JPH0348532Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a detector for an electrochemical oxygen analyzer, and more specifically, it relates to a mounting structure for an oxygen molecule permeable membrane. This provides a mounting structure that allows a tensioned state to be obtained.

One type of device for measuring oxygen concentration is an electrochemical oxygen analyzer, which is configured to extract an electrical signal generated in connection with oxidation or reduction by placing a pair of electrodes spaced apart in an electrolytic solution. Generally, a detector used in such an apparatus is configured to close an opening with an oxygen molecule-permeable membrane that does not allow liquid to pass through, but allows gas to pass through, thereby isolating the sample gas and the electrolyte.

By the way, in the past, when attaching such an oxygen molecule permeable membrane, it was done by tying it with thread or fixing it with adhesive so as to close the opening of the detector. However, in the former case, it is difficult to spread the thread evenly without wrinkles or sagging, and the work requires a considerable amount of man-hours, and a groove must be provided around the opening for the thread to hang. However, there are disadvantages such as the complicated shape of the detector. In addition, in the latter case, a membrane that can be fixed with adhesive must be selected, which limits the number of membranes available, and the detector must be fixed until the adhesive hardens, requiring a waiting period. However, there are drawbacks such as the inability to replace the membrane after it has stuck.

In addition, as a solution to this problem, for example, as described in Japanese Utility Model Publication No. 49-4389, a membrane holding system consisting of two disks with a concave surface and a convex surface that are removably fitted together is proposed. It has been proposed to sandwich the membrane between concave and convex surfaces of the device.

However, with this configuration, there is a problem in that a relatively large dark current is generated because air remains in the fitting portion of the concave and convex surfaces of the two discs sandwiching the membrane immediately after assembly.

Dark current has an adverse effect on the detection and measurement of minute currents, and it is desirable to reduce it as much as possible. Therefore, it is necessary to bleed air for a relatively long time after assembly.

The present invention solves these conventional drawbacks and uses a cylindrical mounting body and elasticity as an oxygen molecule permeable membrane in the above-mentioned electrochemical oxygen analyzer detector. It is characterized by using a membrane unit that is stretched so as to close one end of the attachment body with a ring that is removably fitted so as to tightly adhere to the outer periphery of one end of the body.

Hereinafter, a detailed explanation will be given using the drawings.

FIG. 1 is a partial cross-sectional configuration explanatory diagram showing an example of a detector for an electrochemical oxygen analyzer using a membrane unit according to the present invention, and FIG. 2 is an explanatory diagram of its assembled configuration, where 10 is an upper cover, is an O-ring, 30 is a mounting body, 40 is an oxygen molecule permeable membrane, 50 is a ring, 6
0 is the cathode, 70 is the upper part of the case, 80 is the filter,
90 is the anode, 100 is the lower part of the case, 110, 12
0 is a plug, 130 is a temperature sensor, 140 is an insulating sleeve, 150, 160 is a seal plug, 17
0 is a printed wiring board, 180 is a reinforcing plate, and 190 is a lower cover.

The upper cover 10 is screwed to the case upper part 70 and is formed into a disk shape. A sample gas inlet 11 is provided on one side of the upper cover 10.
and a sample gas outlet 12 are provided, and a cylindrical protrusion 13 is provided on the other surface so as to surround the sample gas inlet 11 and the sample gas outlet 12, and an annular protrusion 13 is provided to surround the protrusion 13. A groove 14 is provided. The O-ring 20 is formed to fit on the inner periphery of the mounting body 30 and to face the end surface of the protrusion 13 of the upper cover 10.
The attachment body 30 is formed into a cylindrical shape so as to fit into the outer periphery of the protrusion 13 and the groove 14 of the upper cover 10. As the oxygen molecule permeable membrane 40, a film member such as polytetrafluoroethylene, polyethylene, polypropylene, etc., which is chemically stable to the electrolytic solution, allows gas to pass through but not liquid, and has high elasticity is used. The ring 50 is made of a resilient member such as plastic and is formed so as to be removably fitted to the outer periphery of one end of the mounting body 30 so as to be in close contact therewith. The attachment body 30, the oxygen molecule permeable membrane 40, and the ring 50 constitute a membrane unit according to the present invention.
0, and is stretched so as to close one end of the mounting body 30. When tensioning the oxygen molecule permeable membrane 40, the oxygen molecule permeable membrane 40 is placed on the ring 50 so as to be flat, and then one end of the attachment body 30 is press-fitted into the ring 50. As a result, even if the oxygen molecule permeable membrane 40 cannot be used with adhesives, it can be applied uniformly, and there is no need for any waiting time when using adhesives, which greatly reduces the number of work steps. The membrane 40 can be easily replaced by removing the ring 50, and since an elastic member is used as the ring 50, the dimensional tolerance of the parts can be relatively loose and the shape of the parts can be simplified. Since the oxygen molecule permeable membrane 40 is closely attached to the outer periphery of the mounting body 30 via the ring 50, there is less residual air and dark current is reduced compared to a configuration in which the membrane is sandwiched between the concave and convex surfaces of two discs. It is small and requires only a short time to vent air after assembly. The cathode 60 has a polarizing effect and is fitted to cover the opening 72 of the upper case 70, and is made of, for example, nickel with a ball crown 61 and a plurality of mounting pieces 62 formed and plated with gold. use something Note that the spherical crown portion 61 is provided with a large number of through holes 63 . The case upper part 70 is overlapped so as to enclose the case lower part 100, and together with the case lower part 100 constitutes a case for storing the electrolyte, and is formed in a cylindrical shape with a bottom. A stepped recess 71 for fitting the cathode 60, the membrane unit, the O-ring 20, and the protrusion 13 of the upper cover 10 is formed on the outer surface of the bottom of the case upper part 70, and the stepped recess 71 has an opening in the center. A section 72 is provided. Furthermore, a stepped part 73 is provided inside to regulate the fitting position of the case lower part 100, and an annular stepped part 73 is provided on the inner surface of the bottom part so as to be deeper by h than the top of the cathode 60 attached to a predetermined position. A groove 74 is provided. The filter 80 is attached to the inner peripheral surface of the cathode 60 attached to the case upper part 70, and is made of, for example, filter paper. The anode 90 is made of a metal that is difficult to polarize and has no polarizing effect, and is placed inside the case so as not to come into contact with the cathode 60.
An example is shown in which a lead wire from a book is tightly wrapped into a coil and crushed and then wrapped around the mounting part 101 of the lower part 100 of the case. As described above, the case lower part 100 is included in the case upper part 70, and is formed into a cylindrical shape with a bottom like the case upper part. A cylindrical attachment part 101 having a slit for attaching the anode 90 is provided on the outer surface of the bottom of the case lower part 100, and an elliptical protrusion 10 is provided on the inner surface.
2 is provided. Inside is a printed wiring board 1
Stepped portion 1 for regulating the fitting position of 70
03 is provided. Further, an insertion hole 104 for inserting one of the attachment pieces 62 of the cathode 60 so as to communicate with the area surrounded by the cylindrical attachment part 101 is provided at the bottom, and one end of the anode 90 is inserted therein. insertion holes (not shown), plugs 110, 12 for
Insertion holes 105 and 106 for inserting 0 are provided. The plugs 110 and 120 are inserted into the case and are made of a material such as rubber that does not cause any chemical change in the electrolyte and has elasticity. A temperature sensor 130 such as a thermistor for temperature compensation is inserted into the plug 110, and the plug 120 is hollow. An insulating sleeve 140 is fitted to one lead wire of the temperature sensor 130. Note that seal plugs 150 and 160 are fitted into the openings of the plugs 110 and 120, respectively.
The printed wiring board 170 connects the cathode 60, the anode 90, and the temperature sensor 130 to the external lead wire 171, and is attached to the lower part 100 of the case so that the notch 172 fits into the protrusion 102. Note that the printed wiring board 170 is provided with a wiring pattern, a through hole, a variable resistor, etc., but these are not shown. The reinforcing plate 180 is for reinforcing the lower cover 190, and is made of an insulating material to strengthen the case lower part 10.
The through hole 18 is formed in a disc shape so as to overlap the opening end surface of the
1 is provided. The lower cover 190 covers the open end of the lower case 100 and covers the lower part 1 of the case.
It is removably fitted onto the outer periphery of the 00, and is formed into a cylindrical shape with a bottom made of an elastic member such as rubber, and a bush 191 through which an external lead wire 171 is inserted is integrated at the bottom.

These components are assembled as a detector for an electrochemical oxygen analyzer as follows.

First, attach the mounting piece 6 to the opening 72 of the upper part 70 of the case.
2 and attach the cathode 60. Next, the membrane unit according to the present invention is inserted into the stepped recess 71 so that the oxygen molecule permeable membrane 40 faces the surface of the spherical portion 61 of the cathode 60, and the membrane unit and the stepped recess 71 are
Seal the joint with adhesive. Next, the mounting body 3
The O-ring 20 is arranged on the inner periphery of the upper cover 1, and the protrusion 13 is fitted into the mounting body 30.
0 on top of the case upper part 70 and screw it down. As a result, the oxygen molecule permeable membrane 40 comes into close contact with the surface of the spherical crown part 61 of the cathode 60, and a space communicating with the outside is formed between the upper cover 10 and the oxygen molecule permeable membrane 40. . Next, the filter 80 is placed in close contact with the inner surface of the spherical crown portion 61 of the cathode 60.
Attach. Next, the case lower part 100 with the anode 90 wrapped thereon is attached to the predetermined mounting piece 62 of the cathode 60.
is inserted into the insertion hole 104 and fitted inside the case upper part 70, and the joint between the case upper part 70 and the case lower part 100 is sealed with an adhesive.
Next, for example, a potassium hydroxide (KOH) aqueous solution is injected as an electrolyte from one of the insertion holes 105 and 106, and then the respective insertion holes 105 and 106
Insert the plugs 110, 120 into. In this embodiment, a temperature sensor 130 having an insulating sleeve 140 fitted to one lead wire is inserted into one plug 110, and the other plug 120 is hollow. After inserting the predetermined parts into the plug 110 in this way, each plug 110, 120
The seal plugs 150 and 160 are press-fitted into the openings of the case lower part 100, the plugs 110 and 120, and the seal plugs 150 and 160.
and the openings of the seal plugs 150, 160 are sealed with adhesive. Next, printed wiring board 1
70 inside the case lower part 100, and the cathode 6
0. The ends of the anode 90 and the temperature sensor 130 are inserted into predetermined through holes of the printed wiring board 170 and soldered. Next, a sealant such as epoxy resin is injected so that the adjustment portion of the component provided on the printed wiring board 170 is exposed. Then, the reinforcing plate 180 is attached by inserting the external lead wire 171 through the through hole 181, and the lower cover 190 is attached by inserting the external lead wire 171 through the bush 191 and fitting it to the outer periphery of the case lower part 100.

In such a configuration, when a sample gas is introduced into the space of the upper cover 10, oxygen molecules in the sample gas permeate through the oxygen molecule permeable membrane 40 and are added to the cathode 60. As a result, an electrical signal related to the oxygen concentration is generated between the cathode 60 and the anode 90.

Here, the filter 80 is attached so as to be in close contact with the inner surface of the spherical crown part 61 of the cathode 60, and the cathode 60 is attached at a predetermined position inside the case upper part 70.
An annular groove 7 that is deeper than the top of 0 by h
4, even if air bubbles are generated inside the case, they will gather in the groove 74, and the generated air bubbles will not directly affect the cathode 60. In addition, since the anode 90 is wound along the injection direction of the electrolyte, air can be easily removed during injection of the electrolyte, and the anode 90 can be placed in the electrolyte.
No debris will be scattered. In addition, since the plugs 110 and 120 are arranged in the electrolyte,
Changes in the volume of the electrolyte due to changes in ambient temperature can be absorbed by these plugs 110 and 120, and the degree of adhesion between the oxygen molecule permeable membrane 40 and the cathode 60 does not change due to changes in the volume of the electrolyte, resulting in a stable structure. You can get the output. In addition, the temperature sensor 130
is inserted into the plug 110 placed in the electrolyte, so highly accurate temperature compensation can be performed.

In the above embodiment, an example was shown in which gold-plated nickel was used as the cathode 60, lead wire was used as the anode 90, and potassium hydroxide aqueous solution was used as the electrolyte, but the combination is not limited to these. You may combine them as appropriate.

Further, the temperature sensor is not limited to a thermistor, and an IC or a transistor may also be used.

As described above, according to the present invention, it is possible to realize a mounting structure for an oxygen molecule permeable membrane that is easy to replace and provides a uniform tensioned state with a relatively simple configuration, and has great practical effects.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional diagram showing an example of a detector for an electrochemical oxygen analyzer using a membrane unit according to the present invention, and FIG. 2 is an explanatory diagram of its assembled configuration. 10...Top cover, 20...O ring, 30...
... Mounting body, 40 ... Oxygen molecule permeable membrane, 50 ... Ring, 60 ... Cathode, 70 ... Case upper part, 80
... Filter, 90 ... Anode, 100 ... Bottom of case, 110, 120 ... Plug, 130 ... Temperature sensor. 140...Insulating sleeve, 150,1
60... Seal plug, 170... Printed wiring board, 180... Reinforcement plate, 190... Lower cover.

Claims (1)

[Scope of utility model registration request] For electrochemical oxygen analyzers, a cathode is installed in the opening of the case that houses the electrolyte, an oxygen molecule-permeable membrane is installed in close contact with the outer surface of the cathode, and an anode is installed inside the case so that it does not come in contact with the cathode. In the detector, the oxygen molecule permeable membrane is configured such that one end of the mounting body is closed by a cylindrical mounting body and a ring that has elasticity and is removably fitted so as to tightly fit around the outer periphery of one end of the mounting body. 1. A detector for an electrochemical oxygen analyzer, characterized in that it uses a membrane unit stretched over a membrane unit.