JP2011117743A - Gas sensor and method for manufacturing the gas sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique that suppresses water from adhering to the tip of a gas sensor element, in a gas sensor. <P>SOLUTION: The gas sensor 1 includes the gas sensor element extending in the axial direction, the gas sensor element extending in the axial direction, a main fitting 10, and a protector 45 for surrounding the periphery of the tip of a gas sensor element. The protector has an outer cover section 50, and an inner cover section 60. The inner cover section has an inner cylindrical section 602 that surrounds the tip 42 of the gas sensor element 40, and an annular protruding section 610 tat is radially and outwardly protruded from the back end of the inner cylindrical section, and reaching the outer cover section on an outer edge. The protruding section 610 has an inner-gas inlet hole 612 for introducing a gas, from the outside to the inside of the inner cover section 60. When the inner-gas inlet hole is seen from the outside toward the inside, the inner gas inlet hole is formed at a position, separating from the outer circumference 602a of the inner cylindrical section by 0.2 mm or more in the protruding section. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a gas sensor, and more particularly to a gas sensor including a protector that covers a portion of a gas sensor element that is exposed to a gas to be measured.

  Conventionally, gas sensors such as oxygen sensors, NOx sensors, and HC sensors are known. Such a gas sensor is generally provided with a protector so as to cover the tip of the gas sensor element so as to protect the tip of the gas sensor element exposed to the gas to be measured such as exhaust gas from being exposed to water. In addition, when covering the tip of the gas sensor element with a protector, in the case of a single structure protector, water is exposed to the inside of the protector from the gas introduction hole provided in the protector in order to expose the gas to be measured to the tip of the gas sensor element. ), Water adheres to the gas sensor element, and the gas sensor element may crack. For this reason, there is a gas sensor in which the protector has a double structure of an inner protector and an outer protector, and the inner gas introduction hole of the inner protector and the outer gas introduction hole of the outer protector are arranged so as not to overlap (for example, Patent Document 1, Patent Document) 2). As a result, water that has entered from the gas inlet hole of the outer protector adheres to the inner protector and the outer protector, making it difficult for water to enter the inner protector from the inner gas inlet hole, and is arranged inside the inner protector. Water hardly adheres to the gas sensor element.

JP 2005-37382 A JP 2005-43349 A

  However, even when the protector has a double structure, water may pass through the inner gas introduction hole and adhere to the tip of the gas sensor element. Specifically, there is a possibility that water adhering to the inner protector or the outer protector is transmitted to the inner gas introduction hole and enters the inner protector from the inner gas introduction hole.

  Therefore, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a technique capable of suppressing water from adhering to the tip portion of a gas sensor element in a gas sensor.

[Application Example 1] A gas sensor element extending in the axial direction, a cylindrical metal shell surrounding the periphery of the gas sensor element in a state in which a tip portion of the gas sensor element protrudes from its own tip, and fixed to the metal shell, A protector surrounding the periphery of the tip of the gas sensor element, wherein the protector is joined to the metal shell and has a cylindrical outer cover portion having an outer gas introduction hole on a side surface; and the outer cover. The outer cover portion and an inner cover portion disposed between the gas sensor element in a radial direction orthogonal to the axial direction, and the inner cover portion includes the outer gas introduction hole. A cylindrical inner cylindrical portion having a portion opposed to the inner cylindrical portion surrounding the front end portion of the gas sensor element, and a front side from the rear end side of the inner cylindrical portion. An annular protrusion that protrudes radially outward and has an outer edge reaching the outer cover part, the protrusion being an inner part for introducing gas from the outside to the inside of the inner cover part A gas introduction hole, and the inner gas introduction hole is formed at a position away from the outer peripheral surface of the inner cylindrical portion by 0.2 mm or more in the projecting portion when viewed along the radial direction. A gas sensor characterized by that.

  According to the gas sensor of Application Example 1, when viewed along the radial direction, the distance between the inner gas introduction hole and the outer peripheral surface of the inner cylindrical portion is set to 0.2 mm or more, so that the gas sensor is attached to the inner cylindrical portion. Even if water reaches the protruding portion through the inner cylindrical portion, the protruding portion can block the water. Accordingly, it is possible to suppress water from entering the inside of the inner cover portion through the inner gas introduction hole and adhering to the tip portion of the gas sensor element. As a result, it is possible to prevent a crack from occurring at the tip of the gas sensor element.

Application Example 2 A gas sensor element extending in the axial direction, a cylindrical metal shell that surrounds the periphery of the gas sensor element in a state in which a tip portion of the gas sensor element protrudes from the tip of the gas sensor element, and is fixed to the metal shell, A protector surrounding the periphery of the tip of the gas sensor element, wherein the protector is joined to the metal shell and has a cylindrical outer cover portion having an outer gas introduction hole on a side surface; and the outer cover. The outer cover portion and an inner cover portion disposed between the gas sensor element in a radial direction orthogonal to the axial direction, and the inner cover portion includes the outer gas introduction hole. A cylindrical inner cylindrical portion having a portion opposed to the inner cylindrical portion that surrounds the periphery of the distal end portion of the gas sensor element, and a rear end side of the inner cylindrical portion. An annular projecting portion projecting outward in the radial direction and having an outer edge reaching the outer cover portion, the projecting portion for introducing gas from the outside to the inside of the inner cover portion An inner gas introduction hole, and the inner gas introduction hole is formed at a position apart from the inner peripheral surface of the outer cover portion by 0.5 mm or more in the projecting portion when viewed along the radial direction. A gas sensor characterized by that.

  According to the gas sensor of Application Example 2, when the distance between the inner gas introduction hole and the inner peripheral surface of the outer cover portion is 0.5 mm or more when viewed along the radial direction, the water adhering to the outer cover portion is increased. Even if it reaches the protruding portion through the outer cover portion, water can be blocked by the protruding portion. Accordingly, it is possible to suppress water from entering the inside of the inner cover portion through the inner gas introduction hole and adhering to the tip portion of the gas sensor element. As a result, it is possible to prevent a crack from occurring at the tip of the gas sensor element.

Application Example 3 In the gas sensor according to Application Example 1 or Application Example 2, when viewed along a radial direction orthogonal to the axial direction, the outer circumferential surface of the inner cylindrical portion and the inner gas introduction hole A gas sensor characterized in that a distance between an inner peripheral surface of the outer cover portion and the inner gas introduction hole is larger than a distance.
According to the inventor's investigation, it has been found that the water that has passed through the outer gas introduction hole adheres more to the inner peripheral surface of the outer cover portion than to the outer peripheral surface of the inner cylindrical portion. Therefore, according to the gas sensor of Application Example 3, the distance between the inner peripheral surface of the outer cover portion and the inner gas introduction hole is larger than the distance between the outer peripheral surface of the inner cylindrical portion and the inner gas introduction hole. It is possible to further suppress the water from entering the inside of the inner cover portion through the gas introduction hole and adhering to the tip portion of the gas sensor element. Thereby, the situation where a crack generate | occur | produces in the front-end | tip part of a gas sensor element can be prevented more.

Application Example 4 In the gas sensor according to any one of Application Examples 1 to 3, the inner gas introduction hole is in a positional relationship overlapping with the metal shell when projected in the axial direction. A gas sensor characterized by that.
According to the gas sensor of Application Example 4, since water can be captured by the bottom surface of the metal shell even when water passes through the inner gas introduction hole together with the gas to be measured, water is collected at the tip of the gas sensor element. Adhesion can be further suppressed. Thereby, the situation where a crack generate | occur | produces in the front-end | tip part of a gas sensor element can be prevented more.

[Application Example 5] The gas sensor according to any one of Application Examples 1 to 4, wherein the projecting portion is directed from the periphery of the inner gas introduction hole toward the tip of the gas sensor element along the axial direction. A gas sensor comprising a folded portion extending in a direction.
According to the gas sensor of Application Example 5, even when water travels toward the inner gas introduction hole along the outer peripheral surface of the inner cylindrical portion and the inner peripheral surface of the outer cover portion, Intrusion into the inner gas introduction hole can be suppressed. Thereby, the situation which a crack generate | occur | produces in the front-end | tip part of a gas sensor element can be prevented further.

[Application Example 6] The gas sensor according to any one of Application Examples 1 to 5, wherein at least a part of the protruding portion has the inner gas introduction hole at the most distal side of the protruding portions. A gas sensor characterized by being inclined with respect to a radial direction so as to be positioned.
According to the gas sensor of Application Example 6, even when water travels toward the inner gas introduction hole along the outer peripheral surface of the inner cylindrical portion and the inner peripheral surface of the outer cover portion, Intrusion into the gas introduction hole can be further suppressed. Thereby, the situation where a crack generate | occur | produces in the front-end | tip part of a gas sensor element can be prevented more.

  The present invention can be realized in various forms. In addition to the configuration as the gas sensor described above, the manufacturing method of any of the gas sensors described above, the vehicle including the gas sensor of any of the configurations described above, and the like. It is realizable with the aspect of.

It is sectional drawing of the gas sensor of 1st Example which concerns on this invention. It is a partial top view of the gas sensor of 1st Example. It is the perspective view which fractured | ruptured a part of protector. It is a fragmentary sectional view of the principal part of the protector of 1st Example. It is a figure for demonstrating the evaluation experiment which investigated the influence which the distance A and the distance B have on the moisture amount of the front-end | tip part. It is a fragmentary sectional view of the gas sensor of the 2nd example. It is the 2nd experimental result which investigated the influence which the direction of a folding | turning part has on the amount of moisture of the front-end | tip part of a gas sensor element. It is the 1st explanatory view for explaining other examples. It is the 2nd explanatory view for explaining other examples.

Next, embodiments of the present invention will be described in the following order.
A. First embodiment:
B. Other examples:
C. Modified example

A. First embodiment:
A-1. Overall configuration of gas sensor:
FIG. 1 is a cross-sectional view of a gas sensor according to a first embodiment of the present invention. FIG. 2 is a partial plan view of the gas sensor of the first embodiment. 1 and 2 show the axis AX of the gas sensor 1. Hereinafter, a direction along the axis AX is referred to as an axis direction BD. A direction perpendicular to the axial direction BD is referred to as a radial direction RD. Further, in the axial direction BD, the upper side of the gas sensor 1 is referred to as a rear end side, and the lower side is referred to as a front end side.

  The gas sensor 1 mainly includes a gas sensor element 40 extending in the axial direction BD, a metal shell 10 surrounding the gas sensor element 40, and a protector 45 that covers a distal end portion 42 of the gas sensor element 40 that is exposed to exhaust gas that is a gas to be measured. Prepare for.

  The shape of the gas sensor element 40 is a bottomed cylinder with the tip 40s closed. The gas sensor element 40 is formed on a solid electrolyte body having oxygen ion conductivity, an outer electrode (not shown) formed on a part of the outer peripheral surface of the solid electrolyte body, and a part of the inner peripheral surface of the solid electrolyte body. An inner electrode (not shown) is provided, and the tip 42 can measure the oxygen concentration in the gas to be measured. A rod-shaped heater 30 for heating the tip portion 42 is disposed inside the tip portion 42.

  Further, in the axial direction BD, a flange portion 40f that protrudes outward in the radial direction RD is provided in an intermediate portion of the gas sensor element 40. The flange portion 40 f is used to engage the metal shell 10 and hold the gas sensor element 40 on the metal shell 10.

  The metal shell 10 surrounds a part of the outer periphery of the gas sensor element 40. An insulator 135 is disposed in the through hole 12 of the metal shell 10 via a metal packing (not shown). A flange portion 40f is engaged with the insulator 135 via a metal packing. Further, a talc 139, a sleeve 141, and a metal packing 83 are arranged on the rear end side of the insulator 135, and the gas sensor element 40 is airtight inside the main metal shell 10 by caulking the rear end side of the main metal shell 10. Is holding in.

  A protector 45 is attached to the distal end side of the metal shell 10. The protector 45 covers the distal end portion 42 of the gas sensor element 40 protruding from the distal end side opening of the metal shell 10. The protector 45 includes an outer cover part 50 and an inner cover part 60 disposed inside the outer cover part 50. The rear end side of the inner cover part 60 and the rear end side of the outer cover part 50 are laser welded and fixed to the front end part of the metal shell 10 over the entire circumference.

  The outer cover part 50 and the inner cover part 60 have gas introduction holes 512 and 612, respectively, and the gas to be measured is introduced into the inner cover part 60 from the outside through the gas introduction holes 512 and 612. Further, the bottom surfaces of the outer cover portion 50 and the inner cover portion 60 have vent holes 503 and 603, respectively. The detailed structure of the outer cover part 50 and the inner cover part 60 will be described later.

  As shown in FIGS. 1 and 2, the metal shell 10 includes a screw portion 10 c on the distal end side of the hexagonal portion 10 a formed on the outer peripheral surface. Moreover, as shown in FIG. 1, the front-end | tip part 20a of the metal outer cylinder 20 is engage | inserted by the rear-end side of the metal shell 10, and it adheres by outer periphery laser welding from the outer side. A grommet 203 made of rubber or the like is inserted into the rear end side opening 20k of the metal outer cylinder 20 and sealed by caulking. At the center of the grommet 203, a filter member 205 that introduces air into the metal outer cylinder 20 and prevents moisture from entering is disposed. Further, a separator 207 made of insulating alumina ceramic is provided on the front end side of the grommet 203. Then, sensor output lead wires 211 and 212 and heater lead wires 213 and 214 are disposed through the grommet 203 and the separator 207. In the separator 207, the connector portion 215b, the insertion portion 215c, and the heater terminal fittings 217 and 218 of the first and second sensor terminal fittings 215 and 216 are held while being insulated from each other.

  The first sensor terminal fitting 215 has a connector part 215b and an insertion part 215c. The first sensor terminal fitting 215 is electrically connected to the sensor output lead wire 211 when the connector portion 215b grips the sensor output lead wire 211, and the insertion portion 215c is inserted into the bottomed hole of the gas sensor element. By this, it electrically connects with the inner electrode (not shown) of the gas sensor element 40.

  The 2nd sensor terminal metal fitting 216 has the connector part 216b and the holding part 216c. The second sensor terminal fitting 216 is electrically connected to the sensor output lead 212 by the connector 216b gripping the sensor output lead 212, and the grip 216c is an outer periphery near the rear end side of the gas sensor element 40. Is electrically connected to an outer electrode (not shown).

  The heater terminal fittings 217 and 218 are electrically connected to the heater lead wires 213 and 214, respectively, and are also electrically connected to the electrode pads 109b and 109c of the heater 30, respectively.

A-2. Detailed configuration of the protector:
Next, the detailed structure of the protector 45 is demonstrated using FIG.3 and FIG.4. FIG. 3 is a perspective view in which a part of the protector is broken. FIG. 4 is a partial cross-sectional view of the main part of the protector of the first embodiment. In FIG. 4, only a part of the metal shell 10 and the protector 45 is illustrated.

  As shown in FIG. 3, the outer cover portion 50 includes a substantially cylindrical outer cylindrical portion 502 and an outer bottom surface portion 501 located on the distal end side. A metal material (for example, stainless steel) having a thickness of 0.5 mm is used for the outer cover portion 50. The outer cylindrical portion 502 is formed with eight outer gas introduction holes 512 (only two are shown in the figure) through which the measurement gas can be introduced from the outer side to the inner side of the outer cover portion 50. Further, the distal end side of the outer cylindrical portion 502 has a tapered shape with a gradually decreasing diameter. The outer gas introduction holes 512 each have an oval shape and are formed at equal intervals in the circumferential direction of the outer cylindrical portion 502. A circular outer tip vent hole 503 is formed in the central portion of the outer bottom surface portion 501.

  The inner cover part 60 includes a substantially cylindrical inner cylindrical part 602, an annular projecting part 610 extending from the rear end side of the inner cylindrical part 602 toward the outer side in the radial direction RD, and a substantially cylindrical part positioned on the rear end side. And a circular inner bottom surface portion 601 located on the tip side. A metal material (for example, stainless steel) having a thickness of 0.3 mm is used for the inner cover portion 60.

  Unlike the outer cylindrical portion 502, the inner cylindrical portion 602 does not have a gas introduction hole, and a part of the inner cylindrical portion 602 is located at a position facing the outer gas introduction hole 512. Thereby, the water introduced into the inner side of the outer cover part 50 together with the gas to be measured can be attached to the outer peripheral surface 602a (FIG. 4) of the inner cylindrical part 602, and the water enters the inner side of the inner cover part 60. Can be suppressed. Note that the distal end side of the inner cylindrical portion 602 has a tapered shape with a gradually decreasing diameter.

  As shown in FIG. 4, the protruding portion 610 is directed from the rear end side (the metallic shell 10 side) of the inner cylindrical portion 602 to the outside in the radial direction RD (the direction toward the inner peripheral surface 502b of the outer cylindrical portion 502). It protrudes and the outer edge is in contact with the inner peripheral surface 502b of the outer cylindrical portion 502. As shown in FIG. 3, twelve inner gas introduction holes 612 through which the gas to be measured can be introduced from the outer side to the inner side of the inner cover portion 60 are formed in the protruding portion 610 (only seven are shown in the figure). The inner gas introduction holes 612 each have a circular shape, and are formed at equal intervals in the circumferential direction of the protrusion 610. The inner gas introduction hole 612 has a diameter φC (FIG. 4) of 1.2 mm.

  As shown in FIG. 4, the inner gas introduction hole 612 is formed at a position separated from the outer peripheral surface 602 a of the inner cylindrical portion 602 by a distance B (mm) when viewed along the radial direction RD. Here, in this embodiment, B ≧ 0.2 mm is satisfied. By carrying out like this, it can suppress that water penetrate | invades into the inner side of the inner side cover part 60. FIG. Further, the inner gas introduction hole 612 is formed at a position away from the inner peripheral surface 502b of the outer cylindrical portion 502 by a distance A (mm) when viewed along the radial direction RD. Here, in this embodiment, A ≧ 0.5 mm is satisfied. By carrying out like this, it can suppress that water penetrate | invades into the inner side of the inner side cover part 60. FIG. It is further preferable to form the inner gas introduction hole 612 at a position satisfying A> B. By carrying out like this, it can suppress more that water penetrate | invades into the inner side of the inner side cover part 60. FIG. The basis for the numerical ranges of distance A and distance B, and the basis for the preferred magnitude relationship between distance A and distance B will be described later. The distance B (mm) means the shortest distance between the outer peripheral surface 602a of the inner cylindrical portion 602 and the outer edge of the inner gas introduction hole 612 when viewed along the radial direction RD. The distance A (mm) means the shortest distance between the inner peripheral surface 502b of the outer cylindrical portion 502 and the outer edge of the inner gas introduction hole 612 when viewed along the radial direction RD.

  As shown in FIG. 4, a folded portion 614 that extends a predetermined length in the direction toward the tip 20 s (FIG. 1) of the gas sensor element 40 in the axial direction BD (downward in the drawing) is provided at the peripheral portion of the inner gas introduction hole 612. It has been. Here, the length H of the folded portion 614 is preferably 0.2 mm or more. By setting it as 0.2 mm or more, it can suppress further that water penetrate | invades into the inner side from the outer side of the inner side cover part 60. FIG.

  Further, when viewed along the axial direction BD, the bottom surface 10b of the metal shell 10 is located immediately above the inner gas introduction hole 612 (upper side in the drawing). That is, when the inner gas introduction hole 612 and the metal shell 10 are projected on the front end side of the gas sensor 1 along the axial direction BD, all of the inner gas introduction holes 612 overlap with the metal shell 10. In other words, when viewed along the radial direction RD, the inner gas introduction hole 612 is located on the outer side in the radial direction RD than the inner peripheral surface 10d of the tip of the metal shell 10. When viewed along the axial direction BD, the distance D between the protrusion 610 and the bottom surface 10b of the metal shell 10 is preferably 0.3 mm or more and 2.0 mm or less. Thereby, water can be captured by the bottom surface of the metal shell 10. If the distance D is smaller than 0.3 mm, there is a risk of clogging between the protruding portion 610 and the bottom surface 10b due to particulate matter such as soot in the gas to be measured, and if the distance D is larger than 2.0 mm, the bottom surface 10b. This is because there is a possibility that water cannot be captured. In the gas sensor 1 of the present embodiment, the distance D is about 0.8 mm.

  As shown in FIG. 3, a circular inner tip vent hole 603 is formed in the central portion of the inner bottom surface portion 601. The outer bottom surface portion 501 and the inner bottom surface portion 601 are overlapped and fixed to each other by spot welding partially.

  The inner peripheral surface of the wall surface portion 620 of the inner cover portion 60 is overlapped with the outer peripheral surface of the distal end portion of the metal shell 10, and the outer peripheral surface is overlapped with the inner peripheral surface of the outer cylindrical portion 502. Then, the outer cover portion 50 and the inner cover portion 60 are fixed to the metal shell 10 by laser welding from the outer peripheral side of the outer cylindrical portion 502 (FIG. 1).

A-3. Manufacturing method of the protector:
The outer cover part 50 is molded by pressing a flat metal material. Thereafter, an outer gas introduction hole 512 and an outer tip vent hole 503 are formed in the outer cylindrical portion 502 which is a side surface portion of the outer cover portion 50. The inner cover portion 60 is molded by pressing a flat metal material. Thereafter, an inner gas introduction hole 612 and an inner tip vent hole 603 are formed. The inner gas introduction hole 612 is formed by punching. In this embodiment, punching is performed in the direction from the rear end side to the front end side of the gas sensor 1. Thereby, the folding | returning part 614 (FIG. 4) can be formed easily, without performing another process.

After the outer cover portion 50 and the inner cover portion 60 are manufactured by the method described above, the inner cover portion 60 is inserted inside the outer cover portion 50, and the outer bottom surface portion 501 and the inner bottom surface portion 601 are overlapped and fixed to each other by spot welding. To do. After fixing, the inner peripheral surface of the wall surface portion 620 of the inner cover portion 60 and the outer peripheral surface of the front end portion of the metal shell 10 are overlapped, and the outer peripheral surface of the wall surface portion 620 and the inner peripheral surface of the outer cylindrical portion 502 are overlapped. Match. Then, the outer cover portion 50 and the inner cover portion 60 are fixed to the metal shell 10 by laser welding from the outer peripheral side of the outer cover portion 50 (FIG. 1). Thereby, the gas sensor 1 provided with the protector 45 can be manufactured.
In addition, the manufacturing method of the gas sensor 1 shown above is an example, Comprising: It is not limited to this. For example, after the outer cover portion 50 and the inner cover portion 60 are fixed to the metal shell 10 by laser welding, the outer bottom surface portion 501 and the inner bottom surface portion 601 may be fixed to each other by spot welding. Further, for example, the inner gas introduction hole 612 may be formed by forming a through hole in the projecting portion 610 by laser cutting instead of punching, and attaching a folded portion 614 separately manufactured to the periphery of the through hole.

A-4. Experimental result:
FIG. 5 is a diagram for explaining an evaluation experiment in which the influence of distance A and distance B on the amount of water at the tip is examined. FIG. 5A is a diagram showing a first experimental result of the evaluation experiment, and FIG. 5B is a diagram for explaining a test method of the evaluation experiment. FIG. 5C is a diagram showing the state of the tip of the ceramic laminate after the evaluation experiment, and FIG. 5C-1 is a partially enlarged photograph of the tip of the ceramic laminate. 5 (c-2) is obtained by image processing of a partially enlarged photograph of the tip of the ceramic laminate.

  In the evaluation experiment, gas sensors 1 having different distances A and B were prepared and evaluated by conducting a water test. However, instead of the bottomed cylindrical gas sensor element 40 of the gas sensor 1, a plate-shaped (flat plate) ceramic laminate (corresponding to the gas sensor element 40 of this example) was assembled and tested. This is to facilitate the calculation of the amount of water to be described later. As shown in FIG. 5B, in the water test, the gas sensor 1 is attached to a pipe 80 having an inner diameter of 50 mm, and a predetermined amount of water Wa is sprayed from the spray nozzle 82 provided in the pipe 80 toward the ceramic laminate. I went there. Moreover, carbon is coated in advance on the surface of the ceramic laminate for the evaluation of the wet test. The portion of the ceramic laminate that is coated with carbon is a portion closer to the tip than the portion held by the insulator 135 (FIG. 1), and the portion exposed in the pipe 80 (hereinafter, the exposed portion is referred to as “ It is also referred to as a “tip”. Specifically, the tip has a width of 4 mm and a length of 15 mm. In the wet test, the distance L from the nozzle 84 to the axis AX of the gas sensor 1 is 150 mm, the gas flowing in the pipe 80 is air, the air flow rate is 30 m / s, and the air flow direction is changed from the spray nozzle 82 to the gas sensor 1. I went as a heading direction. In addition, one water test was performed by repeating a spraying process of spraying 30 ml of water Wa at a spraying pressure of 0.2 Mpa for 5 seconds three times at predetermined intervals.

After the water exposure test, the gas sensor 1 was removed from the pipe 80, and the location where the water Wa hit the tip of the ceramic laminate by three spraying steps was determined by processing the image of the tip. Specifically, as shown in FIG. 5 (c-2), a point AW where the water Wa hits in the tip is white as shown in FIG. 5 (c-2) with respect to the photograph of the tip before image processing shown in FIG. 5 (c-1). Then, image processing was performed in which a portion that was not exposed to water Wa was subjected to black processing, and a portion AW that was exposed to water Wa was determined. Next, the ratio of the location AW where the water Wa hit the surface of the tip was determined by the formula (1), and the calculated value was defined as the wet water amount Wb (%).
[Equation 1]
Wb = (Aw / B) × 100 (1)
Here, Wb is the amount of moisture (%), Aw is the area (mm ² ) of the tip (white) where the water Wa hits, and B is the surface area (mm ² ) of the tip.

  The judgment of the evaluation experiment is “◯” for the gas sensor 1 that showed a good result with a water content Wb of 2.0% or less, and the gas sensor 1 that showed a very good result with a water content Wb of 1.0% or less. Was marked with “」 ”, and the gas sensor 1 that showed an unfavorable result with a water coverage Wb of more than 2.0% was marked“ x ”. Here, the threshold value of the water amount Wb is set to 2.0% because when the gas sensor 1 is used in the exhaust gas pipe, the gas sensor 1 having the water amount Wb of 2.0% or less is hardly cracked. Because of that.

  As shown in FIG. 5A, when paying attention to the distance A, if the distance A is 0.5 mm or more, the water coverage Wb is 0.2% or less. As described above, by forming the inner gas introduction hole 612 at a position satisfying the distance A ≧ 0.5 mm in the protruding portion 610, it is possible to suppress water from adhering to the tip portion 42 and to generate a crack in the tip portion 42. Can be prevented. This is because when water flows into the outer gas introduction hole 512 together with the air flowing in the pipe 80 and adheres to the inner peripheral surface 502b of the outer cylindrical portion 502, the inner peripheral surface 502b of the outer cylindrical portion 502 is used. Even if it reaches the projecting portion 610 along the path, it is considered that the projecting portion 610 can block water. Accordingly, water that passes through the inner gas introduction hole 612 and tries to enter the inner side of the inner cover portion 60 can be reduced.

  Further, as shown in FIG. 5A, when paying attention to the distance B, if the distance B is 0.2 mm or more, the water amount Wb is 2.0% or less. As described above, by forming the inner gas introduction hole 612 at a position satisfying the distance B ≧ 0.2 mm in the projecting portion 610, it is possible to suppress water from adhering to the tip portion 42, and a crack is generated in the tip portion 42. Can be prevented. This is because when air is introduced into the outer gas introduction hole 512 together with the air flowing in the pipe 80 and adheres to the outer peripheral surface 602a of the inner cylindrical portion 602, it travels along the outer peripheral surface 602a of the inner cylindrical portion 602. Even if it reaches the protruding portion 610, it is considered that water can be blocked by the protruding portion 610. Accordingly, water that passes through the inner gas introduction hole 612 and tries to enter the inner side of the inner cover portion 60 can be reduced.

  In addition, Sample No. which showed a good result with a water coverage Wb of 2.0% or less. 3-No. 6 of sample No. 6 satisfying distance A> distance B. 4-No. No. 6 shows a very good result with a water content Wb of 1.0% or less. Thereby, when it sees along radial direction RD, it turns out that it is more preferable to form the inner side gas introduction hole 612 in the position which satisfy | fills distance A> distance B among the protrusion parts 610. FIG. From the inventors' investigation, it is known that the water that has passed through the outer gas introduction hole 512 adheres more to the inner peripheral surface 502b of the outer cylindrical portion 502 than to the outer peripheral surface 602a of the inner cylindrical portion 602. By setting the distance A> the distance B, it is considered that the water that passes through the inner gas introduction hole 612 and tries to enter the inner cover portion 60 can be reduced.

  As described above, the gas sensor element 40 of the first embodiment forms the inner gas introduction hole 612 at a position satisfying the distance A ≧ 0.5 mm or the distance B ≧ 0.2 mm in the protrusion 610. Further, it is possible to suppress water from adhering to the tip portion 42 and to prevent a situation in which a crack occurs in the tip portion 42. Further, by forming the inner gas introduction hole 612 at a position that satisfies the above condition (distance A ≧ 0.5 mm or distance B ≧ 0.2 mm) and satisfies distance A> distance B, the tip 42 is formed. It is possible to further suppress the adhesion of water and to further prevent the occurrence of cracks at the tip portion 42.

  Further, when the inner gas introduction hole 612 and the metal shell 10 are projected on the front end side of the gas sensor 1 along the axial direction BD, all of the inner gas introduction holes 612 are in a positional relationship overlapping with the metal shell 10. Most of the gas to be measured that has passed through the introduction hole 612 and entered from the outside to the inside of the inner cover portion 60 hits the bottom surface 10 b of the metal shell 10. As a result, water contained in the gas to be measured is captured by the metal shell 10, and water can be further suppressed from adhering to the distal end portion 42.

  Further, since the folded portion 614 (FIG. 4) extends in the direction toward the tip 40s (FIG. 1) of the gas sensor element 40 along the axial direction BD, the inner peripheral surface 502b of the outer cylindrical portion 502 and the inner cylindrical portion It is possible to suppress water from reaching the inner gas introduction hole 612 along the outer peripheral surface 602a of 602. Thereby, it can reduce more that water adheres to the front-end | tip part 42. FIG. In addition, the experimental result which supports the effect of the folding | returning part 614 is mentioned later.

  Further, the wall surface portion 620 and the outer cylindrical portion 502 are laser welded over the entire circumference and fixed to the metal shell 10, so that the gap between the outer cylindrical portion 502 and the inner cylindrical portion 602, and the inner cylinder It is possible to further suppress water from entering the inside of the inner cover part 60 through the gap between the shape part 602 and the metal shell 10.

B. Other examples:
B-1. Second embodiment:
FIG. 6 is a partial cross-sectional view of the gas sensor of the second embodiment. The difference from the gas sensor 1 of the first embodiment is the direction of the folded portion 614 a extending from the peripheral edge of the inner gas introduction hole 612. Other configurations (the metal shell 10 and the like) are the same configurations as those of the gas sensor 1 of the first embodiment, and thus the same configurations are denoted by the same reference numerals and description thereof is omitted. In FIG. 6, only a part of the metal shell 10 and the protector 45 is illustrated.

  In the second embodiment, a fold-back portion 614a extending a predetermined length in the direction toward the rear end side (upward on the paper surface) of the gas sensor 1a in the axial direction BD is provided at the peripheral portion of the inner gas introduction hole 612. The folded portion 614a can be formed, for example, by performing a punching process in a direction from the front end side to the rear end side of the gas sensor 1. Even if it does in this way, when paying attention to distance A, it can control that water adheres to tip part 42 by satisfying distance A> = 0.5mm, and can prevent the situation where a crack occurs in tip part 42. it can. Moreover, when paying attention to the distance B, it can suppress that water adheres to the front-end | tip part 42 by satisfying distance B> = 0.2mm, and can prevent the situation where the front-end | tip part 42 generate | occur | produces a crack. Also in the second embodiment, it is more preferable that the distance A> the distance B is satisfied as in the first embodiment. By doing so, it is possible to further suppress the water from adhering to the tip portion 42 and to further prevent the occurrence of cracks in the tip portion 42.

  FIG. 7 shows the results of a second experiment in which the influence of the direction of the folded portion on the amount of moisture at the tip of the gas sensor element was examined. Sample No. 3-No. The experimental result of Sample No. 6 is the sample No. shown in the first experimental result (FIG. 5A). 3-No. The result of 6 is shown again. Sample No. 9 to Sample No. 11, the direction of the folded portion is the direction toward the rear end side of the gas sensor 1 along the axial direction BD as in the second embodiment (FIG. 6). That is, sample No. 9 to Sample No. 11 is a sample in which the direction of the folded portion 614a is upward. Sample No. 9 to Sample No. 11 was also subjected to an evaluation experiment under the same conditions and method as the wet test performed when the first experimental result was obtained (FIG. 5B).

  As shown in FIG. 7, when the inner gas introduction hole 612 is formed at a position satisfying the distance A ≧ 0.5 mm or the distance B ≧ 0.2 mm even in the sample in which the direction of the folded portion 614 a is upward. Shows a good result that the water coverage Wb is 2.0% or less. However, when the moisture content Wb of samples having the same formation position of the inner gas introduction hole 612 in the protruding portion 610 (that is, the same distance A and the same distance B) and different directions of the folded portions 614 and 614a is compared, the folded portion The experiment result of the sample with 614 facing downward indicates a smaller value of the water content Wb. For example, sample no. 3 and sample no. 9 is compared with the sample No. in which the folded portion 614 faces downward. It can be seen that the amount of water Wb of 3 is smaller. Sample No. 4 and sample no. 10, sample no. 5 and sample no. Similarly, when each of the samples 11 and 11 is compared, the sample with the folded-back portion 614 facing downward has a smaller amount of water.

  As described above, the gas sensor 1 (FIG. 4) with the folded portion 614 facing downward further suppresses water from adhering to the tip end portion 42 than the gas sensor 1 a with the folded portion 614 a facing upward (FIG. 6). This can prevent the occurrence of cracks at the tip 42.

B-2. Third and fourth embodiments:
FIG. 8 is a first explanatory diagram for explaining another embodiment. FIG. 8A is a partial sectional view of a gas sensor according to a third embodiment of the present invention. FIG. 8B is a partial cross-sectional view of the gas sensor of the fourth embodiment according to the present invention. The difference between the gas sensor 1 of the first embodiment and the gas sensors 1b and 1c of the third and fourth embodiments is the configuration of the protruding portion 610. Other configurations (the metal shell 10 and the like) are the same configurations as those of the gas sensor 1 of the first embodiment, and thus the same configurations are denoted by the same reference numerals and description thereof is omitted. Also in the third and fourth embodiments, as in the first embodiment, the inner gas introduction hole 612 is formed at a position satisfying the distance A ≧ 0.5 mm or the distance B ≧ 0.2 mm. In FIG. 8, only a part of the metal shell 10 and the protector 45 is shown.

As shown to Fig.8 (a), as for the gas sensor 1b of 3rd Example, the protrusion part 610b inclines with respect to radial direction RD. Specifically, the protrusion 610b is inclined toward the inner gas introduction hole 612 throughout. In other words, the protruding portion 610b is configured to be positioned on the leading end side (the lower side in the drawing) of the gas sensor 1b as it approaches the inner gas introduction hole 612. That is, the inner gas introduction hole 612 is positioned at the most distal end side in the protruding portion 610b. Accordingly, it is possible to suppress water from reaching the inner gas introduction hole 612 along the inner peripheral surface 502b of the outer cylindrical portion 502 and the outer peripheral surface 602a of the inner cylindrical portion 602. Even if water adhering to the bottom surface 10b of the metal shell 10 falls to the tip side (lower side), the tip portion 42 flows toward the inner gas introduction hole 612 of the projection 610b due to the inclination of the projection 610b. It is possible to further suppress water from adhering to the surface. As a result, it is possible to further prevent the occurrence of cracks at the tip 42.
In the gas sensor 1b, as in the first embodiment, a folded portion 614 (FIG. 4) extending a predetermined length in the direction toward the tip 20s (FIG. 1) of the gas sensor element 40 at the peripheral portion of the inner gas introduction hole 612. May be provided. By carrying out like this, it can suppress that water adheres to the front-end | tip part 42 further.

  As shown in FIG. 8B, in the gas sensor 1c of the fourth embodiment, the protrusion 610 is formed in parallel with the radial direction RD, and the folded portions 614, 614a ( 4 and 6) are not provided. That is, the protrusion 610 has a uniform thickness. Even in this case, by forming the inner gas introduction hole 612 at a position satisfying the distance A ≧ 0.5 mm or the distance B ≧ 0.2 mm, water is introduced into the distal end portion 42 as in the first embodiment. It can suppress adhering and can prevent the front-end | tip part 42 from generating a crack.

B-3. Fifth and sixth embodiments:
FIG. 9 is a second explanatory diagram for explaining another embodiment. FIG. 9A is a partial cross-sectional view of a gas sensor according to a fifth embodiment of the present invention. FIG. 9B is a partial cross-sectional view of the gas sensor of the sixth embodiment according to the present invention. The difference between the gas sensor 1 of the first embodiment and the gas sensor 1d of the fifth embodiment is the configuration of the wall surface portion 620. The difference between the gas sensor 1 of the first embodiment and the gas sensor 1 e of the sixth embodiment is the configuration of the outer gas introduction hole 512. Other configurations (the metal shell 10 and the like) are the same configurations as those of the gas sensor 1 of the first embodiment, and thus the same configurations are denoted by the same reference numerals and description thereof is omitted. In the fifth and sixth embodiments, as in the first embodiment, the inner gas introduction hole 612 is formed at a position that satisfies the distance A ≧ 0.5 mm or the distance B ≧ 0.2 mm. In FIG. 9, only members necessary for explanation are shown.

  As shown in FIG. 9A, the wall surface portion 620 of the fifth embodiment is in contact with the bottom surface 10 b of the metal shell 10 without overlapping the outer peripheral surface of the metal shell 10. That is, the metallic shell 10 and the wall surface portion 620 are not fixed by laser welding. Even in this case, since the inner bottom surface portion 601 and the outer bottom surface portion 501 are fixed to each other by spot welding, the inner cover portion 60d is fixed to the outer cover portion 50, and the inner cover portion 60d is attached to the inside of the exhaust gas pipe. It can suppress that the fixing position of cover part 60 shifts. Even in this case, the inner gas introduction hole 612 is formed at a position satisfying the distance A ≧ 0.5 mm or the distance B ≧ 0.2 mm, so that the tip portion 42 has water in the same manner as in the above embodiment. Can be prevented, and the occurrence of cracks at the tip 42 can be prevented.

  As shown in FIG. 9B, in the fifth embodiment, a folding portion 514 extending a predetermined length in the direction toward the outside in the radial direction RD is provided at the peripheral portion of the outer gas introduction hole 512. Thereby, it is possible to reduce the water adhering to the outer peripheral surface 502a of the outer cylindrical portion 502 from reaching the outer gas introduction hole 512 along the outer peripheral surface 502a. Therefore, it is possible to further suppress water from entering the inside from the outside of the inside cover portion 60. Here, the length J of the folded portion 514 is preferably 0.2 mm or more. By setting it as 0.2 mm or more, water reaching the outer gas introduction hole 512 along the outer peripheral surface of the outer cylindrical portion 502 can be further reduced.

C. Variations:
In addition, elements other than the elements described in the independent claims of the claims in the constituent elements in the above-described embodiments are additional elements and can be omitted as appropriate. Further, the present invention is not limited to the above-described examples and embodiments, and can be implemented in various forms without departing from the gist thereof. For example, the following modifications are possible.

C-1. First modification:
In the above embodiment, when the inner gas introduction hole 612 and the metal shell 10 are projected on the tip side of the gas sensors 1, 1a, 1b, 1c, 1d, and 1e along the axial direction BD, all of the inner gas introduction holes 612 are formed. Although it was in a positional relationship overlapping with the metal shell 10, it is not limited to this. For example, a positional relationship in which a part of the inner gas introduction hole 612 overlaps with the metal shell 10 may be employed, or a positional relationship in which the inner gas introduction hole 612 and the metal shell 10 do not overlap may be employed.
Even in this case, by forming the inner gas introduction hole 612 at a position satisfying the distance A ≧ 0.5 mm or the distance B ≧ 0.2 mm, water adheres to the tip portion 42 as in the above embodiment. It is possible to suppress the occurrence of cracks at the tip portion 42.
In addition, it is preferable that at least a part of the inner gas introduction hole 612 overlaps the metal shell 10 when projected onto the front end side of the gas sensors 1, 1 a, 1 b, 1 c, 1 d, 1 e.

C-2. Second modification:
In the above embodiment, the inner gas introduction hole 612 has a circular shape, but is not limited thereto, and may be, for example, an oval shape or a polymorphic shape. That is, the shape of the inner gas introduction hole 612 is not limited as long as it penetrates the protrusions 610, 610 a, and 610 b and the gas to be measured can be introduced from the outer side of the inner cover portion 60 to the inner side.
Even in this case, by forming the inner gas introduction hole 612 at a position satisfying the distance A ≧ 0.5 mm or the distance B ≧ 0.2 mm, water adheres to the tip portion 42 as in the above embodiment. It is possible to suppress the occurrence of cracks at the tip portion 42.

C-3. Third modification:
In the above embodiment, the inner gas introduction hole 612 has a diameter φC of 1.2 mm, but is not particularly limited thereto. Note that the inner gas introduction hole 612 preferably has an opening to the extent that the inner gas introduction hole is not blocked by particulate matter such as soot contained in the measurement gas. For example, when the inner gas introduction hole 612 is circular, the inner gas introduction hole 612 is preferably 0.5 mm or more in diameter. In this way, it is possible to prevent water from adhering to the tip portion 42 and prevent the tip portion 42 from being cracked, and the inner gas introduction hole 612 due to particulate matter in the gas to be measured. Can be suppressed, and the responsiveness of the gas sensor 1 can be maintained well.

C-4. Fourth modification:
In the above embodiment, twelve inner gas introduction holes 612 are formed in the protrusions 610 and 610b. However, the present invention is not limited to this, and one or more inner gas introduction holes 612 are formed in the protrusions 610 and 610b. It only has to be formed. Even in this case, by forming the inner gas introduction hole 612 at a position satisfying the distance A ≧ 0.5 mm or the distance B ≧ 0.2 mm, water adheres to the tip portion 42 as in the above embodiment. It is possible to suppress the occurrence of cracks at the tip portion 42.

C-5. Fifth modification:
In the third embodiment, the protrusion 610b is inclined toward the inner gas introduction hole 612 throughout (FIG. 8 (b)), but toward the inner gas introduction hole 612 in a part of the protrusion 610b. It may be inclined. Even in this case, it is possible to suppress the inner gas introduction hole 612 from reaching the inner peripheral surface 502b of the outer cylindrical portion 502 and the outer peripheral surface 602a of the inner cylindrical portion 602 due to the inclination of the protruding portion 610b.

C-6. Sixth modification:
In the above embodiment, the bottomed cylindrical gas sensor element 40 is used, but the shape of the gas sensor element 40 is not particularly limited thereto. For example, a plate type (flat plate) gas sensor element may be used. Even in this case, by forming the inner gas introduction hole 612 at a position satisfying the distance A ≧ 0.5 mm or the distance B ≧ 0.2 mm, water adheres to the tip portion 42 as in the above embodiment. It is possible to suppress the occurrence of cracks at the tip portion 42.

C-7. Seventh modification:
In the above embodiment, the gas sensor has been described by taking an oxygen sensor capable of measuring the oxygen concentration in the gas to be measured as an example, but it can be applied to various sensors such as a NOx sensor and an HC sensor.

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c, 1d, 1e ... Gas sensor 10 ... Metal fitting 10a ... Hexagonal part 10b ... Bottom 10c ... Screw part 10d ... Inner peripheral surface 12 ... Through-hole 20 ... Metal outer cylinder 20a ... Tip part 20k ... Rear end Side opening 20s ... tip 30 ... heater 40 ... gas sensor element 40f ... flange 40s ... tip 42 ... tip 45 ... protector 50, 50e ... outer cover 60, 60d ... inner cover 80 ... piping 82 ... spray nozzle 83 ... Metal packing 84 ... Nozzle 109b, 109c ... Electrode pad 135 ... Insulator 139 ... Talc 141 ... Sleeve 203 ... Grommet 205 ... Filter member 207 ... Separator 211, 212 ... Sensor output lead wire 213, 214 ... Heater lead wire 215 ... First Sensor terminal fitting 215b ... Connector portion 215c ... insertion part 216 ... second sensor terminal fitting 216b ... connector part 216c ... gripping part 217 ... heater terminal fitting 501 ... outer bottom face part 502 ... outer cylindrical part 502a ... outer peripheral face 502b ... inner peripheral face 503 ... outer tip vent hole 512 ... outside gas introduction hole 514 ... turned back part 601 ... inner bottom face part 602 ... inner cylindrical part 602a ... outer peripheral face 603 ... inner end vent hole 610,610b ... protrusion part 612 ... inner gas inlet hole 614,614a ... folded back part 620 ... Wall surface portion BD: axial direction RD: radial direction AX: axial line Wa: water

Claims (8)

A gas sensor element extending in the axial direction;
With the tip of the gas sensor element protruding from its tip, a cylindrical metal shell surrounding the gas sensor element,
A protector that is fixed to the metal shell and surrounds the periphery of the tip of the gas sensor element,
The protector is
A cylindrical outer cover portion joined to the metal shell and having an outer gas introduction hole on a side surface;
In the radial direction that is joined to the outer cover portion and orthogonal to the axial direction, the outer cover portion, and an inner cover portion that is disposed between the gas sensor element,
The inner cover portion is
A cylindrical inner cylindrical portion having a portion facing the outer gas introduction hole, and an inner cylindrical portion surrounding the periphery of the distal end portion of the gas sensor element;
An annular projecting portion protruding from the rear end side of the inner cylindrical portion toward the radially outer side, and an outer edge reaching the outer cover portion,
The projecting portion has an inner gas introduction hole for introducing gas from the outside to the inside of the inner cover portion,
The inner gas introduction hole is formed at a position away from the outer peripheral surface of the inner cylindrical portion by 0.2 mm or more in the projecting portion when viewed along the radial direction.
A gas sensor characterized by that. A gas sensor element extending in the axial direction;
With the tip of the gas sensor element protruding from its tip, a cylindrical metal shell surrounding the gas sensor element,
A protector that is fixed to the metal shell and surrounds the periphery of the tip of the gas sensor element,
The protector is
A cylindrical outer cover portion joined to the metal shell and having an outer gas introduction hole on a side surface;
In the radial direction that is joined to the outer cover portion and orthogonal to the axial direction, the outer cover portion, and an inner cover portion that is disposed between the gas sensor element,
The inner cover portion is
A cylindrical inner cylindrical portion having a portion facing the outer gas introduction hole, and an inner cylindrical portion surrounding the periphery of the distal end portion of the gas sensor element;
An annular projecting portion protruding from the rear end side of the inner cylindrical portion toward the radially outer side, and an outer edge reaching the outer cover portion,
The projecting portion has an inner gas introduction hole for introducing gas from the outside to the inside of the inner cover portion,
The inner gas introduction hole is formed at a position away from the inner peripheral surface of the outer cover portion by 0.5 mm or more in the projecting portion when viewed along the radial direction.
A gas sensor characterized by that. The gas sensor according to claim 1 or 2,
When viewed along the radial direction perpendicular to the axial direction, the distance between the inner peripheral surface of the outer cover portion and the inner gas introduction hole is larger than the distance between the outer peripheral surface of the inner cylindrical portion and the inner gas introduction hole. The distance is larger,
A gas sensor characterized by that. The gas sensor according to any one of claims 1 to 3,
When projected in the axial direction, the inner gas introduction hole is in a positional relationship overlapping with the metal shell,
A gas sensor characterized by that. The gas sensor according to any one of claims 1 to 4,
The protrusion has a folded portion that extends in a direction from the periphery of the inner gas introduction hole toward the tip of the gas sensor element along the axial direction.
A gas sensor characterized by that. A gas sensor according to any one of claims 1 to 5,
At least a part of the protrusion is inclined with respect to the radial direction so that the inner gas introduction hole is located on the most distal side of the protrusion.
A gas sensor characterized by that. A gas sensor element extending in the axial direction;
With the tip of the gas sensor element protruding from its tip, a cylindrical metal shell surrounding the gas sensor element,
A protector that is joined to the metal shell and surrounds the periphery of the tip of the gas sensor element, and a manufacturing method of a gas sensor comprising:
The protector includes an outer cover part, and an inner cover part disposed inside the outer cover part, the inner cover part having an inner cylindrical part and a protruding part,
(A) molding the cylindrical outer cover part;
(B) the inner cover portion having the tubular inner tubular portion and the annular projecting portion projecting from the rear end side of the inner tubular portion toward the radially outer side perpendicular to the axial direction. Molding process;
(C) A step of providing an inner gas introduction hole, which is a through hole, in the protruding portion, and when viewed along the radial direction, the protruding portion is 0.2 mm or more from the outer peripheral surface of the inner cylindrical portion. Providing the inner gas introduction hole at a distant position;
A method of manufacturing a gas sensor, comprising: A gas sensor element extending in the axial direction;
With the tip of the gas sensor element protruding from its tip, a cylindrical metal shell surrounding the gas sensor element,
A protector that is joined to the metal shell and surrounds the periphery of the tip of the gas sensor element, and a manufacturing method of a gas sensor comprising:
The protector includes an outer cover part, and an inner cover part disposed inside the outer cover part, the inner cover part having an inner cylindrical part and a protruding part,
(A) molding the cylindrical outer cover part;
(B) The inner protector having the tubular inner tubular portion and the annular projecting portion projecting from the rear end side of the inner tubular portion toward the radially outer side perpendicular to the axial direction is molded. And a process of
(C) A step of providing an inner gas introduction hole which is a through hole in the protruding portion, and when viewed along the radial direction, at the protruding portion, 0.5 mm or more from the inner peripheral surface of the outer cover portion Providing the inner gas introduction hole at a distant position;
A method of manufacturing a gas sensor, comprising: