JPH0743615Y2 - Electromagnetic flowmeter detector - Google Patents

Description

[Technical Field of the Invention] The present invention relates to an electromagnetic flowmeter detector, and more particularly to an electrode structure of an electromagnetic flowmeter detector using a ceramic measuring tube.

[Technical background of the device and its problems]

FIG. 3 shows the structure of the electrode portion of the electromagnetic flowmeter detector using the conventional ceramic measuring tube. A ceramic measuring tube (1) has a pair of electrodes (2), the head of which projects into the inner surface of the measuring tube (1). Through the wall of the measuring tube and threaded on the opposite side, the spring (4), washer (5),
It is fixed by nuts (7) via lead terminals (6) for taking out signals.

The inside of the electrode head is hermetically sealed by a packing (3) made of a stretchable material such as rubber or Teflon to prevent the liquid to be measured from leaking into the measuring tube.

In such a conventional structure, since the electrode is projected into the fluid, the high-speed fluid or the slurry causes large wear and may disturb the flow of the fluid, which is unsatisfactory in measurement. Further, even if Teflon is used for the packing (3), the usable temperature is up to about 200 ° C., it cannot be used at higher temperatures, and the heat resistance of the ceramic measuring tube is not utilized.

Recently, as a way to solve the above-mentioned problems, Shoukai 58-1
According to No. 95826, "A conduit for flowing a fluid to be measured formed of a sintered body and a part of this conduit are integrally molded as a conductive sintered body, and the conductive sintered body is used as an electrode to detect a flow signal. An electromagnetic flowmeter characterized by what has been done. " However, in the electromagnetic flowmeter of this published utility model, the sintered body forming the conduit is a ceramic such as alumina or zirconia, and the sintered body forming the electrode is a metal carbide ceramic or Hard powder alloys such as titanium carbide (TiC), silicon carbide (Si
It is disclosed that a material such as C) uses an electrically conductive material. For this reason, the electrode part and the measuring tube part are made of different materials, have poor adhesion, and have different coefficients of thermal expansion, so there is concern about the sealing property.

[Purpose of device]

It is an object of the present invention to provide an electromagnetic flowmeter detector using an integrated electrode type ceramic measuring tube which can withstand high temperatures and is excellent in wear resistance, corrosion resistance and sealability.

[Outline of device]

The present invention provides a cermet having a portion of a wall of a ceramic conduit made of a predetermined insulating ceramic material, which penetrates from the inner surface to the outer surface of the wall, and in which fine metal powder is distributed in the same ceramic material as the ceramic material of the conduit. The electromagnetic flowmeter detector is realized, in which the region is formed by firing as an electrode orthogonal to the axis of the tube, and the intended purpose was achieved.

[Example of device]

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an electrode-integrated ceramic measuring tube of an electromagnetic flowmeter detector according to an embodiment of the present invention. In FIG. 1, (11) is an electrode-integrated ceramic measuring tube, which is formed by sintering the electrode part (15) in a conduit (12) in an integrated manner. (14) is a conductor formed by metallizing, and (15) is a lead wire for taking out the flow rate signal to the outside.

The conduit (12) is pressure-molded into a tubular shape by using a ceramic sintered body material such as alumina or zirconia, and a pair of through holes (12a) with a straight line orthogonal to the axial line of the pipe as a center line at a required position on the pipe wall. Is provided.

On the other hand, in the electrode part (13), the same ceramic sintered body material powder as the material used to mold the conduit (12) is mixed with a metal having high heat resistance and corrosion resistance, such as platinum fine powder or platinum paste, The material is brought into a conductive cermet state and is pressure-molded into a cylindrical shape to be fitted into the through hole (12a).

Most of the ceramics such as metal carbides, nitrides, and oxides are characterized by high hardness, high melting point, low friction coefficient, and little decrease in hardness and strength at high temperature. Is generally fragile. However, the toughness can be significantly increased by filling the ceramic particle gap with a suitable bonding metal. The composite material of ceramic and metal thus formed is generally called cermet.

Then, the electrode (1) is connected to the pair of through holes (12a) of the conduit (12).
3) is incorporated and integrated into a firing furnace to be sintered and completed. The electrode part (13) may be pre-sintered or semi-sintered at low temperature and may be incorporated into the unsintered conduit (12) for sinter-forming.

In the electromagnetic flowmeter detector using the electrode-integrated ceramic measuring tube (11) configured as described above, since no sealing material such as Teflon is used, it can withstand high temperatures,
Measurement at several hundred degrees C is possible. Further, since the electrode portion (13) itself is also ceramic, wear resistance and corrosion resistance are improved. Furthermore, since the conduit (12) and the electrode part (13) are made of the same ceramic sintered body material, the adhesion between them is good and the thermal expansion coefficient is the same, so that the conduit (12) and the electrode part ( 1
3) The sealing property between them becomes more reliable. Further, since the electrode does not project to the inner surface of the conduit, the turbulence of the fluid does not occur.

The present invention is not limited to the above-described embodiment, but can be modified and implemented as shown in FIG. That is, in the electrode part (23) shown in FIG. 2, the cermet part (24) is limited only to the part close to the liquid contact side end face, and the remaining part is composed of the ceramic part (25). A columnar conductor portion (26), one end of which is connected to the cermet portion (24) and the other end of which is exposed at the outer end surface of the ceramic portion (25), is attached to the central axis portion of the cermet portion (24). It is made of the same material as the above, and the signal is guided to the outside.

The electrode (23) of the modified example of FIG. 2 requires less amount of expensive heat-corrosion-resistant metal than the electrode part (13) of the embodiment of FIG. 1, so that the cost can be reduced.

Further, as the ceramic sintered body, alumina (Al
₂ O ₃ ), zirconia (ZrO ₂ · SiO ₂ ), forsterite (2MgO · SiO ₂ ), steatite (MgO · SiO ₂ ), silicon nitride (Si ₃ N ₄ ), and the like. In addition to platinum, gold, tantalum, zircon, titanium, tungsten and the like are used as the heat and corrosion resistant metal.

[Effect of device]

As described above in detail, according to the present invention, the same ceramic material as that of the conduit is penetrated through a part of the wall of the ceramic conduit made of a predetermined insulating ceramic material from the inner surface to the outer surface of the wall. The following effects can be obtained by realizing the electromagnetic flowmeter detector characterized in that the cermet region in which the fine metal powder is distributed is formed by firing as an electrode orthogonal to the axis of the tube.

[1] Since it does not use a sealing material such as Teflon, it can withstand high temperatures and can be measured at several hundred degrees C.

[2] Since the conduit and the electrode part are made of ceramic, wear resistance and corrosion resistance are improved.

[3] Since the conduit and the electrode part are made of the same ceramic sintered body material, the adhesion between them is good and the coefficient of thermal expansion is the same, so the sealing property between the conduit and the electrode part becomes more reliable. .

[4] Since the electrodes do not project into the conduit, the turbulence of the fluid does not occur.

[Brief description of drawings]

FIG. 1 is a sectional view showing an electrode-integrated ceramic measuring tube of an electromagnetic flowmeter detector according to an embodiment of the present invention, FIG. 2 is a perspective view showing a modification of the present invention, and FIG. 3 is a conventional ceramic measuring tube. 3 is a cross-sectional view showing the electrode part of FIG. 11 …… Electrode integrated ceramic measuring tube 12 …… Conduit, 12a …… Through hole 13 …… Electrode part, 14 …… Conductor 15 …… Lead wire, 23 …… Electrode part 24 …… Cermet part, 25 …… Ceramic Part 26 ... Conductor part

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Masaki Katsura Inventor, Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa 1 In Toshiba Research Institute, Inc. Inside the Fuchu Factory (72) Hiroyuki Yoshida 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Within Toshiba Ceramics Co., Ltd. (72) Inventor Shunzo Shimai, Inugata, Togane, Chiba Pref. Company Togane Factory (72) Inventor Noboru Igarashi 1573-8 Tokai, Onuma, Togane-shi, Chiba Toshiba Ceramics Co., Ltd. Togane Factory (56) Reference JP-A-58-66817 (JP, A) JP-A-49 -80594 (JP, A) JP-A-52-139992 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A fine metal powder is distributed in a part of a wall of a ceramic conduit made of a predetermined insulating ceramic material, penetrating from the inner surface to the outer surface of the wall, and in the same ceramic material as the ceramic material of the conduit. An electromagnetic flowmeter detector characterized in that the cermet region is formed by firing as an electrode orthogonal to the axis of the tube.