JP2007101411A - Sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor capable of preventing cracks from generating in an elastic sealing member, while fully securing the sealability of the elastic sealing member. <P>SOLUTION: The elastic sealing member 60 is provided with five lead wire insertion holes 61 to form a set with a lead wire 46, and one of the lead wire insertion holes 61 is arranged at the center of the elastic sealing member 60. The first stress relaxation groove 63 is provided at the rear end side of the elastic sealing member 60. A recess 64 of the first stress relaxation groove 63 is formed to arrange own bottom face, between a rear end 50 of the third outer cylinder part 58 and a rear end 93 of a bottom part 90 of an inner recess 99. The second stress relaxation groove 65 is provided in a tip end side of the elastic sealing member 60. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sensor. More specifically, for example, a gas sensor such as an oxygen sensor, a NOx sensor, or an HC sensor for detecting the concentration of a specific gas component in the exhaust gas discharged from the internal combustion engine, a temperature sensor for detecting the temperature of the exhaust gas, etc. Related to the sensor.

2. Description of the Related Art Conventionally, a gas sensor including a sensor element whose electrical characteristics change according to the concentration of a specific gas component in exhaust gas is used for air-fuel ratio control of an automobile. As this gas sensor, for example, a sensor element made of a solid electrolyte having oxygen ion conductivity, a heater for heating the sensor element, a metal fitting for holding the sensor element, and a rear end side of the metal fitting A cylindrical metal member provided, a lead wire electrically connected to the sensor element and the heater, drawn out from the inside of the cylindrical metal member, and a lead wire insertion hole for inserting the lead wire The thing of the structure provided with the elastic sealing member of this is known. After the elastic seal member is disposed inside the cylindrical metal member, the elastic seal member is compressed and deformed by crimping the cylindrical metal member radially inward to fix the elastic seal member to the inside of the cylindrical metal member. Yes. This ensures airtightness and watertightness (hereinafter also collectively referred to as sealability) between the elastic seal member and the cylindrical metal member and between the lead wire and the elastic sealant. (See Patent Documents 1 and 2)
Japanese Patent Laid-Open No. 9-229897 JP-A-9-54063

  By the way, in order to ensure better sealing performance, it is conceivable to increase the pressure applied when caulking the elastic seal member disposed inside the cylindrical metal member. However, when the pressure during caulking is increased, the compressive stress concentrated near the boundary of the caulking portion of the elastic seal member also increases, and this is coupled with the fact that the elastic seal member undergoes thermal expansion when using the gas sensor. Excessive stress may be applied near the boundary of the caulking portion of the seal member, and the elastic seal member may crack. Further, if the compressive stress concentrated near the boundary of the crimped portion of the elastic seal member becomes excessively large, the elastic seal member may be cracked when crimped.

  Therefore, the present invention provides a sensor capable of preventing cracks in the elastic seal member while sufficiently ensuring the sealing performance between the elastic seal member and the cylindrical metal member and between the lead wire and the elastic seal material. For the purpose.

  In order to achieve the above object, the present invention provides a sensor element extending in the axial direction and having a distal end directed toward a measurement object, a metal shell surrounding the sensor element in the radial direction, and holding the sensor element, and the metal shell A cylindrical metal member provided on the rear end side, at least one lead wire extending from the inside of the cylindrical metal member toward the outside and electrically connected to the sensor element, and the cylindrical metal member And an elastic seal member having a lead wire insertion hole for inserting the lead wire, wherein the cylindrical metal member protrudes inward and has its own The elastic seal member has an inner convex portion that fixes the elastic seal member disposed on the inner side in a state in which the elastic seal member is compressed and deformed in the radial direction. A sensor characterized by having a stress relaxation groove to relieve compressive stress generated therein when it is compressed and deformed by the inner convex portion.

In the present invention, the stress relaxation groove is provided on at least one of the front end side or the rear end side of the elastic seal member.
Thereby, it is possible to relieve the compressive stress generated when the elastic seal member is caulked and fixedly arranged inside the cylindrical metal member, and it is possible to prevent the elastic seal member from cracking. And the sealing performance between the elastic seal member and the cylindrical metal member and between the lead wire and the elastic seal material is sufficiently obtained.
In addition, when the sensor is used, even if heat is applied to the elastic seal member by transmitting the metal shell and the cylindrical metal member, and the elastic seal member undergoes thermal expansion, the stress relaxation groove reduces the compressive stress near the boundary of the crimped portion. Since it is mitigated, it is possible to suppress excessive stress from being applied to the elastic seal member, and to prevent the elastic seal member from cracking.

In the present invention, the stress relaxation groove is preferably provided on the rear end side, and the bottom surface of the stress relaxation groove is preferably disposed on the rear end side from the rear end of the bottom portion of the inner convex portion.
In addition, the bottom part of an inner side convex part is a part most depressed in the radial direction among inner side convex parts.
As a result, since the bottom surface of the stress relaxation groove is not disposed in the portion corresponding to the position where the crimped portion is formed in the elastic seal member, the stress applied to the crimped portion of the elastic seal material is reduced, and the elastic seal It is possible to prevent a situation in which the sealing performance between the member and the cylindrical metal member and between the lead wire and the elastic sealing material cannot be ensured.

  In the sensor of the type in which the inner convex portion is provided at a position away from the rear end of the cylindrical metal member toward the front end side, the bottom surface of the stress relaxation groove is located on the front end side from the rear end of the cylindrical metal member. By disposing it on the rear end side from the rear end of the bottom portion of the inner convex portion, it is possible to more effectively relieve the compressive stress generated in the elastic seal member while ensuring sufficient sealing performance.

Furthermore, in the present invention, it is desirable that the stress relaxation groove is provided on the distal end side, and the bottom surface of the stress relaxation groove is also disposed on the distal end side from the distal end of the bottom portion of the inner convex portion.
As a result, even on the distal end side of the elastic seal member, since the bottom surface of the stress relaxation groove is not disposed in the portion corresponding to the crimped portion forming position in the elastic seal member, the stress applied to the crimped portion of the elastic seal material is reduced. Conversely, it is possible to prevent a situation in which the sealing performance cannot be ensured due to a decrease.

In the present invention, four or more lead wires are provided, while the elastic seal member has a number of lead wire insertion holes corresponding to the number of the lead wires, and one of the lead wire insertion holes. It is desirable that one is disposed at the center of the elastic seal member.
As a result, in a sensor having four or more lead wire insertion holes, the occupied area of the lead wire insertion hole in the cross section of the elastic seal member is smaller than when the lead wire insertion hole is not arranged at the center of the elastic member. can do. Therefore, since a smaller diameter elastic seal member can be used while ensuring the sealing performance of the elastic seal member, a smaller diameter sensor can be obtained.
In addition, when an elastic seal member having a smaller diameter is used, the pressure applied when the elastic seal member is caulked increases, so that the elastic seal member is likely to crack. Therefore, by providing the stress relaxation groove in the elastic seal member, the compressive stress generated in the elastic seal member can be relaxed by the stress relaxation groove, so that the elastic seal member can be prevented from cracking.
Note that the lead wire insertion hole is arranged at the center of the elastic seal member, which means that the center (or center of gravity) of the lead wire insertion hole is substantially the same as the center (or center of gravity) of the elastic seal member in a plane perpendicular to the sensor axial direction. That is, it is arranged at the matching position.

Embodiments to which the present invention is applied will be described below with reference to the drawings.
In this embodiment, the gas sensor is a kind of gas sensor, and is used for air-fuel ratio feedback control in automobiles and various internal combustion engines, and the concentration of a specific gas (specifically, oxygen) in exhaust gas to be measured is determined. A full-range air-fuel ratio sensor 1 (hereinafter, also referred to as air-fuel ratio sensor 1) that is mounted on an exhaust pipe of an internal combustion engine while a sensor element to be detected will be described.

FIG. 1 is a cross-sectional view showing an overall configuration of an air-fuel ratio sensor 1 according to an embodiment to which the present invention is applied.
The air-fuel ratio sensor 1 includes a cylindrical metal shell 102 having a screw portion 103 formed on the outer surface for fixing to an exhaust pipe, and a sensor element 4 having a plate shape extending in the axial direction (vertical direction in the figure). The cylindrical ceramic sleeve 6 arranged so as to surround the radial circumference of the sensor element 4 and the electrode terminal portions 30, 31, 32, 34, 36 of the sensor element 4 are electrically connected to form a current path. And a separator 82 that is formed of an insulating material and that holds the lead frame 10 connected to the electrode terminal portions 30, 31, 32, 34, and 36 of the sensor element 4 with the sensor element 4, A lead wire 46 that forms a current path between the lead frame 10 and the outside of the sensor is provided. The lead wire 46 is composed of a conductive core wire and an insulating resin coating material that covers the core wire, and is configured such that the front end side and the rear end side of the core wire are exposed from the resin coating material. Has been.

  The sensor element 4 has a plate-like shape extending in the axial direction, and a detection portion 8 covered with an electrode protection layer is formed on the front end side (downward in the figure) directed to the gas to be measured, and the rear end side ( Electrode terminal portions 30, 31, 32, 34, and 36 are formed on the first plate surface 21 and the second plate surface 23, which are front and back, of the outer surface (upper in the drawing). Since the lead frame 10 is disposed between the sensor element 4 and the separator 82, the lead frame 10 contacts and is electrically connected to the electrode terminal portions 30, 31, 32, 34, and 36 of the sensor element 4. The lead frame 10 is also electrically and mechanically connected to a lead wire 46 disposed inside the sensor from the outside, and an external device (for example, ECU) to which the lead wire 46 is connected and an electrode A current path for a current flowing between the terminal portions 30, 31, 32, 34, and 36 is formed.

  The metal shell 102 has a substantially cylindrical shape having a through hole 109 penetrating in the axial direction and having a shelf 107 protruding radially inward inside the through hole 109. Further, the metal shell 102 has the detection portion 8 disposed outside the front end side of the through hole 109 and the electrode terminal portions 30, 31, 32, 34, 36 disposed outside the rear end side of the through hole 109. The sensor element 4 inserted through 109 is held. Further, the shelf 107 is formed as an inwardly tapered surface having an inclination with respect to a plane perpendicular to the axial direction.

  In addition, inside the through hole 109 of the metal shell 102, an annular ceramic holder 106, a powder filling layer 108 (hereinafter also referred to as a talc ring 108), and a second powder are provided so as to surround the periphery of the sensor element 4 in the radial direction. The filling layer 111 and the ceramic sleeve 6 described above are laminated in this order from the front end side to the rear end side. A caulking packing caulking packing 112 is disposed between the ceramic sleeve 6 and the rear end portion 104 of the metal shell 102, and the rear end portion 104 of the metal shell 102 is interposed via the caulking packing 112. The ceramic sleeve 6 is crimped so as to press the tip side.

  Further, an element cup 129 that functions as a packing for maintaining airtightness is disposed between the ceramic holder 106 and the shelf 107 of the metal shell 102. The element cup 129 is made of a metal material (for example, stainless steel), and has a bottom surface portion that covers the side surfaces of the ceramic holder 106, the talc ring 108, and the auxiliary sleeve 110 and covers the peripheral edge portion of the ceramic holder 106. It is formed in a cylindrical shape. The bottom surface of the element cup 129 has a central opening having a size that allows the sensor element 4 to be inserted through the central portion.

  Here, a perspective view showing a schematic structure of the sensor element 4 is shown in FIG. In FIG. 2, the sensor element 4 is shown by omitting an intermediate portion in the axial direction. The sensor element 4 has a rectangular shape in which an element portion 20 formed in a plate shape extending in the axial direction (left and right direction in FIG. 2) and a heater 22 formed in a plate shape extending in the axial direction are stacked. It is formed in a plate shape having an axial cross section. In addition, since the sensor element 4 used as the air-fuel ratio sensor 1 is a conventionally well-known thing, detailed description of the internal structure etc. is abbreviate | omitted, However, The schematic structure is as follows.

  First, the element unit 20 includes an oxygen concentration cell element in which a porous electrode is formed on both sides of a solid electrolyte substrate, an oxygen pump element in which a porous electrode is formed on both sides of the solid electrolyte substrate, and a gap between these elements. The spacers are stacked to form a hollow measurement gas chamber. This solid electrolyte substrate is made of zirconia in which yttria is dissolved as a stabilizer, and the porous electrode is mainly made of Pt. The spacer forming the measurement gas chamber is mainly composed of alumina, and inside the hollow measurement gas chamber is one porous electrode of the oxygen concentration cell element and one porous electrode of the oxygen pump element. It arrange | positions so that an electrode may be exposed. The measurement gas chamber is formed so as to be positioned on the distal end side of the element portion 20, and a diffusion rate controlling portion made of porous ceramic for communicating the measurement gas chamber and the outside is provided on the distal end side of the spacer. The portion where the measurement gas chamber is formed corresponds to the detection unit 8. On the other hand, the heater 22 is formed by sandwiching a heating resistor pattern mainly composed of Pt between insulating substrates mainly composed of alumina. The element unit 20 and the heater 22 are joined to each other via a ceramic layer (for example, zirconia ceramic or alumina ceramic). The sensor element 4 has an electrode protective layer (not shown) made of porous ceramic for preventing poisoning on at least the surface of the electrode exposed to the measurement object (exhaust gas in the present embodiment) on the tip side. Is formed. In the present embodiment, the entire front end side including the surface of the electrode exposed to the exhaust gas in the sensor element 4 is covered with the electrode protective layer.

  In such a sensor element 4, as shown in FIG. 2, three electrode terminal portions 30, 31, 32 are formed on the rear end side (right side in FIG. 2) of the first plate surface 21, and the second plate surface Two electrode terminal portions 34 and 36 are formed on the rear end side of 23. The electrode terminal portions 30, 31, and 32 are formed in the element portion 20, and one electrode terminal portion is one porous electrode of the oxygen concentration cell element exposed to the inside of the measurement gas chamber and the oxygen pump element. Are electrically connected in common with one of the porous electrodes. The remaining two electrode terminal portions of the electrode terminal portions 30, 31, and 32 are electrically connected to the other porous electrode of the oxygen concentration cell element and the other porous electrode of the oxygen pump element, respectively. The electrode terminal portions 34 and 36 are formed in the heater 22 and are connected to both ends of the heating resistor pattern via via conductors (not shown) that cross in the thickness direction of the heater.

  As shown in FIG. 1, the sensor element 4 configured in this way protrudes from the front end of the metal shell 102 fixed to the exhaust pipe with the detection unit 8 on the front end side (lower side in FIG. 1), and on the rear end side. The electrode terminal portions 30, 31, 32, 34, and 36 are fixed to the inside of the metal shell 102 in a state of protruding from the rear end of the metal shell 102. On the other hand, as shown in FIG. 1, a bottomed cylindrical external protector 42 having a plurality of holes and covering the protruding portion of the sensor element 4 on the outer periphery of the front end side (downward in FIG. 1) of the metallic shell 102 An internal protector 43 is attached by laser welding or the like.

  Further, the diameter of the sensor element 4 in which the electrode terminal portions 30, 31, 32, 34, and 36 are formed on the rear end side (upper side in FIG. 1) of the sensor element 4 protruding from the rear end portion 104 of the metal shell 102. A separator 82 is disposed so as to surround the periphery of the direction. The separator 82 is urged toward the rear end side so as to come into contact with the front end surface 52 of the elastic seal member 60 by the holding metal fitting 200, and is sandwiched between the front end surface 52 of the elastic seal member 60 and the holding metal fitting 200. The inner cylinder 44 is held in the state without contacting the inner peripheral surface of the outer cylinder 44.

An outer cylinder 44 is fixed to the outer periphery of the rear end side of the metal shell 102. As shown in FIG. 1, the outer cylinder 44 includes a first outer cylinder portion 54 to be joined to the metal shell 102, and a second outer cylinder located on the rear end side and having a smaller diameter than the first outer cylinder portion 54. A portion 56, a first step portion 49 positioned therebetween, a third outer cylinder portion 58 that is located on the rear end side of the second outer cylinder portion 56 and has a smaller diameter than the second outer cylinder portion 56; It has the 2nd step part 48 located between these. Further, in the opening on the rear end side of the outer cylinder 44 (in other words, inside the third outer cylinder part 58), the electrode terminal portions 30, 31, 32, 34, 36 of the sensor element 4 and the lead frame 10 are provided. A rubber elastic seal member 60 including a lead wire insertion hole 61 through which five lead wires 46 electrically connected to each other through the wire and a protruding portion 62 protruding outward in the radial direction is provided. Have been placed.
Further, the elastic seal member 60 is compressed and deformed by caulking a portion of the third outer cylinder portion 58 located around the elastic seal member 60 inward in the radial direction to form the inner convex portion 99. In this state, the third outer cylinder portion 58 is fixed. At this time, the elastic seal member 60 is fixed to the third outer cylinder portion 58 so that the rear end side protrudes from the rear end of the third outer cylinder portion 58. Further, the inner convex portion 99 is located away from the rear end of the third outer cylinder portion 58 toward the front end side.
In addition, the inner side convex part 99 is a part hollowed in radial direction by caulking. And the inner side convex part 99 inclines toward the front end side from the bottom part 90 inclined most toward the radial direction, the rear end side taper part 91 which inclines toward the rear end side from the bottom part 90, and the bottom part 90. A distal end side taper portion 92.

Next, the elastic seal member 60 which is the main part of the present invention will be described in detail.
The elastic seal member 60 is made of fluoro rubber having excellent heat resistance. FIG. 3 shows an upper perspective view of the elastic seal member before compression deformation, and FIG. 4 shows a lower perspective view of the elastic seal member before compression deformation.
As shown in FIGS. 3 and 4, the elastic seal member 60 includes five lead wire insertion holes 61 penetrating in the axial direction, a projecting portion 62 projecting radially outward from the front end, and a rear end side ( The first stress relaxation 63 having a substantially cross shape that is recessed toward the tip in the upper part in FIGS. 3 and 4 and the second stress in the form of a substantially cross that is recessed toward the rear end on the tip side (below in FIGS. 3 and 4). And a relaxation groove 65. The first stress relaxation groove 63 has a circular concave portion 64 that is recessed toward the tip at the center thereof.

  The elastic seal member 60 is provided with a first stress relaxation groove 63 on the rear end side and a second stress relaxation groove 65 on the front end side. The stress relaxation grooves 63 and 65 are deformed in a substantially radial direction when the elastic seal member 60 is caulked. And since stress is required for the deformation, the compressive stress generated when the elastic seal member 60 is swaged and fixed can be relaxed (reduced).

Further, the concave portion 64 of the first stress relaxation groove 63 is formed such that its bottom surface is disposed between the rear end 50 of the third outer cylinder portion 58 and the rear end 93 of the bottom portion 90 of the inner convex portion 99. .
Thereby, it is possible to effectively relieve the compressive stress generated when caulking the elastic seal member 60 while ensuring sufficient sealing performance, and to prevent the elastic seal member 60 from cracking. In addition, when the gas sensor is used, the metal shell 102 and the outer cylinder portions 54, 56, and 58 are transmitted to heat the elastic seal member 60. Even if the elastic seal member 60 is thermally expanded, the compression near the boundary of the crimped portion is performed. Since the stress is relaxed, it is possible to suppress excessive stress from being applied to the elastic seal member 60, and to prevent the elastic seal member 60 from cracking.
In order to more effectively relieve the compressive stress generated in the elastic sealing material 60, the bottom surface of the concave portion 64 of the first stress relaxation groove 63 should be arranged so as to be as close as possible to the boundary of the caulking portion. good. Therefore, the bottom surface of the concave portion 64 of the first stress relaxation groove 63 is preferably disposed between the rear end 93 of the bottom portion 90 of the inner convex portion 99 and the rear end 95 of the inner convex portion 99.

Further, the second stress relaxation groove 65 is formed such that its bottom surface is arranged on the tip side of the tip 94 of the bottom 90 of the inner convex portion 99.
Thereby, also on the front end side of the elastic seal member 60, it is possible to relieve the compressive stress generated when caulking while ensuring sufficient sealing performance, and to prevent the elastic seal member 60 from cracking. .
Further, in order to more effectively relieve the compressive stress generated in the elastic sealing material 60, it is better to dispose the bottom surface of the second stress relaxation groove 65 as close to the boundary of the crimped portion as possible. Therefore, the bottom surface of the second stress relaxation groove 65 is preferably disposed between the tip 94 of the bottom 90 of the inner convex portion 99 and the tip 96 of the inner convex portion 99.

The elastic seal material 60 is formed with five lead wire insertion holes 61 paired with the lead wire 46, and one of the lead wire insertion holes 61 is arranged at the center of the elastic seal material 60.
Thereby, compared with the case where lead wire penetration hole 61 is not arranged in the center of elastic member 60, the occupation area in the section of elastic seal member 60 of lead wire penetration hole 61 can be made small. That is, since the elastic seal member 60 having a smaller diameter can be used while ensuring the sealing performance of the elastic seal member 60, the air-fuel ratio sensor 1 having a smaller diameter can be obtained.
Further, when the elastic seal member 60 having a smaller diameter is used, the pressure applied when the elastic seal member 60 is caulked increases, so that the elastic seal member 60 is likely to crack, but the stress relaxation grooves 63 and 65 are provided. Therefore, it is possible to effectively prevent the elastic seal member 60 from being cracked.

  Further, the elastic seal member 60 is preferably disposed inside the third outer cylinder portion 58 in a state of protruding from the rear end of the third outer cylinder portion 58. As a result, when the lead wire 46 is bent, the lead wire 46 (specifically, the resin coating material of the lead wire) is damaged by coming into contact with the edge or burr at the rear end of the third outer cylinder portion 58. Can be prevented.

Next, an operation for assembling the air-fuel ratio sensor 1 will be described.
Five lead frames 10 to which the lead wires 46 are respectively connected are arranged inside the separator 82. At this time, the holding metal fitting 200 is mounted so that the J-shaped holding portion 203 abuts on the front end side surface of the flange portion 83 with respect to the outer periphery of the front end side portion 301 of the separator 82. Next, the elastic seal member 60 is placed on the rear end surface 305 of the separator 82, and the outer cylinder 44 is moved from the elastic seal member 60 side in this state. Then, the outer cylinder 44 is moved until the second step portion 48 of the outer cylinder 44 comes into contact with the protruding portion 62 of the elastic seal member 60, and the separator 82 and the elastic seal member 60 are accommodated in the outer cylinder 44. At this time, the separator 82 is accommodated in a non-contact state on the inner peripheral surface of the outer cylinder 44.

  Next, a deformed portion 75 is formed by caulking a portion of the second outer tube portion 56 of the outer tube 44 that is located on the radially outer side of the tube portion 201 of the holding metal fitting 200 to the radially inner side using a pressing jig. At the same time, the holding metal fitting 200 positioned inside is also deformed, so that the separator 82 is urged to the rear end side by the holding metal fitting 200. In this way, an upper assembly is first prepared. In addition, the deformation | transformation part 75 was formed by Happo-maru caulking. In addition, when the holding metal fitting 200 is deformed in a state where the separator 82 is in contact with the front end surface of the elastic seal member 60, the elastic seal member 60 is not displaced greatly from the rear end side. The holding metal fitting 200 was deformed in a state where a small load (about 5 N) was applied toward the tip side.

  Next, a lower assembly composed of the sensor element 4, the ceramic sleeve 6, the talc ring 108, the ceramic holder 106, the metal shell 102, the external protector 42, and the like is separately executed. In this lower assembly, the rear end side of the sensor element 4 was appropriately manufactured so as to protrude from the rear end side of the metal shell 102.

Then, by moving the upper assembly and the lower assembly thus manufactured relative to each other, the sensor element 4 is moved relative to the contact insertion hole 84 of the separator 82 in which the lead frame 10 is disposed inside. Insert the rear end. As a result, the element contact portion 16 of the lead frame 10 and the electrode terminal portions 30, 31, 32, 34, and 36 of the sensor element 4 come into contact with each other and are electrically connected to each other. Next, the outer cylinder 44 (first outer cylinder portion 54) disposed on the outer side in the radial direction of the metal shell 102 is crimped on the inner side in the radial direction. Next, a portion located around the elastic seal member 60 in the third outer cylinder portion 58 of the outer cylinder 44 is caulked radially inward using a caulking jig to form the inner convex portion 99, and the outer An elastic seal member 60 having stress relaxation grooves 63 and 65 is fixed to the tube 44 and each lead wire 64. Thereafter, the portion where the outer tube 44 is crimped radially inward with respect to the metal shell 102 is welded to the entire circumference by laser welding, and the metal shell 102 and the outer tube 44 are joined. As a result, the separator 82 is not in contact with the inner peripheral surface of the outer cylinder 44, and the holding metal 200 and the elastic seal member 60 are in a state where the peripheral side of the rear end surface 305 is in contact with the front end surface 52 of the elastic seal member 60. Is finally clamped with a large clamping force. In this way, the air-fuel ratio sensor 1 is completed.
The elastic seal member 60 is disposed so as to protrude from the rear end of the third outer cylinder portion 58, and the inner convex portion 99 is located away from the rear end of the third outer cylinder portion 58 toward the front end side.

In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof. .
For example, the sensor to which the present invention is applied is not limited to a gas sensor having five lead wires, and can be applied to a gas sensor having four or fewer lead wires or six or more lead wires. In this embodiment, the sensor element is a plate-like element, but a bottomed cylindrical element can also be used.
Furthermore, in the present embodiment, as a method of fixing the elastic seal member to the inside of the cylindrical metal member, the inner side of the cylindrical metal member can be formed by press-fitting the elastic seal member after providing the inner metal convex portion on the cylindrical metal member. It is also possible to use a method of fixing to the substrate.

It is sectional drawing which shows the whole area | region air-fuel-ratio sensor of embodiment. It is a perspective view showing the schematic structure of the sensor element which comprises a whole area | region air fuel ratio sensor. The upper perspective view of the elastic seal member before compressive deformation. The lower perspective view of the elastic seal member before compressive deformation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... All-range air-fuel ratio sensor (gas sensor), 4 ... Sensor element, 8 ... Detection part, 10 ... Lead frame (electrode extraction terminal), 30, 31, 32, 34, 36 ... -Electrode terminal part, 44 ... outer cylinder, 46 ... lead wire, 54 ... first outer cylinder part, 56 ... second outer cylinder part, 58 ... third outer cylinder part, 60・ ・ ・ Elastic seal member, 61 ・ ・ ・ Lead wire insertion hole, 63 ・ ・ ・ First stress relaxation groove, 64 ・ ・ ・ Recess, 65 ・ ・ ・ Second stress relaxation groove, 99 ・ ・ ・ Inner convex 102 ... Main metal fitting, 200 ... Holding metal fitting

Claims (5)

A sensor element extending in the axial direction and having the tip side directed toward the measurement object;
A metal shell surrounding the sensor element in the radial direction and holding the sensor element;
A cylindrical metal member provided on the rear end side of the metal shell,
At least one lead wire extending from the inside to the outside of the cylindrical metal member and electrically connected to the sensor element;
A sensor having an elastic seal member disposed inside the cylindrical metal member and having a lead wire insertion hole for inserting the lead wire,
The cylindrical metal member has an inner protrusion that protrudes inward and fixes the elastic seal member disposed inside itself in a state of being compressed and deformed in a radial direction,
The elastic seal member has a stress relaxation groove for relaxing a compressive stress generated inside when the elastic seal member is compressed and deformed by the inner convex portion on at least one of a front end side and a rear end side. The stress relaxation groove is provided on the rear end side,
The sensor according to claim 1, wherein a bottom surface of the stress relaxation groove is disposed on a rear end side from a rear end of a bottom portion of the inner convex portion. The inner convex portion is provided at a position away from the rear end of the cylindrical metal member,
The sensor according to claim 2, wherein a bottom surface of the stress relaxation groove is disposed on a front end side with respect to a rear end of the cylindrical metal member. The stress relaxation groove is provided on the tip side,
The sensor according to any one of claims 1 to 3, wherein a bottom surface of the stress relaxation groove is arranged on a front end side with respect to a front end of the bottom portion of the inner convex portion. While four or more lead wires are provided,
The elastic seal member has a number of the lead wire insertion holes corresponding to the number of the lead wires,
One of the said lead wire penetration holes is arrange | positioned in the center of the said elastic seal member, The sensor in any one of Claims 1-4 characterized by the above-mentioned.