JPH047933B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a measuring tube for an electromagnetic flowmeter used for measuring the flow rate of a fluid to be measured.

[Prior Art] Conventionally, this type of measuring tube for an electromagnetic flowmeter has been constructed as shown in Fig. 12. This will be explained based on the figure. It is a ceramic tube having a flange 2 (only one shown) on each side, and a pair of excitation coils (not shown) that form a magnetic field in a direction perpendicular to the flow direction of the fluid to be measured are provided on the outer peripheral surface so as to face each other. A cylindrical case (not shown) is fitted onto the outer peripheral surface of the flange 2. 3
is a grounding ring that keeps the entire electromagnetic flowmeter and the fluid to be measured at the same potential;
The end face 2a of the flange 2 is provided by subjecting the end face 2a of the flange 2 to metal surface treatment (metallization).
4 is a pair of pipes (only one shown) having a connecting flange 4a and holding the ceramic pipe 1 under pressure with a through bolt (not shown) therebetween;
Reference numeral 5 denotes a gasket interposed between the pipe 4 and the ceramic pipe 1.

In addition, there is a conventional measurement tube for an electromagnetic flowmeter as shown in FIG. 13, which will be explained based on the figure. In the figure, 11 is a metal tube member,
Flanges 12 (only one is shown) are integrally provided at both ends, and a cylindrical case 13 is attached to the outer peripheral surfaces of both flanges 12.
Reference numeral 14 denotes a grounding ring that keeps the entire electromagnetic flowmeter and the fluid to be measured at the same potential, and is in contact with the gasket 15 on the open end surface 11a of the tube member 11 and the gasket 17 on the open end surface 16a of the connecting pipe 16, so that both gaskets 15 , 17, and an extending piece 14a extending in the radial direction is integrally provided on the outer peripheral edge. A lead wire 18 electrically connects the case 13 and the earth ring 14, and is fixed to both members 13 and 14 with screws 19 at both ends.

[Problem that the invention seeks to solve]

However, in the former case, since a part of the earth ring 3 is in contact with the inner wall 1a of the ceramic tube 1, the part of the earth ring 3 that comes into contact with the fluid to be measured containing solids such as sludge and slurry There was a problem that the earth ring 3 was easily worn out and could not maintain its function as the earth ring 3 for a long period of time.

On the other hand, in the latter case, the earth ring 14 is installed on the same axis as the pipe member 11, and therefore skill is required to position the earth ring 14 when installing it on the pipe member 11, making the installation work complicated. There was an inconvenience in having to do so.

[Means for solving problems]

The measurement tube for an electromagnetic flowmeter according to the present invention has an annular stepped portion formed around the opening of the ceramic tube, and
A conductive portion is provided by performing metal surface treatment on the opening end face including the inner surface of the stepped portion, and an annular connector made of a conductive material is fitted into the stepped portion.

In addition, a measurement tube for an electromagnetic flowmeter according to another aspect of the present invention has an annular step formed at the periphery of the opening of the ceramic tube, and a metal surface treatment is applied to the opening end face including the inner surface of the step, thereby making the tube conductive. established a department,
A connector made of a conductive material is elastically mounted within the step portion, and the connector is formed by a partially cut annular body biased in the outer diameter direction.

[Effect]

In the present invention, an annular step is formed at the periphery of the opening of a ceramic tube, and a conductive portion is provided by applying metal surface treatment to the opening end face including the inner surface of the step, and an annular step made of a conductive material is provided within the step. Since the connector is fitted, wear of the connector due to the fluid to be measured can be reduced.

Further, in another aspect of the present invention, an annular step is formed around the opening of the ceramic tube, and a conductive portion is provided by performing metal surface treatment on the opening end face including the inner surface of the step. A connector made of a conductive material is loaded, and this connector is formed by a partially cut annular body that is biased in the outer radial direction. can be positioned on the same axis as

〔Example〕

Figures 1 a and b are a side view and a sectional view showing a measurement tube for an electromagnetic flowmeter according to the present invention, Figure 2 is a sectional view showing the main part of the measurement tube for an electromagnetic flowmeter, and Figure 3 is a measurement thereof. FIG. 2 is a cross-sectional view showing an electromagnetic flowmeter using a tube. In the same figure, the reference numeral 21 is a ceramic tube having flanges 22 at both ends, and annular step portions 23 are formed at the peripheries of both openings.
A conductive portion 24 (thickness: approximately 0.01 mm) extending toward the outer peripheral edge is provided on the opening end face including the stepped inner surface 23a by performing metal surface treatment (metallization). Reference numeral 25 denotes an annular connector electrically connected to both the conductive parts 24, which is fitted into both the stepped parts 23 and fixed by brazing, and is made entirely of a highly wear-resistant conductive material. It is formed. The inner peripheral surfaces of both connectors 25 are exposed within the ceramic tube 21, and are configured to be able to come into contact with the fluid to be measured within the tube. Reference numeral 26 denotes a pair of electrodes (only one of which is shown) for detecting the electromotive force generated at each point in the fluid to be measured, and these electrodes are provided on the wall of the ceramic tube 21 so as to face each other. Reference numeral 27 denotes a cylindrical case having an oscillator attachment portion 27a, which is attached to the outer circumferential surface of the flange 22 of the ceramic tube 21, and has one open end that is attached to the open end surface of the ceramic tube 21, that is, the end surface of the flange 22. Opposing inner flanges 28 are integrally provided. As a result, the conductive portion 24
and the case 27 are electrically connected.
Reference numeral 29 denotes an annular holding plate, which faces the flange end face opposite to the flange 22 with which the inner flange 28 faces, and has a screw 30 attached to the open end face of the case 27.
This electrically connects the conductive portion 24 and the case 27 on the side opposite to the inner flange 28. Reference numeral 31 denotes a pair of excitation coils that form a magnetic field in a direction perpendicular to the flow direction of the fluid to be measured, and are provided between the outer circumferential surface of the ceramic tube 21 and the inner circumferential surface of the case 27 so as to face each other. It is being The reference numeral 32 designates a pair of pipes having flanges 33 for connection, and an electromagnetic flowmeter indicated by reference numeral A is held between these pipes 32 by a through bolt 34. In addition, 35 indicates each pipe 32 and the ceramic pipe 21.
This is a gasket interposed between the

In the measurement tube for an electromagnetic flowmeter constructed in this way, an annular step 23 is formed around the opening of the ceramic tube 21, and the opening end face including the inner surface 23a of this step is subjected to metal surface treatment to make the tube conductive. Since the portion 24 is provided and the annular connector 25 electrically connected to the conductive portion 24 is fitted into the stepped portion 23, wear of the connector 25 due to the fluid to be measured can be reduced.

Although the present embodiment shows an example in which the annular connector 25 is used, the present invention is not limited to this, and the connector 41 may be partially cut off as shown in FIGS. 4a and 4b. Even if it is formed by a C-shaped annular body that is biased in the outer radial direction, the same effect as in the embodiment can be obtained. In this case, the elastic force of the connector 41 is applied in the outer radial direction, and the elastic force of the connector 41 is applied to the gasket 43 in the axial direction.
A pressing force is applied from the side to electrically connect to the conductive portion 44 on the stepped inner surface 42a. Thereby, the connector 41 can be positioned on the same axis as the ceramic tube 45 simply by loading it into the stepped portion 42.

Further, in this embodiment, an example was shown in which the connector 25 is fixed in the stepped portion 23 by brazing, but the fixing method is to cool the connector 46 as shown in FIG. There is a cooling fitting method, a press fitting method in which the connector 47 is press-fitted from the axial direction as shown in FIG. Fixation can also be achieved by loosely fitting a thick connector 48 and using the tightening force of a through bolt 34 (shown in FIG. 2) applied from the gasket 49 side. This brings the connector 48 and the conductive portion 24 into close contact.

Furthermore, in this embodiment, an example was shown in which the step portion 23 is formed into a rectangular cross section as shown in FIGS. The connector 51 may be formed into a circular shape, or may be formed into a trapezoidal cross section as shown in FIG.
Thereby, both members 50 and 51 can be reliably fitted into the stepped portions 52 and 53. In this case, both the stepped portions 52 and 53 urge the connectors 50 and 5 in the outer radial direction.
Each is formed into a shape that matches the shape of 1,
Therefore, both connectors 50 and 51 are connected to the ceramic tube 21.
It does not come off easily.

Furthermore, in this embodiment, case 27
The electrical connection structure of the connector 25 is shown in which the inner flange 28 is brought into contact with the open end surface of the ceramic tube 21, but as shown in FIG. A structure in which the other end is held between the conductive part 24 and the gasket 35, or a structure in which one end of the lead wire 55 is connected to the conductive part 24 by soldering as shown in FIG. 11 may be used.

〔Effect of the invention〕

As explained above, according to the present invention, an annular step is formed around the opening of the ceramic tube, and
A conductive portion is provided by applying metal surface treatment to the opening end face including the inner surface of this stepped portion, and an annular connector made of a conductive material is fitted into the stepped portion, so that wear of the connector due to the fluid to be measured can be reduced. , the function as a conventional earth ring is not lost. In another aspect of the present invention, an annular step is formed around the opening of the ceramic tube, and a conductive portion is provided by applying metal surface treatment to the opening end face including the inner surface of the step, and the conductive portion is provided inside the step. A connector made of a conductive material is loaded in the step, and this connector is formed by a partially cut annular body that is biased in the outer radial direction. Can be positioned on the same axis as the tube,
The installation work can be done extremely easily.

[Brief explanation of drawings]

Figures 1 a and b are a side view and a sectional view showing a measurement tube for an electromagnetic flowmeter according to the present invention, Figure 2 is a sectional view showing the main part of the measurement tube for an electromagnetic flowmeter, and Figure 3 is a measurement thereof. A cross-sectional view showing an electromagnetic flowmeter using a tube, FIGS. 4a and b are a side view and a cross-sectional view showing another first embodiment, and FIGS. 5, 6, and 7 are views inside the step of the connector. 8 and 9 are sectional views showing examples of other shapes of the connector, and Figures 10 and 11 are electrical connections between the connector and the case. 12 and 13 are cross-sectional views showing a conventional measuring tube for an electromagnetic flowmeter. 21...Ceramic tube, 23...Stepped portion, 23a
... Inner surface of stepped portion, 24 ... Conductive portion, 25 ... Connector.

Claims (1)

[Scope of Claims] 1. An annular step is formed around the opening of the ceramic tube, and a conductive portion is provided by applying metal surface treatment to the opening end face including the inner surface of the step, and a conductive material is formed in the step. A measuring tube for an electromagnetic flowmeter, characterized by having an annular connector fitted therein. 2 An annular step is formed around the opening of the ceramic tube, and a conductive part is provided by applying metal surface treatment to the opening end face including the inner surface of the step, and a connector made of a conductive material is elastically mounted within the step. A measurement tube for an electromagnetic flowmeter, characterized in that the connector is formed by a partially cut annular body biased in the outer diameter direction.