JPH0656767U - Galvanic battery oxygen sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a galvanic battery type oxygen sensor with a fast response speed and stable output. [Structure] Positive electrode 4a comprising a catalytic electrode for electrolytic reduction of oxygen
A galvanic cell type oxygen sensor comprising: a diaphragm 4b; a negative electrode 8 made of lead; and an electrolytic solution 7.
And the supply of the electrolytic solution 7 to the diaphragm 4b is performed by the positive electrode current collector holding portion 1
It is configured to be performed from the electrolytic solution supply perforation 12 and the positive electrode current collector perforation 11 provided in FIG. Even when the diaphragm is thin, or when the diaphragm is used for a long time in a high temperature and dry state, the electrolytic solution is sufficiently supplied to the positive electrode and the diaphragm, so that the response speed is fast and the output is stable.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a galvanic battery type oxygen sensor.

[0002]

[Prior art]

 The galvanic battery oxygen sensor is a sensor that outputs a voltage or current according to the oxygen concentration.It is small and lightweight, operates at room temperature, and is inexpensive, so it is a checker for oxygen deficiency conditions in holds and manholes. It is also used in a wide range of fields such as the detection of oxygen concentration in medical devices such as anesthesia machines and ventilators.

FIG. 3 shows a general structure of a galvanic cell type oxygen sensor. In the figure, 4a is a positive electrode provided with a catalytic electrode for electrolytic reduction of oxygen, which is formed integrally with the diaphragm 4b. The positive electrode 4a and the diaphragm 4b are arranged in the positive electrode collector holding portion 13 provided in the container body 9 via the positive electrode collector 5 made of carbon. 3 is a porous polytetrafluoroethylene film provided on the outer surface of the positive electrode, 8 is a lead negative electrode, 7 is an electrolytic solution, and 6 is a positive electrode current collector. The positive electrode 4a and the diaphragm 4b are in contact with the electrolytic solution 7 through the positive electrode current collector holes 11 provided in the positive electrode holding portion 13.

In such a galvanic cell type oxygen sensor, oxygen that has passed through the diaphragm 4b that selectively permeates oxygen and limits the amount of permeation so as to be commensurate with the electrode reaction is reduced on the catalyst electrode as the positive electrode 4a. , The following electrochemical reaction occurs with the negative electrode 8 via the electrolytic solution 7. [When the electrolyte is acidic] Positive electrode reaction O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O Negative electrode reaction 2Pb + 2H ₂ O → 2PbO + 4H ⁺ + 4e ⁻ Overall reaction 2Pb + O ₂ → 2PbO [When the electrolytic solution is alkaline] Positive electrode reaction O ₂ + 2H ₂ O + 4e ^- → 4OH ^- anode reaction ^{2Pb + 4OH - → 2PbO + 2H} 2 O + 4e - total reaction 2Pb + O ₂ → 2PbO

Although the charge bearer differs depending on whether the electrolytic solution is acidic or alkaline, a current depending on the oxygen concentration is generated between the catalyst electrode and the negative electrode in either case. The current generated by the positive electrode reaction on the catalyst electrode is collected by the current collector and normally flows into the negative electrode through the thermistor element for temperature compensation, and is converted into a voltage signal to obtain the sensor output voltage.

[0006]

[Problems to be solved by the device]

 In order for the above electrochemical reaction to be performed smoothly and the sensor function to be accurately exhibited, oxygen and the electrolytic solution must be smoothly supplied. In the conventional galvanic cell type oxygen sensor, as shown in FIG. 3, the electrolyte was supplied to the positive electrode only through the perforations for the positive electrode current collector, but the diaphragm was relatively thick with about 50 μm. Since the permeation rate is slow, in normal use, it was sufficient to supply the electrolyte solution to the positive electrode and the diaphragm only through the perforations 11 for fitting the positive electrode current collector.

However, when a thin membrane having a thickness of 10 to 30 μm is used to speed up the response of the sensor, the amount of oxygen permeation increases, the electrode reaction is promoted, and the supply of the electrolyte solution to the positive electrode and the membrane catches up. There is a problem that the output of the sensor is reduced. In addition, apart from this, there will be applications for long-term use at high temperature and dry conditions, and even with a thick diaphragm, the amount of evaporation of the electrolyte from the diaphragm will increase, and the same problems as above will arise. come.

The present invention has been made to solve the above problems, and an object thereof is to provide a galvanic battery type oxygen sensor having stable output and good performance.

[0009]

Therefore, in the present invention, in a galvanic cell type oxygen sensor including a positive electrode composed of a catalytic electrode for electrolytic reduction of oxygen, a diaphragm, a negative electrode composed of lead, and an electrolytic solution, The galvanic battery type oxygen is characterized in that the electrolytic solution is supplied to the positive electrode and the diaphragm from the electrolytic solution supply hole provided in the positive electrode current collector holding portion and the positive electrode current collecting hole. The above problem is solved by using a sensor.

[0010]

[Action]

 When the diaphragm is thick, it is sufficient to supply the electrolytic solution to the positive electrode and the diaphragm through the holes for fitting the positive electrode current collector. However, when the diaphragm is thin, the amount of oxygen permeation increases and the reduction reaction at the positive electrode is promoted, the supply of electrolyte cannot keep up, and the output drops. In addition, when used at high temperature and dry conditions for a long time, the amount of evaporation of the electrolytic solution from the diaphragm increases, the supply of the electrolytic solution cannot keep up, and there is a risk of electrolytic solution exhaustion near the positive electrode. The galvanic cell type oxygen sensor according to the present invention is provided with a hole for supplying an electrolytic solution to the positive electrode and the diaphragm, in addition to a hole for fitting the positive electrode current collector in the positive electrode current collector holding portion. The electrolyte is sufficiently supplied to the positive electrode even when the diaphragm is thin or when it is used for a long time in a high temperature and dry state. Therefore, the output is stable and the performance is good.

[0011]

【Example】

 Hereinafter, the present invention will be described with reference to a preferred embodiment. FIG. 1 is a schematic sectional view of a galvanic cell type oxygen sensor according to an embodiment of the present invention. In the figure, 1 is an ABS resin inner lid, and 2 is an O-ring. 4a is a positive electrode made of gold deposited on the tetrafluoroethylene hexafluoropropylene copolymer film 4b. Reference numeral 5 is a positive electrode current collector made of carbon. 6 is a positive electrode current collector made of titanium wire, 7 is an electrolytic solution made of a mixed aqueous solution of acetic acid, potassium acetate and lead acetate, 8 is a negative electrode made of lead, 9 is a container body made of ABS resin, and 10 is made of ABS resin. Is the lid. Each of the container body 9 and the lid 10 is threaded. The inner lid 1, the O-ring 2, the porous poly (tetrafluoroethylene) film 3, the gold-deposited diaphragm 4b, and the positive electrode current collector 5 are pressed by screwing the container body 9 and the lid 10 and are in good contact. State is retained. The inner lid 1 functions as a pressing end plate, and the porous polytetrafluoroethylene film 3 is for preventing the surface of the gold-deposited diaphragm 4b from being soiled. The O-ring 2 ensures airtightness and liquidtightness of these. Reference numeral 11 is a hole for the positive electrode current collector, and 12 is a hole for supplying the electrolytic solution.

FIG. 2 shows the structure of the positive electrode current collector holder of the galvanic cell type oxygen sensor according to one embodiment of the present invention. In the figure, 11 is a hole for fitting the positive electrode current collector wire, 12 is a hole for supplying an electrolyte solution to the positive electrode, and 13 is a holding portion for the positive electrode current collector. In this embodiment, two are provided each.

A galvanic cell type oxygen sensor A having the 25 μm thick diaphragm 3 and a sensor B having the same structure as that of the example except that there is no perforation for supplying an electrolytic solution are used as an output voltage in the atmosphere at 40 ° C. As a result of examining the change with time, it was found that the sensor A of the present invention was very stable, but the output of the sensor B was decreased. This clearly indicates the effect of the perforations for supplying the electrolytic solution in the present invention.

[0014]

[Effect of device]

 As described above, the galvanic cell type oxygen sensor according to the present invention comprises a galvanic cell type oxygen sensor including a positive electrode composed of a catalytic electrode for oxygen electrolytic reduction, a diaphragm, a negative electrode composed of lead, and an electrolytic solution. In the sensor, the electrolytic solution is supplied to the positive electrode and the diaphragm by the electrolytic solution supply hole and the positive electrode current collecting hole provided in the positive electrode current collector holding portion. Even if the diaphragm is thin, the electrolyte is sufficiently supplied to the positive electrode, so that the response speed is fast and stable output can be obtained. Also, stable output can be obtained even when used at high temperature or in a dry state for a long time. The value of the present invention is great.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a view showing a main part of one embodiment of the present invention.

[Explanation of Codes] 1 Inner lid 2 O-ring 3 Porous polytetrafluoroethylene film 4a Positive electrode 4b Separator film 5 Positive electrode current collector 6 Positive electrode current collecting wire 7 Electrolyte solution 8 Negative electrode 9 Container body 10 Lid 11 Hole for positive electrode current collecting wire 12 Perforation for Electrolyte Supply 13 Positive Electrode Current Collector Holding Unit

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[Procedure amendment]

[Submission date] November 11, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 3

[Correction method] Added

[Correction content]

FIG. 3 is a diagram showing a general structure of a galvanic cell type oxygen sensor.

Claims (1)

[Scope of utility model registration request] 1. A positive electrode (4a) comprising a catalytic electrode for electrolytic reduction of oxygen, a diaphragm (4b), and a negative electrode (8) comprising lead.
In the galvanic cell type oxygen sensor, the positive electrode (4a) and the diaphragm (4b) are provided with the electrolytic solution (7) in the positive electrode current collector holding portion (13). A galvanic cell type oxygen sensor, characterized in that it is constituted by a perforation (12) for supplying an electrolyte and a perforation (11) for a positive electrode current collector.