JPH09145669A - Manufacture of oxygen sensor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacturing method of an oxygen sensor element, which can largely save the material for forming an inner electrode, does not require masking in forming the inner electrode and can shorten the forming time of the inner electrode. SOLUTION: An injector 20, wherein an injection needle 21 is provided and conductive applying liquid 100 for forming an electrode is filled, is prepared. Then, the tip of the injection needle 21 is arranged at an upper edge part 150 of an inner chamber 15 of solid electrolyte. The conductive applying liquid 100 is injected into the inner chamber 15 along an inner surface 152. A lead applied part 102 is formed on the inner surface 152, and an electrode applied part 101 is formed on all-around surface of a bottom part 151 of the inner chamber 15. Then, an ejector 20 having an exhaust needle 21 is used, and the remaining conductive applying liquid 100 is exhausted. Then, the solid electrolyte 10 is dried. Thereafter, the conductive applying liquid 100 is heated and baked.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing an oxygen sensor element used for combustion control of an internal combustion engine for an automobile or the like.

[0002]

2. Description of the Related Art Heretofore, as a gas detector for detecting the oxygen concentration in the exhaust gas of an automobile internal combustion engine, for example, an oxygen concentration electromotive force type device using a ZrO ₂ solid electrolyte is well known. ， Practical application An oxygen concentration detector 9 shown in FIG. 6 is an example of such a gas detector.

An oxygen sensor element 1 for detecting oxygen concentration is provided at the tip of the oxygen concentration detector 9, and the periphery of the oxygen sensor element 1 is covered by a housing 91 and a case 92 with a window. Further, the oxygen concentration detector 9 is provided with a heater 95 for heating the oxygen sensor element 1 to a temperature at which the oxygen concentration can be measured. Also,
When the oxygen concentration detector 9 is used, the flange 93 is attached to the housing 91 to attach the oxygen concentration detector 9 to an exhaust gas passage of an internal combustion engine for an automobile. Reference numeral 99 in the figure is a connector for extracting the sensor output signal of the oxygen sensor element 1.

As shown in FIG. 7, the oxygen sensor element 1 described above is used.
Consists of a cup-type solid electrolyte 10 having an inner chamber 15 closed at one end and open at the other end, and an outer electrode 12 on the outer surface of the solid electrolyte 10 and an inner electrode 15 on the inner surface of the inner chamber 15. Is provided with an inner electrode 11 including a lead portion 112 and a reaction electrode 111. A protective layer 19 for protecting the outer electrode 12 is provided outside the outer electrode 12.

The reaction electrode 111 in the inner electrode 11 outputs the sensor output according to the oxygen concentration to the outer electrode 1.
This is a part that is generated together with 2. Also, the inner electrode 1
The lead portion 112 in 1 is a portion for sending the sensor output generated in the reaction electrode 111 to the outside. The reaction electrode 111 and the lead portion 112 are electrically connected and are generally formed as an integral electrode.

By the way, examples of the electrode forming method for forming the inner electrode 11 include paste, ink, application of a slurry-like conductive coating solution, chemical plating and sputtering. Both methods have Pt, Rh, P having high electronic conductivity, high catalytic activity and high chemical stability.
This is a method of forming the inner electrode 11 by attaching a noble metal such as d to the inner surface of the solid electrolyte 10.

However, the above precious metals are expensive. Therefore, conventionally, in order to reduce the manufacturing cost of the oxygen sensor element 1, the inner electrode 1 capable of saving the amount of the precious metal used.
Several methods of forming No. 1 are considered. As one of them, for the inner surface of the inner chamber 15 in the solid electrolyte 10,
After partially masking, the chemical plating solution containing the noble metal is then applied to the inner chamber 15 as shown in FIG.
There is a method to circulate in (Japanese Patent Publication No. 3-35621)
issue). The masking is applied to a region other than the portion where the inner electrode 11 is to be formed on the inner surface. According to this method, the plating liquid can be attached only to the portion necessary for forming the inner electrode 11.

Further, there is another method of forming the inner electrode, particularly a method applied when forming the inner electrode of the oxygen sensor element having a taper in the inner chamber (Japanese Patent Publication No. 62-10383).
issue). That is, in the above method, first, the solid electrolyte 1
The conductive coating liquid containing the above-mentioned noble metal is previously attached to the entire inner surface of the inner chamber 15 of No. 0. Next, the inner surface is masked so as to have the same shape as the inner electrode 11 to be obtained. After that, fluid pressure is applied to the inner chamber to remove the excess conductive coating liquid from the inner surface other than the masked portion. As described above, the conductive coating liquid can be left only in the portion necessary for forming the inner electrode 11.

[0009]

[Problems to be Solved] However, the above-mentioned Japanese Patent Publication No. 3
In the methods of No. 35621 and Japanese Patent Publication No. 62-10383, a masking jig or the like is required for masking. Further, a step of inserting the masking jig into the inner chamber is required. For this reason, the cost for preparing the masking jig is high, and the labor for inserting the masking jig is required.

In view of the above problems, the present invention can greatly save the material for forming the electrode, does not require masking for forming the inner electrode, and can shorten the time for forming the inner electrode. It is intended to provide a method for manufacturing a sensor element.

[0011]

According to the first aspect of the present invention, one end is closed,
A cup-type solid electrolyte having an inner chamber with the other end open, an outer electrode on the outer surface of the solid electrolyte, and an inner electrode consisting of a lead portion and a reaction electrode on the inner surface of the inner chamber. In the method of manufacturing the oxygen sensor element having, in forming the inner electrode, first, an injection needle is provided,
Prepare an injector filled with conductive coating liquid for electrode formation,
Next, the tip of the injection needle is placed at the upper end of the inner chamber of the solid electrolyte, and the conductive coating solution is injected into the inner chamber so that the inner surface of the solid electrolyte is filled with a lead coating portion for forming a lead portion. ， In addition, the electrode coating part is formed all around the bottom of the inner chamber,
Then, using a discharger having a suction needle at the tip, the tip of the suction needle is inserted into the bottom of the inner chamber to suck out the conductive coating liquid remaining in the inner chamber, and then dry the solid electrolyte. Then, the method of manufacturing an oxygen sensor element is characterized by heating and baking the conductive coating solution.

The operation of the present invention will be described below. In the present invention, the injection of the conductive coating solution into the inner chamber is performed by directing the conductive coating solution from the upper end of the inner chamber toward the bottom of the inner chamber and connecting the inner side surface of the inner chamber. Therefore, during the injection, the conductive coating liquid adheres to the inner surface of the portion that is in direct contact with the conductive coating liquid due to its own viscosity.
Further, since the injection is performed by using an injection needle, the shape of the portion to which the conductive coating liquid adheres becomes a band extending from the upper end of the inner chamber to the bottom (see FIG. 1).

By the injection, the conductive coating solution is retained at the bottom of the inner chamber. As a result, the conductive coating liquid adheres to the entire circumference of the bottom of the inner chamber, and the electrode coating portion is naturally formed on the entire circumference of the bottom. Then, the inner electrode composed of the reaction electrode and the lead portion can be formed by heating and baking the electrode coating portion and the lead coating portion together with the solid electrolyte.

Thus, in the present invention, the electrode coating portion and the lead coating portion connected to the electrode coating portion can be simultaneously formed by only injecting the conductive coating liquid into the inner chamber without masking. (See FIG. 1). In addition, as described above, since masking is not performed, the time required to form the inner electrode can be shortened.

Further, even after the formation of the electrode coating portion,
The conductive coating liquid that has not adhered to the inner surface and the bottom of the inner chamber remains in the inner chamber as it is. In the present invention, the remaining conductive coating liquid can be sucked and collected by using the discharger having the suction needle at the tip. Then, the collected conductive coating solution is returned to the injector and used for forming a new inner electrode. Therefore, in the present invention, the conductive coating liquid, which is a material for forming the inner electrode, can be largely saved.

The ejector having the suction needle can also be used as the injector having the injection needle (see FIG. 1). In this case, it is possible to save the trouble of returning the recovered conductive coating solution to the injector. Therefore, the inner electrode can be efficiently formed. A dispenser can be used as the injector and the ejector.

Next, the viscosity of the conductive coating solution is 20 to
It is preferably 1000 mPa · S. When the viscosity is less than 20 mPa · S, the conductive coating liquid may not adhere to the lead coating portion and the electrode coating portion of the inner chamber. On the other hand, when the viscosity is more than 1000 mPa · S, the variation in the coating film thickness may be large. Further, the thickness of the inner electrode can be adjusted by changing the viscosity of the conductive coating solution.

Next, the injection amount (volume) of the conductive coating liquid into the inner chamber is preferably 1/5 or more of the volume of the inner chamber. When the injection amount is less than 1/5,
There is a possibility that the internal resistance of the element becomes large and the reaction electrode having a required area cannot be formed.

Next, the injection speed of the conductive coating solution is 1
It is preferable to inject at 0 cm ³ / S or less. When the injection speed is higher than 10 cm ³ / S, the variation of the coating width and the film thickness of the lead coating portion becomes large.

Next, as in the invention of claim 2, it is preferable that the inner diameter of the injection needle is 0.1 to 3 mm. If the inner diameter is less than 0.1 mm, the lead coating portion may become too fine. Further, it takes too much time to inject the conductive coating liquid, which may deteriorate the efficiency of forming the inner electrode. On the other hand, when the inner diameter is larger than 3 mm, the dispersion of the coating width and the film thickness of the lead coating portion becomes large.

Next, as in the third aspect of the invention, it is preferable that the conductive coating liquid contains a noble metal powder, an inorganic binder, a resin, a solvent and a stabilizer. As the noble metal powder, Pt, Rh, Pd, etc. can be used. Examples of the inorganic binder include Al ₂ O ₃ and ZrO.
_Two can be used. As the resin, for example, ethyl cellulose, an acrylic binder, a wax binder, or the like can be used. As the solvent, terpineol, toluene, xylene or the like can be used. As the stabilizer, DBP (dibutyl phthalate), DOP (dioctyl phthalate) or the like can be used.

In the invention of claim 4, one end is closed,
A cup-type solid electrolyte having an inner chamber with the other end open, an outer electrode on the outer surface of the solid electrolyte, and an inner electrode consisting of a lead portion and a reaction electrode on the inner surface of the inner chamber. In the method of manufacturing the oxygen sensor element having, in forming the inner electrode, first, an injection needle is provided,
An injector filled with the activation liquid is prepared, and then the tip of the injection needle is placed at the upper end of the inner chamber of the solid electrolyte, and the activation liquid is injected into the inner chamber so that the inner surface of the solid electrolyte is filled. A lead coating portion for forming a lead portion is formed on the side surface, and an electrode coating portion is formed on the entire circumference of the bottom of the inner chamber. Then, using a discharger having a suction needle at the tip, the tip of the suction needle is moved to Is inserted into the bottom of the inner chamber to suck out the activating liquid remaining in the inner chamber, and then the activating liquid attached to the inner chamber is heat-treated to form an activating portion, and then the plating liquid is injected into the inner chamber. Then, a method of manufacturing an oxygen sensor element is characterized in that a plating film for an inner electrode is formed on the activated portion.

In the above method, when the inner electrode of the oxygen sensor element is formed by plating, the plating solution is activated prior to the injection of the plating solution so that the plating solution adheres to the lead coating section and the electrode coating section in the inner chamber. It is necessary to attach the chemical liquid to the relevant part. Therefore, in the invention of claim 4, the same method as that of the invention of claim 1 is utilized to deposit the activation liquid on the inner surface of the inner chamber or the like. Other details are the same as the invention of claim 1 described above.

Next, the activation liquid preferably contains a noble metal salt or a complex compound. As the above-mentioned noble metal salt and complexing alloy, chloroplatinic acid, platinum chloride dinitrodiamine platinum or the like can be used.

In the manufacturing method according to the present invention, not only the oxygen concentration electromotive force type oxygen sensor element but also the limiting current type oxygen sensor element can be manufactured.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 A method for manufacturing an oxygen sensor element according to an embodiment of the present invention will be described with reference to FIGS. The oxygen sensor element obtained by this example has a cup-type solid electrolyte 10 having an inner chamber 15 with one end closed and the other end open as shown in FIG. The oxygen sensor element 1 has an outer electrode 12 on the other hand, and an inner electrode 11 composed of a lead portion 112 and a reaction electrode 111 on the inner surface of the inner chamber 15.

In forming the inner electrode 11 in the method of manufacturing the oxygen sensor element according to the present embodiment, as shown in FIG.
As shown in (c), first, an injection / discharger 20 having an injection / extraction needle 21 and filled with the conductive coating liquid 100 for forming the inner electrode is prepared. Then, FIG. 1 (a) and FIG.
As shown in FIG. 5, the tip of the injection / extraction needle 21 is arranged at the upper end portion 150 of the inner chamber 15 of the solid electrolyte 10, and the conductive coating liquid 100 is placed on the inner surface 15 of the inner chamber 15
Inject into As a result, as shown in FIGS. 1B and 3, the lead coating portion 102 for forming the lead portion is formed on the inner side surface 152, and the electrode coating portion 101 is formed on the entire circumference of the bottom of the inner chamber 15.
To form

Then, as shown in FIG. 1C, the tip of the injection / extraction needle 21 is inserted into the bottom 151 of the inner chamber 15 by using the injection / exhaust device 20, and the inside of the inner chamber 15 is inserted. The conductive coating liquid 100 remaining in the above is sucked out. Next, the solid electrolyte 10 is dried, and then the lead coating unit 10
2. The conductive coating solution 100 applied to the electrode application section 101 is heated and baked. As described above, the conductive coating liquid 100 becomes the inner electrode 11 (see FIG. 7).

The above manufacturing method will be described in detail below. First, a raw material powder such as ZrO ₂ is pressure-molded into a cup mold (FIG. 1A) having an inner chamber having one end closed and the other end open, and then fired at 1200 ° C. This gives
A calcinated cup type solid electrolyte 10 is obtained (FIG. 1).
(A)). Next, as shown in FIG. 2, a large number of fixing holes 30 provided with the solid electrolyte 10 on the top plate 31 of the support base 3
, And fix each of them.

Next, the particle size of precious metal powder is 1 to 3 μm.
The platinum coating powder, the Al ₂ O ₃ powder as the inorganic binder, the ethyl cellulose as the resin, and the terpineol as the solvent are mixed to prepare a conductive coating liquid 100 having a viscosity of 400 mPa · S. Then, the injection and suction needle 2
Prepare a dispenser 2 in which two injectors 20 each having No. 1 are attached. Then, the inside of the pouring / discharging device 20 is filled with the conductive coating liquid 100. The inner diameter of the injection / extraction needle 21 is 1.0 mm.

Next, as shown in FIG. 2, the conductive coating solution 100 is simultaneously injected into the inner chambers 15 of the two solid electrolytes 10 by using the dispenser 2. In the injection, as shown in FIG. 1A, the tip of the injection / suction needle 21 is arranged at the upper end 150 of the inner chamber 15.

Then, the conductive coating liquid 100 is added to the inner chamber 1
5 is injected into the inner surface 152. The conductive coating liquid 100 is injected by pressing the pressing rod 203 (FIG. 2) provided inside the injecting / discharging device 20. The injection rate in the above injection is 0.1 cm ³ / S.

When the injection amount of the conductive coating liquid 100 reaches 2/5 of the inner chamber volume, the injection of the conductive coating liquid 100 is stopped. Then, the solid electrolyte 10 and the conductive coating liquid 100 are allowed to stand for 1.0 minute while the conductive coating liquid 100 is being injected into the inner chamber 15. Then, as shown in FIG. 1C, the injection / extraction needle 21 is attached to the bottom portion 1 of the inner chamber 15.
The conductive coating liquid 1 inserted in the inner chamber 15 and remaining in the inner chamber 15
Suck out 00.

As a result of the above operation, as shown in FIG. 3, a part of the conductive coating liquid 100 is transferred to the inner surface 152 of the inner chamber 15.
To the lead coating section 102. Further, part of the conductive coating liquid 100 adheres to the bottom portion 151 of the inner chamber 15, and this becomes the electrode coating portion 101. Then,
The inner chamber 15 of the solid electrolyte 10 is heated and dried at a temperature of 120 ° C.

Next, on the outer surface of the solid electrolyte 10, P
The conductive coating liquid for forming the outer electrode is attached and dried by pad printing of the t paste, roll transfer, or the like. The solid electrolyte 10 obtained by the above-mentioned operation and having the inner surface formed with the conductive coating liquid 100 for forming the inner electrode and the outer surface formed with the conductive coating liquid for forming the outer electrode, respectively, at a temperature of 1400.
A solid electrolyte 10 having an inner electrode 12 and an outer electrode 11 is formed by heating and firing at ˜1600 ° C. Then, as shown in FIG. 7 described above, a protective layer 19 is provided on the outer periphery of the outer electrode 11 by plasma spraying to form the oxygen sensor element 1.

Next, the operation and effect of this embodiment will be described. In the method of manufacturing the oxygen sensor element of the present example, the conductive coating liquid 100 that does not adhere to the lead coating portion 102 and the electrode coating portion 101 and remains in the inner chamber 15 is used by using the suction / suction needle 21. , Can be collected and reused. Therefore, the amount of the conductive coating liquid 100 used can be greatly saved.

In this example, the conductive coating solution 100 is injected by connecting the inner side surface 152 from the upper end 150 toward the bottom 151. Also,
The injection is performed using the injection / extraction needle 21 having an inner diameter of 1.0 mm. Therefore, during the injection, the conductive coating liquid 100 adheres to the inner surface 152 of the portion which is in direct contact with the conductive coating liquid 100 due to its own viscosity, and the shape of the adhered portion is shown in FIG. Like, the upper end 150
It becomes a band extending further to the bottom portion 151. Then, this attached portion becomes the lead coating portion 102.

By the injection, the conductive coating liquid 100 stays at the bottom portion 152 of the inner chamber 15 (FIG. 1).
(B)). As a result, as shown in FIG. 3, the conductive coating liquid 100 adheres to the entire circumference of the bottom portion 152, and the electrode coating portion 101 is naturally formed there. As a result, in this example, the electrode coating portion 101 and the lead coating portion 102 connected to the electrode coating portion 101 can be simultaneously formed by only injecting the conductive coating liquid 100 into the inner chamber 15 without masking. (See FIG. 1). Further, as described above, the time required to form the inner electrode 11 can be shortened because masking is not performed.

Next, the relationship between the electromotive force and the air-fuel ratio of the oxygen sensor element obtained by the manufacturing method of this example was calculated as 2000
The characteristics of λ = 0.9 to 1.1 were measured by changing the injector injection time at 1100 rpm in a cc6 cylinder engine (λ is the excess air ratio).

Further, the relationship between the electromotive force and the air-fuel ratio of the oxygen sensor element obtained by the conventional manufacturing method in which the inner electrode is formed by masking shown in Japanese Patent Publication No. 3-35621 is as follows. It measured similarly. The results are shown in FIG. As can be seen from the figure, no significant difference could be recognized between the oxygen sensor elements. Therefore, it was found that the manufacturing method according to the present example can manufacture an oxygen sensor element having the same excellent performance as the conventional one.

The calcination of the solid electrolyte before the injection of the conductive coating liquid 100 is performed at a temperature of 1400 to 1600 ° C.
It can also be done at. Further, the subsequent heating and firing of the solid electrolyte coated with the conductive coating liquid is performed at a temperature of 1000 ° C to 1 ° C.
It can also be performed at 600 ° C. In this case, since the heating and firing temperature is low, in order to prevent the adhesive force between the solid electrolyte and the inner electrode from becoming insufficient, as the precious metal powder of the conductive coating liquid, glass below the above heating and firing temperature is used. Preference is given to using quality-forming oxides.

Examples of the oxides include borosilicate glass and phosphate glass. When platinum powder is used as the precious metal powder, it can be aggregated at a temperature lower than the above-mentioned heating and firing temperature.
10 μm platinum powder is used. As a result, the baking temperature of the conductive coating liquid can be set to a low temperature (1600 ° C. or lower), so that the conductive coating liquid with low heat resistance (precious metal powder)
Can be used.

Embodiment 2 In this embodiment, as shown in FIG. 5, a method of forming an inner electrode by plating will be described. That is, in this example, the activation liquid is attached to the solid electrolyte to form the activation portion. Then, an inner electrode is formed by depositing a plating solution on the activated portion.

First, a calcined cup type solid electrolyte 10 similar to that of the first embodiment is prepared. Then, the activation liquid is injected into the inner chamber along the inner surface in the same manner as in the first embodiment. Then, the activation liquid remaining in the inner chamber is sucked out to adhere the activation liquid to the inner surface of the solid electrolyte 10 to form a lead coating portion and an electrode coating portion for forming the lead portion (FIG. 1). (See (a) to (c)). In addition,
The activation liquid is composed of a noble metal salt such as chloroplatinic acid, platinum chloride, or an organic platinum salt.

Then, a reducing agent (sodium borohydride) is injected into the adhering activation liquid to fill the inner chamber, and the whole amount is sucked out, followed by drying at a temperature of 120 ° C. As a result, the portion to which the activation liquid is attached is reduced and metallized to become an activation portion.

Then, a plating solution is injected into the inner chamber of the solid electrolyte. In the injection, first, as shown in FIG. 5, a holder 40 provided on a plating jig (not shown) is provided.
The solid electrolyte 10 is inserted and fixed to the lower end 41 of the. At this time, the injection needle 42 provided in the holder 40 is inserted so as to reach the bottom of the inner chamber 15 of the solid electrolyte 10.

Next, the solid electrolyte 10 is added to the plating solution 4
It is immersed in a plating tank (not shown) filled with 9. And
The air in the holder 40 is sucked. As a result, the plating liquid 49 is sucked out from the suction needle 42. Along with this, the plating solution 49 is sucked into the inner chamber 15 through the pores 410 provided in the holder 40. Therefore, the inner chamber 15 is filled with the plating solution 49, and the activation part 109 of the inner chamber 15 is filled.
The plating solution 49 adheres to the.

Then, the air is fed into the pipe 40. As a result, the plating liquid 49 is delivered from the suction needle 42. Along with this, the plating solution 49 is discharged from the pores 410 to the outside of the inner chamber 15. The above operation is repeated several times to obtain a plating film having a desired thickness on the activation section 109. The plating film serves as an inner electrode including a lead portion and a reaction electrode. Others are the same as those in the first embodiment.

According to this example, it is possible to manufacture an oxygen sensor element having an inner electrode made of a plated film having excellent adhesion. Further, the same effect as that of the first embodiment can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a step of adhering a conductive coating liquid for forming an inner electrode to a solid electrolyte (a) to (c) in the first embodiment.

FIG. 2 is an explanatory view of an operation of adhering a conductive coating liquid for forming an inner electrode to a solid electrolyte in the first embodiment.

FIG. 3 is a cross-sectional view of a solid electrolyte having lead coating portions and electrode coating portions of (a) and (b) in the first embodiment.

FIG. 4 is a diagram showing a relationship between an air-fuel ratio and an electromotive force in the oxygen sensor element according to the present invention and the conventional oxygen sensor element in the first embodiment.

FIG. 5 is an explanatory view of an operation of attaching a plating solution to a solid electrolyte in the second embodiment.

FIG. 6 is a cross-sectional explanatory view of an oxygen concentration detector in a conventional example.

FIG. 7 is a sectional view of an oxygen sensor element in a conventional example.

[Explanation of symbols]

 1. . . Oxygen sensor element, 10. . . Solid electrolyte, 100. . . Conductive coating solution, 101. . . Electrode application section, 102. . . Lead coating section, 109. . . Activation section, 11. . . Inner electrode, 111. . . Lead portion, 112. . . Reaction electrode, 12. . . Outer electrode, 15. . . Interior room, 150. . . Upper end, 151. . . Bottom, 152. . . Inner surface, 49. . . Plating solution,

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiromi Sano 1-1-1, Showa-cho, Kariya city, Aichi prefecture Nihon Denso Co., Ltd.

Claims (4)

[Claims] 1. A cup-type solid electrolyte having an inner chamber having one end closed and the other end open, wherein an outer electrode is provided on an outer surface of the solid electrolyte and a lead is provided on an inner surface of the inner chamber. In a method of manufacturing an oxygen sensor element having an inner electrode composed of a reaction part and a reaction electrode, in forming the inner electrode, first, an injector having an injection needle and filled with a conductive coating liquid for electrode formation is used. Then, the tip of the injection needle is placed at the upper end of the inner chamber of the solid electrolyte, and the conductive coating solution is injected into the inner chamber according to the inner surface, and leads for forming the lead portion are formed on the inner surface. An electrode coating part is formed on the entire circumference of the bottom part of the inner chamber, and then the tip of the suction needle is inserted into the bottom part of the inner chamber by using an ejector having a suction needle at the tip. The conductive coating liquid remaining in the inner chamber is sucked out, and then the solid A method for manufacturing an oxygen sensor element, which comprises drying a body electrolyte and then heating and baking the conductive coating solution. 2. The method for manufacturing an oxygen sensor element according to claim 1, wherein the injection needle has an inner diameter of 0.1 to 3 mm. 3. The method for manufacturing an oxygen sensor element according to claim 1, wherein the conductive coating liquid contains a noble metal powder, an inorganic binder, a resin, a solvent and a stabilizer. 4. A cup-type solid electrolyte having an inner chamber having one end closed and the other end open, wherein an outer electrode is provided on an outer surface of the solid electrolyte and a lead is provided on an inner surface of the inner chamber. In a method of manufacturing an oxygen sensor element having an inner electrode composed of a reaction part and a reaction electrode, in forming the inner electrode, first, an injector having an injection needle and filled with an activating liquid is prepared, and then, The tip of the injection needle is disposed at the upper end of the inner chamber of the solid electrolyte, and the activating liquid is injected into the inner chamber so that the inner surface of the solid electrolyte is filled with a lead coating portion for forming a lead portion. An electrode coating is formed on the entire circumference of the bottom of the chamber, and then an ejector having a suction needle at the tip is used to
The tip of the suction needle is inserted into the bottom of the inner chamber to suck out the activating liquid remaining in the inner chamber, and then the activating liquid attached to the inner chamber is heat-treated to form an activating part, and then ，
A method for manufacturing an oxygen sensor element, which comprises injecting a plating solution into the inner chamber to form a plating film for an inner electrode on the activated portion.