JP6602257B2 - Gas sensor element - Google Patents

Description

  The present invention relates to a gas sensor element suitably used for detecting a specific gas concentration contained in combustion gas or exhaust gas of a combustor or an internal combustion engine, for example.

Conventionally, a gas sensor (NOx sensor) that detects a specific gas concentration (for example, a concentration of nitrogen oxide (NOx)) in exhaust gas of an internal combustion engine has been used (Patent Document 1). A general NOx sensor has a gas sensor element mainly including a first pump cell, an oxygen concentration detection cell, and a second pump cell.
Among these, the 1st pump cell 1100 has the solid electrolyte layer 1110 and a pair of electrodes 1120 and 1130 arrange | positioned facing both surfaces of the solid electrolyte layer 1110 as shown in FIG. The electrode 1120 is exposed to the internal space of the gas sensor element and pumps oxygen.

As shown in FIG. 10, the second pump cell 1300 includes a solid electrolyte layer 1310 and a pair of electrodes 1320 and 1330 stacked on one surface (same surface) of the solid electrolyte layer 1310 so as to be separated from each other. ing. The electrode 1330 is exposed to the internal space of the gas sensor element to detect the NOx concentration, while the electrode 1320 is exposed to the reference chamber and serves as a reference electrode. Each electrode 1320 and 1330 is partitioned by an insulating layer 1400.
Since the installation space of the second pump cell 1300 is limited so as not to interfere with other cells (first pump cell 1100, oxygen concentration detection cell), each electrode 1320, 1330 is disposed on the same surface of the solid electrolyte layer 1310. By arranging the cell, the cell can be made compact.

JP 2010-122187 A

By the way, in the case of the first pump cell 1100 in which the pair of electrodes 1120 and 1130 are disposed opposite to each other on both surfaces of the solid electrolyte layer 1110, the current path B flowing between the electrodes 1120 and 1130 has a cross-sectional area in the overlapping region of the electrodes 1120 and 1130. And flows in the thickness direction of the solid electrolyte layer 1110. Therefore, as the thickness of the solid electrolyte layer 1110 is thinner, the internal resistance of the cell is reduced, power is saved, the accuracy of oxygen pump control is improved, and the material of the solid electrolyte layer is reduced.
However, when the electrodes 1320 and 1330 are arranged on the same surface of the solid electrolyte layer 1310 as in the second pump cell 1300, the current path C flowing between the electrodes 1320 and 1330 has a cross-sectional area in the thickness direction of the solid electrolyte body 1310. It flows in the horizontal direction. For this reason, there exists a problem that the internal resistance of a cell increases and the detection precision and responsiveness are inferior, so that the thickness of the solid electrolyte layer 1310 is thin. On the other hand, increasing the thickness of the solid electrolyte layer 1310 leads to an increase in cost.

  Therefore, an object of the present invention is to provide a gas sensor element that can reduce internal resistance in a cell in which a pair of electrodes are stacked on the same surface of a solid electrolyte body, improve cell characteristics, and reduce costs.

In order to solve the above-mentioned problem, a gas sensor element of the present invention is a gas sensor element comprising at least one cell having a solid electrolyte body and a pair of electrodes arranged on the same surface of the solid electrolyte body. solid electrolyte body straddles at least a portion of the region to be a shortest distance of the opposing portion between the pair of electrodes, have a thicker convex portion than the maximum thickness of the solid electrolyte body overlapping with the pair of electrodes, wherein Protrusions are formed in all of the regions and are in contact with the pair of electrodes, respectively, and one electrode of the pair of electrodes faces a reference oxygen chamber as an isolated small space. Features.
According to this gas sensor element, by providing a projecting portion across the facing portion between a pair of electrodes, the cross-sectional area of the solid electrolyte body between the pair of electrodes increases, and as a result, the specific resistance of the solid electrolyte body decreases. The cell characteristics (for example, detection accuracy and responsiveness) can be improved. In addition, since it is not necessary to increase the thickness of the entire solid electrolyte layer, the cost can be reduced.

Moreover, according to this gas sensor element, the cross-sectional area of a solid electrolyte body can be increased reliably by forming a convex part in all the said area | regions. Further, when the convex portions are in contact with the pair of electrodes, a current path between the pair of electrodes passing through the convex portions can be reliably generated, and the specific resistance of the solid electrolyte body can be further reduced.

In the gas sensor element of the present invention, when viewed from the stacking direction of the solid electrolyte body and the pair of electrodes, the convex portion may overlap a part of the pair of electrodes.
According to this gas sensor element, when the convex portion is formed on the solid electrolyte body by printing or the like, even if the convex formation region is displaced due to printing misalignment or the like, the convex portion is surely in contact with the pair of electrodes. The specific resistance of the electrolyte body can be further reduced.

  According to the present invention, the internal resistance in a cell in which a pair of electrodes are stacked on the same surface of the solid electrolyte body can be reduced, the cell characteristics can be improved, and the cost can be reduced.

It is sectional drawing which follows the axial direction of the gas sensor (NOx sensor) which concerns on embodiment of this invention. It is sectional drawing which follows the axial direction of a gas sensor element. It is a partial expanded sectional view of an Ip2 cell. It is a partial enlarged top view of an Ip2 cell. It is a disassembled perspective view which shows an example of the formation method of the convex part of a solid electrolyte body. It is a partial expanded sectional view which shows another example of an Ip2 cell. It is a partial expanded top view which shows another example of an Ip2 cell. It is a partial expanded sectional view which shows another example of an Ip2 cell. It is a partial expanded sectional view of the Ip1 cell of the conventional NOx sensor. It is a partial expanded sectional view of the Ip2 cell of the conventional NOx sensor.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a longitudinal sectional view (a sectional view cut along an axis AX) of a gas sensor (NOx sensor) 1 according to an embodiment of the present invention, and FIG. 2 is a sectional view along an axis AX of a gas sensor element 10 included in the gas sensor 1. 3 is a partially enlarged sectional view of the Ip2 cell 130, and FIG. 4 is a partially enlarged top view of the Ip2 cell 130.

The gas sensor 1 includes a gas sensor element 10 that can detect the concentration of a specific gas (NOx) in exhaust gas (measurement gas) that is a measurement target gas, and is used by being mounted on an exhaust pipe (not shown) of an internal combustion engine. It is a NOx sensor. This gas sensor 1 includes a cylindrical metal shell 20 in which a screw portion 21 for fixing to an exhaust pipe is formed at a predetermined position on the outer surface. The gas sensor element 10 has an elongated plate shape extending in the direction of the axis AX, and is held inside the metal shell 20.
More specifically, the gas sensor 1 includes a holding member 60 having an insertion hole 62 into which the rear end portion 10k (the upper end portion in FIG. 1) of the gas sensor element 10 is inserted, and six pieces held inside the holding member 60. Terminal members. In FIG. 1, only two terminal members (specifically, terminal members 75 and 76) out of the six terminal members are illustrated.

A total of six electrode terminal portions 14 and 17 (only two are shown in FIG. 1) having a rectangular shape in plan view are formed at the rear end portion 10k of the gas sensor element 10, and each of the electrode terminal portions 14 and 17 includes The above-described terminal members are electrically connected. For example, the element contact portion 75 b of the terminal member 75 is elastically contacted and electrically connected to the electrode terminal portion 14. Further, the element contact portion 76 b of the terminal member 76 is elastically contacted and electrically connected to the electrode terminal portion 17.
Furthermore, different lead wires 71 are electrically connected to the six terminal members (terminal members 75, 76, etc.), respectively. For example, as shown in FIG. 1, the core wire of the lead wire 71 is crimped and gripped by the lead wire gripping portion 77 of the terminal member 75. Further, the core wire of the other lead wire 71 is crimped and held by the lead wire gripping portion 78 of the terminal member 76.

The metal shell 20 is a cylindrical member having a through hole 23 that penetrates in the direction of the axis AX. The metal shell 20 has a shelf 25 that constitutes a part of the through hole 23 in a form protruding radially inward. The metal shell 20 projects the front end portion 10s of the gas sensor element 10 to the outside of its front end side (downward in FIG. 1), and the rear end portion 10k of the gas sensor element 10 to the outside of its rear end side (upward in FIG. 1). The gas sensor element 10 is held in the through hole 23 in a state where the gas sensor element 10 is protruded into the through hole 23.
Further, an annular ceramic holder 42, two talc rings 43 and 44 formed by annularly filling talc powder, and a ceramic sleeve 45 are disposed inside the through hole 23 of the metal shell 20. Specifically, the ceramic holder 42, the talc rings 43 and 44, and the ceramic sleeve 45 are arranged in this order in the axial direction front end side (lower end side in FIG. 1) of the metal shell 20 in a state of surrounding the gas sensor element 10 in the radial direction. To the rear end side in the axial direction (upper end side in FIG. 1).

Further, a metal cup 41 is disposed between the ceramic holder 42 and the shelf 25 of the metal shell 20. A caulking ring 46 is disposed between the ceramic sleeve 45 and the caulking portion 22 of the metal shell 20. The caulking portion 22 of the metal shell 20 is crimped so as to press the ceramic sleeve 45 against the distal end side via the crimping ring 46.
A metal (specifically, stainless steel) external protector 31 and an internal protector 32 having a plurality of holes are attached to the distal end portion 20b of the metal shell 20 by welding so as to cover the distal end portion 10s of the gas sensor element 10. ing. On the other hand, an outer cylinder 51 is attached to the rear end portion of the metal shell 20 by welding. The outer cylinder 51 has a cylindrical shape extending in the direction of the axis AX and surrounds the gas sensor element 10.

The holding member 60 is a cylindrical member made of an insulating material (specifically alumina) and having an insertion hole 62 penetrating in the direction of the axis AX. In the insertion hole 62, the six terminal members (terminal members 75, 76, etc.) described above are arranged. At the rear end portion of the holding member 60, a flange portion 65 that protrudes radially outward is formed. The holding member 60 is held by the internal support member 53 in such a manner that the collar portion 65 contacts the internal support member 53. The inner support member 53 is held by the outer cylinder 51 by a caulking portion 51g that is caulked toward the radially inner side of the outer cylinder 51.
An insulating member 90 is disposed on the rear end surface 61 of the holding member 60. The insulating member 90 is made of an electrically insulating material (specifically, alumina) and has a cylindrical shape. The insulating member 90 is formed with a total of six through holes 91 penetrating in the direction of the axis AX. In the through hole 91, the lead wire gripping portions (lead wire gripping portions 77, 78, etc.) of the terminal member described above are arranged.

  Further, an elastic seal member 73 made of fluororubber is disposed on the radially inner side of the rear end opening 51c located at the rear end in the axial direction (the upper end in FIG. 1) of the outer cylinder 51. The elastic seal member 73 is formed with a total of six cylindrical insertion holes 73c extending in the direction of the axis AX. Each insertion hole 73 c is configured by an insertion hole surface 73 b (cylindrical inner wall surface) of the elastic seal member 73. One lead wire 71 is inserted through each insertion hole 73c. Each lead wire 71 extends to the outside of the gas sensor 1 through the insertion hole 73 c of the elastic seal member 73. The elastic seal member 73 is elastically compressed and deformed in the radial direction by caulking the rear end opening 51c of the outer cylinder 51 inward in the radial direction, whereby the insertion hole surface 73b and the outer peripheral surface 71b of the lead wire 71 are brought into close contact with each other. Thus, the space between the insertion hole surface 73b and the outer peripheral surface 71b of the lead wire 71 is sealed in a watertight manner.

On the other hand, as shown in FIG. 2, the gas sensor element 10 includes an insulating layer 115, three composite layers 201, 202, 203, and an insulator 140 disposed between the composite layers 201, 202. It has the structure laminated | stacked on the lamination direction in this order. The composite layers 201, 202, and 203 are formed by filling solid electrolyte bodies 111, 121, and 131 into through holes provided in the insulating layers 181, 182, and 183, respectively.
Further, a heater 161 is laminated on the gas sensor element 10 on the back side of the composite layer 203. In FIG. 2, the insulating layer 115 side is described as “front surface side”, and the heater 161 side is described as “back surface side”. The heater 161 includes plate-like insulators 162 and 163 mainly composed of alumina, and a heater pattern 164 (mainly composed of Pt) embedded therebetween.

The solid electrolyte bodies 111, 121, and 131 are made of zirconia, which is a solid electrolyte, and have oxygen ion conductivity. A through hole is formed in the insulator 140, and the through hole 140 h becomes a first space 150 formed between the two composite layers 201 and 202.
Further, a part of the composite layer 203 in which the solid electrolyte body 131 is embedded is cut out to form a second space 160 in which the solid electrolyte body 131 is exposed.
A through hole is formed in the solid electrolyte body 121 of the composite layer 202 disposed between the first space 150 and the second space 160 in the stacking direction, and the first space 150 is formed through the through hole. And the second space 160 communicate with each other. In this way, the gas to be measured introduced into the first space 150 flows along the axis AX direction, and then is introduced into the second space 160 along the stacking direction. The introduction direction (flow direction) of the gas to be measured is indicated by a symbol F.

  A first porous body (not shown) having gas permeability and water permeability is provided on the side of the first space 150 (the front and back directions in FIG. 2). A gas to be measured can be introduced by communicating with the outside of the gas sensor element 10 through one porous body. The first porous body serves as a partition from the outside of the gas sensor element 10 and restricts the flow rate of exhaust gas per unit time into the first space 150.

On the surface side of the solid electrolyte body 111, a porous Ip1 + electrode 112 is provided. A porous Ip1-electrode 113 is provided on the back side of the solid electrolyte body 111. The solid electrolyte body 111, the Ip1 + electrode 112, and the Ip1-electrode 113 constitute an Ip1 cell 110.
In addition, an insulating layer 115 made of alumina or the like is laminated on the surface side of the Ip1 + electrode 112 and the Ip1 + lead 112r, and a substantially rectangular through hole surrounding the Ip1 + electrode 112 is provided on the tip side of the insulating layer 115. A porous layer 190 is embedded in the surface. In this way, gas can enter and exit between the Ip1 + electrode 112 and the outside via the porous layer 190.
In this Ip1 cell 110, the atmosphere in contact with the Ip1 + electrode 112 (atmosphere outside the gas sensor element 10) and the atmosphere in contact with the Ip1-electrode 113 (first atmosphere) according to the pump current Ip1 flowing between the Ip1 + electrode 112 and the Ip1-electrode 113. The atmosphere is pumped and pumped (so-called oxygen pumping).

The solid electrolyte body 121 is disposed so as to face the solid electrolyte body 111 in the stacking direction with the insulator 140 interposed therebetween. A porous Vs-electrode 122 is provided on the surface side of the solid electrolyte body 121. More specifically, the Vs− electrode 122 is provided in the first space 150 on the downstream side of the measurement gas introduction direction F with respect to the Ip1− electrode 113.
In addition, a porous Vs + electrode 123 is provided on a portion of the back surface side of the solid electrolyte body 121 facing the Vs− electrode 122. Here, as described above, a part of the composite layer 203 in which the solid electrolyte body 131 is embedded is cut out, and the Vs + electrode 123 is disposed in the cut out part.
The solid electrolyte body 121, the Vs− electrode 122, and the Vs + electrode 123 constitute a Vs cell 120. The Vs cell 120 mainly includes an oxygen partial pressure difference between the atmospheres separated by the solid electrolyte body 121 (the atmosphere in the first space 150 in contact with the electrode 122 and the atmosphere in a reference oxygen chamber 170 to be described later in contact with the electrode 123). An electromotive force is generated according to

The solid electrolyte body 131 is disposed so as to face the solid electrolyte body 121 in the stacking direction. On the same surface (front surface) side of the solid electrolyte body 131, a porous Ip2 + electrode 132 and a porous Ip2-electrode 133 are provided apart from each other in the axis AX direction.
A reference oxygen chamber 170 as an isolated small space is formed between the Ip2 + electrode 132 and the Vs + electrode 123. The reference oxygen chamber 170 is configured by a gap in the stacking direction between the above-described hollow portion of the composite layer 203 and the solid electrolyte body 121, and is further partitioned by an insulator 145 from the second space 160. In the reference oxygen chamber 170, a ceramic porous body is disposed.
Further, the Ip2-electrode 133 is disposed in the second space 160 at the cutout portion of the composite layer 203 described above.

The solid electrolyte body 131, the Ip2 + electrode 132, and the Ip2-electrode 133 constitute an Ip2 cell 130 for detecting the nitrogen oxide (NOx) concentration. The Ip2 cell 130 moves NOx-derived oxygen (oxygen ions) decomposed in the second space 160 to the reference oxygen chamber 170 through the solid electrolyte body 131. At this time, a current corresponding to the concentration of nitrogen oxide contained in the exhaust gas (measured gas) introduced into the second space 160 flows between the electrode 132 and the electrode 133.
Here, the Ip2 + electrode 132 and the Ip2- electrode 133 correspond to “a pair of electrodes” in the claims. The Ip2 cell 130 corresponds to a “cell” in the claims.

Here, the NOx concentration detection by the gas sensor 1 of the present embodiment will be briefly described.
The solid electrolyte bodies 111, 121, 131 of the gas sensor element 10 are heated and activated as the heater pattern 164 is heated. As a result, the Ip1 cell 110, the Vs cell 120, and the Ip2 cell 130 are operated.
Exhaust gas (measurement target gas) flowing through an exhaust passage (not shown) is introduced into the first space 150 while being restricted by the first porous body. At this time, a weak current Icp flows through the Vs cell 120 from the Vs + electrode 123 side to the Vs− electrode 122 side. Therefore, oxygen in the exhaust gas can receive electrons from the Vs-electrode 122 in the first space 150 on the negative electrode side, flows as oxygen ions in the solid electrolyte body 121, and enters the reference oxygen chamber 170. Moving. That is, when the current Icp flows between the Vs− electrode 122 and the Vs + electrode 123, oxygen in the first space 150 is sent into the reference oxygen chamber 170.

When the oxygen concentration of the exhaust gas introduced into the first space 150 is lower than a predetermined value, the current Ip1 is supplied to the Ip1 cell 110 so that the Ip + electrode 112 side becomes a negative electrode, and the gas sensor element 10 enters the first space 150 from the outside. Pump oxygen. On the other hand, when the oxygen concentration of the exhaust gas introduced into the first space 150 is higher than a predetermined value, the current Ip1 is supplied to the Ip1 cell 110 so that the Ip-electrode 113 side becomes a negative electrode, and the gas sensor element 10 is supplied from the first space 150. Pump out oxygen to the outside.
Thus, the gas to be measured whose oxygen concentration is adjusted in the first space 150 is introduced into the second space 160. The specific gas component (NOx component) in the gas to be measured that is in contact with the Ip2-electrode 133 in the second space 160 is applied with a voltage Vp2 between the Ip2-electrode 133 and the Ip2 + electrode 132, whereby the Ip2-electrode 133 is obtained. The oxygen that has been decomposed (reduced) into nitrogen and oxygen above flows into the solid electrolyte body 131 as oxygen ions and moves into the reference oxygen chamber 170. At this time, the current Ip2 flowing through the Ip2 cell 130 can be detected, and the NOx concentration in the measurement gas can be detected based on the current value.

Next, the convex part 131p of the solid electrolyte body 131 is demonstrated with reference to FIG. 3, FIG.
As shown in FIG. 3, the solid electrolyte body 131 straddles the facing portions of the pair of electrodes 132 and 133, and integrally includes a convex portion 131 p having a thickness t <b> 1. This thickness t1 is thicker than the maximum thickness t0 of the solid electrolyte body 131 that overlaps the pair of electrodes 132 and 133. In the example of FIG. 3, the convex portion 131p is on the electrodes 132 and 133 side (surface side) of the solid electrolyte body 131. ). Further, the height in the stacking direction of the convex portion 131p is lower than the height in the stacking direction of the second space 160 and the reference oxygen chamber 170, and between the second space 160 and the reference oxygen chamber 170 on the surface side of the convex portion 131p. A partitioning insulating layer 145 is stacked.
Further, as shown in FIG. 4, the convex portion 131p is at least a part of the region R that is the shortest distance indicated by the arrow among the opposed portions of the pair of electrodes 132 and 133 (in the example of FIG. (In addition to the periphery of the region R). The leads 132L.1 from the electrodes 132 and 133 toward the rear end side. 133L extends.

Thus, by providing the convex part 131p across the opposing part of a pair of electrodes 132 and 133, as shown in FIG. 3, the solid electrolyte body 131 (part of thickness t0) which overlaps with a pair of electrodes 132 and 133, respectively. ) In addition to the normal current path C that passes through the projections 131p from the side surfaces of the pair of electrodes 132 and 133. For this reason, the cross-sectional area of the solid electrolyte body 131 between the pair of electrodes 132 and 133 is increased, and as a result, the specific resistance of the solid electrolyte body 131 is lowered, so that the detection accuracy and responsiveness of the Ip2 cell 130 can be improved. . Moreover, since it is not necessary to thicken the whole part which overlaps with a pair of electrodes 132 and 133 among the solid electrolyte layers 131, cost reduction is realizable.
From the viewpoint of reliably reducing the specific resistance of the solid electrolyte body 131, it is preferable that the thickness t1 ≧ 1.2 × t0. The upper limit of the thickness t1 is not particularly limited. For example, the upper limit is less than the height of the second space 160 or the reference oxygen chamber 170.

FIG. 5 is an exploded perspective view showing an example of a method of forming the convex portion 131p. First, the pair of electrodes 132 and 133 and their leads 132L and 133L are paste-printed on the solid electrolyte body 131 (surface side) of the composite layer 203 including the insulating layer 1831. Next, the convex portion 131p is paste-printed so as to cover the region R.
Further, the insulating layer 1832 is paste-printed so as to fill the step between the pair of electrodes 132 and 133 and the convex portion 131p. The opening size of the through hole 1832h provided in the insulating layer 1832 is smaller than the outer shape of the solid electrolyte body 131, covers the outer periphery of the solid electrolyte body 131, and the through hole 1832h forms the second space 160 and the reference oxygen chamber 170. It corresponds to the above-mentioned “cut-out part”.
Next, the insulating layer 1833 is paste printed over the insulating layer 1832 (on the front surface side). The insulating layer 1833 includes an insulating layer 145 that covers the top (surface side) of the protrusion 131p.
Thereafter, other portions of the gas sensor element 10 are appropriately laminated and the whole is fired, whereby the insulating layers 1831, 1832, and 1833 become the insulating layer 183.

In order to reduce the specific resistance of the solid electrolyte body 131 by reliably generating the current path D passing through the convex portion 131p, a configuration in which the convex portion 131p and the electrode 132 are just in contact as shown in FIG. preferable. On the other hand, if paste printing is performed so that the convex portion 131p is laminated on the solid electrolyte body 131, manufacture is facilitated, but the convex portion 131p may not contact the electrode 133 due to printing misalignment as shown in FIG. In this case, compared with the case where the convex portion 131p is in contact with the electrode 133, the contribution by the current path D passing through the convex portion 131p tends to be reduced.
Therefore, as shown in FIG. 3, when viewed from the stacking direction of the solid electrolyte body 131 and the pair of electrodes 132 and 133, the convex portion 131 p is part of the electrode 133 (at least part of the portion facing the electrode 132). It is preferable to overlap with the overlap L because the protrusion 131p and the electrode 133 (132) can be reliably brought into contact with each other even if printing misalignment occurs. The same applies to the protrusion 131p and the electrode 1332.

It goes without saying that the present invention is not limited to the above-described embodiment, but extends to various modifications and equivalents included in the spirit and scope of the present invention.
For example, in the above embodiment, the convex portion 131p is formed in the entire region R, but as shown in FIG. 7, the convex portion 231p may be formed in a part of the region R. In the example of FIG. 7, the convex portion 231p and the electrode 232 are in contact with each other, but the convex portion 231p and each of the electrodes 232 and 233 may not be in contact with each other. In the example of FIG. 7, the electrodes 232 and 233 of the Ip2 cell 230 are separated in a direction that intersects the axis AX direction.

In the above embodiment, the protrusion 131p protrudes toward the electrodes 132 and 133 (surface side) of the solid electrolyte body 131. However, the protrusion 331p corresponds to the electrodes 332 and 332 of the solid electrolyte body 331 as shown in FIG. You may protrude on the opposite side (back side) to 333. In the example of FIG. 8, in addition to the normal current path C that passes through the solid electrolyte body 331 (part of thickness t0) that overlaps with the pair of electrodes 332 and 333, the solid electrolyte body 331 (thickness t1) on the back side of the current path C. A current path D passing through the region of As a result, the cross-sectional area of the solid electrolyte body 331 between the pair of electrodes 332 and 333 increases, and as a result, the specific resistance of the solid electrolyte body 331 decreases.
Also in the example of FIG. 8, the convex portion 331 p overlaps with a part of the electrode 333 (at least a part of the part facing the electrode 332) with an overlap L when viewed from the stacking direction.

Moreover, in the said embodiment, although the convex part 131p was paste-printed on the solid electrolyte body 131, the formation method of the convex part 131p is not restricted to this. The convex portion and the solid electrolyte body (other than the convex portion) may have the same composition. For example, a material having higher oxygen ion conductivity than the solid electrolyte body may be used for the convex portion.
The cell to which the present invention is applied is not limited to the Ip2 cell 130 but may be applied to the Ip1 cell 110 and the Vs cell 120 as long as a pair of electrodes are stacked on the same surface of the solid electrolyte body. When the present invention is applied to the Ip1 cell, the oxygen pump can be controlled with high precision, particularly when the Ip1 cell is energized with a large current. Further, when the present invention is applied to the Vs cell 120, the detection accuracy and responsiveness of the gas to be detected are improved as in the case of the Ip2 cell 130.
Further, the present invention is not limited to the NOx sensor, and can be applied to, for example, an oxygen sensor or an ammonia sensor having at least one cell.

10 Gas sensor element 130, 230, 330 cell (second pump cell)
131, 231, 331 Solid electrolyte body 131p, 231p, 331p Protruding part 132, 232, 332 A pair of electrodes (Ip2 + electrode)
133, 232, 333 Pair of electrodes (Ip2-electrode)
R The region of the shortest distance between the opposed portions of the pair of electrodes L The overlap between the convex portion and the electrode t0 The maximum thickness of the solid electrolyte body t1 The thickness of the convex portion

Claims (2)

In a gas sensor element comprising at least one cell having a solid electrolyte body and a pair of electrodes disposed on the same surface of the solid electrolyte body,
The solid electrolyte body, straddling at least a part of the region to be a shortest distance of the opposing portion between the pair of electrodes, have a thicker convex portion than the maximum thickness of the solid electrolyte body overlapping the pair of electrodes,
The convex portions are formed in all of the regions and are in contact with the pair of electrodes,
One electrode of the pair of electrodes faces a reference oxygen chamber as an isolated small space . 2. The gas sensor element according to claim 1 , wherein the convex portion overlaps part of the pair of electrodes when viewed from the stacking direction of the solid electrolyte body and the pair of electrodes .

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