JPS62200280A - Magnetic body detector - Google Patents

Abstract

PURPOSE:To obtain a simple, firm and stable detection performance for a long time, by a method wherein a DC magnetic field is always applied to a Matteuci effect element and an orbit of a magnetic body to be detected with a magnet and as the magnetic body being detected approaches the magnet, changes in the pulse voltage are detected with a detection circuit connected across an amorphous alloy wire to generate a signal. CONSTITUTION:As a magnetic body 10 to be detected approaches a permanent magnet 5 along an orbit passing through a DC magnetic field thereof 5, a magnetic field generated from the permanent magnet 5 is attracted to the magnetic body 10 with a higher relative permeability to reduce the amount of the DC magnetic flux passing through an amorphous alloy wire 2, causing a change in the hysteresis curve and based on the change, the peak value of an output pulse voltage generated by the Mathieu..s effect increase. Therefore, when the output pulse voltage exceeding the output pulse voltage as threshould is detected with a detection circuit conductively connected across the amorphous alloy wire 2, the detection signal is outputted. Thus enables the detection of an access of the magnetic body 10 being detected.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention is a moving product counting, proximity switch.

The present invention relates to a magnetic body detection device that utilizes magnetic sensitivity with a magnetic body to be detected, which is used in a non-contact distance control device or the like.

[Traditional technology and its problems]

As a magnetic substance detection device using magnetic sensitivity, a Hall element is used when the magnetic substance to be detected generates a magnetic field, and a high-frequency induction device is used when the magnetic substance to be detected does not generate a magnetic field. Magnetic substance detection devices of the following type have been widely used in the past. However, the Hall element is expensive, and its characteristics change due to the influence of ambient temperature, so there are problems in that the structure becomes complicated, such as requiring a temperature correction circuit. In addition, in the high-frequency induction type detection device, the magnetic flux emitted from the ferrite core interlinks with the magnetic material to be detected, generating eddy current in the magnetic material to be detected, and when the current stops, the magnetic material to be detected is detected. However, there are drawbacks such as a complicated circuit configuration and high processing costs for the ferrite core.

[Purpose of the invention]

The present invention was made in view of the above-mentioned situation, and an object of the present invention is to provide a magnetic body detection device that has a simple configuration, is not easily affected by ambient temperature, and is capable of stably detecting the approach of a magnetic body to be detected over a long period of time. shall be.

[Key points of the invention]

Fe-based amorphous alloy wire, which is manufactured by ultra-quenching molten metal using spinning in a rotating liquid, has high magnetostriction and strong elasticity that retains the torsional residual stress that occurs in the surface layer during solidification. In an alternating magnetic field, magnetization reversal occurs due to domain wall movement due to some torsional residual stress in an alternating current magnetic field, and the hysteresis loop exhibits a rectangular shape. A phenomenon known as the so-called "dead effect" in which a pulse voltage is generated between both ends of the line occurs significantly. .

The present invention was made by paying attention to the magnetic effect of an amorphous alloy wire, and uses a magnetic effect element made by winding an AC excitation coil around the outer circumferential surface of an amorphous alloy wire having high magnetostriction. , a magnet that constantly applies a direct current magnetic field to the trajectory of the Machiushi effect element and the magnetic substance to be detected, and a non-magnetic base that fixes the distance between the magnet and the Machiushi effect element, and the magnetic substance to be detected is the magnet. When the magnetic object to be detected is not close to the magnet, the DC magnetic field passing through the amorphous alloy wire suppresses the pulse voltage generated in the alloy wire due to the magnetic field effect. The DC magnetic flux that is attracted by the magnetic material and passes through the amorphous alloy wire is reduced, and the peak value of the output pulse voltage is increased.
By using a detection circuit conductively connected to both ends of the amorphous alloy wire to detect changes in the pulse voltage and emit a signal, a simple detection device can detect changes in the magnetic field due to the proximity of the magnetic substance to be detected. This converts the signal into an electrical signal, making it possible to detect it stably and reliably.

[Embodiments of the invention]

The present invention will be explained below based on examples.

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

In the figure, 1 is a Machiushi effect element, which has a length of several tens of meters.
Fe-based amorphous alloy wire 2 (diameter 0, 12 m, Fe775i8B15) having high magnetostriction and cut to a certain degree;
It consists of an AC excitation coil 3 wound around its outer circumferential surface and excited by an oscillator 4, and is fixed on a non-magnetic base 6. Reference numeral 5 denotes a thin bar-shaped permanent magnet, which is fixed on a base 6 in parallel with the Machiushi effect element 1 at a distance of several meters, thereby absorbing a considerable amount of the DC magnetic flux generated by the permanent magnet 5. The parts are magnetically coupled through an amorphous alloy wire 2 having high magnetic permeability. 7 is amorphous alloy wire 2
This is a detection circuit that is conductively connected to both ends of the detection circuit, and when the output pulse voltage generated in the amorphous alloy wire 2 due to the magnetic field effect exceeds a predetermined threshold, it emits a detection signal for the magnetic substance to be detected. configured. Further, 10 is a magnetic body to be detected, which moves in the direction shown by the arrow in the figure along a trajectory 15 passing within the DC magnetic field of the permanent magnet 5, and at a position closest to the permanent magnet '; F55. The distance is about several kilometers.

FIG. 2 is a magnetization characteristic diagram of the Machiushi effect element alone in the example. Since magnetization reversal of the amorphous alloy wire 2 excited by AC occurs rapidly due to domain wall movement, the systeresis loop becomes rectangular, and instantaneous Along with the magnetization reversal, a pulse voltage based on the Machinshi effect is generated.

Figures 3 and 84 are magnetization characteristic hysteresis diagrams in a state where direct current magnetic fields in opposite directions are applied to the Machiushi effect element, and when the direct current magnetic field is applied, the systeresis loop is caused by the magnetizing force H on the right or right side of the figure. The amorphous alloy wire 2 is moved to a higher region, and the axial magnetization due to the DC magnetic field becomes dominant inside the amorphous alloy wire 2, and the stiffness effect due to torsional residual stress in the surface layer portion of the amorphous alloy wire 2 is reduced.

FIG. 5 is a waveform diagram of the alternating magnetic field and generated pulse voltage of the Machiushi effect element, where waveform 11 is the alternating magnetic field, waveform 12
Waveform 3 shows the output pulse voltage waveform under the same conditions as in Figure 2, and waveform 14 shows the output pulse pressure waveform under the same conditions as in Figure 4. It is something. First, waveform 11
Machiushi effect element 1 generating an alternating magnetic field shown by
The output pulse voltage generated at both ends of a single amorphous alloy wire 2 is generated instantaneously due to magnetization reversal of the amorphous alloy wire 2 or domain wall movement in a region where the magnetizing force H is low as shown in Fig. 2. The pulse voltage that appears at both ends of the amorphous alloy wire due to the Machinshi effect is generated in synchronization with the vicinity of the zero phase of the alternating current magnetic field as shown in waveform 12; the amount of change in the magnetic flux of the alternating current magnetic field 11 near the zero phase is Since (dφ/d t ) is large, it becomes a large pulse with a waveform value of V1. Next, permanent magnet 5. When the DC magnetic field generated by is superimposed on the amorphous alloy wire 2, and the hysteresis loose is moved to the region where the magnetizing force H is high as shown in Figs. 3 and 4, due to the DC bias magnetic field,
Since magnetization reversal occurs near the peak value of either the positive or negative half wave of the AC magnetic field shown in waveform 11, the output pulse voltage is the positive half wave of the AC magnetic field in waveform 13, and the negative half wave in waveform 14. Two pulses are output with the wave peak value phase of the AC magnetic field in between, and the amount of change in magnetic flux (dφ/d t ) near the peak value of the AC magnetic field becomes small, resulting in an output based on the Machining effect. The peak value v2 of the pulse voltage is lower than the peak value V of the output pulse voltage of the Machiushi effect element alone. Since the present invention detects the magnetic body 1o to be detected using the difference between the output pulse voltages V and 2, the voltage V Consider making the ratio between , and ■ as large as possible.

Assume that the magnetic body 1-0 to be detected approaches the permanent magnet of the detection device configured as described above along the trajectory 15 passing within the DC magnetic field of the permanent magnet 5.

The magnetic field generated by the permanent magnet 5 is attracted to the detected magnetic body 10 having a high relative magnetic permeability, and the amount of DC magnetic flux passing through the amorphous alloy wire 2 decreases, so the hysteresis curve returns to the state shown in FIG. 2. Based on this, the peak value v2 of the output pulse voltage increases toward {circle over (1)}1. Therefore, the detection circuit conductively connected to both ends of the amorphous alloy wire 2 is configured to output a detection signal when an output pulse voltage exceeding V is detected with the output pulse voltage V being a threshold value. Accordingly, the proximity of the magnetic body 10 to be detected can be detected. Note that the magnetic body 10 to be detected must not be magnetized to the extent that it cannot attract the magnetic field generated by the permanent magnet 5. In addition, Fe-based amorphous alloy wire is not affected by the static effect up to an ambient temperature of about 150°C, so there is no need for a compensation circuit for changes in ambient temperature, which simplifies the configuration of the device and reduces the risk of deterioration over time. Since it is difficult to cause this, stable magnetic substance detection performance can be maintained for a long period of time. Therefore, by counting the output detection signal of the detection circuit 7, a product counting device in a production line can be configured, and by opening and closing the electrical contacts based on the output detection signal, a proximity switch can be configured, and the magnetic material to be detected can be A non-contact distance sensor can be configured by calibrating the relationship between the distance to the detection device and the peak value of the pulse voltage in advance.

In addition, in the above-mentioned embodiment, an example was shown in which a permanent magnet was used as the magnet 5, but the same function as in the embodiment can be obtained by using, for example, a rod-shaped DC electromagnet. Also, the base 6
is made into a synthetic resin cured product, and Machiushi effect cord 1
．． By embedding the main components such as the magnet 5 in the base 6, the detection device can have mechanical stability and ease of handling.

〔Effect of the invention〕

As a result of the above-described configuration of the present invention, a large output pulse voltage can be obtained because the amorphous alloy wire has high magnetostriction and strong elasticity, and the amorphous alloy wire and the magnetic body to be detected are magnetized. It is possible to change the output pulse voltage according to the proximity of the magnetic object to be detected by the direct current magnetic field generated by the magnets coupled to the Approach can be easily detected using a principle different from conventional technology, and the output pulse voltage of the amorphous alloy wire is
It is not affected by temperatures up to around 30 degrees Fahrenheit and therefore does not require a temperature compensation circuit, making the device structure simple and robust.
It is possible to economically advantageously provide a magnetic substance detection device that is simple, strong, and provides long-term stable detection performance. Furthermore, depending on how the output signal of the detection circuit is processed, it has the advantage that it can be applied to various fields such as counting of magnetic substances to be detected, proximity switches, and non-contact distance sensors.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of an apparatus according to an embodiment of the present invention, Fig. 2 is a magnetization characteristic diagram of the Machiushi effect element alone in the embodiment, and Figs. 3 and 4 are the Machiushi effect element in a state where a DC magnetic field is applied. FIG. 5 is a waveform diagram of the alternating current magnetic field and output pulse voltage of the Machiushi effect element. 1...Machiushi effect element, 2...Amorphous alloy wire, 3
...AC excitation coil, 5...Magnet (permanent magnet), 6
...1 stone and 2 stones, 1st ward

Claims (1)

[Claims] 1) A Machiushi effect element formed by winding an AC excitation coil around an amorphous alloy wire having high magnetostriction, and a DC magnetic field constantly applied to the orbit of the Machiushi effect element and the magnetic substance to be detected. a non-magnetic base that fixes the distance between the magnet and the Machiushi effect element; and a non-magnetic base that is conductively connected to both ends of the amorphous alloy wire to detect the output pulse voltage of the Machiushi effect element and generate a signal. A magnetic substance detection device characterized by comprising a detection circuit that emits light. 2) A magnetic body detection device according to claim 1 or 2, characterized in that the magnet is a permanent magnet. 3) A magnetic substance detection device according to claim 1, wherein the magnet is an electromagnet having a DC excitation coil wound around an iron core. 4) A magnetic substance detection device according to claim 1, wherein the base is made of a cured synthetic resin, and the Machiushi effect element and the magnet are embedded in the base.