JP2590728Y2 - Electric conductivity measurement cell - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring cell of an electric conductivity measuring device used for physics and chemistry, industrial use, agricultural use and the like.

[0002]

2. Description of the Related Art Electric conductivity is a physical quantity mainly used as an index of the concentration of electrolyte in water, and has been widely used in water quality control of boiler water and fertilizer concentration control in the agricultural field. I have. As a method of measuring electric conductivity, a two-electrode method of immersing electrodes of a fixed area at a predetermined distance in a solution and applying an AC voltage to these electrodes to measure a current value flowing between the electrodes. Has been known for a long time, but this two-electrode method is affected by polarization of the solution, so it has the disadvantage that it cannot measure highly accurate electrical conductivity, and is currently used only for simple measurement. .

On the other hand, a four-electrode method has been devised as a measuring method which eliminates the disadvantages of the above-mentioned two-electrode method. At present, the electric conductivity is generally measured by the four-electrode method. In this four-electrode method, four electrodes are immersed in a solution to measure the electrical conductivity, and the effects of the polarization of the solution and the resistance of the cable connecting the electrodes and the measurement circuit are avoided. Since it is possible, it is possible to measure the electric conductivity with higher accuracy than the two-electrode method (for example, see Japanese Utility Model Application Laid-Open No. 2-133677, etc. according to the present inventor).

Conventionally, various types of measuring cells of the four-electrode method electric conductivity measuring apparatus have been put to practical use.
As typical examples, there are a rod-shaped insulator in which dot-shaped or band-shaped electrodes are arranged in the longitudinal direction, and a pipe-shaped electrode in which dot-shaped electrodes are arranged in the longitudinal direction.

[0005]

However, the above-mentioned conventional cell has a structure in which lathe-processed parts are mainly assembled by hand, resulting in poor productivity and an ideal electric field formed around the electrodes. Since the target state is not reached, the influence of the container outside the cell is great, and these factors overlap, making miniaturization difficult and requiring a large amount of liquid to be measured. The present invention has been made for the purpose of improving the above-mentioned disadvantages of the conventional electric conductivity measuring cell, and aims to provide a cell having a small size, a small capacity, a high measuring accuracy, and a high productivity. .

[0006]

According to the present invention, in order to achieve the above object, in a cell of an electric conductivity measuring apparatus for measuring electric conductivity of a liquid to be measured using four electrodes, There is provided an electric conductivity measuring cell, wherein an exposed surface in a cell of each electrode plate is embedded in an insulator so as to be exposed in a vertical direction in parallel with each other and concentrically.

[0007]

As described above, the electric conductivity measuring cell of the present invention is embedded in the insulator such that the exposed surfaces of the electrode plates in the cell are exposed vertically and concentrically to each other. Therefore, the electrode length is short in the direction in which the current flows (vertical direction) and there is no path for the current to flow outside the cell, so that an ideal electric field parallel to the electrode plates is formed, Since the exposed surface in the cell is formed concentrically, that is, in an annular shape, the electrode in the direction of current flow is in contact with the liquid to be measured with a sufficient area even if the length of the electrode is short. Conductivity can be measured. In addition, since each electrode plate is embedded in the insulator concentrically in parallel with the vertical direction, a small and small-capacity measuring cell can be formed.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
The present invention will be specifically described.

FIGS. 1 and 2 show the steps of manufacturing a measuring cell of the present invention by embedding an annular electrode made of a metal plate in a synthetic resin as an insulator, and then additionally processing the inner surface of the cell. First, as shown in FIG. 1, an annular electrode plate having an inner diameter corresponding to each of the outer diameter portions 3a to 3c of the spacer is used by using a spacer 3 having an outer diameter gradually decreasing at predetermined intervals downward. 1a to 1c are fitted respectively. That is, the electrode plate 1a having a larger inner diameter formed by punching a sheet metal is placed on the outer diameter portion 3a of the spacer 3, the electrode plate 1b having the next larger inner diameter is placed on the outer diameter portion 3b, and the electrode plate having the smallest inner diameter is formed. 1c is fitted into the lowermost outer diameter portion 3c,
Finally, the lower end surface of the spacer 3 is brought into contact with the disk-shaped electrode plate 1d. Reference numerals 2a to 2d denote elongated lead wire members formed by bending one side of each of the electrode plates 1a to 1d.

As described above, the electrode plates 1a to 1d are arranged in a mold while being held in parallel at appropriate intervals by the spacers 3, and the resin is filled around the spacers 3 to perform resin molding. . After the molding, the spacer 3 is extracted. At this stage, since the inner surface of the hole of the extracted spacer portion has a circular step shape, this portion is subjected to additional processing (grinding) to finish the inner surface 5 smoothly. In this manner, as shown in FIG. 2, each of the ring-shaped electrode plates 1a to 1d is embedded in the resin insulator 4 in parallel with each other in the vertical direction, and each of the electrode plates 1a
~ 1d are obtained in which the exposed surfaces in the cells are concentrically exposed and arranged.

3 to 5 show an embodiment in which the electric conductivity measuring cell of the present invention is formed in the form of a bar sensor. Four metal pipes 6a to 6d having different diameters are coaxially arranged and embedded in the resin insulator 4, and a tapered hole is formed at the end thereof to finish the inner surface 8 of the cell. Reference numerals 7a to 7d denote lead wire members protruding from the metal tubes 6a to 6d. By using the metal tubes having different tube diameters in this manner, each of the metal tubes 6a to 6d
Thus, a cell in the form of a rod-shaped sensor whose exposed surfaces in the cell are concentrically arranged and exposed in parallel with each other in the vertical direction is obtained, for example, is inserted into a solution such as tanks of various industrial processes to be electrically operated. It can be used particularly advantageously as a rod-shaped sensor or the like for measuring conductivity.

When each cell obtained in this way is used as a four-electrode conductivity measuring cell, the electrode length is short in the direction of current flow and there is no path for current flow outside the cell. An ideal electric field parallel to the electrode plate is formed. In addition, since the exposed surface of each electrode in the cell is formed in a ring around the inner surface of the cell, the electrode is in contact with the liquid to be measured with a sufficient area, and the electrical stability is increased. Therefore, the electric conductivity of the liquid to be measured can be accurately and stably measured.

As described above, the electric conductivity measuring cell according to the present invention has been described in detail with reference to the embodiments. However, it goes without saying that the present invention is not limited to the above-described embodiments.
For example, a spacer having a truncated cone shape, a hyperboloid shape, or the like may be used instead of the spacer 3 whose outer diameter is reduced stepwise, or the inner surface of the upper die (or lower die) of the molding die is formed as described above. The resin molding may be performed using a mold molded into a different shape. In addition, for example, to make the inner surface of the cell a hyperboloid,
The exposed area in the cell of each electrode can be made the same by changing the angle of the exposed end face in the cell of each electrode plate or changing the thickness of each electrode plate. Further, the lowermost electrode plate in the cell may be formed in an annular shape instead of the disk shape as in the embodiment shown in FIGS. 1 and 2, and an electrode member formed in a ring shape in advance may be embedded. Such as molding
The design can be arbitrarily changed without departing from the spirit and features of the present invention.

[0014]

As described above, according to the electric conductivity measuring cell of the present invention, since an ideal electric field is formed and the electric stability is high, the electric conductivity can be measured with high accuracy. Further, the miniaturization is easy, and the electric conductivity can be measured using a small volume of the liquid to be measured. Further, a punching process of the electrode plate (FIG. 3)
5 is unnecessary in the embodiment shown in FIG. 5), the cell can be manufactured by casting or injection molding of a resin insulator, and slight additional processing can be performed. Thus, the productivity can be increased and the electric conductivity measuring cell can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic partial cross-sectional view showing an example of a manufacturing process of an electric conductivity measuring cell of the present invention.

FIG. 2 is a sectional view of a main part of one embodiment of the electric conductivity measuring cell of the present invention.

FIG. 3 is a plan view of another embodiment of the electric conductivity measuring cell of the present invention.

FIG. 4 is a longitudinal sectional view of another embodiment of the electric conductivity measuring cell of the present invention.

FIG. 5 is an enlarged sectional view of a portion A in FIG. 4;

[Explanation of symbols]

1a, 1b, 1c, 1d Electrode plate, 2a, 2b, 2
c, 2d lead wire member, 3 spacer, 3a, 3
b, 3c outer diameter of spacer, 4 resin insulator, 5
Cell inner surface, 6a, 6b, 6c, 6d Metal tube, 7
a, 7b, 7c, 7d Lead wire member, 8 Cell inner surface

Claims (1)

(57) [Scope of request for utility model registration] 1. A cell of an electric conductivity measuring apparatus for measuring electric conductivity of a liquid to be measured using four electrodes, wherein exposed surfaces in the cell of each electrode plate are parallel to each other vertically and concentrically. An electric conductivity measurement cell, wherein the cell is embedded in an insulator so as to be exposed to the outside.