JP4887981B2 - Method for manufacturing gas sensor element - Google Patents

Description

  The present invention relates to a method for manufacturing a gas sensor element for detecting a specific gas concentration in a gas to be measured.

Conventionally, a gas sensor element for detecting a specific gas concentration in a measured gas such as exhaust gas by providing a measured gas side electrode on one surface of the solid electrolyte body and a reference gas side electrode on the other surface has been provided. is there. The gas sensor element is provided with a porous protective layer so as to cover a gas inlet for introducing the measurement gas in order to protect the measurement gas side electrode from poisonous substances contained in the measurement gas such as exhaust gas. ing.
Since the porous protective layer is formed by immersing and attaching the tip of the gas sensor element to the ceramic protective layer forming material, the porous protective layer is basically formed over the entire circumference of the tip of the gas sensor element.

  Further, the exhaust gas of the internal combustion engine contains water droplets generated by the combustion of the fuel. If these water droplets or the like adhere to the ceramic gas sensor element, particularly the heater part, which is at a high temperature when the gas sensor is used, it adheres. The temperature of the affected part rapidly decreases, and a temperature difference is generated between it and the surrounding area. The stress due to this may cause cracks, cracks, etc. in the ceramic, leading to disconnection of the heating element.

  In other words, the gas sensor element is heated by a built-in heater unit. At this time, if water droplets flying together with the gas to be measured adhere to the surface of the gas sensor element, the element may be cracked. In particular, when the water is applied to the side corners of the heater substrate close to the heating element of the heater part, a large temperature difference can be generated between the heater and the surroundings, and stress is likely to be concentrated, leading to element cracking.

  When the present inventors observed the occurrence of cracks due to the adhesion of water droplets, the water droplets adhering to the porous protective layer were instantly absorbed and diffused by the water retention of the porous protective layer, and the temperature around the adhered portion suddenly increased. It was found that the water resistance of the porous protective layer was lowered. If a porous protective layer is also formed on the side corners of the heater substrate where element cracking is likely to occur as described above, it is considered that water cracking is particularly likely to occur when the side corners are covered with water.

On the other hand, it was found that the one without the porous protective layer was excellent in water resistance. In the absence of a porous protective layer, the water droplets adhering to the sensor element surface are almost free from spreading on the element surface due to the Leidenfrost phenomenon. Compared with the case where there is a protective layer, it can be suppressed to a very small size, and as a result, it is considered that a gas sensor element in which cracks are unlikely to occur when water droplets adhere thereto is considered.
The Leidenfrost phenomenon is a phenomenon in which when a water droplet comes into contact with the high temperature portion of the surface of the gas sensor element, the surface of the water droplet instantly evaporates and the evaporated water vapor layer acts as a heat insulating layer between the element surface and the water droplet. .

On the other hand, in order to prevent water cracking, a gas protective element having a porous protective layer formed all around is disclosed (Patent Document 1). However, as described above, since the porous protective layer has a water retention effect, the formation of the porous protective layer at the side corners of the heater substrate tends to cause water cracking.
Further, if the thickness of the porous protective layer is increased, the attached water droplets can be dispersed in the surface direction so that the water droplets do not reach the element surface, so that water cracking can be suppressed. However, in this case, the heat capacity of the gas sensor element is increased, and the rapid thermal performance is reduced. This hinders early activation of the gas sensor element, and there is a problem that it is difficult to accurately detect the gas concentration when the engine is started.

JP 2003-322632 A

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a method for manufacturing a gas sensor element that prevents water cracking and ensures early activation.

A first reference invention includes an oxygen ion conductive solid electrolyte body, a measured gas side electrode provided on one surface of the solid electrolyte body, and a reference gas side electrode formed on the other surface of the solid electrolyte body And a heater portion laminated on the solid electrolyte body. The heater portion is formed by forming a heating element that generates heat upon energization on the heater substrate, and the heater substrate is laminated on the solid electrolyte body. And a porous protective layer formed on the surface so as to cover at least a region exposed to the gas to be measured among the gas introduction port for introducing the gas to be measured to the gas to be measured side electrode, A gas sensor in which a protective layer non-forming portion that does not form a porous protective layer is disposed in at least a part of a side portion of the heating element that is a side portion of the heater substrate in a region corresponding to the axial length of the heating element. Those who manufacture elements There is,
The porous protective layer is formed on the entire surface of the region exposed to the gas to be measured among at least the length region where the gas inlet is formed in the gas sensor element,
Then, by polishing removing at least a portion of the porous protective layer formed on the heat generating side corner portion, Ru manufacturing method near the gas sensor element characterized by providing the protective layer-free portion.

Next, the effect of the first reference invention will be described.
In the gas sensor element manufacturing method, as described above, a porous protective layer is formed on the entire surface of the area exposed to the gas to be measured among at least the length of the gas sensor element where the gas inlet is formed. Then, at least a part of the porous protective layer formed on the side portion of the heating element is polished and removed.
Thereby, while being able to form a porous protective layer easily so that the said gas inlet may be covered reliably, the said protective layer non-formation part can be provided easily and reliably in the said heat generating body side corner part.

As described above, since the porous protective layer can be easily formed so as to reliably cover the gas inlet, the gas sensor element obtained by the present manufacturing method removes poisonous substances contained in the measured gas. Thus, poisoning of the measured gas side electrode can be prevented.
Further, as described above, the protective layer non-forming portion that does not form the porous protective layer can be reliably provided in at least a part of the side portion of the heating element side, so that the resulting gas sensor element is effectively cracked. Can be suppressed.

That is, the mechanism of the effect of suppressing water cracking can be considered as follows.
As described above, the heating element side corner portion is a portion where thermal stress is particularly likely to be concentrated when exposed to water, and in the gas sensor element obtained by the first reference invention , the thermal stress is likely to be concentrated on the portion. A “protective layer non-forming portion”, which is a portion where the porous protective layer is not formed, is provided.

  The protective layer non-forming portion does not have water retention, and even if water droplets adhere to the protective layer non-forming portion, the water droplets instantaneously leave the surface of the element due to the Leidenfrost phenomenon described above, and Temperature drop can be suppressed. Therefore, water cracking can be effectively prevented by disposing the protective layer non-forming portion in the side portion of the heating element.

  In the gas sensor element, the porous protective layer is not provided on the entire circumference, and it is not particularly necessary to increase the thickness of the porous protective layer. Therefore, the heat capacity of the gas sensor element can be kept small, and quick heat performance can be ensured. Thereby, the early activation of a gas sensor element is securable.

As described above, according to the first reference invention , it is possible to provide a method for manufacturing a gas sensor element that prevents water cracking and ensures early activity.

The second reference invention includes an oxygen ion conductive solid electrolyte body, a measured gas side electrode provided on one surface of the solid electrolyte body, and a reference gas side electrode formed on the other surface of the solid electrolyte body. And a heater portion laminated on the solid electrolyte body. The heater portion is formed by forming a heating element that generates heat upon energization on the heater substrate, and the heater substrate is laminated on the solid electrolyte body. And a porous protective layer formed on the surface so as to cover at least a region exposed to the gas to be measured among the gas introduction port for introducing the gas to be measured to the gas to be measured side electrode, A protective layer non-forming portion that does not form a porous protective layer is a surface opposite to the side where the heater portion is provided in a region corresponding to the axial length of the heating element, excluding the gas inlet. Placed on at least part of the part A method of manufacturing a gas sensor element,
The porous protective layer is formed on the entire surface of a region exposed to the gas to be measured among at least the length region where the gas inlet is formed in the gas sensor element,
Next, by polishing and removing at least part of the porous protective layer formed on the surface of the gas sensor element on the side opposite to the side where the heater portion is provided and excluding the gas inlet, Ru manufacturing method near the gas sensor element and providing a protective layer-free portion.

Next, the function and effect of the second reference invention will be described.
In the gas sensor element obtained by the above manufacturing method, a protective layer non-forming portion without a porous protective layer is disposed on the surface opposite to the side on which the heater portion is provided. Therefore, when the surface opposite to the side where the heater is provided is wetted, water droplets can be instantaneously detached from the element surface, suppressing the temperature drop on the element surface, and suppressing element cracking. Can do. In addition, since the amount of the porous protective layer formed is reduced, the heat capacity of the gas sensor element can be reduced to facilitate early activation.

As described above, according to the second reference invention , it is possible to provide a method for manufacturing a gas sensor element that prevents water cracking and ensures early activity.

The first invention includes an oxygen ion conductive solid electrolyte body, a gas side electrode to be measured provided on one surface of the solid electrolyte body, and a reference gas side electrode formed on the other surface of the solid electrolyte body. A heater part laminated on the solid electrolyte body, and the heater part is formed on a heater substrate that generates heat when energized, and the heater substrate is laminated on the solid electrolyte body, A porous protective layer is formed on the surface so as to cover at least a region exposed to the measurement gas in the gas introduction port for introducing the measurement gas to the measurement gas side electrode. A gas sensor element in which a non-protective layer forming portion that does not form a quality protective layer is disposed in at least a part of a side portion of the heating element that is a side portion of the heater substrate in a region corresponding to the axial length of the heating element. In the way of manufacturing I,
Forming a mask layer made of an organic material on at least a part of the side portion of the heating element side,
Next, the porous protective layer is formed so as to cover the mask layer on the entire surface of the region exposed to the gas to be measured among at least the length region where the gas introduction port is formed in the gas sensor element. Attach protective layer forming material for,
Next, the porous protective layer is baked by performing a heat treatment, and the mask layer is burned out to remove the porous protective layer on the mask layer, thereby providing the protective layer non-forming portion. It is in the manufacturing method of the gas sensor element characterized by ( Claim 1 ).

Next, the effects of the present invention will be described.
In the method of manufacturing the gas sensor element, as described above, the protective layer forming material is attached to the entire surface of the predetermined length region of the gas sensor element from above the mask layer formed in the side portion of the heating element. Heat treatment is performed. Thus, the porous protective layer is baked, and the mask layer is burned away to remove the porous protective layer on the mask layer, thereby providing the protective layer non-forming portion.

  Therefore, the porous protective layer can be easily formed so as to reliably cover the gas inlet, and the protective layer non-forming portion can be easily and reliably provided in the side portion of the heating element. Moreover, since the porous protective layer can be baked and the mask layer can be burned out in one step, the production efficiency can be improved.

As described above, since the porous protective layer can be easily formed so as to reliably cover the gas inlet, the gas sensor element obtained by the present manufacturing method removes poisonous substances contained in the measured gas. Thus, poisoning of the measured gas side electrode can be prevented.
Further, as described above, the protective layer non-forming portion that does not form the porous protective layer can be reliably provided in at least a part of the side portion of the heating element side, so that the resulting gas sensor element is effectively cracked. Can be suppressed.

  As described above, according to the present invention, it is possible to provide a method for manufacturing a gas sensor element that prevents water cracking and ensures early activity.

The second invention includes an oxygen ion conductive solid electrolyte body, a gas side electrode to be measured provided on one surface of the solid electrolyte body, and a reference gas side electrode formed on the other surface of the solid electrolyte body. A heater part laminated on the solid electrolyte body, and the heater part is formed on a heater substrate that generates heat when energized, and the heater substrate is laminated on the solid electrolyte body, A porous protective layer is formed on the surface so as to cover at least a region exposed to the measurement gas in the gas introduction port for introducing the measurement gas to the measurement gas side electrode. A portion where the protective layer non-forming portion that does not form a quality protective layer is a surface on the opposite side of the heater portion in the region corresponding to the axial length of the heating element, excluding the gas inlet That is placed on at least a part of A method of manufacturing a sensor element,
A mask layer made of an organic material is formed on at least a part of the surface on the side opposite to the side where the heater is provided and excluding the gas inlet,
Next, the porous protective layer is formed so as to cover the mask layer on the entire surface of the region exposed to the gas to be measured among at least the length region where the gas introduction port is formed in the gas sensor element. Attach protective layer forming material for,
Next, the porous protective layer is baked by performing a heat treatment, and the mask layer is burned out to remove the porous protective layer on the mask layer, thereby providing the protective layer non-forming portion. It is in the manufacturing method of the gas sensor element characterized by ( Claim 2 ).

In the present invention, similarly to the second reference invention , a protective layer non-forming portion without a porous protective layer is disposed on the surface opposite to the side where the heater portion is provided. Therefore, when the surface opposite to the side where the heater is provided is wetted, water droplets can be instantaneously detached from the element surface, suppressing the temperature drop on the element surface, and suppressing element cracking. Can do. In addition, since the amount of the porous protective layer formed is reduced, the heat capacity of the gas sensor element can be reduced to facilitate early activation.

  As described above, according to the present invention, it is possible to provide a method for manufacturing a gas sensor element that prevents water cracking and ensures early activity.

According to a third aspect of the present invention, there is provided an oxygen ion conductive solid electrolyte body, a measured gas side electrode provided on one surface of the solid electrolyte body, and a reference gas side electrode formed on the other surface of the solid electrolyte body. A heater part laminated on the solid electrolyte body, and the heater part is formed on a heater substrate that generates heat when energized, and the heater substrate is laminated on the solid electrolyte body, A porous protective layer is formed on the surface so as to cover at least a region exposed to the measurement gas in the gas introduction port for introducing the measurement gas to the measurement gas side electrode. A gas sensor element in which a non-protective layer forming portion that does not form a quality protective layer is disposed in at least a part of a side portion of the heating element that is a side portion of the heater substrate in a region corresponding to the axial length of the heating element. In the way of manufacturing I,
The protective layer forming material for forming the porous protective layer covers at least a part of the gas introduction port exposed to the gas to be measured and leaves at least a part of the side portion of the heating element side of the gas sensor element. Adhere to the surface,
Next, the method for producing a gas sensor element is characterized in that the protective layer forming material is heat-treated to form the porous protective layer ( Claim 7 ).

Next, the effects of the present invention will be described.
In the method of manufacturing the gas sensor element, as described above, the protective layer forming material is attached to the surface of the gas sensor element so as to cover the gas inlet and leave at least part of the side portion of the heating element side, The porous layer is formed by firing the protective layer forming material.

Therefore, the porous protective layer can be easily formed so as to reliably cover the gas inlet, and the protective layer non-forming portion can be easily and reliably provided in the side portion of the heating element.
As described above, since the porous protective layer can be easily formed so as to reliably cover the gas inlet, the gas sensor element obtained by the present manufacturing method removes poisonous substances contained in the measured gas. Thus, poisoning of the measured gas side electrode can be prevented.
Further, as described above, the protective layer non-forming portion that does not form the porous protective layer can be reliably provided in at least a part of the side portion of the heating element side, so that the resulting gas sensor element is effectively cracked. Can be suppressed.

  As described above, according to the present invention, it is possible to provide a method for manufacturing a gas sensor element that prevents water cracking and ensures early activity.

According to a fourth aspect of the present invention, there is provided an oxygen ion conductive solid electrolyte body, a measured gas side electrode provided on one surface of the solid electrolyte body, and a reference gas side electrode formed on the other surface of the solid electrolyte body. A heater part laminated on the solid electrolyte body, and the heater part is formed on a heater substrate that generates heat when energized, and the heater substrate is laminated on the solid electrolyte body, A porous protective layer is formed on the surface so as to cover at least a region exposed to the measurement gas in the gas introduction port for introducing the measurement gas to the measurement gas side electrode. A portion where the protective layer non-forming portion that does not form a quality protective layer is a surface on the opposite side of the heater portion in the region corresponding to the axial length of the heating element, excluding the gas inlet That is placed on at least a part of A method of manufacturing a sensor element,
The protective layer forming material for forming the porous protective layer covers at least a region of the gas inlet that is exposed to the gas to be measured, and is a surface opposite to the side on which the heater portion is provided, and Adhering to the surface of the gas sensor element so as to leave at least part of the portion excluding the gas inlet,
Next, the method for producing a gas sensor element is characterized in that the protective layer forming material is heat-treated to form the porous protective layer ( claim 8 ).

In the present invention, similarly to the second reference invention , a protective layer non-forming portion without a porous protective layer is disposed on the surface opposite to the side where the heater portion is provided. Therefore, when the surface opposite to the side where the heater is provided is wetted, water droplets can be instantaneously detached from the element surface, suppressing the temperature drop on the element surface, and suppressing element cracking. Can do. In addition, since the amount of the porous protective layer formed is reduced, the heat capacity of the gas sensor element can be reduced to facilitate early activation.

  As described above, according to the present invention, it is possible to provide a method for manufacturing a gas sensor element that prevents water cracking and ensures early activity.

  In the present invention, the side corner portion of the heater substrate is a corner portion of a side end portion of a surface of the heater substrate opposite to the solid electrolyte body, and is also a side corner portion of the gas sensor element. In some cases, a chamfered portion is formed in the side corner portion, and the chamfered portion is also included in the side corner portion.

In addition, as the gas sensor element, for example, an A / F sensor element that is installed in an exhaust pipe of an internal combustion engine for various vehicles such as an automobile engine and detects an oxygen concentration in the exhaust gas for use in an exhaust gas feedback system. And an O ₂ sensor element, or a NOx sensor element for detecting a NOx concentration used for detecting deterioration of a three-way catalyst installed in an exhaust pipe.
In the present specification, the “front end side” refers to the side of the gas sensor element that is inserted into the exhaust pipe or the like, and the opposite side is referred to as the “base end side”.

  The porous protective layer is preferably not formed as much as possible on the surface of the gas sensor element other than the gas inlet. This is because if the porous protective layer is formed in a large amount, the probability of water cracking increases, and the early activation of the gas sensor element is hindered. Therefore, ideally, the porous protective layer is preferably provided only at the gas inlet.

The protective layer non-formation part is preferably provided on the entire side of the heating element that is the side corner of the heater substrate in a region corresponding to the axial length of the heating element.
In this case, water cracking can be prevented more reliably. That is, basically, in the region corresponding to the axial length of the heating element, the heating element side corner portion, which is the side corner portion of the heater substrate , is likely to cause thermal stress due to water and easily generate cracks. By arranging the protective layer non-forming part over the entire part, water cracking can be prevented more reliably.

In the first invention ( Invention 1 ) and the third invention ( Invention 7 ), as the protective layer forming material, for example, a slurry or paste can be used.

Next, in the second reference invention , the porous protective layer is formed on the entire surface of the region exposed to the gas to be measured in at least the length region where the gas inlet is formed in the gas sensor element. Then, by polishing and removing at least a part of the porous protective layer formed in the side portion of the heating element that is the side portion of the heater substrate, the protective layer non-forming portion is also formed in the side portion of the heating element. it is not preferable to provide.
In this case, both the operational effects of the second reference invention and the operational effects of the first reference invention can be obtained. Therefore, it is possible to provide a method of manufacturing a gas sensor element that ensures further prevention of water cracking and early activation.

Then, in the first or second reference invention, the porous abrasive removal of the protective layer is not preferable to perform the elastic polishing tool which contains abrasive grains in the elastic foam.
In this case, polishing removal of the porous protective layer can be performed easily and reliably. Further, due to the followability of the elastic polishing tool to the shape of the gas sensor element, the peripheral part of the gas sensor element can be simultaneously polished in addition to the side portion of the heating element. Therefore, the porous protective layer can be efficiently removed, and productivity can be improved.

Further, the polishing removal of the porous protective layer, Ru can also be carried out by the belt-shaped belt-shaped grinding tool with attached abrasive grains on the surface of the member.
In this case, the two heating element side corners at both ends in the width direction of the gas sensor element can be polished simultaneously. That is, since the belt-shaped polishing tool can be freely curved, the surface of the belt-shaped polishing tool can be simultaneously brought into contact with the two heating element side corners. Therefore, the two heating element side corners can be polished simultaneously, and productivity can be improved.
It is also possible to simultaneously polish a plurality of gas sensor elements. Further, by pressing the surface of the heater substrate, for example, by pressing the belt-shaped polishing tool, the porous protective layer can be simultaneously removed from the side portions of the heating element and the surface of the heater substrate. .

Next, in the second invention ( invention 2 ), the mask layer is a side angle of the heating element that is a side corner of the heater substrate in a region corresponding to the axial length of the heating element in the gas sensor element. by also forming at least a portion of the parts, it is preferable that disposing the protective layer-free portion in at least a portion of the heat generating side corner portion (claim 3).
In this case, both the operational effects of the second invention and the operational effects of the first invention can be obtained. Therefore, it is possible to provide a method of manufacturing a gas sensor element that ensures further prevention of water cracking and early activation.

Next, in the first or second invention (invention 1 or 2), the mask layer comprises a mask material adhered to a flexible pad material, at least a part of the heating element side corner , or the heater. Preferably, it is formed by transferring to at least a part of the surface on the side opposite to the side where the portion is provided and excluding the gas introduction port .
In this case, since the mask layer can be formed easily and reliably, a method for manufacturing a gas sensor element with excellent productivity can be obtained. Then, due to the flexibility of the pad material, the mask material is at least a part of the side portion of the gas sensor element on the side of the heating element , or the surface opposite to the side where the heater is provided, and excludes the gas introduction port. It can be attached to at least a part of the portion at the same time. Therefore, it is easy and efficient to protect at least a part of the side portion of the heating element side , or at least a part of the surface opposite to the side where the heater part is provided and excluding the gas inlet. A layer non-formation part can be provided.

In addition, the mask layer is a portion excluding the gas introduction port on the surface opposite to the side provided with the heater portion, or at least a part of the side portion of the heating element side with the mask material impregnated with the felt material It can also form by making it adhere to at least one part of (Claim 5).
Also in this case, since the mask layer can be formed easily and reliably, a method for manufacturing a gas sensor element with excellent productivity can be obtained. In addition, by changing the shape of the felt material in various ways, the mask layer can be easily and accurately matched to the shape of the portion where the mask layer is to be formed, that is, the portion where the protective layer non-forming portion is to be provided. Can be formed.

Further, the mask layer is preferably formed of a resin (Claim 6).
In this case, the mask layer can be easily burned out by performing heat treatment.
Moreover, as said mask layer, organic type resins, such as an acrylic type, a butyral type | system | group, a cellulose type, or an ultraviolet curable resin can be used, for example.
When an ultraviolet curable resin is used, the mask layer can be cured in a short time by irradiating ultraviolet rays after applying the mask material. Thereby, since the said protective layer forming material can be apply | coated without leaving time long after application | coating of a mask material, production efficiency can be improved.

Further, the mask layer, in the gas sensor element, the side provided with the heater unit Ru can also be a surface on the opposite side to be formed in a portion excluding the gas inlet.
In this case, a protective layer non-forming portion without a porous protective layer is also disposed on the surface opposite to the side where the heater portion is provided. Therefore, even when the surface on the side opposite to the side on which the heater portion is provided gets wet, element cracking can be further suppressed. Moreover, early activation can be facilitated by reducing the heat capacity of the gas sensor element.

Next, in the fourth aspect of the present invention (invention 8), the protective layer forming material is formed on the side of the heating element that is the side corner of the heater substrate in the region corresponding to the axial length of the heating element. By attaching to the surface of the gas sensor element so as to leave at least a part, at least a part of a side portion of the heating element that is a side corner portion of the heater substrate in a region corresponding to the axial length of the heating element. In addition, it is preferable to dispose the protective layer non-forming portion (claim 9).
In this case, the operational effects of both the operational effects of the fourth invention and the operational effects of the third invention can be obtained. Therefore, it is possible to provide a method of manufacturing a gas sensor element that ensures further prevention of water cracking and early activation.

Next, in the third or fourth invention (invention 7 or 8 ), the protective layer forming material is preferably attached by application with a dispenser (invention 10 ).
In this case, the porous protective layer can be formed in an accurate position and an accurate size and thickness. That is, since the dispenser can precisely control the discharge amount, it is possible to accurately control the shape, area, and coating thickness of the coating part. Further, by controlling the diameter of the discharge part of the dispenser and the operation of the dispenser on the element surface, it is possible to cope with a complex-shaped element surface. Further, by using a plurality of tispencers, the application area can be expanded and the productivity can be improved.

The protective layer forming material can be attached by spraying from a nozzle ( claim 11 ).
In this case, the protective layer forming material can be attached easily and reliably even when the element surface has a complicated shape, particularly when it has an uneven shape.

The protective layer forming material can be attached by screen printing ( claim 12 ).
In this case, the porous protective layer can be formed in an accurate shape, size, and position.

Further, adhesion of the protective layer forming material is preferably the protective layer forming material deposited pad material having flexibility performed than be transferred to the surface of the gas sensor element (claim 13).
In this case, even if the element surface has a complicated shape, the pad material can follow the shape, so that it can be formed in an accurate shape, size, and position.

( Reference Example 1 )
The manufacturing method of the gas sensor element concerning a reference example is demonstrated using FIGS.
As shown in FIG. 1, the gas sensor element 1 obtained by the manufacturing method of this example includes an oxygen ion conductive solid electrolyte body 2, a measured gas side electrode 21 provided on one surface of the solid electrolyte body 2, and A reference gas side electrode 22 formed on the other surface of the solid electrolyte body 2 and a heater unit 3 laminated on the solid electrolyte body 2 are provided.

The heater section 3 is formed by forming a heating element 31 that generates heat upon energization on a heater substrate 32, and the heater substrate 32 is laminated on the solid electrolyte body 2.
As shown in FIGS. 1, 2, 4, and 5, the gas sensor element 1 includes at least a region exposed to the measurement gas in the gas introduction port 11 that introduces the measurement gas to the measurement gas side electrode 21. The surface has a porous protective layer 4 formed so as to cover it.
Further, as shown in FIGS. 1 to 3 and FIG. 5, the protective layer non-forming portion 5 that does not form the porous protective layer 4 is arranged in the lateral direction of the heater substrate 32 in the region corresponding to the axial length of the heating element 31. It is arranged at least at a part of the heating element side corner portion 33 which is a portion.

  In manufacturing the gas sensor element 1, first, as shown in FIG. 6, at least the entire surface of the area exposed to the gas to be measured in the length area where the gas inlet 11 is formed in the gas sensor element 1, The porous protective layer 4 is formed. The gas sensor element 1 is used in a state where a part of the gas sensor element 1 is inserted into an insulator (see reference numeral 13 in FIG. 14) and sealed with a sealing material. This region is the “region exposed to the gas to be measured”.

  Next, as shown in FIG. 7 to FIG. 9, at least a part of the porous protective layer 4 formed in the heating element side corner portion 33 is polished and removed, so that the protective layer non-forming portion is shown in FIG. 1. 5 is provided.

Specifically, for example, as shown in FIG. 7, by attaching the water-resistant paper 72 to the rotating polishing jig 71, and pressing the water-resistant paper 72 against the heating element side corner portion 33 of the heater unit 3, The porous protective layer 4 is removed. When the surface 320 of the heater substrate 32 or the side surface 100 of the gas sensor element 1 is polished, the angle of the polishing jig 71 is changed. For example, # 200 can be used as the count of the water-resistant paper 72, but it can be arbitrarily selected.
The porous protective layer 4 is removed by polishing after slurry dipping and drying, so that there is little uncut residue, the durability of the water-resistant paper is good, the workability and the productivity are good, but the porous protective layer 4 may be removed by polishing after firing.

Further, the polishing removal of the porous protective layer 4 can also be performed by an elastic polishing tool 73 in which abrasive grains are contained in an elastic foam as shown in FIG. That is, by fixing the elastic polishing tool 73 on the surface of the rotating polishing jig 71 in the same manner as described above, and pressing the elastic polishing tool 73 against the heating element side corner portion 33 of the gas sensor element 1, the porous protective layer 4. Is removed by polishing.
As the elastic polishing tool 73, it is preferable to use a tool having a structure in which aluminum oxide abrasive grains are applied to a special sponge and having both polishing power and flexibility. The polishing power can be adjusted by the grain size of the abrasive grains and the hardness of the sponge material. For example, SF (# 320 to # 600) manufactured by Sumitomo 3M can be used as the elastic polishing tool 73.

  Moreover, the polishing removal of the porous protective layer 4 can also be performed by a belt-shaped polishing tool 74 in which abrasive grains are attached to the surface of the belt-shaped member, as shown in FIG. In this case, by simultaneously bringing the surface of the belt-shaped polishing tool into contact with the two heating element side corners 33 at both ends in the width direction of the gas sensor element 1, the two heating element side corners are simultaneously polished. To do.

  As shown in FIGS. 1, 2, and 5, the gas sensor element 1 obtained in this way has a protective layer non-forming portion 5 that does not form the porous protective layer 4 disposed on the entire heating element side corner portion 33. ing. And it arrange | positions not only to the whole heat generating body side corner part 33 but to the whole side corner part 330 of the heater board | substrate 32 in the area | region exposed to to-be-measured gas. Further, as shown in FIG. 2, the protective layer non-forming portion 5 is also disposed at the tip corner portion 34 of the heater substrate 32 at the tip portion of the gas sensor element 1. These protective layer non-forming portions 5 are also provided by polishing and removing the porous protective layer 4 by the above polishing removal method.

The gas sensor element 1 of the present example obtained by the above manufacturing method is installed in an exhaust pipe of an internal combustion engine for various vehicles such as an automobile engine, and detects oxygen concentration in exhaust gas for use in an exhaust gas feedback system. / F sensor element or O ₂ sensor element.
As shown in FIG. 1, the gas sensor element 1 has a chamber forming layer 121 interposed between the solid electrolyte body 2 and the heater portion 3, and the chamber forming layer 121 and the solid electrolyte body 2 are interposed between the chamber forming layer 121 and the solid electrolyte body 2. A chamber 122 for introducing outside air serving as a reference gas is formed. The reference gas side electrode 22 faces the chamber 122.
Further, the side corner portion 330 of the heater substrate 32 has a chamfered portion.

In addition, a porous diffusion resistance layer 124 is laminated on the side where the measured gas side electrode 21 is provided in the solid electrolyte body 2 via a spacer layer 123. A dense shielding layer 125 is laminated on the diffusion resistance layer 124. Further, a measured gas chamber 126 for introducing a measured gas is formed between the solid electrolyte body 2 and the diffusion resistance layer 124, and the measured gas side electrode 21 faces the measured gas chamber 126. is doing.
The portion of the side end face of the diffusion resistance layer 124 that is exposed to the gas to be measured becomes the gas inlet 11. And the corner | angular part of the gas sensor element 1 in the periphery of this gas inlet 11 is formed in the taper shape.

As shown in FIG. 3, the heater unit 3 is provided with a heater pattern 310 in the heater substrate 32 or on the bonding surface with the chamber forming layer 121. The heater pattern 310 is formed in a meandering state near the tip of the heater substrate 32, and this portion becomes the heating element 31. The heater pattern 310 is connected to a heater terminal 311 provided at the proximal end portion of the heater substrate 32.
The solid electrolyte body 2 has zirconia (ZrO ₂ ) as a main component, and the other layers have alumina (Al ₂ O ₃ ) as a main component.

  Further, the diffusion resistance layer 124 and the shielding layer 125 are formed in the vicinity of the distal end portion of the gas sensor element 1, that is, around the detection portion of the gas sensor element 1, and are not provided on the proximal end side. The porous protective layer 4 is provided in the vicinity of the detection portion of the gas sensor element 1. Further, this part is a part exposed to the gas to be measured.

  As shown in FIGS. 1 and 2, the porous protective layer 4 is formed in a region excluding the side corner portion 330 and the tip corner portion 34 of the heater substrate 32 and their peripheral portions in the region exposed to the gas to be measured. ing. That is, the protective layer non-forming portion 5 is disposed only in the side corner portion 330, the tip corner portion 34, and their peripheral portions in the region exposed to the gas to be measured. Conversely, the porous protective layer 4 is also formed on the side surface 100 of the gas sensor element 1, the surface 129 of the shielding layer 125, and the surface 320 of the heater substrate 32 in addition to the gas inlet 11.

Specifically, the region where the protective layer non-forming portion 5 is arranged is as follows.
That is, as shown in FIG. 1, the stacking direction distance from the heating element side corner portion 33 (the end portion on the side surface side of the chamfered portion) to the end portion of the protective layer non-forming portion 5 on the side surface 100 of the gas sensor element 1 is a. When the distance in the stacking direction from the body side corner portion 33 to the surface of the gas sensor element 1 opposite to the heater portion 31 (the surface 129 of the shielding layer 125) is b, a / b is 0.05 or more.

  Further, the distance in the width direction from the heating element side corner 33 to the end of the protective layer non-forming part 5 on the surface of the gas sensor element 1 on the heater part 3 side (the surface 320 of the heater substrate 32) is c, and the heater of the gas sensor element 1 When the width of the surface 320 on the part 3 side is d, c / d is 0.02 or more.

The porous protective layer 4 may be formed in multiple layers. In this example, as shown in FIG. 1, two porous protective layers 4 are formed, a first protective layer 41 close to the surface of the gas sensor element 1 and a second protective layer 42 far from the surface of the gas sensor element 1. And have. The second protective layer 42 has a larger particle size than the first protective layer 41.
The porous protective layer 4 is mainly composed of γ-alumina or θ-alumina, and the first protective layer 41 of the porous protective layer 4 carries a catalyst made of metal or metal oxide. Become. Here, as the metal catalyst, for example, Pt, Rh, Ru, Pd or the like can be used, and as the metal oxide catalyst, for example, titania (TiO ₂ ) or the like can be used.

Next, the effects of the present invention will be described.
In the gas sensor element manufacturing method, as described above, the porous protective layer 4 is formed on the entire surface of the area exposed to the gas to be measured in at least the length area where the gas inlet 11 is formed in the gas sensor element 1. Then, at least a part of the porous protective layer 4 formed on the heating element side corner portion 33 is polished and removed.
Accordingly, the porous protective layer 4 can be easily formed so as to reliably cover the gas inlet port 11, and the protective layer non-forming portion 5 is easily and reliably provided in the heating element side corner portion 33. Can do.

As described above, since the porous protective layer 4 can be easily formed so as to reliably cover the gas inlet port 11, the gas sensor element 1 obtained by the present manufacturing method has the target contained in the gas to be measured. It is possible to prevent poisoning of the measured gas side electrode 21 by removing the poisonous substance.
Further, as described above, the protective layer non-forming portion 5 that does not form the porous protective layer 4 can be reliably provided in at least a part of the heating element side corner portion 33. Can be effectively suppressed.

That is, the mechanism of the effect of suppressing water cracking can be considered as follows.
As described above, the heating element side corner portion 33 is a portion where thermal stress is particularly likely to be concentrated when it is exposed to water, and in the gas sensor element 1 obtained according to the present invention, the portion where thermal stress is likely to concentrate is porous. A “protective layer non-forming portion 5”, which is a portion where the quality protective layer 4 is not formed, is provided.

  The protective layer non-forming portion 5 does not have water retention, and even if water droplets adhere to the protective layer non-forming portion 5, the water droplets instantaneously leave the element surface due to the above-mentioned Leidenfrost phenomenon, The temperature drop of the part can be suppressed. Therefore, by arranging the protective layer non-forming portion 5 in the heating element side corner portion 33, water cracking can be effectively prevented.

  In the gas sensor element 1, the porous protective layer 4 is not provided on the entire circumference, and it is not particularly necessary to increase the thickness of the porous protective layer 4. Therefore, the heat capacity of the gas sensor element 1 can be kept small, and quick heat performance can be ensured. Thereby, the early activation of the gas sensor element 1 can be ensured.

  Further, as shown in FIG. 8, the removal and removal of the porous protective layer 4 can be easily and reliably performed by removing the porous protective layer 4 with an elastic polishing tool 73 containing abrasive particles in an elastic foam. Can be done. Further, due to the followability of the elastic polishing tool 73 to the shape of the gas sensor element 1, in addition to the heating element side corner portion 33 in the gas sensor element 1, the peripheral portion thereof can be simultaneously polished. Therefore, the porous protective layer 4 can be efficiently removed, and productivity can be improved.

Further, as shown in FIG. 9, by removing the porous protective layer 4 by polishing with the belt-shaped polishing tool 74, the two heating element side corners 33 at both ends in the width direction of the gas sensor element 1 are obtained. It can be polished at the same time. That is, since the belt-like polishing tool 74 can be freely curved, the surface of the belt-like polishing tool 74 can be simultaneously brought into contact with the two heating element side corners 33. Therefore, the two heating element side corners 33 can be polished simultaneously, and productivity can be improved.
Moreover, it is also possible to perform the grinding | polishing process of the several gas sensor element 1 simultaneously.

  As described above, according to this example, it is possible to provide a method for manufacturing a gas sensor element that prevents water cracking and ensures early activity.

( Example 1 )
In this example, as shown in FIGS. 10 to 19, a mask layer 61 is formed on a part of the surface of the gas sensor element 1, and then the entire surface in a predetermined region of the gas sensor element 1 is porous from above the mask layer 61. It is an example of the manufacturing method of the gas sensor element 1 in which the protective layer 4 is formed, and then the mask layer 61 is burned away to provide the protective layer non-forming portion 5.

That is, first, as shown in FIG. 11, a mask layer 61 made of an organic material is formed on the heating element side corner portion 33 and its peripheral portion and the surface 320 of the heater substrate 32 (step S1).
Next, as shown in FIG. 12, in the gas sensor element 1, at least the length of the region where the gas introduction port 11 is formed, the entire surface of the region exposed to the gas to be measured is covered with the porous layer so as to cover the mask layer 61. A protective layer forming material 40 (slurry) for forming the quality protective layer 4 is adhered (steps S2 to S5).
Next, by performing heat treatment, as shown in FIG. 13, the porous protective layer 4 is baked, and the mask layer 61 is burned off to remove the porous protective layer 4 on the mask layer 61, thereby protecting the protective layer. The layer non-formation part 5 is provided (steps S6 and S7).

  Specifically, an acrylic or cellulose binder is dissolved in an organic solvent to form a paste-like mask material 610 at a position where the protective layer non-forming portion 5 in the gas sensor element 1 is to be provided (a heating element side corner portion 33). Etc.), by applying and drying by a pad transfer method, a mask layer 61 is formed as shown in FIG. 11 (step S1).

  As shown in FIGS. 14 to 19, the mask layer 61 is formed by transferring a mask material 610 attached to a flexible rubber pad material 62 to the heating element side corner portion 33 or the like. Then, it dries as needed.

Next, the gas sensor element 1 is dipped into the slurry for forming the first protective layer 41 of the porous protective layer 4 and pulled up, so that the gas sensor element 1 has the entire circumference in a predetermined length region. The slurry for 1 protective layer is apply | coated (step S2), and this is dried (step S3).
Next, the slurry for forming the second protective layer 42 is applied by applying the slurry for the second protective layer on the first protective layer 41 by dipping (immersing) the gas sensor element 1 and pulling it up (step). S4), this is dried (step S5).

Next, the gas sensor element 1 provided with the porous protective layer 4 is heat-treated at about 500 to 1000 ° C. Thereby, the mask layer 61 made of a resin film is thermally decomposed and removed (step S6). The porous protective layer 4 adhered on the mask layer 61 at the time of dipping can have almost no adhesion strength with the gas sensor element 1 and can be easily removed by air blowing, vibration or the like (step S7). . As described above, the porous protective layer 4 can be accurately formed in a desired portion (FIG. 13).
Further, as the mask layer 61 (mask material 610), a paste containing an ultraviolet curable resin can also be used. In this case, when the mask layer 61 is formed, the mask layer 610 is cured by pad-transferring the mask material 610 onto a predetermined surface of the gas sensor element 1 and then irradiating ultraviolet rays.

  Further, as the mask material 610, for example, an acrylic resin or terpineol as a main component, a slight dispersant, a viscosity stabilizer, and a dye added to ensure the visibility of the coated portion can be used. . As a result, it is possible to facilitate visual inspection of the coating shape or inspection of the coating portion by image recognition using a camera or the like.

Further, a pad transfer method of the mask material 610 will be described with reference to FIGS.
That is, for the pad transfer, an intaglio 63 provided with a recess 631 having a size, shape and depth corresponding to the mask layer 61 to be obtained, and a ring blade 641 sliding on the upper surface of the intaglio 63 are provided. An ink pot 64 and a pad material 62 are used.
First, as shown in FIG. 14, the concave portion 631 of the intaglio 63 is disposed below the ink pot 64 filled with the mask material 610. As a result, the mask material 610 is filled in the recess 631. In addition, let the position of the intaglio 63 at this time be an origin.

Next, as shown in FIG. 15, by moving the intaglio 63 horizontally, the recess 631 is shifted from below the ink pot 64 and moved below the pad material 62. As a result, the concave portion 631 is filled with a predetermined amount of the mask material 610.
Next, as shown in FIG. 16, the pad material 62 is lowered and brought into close contact with the intaglio 63, and then lifted to transfer the mask material 610 of the recess 631 to the pad material 62.
Next, as shown in FIG. 17, the intaglio 63 is returned to the origin.

Next, as shown in FIG. 18, the mask material 610 is transferred to the gas sensor element 1 by bringing the pad material 62 to which the mask material 610 is adhered into close contact with the gas sensor element 1.
Next, as shown in FIG. 19, the pad material 62 is cleaned with the cleaning tape 65 to remove the residue of the mask material 610.
Then, the same pad transfer process as described above is sequentially performed on the plurality of gas sensor elements 1.
As shown in FIGS. 14 to 18, the mask layer 61 is formed in a state where the gas sensor element 1 is inserted and fixed to the insulator 13.

As shown in FIG. 13, the gas sensor element 1 obtained by the manufacturing method of this example is provided at the gas inlet 11, the surface 129 and corners of the shielding layer 125, and the side surface 100 of the gas sensor element 1. In addition, the protective layer non-forming portion 5 is disposed on the heating element side corner portion 33 and its peripheral portion of the heater substrate 32 and the surface 320 of the heater substrate 32.
Others are the same as in Reference Example 1 .

Next, the function and effect of this example will be described.
In the gas sensor element manufacturing method of this example, as described above, the protective layer forming material 40 is applied to the entire surface of the predetermined length region of the gas sensor element 1 from above the mask layer 61 formed in the heating element side corner portion 33. Then, heat treatment is performed. Thus, the porous protective layer 4 is baked, the mask layer 61 is burned off, the porous protective layer 4 on the mask layer 61 is removed, and the protective layer non-forming portion 5 is provided.

  Therefore, the porous protective layer 4 can be easily formed so as to reliably cover the gas inlet 11, and the protective layer non-forming portion 5 is easily and reliably provided in the heating element side corner portion 33. Can do. Moreover, since the porous protective layer 4 and the mask layer 61 can be burned in one step (step S6 in FIG. 6), the production efficiency can be improved.

  The mask layer 61 is formed by transferring the mask material 610 attached to the flexible pad material 62 to the heating element side corner portion 33. Thereby, since the mask layer 61 can be formed easily and reliably, the manufacturing method of the gas sensor element excellent in productivity can be obtained. Then, due to the flexibility of the pad material 62, the mask material 61 can be simultaneously attached to the peripheral portion of the heating element side corner portion 33 of the gas sensor element 1. Therefore, the protective layer non-forming portion 5 can be easily and efficiently provided in the peripheral portion of the heating element side corner portion 61.

Further, since the mask layer 61 is made of an ultraviolet curable resin, the mask layer 61 can be cured in a short time by irradiating ultraviolet rays after the mask material 610 is applied. Thereby, since the protective layer forming material 40 can be applied without much time after the mask material 610 is applied, the production efficiency can be improved.
In addition, the same effects as those of Reference Example 1 are obtained.

( Example 2 )
In this example, as shown in FIGS. 20 to 22, the mask layer 61 is formed by adhering the mask material 610 impregnated in the felt material 65 to the heating element side corner portion 33 to form the mask layer 61. is there.
That is, as shown in FIG. 20, the porous felt material 65 held inside the nozzle tube 650 is impregnated with a paste-like mask material 610 containing a resin. And the front-end | tip part 653 of the felt material 65 exposed from the front-end | tip of the nozzle pipe | tube 650 is moved, contacting the predetermined area | region in the surface of the gas sensor element 1, such as the heat generating body side corner | angular part 33. Thereby, the mask material 610 is applied to the surface of the gas sensor element 1 by utilizing capillary action. That is, the mask layer 61 can be applied and formed in the same manner as when marking with a so-called felt pen.
In this example, a mask layer 610 is formed by applying a mask material 610 to the heating element side corner portion 33 and its periphery and the surface 320 of the heater substrate 32.

  As shown in FIGS. 21 and 22, the felt material 65 is a string-like body, and the base end portion 654 thereof is disposed in the tank 651. A mask material 610 is stored in the tank 651, and a pressurizing / depressurizing device 652 for adjusting the pressure in the tank 651 is connected. The supply amount of the mask material 610 to the felt material 65 is adjusted by the pressurization / decompression by the pressurization / decompression device 652. In other words, depending on the viscosity of the mask material 610, application using capillary action is performed, and pressure and pressure are reduced so as not to cause bleeding or blurring to unnecessary portions while controlling the ejection amount of the ink material. Can be.

Note that the base end portion 654 of the felt material 65 does not necessarily have to protrude into the tank 651, and the felt material 65 may be inserted partway through the nozzle tube 650. Further, the shape of the felt material 65 is not limited to the illustrated cylindrical shape, and it is desirable to appropriately select it according to the shape of the surface to be applied. Further, the tip portion 653 of the felt material 65 and the surface of the gas sensor element 1 can be applied even if there is a slight gap.
Others are the same as in the first embodiment .

Also in this example, since the mask layer 61 can be formed easily and reliably, a method for manufacturing a gas sensor element excellent in productivity can be obtained. Further, by changing the shape of the felt material 65 in various ways, the mask layer can be easily formed corresponding to the shape of the portion where the mask layer 61 is to be formed, that is, the portion where the protective layer non-forming portion 5 is to be provided. It can be formed accurately.
In addition, the same effects as those of the first embodiment are obtained .

( Example 3 )
In this example, as shown in FIGS. 23 and 24, the protective layer forming material 40 for forming the porous protective layer 4 covers at least the region of the gas inlet 11 exposed to the gas to be measured and the side portion of the heating element. This is an example of a method of manufacturing a gas sensor element in which at least a part of the gas sensor element 1 is attached to the surface of the gas sensor element 1 and then the protective layer forming material 40 is heat-treated to form the porous protective layer 4.

The protective layer forming material 40 is attached by application using a dispenser 66. That is, the protective layer forming material 40 is adjusted to a paste or slurry, and is partially applied directly to the portion where the porous protective layer 40 is to be applied by the dispenser 66.
Others are the same as in Reference Example 1 .

In this case, the porous protective layer 4 can be formed in an accurate position and an accurate size and thickness. That is, since the dispenser 66 can precisely control the discharge amount, it is possible to accurately control the shape, area, and application thickness of the application part. In addition, by controlling the diameter of the discharge portion of the dispenser 66 and the operation of the dispenser 66 with respect to the element surface, it is possible to cope with the element surface having a complicated shape. In addition, as shown in FIG. 24, by using a plurality of tispencers 66, the application area can be expanded and the productivity can be improved.
In addition, the same effects as those of Reference Example 1 are obtained.

( Example 4 )
In this example, as shown in FIG. 25, the protective layer forming material 40 is attached by spraying from a nozzle 67, which is an example of a method for manufacturing a gas sensor element.
That is, the protective layer forming material 40 adjusted to a paste or slurry is partially applied by directly spraying the portion where the porous protective layer 4 is to be formed.
Others are the same as in the third embodiment .

In this case, the protective layer forming material 40 can be attached easily and reliably even when the element surface has a complicated shape, particularly when it has an uneven shape.
In addition, the same effects as those of the third embodiment are obtained .

( Example 5 )
In this example, as shown in FIG. 26, the porous protective layer 4 is formed on the surface of the gas sensor element 1 by transferring the protective layer forming material 40 adhered to the flexible pad material 68 to the surface of the gas sensor element 1. It is an example of the manufacturing method of the gas sensor element to form.
That is, using the same pad material 68 as the pad material 62 shown in the first embodiment , the protective layer forming material 40 adjusted to a paste is transferred to a predetermined surface of the gas sensor element 1.
Others are the same as in the third embodiment .

In the case of this example, even if the element surface has a complicated shape, the pad material 68 can follow the shape, so that it can be formed in an accurate shape, size, and position.
Further, the film thickness can be controlled with high accuracy by methods such as cutting out the transfer paste and adjusting the groove depth of the plate, and the porous protective layer 4 having small film thickness variation can be formed.
In addition, the same effects as those of the third embodiment are obtained .

Further, as a method similar to the fifth embodiment , there is a method (not shown) of attaching the protective layer forming material 40 to the gas sensor element 1 by screen printing. Also in this case, the porous protective layer can be formed in an accurate shape, size and position.

( Example 6 )
As shown in FIG. 27, this example is an example of the gas sensor element 1 in which the ratio a / b between the stacking direction distances a and b shown in Reference Example 1 (FIG. 1) is about 50%. Others are the same as in Reference Example 1 .
The side surface 100 of the gas sensor element 1 is more resistant to water than the side portion 33 of the heating element, but a portion where stress is likely to concentrate, such as a minute firing defect, may be the starting point of cracking. In such a case, if the porous protective layer is not formed on the side surface as much as possible, the probability of occurrence of cracks can be suppressed due to the Leidenfrost phenomenon. Therefore, according to this example in which a / b is increased, the crack suppression effect can be improved.
The gas sensor element 1 of this example can be manufactured by any of the methods of Reference Example 1 and Examples 1 to 5 described above.
In addition, the same effects as those of Reference Example 1 are obtained.

( Example 7 )
This example is an example of the gas sensor element 1 in which the porous protective layer 4 is composed of one layer as shown in FIG. Others are the same as in Example 1, the same effects as in Example 1.
The gas sensor element 1 of this example can also be manufactured by any of the methods of Reference Example 1 and Examples 1 to 5 described above.

( Example 8 )
This example is an example of the gas sensor element 1 in which the heating element 31 is embedded in a portion close to the chamber 122 as shown in FIG.
Further, the position close to the solid electrolyte body 2 on the side surface 100 of the gas sensor element 1 becomes high because the position of the heating element 31 is close to the solid electrolyte body 2. For this reason, the porous protective layer 4 is not formed on the side surface of the heating element 31.
Others are the same as in Reference Example 1 .

According to this example, since the heating element 31 is brought close to the solid electrolyte body 2, the activation time of the gas sensor element 1 can be shortened.
The gas sensor element 1 of this example can also be manufactured by any of the methods of Reference Example 1 and Examples 1 to 5 described above.
In addition, the same effects as those of Reference Example 1 are obtained.

( Example 9 )
This example is an example of the gas sensor element 1 in which the corners on the shielding layer 125 side and the heater unit 3 side are not chamfered as shown in FIG.
And the protective layer non-formation part 5 which does not form the porous protective layer 4 is arrange | positioned in the heat generating body side corner | angular part 33 and its peripheral part. Further, the porous protective layer 4 is not provided at the corner portion on the shielding layer 125 side. The porous protective layer 4 is provided on the other surface 129 of the shielding layer 125, the surface 320 of the heater substrate 32, and the side surface 100 of the gas sensor element 1.

Further, in this example, the regions of the protective layer non-forming portion 5 around the heating element side corner portion 33 are a / b = 0.2 (20%) and c / d = 0.1 (10%). This is an important area.
The region of the protective layer non-forming portion 5 around the side corner portion 127 on the shielding layer 125 side is as follows. That is, when the distance in the width direction from the side corner portion 127 to the end portion of the protective layer non-forming portion 5 is e and the width of the gas sensor element 1 is f, e / f is 0.05 (5%). . Further, g / b is 0.1 (10%), where g is the distance in the stacking direction from the side corner portion 127 to the end portion of the protective layer non-forming portion 5.
The gas sensor element 1 of this example can also be manufactured by any of the methods of Reference Example 1 and Examples 1 to 5 described above.
Others are the same as in Reference Example 1, it has the same effect as in Reference Example 1.

( Example 10 )
This example is an example of the gas sensor element 1 configured to allow gas diffusion rate control to function in the pinhole 142 as shown in FIG.
In the gas sensor element 1 of this example, a dense layer 141 is laminated on the measured gas chamber 126 side of the solid electrolyte body 2 via a spacer layer 123, and a pinhole 142 is formed in the dense layer 141. The pinhole 142 is covered with a porous layer 143 laminated on the dense layer 141.

As a result, the measurement gas is introduced into the measurement gas chamber 126 through the pinhole 142, and the diffusion-controlled rate of the measurement gas can be adjusted according to the size and number of the pinholes 142.
The porous protective layer 4 is provided on the surface 144 of the porous layer 143, the surface 320 of the heater substrate 32, and the side surface 100 of the gas sensor element 1. In addition, a protective layer non-forming portion 5 that does not form the porous protective layer 4 is disposed in the heat generating body side corner portion 33 and the side corner portion 145 of the porous layer 143.
The gas sensor element 1 of this example can also be manufactured by any of the methods of Reference Example 1 and Examples 1 to 5 described above.
Others are the same as in Reference Example 1, it is possible to obtain the same effects as in Reference Example 1.

The manufacturing method of the gas sensor element of the present invention is not limited to the shape shown in each of the above embodiments. For example, in the gas sensor element shown in Reference Example 1 , the heating element side corner portion 33 is not chamfered and shielded. The corner on the side of the layer 125 can be applied to a gas sensor element in a chamfered state, and the present invention can be applied to gas sensor elements having various shapes.

( Example 11 )
This example is an example of the gas sensor 1 in which the porous protective layer 4 is not formed on the surface 129 of the shielding layer 125 as shown in FIG.
That is, the porous protective layer 4 is not formed on the surface of the gas sensor element 1 on the side opposite to the side where the heater 3 is provided, excluding the gas inlet 11.

In manufacturing the gas sensor 1 of this example, the method of Reference Example 1 can be used. In this case, after forming the porous protective layer 4 on the entire surface of the region exposed to the gas to be measured among the length region where the gas introduction port 11 is formed in the gas sensor element 1, The porous protective layer 4 formed on the surface 129 of the shielding layer 125 together with the porous protective layer 4 is also polished and removed.
Alternatively, the same method as in the first embodiment can be used. In this case, the mask layer 61 is also formed on the surface 129 of the shielding layer 25 together with the heating element side corner portion 33.
Others are the same as in Reference Example 1 .

In the case of this example, the protective layer non-forming part 5 without the porous protective layer 4 is also disposed on the surface 129 opposite to the side where the heater part 3 is provided. Therefore, even when the surface 129 is flooded, water droplets can be instantaneously detached from the element surface, temperature drop on the element surface can be suppressed, and element cracking can be further suppressed. Further, since the amount of the porous protective layer 4 formed is reduced, the heat capacity of the gas sensor element 1 can be reduced to facilitate early activation.
In addition, the same effects as those of Reference Example 1 are obtained.
The porous protective layer 4 may not be formed on the surface 320 of the heater substrate 32. Alternatively, the porous protective layer 4 may be formed also on the heating element side corner portion 33 and the protective layer non-forming portion 5 may be disposed only on the surface 129.

( Example 12 )
As shown in Tables 1 to 3, this example is an example in which the effect of the gas sensor element 1 obtained by the manufacturing method of the present invention shown in the above Reference Example 1 was confirmed.
That is, a test was performed as to how much temperature drop occurs and how much cracking occurs when a water droplet is dropped on the heating element side corner 33 of the gas sensor element 1.
In the test, first, the gas sensor element 1 of Reference Example 1 in which the porous protective layer 4 was not provided in the heating element side corner portion 33 was prepared as Level 1. For comparison, the layers 2, 4, 4, and 5 having the porous protective layer 4 formed at the heating element side corners 33 in thicknesses of 5 μm, 20 μm, 50 μm, and 80 μm were prepared.

For each sample, the results of measuring the temperature drop of the heating element side corner portion 33 when 0.1 μL water droplets and 0.2 μL water droplet are dropped onto the heating element side corner portion 33 corresponding to the center of the heating element 31 are shown. It is shown in 1.
The surface temperature of the gas sensor element in the water droplet dropping part was 700 ° C. The surface temperature was measured with a thermoviewer. Further, the temperature drop ΔT due to the water droplet dropping indicates the minimum value to the maximum value of 10 pieces of measurement data for each level. The thickness of the porous protective layer is the total thickness of the two layers (the first protective layer 41 and the second protective layer 42) in the heating element side corner portion 33. The gas sensor element has a width of 4.2 mm and a thickness of 2.0 mm.

  From Table 1, when the porous protective layer 4 was not formed, the temperature drop amount ΔT was almost the same in both cases of the dropping amount of 0.1 μL and 0.2 μL, and was 30 ° C. to 80 ° C. On the other hand, when the porous protective layer is formed, the temperature drop ΔT is large. When the level 2 of 5 μm, the level 3 of 20 μm, and the level 4 of 50 μm are formed, 140 to 220 ° C. and 100 ° C., respectively. 170 ° C. and 70 to 100 ° C.

In addition, when the porous protective layer was formed to 80 μm as in level 5, the amount of temperature decrease was the same as that in the case where the porous protective layer was not formed (level 1). That is, it is possible to reduce the amount of temperature decrease by forming the porous protective layer thick. However, by increasing the thickness of the porous protective layer, the heat capacity of the gas sensor element 1 increases, the rapid thermal performance decreases, and the so-called active time from when the engine is started until sensor output is obtained becomes longer. As emission regulations become stricter, it is essential to shorten this activation time, in particular, in order to reduce the amount of THC (total hydrocarbon) emitted when starting the engine.
Therefore, in order to prevent moisture cracking while ensuring early activity, it is necessary to employ the gas sensor element of the present invention in which a porous protective layer is not provided at the side portion of the heating element as in Level 1.

  In addition, Table 2 shows the crack occurrence rate in the gas sensor element in the above drop test. The crack occurrence rate is a value calculated by (number of crack occurrences / 10) × 100 in 10 test results for each level.

  As can be seen from Table 2, cracks caused by dropping water droplets do not occur when a level 1 porous protective layer is not formed. The smaller the thickness of the porous protective layer, the higher the occurrence rate of cracks, almost correlating with the magnitude of the temperature drop due to the water droplet dropping shown in Table 1. When the thickness of the porous protective layer is increased to about 80 μm as in Level 5, no cracks are generated. This is presumed that the water absorption phenomenon in the surface direction of the porous protective layer occurred at the same time as the water was applied, and water droplets hardly reached the surface of the device, so that the temperature drop of the device was small and no crack was generated. However, as described above, there is a considerable delay in activation time.

Next, the relationship between the ratio a / b between the stacking direction distances a and b shown in Reference Example 1 (FIG. 1) and the crack generation rate of the gas sensor element due to the water droplet dropping was examined.
The results are shown in Table 3. The crack occurrence rate is a value obtained by a calculation method similar to that shown in Table 2 above. The physique of the gas sensor element is the same as that shown in the test method of Table 1 above. The diffusion resistance layer is formed at a position 0.75b away from the side portion of the heating element.

When a / b was 2% (0.02) or less, cracks occurred. At the same time as the Leidenfrost phenomenon, water droplets deposited on the side portions of the heating element spread, and the porous protective layer that is only slightly away from the side portions of the heating element retains a part of the water droplets, resulting in a decrease in the element surface temperature. It is thought that cracks were generated. On the other hand, with respect to those having a / b of 5% or more, since there is little or no influence of water retention of water droplets on the porous protective layer, the temperature drop of the element can be suppressed to a low level due to the Leidenfrost phenomenon, It is thought that no cracks occurred.
From this result, it is considered that water cracking can be more effectively prevented by setting a / b to 5% (0.05) or more.

Next, a ratio c / d between the width direction distance c from the heating element side corner portion 33 to the end of the protective layer non-forming portion 5 on the surface 320 of the heater substrate 32 and the width d of the surface 320, and a gas sensor by dripping water droplets The relationship with the crack occurrence rate of the element was investigated. The test method is the same as that shown in Table 3 above.
The results are shown in Table 4.

As can be seen from Table 4, cracks occurred when c / d was 1% (0.01) or less. On the other hand, when the c / d is 2% (0.02) or more, there is little or no influence of water retention of the water droplets on the porous protective layer. It can be suppressed, and it is considered that cracks did not occur.
From this result, it is considered that water cracking can be more effectively prevented by setting c / d to 2% (0.02) or more.

It is sectional drawing of the gas sensor element in the reference example 1 , Comprising: It is AA arrow sectional drawing (up-down direction is reverse) of FIG. The perspective view of the gas sensor element in the reference example 1. FIG. Plane explanatory drawing of the gas sensor element which shows the position of the heat generating body in the reference example 1. FIG. The top view of the gas sensor element in the reference example 1. FIG. The side view of the gas sensor element in the reference example 1 . Sectional drawing showing the state in which the porous protective layer was formed in the perimeter of the gas sensor element in the reference example 1. FIG. Explanatory drawing of the grinding | polishing removal method of the porous protective layer using the paper for water in the reference example 1. FIG. Explanatory drawing of the polishing removal method of the porous protective layer using the elastic polishing tool in the reference example 1. FIG. Explanatory drawing of the grinding | polishing removal method of the porous protective layer using the belt-shaped polishing tool in the reference example 1. FIG. FIG. 3 is a process flow diagram showing a method for forming a porous protective layer in Example 1 . Sectional explanatory drawing which shows the state in which the mask layer was formed in the predetermined position of the gas sensor element in Example 1. FIG. Sectional explanatory drawing which shows the state which formed the slurry of the porous protective layer in the perimeter of the gas sensor element from the mask layer in Example 1. FIG. FIG. 3 is a cross-sectional view of a gas sensor element in Example 1 . FIG. 3 is a first explanatory diagram showing a pad transfer method of a mask layer in Example 1 . FIG. 6 is a second explanatory diagram showing a pad transfer method of a mask layer in Example 1 . FIG. 4 is a third explanatory diagram showing a pad transfer method of a mask layer in Example 1 . FIG. 6 is a fourth explanatory diagram showing a pad transfer method of a mask layer in Example 1 . FIG. 10 is a fifth explanatory diagram illustrating a pad transfer method for a mask layer in the first embodiment . FIG. 6 is a sixth explanatory diagram illustrating a pad transfer method of a mask layer in the first embodiment . FIG. 10 is an explanatory diagram of a method for forming a mask layer in Example 2 . Explanatory drawing of the formation method of the mask layer in Example 2 using the tank and a pressurization / decompression apparatus. Sectional explanatory drawing of the felt material and a tank in Example 2. FIG. Explanatory drawing of the formation method of the porous protective layer which used the dispenser in Example 3. FIG. Explanatory drawing of the formation method of the porous protective layer using the some dispenser in Example 3. FIG. Explanatory drawing of the formation method of the porous protective layer using the injection nozzle in Example 4. FIG. FIG. 9 is an explanatory diagram of a method for forming a porous protective layer using pad transfer in Example 5 . Sectional drawing of the gas sensor element in Example 6. FIG. Sectional drawing of the gas sensor element in Example 7. FIG. Sectional drawing of the gas sensor element in Example 8. FIG. Sectional drawing of the gas sensor element in Example 9. FIG. Sectional drawing of the gas sensor element in Example 10. FIG. Sectional drawing of the gas sensor element in Example 11. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas sensor element 11 Gas inlet 2 Solid electrolyte body 21 Gas side electrode 22 to be measured 22 Reference gas side electrode 3 Heater part 31 Heating body 32 Heater board 33 Heating body side corner part 4 Porous protective layer 5 Protection layer non-formation part

Claims (14)

An oxygen ion conductive solid electrolyte body, a gas side electrode to be measured provided on one side of the solid electrolyte body, a reference gas side electrode formed on the other side of the solid electrolyte body, and the solid electrolyte body The heater unit is formed by forming a heating element that generates heat upon energization on the heater substrate, the heater substrate being stacked on the solid electrolyte body, and the measured gas side electrode. The porous protective layer is formed on the surface so as to cover at least a region exposed to the measured gas in the gas introduction port for introducing the measured gas into the gas, and the porous protective layer is not formed. This is a method for manufacturing a gas sensor element in which a protective layer non-forming portion is disposed at least at a part of a side portion of the heating element that is a side portion of the heater substrate in a region corresponding to the axial length of the heating element. And
Forming a mask layer made of an organic material on at least a part of the side portion of the heating element side,
Next, the porous protective layer is formed so as to cover the mask layer on the entire surface of the region exposed to the gas to be measured among at least the length region where the gas introduction port is formed in the gas sensor element. Attach protective layer forming material for,
Next, the porous protective layer is baked by performing a heat treatment, and the mask layer is burned out to remove the porous protective layer on the mask layer, thereby providing the protective layer non-forming portion. A method for manufacturing a gas sensor element. An oxygen ion conductive solid electrolyte body, a gas side electrode to be measured provided on one side of the solid electrolyte body, a reference gas side electrode formed on the other side of the solid electrolyte body, and the solid electrolyte body The heater unit is formed by forming a heating element that generates heat upon energization on the heater substrate, the heater substrate being stacked on the solid electrolyte body, and the measured gas side electrode. The porous protective layer is formed on the surface so as to cover at least a region exposed to the measured gas in the gas introduction port for introducing the measured gas into the gas, and the porous protective layer is not formed. The protective layer non-formation part is disposed on at least a part of the surface of the region corresponding to the axial length of the heating element on the side opposite to the side where the heater part is provided, excluding the gas introduction port. Gas sensor element A method of forming,
A mask layer made of an organic material is formed on at least a part of the surface on the side opposite to the side where the heater is provided and excluding the gas inlet,
Next, the porous protective layer is formed so as to cover the mask layer on the entire surface of the region exposed to the gas to be measured among at least the length region where the gas introduction port is formed in the gas sensor element. Attach protective layer forming material for,
Next, the porous protective layer is baked by performing a heat treatment, and the mask layer is burned out to remove the porous protective layer on the mask layer, thereby providing the protective layer non-forming portion. A method for manufacturing a gas sensor element.   The mask layer according to claim 2, wherein the mask layer is also formed on at least a part of a side portion of the heating element that is a side corner portion of the heater substrate in a region corresponding to an axial length of the heating element in the gas sensor element. Thus, the method for producing a gas sensor element is characterized in that the protective layer non-formed portion is also disposed at least at a part of the side portion of the heating element.   4. The mask layer according to claim 1, wherein the mask layer is a mask material attached to a flexible pad material, at least a part of the heating element side corner portion, or a side on which the heater portion is provided. A method for producing a gas sensor element, wherein the gas sensor element is formed by transferring to at least a part of a portion of the opposite surface excluding the gas inlet.   The mask layer according to any one of claims 1 to 3, wherein the mask layer has a mask material impregnated with a felt material, at least a part of the side portion of the heating element side, or a surface opposite to the side on which the heater portion is provided. A method of manufacturing a gas sensor element, wherein the gas sensor element is formed by adhering to at least a part of a portion excluding the gas inlet.   6. The method of manufacturing a gas sensor element according to claim 1, wherein the mask layer is made of a resin. An oxygen ion conductive solid electrolyte body, a gas side electrode to be measured provided on one side of the solid electrolyte body, a reference gas side electrode formed on the other side of the solid electrolyte body, and the solid electrolyte body The heater unit is formed by forming a heating element that generates heat upon energization on the heater substrate, the heater substrate being stacked on the solid electrolyte body, and the measured gas side electrode. The porous protective layer is formed on the surface so as to cover at least a region exposed to the measured gas in the gas introduction port for introducing the measured gas into the gas, and the porous protective layer is not formed. This is a method for manufacturing a gas sensor element in which a protective layer non-forming portion is disposed at least at a part of a side portion of the heating element that is a side portion of the heater substrate in a region corresponding to the axial length of the heating element. And
The protective layer forming material for forming the porous protective layer covers at least a part of the gas introduction port exposed to the gas to be measured and leaves at least a part of the side portion of the heating element side of the gas sensor element. Adhere to the surface,
Subsequently, the said protective layer forming material is heat-processed, and the said porous protective layer is formed, The manufacturing method of the gas sensor element characterized by the above-mentioned. An oxygen ion conductive solid electrolyte body, a gas side electrode to be measured provided on one side of the solid electrolyte body, a reference gas side electrode formed on the other side of the solid electrolyte body, and the solid electrolyte body The heater unit is formed by forming a heating element that generates heat upon energization on the heater substrate, the heater substrate being stacked on the solid electrolyte body, and the measured gas side electrode. The porous protective layer is formed on the surface so as to cover at least a region exposed to the measured gas in the gas introduction port for introducing the measured gas into the gas, and the porous protective layer is not formed. The protective layer non-formation part is disposed on at least a part of the surface of the region corresponding to the axial length of the heating element on the side opposite to the side where the heater part is provided, excluding the gas introduction port. Gas sensor element A method of forming,
The protective layer forming material for forming the porous protective layer covers at least a region of the gas inlet that is exposed to the gas to be measured, and is a surface opposite to the side on which the heater portion is provided, and Adhering to the surface of the gas sensor element so as to leave at least part of the portion excluding the gas inlet,
Subsequently, the said protective layer forming material is heat-processed, and the said porous protective layer is formed, The manufacturing method of the gas sensor element characterized by the above-mentioned. 9. The protective layer forming material according to claim 8, wherein the protective layer forming material leaves at least a part of a side portion of the heating element that is a side corner portion of the heater substrate in a region corresponding to an axial length of the heating element. By adhering to the surface of the gas sensor element, the protective layer non-forming portion is also formed on at least a part of the heating element side corner portion that is the side corner portion of the heater substrate in the region corresponding to the axial length of the heating element. A method for manufacturing a gas sensor element, comprising: disposing the gas sensor element.   The method for manufacturing a gas sensor element according to claim 7, wherein the protective layer forming material is attached by application using a dispenser.   The method for manufacturing a gas sensor element according to claim 7, wherein the protective layer forming material is attached by spraying from a nozzle.   The method for manufacturing a gas sensor element according to claim 7, wherein the protective layer forming material is attached by screen printing.   In any one of Claims 7-9, adhesion of the said protective layer forming material is performed by transferring the said protective layer forming material adhered to the pad material which has a softness | flexibility to the surface of the said gas sensor element. A method for manufacturing a gas sensor element. The protective layer non-forming portion according to any one of claims 1 to 13, wherein the protective layer non-forming portion is formed on the entire heating element side corner portion that is a side corner portion of the heater substrate in a region corresponding to the axial length of the heating element. A method of manufacturing a gas sensor element, comprising: providing a gas sensor element.

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