阅读说明：本技术 气体传感器元件和气体传感器 (Gas sensor element and gas sensor ) 是由 中川惠介 上野正刚 清家晃 山川游 大塚茂弘 于 2018-12-07 设计创作，主要内容包括：气体传感器元件具有元件主体、外部电极和凸缘导引部。元件主体形成为：以固体电解质体主体,形成为沿轴线方向延伸且前端封闭的有底筒状,并且具有向径向外侧突出的凸缘部。外部电极含有贵金属,以从比凸缘部靠前端侧的位置朝向凸缘部延伸的方式形成在元件主体的外表面。凸缘导引部与外部电极重叠,该凸缘导引部至少在凸缘部中的面朝前端侧的前端朝向面上沿着元件主体的周向形成,该凸缘导引部形成为：该凸缘导引部在前端朝向面上的沿着元件主体的周向的长度大于外部电极和凸缘导引部相重叠的重叠部处的外部电极的沿着周向的长度。凸缘导引部以导电性氧化物为主要成分。(The gas sensor element has an element body, an external electrode, and a flange guide. The element main body is formed as follows: the solid electrolyte body is formed in a bottomed cylindrical shape extending in an axial direction and having a closed tip, and has a flange portion projecting radially outward. The external electrode contains a noble metal, and is formed on the outer surface of the element body so as to extend from a position on the tip side of the flange portion toward the flange portion. A flange guide portion that is formed along a circumferential direction of the element main body at least on a front end facing surface facing a front end side in the flange portion, the flange guide portion being formed to overlap the external electrode: the length of the flange guide portion in the circumferential direction of the element main body on the leading end facing surface is larger than the length of the external electrode in the circumferential direction at the overlapping portion where the external electrode and the flange guide portion overlap. The flange guide portion contains a conductive oxide as a main component.)

1. A gas sensor element, comprising:

an element main body formed as: a solid electrolyte body serving as a main body, formed in a bottomed cylindrical shape extending in an axial direction with a closed tip, and having a flange portion protruding radially outward;

an external electrode containing a noble metal and formed on an outer surface of the element body so as to extend from a position closer to a tip end side than the flange portion toward the flange portion; and

a flange guide portion that overlaps the external electrode, the flange guide portion being formed along a circumferential direction of the element main body at least on a leading end facing surface facing a leading end side in the flange portion, the flange guide portion being formed to: a length of the flange guide portion in the circumferential direction of the element main body on the leading end-facing surface is larger than a length of the external electrode in the circumferential direction at an overlapping portion where the external electrode and the flange guide portion overlap,

the flange guide portion contains a conductive oxide as a main component.

2. The gas sensor element according to claim 1,

the flange guide portion and the external electrode are formed so as to extend to a rear end side outer peripheral surface which is an outer peripheral surface on a rear end side of the front end facing surface in the flange portion,

the flange guide and the external electrode are in contact with each other at the rear end side outer peripheral surface.

3. A gas sensor, wherein,

the gas sensor includes: the gas sensor element of claim 1 or 2; and a holding member that holds the gas sensor element in a state of being electrically connected to the flange guide.

4. The gas sensor according to claim 3,

the flange guide portion and the holding member are in direct contact, or a conductive member is interposed between the flange guide portion and the holding member to electrically connect the flange guide portion and the holding member to each other,

a part of the flange guide and a part of the external electrode are arranged between the flange guide or a 1 st contact surface of the external electrode with the holding member and the distal end facing surface in a state where the flange guide and the holding member are in direct contact,

in the case where the conductive member is interposed between the flange guide and the holding member, a part of the flange guide and a part of the external electrode are arranged between the 2 nd contact surface where the flange guide or the external electrode is in contact with the conductive member and the distal end facing surface.

Technical Field

The present invention relates to a gas sensor element and a gas sensor having an element body formed in a bottomed cylindrical shape.

Background

As described in patent document 1, there is known a gas sensor element including an element main body formed in a bottomed cylindrical shape extending in an axial direction and having a closed tip end, the element main body including a solid electrolyte body, and having a flange portion protruding radially outward.

In the gas sensor element described above, a flange guide portion is formed in the flange portion so as to be electrically connected to a metal shell that holds the gas sensor element. The flange guide is formed of a noble metal such as platinum.

Disclosure of Invention

Problems to be solved by the invention

In order to ensure electrical connection with the main body metal case, the flange guide portion needs to be formed over a wide range. There is therefore a problem that: when a relatively expensive noble metal is used for the flange guide, the manufacturing cost of the gas sensor element is greatly increased.

The invention can reduce the manufacturing cost of the gas sensor element.

Means for solving the problems

One aspect of the present invention is a gas sensor element including an element main body, an external electrode, and a flange guide portion. The element main body is formed as follows: the solid electrolyte body is formed in a bottomed cylindrical shape extending in an axial direction and having a closed tip, and has a flange portion projecting radially outward. The external electrode contains a noble metal, and is formed on the outer surface of the element body so as to extend from a position on the tip side of the flange portion toward the flange portion. A flange guide portion that is formed along a circumferential direction of the element main body at least on a front end facing surface facing a front end side in the flange portion, the flange guide portion being formed to overlap the external electrode: the length of the flange guide portion in the circumferential direction of the element main body on the leading end facing surface is larger than the length of the external electrode in the circumferential direction at the overlapping portion where the external electrode and the flange guide portion overlap. In the gas sensor element of the present invention, the flange guide portion contains a conductive oxide as a main component. The term "main component" refers to a component that accounts for more than 50% by mass of all components constituting the site to be targeted.

In the gas sensor element of the present invention configured as described above, the conductive oxide which is less expensive than the noble metal is used as the main component of the flange guide, so that the amount of the noble metal used in the flange guide can be reduced, and the manufacturing cost of the gas sensor element can be reduced.

In one aspect of the present invention, the flange guide portion and the external electrode may be formed to extend to a rear end side outer peripheral surface that is an outer peripheral surface on a rear end side of the front end facing surface in the flange portion, and the flange guide portion and the external electrode may be in contact with each other on the rear end side outer peripheral surface.

In the gas sensor element of the present invention configured as described above, since a load is applied to the distal end facing surface in the manufacturing process of assembling the gas sensor element and the holding member for holding the gas sensor element, the flange guide portion formed on the distal end facing surface may be detached from the flange portion, and even in this case, the flange guide portion and the external electrode may be in contact with each other on the rear end side outer peripheral surface. Thus, the gas sensor element of the present invention can improve the reliability of conduction between the flange guide and the external electrode in the manufacturing process.

Another aspect of the present invention is a gas sensor including the gas sensor element according to one aspect of the present invention and a holding member for holding the gas sensor element.

The gas sensor of the present invention configured as described above is a gas sensor including the gas sensor element according to one aspect of the present invention, and can obtain the same effects as those of the gas sensor element of the present invention. That is, the gas sensor of the present invention can reduce the manufacturing cost of the gas sensor by reducing the manufacturing cost of the gas sensor element.

In another aspect of the present invention, the flange guide and the holding member may be electrically connected to each other by directly contacting each other, or by interposing a conductive member between the flange guide and the holding member. In the gas sensor according to the present invention, when the flange guide and the holding member are in direct contact with each other, a part of the flange guide and a part of the external electrode may be arranged between the flange guide or a 1 st contact surface of the external electrode, which is in contact with the holding member, and the distal end facing surface. In the gas sensor according to the present invention, when the conductive member is interposed between the flange guide and the holding member, a part of the flange guide and a part of the external electrode may be disposed between the flange guide or the 2 nd contact surface of the external electrode, which is in contact with the conductive member, and the distal end facing surface.

In the gas sensor of the present invention configured as described above, even when the flange guide portion is detached from the tip end side of the 1 st contact surface or the 2 nd contact surface in the manufacturing process, the state in which a part of the flange guide portion and a part of the external electrode are in contact with each other can be maintained on the rear end side of the tip end side of the 1 st contact surface or the 2 nd contact surface. In the manufacturing process, the flange guide portion is more likely to be detached from the tip end side of the 1 st contact surface and the 2 nd contact surface than from the tip end side of the 1 st contact surface and the 2 nd contact surface. Thus, the gas sensor according to the present invention can improve the reliability of conduction between the flange guide and the external electrode in the manufacturing process.

Drawings

Fig. 1 is a view showing a state in which a gas sensor is cut in an axial direction.

Fig. 2 is a front view of the gas sensor element.

Fig. 3 is a sectional view of the gas sensor element.

Fig. 4 is a cross-sectional view of the annular guide portion, the longitudinal guide portion, and the pad around the flange portion of the element.

Fig. 5 is a view showing crack generation positions in the annular guide portion.

Fig. 6 is a cross-sectional view of the annular guide portion, the longitudinal guide portion, and the guard around the element flange portion.

Fig. 7 is a cross-sectional view of an element flange portion of another embodiment.

Description of the reference numerals

3. A gas sensor element; 21. an element main body; 23. an element flange portion; 23b, a front end facing surface; 27. an outer electrode; 28. an annular guide portion; 29. a longitudinal guide part.

Detailed Description

Embodiments of the present invention will be described below with reference to the accompanying drawings.

The gas sensor 1 of the present embodiment is attachable to an exhaust pipe of a vehicle such as an automobile or a motorcycle, for example, and detects the concentration of oxygen contained in exhaust gas in the exhaust pipe.

As shown in fig. 1, the gas sensor 1 has a gas sensor element 3, a separator 5, a blocking member 7, a terminal fitting 9, and a lead wire 11. Further, the gas sensor 1 has a main body metal housing 13, a guard 15, and an outer cylinder 16. The metal shell 13, the protector 15, and the outer cylinder 16 are disposed so as to cover the gas sensor element 3, the separator 5, and the blocking member 7. The outer cylinder 16 has an inner outer cylinder 17 and an outer cylinder 19.

The gas sensor 1 does not have a heater for heating the gas sensor element 3. That is, the gas sensor 1 activates the gas sensor element 3 by the heat of the exhaust gas to detect the oxygen concentration.

The gas sensor element 3 is formed using a solid electrolyte body having oxygen ion conductivity. As shown in fig. 2, the gas sensor element 3 has a bottomed cylindrical shape with a closed end portion 25, and has a cylindrical element body 21 extending in the direction of the axis O (hereinafter referred to as the axial direction). An element flange portion 23 protruding radially outward is formed on the outer periphery of the element main body 21 along the circumferential direction.

Zirconia (ZrO) was used as the solid electrolyte constituting the element body 21₂) In which yttrium oxide (Y) is added as a stabilizer₂O₃) Or a partially stabilized zirconia sintered body made of calcium oxide (CaO). The solid electrolyte constituting the element body 21 is not limited to these, and "alkaline earth metal oxide and ZrO" may be used₂Solid solution of (a), "" rare earth metal oxide and ZrO₂The solid solution of (3), and the like. Further, the above-mentioned substance may contain HfO₂The solid electrolyte body of (2) is used as the solid electrolyte body constituting the element main body 21.

An outer electrode 27 is formed on the outer peripheral surface of the element main body 21 at the distal end portion 25 of the gas sensor element 3. The outer electrode 27 is formed by forming Pt or a Pt alloy in a porous manner.

The surface of the element flange portion 23 is formed by a peak surface 23a, a front end facing surface 23b, and a rear end facing surface 23 c.

The peak surface 23a is located on the outermost side in the radial direction of the element flange portion 23, and is a surface parallel to the axial direction. The distal end facing surface 23b is a surface inclined from the distal end of the peak surface 23a toward the distal end of the element main body 21 so as to become closer to the axis O as the distance from the peak surface 23a becomes farther. The rear end facing surface 23c is a surface inclined from the rear end of the peak surface 23a toward the rear end of the element main body 21 so as to become closer to the axis O as the distance from the peak surface 23a becomes farther.

An annular guide portion 28 is formed on the peak surface 23a and the distal end facing surface 23b of the element flange portion 23.

The annular guide 28 contains, as main components, the following conductive oxides: contains a crystalline phase (i.e., perovskite phase) having a perovskite-type oxide crystal structure satisfying the following formula (1).

La_aM_bNi_cO_x……(1)

Here, the element M represents one or more of Co, Fe, and Cu, and a + b + c is 1, 1.25 ≦ x ≦ 1.75. The coefficients a, b, c satisfy the following relational expressions (2a), (2b), (2c), respectively.

0.459≤a≤0.535……(2a)

0.200≤b≤0.475……(2b)

0.025≤c≤0.350……(2c)

A vertical guide 29 formed of Pt or the like is formed on the outer peripheral surface of the element main body 21 so as to extend in the axial direction between the outer electrode 27 and the annular guide 28. The longitudinal guide portion 29 extends to the peak surface 23a of the element flange portion 23. The vertical guide 29 electrically connects the outer electrode 27 and the annular guide 28. A rectangular overlap region RO shown by a broken line in fig. 2 is a region where the vertical guide portion 29 and the annular guide portion 28 overlap.

As shown in fig. 1, an inner electrode 30 is formed on the inner peripheral surface of the gas sensor element 3. The inner electrode 30 is formed by forming Pt, a Pt alloy, or an oxide conductor in a porous manner. The outer electrode 27 is exposed to the exhaust gas at the front end portion 25 of the gas sensor element 3, and the inner electrode 30 is exposed to the reference gas, so that the gas sensor element 3 can detect the oxygen concentration in the exhaust gas. In the present embodiment, the reference gas is atmospheric air.

The separator 5 is a cylindrical member formed of an electrically insulating material (e.g., alumina). A through hole 35 into which the lead wire 11 is inserted is formed at the axial center of the separator 5. The separator 5 is disposed so as to have a gap 18 between the separator and an inner outer tube 17 covering the outer circumferential side thereof.

The plugging member 7 is a cylindrical sealing member formed of an electrically insulating material (for example, fluororubber). The blocking member 7 has a protruding portion 36 protruding radially outward at its rear end. The plugging member 7 has a lead wire insertion hole 37 at the axial center thereof into which the lead wire 11 is inserted. The front end surface 95 of the plugging member 7 is in close contact with the rear end surface 97 of the separator 5, and the lateral outer peripheral surface 98 of the plugging member 7 on the front end side of the protruding portion 36 is in close contact with the inner surface of the inner outer cylinder 17. That is, the closing member 7 closes the rear end side of the outer tube 16.

The lead wire protecting member 89 is supported with the flange portion 89b of the lead wire protecting member 89 sandwiched between the rear end facing surface 99 of the plugging member 7 and the front end facing surface 19a of the reduced diameter portion 19g of the outer cylindrical tube 19.

The reduced diameter portion 19g extends radially inward on the rear end side of the blocking member 7, and the distal end facing surface 19a of the reduced diameter portion 19g is formed as a surface facing the distal end side of the gas sensor 1. A lead insertion portion 19c into which the lead 11 and the lead protecting member 89 are inserted is formed in a central region of the reduced diameter portion 19 g.

The lead wire protecting member 89 is a cylindrical member having an inner diameter dimension capable of accommodating the lead wire 11, and is made of a material having flexibility, heat resistance, and insulation properties (for example, a glass tube, a resin tube, or the like). The lead protecting member 89 is installed to protect the lead 11 from flying objects (e.g., stones, water, etc.) from the outside.

The lead wire protecting member 89 has a plate-shaped flange portion 89b protruding outward in the direction perpendicular to the axial direction at the distal end portion 89 a. The flange portion 89b is not formed in a part of the lead wire protecting member 89 in the circumferential direction, but is formed over the entire circumference of the lead wire protecting member 89.

The flange portion 89b of the lead wire protecting member 89 is sandwiched between the distal end facing surface 19a of the reduced diameter portion 19g of the outer cylinder 19 and the rear end facing surface 99 of the closing member 7.

The terminal fitting 9 is a cylindrical member formed of a conductive material to transmit a sensor output to the outside. The terminal metal fitting 9 is configured to: is electrically connected to the lead wire 11, and is in electrical contact with the inner electrode 30 of the gas sensor element 3. The terminal fitting 9 has a flange portion 77 protruding outward in the radial direction (i.e., in the direction perpendicular to the axial direction) on the rear end side thereof. The flange portion 77 has three plate-like flange pieces 75.

The lead 11 has a core wire 65 and a covering portion 67 covering the outer periphery of the core wire 65.

The main body metal housing 13 is a cylindrical member formed of a metal material (e.g., iron or SUS 430). A step portion 39 protruding radially inward is formed on the inner peripheral surface of the metal shell 13. The step portion 39 is formed for the purpose of supporting the element flange portion 23 of the gas sensor element 3.

A screw portion 41 for attaching the gas sensor 1 to the exhaust pipe is formed on the outer peripheral surface of the metal shell 13 on the front end side. A hexagonal portion 43, to which an attachment tool is engaged when attaching and detaching the gas sensor 1 to and from the exhaust pipe, is formed in the metal shell 13 at a position closer to the rear end side than the threaded portion 41. Further, a cylindrical portion 45 is provided on the rear end side of the hexagonal portion 43 in the metal shell 13.

The protector 15 is a protective member formed of a metal material (e.g., SUS310S) and covering the tip end side of the gas sensor element 3, and the protector 15 introduces the exhaust gas into the gas sensor element 3 through a plurality of gas flow holes formed therein. The guard 15 is fixed so that the rear end edge thereof is sandwiched between the element flange portion 23 of the gas sensor element 3 and the step portion 39 of the metal case 13 via a pad 88 made of a conductive material.

In the gas sensor element 3, ceramic powder 47 made of talc and ceramic bush 49 made of alumina are disposed in a region on the rear end side of the element flange portion 23 and between the metal shell 13 and the gas sensor element 3 from the front end side toward the rear end side.

Further, a ferrule 53 formed of a metal material (e.g., SUS430) and a front end 55 of the inner outer cylinder 17 formed of a metal material (e.g., SUS304L) are disposed inside the rear end 51 of the cylindrical portion 45 of the main metal shell 13. The front end 55 of the inner outer cylinder 17 is formed in a shape expanding radially outward. That is, by tightening the rear end 51 of the cylindrical portion 45, the front end 55 of the inner outer cylinder 17 is sandwiched between the rear end 51 of the cylindrical portion 45 and the ceramic bush 49 via the metal ring 53, and the inner outer cylinder 17 is fixed to the metal shell 13.

A cylindrical filter 57 made of a resin material (e.g., PTFE) is disposed on the outer periphery of the inner outer tube 17, and an outer tube 19 made of SUS304L, for example, is disposed on the outer periphery of the filter 57. The filter portion 57 is permeable to air but can suppress the entry of moisture.

Then, the tightening part 19b of the outer cylinder 19 is tightened from the outer peripheral side to the inner radial side, whereby the inner outer cylinder 17, the filter part 57, and the outer cylinder 19 are integrally fixed. Then, by tightening the tightening portion 19h of the outer cylinder 19 from the outer peripheral side to the radially inner side, the inner outer cylinder 17 and the outer cylinder 19 are integrally fixed, and the lateral outer peripheral surface 98 of the plugging member 7 comes into close contact with the inner surface of the inner outer cylinder 17.

The inner outer cylinder 17 has a vent hole 59, and the outer cylinder 19 has a vent hole 61. That is, the inside and the outside of the gas sensor 1 can be ventilated through the vent hole 59, the vent hole 61, and the filter 57.

As shown in fig. 3, the outer electrode 27 and the inner electrode 30 are disposed so as to sandwich the element body 21 at the distal end portion 25 of the gas sensor element 3. The element main body 21 and the pair of electrodes (i.e., the outer electrode 27 and the inner electrode 30) constitute an oxygen concentration cell, and are capable of generating an electromotive force according to the oxygen concentration in the exhaust gas. That is, the outer electrode 27 is exposed to the exhaust gas at the front end portion 25 of the gas sensor element 3, and the inner electrode 30 is exposed to the reference gas, so that the gas sensor element 3 can detect the oxygen concentration in the exhaust gas.

As described above, the outer electrode 27 is electrically connected to the annular guide 28 via the vertical guide 29. The annular guide 28 is electrically connected to the main metal housing 13 via the pad 88 and the guard 15 formed of a conductive material. The shape and arrangement of the outer electrode 27 are merely examples, and various other shapes and arrangements may be adopted.

An inner electrode 30 is formed on the inner peripheral surface of the element body 21 of the gas sensor element 3. The inner electrode 30 has an inner detection electrode portion 30a and an inner lead portion 30 b.

The inner detection electrode portion 30a is formed so as to cover the inner surface of the distal end portion 25 of the element main body 21. The inner lead 30b is in contact with the inner detection electrode 30a at the inner detection electrode 30a, and is electrically connected to the terminal fitting 9. The inner detection electrode portion 30a and the inner guide portion 30b are integrally formed so as to cover the entire inner surface of the element main body 21.

That is, in the element main body 21 of the gas sensor element 3, the outer electrode 27 and the inner detection electrode portion 30a are formed in the front end side region F1, and the inner guide portion 30b is formed in the rear end side region F2. The distal end side region F1 of the element main body 21 corresponds to the distal end portion 25 of the element main body 21.

As shown in fig. 4, a part of the annular guide 28 and a part of the longitudinal guide 29 are disposed between the contact surface PC1 where the annular guide 28 and the pad 88 contact each other and the distal end facing surface 23 b. "a part of the annular guide portion 28 and a part of the longitudinal guide portion 29 are disposed between the contact surface PC1 and the distal end facing surface 23 b" corresponds to: a straight line extending from the contact face PC1 toward the leading end facing face 23b and perpendicular to the contact face PC1 (i.e., a normal line of the contact face PC 1) passes through the annular guide 28 and the longitudinal guide 29.

Next, a method for manufacturing the gas sensor element 3 will be described.

In step 1, an unsintered molded body is produced. Specifically, first, as for the powder of the solid electrolyte body as the material of the element main body 21, the following powder is prepared: for the treatment of zirconium oxide (ZrO)₂) Adding 5 mol% of yttrium oxide (Y) as stabilizer₂O₃) The resultant powder (hereinafter also referred to as 5YSZ) was added with alumina powder. When the total material powder of the element main body 21 was set to 100 mass%, the content of 5YSZ was 99.6 mass%, and the content of alumina powder was 0.4% by mass. After the powder was pressed, it was cut into a cylindrical shape to obtain an unsintered molded body.

Next, in step 2, a slurry containing platinum (Pt) and zirconia is applied to the formation positions of the outer electrode 27, the longitudinal guide 29, and the inner electrode 30. In this case, as the slurry for forming the outer electrode 27 and the longitudinal guide 29, a slurry obtained by adding 15 mass% monoclinic zirconia to platinum was used. As the paste for forming inner electrode 30, a paste obtained by adding 15 mass% of "99.6 mass% of 5YSZ/0.4 mass% of mixed powder of alumina" (i.e., the same composition as that of element body 21) to platinum was used.

Next, in step 3, a slurry for the annular guide 28 is prepared. When preparing the slurry for the annular guide 28, first, raw material powders of conductive oxides are weighed, then wet-mixed and dried to prepare a raw material powder mixture, and the mixture is calcined at 700 to 1300 ℃ for 1 to 5 hours to prepare a calcined powder. Then, the calcined powder is pulverized by a wet ball mill or the like to be adjusted to a predetermined particle size. In this case, La (OH) can be used as the raw material powder of the perovskite phase₃Or La₂O₃And Co₃O₄、Fe₂O₃And NiO. Then, the calcined powder adjusted to a predetermined particle size is mixed by a wet ball mill or the like, and the powder is dissolved in a solvent such as terpineol or butyl carbitol together with a binder such as ethyl cellulose to prepare a slurry.

Next, in the 4 th step, the slurry of the annular guide 28 is applied to the formation position of the annular guide 28.

In the next step 5, the green compact coated with each slurry is dried and then fired at a predetermined firing temperature. The firing temperature is, for example, 1250 ℃ or higher and 1450 ℃ or lower, preferably 1350. + -. 50 ℃.

The gas sensor element 3 can be manufactured by performing the above steps.

The gas sensor element 3 configured as described above includes the element body 21, the outer electrode 27, the longitudinal guide 29, and the annular guide 28.

The element main body 21 is formed by: the solid electrolyte body is mainly formed in a bottomed cylindrical shape extending in the axial direction and having a closed tip, and has an element flange portion 23 protruding radially outward. The vertical guide 29 contains a noble metal, and is formed on the outer surface of the element main body 21 so as to extend from a position closer to the distal end side than the element flange 23 toward the element flange 23. The annular guide portion 28 overlaps the longitudinal guide portion 29, and is formed along the circumferential direction of the element main body 21 on at least the distal end facing surface 23b facing the distal end side in the element flange portion 23. Further, the annular guide portion 28 is formed such that: the length of the annular guide portion 28 in the circumferential direction of the element main body 21 on the leading end facing surface 23b is larger than the length of the longitudinal guide portion 29 in the circumferential direction at the overlapping region RO where the longitudinal guide portion 29 and the annular guide portion 28 overlap. In the gas sensor element 3, the annular guide 28 contains a conductive oxide as a main component. The "main component" means a component that accounts for more than 50 mass% of all components constituting the target site (i.e., the annular guide 28).

In this way, in the gas sensor element 3, the amount of the noble metal used in the annular guide 28 can be reduced by using a conductive oxide which is less expensive than the noble metal as the main component of the annular guide 28, and the manufacturing cost of the gas sensor element 3 can be reduced.

The annular guide portion 28 and the longitudinal guide portion 29 are formed so as to extend to the peak surface 23a on the rear end side of the distal end facing surface 23b in the element flange portion 23, and the annular guide portion 28 and the longitudinal guide portion 29 are in contact with each other at the peak surface 23 a.

Thus, in the gas sensor element 3, since a load is applied to the distal end facing surface 23b in a manufacturing process (hereinafter, referred to as an assembly process) of assembling the gas sensor element 3, the metal shell 13 for holding the gas sensor element 3, and the protector 15, the annular guide portion 28 formed on the distal end facing surface 23b may be detached from the element flange portion 23, and even in this case, the annular guide portion 28 and the longitudinal guide portion 29 may be in contact with each other on the peak surface 23 a. Therefore, the gas sensor element 3 can improve the reliability of conduction between the annular guide portion 28 and the vertical guide portion 29 in the above-described assembly process. In addition, the reason why the annular guide portion 28 is detached from the element flange portion 23 in the above-described assembly process is that the conductive oxide, which is the main component of the annular guide portion 28, is not ductile unlike a noble metal such as platinum.

The gas sensor 1 includes a gas sensor element 3, a metal case 13 for holding the gas sensor element 3, and a protector 15. In this way, since the gas sensor 1 includes the gas sensor element 3, the same effect as that of the gas sensor element 3 can be obtained. That is, the gas sensor 1 can reduce the manufacturing cost of the gas sensor 1 by reducing the manufacturing cost of the gas sensor element 3.

In the gas sensor 1, the annular guide portion 28, the metal shell 13, and the guard 15 are electrically connected to each other by interposing the pad 88 between the annular guide portion 28 and the metal shell 13 and the guard 15. In the gas sensor 1, a part of the annular guide 28 and a part of the longitudinal guide 29 are disposed between the contact surface PC1 where the annular guide 28 and the pad 88 contact each other and the distal end facing surface 23 b.

In the gas sensor 1 configured as described above, even when the annular guide 28 falls off at a position on the front end side (i.e., radially inward) of the front end side end of the contact surface PC1 in the above-described assembly step, a state in which a part of the annular guide 28 and a part of the longitudinal guide 29 are in contact with each other can be maintained at a position on the rear end side (i.e., radially outward) of the front end side end of the contact surface PC 1. In the above-described assembling process, the annular guide portion 28 is more likely to come off at a position closer to the front end side than the front end side end portion of the contact surface PC1, as compared with a position closer to the rear end side than the front end side end portion of the contact surface PC 1. Fig. 5 is a view of the annular guide portion 28 as viewed from the distal end side, and shows a state in which the crack CR is generated in the annular guide portion 28 at a position radially inward of the radially inner end EF of the region RC in contact with the pad 88. This improves the reliability of conduction between the annular guide 28 and the vertical guide 29 in the assembly process of the gas sensor 1.

In the above-described embodiment, the element flange portion 23 corresponds to a flange portion, the outer electrode 27 and the longitudinal guide portion 29 correspond to an outer electrode, the annular guide portion 28 corresponds to a flange guide portion, and the peak surface 23a corresponds to a rear end side outer peripheral surface.

The metal shell 13 and the protector 15 correspond to a holding member, the pad 88 corresponds to a conductive member, and the contact surface PC1 corresponds to the 2 nd contact surface.

While one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and can be implemented by various modifications.

For example, although the above embodiment shows the mode in which the annular guide portion 28 is disposed on the vertical guide portion 29, the vertical guide portion 29 may be disposed on the annular guide portion 28. However, since the vertical guide 29 is thin, when the vertical guide 29 is disposed on the annular guide 28, disconnection is likely to occur in the vertical guide 29. Therefore, it is preferable that the annular guide portion 28 is disposed on the vertical guide portion 29.

In the above embodiment, the annular guide 28 is described as containing a conductive oxide as a main component, but may contain a component other than a conductive oxide (for example, ceria to which rare earth is added).

In the above embodiment, the guide portion (i.e., the flange guide portion) formed in the element flange portion 23 is formed in an annular shape, but an end ring shape or an arc shape may be used in which the length of the region where the vertical guide portion 29 and the annular guide portion 28 overlap each other along the circumferential direction of the element main body 21 is longer than the vertical guide portion 29. In the above-described assembly process, in order to ensure contact between the flange guide and the pad 88, it is desirable that the axial length of the flange guide be greater than the axial length of the pad 88.

In the above embodiment, the annular guide portion 28 is formed on the entire distal end facing surface 23b, but the annular guide portion 28 may be formed in a part of the distal end facing surface 23 b.

In the above embodiment, the pad 88 is interposed between the annular guide portion 28 and the guard 15 to electrically connect them, but the annular guide portion 28 and the guard 15 may be directly contacted without interposing the pad 88 as shown in fig. 6. In this case, a part of the annular guide portion 28 and a part of the longitudinal guide portion 29 are disposed between the contact surface PC2 where the annular guide portion 28 and the protector 15 contact each other and the distal end facing surface 23 b. "a part of the annular guide 28 and a part of the longitudinal guide 29 are arranged between the contact surface PC2 and the distal end facing surface 23 b" corresponds to a straight line extending from the contact surface PC2 toward the distal end facing surface 23b and perpendicular to the contact surface PC2 (i.e., a normal line of the contact surface PC 2) passing through the annular guide 28 and the longitudinal guide 29. The contact surface PC2 corresponds to the 1 st contact surface.

In the above embodiment, the surface of the element flange portion 23 is bent at the boundary between the peak surface 23a and the distal end facing surface 23 b. But may be made to curve at the outermost point PO located on the outermost side in the radial direction in the element flange portion 23, as shown in fig. 7. In this case, the rear end side end portion of the distal end facing surface 23b is the outermost point PO. Further, as the leading end side end of the leading end facing surface 23b moves toward the trailing end side, the angle θ formed by the normal vector VN of the leading end facing surface 23b and the axis O gradually approaches 90 °. The position where the angle θ changes from less than 90 ° to 90 ° is the rear end side end of the distal end facing surface 23 b. The angle θ of the normal vector VN1 at the outermost point PO to the axis O is 90 °.

In the above embodiments, the functions of one component may be shared by a plurality of components, or the functions of a plurality of components may be exerted by one component. Moreover, a part of the structure of each of the above embodiments may be omitted. At least a part of the structures of the above embodiments may be added to or replaced with the structures of the other above embodiments. In addition, all the modes included in the technical idea specified by the contents of the claims are the embodiments of the present invention.