JPH06130026A - Galvanic cell-type oxygen sensor - Google Patents

Abstract

PURPOSE:To provide a galvanic cell-type oxygen sensor wherein its reliability is high even when it is operated at a high temperature or even when it is operated for many hours. CONSTITUTION:A galvanic cell-type oxygen sensor is provided with a positive electrode composed of a catalyst electrode for oxygen electrolytic reduction use, with a negative electrode composed of lead, with an electrolytic solution, with a diaphragm, and with a container which houses them. In the galvanic cell-type oxygen sensor, an electrolytic-solution absorbing member 14 is arranged and installed in an electrolytic-solution passage which is used to supply the electrolytic solution 7 to the positive electrode 5 and the diaphragm 4 in such a way that it is in contact with the positive-electrode collector 5. Even when the operating temperature range of the sensor is wide or even when the sensor is operated for many hours in a high-temperature state and in a dry state, a stable output can be obtained because the electrolytic solution 7 is supplied sufficiently to the positive electrode 5 and the diaphragm 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a galvanic cell type oxygen sensor. More specifically, the present invention relates to a galvanic cell type oxygen sensor including a positive electrode made of a catalytic electrode effective for electrolytic reduction of oxygen, a negative electrode made of lead, an electrolytic solution, a diaphragm, and a container.

[0002]

2. Description of the Related Art A galvanic battery oxygen sensor is small and lightweight, operates at room temperature, and is inexpensive, so it can be used for checking oxygen deficiency conditions in holds and manholes, anesthesia machines, artificial respirators, etc. It is used in a wide range of fields such as detection of oxygen concentration in medical equipment.

FIG. 2 shows a general structure of a conventional galvanic cell type oxygen sensor. In the figure,
1 is an ABS resin inner lid, 2 is an O-ring, 3 is a porous polytetrafluoroethylene film, 4 is a diaphragm made of gold-deposited tetrafluoroethylene hexafluoropropylene copolymer film,
5 is a positive electrode current collector made of carbon, 6 is a lead wire 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, and 9 is ABS.
Resin holder-Main body, 10 is ABS resin holder-
It is a lid. In the holder-body 9 and the holder-lid 10,
Each is screwed. Inner lid 1, O-ring 2,
Porous polytetrafluoroethylene film 3, gold-deposited diaphragm 4,
The positive electrode current collector 5 is pressed by screwing the holder-main body 9 and the holder-lid 10, and a good contact state is maintained. The inner lid 1 functions as a pressing end plate, and the porous poly (tetrafluoroethylene) film 3 is for preventing the surface of the gold-deposited diaphragm 4 from being soiled. Airtight by O-ring 2,
Liquid tightness is secured. Reference numeral 11 is a hole for fitting a lead wire made of titanium wire, 12 is a hole for supplying an electrolytic solution to the positive electrode and the diaphragm, and 13 is a holding portion for the positive electrode current collector.

In the galvanic cell type oxygen sensor, the electrolyte is supplied to the positive electrode and the diaphragm through the holes 12 for supplying the electrolyte.

However, when this oxygen sensor is used in a wide temperature range from low temperature to high temperature, the gas dissolved in the electrolytic solution at low temperature is gasified at high temperature and adheres to the holes for supplying electrolytic solution. However, the supply of electrolyte is blocked,
There is a problem that the output voltage value of the oxygen sensor decreases. Further, when the oxygen sensor is used in a high temperature and dry condition for a long time, the amount of evaporation of the electrolytic solution from the diaphragm increases, and the supply of the electrolytic solution cannot keep up with the same problem as described above.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a highly reliable galvanic system even in a wide temperature range and for a long time. It is to provide a battery-powered oxygen sensor.

[0006]

Therefore, in the present invention, an electrolytic solution absorbing member is disposed in the electrolytic solution passage for supplying the electrolytic solution to the positive electrode and the diaphragm so as to be in contact with the positive electrode current collector, The capillarity of the absorbing member is used to surely supply the electrolytic solution to the positive electrode and the diaphragm to solve the above-mentioned problems. In the present invention, the electrolytic solution absorbing member means a member that absorbs water by a capillary action.

[0007]

As described above, the supply of the electrolytic solution to the positive electrode and the diaphragm is performed from the electrolytic solution supply passage provided in the positive electrode current collector holding portion. However, when the oxygen sensor is used in a wide temperature range from low temperature to high temperature, the gas dissolved in the electrolytic solution at low temperature is gasified at high temperature and adheres to the holes for supplying the electrolytic solution to hinder the supply of the electrolytic solution. As a result, the output voltage value of the oxygen sensor decreases. Further, when used for a long time in a high temperature and dry state, the amount of evaporation of the electrolytic solution from the diaphragm increases, the supply of the electrolytic solution cannot be kept up, and there is a risk of electrolyte depletion in the vicinity of the positive electrode. However, as in the present invention, the electrolytic solution passage for supplying the electrolytic solution to the positive electrode and the diaphragm is provided with the electrolytic solution absorbing member so as to be in contact with the positive electrode current collector. Even if the gas adheres to and the supply of the electrolytic solution is hindered, the electrolytic solution is supplied due to the capillary action of the electrolytic solution absorbing material. Further, even when the electrolytic solution is used for a long time in a high temperature and dry state and the amount of evaporation of the electrolytic solution from the diaphragm increases, the electrolytic solution absorbing member sufficiently supplies the electrolytic solution to the positive electrode and the diaphragm. Therefore, the problem of performance deterioration due to depletion of the electrolytic solution does not occur.

[0008]

EXAMPLES The present invention will be described below with reference to preferred examples. FIG. 1 shows a sectional structure of a galvanic cell type oxygen sensor according to an embodiment of the present invention. In FIG. 1, 1 is ABS
Resin inner lid, 2 O-ring, 3 porous polytetrafluoroethylene film, 4 diaphragm made of gold-deposited tetrafluoroethylene hexafluoropropylene copolymer film, 5 from carbon Positive electrode current collector, 6 is a lead wire 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, and 9 is a holder body made of ABS resin. Reference numeral 10 is a holder-lid made of ABS resin. The holder-body 9 and the holder-lid 10 are each threaded. The inner lid 1, the O-ring 2, the porous polytetrafluoroethylene film 3, the gold-deposited diaphragm 4, and the positive electrode current collector 5 are pressed by the screwing of the holder-body 9 and the holder-lid 10, and are good. The contact state is maintained. The inner lid 1 functions as a pressing end plate, and the porous poly (tetrafluoroethylene) film 3 is for preventing the surface of the gold-deposited diaphragm 4 from being soiled. The O-ring 2 ensures air tightness and liquid tightness. Reference numeral 11 is a hole for fitting a lead wire made of a titanium wire, 12 is a hole for supplying an electrolytic solution to the positive electrode and the diaphragm, 13 is a holding portion for a positive electrode current collector, and 14 is an electrolytic solution absorbing member. In this embodiment, a cellulose sponge is used as the electrolyte absorbing member 14.

The galvanic cell type oxygen sensor obtained in the above-mentioned embodiment is designated as A, and in the embodiment, the conventional sensor having no electrolyte absorbing material in the holes for supplying the electrolyte is designated as B, and -20.degree.
When the heat cycle test at -60 ° C was repeated and the change with time in the output voltage in the atmosphere was examined, the sensor A according to the present invention was very stable, but the sensor B showed a decrease in output. It was This clearly indicates the effect of disposing the electrolyte solution absorbing material in contact with the positive electrode current collector in the electrolyte solution passage for supplying the electrolyte solution to the positive electrode and the diaphragm.

In this embodiment, the electrolytic solution absorbing material is only the perforated portion for supplying the electrolytic solution, but the tip of the electrolytic solution absorbing material may be extended into the electrolytic solution for a long time.

[0011]

As described above, in the galvanic cell type oxygen sensor according to the present invention, the electrolytic solution absorbing member is provided so as to come into contact with the positive electrode current collector in the electrolytic solution passage for supplying the electrolytic solution to the positive electrode and the diaphragm. Is provided. As a result, even when the operating temperature range is wide, or even when it is used for a long period of time in a high temperature and dry state, the electrolytic solution is sufficiently supplied to the positive electrode and the diaphragm, so that a stable output can be obtained. The value of this invention is extremely great.

[Brief description of drawings]

FIG. 1 is a view showing a sectional structure of a galvanic cell type oxygen sensor according to the present invention.

FIG. 2 is a view showing a sectional structure of a conventional galvanic cell type oxygen sensor.

[Explanation of symbols]

 1 Inner lid 2 O-ring 3 Porous polytetrafluoroethylene film 4 Gold-deposited diaphragm 5 Positive electrode collector 6 Lead wire 7 Electrolyte 8 Negative electrode 9 Holder-Main body 10 Holder-Lid 11 For lead wire Hole 12 for supplying electrolyte solution 13 Positive electrode current collector holding portion 14 Electrolyte solution absorbing material

Claims (1)

[Claims] 1. A galvanic cell oxygen sensor comprising a positive electrode composed of a catalytic electrode for electrolytic reduction of oxygen, a negative electrode composed of lead, an electrolytic solution, a diaphragm, and a container accommodating these, wherein the electrolytic solution is applied to the positive electrode and the diaphragm. In the electrolyte passage for supplying,
A galvanic cell type oxygen sensor, characterized in that an electrolytic solution absorbing member is disposed so as to contact the positive electrode current collector.