JP5472208B2 - Gas sensor element, manufacturing method thereof, and gas sensor - Google Patents

Description

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

An exhaust system such as an internal combustion engine for a vehicle is provided with a gas sensor that includes a gas sensor element that detects a specific gas concentration (for example, oxygen concentration) in a gas to be measured such as exhaust gas.
Examples of the gas sensor element include an oxygen ion conductive solid electrolyte body, a measurement gas side electrode and a reference gas side electrode provided on one surface and the other surface of the solid electrolyte body, and a gas to be measured. A porous diffusion resistance layer is known.

For example, in Patent Document 1, as shown in FIGS. 8 and 9, an intermediate layer 96 is provided between the solid electrolyte body 91 and the diffusion resistance layer 97, and the solid electrolyte body 91 is diffused inside the intermediate layer 96. A gas sensor element 9 is disclosed in which a hollow portion 969 for introducing a measurement gas to be brought into contact with the measurement gas side electrode 92 is formed between the resistance layer 97 and the resistance layer 97. In the gas sensor element 9, the intermediate layer 96 and the diffusion resistance layer 97 are bonded by an adhesive layer 99.
In FIG. 8 and FIG. 9, illustration of other portions of the gas sensor element 9 is omitted.

  In manufacturing the gas sensor element 9 having the above-described configuration, for example, as shown in FIG. 8A, the intermediate layer material 960 is provided on one surface of the solid electrolyte sheet 910 coated with the measured gas side electrode material 920. Then, the adhesive layer material 990 is applied in order, and a diffusion resistance layer sheet 970 is laminated on the surface of the adhesive layer material 990 as shown in FIG.

  Further, as shown in FIG. 9A, the intermediate layer material 960 is applied to one surface of the solid electrolyte sheet 910 coated with the measured gas side electrode material 920, and one of the diffusion resistance layer sheets 970 is applied. The adhesive layer material 990 is applied to the surface of the substrate, and as shown in FIG. 9B, the solid electrolyte sheet 910 and the diffusion resistance layer sheet 970 are laminated so that the applied surfaces face each other. A portion 969 can also be formed.

JP 2007-248219 A

  However, when the hollow portion 969 is formed by the method shown in FIG. 8, the exposed surface 991 exposed to the hollow portion 961 in the adhesive layer material 990 and the diffusion resistance layer sheet 970 are obtuse (β). Therefore, a notch 901 is formed between the two. Therefore, if stress or the like is generated when the gas sensor element 9 is used, the stress is concentrated around the notch portion 901 between the adhesive layer 99 and the diffusion resistance layer 97 (notch effect), which may cause a crack or the like. is there.

  On the other hand, when the hollow portion 969 is formed by the method as shown in FIG. 9, when the intermediate layer material 960 and the adhesive layer material 990 are bonded, a void 902 is formed at the bonding interface due to the presence of surface irregularities. Will occur. Here, the intermediate layer 96 and the adhesive layer 99 are both non-porous. For this reason, if the gas sensor element 9 is rapidly heated in a state where water has entered the void 902, the vapor generated in the void 902 loses escape, causing a large thermal stress around the void 902, leading to cracks and the like. There is a fear.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a gas sensor element that can prevent the occurrence of cracks, a manufacturing method thereof, and a gas sensor.

According to a first aspect of the present invention, there is provided an oxygen ion conductive solid electrolyte body, a measurement gas side electrode and a reference gas side electrode respectively provided on one surface and the other surface of the solid electrolyte body, and the measurement gas side A porous diffusion resistance layer that covers the electrode and allows the gas to be measured to pass through; an intermediate layer provided between the solid electrolyte body and the diffusion resistance layer; and the solid electrolyte body inside the intermediate layer And a laminated gas sensor element provided with a hollow portion for introducing a gas to be measured, formed between the diffusion resistance layer and the diffusion resistance layer,
Between the intermediate layer and the diffusion resistance layer, there is provided an adhesive layer for adhering both,
The adhesive layer includes a first adhesive portion provided on the surface of the intermediate layer on the diffusion resistance layer side and a second adhesive portion provided on the surface of the diffusion resistance layer on the intermediate layer side,
The first adhesive part has at least a part of its inner periphery joined to the second adhesive part, and an outer part thereof joined to the diffusion resistance layer,
The second adhesive portion has its inner peripheral end exposed to the hollow portion, and is formed between the exposed surface of the inner peripheral end and the surface of the diffusion resistance layer on the intermediate layer side. The gas sensor element is characterized in that the bonding angle is an acute angle in the cross section in the stacking direction.

A second invention is a method of manufacturing the gas sensor element of the first invention,
In forming the hollow portion, the intermediate layer material application step of applying the intermediate layer material on one surface of the solid electrolyte sheet,
A first adhesive portion material application step of applying a first adhesive portion material on the surface of the intermediate layer material;
A second adhesive portion material application step of applying a second adhesive portion material to one surface of the diffusion resistance layer sheet;
A laminating step of laminating the solid electrolyte body sheet and the diffusion resistance layer sheet so that the first adhesive portion material and the second adhesive portion material face each other;
In the laminating step, at least a part of the inner peripheral portion of the first adhesive portion material is bonded to the second adhesive portion material in a state where the inner peripheral end portion of the second adhesive portion material is exposed. The gas sensor element manufacturing method is characterized in that the outer portion is joined to the diffusion resistance layer sheet.

  According to a third aspect of the present invention, there is provided a gas sensor comprising the gas sensor element according to the first aspect of the present invention.

  In the gas sensor element according to the first aspect of the present invention, an adhesive layer for adhering both is provided between the intermediate layer and the diffusion resistance layer, and the adhesive layer is a first adhesive provided on the intermediate layer. Part and a second adhesive part provided on the diffusion resistance layer. The second adhesive portion has an inner peripheral end portion exposed to the hollow portion, and an adhesive formed between the exposed surface of the inner peripheral end portion and the intermediate layer side surface of the diffusion resistance layer. The corner is an acute angle in the cross section in the stacking direction.

  That is, the adhesive layer is formed so that the adhesive angle formed between the exposed surface of the adhesive layer (the inner peripheral end of the second adhesive portion) and the intermediate layer side surface of the diffusion resistance layer is an acute angle. ing. Therefore, stress can be prevented from concentrating around the portion where the exposed surface of the adhesive layer and the surface on the intermediate layer side of the diffusion resistance layer merge, compared to the case where the adhesion angle is obtuse as in the prior art. . Thereby, generation | occurrence | production of the crack etc. resulting from the stress etc. which generate | occur | produce at the time of use of a gas sensor element can be prevented.

  In the adhesive layer, the first adhesive portion has at least a part of the inner peripheral portion thereof joined to the second adhesive portion, and the outer portion thereof is joined to the diffusion resistance layer. That is, the second adhesive portion and the diffusion resistance layer are joined to the first adhesive portion. Therefore, a part of the bonding interface of the first bonding portion becomes a bonding interface with the porous diffusion resistance layer. Thereby, the void formed in the joining interface of the adhesion parts of the 1st adhesion part and the 2nd adhesion part can be reduced.

  Even if a void is formed at the bonding interface between the first adhesive portion and the diffusion resistance layer, and the gas sensor element is rapidly heated with water entering the void, the vapor generated in the void is made porous. It is possible to escape through pores existing in the diffusion resistance layer. Thereby, it can suppress that a vapor | steam lose | disappears in a void and a big thermal stress arises around a void like the past, and generation | occurrence | production of the crack of a gas sensor element, etc. can be prevented.

  In the gas sensor element manufacturing method according to the second aspect of the invention, in the second adhesive portion material applying step, the second adhesive portion material for forming the second adhesive portion of the adhesive layer is applied to the diffusion resistance layer sheet. To do. And in the said lamination process, the sheet | seat for solid electrolyte bodies and the sheet | seat for diffused resistance layers are laminated | stacked in the state which exposed the inner peripheral edge part of the material for 2nd adhesion parts. Therefore, it becomes easy to make the said adhesion angle formed between the exposed surface of the inner peripheral edge part of a 2nd adhesion part and the surface by the side of the intermediate layer of a diffused resistance layer into an acute angle.

Moreover, at the said lamination process, at least one part of the inner peripheral part of the 1st adhesion part material is joined to the 2nd adhesion part material, and the part outside it is joined to the sheet | seat for diffused resistance layers. Therefore, in the adhesive layer, a part of the bonding interface of the first bonding portion can be a bonding interface with the porous diffusion resistance layer.
Thereby, the gas sensor element of the first invention capable of preventing the occurrence of cracks and the like can be easily manufactured.

  The gas sensor of the third invention includes the gas sensor element of the first invention. That is, the gas sensor element which can prevent generation | occurrence | production of a crack etc. is incorporated. Therefore, the gas sensor is excellent in durability.

  As described above, according to the first to third aspects of the invention, it is possible to provide a gas sensor element that can prevent the occurrence of cracks, a manufacturing method thereof, and a gas sensor.

Sectional explanatory drawing which shows the structure of the gas sensor element in Example 1. FIG. FIG. 2 is a cross-sectional explanatory view taken along line AA in FIG. 1. In Example 1, (a) explanatory drawing which shows the sheet | seat for solid electrolyte bodies which apply | coated the material for intermediate | middle layers, and the material for 1st adhesion parts, (b) The sheet | seat for diffused resistance layers which apply | coated the material for 2nd adhesion parts FIG. In Example 1, (a) Explanatory drawing which shows the process of laminating | stacking the sheet | seat for fixed electrolyte bodies, and the sheet | seat for diffusion resistance layers, (b) A hollow part exists between the sheet | seat for solid electrolyte bodies, and the sheet | seat for diffusion resistance layers. Explanatory drawing which shows the formed state. Sectional explanatory drawing which shows the structure of the gas sensor in Example 1. FIG. Explanatory drawing which shows the relationship between the angle of the adhesion angle in Example 2, and the voltage which the crack generate | occur | produced. Explanatory drawing which shows the relationship between the void presence rate in Example 3, and the voltage which the crack generate | occur | produced. In the past, (a) Explanatory drawing which shows the process of forming a hollow part, (b) Explanatory drawing which shows the state which formed the hollow part. In the past, (a) Explanatory drawing which shows the process of forming a hollow part, (b) Explanatory drawing which shows the state which formed the hollow part.

  In the first invention, the gas sensor element is disposed in, for example, an exhaust system of a vehicle internal combustion engine or the like, and has a gap between electrodes depending on a specific gas concentration (oxygen concentration) in a gas to be measured (exhaust gas). An A / F sensor element for detecting the air-fuel ratio (A / F) of the air-fuel mixture supplied to the internal combustion engine based on the flowing limit current, a specific gas concentration (oxygen concentration) between the gas to be measured and the reference gas (atmosphere) It is applied to an oxygen sensor element that detects an air-fuel ratio based on an electromotive force generated between electrodes depending on the ratio.

Moreover, in the said adhesive layer, it is preferable that the joining interface of the said 1st adhesion part and the said 2nd adhesion part is as small as possible.
In this case, the bonding interface between the first adhesive portion and the porous diffusion resistance layer can be increased. Thereby, the void formed in the joining interface of the adhesion parts of the 1st adhesion part and the 2nd adhesion part can be reduced further. Moreover, the effect which prevents generation | occurrence | production of the crack with respect to the above thermal stress, etc. can be heightened.

In addition, the bonding angle formed between the exposed surface of the inner peripheral end of the second bonding portion and the intermediate layer side surface of the diffusion resistance layer is an acute angle in the cross section in the stacking direction.
For example, in the cross-section in the stacking direction, the bonding angle is obtained by drawing the tangent at the point where the curvature of the exposed surface of the inner peripheral end of the second bonding portion is maximized and the intermediate layer side of the diffusion resistance layer. The angle formed by the surface.

In the adhesive layer, the adhesive angle is preferably 80 ° or less.
In this case, it is possible to reliably prevent the occurrence of cracks or the like due to stress or the like generated when the gas sensor element is used.

The adhesion angle is more preferably 50 ° or less (claim 3).
In this case, it is possible to more reliably prevent the occurrence of cracks and the like due to the stress generated when the gas sensor element is used.

Moreover, it is preferable that the void presence rate in the joining interface of the said 1st adhesion part of the said contact bonding layer and the said diffusion resistance layer is 70% or less (Claim 4).
In this case, even if the gas sensor element is rapidly heated in a state where water has entered the void formed at the adhesion interface, the vapor generated in the void is passed through the pores existing in the porous diffusion resistance layer. You can get away enough.
In addition, when the said void presence rate exceeds 70%, there exists a possibility that the vapor | steam generate | occur | produced in the void cannot fully escape through the pore which exists in a porous diffusion resistance layer.

Here, the void presence rate at the bonding interface between the first bonding portion of the bonding layer and the diffusion resistance layer refers to the ratio of the area where voids exist to the area of the bonding interface.
For example, in the cross section of the gas sensor element, the void existence ratio is measured by measuring the length of the portion where the void is formed with respect to the length of the bonding interface (if there are a plurality of voids, the length of the plurality of voids). By calculating the ratio of the total).

Moreover, it is preferable that the porosity of the said diffusion resistance layer which is porous is 10 to 20%.
In this case, even if the gas sensor element is rapidly heated in a state where water has entered the void formed at the adhesion interface, the vapor generated in the void is passed through the pores existing in the porous diffusion resistance layer. You can escape more effectively.

Example 1
A gas sensor element according to an embodiment of the present invention, a manufacturing method thereof, and a gas sensor will be described with reference to the drawings.
As shown in FIG. 1 and FIG. 2, the gas sensor element 1 of this example includes an oxygen ion conductive solid electrolyte body 11, one surface (first surface) 111 and the other surface (second surface) of the solid electrolyte body 11. ) 112 to be measured gas side electrode 12 and reference gas side electrode 13 respectively provided on 112, a porous diffusion resistance layer 17 that covers the gas to be measured side electrode 12 and allows the gas to be measured to pass through, and a solid electrolyte body 11. An intermediate layer 16 provided between the diffusion resistance layer 17 and a hollow portion 169 that is formed inside the intermediate layer 16 and between the solid electrolyte body 11 and the diffusion resistance layer 17 and introduces a gas to be measured. And.

An adhesive layer 2 is provided between the intermediate layer 16 and the diffusion resistance layer 17 to adhere them, and the adhesive layer 2 is provided on the surface 161 of the intermediate layer 16 on the diffusion resistance layer 17 side. The first adhesive portion 21 and the second adhesive portion 22 provided on the surface (second surface) 172 of the diffusion resistance layer 17 on the intermediate layer 16 side.
The first bonding portion 21 has at least a part of the inner peripheral portion 211 bonded to the second bonding portion 22 and a portion outside the first bonding portion 21 bonded to the diffusion resistance layer 17.
The second bonding portion 22 has its inner peripheral end 221 exposed to the hollow portion 169, and the exposed surface 222 of the inner peripheral end 221 and the surface of the diffusion resistance layer 17 on the intermediate layer 16 side (second surface). The bonding angle α formed between the 172 and 172 is an acute angle in the cross section in the stacking direction.
This will be described in detail below.

As shown in FIG. 1, the gas sensor element 1 includes an air-fuel ratio (air-fuel ratio) of an air-fuel mixture supplied to an engine based on a limit current flowing between electrodes depending on a specific gas concentration (oxygen concentration) in a gas to be measured (exhaust gas). A / F sensor element for detecting (A / F).
Further, the gas sensor element 1 has an oxygen ion conductive solid electrolyte body 11. A measured gas side electrode 12 made of platinum is provided on the first surface 111 of the solid electrolyte body 11. Further, a reference gas side electrode 13 made of platinum is provided on the second surface 112 of the solid electrolyte body 11.

  As shown in the figure, the second surface 112 of the solid electrolyte body 11 has a reference gas chamber forming layer 14 made of alumina that is electrically insulative and dense and does not transmit gas, outside the reference gas side electrode 13. Are stacked. A groove portion 141 is provided in the reference gas chamber forming layer 14, and a reference gas chamber 140 is formed by the groove portion 141. The reference gas chamber 140 is configured to be able to introduce a reference gas (atmosphere).

  A heater substrate 15 is laminated on the side of the reference gas chamber forming layer 14 opposite to the solid electrolyte body 11. On the heater substrate 15, a heating element (heater) 151 that generates heat when energized is provided so as to face the reference gas chamber forming layer 14. The heating element 151 is configured to heat the gas sensor element 1 to an activation temperature by generating heat by energization.

As shown in the figure, an intermediate layer 16 having an opening 168 is laminated on the first surface 111 of the solid electrolyte body 11 outside the gas-side electrode 12 to be measured. The intermediate layer 16 is made of alumina that has electrical insulation and is dense and impermeable to gas.
On the opposite side of the intermediate layer 16 from the solid electrolyte body 11, a porous diffusion resistance layer 17 made of a gas-permeable alumina porous body is laminated.

Further, it is covered with the space formed between the solid electrolyte body 11 and the diffusion resistance layer 17 inside the intermediate layer 16, that is, the opening 168 of the solid electrolyte body 11, the intermediate layer 16, and the diffusion resistance layer 17. A hollow portion 169 serving as a gas chamber to be measured is formed in the space. The hollow portion 169 is configured such that a gas to be measured can be introduced from the diffusion resistance layer 17.
Further, on the first surface 171 opposite to the second surface 172 of the diffusion resistance layer 17, a shielding layer 18 made of alumina that is electrically insulating and dense and does not transmit gas is laminated.

As shown in the figure, an adhesive layer 2 is provided between the intermediate layer 16 and the diffusion resistance layer 17 for bonding them together.
The adhesive layer 2 includes a part of the first adhesive portion 21 provided on the surface 161 of the intermediate layer 16 on the diffusion resistance layer 17 side and the second adhesive portion 22 provided on the second surface 172 of the diffusion resistance layer 17. It is composed of overlapping. The first adhesive portion 21 and the second adhesive portion 22 are a mixture of alumina and a binder.

  Specifically, as shown in FIGS. 1 and 2, the first adhesive portion 21 is covered in a state where an opening is provided on the surface 161 of the intermediate layer 16 on the diffusion resistance layer 17 side in the same manner as the intermediate layer 16. It is formed so as to cover the outside of the measurement gas side electrode 12. Further, the second bonding portion 22 covers the outer side of the measured gas side electrode 12 with the opening provided on the inner peripheral portion 211 of the first bonding portion 21 in the same manner as the first bonding portion 21. It is formed in an annular shape. That is, the inner peripheral portion 211 of the first bonding portion 21 and the second bonding portion 22 are joined.

Further, as shown in the figure, the second adhesive portion 22 is not formed on the outer peripheral portion 212 of the first adhesive portion 21, and the outer peripheral portion 212 of the first adhesive portion 21 is the first of the diffusion resistance layer 17. Directly bonded to the two surfaces 172.
Further, as shown in FIG. 1, the inner peripheral end 221 of the second adhesive portion 22 is exposed in the hollow portion 169. In addition, the adhesion angle α formed between the exposed surface 222 of the inner peripheral end 221 and the second surface 172 of the diffusion resistance layer 17 is an acute angle (greater than 0 ° and 90 ° in the cross section in the stacking direction of the gas sensor element 1). Angle smaller than °).

Next, the manufacturing method of the gas sensor element 1 of this example is demonstrated.
In the manufacturing method of the gas sensor element 1 of the present example, when forming the hollow portion 169 to be the gas chamber to be measured, as shown in FIGS. 3 and 4, at least the intermediate layer material application step, the first adhesive portion material An application process, a second adhesive portion material application process, and a lamination process are performed.

In the intermediate layer material application step, as shown in FIG. 3A, the intermediate layer material 160 is applied to one surface (first surface) 111 of the solid electrolyte sheet 111.
In the first adhesive portion material application step, as shown in FIG. 3A, the first adhesive portion material 210 is applied to the surface of the intermediate layer material 160.
In the second bonding portion application step, as shown in FIG. 3B, the second bonding portion material 220 is applied to one surface (second surface) 172 of the diffusion resistance layer sheet 170.

In the laminating step, as shown in FIGS. 4A and 4B, the solid electrolyte sheet 110 and the diffusion resistance layer sheet so that the first adhesive portion material 210 and the second adhesive portion material 220 face each other. 170 is laminated. Then, with the inner peripheral end 221 of the second adhesive portion material 220 exposed, the inner peripheral portion 211 of the first adhesive portion material 210 is joined to the second adhesive portion material 220, and the outer side of the inner peripheral portion 211 is outside. The portion is bonded to the diffusion resistance layer sheet 170.
This will be described in detail below.

  In manufacturing the gas sensor element 1 of this example, first, the heater substrate sheet, the reference gas chamber forming layer 14, the solid electrolyte body 11, the diffusion resistance layer 17, and the shielding layer 18 in the gas sensor element 1 are formed. 150, a reference gas chamber forming layer sheet 140, a solid electrolyte body sheet 110, a diffusion resistance layer sheet 170, and a shielding layer sheet 180 are produced (see FIG. 1).

  Next, as shown in FIG. 3A, a paste-like measured gas side electrode material 120 that forms the measured gas side electrode 12 is applied to the first surface 111 of the solid electrolyte sheet 110 by printing. Further, a reference gas side electrode material (not shown) for forming the reference gas side electrode 13 is applied to the second surface 112 of the solid electrolyte sheet 11 by printing.

  Next, as shown in the figure, a paste-like intermediate layer material 160 for forming the intermediate layer 16 is applied to the first surface 111 of the solid electrolyte sheet 110 by printing. At this time, the intermediate layer material 160 is applied so as to cover the outside of the measured gas side electrode material 120 that has already been applied, with the opening provided.

  Next, as shown in the figure, a paste-like first adhesive portion material 210 that forms the first adhesive portion 21 of the adhesive layer 2 is applied to the surface of the applied intermediate layer material 160 by printing. At this time, the first adhesive portion material 210 is applied by printing a plurality of times. In addition, the viscosity of the first adhesive portion material 210 is 30 to 150 Pa · s.

  On the other hand, as shown in FIG. 3B, a paste-like second adhesive portion material 220 for forming the second adhesive portion 22 of the adhesive layer 2 is applied to the second surface 172 of the diffusion resistance layer sheet 170 by printing. To do. At this time, the second adhesive portion material 220 is annularly applied with a smaller area than the first adhesive portion material 210 so as to be finally joined to the inner peripheral portion 211 of the first adhesive portion material 210. . Moreover, the viscosity of the material 220 for 2nd adhesion part shall be 30-150 Pa.s.

Next, as shown in FIG. 4A, the first surface 111 of the solid electrolyte sheet 110 and the second surface 172 of the diffusion resistance layer sheet 170 are opposed to each other so as to be laminated. Then, the inner peripheral portion 211 of the first adhesive portion material 210 is joined to the second adhesive portion material 220. Further, the outer peripheral portion 212 of the first adhesive portion material 210 is joined to the second surface 172 of the diffusion resistance layer sheet 170. At this time, the first adhesive portion material 210 and the second adhesive portion material 220 are joined together with the inner peripheral end portion 221 of the second adhesive portion material 220 exposed.
Thereby, as shown in FIG. 4B, a hollow portion 169 is formed between the solid electrolyte sheet 111 and the diffusion resistance layer sheet 171.

Next, the reference gas chamber forming layer sheet 140 and the heater substrate sheet 150 are laminated on the second surface 112 of the solid electrolyte sheet 110, and the shielding layer sheet is further formed on the first surface 171 of the diffusion resistance layer sheet 170. 180 are stacked. Thus, an element intermediate is produced (see FIG. 1).
And an element intermediate body is baked on predetermined conditions, and the gas sensor element 1 (FIG. 1) is obtained.

Next, the gas sensor 8 incorporating the gas sensor element 1 of this example will be described.
As shown in FIG. 5, the gas sensor 8 includes a gas sensor element 1, an insulator 81 that inserts and holds the gas sensor element 1 inside, a housing 82 that inserts and holds the insulator 81 inside, and a base end side of the housing 82. It has an atmosphere-side cover 83 provided and an element cover 84 that is disposed on the front end side of the housing 82 and protects the gas sensor element 1.

As shown in the figure, the element cover 84 is constituted by a double-structured cover including an outer cover 841 and an inner cover 842.
The outer cover 841 and the inner cover 842 are provided with a conduction hole 843 in the side surface and the bottom surface for conducting the gas to be measured.

Next, the effects of the gas sensor element 1 of this example, the manufacturing method thereof, and the gas sensor 8 will be described.
In the gas sensor element 1 of the present example, an adhesive layer 2 is provided between the intermediate layer 16 and the diffusion resistance layer 17 to bond them together, and the adhesive layer 2 is provided on the intermediate layer 16. It consists of a first bonding portion 21 and a second bonding portion 22 provided on the diffusion resistance layer 17. The second adhesive portion 22 is formed between the exposed surface 222 of the inner peripheral end portion 221 and the second surface 172 of the diffusion resistance layer 17 while exposing the inner peripheral end portion 221 to the hollow portion 169. The bonding angle α is an acute angle in the cross section in the stacking direction.

  That is, the bonding is performed so that the bonding angle α formed between the exposed surface 222 of the bonding layer 2 (the inner peripheral end 221 of the second bonding portion 22) and the second surface 172 of the diffusion resistance layer 17 becomes an acute angle. Layer 2 is formed. Therefore, compared with the conventional case where the bonding angle is an obtuse angle, it is possible to prevent stress from being concentrated around the portion where the exposed surface 222 of the adhesive layer 2 and the second surface 172 of the diffusion resistance layer 17 merge. it can. Thereby, generation | occurrence | production of the crack etc. resulting from the stress etc. which generate | occur | produce at the time of use of the gas sensor element 1 can be prevented.

  In the adhesive layer 2, the first adhesive portion 21 has an inner peripheral portion 211 joined to the second adhesive portion 22, and an outer peripheral portion 212 that is an outer portion thereof joined to the diffusion resistance layer 17. Has been. That is, the second adhesive portion 22 and the diffusion resistance layer 17 are joined to the first adhesive portion 21. Therefore, a part of the bonding interface of the first adhesive portion 21 becomes a bonding interface with the porous diffusion resistance layer 17. Thereby, the void formed in the joining interface of the adhesion parts of the 1st adhesion part 21 and the 2nd adhesion part 22 can be reduced.

  Even if a void is formed at the bonding interface between the first adhesive portion 21 and the diffusion resistance layer 17 and the gas sensor element 1 is rapidly heated in a state where water has entered the void, the vapor generated in the void is generated. Can escape through pores present in the porous diffusion resistance layer 17. Thereby, it can suppress that a vapor | steam lose | disappears in a void and a big thermal stress arises around a void like the past, and generation | occurrence | production of the crack of a gas sensor element, etc. can be prevented.

  In the method for manufacturing the gas sensor element 1, in the second adhesive portion material applying step, the second adhesive portion material 220 for forming the second adhesive portion 22 of the adhesive layer 2 is applied to the diffusion resistance layer sheet 170. To do. In the stacking step, the solid electrolyte sheet 110 and the diffusion resistance layer sheet 170 are stacked with the inner peripheral end 221 of the second adhesive portion material 220 exposed. Therefore, it becomes easy to make the bonding angle α formed between the exposed surface 222 of the inner peripheral end 221 of the second bonding portion 22 and the second surface 172 of the diffusion resistance layer 17 an acute angle.

Further, in the laminating step, the inner peripheral portion 211 of the first adhesive portion material 210 is joined to the second adhesive portion material 220, and the outer peripheral portion 212 that is an outer portion is joined to the diffusion resistance layer sheet 170. . Therefore, in the adhesive layer 2, a part of the bonding interface of the first bonding portion 21 can be used as a bonding interface with the porous diffusion resistance layer 17.
Thereby, the gas sensor element 1 of this example which can prevent generation | occurrence | production of a crack etc. can be manufactured easily.

  Further, the gas sensor 8 of the present example incorporates the gas sensor element 1 described above. That is, the gas sensor element 1 which can prevent generation | occurrence | production of a crack etc. is incorporated. Therefore, the gas sensor 8 is excellent in durability.

  Thus, according to this example, it is possible to provide the gas sensor element 1 that can prevent the occurrence of cracks, the manufacturing method thereof, and the gas sensor 8.

(Example 2)
In this example, the performance of the gas sensor element is evaluated as shown in FIG.
In this example, a plurality of gas sensor elements having different adhesion angles α were produced, and the effect of preventing the occurrence of cracks was evaluated.
The basic configuration of the gas sensor element is the same as that of the first embodiment (FIG. 1).

Next, the evaluation method will be described.
First, the gas sensor element is immersed in water for a predetermined time and taken out. Next, a voltage is applied to the gas sensor element, and the voltage is increased until cracking occurs. And the voltage when a crack generate | occur | produces in a gas sensor element is measured. It should be noted that the occurrence of cracks is confirmed by utilizing the fact that the insulating properties decrease when cracks occur.

Next, the above evaluation results are shown in FIG.
In the figure, the vertical axis represents voltage, and the horizontal axis represents the angle (°) of the adhesion angle α. For the voltage on the vertical axis, the voltage at which cracking occurs when a voltage is applied to the gas sensor element having an acute adhesion angle α is 1.0.
As shown in the figure, when the adhesion angle α is an acute angle, there is no change in the voltage at which cracking occurs. On the other hand, when the adhesion angle α becomes an obtuse angle, the voltage at which cracking occurs is significantly reduced.

  That is, when the bonding angle α is an obtuse angle, a notch is formed between the bonding layer and the diffusion resistance layer (see FIG. 9B). Therefore, the stress generated when a voltage is applied to the gas sensor element concentrates on the notch between the adhesive layer and the diffusion resistance layer (notch effect). Therefore, it is considered that cracking occurs even at a low voltage. On the other hand, when the bonding angle α is an acute angle, such stress concentration does not occur, so that it is considered that the occurrence of cracks can be prevented.

  From the above results, it was found that the adhesion angle α is preferably an acute angle. And it turned out that the effect which prevents generation | occurrence | production of a crack is fully acquired by making the adhesion angle (alpha) into an acute angle. In particular, it was found that when the bonding angle α is 50 ° or less, the stress is extremely reduced and the effect of preventing the occurrence of cracking is further enhanced.

(Example 3)
In this example, the performance of the gas sensor element is evaluated as shown in FIG.
In this example, a plurality of gas sensor elements (samples A) having different void existence ratios at the bonding interface between the first bonding portion of the bonding layer and the porous diffusion resistance layer are prepared. A plurality of gas sensor elements (sample B) having different void existence ratios at the interface with the porous intermediate layer were prepared, and the effects of preventing the occurrence of cracks were evaluated.

Here, the void presence rate is measured by measuring the length of the bonded interface or the length of the portion where the void is formed with respect to the length of the interface in the cross section of the gas sensor element (if there are a plurality of voids, By calculating the ratio of the total length).
The basic configuration of the gas sensor element is the same as that of the first embodiment (FIG. 1).

Next, the evaluation method will be described.
First, the gas sensor element is immersed in water for a predetermined time and taken out. Next, a voltage is applied to the gas sensor element, and the voltage is increased until a crack occurs at the junction interface or in the vicinity of the interface. And the voltage when a crack generate | occur | produces in a gas sensor element is measured. It should be noted that the occurrence of cracks is confirmed by utilizing the fact that the insulating properties decrease when cracks occur.

Next, the above evaluation results are shown in FIG.
In the figure, the vertical axis represents voltage, and the horizontal axis represents void presence rate (%). As for the voltage on the vertical axis, the voltage at which cracking occurs when a voltage is applied to a gas sensor element having a void presence rate of 0% is 1.0.
As shown in the figure, sample A has no change in the voltage at which cracking occurs if the void abundance ratio is 70% or less. On the other hand, sample B has no change in the voltage at which cracking occurs if the void abundance ratio is 20% or less, but when it exceeds 20%, the voltage at which cracking occurs is significantly reduced.

That is, when a voltage is applied to the gas sensor element while water has entered and accumulated in the void, the gas sensor element is heated and steam is generated in the void. At this time, even if a void exists at the bonding interface between the first adhesion portion of the adhesive layer and the porous diffusion resistance layer, the vapor in the void escapes through the pores existing in the porous diffusion resistance layer. You can do it.
However, if a void exists at the interface between the first adhesive portion of the adhesive layer and the non-porous intermediate layer, the vapor in the void loses the escape field. Therefore, a large thermal stress is generated around the void, and it is considered that cracking occurs even at a low voltage.

From the above results, it was found that the void presence rate at the bonding interface between the first adhesive portion of the adhesive layer and the porous diffusion resistance layer is preferably 70% or less. And it turned out that the effect which prevents generation | occurrence | production of a crack is fully acquired by making a void presence rate into 70% or less.
Moreover, it turned out that it is preferable that the void presence rate in the interface of the 1st adhesion part of a contact bonding layer and a non-porous intermediate | middle layer is 20% or less.

DESCRIPTION OF SYMBOLS 1 Gas sensor element 11 Solid electrolyte body 12 Measured gas side electrode 13 Reference gas side electrode 16 Intermediate | middle layer 169 Hollow part 17 Diffusion resistance layer 172 2nd surface (surface of intermediate | middle layer side)
2 Adhesive layer 21 1st adhesion part 211 Inner circumference 22 Second adhesion part 221 Inner circumference end 222 Exposed surface

Claims (6)

An oxygen ion conductive solid electrolyte body, a measured gas side electrode and a reference gas side electrode provided on one surface and the other surface of the solid electrolyte body, and the measured gas side electrode and the measured gas side electrode A porous diffusion resistance layer that allows gas to permeate; an intermediate layer provided between the solid electrolyte body and the diffusion resistance layer; and the solid electrolyte body and the diffusion resistance layer inside the intermediate layer. In a laminated type gas sensor element that is formed between and having a hollow portion for introducing a gas to be measured,
Between the intermediate layer and the diffusion resistance layer, there is provided an adhesive layer for adhering both,
The adhesive layer includes a first adhesive portion provided on the surface of the intermediate layer on the diffusion resistance layer side and a second adhesive portion provided on the surface of the diffusion resistance layer on the intermediate layer side,
The first adhesive part has at least a part of its inner periphery joined to the second adhesive part, and an outer part thereof joined to the diffusion resistance layer,
The second adhesive portion has its inner peripheral end exposed to the hollow portion, and is formed between the exposed surface of the inner peripheral end and the surface of the diffusion resistance layer on the intermediate layer side. A gas sensor element characterized in that an adhesion angle is an acute angle in a cross section in the stacking direction.   The gas sensor element according to claim 1, wherein the bonding angle is 80 ° or less.   3. The gas sensor element according to claim 1, wherein the adhesion angle is 50 ° or less. 4.   The gas sensor element according to any one of claims 1 to 3, wherein a void existing rate in a bonding interface between the first adhesive portion of the adhesive layer and the diffusion resistance layer is 70% or less. Gas sensor element to do. A method for producing the gas sensor element according to any one of claims 1 to 4,
In forming the hollow portion, the intermediate layer material application step of applying the intermediate layer material on one surface of the solid electrolyte sheet,
A first adhesive portion material application step of applying a first adhesive portion material on the surface of the intermediate layer material;
A second adhesive portion material application step of applying a second adhesive portion material to one surface of the diffusion resistance layer sheet;
A laminating step of laminating the solid electrolyte body sheet and the diffusion resistance layer sheet so that the first adhesive portion material and the second adhesive portion material face each other;
In the laminating step, at least a part of the inner peripheral portion of the first adhesive portion material is bonded to the second adhesive portion material in a state where the inner peripheral end portion of the second adhesive portion material is exposed. A method for producing a gas sensor element, comprising bonding a portion on the outer side to the diffusion resistance layer sheet.   A gas sensor comprising the gas sensor element according to any one of claims 1 to 4.

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