JP2010190756A - Gas sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas sensor capable of reliably protecting a filter member provided on an air communication hole to expose the reference electrode of a detection element by introducing an atmosphere with a simple construction. <P>SOLUTION: The filter member 87 with permeability and a waterproofing property is arranged in the air communication hole 91 provided on a grommet 9 located on a rear end 38 in an outer cylinder 3. A ventilation section 34 provided to protect this filter member 87 and secure the permeability is connected to the end (open end 32) of the sidewall 39 of the outer cylinder 3 to surround the grommet 9 by an arm 33. The arm 33 is located in the groove 93 of the grommet 9, and thus the grommet 9 is positioned to the outer cylinder 3. Accordingly, the ventilation section 34 constructed integrally with the outer cylinder 3 is never misaligned, inclined, and twisted to air communication hole 91. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a gas sensor having a ventilation structure for exposing a reference electrode of a detection element for detecting a gas to be detected to the atmosphere.

  2. Description of the Related Art Conventionally, a gas sensor using a solid electrolyte body made of a ceramic such as zirconia and having a detection element for detecting a specific gas component (for example, oxygen) in exhaust gas discharged from an internal combustion engine is known. For example, a detection element of an oxygen sensor that detects oxygen is a pair of a detection electrode that is exposed to exhaust gas and a reference electrode that is exposed to a reference gas (usually the atmosphere), and sandwiches the solid electrolyte body. Thus, it has the structure formed on the surface of the solid electrolyte body. This detection element is based on an electromotive force generated between two electrodes according to a difference in oxygen partial pressure between two atmospheres separated by a solid electrolyte body, that is, between an exhaust gas and a reference gas (atmosphere). It detects oxygen in the exhaust gas.

  The detection element is held by the metal shell, and when the metal shell is attached to the exhaust pipe of the internal combustion engine, the detection electrode (detection unit) provided on the front end side of the detection element is in the exhaust gas flowing through the exhaust pipe. Be exposed. On the other hand, the rear end side of the detection element is exposed from the metal shell and is surrounded by an outer cylinder joined to the metal shell, and the reference electrode of the detection element is in contact with the atmosphere in the outer cylinder. The atmosphere inside the outer cylinder and the atmosphere around the detection electrode are separated by a metal shell. Further, a lead wire for taking out a detection signal of the detection element is drawn out of the outer cylinder, and a plug member for closing the lead-out port is assembled to the lead-out port of the lead wire. In addition to the lead wire insertion hole for inserting the lead wires (sensor output lead wire and heater lead wire), the plug member (grommet) ensures air permeability between the inside and the outside of the outer cylinder and the reference electrode An air communication hole (through hole) for introducing air to the side is provided. The air communication hole is provided with a filter member for preventing water droplets or the like from entering while introducing air into the outer cylinder (see, for example, Patent Document 1).

JP 2006-208165 A

  However, in the oxygen sensor of Patent Document 1, the filter member is directly exposed to the outside. Usually, since an oxygen sensor is disposed near the road surface of an automobile, the filter member may directly receive an impact from the outside due to a contact with a plant or a collision with a flying stone or the like, which may cause damage to the filter member. Therefore, in order to protect the filter member, a protective member for protecting the filter member may be provided so as to cover the air communication hole on the rear end side with respect to the filter member. The lead wire is also drawn out, and it is necessary to provide a protective member without damaging the lead wire. Furthermore, considering the ease of assembly in the manufacturing process of the oxygen sensor, it is desirable that the protective member having a structure that is not in contact with the lead wire is assembled to the outer cylinder in the final process of the manufacturing process. However, there is a possibility that the protective member cannot reliably protect the filter member because the protective member is assembled to the outer cylinder in a tilted manner or the protective outer cylinder is wobbled after assembly.

  The present invention has been made to solve the above problems, and reliably protects the filter member provided in the air communication hole for introducing the atmosphere and exposing the reference electrode of the detection element to the atmosphere with a simple configuration. It is characterized by providing a gas sensor capable of performing the above.

  The gas sensor according to the first aspect of the present invention extends in the axial direction and includes a detection element having a detection unit for detecting a gas to be detected on its tip side, and the detection unit protruding from its tip, A metal shell that surrounds the periphery of the detection element in the radial direction; a cylindrical shape that surrounds the periphery of the detection element in the radial direction on the rear end side; and an outer cylinder whose front end is fixed to the metal shell; A plug member disposed on the rear end side of the plug, with a lead wire insertion hole through which a lead wire for taking out a detection signal of the detection element is inserted, and a filter member having air permeability and waterproofness interposed And a plug member formed so that atmospheric communication holes that enable atmospheric communication between the inside and the outside of the outer cylinder extend in the axial direction, respectively. Surrounding side And a ventilation portion that is disposed on the rear side of the plug member, covers the atmosphere communication hole of the plug member, and has an opening that is at least smaller than the opening of the atmosphere communication hole, and extends in the radial direction, It has a plate-shaped arm part which connects a side part and the ventilation part, It is characterized by the above-mentioned.

  In the gas sensor according to the first aspect, since the ventilation portion provided in the outer cylinder covers the atmosphere communication hole of the plug member, the filter member disposed (intervened) in the atmosphere communication hole is prevented from being exposed to the outside. The filter member can be protected from an external impact caused by contact or collision of flying stones. The air permeability between the outside and the atmosphere communication hole can be ensured by the opening provided in the ventilation portion. In addition, by using a plate-like arm portion as a connection structure between the ventilation portion and the side surface portion, the arm portion and the lead wire can be separated, and interference between the arm portion and the lead portion can be prevented.

  By the way, the side part of the outer cylinder surrounding the periphery of the plug member and the ventilation part are connected by an arm part. In other words, the arm part and the ventilation part are integrated with the outer cylinder, that is, configured as a part of the outer cylinder. Therefore, in the process of manufacturing the gas sensor, the arm part and the ventilation part are simply fixed to the metal shell. Can also be fixed to the metal shell. Therefore, when the outer cylinder and the ventilation part are separate bodies, the ventilation part is not tilted and assembled to the outer cylinder, and the ventilation part does not wobble after the assembly, and the ventilation part can reliably protect the filter member.

  In addition, a two-step process is required to fix the outer cylinder to the metal shell and then fix the arm part and ventilation part to the outer cylinder, but this process can be completed in one step, reducing man-hours. it can. Furthermore, if the outer cylinder, the arm part, and the ventilation part are made up of a single part, it is not necessary to provide a structure for fixing them to each other, not only reducing the number of parts, but also simplifying the structure. Can do.

  Further, in the gas sensor according to the first aspect, the plug member has a groove portion extending radially outward from the air communication hole as a starting point, avoiding the lead wire insertion hole, on the rear end facing surface side thereof. In this case, the arm part may be disposed in the groove part. Thus, if an arm part is arrange | positioned in the groove part provided avoiding the lead wire penetration hole, interference with an arm part and a lead wire can be avoided reliably. Further, since the arm portion and the groove portion are positioned with respect to each other, the plug member is prevented from rotating in the circumferential direction with respect to the outer cylinder, and therefore, the contact between the lead wire and the arm portion can be prevented. Furthermore, the lead wire does not come into contact with the ventilation portion and the outer cylinder integral with the arm portion, and the lead wire can be reliably protected from damage due to contact with other members.

  In the gas sensor according to the first aspect, the outer cylinder may include at least two or more of the arm portions, and the plug member may include at least two or more of the groove portions. Each of these may be disposed in the groove. Since the plurality of arm portions are respectively disposed in the groove portion, even when a twist with one arm portion as the central axis is added to the ventilation portion, the two arm portions abut against the groove portion to suppress the twist. It is possible to prevent the occurrence of inclination and displacement in the arrangement of the ventilation portion with respect to the hole.

  Further, in the gas sensor according to the first aspect, the vent has a form having a plurality of holes penetrating in the axial direction, a form in which a mesh-like member is assembled in the opening in the axial direction, or a convex part formed on itself. It may be formed in any one of the forms having openings on the side surfaces. It is desired that the ventilation portion has a structure capable of sufficiently maintaining the air permeability between the inside and the outside of the outer cylinder while covering and protecting the filter member from the outside. If a plurality of holes penetrating in the axial direction are provided in the ventilation portion, the filter member can be protected and the air permeability can be secured with a simple structure. Similarly, the filter member can be protected and the air permeability can be ensured even when the mesh member is assembled to the ventilation portion or the opening is formed on the side surface of the convex portion provided in the ventilation portion to allow ventilation. Can be performed with a simple structure.

  The gas sensor according to the second aspect of the present invention extends in the axial direction, and has a detection element having a detection unit for detecting a gas to be detected on its tip side, and the detection unit protruding from its tip, A metal shell that surrounds the periphery of the detection element in the radial direction; a cylindrical shape that surrounds the periphery of the detection element in the radial direction on the rear end side; and an outer cylinder whose front end is fixed to the metal shell; A plug member disposed on the rear end side of the plug, with a lead wire insertion hole through which a lead wire for taking out a detection signal of the detection element is inserted, and a filter member having air permeability and waterproofness interposed A gas sensor comprising an atmosphere communication hole that allows atmospheric communication between the inside and the outside of the outer cylinder, each extending so as to extend in the axial direction. Surrounding side And a cover that covers the filter member so that the filter member is not visible when the gas sensor is viewed in the axial direction from the rear side, and is connected to the atmosphere via a gap between itself and the plug member. It has a covering portion that allows ventilation between the inside and outside of the hole, and a plate-like arm portion that extends in the radial direction and connects the side surface portion and the covering portion.

  In the gas sensor according to the second aspect, since the covering portion provided on the outer cylinder covers the atmosphere communication hole of the plug member, the filter member disposed (intervened) in the atmosphere communication hole is prevented from being exposed to the outside, The filter member can be protected from an external impact caused by contact or collision of flying stones. The air permeability between the outside and the atmosphere communication hole can be ensured by the gap between the covering portion and the plug member. In addition, by using a plate-like arm portion as a connection structure between the ventilation portion and the side surface portion, the arm portion and the lead wire can be separated, and interference between the arm portion and the lead portion can be prevented.

  By the way, the side part of the outer cylinder surrounding the periphery of the plug member and the covering part are connected by an arm part. In other words, the arm part and the covering part are integrated with the outer cylinder, that is, as a part of the outer cylinder. Therefore, in the process of manufacturing the gas sensor, the arm part and the covering part are simply fixed to the metal shell. Can also be fixed to the metal shell. Therefore, when the outer cylinder and the ventilation part are separate bodies, the ventilation part is not tilted and assembled to the outer cylinder, and the ventilation part does not wobble after the assembly, and the ventilation part can reliably protect the filter member. .

  Furthermore, a two-step process is required to fix the outer cylinder to the metal shell and then fix the arm part and the covering part to the outer cylinder, but since this process can be completed in one step, man-hours can be reduced. it can. Furthermore, if the outer cylinder, the arm part, and the covering part are made of a single part, it is not necessary to provide a structure for fixing them to each other, not only reducing the number of parts, but also simplifying the structure. Can do.

  The gas sensor which concerns on a 2nd aspect WHEREIN: Even if the said plug member has the groove part extended toward the radial direction outer side from the said air | atmosphere communicating hole on the side facing the rear end of itself, avoiding the said lead wire penetration hole In this case, at least one of the arm portions may be disposed in the groove portion. Thus, if an arm part is arrange | positioned in the groove part provided avoiding the lead wire penetration hole, interference with an arm part and a lead wire can be avoided reliably. Further, since the arm portion and the groove portion are positioned with respect to each other, the plug member is prevented from rotating in the circumferential direction with respect to the outer cylinder, and therefore, the contact between the lead wire and the arm portion can be prevented. Further, the lead wire does not come into contact with the covering portion and the outer cylinder integral with the arm portion, and the lead wire can be reliably protected from damage due to contact with other members.

  In the gas sensor according to the second aspect, the outer cylinder may include at least two arm portions, and the plug member may include at least two groove portions. In this case, the arm Each of the portions may be disposed in the groove portion. Since the plurality of arm portions are respectively disposed in the groove portion, even when a twist with one arm portion as the central axis is applied to the covering portion, the two arm portions abut against the groove portion to suppress the torsion. In the arrangement of the covering portion with respect to the hole, it is possible to prevent the occurrence of inclination, displacement, twisting and the like.

It is a longitudinal cross-sectional view which shows the structure of the gas sensor 1 of 1st Embodiment. It is a perspective view of the grommet 9 before an assembly | attachment. It is the figure which looked at the gas sensor 1 from the axis line O direction rear end side (upper side in FIG. 1). It is a perspective view of the outer cylinder 3 before an assembly | attachment. It is a figure which shows an example of the process in which the partial goods of the rear end side of a gas sensor are manufactured. It is a perspective view which shows the shape of the rear-end part of the outer cylinder 110 as a modification. It is a perspective view which shows the shape of the rear-end part of the outer cylinder 120 as a modification. It is a perspective view which shows the shape of the rear-end part of the outer cylinder 130 as a modification. It is a perspective view which shows the shape of the rear-end part of the outer cylinder 140 as a modification. It is a longitudinal cross-sectional view which shows the structure of the gas sensor 201 of 2nd Embodiment. It is the figure which looked at the gas sensor 201 from the axis line O direction rear end side (upper side in FIG. 10).

  Hereinafter, an embodiment of a gas sensor embodying the present invention will be described with reference to the drawings. First, as a first embodiment, the structure of a gas sensor 1 will be described with reference to FIGS. 1 is used by being attached to an exhaust pipe (not shown) of exhaust gas discharged from an engine of an internal combustion engine such as an automobile. In the following, in the direction of the axis O of the gas sensor 1, the side toward the tip of the detection element 6 inserted into the exhaust pipe (the closed side and the lower side in the figure) is the tip side, and the side in the opposite direction ( The upper side in the figure will be described as the rear end side.

  A gas sensor 1 shown in FIG. 1 is a sensor for detecting the presence or absence of oxygen in exhaust gas flowing through an exhaust pipe, and a cylindrical detection element 6 having a long and closed end is connected to a metal shell 5 and an outer cylinder 3. And a structure held in the protector 4. A lead wire 18 is drawn out from the gas sensor 1 for taking out a signal output from the detection element 6 and energizing the heater 7 provided in the detection element 6. Each lead wire 18 is electrically connected to a sensor control device (not shown) provided at a position away from the gas sensor 1 or an electronic control device (ECU) of an automobile.

  The detection element 6 of the gas sensor 1 is configured by using a solid electrolyte body 61 mainly composed of zirconia formed in a bottomed cylindrical shape extending in the direction of the axis O as a base. On the inner surface of the solid electrolyte body 61, a reference electrode 62 made of Pt or a Pt alloy is formed in a porous shape so as to cover almost the entire surface thereof. Similarly to the reference electrode 62, the detection electrode 63 made of Pt or a Pt alloy is formed on the outer surface of the solid electrolyte body 61 in a porous shape. The front end side (closed side) of the detection element 6 is configured as a detection unit 64, and the detection electrode 63 on the outer surface is exposed to the exhaust gas flowing in the exhaust pipe (not shown). Although not shown, the detection electrode 63 is covered with a porous electrode protection layer made of heat-resistant ceramic, and is protected from poisoning by exhaust gas. In addition, a flange-like flange portion 65 protruding outward in the radial direction is provided at a substantially intermediate position in the axis O direction of the detection element 6. A rod-shaped heater 7 for heating and activating the solid electrolyte body 61 is inserted into the bottomed cylinder of the detection element 6.

  The detection element 6 is held in the cylindrical hole 55 of the metal shell 5 in a state where the circumference of the detection element 6 is surrounded by the cylindrical metal shell 5. The metal shell 5 is a cylindrical member made of stainless steel such as SUS430, and a male threaded portion 52 that is screwed into a mounting portion (not shown) of the exhaust pipe is formed on the distal end side. A distal end engaging portion 56 is formed on the outer periphery of the male screw portion 52 to engage a protector 4 described later on the outer periphery thereof. The detection portion 64 of the detection element 6 protrudes further toward the distal end side than the distal end engaging portion 56.

  A tool engaging portion 53 having a radially increased diameter is formed on the rear end side of the male screw portion 52 of the metal shell 5 and is used when the gas sensor 1 is attached to an attachment portion (not shown) of the exhaust pipe. An installation tool is engaged. An annular gasket 11 is inserted into a portion between the tool engaging portion 53 and the male screw portion 52 to prevent gas from being released through the attachment portion of the exhaust pipe. A caulking portion 57 for caulking and fixing the detection element 6 held in its cylindrical hole 55 is provided on the rear end side of the metal shell 5. The rear end portion 66 of the detection element 6 protrudes toward the rear end side from the caulking portion 57. And between the tool engaging part 53 and the crimping part 57, the rear-end engaging part 58 with which the front-end | tip part 31 of the outer cylinder 3 mentioned later is engaged is formed in the outer periphery.

  Next, a step portion 59 is provided on the front end side in the cylindrical hole 55 of the metal shell 5 so that the inner periphery thereof protrudes radially inward, and the metal packing 12 is attached to the step portion 59. A cylindrical support member 13 made of alumina is engaged therewith. The inner periphery of the support member 13 is also formed in a step shape, and the flange portion 65 of the detection element 6 is supported by the support member 13 through a metal packing 14 disposed in the stepped portion. Further, the cylindrical hole 55 is filled with a filler member 15 made of talc powder on the rear end side of the support member 13, and the rear end side of the filler member 15 is sandwiched between the filler member 15 and the support member 13. A tubular sleeve 16 made of alumina is disposed on the surface.

  An annular ring 17 is disposed on the rear end side of the sleeve 16, and the sleeve 16 is connected to the filling member 15 via the ring 17 by caulking the caulking portion 57 of the metal shell 5 toward the inner distal end. It is pressed. Through the caulking of the caulking portion 57, the filling member 15 presses the flange portion 65 of the detecting element 6 toward the support member 13 locked to the stepped portion 59 of the metal shell 5, so that the cylindrical hole of the metal shell 5 is pressed. In addition to being compressed and filled in 55, the gap between the inner peripheral surface of the cylindrical hole 55 and the outer peripheral surface of the detection element 6 is filled in an airtight manner. As described above, the detection element 6 is held in the cylindrical hole 55 of the metal shell 5 through the members sandwiched between the crimping portion 57 and the step portion 59 of the metal shell 5.

  Next, the protector 4 that covers the detection portion 64 of the detection element 6 protruding from the front end engagement portion 56 toward the front end side in the axis O direction is assembled to the front end engagement portion 56 of the metal shell 5 by welding. ing. The protector 4 protects the detection portion 64 of the detection element 6 that protrudes into the exhaust pipe when the gas sensor 1 is attached to the exhaust pipe (not shown) from collision of water droplets or foreign matters contained in the exhaust gas. It is. The protector 4 has a bottomed cylindrical shape and an outer protector 41 whose peripheral edge on the opened side is joined to the tip engaging portion 56, and a bottomed cylindrical inner protector 45 fixed inside the outer protector 41. It is comprised so that the double structure which consists of these may be made. On the outer peripheral surfaces of the outer protector 41 and the inner protector 45, there are respectively introduced inlets 42 for introducing exhaust gas into the interior and guiding them to the detection part 64 of the detection element 6 (the gas inlets of the inner protector 45 are Not shown). In addition, on the bottom surfaces of the outer protector 41 and the inner protector 45, discharge ports 43 and 48 for discharging water droplets and exhaust gas that have entered the inside are opened.

  Further, as described above, the rear end portion 66 of the detection element 6 protrudes rearward from the rear end (caulking portion 57) of the metal shell 5. A cylindrical separator 8 made of an insulating ceramic is disposed on the rear end side in the axis O direction from the rear end portion 66. The separator 8 has an accommodating portion 82 that independently accommodates four connection terminals 19 (three of which are shown in FIG. 1). The accommodating portion 82 penetrates the separator 8 in the direction of the axis O, and is configured to be able to vent between the front end side and the rear end side with respect to the separator 8. Each connection terminal 19 has a pair of electrodes 71 (one of which is shown in FIG. 1) exposed on the rear end side to energize the reference electrode 62, the detection electrode 63, and the heating resistor of the heater 7. Electrode 71 is shown)) and is electrically connected to each other. The separator 8 accommodates the connection terminals 19 in a separated state to prevent contact between the connection terminals 19. Core wires of four lead wires 18 are caulked and joined to each connection terminal 19 (two lead wires 18 are shown in FIG. 1), and each lead wire 18 is a grommet described later. 9 is pulled out to the outside of the gas sensor 1. Further, a flange portion 81 protruding radially outward is provided on the outer peripheral surface of the separator 8, and a substantially cylindrical holding metal fitting 85 is fitted on the outer peripheral surface on the tip side of the flange portion 81. Yes.

  A grommet 9 made of fluorine rubber is disposed on the rear end side of the separator 8. As shown in FIG. 2, the grommet 9 is a member formed in a substantially cylindrical shape with the axis O direction as the height direction, and includes an air communication hole 91 and four lead wire insertion holes 92 penetrating in the axis O direction. Have. The air communication hole 91 is formed at the center in the radial direction of the grommet 9, and the lead wire insertion holes 92 are equally spaced in the circumferential direction so as to surround the air communication hole 91 on the outer peripheral side of the air communication hole 91. Are formed respectively. As shown in FIG. 1, the atmosphere communication hole 91 is provided for introducing the atmosphere into the gas sensor 1 (in an outer cylinder 3 described later) via the accommodating portion 82 of the separator 8. In the outer cylinder 3, the detection element 6 is held by the metal shell 5 in a form in which the rear end portion 66 is projected, but the reference electrode 62 formed in the bottomed cylinder of the detection element 6 is in the atmosphere. It is configured to be exposed. As shown in FIG. 3, the four lead wires 18 described above are inserted into the four lead wire insertion holes 92 independently of each other.

  As shown in FIGS. 2 and 3, the top surface 99 facing the rear end when the grommet 9 is assembled to the gas sensor 1 starts from the formation position of the air communication hole 91 toward the outer peripheral side. Four groove portions 93 extending in a groove shape along the radial direction are formed. Each groove portion 93 is disposed between two adjacent lead wire insertion holes 92 so as to avoid the positions of the four lead wire insertion holes 92 opened on the top surface 99. Therefore, the top surface 99 is divided into four sections by the groove 93.

  As shown in FIG. 1, a filter member 87 and a fastener 88 are inserted into the atmosphere communication hole 91 of the grommet 9. The filter member 87 is a thin-film filter having a micron-sized network structure made of a fluororesin such as PTFE (polytetrafluoroethylene), and is configured to allow air to communicate without passing water droplets. is there. The clasp 88 is a member formed in a cylindrical shape, and a filter member 87 is sandwiched between the outer periphery of itself and the inner periphery of the air communication hole 91 and fixed to the grommet 9. The groove part 93 of the grommet 9 described above forms a flow path that leads to the outer peripheral side so that water droplets or the like that could not pass through the filter member 87 do not accumulate on the filter member 87. In addition, the groove part 93 may have an inclination which goes to the rear end side from the front end side in the axis O direction as it goes from the radially outer side to the central side.

  Next, a cylindrical outer cylinder 3 extending in the direction of the axis O is assembled to the rear end side of the metal shell 5. As shown in FIG. 4, the outer cylinder 3 is formed of stainless steel such as SUS304 in a cylindrical shape extending along the direction of the axis O, and further, a distal end portion 31 positioned on the distal end side (lower side in FIG. 4) from the approximate center. Is formed in a large diameter. The inner diameter of the distal end portion 31 is formed larger than the outer diameter of the rear end engaging portion 58 in order to engage the distal end portion 31 with the rear end engaging portion 58 (see FIG. 1) of the metal shell 5. As shown in FIGS. 3 and 4, the rear end (opening end 32) of the rear end portion 38 located on the rear end side of the outer cylinder 3 is bent inward in the radial direction. Four arm portions 33 having a plate shape extending toward the axis O are projected from four directions. In the present embodiment, each of the four arm portions 33 has an inclination that goes from the front end side to the rear end side in the axis O direction as it goes from the radially outer side to the central side.

  Each arm 33 is connected to the outer periphery of a circular plate-shaped vent 34. The ventilation portion 34 has an outer diameter that is substantially the same size as the atmosphere communication hole 91 of the grommet 9 shown in FIG. 2, and the thickness direction is aligned with the axis O direction as shown in FIGS. The arm portion 33 supports the hole 91 so that the hole 91 is covered. Further, as shown in FIG. 4, the ventilation portion 34 is provided with an opening 35 penetrating in the thickness direction. The opening 35 is formed smaller than the opening (size) of the air communication hole 91 (see FIG. 1), and entry of flying stones or the like into the air communication hole 91 through the opening 35 is prevented. . Further, the ventilation portion 34 is provided with a cover 36 that rises from the edge of the opening 35 in the thickness direction of the ventilation portion 34 and covers the opening 35, and prevents entry of stepping stone or the like from the rear end side in the axis O direction. Is done. Further, by forming the opening 37 that opens a part of the side surface of the cover 36, the ventilation between the outside and the atmosphere communication hole 91 (that is, the ventilation between the inside and the outside of the outer cylinder 3) is ensured through the opening 35. Has been. The ventilation portion 34 is provided to protect the filter member 87 disposed in the air communication hole 91 from external impacts such as contact with plants and collisions with flying stones, and to prevent damage.

  As shown in FIG. 1, the outer cylinder 3 having such a structure surrounds each side surface of the rear end portion 66 of the detection element 6, the separator 8, and the grommet 9 arranged in the direction of the axis O in the circumferential direction. In this state, it is arranged on the rear end side of the metal shell 5. The front end portion 31 of the outer cylinder 3 is fitted on the outer periphery of the rear end engaging portion 58 of the metal shell 5 and is crimped radially inward from the outer peripheral side. Further, the outer tube 3 is fixed to the metal shell 5 by performing laser welding around the outer periphery of the tip 31.

  Further, the side surface of the outer cylinder 3 corresponding to the position of the front end side of the flange portion 81 of the separator 8 is crimped radially inward around the outer periphery. A holding metal fitting 85 is disposed at this position, and the holding metal fitting 85 is caulked and held in the outer cylinder 3 in a state where the separator 8 is held inside itself. The side surface of the outer cylinder 3 corresponding to the position of the rear end side of the flange portion 81 of the separator 8 is also crimped radially inward at a plurality of locations in the circumferential direction. The caulking of this portion is performed at a position in contact with the rear end of the flange portion 81. The flange portion 81 is sandwiched between the caulking portion and the holding metal fitting 85, and movement of the separator 8 in the direction of the axis O is restricted. Yes.

  As shown in FIG. 1, the grommet 9 disposed on the rear end side of the separator 8 is disposed in the rear end portion 38 of the outer cylinder 3. The top surface 99 of the grommet 9 divided into four sections passes through the four arm portions 33 and protrudes from the outer cylinder 3 to the rear end side, and the arm portion 33 is disposed in the groove portion 93. That is, the grommet 9 is sandwiched between the arm portion 33 and the separator 8 in the outer cylinder 3, and movement in the axis O direction is restricted. Further, the side wall 39 of the outer cylinder 3 surrounding the outer periphery of the grommet 9 disposed in the rear end portion 38 of the outer cylinder 3 is caulked inward in the radial direction from the outer peripheral side, and the grommet 9 extends in the radial direction. Movement is also restricted. Further, as shown in FIG. 3, the arm portion 33 of the outer cylinder 3 is disposed in the groove portion 93 of the grommet 9, so that the rotation of the grommet 9 around the axis O in the circumferential direction is also restricted. Thus, the four lead wires 18 inserted through the four lead wire insertion holes 92 (see FIG. 3) of the grommet 9 are all positioned with respect to the outer cylinder 3, and the arm portion 33, the ventilation portion 34, and the side wall 39. (Especially the opening end 32) is not touched. Therefore, the lead wire 18 can be reliably protected from damage due to contact with other members (the outer cylinder 3).

  Further, since the outer cylinder 3, the arm part 33, and the ventilation part 34 are integrally formed, the ventilation part 34 that is generated when the outer cylinder 3 and the ventilation part 34 are separate bodies is inclined to the outer cylinder 3. The ventilation part 34 does not wobble after being assembled or assembled, and the ventilation part 34 can reliably protect the filter member 87. Further, when formed separately, it is not necessary to provide a structure for fixing both of them, which not only reduces the number of parts but also simplifies the structure. In addition, in the manufacturing process, it is possible to reduce the man-hours for fixing both of them.

  Further, since there are two or more arm portions 33 (four in the first embodiment), the support of the ventilation portion 34 by the arm portion 33 is made stronger and the ventilation portion 34 of the ventilation tube 34 with respect to the side wall 39 of the outer cylinder 3 is made. Positioning is ensured. Therefore, the twist of the ventilation part 34 with respect to the air communication hole 91 can be prevented.

  Manufacture of such a form of gas sensor 1 may be performed, for example, according to the following procedure. First, as shown in the first step of FIG. 5, a plate material made of stainless steel such as SUS304 is pressed to produce a bottomed cylindrical outer cylinder intermediate 101. Next, a portion 102 corresponding to the cylinder bottom of the outer cylinder intermediate body 101 is punched with a press machine, and the outer cylinder 3 in which the arm part 33 and the ventilation part 34 are formed is obtained as shown in the second step. Further, the ventilation portion 34 is pressed to form the opening 35 and the cover 36 (the opening 37 of the cover 36 shown in FIG. 4 is also formed). In addition, you may perform the said 1st process and 2nd process simultaneously by one press work.

  Next, the filter member 87 and the fastener 88 (see FIG. 1) are assembled in the air communication hole 91 of the grommet 9 produced in a separate process. Further, the four lead wires 18 are respectively inserted into the lead wire insertion holes 92 of the grommet 9, and the lead wires 18 are exposed from the tip of the grommet 9. In this state, the grommet 9 is accommodated in the outer cylinder 3. At this time, the top surface 99 of the grommet 9 divided into four sections is passed between the arm portions 33 to be exposed from the rear end of the outer cylinder 3, and the arm portion 33 is placed in the groove 93 of the grommet 9 (FIG. 1). The grommet 9 and the lead wire 18 are positioned with respect to the outer cylinder 3.

  Then, as shown in the third step, at the rear end portion 38 of the outer cylinder 3, a plurality of circumferential locations (four locations in this example) are intermittently crimped radially inward and protrude into the outer cylinder 3. A recess (inner protrusion 103) in the side wall 39 is provided. The grommet 9 is caught by the inner protrusion 103 and is prevented from coming off from the rear end 38 during the assembly of the gas sensor 1.

  Further, after the lead wires 18 are inserted into the separator 8 and the holding metal fitting 85 manufactured in separate steps and passed through, the tips of the lead wires 18 are joined to the four connection terminals 19 (see FIG. 1). Two of the connection terminals 19 are joined to the electrode 71 of the heater 7. In this state, the lead wire 18 is pulled to the rear side of the outer cylinder 3, and the rear end portions of the separator 8, the holding bracket 85 and the heater 7 are accommodated in the outer cylinder 3 as shown in the fourth step. In this manner, the rear end part of the gas sensor 1 in which the rear ends of the grommet 9, the separator 8, and the heater 7 are held in the outer cylinder 3 is completed.

  In a separate process, the detection element 6 is held by the metal shell 5 shown in FIG. 1, and a part on the front end side of the gas sensor 1 in a state where the protector 4 and the gasket 11 are assembled is manufactured. In combination, the front end portion 31 of the outer cylinder 3 is fitted into the rear end engaging portion 58 of the metal shell 5. And the front-end | tip part 31 of the outer cylinder 3 is crimped radially inward with respect to the rear-end engaging part 58, and the inner-projection part which formed the flange part 81 of the separator 8 next in the 3rd process (refer FIG. 5). 103, the side wall of the outer cylinder 3 corresponding to the arrangement position of the holding metal fitting 85 is caulked inward in the radial direction, and the side wall 39 of the outer cylinder 3 corresponding to the arrangement position of the grommet 9 is further inward in the radial direction. Clamp. Thereafter, laser welding is performed around the outer periphery of the crimped portion of the distal end portion 31 of the outer cylinder 3 to complete the gas sensor 1.

  Various modifications can be made to the first embodiment. For example, like the outer cylinder 110 shown in FIG. 6, the ventilation part 111 is provided with an opening 112 larger than the opening 35 (see FIG. 1) of the first embodiment, and the wire material is formed in the opening 112 in a mesh shape. A mesh member 113 formed by assembling may be attached. While the filter member 87 is protected from breakage by the mesh member 113, the ventilation through the opening 112 can be ensured.

  Moreover, you may provide the some hole 122 in the ventilation part 121 like the outer cylinder 120 shown in FIG. If the inner diameter of the hole 122 is set as appropriate while ensuring ventilation through the hole 122 and the size is such that the impact from the outside due to contact with plants or collision with flying stones can be prevented, the filter member 87 is sufficient. Can be protected from breakage. Of course, the number of the holes 122 can be changed as appropriate. If the total opening area is increased by increasing the number of holes, sufficient ventilation can be ensured in the ventilation portion 121.

  In the first embodiment, the number of the arm portions 33 that support the ventilation portion 34 is four. However, as shown in FIG. The ventilation portion 141 may be supported by one arm portion 142 as in the outer cylinder 140 shown in FIG. Of course, the number of arms may be three, five, or more. Further, the number of grooves of the grommet may be increased or decreased according to the number of arms, or the number of grooves may be larger than the number of arms.

  Further, in the first embodiment, the three openings 35 are provided in the ventilation portion 34, but the number of the openings 35 may be set as appropriate. For example, the outer cylinder 140 shown in FIG. 9 has two openings 143 formed in the ventilation part 141 and provided with a cover 144 for each. However, one opening may be provided, or four or more openings may be provided. Good.

  Next, as a second embodiment of the gas sensor according to the present invention, a gas sensor 201 will be described as an example with reference to FIGS. The gas sensor 201 according to the second embodiment includes a cover portion 234 having a different form from the ventilation portion 34 (see FIG. 1) provided in the outer tube 3 of the gas sensor 1 according to the first embodiment. Is provided. That is, among the components constituting the gas sensor 201, components other than the outer cylinder 203 are the same as those of the gas sensor 1. Therefore, the form of the outer cylinder 203 will be described here, and description of other parts will be omitted or simplified.

  As in the first embodiment, the outer cylinder 203 of the gas sensor 201 shown in FIG. 10 is formed of stainless steel such as SUS304 in a bottomed cylindrical shape, and the bottom portion is cut out to form the arm portion 233 and the covering portion 234. It is a thing. As shown in FIGS. 10 and 11, the covering portion 234 has a circular plate shape having an outer diameter substantially the same size as the atmosphere communication hole 91 of the grommet 9, and the open end 232 of the side wall 239 surrounding the outer periphery of the grommet 9. Is supported by two arm portions 233 extending radially inward from. The two arm portions 233 have the same inclination as the arm portion 33 of the first embodiment. In addition, the root portion of the arm portion 233 at the opening end 232 is located on the front end side in the axis O direction from the arm portion 33. The covering portion 234 is not provided with an opening.

  In the gas sensor 201 having such a configuration, the covering portion 234 is disposed so as to cover the atmospheric communication hole 91. For this reason, as shown in FIG. 11, when the gas sensor 201 is viewed from the rear end side along the axis O, it is blocked by the covering portion 234 and the filter member 87 cannot be visually recognized. As a result, the filter member 87 is protected from contact with plants, collision with flying stones, and the like, and damage due to external impact is prevented.

  The two arm portions 233 are disposed in the two groove portions 93 among the four groove portions 93 of the grommet 9. As shown in FIG. 10 and FIG. 11, in the groove portion 93 on the side where the arm portion 233 is not disposed (here, referred to as the groove portion 94 for convenience), the groove portion 93 is interposed between the covering portion 234 and the groove portion 94. A gap 238 leading to the atmosphere communication hole 91 is formed. Through this gap 238, ventilation between the outside and the atmosphere communication hole 91 (that is, ventilation between the inside of the outer cylinder 203 and the outside) is ensured. Of course, the groove 93 on the side where the arm portion 233 is disposed also has a gap 237 between the groove 93 and the covering portion 234, so that ventilation between the outside and the atmosphere communication hole 91 is possible through this gap 237. is there.

  In addition, since the outer cylinder 203, the arm portion 233, and the covering portion 234 are integrally formed, the covering portion 234 is inclined to the outer cylinder 203, which may occur when the outer cylinder 203 and the covering portion 234 are separate bodies. The cover portion 234 is not wobbled after being assembled, and the filter member 87 can be reliably protected by the cover portion 234. Further, when formed separately, it is not necessary to provide a structure for fixing both of them, which not only reduces the number of parts but also simplifies the structure. In addition, in the manufacturing process, it is possible to reduce the man-hours for fixing both of them.

  Since there are two or more arm portions 233 (four in the first embodiment), the arm portion 233 supports the covering portion 234 more firmly, and positioning of the covering portion 234 with respect to the outer cylinder 203 is ensured. It becomes. Therefore, generation | occurrence | production of the twist of the coating | coated part 234 with respect to the air | atmosphere communicating hole 91 can be prevented.

  Various modifications can be made to the second embodiment. For example, the number of arms may be one as in the above-described outer cylinder 140 (see FIG. 9). Alternatively, the outer cylinder may have four arm portions, and the arm portions may be disposed in all four groove portions 93 of the grommet 9. In this case, if the width of the arm portion is made smaller than the width of the groove portion 93, it is possible to ensure the reliability of air introduction between the arm portion and the groove portion 93. The ventilation between the outside and the atmosphere communication hole 91 can be secured through the gap 237 between the covering portion 234 and the groove portion 93. Of course, the number of arm portions of the outer cylinder and the groove portions of the grommets can be changed as appropriate.

  Further, the grommet 9 side is processed, and, for example, a notch or the like that leads to a gap between the arm part 233 and the groove part 93 is provided, and air permeability between the arm part 233 and the groove part 93 is ensured through the notch. May be. Then, the outside and the atmosphere communication hole 91 may be ventilated through the gap 237 between the covering portion 234 and the groove portion 93.

  In the first and second embodiments, the grommet 9 does not need to have the groove 93. In this case, it is preferable to provide at least a pair of protrusions on the top surface 99 of the grommet 9 and to arrange the arm portions 33 and 233 of the outer cylinder at positions sandwiched between the protrusions. Alternatively, the groove 93 may be partially formed in a groove shape. That is, although the groove is formed in the vicinity of the air communication hole 91, the groove portion may be formed so that the depth disappears as it approaches the outer peripheral side, and is made identical to the top surface 99.

DESCRIPTION OF SYMBOLS 1 Gas sensor 3 Outer cylinder 5 Main metal fitting 6 Detection element 9 Grommet 31 Tip part 33 Arm part 34 Ventilation part 35 Opening 36 Cover 37 Opening 38 Rear end part 39 Side wall 64 Detection part 87 Filter member 91 Atmospheric communication hole 92 Lead wire insertion hole 93 Groove 111 Vent 112 Open 113 Mesh member 121 Vent 122 Hole 201 Gas sensor 203 Outer cylinder 233 Arm 234 Cover 239 Gap

Claims (7)

A detection element that extends in the axial direction and has a detection unit for detecting a gas to be detected on its tip side;
A metal shell that surrounds the periphery of the detection element in the radial direction while causing the detection unit to protrude from its tip,
A cylindrical shape surrounding the periphery of the detection element in the radial direction on the rear end side, and an outer cylinder whose front end is fixed to the metal shell,
A plug member disposed on the rear end side of the outer cylinder, comprising a lead wire insertion hole through which a lead wire for taking out a detection signal of the detection element is inserted, and a filter member having air permeability and waterproofness Plug members formed so that air communication holes that allow air communication between the inside and the outside of the outer cylinder by interposing each extend in the axial direction;
In the gas sensor with
The outer cylinder is
A side surface surrounding the periphery of the plug member;
A ventilation portion that is arranged on the rear side of the plug member, covers the atmosphere communication hole of the plug member, and has an opening that is at least smaller than the opening of the atmosphere communication hole;
A plate-like arm portion that extends in the radial direction and connects the side surface portion and the ventilation portion,
A gas sensor comprising: The plug member has a groove extending outward in the radial direction avoiding the lead wire insertion hole starting from the atmosphere communication hole on the rear end facing surface side thereof,
The gas sensor according to claim 1, wherein the arm portion is disposed in the groove portion. The outer cylinder has at least two arm portions, and the plug member has at least two groove portions,
The gas sensor according to claim 2, wherein each of the arm portions is disposed in each of the groove portions.   Of the form having a plurality of holes penetrating in the axial direction, the form in which a mesh-like member is assembled to the opening in the axial direction, or the form having an opening on the side surface of the convex part formed on itself The gas sensor according to any one of claims 1 to 3, wherein the gas sensor is formed in any form. A detection element that extends in the axial direction and has a detection unit for detecting a gas to be detected on its tip side;
A metal shell that surrounds the periphery of the detection element in the radial direction while causing the detection unit to protrude from its tip,
A cylindrical shape surrounding the periphery of the detection element in the radial direction on the rear end side, and an outer cylinder whose front end is fixed to the metal shell,
A plug member disposed on the rear end side of the outer cylinder, comprising a lead wire insertion hole through which a lead wire for taking out a detection signal of the detection element is inserted, and a filter member having air permeability and waterproofness Plug members formed so that air communication holes that allow air communication between the inside and the outside of the outer cylinder by interposing each extend in the axial direction;
In the gas sensor with
The outer cylinder is
A side surface surrounding the periphery of the plug member;
When the gas sensor is viewed from the rear side in the axial direction, it is a covering portion that covers the filter member so that the filter member cannot be visually recognized. A cover that allows ventilation to the outside;
A plate-like arm portion that extends in the radial direction and connects the side surface portion and the covering portion;
A gas sensor comprising: The plug member has a groove extending outward in the radial direction avoiding the lead wire insertion hole starting from the atmosphere communication hole on the rear end facing surface side thereof,
The gas sensor according to claim 5, wherein at least one of the arm portions is disposed in the groove portion. The outer cylinder has at least two arm portions, and the plug member has at least two groove portions,
The gas sensor according to claim 6, wherein each of the arm portions is disposed in each of the groove portions.

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