JPH011924A - Mechanical quantity sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a mechanical quantity sensor using an alloy having a magnetostrictive effect such as an amorphous magnetic alloy.

BACKGROUND OF THE INVENTION In recent years, mechanical quantity sensors have been proposed that utilize alloys that use magnetostrictive effects, such as amorphous magnetic alloys. As an example, a pressure sensor using an amorphous magnetic alloy as a pressure diaphragm has been proposed.

For example, there are those described in Japanese Patent Application Laid-Open No. 60-88336.

FIG. 5 shows an example.

31 is a cylindrical soft magnetic body provided with an annular groove;
2 is an amorphous magnetic alloy disk having magnetostriction, 33 is a coil wound around the groove of the soft magnetic material, and 34 has one end in contact with the bottom of the groove and the other end in a plane with the opening surface of the soft magnetic material. The non-magnetic ring, 35 is a container for storing these, and 36 is a lid having a through hole 37 for transmitting pressure to the amorphous magnetic alloy. When hydraulic pressure is applied to the hydraulic pressure inlet 38, pressure is applied to the amorphous magnetic alloy disk 32 through the through hole 37, pushing it down in the soft magnetic groove, and stress is generated within the amorphous magnetic alloy disk. 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 a coil 33, and pressure (hydraulic pressure in this case) is measured.

Problems to be Solved by the Invention In a sensor configured as described above, a magnetic circuit is composed of a cylindrical soft magnetic material and an amorphous magnetic alloy disc having magnetostriction, and the magnetic circuit is composed of a cylindrical soft magnetic material and an amorphous magnetic alloy disk having magnetostriction. Pressure is detected by detecting changes in magnetic permeability, that is, changes in magnetic resistance of the magnetic circuit. In this Jinza, the components constituting the magnetic circuit, which is the transducer part, are divided, so it is necessary to uniformly control the magnetic resistance of the cylindrical soft magnetic material when configuring the sensor, and to combine the soft magnetic material with magnetostriction. It is difficult to make the contact state of an amorphous magnetic alloy uniform, and these causes cause variations in the inductance value at the time of assembly of the sensor, and are factors that cause the subsequent output characteristics 11 of the sensor to change significantly. becomes. Furthermore, since these magnetic circuit components are in r+I contact with the sensor container, there is a drawback that the output characteristics are easily affected by temperature.

It is an object of the present invention to eliminate the above-mentioned two drawbacks, to provide a mechanical quantity sensor that stabilizes the sensor output at the time of construction and thereafter, and whose output characteristics are less likely to change due to temperature.

Means for Solving the Problems A metal having magnetostriction which is a material for a mechanical quantity sensor, a material supporting the n1 metal having a thermal expansion coefficient difference of 2X10-6 or less, and a material that supports the metal having magnetostriction, which is a material for a mechanical quantity sensor, and It has a structure in which an external force is indirectly applied to the metal via the support material, and the application of force causes displacement of the magnetostrictive metal, and the change in magnetic permeability that occurs at that time is detected. .

Function: With this configuration, the metal having magnetostriction, which is the material of the mechanical quantity sensor, is separated from the container or the like to which force is applied.

As a result, it is possible to eliminate the output instability caused by the soft magnetic material containing the coil, which occurs in the conventional example, and the instability of the contact state caused by the contact between the soft magnetic material and the magnetostrictive metal that is the sensor material. At the same time, changes due to differences in thermal expansion caused by temperature changes can be reduced, making it possible to reduce the effects of forces other than the detection pressure on the sensor material, making it possible to supply a pressure sensor with extremely stable sensor output characteristics. .

Example The present invention will be explained in detail below using examples.

Example 1 FIG. 1 is a cross-sectional view of one embodiment of this patent.

1 is a cylindrical sensor body made of 45% Ni Fe alloy. A pedestal 2 serving as a force transmission means is provided on one side of the container.
The applied force is transmitted to the sensor body through the contact 3. Since the wall thickness of the contact point 3 portion of the main body is thin, a cylindrical Fe-based amorphous magnetic alloy 4 formed under the applied force is placed below the contact point 3, and both ends of the cylindrical Fe-based amorphous magnetic alloy 4 are
It is firmly attached to the Fe alloy. At this time, the difference in thermal expansion coefficient between Fe-based amorphous magnetic alloy and Ni-Fe alloy is 0.3X10-'
Met. 5 is a coil concentrically wound around a cylindrical amorphous magnetic alloy. 6 is a sensor output detection circuit, 7 is an output terminal, and 8 is rubber for flexible fixing of the base. 9 is a screw for fixing the transducer part.

The force applied from the pedestal 2 is transmitted to the cylindrical amorphous magnetic alloy via the pedestal, and compressive force is applied in the longitudinal direction of the cylinder. This gives displacement to a cylindrical amorphous magnetic alloy having a thickness of 30 μm.

This stress/displacement reduces the magnetic permeability of the amorphous magnetic alloy and causes an inductance change. The results are shown in Figure 2. The measurement frequency was 20kHz. power is 10
Up to kg/cJ, the inductance value decreases monotonically and there is a one-to-one correspondence with the pressure. This relationship allows pressure to be measured.

Further, the temperature characteristics of this output showed almost the same inductance change in the range of -30 to 80°C, and there was almost no pressure hysteresis during pressurization and depressurization, as shown in FIG.

Embodiment 2 FIG. 3 shows another embodiment. 11 is a cylindrical sensor body made of titanium alloy. A pedestal 12 serving as a force transmitting means is arranged on one side of the container, and the applied force is transmitted to the sensor body through contacts 13. Main body contact 13
Since the wall thickness of the portion is formed thin, the applied force is further transmitted to the cylindrical titanium alloy 14 formed below. The titanium alloy is compressed by the applied compressive force in the axial direction of the cylinder, but expands in the radial direction due to Poisson coupling. The stress/strain generated by these is detected by the change in magnetic permeability of the cylindrical cobalt-based amorphous magnetic alloy 15 having magnetostriction fixed on the circumference of the cylindrical titanium alloy 14. At this time, the difference in coefficient of thermal expansion between the cobalt-based amorphous magnetic alloy and the titanium alloy is 0.8X.
It was 10-6. 16 is a coil concentrically wound around a cylindrical amorphous magnetic alloy. 17 is a sensor output detection circuit, 18 is an output terminal, and 19 is rubber for flexible fixing of the base. 20 is a screw for fixing the transducer section. This sensor is 1000k
It can withstand force measurements up to g/cd and is also capable of measuring even higher pressures. The output results as a force sensor were almost the same as in Example 1 and were good.

Embodiment 3 FIG. 4 shows yet another embodiment. 21 is a cylindrical sensor body made of titanium alloy. A pedestal 22 serving as a force transmitting means is arranged on one side of the container, and the applied force is transmitted to the sensor body through contacts 23. Since the wall thickness of the contact point 23 portion of the main body is formed thin, the applied force is further transmitted to the convex cylindrical titanium alloy 24 formed below. The titanium alloy is displaced in the axial direction of the applied tension, and at this time, tension is applied to the magnetostrictive iron-based linear amorphous alloy formed at 25. Here, the iron-based linear amorphous alloy is fixed to the sensor body 21 as if it were solid. The stress/strain generated at this time is detected by a change in magnetic permeability of the linear amorphous magnetic alloy 25. At this time, the difference in coefficient of thermal expansion between the iron-based amorphous magnetic alloy and the titanium alloy was 0.8×10 −6 . 26 is a coil wound concentrically around a cylindrical amorphous magnetic alloy. 27
is a sensor output detection circuit, 28 is an output terminal, 29
is the rubber that flexibly fixes the pedestal. 30 is a screw for fixing the transducer section. This sensor is 3
It can withstand force measurements up to 0.00 kg/cj and is also capable of measuring even higher pressures. The output results as a pressure sensor were almost the same as in Example 1 and were good.

In the structure of the present invention described above, when a material supporting the cylinder having a thermal expansion coefficient difference of 2X10-6 or less with the magnetostrictive metal of the sensor part is used, the structure shown in Examples 1.2 and 3 is used. Although the sensor outputs were almost the same, if the difference in coefficient of thermal expansion was 2X10-6 or more, the temperature characteristics of the sensor outputs fluctuated greatly, making temperature correction of the outputs extremely difficult, making them unsuitable as materials of the present invention. . From this, it is necessary to realize a stable sensor output that the difference in coefficient of thermal expansion between the magnetostrictive metal of the sensor portion and the material supporting the metal is 2×10 −6 or less.

In addition, amorphous magnetic alloys exhibit high magnetic permeability due to their extremely small magnetocrystalline anisotropy, and the magnetostriction generated in the material increases (changes) this magnetic permeability, which improves the detection sensitivity of the sensor. It is particularly excellent as a sensor material.

Effects of the Invention The mechanical quantity sensor of the present invention has extremely good temperature characteristics of the sensor output, exhibits almost the same inductance change in the range of -30 to 80°C, and exhibits a change in pressure when force is applied and when force is released. It has an excellent effect as a sensor with almost no hysteresis. As a result, the detection accuracy is 0.1% of the full scale of the detection power, making it possible to measure mechanical quantities with high precision.In addition, because the configuration is simple, it can be supplied at low cost, making it a great contribution to various pressure controls. be able to.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a mechanical quantity sensor according to an embodiment of the present invention, FIG. 2 is a graph showing the relationship between pressure and inductance change, FIG. 3 is a cross-sectional view of a second embodiment of the present invention, and FIG. The figure is a sectional view of a third embodiment of the present invention, and FIG. 5 is a sectional view of a conventional sensor. ■...Cylindrical sensor body, 2...Pedestal which is a means of transmitting force, 3...Contact point between pedestal and sensor body, 4...
...Cylindrical F' e-based amorphous magnetic alloy, 5...
Coil wound concentrically, 6...Sensor output detection circuit, 7...Output terminal, 8...Pedestal fixing rubber, 9...Transducer fixing screw. Name of agent: Patent attorney Toshio Nakao (K9/cynsu)

Claims (2)

[Claims] (1) A metal that has magnetostriction and a material that supports the metal and has a difference in coefficient of thermal expansion of 2×10^-^6 or less between the metal and the metal, and a force applied from the outside is passed through the support material. Dynamics has a structure in which an external force is indirectly applied to the metal, and the application of force causes displacement of the magnetostrictive metal, and the change in magnetic permeability that occurs at that time is detected. quantity sensor. (2) The mechanical quantity sensor according to claim 1, wherein the magnetostrictive metal is an amorphous magnetic alloy.