JP2013234878A - Gas sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas sensor which prevents a water droplet from moving toward the direction of a detection element, so that the detection element is surely prevented from being wetted with water.SOLUTION: The outer surface 126 of an inner protector 120 is provided with a water capturing part 130. The outer surface 118 of an outer protector 110 is provided with a water capturing part 140, and the inner surface 117 is provided with a water capturing part 145. When exhaust gas passing through an exhaust pipe collides with a protector 100, a water droplet contained in the exhaust gas is captured with the water capturing part 140 of the outer protector 110. The water droplet captured with the water capturing part 140 is heated with the exhaust gas for evaporation. A water droplet entering a gas separation chamber 119 from an outer inlet port 170 collides with the water capturing part 130 of the inner protector 120 opposite to the outer inlet port 170 so as to be captured with a groove part 131. The water droplet moves along the groove part 131 so as to be discharged from the outer inlet port 170 on the exit side of the exhaust gas.

Description

  The present invention relates to a gas sensor including a protector that protects a detection element exposed to a detection gas from water.

  Conventionally, a gas sensor provided with a detection element that generates electromotive force of different magnitude or changes its resistance value according to the concentration of a specific gas, such as NOx (nitrogen oxide) or oxygen, in an exhaust gas of an automobile or the like It has been known. This gas sensor is used by being attached to the exhaust pipe of an automobile, etc., but the detection element becomes hot by heating the detection element or exposing the detection element to high-temperature exhaust gas. If the detection element is subjected to a thermal shock due to the moisture (water droplets) contained in the gas adhering (watering) to the detection element, there is a possibility that cracks or cracks may occur. Therefore, a protector that covers the detection element is attached to the gas sensor, and the detection element is protected from being exposed to water.

  For example, the gas sensor described in Patent Document 1 includes a gas sensor element, a housing, and an element cover. The element cover has a double structure of an outer cover and an inner cover. The outer cover has an outer opening, and the inner cover has an inner opening at a position closer to the base end side than the outer opening. In the gap between the outer cover and the inner cover, a plurality of partition portions that divide the gap along the axial direction are formed. In the divided space divided by the outer cover, the inner cover, and the partition part, either one of the inner opening and the outer opening is disposed. The divided space in which the inner opening is disposed and the divided space in which the outer opening is disposed are communicated with each other by a communication portion formed on the base end side of the partition portion that partitions the two.

  In the gas sensor described in Patent Document 1, the exhaust gas that has entered from the outer opening of the outer cover rises in the divided space, enters the adjacent divided space from the communication portion, and enters the inner opening from the inner opening of the adjacent divided space. It is designed to enter the cover. With such a structure, water drops are prevented from entering the inner cover.

  Moreover, in the gas sensor described in Patent Document 2, in order to integrate the outer cover and the inner cover, a plurality of recesses recessed inward are formed in each of the outer cover and the inner cover. The outer cover and the inner cover are integrated by engaging the recess.

JP 2009-58364 A JP-A-1-223333

  However, even in the gas sensor described in Patent Document 1, there is a possibility that water droplets rise in the divided space, enter the adjacent divided space from the communication portion, and enter the inner cover from the inner opening of the adjacent divided space. there were. In this case, there is a problem that cracks or cracks may occur when the detection element receives a thermal shock due to water droplets adhering to the detection element (water exposure).

  The present invention has been made to solve the above problems, and provides a gas sensor that can prevent water droplets from moving in the direction of the detection element and reliably prevent the detection element from getting wet. Objective.

  According to the first aspect of the present invention, the detection element that extends in the axial direction and has a detection unit for detecting a specific gas component in the gas to be detected on the tip side, and the detection unit are protruded from the tip of its own. A metal shell that surrounds and holds the periphery of the detection element in the radial direction, a peripheral wall and a distal end wall on the distal end side thereof, and the opening on the proximal end side in the state in which the detection unit is accommodated inside A protector in which an end portion is fixed to the tip end portion of the metal shell and an inlet for introducing the detected gas into the peripheral wall is formed therein or has a plurality of gaps. In the gas sensor, the surface of the peripheral wall of at least one of the protectors is processed to provide a water droplet capturing portion for capturing water droplets on the surface, and the water droplet capturing portion has a groove shape, a ridge shape, and a dimple shape. Projecting shape Gas sensor, which is a one is provided even without.

  In the first aspect, since the water droplet trapping portion having at least one of the groove shape, the ridge shape, the dimple shape, and the protrusion shape is provided on the surface of the peripheral wall of the protector, the water droplet trapped in the water droplet trapping portion is easily evaporated. Become. Therefore, it is possible to prevent the detection element from being damaged due to water droplets adhering to the detection element.

  In the first aspect, the protector has a peripheral wall and a distal end wall on the distal end side thereof, and the opening end on the proximal end side is the distal end of the metal shell in a state in which the detection unit is accommodated inside the protector. At least the inner side of the inner protector having an air gap between the inner protector and the inner protector that is fixed to the inner part and has an inner inlet for introducing the detected gas into the peripheral wall. An outer protector having a cylindrical shape surrounding the peripheral wall of the protector and having an outer inlet for introducing the detected gas into the gap on the peripheral wall of the protector, the inner inlet and the outer inlet The water droplet trapping portion may be formed on the outer surface of the peripheral wall of the inner protector, the inner surface of the outer wall of the outer protector, and / or the outer peripheral surface of the outer wall between the gas flow paths formed therebetween. There.

  When the water droplet trapping part is formed on the outer surface of the peripheral wall of the inner protector between the gas flow paths formed between the inner inlet and the outer inlet, water drops that have entered between the gas flow paths from the outer inlet It can move to the inner inlet of the upper part of an inner protector, and can prevent entering into an inner protector from an inner inlet. In addition, when a water droplet trapping portion is formed on the outer surface of the peripheral wall of the outer protector, the water droplet trapped by the water droplet trapping portion is likely to evaporate. Further, when a water droplet trapping portion is formed on the inner surface of the peripheral wall of the outer protector, the water droplet trapped by the water droplet trapping portion is likely to evaporate.

  In the first aspect, the protector has a peripheral wall and a distal end wall on the distal end side thereof, and the opening end on the proximal end side is the distal end of the metal shell in a state in which the detection unit is accommodated inside the protector. At least the inner side of the inner protector having an air gap between the inner protector and the inner protector that is fixed to the inner part and has an inner inlet for introducing the detected gas into the peripheral wall. An outer protector having a cylindrical shape surrounding the peripheral wall of the protector and having an outer introduction port for introducing the detected gas into the gap in the peripheral wall; and an outer surface of the peripheral wall of the inner protector; Of at least one of the inner walls of the outer wall of the outer protector, at least the water droplets are captured on the surface facing the gap in the region facing the inner inlet or the outer inlet. It may be formed.

  In this case, when the water droplet trapping part is formed on the surface facing the gap in the region facing the outer introduction port in the outer surface of the peripheral wall of the inner protector, the water droplet is captured by the water droplet trapping part, and the inner protector Water droplets do not move to the inner inlet. Further, when a water droplet trapping portion is formed in a region facing the inner inlet of the inner surface of the outer wall of the outer protector, the water droplet is trapped and evaporated in the water droplet trapping portion.

  Moreover, a 1st aspect may form the said water droplet capture | acquisition part in the outer surface of the surrounding wall of the said inner side protector. In this case, the water droplet is captured by the water droplet capturing portion on the outer surface of the peripheral wall of the inner protector, and the water droplet does not move to the inner inlet of the inner protector.

  Moreover, a 1st aspect may form the said water droplet capture | acquisition part in both the outer surface and inner surface of the surrounding wall of the said outside protector. In this case, since there is a water droplet trapping part on both the outer and inner surfaces of the outer protector wall, water droplets are captured both inside and outside the outer protector, and water droplets enter the inside through the inner inlet of the inner protector. Can be prevented.

  In the first aspect, a plurality of the water droplet capturing parts may be provided on the outer surface of the peripheral wall of the inner protector between the gas flow paths and the inner wall and / or the outer surface of the outer wall of the outer protector. Good. In this case, water droplets can be captured both on the outer and inner surfaces of the outer protector and on the outer surface of the inner protector, so that it is possible to prevent water droplets from entering the inside through the inner inlet of the inner protector.

2 is a partial cross-sectional view of the gas sensor 1. FIG. It is the front view of the protector 100 of 1st embodiment seen from the same direction as FIG. It is a longitudinal cross-sectional view of the protector 100 of 1st embodiment of the same direction as the cross section of FIG. It is a longitudinal cross-sectional view of the protector 100 of 2nd embodiment of the same direction as the cross section of FIG. It is a front view of the protector 100 of 3rd embodiment. It is a longitudinal cross-sectional view of the protector 100 of 3rd embodiment of the same direction as the cross section of FIG. It is a front view of the protector 100 of 4th embodiment. It is a longitudinal cross-sectional view of the protector 100 of 4th embodiment of the same direction as the cross section of FIG. It is a longitudinal cross-sectional view of the protector 100 of 5th embodiment of the same direction as the cross section of FIG. It is a front view of the protector 100 of 6th embodiment. It is a longitudinal cross-sectional view of the protector 100 of 6th Embodiment of the same direction as the cross section of FIG. It is a front view of the protector 100 of 7th Embodiment. It is a longitudinal cross-sectional view of the protector 100 of 7th Embodiment of the same direction as the cross section of FIG. It is a front view of protector 100 of an eighth embodiment. It is a longitudinal cross-sectional view of the protector 100 of 8th Embodiment of the same direction as the cross section of FIG. It is a front view of the protector 100 of 9th Embodiment. It is a longitudinal cross-sectional view of the protector 100 of 9th Embodiment of the same direction as the cross section of FIG. It is a front view of protector 100 of a 10th embodiment. It is a longitudinal cross-sectional view of the protector 100 of 10th Embodiment of the same direction as the cross section of FIG. It is a front view of protector 100 of an 11th embodiment. It is a longitudinal cross-sectional view of the protector 100 of 11th Embodiment of the same direction as the cross section of FIG. It is a longitudinal cross-sectional view of the modification of the protector 100. FIG. It is a perspective view of the modification of the inner protector.

  Hereinafter, a first embodiment of a gas sensor embodying the present invention will be described with reference to FIGS. 1 to 3, the axis O direction of the gas sensor 1 (indicated by a one-dot chain line) is shown as a vertical direction, and the detection unit 11 side of the detection element 10 held inside is the front end side of the gas sensor 1 and the rear end portion 12. The side (see FIG. 2) will be described as the rear end side of the gas sensor 1.

  A gas sensor 1 shown in FIG. 1 is attached to an exhaust pipe (not shown) of an automobile, and a detection unit 11 of a detection element 10 held inside is exposed to exhaust gas flowing in the exhaust pipe, and is included in the exhaust gas. An example is a so-called oxygen sensor that detects an oxygen concentration as a gas to be detected.

  The detection element 10 has a narrow plate shape extending in the direction of the axis O as is well known, a gas detection body for detecting the oxygen concentration, and a heater body for heating to activate the gas detection body early. Are laminated together and integrated as a laminate having a substantially prismatic shape. In FIGS. 1 and 2, the left-right direction on the paper is shown as the plate thickness direction, and the front-back direction on the paper is shown as the plate width direction. The gas detector is composed of a solid electrolyte body mainly composed of zirconia, a detection electrode mainly composed of platinum, and the like (not shown), and the detection electrode is disposed in the detection section 11 on the distal end side of the detection element 10. . Further, six electrode pads 16 (two of which are shown in FIG. 1) are provided at the rear end portion 12 on the rear end side of the detection element 10 for taking out electrodes from the gas detection body and the heater body. Is formed. In the present embodiment, the detection element 10 is described as the “detection element” in the present invention. However, strictly speaking, the heater element is not necessarily required as the configuration of the detection element, and the gas detection element is the “detection element” of the present invention. It corresponds to “element”.

  A metal cup 20 made of metal having an opening 25 in the bottom wall in the shape of a bottomed cylinder is disposed at a position slightly on the tip side from the center of the body portion 13 of the detection element 10. The detection element 10 is inserted into the metal cup 20 through the opening 25, and the detection unit 11 protrudes from the opening 25 to the tip side. The metal cup 20 is a member for holding the detection element 10 in the metal shell 50, and a tip peripheral portion 23 having a tapered shape from the bottom wall to the outer peripheral wall is formed at the edge portion of the bottom wall. In the metal cup 20, an alumina ceramic ring 21 and a talc ring 22 obtained by compressing and solidifying talc powder are arranged and housed in layers in the direction of the axis O while surrounding the detection element 10. The talc ring 22 is crushed in the metal cup 20 so as to be filled in details, whereby the detection element 10 is positioned and held in the metal cup 20.

  The detection element 10 integrated with the metal cup 20 is surrounded and held by a cylindrical metal shell 50 made of low carbon steel such as SUS430. The metal shell 50 is for attaching and fixing the gas sensor 1 to an exhaust pipe (not shown) of an automobile, and an attachment portion 51 having a male screw for attachment to the exhaust pipe is provided on the outer peripheral tip side. . A distal end engaging portion 56 to which a protector 100 described later is engaged is formed on the distal end side of the mounting portion 51. Further, a tool engaging portion 52 with which a tool for attachment is engaged is formed at the center of the outer periphery of the metal shell 50. On the rear end side of the tool engagement portion 52, a rear end engagement portion 57 with which an outer cylinder 30 described later is engaged is formed. Further, on the rear end side, the detection element 10 is added in the metal shell 50. A caulking portion 53 is formed for tightening and holding. And between the tool engaging part 52 and the attaching part 51, the annular gasket 55 which prevents the gas escape when attaching to an exhaust pipe is inserted.

  Next, a stepped portion is provided in the vicinity of the attachment portion 51 on the inner periphery of the metal shell 50, and the tip peripheral portion of the metal cup 20 that holds the detection element 10 described above is provided in the stepped portion. 23 is locked. A talc ring 26 is loaded on the inner periphery of the metal shell 50 from the rear end side of the metal cup 20 with the detection element 10 inserted therethrough. Further, a cylindrical sleeve 27 is fitted into the metal shell 50 while allowing the detection element 10 to pass through so as to hold down the talc ring 26 from the rear end side. A shoulder portion 28 having a step shape is formed on the outer periphery of the rear end side of the sleeve 27, and an annular packing 29 is disposed on the shoulder portion 28. In this state, the crimping portion 53 of the metal shell 50 is crimped inward, and the shoulder portion 28 of the sleeve 27 is pressed toward the distal end side through the packing 29. By this caulking, the talc ring 26 pressed against the sleeve 27 is crushed in the metal shell 50 and filled in detail. The metal cup 20 and the detection element 10 are positioned and held in the metal shell 50 by the talc ring 26 and the talc ring 22 loaded in advance in the metal cup 20.

  The rear end portion 12 of the detection element 10 protrudes rearward from the rear end (caulking portion 53) of the metal shell 50, and the rear end portion 12 is covered with a cylindrical separator 60 made of insulating ceramics. ing. The separator 60 includes a front end side separator 63 and a rear end side separator 64, and the rear end side separator 64 is engaged with a bowl-shaped flange portion 62 provided on the front end side separator 63. The front-end separator 63 includes six electrode pads 16 formed at the rear end portion 12 of the detection element 10 and six connection terminals 61 (one of them in FIG. 1) that is electrically connected to each of the electrode pads 16. The connection site | part with the inside is accommodated and hold | maintained. The rear end side separator 64 accommodates a connection portion between each connection terminal 61 and six lead wires 65 (four of which are shown in FIG. 1) drawn out of the gas sensor 1 inside. Yes.

  A cylindrical outer cylinder 30 made of stainless steel (for example, SUS304) is disposed so as to surround the rear end portion 12 of the detection element 10 in which the separator 60 is fitted. The outer cylinder 30 has an opening end 31 on the front end side engaged with the outer periphery of the rear end engaging portion 57 of the metal shell 50. The open end 31 is crimped from the outer peripheral side, and further, laser welding is performed around the outer periphery and joined to the rear end engaging portion 57, whereby the outer cylinder 30 and the metal shell 50 are integrated. It has become.

  Further, in the gap between the outer cylinder 30 and the front end side separator 63, a metal-made cylindrical holding metal fitting 70 is disposed. The holding metal fitting 70 has a support portion 71 formed by bending the rear end of the holding metal 70 inward, and the support portion 71 is engaged with the flange portion 62 of the front end side separator 63 inserted into the inside thereof. The front end side separator 63 is held. In this state, the outer peripheral surface of the outer cylinder 30 where the holding metal fitting 70 is disposed is crimped inward, whereby the holding metal fitting 70 that supports the front end side separator 63 is fixed to the outer cylinder 30.

  Next, a grommet 75 made of fluorine rubber is fitted into the opening on the rear end side of the outer cylinder 30. The grommet 75 has six insertion holes 76 (one of which is shown in FIG. 1), and the six lead wires 65 drawn from the separator 60 are inserted into the insertion holes 76 in an airtight manner. Has been. In this state, the grommet 75 is clamped from the outer periphery of the outer cylinder 30 and is fixed to the rear end of the outer cylinder 30 while pressing the rear end side separator 64 against the front end side separator 63.

  On the other hand, the detection portion 11 of the detection element 10 held by the metal shell 50 protrudes from the tip end portion (tip engagement portion 56) of the metal shell 50. The protector 100 is fitted to the tip engaging portion 56 and is fixed by spot welding or laser welding. The protector 100 is for protecting the detection part 11 of the detection element 10 from the contamination | degradation by the deposits (toxic toxic substances, such as fuel ash and an oil component) in exhaust gas, the breakage | damage by water exposure, etc.

  Hereinafter, the structure of the protector 100 of 1st embodiment is demonstrated with reference to FIG.2 and FIG.3. The protector 100 shown in FIGS. 2 and 3 includes an inner protector 120 having a bottomed cylindrical shape having a peripheral wall 122 and a distal end wall 124 on the distal end side thereof, and an outer shape having a cylindrical shape surrounding the periphery of the peripheral wall 122 in the radial direction by the peripheral wall 112. It has a double structure composed of the protector 110. A gap between the outer surface 126 of the peripheral wall 122 of the inner protector 120 and the inner surface 117 of the peripheral wall 112 of the outer protector 110 is configured as a gas separation chamber 119.

  The inner protector 120 has an outer diameter that is smaller than the distal end engaging portion 56 of the metal shell 50, and the base end portion 121 on the opening end side (rear end side) is engaged with the outer periphery of the distal end engaging portion 56. The diameter is expanded to match. Further, the peripheral edge portion of the tip wall 124 is configured as a tapered portion 123 that expands in a tapered shape toward the peripheral wall 122. A plurality (six in this embodiment) of inner introduction ports 125 are opened in the circumferential wall 122 of the inner protector 120 along the circumferential direction at a position near the base end 121 in the axis O direction. The inner introduction port 125 mainly detects gas components in the exhaust gas introduced into the gas separation chamber 119 via the outer introduction port 170 of the outer protector 110 described later, and detects the inside of the inner protector 120, that is, the detection element 10. This is a hole for introducing the portion 11 into the exposed gas detection chamber 129.

  Laser welding is performed from the outer periphery of the base end portion 121 together with the outer protector 110 described later, and the inner protector 120 is fixed to the distal end engaging portion 56 of the metal shell 50. A discharge port 160 is opened in the distal end wall 124 of the inner protector 120. Water droplets that have entered the inner protector 120 (in the gas detection chamber 129) are discharged to the outside of the protector 100 through the discharge port 160. In addition, the gas component introduced into the gas detection chamber 129 via the inner introduction port 125 is also discharged to the outside via the discharge port 160, and gas exchange in the gas detection chamber 129 is performed. Yes.

  Next, one end of the outer protector 110 has an enlarged diameter, and is engaged with the outer periphery of the base end 121 of the inner protector 120 as the base end 111. With the base end portion 111 of the outer protector 110 overlapped with the base end portion 121 of the inner protector 120, the front end of the metal shell 50 (see FIG. 1) passes through the base end portion 121 from the outer peripheral surface side of the base end portion 111. Laser welding reaching the engaging portion 56 is performed while making a round around the outer periphery of the base end portion 111. Thereby, the outer protector 110 and the inner protector 120 are fixed to the metal shell 50.

  Further, the front end portion 113 of the outer protector 110 is bent inward near the tapered portion 123 of the inner protector 120. Thereby, the space | gap between the outer surface 126 of the surrounding wall 122 of the inner side protector 120 and the inner surface 117 of the outer side protector 110 is obstruct | occluded by the front end side, and it is comprised as said gas separation chamber 119. And the taper part 123 of the taper-shaped inner protector 120 becomes a form protruded toward the front end side in the axis O direction from the front end part 113 of the outer protector 110. The distal end portion 113 of the outer protector 110 and the tapered portion 123 of the inner protector 120 form a continuous taper although the angles are different.

  Next, on the peripheral wall 112 of the outer protector 110, a plurality of (six in this embodiment) outer introduction ports 170 that communicate the outside of the outer protector 110 and the gas separation chamber 119 are formed along the circumferential direction. ing. The outer introduction port 170 is formed at a position closer to the tip side than the formation position of the inner introduction port 125 of the inner protector 120 in the direction of the axis O (that is, the position of the rear end of the outer introduction port 170 is the inner introduction port 125). It is arranged on the tip side from the position of the tip.

  Next, with reference to FIG. 3, the water droplet capturing part 130 formed on the peripheral wall 122 of the inner protector 120 of the protector 100 of the first embodiment will be described. The water droplet capturing part 130 is a part that enters the gas separation chamber 119 from the outer introduction port 170 and captures water droplets attached to the peripheral wall 122 of the inner protector 120. The water droplet capturing part 130 is formed on the outer surface 126 of the peripheral wall 122 of the inner protector 120, between the inner inlet 125 and the tapered part 123, and in the region of the peripheral wall 122 facing the outer inlet 170. The water droplet capturing part 130 is configured by a groove-shaped groove part 131 that is formed in a plurality with a predetermined width and a predetermined depth in the circumferential direction of the inner protector 120. A wall portion 132 having a predetermined width is formed between the groove portion 131 and the adjacent groove portion 131. In the example shown in FIG. 3, six grooves 131 are formed on the peripheral wall 122 at regular intervals.

  When the gas sensor 1 having such a configuration is attached to the exhaust pipe of the internal combustion engine, the gas sensor 1 is attached with the front end side in the axis O direction downward in the direction of gravity, and the front end side is exposed in the exhaust pipe from the attachment portion 51 of the metal shell 50. The The exhaust gas flowing through the exhaust pipe collides with the protector 100 shown in FIG. 2 from at least a direction different from the direction of the axis O (for example, a direction orthogonal to the axis O), and the gas separation chamber 119 from the outer introduction port 170 of the outer protector 110. Introduced in. At this time, relatively heavy water (water droplets) contained in the exhaust gas and relatively light gas components are separated. The water droplet collides with the water droplet capturing part 130 of the inner protector 120 facing the outer introduction port 170 and is captured by the groove 131. Next, the water droplet travels along the groove 131 and is discharged from the outer introduction port 170 on the side from which the exhaust gas flows out. The water droplets captured by the water droplet capturing unit 130 are heated by the exhaust gas and evaporated. Accordingly, it is possible to prevent water droplets from climbing the outer surface 126 of the peripheral wall 122 of the inner protector 120 and entering the gas detection chamber 129 from the inner inlet 125.

  Next, with reference to FIG. 4, the water droplet capture | acquisition part 130 of the protector 100 of the gas sensor 1 of 2nd embodiment is demonstrated. The gas sensor 1 of the second embodiment is the same as the first embodiment except for the structure of the protector 100 and the other structures. In the third to eleventh embodiments, only the structure of the gas sensor 1 protector 100 is different and the other structures are the same. Therefore, only the differences from the protector 100 of the first embodiment will be described below.

  Hereinafter, the protector 100 of 2nd embodiment is demonstrated. In the protector 100 of the second embodiment, the structure of the outer protector 110 is the same as the structure of the outer protector 110 of the first embodiment. The water droplet capturing part 130 of the inner protector 120 is formed in a region approximately ½ of the distal end side of the inner protector 120 facing the outer introduction port 170. The water droplet capturing part 130 is configured by a plurality of ridge-shaped ridge parts 133 that protrude a predetermined height in the circumferential direction of the inner protector 120 and are formed. A wall portion 134 having a predetermined width is formed between the ridge portion 133 and the adjacent ridge portion 133. In the example shown in FIG. 4, six ridges 133 are formed on the peripheral wall 122 at regular intervals.

  In the protector 100 of the second embodiment, the water droplets that have entered the gas separation chamber 119 from the outer introduction port 170 of the outer protector 110 collide with the water droplet capturing unit 130 of the inner protector 120 that faces the outer introduction port 170. The water droplet is captured in a recess formed by the ridge portion 133 adjacent to the ridge portion 133 and the wall portion 134 therebetween. Next, the water droplet moves along the depression and is discharged from the outer introduction port 170 on the side from which the exhaust gas flows out. Further, the water droplets still captured by the water droplet capturing unit 130 are heated and evaporated by the exhaust gas, and are discharged from the outer introduction port 170. Accordingly, it is possible to prevent water droplets from climbing the outer surface 126 of the peripheral wall 122 of the inner protector 120 and entering the gas detection chamber 129 from the inner inlet 125.

  Next, with reference to FIG.5 and FIG.6, the structure of the protector 100 of 3rd embodiment is demonstrated. In the third embodiment, the inner protector 120 is not provided with the water droplet capturing portion 130, the water droplet capturing portion 140 is provided on the outer surface 118 of the outer protector 110, and the water droplet capturing portion 145 is provided on the inner surface 117. As shown in FIG. 5, in the third embodiment, a water droplet capturing part 140 is provided in a region around a portion where the outer introduction port 170 is formed on the outer surface 118 of the peripheral wall 122 of the outer protector 110. The water droplet capturing portion 140 is formed in a region at a position about 1/2 of the distal end side of the outer protector 110. The water droplet trapping portion 140 includes a groove-shaped groove portion 141 that is formed in a plurality with a predetermined width and a predetermined depth in the circumferential direction of the outer protector 110. A wall 142 having a predetermined width is formed between the groove 141 and the adjacent groove 141. In the example shown in FIGS. 5 and 6, six grooves 141 are formed on the peripheral wall 112 at regular intervals. As shown in FIG. 6, the inner surface 117 of the peripheral wall 112 on the back side of the groove portion 141 is formed with a plurality of ridge-shaped ridge portions 143 projecting a predetermined height in the circumferential direction. A wall 144 having a predetermined width is formed between the ridge 143 and the adjacent ridge 143. In the example shown in FIG. 6, six ridges 143 are formed on the inner surface 117 of the peripheral wall 112 at regular intervals. The ridge portion 143 and the wall portion 144 form a water droplet capturing portion 145.

  In the outer protector 110 of the third embodiment, when the exhaust gas flowing through the exhaust pipe collides with the protector 100, the water droplet capturing unit 140 of the outer protector 110 captures water droplets contained in the exhaust gas. The water droplets captured by the water droplet capturing unit 140 are heated by the exhaust gas and evaporated. Further, the water droplets that have entered the gas separation chamber 119 from the outer introduction port 170 of the outer protector 110 are captured by the water droplet capturing part 145 on the inner surface 117 of the peripheral wall 122 of the outer protector 110. The water droplets captured by the water droplet capturing unit 145 are heated and evaporated by the exhaust gas and are discharged from the outer introduction port 170.

  Next, with reference to FIG.7 and FIG.8, the structure of the protector 100 of 4th embodiment is demonstrated. In the fourth embodiment, a water droplet capturing portion 130 is provided on the outer surface 126 of the inner protector 120, a water droplet capturing portion 140 is provided on the outer surface 118 of the outer protector 110, and a water droplet capturing portion 145 is provided on the inner surface 117. The water droplet capturing unit 130 has the same structure as that of the first embodiment shown in FIG. Moreover, the water droplet capturing part 140 and the water droplet capturing part 145 of the outer protector 110 have the same structure as that of the third embodiment shown in FIG.

  In the protector 100 according to the fourth embodiment, when the exhaust gas flowing through the exhaust pipe collides with the protector 100, the water droplet capturing unit 140 of the outer protector 110 captures water droplets contained in the exhaust gas. The water droplets captured by the water droplet capturing unit 140 of the outer protector 110 are heated and evaporated by the exhaust gas. Further, the water droplet that has entered the gas separation chamber 119 from the outer introduction port 170 collides with the water droplet capturing unit 130 of the inner protector 120 facing the outer introduction port 170 and is captured by the groove 131. Next, the water droplet travels along the groove 131 and is discharged from the outer introduction port 170 on the side from which the exhaust gas flows out. Further, the water droplets captured and retained by the water droplet capturing unit 130 are heated by the exhaust gas and evaporated. Of the water droplets that have entered the gas separation chamber 119 from the outer introduction port 170, the water droplets captured by the water droplet capturing section 140 of the outer protector 110 are heated and evaporated by the exhaust gas. Accordingly, it is possible to prevent water droplets from climbing the outer surface 126 of the peripheral wall 122 of the inner protector 120 and entering the gas detection chamber 129 from the inner inlet 125.

  Next, the protector 100 of 5th embodiment is demonstrated with reference to FIG. In the fifth embodiment, the outer protector 110 is not provided with the water droplet trapping portion 140, and the water droplet trapping portion 130 is provided in a region approximately ½ of the distal end side of the inner protector 120 facing the outer introduction port 170. In the water droplet capturing portion 130, a plurality of dimple-shaped concave portions 135 recessed in a spherical shape are formed in the circumferential direction of the inner protector 120. In the example shown in FIG. 9, the rows of the recesses 135 formed in the circumferential direction of the inner protector 120 are formed in four upper and lower stages in the axis O direction.

  In the protector 100 of the fifth embodiment, when the exhaust gas flowing through the exhaust pipe collides with the protector 100, it is introduced into the gas separation chamber 119 from the outer introduction port 170 of the outer protector 110. The water droplet collides with the water droplet capturing portion 130 of the inner protector 120 facing the outer introduction port 170 and is captured by the concave portion 135. Since the recess 135 has a dimple shape, the water droplet is not reflected upward, and the water droplet is easily captured. Accordingly, it is possible to prevent water droplets from climbing the outer surface 126 of the peripheral wall 122 of the inner protector 120 and entering the gas detection chamber 129 from the inner inlet 125. Further, the water droplets captured in the recess 135 are heated and evaporated by the exhaust gas, and are discharged from the outer introduction port 170.

  Next, the structure of the protector 100 according to the sixth embodiment will be described with reference to FIGS. 10 and 11. In the sixth embodiment, a water droplet capturing part 130 is provided on the outer surface 126 of the inner protector 120, a water droplet capturing part 140 is provided on the outer surface 118 of the peripheral wall 112 of the outer protector 110, and a water droplet capturing part 145 is provided on the inner surface 117. ing. The water droplet capturing part 130 has the same structure as that of the fifth embodiment shown in FIG. Next, the water droplet capturing part 140 of the outer protector 110 will be described. In the sixth embodiment, on the outer surface 118 of the peripheral wall 122 of the outer protector 110, the water droplet capturing portion 140 is provided in a region around the portion where the outer introduction port 170 is formed. The water droplet capturing portion 140 is formed in a region at a position about 1/2 of the distal end side of the outer protector 110. The water droplet capturing part 140 is composed of a ridge-shaped ridge part 146 that protrudes a predetermined height in the circumferential direction of the outer protector 110 and is formed in plural. A wall portion 147 having a predetermined width is formed between the ridge portion 146 and the adjacent ridge portion 146. In the example shown in FIGS. 10 and 11, five ridges 146 are formed on the peripheral wall 112 of the outer protector 110 at regular intervals.

  Further, as shown in FIG. 11, a recess 148 that is recessed at a predetermined depth in the circumferential direction is formed on the inner surface 117 of the outer protector 110 of the peripheral wall 112 on the back side of the ridge 146. A wall portion 149 having a predetermined width is formed between the concave portion 148 and the adjacent concave portion 148. In the example shown in FIG. 11, five recesses 148 are formed on the inner surface 117 of the peripheral wall 112 at regular intervals. The water droplet capturing portion 145 is formed by the recess 148 and the wall portion 149.

  In the sixth embodiment, when the exhaust gas flowing through the exhaust pipe collides with the protector 100, the water droplet capturing unit 140 of the outer protector 110 captures water droplets contained in the exhaust gas. The water droplets captured by the water droplet capturing unit 140 are heated by the exhaust gas and evaporated. Further, the water droplets that have entered the gas separation chamber 119 from the outer introduction port 170 collide with the water droplet capturing unit 130 of the inner protector 120 facing the outer introduction port 170 and are captured by the recess 135. Since the recess 135 has a dimple shape, it is easy to capture water droplets, and the water droplets can be prevented from climbing the outer surface 126 of the peripheral wall 122 of the inner protector 120 and entering the gas detection chamber 129 from the inner inlet 125. Further, the water droplets captured in the recess 135 are heated and evaporated by the exhaust gas, and are discharged from the outer introduction port 170. Further, the water droplets captured by the water droplet capturing portion 145 on the inner surface 117 of the peripheral wall 122 of the outer protector 110 are heated and evaporated by the exhaust gas and are discharged from the outer introduction port 170.

  Next, the structure of the protector 100 according to the seventh embodiment will be described with reference to FIGS. In the seventh embodiment, the inner protector 120 is not provided with the water droplet capturing part 130. Instead, the water droplet capturing part 140 is provided in the entire region of the outer surface 118 of the peripheral wall 122 of the outer protector 110, and the water droplet capturing part 145 is provided in the entire region of the inner surface 117. The water droplet capturing part 140 is formed on the wall part 147 between the ridge part 146 having a predetermined height protruding in the circumferential direction of the outer protector 110 and formed in a plurality of ridge parts 146 and the ridge part 146 adjacent to the ridge part 146. The groove portion 150 has a groove shape with a predetermined width and a predetermined depth. In the example shown in FIGS. 12 and 13, five ridges 146 are formed on the peripheral wall 112 at regular intervals. Further, five grooves 141 are formed on the peripheral wall 112 at regular intervals.

  As shown in FIG. 13, the inner surface 117 of the peripheral wall 112 on the back side of the groove 150 includes a ridge portion 151 having a ridge shape that protrudes by a predetermined height in the circumferential direction. A wall portion 149 having a predetermined width is formed between the ridge portion 151 and the adjacent ridge portion 151. In the example shown in FIG. 13, five ridges 151 are formed on the inner surface 117 of the peripheral wall 112 at regular intervals. The wall 149 on the back side of the ridge 146 is formed with a recess 148 that is recessed at a predetermined depth in the circumferential direction. In the example shown in FIG. 13, five recesses 148 are formed on the inner surface 117 of the peripheral wall 112 at regular intervals. The ridge 151, the wall 149, and the recess 148 form a water droplet capturing part 145.

  In the seventh embodiment, when the exhaust gas flowing through the exhaust pipe collides with the protector 100, the wall portion 149 and the groove portion 150 of the water droplet capturing unit 140 capture water droplets contained in the exhaust gas. The water droplets captured by the water droplet capturing unit 140 are heated by the exhaust gas and evaporated. Further, water droplets that have entered the gas separation chamber 119 from the outer introduction port 170 are captured by the recess 148 and the wall portion 149 of the water droplet capturing portion 145 on the inner surface 117 of the peripheral wall 122 of the outer protector 110. The water droplets captured by the water droplet capturing unit 145 are heated and evaporated by the exhaust gas and are discharged from the outer introduction port 170.

  Next, the structure of the protector 100 according to the eighth embodiment will be described with reference to FIGS. The protector 100 according to the eighth embodiment includes only the outer protector 110 and does not include the inner protector 120. On the distal end side of the outer protector 110, a circular outer introduction port 170 for introducing exhaust gas into the gas detection chamber 129 inside the outer protector 110 from the outside is formed along the circumferential direction. A discharge port 160 for discharging water droplets to the outside is formed at the bottom of the outer protector 110.

  Next, the water droplet capturing part 140 of the outer protector 110 will be described. In the eighth embodiment, the water droplet capturing part 140 is provided in the entire region of the outer surface 118 of the peripheral wall 112 of the outer protector 110, and the water droplet capturing part 145 is provided in the entire region of the inner surface 117. The water droplet capturing portion 140 is configured by a groove-shaped groove portion 141 that is formed in a plurality with a predetermined width and a predetermined depth in the circumferential direction of the peripheral wall 112 of the outer protector 110. A wall 142 having a predetermined width is formed between the groove 141 and the adjacent groove 141. In the example shown in FIGS. 14 and 15, ten grooves 141 are formed on the peripheral wall 112 at regular intervals. Further, as shown in FIG. 15, the inner surface 117 of the peripheral wall 112 on the back side of the groove portion 141 is formed with a plurality of ridge-shaped ridge portions 143 projecting a predetermined height in the circumferential direction. A wall 144 having a predetermined width is formed between the ridge 143 and the adjacent ridge 143. In the example shown in FIG. 15, ten ridges 143 are formed on the inner surface 117 of the peripheral wall 112 at regular intervals. The ridge portion 143 and the wall portion 144 form a water droplet capturing portion 145.

  In the eighth embodiment, when the exhaust gas flowing through the exhaust pipe collides with the protector 100, the groove portion 141 of the water droplet capturing portion 140 of the outer protector 110 captures water droplets contained in the exhaust gas. The water droplets captured by the water droplet capturing unit 140 are heated by the exhaust gas and evaporated. Therefore, water droplets can be prevented from entering the gas detection chamber 129 from the outer introduction port 170 provided on the distal end side (lower side) through the outer surface 118 of the outer protector 110 to the distal end side (lower side). Further, water droplets that have entered the gas detection chamber 129 from the outer introduction port 170 are captured by the wall portion 144 between the ridge portion 143 and the ridge portion 143 of the water droplet capturing portion 145 on the inner surface 117 of the peripheral wall 122 of the outer protector 110. The The water droplets captured by the water droplet capturing unit 145 are heated and evaporated by the exhaust gas and are discharged from the outer introduction port 170.

  Next, with reference to FIG.16 and FIG.17, the protector 100 of 9th Embodiment is demonstrated. In the ninth embodiment, the water droplet capturing part 130 is provided on the outer surface 126 of the inner protector 120, the water droplet capturing part 140 is provided on the outer surface 118 of the outer protector 110, and the water droplet capturing part 145 is provided on the inner surface 117. The water droplet capturing unit 130 has the same structure as that of the second embodiment shown in FIG. The water droplet capturing unit 140 and the water droplet capturing unit 145 have the same structure as that of the sixth embodiment shown in FIGS. 10 and 11.

  In the ninth embodiment, when the exhaust gas flowing through the exhaust pipe collides with the protector 100, the water droplet capturing part 140 of the outer protector 110 captures water droplets contained in the exhaust gas. The water droplets captured by the water droplet capturing unit 140 are heated by the exhaust gas and evaporated. Further, the water droplets that have entered the gas separation chamber 119 from the outer introduction port 170 of the outer protector 110 collide with the water droplet capturing unit 130 of the inner protector 120 that faces the outer introduction port 170. The water droplet is captured in a depression formed by the ridge portion 133 adjacent to the ridge portion 133 of the water droplet capturing portion 130 and the wall portion 134 therebetween. Next, the water droplet moves along the depression and is discharged from the outer introduction port 170 on the side from which the exhaust gas flows out. Further, the water droplets captured and retained by the water droplet capturing unit 130 are heated by the exhaust gas and evaporated. Accordingly, it is possible to prevent water droplets from climbing the outer surface 126 of the peripheral wall 122 of the inner protector 120 and entering the gas detection chamber 129 from the inner inlet 125. Further, the water droplets captured by the water droplet capturing portion 145 on the inner surface 117 of the outer protector 110 are heated and evaporated by the exhaust gas and are discharged from the outer introduction port 170.

  Next, the protector 100 of 10th Embodiment is demonstrated with reference to FIG.18 and FIG.19. In the tenth embodiment, a water droplet capturing part 130 is provided on the outer surface 126 of the inner protector 120, a water droplet capturing part 140 is provided on the outer surface 118 of the outer protector 110, and a water droplet capturing part 145 is provided on the inner surface 117. The water droplet capturing unit 130 has the same structure as that of the fifth embodiment shown in FIG. That is, a plurality of dimple-shaped recesses 135 recessed in a spherical shape in the circumferential direction of the outer surface 126 of the inner protector 120 are formed in the water droplet capturing part 130. In the example shown in FIG. 19, the recesses 135 are formed in four rows vertically. Next, the water droplet capturing unit 140 will be described. In the tenth embodiment, the water droplet capturing part 140 is provided on the entire outer surface 118 of the peripheral wall 122 of the outer protector 110. The water droplet capturing part 140 is formed in the entire region of the outer surface 118 of the outer protector 110. The water droplet capturing portion 140 has a plurality of dimple-shaped recesses 136 that are recessed in a spherical shape in the circumferential direction of the water droplet capturing portion 140. In the example shown in FIG. 18, the recesses 136 are formed in six rows vertically.

  The water droplet capturing unit 145 will be described. As shown in FIG. 19, on the inner surface 117 of the peripheral wall 112 on the back side of the recess 136, a plurality of projection-shaped projections 137 protruding in a spherical shape are formed. A wall portion 138 having a predetermined width is formed between the convex portion 137 and the adjacent convex portion 137. In the example shown in FIG. 19, the convex portions 137 are formed in six rows vertically on the inner surface 117 of the peripheral wall 112. A water droplet capturing portion 145 is formed by the convex portion 137 and the wall portion 138.

  In the tenth embodiment, when the exhaust gas flowing through the exhaust pipe collides with the protector 100, the recess 136 of the water droplet capturing part 140 of the outer protector 110 captures water droplets contained in the exhaust gas. The water droplets captured by the water droplet capturing unit 140 are heated by the exhaust gas and evaporated. In addition, the water droplets that have entered the gas separation chamber 119 from the outer introduction port 170 collide with the water droplet capturing unit 130 of the inner protector 120 that faces the outer introduction port 170. The water droplet is captured in the recess 135 of the water droplet capturing unit 130, heated and evaporated by the exhaust gas, and discharged from the outer introduction port 170. Further, the water droplets captured by the water droplet capturing portion 145 on the inner surface 117 of the outer protector 110 are heated and evaporated by the exhaust gas and are discharged from the outer introduction port 170. Accordingly, it is possible to prevent water droplets from climbing the outer surface 126 of the peripheral wall 122 of the inner protector 120 and entering the gas detection chamber 129 from the inner inlet 125.

  Next, the structure of the protector 100 according to the eleventh embodiment will be described with reference to FIGS. Unlike the protector 100 of the first to tenth embodiments, the protector 100 of the eleventh embodiment has a triple structure. That is, the protector 100 according to the eleventh embodiment is arranged with an outer protector 110, an intermediate protector 220, and an inner protector 180 in order from the outside. On the peripheral wall 112 of the outer protector 110, a plurality (six in this embodiment) of outer introduction ports 170 that communicate the outside of the outer protector 110 and the gas separation chamber 119 are formed along the circumferential direction. The outer introduction port 170 is formed at a position closer to the front end side than the formation position of the intermediate introduction port 225 of the intermediate protector 220 in the direction of the axis O (that is, the position of the rear end of the outer introduction port 170 is the intermediate introduction port 225). It is arranged on the tip side from the position of the tip. The outer protector 110 is not provided with a water droplet capturing part.

  In the outer protector 110, an intermediate protector 220 having the same structure as the inner protector 120 of the first embodiment shown in FIG. 3 is provided. The structure of the intermediate protector 220 will be described with reference to FIG. The intermediate protector 220 has a bottomed cylindrical shape, and has an outer diameter smaller than the front end engaging portion 56 of the metal shell 50 and smaller than an inner diameter of the outer protector 110. In addition, the intermediate protector 220 is formed with a water droplet capturing part 230 and a water droplet capturing part 236 similar to those in the first embodiment in a region approximately ½ of the distal end side. A plurality (six in this embodiment) of intermediate inlets 225 are opened in the circumferential wall 222 of the intermediate protector 220 along the circumferential direction at a position near the base end 221 in the axis O direction. The intermediate inlet 225 is a hole for mainly introducing a gas component of the exhaust gas introduced into the gas separation chamber 119 through the outer inlet 170 of the outer protector 110 into the intermediate protector 220.

  The water droplet capturing unit 230 is a portion that enters the gas separation chamber 119 from the outer introduction port 170 and captures water droplets attached to the peripheral wall 222 of the intermediate protector 220. The water droplet capturing part 230 is formed on the outer surface 226 of the peripheral wall 222 of the intermediate protector 220 between the intermediate introduction port 225 and the tapered part 123 and in the region of the peripheral wall 222 facing the outer introduction port 170. The water droplet capturing unit 230 includes a groove-shaped groove portion 231 formed in a plurality with a predetermined width and a predetermined depth in the circumferential direction of the intermediate protector 220. A wall portion 232 having a predetermined width is formed between the groove portion 231 and the adjacent groove portion 231. In the example shown in FIG. 21, six grooves 231 are formed on the peripheral wall 222 at regular intervals.

  Next, the water droplet capturing unit 236 will be described. As shown in FIG. 21, a water droplet capturing portion 236 is formed on the inner surface 217 of the peripheral wall 222 on the back side of the groove portion 231. The water droplet capturing part 236 is formed with a ridge-shaped ridge part 237 projecting a predetermined height in the circumferential direction. A wall portion 238 having a predetermined width is formed between the ridge portion 237 and the adjacent ridge portion 237. In the example shown in FIG. 21, six ridges 237 are formed on the inner surface 217 of the peripheral wall 222 at regular intervals. The ridge portion 237 and the wall portion 238 form a water droplet capturing portion 236.

  Next, the structure of the inner protector 180 will be described with reference to FIG. The inner protector 180 has a bottomed cylindrical shape, and its outer diameter is smaller than the inner diameter of the intermediate protector 220 and smaller than the tip engaging portion 56 of the metal shell 50. The proximal end portion 121 on the opening end side (rear end side) is enlarged in diameter so as to engage with the outer periphery of the distal end engaging portion 56. A circular inner inlet 182 for introducing exhaust gas into the gas detection chamber 129 inside the intermediate protector 220 is formed along the circumferential direction at the distal end side of the inner protector 180.

  A water droplet trapping portion 184 is provided on the outer surface 188 of the peripheral wall 181 in a substantially ½ region on the rear end side (upper side) of the inner protector 180, and a substantially ½ region on the rear end side (upper side) of the inner protector 180. A water droplet capturing part 190 is also provided on the inner surface 187 of the peripheral wall 181. The water droplet capturing portion 184 is configured by a groove-shaped groove portion 185 formed in a plurality of grooves with a predetermined width and a predetermined depth in the circumferential direction of the outer surface 188 of the peripheral wall 181 of the inner protector 180. A wall portion 186 having a predetermined width is formed between the groove portion 185 and the adjacent groove portion 185. In the example shown in FIGS. 20 and 21, four grooves 185 are formed on the peripheral wall 181 at regular intervals. As shown in FIG. 21, a plurality of ridge-shaped ridge portions 191 are formed on the inner surface 187 of the peripheral wall 181 on the back side of the groove portion 185 so as to protrude in the circumferential direction by a predetermined height. A wall portion 192 having a predetermined width is formed between the ridge portion 191 and the adjacent ridge portion 191. In the example shown in FIG. 21, four ridges 191 are formed on the inner surface 187 of the peripheral wall 181 at regular intervals. The ridge portion 191 and the wall portion 192 form a water droplet capturing portion 190.

  In the eleventh embodiment, when the exhaust gas flowing through the exhaust pipe collides with the protector 100, the water droplets that have entered the outer protector 110 from the outer introduction port 170 of the outer protector 110 become the intermediate protector that faces the outer introduction port 170. It collides with 220 water droplet capturing section 230. The water droplet is captured in the groove 231. Next, the water droplet travels along the groove 231 and is discharged from the outer introduction port 170 on the side from which the exhaust gas flows out. The water droplets remaining in the groove portion 231 are heated and evaporated by the exhaust gas and are discharged from the outer introduction port 170.

  Further, the water droplets that have entered the intermediate protector 220 from the intermediate inlet 225 of the intermediate protector 220 are captured by the groove portion 185 of the water droplet capturing portion 184 of the inner protector 180. Next, the water droplet travels along the groove 185 and is discharged from the intermediate inlet 225 on the side from which the exhaust gas flows out. The water droplets remaining in the groove 185 are heated and evaporated by the exhaust gas and discharged from the intermediate inlet 225. Further, the water droplets captured by the water droplet capturing unit 236 of the intermediate protector 220 are heated and evaporated by the exhaust gas and discharged from the discharge port 160.

  The protector 100 is an example of the “protector” of the present invention, the outer protector 110 is an example of the “outer protector” of the present invention, and the inner protectors 120 and 180 are examples of the “inner protector” of the present invention. The water droplet capturing units 130, 140, 145, and 184 are examples of the “water droplet capturing unit” of the present invention. The inner introduction ports 125 and 182 are examples of the “inner introduction port” in the present invention. The outer introduction port 170 is an example of the “outer introduction port” in the present invention. The gas separation chamber 119 is an example of the “gap” and “gas flow path” of the present invention.

  The present invention is not limited to the above embodiment, and various modifications can be made. For example, the water droplet capturing portion 140 on the outer surface 118 of the outer protector 110, the water droplet capturing portion 145 on the inner surface 117, and the water droplet capturing portion 130 on the outer surface 126 of the inner protector 120 are not limited to the above-described embodiments, Any of a shape, a dimple shape, and a protrusion shape may be used. A plurality of shapes may be combined. Further, the water droplet capturing portions 130, 140, 145, and 184 may be longitudinal grooves or the like. In addition, the water droplet trapping portion can be formed by various methods such as punching, etching, chemical polishing, and the like.

  The present invention can also be applied to a gas sensor including a detection element 66 in which a solid electrolyte body made of ceramics such as zirconia is formed in a bottomed cylindrical shape, and a pair of electrodes sandwiching the solid electrolyte body is formed on the surface. . For example, as shown in FIG. 22, a plurality of outer introduction ports 170 are formed in the peripheral wall 112 of the outer protector 110 constituting the protector 100 as in the above embodiment. Further, as shown in FIG. 23, the peripheral wall 122 of the inner protector 120 is formed in a cylindrical shape without providing an inner inlet. Then, six notches 127 are formed in the peripheral wall 122A at the upper end of the inner protector 120 at regular intervals. This notch 127 functions as an inner inlet. Accordingly, as shown by an arrow A in FIG. 23, the exhaust gas flows from the notch 127 into the gas detection chamber 129 in the inner protector 120. In this case, there is no opening in the peripheral wall 122 of the inner protector 120, and the notch 127 serving as the inner introduction port exists in the peripheral wall 122A at the upper end of the inner protector 120, so that water droplets into the inner protector 120 can be prevented. High intrusion prevention effect.

  The present invention can be similarly applied to protectors used for NOx sensors, HC sensors, temperature sensors and the like in addition to the oxygen sensors described in the above embodiments.

DESCRIPTION OF SYMBOLS 1 Gas sensor 10 Detection element 11 Detection part 50 Main metal fitting 56 Tip engagement part 100 Protector 110 Outer protector 112 Outer wall 112 Inner surface 118 Outer surface 119 Gas separation chamber 120 Inner protector 122, 122A Outer wall 125 Inner inlet 126 Outer surface 127 Notch 129 Gas detection chamber 125 Inner inlet 130 Water drop capturing part 131 Groove part 132 Wall part 133 Ridge part 134 Wall part 135 Recessed part 136 dent part 138 Wall part 140 Water drop capturing part 141 Groove part 142 Wall part 143 Ridge part 144 Wall part 145 Water drop Trapping part 146 Ridge part 147 Wall part 148 Recessed part 149 Wall part 150 Groove part 151 Ridge part 160 Discharge port 170 Outer inlet port 180 Inner protector 181 Peripheral wall 182 Inner inlet port 184 Water droplet trapping part 185 Groove part 186 Wall part 187 Inner surface 188 Outer surface 1 0 water droplets capturing unit 191 ridges 192 wall 220 intermediate the protector 222 peripheral wall 225 intermediate inlet 226 outer surface 230 water droplet trapping section 231 groove 232 wall 236 water droplet trapping section 237 ridges 238 wall portion

Claims (6)

A detection element that extends in the axial direction and has a detection part for detecting a specific gas component in the gas to be detected on the tip side;
A metal shell that surrounds and holds the periphery of the detection element in the radial direction in a state where the detection unit protrudes from the tip of the detection unit,
A peripheral wall and a distal end wall on the distal end side thereof, and in a state where the detection portion is accommodated in itself, an opening end portion on the proximal end side is fixed to the distal end portion of the metal shell, and the peripheral wall is A protector that is overlapped with one or a gap in which an introduction port for introducing the gas to be detected is formed;
In the gas sensor with
By processing the surface of the peripheral wall of at least one of the protectors, a water droplet capturing part for capturing water droplets is provided on the surface,
The gas sensor according to claim 1, wherein the water droplet trapping portion is at least one of a groove shape, a ridge shape, a dimple shape, and a protrusion shape. The protector has a peripheral wall and a distal end wall on the distal end side thereof, and the opening end portion on the proximal end side is fixed to the distal end portion of the metal shell in a state in which the detection unit is accommodated therein, An inner protector in which an inner introduction port for introducing the detected gas into itself is formed in the peripheral wall;
A cylindrical shape surrounding at least the peripheral wall of the inner protector is formed with a gap between the inner protector and an outer inlet for introducing the detected gas into the gap is formed on the peripheral wall of the inner protector. Consisting of an outer protector,
The water droplets on the outer surface of the peripheral wall of the inner protector and / or the inner surface and / or outer surface of the outer wall of the outer protector between the gas flow paths formed between the inner inlet and the outer inlet The gas sensor according to claim 1, wherein a capturing part is formed. The protector has a peripheral wall and a distal end wall on the distal end side thereof, and the opening end portion on the proximal end side is fixed to the distal end portion of the metal shell in a state in which the detection unit is accommodated therein, An inner protector in which an inner introduction port for introducing the detected gas into itself is formed in the peripheral wall;
A cylindrical shape surrounding at least the peripheral wall of the inner protector is formed with a gap between the inner protector and an outer inlet for introducing the detected gas into the gap is formed on the peripheral wall of the inner protector. Consisting of an outer protector,
Of the surface of at least one of the outer surface of the peripheral wall of the inner protector and the inner surface of the peripheral wall of the outer protector, trapping at least the water droplets on the surface facing the gap in the region facing the inner inlet or the outer inlet. The gas sensor according to claim 1, wherein a portion is formed.   The gas sensor according to claim 2 or 3, wherein the water droplet capturing part is formed on an outer surface of a peripheral wall of the inner protector.   The gas sensor according to any one of claims 2 to 4, wherein the water droplet capturing part is formed on both an outer surface and an inner surface of a peripheral wall of the outer protector.   The plurality of water droplet capturing parts are provided on the outer surface of the peripheral wall of the inner protector between the gas flow paths and the surface of at least one of the inner wall and outer surface of the outer protector. The gas sensor in any one of thru | or 5.

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