the value of the inductance L.

〔Example〕

In the embodiment of the present invention, as shown in FIG. 1, a central leg 1 is butted against an E-shaped magnetic core 2 whose length is shorter than the other legs 2.
A gap 3 is provided between the central legs 1. 2 in this cavity 3
A magnetic core made of temperature-sensitive magnetic materials having different Curie temperatures or more is inserted to form a closed magnetic circuit, and a winding 4 is wound around the central leg 1 to form an outside temperature compensated inductor.

The temperature-sensitive magnetic bodies inserted into the air gap 3 of this inductor have different Curie temperatures, and their operation is as shown in the curve showing the relationship between the outside temperature t and the magnetic permeability μiac in Figure 2. When the temperature rises and the temperature-sensitive magnetic material in the temperature range of curve a reaches the Curie temperature, the magnetic permeability μi suddenly decreases.
ac decreases. However, since the temperature range of the curve is reached and a similar phenomenon occurs, even when combined with magnetic core 2, the value of inductance L decreases only at one temperature of the temperature-sensitive magnetic material's Curie temperature, and above the Curie temperature of this temperature-sensitive magnetic material. The decreased value is transferred to the next temperature-sensitive magnetic material, and a magnetic permeability μiac with little change is obtained. Further, as shown in FIG. 6, changes in the outside temperature t and changes in the value of the inductance L in the inductor of the present invention are shown. As shown in the figure, the curve has a positive temperature coefficient as in conventional inductors. In addition, the curve is -20 to 50℃ according to the present invention.
1 curve C is an inductance value using a temperature-sensitive magnetic material of -20 to +80°C, which has a negative temperature coefficient, and its change is smaller than that of the conventional one.

〔Effect of the invention〕

As described above, according to the present invention, an inductor with a negative temperature coefficient and a small change in the value of inductance L with respect to changes in outside temperature t can be obtained, and a stable resonant frequency with respect to outside temperature t can be obtained. Electronic circuits such as resonant circuits and filter circuits are formed.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view of an embodiment of the inductor of the present invention, FIG. 2 is a curve diagram showing changes in magnetic permeability of the temperature-sensitive magnetic material in various temperature ranges and outside air temperature according to the present invention, and FIG. 3 is a diagram of the present invention. A curve diagram showing the relationship between the inductance value and outside temperature of the inductor according to the invention and the conventional inductor, FIG. 4 is a vertical cross-sectional view (a) and an external perspective view (b) of the conventional inductor, and FIG. 5 is the conventional inductor. FIG. 6 is a curve diagram showing the relationship between the inductance value and the outside temperature. FIG. 6 is a curve diagram showing the relationship between the magnetic permeability of the temperature-sensitive magnetic material and the outside temperature. Note that 2: magnetic core, 3: gap, 4: winding. Figure 1 Figure 2 (a) (1)) 4 Figure 4

Claims (1)

[Claims] 1. Outdoor temperature compensation characterized in that a plurality of types of temperature-sensitive magnetic materials having different low Curie temperatures are inserted into a part of the closed magnetic circuit of a magnetic core made of a magnetic material having a high Curie temperature and wound around the magnetic core. type inductor.