JPS6140557A - Galvanic battery type oxygen sensor - Google Patents

Abstract

PURPOSE:To keep the contact state constant between a diaphragm and a positive pole, by providing a space at a part of a container for holding an electrolytic solution of a galvanic battery type oxygen sensor while a porous body or a cotton-like body is housed in the container. CONSTITUTION:A holding plate 3, O rings 4 and 4', a disphragm 5 comprising a tetraluoroethylene-haxafluoropropyrene copolymer fln, a positive pole 6 made of gold, an intermediate current collector 7 comprising carbon parper and a positive current collector 8 comprising a titanium wire are housed and screwed down between container body 1 and a container lid 2. The container body 1 houses an electrolytic solution 9 comprising acetic acid and a mixed aqueous solution of potassium propionate and lead acetate, a negative pole 10 made of lead and a porous body or cotton-like body 11 made of glass fiber or the like while a space 12 is formed at a part of the container. With such an arrangement, there is no change in the contact state between a disphragm and a positive pole regardless of variations in the internal sensor pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a galvanic T1 pond type oxygen sensor. More specifically, the present invention relates to a galvanic cell type oxygen sensor comprising a positive electrode made of a catalytic electrode effective for reducing oxygen by N solution, a negative electrode made of lead, an electrolytic solution, a diaphragm, and a container.

Galvanic battery-type oxygen sensors are small, lightweight, operate at room temperature, and are inexpensive. etc. for the detection of
Used in a wide range of fields.

Conventional Galvanic Cell Oxygen Sensors are generally comprised of a positive electrode made of a catalyst electrode, a negative electrode made of lead, an electrolytic solution, a diaphragm, and a container.

Furthermore, when classifying the structure of galvanic cell type oxygen sensors, there are types in which the diaphragm and positive electrode are simply in close contact with each other (for example, JP-A-58-187846), and types in which they are integrally joined (for example, British patent 12005
95@). In the former case, oxygen passing through the diaphragm dissolves in the electrolyte film formed between the diaphragm and the positive electrode, and participates in an electrolytic reduction reaction on the surface of the positive electrode. In the latter case, oxygen dissolves into the electrolyte filling the pores of the porous positive electrode and participates in an electrolytic reduction reaction on the pore walls of the positive electrode.

On the other hand, conventionally, the sensor container is filled with electrolyte, but in this case, the temperature of the atmospheric gas surrounding the oxygen sensor is high and the relative humidity is low. Then, water in the electrolyte passes through the diaphragm and evaporates by 3ffl, reducing the sensor internal pressure. Conversely, if the temperature of the atmospheric gas is low and the relative humidity is high, the moisture in the atmospheric gas will not be absorbed by the electrolyte, and the internal pressure of the sensor will increase.

Problems that the invention aims to solve When the sensor internal pressure changes due to increase or decrease in electrolyte, the interval IB! In the case of a type of sensor in which the diaphragm and the positive electrode are in contact, the diaphragm deforms, and the thickness of the electrolyte film between the diaphragm and the positive electrode fluctuates, causing the sensor output to become unstable. In extreme cases, this can lead to the death of the sensor.1Also, even if the diaphragm and the positive electrode are joined together, the positive electrode may be damaged or the diaphragm and the positive electrode may be damaged. Peeling 1. There is a problem with dl.

Means for Solving the Problems The present invention is designed so that the sensor container is not filled with electrolyte, leaving a part of the space, and also contains cellulose and synthetic polymer 11 fibers ( This is an attempt to solve the above-mentioned problems by accommodating a porous body or a cotton-like body made of glass mM.

When the sensor container is filled with a working electrolyte and, for example, water in the electrolyte evaporates, a pressure difference of 1 atmosphere occurs between the atmospheric pressure and the sensor internal pressure. On the other hand, if a space exists without being filled with electrolyte as in the present invention, the internal pressure P of this space is given by the following equation.

P=Po -Vo/V P: Internal pressure of the space Po: Initial internal pressure of the space (1 atm) Vo: Initial volume of the space V: Volume of air after the space has changed, that is, the volume of air in the electrolyte Evaporation of moisture occurs, and when P decreases by 1, the air in the space expands, increasing If the target is made large, P will not decrease much even if a considerable amount of water evaporates. When the increase and decrease in the Renley internal pressure is suppressed in this way, deformation of the diaphragm or the positive electrode is also suppressed.

However, when such a space is removed from the stage C, a new problem arises. In other words, if an oxygen sensor with a space like this is used with the diaphragm at the bottom, there will be no problem, but if the IC is inserted with the diaphragm at the top, the positive electrode will Air comes to the adjacent position, so
The positive electrode and the electrolyte may not be in contact with each other. In such a state, the sensor output will drop significantly.

This point can be solved by housing a porous or cotton-like material made of cellulose, synthetic polymer fibers, or glass fibers in the sensor container. That is, the electrolyte is replenished to the positive electrode due to the capillary action of these porous bodies or flocculent bodies. Moreover, these porous bodies or cotton-like bodies prevent air bubbles from migrating to the positive electrode side.

Embodiment FIG. 1 shows a cross-sectional structure of a galvanic cell type oxygen sensor according to an embodiment of the present invention.

A presser plate (3) is placed between the container body (1) and the container lid (2).
, O-ring (4), <4'), diaphragm (5) consisting of a membrane of tetrafluoroethylene-〇fluoropropylene copolymer
), a positive electrode made of gold <6>, an intermediate current collector made of carbon paper (7), a positive electrode current collector made of titanium wire (8)
are stored and screwed down. A positive electrode (6) is integrally joined to the diaphragm (5) by sputtering.

The container body (1) contains an electrolytic solution (9) made of a mixed aqueous solution of acetic acid, potassium propionate, and lead acetate, a negative electrode (10) made of lead, and glass fiber cotton (11). Moreover, (12) is a space part.

A thermistor (13) for temperature compensation is installed between the positive and negative electrodes.
) and a resistor (14) are connected.

Effects of the Invention 1?When the galvanic cell type oxygen sensor 6 obtained in the embodiment is turned Δ and Δ is turned upside down? The sensor is designated as B, and in the example, the sensor when the glass fiber cotton (11) is not stored is turned upside down and the sensor is designated as C.
In the example, a conventional type without a space (12) and filled with an electrolytic solution is used. When the change in output voltage of the sensor over time was investigated, the results shown in FIG. 2 were obtained.

That is, while sensors A and B showed a stable output voltage for 40 [1], in the case of sensors 1)-0 and D, the output voltage significantly decreased over a short period of time.

In addition, when all the sensors were disassembled and inspected on the 40th [1], no abnormalities were found in A and B, while in C there was no difference between the positive electrode and the diaphragm! 11911I did not occur, but the positive electrode and intermediate current collector were dry, and in D, a portion of the positive electrode had peeled off from the diaphragm.

These results can be explained as follows. That is, first, in the case of all sensors, the water in the electrolyte evaporates, but in the case of sensors A, B, and C, the air in the space expands, and the sensor internal pressure does not decrease much. However, in the case of sensor D, the internal pressure of the sensor decreased significantly, causing deformation of the diaphragm and the positive electrode, and furthermore, the positive electrode partially separated from the diaphragm. It is thought that it was peeled off from the

On the other hand, when the sensor is turned upside down, there is no abnormality in the case of sensor B, but an abnormality occurs in the case of Lennar C. In the case of C, the air in the space becomes bubbles and the middle While the current collector part is covered and the electrolyte is not replenished to the intermediate current collector and the positive electrode, in the case of B, the air bubbles are blocked by the glass II cotton, and the capillary action of this cotton causes j- This is thought to be because the electrolyte was sufficiently supplied to the intermediate current collector and the positive electrode.

[Brief explanation of drawings]

FIG. 1 shows a galvanic electrode according to an embodiment of the present invention.
□Shows the cross-sectional structure of a pond-type oxygen sensor. Figure 2 shows changes over time in the output voltages of oxygen sensor A according to an embodiment of the present invention, oxygen sensor B with Δ turned upside down, oxygen sensor C with cotton-like bodies removed from B, and conventional oxygen sensor D. show. 1... Container body, 2... Container lid, 5... Diaphragm, 6
... Positive electrode, 9... Electrolyte, 10... Negative electrode, 11.
...Glass s1\i string cotton, 12...Space Department Large Z Mesaki Street F:J Kinsen-Zokune City Official Book (Method) % formula% 1, Incident display Showa 59'+11'Fr permission request No. 162289g2
,! Name of the Ming Dynasty Galvanic battery type cable lens Representative Nobuo Nasu 5 Date of amendment order (shipment date) 1980 11 υ 2
70''

Claims (1)

[Claims] 1. In a galvanic cell type oxygen sensor consisting of a positive electrode consisting of a catalytic electrode effective for electrolytic reduction of oxygen, a negative electrode consisting of lead, an electrolyte, a diaphragm, and a container, a part of the space is formed in the container, and A galvanic cell-type oxygen sensor characterized by containing a porous or cotton-like body made of cellulose, synthetic polymer fiber, or glass fiber.