JPS6154128A - Current sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a current sensor that uses the fact that the magnetic permeability of a highly magnetically permeable material changes significantly before and after the temperature transformation point, the so-called Curie transformation point.

Normally, the transformation point of this type of magnetic material is as high as several hundred degrees, but for example, it is called magnetic shunt steel.

It is known that the Curi transformation point of a magnetic material having an alloy composition such as Cr-added iron or iron/nickel/chromium can be lowered to near room temperature. The above 62 external body is always 11□1
1 has high permeability, but it becomes J-type at temperatures higher than the transformation temperature.

The present invention proposes a novel current sensor that uses the above-mentioned magnetic material having a relatively low transformation point temperature.

[Conventional technology]

As a conventional current sensor, there is a bimetallic switch shown in the 9th cross-sectional view, which is made by bonding metals with different coefficients of thermal expansion, and its structure is as follows.

In the figure, 31 is a bimetal made by bonding dissimilar metals.

32 is a metal plate facing the bimetal 31, and 33 is a facing contact formed at each end of the bimetal and the metal plate.

and 34 are glass tubes that seal the opposing contact 33 and the bimetal and metal plate, and the lower part of the cough tube serves as a switch terminal.

Although the switch contact part 33 is normally closed, the opposite contact part 33
When the current between them reaches a certain value, the bimetal is bent as shown by the dotted line due to the Joule heat of the current, and the contact of the switch is opened.

This is used, for example, to interrupt excessive current. However.

The open switch contact closes after a certain period of time.

Furthermore, the switch i'i? In addition to current interruption based on the thermal current of the current described in 7, it may also be used as a general temperature switch.

[Problem that the invention seeks to solve]

For example, since the bimetallic switch described above is equipped with a mechanical opening/closing contact section, the contact bounce during opening/closing is severe, and this wears out the contacts, resulting in a short lifespan. There are problems such as a large temperature difference at the point in time.

[Means for solving problems]

The above problem is.

To provide a current sensor according to the present invention, which uses the Joule heat of a metal magnetic material through which a current flows to reach the transformation point temperature of the magnetic material, and senses a specific level of the current value flowing through the magnetic material from devitrification of permeability. This is achieved by

Furthermore, a magnetic flux detection coil is wound around the magnetic body to extract the sensor output.

[For production]

The current sensor of the present invention uses a ring-shaped or rod-shaped magnetic material having a low Curie transformation point temperature as a sensor base, and inserts the mI base into a circuit to be detected by the sensor to generate a J electric current. Conversely, the current level is sensed from the temperature of the magnetic body, which is proportional to Joule heat loss.

In this case, the two-magnetic body is provided with one or more magnetic flux detection coils to check the magnetic permeability, thereby detecting the presence or absence of sex in m45. A specific level of current is detected depending on whether the output voltage level of the detection coil is high or extremely low.

〔Example〕

An example of the configuration of a current sensor according to the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 is a perspective view of a current sensor having a single coil configuration.

Figure 2 is a perspective view of a sensor with a multiple coil configuration, Figure 3 is an operating waveform diagram of a current sensor, and Figure 4 is a metal with a low Curie transformation point of iron (Fe), nickel (Ni), and chromium (Cr) composition. It is also a relational characteristic diagram showing external body composition.

The basic configuration of the sensor will be explained with reference to FIG.

In the figure, 1 is a metal body whose surface is insulated and transforms alternating current (1) into Joule heat loss 12R, and 2 is a rod-shaped magnetic body having the above-mentioned transformation point.

3 is a magnetic flux detection coil wound around a magnetic material.

The metal body 1 and the magnetic body 2 are arranged in an orthogonal position to achieve a close magnetic coupling, and are in contact with each other.

When an alternating current is applied to the metal body 1 arranged in this manner, the magnetic flux force W of the current (2) is induced in the magnetic body 2, so that a sensor output as shown in FIG. 3 is obtained at the detection coil 3. However, when the temperature of the metal body rises and exceeds a certain temperature in response to the loss of 1 or 14 due to the Joule heat of the current I flowing through the metal body, the magnetic body 2 in contact with the metal body becomes non-active when it reaches the magnetic transformation point temperature. As a result of becoming magnetic, the coil output (alternating current) becomes an extremely low output level.

Changes in the output of the coil 3 can be determined by adding 1 to the sensor (not shown).
．． It can be detected with a level detector based on '71.

Figure 2 shows the current (alternating current)
FIG. 2 is a perspective view of an embodiment of the current sensor of the present invention that flows through the I-type body 5;

Since the current 1 flows from one end of the magnetic body end 9 or 10 of the forming gap 8 of the annular magnetic body 5 to the other end, a metal body disposed in contact between the curves is unnecessary.

In the figure, 6 and 7 are both coils made of magnetic material, coil 6 is an input side coil, and coil 7 is a coil for detecting magnetic flux (corresponding to the inter-track coil 3).

The sensor operation in FIG. 2 will be explained with reference to the waveforms in FIG. 3.

AC voltage A is always input to the input side coil 6. Accordingly, the magnetic flux detection coil 7, which is magnetically coupled via the annular magnetic body 5, takes out an inverted pulse output as shown in voltage waveform B in FIG. However, when the Joule heat loss increases with the increase in the current and the temperature of the magnetic body increases and reaches the transformation point temperature, the pulse output voltage B suddenly decreases to a low level voltage as shown in waveform C in the figure. As in FIG. 1, this is detected by a level detector (not shown). In this case, the current (2) may be a direct current.

FIG. 4 shows characteristic data for selecting a desired Curie transformation point temperature from a metal magnetic material having a Fe--Ni--Cr alloy composition.

Electric l, I! The composition of the magnetic material 3 or 5 used for J-Centralization is effective: Cr: 5-15%, Ni: 30-45%, and the balance is Fe, and the magnetic transformation point temperature is 300° C. or less.

5 and 6 are perspective views of other embodiments of the current sensor of the present invention.

As is clear from comparing FIG. 5 with FIG. 1, the magnetic body 11 formed in a U-shape with the metal body l of Joule heat conversion perpendicular to each other and the three windings of the detection coil is dependent on the temperature of the metal body. Since it has a configuration that can more effectively detect surrounding magnetic flux, it has a sensor configuration that improves the detection sensitivity of the coil output level.

FIG. 6 shows a modification of the sensor shown in FIG. 5. The current is generated by passing an AC current to be detected through the tH magnetic body 2 formed into the shape shown in the figure, and detecting the transformation point temperature of the magnetic body 12 corresponding to the heat loss within the magnetic body using the output level of the detection coil. It is a sensor.

The current sensor of the present invention illustrated in FIGS. 1 to 6 is as follows:
Using the Gffi transformation point of a magnetic substance, a magnetic substance 2°5,
And by the magnetic flux detection coils wound around 11 and 12,
Stones go crazy due to Joule heat based on electric current! The feature is that devitrification of the SIt nature at a temperature near the imaginary point is detected by a change in the sensor output level as shown in FIG.

Next, another embodiment of the present invention will be described with reference to sensor perspective views shown in FIGS. 7 and 8.

In FIGS. 7 and 8, 20 is a U-shaped magnetic body made of a soft ferromagnetic material with a built-in magnet, 21 is the aforementioned magnet, 22 is a rod-shaped magnetic body with a low Kuyuri point,
Reference numeral 23 denotes an opening/closing contact portion formed at mutually opposing ends of the soft ferromagnetic material 20 and the rod-shaped magnetic material 22, and 25 is an insulating layer that connects the magnetic materials.

External connection terminals 26 and 27 of the sensor as shown in FIG. 7 are provided at the ends of the mutual magnetic bodies 20 and 22 with an insulator N25 interposed therebetween. The annular magnetic circuit passing through the contact section 23 provided with the terminal sections 26 and 27 forms a sensor current path to be detected having the same shape as that shown in FIG. Contact point 2 for suctioning the body 22
Close 3. However, if the temperature on the magnetic body 22 side, which is proportional to the Joule heat loss caused by the current flowing from one of the terminals 26 and 27 to the other, reaches the low Curie transformation point, the magnetic permeability will be lost and the contact portion 23 will open. become.

However, 1. In the structure of the 6-silicon circuit, 1. rod-shaped stone) 1.
2 is made of a soft ferromagnetic material, and the U-shaped magnetic material side with a built-in magnet is made of a magnetic material having a low Curie transformation point, but the operation of the element remains unchanged.

FIG. 8 is a perspective view of another embodiment of the current sensor of the present invention, and the main differences from the embodiment of FIG. 7 and different device application examples will be described below.

In FIG. 8, a U-shaped soft ferromagnetic material 20 and a magneto magnetic material 1-21 are provided, and a magnetic material formed in a U-shaped shape made of a soft ferromagnetic material is also provided behind the rod-shaped (fi-type outer body 2). 2
8 are connected via the contact portion 24, and the same insulating layer 25 as described above is inserted at the end connected to the rod-shaped Lil body 22. Although not shown in detail at the end, the circuit of the element 0:1.1
A child 29 is provided. Furthermore, in Figure 1, 30 is a rod-shaped magnetic body 2.
A thin film of Mr. 1 antibody was attached to one side of 2.

Figure 4.1. In the i-formation, Fe-Ni-Cr (il
When the ambient temperature is lower than the transformation point of the alloy, one rod-like Li
The magnetic body 22 is attracted to the magnetic body 21 side of the built-in magnet 71 and the contact portion 23 operates, so that the circuit terminals 26 and 27 are turned on.

Next, when a voltage (Vin) is applied to the heat-generating thin film resistor 30, the temperature of the rod-shaped magnetic body 22 increases due to Joule heat, the magnetic force of the magnet decreases, and the elastic restoring force of the magnetic body 22 causes the contact portion 23 to Since the circuit terminals 27 and 29 are opened and the contact portion 24 side is closed, the circuit terminals 27 and 29 are in the ON state. When the Vin voltage is cut off, the temperature of the rod-shaped magnetic body 22 decreases, so that the terminals 26 and 27 are turned on again, and the other circuit terminals 27 and 29 are turned off.

As the soft ferromagnetic material cited in the description of the above embodiments, for example, permalloy alloy (Fe--Ni alloy) or the like may be used.

The current sensor shown in FIG. 7 can be used, for example, as a safety relay for a circuit in which the element is inserted, and as a circuit interrupter IJfr25 when a large current flows.

Furthermore, FIG. 8 can be applied to control elements of various circuits, such as the aforementioned circuit breaker in which a thin film resistor is regarded as a heat-sensitive element, or a coilless relay that utilizes changes in magnetic flux density with respect to temperature.

〔Effect of the invention〕

(According to the current sensor of the present invention, which uses a metal magnetic alloy having a transformation point of -1 -
Simple element configuration reduces circuit current or Joule heat tJ!
'! Since it is possible to detect 'l aA temperature, its industrial effects are great.

[Brief explanation of the drawing]

1 and 2 are perspective views of an embodiment of the current sensor of the present invention. FIG. 3 is an output pulse waveform diagram of the current sensor shown in FIG. 2. FIG. 4 is a relationship characteristic diagram showing the composition of the magnetic material at the low Curie transformation point. 5 and 6 are perspective views of other current sensor embodiments. 7 and 8 are perspective views of another current sensor embodiment of the present invention. FIG. 9 is a sectional view showing an example of a conventional current sensor. In the figure, 1 is a metal body, 2. IL25 is Fc-Ni-Cr1
(K outer body. 3 and 6 are coils for detecting 6 bundles. 5 is a ring-shaped magnetic body, 7 is an input coil. 21 is a magnet 22 is a rod-shaped magnetic body. 23 and 24 are contact parts, 20 and 28 are soft and strong Magnetic material. 30 is a thin film resistor.

Claims (6)

[Claims] (1) A current characterized in that the Joule heat loss of the metal magnetic material through which the current flows reaches the transformation point temperature of the magnetic material, and a specific level of the current value flowing through the magnetic material is sensed from the devitrification of the permeability. sensor. (2) The current sensor according to claim 1, characterized in that a magnetic flux detection coil is wound around the magnetic body. (3) Claim 1, wherein the magnetic material is a magnetic material having a Fe-Ni-Cr composition with a low Curie point.
Current sensor described in section. (4) The current sensor as set forth in claim 1, wherein the Joule heat is generated by a metal body that is placed in close contact with the magnetic body. (5) The current sensor according to claim 1, wherein a soft ferromagnetic material with a built-in magnet and the magnetic material are coupled via a contact portion to form a relay. (6) The current sensor according to claim 1, wherein a thin film resistor is provided on one side of the magnetic body, and the magnetic body senses Joule heat of the thin film resistor.