JP4809781B2 - Gas sensor - Google Patents

Description

  The present invention relates to a gas sensor.

  Patent Document 1 discloses a conventional gas sensor. This gas sensor extends in the axial direction, and has a detection element having a detection unit for detecting a specific gas component in the gas to be measured on the tip side, and a detection element inserted inside itself, and the detection unit is exposed to the tip side. Thus, a housing body that holds the detection element and a protector that is fixed to the distal end side of the housing body and covers the detection unit are provided.

  The protector includes a cylindrical inner protector that accommodates the detection unit, and a cylindrical outer protector that is coaxially provided outside the inner protector and accommodates the inner protector in a form in which a tip of the inner protector protrudes. The outer protector has a plurality of outer gas introduction holes through which the gas to be measured can be introduced. The inner protector has a plurality of inner gas introduction holes through which the gas to be measured can be introduced. Is formed.

  The conventional gas sensor having such a configuration is mounted on an automobile or the like, for example, and is mounted in a state where the detection unit is exposed to exhaust gas as a measurement gas discharged from an internal combustion engine. This gas sensor is introduced into the inner space (hereinafter referred to as “inner chamber”) of the inner protector via a gap (hereinafter referred to as “outer chamber”) between the outer protector and the inner protector, and contacts the detection unit. The specific gas component in the gas to be measured can be detected.

  In this gas sensor, the detection element is generally made of ceramic that is brittle against thermal shock, and the gas to be measured is a high-temperature gas. For this reason, when moisture mixed in the gas to be measured adheres to the detection unit, there is a risk of adverse effects such as breakage due to the occurrence of cracks or a decrease in detection performance.

  For this reason, in this gas sensor, it protects so that moisture, such as a water droplet, may not adhere to a detection part with the protector which covers a detection part.

  Further, in this gas sensor, although an inner protector and an outer protector are provided so that moisture such as water droplets does not adhere to the detection unit, moisture such as water drops enter the outer chamber from the outer gas introduction hole of the outer protector, and There is a risk that moisture may remain in the chamber and be difficult to be discharged. Therefore, in the conventional gas sensor, a drain hole for discharging moisture is separately provided in the flange portion of the outer protector formed on the front end side of the outer chamber, thereby preventing moisture from staying in the outer chamber.

JP 2004-109125 A

  By the way, since the request | requirement of size reduction is increasing with respect to the recent protector, the flange part of an outside protector is being similarly reduced in diameter. For this reason, it is becoming difficult to separately provide the discharge hole provided in the flange portion in the downsized outer protector. Therefore, the opening for projecting the inner protector provided in the flange part of the outer protector is made slightly larger than the outer diameter of the inner protector, and the gap with the flange part provided around the inner protector is used instead of the discharge hole. This prevents moisture from staying in the outer chamber.

  However, in the discharge hole using the gap between the flange portion provided around the inner protector, the displacement between the outer protector and the inner protector (specifically, when inserting the inner protector into the outer protector). ) The gap between the inner protector and the outer protector is tilted with respect to the outer protector, or the outer protector and the inner protector are misaligned. May not be provided. Since the gas sensor is usually arranged in the exhaust pipe of an internal combustion engine or the like without considering the directivity, for example, a portion having a narrow gap may be arranged on the upstream side of the exhaust pipe. In such a case, when the gas to be measured sent from the upstream side of the exhaust pipe is introduced into the outer chamber, moisture tends to stay in the portion where the gap between the outer chambers becomes narrow, and as a result, stays. There was a possibility that the water overflowed and entered the inner chamber and adhered to the detection unit, which had an adverse effect.

  The present invention has been made in view of the above-described conventional situation, and provides a gas sensor capable of suitably discharging water staying in the outer chamber and suppressing the water from adversely affecting the detection unit through the inner chamber. It is a problem to be solved.

The gas sensor of the present invention has a detection element that extends in the axial direction and has a detection unit that detects a specific gas component in the gas to be measured on the tip side,
A housing body for holding the detection element so that the detection element is inserted into the inside thereof, and the detection unit is exposed to the distal end side;
A protector that is fixed to the distal end side of the housing body and covers the detection unit;
The protector is a gas sensor including an inner protector that accommodates the detection unit, and an outer protector that is provided outside the inner protector and accommodates the inner protector.
The outer protector has a cylindrical shape, and is formed at an outer cylindrical portion formed with a plurality of outer gas introduction holes capable of introducing the gas to be measured into itself, and at an end of the outer cylindrical portion, A flange portion having an opening in itself,
The inner protector has a cylindrical shape, and is formed at an inner cylindrical portion formed with a plurality of inner gas introduction holes capable of introducing the gas to be measured into itself, and at the tip of the inner cylindrical portion, A lid portion that is substantially in the same position as the opening of the outer protector as viewed in the axial direction or at a position closer to the tip than the opening of the outer protector,
Between the flange portion and the inner protector, a plurality of communication holes that communicate between the outer chamber provided between the inner protector and the outer protector and the outside are formed in a state of being divided in the circumferential direction. It is characterized by.

  In the gas sensor of the present invention having such a configuration, a plurality of communication holes that open the outer chamber to the outside are formed between the flange portion and the inner protector in a state of being divided in the circumferential direction. For this reason, the gap between the flange portion other than the communication hole and the inner protector can be smaller or eliminated than the communication hole, and the arrangement of the outer protector and the inner protector is difficult to shift. On the other hand, the communication hole provided in the gap between the flange portion and the inner protector can sufficiently secure the size of the hole. Therefore, even if it is a gas sensor arrange | positioned without considering directionality in an exhaust pipe, it can prevent that a water | moisture content tends to stay in an outer chamber.

  Further, since this gas sensor uses a gap with the flange portion provided around the inner protector as a discharge hole, even if the protector is downsized and the flange portion of the outer protector is reduced in diameter, moisture remains in the outer chamber. It is surely prevented from staying.

  Therefore, the gas sensor according to the present invention suitably discharges the moisture remaining in the outer chamber, and can suppress the moisture from adversely affecting the detection unit through the inner chamber.

  In addition, if the gap between the flange portion other than the communication hole and the inner protector is made smaller than the communication hole, it is possible to suppress displacement of the arrangement of the outer protector and the inner protector. Furthermore, the displacement between the outer protector and the inner protector can be more effectively suppressed by bringing the flange portion other than the communication hole into contact with the inner protector (that is, by eliminating the gap). In this case, the flange portion and the inner protector may be held in an engaged state, or may be fixed by welding or the like.

  Furthermore, the larger the size of the communication hole, the easier it is to prevent moisture from staying in the outer chamber, but the flange portion of the outer protector is considered to be smaller in diameter and is divided in the circumferential direction of the flange portion. It may be formed in consideration of what to do.

  In the gas sensor of the present invention, it is preferable that the communication holes are formed at equal intervals in the circumferential direction. By doing so, even if the gas sensor is arranged in the exhaust pipe without considering the directionality, it is possible to reliably prevent moisture from being easily retained in the outer chamber.

  By the way, if the diameter of the flange portion of the outer protector is reduced due to the demand for downsizing of the protector, the clearance between the outer chambers is also reduced accordingly. In such a case, if moisture enters the outer chamber, the moisture may stay in the outer chamber which is narrow due to surface tension, and may not be easily discharged. Therefore, in the gas sensor of the present invention, it is preferable that the flange portion is inclined toward the tip side as it goes radially inward.

  In the gas sensor having such a configuration, the gas to be measured that flows around the outer protector abuts against the flange portion to generate a flow that flows toward the tip side, and as a result, the communication hole has a negative pressure. For this reason, the water | moisture content which retains in an outer chamber will be discharged | emitted so that it may be sucked outside from a communicating hole. For this reason, this gas sensor can reliably prevent moisture from staying and becoming difficult to be discharged even in a narrow outer chamber due to downsizing.

In the gas sensor of the present invention, the inner protector has a cylindrical shape, and the opening of the flange portion can be formed in a wave shape. In this case, the flange portion inclines toward the tip end as it goes radially inward, and the lid portion has a tapered portion that inclines toward the tip end as it goes radially inward . peripheral is composed of a protrusion protruding into the recess and the tip side projecting on the rear end side, against axial and valley-shaped surface and a tapered portion connecting the front end of the recess and the outer cylindrical portion of the flange portion It can be inclined at the same angle. Thereby, since the gas to be measured flows more smoothly around the external protector, the inside of the communication hole is more likely to become a negative pressure, and moisture staying in the outer chamber can be reliably discharged.

Further, in the gas sensor of the present invention, the inner peripheral edge of the flange portion is circular, and the outer peripheral edge at the position of the opening of the inner protector can be formed in a wave shape. In this case, the flange portion is inclined toward the distal end as it goes radially inward, and the lid portion has a tapered portion that is inclined toward the distal end as it goes radially inward, and the outer portion at the position of the opening of the inner protector. peripheral edge, the inner cylindrical portion and the concave portion or the tapered portion and the recess, it forms a wavy, the flange portion and the tapered portion may be inclined at the same angle to the axial center. Thereby, since the gas to be measured flows more smoothly around the external protector, the inside of the communication hole is more likely to become a negative pressure, and moisture staying in the outer chamber can be reliably discharged.

  In the gas sensor of the present invention, a through hole that opens the inner chamber to the outside may be formed in the lid portion by partially cutting and bending the center of the lid portion. By this through hole, the water stored in the inner chamber is easily discharged, and the adverse effect of the water on the detection unit can be further prevented. When the center of the lid portion is formed in a circular surface, the center of the lid portion can be partially cut and bent in a fan shape with the through hole as an arc. It is preferable that the number of fans is equiangular.

  Embodiments 1 to 6 embodying the present invention will be described below with reference to the drawings. 1, 3, and 4, the lower side is the front end side and the upper side is the rear end side, but in FIGS. 5 to 16, the lower side is the rear end side, and the upper side is the front end side. is there.

  The gas sensor 1 according to the first embodiment shown in FIGS. 1 to 4 is, for example, an exhaust gas as a measured gas that is mounted on an exhaust pipe of an internal combustion engine and in which a detection unit 11 of a detection element 10 held therein circulates in the exhaust pipe. This is a so-called full-range air-fuel ratio sensor that detects the air-fuel ratio of the exhaust gas from the oxygen concentration of the exhaust gas by being exposed to the air. The gas sensor 1 includes a detection element 10 having a detection unit 11 on the front end side, and a main body as a housing body that holds the detection element 10 so that the detection unit 11 is exposed to the front end side through the detection element 10 inside. A metal fitting 50 and a protector 100 that is fixed to the outer periphery on the front end side of the metal shell 50 and covers the detection unit 11 are provided.

  The detection element 10 has a narrow plate shape extending in the direction of the axis O, a gas detection body for detecting the oxygen gas concentration in the exhaust gas, and a heater for heating to activate the gas detection body at an early stage The body is bonded to each other and integrated as a laminated body having a substantially prismatic shape (in FIG. 1, the left-right direction on the paper surface is shown as the plate thickness direction, and the front-back direction on the paper surface is shown as the plate width direction). The gas detector is composed of a solid electrolyte body mainly composed of zirconia and a detection electrode mainly composed of platinum (both not shown), and the detection electrode is disposed in the detection section 11 on the distal end side of the detection element 10. ing. And in order to protect a detection electrode from poisoning by exhaust gas, the protective layer 15 is formed in the detection part 11 of the detection element 10 so that the outer peripheral surface may be wrapped. Further, five electrode pads 16 (one of which is shown in FIG. 1) are provided on 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 will be 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 metal cup 20 having a bottomed cylindrical shape is inserted slightly into the front end side from the center of the body portion 13 of the detection element 10, and the detection element 11 is opened to the bottom of the cylinder. It is arranged in a state protruding from 25. The metal cup 20 is a member for holding the detection element 10 in the metal shell 50, and the distal end peripheral portion 23 of the edge portion of the cylinder bottom is formed in a tapered shape. In the metal cup 20, an alumina ceramic ring 21 and a talc ring 22 obtained by compressing and solidifying talc powder are housed in a state where they are inserted into the detection element 10. The talc ring 22 is crushed in the metal cup 20 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. The metal shell 50 is for attaching and fixing the gas sensor 1 to an exhaust pipe or the like (not shown) of the internal combustion engine, and is made of low carbon steel such as SUS430. A male threaded portion 51 for mounting and fixing to an exhaust pipe or the like is formed on the outer peripheral distal end side of the metal shell 50, and a distal end engaging portion 56 to be engaged with a protector 100 described later is formed on the distal end side of the male threaded portion 51. ing. Further, a tool engaging portion 52 that engages with a tool for attachment is formed at the center of the outer periphery of the metal shell 50, and between the front end surface of the tool engaging portion 52 and the rear end of the male screw portion 51. Is fitted with a gasket 55 for preventing gas escape when attached to an exhaust pipe or the like. Further, the rear end side of the tool engagement portion 52 is engaged with a rear end engagement portion 57 with which an outer cylinder 30 described later is engaged, and the detection element 10 is caulked and held in the metal shell 50 on the rear end side. For this purpose, a caulking portion 53 is formed.

  Further, a step portion 54 is formed in the vicinity of the male screw portion 51 on the inner peripheral side of the metal shell 50, and the tip peripheral portion 23 of the metal cup 20 that holds the detection element 10 is locked to the step portion 54. Yes. Further, on the inner peripheral side of the metal shell 50, the talc ring 26 is loaded from the rear end side of the metal cup 20 in a state where the talc ring 26 is fitted to the detection element 10, and the cylindrical sleeve 27 detects the detection element. 10, the talc ring 26 is inserted from the rear end side of the talc ring 26 so as to be pressed. 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 caulking packing 29 is disposed on the shoulder portion 28. In this state, the crimping portion 53 of the metal shell 50 is crimped so as to press the shoulder portion 28 of the sleeve 27 toward the distal end side via the crimping packing 29. Then, the talc ring 56 pressed against the sleeve 27 is crushed in the metal shell 50 and filled in the details, and the talc ring 26 and the talc ring 22 preloaded in the metal cup 20 are used for the metal cup 20 and The detection element 10 is positioned and held in the metal shell 50.

  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 is inserted into the inner peripheral side of a cylindrical separator 60 made of insulating ceramics. The separator 60 includes five electrode pads 16 formed on the rear end portion 12 of the detection element 10 and five connection terminals 61 that are electrically connected to each other (one of them is shown in FIG. 1). Are housed inside, and each connection portion of each of the connection terminals 61 and five lead wires 65 (three of which are shown in FIG. 1) drawn out of the gas sensor 1 are accommodated. And protect.

  And the cylindrical outer cylinder 30 is arrange | positioned so that the circumference | surroundings of the separator 60 may be enclosed. The outer cylinder 30 is made of stainless steel (for example, SUS304), and the opening end 31 on its front end side is engaged with the outer periphery of the rear end engaging portion 57 of the metal shell 50. The outer cylinder 30 and the metal shell 50 are integrally joined and fixed by caulking the open end 31 from the outer peripheral side and further performing laser welding that goes around the outer periphery.

  Further, a metal-made cylindrical holding metal fitting 70 is disposed in the gap between the outer cylinder 30 and the separator 60. The holding metal fitting 70 has a support portion 71 formed by bending its rear end inward, and supports a flange portion 62 provided in a hook shape on the outer periphery of the rear end side of the separator 60 inserted into itself. The separator 60 is supported by being engaged with 71. In this state, the outer peripheral surface of the outer cylinder 30 where the holding metal fitting 70 is disposed is crimped, and the holding metal fitting 70 that supports the separator 60 is fixed to the outer cylinder 30.

  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 five insertion holes 76 (one of which is shown in FIG. 1), and the five lead wires 65 drawn from the separator 60 are inserted into each insertion hole 76 in an airtight manner. Has been. In this state, the grommet 75 is crimped from the outer periphery of the outer cylinder 30 while pressing the separator 60 toward the front end side, and is fixed to the rear end of the outer cylinder 30.

  On the other hand, the detection portion 11 of the detection element 10 held by the metal shell 50 is in a state of protruding from the tip end portion (tip engagement portion 56) of the metal shell 50. A protector for protecting the detection portion 11 of the detection element 10 from contamination (degradable deposits such as fuel ash and oil components) in the exhaust gas, breakage due to moisture, etc. 100 is fitted and fixed by spot welding or laser welding. Hereinafter, the protector 100 will be described in more detail with reference to FIGS.

  The protector 100 is provided coaxially on the outer side of the inner protector 120 and the inner protector 120 that accommodates the detection unit 11 in the inner chamber 129 (also referred to as “gas detection chamber”). The outer protector 110 accommodated in the “separation chamber” is formed in a double structure.

  As shown in FIG. 5, the inner protector 120 includes a cylindrical inner cylindrical portion 121, a disk-shaped lid portion 122 formed at the tip of the inner cylindrical portion 121, and a rear end of the inner cylindrical portion 121. And a base end portion 123 formed on the side.

  The outer diameter of the inner cylindrical portion 121 is formed smaller than the distal end engaging portion 56 of the metal shell 50, and the outer diameter of the base end portion 123 is inner cylindrical so as to engage with the outer periphery of the distal end engaging portion 56. The outer diameter of the part 121 is made larger. The inner protector 120 is joined and fixed to the distal end engaging portion 56 of the metal shell 50 by performing laser welding that goes around the outer periphery of the base end portion 123.

  A plurality (four in this embodiment) of inner gas introduction holes 130 are opened along the circumferential direction at a position near the base end portion 123 of the inner cylindrical portion 121. The inner gas introduction hole 130 is an inner part of the exhaust gas introduced into the outer chamber 119 via the outer gas introduction hole 115 of the outer protector 110 described later, mainly for the gas component, and the detection part 11 of the detection element 10 is exposed. It is provided for introduction into the chamber 129.

  Further, a plurality (six in this embodiment) of drain holes 150 are provided in the inner chamber 129 along the circumferential direction at a position near the lid portion 122 of the inner cylindrical portion 121. It is opened so as to push in. A through hole 160 is formed on the outer peripheral side of the lid 122 so as to push a pair of semicircular cuts on the same circumference into the inner chamber 129. The pair of semicircular cuts are bent into the inner chamber 129 as two equiangular fan-shaped sections by being bent. The drain hole 150 and the through hole 160 are provided as a conduit for discharging moisture (water droplets) and the like contained in the exhaust gas introduced into the outer chamber 119 to the outside through the inner chamber 129. Also, the fan-shaped piece constituting the through hole 160 facilitates the drainage of water stored in the inner chamber 129, and water droplets or the like flying from the front end side of the inner protector 120 to the inner chamber 129 along the axis O direction. It is difficult to reach the detection unit 11, and the detection unit 11 can be reliably protected from being exposed to water.

  As shown in FIG. 6, the outer protector 110 is formed on a cylindrical outer cylindrical portion 111, a flange portion 112 formed at the tip of the outer cylindrical portion 111, and a rear end side of the outer cylindrical portion 111. And a base end portion 113.

  The base end 113 is engaged with the outer periphery of the base end 123 of the inner protector 120 so as to be spot welded. Thereby, the outer protector 110 is joined and fixed to the inner protector 120.

  A plurality of (six in the present embodiment) outer gas introduction holes 115 are arranged in the outer chamber 119 in the outer chamber 119 along the circumferential direction at a position near the flange portion 112 of the outer cylindrical portion 111. It is opened so as to push in. A U-shaped notch bent toward the inside of the outer chamber 119 serves as a guide body 116. The outer gas introduction hole 115 is provided to introduce exhaust gas into the outer chamber 119. And the guide body 116 produces the swirling flow which flows so that the outer periphery of the inner side cylindrical part 121 of the inner side protector 120 may be enclosed in the exhaust gas introduce | transduced in the outer chamber 119 through the outer side gas introduction hole 115 from the exterior. It has a function.

  The flange portion 112 is formed so as to be tapered from the tip of the outer cylindrical portion 111, and has an opening 114 at its tip. Then, the flange portion 112 itself is bent into a wave shape so that the inner peripheral edge of the opening 114 undulates. The wavy undulation is 12 periods, and the length of each period is the same.

  As shown in FIGS. 4 and 7, the opening 114 and the lid portion 122 are substantially at the same position when viewed in the axis O direction. Of the inner peripheral edge of the opening 114 that undulates, the recess 114 a that protrudes toward the rear end abuts on the outer periphery of the inner protector 120, and the protrusion 114 b that protrudes toward the front end is separated from the outer periphery of the inner protector 120. is doing. As a result, a plurality (12 in this embodiment) of communication holes 114c that open the outer chamber 119 to the outside are formed at equal intervals between the flange portion 112 and the lid portion 122 in a state of being divided in the circumferential direction. Has been.

  When the gas sensor 1 according to the first embodiment having such a configuration is attached to an exhaust pipe or the like of an internal combustion engine, the tip end side of the male screw portion 51 is exposed in the exhaust pipe. The exhaust gas flowing through the exhaust pipe collides with the protector 100 from at least a direction different from the direction of the axis O (for example, a direction orthogonal to the direction of the axis O), and the outer chamber 119 from the outer gas introduction hole 115 of the outer protector 110. Introduced in. At this time, the exhaust gas is guided in the flow path direction by the guide body 116, and a swirling flow that flows so as to surround the outer periphery of the inner cylindrical portion 121 of the inner protector 120 is generated in the outer chamber 119. The inertial force generated by the swirling flow separates relatively heavy moisture and relatively light gas components contained in the exhaust gas.

  A gas component having a low specific gravity is introduced into the inner chamber 129 from the inner gas introduction hole 130 and comes into contact with the detection unit 11. As a result, the detection unit 11 can detect the oxygen concentration in the exhaust gas.

  On the other hand, moisture having a high specific gravity moves to the front end side in the outer chamber 119, and a part of the moisture is introduced into the inner chamber 129 from the drain hole 150 and discharged to the outside through the through hole 160. Further, the exhaust gas flowing in the exhaust pipe flows along the flange portion 112 of the outer protector 110 and the lid portion 122 of the inner protector 120 (flow in the F direction shown in FIG. 7), so that the concave portion 114 a and the convex portion of the opening 114 are formed. A difference in flow velocity occurs in the vicinity of the portion 114b, and a negative pressure is generated in each communication hole 114c. For this reason, a part of the water moved to the front end side in the outer chamber 119 is discharged to the outside so as to be sucked out by the negative pressure from each communication hole 114c.

  As described above, the gas sensor 1 according to the first embodiment is formed between the flange portion 112 and the inner protector 120 in a state where the plurality of communication holes 114c that open the outer chamber 119 to the outside are divided in the circumferential direction. Yes. For this reason, since the recessed part 114a of the opening 114 is in contact with the outer peripheral edge of the inner protector 120, the arrangement of the outer protector 110 and the inner protector 120 is difficult to shift. On the other hand, the communication hole 114c provided in the gap between the flange portion 114 and the inner protector 120 can sufficiently secure the size of the hole. Therefore, even if it is the gas sensor 1 arrange | positioned without considering directionality in an exhaust pipe, it can prevent that a water | moisture content tends to stay in the outer chamber 119. FIG.

  Further, since the gas sensor 1 uses a gap with the flange portion 112 provided around the inner protector 120 as a discharge hole, even if the flange portion 112 of the outer protector 120 is reduced in diameter, moisture is contained in the outer chamber 119. It is surely prevented from staying.

  Therefore, the gas sensor 1 according to the first embodiment suitably discharges the moisture remaining in the outer chamber 119, and can suppress the moisture from adversely affecting the detection unit 11 via the inner chamber 129.

  In the gas sensor 1 according to the first embodiment, the communication holes 114c are formed at equal intervals in the circumferential direction. Therefore, even in the gas sensor 1 arranged without considering the directionality in the exhaust pipe, the outer chamber 119 is provided. It is possible to reliably prevent moisture from being easily retained.

  Further, in the gas sensor 1 according to the first embodiment, the measured gas flowing around the outer protector 110 of the gas sensor 1 comes into contact with the flange portion 112 because the flange portion 112 is inclined toward the inner side in the radial direction. As a result, a flow that flows toward the tip side is generated, and as a result, the inside of the communication hole 114c becomes negative pressure. For this reason, the moisture staying in the outer chamber 119 is discharged so as to be sucked out from the communication hole 114c. For this reason, the gas sensor 1 can reliably prevent moisture from staying and being difficult to be discharged even in the narrow outer chamber 119 due to downsizing.

  The gas sensor of the second embodiment employs an inner protector 220 in which the lid portion 122 of the inner protector 120 in the gas sensor 1 of the first embodiment is changed to a bowl-shaped lid portion 222 shown in FIGS. These are the same as those of the gas sensor 1 of the first embodiment. Therefore, in Example 2, it demonstrates centering on the cover part 222 of the inner side protector 220, about another structure, the code | symbol same as Example 1 is attached | subjected, and description is simplified or abbreviate | omitted.

  As shown in FIG. 8, the lid portion 222 includes a tapered portion 222a formed at the distal end of the inner cylindrical portion 121 and a disc portion 222b formed at the distal end of the tapered portion 222a.

  The tapered portion 222a and the flange portion 112 (a valley-like surface connecting the concave portion 114a and the tip of the outer cylindrical portion 111) are inclined at the same angle with respect to the axis O.

  On the outer peripheral side of the disk portion 222 b, a through hole 260 is opened so as to push a pair of semicircular cuts on the same circumference into the inner chamber 129. The pair of semicircular cuts are bent into the inner chamber 129 as two equiangular fan-shaped sections by being bent.

  As shown in FIG. 9, a plurality (12 in this embodiment) of communication holes 214c that open the outer chamber 119 to the outside are divided between the flange portion 112 and the tapered portion 222a of the lid portion 222 in the circumferential direction. In this state, they are formed at equal intervals.

Since the gas sensor of the second embodiment having such a configuration is inclined at the same angle with respect to the taper portion 222a and the flange portion 112 axis O, the exhaust gas flows more smoothly around the protector 100. The inside of the hole 214c is more likely to become a negative pressure,
Moisture remaining in the outer chamber can be reliably discharged. In addition, the gas sensor of the second embodiment can achieve the same operational effects as the gas sensor 1 of the first embodiment more reliably.

  As shown in FIGS. 10 and 11, the gas sensor of the third embodiment employs an inner protector 320 in which a plurality of (six in this embodiment) recesses 324a are formed in the inner protector 220 of the gas sensor of the second embodiment. The other configuration is the same as that of the gas sensor of the second embodiment. Therefore, in Example 3, it demonstrates centering around the recessed part 324a of the inner side protector 320, about another structure, the code | symbol same as Example 1, 2 is attached | subjected, and description is simplified or abbreviate | omitted.

  As shown in FIG. 10, each concave portion 324a is provided by forming a semicircular cross-sectional groove from the tip end side of the inner cylindrical portion 121 to the outer peripheral edge of the tapered portion 222a of the lid portion 222. It is formed at equal intervals in the direction.

  As shown in FIG. 11, this gas sensor has six large communication holes 314 c formed by facing each of the concave portions 324 a to six of the twelve convex portions 114 b of the opening 114, and six And a communication hole 214c. For this reason, in this gas sensor, the water staying in the outer chamber 119 is more easily discharged to the outside by the large communication hole 314c.

  The gas sensor according to the third embodiment having such a configuration can also exhibit the same operational effects as the gas sensor 1 according to the first and second embodiments more reliably.

  The gas sensor of the fourth embodiment employs an outer protector 410 in which the flange portion 112 of the outer protector 110 in the gas sensor of the third embodiment is changed to a flange portion 412 having no wavy bending as shown in FIGS. Other configurations are the same as those of the gas sensor of the third embodiment. Therefore, in Example 4, it demonstrates centering on the flange part 412 of the outer side protector 410, about the other structure, the code | symbol same as Examples 1-3 is attached | subjected, and description is abbreviate | omitted or abbreviate | omitted.

  The flange portion 412 has a tapered shape without wavy bending, and the opening 414 of the flange portion 412 also has a simple circular shape. The tapered portion 222a and the flange portion 412 of the inner protector 320 are inclined at the same angle with respect to the axis O.

  As shown in FIG. 13, a plurality (six in this embodiment) of communication holes 414 c that open the outer chamber 119 to the outside are divided between the flange portion 412 and the concave portions 324 a of the lid portion 222 in the circumferential direction. In this state, they are formed at equal intervals.

  The gas sensor of Example 5 having such a configuration can also achieve the same operational effects as the gas sensor 1 of Examples 1 to 3.

  The gas sensor of the fifth embodiment employs an inner protector 520 in which the concave portions 324a of the inner protector 320 in the gas sensor of the fourth embodiment are changed to the concave portions 524a shown in FIGS. 14 and 15, and other configurations are the same as in the embodiment. This is the same as the gas sensor 4. Therefore, in Example 5, it demonstrates centering around the recessed part 524a of the inner side protector 520, about another structure, the code | symbol same as Examples 1-4 is attached | subjected, and description is simplified or abbreviate | omitted.

  As shown in FIG. 14, each recess 524 a is provided by forming a groove having a short semicircular cross section in the tapered portion 222 a of the lid portion 222, and is formed at equal intervals in the circumferential direction.

  As shown in FIG. 15, a plurality (six in this embodiment) of communication holes 514 c that open the outer chamber 119 to the outside are divided between the flange portion 412 and the concave portions 524 a of the lid portion 222 in the circumferential direction. In this state, they are formed at equal intervals.

  The gas sensor according to the fifth embodiment having such a configuration can achieve the same effects as the gas sensor 1 according to the first to fourth embodiments.

  The gas sensor according to the sixth embodiment employs an outer protector 610 in which the flange portion 412 of the outer protector 410 in the gas sensor according to the fourth embodiment is changed to the flange portion 612 illustrated in FIG. 16. It is the same as the gas sensor. Therefore, in Example 6, it demonstrates centering on the flange part 612 of the outer side protector 610, about another structure, the code | symbol same as Examples 1-4 is attached | subjected, and description is abbreviate | omitted or abbreviate | omitted.

  As shown in FIG. 16, the flange portion 612 is not subjected to a wave-like bending process, and the opening 614 of the flange portion 612 is also a simple circular shape. The flange portion 612 is not tapered but has a shape extending in a radial direction substantially perpendicular to the axis O.

  Between the flange portion 612 and the concave portions 324a of the lid portion 222, a plurality (six in this embodiment) of communication holes 614c that open the outer chamber 119 to the outside are equally spaced in a state where they are divided in the circumferential direction. Is formed.

  The gas sensor of Example 6 having such a configuration can also achieve the same operational effects as the gas sensor 1 of Examples 1 to 5.

  In the above, the present invention has been described with reference to the first to sixth embodiments. However, the present invention is not limited to the first to sixth embodiments, and can be appropriately modified and applied without departing from the spirit of the present invention. Needless to say.

  The present invention can be used for a gas sensor.

1 is a partial cross-sectional view of a gas sensor of Example 1. FIG. FIG. 2 is a front view of the gas sensor according to the first embodiment viewed from the direction of arrow II in FIG. 1. FIG. 3 is an enlarged cross-sectional view of the gas sensor of Example 1 (showing the III-III cross section of FIG. 2). FIG. 4 is an enlarged cross-sectional view (showing a cross section IV-IV in FIG. 2) of the gas sensor according to the first embodiment. It is a perspective view which shows the inner side protector concerning the gas sensor of Example 1. FIG. It is a perspective view which shows the outer side protector concerning the gas sensor of Example 1. FIG. It is a perspective view which concerns on the gas sensor of Example 1 and shows the front end side of a protector. It is a perspective view which shows the inner side protector regarding the gas sensor of Example 2. FIG. It is a perspective view which shows the front end side of a protector concerning the gas sensor of Example 2. FIG. It is a perspective view which shows the inner side protector regarding the gas sensor of Example 3. FIG. It is a perspective view which shows the front end side of a protector concerning the gas sensor of Example 3. FIG. It is a perspective view which shows the outer side protector regarding the gas sensor of Example 4. FIG. It is a perspective view which shows the front end side of a protector concerning the gas sensor of Example 4. FIG. It is a perspective view which shows the inner side protector regarding the gas sensor of Example 5. FIG. It is a perspective view which concerns on the gas sensor of Example 5 and shows the front end side of a protector. It is a perspective view which concerns on the gas sensor of Example 6 and shows the front end side of a protector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Gas sensor 10 ... Detection element 11 ... Detection part 50 ... Housing main body (main metal fitting)
DESCRIPTION OF SYMBOLS 100 ... Protector 110, 410, 610 ... Outer protector 111 ... Outer cylindrical part 112, 412, 612 ... Flange part 114, 414, 614 ... Opening 114c, 214c, 314c, 414c, 514c, 614c ... Communication hole 115 ... Outer Gas introduction hole 119 ... Outer chamber 120, 220, 320, 520 ... Inner protector 121 ... Inner cylindrical portion 122, 222 ... Lid portion 129 ... Inner chamber 130 ... Inner gas introduction hole O ... Axis

Claims (7)

A detection element that extends in the axial direction and has a detection unit that detects a specific gas component in the gas to be measured on the tip side;
A housing body for holding the detection element so that the detection element is inserted into the inside thereof, and the detection unit is exposed to the distal end side;
A protector that is fixed to the distal end side of the housing body and covers the detection unit;
The protector is a gas sensor including an inner protector that accommodates the detection unit, and an outer protector that is provided outside the inner protector and accommodates the inner protector.
The outer protector has a cylindrical shape, and is formed at an outer cylindrical portion formed with a plurality of outer gas introduction holes capable of introducing the gas to be measured into itself, and at an end of the outer cylindrical portion, A flange portion having an opening in itself,
The inner protector has a cylindrical shape, and is formed at an inner cylindrical portion formed with a plurality of inner gas introduction holes capable of introducing the gas to be measured into itself, and at the tip of the inner cylindrical portion, A lid portion that is substantially in the same position as the opening of the outer protector as viewed in the axial direction or at a position closer to the tip than the opening of the outer protector,
Between the flange portion and the inner protector, a plurality of communication holes that communicate between the outer chamber provided between the inner protector and the outer protector and the outside are formed in a state of being divided in the circumferential direction. Gas sensor characterized by having   The gas sensor according to claim 1, wherein the communication holes are formed at equal intervals in the circumferential direction.   The gas sensor according to claim 1, wherein the flange portion is inclined toward the distal end side as it goes radially inward.   The gas sensor according to any one of claims 1 to 3, wherein the inner protector has a cylindrical shape, and the opening of the flange portion is formed in a wave shape. The flange portion is inclined to the tip side as it goes radially inward,
The lid portion has a tapered portion that is inclined toward the distal end side toward the radially inner side,
The inner peripheral edge of the opening formed in a wavy shape is composed of a concave portion protruding to the rear end side and a convex portion protruding to the front end side,
The sensor of claim 4 wherein the inclined at the same angle to the axial center and the valley-shaped surface wherein the tapered portion connecting the front end of the recess and the outer cylindrical portion of the flange portion.   The gas sensor according to any one of claims 1 to 3, wherein an inner peripheral edge of the flange portion is circular, and an outer peripheral edge at the position of the opening of the inner protector is formed in a wave shape. The flange portion is inclined to the tip side as it goes radially inward,
The lid portion has a tapered portion that is inclined toward the distal end side toward the radially inner side,
The outer peripheral edge at the position of the opening of the inner protector is formed of a wave shape by the inner cylindrical portion and the concave portion, or by the tapered portion and the concave portion,
The flange portion and the gas sensor according to claim 6 wherein the inclined at the same angle to the axial center and the tapered portion.

Images