JP6367708B2 - Gas sensor element and gas sensor - Google Patents

Description

  The present invention relates to a gas sensor element for detecting a specific gas contained in a measurement target gas and a gas sensor including the gas sensor element.

  A gas sensor element for detecting a specific gas (for example, NOx or the like) contained in a measurement target gas (for example, exhaust gas) and a gas sensor including such a gas sensor element are known.

The gas sensor element includes a cell having a plate-type solid electrolyte body and a pair of electrode portions formed on the outer surface of the solid electrolyte body.
For example, a gas sensor element that detects NOx includes, as cells, a first pump cell, a second pump cell, and the like (for example, Patent Document 1).

  The first pump cell adjusts the oxygen concentration of the measurement target gas by pumping and pumping (pumping) oxygen in the measurement target gas (exhaust gas or the like). Then, a second pumping current corresponding to the NOx concentration contained in the measurement target gas whose oxygen concentration is adjusted flows through the second pump cell. The NOx concentration in the measurement target gas can be determined based on the second pumping current.

  In addition, as a structure of the cell in a gas sensor element, one electrode part and the other electrode part are each arrange | positioned on a different surface of a solid electrolyte body so that a pair of electrode part may pinch | interpose a solid electrolyte body, The electrode part of each is arrange | positioned at the position which differs in the same surface of a solid electrolyte body, respectively (for example, patent document 2).

JP 2010-122187 A Special table 2003-508750 gazette

  However, in a cell having a configuration in which the pair of electrode portions are disposed at different positions on the same surface of the solid electrolyte body, the pair of electrode portions is compared with a cell having a configuration in which the pair of electrode portions are disposed so as to sandwich the solid electrolyte body. There is a possibility that the current flowing between the electrode portions of the first and second electrode portions becomes small.

  That is, in a cell having a configuration in which a pair of electrode portions are arranged so as to sandwich the solid electrolyte body, the area of the electrode portions opposed to each other with the solid electrolyte body interposed therebetween is a region involved in the movement of ions in the solid electrolyte body. Therefore, the area where a pair of electrode part overlaps via a solid electrolyte body can be enlarged by making the distance of the direction orthogonal to the thickness direction of a solid electrolyte body in a pair of electrode part close. Thereby, since a large region related to the movement of ions in the solid electrolyte body can be secured, it is possible to increase the current flowing between the pair of electrode portions.

On the other hand, in a cell having a configuration in which a pair of electrode portions are arranged on the same surface of the solid electrolyte body, a region in the vicinity of the pair of electrode portions of the solid electrolyte body mainly includes a region involved in ion migration. However, the electrode portions cannot be overlapped with each other. Therefore, even if the distance between the pair of electrode portions is reduced, it is difficult to ensure a large region related to the movement of ions in the solid electrolyte body. In such a configuration, the current flowing between the pair of electrode portions may be small. Moreover, when the distance between a pair of electrode parts varies for every sensor, the magnitude | size of the electric current which flows between a pair of electrode parts will vary, and there exists a possibility that variation may occur in gas detection accuracy for every sensor.

  In particular, in a gas sensor element for detecting NOx, for example, the second pumping current flowing through the second pump cell in accordance with the NOx concentration is very small. For this reason, when the second pump cell has a configuration in which the pair of electrode portions are respectively disposed on the same surface of the solid electrolyte body, the detection accuracy of the second pumping current is lowered, and the NOx detection accuracy may be lowered. There is.

  Note that a cell having a configuration in which a pair of electrode portions is disposed on the same surface of the solid electrolyte body is compared with a cell having a configuration in which the pair of electrode portions are disposed so as to sandwich the solid electrolyte body. There is an advantage that the dimension in the stacking direction with the electrode portion can be reduced.

  Therefore, the present invention provides a gas sensor element including a cell having a configuration in which a pair of electrode portions are respectively disposed on the same surface of a solid electrolyte body, and can provide a gas sensor element capable of suppressing a decrease in detection accuracy of a specific gas. And it aims at providing a gas sensor provided with such a gas sensor element.

The gas sensor element according to the first aspect of the present invention includes a first measurement chamber, a second measurement chamber, a first pump cell, and a second pump cell.
A gas to be measured is introduced into the first measurement chamber. In the second measurement chamber, a measurement target gas into which oxygen has been pumped or pumped in the first measurement chamber is introduced.

  The first pump cell has a solid electrolyte body and a pair of first electrodes formed on the solid electrolyte body. One electrode of the pair of first electrodes is exposed to the first measurement chamber. The first pump cell pumps or pumps oxygen into the measurement target gas introduced into the first measurement chamber.

  The second pump cell has a solid electrolyte body and a pair of second electrodes formed on the solid electrolyte body. One electrode of the pair of second electrodes is exposed to the second measurement chamber, and the other electrode of the pair of second electrodes is provided outside the second measurement chamber. The 2nd pump cell is constituted so that the 2nd pumping current according to the specific gas concentration in the measuring object gas introduced into the 2nd measurement chamber may flow.

  One electrode and the other electrode of the pair of second electrodes are both formed on the same surface of the solid electrolyte body forming the second pump cell. One electrode is provided as a central electrode disposed on the center side, and the other electrode is provided as a peripheral electrode disposed in at least a part of the peripheral region of the central electrode.

  The central electrode is formed by arranging a conductive material inside the contour without any gap. The peripheral electrode includes two virtual points arranged so as to sandwich the center of gravity of the center electrode, and a connection region connecting the two virtual points.

As described above, the pair of second electrodes in the second pump cell is configured by the central electrode and the surrounding electrodes as described above, so that the pair of second electrodes are each formed in a rectangular shape and are simply arranged adjacent to each other. Compared to the configuration, manufacturing variations are less likely to occur in the distance between the pair of second electrodes. In other words, the relative positional relationship between the center of gravity of the central electrode and the two virtual points in the peripheral electrode is specified, and the peripheral electrode has a connection region, so that the distance between the central electrode and the peripheral electrode is within a certain range. Therefore, manufacturing variations are unlikely to occur in the distance between the pair of second electrodes.

  In particular, since the second pumping current is a very small current, the detection error of the second pumping current can be reduced by suppressing the manufacturing variation of the distance between the pair of second electrodes. Reduction can be suppressed.

  In addition, since the surrounding electrode is arranged in at least a part of the surrounding area of the central electrode, even if a temperature gradient occurs in each part of the entire gas sensor element, a temperature difference occurs between the central electrode and the surrounding electrode. I get tired. For this reason, even if a temperature gradient is generated for each part in the entire gas sensor element, the detection error of the second pumping current due to the temperature gradient can be reduced, so that a decrease in gas detection accuracy in the second pump cell can be suppressed.

  Furthermore, the center electrode is formed with a conductive material disposed without any gap inside the contour, so that the effective electrode area is larger than an electrode having a gap of the conductive material in the same size contour. A large (area of conductive material) can be secured. By ensuring a large effective electrode area in this way, it is possible to increase the second pumping current per unit area in the central electrode arrangement region, and to suppress a decrease in gas detection accuracy in the second pump cell. Further, by providing such a center electrode, a large effective electrode area can be secured, so that an increase in size of the center electrode can be suppressed and an increase in size of the gas sensor element can also be suppressed.

  Therefore, according to this gas sensor element, even when a pair of electrode parts are each provided with the cell of the structure arrange | positioned on the same surface of a solid electrolyte body, the fall of the detection precision of specific gas can be suppressed.

  Note that the peripheral electrode may be formed so as to completely surround the periphery of the center electrode. In that case, the signal path for electrically connecting the central electrode and the external device is not the same surface of the solid electrolyte body, for example, it is solid via a through hole penetrating the solid electrolyte body in the thickness direction. You may form so that it may connect with the back surface of an electrolyte body.

  The gas sensor element described above may include a ceramic layer member disposed between the first measurement chamber and the second measurement chamber. The ceramic layer member is a through hole that connects the first measurement chamber and the second measurement chamber, and includes a through hole through which the measurement target gas introduced from the first measurement chamber to the second measurement chamber passes. Good. Furthermore, the central electrode may be formed so that at least a part thereof is included in a region facing the through hole in the inner surface of the second measurement chamber.

In the gas sensor element having such a configuration, the measurement target gas introduced into the second measurement chamber can easily touch the center electrode, and the gas detection accuracy in the second pump cell can be improved.
In addition, the “region facing the through hole” is, in other words, a region in which the through hole is projected in the through direction (inflow direction of the measurement target gas), and this region is where the measurement target gas flowing from the through hole is projected. It is an area that is easy to reach.

In the gas sensor element described above, the central electrode may be arranged away from the contour of the region facing the second measurement chamber in the solid electrolyte body.
In the gas sensor element having such a configuration, a manufacturing error occurs in the electrode position of the central electrode when the gas sensor element is manufactured, compared to a structure in which the central electrode is in contact with the outline of the region facing the second measurement chamber of the solid electrolyte body. However, it can suppress that a part (especially edge part) of a center electrode will be in the state which is not exposed to a 2nd measurement chamber. That is, even if a manufacturing error occurs in the electrode position of the central electrode, it is possible to suppress an error in the area of the central electrode exposed to the second measurement chamber and to suppress an error in the second pumping current.

Therefore, according to this gas sensor element, since it is possible to suppress an error from occurring in the second pumping current, it is possible to suppress a decrease in gas detection accuracy in the second pump cell.
The gas sensor element described above may include a signal path for electrically connecting the central electrode and an external device. The peripheral electrode may be formed so as to partially surround the central electrode, and the signal path may be disposed so as to pass through a region where the peripheral electrode is not disposed in the peripheral region of the central electrode.

  In the gas sensor element having such a configuration, a signal path for electrically connecting the central electrode and an external device can be arranged on the surface of the solid electrolyte body where the central electrode and the peripheral electrode are formed. .

In the gas sensor element described above, the central electrode may be circular or elliptical, and the surrounding electrode may be annular.
In the gas sensor element having such a configuration, since the surrounding electrode has an annular shape, the surrounding electrode can surround the surrounding area of the central electrode without interruption. In addition, since the central electrode has a circular shape or an elliptical shape, the outer peripheral shape of the central electrode is similar to the inner peripheral shape of the peripheral electrode, and the distance between the central electrode and the peripheral electrode is constant over the entire outer periphery of the central electrode. It becomes easy and the whole outer periphery of a center electrode can be used as an area | region which contributes to the movement of ion.

  A gas sensor according to another aspect of the present invention is a gas sensor including a gas sensor element that detects a specific gas contained in a measurement target gas, and includes any of the gas sensor elements described above as the gas sensor element.

  As described above, the gas sensor including any one of the gas sensor elements described above suppresses a decrease in the detection accuracy of the specific gas even when the pair of electrode portions includes cells each configured to be disposed on the same surface of the solid electrolyte body. it can.

  According to the gas sensor element and the gas sensor of the present invention, it is possible to suppress a decrease in the detection accuracy of a specific gas even when the pair of electrode portions includes cells each configured to be disposed on the same surface of the solid electrolyte body.

It is sectional drawing which shows the state which fractured | ruptured the NOx sensor of embodiment along the axial direction. It is a perspective view which shows a gas sensor element. It is a perspective view which decomposes | disassembles and shows a gas sensor element. It is explanatory drawing showing the internal structure in the front end side of a gas sensor element. It is expansion explanatory drawing showing the shape of a pair of electrode (a center 2nd pump electrode part and a surrounding 2nd pump electrode part) in a 2nd pumping cell. It is explanatory drawing showing the internal structure in the front end side of the 2nd gas sensor element of 2nd Embodiment. (A) is an expansion explanatory view showing the shape of a pair of electrodes (center electrode and surrounding electrode) in the 2nd pump cell of the 1st modification, and (b) is a pair in the 2nd pump cell of the 2nd modification. It is expansion explanatory drawing showing the shape of the electrode (center electrode and surrounding electrode) of this, (c) is an expansion showing the shape of a pair of electrodes (center electrode and surrounding electrode) in the 2nd pump cell of a 3rd modification. It is explanatory drawing.

Embodiments to which the present invention is applied will be described below with reference to the drawings.
In the embodiment described below, the NOx sensor 1 which is a kind of gas sensor is taken as an example. Specifically, a gas sensor mounted on an exhaust pipe of an automobile or various internal combustion engines, which is assembled with a gas sensor element (detection element) for detecting a specific gas (nitrogen oxide: NOx) in the exhaust gas to be measured. An explanation will be given by taking the NOx sensor 1 constructed as an example.

[1. First Embodiment]
[1-1. overall structure]
The overall configuration of the NOx sensor in which the gas sensor element of this embodiment is used will be described with reference to FIG. FIG. 1 is a cross-sectional view showing the internal configuration of the NOx sensor. In FIG. 1, the downward direction in the drawing is the front end side of the NOx sensor, and the upward direction in the drawing is the rear end side of the NOx sensor.

  As shown in FIG. 1, the NOx sensor 1 in this embodiment includes a cylindrical metal shell 5 having a screw portion 3 formed on the outer surface for fixing to an exhaust pipe, and an axis O direction (longitudinal direction of the NOx sensor 1). Direction: vertical direction in FIG. 1) a plate-like gas sensor element 7, a cylindrical ceramic sleeve 9 disposed so as to surround the periphery of the gas sensor element 7 in the radial direction, and an insertion hole 11 penetrating in the direction of the axis O The first separator 13 is disposed with its inner wall surface surrounding the rear end of the gas sensor element 7, and six are disposed between the gas sensor element 7 and the first separator 13 (two in FIG. 1). Only the connection terminal 15 is shown.

  As will be described in detail later, the gas sensor element 7 is formed in a rectangular parallelepiped shape (plate shape) extending in the longitudinal direction, and detects a specific gas (in this case, NOx) included in the measurement target gas at the tip side thereof. A detection unit 17 is provided. Further, the gas sensor element 7 has electrode pads 125, on the first main surface 21 and the second main surface 23 that are in a positional relationship of the front and back of the outer surface on the rear end side (upper side in FIG. 1: rear end portion in the longitudinal direction). 126, 127, 128, 129, and 130 (refer to FIGS. 2 and 3 for details) are formed.

  Different connection terminals 15 are electrically connected to the electrode pads 125, 126, 127, 128, 129, and 130 of the gas sensor element 7, respectively, and the connection terminals 15 are leads arranged inside the sensor from the outside. It is electrically connected to the line 35. As a result, a current path for the current flowing between the external device to which the lead wire 35 is connected and the electrode pads 125, 126, 127, 128, 129, 130 is formed.

  The metal shell 5 has a through-hole 37 that penetrates in the direction of the axis O, and has a substantially cylindrical shape having a shelf 39 that protrudes radially inward of the through-hole 37. In the metal shell 5, the detection unit 17 is disposed on the front end side with respect to the front end of the through hole 37, and the electrode pads 125, 126, 127, 128, 129 and 130 are disposed on the rear end side with respect to the rear end of the through hole 37. In this state, the gas sensor element 7 inserted through the through hole 37 is held.

  Further, inside the through hole 37 of the metal shell 5, an annular ceramic holder 41, a talc ring 43, a talc ring 45, and the above-described ceramic sleeve 9 are provided so as to surround the periphery of the gas sensor element 7 in the radial direction. They are laminated in order from the front end side to the rear end side.

  A caulking packing 49 is disposed between the ceramic sleeve 9 and the rear end portion 47 of the metal shell 5, while a talc ring 43, between the ceramic holder 41 and the shelf 39 of the metal shell 5 is provided. 45 and a metal holder 51 for holding the ceramic holder 41 are arranged. Note that the rear end portion 47 of the metal shell 5 is crimped so as to press the ceramic sleeve 9 toward the front end side via a crimping packing 49.

Further, a metal double protector 55 (for example, stainless steel) covering the protruding portion of the gas sensor element 7 is attached to the outer periphery of the distal end portion 53 of the metal shell 5 by welding or the like.

  On the other hand, an outer cylinder 57 is fixed to the outer periphery on the rear end side of the metal shell 5. Further, a grommet 59 in which six lead wire insertion holes 61 (only two are shown in FIG. 1) is formed in the opening on the rear end side of the outer cylinder 57. Six lead wires 35 (two are shown in FIG. 1) electrically connected to the electrode pads 125, 126, 127, 128, 129, and 130, respectively, are inserted into the six lead wire insertion holes 61. The

  A flange 63 is formed on the outer periphery of the first separator 13, and the flange 63 is fixed to the outer cylinder 57 via a holding member 65. A second separator 67 that is sandwiched between the first separator 13 and the grommet 59 is disposed on the rear end side of the first separator 13. The rear end side of the connection terminal 15 is inserted into the second separator 67.

[1-2. Configuration of gas sensor element]
Next, the structure of the gas sensor element 7 which is the principal part of this embodiment is demonstrated in detail based on FIGS.

FIG. 2 is a perspective view showing the appearance of the gas sensor element 7. In FIG. 2, the downward direction in the drawing is the front end side of the gas sensor element 7, and the upward direction in the drawing is the rear end side of the gas sensor element 7.
As shown in FIG. 2, the gas sensor element 7 is a long plate material extending in the longitudinal direction (Y-axis direction). In FIG. 2, the longitudinal direction is along the direction of the axis O of the gas sensor. 2 is a stacking direction perpendicular to the longitudinal direction, and the X-axis direction is a width direction perpendicular to the longitudinal direction and the stacking direction.

  The gas sensor element 7 is formed in a rectangular parallelepiped shape (plate shape) extending in the longitudinal direction, and a plate-like element portion 71 extending in the longitudinal direction and a plate-like heater 73 extending in the longitudinal direction are laminated. It is configured. The gas sensor element 7 includes a detection unit 17 that detects a specific gas contained in the measurement target gas on the tip side.

  FIG. 3 is an exploded perspective view of the gas sensor element 7. In FIG. 3, the left direction in the drawing is the front end side of the gas sensor element 7, and the right direction in the drawing is the rear end side of the gas sensor element 7. FIG. 4 is an explanatory diagram showing the internal structure on the distal end side of the gas sensor element 7. The explanatory view shown in FIG. 4 is an end view (cut end view) of a portion of the gas sensor element 7 cut along a plane parallel to its longitudinal direction, and shows an end view showing the stacked state of the element portion 71 and the heater 73. It is. In FIG. 4, the left direction in the drawing is the front end side of the gas sensor element 7, and the right direction in the drawing is the rear end side of the gas sensor element 7. Further, in FIG. 4, illustration of an intermediate position in the longitudinal direction of the gas sensor element 7 is omitted, and an electrical connection state between the gas sensor element 7 and an external device (control unit 30) is schematically shown.

  3, the gas sensor element 7 is disposed on one side in the stacking direction (upper side in FIG. 3) and has a plate-like element portion 71 extending in the longitudinal direction, and the opposite side of the element portion 71. A plate-like heater 73 disposed on the back side and extending in the longitudinal direction.

  Among these, the element part 71 has the structure which laminated | stacked the insulator 84e, the 1st solid electrolyte body 81a, the insulator 84a, the 2nd solid electrolyte body 82a, the insulator 84b, and the 3rd solid electrolyte body 83a in this order. The heater 73 has a structure in which insulators 84c and 84d are stacked in this order. Each of these layers is laminated in a direction perpendicular to the longitudinal direction of the gas sensor element 7. Each solid electrolyte body 81 a, 82 a, 83 a has a plate shape extending in the longitudinal direction of the gas sensor element 7.

  A first measurement chamber 86 is formed between the first solid electrolyte body 81a and the second solid electrolyte body 82a. The front end side region of the first measurement chamber 86 is connected to the outside via two first diffusion resistors 85a. A measurement target gas (exhaust gas), which is outside air, is introduced into the gas sensor element 7 from the outside through the first diffusion resistor 85a. In the rear end region, the first measurement chamber 86 is connected to the second measurement chamber 88 formed in the insulator 84b through a through hole 88a formed in the second solid electrolyte body 82a.

  A heating resistor 105 formed of a conductor such as tungsten is provided between the two insulators 84c and 84d. The heating resistor 105 is provided as a part of the heater 73.

  The heater 73 heats up the gas sensor element 7 (in particular, the element unit 71) to a predetermined activation temperature when the heating resistor 105 generates heat by electric power supplied from the outside, and conducts oxygen ions in the solid electrolyte body. Is used to stabilize the operation.

  In the first embodiment, the solid electrolyte bodies 81a, 82a, and 83a are each formed using zirconia having oxygen ion conductivity as a main component. The insulators 84a to 84e are formed using alumina as a main component, and are formed dense enough to prevent permeation (circulation) of fluid such as gas. The first diffusion resistor 85a is formed using a porous material such as alumina, and gas can be circulated. The main component means that “the content of the main material in the ceramic layer is 50 wt% or more”. For example, the solid electrolyte body contains 50 wt% or more of zirconia. Six layers 84e, 81a, 82a, 83a, 84c, 84d of the eight layers of the solid electrolyte body and the insulator are each formed using a raw material sheet (for example, zirconia, alumina, or the like). Ceramic sheet). The two insulators 84a and 84b are formed by screen printing on a ceramic sheet. And the gas sensor element 7 is formed by baking the laminated body obtained by laminating | stacking each layer before baking.

The element unit 71 includes a first pumping cell 81, an oxygen concentration detection cell 82, and a second pumping cell 83.
The first pumping cell 81 includes a first solid electrolyte body 81a and a pair of electrodes (an inner first electrode portion 81c and an outer first electrode portion 81b) arranged so as to sandwich the first solid electrolyte body 81a. The inner first electrode portion 81 c faces the first measurement chamber 86. The inner first electrode portion 81c and the outer first electrode portion 81b are both formed mainly of platinum. The outer first electrode portion 81b is covered with a porous portion 81d (for example, alumina) embedded in a portion of the insulator 84e that faces the outer first electrode portion 81b. The porous portion 81d is configured to allow gas (for example, oxygen) to pass therethrough.

  The oxygen concentration detection cell 82 includes a second solid electrolyte body 82a, and a detection electrode portion 82b and a reference electrode portion 82c arranged so as to sandwich the second solid electrolyte body 82a. Each of the detection electrode part 82b and the reference electrode part 82c is formed mainly of platinum.

  A reference oxygen chamber 87 as a space portion penetrating in the thickness direction of the insulator 84b is formed in a portion of the insulator 84b in contact with the reference electrode portion 82c. The reference oxygen chamber 87 has a C-shaped cross section when viewed in the thickness direction of the insulator 84b, and a porous portion 87a is disposed in a region facing the third solid electrolyte body 83a therein. The other regions are formed as cavities. In addition, a second measurement chamber 88 as a space portion penetrating in the thickness direction of the insulator 84b is formed in an inner region of the reference oxygen chamber 87 in the insulator 84b.

By passing a predetermined weak constant current through the oxygen concentration detection cell 82, oxygen is sent from the first measurement chamber 86 to the reference oxygen chamber 87 via the oxygen concentration detection cell 82. The oxygen concentration in the reference oxygen chamber 87 is maintained at a predetermined concentration. Thereby, the reference oxygen chamber 87 is used as a reference for the oxygen concentration.

  The second pumping cell 83 includes a third solid electrolyte body 83a and a pair of electrodes (a central second pump electrode portion 83b, a peripheral second electrode) disposed on the surface of the third solid electrolyte body 83a facing the second measurement chamber 88. 2 pump electrode portion 83c). The central second pump electrode portion 83b and the surrounding second pump electrode portion 83c are both formed mainly of platinum. The peripheral second pump electrode portion 83c is formed on the surface of the third solid electrolyte body 83a that faces the insulator 84b, and is disposed in a region corresponding to the reference oxygen chamber 87 of the insulator 84b. The surrounding second pump electrode portion 83c faces the reference oxygen chamber 87 so as to face the reference electrode portion 82c. The central second pump electrode portion 83b is formed on the surface of the third solid electrolyte body 83a that faces the insulator 84b, and is disposed in a region corresponding to the second measurement chamber 88 of the insulator 84b.

  Each electrode part 81b, 81c, 82b, 82c, 83b, 83c is formed in a porous shape to the extent that gas can be circulated therein in order to maintain the electrode reaction well. That is, it is porous enough to satisfactorily form a three-phase interface where the gas of the measurement target gas (gas phase such as oxygen or NOx), the electrode part (catalyst phase) and the solid electrolyte body (oxygen ion conduction phase) are in contact Is formed.

  Three electrode pads 125, 126, and 127 are formed on the outer surface on the rear end side of the insulator 84e. In addition, three electrode pads 128, 129, and 130 are formed on the outer surface on the rear end side of the insulator 84d. Each electrode pad 125, 126, 127, 128, 129, 130 is formed, for example, by printing and baking a metallized ink such as Pt on insulators 84e, 84d.

  Each electrode part 81b, 81c, 82b, 82c, 83b, 83c and the heating resistor 105 are electrically connected to the corresponding electrode pads 125, 126, 127, 128, 129, 130 by the wiring units L1 to L6. Yes.

  Specifically, the first electrode pad 125 is electrically connected to the outer first electrode portion 81b by the first wiring unit L1. The second electrode pad 126 is electrically connected to the reference electrode portion 82c by the second wiring unit L2. The third electrode pad 127 is electrically connected to the inner first electrode part 81c, the detection electrode part 82b, and the central second pump electrode part 83b by the third wiring unit L3. The fourth electrode pad 130 is electrically connected to the surrounding second pump electrode portion 83c by the fourth wiring unit L4. The first heater electrode pad 128 is electrically connected to the heating resistor 105 by the first heater wiring unit L5. The second heater electrode pad 129 is electrically connected to the heating resistor 105 by the second heater wiring unit L6. The wiring units L1 to L6 are provided by printing a paste containing platinum as a main component and ceramic (for example, alumina).

  The first wiring unit L1 has a first lead portion 90b and a first through-hole conductor portion 95a. The first lead portion 90b extends in the longitudinal direction from the outer first electrode portion 81b along the first solid electrolyte body 81a. Specifically, the first lead portion 90b extends along the longitudinal direction from the outer first electrode portion 81b toward the rear end side. The first through-hole conductor portion 95a is formed by a through hole H15 that penetrates the insulator 84e in the stacking direction. Specifically, the first through-hole conductor portion 95a is created by forming a conductor on the inner surface of the through hole H15. The first through-hole conductor part 95a has one end connected to the first electrode pad 125 and the other end connected to the first lead part 90b.

The second wiring unit L2 includes a second lead portion 91c, a second through-hole conductor portion 95b,
Have The second lead portion 91c extends in the longitudinal direction from the reference electrode portion 82c toward the rear end side along the second solid electrolyte body 82a. The second through-hole conductor portion 95b is formed by through holes H16, H26, H36, and H46 that penetrate the insulator 84e, the first solid electrolyte body 81a, the insulator 84a, and the second solid electrolyte body 82a in the stacking direction. Specifically, the second through-hole conductor portion 95b is created by forming a conductor on the inner surface of the through holes H16, H26, H36, and H46. The second through-hole conductor portion 95b has one end connected to the second electrode pad 126 and the other end connected to the second lead portion 91c.

  The third wiring unit L3 includes a third lead portion 90c, a fourth lead portion 91b, a fifth lead portion 93b, and a third through-hole conductor portion 95c. The third lead portion 90c extends in the longitudinal direction from the inner first electrode portion 81c toward the rear end side along the first solid electrolyte body 81a. The fourth lead portion 91b extends in the longitudinal direction from the detection electrode portion 82b toward the rear end side along the second solid electrolyte body 82a. The fifth lead portion 93b extends in the longitudinal direction from the central second pump electrode portion 83b toward the rear end side along the third solid electrolyte body 83a. The third through-hole conductor portion 95c includes through holes H17, H27, H37, H47, which penetrate the insulator 84e, the first solid electrolyte body 81a, the insulator 84a, the second solid electrolyte body 82a, and the insulator 84b in the stacking direction. Formed by H57. Specifically, the third through-hole conductor portion 95c is created by forming a conductor on the inner surface of the through holes H17, H27, H37, H47, and H57. The third through-hole conductor portion 95c has one end connected to the third electrode pad 127, an intermediate portion connected to the third lead portion 90c and the fourth lead portion 91b, and the other end connected to the fifth lead portion 93b. The

  As described above, the inner first electrode portion 81c, the detection electrode portion 82b, and the central second pump electrode portion 83b are electrically connected to the common third electrode pad 127. The third electrode pad 127 is connected to the ground potential of the control unit 30.

  The fourth wiring unit L4 includes a sixth lead portion 93c and a fourth through-hole conductor portion 95d. The sixth lead portion 93c extends in the longitudinal direction from the surrounding second pump electrode portion 83c toward the rear end side along the third solid electrolyte body 83a. The fourth through-hole conductor portion 95d is formed by through holes H66, H76, and H86 that penetrate the third solid electrolyte body 83a, the insulator 84c, and the insulator 84d in the stacking direction. Specifically, the fourth through-hole conductor portion 95d is created by forming a conductor on the inner surfaces of the through holes H66, H76, and H86. The fourth through-hole conductor portion 95d has one end connected to the fourth electrode pad 130 and the other end connected to the sixth lead portion 93c.

  The first heater wiring unit L5 includes a first heater lead portion 94a and a first heater through-hole conductor portion 96a. The first heater lead portion 94a extends along the longitudinal direction from the heating resistor 105 toward the rear end side. The first heater through-hole conductor 96a is formed by a through-hole H88 that penetrates the insulator 84d in the stacking direction. Specifically, the first heater through-hole conductor portion 96a is created by forming a conductor on the inner surface of the through hole H88. The first heater through-hole conductor 96a has one end connected to the first heater lead 94a and the other end connected to the first heater electrode pad 128.

The second heater wiring unit L6 includes a second heater lead portion 94b and a second heater through-hole conductor portion 96b. The second heater lead portion 94b extends along the longitudinal direction from the heating resistor 105 toward the rear end side. The second heater through-hole conductor 96b is formed by a through hole H89 that penetrates the insulator 84d in the stacking direction. Specifically, the second heater through-hole conductor portion 96b is created by forming a conductor on the inner surface of the through hole H89. The second heater through-hole conductor 96b has one end connected to the second heater lead 94b and the other end connected to the second heater electrode pad 129. Here, the first heater lead 94a is a plus terminal through which current flows, and the second heater lead 94b is a minus terminal through which current flows.

[1-3. Operation of gas sensor element]
Next, an example of the operation of the gas sensor element 7 will be described.
First, when the control unit 30 is activated by starting the engine, the control unit 30 supplies power to the heater 73. The heater 73 heats the first pumping cell 81, the oxygen concentration detection cell 82, and the second pumping cell 83 to the activation temperature. When each of the cells 81 to 83 is heated to the activation temperature, the control unit 30 causes a current (first pumping current Ip1) to flow through the first pumping cell 81. Accordingly, the first pumping cell 81 flows into the first measurement chamber 86 by moving oxygen between the inner first electrode portion 81c and the outer first electrode portion 81b via the first solid electrolyte body 81a. The oxygen in the measured gas (exhaust gas) is pumped in and out.

  The control unit 30 controls the first pumping current Ip1 energized in the first pumping cell 81 so that the interelectrode voltage (interterminal voltage) of the oxygen concentration detection cell 82 becomes a constant voltage V1 (for example, 425 mV). The voltage of the oxygen concentration detection cell 82 is a value corresponding to the oxygen concentration in the detection electrode portion 82b with reference to the oxygen concentration in the reference oxygen chamber 87. By this control, the oxygen concentration in the first measurement chamber 86 is adjusted to the extent that NOx is not decomposed.

  The measurement target gas whose oxygen concentration is adjusted in the first measurement chamber 86 further flows toward the second measurement chamber 88. The control unit 30 applies an interelectrode voltage (interterminal voltage) to the second pumping cell 83. This voltage is set to a constant voltage such that the NOx gas in the measurement target gas is decomposed into oxygen and nitrogen gas (a voltage higher than the control voltage value of the oxygen concentration detection cell 82, for example, 450 mV). Thereby, NOx in the measurement target gas is decomposed into nitrogen and oxygen.

  A current (second pumping current Ip2) flows through the second pumping cell 83 so that oxygen generated by the decomposition of NOx is pumped from the second measurement chamber 88, and the control unit 30 detects the second pumping current Ip2. Since there is a proportional relationship between the second pumping current Ip2 and the NOx concentration, the NOx concentration in the measurement target gas can be detected by detecting the current value of the second pumping current Ip2.

  The gas sensor element 7 is connected to an external device (control unit 30) via the connection terminal 15 and the lead wire 35. The control unit 30 supplies electric power for heat generation to the heater 73 and transmits / receives a signal to / from each cell (first pumping cell 81, oxygen concentration detection cell 82, second pumping cell 83) of the element unit 71. Thus, the gas sensor element 7 is controlled. In the first embodiment, the control unit 30 is provided as an electronic circuit formed using an operational amplifier or the like. The control unit 30 may be formed using a computer having a CPU, a memory, and the like.

[1-4. Configuration of second pump cell]
As described above, the second pumping cell 83 includes the third solid electrolyte body 83a and a pair of electrodes (central second pump electrode) disposed on the surface of the third solid electrolyte body 83a facing the second measurement chamber 88. Part 83b and surrounding second pump electrode part 83c).

  As can be seen from FIGS. 3 and 4, the central second pump electrode portion 83 b and the surrounding second pump electrode portion 83 c are both formed on the same surface of the third solid electrolyte body 83 a. The central second pump electrode portion 83b is provided as a central electrode disposed on the central side, and the peripheral second pump electrode portion 83c is disposed in at least a part of the peripheral region of the central second pump electrode portion 83b. Provided as a surrounding electrode.

Here, FIG. 5 is an enlarged explanatory view showing the shapes of the central second pump electrode portion 83b and the surrounding second pump electrode portion 83c.
The center second pump electrode portion 83b is formed in a circular shape. In addition, the central second pump electrode portion 83b is formed by arranging a conductive material (a conductive material containing platinum as a main component) inside the outline without a gap.

  The surrounding second pump electrode portion 83c has a shape (C shape) having a notch in a part of the annular shape, and is disposed so as to surround the central second pump electrode portion 83b. The surrounding second pump electrode portion 83c includes two virtual points 83e arranged so as to sandwich the center of gravity 83d of the central second pump electrode portion 83b, and a connection region 83f that connects the two virtual points 83e.

  That is, the surrounding second pump electrode portion 83c is arranged so as to surround a region of at least 180 degrees or more of the entire circumference (360 degrees) around the central second pump electrode portion 83b. In particular, the peripheral second pump electrode portion 83c of the present embodiment is disposed so as to surround a region of 270 degrees or more.

  As shown in FIG. 4, the central second pump electrode portion 83 b is formed so that at least a part thereof is included in a region facing the through hole 88 a on the inner surface of the second measurement chamber 88. The through hole 88a is formed so as to penetrate the second solid electrolyte body 82a in the plate thickness direction, and connects the first measurement chamber 86 and the second measurement chamber 88, and from the first measurement chamber 86 to the second measurement chamber. A gas flow path for the gas to be measured introduced into 88 is formed.

  Further, as shown in FIG. 4, the central second pump electrode portion 83b of the second pumping cell 83 has a region facing the second measurement chamber 88 in the third solid electrolyte body 83a (out of the third solid electrolyte body 83a). The second measurement chamber 88 is disposed away from the outline of the region forming the inner wall surface of the second measurement chamber 88. In other words, the central second pump electrode portion 83b is disposed away from the insulator 84b. The insulator 84b forms an inner wall surface adjacent to the inner wall surface formed by the third solid electrolyte body 83a among the inner wall surfaces of the second measurement chamber 88.

[1-5. effect]
As described above, the gas sensor element 7 in the NOx sensor 1 of the present embodiment includes the central second pump electrode portion 83 b and the surrounding second pump electrode portion 83 c as a pair of electrodes in the second pumping cell 83.

  The central second pump electrode portion 83b and the surrounding second pump electrode portion 83c are all formed on the same surface of the third solid electrolyte body 83a. The central second pump electrode portion 83b is provided as a central electrode, and the peripheral second pump electrode portion 83c is provided as a peripheral electrode disposed in a part of the peripheral region of the central second pump electrode portion 83b.

  The pair of electrodes in the second pumping cell 83 is configured by the central second pump electrode portion 83b and the surrounding second pump electrode portion 83c, so that the pair of electrodes are each formed in a rectangular shape and are simply arranged adjacent to each other. Compared to the configuration, manufacturing variation is less likely to occur between the pair of electrodes. That is, the relative positional relationship between the center of gravity 83d of the central second pump electrode portion 83b and the two virtual points 83e of the peripheral second pump electrode portion 83c is specified, and the peripheral second pump electrode portion 83c has two virtual points. By having the connection region 83f that connects the points 83e, the distance between the central second pump electrode portion 83b and the surrounding second pump electrode portion 83c is within a certain range. For this reason, it is difficult for manufacturing variation to occur in the distance between the central second pump electrode portion 83b and the surrounding second pump electrode portion 83c.

  In particular, since the second pumping current Ip2 flowing through the second pumping cell 83 is a very small current, it is possible to suppress the manufacturing variation in the distance between the central second pump electrode portion 83b and the surrounding second pump electrode portion 83c. Since the detection error of the pumping current Ip2 can be reduced, a decrease in gas detection accuracy (NOx detection accuracy) in the second pumping cell 83 can be suppressed.

  In addition, since the peripheral second pump electrode portion 83c is arranged in at least a part of the peripheral region of the central second pump electrode portion 83b, even if a temperature gradient occurs for each part in the entire gas sensor element 7, A temperature difference between the central second pump electrode portion 83b and the surrounding second pump electrode portion 83c is unlikely to occur. For this reason, even if a temperature gradient occurs for each part in the entire gas sensor element 7, the detection error of the second pumping current Ip2 caused by the temperature gradient can be reduced, so that the gas detection accuracy (NOx) in the second pumping cell 83 is reduced. Decrease in detection accuracy can be suppressed.

  Furthermore, since the central second pump electrode portion 83b is formed with the conductive material arranged without a gap inside the contour, compared to an electrode having a gap of the conductive material in the contour of the same size. A large effective electrode area (area of the conductive material) can be secured. By ensuring a large effective electrode area in this way, the second pumping current Ip2 per unit area in the arrangement region of the central second pump electrode portion 83b can be increased, and the gas detection accuracy in the second pumping cell 83 can be increased. A decrease in (NOx detection accuracy) can be suppressed. Furthermore, since the effective second electrode area can be ensured by providing such a central second pump electrode portion 83b, an increase in size of the central second pump electrode portion 83b can be suppressed, and an increase in size of the gas sensor element 7 can also be suppressed.

  Therefore, according to the gas sensor element 7, a pair of electrode portions (the central second pump electrode portion 83b and the surrounding second pump electrode portion 83c) are arranged on the same surface of the third solid electrolyte body 83a (first cell). Even when the two pumping cells 83) are provided, it is possible to suppress a decrease in the detection accuracy of the specific gas (NOx).

  The gas sensor element 7 includes a second solid electrolyte body 82a (ceramic layer member) disposed between the first measurement chamber 86 and the second measurement chamber 88. The second solid electrolyte body 82a A through-hole 88a that connects the first measurement chamber 86 and the second measurement chamber 88, and includes a through-hole 88a through which the measurement target gas introduced from the first measurement chamber 86 into the second measurement chamber 88 passes. The central second pump electrode portion 83b is formed so that at least a part thereof is included in a region of the inner surface of the second measurement chamber 88 facing the through hole 88a.

  In the gas sensor element 7 having such a configuration, the measurement target gas (exhaust gas) introduced into the second measurement chamber 88 can easily touch the central second pump electrode portion 83b, and the gas detection accuracy (NOx) in the second pumping cell 83 is increased. Detection accuracy).

  Further, the central second pump electrode portion 83b of the second pumping cell 83 is a region facing the second measurement chamber 88 in the third solid electrolyte body 83a (inside the second measurement chamber 88 of the third solid electrolyte body 83a). The wall is formed at a distance from the outline of the region forming the wall. In other words, the central second pump electrode portion 83b is disposed away from the insulator 84b.

  The gas sensor element 7 having such a configuration is more centralized at the time of manufacturing the gas sensor element than the configuration in which the central second pump electrode portion is in contact with the contour of the region facing the second measurement chamber 88 in the third solid electrolyte body 83a. Even if a manufacturing error occurs in the electrode position of the second pump electrode portion 83 b, it is possible to prevent a part (particularly, an end portion) of the central second pump electrode portion 83 b from being exposed to the second measurement chamber 88. In other words, it is possible to suppress a part (particularly, an end portion) of the central second pump electrode portion 83b from being sandwiched between the insulator 84b and the third solid electrolyte body 83a.

  That is, the gas sensor element 7 can suppress the occurrence of an error in the area of the central second pump electrode portion 83b exposed to the second measurement chamber 88 even if a manufacturing error occurs in the electrode position of the central second pump electrode portion 83b. At the same time, the occurrence of an error in the second pumping current Ip2 can be suppressed.

  Therefore, according to the gas sensor element 7, since it can suppress that an error arises in the 2nd pumping current Ip2, the fall of the gas detection accuracy (NOx detection accuracy) in the 2nd pumping cell 83 can be suppressed.

  Since the NOx sensor 1 of the present embodiment includes the gas sensor element 7 as described above, the pair of electrode portions (the central second pump electrode portion 83b and the surrounding second pump electrode portion 83c) are each a third solid electrolyte body 83a. Even when a cell (second pumping cell 83) configured to be disposed on the same surface is provided, it is possible to suppress a decrease in detection accuracy of the specific gas (NOx).

[1-6. Correspondence with Claims]
Here, the correspondence of the words in the claims and the present embodiment will be described.
The NOx sensor 1 corresponds to an example of a gas sensor, the gas sensor element 7 corresponds to an example of a gas sensor element, the first measurement chamber 86 corresponds to an example of a first measurement chamber, and the second measurement chamber 88 corresponds to an example of a second measurement chamber. It corresponds to an example.

The first pumping cell 81 corresponds to an example of a first pump cell, and the outer first electrode portion 81b and the inner first electrode portion 81c correspond to an example of a pair of first electrodes.
The second pumping cell 83 corresponds to an example of a second pump cell, and the central second pump electrode portion 83b and the surrounding second pump electrode portion 83c correspond to an example of a pair of second electrodes. The central second pump electrode portion 83b corresponds to an example of the central electrode, the peripheral second pump electrode portion 83c corresponds to an example of the peripheral electrode, and the virtual point 83e of the peripheral second pump electrode portion 83c corresponds to an example of the virtual point. And the connection area | region 83f of the surrounding 2nd pump electrode part 83c is equivalent to an example of a connection area | region.

The second solid electrolyte body 82a corresponds to an example of a ceramic layer member, and the through hole 88a corresponds to an example of a through hole.
[2. Other Embodiments]
As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it is possible to implement in various aspects.

  For example, in the above-described embodiment, the gas sensor element 7 having a configuration in which at least a part of the center second pump electrode portion 83b is included in the region facing the through hole 88a in the inner surface of the second measurement chamber 88 has been described. The gas sensor element is not limited to such a configuration. In the above embodiment, the gas sensor element 7 having a configuration in which the reference electrode portion 82c of the oxygen concentration detection cell 82 is disposed in the entire region of the reference oxygen chamber 87 that faces the surrounding second pump electrode portion 83c has been described. The gas sensor element of the present invention is not limited to such a configuration.

  Specifically, as in the second gas sensor element 107 of the second embodiment shown in FIG. 6, the central second pump electrode portion 83b is arranged not to be included in the region facing the through hole (deformed through hole 188a). It may be configured. The deformed through hole 188a is formed so as to penetrate the deformed second solid electrolyte body 182a in the plate thickness direction, and is formed at a position connected to the rear end side of the second measurement chamber 88. Even in such a configuration, the measurement target gas can be introduced into the second measurement chamber 88, and the second pumping cell 83 including the central second pump electrode portion 83b and the surrounding second pump electrode portion 83c allows the specific gas (NOx). ) Can be detected.

  Further, like the second gas sensor element 107, the reference electrode portion (deformed reference electrode portion 182c) of the oxygen concentration detection cell is disposed in a part of the reference oxygen chamber 87 in a region facing the surrounding second pump electrode portion 83c. It may be a configuration. In addition, the deformation | transformation detection electrode part 182b and the deformation | transformation reference electrode part 182c are formed in semicircle shape instead of the circular shape like the above-mentioned detection electrode part 82b and the reference electrode part 82c. Further, the deformation detection electrode part 182b and the deformation reference electrode part 182c are located in the region of the third solid electrolyte body 83a on the tip side from the center of gravity 83d of the central second pump electrode part 83b in the longitudinal direction of the second gas sensor element 107. Has been placed. Even with such a configuration, an oxygen concentration detection cell for maintaining the oxygen concentration of the reference oxygen chamber 87 at a predetermined concentration can be realized.

  The second gas sensor element 107 includes, in the gas sensor element 7, a modified second solid electrolyte body 182a instead of the second solid electrolyte body 82a, a deformation detection electrode section 182b instead of the detection electrode section 82b, and a reference Instead of the electrode portion 82c, a deformation reference electrode portion 182c is provided. The second gas sensor element 107 is configured by laminating a deformation element portion 171 and a heater 73.

Next, the pair of second electrodes in the second pump cell is not limited to the configuration of the central second pump electrode portion 83b and the surrounding second pump electrode portion 83c.
For example, as in the first modification shown in FIG. 7A, the pair of second electrodes in the second pump cell are disposed around the deformed central electrode part 183b and the deformed center electrode part 183b which are not circular but rectangular. And a deformed peripheral electrode portion 183c. When the area of the central electrode can be secured larger than that of the circular shape by using the rectangular deformed central electrode portion 183b, an effective electrode area (area of the conductive material) can be obtained by adopting such a configuration. A large amount can be secured and the second pumping current Ip2 per unit area can be increased, so that a decrease in the detection accuracy of the specific gas (NOx) can be suppressed.

  Further, as in the second modification shown in FIG. 7B, the pair of second electrodes in the second pump cell is different from the central second pump electrode portion 83b of the first embodiment in the connection position with the lead portion. You may comprise the 2nd deformation | transformation center electrode part 283b and the 2nd deformation | transformation surrounding electrode part 283c from which the connection position with a lead part differs from the surrounding 2nd pump electrode part 83c of 1st Embodiment. The second deformation peripheral electrode portion 283c has a shape (C shape) having a notch in a part of the annular shape, and an end portion thereof is connected to the lead portion (sixth lead portion 93c). In other words, the connection position of each of the center electrode and the peripheral electrode with the lead portion is not limited to a specific position, and can be set to an arbitrary position.

  Further, as in the third modified embodiment shown in FIG. 7C, the pair of second electrodes in the second pump cell is formed of a rectangular third modified central electrode portion 383b and a periphery of the third modified central electrode portion 383b. You may comprise with the 3rd deformation | transformation surrounding electrode part 383c arrange | positioned at the area | region corresponding to 3 sides. That is, the peripheral electrode is not limited to the configuration arranged in the region corresponding to all four sides of the third modified central electrode portion 383b, and sandwiches the center of gravity 83d of the central electrode (third modified central electrode portion 383b). Any configuration can be adopted as long as the configuration includes two virtual points 83e arranged in the region and a connection region 83f that connects the two virtual points 83e.

  Further, although not shown, the pair of second electrodes in the second pump cell may be constituted by a central electrode and a peripheral electrode formed so as to completely surround the periphery of the central electrode. In this case, the lead portion (signal path) of the central electrode may be formed so as to be connected to the back surface of the solid electrolyte body through a through hole penetrating the solid electrolyte body in the thickness direction.

Further, in the gas sensor element 7 of the first embodiment, the reference oxygen chamber 87 has a porous portion 87a disposed in a region facing the third solid electrolyte body 83a in the inside thereof, and other regions are formed as cavities. However, a configuration in which the porous portion is disposed throughout the reference oxygen chamber may be used.

  Further, the gas sensor element 7 of the first embodiment has a configuration in which the entire surrounding electrode (the surrounding second pump electrode portion 83c) is exposed inside the reference oxygen chamber 87, but a part of the surrounding electrode is the reference oxygen chamber. The structure exposed inside may be sufficient. For example, the reference oxygen chamber is formed in a region corresponding to the deformed reference electrode portion 182c of the second gas sensor element 107 (a region on the tip side of the center of gravity 83d of the central second pump electrode portion 83b), and the peripheral electrode (the peripheral second electrode). A part of the pump electrode part 83c) may be exposed inside the reference oxygen chamber, and the other part may be sandwiched between the insulator 84b and the third solid electrolyte body 83a.

  DESCRIPTION OF SYMBOLS 1 ... NOx sensor, 7 ... Gas sensor element, 30 ... Control part, 71 ... Element part, 73 ... Heater, 81 ... 1st pumping cell, 81a ... 1st solid electrolyte body, 81b ... Outside 1st electrode part, 81c ... Inside 1st electrode part, 81d ... Porous part, 82 ... Oxygen concentration detection cell, 82a ... 2nd solid electrolyte body, 82b ... Detection electrode part, 82c ... Reference electrode part, 83 ... 2nd pumping cell, 83a ... 3rd solid Electrolyte body, 83b ... center second pump electrode part, 83c ... peripheral second pump electrode part, 83d ... center of gravity, 83e ... virtual point, 83f ... connection region, 86 ... first measurement chamber, 87 ... reference oxygen chamber, 87a ... Porous part, 88 ... second measurement chamber, 88a ... through hole, 107 ... second gas sensor element, 171 ... deformation element part, 182a ... deformed second solid electrolyte body, 182b ... deformation detection electrode part, 182c ... deformation reference electrode Part 183b ... Deformed central electrode part, 183c ... Deformed peripheral electrode part, 188a ... Deformed through-hole, 283b ... Second modified central electrode part, 283c ... Second modified peripheral electrode part, 383b ... Third modified central electrode part, 383c ... First 3 deformation surrounding electrode part.

Claims (6)

A first measurement chamber into which a measurement target gas is introduced;
A second measurement chamber into which the measurement target gas into which oxygen has been pumped or pumped in the first measurement chamber is introduced;
A solid electrolyte body and a pair of first electrodes formed on the solid electrolyte body, wherein one electrode of the pair of first electrodes is exposed to the first measurement chamber; A first pump cell for pumping or pumping oxygen to the measurement target gas introduced in
A solid electrolyte body and a pair of second electrodes formed on the solid electrolyte body, wherein one electrode of the pair of second electrodes is exposed to the second measurement chamber, and the other electrode is A second pump cell provided outside the second measurement chamber and through which a second pumping current according to a specific gas concentration in the measurement target gas introduced into the second measurement chamber flows;
A gas sensor element comprising:
The one electrode and the other electrode of the pair of second electrodes are both formed on the same surface of the solid electrolyte body forming the second pump cell, and the one electrode is disposed on the center side. Provided as a central electrode, and the other electrode is provided as a peripheral electrode disposed in at least a part of a peripheral region of the central electrode,
The central electrode is formed by arranging a conductive material inside the contour without a gap,
The peripheral electrode includes two virtual points arranged so as to sandwich the center of gravity of the central electrode, and a connection region connecting the two virtual points ,
The specific gas concentration is a NOx concentration.
Gas sensor element. A ceramic layer member disposed between the first measurement chamber and the second measurement chamber;
The ceramic layer member is a through hole that connects the first measurement chamber and the second measurement chamber, and the through hole through which the measurement target gas introduced from the first measurement chamber into the second measurement chamber passes. With
The central electrode is formed so that at least a part thereof is included in a region facing the through hole in the inner surface of the second measurement chamber.
The gas sensor element according to claim 1. The central electrode is disposed away from the outline of the region facing the second measurement chamber in the solid electrolyte body of the second pump cell .
The gas sensor element according to claim 1 or 2. A signal path for electrically connecting the central electrode and an external device;
The peripheral electrode is formed to partially surround the central electrode;
The signal path is disposed so as to pass through a region where the peripheral electrode is not disposed in a peripheral region of the central electrode.
The gas sensor element according to any one of claims 1 to 3. The central electrode is circular or elliptical,
The surrounding electrode is annular.
The gas sensor element according to any one of claims 1 to 3. A gas sensor including a gas sensor element for detecting a specific gas contained in a measurement target gas,
As the gas sensor element, comprising the gas sensor element according to any one of claims 1 to 5,
A gas sensor.