JPS62175635A - Pressure sensor - Google Patents

Abstract

PURPOSE:To enable the securing of reproducibility of a sensor output, by providing a bridge section adapted to be plastically deformed or fractured under a pressure to always keep the width of a groove-shaped hole of a non-magnetic disc when the sensor is assembled. CONSTITUTION:A sensor is made up of a soft magnetic body, a non-magnetic disc, an amorphous magnetic alloy disc, a coil wound on a groove of the soft magnetic body, a holding container and the like. In the non-magnetic disc 10, an internal disc 10a and an external circular plate 10b are connected with a bridge section 10c and a constriction 10d is provided at the center. As a pressure is applied, the amorphous magnetic alloy is deformed down to deform the bridge section 10c. A stress is concentrated most on the constriction 10d, causing either a plastic deformation or a fracture as shown by (C). When the sensor is assembled, the disc 10 is fixed in place as the internal disc is held on the external circular plate with the bridge section 10c thereby always keeping the width of the groove-shaped hole so constant as to secure the reproducibility of the sensor output.

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. FIG. 4 shows a cross-sectional view of an example of such a pressure sensor. 1 is a cylindrical soft magnetic material provided with an annular groove 1a; 2 is an amorphous magnetic alloy disk having magnetostriction disposed above the cylindrical soft magnetic material; 3 is a soft magnetic material 1 and the amorphous magnetic alloy; This is a spacer made of a non-magnetic disc inserted between the disc 2 and the disc 2. Reference numeral 4 denotes a lid portion having an O-ring 5 and a through hole 6, forming a pressure introduction port 4a. 8 is soft magnetic material 1
A coil is wound around the groove 1a, 7 is a container for storing these, and 10 is a detection circuit.

When pressure is applied to the pressure introduction port 4a, pressure is applied to the amorphous magnetic alloy disk 2 through the through hole 6, pushing it down in the groove 1a, and stress is generated within the amorphous magnetic alloy disk 2.

Due to the generation of this internal stress, the magnetic permeability of the amorphous magnetic alloy decreases due to the magnetostrictive effect.

This change is detected in the form of inductance using the coil 8 and the pressure is measured.

FIG. 5 shows an example of the spacer 3 used in the example shown in FIG. 4, which is separated into an inner circular plate and an outer annular plate by a groove-shaped hole 3b.
The two are connected by a bridge portion 3a to prevent them from coming apart.

Problems to be Solved by the Invention In the sensor configured as described above, complex stress is applied to the amorphous magnetic alloy at the bridge portion 3a, significantly reducing the withstand voltage of the sensor. Therefore, the bridge portion 3a may be omitted (although it is better to do so,
It becomes extremely difficult to position the inner disk, and as a result, the width of the groove-like hole 3b, which determines the sensitivity of this sensor, cannot be set with good reproducibility, which becomes a fatal drawback to the characteristics of the sensor.

Means for Solving the Problems The bridge portion connecting the inner circular plate and the outer annular plate of the nonmagnetic disk is configured to be plastically deformed or broken by applying pressure.

By configuring the functional bridge part to be plastically deformed or broken by applying pressure, the positional relationship between the inner circular plate and the outer annular plate is constant during assembly, and the bridge part is plastically deformed or broken by pressure application during use. Therefore, no complex stress occurs in the amorphous magnetic alloy.

Embodiment FIG. 1 shows an embodiment of the present invention. In the same figure (A), 10 is a non-magnetic disk corresponding to the spacer 3 in the conventional example in FIG.
connected by c. Figure (B) shows the shape of the crosslinked portion.

A constriction 10d is provided in the central portion. As can be seen from FIG. 4, when pressure is applied, the amorphous magnetic alloy deforms downward, deforming the bridge portion 10c. (The fin part is where stress is concentrated the most, causing plastic deformation or breakage as shown in Figure 1(C).

When assembling the sensor, the non-magnetic disc is fixed at a predetermined position by the bridging portion 10c holding the inner disc to the outer annular plate.
The width of the groove-shaped hole in the non-magnetic disk is always constant, ensuring reproducibility of the sensor output. Then, at the time of measurement, the crosslinked portion 10
Since c has already been plastically deformed or fractured by pressure, no complicated stress is generated in the amorphous magnetic alloy, the sensor characteristics are stabilized, and the pressure resistance characteristics are also improved.

FIG. 2(A) shows another form of a non-magnetic disk, in which 11 is a non-magnetic disk, and an inner disk 11a and an outer annular plate 11b are connected by a bridge portion 11c. Figure (B) shows the shape of the crosslinked portion. The whole thing is extremely thin. When pressure is applied, the amorphous magnetic alloy deforms downward, deforming the bridge portion 11c, as in the previous embodiment. Since the bridging member is thin, it cannot withstand the stress caused by the deformation of the amorphous magnetic alloy and undergoes plastic deformation or rupture as shown in FIG. 2(C).

In the case of this embodiment, the same effects as in the embodiment of FIG. 1 can be obtained.

Fig. 3 shows another form of a non-magnetic disc, and as shown in Fig. 3 (A), 12 is a non-magnetic disc with an inner disc 12a and an outer annular plate 12b.
are connected by a bridge portion 12c. The same figure (B) represents the cross-sectional shape of bb' of the bridge part 12c. Bridge part 12
c is made thinner than the whole part. When pressure is applied, the amorphous magnetic alloy deforms downward, deforming the bridge portion 12c, as in the previous embodiment. Since the bridge portion is thin, it cannot withstand the stress caused by the deformation of the amorphous magnetic alloy and undergoes plastic deformation or rupture as shown in FIG. 3(C).

In the case of this embodiment, the same effects as in the embodiment of FIG. 1 can be obtained.

Effects of the Invention By providing a bridge that plastically deforms or breaks under pressure, the width of the groove-shaped hole in the non-magnetic disc is always constant during sensor assembly, ensuring reproducibility of the sensor output. During measurement, the bridge is plastically deformed or fractured by pressure, so no complicated stress is generated in the amorphous magnetic alloy, resulting in stable sensor characteristics and improved pressure resistance.

[Brief explanation of drawings]

FIG. 1(A) is a plan view of a non-magnetic disk in a pressure sensor according to an embodiment of the present invention, FIG. FIG. 4 is a sectional view of a conventional pressure sensor;
FIG. 5 is a plan view of the non-magnetic disk in the embodiment shown in FIG. 10...Nonmagnetic disk, 10a...Inner disk, 10b.
...Outer annular plate, llc...bridge. Name of agent: Patent attorney Toshio Nakao and one other person Figure 2
Figure 3 of the inkstone! z mountain

Claims (1)

[Claims] (1) A cylindrical soft magnetic body provided with an annular groove, and an inner circular plate and an outer annular plate each having a grooved hole corresponding to the groove of the soft magnetic body and separated by the grooved hole. at least one magnetostrictive amorphous magnetic alloy disk that is in contact with the non-magnetic disk on a side opposite to the soft magnetic material; a coil for holding the coils, a container for holding the coils, a means for preventing the pressure transmission medium from flowing out in contact with the amorphous magnetic alloy, and a means for applying pressure to the amorphous magnetic alloy disk in correspondence with the grooves of the soft magnetic material. A pressure sensor comprising: a lid portion having a transmission means; and a bridge portion connecting the inner disk and the outer annular plate of the non-magnetic disk is configured to be plastically deformed or broken by pressure application.