JPS62106335A - High voltage pressure sensor - Google Patents

Abstract

PURPOSE:To enhance the pressure resistance of a pressure sensor without deteriorating magnetic characteristics, by superposing a plurality of amorphous magnetic alloy discs one upon another constituting a diaphragm. CONSTITUTION:A plurality of amorphous magnetic alloy discs 2 having magnetostriction are laminated to constitute a diaphragm. When pressure is applied to the pressure introducing port 10 of a lid part 4, pressure is applied to amorphous magnetic alloy discs 2 through a through-hole 6 to downwardly push the same at the part of a soft magnetic groove 1a. As a result, stress is generated in the amorphous magnetic alloy discs 2 and the magnetic permeability of the amorphous magnetic alloy discs is reduced by magnetostriction effect due to he internal stress. This change is detected in an inductance form by a coil 8 to make it possible to measure oil pressure. By this constitution, the pressure resistance of the amorphous magnetic alloy discs constituting the diaphragm can be enhanced in the magnification corresponding to the number of superposed discs.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a pressure sensor using the magnetostrictive effect of an amorphous magnetic alloy.

BACKGROUND OF THE INVENTION In recent years, pressure sensors using the magnetostrictive effect of amorphous magnetic alloys have been proposed. For example, Japanese Patent Laid-Open No. 60-88336 discloses an embodiment as shown in FIG.

31 is a cylindrical soft magnetic body provided with an annular groove 31a, and 32 is an amorphous magnetic alloy disk having magnetostriction disposed on the soft magnetic body 31, which constitutes a diaphragm. 3
3 is a coil wound around the groove 31a of the soft magnetic material 31;
34 is a non-magnetic ring whose one end is in contact with the bottom of the groove of the soft magnetic material 31 and the other end is located on the same plane as the opening surface of the soft magnetic material; 35 is a container for storing these; and 36 is an amorphous magnetic alloy disk 32.
This is a lid portion having a through hole 37 for transmitting pressure to.

When hydraulic pressure is applied to the hydraulic pressure inlet 38 of the lid 36, the through hole 37
Pressure is applied to the amorphous magnetic alloy disc 32 through the amorphous magnetic alloy disc 32, pushing it down in the soft magnetic groove 31a, and stress is generated within the amorphous magnetic alloy disc 32.

Due to the generation of this internal stress, the magnetic permeability of the amorphous magnetic alloy disc 32 decreases due to the magnetostrictive effect. This change is detected in the form of inductance using a coil 33 to measure the oil pressure.

[Problems to be Solved by the Invention] The sensor having the above structure has a drawback that the withstand pressure cannot be increased because it has only one diaphragm made of an amorphous magnetic alloy disc. This drawback can be solved by increasing the thickness of the amorphous magnetic alloy disk, but at present, amorphous magnetic alloy disks can only be manufactured with a thickness of several tens of microns at most. The solution is not realistically possible.

Means for Solving the Problems In order to provide a pressure sensor with high pressure resistance, a plurality of amorphous magnetic alloy discs constituting a diaphragm are stacked together.

By stacking a plurality of operational amorphous magnetic alloy disks, the applied pressure is applied equally to each amorphous magnetic alloy disk. As a result, the stress generated in the amorphous magnetic alloy discs is reduced by the number of overlapping discs, and as a result, the withstand pressure of the pressure sensor can be increased. As a result, pressure sensors with different withstand pressures are configured, and if a signal of several tens of kHz is used to measure inductance, the penetration depth of the detection magnetic field can be set to the thickness of one amorphous magnetic alloy diaphragm. The same detection circuit can also be used regardless of the number of magnetic alloys.

Embodiment FIG. 1 is a sectional view of an embodiment of the present invention. Reference numeral 1 denotes a cylindrical soft magnetic body 2 provided with an annular groove 1a, which is an amorphous magnetic alloy disk having magnetostriction, and a plurality of disks are laminated to form a diaphragm. Soft magnetic material 1 and amorphous magnetic alloy disk 2
A non-magnetic disk (spacer) is placed between them, and this non-magnetic disk 3 has an elongated groove in a portion corresponding to the soft magnetic groove 1a. These three constitute one closed magnetic path. On top of the amorphous magnetic alloy disc 2, a lid part 4 is arranged, which has a through hole 6 for transmitting pressure and an O-ring 5 for preventing leakage of the pressure medium. It stores and holds the constituent members. 8 is soft magnetic groove 1
The coil installed inside a is used to measure the inductance of the magnetic circuit mentioned above. 9 is a detection circuit. When pressure is applied from the pressure introduction port 10 of the lid part 4, the pressure is applied to the amorphous magnetic alloy disk 3 through the through hole 6, and pushes the amorphous magnetic alloy disk 3 downward at the soft magnetic groove 1a. . This generates stress within the amorphous magnetic alloy disc 3, and this internal stress reduces the magnetic permeability of the amorphous magnetic alloy due to the magnetostrictive effect.

This change is detected in the form of inductance using a coil 8 to measure the oil pressure. As can be seen from the above detection principle, this sensor receives pressure through the diaphragm of an amorphous magnetic alloy disk, and therefore the withstand pressure is determined by the magnitude of the internal stress of the amorphous magnetic alloy disk generated by pressure. be done.

FIG. 2 shows a groove 1a of the soft magnetic material 1 in which stress is mainly generated in the amorphous magnetic alloy disc diaphragm in this embodiment.
It is an enlarged view of the part. As can be seen from this figure, pressure is applied equally to the three amorphous magnetic alloy discs 2 in this embodiment. In other words, the internal stress generated in the amorphous magnetic alloy disc 2 is reduced to - that in the case of one disc. This means that the withstand pressure of the pressure sensor of this embodiment is twice that of a single sheet.

Furthermore, in this embodiment, the non-magnetic disc 3 (spacer) was provided with an elongated groove in a portion corresponding to the soft magnetic groove.
Even in examples where the non-magnetic disk is not provided with grooves, the mechanical yield point of the non-magnetic disk is lower than that of an amorphous magnetic alloy, so once pressure is applied, the non-magnetic disk will undergo plastic deformation. This is equivalent if a substantially elongated groove is provided.

FIG. 4 is a graph plotting the failure pressure of the sensor configured as described above against the number of amorphous magnetic alloy diaphragms. It can be seen that the influence of friction between the amorphous magnetic alloy disks is small, and the pressure resistance increases in proportion to the number of disks.

FIG. 5 is a graph showing the change in the inductance value of the sensor with the above structure when the number of amorphous magnetic alloy discs is increased. The frequency of the measurement magnetic field is set to 20k.
It can be seen that in the case of Hz, the change in inductance is extremely small and it is possible to use the same detection circuit in practice.

Effects of the Invention According to the present invention, the withstand voltage of the amorphous magnetic alloy constituting the diaphragm can be increased without deteriorating the magnetic properties.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a high pressure sensor according to an embodiment of the present invention;
FIG. 2 is an enlarged cross-sectional view of the area around the soft magnetic groove in the embodiment shown in FIG. 1, FIG. 3 is a cross-sectional view of a conventional sensor, and FIG.
The figure is a graph showing the relationship between sensor breakdown voltage and the number of amorphous magnetic alloy diaphragms, and FIG. 5 is a graph showing the relationship between sensor inductance and the number of amorphous magnetic alloy diaphragms. 1 is a soft magnetic material, 2 is an amorphous magnetic alloy disk, 3 is a non-magnetic disk, 4 is a lid, 5 is an O ring, 6 is a through hole, 7 is a container, 8
9 is a coil, and 9 is a detection circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person Fig. 1 1O Five sword inlet Fig. 3 J6 Fig. 4 12.346 Isho buying money yen water roasting Fig. 5 2 δ 4 Yo 1 Ga alloy disc Kei, piece

Claims (2)

[Claims] (1) A cylindrical soft magnetic body provided with an annular groove, a non-magnetic disc in contact with a surface of the soft magnetic body having the groove, and a non-magnetic circular plate on a surface opposite to the soft magnetic body. A plurality of magnetostrictive amorphous magnetic alloy disks in contact with the plate, a coil wound around the soft magnetic groove, a container holding these, and a pressure transmission medium in contact with the amorphous magnetic alloy. A high-pressure pressure sensor comprising: a non-magnetic lid portion having a means for preventing outflow, and a non-magnetic lid portion having a means for transmitting pressure to the amorphous magnetic alloy disc corresponding to the soft magnetic groove portion. (2) The high-pressure pressure sensor according to claim 1, wherein the non-magnetic disc has an elongated groove in a portion corresponding to the soft magnetic groove.