JPH07333091A - Pressure sensor - Google Patents

Abstract

PURPOSE:To improve the mounting accuracy of a permeability detection element by providing a head where the permeability detection element is in one piece from a deformed part to a non-deformed part. CONSTITUTION:An amorphous magnetic alloy 5 is hardened and installed, with an adhesive, on the upper surface of a deformed part 4 due to the pressure in a pressure room 3 and a non-deformed part 8 which is not distorted due to pressure. Then, pressure detection head 21 is provided on the alloy 5 which is sealed on the plane of the part 4 as a permeability detection element and a differential head 22 is provided on the alloy 5 which is sealed on the upper surface of a part 8. A head part 23 is constituted with the heads 21 and 22 as a continuous one-piece structure. In this manner, by forming the permeability detection element as a one-piece structure, the mounting accuracy can be further improved as compared with a case where two heads are mounted separately, thus suppressing the scattering in output characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor using the magnetostrictive effect of an amorphous magnetic alloy.

[0002]

2. Description of the Related Art As a conventional technique, a pressure sensor using the magnetostrictive effect of an amorphous magnetic alloy is disclosed in, for example, Japanese Patent Laid-Open No. 2-138.
It is proposed in Japanese Patent No. 842.

FIG. 4 is a sectional view showing a conventional pressure sensor. Note that FIG. 4B is a cross-sectional view taken along the line AA of FIG. In the figure, 1 is a diameter of 5 made of SUS304 steel.
0 mm, height 10 mm T-shaped body, 2 is a pressure inlet having a diameter of 10 mm and height 10 mm provided at the lower end of the body 1, and 3 is a space inside the body 1 in the T-shaped height direction. The pressure chamber is provided so as to transmit the pressure of the pressure inlet 2. Reference numeral 4 denotes a deformed portion provided on the upper surface of the pressure chamber 3, which is formed by processing a part of the main body 1 to a thickness of 1 mm. 8
Is a non-deformable portion so that strain due to the pressure of the pressure chamber 3 does not occur. 5 is a deformed portion 4 on the upper plane of the main body 1.
250 on the non-deformed part 8 with a polyimide adhesive
It is an Fe-Si-B type amorphous magnetic alloy solidified at 1 ° C for 1 hour. Reference numeral 6 denotes a magnetic permeability detecting element, which is a pressure detecting head arranged above the amorphous magnetic alloy 5 fixed on the plane of the deformed portion 4 and is formed by winding a coil around a U-shaped ferrite core 40 times. Reference numeral 7 denotes a differential head provided above the amorphous magnetic alloy 5 fixed to the upper surface of the non-deformed portion 8 and has the same structure as the pressure detection head 6. The measurement magnetic fields of the pressure detection head 6 and the differential head 7 are about 10 O.
These heads are bonded and fixed to the bottom of the substrate of the detection circuit 10 with silicone rubber. 9 is a case in which the detection circuit 10 is attached, and this case 9 is the main body 1
It was fixed with a screw (not shown).

The operation of the conventional pressure sensor configured as described above will be described below.

First, the pressure is transmitted from the pressure introducing port 2 to the pressure chamber 3 and pushes the deformed portion 4. As a result, the amorphous magnetic alloy 5 fixed to the surface of the deformed portion 4 is deformed. Due to this deformation, the magnetic permeability changes due to the inverse magnetostrictive effect of the amorphous magnetic alloy 5, and this is detected by the pressure detection head 6 as a change in inductance. On the other hand, since the non-deformable portion 8 is not deformed even when pressure is applied, the inductance of the differential head 7 does not change. Therefore, the pressure detection head 6
By calculating the difference between the change in the inductance detected in step 1 and the change in the inductance of the differential head 7 in the detection circuit 10, the change in the pressure that cancels the temperature drift is obtained.

[0006]

SUMMARY OF THE INVENTION In the above conventional configuration,
When the amorphous magnetic alloy 5 is fixed to the upper surfaces of the deformed portion 4 and the non-deformed portion 8, the characteristic variations of the amorphous magnetic alloy 5 are different depending on the partial portions, so that the upper surfaces of both are bonded in exactly the same state. Had a problem that it was difficult.

Further, the pressure detection head 6 and the differential head 7 also have a problem that the sensor output characteristics vary unless they are fixed on the upper surface of the amorphous magnetic alloy in the same state.

[0008]

In order to solve the above-mentioned problems, the present invention has a main body in which one end of a cylinder is closed like a flat plate, and the flat plate is formed by the pressure introduced from the other end of the main body. An amorphous magnetic alloy having a magnetostriction is fixed to the deformed portion and the non-deformed portion, which has a deformed portion where strain occurs and a non-deformed portion where dents do not occur. In a pressure sensor for detecting a change in magnetic permeability of an amorphous magnetic alloy due to pressure application and a difference between the deformed and non-deformed parts so as to form a circuit, by an electric means. The magnetic permeability detecting element has a detecting portion at the deformed portion and the non-deformable portion, and a head having a continuous integral structure over the deformable portion and the non-deformable portion.

[0009]

According to the above structure, since the magnetic permeability detecting element is a head having an integral structure, the mounting accuracy is remarkably improved as compared with the case where two heads are mounted separately, and variations in output characteristics are suppressed. It

[0010]

【Example】

(Embodiment 1) FIG. 1 is a sectional view of a pressure sensor according to Embodiment 1 of the present invention, and FIG. 1B is a sectional view taken along the line AA of FIG. Here, the same parts as those of the conventional example are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the figure, the feature of this embodiment is that a pressure detecting head 21 provided on the upper surface of the amorphous magnetic alloy 5 and a head portion 23 in which a differential head 22 is continuously integrated are formed. That is. This pressure detection head 21
The core of the differential head 22 is an E-shaped ferrite, and the coil is wound 100 turns around the recessed portion to form the head portion 23. This head part 23
Are fixed to the lower part of the substrate of the detection circuit 10 with a silicon-based adhesive (not shown).

With this structure, the pressure detecting head and the differential head, which have been separately mounted conventionally, are integrated into the head portion 23, whereby the mounting accuracy is improved, and
The mounting process can be simplified and the cost of the pressure sensor can be reduced.

(Second Embodiment) FIG. 2 is a sectional view of a pressure sensor according to a second embodiment of the present invention.

In FIG. 2, reference numeral 11 denotes a cylindrical carbon steel main body, which is cut so that its lower end is closed in a disk shape. Reference numeral 12 is a pressure introducing port provided at the lower end of the main body 11, and 13 is a pressure chamber through which the pressure of the pressure introducing port 12 is transmitted. Reference numeral 14 denotes a deformed portion of the pressure chamber 13 which is an upper surface portion of the pressure chamber 13 of the main body 11 due to pressure application. Reference numeral 14a is a tensile stress applying portion that receives a tensile stress as the deformed portion 14 is applied with pressure, and 14b is a compressive stress applying portion that receives compressive stress as the deformable portion 14 is applied with pressure. 15 is a deformed portion 1
4 is a Fe-Si-B type amorphous magnetic alloy which is solidified with a polyimide adhesive on 250 ° C. for 1 hour. 16a,
Reference numeral 16b denotes first and second pressure detection heads, which are magnetic permeability detection elements, and are respectively arranged on the tensile stress applying portion 14a and the compressive stress applying portion 14b so as to form a magnetic circuit with the amorphous magnetic alloy 15. . The first and second pressure detection heads 16a and 16b are formed by winding a coil around a U-shaped ferrite core for 100 turns. 17
Is a detection circuit, the second pressure detection head 16b and the case 1
It is clamped on the inner surface of 8. Reference numeral 19 is a screw portion for fixing the pressure sensor.

The operation of the pressure sensor of the second embodiment constructed as above will be described below.

First, the pressure is applied from the pressure inlet 12 to the pressure chamber 1
3, the stress is applied in the direction of expanding the pressure chamber 13. As a result, the deformed portion 14 provided on the upper surface of the pressure chamber 13 changes. Then, the tensile stress applying portion 14a
The amorphous magnetic alloy 15 adhered to the surface of the element receives tensile stress, and the amorphous magnetic alloy 15 adhered to the surface of the compressive stress applying portion 14b receives compressive stress. Next, the magnetic permeability of the amorphous magnetic alloy 15 changes in the opposite directions depending on the stress received by each part. This change is detected by the first and second pressure detection heads 16a and 16b, and the output difference between the two heads is calculated by the detection circuit 17 to obtain the pressure.

In this embodiment, the disk-shaped deformed portion 1
Although No. 4 was manufactured by cutting carbon steel, this part may be formed by separately manufacturing a disc and welding it to a carbon steel column. In this case, needless to say, the cutting cost is reduced because the cutting process is unnecessary.

Further, as shown in FIG. 3, a head portion 30 having a continuous and integrated structure of a pressure detecting head is formed, and the core portion of the head is made of E-shaped ferrite, and a coil is wound 100 turns in each recess. To form two pressure detecting head portions, and the head is fixed to the lower portion of the substrate of the detection circuit 10 with a silicon-based adhesive so that the pressure detecting portions reach the tensile stress applying portion 14a and the compressive stress applying portion 14b. Even if the same effect is obtained.

[0019]

As is apparent from the above description, according to the present invention, the magnetic permeability detecting element is a head having an integral structure, so that the mounting accuracy is higher than that when the two heads are mounted separately. It is possible to significantly improve, suppress variations in output characteristics, and improve yield.

[Brief description of drawings]

FIG. 1A is a sectional view of a pressure sensor according to a first embodiment of the present invention. FIG. 1B is a sectional view taken along line AA of FIG. 1A.

FIG. 2 is a sectional view of a pressure sensor according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a pressure sensor according to a third embodiment of the present invention.

FIG. 4A is a sectional view of a conventional pressure sensor. FIG. 4B is a sectional view taken along line AA of FIG. 4A.

[Explanation of symbols]

 1, 11 Body 2, 12 Pressure inlet 3,13 Pressure chamber 4,14 Deformation part 5,15 Amorphous magnetic alloy 8 Non-deformation part 10,17 Detection circuit 14a Tensile stress application part 14b Compressive stress application part 16a, 21 Pressure detection head 16b, 22 Differential head

Claims (3)

[Claims] 1. A T-shaped main body having a space having a pressure chamber inside in the height direction, a deformed portion which is provided on the upper surface of the main body and which is distorted by the pressure of the pressure chamber, and a strain is not generated. A non-deformed portion, a magnetostrictive amorphous magnetic alloy provided on the upper surface of the deformed portion and the non-deformed portion, and an upper surface of the amorphous magnetic alloy on the deformed portion and the non-deformed portion, respectively. A pressure sensor comprising a head unit in which the magnetic permeability detecting element is integrally formed and a detection circuit for detecting a difference in magnetic permeability of the magnetic permeability detecting element of the head unit by an electric means. 2. A body having a pressure chamber inside a cylinder, a deformed portion on the upper surface of the body where strain is caused by the pressure of the pressure chamber, and a magnetostrictive amorphous magnet provided on the upper surface of the deformed portion. The alloy and the amorphous magnetic alloy are provided on the upper surface of the amorphous magnetic alloy so as to form a magnetic circuit with the amorphous magnetic alloy, at the central portion of the deformed portion where the tensile stress is applied and at the peripheral portion where the compressive stress is applied. A pressure sensor in which a magnetic permeability detection element and a detection circuit for detecting a difference in change of the magnetic permeability detection element by electrical means are sandwiched between the magnetic permeability detection element and a case. 3. The pressure sensor according to claim 2, wherein the magnetic permeability detecting element has an integral structure.