JPS6246225A - High pressure hydraulic sensor - Google Patents

Abstract

PURPOSE:To stabilize output and to enable measurement up to high oil pressure, by using an amorphous alloy having magnetostriction and a non-magnetic amorphous alloy in a superposed state as a pressure receiving diaphragm. CONSTITUTION:Oil pressure is applied to a diaphragm layer comprising an amorphous alloy from an oil pressure introducing port 8 through a through-hole 9 and strain is generated in the alloy. The magnetic permeability of an amorphous alloy disc 1 having magnetostriction changes by the generation of strain and the inductance value measured by an inductance detection circuit 10 changes and oil pressure is detected in an inductance form. Because oil pressure is received by the disc 1 and a non-magnetic amorphous alloy disc 3, the generated strain is lowered to 1/several numbers as compared with such a case that oil pressure is received only by the disc 1 and strain is reduced and, therefore, destruction pressure also increases. That is, measurable oil pressure increases by several times by superposing the disc 3. Further, because the disc 3 is arranged between the disc 1 and soft magnetic ferrite 2, said disc 3 also has function as the spacer of a magnetic circuit and the magnetic circuit is stabilized and output irregularity is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a hydraulic sensor that utilizes the magnetostrictive effect of an amorphous magnetic alloy, and particularly relates to a hydraulic sensor suitable for detecting high-pressure hydraulic pressure.

Conventional technology An example of a hydraulic sensor using the magnetostrictive effect of an amorphous magnetic alloy is
For example, it is shown in Japanese Patent Application Laid-Open No. 59-111033. This technology uses an amorphous alloy diaphragm directly as a magnetic circuit, and is configured to detect strain caused by hydraulic pressure as a change in inductance. And, the amorphous alloy has extremely strong mechanical properties (tensile strength of 3
There are some that reach ooKy/mm or more. ), ■ A chemically homogeneous protective film is easily formed and has high corrosion resistance, ■ Iron-based materials have a large magnetostrictive effect. It makes clever use of such characteristics.

Problems to be Solved by the Invention In the conventional technology such as the above-mentioned oil pressure sensor, since a single plate of an amorphous alloy having magnetostriction 2 is used as the pressure receiving diaphragm, there is a drawback that it cannot withstand high pressure oil pressure. Therefore, a method of stacking amorphous alloys of the same composition can be considered. However, although this method does not interfere with the utilization of the magnetostrictive effect, it has the drawback that the configuration of the magnetic circuit changes, and therefore the configuration of the detection circuit must be changed. Furthermore, in order to improve the sensitivity and temperature characteristics of the hydraulic sensor as mentioned above, a patent application was filed in 1973.
As shown in No. 9-118508, it is necessary to superimpose a DC magnetic field on the detection AC magnetic field of all transducer sections, and when multiple amorphous alloys with the same composition and magnetism are stacked, the DC magnetic field cannot be optimized. In order to increase the size of the coil, it becomes necessary to pass a large amount of direct current through the coil. This DC magnetic field consumes extra current that is not used for direct detection by the oil pressure sensor, and from this point of view as well, it is not appropriate to stack amorphous alloys of the same composition.

The only way to solve all of the problems is to create a pressure-receiving diaphragm using a plurality of amorphous plates made by stacking magnetostrictive amorphous alloys and non-magnetic amorphous alloys, and combine this with a soft magnetic material to create an entire magnetic circuit. Configure. In this case, the amorphous alloy that does not have magnetism is placed on the soft magnetic material side, and the amorphous alloy that has magnetostriction is placed on the pressure receiving side.

As the thickness of the pressure-receiving diaphragm increases, the amount of distortion of the diaphragm due to hydraulic pressure decreases, making it possible to measure high pressures over a wide range. Furthermore, since the non-magnetic amorphous alloy is placed between the soft magnetic material and the magnetostrictive amorphous alloy, the stability of the magnetic circuit is increased. 1) In order to improve the sensitivity and temperature characteristics of the oil pressure sensor, it is necessary to superimpose a DC magnetic field on the detection AC of the transducer, but the non-magnetic amorphous alloy added to the pressure receiving diaphragm can absorb this DC magnetic field. Since the magnetostrictive amorphous alloy plate has no relation to , the thickness of the magnetostrictive amorphous alloy plate is sufficient to be sufficient for sensitivity, and as a result, there is no need for an extra DC current to be passed through the coil.

Embodiment FIG. 1 is a sectional view of a transducer portion of a hydraulic sensor according to the present invention. 1 is an amorphous alloy disk having magnetostriction, 2
is a soft magnetic ferrite, and these two constitute a magnetic circuit. 3 is a non-magnetic amorphous alloy disk, which is overlapped with the magnetostrictive amorphous alloy disk 1 to form a pressure-receiving diaphragm. 4 is a coil provided in the cylindrical groove of the soft magnetic ferrite 2. These are housed in a cylindrical container 5 with a lid 6.
is fixed from above. Reference numeral 7 denotes a Q valve for sealing off the pressure medium oil that enters from the hydraulic pressure inlet 8 through the through hole 9. Reference numeral 10 denotes a circuit section that uses the coil 4 to measure the inductance of the transducer section, which changes depending on the oil pressure.

Hydraulic pressure is applied to the diaphragm layer of the amorphous alloy from the inlet 8 through the through hole 9, and strain is generated in the amorphous alloy as the hydraulic pressure is applied. Is this magnetostriction? The magnetic permeability of the amorphous alloy disk 1 changes, and the inductance value measured by the inductance detection circuit 10 changes. That is, oil pressure is detected in the form of inductance.

Since the applied hydraulic pressure is received by the amorphous alloy discs 1 and 3, the strain that occurs is reduced to a fraction of that when the pressure is received only by the amorphous alloy disc 1. Furthermore, since the strain is reduced, the bursting pressure is also increased. That is, by stacking the amorphous alloy plates 2, the measurable oil pressure increases several times. In this case, if the amorphous alloy plate 3 is crystalline, the elastic limit is low and it is difficult to obtain the same effect due to the loose deformation.

Furthermore, since the non-magnetic amorphous alloy plate 3 is placed between the magnetostrictive amorphous alloy 1 and the soft magnetic ferrite, it also functions as a spacer for the magnetic circuit. This stabilizes the magnetic circuit and reduces variations in output.

Also, is the amorphous alloy disk 3 magnetic? Since it does not have a magnetic circuit, it can be considered as a metal spacer. As a result, the magnetic circuit becomes simpler and the design becomes easier than when S amorphous alloys having the same composition and magnetostriction are stacked. In addition, in order to improve the sensitivity and temperature characteristics of the oil pressure sensor, a DC magnetic field is superimposed on the AC magnetic field for detecting all transducers, but since there is no unnecessary amorphous magnetic alloy with the same composition in this DC magnetic field current, , that extra current is no longer necessary, and unnecessary current consumption can be suppressed.

FIG. 2 shows another embodiment of the invention. The configuration is almost the same as in Figure 1, and the same parts are given common numbers. What is different is the non-magnetic amorphous alloy disk 11, in which band-shaped through holes 12 are provided in the part corresponding to the grooves of the soft magnetic ferrite 2 on the soft magnetic side of the two amorphous alloy disks. ing.

The hydraulic sensor configured in this manner not only has the above-mentioned features, but also allows easy design of the deformation part of the magnetostrictive amorphous alloy due to hydraulic pressure due to the shape of the through hole 12, and the hydraulic range can be freely adjusted even within a high pressure range. It also has features that allow it to be designed. Naturally, the same effect can be obtained even if this through hole is provided only in the non-magnetic amorphous alloy that is in contact with the amorphous alloy 1 that has magnetostriction. By using an alloy and a non-magnetic amorphous alloy in layers, the following effects can be obtained.

(1) It is possible to measure up to high oil pressure.

(2) The magnetic circuit can be stabilized, resulting in stable output.

(3) There is no need to increase the DC magnetic redundancy to improve characteristics.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a high-pressure oil pressure sensor according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the flow side of the present invention. 1... Amorphous alloy disc with magnetostriction, 2...
Soft magnetic ferrite, 3...Nonmagnetic amorphous alloy, 4.
・Koinobe 5... Container, 6... Lid, 7
・Q IJ ring, 8...Hydraulic pressure inlet, 9...Through hole, 10...Detection circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (2)

[Claims] (1) A cylindrical soft magnetic body provided with an annular groove, a single or multiple non-magnetic amorphous alloy plate disposed on the opening surface of the soft magnetic body groove, and the non-magnetic a single or plural amorphous magnetic alloy plate having magnetostriction disposed on a surface opposite to the soft magnetic material side of the amorphous alloy plate; a coil wound in the soft magnetic material groove; and a coil wound in the soft magnetic material groove; a cylindrical container that holds the body; a lid that is in contact with the magnetostrictive amorphous alloy plate and has a through hole through which a pressure transmission medium passes; and a lid that is attached to the lid that seals the pressure transmission medium. A high-pressure oil pressure sensor comprising an O-ring and a detection circuit connected to the coil. (2) The high-pressure oil pressure sensor according to claim 1, wherein the nonmagnetic amorphous alloy plate has a band-shaped through hole in a portion corresponding to the soft magnetic groove.