JPH0533339B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a mechanical quantity-inductance conversion type sensor detection method using an amorphous magnetic alloy.

Conventional configurations and their problems Conventionally, sensors have been proposed that detect various forces, strains, etc. using the magnetostrictive effect of amorphous magnetic alloys.
Problems remained in sensitivity, reproducibility, and stability. The detection method uses a single alternating current magnetic field to detect inductance, and is not effective as a detection method for a magnetic circuit that has at least a portion of an amorphous magnetic alloy.

OBJECTS OF THE INVENTION The present invention provides a sensor detection method that solves the problems in amorphous magnetic alloy applied sensors that still have problems in sensitivity, reproducibility, and stability as described above.

Structure of the Invention In order to solve the above-mentioned problem, the present invention uses at least two types of magnetic field waveforms when detecting the inductance value of a sensor, tends to align the magnetic domain structure of an amorphous magnetic alloy, and at the same time aligns the magnetic domain structure of an amorphous magnetic alloy. Detection is performed by reducing the influence of radio waves (hereinafter abbreviated as D and A).

DESCRIPTION OF EMBODIMENTS FIG. 1 shows an example of a pressure sensor using an amorphous magnetic alloy. 1 is an amorphous magnetic alloy having magnetostriction, and 2 is a soft magnetic ferrite, and these two constitute a magnetic circuit. 3 is a coil that excites this magnetic circuit, and the whole is housed in a case 4. Pressure is applied to the amorphous magnetic alloy 1 from the introduction part 5 through the through hole 6. When strain occurs in the amorphous magnetic alloy due to the application of pressure, the magnetism of the amorphous magnetic alloy changes due to the magnetostrictive effect, which is detected by the inductance measuring circuit 7, and the pressure is detected in the form of an inductance value.

However, when a normal single AC magnetic field as shown in FIG. 2 is used, the output of the hydraulic pressure-inductance value change is small, the reproducibility is poor, hysteresis occurs, and the stability due to D and A is poor.

FIG. 3 shows an output example of pressure-inductance value changes when measured only with an alternating magnetic field as shown in FIG. 2. Arrows indicate the order of measurements.

Figure 4 shows that the inductance value when a DC magnetic field is superimposed on the oil pressure sensor shown in Figure 1 is the DC magnetic field.
This figure shows how it changes depending on the size of Hdc at 0 and 30 atmospheres. The measurement temperature is 50 degrees and the frequency is 20kHz. From this it can be seen that the output is small when measured only with an alternating magnetic field, and it can be seen that the normal measurement method is inappropriate. It can be seen that the output increases by superimposing a DC magnetic field.

FIG. 5 shows the inductance value detection magnetic field of the detection method according to the present invention. A high-frequency alternating current is superimposed on a low-frequency rectangular wave. This method improves the output as shown in FIG. Furthermore, since there is no direct current magnetic field in this method, it is equivalent to constantly performing alternating current demagnetization, and changes over time can also be suppressed.

FIG. 6 shows another detection magnetic field of the detection method according to the invention. The rising portion of the low frequency rectangular wave is made into a large amplitude H _nax and then converged to a constant value Hs. Measurement of the inductance value is performed at this post-convergence portion. In such a measurement waveform, as shown in Figure 7, the measurement point moves all at once to the high magnetic field side of the B-H loop of the amorphous magnetic alloy, and as a result, the magnetic domain structure is oriented, and then measurement begins. Therefore, it is magnetically stable. As a result, D, A, and other instabilities can be removed, and the output is improved as in the above example.

Effects of the Invention As described above, if the detection method according to the present invention is used, it is possible to increase the output in a mechanical quantity-inductance conversion type sensor using magnetostriction of an amorphous magnetic alloy, and improve reproducibility and stability. , a sensor with little change over time can be realized, and the effect is extremely large.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a pressure sensor using an amorphous magnetic alloy, Figure 2 is a conventional detection magnetic field waveform diagram, Figure 3 is a characteristic diagram showing the measurement results of the conventional detection method, and Figure 4 is 0. A diagram showing the dependence of the inductance value of the pressure sensor on DC magnetic field superimposition when an atmospheric pressure of 30 atm is applied. Figures 5 and 6 are detection magnetic field waveform diagrams of the present invention. Figure 7 is the B of the amorphous magnetic alloy. - It is a figure which shows H loop. DESCRIPTION OF SYMBOLS 1...Amorphous magnetic alloy, 2...Soft magnetic ferrite, 3...Coil, 4...Case, 5...Introduction part, 6...Through hole.

Claims (1)

[Scope of Claims] 1. When detecting the inductance value of a magnetic circuit at least partially composed of an amorphous magnetic alloy having magnetostriction and in which strain is generated in the amorphous magnetic alloy by an object to be detected, A sensor detection method characterized in that a high-frequency alternating current magnetic field superimposed on a low-frequency rectangular wave is used as the magnetic field, and the amplitude of the rectangular wave is made to change greatly due to distortion of an inductance value. 2 Instead of the detection magnetic field described in the previous section, a high-frequency alternating current magnetic field is used that is superimposed on a low-frequency rectangular wave that starts with a large amplitude and is then trained to a constant value, and the rectangular wave is trained to a constant value with distortion of the inductance value. A sensor detection method characterized in that the inductance value measurement is performed when the rectangular wave has trained to a constant value.