JPS60252252A - Galvanic cell type oxygen sensor - Google Patents

Abstract

PURPOSE:To decrease the change in the internal pressure of an oxygen sensor with the evaporation and absorption of moisture by forming a hermetic space in the sensor and sealing an inert gas or carbon dioxide into the space. CONSTITUTION:A diaphragm 2 made of ethylene tetrafluoride-propylene hexafluoride polymer, a positive electrode 3 consisting of gold, carbon paper 4 and a current collector 5 consisting of expanded titanium are incorporated in the lower part of a holder body 1. On the other hand, a negative electrode 8 consisting of lead and a desired amt. of an electrolyte 9 consisting of an aq. soln. mixture composed of propionic acid, potassium propionate and lead oxide are incorporated in the upper part of the holder 1 and a desired volume of the space part 10 is simultaneously formed therein. The internal pressure of the sensor is thus hardly affected by the evaporation and absorption of the moisture in the electrolyte 9 and the output voltage of the sensor is hardly changed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention: Field of the Invention The present invention relates to a galvanicity curved oxygen sensor. More specifically, the present invention consists of a 4C filtration positive electrode, a negative electrode made of lead, an electrolytic solution, and a spacing (1! spoon) made of an electrolytic solution and a polymeric film. This relates to a galvanic cell-type oxygen sensor in which a thermistor or a thermistor and a resistor are connected to the positive electrode and the color (j).

Conventional technology oxygen sensor has a galvanic bending type (fuel sensor).
There are various types such as 11 type), polarographic type 9 magnetic type and zirconia type. Among them, the galvanic curved oxygen sensor is generally small and inexpensive, and operates at room temperature, so it is suitable for use in ship holds.

It is used in a wide range of fields to detect oxygen deficiency in manpoles, etc., and to measure 1111 degrees of oxygen in anesthetic gas.

A galvanic cell-type oxygen sensor consists of a positive electrode made of a metal effective for electrolytic reduction of oxygen, such as gold, platinum, or silver, and a negative electrode made of a metal such as gold, platinum, or silver, and a water bath made of a mixture of alkali hydroxide, organic acid, and acid salt. When a constant resistance is connected between the positive and negative electrodes, the difference between the current flowing between the positive and negative electrodes and the oxygen concentration is Kii.
! This method takes advantage of linearity.

In a galvanic cell oxygen sensor, the positive electrode, negative electrode, and electrolyte are housed in a cell container. It consists of a septum. The diaphragm made of this polymer film has the function of suppressing the diffusion rate of oxygen that passes through the molecular gaps of the diaphragm and reaches the hidden surface of the IE, if it exceeds 1 iK.

A thermistor for temperature compensation is usually connected between the positive electrode and the negative electrode.

The diaphragm and the heel of the cap are integrated with the t-shaped structure (for example, JP-A-58-1.87846 @) that is in close contact with the 41 VCf.
H-combined, T-ru structure (for example, British patent 12005)
No. 95).

Conventionally, alI! is placed inside the cell container. Is it sealed so that it is filled with liquid? The upper part of the release (as opposed to the diaphragm) is in the release state.

(For example, E-Elsworth, “The Ch
chemicalEngineer'(258L P65(
1972)) Problems that the invention aims to solve Moisture in the electrolyte evaporates, and conversely when the temperature is low and humidity is high, the electrolyte absorbs moisture in the atmosphere.

Therefore, when the electrolyte is sealed and filled in the cell container of the sensor as described above, the pressure inside the cell decreases and increases as water evaporates and absorbs, and the As a result, the diaphragm is dented or bulged (n, 7).In the case of a sensor where the diaphragm and the positive electrode are simply in close contact with each other, if the diaphragm is dented or bulged, the diaphragm and the positive electrode may There is a problem in that the thickness of the electrolyte film formed during this period changes, and the sensor output changes significantly at that moment.

On the other hand, if the diaphragm and the positive electrode are joined together, 1. In the case of a sensor with a structure such as
There is a problem with the electrolyte leaking from the edge of the diaphragm.

On the other hand, in the case of a sensor with a structure in which the upper part of the electrolyte is open, the internal pressure of the cell does not change as described above, but if the sensor is tilted and shaken, the electrolyte may spill out. There is a problem.

3-Means for resolving the problem The present invention forms a sealed space inside the galvanic electric bending type oxygen sensor and fills this space with inert gas or carbon dioxide gas, thereby solving the above problems. It aims to solve problems.

Function Among the above-mentioned means of the present invention, first, the formation of the space has the effect of suppressing fluctuations in the internal pressure of the sensor due to increases and decreases in the amount of electrolyte. γFor example, when the space is 4C, the amount of electrolyte decreases, and in this case, a pressure difference of 1 kg/c- occurs between the atmosphere and the inside of the sensor, but when the space is formed, the internal pressure of the sensor decreases. P is P = Po −Vo /Vo−t−V(Po : l
kq/d, Vo: space fR) 8 initial CD volume.

C: increase/decrease in the volume of the space due to increase/decrease in electrolytic dissolution] and falls within the range of 0 to 1 kg/d. In other words, the differential pressure is always below Lkg/C11. If 0 is made relatively large with respect to ν, the differential pressure becomes extremely small.

Next, when the space is air, approximately 21% of the oxygen contained in the air is dissolved into the electrolyte, and is extinguished by the positive electrode, and then 71. The internal pressure of the processor decreases. If the air in the space is replaced with old gas or carbon dioxide as in the present invention, the sensor internal pressure will be prevented from decreasing due to the f14 consumption of oxygen in the space.

Example 1 Figure 1 shows a schematic cross-sectional structure diagram of a galvanic pond type oxygen sensor according to the first example of the present invention.

Inside the holder body (1), there is a spacer made of tetrafluoroethylene-hexafluoropropylene copolymer (2+), a positive electrode (81) made of gold, a carbon paper (4), and a current collector made of expanded titanium. (4) are stored, and these stored items include the perforated presser plate (5) and O-rings (61, (6)
) is screwed onto the holder lid (7). The diaphragm (2) and the positive electrode (3) are first joined together.

On the other hand, inside the holder body (1), there is a negative electrode (8) made of lead.
) and an electrolytic solution (9) consisting of a mixed aqueous solution of propionic acid, potassium propionate, and lead oxide, and at the same time a space (■0) is formed.1. It's okay.

Empty IA part 1 (October'C is filled with nitrogen gas.

The awakening dissolution t't is 5 cc, and the space part (10) is 0.
5 CC.

A thermistor (■1) is connected between the IF1' skin (3) and the @trough (8). The voltage across the thermistor (11) is proportional to the oxygen resistance IW.

In the example mentioned above, the first and second cases are A and B, respectively, where the space is filled with air and the second case is B.

Adjust the light inside the holder main body (1) using the solution f(9);
The output voltage of the conventional oxygen sensor (in the case where there is no space) is A look at the changes in military songs over time. The results are shown in the table below.

4 ``In other words, in the case of the oxygen sensor according to the present invention (Al), the output work gloves hardly change.
The decrease in the output electrons of Bj and C is large.

When each sensor was disassembled and observed, no abnormality was observed in case 1. However, in case 3, a slight part of the positive electrode was peeled off from the diaphragm. In the case of , C, most of the iE CM has peeled off from the diaphragm r, -0 These results are due to the evaporation of water in the electrolyte, and in the case of A, there is almost no effect. In contrast, in case B, the remaining oxygen is consumed at the positive electrode in the space lK, and the drop in the sensor internal pressure is that much greater than in case A. , C, the diaphragm -1TEf! has a very large decrease in the sensor internal pressure. If you consider that the curvature of the zygote is a more serious problem, try lft.

Effects of the Invention J: As described in detail, the present invention is effective in suppressing changes in the internal pressure of the sensor due to the evaporation and absorption of water, and has extremely great industrial value.

[Brief explanation of the drawing]

FIG. 1 shows a schematic cross-sectional structure of a galvanic cell type oxygen sensor 'IY- according to an embodiment of the present invention. 7- ■...--Holder's body, 2...Diaphragm. 3...Positive electrode, 7...Holder lid, 8
・−・Negative electrode. 9...” Electrolyte, 10... Empty [11 parts. 8- 5 6' 7

Claims (1)

[Claims] A space inside the galvanic cell type oxygen processor consisting of a positive electrode consisting of a positive electrode surrounded by a catalyst effective for the 1E reduction of oxygen, a negative electrode consisting of a dissolution and a separation. Form a space, and fill the space with inert gas or carbon dioxide gas.
[A galvanic cell-type oxygen tank characterized by]→tar.