JPS6311645Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a novel gas concentration measurement sensor, especially for various gases in the air (e.g. carbon monoxide, nitrogen oxide,
The present invention relates to a gas concentration measuring sensor for a measuring device that measures the concentration of sulfur dioxide, hydrogen sulfide, hydrocarbons, alcohol, etc.

The measuring device in which this gas concentration measurement sensor is used is constructed using the principle of constant potential electrolysis, and various gases in the air are electrochemically oxidized or reduced by constant potential electrolysis. The concentration of various gases in the air is measured by measuring the electrolytic current.

The constant potential electrolysis method is a method in which the gas to be measured, which has passed through a diaphragm and been diffused and absorbed into an electrolyte, is electrolyzed at a specific potential, and the resulting diffusion current is detected to measure the concentration of the gas. This is the way to do it. Characteristics of this method include: making it possible to create small and lightweight detectors and detection alarms; being able to measure low concentration gases with high precision; and having little influence from interfering gases.

A conventional gas concentration measuring sensor used in such a gas concentration measuring device that measures gas concentration by the constant potential electrolysis method is shown in FIG. In the figure, 1 is a cylindrical sensor container main body, and openings 2 and 3 are provided on both side walls of the main body 1. One opening 2 is provided with a counter electrode 4 and a comparison electrode 5, and the other opening 3 is provided with a working electrode. 6, and lead wires 7, 8, and 9 are in contact with each pole, respectively. In the figure, the counter electrode 4 and the comparison electrode 5 or their respective lead wires 7 and 8 are not shown separately, but only one of them is shown.
Others are hidden on the other side of the diagram. An air hole 10 is provided in the main body on the side of the opening 2, and a gas ventilation path 11 and an exhaust path 12 are provided in the main body on the side of the opening 3. These are all crimped and fixed, and the electrolyte 13 is filled into the container body. Similarly, only one of the gas ventilation channel and the exhaust channel is shown.

When this sensor is used, air containing the target gas to be measured is sent through the gas ventilation path and comes into contact with the working electrode 6, at which time the gas is electrochemically oxidized or reduced and the electrolytic current generated is detected. In this case, it is inevitable that the amount of electrolyte will increase or decrease depending on the relationship between the electrolyte and the partial pressure of water vapor in the atmosphere in which it is used. When the electrolytic solution decreases, contact between the counter electrode, reference electrode, and working electrode and the electrolytic solution becomes insufficient, which prevents accurate measurement, and the drawback is that the troublesome work of replenishing the electrolytic solution is required. On the other hand, when the electrolyte increases, there is a drawback that leakage occurs due to exceeding the capacity of the sensor container body.

It is an object of the present invention to provide a sensor for measuring gas concentration that can eliminate these drawbacks, always perform normal measurements regardless of the increase or decrease of the electrolyte, and improve measurement accuracy.

According to the present inventors, this purpose is to provide an opening at the bottom of the sensor container body into which an electrolytic solution is filled, and provide a counter electrode, a comparison electrode, and a working electrode in the opening.
It has been discovered that this can be achieved by ensuring that the electrolyte filled in the container is always in sufficient contact with the counter electrode, reference electrode and working electrode.

In particular, the aperture is formed from two apertures, one aperture is provided with a counter electrode, a reference electrode, which communicates with the air hole, ie, the atmosphere, while the other aperture, which communicates with the measuring gas passage, is provided with a working electrode. It has been found that contact between electrodes other than the working electrode and the measurement gas can be prevented.

To explain one embodiment of the present invention in more detail with reference to FIGS. 1 and 2, reference numeral 14 denotes a sensor container body, which is hollow inside and has an opening 15 at the bottom.
is provided. The opening 15 is divided into two openings 17 and 18 by a partition plate 16.
One opening 17 is equipped with a counter electrode 19 and a comparison electrode 20, and the other opening 18 is equipped with a working electrode 21. These, counterpoints 19,
The reference electrode 20 and the working electrode 21 are made by sintering a noble metal catalyst into a semicircular or quarter circle shape on a circular polymer membrane 22 that is permeable to gas but impermeable to liquid. be. Each electrode has lead wires 23, 24, 2
5 are in contact. The counter electrode 19, the comparison electrode 20, and the working electrode 21 are attached to the sensor body using a polymer membrane 22 having the counter electrode 19, the comparison electrode 20, and the working electrode 21.
The outer periphery and center of the sensor are inserted between the bottom plate 26 and the partition plate 16, connected to the sensor container body, and fixed by pressure. Air holes 27 are formed on the counter electrode 19 and comparison electrode 20 sides of the bottom plate 26, and gas ventilation and exhaust passages 28 and 29 are provided on the working electrode 21 side. Furthermore, an air vent hole 30 is provided in the upper part of the sensor container body 14, and a polymer membrane 31 is fixed with an air vent plug 32. Furthermore, container body 1
In order to prevent leakage of the electrolytic solution 33 in the partition plate 1
Above and below 6 are packings 34 and 35 of the same shape.
is inserted.

Gas concentration measurement using the gas concentration measurement sensor of the present invention configured as described above is performed as follows. The air containing the measurement gas sent through the gas ventilation path 28 or 29 of the bottom plate 26 is transferred to the working electrode 21.
The electrolytic current generated when the gas is electrochemically oxidized or reduced is detected. The gas produced by oxidation or reduction at this time is discharged from the gas exhaust path 28 or 29.

The sensor for gas concentration measurement of the present invention has a counter electrode, a comparison electrode, and a working electrode arranged at the bottom of the sensor container body, so that the electrolyte can be kept in contact with the counter electrode, the comparison electrode, the working electrode, and the electrolyte to prevent the amount of electrolyte from decreasing due to use. There will never be insufficient contact. Since the working electrode is provided at the opening communicating with the measurement gas passage and the other electrodes are provided at the opening communicating with the atmosphere, the electrodes other than the working electrode do not come into contact with the measurement gas. Furthermore, even if the electrolytic solution increases, it can be kept within the capacity of the sensor container body by appropriately setting the initial electrolytic solution concentration and amount. Therefore relative humidity 0%
This gas concentration measurement sensor can perform stable measurements over the entire range of ~100%.

Thus, according to the present invention, the electrolytic solution can always be in sufficient contact with the counter electrode, reference electrode, and working electrode regardless of the increase or decrease in the electrolytic solution, and it is possible to always measure a normal gas concentration and improve measurement accuracy. It can be done.

Therefore, the present invention provides a truly effective sensor for measuring gas concentration of this type.

[Brief explanation of the drawing]

Figure 1 is a sectional view of an embodiment of the gas concentration measurement sensor according to the present invention, Figure 2 is an exploded explanatory view of the same,
FIG. 3 is an explanatory diagram of an example of the conventional sensor. 1, 14... Sensor container body, 4, 19... Counter electrode, 5, 20... Reference electrode, 6, 21... Working electrode.

Claims (1)

[Scope of utility model registration request] In a gas concentration measuring sensor for a gas concentration measuring device that measures gas concentration using a constant potential electrolysis method, an opening with two openings is provided at the bottom of the sensor container body into which the electrolyte is filled, and one opening that communicates with the atmosphere is provided. A sensor for measuring gas concentration, characterized in that a counter electrode and a comparison electrode are provided in an opening, and a working electrode is provided in another opening communicating with a measurement gas passage.