JPH0226034Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to an electromagnetic flowmeter transmitter (hereinafter abbreviated as a transmitter when necessary), and is particularly applicable to a transmitter with an improved wetted electrode. Concerning useful ideas. <Prior Art> FIG. 1 is a sectional view showing a cross section of a conventional transmitter. Reference numeral 1 designates a conduit that can withstand the internal pressure of the fluid to be measured 2, and its inner surface is lined with an insulating lining material 3. A concentric case 4 is disposed outside the conduit 1 and is integrally fixed to the conduit 1 with pipe-shaped bosses 5a, 5b. Excitation coils 6a and 6b are provided between the conduit 1 and the case 4, and apply a magnetic field B to the fluid 2 to be measured. boss 5
The insides of a and 5b are also lined with a lining material 3, and liquid contact electrodes 7a and 7b are inserted inside and fixed with members 8a and 8b. case 4
A leg 9 is fixed to the lower part of the frame with a bolt 10. As the fluid to be measured 2 flows in a direction perpendicular to the plane of the paper, a voltage corresponding to the flow rate of the fluid to be measured is generated in the liquid contact electrodes 7a and 7b under the application of the magnetic field B. In such a conventional transmitter, the mounting portion of the electrode 7 is considerably larger than the aperture, so as the aperture becomes smaller, it becomes difficult to employ this type of electrode structure. Further, since the structure of the electrode portion is complicated, it is difficult to adopt a structure with many pairs of electrodes, and in practical terms, the number of pairs is limited to two. Furthermore, increasing the number of electrodes in contact with liquid increases the number of causes of liquid leakage from the electrodes, leading to a decrease in reliability. Furthermore, if a large number of pairs of electrodes are used, the positions of the excitation coil and the electrode portion may coincide with each other, making it impossible to mount the liquid-contacted electrode at an optimal position. There are drawbacks such as. <Purpose of the invention> In view of the above-mentioned prior art, the present invention aims to obtain a structure of a liquid-contacted electrode that has a simple configuration and requires less installation space. <Structure of the invention> The present invention achieves this object by forming a conduit made of a molded material obtained by mixing a fibrous conductive material into an insulating resin and molding it by extrusion molding. The conductive material is arranged so as to be perpendicular to both the axial direction of the conduit, and a wetted electrode is formed integrally with the conductive material on the outer peripheral surface of the conduit, and the property of the conduit is that it is conductive only in the forming direction. This feature is characterized in that the structure of the liquid-contacted electrode is simplified by using the liquid-contact electrode. <Example> Hereinafter, an example of the present invention will be described in detail based on the drawings. Note that parts having the same functions as those in the prior art are given the same reference numerals, and redundant explanations will be omitted. FIG. 2 is a cross-sectional view showing the main parts of the first embodiment of the present invention. 11 is a conduit through which the fluid 2 to be measured flows. A magnetic field B is applied at right angles to the axial direction of the conduit 11 (direction perpendicular to the plane of the paper). The conduit 11 is made of resin 111, fibrous conductive material 112, and the like. When fibrous conductive material 112 is mixed with resin 111 and extrusion molded under appropriate conditions, the fibrous conductive material is arranged in the molding direction to form conductive material 112.
When they come into contact with each other, the conductivity in the molding direction becomes very good, but on the other hand, the conductivity in the direction perpendicular to the molding direction becomes extremely poor. This type of material is, for example, a mixture of graphite and tetrafluoride resin, manufactured by Yodogawa Kasei Co., Ltd. under the trade name (Yodofuron:
YR-15). The conduit 11 is made of this type of material and is arranged such that its forming direction is perpendicular to the magnetic field B and the axial direction of the conduit 11 , which is the forming direction M. Bolts 12a and 12b are attached to the outer peripheral surface of the conduit 11.
and 13a, 13b are lug plates 14a, 1, respectively.
4b and 15a, 15b. Conduit material 112 and bolt 1 in conduit 11
2a, 12b and 13a, 13b are in electrical contact with liquid contact electrodes 16a , 16b or 17, respectively.
a and 17b . Lug plates 14a, 14
Lead wires 20a, 20 between b and 15a, 15b
b, and the signal terminals 21a, 2 are connected from the midpoint thereof.
1b has been derived. The transmitter of this embodiment can be constructed by inserting the conduit 11 constructed in this way in place of the conduit 11 and lining 3 in FIG. 1, for example. When the fluid 2 to be measured flows while the magnetic field B is applied to the conduit 11 , a signal voltage e is generated in the direction of the arrow. In this case, when the conductivity of the conduit 11 has no directionality and is uniform, the signal voltage e is short-circuited in the conduit 11 as shown by the dotted line 22 , and is generated at the wetted electrodes 16a, 16b , 17a , and 17b . The voltage will be significantly reduced. However, if there is conductivity only in the direction of arrow M as in this embodiment, the dotted line 22
Since the voltage short circuit shown in is not formed, the signal voltage e does not decrease. Moreover, since there is sufficient conductivity in the direction of arrow M, the wetted electrodes 16a , 1
6b or 17a , 17b , a signal voltage that is not attenuated can be detected. Although this embodiment shows an example in which the electrodes are configured as two sets of point electrodes, it is possible to configure more sets as necessary. FIG. 3 is a cross-sectional view showing the main parts of a second embodiment of the present invention. The embodiment shown in FIG. 2 is an example in which a point electrode is used as the electrode in contact with the liquid, but this embodiment is an example in which a surface electrode with a large area in contact with the liquid is used. Figure 3a
The spring materials 23a and 23b are connected to the bolts 12a and 12b.
and 13a, 13b are pressed and fixed to the outer periphery of the conduit 11 , and signal terminals 24a, 24b are brought out from the center of the spring members 23a, 23b to form liquid contact electrodes 25a , 25b together with the conductive material 112. FIG. 3b shows a conductive plate 26b (the same is true for the other side a) having a tooth-shaped inner surface on the outer peripheral surface of the conduit 11 , and a bolt 2
The electrodes 7b and 28b are press-fixed via springs 29b and 30b, respectively, to maintain good contact with the conductive material 112, thereby forming the wetted electrode 31b . The signal voltage from the wetted electrode is received by a converter (not shown) with a high input impedance of about 100 MΩ, so even if the resistance between the conductive material and the conductive plate is on the order of several KΩ, it will affect the operation. Never. When using a surface electrode as shown in FIG. 3, it is possible to reduce the influence of the flow velocity distribution that changes depending on the piping condition on the upstream side, and furthermore, it is possible to reduce the effects of electrochemical The effect of averaging noise can be obtained. FIG. 4 is a perspective view showing the main parts of a third embodiment of the present invention. In FIG. 4, a rectangular conductive material 32b (same for the other side a) having an area in the flow direction of the fluid to be measured is fixed to the outer peripheral surface of the conduit 11 , and a liquid contact electrode 33b is formed together with the conductive material 112. be. Conventionally, such a liquid-contact electrode must be provided on the inner circumferential surface of the conduit, making it difficult to fix or liquid-seal it, but in this embodiment, it is fixed to the outer circumferential surface of the conduit 11 , making it easy to fix. It is simple and there is no need to worry about liquid seals. With such an electrode shape, the influence of flow velocity distribution and electrochemical noise can be reduced compared to the case of point electrodes. Although the shape of the liquid-contact electrode is rectangular in this embodiment, it can easily be formed into a circular, diamond-shaped, or other complicated shape as required. By adopting an optimal shape, the influence of flow velocity distribution can be minimized. FIG. 5 is a perspective view showing the main parts of a fourth embodiment of the present invention. In this embodiment, the outer periphery of the conduit 11 on the upstream and downstream sides of the electrode 34b for detecting the signal voltage (the same is true for the other a side) is surrounded by conductive plates 35 and 36 in a ring shape, and the conductive plates block noise coming in from the outside. 3
5 and 36 are grounded at a grounding point 37 to isolate them. The conductive plates 35 and 36 are each made of conductive material 11
2 and constitute liquid contact electrodes 38 and 39 .
These liquid contact electrodes 38 and 39 have a function as an earth ring. <Effects of the Present Invention> As specifically explained above with reference to the embodiments, according to the present invention, the electrode structure is extremely simple because the wetted electrode can be constructed by simply screwing a bolt or the like onto the outer peripheral surface of the conduit. Therefore, it is extremely easy to create a multi-electrode type transmitter. Moreover, even if the number of electrodes in contact with liquid is increased, there is no fear of liquid leakage, and high reliability can be ensured. Further, even in a transmitter having a relatively small diameter, there is no fear that the electrode mounting portion will hit the excitation coil, so the electrode can be selected at the optimum position where it is least affected by the flow velocity distribution. Furthermore, since a wetted electrode of any shape can be easily made, the optimal shape of the electrode that minimizes the influence of the flow velocity distribution can be selected depending on the state of the mating piping.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a cross section of a conventional transmitter.
Figure 2 is a cross-sectional view showing the main parts of the first embodiment of the present invention, Figure 3 is a cross-sectional view showing the main parts of the second embodiment of the invention, and Figure 4 is the cross-sectional view showing the main parts of the second embodiment of the invention. FIG. 5 is a perspective view showing the main parts of the fourth embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Conduit, 2... Fluid to be measured, 3... Lining material, 4... Case, 11 ... Conduit, 111...
...resin, 112...conductive material, 16a , 16b ,
17a, 17b ...liquid contact electrode, 25a , 25b ...
...Wetted electrode.

Claims (1)

[Scope of utility model registration request] A conduit made of a molded material made by mixing a fibrous conductive material with an insulating resin and molding it by extrusion molding is arranged so that the molding direction of the conduit is perpendicular to both the magnetic field and the axial direction of the conduit. . An electromagnetic flowmeter transmitter, characterized in that a liquid contact electrode is formed integrally with the conductive material on the outer peripheral surface of the conduit.