JP2015135252A - gas sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas sensor capable of easily adjusting a positional relationship in a circumferential direction of a gas circulation hole of a protector and a detecting portion to assemble, and improving the responsivity of gas detection of the detecting portion.SOLUTION: A gas sensor includes: a sensor element structure that has a body fitting 11 which has a rear end facing surface 18a at a par of an inner surface configuring an insertion hole 18 and a bulging portion 30 projecting outward in a diametrical direction with a detecting portion, and in which a tip end facing surface 30a of the bulging portion 30 is inserted in the insertion hole 18 while engaged with the rear end facing surface 18a of the main body fitting 11; a flange portion 51f sandwiched between the rear end facing surface 18a of the main body fitting 11 and the tip end facing surface 30a of the bulging portion; and a protector 51 which is disposed on a tip end side than the flange portion 51f, and has a cylindrical portion 51t covering the detecting portion and provided with a gas circulation hole 56. On the flange portion 51f, a regulating portion 51j fitted with a fitting portion 30e provided on the bulging portion is formed.

Description

  The present invention relates to a gas sensor that is exposed to a gas to be detected and has a detector that detects a specific gas component therein covered with a protector.

Conventionally, it is used by being attached to an exhaust pipe of an automobile, etc., and an electromotive force having a different magnitude or resistance value is generated depending on the concentration of a specific gas (for example, NOx (nitrogen oxide) or oxygen) in the exhaust gas. There is known a gas sensor including a sensor element that changes. A detection unit that detects a specific gas component is provided on the tip side of the sensor element, and the detection unit detects the specific gas component by heating the detection unit with a heater or the like. On the other hand, if water droplets or the like contained in the exhaust gas adhere to the detection unit (being wet) when the detection unit is heated to a high temperature, the sensor element may be damaged by a thermal shock. Therefore, in order to protect the detection portion, a bottomed cylindrical protector that covers the detection portion and has a gas flow hole is attached to the front end side of the casing (metal shell).
By the way, as a method of attaching the protector to the metal shell, welding or caulking has been conventionally performed. However, in the case of welding, a welding process is necessary, and in the case of caulking, caulking is accompanied by the use of a gas sensor. There was a problem that the part became hot and softened and loosened. Therefore, a flange-like portion (hereinafter referred to as a flange portion) projecting radially outward is formed on the rear end side of the protector. This flange portion is formed on the inner surface of the casing, and the rear-facing surface and the flange portion of the sensor element. A technology has been developed in which the ceramic holder is fixed by being sandwiched between the ceramic holder and the tip-facing surface of the ceramic holder that is engaged with the tip side (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 11-190715

  By the way, in recent years, the positional relationship in the circumferential direction between the detection part of the sensor element (particularly, the electrode provided in the detection part) and the gas flow hole of the protector has been regarded as important. For example, in the case of a plate-shaped sensor element, in order to improve the gas detection responsiveness, the circumference between the gas flow hole and the detection part of the sensor element (particularly, the electrode exposed to the gas to be measured provided in the detection part). It is necessary to define the positional relationship in the direction as a specific relationship. On the other hand, even in the case of a cylindrical sensor element (detection unit), in recent years, an outer electrode may be formed on a part of the radial direction instead of the entire circumference of the outer surface of the element. In order to improve the gas detection responsiveness in the same manner as in the above, the relationship in the circumferential direction between the gas flow hole of the protector and the detection part of the sensor element (especially the outer electrode exposed to the gas to be measured provided in the detection part) Must be specified in a specific relationship.

  On the other hand, as a method for defining the positional relationship between the gas flow hole of the protector and the sensor element (detection unit), for example, the shape of the gas flow hole or the sensor element (detection unit) is image-recognized and the relationship between the two is adjusted However, there is a problem that a complicated computer system is required, resulting in an increase in cost and excessive equipment.

  The present invention has been made in view of the present situation, and can easily adjust and assemble the positional relationship in the circumferential direction between the gas flow hole of the protector and the detection unit, and the response of the gas detection of the detection unit An object of the present invention is to provide a gas sensor with improved performance.

  The gas sensor of the present invention has an insertion hole penetrating in the axial direction, and a metal shell having an annular rear end-facing surface facing the rear end side at a part of the inner surface constituting the insertion hole, and the front end side of the metal sensor A sensor element structure comprising one or a plurality of members having a detection portion for detecting a specific gas and a bulging portion provided on the rear end side of the detection portion and projecting radially outward. A sensor element that is inserted through the insertion hole and protrudes the detection part further to the front end side than the front end of the metal shell while the front surface of the bulging part is engaged with the rear end surface of the metal shell A structure, a flange portion sandwiched between the rear-facing surface of the metal shell and the front-facing surface of the bulging portion, and disposed on the front end side from the flange portion, covers the detection portion and distributes gas Protector having a cylindrical portion provided with a hole The provided, the flange portion, wherein the restricting portion to be fitted into the fitting portion provided on the bulging portion.

  According to this gas sensor, the relationship between the position in the circumferential direction between the gas flow hole of the protector and the detection portion of the sensor element structure is obtained by fitting the restriction portion of the flange portion and the fitting portion of the bulging portion. Can be specified in a specific relationship. For this reason, the flow of the gas to be detected flowing to the detection unit via the gas flow hole is optimized, and the response of gas detection is improved. Moreover, since the positional relationship between the protector and the detecting portion in the circumferential direction can be defined as a specific relationship only by fitting the restricting portion and the fitting portion, it can be mechanically adjusted and assembled at a low cost.

The protector may be a single protector, or may be a protector that covers a plurality of sensor element structures, such as a double protector composed of an outer protector and an inner protector. In the case of a plurality of protectors, the gas flow of the inner protector (for example, the inner protector in the case of a double protector) closest to the sensor element structure (detection unit) by fitting the restricting portion and the fitting portion. The positional relationship between the hole and the detection unit in the circumferential direction may be a specific relationship.
Examples of the “sensor element structure composed of one or a plurality of members” include the following structures. For example, as a sensor element structure formed of one member, a sensor element having a detection portion on its front end side and a protrusion protruding outward in the radial direction can be given. In addition, for example, as a sensor structure including a plurality of members, a sensor element having a detection part on its front end side and a protruding part protruding radially outward, and supporting the sensor element and surrounding the sensor element Including an annular holder surrounding the. Furthermore, as a sensor structure composed of a plurality of members, for example, a sensor structure including a plate-type sensor element having a detection part on its own tip side and an annular holder surrounding the plate-type sensor element is cited.

Further, in the gas sensor of the present invention, the restricting portion is a convex portion protruding from the rear end facing surface of the flange portion toward the rear end side, or a recess from the rear end facing surface of the flange portion toward the front end side. At least one of the concave portions, and the fitting portion is fitted with the convex portion of the restricting portion, and is a concave portion that is recessed from the front-facing surface of the bulging portion toward the rear end side, or It is preferable that it is at least any one of the convex part which fits with the said recessed part of a control part, and protrudes toward the front end side from the front surface direction of the said bulging part.
According to this gas sensor, the convex portion is formed as the restricting portion and the concave portion is formed as the fitting portion, or the concave portion is formed as the restricting portion and the convex portion is formed as the fitting portion. It becomes possible to easily fit the part and the fitting part. Therefore, the positional relationship in the circumferential direction between the gas flow hole of the protector and the detection part of the sensor element structure can be easily defined as a specific relationship.

  Note that one fitting portion and one restriction portion may be formed, or a plurality of fitting portions and restriction portions may be formed. In the case of forming a plurality, a combination of forming the concave portion and the convex portion as the fitting portion while forming the convex portion and the concave portion as the restricting portion may be used.

In the gas sensor of the present invention, the fitting portion is a convex portion that protrudes toward the tip side from the tip-facing surface of the bulging portion, and the restricting portion includes the convex portion of the fitting portion. A notch that is fitted with a through-hole penetrating the flange portion in the axial direction or with the convex portion of the fitting portion, and a part of the flange portion is notched in the radial direction. It is preferable that
According to this gas sensor, it is possible to easily fit the restriction portion and the fitting portion by forming the through hole or the notch as the restriction portion while forming the convex portion as the fitting portion. Therefore, the positional relationship in the circumferential direction between the gas flow hole of the protector and the detection part of the sensor element structure can be easily defined as a specific relationship.

On the other hand, another gas sensor of the present invention has an insertion hole penetrating in the axial direction, and a metal shell having an annular rear end facing surface facing the rear end side as a part of an inner surface constituting the insertion hole, A sensor element structure comprising one or a plurality of members, which has a detection unit for detecting a specific gas on its front end side, and has a bulging portion that is on the rear end side of the detection unit and protrudes radially outward. The front-end facing surface of the bulging portion is engaged with the rear-end-facing surface of the metal shell, and is inserted into the insertion hole so that the detection portion protrudes further to the front side than the front end of the metal shell. A sensor element structure, a flange portion sandwiched between the rear end facing surface of the metal shell and the front end facing surface of the bulging portion, and disposed on the front end side from the flange portion, covering the detection portion A protector having a cylindrical portion provided with a gas flow hole The metal shell is formed with a protrusion that protrudes from the rear end-facing surface of the metal shell toward the rear edge, and the flange portion is fitted with the protrusion. In addition, a through hole penetrating the flange portion in the axial direction or a fitting portion with the protruding portion, and a notch is formed by cutting a part of the flange portion in the radial direction,
The bulged portion is formed with a concave portion that fits into the protruding portion and that is recessed from the front-facing surface of the bulged portion toward the rear end side.

  According to this gas sensor, the through hole or notch of the flange portion and the concave portion of the bulging portion are fitted to the protruding portion of the metal shell, so that the gas flow hole of the protector and the detection portion of the sensor element structure The positional relationship in the circumferential direction can be defined as a specific relationship. For this reason, the flow of the gas to be detected flowing to the detection unit via the gas flow hole is optimized, and the response of gas detection is improved. In addition, the positional relationship in the circumferential direction between the protector and the detection unit can be defined as a specific relationship only by fitting the through hole or notch, the concave portion, and the protruding portion. Can be assembled.

Further, in the gas sensor of the present invention, the sensor element structure has an annular shape having a plate-like sensor element having the detection unit on its tip side and a substantially rectangular element insertion hole through which the sensor element is inserted. It is preferable that the holder constitutes the bulging portion.
According to this gas sensor, since the positional relationship between the plate-shaped sensor element and the annular holder has a specific relationship due to the substantially rectangular element insertion hole, the holder forms the bulging portion, so that the plate shape Also in this sensor element, the positional relationship in the circumferential direction between the gas flow hole of the protector and the detection portion of the sensor element can be defined as a specific relationship.

Further, in the gas sensor of the present invention, the sensor element structure includes the sensor unit provided on the tip side of the sensor element structure, the sensor element including a projecting portion protruding radially outward, and the projecting portion of the sensor element. A ring-shaped insulating holder that engages with the front-facing surface of the rear-end-facing surface, and the insulating holder constitutes the bulging portion. At least one of a convex portion projecting toward the front end side or a concave portion recessed from the surface facing the front end of the projection portion toward the rear end side is formed, and the convex portion of the projection portion is formed on the insulating holder. And a recess recessed from the rear end facing surface of the insulating holder toward the front end side, or the concave portion of the protrusion, and from the rear end facing surface of the insulating holder to the rear end side. At least the convex part protruding toward It is preferred that one is formed or Re.
According to this gas sensor, the insulating holder constitutes the bulging portion, and the convex portion provided in the insulating holder and the concave portion provided in the protruding portion are fitted, or provided in the concave portion and the protruding portion provided in the insulating holder. Even in a sensor element structure having a sensor element having an insulating holder and a protrusion by fitting the convex portion, the relationship between the position of the protector gas flow hole and the detection portion in the circumferential direction is a specific relationship. Can be specified.

  In addition, it may be a combination of forming a convex portion on the insulating holder and forming a concave portion on the protruding portion, or a combination of forming a concave portion on the insulating holder and forming a convex portion on the protruding portion, A combination of forming the convex portion and the concave portion on the insulating holder and forming the concave portion and the convex portion on the protruding portion may be used.

  According to the present invention, in the gas sensor, the positional relationship in the circumferential direction between the gas flow hole of the protector and the detection unit can be easily adjusted and assembled, and the gas detection response of the detection unit can be improved.

It is sectional drawing of the gas sensor concerning Embodiment of 1st invention of this invention. It is a perspective view which shows the fixation aspect of an inner protector and the ceramic holder which is a part of sensor element structure. It is a figure which shows the process of assembling a sensor element structure to a metal shell. It is a figure which shows the last process of manufacture of a gas sensor, and an assembly. It is a fragmentary sectional view showing the modification of the gas sensor concerning the embodiment of the 1st invention. It is a perspective view which shows the fixed aspect of the inner side protector in the gas sensor of FIG. 5, and the ceramic holder which is a part of sensor element structure. It is sectional drawing of the gas sensor concerning Embodiment of 2nd invention of this invention. It is the elements on larger scale of FIG. It is a perspective view which shows the fixation aspect with the inner side protector in the gas sensor which concerns on 2nd invention, the insulation holder which is a sensor element structure, and a sensor element. It is a perspective view which shows a cylindrical sensor element.

A gas sensor according to an embodiment of the first invention will be described in detail with reference to FIGS. However, the present embodiment embodies an all-range air-fuel ratio gas sensor that detects the oxygen concentration in the exhaust gas. Therefore, first, the overall configuration of the gas sensor 1 will be briefly described, and then the configuration together with each part. Will be described in more detail.
In FIG. 1, a gas sensor (full-range air-fuel ratio gas sensor) 1 includes a sensor element 21, a ceramic holder 30 having a rectangular element insertion hole 32 through which the sensor element 21 is inserted, and a main body surrounding the periphery of the ceramic holder 30 in the radial direction. And a metal fitting 11.
The sensor element 21 that has passed through the element insertion hole 32 of the ceramic holder 30 has a sealing material 41 (talc in this example) disposed on the rear end surface side (the upper side in the drawing) of the ceramic holder 30, a sleeve 43 made of an insulating material, By compressing in the front-rear direction via the ring washer 45, the inner side of the metal shell 11 is fixed while being kept airtight in the front-rear direction. And the detection part 22 at the front end side of the sensor element 21 protrudes from the ceramic holder 30 and the metal shell 11 to the front end. Further, the portion near the rear end 29 including the rear end 29 of the sensor element 21 protrudes rearward from the sleeve 43 and the metal shell 11, and the electrode terminal 24 formed at the portion closer to the rear end 29 passes through the sealing material 85 to the outside. The terminal fittings 75 provided at the tips of the lead wires 71 drawn out are pressed and electrically connected. Further, a portion near the rear end 29 of the sensor element 21 including the electrode terminal 24 is covered with a protective cylinder 81. This will be described in more detail below.
The ceramic holder 30 and the sensor element 21 correspond to a “sensor element structure” in the claims. The ceramic holder 30 corresponds to a “bulged portion” in the claims.

  The sensor element 21 extends in the direction of the axis O, and a pair of electrodes (not shown) such as detection electrodes are arranged on the tip side (lower side in the figure) directed toward the measurement object, and a specific gas component in the gas to be detected. It has a belt plate shape (plate shape) provided with a detection unit 22 for detection. The cross section of the sensor element 21 has a rectangular shape having a substantially constant size, and is formed as an elongated body mainly made of ceramic (solid electrolyte or the like). The detection portion 22 of the sensor element 21 is covered with a porous protective layer 25 made of alumina, spinel, or the like, and the protective layer 25 is formed at the thickness of the protective layer 25 (for example, 0.5 to 0.6 mm). The cross section is large (thickness is exaggerated). The sensor element 21 itself is the same as a conventionally known one, and a pair of electrodes forming the detection unit 22 is disposed near the tip of the solid electrolyte (member). The electrode terminal 24 for connecting the lead wire 71 for extracting the output is exposed and formed. In this example, a heater (not shown) is provided in the sensor element 21 inside the ceramic material formed in a laminated form on the solid electrolyte (member) in the vicinity of the front end. The electrode terminal 24 for connecting the lead wire 71 for applying a voltage to the heater is exposed. Although not shown in the drawings, these electrode terminals 24 are formed in a vertically long rectangle. For example, three or two electrode terminals 24 are arranged horizontally on the wide surface (both sides) of the band plate near the rear end 29 of the sensor element 21. Are lined up.

  The metal shell 11 has an insertion hole 18 penetrating in the direction of the axis O, and has a cylindrical shape with concentric and different diameters. On the inner surface 17 of the insertion hole 18, a tapered rear end-facing surface 18 a that is tapered toward the front end is formed. On the other hand, the front end side of the metal shell 11 has a small-diameter cylindrical annular portion (hereinafter also referred to as a cylindrical portion) 12 for externally fitting and fixing an outer protector 61 to be described later. The upper outer peripheral surface is provided with a screw 13 having a larger diameter than that for fixing to the engine exhaust pipe. In addition, a polygonal portion 14 for screwing the sensor 1 with the screw 13 is provided behind it. Further, behind the polygonal portion 14, a cylindrical portion 15 for externally fitting and welding a protective cylinder (outer cylinder) 81 that covers the back of the gas sensor 1 is provided, and the outer diameter is provided behind it. A small and thin caulking cylindrical portion 16 is provided. The caulking cylindrical portion 16 is bent inward in FIG. 1 after caulking. A gasket 19 for sealing at the time of screwing is attached to the lower surface of the polygonal portion 14.

A ceramic holder 30 made of an insulating ceramic (for example, alumina) and formed in a substantially short cylindrical shape is disposed inside the insertion hole 18 of the metal shell 11. As shown in FIG. 2, a tip-facing surface 30 a that is tapered toward the tip is formed on the outer peripheral side of the tip of the ceramic holder 30, and the inner peripheral side of the tip-facing surface 30 a is the element insertion hole 32. The recess 35 is recessed toward the rear end while communicating with the front end. Then, as will be described later, the ceramic holder 30 is attached to the rear end of the metal shell 11 with the flange portion 51f of the inner protector 51 sandwiched between the front surface 30a and the rear surface 18a of the metal shell 11. It is positioned in the metal shell 11 while being engaged with the facing surface 18a, and is fitted in a gap.
On the other hand, the element insertion hole 32 is provided at the center of the ceramic holder 30 and is substantially the same as the cross section of the sensor element 21 so that a portion of the sensor element 21 on the rear end side with respect to the protective layer 25 passes without a gap. The size of the rectangular opening. The sensor element 21 is passed through the element insertion hole 32 of the ceramic holder 30, and the tip of the sensor element 21 protrudes further forward than the tip-facing surface 30 a of the ceramic holder 30 and the tip 12 a of the metal shell 11. The rear end portion 26 of the protective layer 25 is accommodated in the concave hole 35, and the protective layer 25 is separated from the concave hole 35.

On the other hand, at the tip portion of the sensor element 21, in this embodiment, a protector 60 having a two-layer structure of a bottomed cylindrical inner protector 51 and an outer protector 61 that is spaced apart from the outer periphery of the inner protector 51. Is covered.
The inner protector 51 is connected to the cylindrical portion 51t that covers the circumferential direction of the detecting portion 22 and the rear end edge of the cylindrical portion 51t, expands radially outward, and is substantially the same taper as the rear end facing surface 18a of the metal shell 11. A tapered flange portion 51f having a corner is integrally formed (see FIG. 2). Further, for example, eight vent holes 56 are provided in the circumferential direction on the rear end side of the cylindrical portion 51t of the inner protector 51, and for example, four discharge holes 53 are provided on the distal end side in the circumferential direction (see FIG. 2).
The inner protector 51 corresponds to a “protector” in the claims. The vent hole 56 corresponds to a “gas flow hole” in the claims.
Similarly, the outer protector 61 has a cylindrical portion 61t that covers the circumferential direction of the cylindrical portion 51t of the inner protector 51, and, for example, eight vent holes 67 are provided in the circumferential direction near the tip of the cylindrical portion 61t. Also, a discharge hole 69 is provided at the center of the bottom of the outer protector 61.
The rear end side of the cylindrical portion 51t of the inner protector 51 is accommodated inside the cylindrical portion 12 of the metal shell 11, and between the front end facing surface 30a of the ceramic holder 30 and the rear end facing surface 18a of the main metal shell 11. Further, the flange portion 51 f of the inner protector 51 is sandwiched, and the inner protector 51 is fixed to the metal shell 11.
On the other hand, the outer protector 61 is welded with the rear end portion of the metal shell 11 being fitted to the cylindrical portion 12 of the metal shell 11 while being fitted to the inner protector 51 with a gap.

On the other hand, each electrode terminal 24 formed near the rear end 29 of the sensor element 21 has each terminal fitting 75 provided at the tip of each lead wire 71 drawn out through the sealing material 85 to the outside due to its spring property. They are pressed and electrically connected. In the gas sensor 1 of the present embodiment, each terminal fitting 75 including the pressure contact portion is provided in a terminal fitting holding member (separator) 91 made of an insulating material disposed in a protective cylinder (metal cylinder) 81 having a different diameter cylindrical shape. In each accommodating part provided in each, it is provided by opposing arrangement | positioning, respectively. The terminal fitting holding member 91 is restricted from moving in the radial direction and the distal end side via an annular support member 80 fixed in a protective cylinder (metal cylinder) 81. The rear end of the gas sensor 1 is covered by fitting the front end portion (large diameter cylindrical portion) 82 of the protective cylinder 81 to the cylindrical portion 15 near the rear end of the metal shell 11 and welding it. The lead wire 71 is drawn out through a sealing material (for example, rubber) 85 disposed inside the small-diameter cylindrical portion 83 at the rear end of the protective cylinder 81, and the small-diameter cylindrical portion 83 is reduced in diameter. By crimping and compressing the sealing material 85, the airtightness of this part is maintained.
Incidentally, this sealing material 85 is arranged in such a manner that the rear end of the terminal fitting holding member 91 is pushed forward, whereby the mounting stability of the terminal fitting holding member 91 and the terminal fitting 75 provided therein is improved. It has been. The terminal fitting holding member 91 has a flange 93 formed on the outer periphery thereof supported on an annular support member 80 fixed to the inside of the protective cylinder 81, and receives the compressive force of the sealing material 85. ing.

Next, with reference to FIG. 2, the fixation aspect of the inner protector 51 and the ceramic holder 30 which is a part of the sensor element structure, which is a gist of the present invention, will be described. In FIG. 2, illustration of the sensor element 21 which is another component of the sensor element structure is omitted. A method for assembling the sensor element structure will be described later.
On the flange portion 51f of the inner protector 51, a convex portion 51j protruding from the rear end facing surface 51a of the flange portion 51f toward the rear end side is formed by pressing. On the other hand, the ceramic holder 30 is formed with a concave portion 30e that fits with the convex portion 51j and that is recessed from the front end facing surface 30a of the ceramic holder 30 toward the rear end side. Then, the cylindrical portion 51t of the inner protector 51 is inserted into the rear end side of the metal shell 11, the flange portion 51f is locked to the rear end facing surface 18a of the metal shell 11, and the ceramic holder 30 is attached to the rear end of the metal shell 11. When the flange portion 51f is engaged with the front end facing surface 30a of the ceramic holder 30, the convex portion 51j of the flange portion 51f is engaged with the concave portion 30e while the main body and the ceramic holder 30 are A flange portion 51 f is sandwiched between the metal fitting 11.
Note that the convex portion 51j corresponds to a “restricting portion” in the claims, and the concave portion 30e corresponds to a “fitting portion” in the claims.
Thus, the convex part 51j of the flange part 51f and the concave part 30e of the ceramic holder 30 are fitted, so that the gas passage hole (vent hole 56) of the inner protector 51 and the element insertion hole 32 of the ceramic holder 30 are inserted. The relationship between the position of the sensor element 21 and the detection unit 22 in the circumferential direction can be defined as a specific relationship. For this reason, the flow of the gas to be detected flowing to the detection unit 22 through the gas flow hole is optimized, and the response of gas detection is improved. Moreover, since the positional relationship in the circumferential direction between the inner protector 51 and the detection portion 22 of the sensor element 21 can be defined as a specific relationship only by fitting the convex portion 51j of the flange portion 51f and the concave portion 30e of the ceramic holder 30. It can be adjusted and assembled mechanically at low cost.
Furthermore, since it has fitted using the convex part 51j of the flange part 51f, and the recessed part 30e of the ceramic holder 30, the position in the circumferential direction of the gas flow hole of the inner side protector 51 and the detection part 22 of the sensor element 21 is fitted. Relationships can be easily specified for specific relationships.
In addition, since the positional relationship between the plate-shaped sensor element 21 and the annular ceramic holder 30 has a specific relationship due to the substantially rectangular element insertion hole 32, the inner protector 51 is also included in the plate-shaped sensor element 21. The positional relationship in the circumferential direction between the gas flow hole and the detection unit 22 of the sensor element 21 can be defined as a specific relationship.

Next, a method for assembling the gas sensor 1 will be described.
In the gas sensor 1 of this example, as described above, the sealing material 41 (talc in this example) is disposed in a filled state on the rear end surface side of the ceramic holder 30 provided in the metal shell 11, and the sealing material 41 A thin sleeve 43 for caulking that is connected to the cylindrical portion 15 near the rear end of the metal shell 11 is bent inward and compressed to the front end side via a ring washer 45. ing. And by this compression, an internal sealing material etc. are compressed and the sensor element 21 is airtightly fixed inside the metal shell 11.
The sensor element 21 is fixed as shown on the left side of FIG. That is, the rear end 29 of the sensor element 21 is set as an assembly work product through each element insertion hole provided in the ceramic holder 30, the sealing material 41, and the sleeve 43. On the other hand, as shown in FIG. 2, an inner protector 51 is inserted in advance into the inner hole 18 of the metal fitting body 11. And this assembly work in process is inserted (arranged) into the inner hole 18 of the metal fitting body 11 as shown in the lower part of the left figure of FIG. As a result, the flange portion 51 f is sandwiched between the ceramic holder 30 and the metal shell 11.
Then, a ring washer 45 is arranged at the rear end of the sleeve 43 and inside the caulking cylindrical portion 16 at the rear end of the metal shell 11, and the tip 23 of the sensor element 21 is projected by an appropriate amount. Next, the metal shell 11 in this state is positioned and supported by a jig 201 as shown in the right figure of FIG. In this support, the lower surface of the polygonal portion 14 of the metal shell 11 is brought into contact with the positioning portion 205 of the jig 201. Thereafter, the crimping cylindrical portion 16 is compressed to the tip side and bent inward with a crimping die 210 as illustrated in FIG. Thereby, the sensor element structure including the sensor element 21 and the ceramic holder 30 and the inner protector 51 are fixed to the inside of the metal shell 11, and the tip 23 of the sensor element 21 protrudes from the tip of the ceramic holder 30. In addition, in the center of the seal material (talc molding) 41 before compression and the sleeve 43, similarly to the ceramic holder 30, a rectangular shape (rectangular shape) whose transverse section corresponds to the transverse section of the sensor element 21 as viewed from the direction of the axis O. A hole is provided.

  Then, for example, as shown in FIG. 4, the tip end side subassembly 101 including the sensor element 21 is manufactured and assembled. 4 can be manufactured by welding the outer protector 61 to the metal shell 11 and further assembling the gasket 19 to the metal shell 11 after the manufacturing process shown in FIG. On the other hand, the gas sensor 1 is manufactured by separately manufacturing and assembling the above-described rear end side portion, which is the other portion, as a semi-assembled body (in-process product) 102 and assembling them. That is, both are arranged coaxially as shown in FIG. 4, and the portion near the rear end 29 of the element 21 protruding in the lower half assembly 101 is opposed to the terminal fitting holding member 91. The terminal fittings 75 are relatively inserted between the arranged terminal fittings 75, and the terminal fittings 75 are brought into pressure contact with the electrode terminals 24 provided near the rear end 29 of the element 21 by a spring property. 1 is manufactured by fitting the large-diameter cylindrical portion 82 at the front end of the protective cylinder 81 to the cylindrical portion 15 near the rear end of the metal shell 11, and laser welding the entire circumference of the cylindrical portion 15 in the same portion. The

Next, a modification of the gas sensor according to the embodiment of the first invention will be described with reference to FIGS. 5 and 6 is different from the gas sensor 1 according to the embodiment of the first invention only in the ceramic holder 30B and the inner protector 51B, and the same reference numerals are given to the same components as the gas sensor 1. A description thereof will be omitted.
As shown in FIG. 6, in the gas sensor 1B, a circular through hole 51j2 penetrating in the axis O direction is formed in the flange portion 51f2 of the inner protector 51B. On the other hand, the cylindrical holder 30B is formed with a columnar convex portion 30e2 that fits into the through hole 51j2 and protrudes from the tip-facing surface 30a2 of the ceramic holder 30B toward the tip side. The cylindrical portion 51t2 of the inner protector 51B is inserted into the rear end side of the metal shell 11, the flange portion 51f2 is locked to the rear end facing surface 18a of the metal shell 11, and the ceramic holder 30B is attached to the rear end of the metal shell 11. Is inserted into the side, and the front end facing surface 30a2 of the ceramic holder 30B is engaged with the rear end facing surface 51a2 of the flange portion 51f2, the through hole 51j2 of the flange portion 51f2 is fitted into the convex portion 30e2, and the ceramic holder 30B A flange 51f2 is sandwiched between the metal shell 11 and the metal shell 11.
Note that the through hole 51j2 corresponds to a “restricting portion” in the claims, and the convex portion 30e2 corresponds to a “fitting portion” in the claims.

As described above, also in the gas sensor 1B, the through hole 51j2 of the flange portion 51f2 and the convex portion 30e2 of the ceramic holder 30B are fitted, so that the gas flow hole (vent hole 56B) of the inner protector 51B and the ceramic holder 30B are connected. The positional relationship in the circumferential direction with the detection unit 22 of the fixed sensor element 21 can be defined as a specific relationship. For this reason, the flow of the gas to be detected flowing through the detection unit 22 through the gas flow hole is optimized, and the response of gas detection can be improved. Further, only by fitting the through hole 51j2 of the flange portion 51f2 and the convex portion 30e2 of the ceramic holder 30B, the positional relationship in the circumferential direction between the inner protector 51B and the detecting portion 22 of the sensor element 21 can be defined as a specific relationship. Therefore, it can be mechanically adjusted and assembled at low cost.
Furthermore, since it has fitted using the through-hole 51j2 of the flange part 51f2, and the convex part 30e2 of the ceramic holder 30B, the position in the circumferential direction of the gas flow hole of the inner side protector 51B and the detection part 22 of the sensor element 21 Can be easily defined as a specific relationship.

Next, a gas sensor according to an embodiment of the second invention of the present invention will be described with reference to FIGS.
The gas sensor 1c is an oxygen sensor that detects the oxygen concentration in the exhaust gas. In FIG. 7, the gas sensor 1 c includes a sensor element 21 c, an insulating holder 47 through which the sensor element 21 c is inserted, and a metal shell 11 c that surrounds the periphery of the ceramic holder 47 in the radial direction.
The insulating holder 47 and the sensor element 21c correspond to the “sensor element structure” in the claims. The insulating holder 47 corresponds to a “bulged portion” in the claims.

Specifically, as shown in FIG. 10, the sensor element 21c has a cylindrical solid electrolyte body 21g that is closed at the front end and has a cylindrical hole 21h on the rear end side, and is tapered toward the front end. This is a cylindrical oxygen sensor element composed of an inner electrode (not shown) and an outer electrode 21s formed on the inner and outer peripheral surfaces of the electrolyte body 21g. The internal space of the sensor element 21c is used as a reference gas atmosphere, and the gas to be detected is brought into contact with the outer surface of the sensor element 21c. In addition, a protrusion 27 protruding outward in the radial direction is provided near the center of the sensor element 21c.
In this example, the outer electrode 21s is formed on a part of the outer circumferential surface of the solid electrolyte body 21g in the circumferential direction on the tip side from the protrusion 27. A lead portion 21L extends from the outer electrode 21s to the rear end side across the protrusion 27, and the rear end side of the lead portion 21L is connected to a ring lead portion 21M having a width wider than the lead portion 21L. Further, a rod-shaped heater 88 is inserted in the internal space of the sensor element 21c (see FIG. 7).

Returning to FIG. 7, the metal shell 11 c has an insertion hole 18 c penetrating in the direction of the axis O and has a cylindrical shape with concentric and different diameters at the front and rear. On the inner surface 17c of the insertion hole 18c, a tapered rear end-facing surface 18ac that is tapered toward the front end is formed. On the other hand, the front end side of the metal shell 11c has a small-diameter cylindrical annular portion (hereinafter also referred to as a cylindrical portion) 12c for externally fitting and fixing an outer protector 61c to be described later. The upper outer peripheral surface is provided with a screw 13c for fixing to the engine exhaust pipe having a larger diameter. In addition, a polygonal portion 14 c for screwing the sensor 1 with the screw 13 is provided at the rear thereof. In addition, a cylindrical portion 15c that externally fits and welds a protective cylinder (outer cylinder) 81c that covers the rear of the gas sensor 1c is connected to the rear of the polygonal portion 14c. A small and thin caulking cylindrical portion 16c is provided. The caulking cylindrical portion 16c is bent inward in FIG. 7 after caulking. A gasket 19c for sealing at the time of screwing is attached to the lower surface of the polygonal portion 14.
The sensor element 21c is inserted into the insertion hole 18c of the metal shell 11c, and is held inside the metal shell 11c by engaging its protrusion 27 with an insulating holder 47 described later. The relationship among the protrusion 27, the insulating holder 47, and the metal shell 11c will be described later.

  Further, a sealing material (talc in this example) 41c is filled in a radial gap between the sensor element 21c and the metal shell 11c on the rear end side of the protrusion 27, and an insulating material is further provided on the rear end side of the sealing material 41c. A sleeve 43c is arranged. Then, a ring washer 45c is arranged on the rear end side of the sleeve 43c, and the caulking cylindrical portion 16c of the metal shell 11c is bent inward, whereby the sleeve 43c is pressed to the front end side to crush the sealing material 41c, and the sleeve 43c In addition, the sealing member 41c is fixed by crimping, the gap between the sensor element 21c and the metal shell 11c is sealed, and the sensor element 21c is fixed inside the metal shell 11c while maintaining airtightness in the front-rear direction.

  The outer electrode 21s on the front end side of the sensor element 21c protrudes from the insulating holder 47 and the metal shell 11c to the front end. Further, the rear end portion of the sensor element 21c protrudes rearward from the sleeve 43c and the metal shell 11c, and a lead member (not shown) extending from the inner electrode and the outer electrode formed in the rear end portion (not shown) is provided with a sealing material. Terminal fittings 75c1 and 75c2 provided at the tips of the respective lead wires 71c drawn to the outside through 85c are electrically connected.

Of the terminal fittings 75c1 and 75c2 arranged on the rear end side of the sensor element 21c, a cylindrical terminal fitting 75c1 located on the radially inner side is fitted into the cylindrical hole 21h, and an inner electrode (not shown) is provided. Electrically connected. A cylindrical terminal fitting 75c2 is fitted on the outside of the gas sensor element 21c, and is electrically connected to the electrode pad portion 21M (outer electrode 21s). Further, lead wires 71c connected to a pair of heater terminal fittings 75c3 (only one is shown in FIG. 7) that is electrically connected to the heater 88 are drawn out through the sealing material 85c. The terminal fittings 75c1 and 75c2 and the heater terminal fitting 75c3 are respectively provided in the respective housing portions provided in the terminal fitting holding member 91c made of an insulating material arranged in the protective cylinder 81c. Note that the movement of the terminal fitting holding member 91c in the radial direction and the distal end side is restricted via an annular support member 80c fixed in the protective cylinder 81c. The rear end of the gas sensor 1c is covered in an airtight manner by fitting the front end portion (large diameter cylindrical portion) 82c of the protective cylinder 81c to the cylindrical portion 15c near the rear end of the metal shell 11c and welding it. ing. The lead wire 71c passes through a sealing material (for example, rubber) 85c disposed inside the small-diameter cylindrical portion 83c at the rear end of the protective cylinder 81c and is drawn out to the outside. The small-diameter cylindrical portion 83c is reduced in diameter. By crimping and compressing the sealing material 85c, the airtightness of this part is maintained.
Incidentally, this sealing material 85c is arranged in such a manner that the rear end of the terminal metal fitting holding member 91c is pushed forward, so that the terminal metal holding member 91c and the terminal metal fittings 75c1 and 75c2 provided therein are stably mounted. Is planned. The terminal fitting holding member 91c has a flange 93c formed on the outer periphery thereof supported on an annular support member 80c fixed to the inside of the protective cylinder 81c, and receives the compressive force of the sealing material 85c. ing.
Further, a through hole 85h is formed at the center of the sealing material 85c and communicates with the internal space of the sensor element 21c. A water-repellent ventilation filter 140 is interposed in the through-hole 85h, and the reference gas (atmosphere) is introduced into the internal space of the sensor element 21c without allowing external water to pass therethrough.

On the other hand, a protector 60c having a two-layer structure of a bottomed cylindrical inner protector 51c and an outer protector 61c arranged apart from the outer periphery of the inner protector 51 is put on the tip portion of the sensor element 21c. .
The inner protector 51c is connected to a cylindrical portion 51tc that covers the circumferential direction on the distal end side of the gas sensor element 21c, and a rear end edge of the cylindrical portion 51tc, expands radially outward, and is substantially the same as the rear end facing surface 18ac of the metal shell 11c. A tapered flange portion 51fc having the same taper angle is integrally formed. Further, for example, six vent holes 56c are provided in the circumferential direction on the rear end side of the cylindrical portion 51tc of the inner protector 51c, and discharge holes 53c are provided on the bottom surface on the front end side.
The inner protector 51c corresponds to the “protector” in the claims. The vent hole 56c corresponds to a “gas flow hole” in the claims.
Similarly, the outer protector 61c has a cylinder part 61tc that covers the circumferential direction of the cylinder part 51tc of the inner protector 51c, and, for example, eight vent holes 67c are provided in the circumferential direction near the tip of the cylinder part 61tc. A discharge hole 69c is also provided at the center of the bottom of the outer protector 61c.
The rear end side of the cylindrical portion 51tc of the inner protector 51c is accommodated inside the cylindrical portion 12c of the metal shell 11c, and between the front end facing surface 47a of the insulating holder 47 and the rear end facing surface 18ac of the main metal shell 11c. Further, the flange portion 51fc of the inner protector 51c is sandwiched, and the inner protector 51c is fixed to the metal shell 11c.
On the other hand, the outer protector 61c is welded with the rear end portion of the outer metal protector 61c being fitted to the cylindrical portion 12c of the metal shell 11c while being fitted to the inner protector 51c with a gap.

Next, FIG. 8 and FIG. 9 show the main points of the second invention.
In the invention of FIG. 8, a protruding portion 18p protruding to the rear end is formed on the rear end facing surface 18ac of the metal shell 11c. An insulating holder 47 made of an insulating ceramic (for example, alumina) and having a substantially short cylindrical shape is disposed inside the insertion hole 18c of the metal shell 11c. As shown in FIG. 9, the outer peripheral side of the tip of the insulating holder 47 forms a tip-facing surface 47 a that is tapered toward the tip. As will be described later, the insulating holder 47 is connected to the rear end of the metal shell 11c with the flange portion 51fc of the inner protector 51c sandwiched between the front surface 47a and the rear surface 18ac of the metal shell 11c. It is positioned in the metal shell 11c while being engaged with the facing surface 18ac, and is fitted in a gap.
The sensor element 21 c is passed through the center hole 47 h of the insulating holder 47, and the protrusion 27 of the sensor element 21 c is locked to the rear end facing surface 47 b of the insulating holder 47. And the front-end | tip of the sensor element 21c is protruded ahead rather than the front-end | tip direction surface 47a of the insulation holder 47, and the front-end | tip 12ac of the metal shell 11c.

The flange portion 51fc of the inner protector 51c is formed with a U-shaped notch 51j3 that opens radially outward. On the other hand, a recess 47e is formed on the tip-facing surface 47a of the insulating holder 47. Then, the cylindrical portion 51tc of the inner protector 51c is inserted into the rear end side of the metal shell 11c, the flange portion 51fc is locked to the rear end facing surface 18ac of the metal shell 11c, and the insulating holder 47 is connected to the rear end of the metal shell 11c. When inserted to the side, the flange 51fc is sandwiched between the insulating holder 47 and the metal shell 11c while the notch 51j3 and the recess 47e are fitted into the protruding portion 18p of the metal shell 11.
Here, in this example, since the sensor element 21c is cylindrical, if the relative position in the radial direction between the insulating holder 47 and the sensor element 21c is not restricted, the sensor element 21c is circumferentially arranged in the insulating holder 47. Even if it is attached in an arbitrarily rotated state and the positional relationship between the inner protector 51c and the insulating holder 47 is defined, there is a high possibility that it will be wasted. Therefore, a convex portion 47p that protrudes toward the rear end side is formed on the rear end facing surface 47b of the insulating holder 47, and a concave portion 27e that engages with the convex portion 47p is formed on the front end facing surface 27a of the protruding portion 27 of the sensor element 21c. Is formed.

Then, the flange portion 51fc is sandwiched between the insulating holder 47 and the metal shell 11c with the concave portion 27e engaged with the convex portion 47p.
Thus, the notch 51j3 of the flange portion 51fc and the recess 47e of the insulating holder 47 are fitted to the protruding portion 18p of the metal shell 11c, so that the gas flow hole (vent hole 56) of the inner protector 51c, The positional relationship between the sensor element 21c fixed to the insulating holder 47 and the outer electrode 21s is defined as a specific relationship. For this reason, also in the second aspect of the invention, the flow of the gas to be detected flowing to the outer electrode 21s through the gas flow hole is optimized, and the response of gas detection is improved. Further, since the positional relationship between the inner protector 51c and the sensor element 21c in the circumferential direction can be made a specific relationship only by fitting the notch 51j3, the recess 47e, and the protruding portion 18p, it is mechanically inexpensive. Can be adjusted and assembled.

  Further, according to the gas sensor 1c, the insulating holder 47 is engaged with the metal shell 11c, and the convex portion 47p provided on the insulating holder 47 and the concave portion 27e provided on the protruding portion 27 are fitted to each other. 47, and also in the sensor structure having the sensor element 1c provided with the protrusion 27, the positional relationship in the circumferential direction between the gas flow hole of the protector 51c and the outer electrode 21s of the sensor element 21 is defined as a specific relationship. Can do.

  In the gas sensor 1c, the insulating holder 47 is used to insulate the outer electrode 21s from the metal shell 11c. However, a simple sensor (for example, a two-wheeled vehicle) that can electrically connect the outer electrode 21s to the metal shell 11c. In the case of an oxygen sensor), the protrusion 27 of the sensor element 21c may be directly engaged with the flange 51fc of the inner protector 51c without using the insulating holder 47. In this case, the protrusion 27 corresponds to the “bulged portion” in the claims. In this case, the sensor element 21c corresponds to a “sensor element structure” in the claims.

The gas sensor of the present invention can be embodied by appropriately changing the structure and configuration without departing from the gist of the present invention.
For example, in the embodiment of the first invention of the present invention, the convex portion 51j is formed in the flange portion 51f, the concave portion 30e is formed in the ceramic holder 30, and the convex portion 51j and the concave portion 30e are fitted. Without being limited thereto, a concave portion that is recessed from the rear end facing surface 51a toward the front end side is formed in the flange portion 51f, and a convex portion that protrudes from the front end facing surface 30a of the ceramic holder 30 toward the front end side is formed, You may fit this recessed part and a convex part. Moreover, while forming a convex part and a recessed part in the flange part 51f, a recessed part and a convex part may be formed in the ceramic holder 30, and this several recessed part and convex part may be fitted, respectively.
Further, in the modification of the embodiment of the first invention of the present invention, the through hole 51j2 is formed in the flange portion 51f2, the convex portion 30e2 is formed in the ceramic holder 30B, and the through hole 51j2 and the convex portion 30e2 are fitted. However, the present invention is not limited to this, and a notch (for example, the form of the notch 51j3 according to the embodiment of the second invention) is formed in the flange portion 51f2 by cutting out a part of the flange portion 51f2. You may fit a notch and the convex part 30e2 of the ceramic holder 30B.
In the embodiment and the modification of the first invention of the present invention, each of the flange portion and the ceramic holder is provided with one restricting portion and one fitting portion. However, the present invention is not limited to this, and a plurality of restricting portions are provided. And a fitting part may be provided.
In the second embodiment of the present invention, the protrusion 47p is formed in the insulating holder 47, the recess 27e of the protrusion 27 is formed, and the protrusion 47p and the recess 27e are fitted. However, the present invention is not limited thereto, and a concave portion that is recessed toward the front end side is formed on the rear end facing surface 47b of the insulating holder 47, and a convex portion that protrudes from the front end facing surface 27a of the protruding portion 27 toward the front end side is formed. The concave portion and the convex portion may be fitted.
In the second embodiment of the present invention, the notch 51j3 is formed in the flange portion 51fc of the inner protector 51c. However, the present invention is not limited to this, and a through-hole penetrating in the axial direction may be provided in the flange portion 51fc. good.
In the embodiment of the second invention of the present invention, the convex portion provided on the metal shell, the notch provided on the flange portion, and the concave portion provided on the ceramic holder are each one, but this is not limitative. Instead, a plurality of convex portions, notches, and concave portions may be provided.

In the embodiment and the modification of the first invention of the present invention, the plate-type sensor element 21 and the ceramic holder 30 are used as the sensor structure. However, the present invention is not limited to this, and the second embodiment of the present invention. The cylindrical sensor element 21c and the insulating holder 47 described in the embodiment of the invention may be used, or only the cylindrical sensor element 21c may be used.
Furthermore, in the second embodiment of the present invention, the cylindrical sensor element 21c and the insulating holder 47 are used as the sensor structure. However, the present invention is not limited to this, and the first embodiment of the present invention is implemented. You may use the plate-shaped sensor element 21 and the ceramic holder 30 which were demonstrated by the form.
In the embodiment and the modification of the first invention of the present invention, the plate-like sensor element is a belt plate having a rectangular cross section, but the plate used in the gas sensor of the present invention. The sensor element may have a square cross section or may be other than that. Furthermore, in the above description, the full range air-fuel ratio gas sensor and the oxygen sensor are embodied, but the gas sensor according to the present invention can also be embodied in other gas sensors.

1, 1B, 1c Gas sensor 11, 11c Metal fitting 18, 18c Metal fitting insertion hole 18a, 18ac Rear end face 18p of metal fitting Metal metal protrusions 21, 30, 21c, 47 Sensor element structure 22 Detector 27 Projection 27a Projection-facing tip-facing surface 30, 47 Swelling portion 30a, 47a Swell-protruding tip-facing surface 30e, 30e2 Fitting portion (concave, convex)
51, 51B, 51c Protector (inner protector)
51f, 51f2, 51fc Flange part 51t, 51t2, 51tc Tube part 51j, 51j2, 51j3 Restriction part (convex part, through hole, notch)
27e, 47e Concave portion 47p Convex portions 56, 56B, 56c Gas flow hole O Axis line

Claims (6)

A metal shell having an insertion hole penetrating in the axial direction and having an annular rear end facing surface facing the rear end side in a part of the inner surface constituting the insertion hole,
A sensor element structure comprising one or a plurality of members, having a detection unit for detecting a specific gas on its front end side, and having a bulging portion provided on the rear end side of the detection unit and projecting radially outward. A front-facing surface of the bulging portion is engaged with the rear-facing surface of the metal shell, and is inserted through the insertion hole so that the detection portion is located on the front side of the metal shell. A sensor element structure to be projected;
A flange portion sandwiched between the rear end-facing surface of the metal shell and the front-facing surface of the bulging portion is disposed on the front end side from the flange portion, covers the detection portion, and is provided with a gas flow hole. A gas sensor comprising a protector having a cylindrical portion,
The gas sensor according to claim 1, wherein a restriction portion that fits into a fitting portion provided in the bulging portion is formed in the flange portion. The restricting portion is at least one of a convex portion protruding from the rear end facing surface of the flange portion toward the rear end side, or a concave portion recessed from the rear end facing surface of the flange portion toward the front end side. ,
The fitting portion is fitted with the convex portion of the restricting portion, and is fitted with a concave portion that is recessed from the front-facing surface of the bulging portion toward the rear end side, or the concave portion of the restricting portion. 2. The gas sensor according to claim 1, wherein the gas sensor is at least one of convex portions protruding from the surface facing the distal end of the bulging portion toward the distal end side. The fitting portion is a convex portion that protrudes from the tip-facing surface of the bulging portion toward the tip side,
The restricting portion is fitted to the convex portion of the fitting portion, and is fitted to a through-hole penetrating the flange portion in the axial direction, or the convex portion of the fitting portion, and the flange portion The gas sensor according to claim 1, wherein a part of the gas sensor is cut out in a radial direction. A metal shell having an insertion hole penetrating in the axial direction and having an annular rear end facing surface facing the rear end side in a part of the inner surface constituting the insertion hole,
A sensor element structure comprising one or a plurality of members, which has a detection unit for detecting a specific gas on its front end side, and has a bulging portion that is on the rear end side of the detection unit and protrudes radially outward. The front-end facing surface of the bulging portion is engaged with the rear-end-facing surface of the metal shell, and is inserted into the insertion hole so that the detection portion protrudes further to the front side than the front end of the metal shell. A sensor element structure
A flange portion sandwiched between the rear end-facing surface of the metal shell and the front-facing surface of the bulging portion, disposed on the front end side from the flange portion, and provided with a gas flow hole while covering the detection portion A gas sensor comprising a protector having a cylindrical portion,
The metal shell is formed with a protruding portion that protrudes from the rear-facing surface of the metal shell toward the rear edge side.
The flange portion is fitted with the projecting portion, and is fitted with a through-hole penetrating the flange portion in the axial direction or with the projecting portion, and a part of the flange portion is cut in a radial direction. A notch is formed,
The gas sensor according to claim 1, wherein the bulging portion is formed with a concave portion that fits with the protruding portion and that is recessed from the front-facing surface of the bulging portion toward the rear end side. The sensor element structure has a plate-like sensor element including the detection unit on its tip side, and an annular holder having a substantially rectangular element insertion hole for inserting the sensor element,
The gas sensor according to claim 1, wherein the holder constitutes the bulging portion. The sensor element structure includes the sensor on the tip side of the sensor element, the sensor element having a protrusion protruding radially outward, and the rear end of the sensor element facing the tip of the protrusion of the sensor element. An annular insulating holder with which the surface engages,
The insulating holder constitutes the bulging portion;
The protrusion is formed with at least one of a protrusion protruding from the tip-facing surface toward the tip side of the protrusion or a recess recessed from the tip-facing surface of the protrusion toward the rear end. And
The insulating holder is fitted with the convex portion of the protruding portion, and is recessed with the concave portion recessed from the rear end facing surface of the insulating holder toward the front end side, or the concave portion of the protruding portion, The gas sensor according to any one of claims 1 to 4, wherein at least one of convex portions protruding from the rear end facing surface of the insulating holder toward the rear end side is formed.

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