JP2017211186A - Gas sensor element and gas sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the mechanical strength of a multilayer gas sensor element containing a space.SOLUTION: A gas sensor element 4 has a multilayer structure including: a solid electrolyte layer 430; a detection electrode 441 on one surface of the solid electrolyte layer exposed to a measurement target gas; a reference electrode 442 on the other surface of the solid electrolyte layer exposed to a reference gas; a first layer 422 for forming a reference gas flow path for introducing the reference gas into the reference electrode; and a reinforcement layer 80 containing tetragonal zirconia in at least one of the two opposed inner surfaces of the reference gas flow path in the multilayer direction of the gas sensor element.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a gas sensor element and a gas sensor.

  Conventionally, a gas sensor for detecting the concentration of a specific gas component in exhaust gas discharged from an internal combustion engine of an automobile or the like is known. A gas sensor element used for a gas sensor generally includes a solid electrolyte layer, a reference electrode and a detection electrode disposed on each surface of the solid electrolyte layer, and a reference gas (for example, air) is supplied to the reference electrode. A gas to be measured is supplied to the detection electrode. As such a gas sensor element, for example, a laminated gas sensor element having a plate-like outer shape as a whole, which is composed of a laminated body in which an insulating layer, a heater and the like are further laminated together with the above-described solid electrolyte layer having a pair of electrodes. Are known.

  In such a gas sensor element, it is desired to increase the strength of the gas sensor element to suppress breakage. As one of the problems related to the strength of the gas sensor element, in the manufacturing process of the gas sensor element, the debris from the setter for firing adheres to the surface of the gas sensor element, and the alumina constituting the gas sensor element and the deagglomerated debris form during firing. The problem of reacting was known. That is, when alumina reacts with crushed waste, the alumina grows abnormally, resulting in a problem that the bending strength of the sensor element is lowered. And the structure which provides the coating layer containing a tough material in the specific location of the outer surface of a sensor element with respect to such a problem is proposed. Thereby, even if it is a case where a shattering waste adheres to the surface of a gas sensor element, it is possible to ensure the bending strength of a gas sensor element (for example, refer to patent documents 1).

Patent 05275427

  As a laminated gas sensor element, a configuration is known in which an air introduction hole for introducing the air as a reference gas to the reference electrode is provided in the laminated body. Thus, when providing a space inside a laminated body, the intensity | strength of the area | region in which the space was provided in the laminated body falls. Therefore, when an external force is applied when the gas sensor element is assembled in the gas sensor or in the process of using the gas sensor after the gas sensor element is assembled, the gas sensor element is easily damaged. Therefore, it has been desired to increase the mechanical strength of the gas sensor element even when a space such as an air introduction hole is provided inside.

  The present invention has been made to solve the above-described problems, and can be realized as the following forms.

(1) According to one aspect of the present invention, a solid electrolyte layer, a detection electrode provided on one surface of the solid electrolyte layer and exposed to a gas to be measured, and provided on the other surface of the solid electrolyte layer There is provided a gas sensor element in which a plurality of layers including a reference electrode exposed to a reference gas and a first layer for forming a reference gas channel for introducing the reference gas into the reference electrode are stacked. The In this gas sensor element, a reinforcing layer containing tetragonal zirconia is provided on at least one of the two inner wall surfaces facing each other in the stacking direction of the gas sensor elements among the inner wall surfaces of the reference gas flow path.
According to the gas sensor element of this aspect, in the gas sensor element, by forming the reference gas flow path using the first layer, the strength of the portion where the strength of the gas sensor element is reduced is increased, and the bending strength of the gas sensor element is increased. be able to.

(2) In the gas sensor element of the above aspect, the gas sensor element extends from the outer surface of the gas sensor element toward the reference gas flow path in the stacking direction and introduces the reference gas into the reference gas flow path. A first through-hole that forms a flow path of the first through-hole; the reinforcing layer may be formed in a region that overlaps the first through-hole when projected in the stacking direction. According to the gas sensor element of this form, the strength reduction of the gas sensor element due to the provision of the first through hole can be further suppressed.

(3) In the gas sensor element of the above aspect; the gas sensor element includes at least one selected from the detection electrode, the reference electrode, and a heater for heating the solid electrolyte layer, and an outer surface of the gas sensor element A second through hole extending in the laminating direction is formed to form a path for electrically connecting the electrode terminal portion provided in the electrode terminal portion; and when the reinforcing layer is projected in the laminating direction It may be formed in a region overlapping with the second through hole. According to the gas sensor element of this form, the strength reduction of the gas sensor element due to the provision of the second through hole can be further suppressed.

(4) In the gas sensor element according to the above aspect, the reinforcing layer includes the two inner wall surfaces facing each other in the reference gas flow path, and each of the two inner wall surfaces to the outer surface of the gas sensor element. It is good also as providing in the surface where the thickness of the direction which mutually spaces apart in the lamination direction is smaller. According to the gas sensor element of this embodiment, the effect of increasing the strength of the gas sensor element can be enhanced by providing the reinforcing layer on the side where the strength is further insufficient.

(5) In the gas sensor element of the above aspect, the reference gas flow path is formed between the first layer and a layer adjacent to the first layer, and the reinforcing layer is the adjacent layer It is good also as forming in the surface of the side which touches the said 1st layer in the layer to carry out. According to the gas sensor element of this aspect, the reinforcing layer can be easily formed by providing the reinforcing layer on the surface of the adjacent layer that is in contact with the first layer.

(6) In the gas sensor element of the above aspect, when the reinforcing layer and the reference gas channel are projected in the stacking direction, the reinforcing layer has the reference in the width direction orthogonal to the direction in which the reference gas channel extends. It is good also as forming over the area | region beyond the outer edge of a gas flow path. According to the gas sensor element of this embodiment, since the strength can be secured by the reinforcing layer even at the corner portion where stress is particularly concentrated on the inner wall surface of the reference gas flow path, the effect of reinforcing the gas sensor element can be enhanced.

(7) In the gas sensor element of the above aspect, the reinforcing layer may be provided so as not to be exposed on an outer surface of the gas sensor element. According to the gas sensor element of this aspect, even when liquid water may come into contact with the outer surface of the gas sensor element when the gas sensor element is incorporated in the gas sensor, the gas sensor element is damaged due to contact with the liquid water. In addition, it is possible to suppress a decrease in sensitivity of the gas sensor due to a decrease in temperature of the gas sensor element.

(8) The gas sensor element of the said form WHEREIN: The said gas sensor element is good also as providing the layer containing 50 mass% or more of alumina as a base material layer laminated | stacked with the said solid electrolyte layer. According to the gas sensor element of this aspect, when the gas sensor element is incorporated in the gas sensor and used, it is possible to suppress the occurrence of a temperature gradient in the gas sensor element.

(9) According to another aspect of the present invention, a gas sensor is provided that includes a gas sensor element for detecting a specific gas in a gas to be measured and a metal shell that holds the gas sensor element. This gas sensor includes the gas sensor element according to any one of (1) to (8) as the gas sensor element. According to the gas sensor of this aspect, since the strength of the gas sensor element is increased, the durability of the gas sensor can be improved.

(10) The gas sensor of the above aspect further includes a holding portion that presses and holds the gas sensor element, and the reinforcing layer is provided at least in a portion where the gas sensor element is pressed and held by the holding portion. Also good. According to the gas sensor of this aspect, the effect of increasing the strength of the gas sensor element and increasing the durability of the gas sensor can be obtained particularly remarkably.

(11) In the gas sensor element of the above aspect, the reinforcing layer may be provided so as not to be exposed to a region in contact with the gas to be measured on the outer surface of the gas sensor element. According to the gas sensor of this form, it is possible to suppress the reinforcing layer from coming into contact with liquid water during use of the gas sensor. Therefore, it is possible to suppress the gas sensor element from being damaged due to the reinforcing layer coming into contact with liquid water, and the gas sensor sensitivity from being lowered due to the temperature drop of the gas sensor element.

  The present invention can be realized in various modes other than the above. For example, it is realizable with forms, such as a manufacturing method of a gas sensor element, a manufacturing method of a gas sensor, and a reinforcement method of a gas sensor element.

It is sectional drawing which shows the whole structure of a gas sensor. It is a disassembled perspective view of a sensor element. It is a top view of a sensor element. It is sectional drawing of a sensor element. It is a top view of a sensor element. It is a top view of a sensor element. It is sectional drawing of a sensor element. It is sectional drawing of a sensor element.

A. First embodiment:
A-1. Gas sensor configuration:
FIG. 1 is a cross-sectional view showing an overall configuration of a gas sensor 2 as a first embodiment of the present invention. This gas sensor 2 is fixed to an exhaust pipe of an internal combustion engine (engine) (not shown), and measures the concentration of a specific gas contained in the exhaust gas that is the gas to be measured. The gas sensor 2 of the present embodiment is a sensor that measures the oxygen gas concentration. FIG. 1 shows a cross section including the axis CL of the gas sensor 2 and parallel to the axial direction CD which is a direction parallel to the axis CL. The axis CL extends in the longitudinal direction of the gas sensor 2 at the center of the gas sensor 2. In the following description, the lower side with respect to the paper surface of FIG. 1 is referred to as “front end AS”, the upper side is referred to as “rear end BS”, and the direction perpendicular to the axis CL through the axis CL is referred to as “radial direction”. "

  The gas sensor 2 includes a plate-like sensor element 4 extending in the axial direction CD, a front end side separator 66 inserted through the rear end side BS of the sensor element 4, and a rear end side disposed on the rear end side BS of the front end side separator 66. A metal shell that surrounds the periphery of the sensor element 4 at a position closer to the front end side AS than the front end side separator 66, and the separator 63, the metal terminal member 10 that contacts the electrode terminal portion 30 formed on the rear end side BS of the sensor element 4. 38. Four electrode terminal portions 30 and four metal terminal members 10 are provided. In FIG. 1, only two electrode terminal portions 30 and metal terminal members 10 are shown.

  The sensor element 4 outputs a signal for detecting the oxygen concentration in the exhaust gas that is the measurement target gas. In the plate-like sensor element 4, the first plate surface 21 and the second plate surface 23 that is the back surface of the first plate surface 21 constitute a main surface that is the largest surface. As will be described later, the sensor element 4 is configured by stacking a plurality of sheet-like members. In FIG. 1, the stacking direction of the sheet-like members described above, which is a direction orthogonal to the axial direction CD, is shown as a stacking direction LD. The first plate surface 21 and the second plate surface 23 are outer surfaces of the sensor element 4 that are orthogonal to the stacking direction LD.

  The sensor element 4 includes a detection unit 8 that is positioned on the front end side AS and exposed to the gas to be measured, and four electrode terminal units 30 that are positioned on the rear end side BS and that the corresponding metal terminal member 10 contacts. Have. Two of the four electrode terminal portions 30 are formed on the first plate surface 21, and the remaining two are formed on the second plate surface 23. The sensor element 4 is fixed inside the metal shell 38 with the detection unit 8 protruding from the front end of the metal shell 38 and the electrode terminal 30 protruding from the rear end of the metal shell 38. Details of the sensor element 4 will be described later. In the present embodiment, the detection unit 8 on the tip side AS of the sensor element 4 is covered with a porous protective layer, and impurities (for example, water) contained in the gas to be measured are detected by the detection unit. 8 is suppressed. The “sensor element 4” in the present embodiment functions as a “gas sensor element”.

  The front end side separator 66 and the rear end side separator 63 are formed of an insulating member such as alumina. The front end side separator 66 is substantially cylindrical. The front end side separator 66 is disposed so as to surround the rear end side portion of the sensor element 4 where the electrode terminal portion 30 is located. The front end separator 66 includes an insertion portion 65a for inserting the rear end portion of the sensor element 4, and four groove portions 65b (only two are shown in FIG. 1) formed on the inner wall surface of the insertion portion 65a. Have. The four groove portions 65 b extend in the axial direction CD and penetrate from the front end side end surface 68 to the rear end side end surface 62 of the front end side separator 66. The corresponding metal terminal member 10 is inserted through the four groove portions 65b. Moreover, the front end side separator 66 has a flange portion 67 protruding radially outward at the rear end side BS. The rear end side separator 63 is formed with a through hole penetrating the inside along the axial direction CD, and the rear end portion of the metal terminal member 10 is inserted into the through hole.

  The metal terminal member 10 is positioned between the sensor element 4 and the front end side separator 66 in the stacking direction LD in a state where the metal terminal member 10 is inserted through the corresponding groove 65b. The metal terminal member 10 is sandwiched between the sensor element 4 and the front end side separator 66. The metal terminal member 10 forms a current path between the sensor element 4 and an external device for calculating the oxygen concentration. The rear end portion of the metal terminal member 10 is electrically connected to the lead wire 46 disposed from the outside to the inside of the gas sensor 2 in the rear end side separator 63, and the sensor element in the front end side separator 66. 4 electrode terminal portions 30 are electrically connected. Four lead wires 46 are provided corresponding to the number of electrode terminal portions 30, and are electrically connected to an external device (only two are shown in FIG. 1).

  The metal shell 38 is a substantially cylindrical metal member. The metal shell 38 includes a through hole 54 that penetrates in the axial direction CD and a shelf 52 that protrudes radially inward of the through hole 54. In the metal shell 38, the detection portion 8 is positioned on the front end side AS with respect to the opening on the front end side AS of the through hole 54, and the electrode terminal portion 30 is positioned on the rear end side BS with respect to the opening on the rear end side BS of the through hole 54 Thus, the sensor element 4 is held in the through hole 54. The shelf 52 is formed as an inwardly tapered surface having an inclination with respect to a plane perpendicular to the axial direction CD. A screw portion 39 for fixing the gas sensor 2 to the exhaust pipe is formed on the outer surface of the metal shell 38.

  Inside the through hole 54, an annular ceramic holder 53, a powder-filled layer (talc ring) 56, and a ceramic sleeve 6 are provided from the front end side AS to the rear end so as to surround the radial periphery of the sensor element 4. It is laminated in this order over the side BS. Further, a caulking packing 57 is disposed between the ceramic sleeve 6 and the rear end portion 40 of the metal shell 38. The rear end portion 40 of the metallic shell 38 is crimped so as to press the ceramic sleeve 6 against the distal end side via the crimping packing 57.

  The gas sensor 2 further includes an outer cylinder 44 fixed to the outer periphery of the metal shell 38 at the rear end BS of the metal shell 38, a holding member 69 for holding the front-end separator 66, and a rear end portion of the outer cylinder 44. And a grommet 50 disposed on the outer edge of the metal shell 38 and an outer protector 45 and an inner protector 43 fixed to the outer periphery of the front end AS.

  The outer cylinder 44 is a substantially cylindrical metal member. The outer periphery of the distal end AS of the outer cylinder 44 is attached to the metal shell 38 by laser welding or the like. The outer cylinder 44 has a reduced outer diameter at the rear end BS, and a grommet 50 is fitted into the reduced diameter opening. The grommet 50 is formed with four lead wire insertion holes 61 (only two are shown in FIG. 1) through which the lead wire 46 is inserted.

  The grommet 50 is further formed with a through hole 58 that penetrates the central portion along the axis CL. The through-hole 58 is loaded with a filter unit 59 composed of a filter and a metal cylindrical member for fixing the filter, and the atmosphere is introduced into the outer cylinder 44 through the filter unit 59. Thereby, the space in the outer cylinder 44 is filled with air.

  The holding member 69 is a metal cylindrical member. The holding member 69 is fixed to the outer cylinder 44 and positioned in the outer cylinder 44. The holding member 69 holds the front end side separator 66 by contacting the flange portion 67 of the front end side separator 66 at the rear end side BS.

  The external protector 45 and the internal protector 43 are bottomed cylindrical shapes and are metal members having a plurality of holes. The external protector 45 and the internal protector 43 are attached to the outer periphery of the front end AS of the metal shell 38 by laser welding or the like. The external protector 45 and the internal protector 43 protect the sensor element 4 by covering the detection unit 8. The gas to be measured flows into the internal protector 43 by passing through a plurality of holes provided in the external protector 45 and the internal protector 43.

A-2. Sensor element configuration:
FIG. 2 is an exploded perspective view of the sensor element 4. The axial direction CD, the front end side AS, the rear end side BS, and the stacking direction LD shown in FIG. 2 correspond to the directions shown in FIG. The sensor element 4 includes an insulating layer 421, a detection electrode 441, a solid electrolyte layer 430, a reinforcing layer 80, a reference electrode 442, a gas flow path forming layer 422, an insulating layer 423, a heater 450, and an insulating layer. 424, and these constituent members are stacked in this order along the stacking direction LD. The insulating layer 421, the solid electrolyte layer 430, the gas flow path forming layer 422, and the insulating layers 423 and 424 are rectangular sheet-like members and have substantially the same outer shape.

  In FIG. 2, four electrode terminal portions 30 (specifically, electrode terminal portions 31 to 34) are also illustrated. Each electrode terminal portion 30 is used for electrical connection of the sensor element 4. Each electrode terminal part 30 is formed using platinum, rhodium, etc., for example, and is a substantially rectangular shape. The electrode terminal portion 30 can be formed, for example, by screen printing a paste mainly composed of platinum or the like on the insulating layer 421 or the insulating layer 424. The electrode terminal portions 31 and 32 are formed side by side in the direction perpendicular to the axial direction CD on the first plate surface 21 of the insulating layer 421 on the rear end BS of the sensor element 4. The electrode terminal portions 33 and 34 are formed side by side in a direction perpendicular to the axial direction CD on the second plate surface 23 of the insulating layer 424 at the rear end BS of the sensor element 4. In FIG. 2, a direction parallel to the first plate surface 21 and the second plate surface 23 and perpendicular to the axial direction CD is shown as a width direction WD.

The solid electrolyte layer 430 functions as an oxygen concentration cell that detects the oxygen concentration in the exhaust gas together with the detection electrode 441 and the reference electrode 442. The solid electrolyte layer 430 is composed of a solid electrolyte having oxide ion conductivity (oxygen ion conductivity). In the present embodiment, the solid electrolyte layer 430 is composed of zirconium oxide (ZrO ₂ ) to which yttrium oxide (Y ₂ O ₃ ) is added as a stabilizer, that is, yttria stabilized zirconia (YSZ). Alternatively, by other solid electrolyte such as stabilized zirconia to which an oxide selected from calcium oxide (CaO), magnesium oxide (MgO), cerium oxide (CeO ₂ ), scandium oxide (Sc ₂ O ₃ ) and the like is added. The solid electrolyte layer 430 may be configured. The solid electrolyte layer 430 is formed with through holes 30a and 30c that penetrate the solid electrolyte layer 430 in the thickness direction (stacking direction LD). The through hole 30a is provided at the end of the rear end BS of the solid electrolyte layer 430, and the through hole 30c is provided at the front end AS rather than the through hole 30a. In the present embodiment, the entire solid electrolyte layer 430 is formed of the solid electrolyte, but may have a different configuration. At least the region sandwiched between the first electrode portion 41a of the detection electrode 441 described later and the second electrode portion 42a of the reference electrode 442 only needs to be formed of a solid electrolyte.

  The insulating layers 421, 423, and 424 are dense layers that electrically insulate between adjacent layers. The insulating layers 421, 423, and 424 are formed using alumina as a main component. The insulating layers 421, 423, 424, and a gas flow path forming layer 422, which will be described later, function as a base material layer that constitutes most of the sensor element 4. These base material layers may be made of a material other than alumina, but it is preferable that at least 50% by mass or more of alumina is included. By including alumina with high thermal conductivity at a high rate as described above, it is possible to suppress the occurrence of a temperature gradient in the sensor element 4 when heated by the heater 450.

  A porous protective layer 460 that penetrates the insulating layer 421 in the thickness direction (lamination direction LD) and has a rectangular shape in plan view is formed on the front end AS of the insulating layer 421. The porous protective layer 460 is a porous layer formed of alumina or the like, and is provided for diffusing the measurement gas flowing to the detection electrode 441. In the sensor element 4, a portion including the porous protective layer 460 on the front end side AS is included in the detection unit 8 described above. In addition, three through holes 21a, 21b, and 21c that penetrate the insulating layer 421 in the stacking direction LD are formed in the rear end side BS of the insulating layer 421. Similarly, two through holes 23d and 23e penetrating the insulating layer 424 in the thickness direction (lamination direction LD) are formed in the rear end side BS of the insulating layer 424.

  The detection electrode 441 is formed using, for example, platinum, rhodium, or the like. The detection electrode 441 is disposed on one surface of the solid electrolyte layer 430 in the stacking direction LD (the surface on the side where the insulating layer 421 is disposed). The detection electrode 441 includes a first electrode part 41a provided at an end part of the front end side AS, and a first lead part 41b extending from the first electrode part 41a toward the rear end side BS. The detection electrode 441 is electrically connected to the electrode terminal portion 32 from the end of the rear end BS of the first lead portion 41b through the through hole 21b of the insulating layer 421. That is, the space formed by the through hole 21 b functions as a “second through hole” for forming a path for electrically connecting the detection electrode 441 and the electrode terminal portion 32.

  The reference electrode 442 is formed using, for example, platinum, rhodium, or the like. The reference electrode 442 is disposed on the other surface of the solid electrolyte layer 430 in the stacking direction LD (the surface on the side where the gas flow path forming layer 422 is disposed). The reference electrode 442 includes a second electrode portion 42a provided at an end portion of the front end side AS, and a second lead portion 42b extending from the second electrode portion 42a toward the rear end side BS. The reference electrode 442 is electrically connected to the electrode terminal portion 31 from the second lead portion 42b through the through hole 30a of the solid electrolyte layer 430 and the through hole 21a of the insulating layer 421. That is, the space formed by the through holes 21 a and 30 a functions as a “second through hole” for forming a path for electrically connecting the reference electrode 442 and the electrode terminal portion 31.

  The gas flow path forming layer 422 is formed of a dense ceramic (for example, alumina). The gas flow path forming layer 422 is a through-hole penetrating the gas flow path forming layer 422 in the thickness direction (lamination direction LD), and a reference gas flow path CP for introducing the reference gas into the reference electrode 442 An introduction hole 70 is provided for forming the. In the present embodiment, the atmosphere is used as the reference gas. The introduction hole 70 has a reference chamber hole 70a formed in a rectangular shape in plan view at the end of the front end side AS, and the length in the width direction WD is shorter than the reference chamber hole 70a, and the rear end side BS from the reference chamber hole 70a. And a vent hole 70b extending in the direction. The introduction hole 70 is surrounded by the solid electrolyte layer 430 having the reference electrode 442 formed on the surface and the insulating layer 423 in addition to the gas flow path forming layer 422, and a reference for introducing the reference gas into the reference electrode 442. A gas flow path CP is configured. That is, the gas flow path forming layer 422 functions as a “first layer” in which a reference gas flow path for introducing the reference gas to the reference electrode 442 is formed. The reference gas channel CP will be described in more detail later.

  The reinforcing layer 80 is a layer formed on the solid electrolyte layer 430. The reinforcing layer 80 includes tetragonal zirconia. Since tetragonal zirconia exhibits excellent toughness, the reinforcing layer 80 has a function of increasing the bending strength of the sensor element 4. Further, the tetragonal zirconia has a property that a phase transition from a tetragonal crystal to a monoclinic crystal occurs at the time of crack occurrence, and has the property of suppressing the extension of cracks by the volume expansion at that time. It has a function of suppressing damage to the sensor element 4. The reinforcing layer 80 will be described in detail later.

  A heater 450 extending along the axial direction CD is embedded between the insulating layer 423 and the insulating layer 424. The heater 450 is used to raise the temperature of the sensor element 4 to a predetermined activation temperature, increase the conductivity of oxygen ions in the solid electrolyte layer 430, and stabilize the operation of the gas sensor 2. The heater 450 is a heating resistor formed of a conductor such as platinum, and generates heat by supplied power.

  The heater 450 includes a heating portion 450a formed in a meandering manner on the front end side AS, and heater lead portions 450b and 450c connected to both ends of the heating portion 450a and extending linearly toward the rear end side BS, respectively. Prepare. The ends of the heater lead portions 450b and 450c on the rear end side BS are electrically connected to the electrode terminal portions 33 and 34 through through holes 23d and 23e formed in the insulating layer 424, respectively. That is, the space formed by the through holes 23 d and 23 e functions as a “second through hole” for forming a path for electrically connecting the heater 450 and the electrode terminal portions 33 and 34.

A-3. Reference gas flow path configuration:
FIG. 3 is a plan view of the sensor element 4 as viewed from the first plate surface 21 side. 4 is a cross-sectional view of the sensor element 4 taken along the line AA shown in FIG. In FIG. 3, the structure appearing on the first plate surface 21 of the insulating layer 421 is represented by a solid line, and the internal structure of the sensor element 4 is represented by a broken line. Although the stacking direction LD is not shown in FIG. 3, the stacking direction LD is a direction perpendicular to the paper surface in FIG. Further, although the width direction WD is not shown in FIG. 4, the width direction WD is a direction perpendicular to the paper surface in FIG.

  As described above, the introduction hole 70 formed in the gas flow path forming layer 422 and forming the reference gas flow path CP includes the reference chamber hole 70a and the vent hole 70b. As shown in FIGS. 3 and 4, the reference chamber hole 70 a has the entire first electrode portion 41 a of the detection electrode 441 and the entire second electrode portion 42 a of the reference electrode 442 when projected in the stacking direction LD. And are provided at overlapping positions. Therefore, the second electrode portion 42a of the reference electrode 442 is exposed in a space that is part of the reference gas channel CP and is formed by the reference chamber hole 70a.

  Further, as shown in FIG. 3, the end of the rear end BS of the vent hole 70b is provided in the entire through hole 21c provided in the insulating layer 421 and in the solid electrolyte layer 430 when projected in the stacking direction LD. The entire through hole 30c overlaps. As shown in FIG. 4, the through hole 21c of the insulating layer 421 and the through hole 30c of the solid electrolyte layer 430 are stacked in the stacking direction from the outer surface (first plate surface 21) of the sensor element 4 to the reference gas channel CP. An introduction channel IP, which is a channel for guiding the reference gas by extending to the LD, is formed. Therefore, in the sensor element 4, the reference gas is taken into the reference gas flow path CP via the introduction flow path IP having an opening in the first plate surface 21 of the insulating layer 421, and the second of the reference electrode 442. The electrode part 42a is exposed to the reference gas (see FIG. 2). As shown in FIG. 1, the sensor element 4 is surrounded by the metal shell 38 inside the gas sensor 2 at the opening of the introduction flow path IP (the opening of the through hole 21 c of the insulating layer 421) on the first plate surface 21. It arrange | positions between an area | region and the area | region where the sensor element 4 is enclosed by the front end side separator 66. FIG. Thereby, the opening is exposed to the atmosphere, and the atmosphere as the reference gas can be introduced into the introduction flow path IP. Note that the “introduction channel IP” in the present embodiment functions as a “first through hole”.

A-4. Reinforcement layer configuration:
The reinforcing layer 80 is formed in a substantially rectangular shape as shown in FIG. Further, the reinforcing layer 80 is provided so as to overlap the vent hole 70b when projected in the stacking direction LD as shown in FIG. Specifically, the reinforcing layer 80 is projected from the vicinity of the boundary between the vent hole 70b and the reference chamber hole 70a in the axial direction CD when projected in the stacking direction LD as shown in FIG. It is provided up to the vicinity of the end of the tip side AS on the outer periphery. The width direction WD is formed wider than the vent hole 70b beyond the outer periphery of the vent hole 70b.

As described above, the reinforcing layer 80 includes tetragonal zirconia. Zirconia (zirconium oxide; ZrO ₂ ) is most stable in a monoclinic state at room temperature, and causes a phase transition in a high temperature region. By adding a stabilizer to such zirconia and making it dissolve, cubic or tetragonal stabilization becomes possible. The reinforcing layer 80 includes such stabilized zirconia as tetragonal zirconia. In the present specification, “stabilized zirconia” includes “partially stabilized zirconia”.

In the present embodiment, zirconium oxide (ZrO ₂ ) added with yttrium oxide (Y ₂ O ₃ ) as a stabilizer, that is, yttria-stabilized zirconia (YSZ) is used as the tetragonal zirconia contained in the reinforcing layer 80. . Alternatively, other types of stabilized zirconia to which an oxide selected from calcium oxide (CaO), magnesium oxide (MgO), cerium oxide (CeO ₂ ), scandium oxide (Sc ₂ O ₃ ) and the like is added may be used. Good. For example, when yttrium oxide (Y ₂ O ₃ ) is used as a stabilizer, the amount of stabilizer added to zirconia can be 1 to 5 mol%, and if the amount added is 3 mol%, The ratio of the tetragonal portion in zirconia can be extremely high, which is desirable.

  The reinforcing layer 80 can be formed by, for example, applying a zirconia paste containing tetragonal zirconia on the solid electrolyte layer 430. In order to prepare a zirconia paste, first, a stabilized zirconia powder in which a stabilizer such as 1 to 5 mol% of yttria (yttrium oxide) is dissolved in zirconia may be prepared. Then, a zirconia paste is obtained by mixing the stabilized zirconia powder with a solvent, a binder, and, if necessary, a powder of another type of ceramic material. In order to enhance the effect of improving the strength of the sensor element 4 by providing the reinforcing layer 80, the content ratio of tetragonal zirconia in the zirconia paste is desirably 20% by mass or more, for example. In addition, the content rate of the tetragonal zirconia in the reinforcement layer 80 or a zirconia paste can be calculated | required with a X ray diffraction method (XRD).

  As another type of ceramic material to be mixed with the zirconia paste described above, for example, alumina can be used. Zirconia has a property that its thermal conductivity is lower than that of alumina which is a main component of the insulating layers 421, 423 and 424 which are main constituent members of the sensor element 4. Therefore, a ceramic material (for example, alumina) having a higher thermal conductivity than zirconia is added to the zirconia paste from the viewpoint of suppressing a local decrease in thermal conductivity in the sensor element 4 due to the provision of the reinforcing layer 80. Is desirable. As described above, the reinforcing layer 80 has a function of increasing the bending strength of the sensor element 4 by including tetragonal zirconia exhibiting excellent toughness. Therefore, from the viewpoint of improving the strength of the sensor element 4 by providing the reinforcing layer 80 containing tetragonal zirconia and suppressing the decrease in thermal conductivity in the sensor element 4 due to the arrangement of tetragonal zirconia, the stabilized zirconia powder The ratio of the stabilized zirconia powder to the total amount of the ceramic powder and other types of ceramic powder (alumina powder or the like) may be, for example, 15 to 35% by mass.

  When the reinforcing layer 80 is formed by applying a zirconia paste on the solid electrolyte layer 430, the reference electrode 442 is formed by applying a noble metal paste containing platinum, rhodium, or the like after the application of the zirconia paste. That's fine. Alternatively, when the reinforcing layer 80 is formed on the solid electrolyte layer 430, the reference electrode 442 may be formed on the solid electrolyte layer 430 and then the zirconia paste may be applied.

  According to the gas sensor 2 including the sensor element 4 of the present embodiment configured as described above, the reinforcing layer 80 is formed between the solid electrolyte layer 430 and the gas flow path forming layer 422. That is, the reinforcing layer 80 is formed so as to cover the surface portion of the solid electrolyte layer 430 among the inner wall surface of the reference gas flow path CP formed by the vent hole 70b. Therefore, in the sensor element 4, by providing the vent hole 70b for forming the reference gas flow path CP, the strength of the portion where the strength is lowered can be increased, and the bending strength of the sensor element 4 can be increased.

  A further description will be given of a decrease in strength of the sensor element 4 due to the formation of the vent hole 70b. When the sensor element 4 is assembled to the gas sensor 2 or when the completed gas sensor 2 is used, an external force may act on the sensor element 4 from various directions, and stress may be generated in the sensor element 4. Since the sensor element 4 is provided with a space (hollow part) for forming the reference gas flow path CP therein, when an external force is applied to the sensor element 4, a large tensile stress is applied to the inner wall surface of the hollow part. It is thought to occur. In this embodiment, since the reinforcing layer 80 including tetragonal zirconia, which is a material having higher toughness than the constituent material of the insulating layers 421, 423, 424, is provided on the inner wall surface of the hollow portion, the tensile stress described above is provided. The strength of the generated part can be increased, and the bending strength of the sensor element 4 can be increased. Further, by providing the reinforcing layer 80 on the inner wall surface of the hollow portion, even when a crack occurs on the inner wall surface of the hollow portion due to the stress, the progress of the crack is suppressed and the durability of the sensor element 4 is improved. Can increase the sex.

  When an external force is applied to the sensor element 4 as described above, it is considered that the influence of the sensor element 4 increases as the stress in the stacking direction LD increases in the area of the sensor element 4 that receives the external force. In the present embodiment, since the reinforcing layer 80 is provided along the surface of the solid electrolyte layer 430 perpendicular to the stacking direction LD, the strength of the sensor element 4 can be increased efficiently.

  Examples of the external force applied to the sensor element 4 when the gas sensor 2 is used include a force applied from a holding portion that presses and holds the sensor element 4 in the gas sensor 2. Specific examples of the holding portion include a powder packed layer (talc ring) 56. In the present embodiment, since the reinforcing layer 80 is provided at a portion where the sensor element 4 is pressed and held by the holding portion, the effect of increasing the strength of the sensor element 4 and increasing the durability of the gas sensor 2 is obtained particularly remarkably. be able to. Note that the reinforcing layer 80 is provided at a portion where the sensor element 4 is pressed and held by the holding portion when the region in contact with the holding portion on the surface of the sensor element 4 is projected in the stacking direction LD. A region in contact with the portion overlaps the reinforcing layer 80. In FIG. 4, a range in which the sensor element 4 is pressed and held by the holding portion is indicated as a pressing holding portion PH.

  From the viewpoint of enhancing the durability of the gas sensor 2, it is desirable that the entire pressing holding portion PH overlaps the reinforcing layer 80. In the present embodiment, the reinforcing layer 80 is provided from the vicinity of the boundary between the vent hole 70b and the reference chamber hole 70a to the vicinity of the outer periphery of the introduction flow path IP. However, the reinforcing layer 80 may be provided so as to overlap at least the press holding portion PH. desirable. Thereby, the effect which suppresses the intensity | strength fall of the sensor element 4 resulting from the pressing force from a holding | maintenance part can be heightened.

  Further, the reinforcing layer 80 of the present embodiment is formed so as to exceed the outer periphery of the vent hole 70b when projected in the stacking direction LD in the width direction WD. Thereby, since the strength can be ensured even at the corner portion of the inner wall surface of the reference gas flow path CP where stress is particularly concentrated, the effect of reinforcing the sensor element 4 can be enhanced. The reinforcing layer 80 may have a shape that does not exceed the outer periphery of the air hole 70b in the width direction WD when projected in the stacking direction LD. Even in this case, the reinforcing layer 80 is provided. The effect of reinforcement by is obtained.

  In addition, the effect which improves the intensity | strength of the sensor element 4 can be heightened, so that the area of the reinforcement layer 80 formed on the solid electrolyte layer 430 is enlarged. However, in this embodiment, the length of the reinforcing layer 80 in the width direction WD (hereinafter also simply referred to as width) is made smaller than the width of the sensor element 4. Therefore, exposure of the reinforcing layer 80 to the outer surface of the sensor element 4 can be suppressed. Thereby, for example, in a vehicle to which the gas sensor 2 is attached, even when condensation occurs in the exhaust gas flow channel, it is possible to prevent the liquid water from coming into contact with the reinforcing layer 80.

  When liquid water comes into contact with the outer surface of the sensor element 4, the temperature of the part in contact with the liquid water decreases. At this time, if the reinforcing layer 80 is exposed in the vicinity of the contact portion of the liquid water on the outer surface of the sensor element 4, the zirconia and alumina have different thermal expansion coefficients, so that cracks or cracks are formed at the interface of the reinforcing layer 80. May occur. In addition, since zirconia has lower thermal conductivity than alumina, when liquid water comes into contact with a portion where the reinforcing layer 80 is exposed and the reinforcing layer 80 is cooled, the liquid water comes into contact with a portion other than the reinforcing layer 80 There is a possibility that the temperature rise (recovery of temperature) of the sensor element 4 is delayed as compared with FIG. Therefore, by not exposing the reinforcing layer 80 to the outer surface of the sensor element 4, it is possible to suppress damage to the sensor element 4 due to contact with liquid water and reduction in sensitivity of the gas sensor 2 due to temperature drop of the sensor element 4. Can do.

  The reinforcing layer 80 of the present embodiment is formed so as to extend to the vicinity of the boundary between the vent hole 70b and the reference chamber hole 70a with respect to the tip side AS in the axial direction CD. It is good also as not providing in the detection part 8 (refer FIG. 1) exposed to measurement gas. That is, the reinforcing layer 80 may be provided so as not to overlap the detection unit 8 when the reinforcing layer 80 is projected in the stacking direction LD. In this case, even if the area of the reinforcing layer 80 is large enough to expose the reinforcing layer 80 to the outer surface of the sensor element 4 and the effect of improving the strength is enhanced, the reinforcing layer 80 is formed on the outer surface of the sensor element 4. Occurrence of the problems described above due to exposure can be suppressed.

B. Second embodiment:
FIG. 5 is a plan view showing a state in which the sensor element 104 of the second embodiment is viewed from the first plate surface 21 side, as in FIG. The sensor element 104 of the second embodiment is used for the gas sensor 2 in place of the sensor element 4 of the first embodiment, and the same reference numerals are given to the parts common to the first embodiment, and detailed description will be given. Is omitted.

  The sensor element 104 is different from the sensor element 4 of the first embodiment in that it includes a reinforcing layer 180 instead of the reinforcing layer 80. The reinforcing layer 180 is formed on the solid electrolyte layer 430 similarly to the reinforcing layer 80. However, in addition to the region similar to the reinforcing layer 80, when the projection is further projected in the stacking direction LD, It differs from the reinforcing layer 80 in that it is formed in the overlapping region. That is, when the reinforcing layer 180 is projected in the stacking direction LD, with respect to the axial direction CD, from the vicinity of the boundary between the vent hole 70b and the reference chamber hole 70a, the end portion of the rear end BS on the outer periphery of the introduction channel IP It is provided to the vicinity of.

  With such a configuration, in addition to the same effects as in the first embodiment, the strength of the sensor element 104 is reduced due to the provision of the introduction flow path IP that is a hollow portion provided in the sensor element 104. Is obtained. The part of the sensor element 104 where the introduction flow path IP is provided is not a part of the gas sensor 2 that is held by the holding unit. For example, when the gas sensor 2 is used by being attached to an internal combustion engine of the vehicle, the vibration of the vehicle For example, stress may be generated in the sensor element 104 when the gas sensor 2 is used. Even in such a case, it is possible to ensure the strength at the site where the introduction channel IP is provided.

  In FIG. 5, a single reinforcing layer 180 is provided, but a different configuration may be used. For example, when the reinforcing layer is projected in the stacking direction LD, a portion that overlaps the vent hole 70b and a portion that overlaps the introduction flow path IP may be provided apart from each other. Further, the reinforcing layer 180 may be formed so as to overlap with a part of the introduction channel IP when projected in the stacking direction LD. Even in this case, the strength reduction of the sensor element 104 due to the introduction flow path IP can be suppressed in the range where the reinforcing layer 180 is provided.

C. Third embodiment:
FIG. 6 is a plan view showing a state in which the sensor element 204 of the third embodiment is viewed from the first plate surface 21 side, similarly to FIG. The sensor element 204 of the third embodiment is used for the gas sensor 2 instead of the sensor element 4 of the first embodiment, and the same reference numerals are given to the parts common to the first embodiment, and detailed description will be given. Is omitted.

  The sensor element 204 is different from the sensor element 4 of the first embodiment in that the sensor element 204 further includes reinforcing layers 281a and 281b in addition to the reinforcing layer 80. The reinforcing layer 281a is formed in a region overlapping the through hole 21a of the insulating layer 421 and the through hole 30a of the solid electrolyte layer 430 when projected in the stacking direction LD. The reinforcing layer 281b is formed in a region overlapping the through hole 21b of the insulating layer 421 when projected in the stacking direction LD.

  With such a configuration, in addition to the same effects as those of the first embodiment, the sensor element 204 resulting from the provision of the through holes 21a, 21b, and 30a that are hollow portions provided in the sensor element 204 is also provided. The effect of suppressing the decrease in strength is obtained. In addition, the site | part in which through-hole 21a, 21b, 30a was provided in the sensor element 204 receives a pressing force from the metal terminal member 10 via the electrode terminal part 30 (electrode terminal part 31, 32) in the gas sensor 2. .

  In FIG. 6, the reinforcing layers 180, 281a, and 281b are provided apart from each other, but may be provided continuously with each other. Further, the reinforcing layers 281a and 281b may be formed so as to overlap a part of the through holes 21a, 21b, and 30a when projected in the stacking direction LD. Even in this case, the strength reduction of the sensor element 204 due to the through holes 21a, 21b, and 30a can be suppressed in the range where the reinforcing layers 281a and 281b are provided.

D. Fourth embodiment:
FIG. 7 is a cross-sectional view showing the cross-sectional state of the sensor element 304 of the fourth embodiment in the same manner as FIG. The sensor element 304 of the fourth embodiment is used for the gas sensor 2 instead of the sensor element 4 of the first embodiment, and the same reference numerals are given to the parts common to the first embodiment, and detailed description will be given. Is omitted.

  The sensor element 304 is different from the sensor element 4 of the first embodiment in that it further includes a reinforcing layer 380 in addition to the reinforcing layer 80. The reinforcing layer 380 is formed in a region overlapping the reinforcing layer 80 when projected in the stacking direction LD on the surface of the insulating layer 423 on the side in contact with the gas flow path forming layer 422.

  With such a configuration, the effect of improving the strength of the sensor element 304 can be further enhanced as compared with the first embodiment. Although both the reinforcing layer 80 on the solid electrolyte layer 430 and the reinforcing layer 380 on the insulating layer 423 are provided in FIG. 7, only the reinforcing layer 380 may be provided.

  When the reinforcing layer 380 is provided on the insulating layer 423, the reinforcing layer 380 is placed on the tip side AS in the axial direction CD up to a region overlapping with the reference chamber hole 70a when projected in a direction perpendicular to the stacking direction LD. You may extend and form. Thereby, the strength reduction of the sensor element 304 resulting from providing the reference chamber hole 70a can be suppressed. However, in the gas sensor 2, from the viewpoint of the efficiency of transferring the heat generated by the heater 450 to the solid electrolyte layer 430, the reinforcing layer 380 is disposed in a region overlapping the reference chamber hole 70 a when projected in a direction perpendicular to the stacking direction LD. It is desirable not to provide.

  Further, a reinforcing layer may be further provided on the insulating layer 423 in a region overlapping with the through holes 23d and 23e of the insulating layer 424 when projected in the stacking direction LD. With such a configuration, it is possible to obtain an effect of suppressing the strength reduction of the sensor element due to the provision of the through holes 23d and 23e which are hollow portions in the sensor element.

E. Variations:
・ Modification 1:
In each said embodiment, although the sensor element is comprised by the several sheet-like member shown in FIG. 2, it is good also as a different structure, for example, it is good also as a laminated body which added the other sheet-like member. Regardless of the configuration of the sheet-like member constituting the sensor element, the reinforcing layer may be provided only on one of the two inner wall surfaces facing each other in the stacking direction LD among the inner wall surfaces of the reference gas flow path CP. In that case, it is preferable to provide the reinforcing layer on the surface on the side where the distance from the reinforcing layer to the outer surface of the sensor element is shortened. That is, it is desirable to provide the two inner wall surfaces on the surface having the smaller thickness in the direction away from each other in the stacking direction LD from each of the two inner wall surfaces to the outer surface of the gas sensor element. Specifically, in FIG. 4, the distance from the surface on the solid electrolyte layer 430 constituting the inner wall surface of the reference gas channel CP to the first plate surface 21 is D _A , and the inner wall surface of the reference gas channel CP is configured. the distance from the surface of the insulating layer 423 to the second plate surface 23 which represents a D _B. At this time, when the reinforcing layer is provided on the solid electrolyte layer 430, it is desirable that D _A <D _B is satisfied. With such a configuration, the effect of increasing the strength of the sensor element 4 is prominent by providing the reinforcing layer on the side where the thickness to the hollow portion provided in the sensor element is thin, that is, on the side where the strength is insufficient. Can be obtained.

Modification 2
In each of the above embodiments, the reference gas flow path CP is formed by the introduction hole 70 which is a through hole provided in the gas flow path forming layer 422, but may have a different configuration. For example, the introduction hole 70 provided in the gas flow path forming layer 422 may be a recess that does not penetrate to the insulating layer 423 side instead of the through hole.

  FIG. 8 is a cross-sectional view showing the state of the cross section of the sensor element 404 of the modified example in the same manner as FIG. In the gas flow path forming layer 422 of the sensor element 404, a concave-shaped introduction hole 70 is formed. And the reinforcement layer 80 similar to 1st Embodiment is provided. As described above, a through hole or a recess is provided as the introduction hole 70 in the gas flow path forming layer 422, and a reference is provided between layers adjacent to the gas flow path forming layer 422 (for example, the solid electrolyte layer 430 and the insulating layer 423). When forming the gas flow path CP, a reinforcing layer can be easily formed by providing a layer containing tetragonal zirconia on the adjacent layer. FIG. 8 shows a state in which a reinforcing layer 480 is further provided on the bottom surface of the recessed introduction hole 70.

  Alternatively, the vent hole 70b is not formed into a shape in which the portion opened on the laminated surface of the gas flow path forming layer 422 extends along the axial direction CD like the above-described through hole or concave portion, but the gas flow path forming layer 422. It is good also as a shape which penetrates the inside and extends in the axial direction CD. In any case, the strength of the sensor element 4 is increased by providing a reinforcing layer on at least one of the two inner wall surfaces facing each other in the stacking direction LD among the inner wall surfaces of the reference gas channel CP. Similar effects can be obtained.

  When the cross section of the reference gas flow path CP is not rectangular, the at least one surface is a range including at least one of the upper end and the lower end of the stacking direction LD among the inner wall surfaces of the reference gas flow path CP. And it is sufficient. In this case, it is desirable to provide a reinforcing layer in a range of ¼ or more of the outer periphery of the gas flow path forming layer 422 in the cross section of the gas flow path forming layer 422 perpendicular to the axial direction CD.

・ Modification 3:
In each of the above embodiments, the reference gas flow path CP is formed by a hollow portion formed in the sensor element, but a porous body is formed in at least a part of the reference gas flow path CP (introduction hole 70). It is good also as filling. Even when the introduction hole 70 is filled with a porous material, the strength of the sensor element can be reduced by providing the introduction hole 70, but the same effect of suppressing the strength reduction of the sensor element can be achieved by providing the reinforcing layer. An effect is obtained. When the porous material is filled in the reference gas channel CP, the inner wall surface of the reference gas channel CP is the inner wall surface of the introduction hole 70 provided in the gas channel forming layer 422. The surface which divides the space filled with a porous body is pointed out.

-Modification 4:
In each of the above embodiments, the introduction flow path IP for guiding the reference gas from the outer surface of the sensor element to the reference gas flow path CP has a shape extending in the stacking direction in the sensor element, but may have a different configuration. For example, an opening of the introduction channel IP is provided on the side surface 422a or the side surface 422b (see FIG. 2) of the gas channel formation layer 422, and the introduction channel IP is formed in the plane of the gas channel formation layer 422. Also good. In this case, among the inner wall surfaces of the introduction channel IP, at least one of the two inner wall surfaces facing the stacking direction LD is provided with a reinforcing layer similar to the reinforcing layer 80, resulting in the introduction channel IP. A decrease in strength of the sensor element can be suppressed.

-Modification 5:
In each said embodiment, although the gas sensor was made into the oxygen concentration sensor, it is good also as a different structure. It is good also as a sensor which detects different kinds of gas, such as NOx in exhaust gas. The present invention is a sensor having a concentration cell having a pair of electrodes laminated on both surfaces of a solid electrolyte having ion conductivity and generating an electromotive force due to a concentration difference (partial pressure difference) of a specific gas component on each electrode. The same effect can be obtained by applying.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the above effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

2 ... Gas sensor 4, 104, 204, 304, 404 ... Sensor element 6 ... Ceramic sleeve 8 ... Detection part 10 ... Metal terminal member 21 ... First plate surface 21a, 21b, 21c ... Through hole 23 ... Second plate surface 23d ... Through hole 30, 31-34 ... Electrode terminal part 30a, 30c ... Through hole 38 ... Metal fitting 39 ... Screw part 40 ... Rear end part 41a ... First electrode part 41b ... First lead part 42a ... Second electrode part 42b ... 2nd lead part 43 ... Internal protector 44 ... Outer cylinder 45 ... External protector 46 ... Lead wire 50 ... Grommet 52 ... Shelf part 53 ... Ceramic holder 54 ... Through hole 56 ... Powder packing layer 57 ... Clamping packing 58 ... Through hole 59 ... Filter unit 61 ... Lead wire insertion hole 62 ... Rear end side end face 63 ... Rear end side separator 65a ... Insertion part 65b ... Groove part 6 ... tip side separator 67 ... collar 68 ... tip side end surface 69 ... holding member 70 ... introduction hole 70a ... reference chamber hole 70b ... vent hole 80, 180, 281a, 281b, 380, 480 ... reinforcing layer 421, 423, 424 ... Insulating layer 422 ... Gas flow path forming layer 422a, 422b ... Side surface 430 ... Solid electrolyte layer 441 ... Detection electrode 442 ... Reference electrode 450 ... Heater 450a ... Heating part 450b ... Heater lead part 460 ... Porous protective layer

Claims (11)

A solid electrolyte layer; a detection electrode provided on one surface of the solid electrolyte layer and exposed to a gas to be measured; a reference electrode provided on the other surface of the solid electrolyte layer and exposed to a reference gas; and the reference A gas sensor element in which a plurality of layers including a first layer for forming a reference gas flow path for introducing the reference gas into an electrode are laminated,
A reinforcing layer containing tetragonal zirconia is provided on at least one of the two inner wall surfaces facing each other in the stacking direction of the gas sensor elements among the inner wall surfaces of the reference gas flow path. element. The gas sensor element according to claim 1,
The gas sensor element has a first penetration that extends in the stacking direction from the outer surface of the gas sensor element toward the reference gas flow path and forms a flow path for introducing the reference gas into the reference gas flow path. Holes are provided,
The gas sensor element, wherein the reinforcing layer is formed in a region overlapping with the first through hole when projected in the stacking direction. The gas sensor element according to claim 1 or 2,
The gas sensor element includes at least one selected from the detection electrode, the reference electrode, and a heater for heating the solid electrolyte layer, and an electrode terminal portion provided on the outer surface of the gas sensor element. A second through-hole extending in the stacking direction for forming a path for electrical conduction is formed,
The gas sensor element, wherein the reinforcing layer is formed in a region overlapping with the second through hole when projected in the stacking direction. The gas sensor element according to any one of claims 1 to 3,
The reinforcing layer has a thickness in a direction away from each other in the stacking direction from each of the two inner wall surfaces to the outer surface of the gas sensor element among the two inner wall surfaces facing each other in the reference gas flow path. A gas sensor element provided on a smaller surface. The gas sensor element according to any one of claims 1 to 4, wherein:
The reference gas flow path is formed between the first layer and a layer adjacent to the first layer,
The reinforcing layer is formed on a surface of the adjacent layer that is in contact with the first layer. Gas sensor element. The gas sensor element according to claim 5,
The reinforcing layer is formed over a region beyond the outer edge of the reference gas channel in the width direction orthogonal to the direction in which the reference gas channel extends when the reinforcing layer and the reference gas channel are projected in the stacking direction. A gas sensor element characterized by being made. The gas sensor element according to claim 5 or 6,
The reinforcing layer is provided so as not to be exposed on an outer surface of the gas sensor element. The gas sensor element according to any one of claims 1 to 7,
The gas sensor element includes a layer containing 50% by mass or more of alumina as a base material layer laminated with the solid electrolyte layer. A gas sensor comprising a gas sensor element for detecting a specific gas in a gas to be measured, and a metal shell for holding the gas sensor element,
A gas sensor comprising the gas sensor element according to claim 1 as the gas sensor element. The gas sensor according to claim 9, further comprising:
A holding portion for pressing and holding the gas sensor element;
The reinforcing layer is provided at least in a portion where the gas sensor element is pressed and held by the holding portion. The gas sensor according to claim 9 or 10, wherein
The reinforcing layer is provided so as not to be exposed in a region in contact with the gas to be measured on the outer surface of the gas sensor element.

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