JP2011242410A - Gas sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas sensor which prevents breakage of a seal member and can exhibit more excellent durability.SOLUTION: In a gas sensor 1, a seal member 17 is fixed to a case 60 by caulking the rear end side of the case 60. A gap D which allows the expansion of the seal member 17 in an axial X direction is formed between the tip face of the seal member 17 and the rear end face of a separator 18. The tip of an insertion member 86 is brought into contact with the rear end face of the separator 18. The insertion member 86 includes an insertion part 86a which is inserted into a through-hole 17a, and a protrusion part 86b which protrudes toward the tip side from the insertion part 86a. The protrusion part 86b has an outer flange 86c which is extended in a direction orthogonal to the axial X direction from the tip side of the insertion part 86a, and a cylindrical part 86d which protrudes toward the tip side from the outer flange 86c.

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 on the front end side that detects a gas component to be measured, and holds the detection section exposed to the gas to be measured. A case that forms a gas space, and a seal member that is disposed on the rear end side of the case, forms a reference gas space together with the case, and has a through-hole penetrating from the atmosphere side to the reference gas space side. .

  Further, this gas sensor is inserted into the through hole of the seal member, and has a cylindrical insertion member having an atmosphere side opening on the rear end side and a reference side opening formed on the front end side, and the inner surface of the through hole. A sheet-like ventilation filter that is sandwiched between the outer surface of the member and covers the atmosphere-side opening, and a separator made of an insulating material disposed between the detection element and the sealing member.

  In general, the case is made of metal, the seal member is made of an elastic material such as heat-resistant rubber, and the separator is made of ceramic.

  A conventional gas sensor having such a configuration is mounted on, for example, an automobile. The gas sensor is attached to an intake system pipe or an exhaust system pipe of an engine or the like, and can detect a gas component to be measured by a detection element. Further, in this gas sensor, the atmosphere side and the reference gas space communicate with each other through the ventilation filter, the atmosphere side opening, and the reference side opening, so that the detection accuracy of the detection element of the gas sensor can be maintained. Yes.

JP 2005-291907 A

  By the way, since the conventional gas sensor is mounted at a high temperature part such as an intake system pipe or an exhaust system pipe, it is used under a situation where heating and cooling are repeated. For this reason, among structural members such as cases, seal members, and separators, seal members formed using an elastic material such as heat-resistant rubber have a particularly large linear thermal expansion coefficient. , Remarkably repeat thermal expansion and contraction. For this reason, this sealing material may break due to local concentration of internal strain due to long-term use.

  This invention is made | formed in view of the said conventional situation, Comprising: It is the problem which should be solved to provide the gas sensor which can suppress the fracture | rupture of a sealing member and can exhibit the outstanding durability.

  In order to solve the above-mentioned problems, the inventors have investigated the cause of the occurrence of breakage of the seal member and elucidated the cause of one form of breakage as described below.

  That is, in the above conventional gas sensor, the sealing member is restrained by the case by being crimped at the rear end side of the case, so when thermally expanding, the seal member is in an axial direction that is a direction orthogonal to the crimping direction. In particular, dimensional changes are likely to occur. However, in the above conventional gas sensor, since the entire front end surface of the seal member is in contact with the rear end surface of the separator, the front end surface of the seal member is restrained by the separator even if the seal member tries to expand in the axial direction. Can't swell. For this reason, in the sealing member, a large compressive strain is repeatedly generated in the vicinity of the portion constrained by the case, and as a result, the sealing member is broken.

Therefore, the gas sensor of the present invention extends in the axial direction and has a detection element on the distal end side that has a detection unit for detecting a gas component to be measured,
A case in which the detection unit is held so as to be exposed to the gas to be measured, and a reference gas space is formed on the rear end side of the detection element;
A seal member which is disposed on the rear end side of the case, forms a reference gas space with the case, and has a through-hole penetrating from the atmosphere side to the reference gas space side;
A ventilation filter that is disposed in the through-hole and that prevents passage of water and has air permeability;
In order to hold the ventilation filter in the through-hole, a cylindrical insertion member that is inserted into the through-hole, has an atmosphere side opening on the rear end side, and has a reference side opening formed on the front end side; ,
A gas sensor comprising a separator made of an insulating material disposed between the detection element and the seal member,
The seal member is fixed to the case by crimping the rear end side of the case, and the axial expansion of the seal member is caused between the front end surface of the seal member and the rear end surface of the separator. An allowable gap is formed, and the tip of the insertion member is in contact with the rear end surface of the separator,
The insertion member includes an insertion portion that is inserted through the through hole, and a protruding portion that protrudes from the insertion portion toward the distal end side.
The protruding portion includes an outer flange extending in a direction orthogonal to the axis from the distal end side of the insertion portion, and a cylindrical portion protruding from the outer flange toward the distal end side.

  In the gas sensor of the present invention having such a configuration, the sealing member is constrained to the case by crimping the rear end side of the case. In particular, dimensional changes are likely to occur in the axial direction. Here, in this gas sensor, a gap that allows expansion of the seal member in the axial direction is formed between the front end surface of the seal member and the rear end surface of the separator. For this reason, even when the seal member expands in the axial direction and undergoes dimensional deformation, the front end surface of the seal member is less likely to abut on the rear end surface of the separator and is not easily restrained by the separator. For this reason, in the seal member, in the vicinity of the portion restrained by the case by crimping the rear end side of the case, it is suppressed that large compressive strain is repeatedly generated as in the conventional gas sensor. The breakage of the member is suppressed.

  By the way, if a gap is simply provided between the front end surface of the seal member and the rear end surface of the separator for dimensional deformation of the seal member, both the front end of the insertion member inserted into the through hole of the seal member and the rear end surface of the separator A gap is formed. Then, when attached to the piping of the internal combustion engine, the insertion member falls out to the tip end side due to vibration of the internal combustion engine or the like, and as a result, the ventilation filter may not be held. On the other hand, in this invention, the front-end | tip of an insertion member is in contact with the rear-end surface of a separator. For this reason, even if the above-mentioned gap is formed, there is no gap between the front end of the insertion member and the rear end surface of the separator, and the insertion member falls out to the front end side, which prevents the ventilation filter from being held. Can be prevented.

  In the gas sensor of the present invention, any ventilation filter may be used as long as it exhibits the effects of the present invention.

  For example, in the gas sensor of the present invention, the ventilation filter may be a sheet that is sandwiched between the inner surface of the through hole and the outer surface of the insertion member and covers the atmosphere side opening.

  For example, in the gas sensor of the present invention, the ventilation filter may be a columnar one that is inserted into the insertion member and covers the atmosphere side opening.

  In the gas sensor of the present invention, the insertion member includes an insertion portion that is inserted through the through hole and a protrusion that protrudes from the insertion portion toward the distal end side. In this case, a gap can be secured by the protruding portion, and furthermore, the protruding portion can be prevented from coming into contact with the rear end surface of the separator and the insertion member can be prevented from falling off to the front end side, so that the operational effects of the present invention can be reliably achieved. Can do.

  The insertion portion may have any configuration as long as it can hold the ventilation filter and has a through-hole penetrating the atmosphere side and the reference gas space side. For example, the insertion portion may be cylindrical. Further, the projecting portion may have any configuration as long as it can secure a gap and can come into contact with the rear end face of the separator. A cylindrical shape such as a rectangular shape or a rectangular tube shape, or a ring shape (circular cross section) may be used. Furthermore, a notch may be formed in the protruding portion.

  Furthermore, in the gas sensor according to the present invention, the protruding portion has an outer flange extending in a direction orthogonal to the axis from the distal end side of the insertion portion, and a cylindrical portion protruding from the outer flange toward the distal end side. In this case, the outer flange comes into contact with the peripheral edge on the front end side of the through hole of the seal member, and the front end of the cylindrical portion comes into contact with the rear end surface of the separator. For this reason, the protrusion can reliably secure a gap and can contact the rear end surface of the separator.

  In the gas sensor of the present invention, it is preferable that the axial length of the protrusion is longer than the thickness of the insertion member. Thereby, since this gas sensor can secure a sufficient gap, the operational effects of the present invention can be reliably achieved.

It is a longitudinal cross-sectional view of the gas sensor of Example 1. FIG. 3 is an enlarged vertical sectional view of a main part of the gas sensor according to the first embodiment. It is a perspective view of an insertion member concerning a gas sensor of Example 1. 3 is an enlarged vertical sectional view of a main part of a gas sensor of Reference Example 1. FIG. It is a longitudinal cross-sectional view which concerns on the gas sensor of the reference example 1, and shows the modification of a spacer member. 10 is an enlarged vertical sectional view of a main part of a gas sensor of Reference Example 2. FIG. FIG. 7 is a cross-sectional view of the separator in the VII-VII cross section of FIG. 6 according to the gas sensor of Reference Example 2. 10 is an enlarged vertical cross-sectional view of a main part of a gas sensor of Reference Example 3. FIG. It is a principal part expanded longitudinal cross-sectional view of the gas sensor of Example 2. FIG. 10 is an enlarged vertical sectional view of a main part of a gas sensor of Reference Example 4. FIG.

  Hereinafter, Examples 1 and 2 and Reference Examples 1 to 4 embodying the present invention will be described with reference to the drawings. In addition, after demonstrating Example 1 and Reference Examples 1-3, Example 2 and Reference Example 4 are demonstrated. In FIGS. 1 to 6 and FIGS. 8 to 10, the side toward the lower side of the drawing is the front end side, and the side toward the upper side of the drawing is the rear end side.

Example 1
As shown in FIGS. 1 and 2, the gas sensor 1 according to the first embodiment is an oxygen sensor that is attached to an exhaust system of an automobile and measures the oxygen concentration in the exhaust gas, and mainly includes a detection element 20 and a case. 60, a seal member 17, an insertion member 86, a ventilation filter 85, and a separator 18.

  The detection element 20 is made of a solid electrolyte having oxygen ion conductivity, and has a bottomed cylindrical shape having a substantially U-shaped cross section extending in the axis X direction with the front end closed and the rear end opened. A detection unit 20 a that detects oxygen, which is a gas component to be measured, is provided on the front end side of the detection element 20.

  An engagement flange portion 20s protruding outward in the radial direction is provided at an intermediate portion in the axis X direction of the detection element 20, and the engagement flange portion 20s is fixed to the metal shell via a ceramic separator 13a described later. The An inner electrode layer 24 formed of a porous material such as Pt or a Pt alloy so as to cover almost the entire inner surface of the bottomed hole 21 of the detection element 20 is formed by a known electroless plating method. Is formed. On the other hand, a porous external electrode layer 25 similar to the internal electrode layer 24 is formed on the entire outer peripheral surface of the detection element 20 on the front end side of the engagement flange portion 20s. The internal electrode layer 24 is electrically connected to the distal end side of the internal electrode layer connection member 30 inserted on the rear end side of the bottomed hole 21 of the detection element 20, and the external electrode layer 25 is connected to the detection element 20. It is electrically connected to the front end side of the external electrode layer connection member 31 fitted on the rear end side.

  Further, the heater 12 held by the internal electrode layer connection member 30 is disposed in the bottomed hole 21 of the detection element 20, and the heater 12 abuts against the inner peripheral surface of the detection element 20 to detect the detection portion 20 a. The detection element is activated early by heating the element.

  Next, the case 60 is constituted by the metal shell 11 and the metal outer cylinder 16 from the front end side along the axis X. With this case 60, a reference gas space 60 a is formed on the rear end side of the detection element 20.

  Among these, the metal shell 11 is a metal hollow cylindrical body, and a flange portion 11c protruding outward in the radial direction is formed at a substantially central portion in the axis X direction. On the side, a screw portion 11b for attaching the gas sensor 1 to the exhaust pipe is formed. Furthermore, the front end side opening part 11a which engages the protector 15 mentioned later is formed in the front end side rather than the screw part 11b. On the other hand, a connecting portion 11d for engaging the metal outer cylinder 15 is formed on the rear end side of the flange portion 11c, and a rear end opening portion 11e for caulking is formed on the rear end side. Has been.

  The detection element 20 is inserted and disposed in the inner hole 22 of the metal shell 11. The inner hole 22 has a metal step 22a, and the metal flange 81, the ceramic holder 13a, and the metal packing 82 are engaged with the engagement flange of the detection element 20 in the metal step 22a. 20s is held. On the other hand, a ceramic powder 14 (for example, talc) is filled in the rear end side of the engagement flange portion 20s in the gap between the metal shell 11 and the detection element 20, and a ceramic sleeve 13b is disposed behind the ceramic powder 14 (for example, talc). Yes. The airtightness is maintained by the ceramic powder 14 by caulking the rear end side opening portion 11e through the metal packing 83 disposed on the rear end side of the ceramic sleeve 13b.

  The metal outer cylinder 16 is inserted into the connecting portion 11d of the metal shell 11 from the outside at the front end side and fixed by laser welding all around. The metal outer cylinder 16 has a tip end side that is larger in diameter than the rear end side, the front end side surrounds the detection element 20, and a separator 18 and a seal member 17 described later are disposed on the rear end side.

  In addition, a protector 15 is attached to the distal end side opening portion 11a of the metallic shell 11 so as to cover the detection portion 20a of the detection element 20 protruding from the distal end side opening portion 11a of the metallic shell 11. The protector 15 has a double structure of an outer protector 15a and an inner protector 15b. The outer protector 15a and the inner protector 15b are formed with a plurality of gas permeation ports through which the gas to be measured is permeated. For this reason, the external electrode layer 25 of the detection element 20 can come into contact with the gas to be measured through the gas transmission port of the protector 15.

  The separator 18 is a substantially cylindrical body made of an insulating alumina ceramic, and is disposed between the detection element 20 and a seal member 17 described later. The separator 18 is formed with a cavity 18a having four openings on the rear end face side of the separator 18 and one large opening connected to the four openings on the front end face side. In the cavity 18a, the rear end 30a side of the internal electrode layer connection member 30, the rear end 31a side of the external electrode layer connection member 31, heater connection members 32 and 33 (33 is the axis of 32 (Symmetric position with respect to X). In the gap 18a, the rear end 30a of the internal electrode layer connection member 30 and the rear end 31a of the external electrode layer connection member 31 are mechanically connected to a sensor output lead wire 19a, which will be described later. Wire connection members 32 and 33 are mechanically connected to the heater lead wires 12a and 12b.

  The seal member 17 is a substantially cylindrical body made of fluororubber. The seal member 17 is fitted into the rear end side opening 16a of the metal outer cylinder 16, and the rear end side opening 16a is caulked in the radial direction so as to be sealed to the metal outer cylinder 16, and It is arranged on the rear end side. The seal member 17 is formed with a through hole 17a having the axis X as the central axis. Such a sealing member 17 forms the reference gas space 60a together with the case 60, and communicates the atmosphere side and the reference gas space 60a side through the through hole 17a.

  An insertion member 86 is inserted into the through hole 17 a of the seal member 17. Further, a ventilation filter 85 is disposed so as to be sandwiched between the insertion member 86 and the through hole 17 a of the seal member 17.

  As shown in FIG. 3, the insertion member 86 is a stepped cylindrical body having an atmosphere side opening 86p on the rear end side and a reference side opening 86q formed on the front end side. More specifically, the insertion member 86 includes an insertion portion 86a that is inserted through the through hole 17a, and a protrusion 86b that integrally protrudes from the insertion portion 86a toward the distal end side. And the protrusion part 86b has the outer flange 86c extended in the direction orthogonal to the axis line X from the front end side of the insertion part 86a, and the cylindrical part 86d which protrudes toward the front end side from the outer flange 86c. Yes. The insertion member 86 is manufactured by press-molding a thin metal plate, and the length L in the axis X direction of the protrusion 86b is sufficiently longer than the thickness (about 0.2 mm) of the insertion member 86 1 0.0 mm. A plurality of ventilation notches 86e are formed in the cylindrical portion 86d.

  The ventilation filter 85 is a sheet-like body having both water repellency and air permeability (specifically, using a PTFE material). Then, before the sealing member 17 is fitted into the rear end side opening 16a of the metal outer cylinder 16, the insertion member 86 with the ventilation filter 85 covered is fitted into the through hole 17a, whereby the insertion portion of the insertion member 86 is inserted. 86a is inserted through the through hole 17a, and the ventilation filter 85 is sandwiched between the inner surface of the through hole 17a and the outer surface of the insertion portion 86a of the insertion member 86 to cover the atmosphere side opening 86p. Then, when the rear end side opening 16a of the metal outer cylinder 16 is crimped in the radial direction and the seal member 17 is sealed and fixed to the metal outer cylinder 16, the tip of the protrusion 86b is connected to the separator 18. A gap D that allows the expansion of the seal member 17 in the axis X direction is formed between the front end surface of the seal member 17 and the rear end surface of the separator 18 in contact with the rear end surface.

  With such a configuration, the atmosphere outside the gas sensor 1 is introduced into the reference gas space 60a in the metal outer cylinder 16 through the ventilation filter 85, the atmosphere-side opening 86p of the insertion member 86, and the reference-side opening 86q. It is introduced into the bottomed hole 21 of the element 20.

  Four lead wire insertion holes are further formed in the seal member 17, and the sensor output lead wires 19a and 19b and the heater lead wires 12a and 12b are drawn out to the outside.

  The gas sensor 1 according to the first embodiment having such a configuration is mounted on, for example, an automobile, and is mounted on an intake system pipe or an exhaust system pipe of an engine or the like. Then, the atmosphere is introduced into the reference gas space 60a from the outside through the ventilation filter 85, the atmosphere side opening 86p, and the reference side opening 86q. Then, the atmospheric air as the reference gas is also introduced into the bottomed hole 21 of the detection element 20 and contacts the internal electrode layer 24 on the inner peripheral surface of the bottomed hole 21. On the other hand, the gas to be measured comes into contact with the external electrode layer 25 on the outer peripheral surface of the detection element 20 through the gas transmission port of the protector 15. As a result, an electromotive force is generated according to the oxygen concentration difference between the inner and outer surfaces of the detection element 20, and this electromotive force is used as a detection signal for the oxygen concentration in the gas to be measured, so that the internal electrode layer 24, the external electrode layer 25, the internal electrode The oxygen concentration in the gas to be measured can be detected by taking it out through the layer connection member 30, the external electrode layer connection member 31, the sensor output lead wires 19a and 19b, and the like.

  In the gas sensor 1, a gap D that allows expansion of the seal member 17 in the axis X direction is formed between the front end surface of the seal member 17 and the rear end surface of the separator 18. For this reason, the front end surface of the seal member 17 is difficult to come into contact with the rear end surface of the separator 18 and is not easily restrained by the separator 18. For this reason, in the seal member 17, in the vicinity of the part S restrained by the metal outer cylinder 16 by crimping the rear end side opening 16a of the metal outer cylinder 16, a large compressive strain is generated as in the conventional gas sensor. Repeated occurrence is suppressed, and as a result, the breakage of the seal member 17 is suppressed.

  In the gas sensor 1, the distal end of the insertion member 86 is in contact with the rear end surface of the separator 18. For this reason, even if the above-mentioned gap D is formed, there is no gap between the front end of the insertion member 86 and the rear end surface of the separator 18, and the insertion member 86 falls off to the front end side, and the ventilation filter 85 is removed. It is possible to prevent a problem that it cannot be held.

  In this gas sensor 1, the insertion member 86 includes an insertion portion 86a and a protrusion 86b, and the protrusion 86b has an outer flange 86c and a cylindrical portion 86d. For this reason, in this gas sensor 1, the outer flange 86 c comes into contact with the peripheral edge on the front end side of the through hole 17 a, and the front end of the cylindrical portion 86 d comes into contact with the rear end face of the separator 18, so that the gap D can be ensured. At the same time, the insertion member 86 can be prevented from falling off to the tip side.

  Further, in this gas sensor 1, since the length L in the axis X direction of the protrusion 86 b is longer than the thickness of the insertion member 86, a sufficient gap D can be secured and the seal member 17 is compressed. It is more reliably suppressed that the distortion occurs repeatedly.

  In the gas sensor 1 of the first embodiment, it is not essential to form the ventilation notch 86e in the insertion member 86. For example, a ventilation groove may be formed on the rear end surface of the separator 18 instead of the ventilation notch 86e.

(Reference Example 1)
Next, Reference Example 1 will be described with reference to FIG. As shown in FIG. 4, the gas sensor 2 of Reference Example 1 employs an insertion member 286 and a spacer member 286b instead of the insertion member 86 in the gas sensor 1 of Example 1, and other configurations are implemented. This is the same as the gas sensor 1 of Example 1. Therefore, in the reference example 1, it demonstrates centering on the insertion member 286 and the spacer member 286b, and the description about another structure is simplified or abbreviate | omitted.

  As shown in FIG. 4, an insertion member 286 is inserted into the through hole 17 a of the seal member 17. Further, a ventilation filter 85 is disposed so as to be sandwiched between the insertion member 286 and the through hole 17 a of the seal member 17.

  As shown in FIG. 4, the insertion member 286 is a stepped cylindrical body having an atmosphere side opening 286p on the rear end side and a reference side opening 286q formed on the front end side. More specifically, the insertion member 286 includes an insertion portion 286a inserted through the through hole 17a, an outer flange 286c extending in a direction orthogonal to the axis X from the distal end side of the insertion portion 286a, and a distal end from the outer flange 286c. And a cylindrical portion 286d protruding toward the side.

  Further, an outer flange 286 c of the insertion member 286 and a spacer member 286 b that contacts the rear end surface of the separator 18 are provided. The spacer member 286b is an annular ring having a rectangular cross section, and is separate from the insertion member 286a and the separator 18. The spacer member 286b forms a gap D that allows the seal member 17 to expand in the axis X direction.

  In such a gas sensor 2 of Reference Example 1, a gap D is formed between the front end surface of the seal member 17 and the rear end surface of the separator 18 by the spacer member 286b. For this reason, in the gas sensor 1, even when the seal member 17 expands in the axis X direction, the front end surface of the seal member 17 is difficult to abut on the rear end surface of the separator 18 and is not easily restrained by the separator 18. For this reason, in the seal member 17, in the vicinity of the part S restrained by the metal outer cylinder 16 by crimping the rear end side opening 16a of the metal outer cylinder 16, a large compressive strain is generated as in the conventional gas sensor. Repeated occurrence is suppressed, and as a result, the breakage of the seal member 17 is suppressed.

  In the gas sensor 2 of Reference Example 1, the outer flange 286c of the insertion member 286 is in contact with the rear end surface of the separator 18 via the spacer member 286b. For this reason, even if the above-mentioned gap D is formed, there is no gap between the front end of the insertion member 286 and the rear end surface of the separator 18, and the insertion member 286 falls out to the front end side, and the ventilation filter 85 is removed. It is possible to prevent a problem that it cannot be held.

  Instead of the spacer member 286b, a spacer member 286e having a ring shape with a “U” shape as shown in FIG. 5 may be employed.

(Reference Example 2)
As shown in FIGS. 6 and 7, the gas sensor 3 of Reference Example 2 employs the insertion member 286 in the gas sensor 2 of Reference Example 1 and has a convex portion on the rear end surface of the separator 18 in the gas sensor 1 of Example 1. 318a is provided, and the other configurations are the same as those of the gas sensors 1 and 2 of the first embodiment and the first reference example. Therefore, in the reference example 2, it demonstrates centering on the separator 18, and the description about another structure is simplified and abbreviate | omitted.

  On the rear end surface of the separator 18, a columnar convex portion 318 a that integrally protrudes toward the rear end side is formed at substantially the center of the separator 18. The outer flange 286c of the insertion member 286 is in contact with the convex portion 318a, and a gap D that allows expansion of the seal member 17 in the axis X direction is formed by the convex portion 318a. Further, a cross-shaped ventilation groove 318b is provided in the convex portion 318a.

  In the gas sensor 3 of Reference Example 2 having such a configuration, a gap D is formed between the front end surface of the seal member 17 and the rear end surface of the separator 18 by the convex portion 318 a of the separator 18. For this reason, in the gas sensor 1, even when the seal member 17 expands in the direction of the axis X, the front end surface of the seal member 17 is difficult to abut on the rear end surface of the separator 18 and is not easily restrained by the separator 18. For this reason, in the seal member 17, in the vicinity of the part S restrained by the metal outer cylinder 16 by crimping the rear end side opening 16a of the metal outer cylinder 16, a large compressive strain is generated as in the conventional gas sensor. Repeated occurrence is suppressed, and as a result, the breakage of the seal member 17 is suppressed.

  In this gas sensor 3, the outer flange 286c of the insertion member 286 is in contact with the rear end surface of the convex portion 318a. For this reason, even if the above-mentioned gap D is formed, there is no gap between the front end of the insertion member 286 and the rear end surface of the separator 18, and the insertion member 286 falls out to the front end side, and the ventilation filter 85 is removed. It is possible to prevent a problem that it cannot be held.

(Reference Example 3)
As shown in FIG. 8, the gas sensor 4 of Reference Example 3 has a flanged columnar ventilation instead of the insertion members 86 and 286 and the sheet-like ventilation filter 85 in the gas sensors 1 and 2 of Example 1 and Reference Example 1. A filter 485 is employed. Other configurations are the same as those of the gas sensors 1 and 2 of the first embodiment and the first reference example. Therefore, in the reference example 3, it demonstrates centering on the ventilation filter 485, and the description about another structure is simplified and abbreviate | omitted.

  The ventilation filter 485 has both water repellency and air permeability (specifically, a PTFE material is used). As shown in FIG. 8, a columnar insertion portion 485a and a distal end side from the insertion portion 485a. And a flange portion 485b having a diameter larger than that of the insertion portion 485a.

  The outer diameter of the insertion portion 485a is slightly larger than the inner diameter of the through hole 17a. In addition, the outer diameter of the flange portion 485b is sufficiently large so that the rear end surface of the flange portion 485b contacts and stops against the peripheral edge of the through hole 17a. Furthermore, the length of the flange portion 485b in the direction of the axis X is also sufficiently long in order to secure the gap D (in this reference example, 1 mm or more).

  Then, after the insertion portion 485a is inserted into the through hole 17a, the rear end side opening portion 16a of the metal outer cylinder 16 is crimped in the radial direction, and the seal member 17 is sealed and fixed to the metal outer cylinder 16. Thus, the ventilation filter 485 is held in the through hole 17 a of the seal member 17. At this time, the flange portion 485 b abuts on the front end surface of the seal member 17 and the rear end surface of the separator 18, whereby the seal member 17 expands in the axis X direction between the front end surface of the seal member 17 and the rear end surface of the separator 18. Is formed.

  In the gas sensor 4 of Reference Example 3 having such a configuration, since the ventilation filter 485 is interposed between the atmosphere side and the reference gas space 60a, it is possible to prevent water from passing and to ensure air permeability. ing.

  In the gas sensor 4, a gap D is formed between the front end surface of the seal member 17 and the rear end surface of the separator 18 by the flange portion 485 b of the ventilation filter 485. For this reason, in the gas sensor 4, even when the seal member 17 expands in the direction of the axis X, the front end surface of the seal member 17 is difficult to come into contact with the rear end surface of the separator 18 and is not easily restrained by the separator 18. . For this reason, in the seal member 17, in the vicinity of the part S restrained by the metal outer cylinder 16 by crimping the rear end side opening 16a of the metal outer cylinder 16, a large compressive strain is generated as in the conventional gas sensor. Repeated occurrence is suppressed, and as a result, the breakage of the seal member 17 is suppressed.

  In the gas sensor 4, the flange portion 485 b of the ventilation filter 485 is in contact with the rear end surface of the separator 18. For this reason, even if the above-mentioned gap D is formed, there is no gap between the front end of the ventilation filter 485 and the rear end surface of the separator 18, and the ventilation filter 485 falls off to the front end side. It is possible to prevent a problem that it cannot be held.

  Furthermore, in this gas sensor 4, since the number of parts is reduced by eliminating the insertion member, it is possible to shorten the time of assembly work.

(Example 2)
In Example 1 and Reference Examples 1 and 2, the ventilation filter 85 has a sheet shape and is configured to be sandwiched and disposed between the insertion members 86 and 286 and the through hole 17a of the seal member 17. The configuration is not limited to this, and the ventilation filter may have a rod shape or a column shape that is a superordinate concept including a rod shape, and may be arranged in the insertion member 86. A second embodiment in which such a configuration is embodied is shown in FIG. In FIG. 9, the sheet-like ventilation filter 85 in the gas sensor 1 (shown in FIG. 2) of the first embodiment is changed to a columnar (also referred to as a rod-like) ventilation filter 585. The ventilation filter 585 has both water repellency and air permeability (specifically, a PTFE material is used), and its outer diameter is slightly larger than the inner diameter of the insertion portion 86a of the insertion member 86. Yes. For this reason, the ventilation filter 585 is tightly fixed in the insertion member 86 by being inserted into the insertion member 86. And after the insertion part 86a of the insertion member 86 is inserted in the through-hole 17a, the rear end side opening part 16a of the metal outer cylinder 16 is crimped in radial direction, and the sealing member 17 is sealed to the metal outer cylinder 16 By being fixed, the insertion member 86 and the ventilation filter 585 are held in the through hole 17 a of the seal member 17. Further, since the ventilation filter 585 is interposed between the atmosphere side opening 86p of the insertion member 86 and the reference side opening 86q, it is possible to prevent the passage of water and ensure air permeability. Even with such a configuration, the same effects as the gas sensor 1 of the first embodiment can be obtained.

(Reference Example 4)
Although the spacer member 286b of the reference example 1 is disposed so as to contact the outer flange 286c of the insertion member 286 and the rear end surface of the separator 18, the spacer member is not limited to this, for example, a spacer member as in the reference example 4 shown in FIG. 586e may be used. In FIG. 10, the insertion member 586 is a stepped cylindrical body having an atmosphere side opening 586p on the rear end side and a reference side opening 586q formed on the tip end side. More specifically, the insertion member 586 includes: The insertion portion 586a is inserted through the through hole 17a, and the protruding portion 586b protrudes integrally from the insertion portion 586a toward the distal end side. The protruding portion 586b has a cylindrical portion 586d extending in the direction of the axis X from the distal end side of the insertion portion 86a, and an outer flange 586c extending from the cylindrical portion 586d in a direction orthogonal to the axis X. The spacer 586e is sandwiched between the front end surface of the seal member 17 and the rear end surface of the outer flange 586c, and the spacer member 586b forms a gap D that allows the seal member 17 to expand in the axis X direction. The

  In the above, the present invention has been described with reference to the first and second embodiments. However, the present invention is not limited to the first and second 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, 2, 3, 4 ... Gas sensor 17 ... Sealing member 17a ... Through hole 18 ... Separator 20 ... Detection element 20a ... Detection part 60 ... Case (11 ... Metal shell, 16 ... Metal outer cylinder)
60a ... Reference gas space 85, 485, 585 ... Ventilation filter 86, 286, 586 ... Insertion member 86a, 286a, 586a ... Insertion portion 86b, 586b ... Projection part 86c, 286c, 586c ... Outer flange 86d, 586d ... Cylindrical portion 86p, 286p, 586p ... Air side opening 86q, 286q, 586q ... Reference side opening 286b, 286e, 586e ... Spacer member 318a ... Convex portion 485a ... Ventilation filter insertion portion 485b ... Ventilation filter flange D ... Gap L ... Axial length of protrusion X ... Axis

Claims (3)

A detection element that extends in the axial direction and has a detection part on the tip side for detecting a gas component to be measured;
A case in which the detection unit is held so as to be exposed to the gas to be measured, and a reference gas space is formed on the rear end side of the detection element;
A seal member which is disposed on the rear end side of the case, forms a reference gas space with the case, and has a through-hole penetrating from the atmosphere side to the reference gas space side;
A ventilation filter that is disposed in the through-hole and that prevents passage of water and has air permeability;
In order to hold the ventilation filter in the through-hole, a cylindrical insertion member that is inserted into the through-hole, has an atmosphere side opening on the rear end side, and has a reference side opening formed on the front end side; ,
A gas sensor comprising a separator made of an insulating material disposed between the detection element and the seal member,
The seal member is fixed to the case by crimping the rear end side of the case, and the axial expansion of the seal member is caused between the front end surface of the seal member and the rear end surface of the separator. An allowable gap is formed, and the tip of the insertion member is in contact with the rear end surface of the separator,
The insertion member includes an insertion portion that is inserted through the through hole, and a protruding portion that protrudes from the insertion portion toward the distal end side.
The projecting portion includes an outer flange extending in a direction orthogonal to the axis from the distal end side of the insertion portion, and a cylindrical portion projecting from the outer flange toward the distal end side.   The gas sensor according to claim 1, wherein the ventilation filter has a columnar shape that is inserted into the insertion member and covers the atmosphere side opening.   The gas sensor according to claim 1 or 2, wherein a length in the axial direction of the protrusion is longer than a thickness of the insertion member.

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