JP2013061353A - Gas sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas sensor suppressed in deterioration in air tightness due to a sealant.SOLUTION: A gas sensor 100 comprises: a housing 20; a sensor element 3 disposed inside the housing; a sealant 6 injected in a gap between the sensor element and the housing; a cylindrical insulating member 10 disposed on a base end side of the sealant to separate at least the outside surface 10Bf of the base end part 10B from the inside surface of the housing; and an annular metal ring 30 made of precipitation-hardened alloy, which is disposed on a base end side of the insulating member and is protruded radially outwardly from the base end part of an outer periphery 30a. The seal material, the insulating member and the metal ring are caulked and fixed by a caulking part 20a formed by bending the base end part of the housing to the inside and the relation of 0.05<A/T<0.55 is satisfied when the thickness of the metal ring is defined as T and the radial distance between an outside surface 30f of the outer periphery of the metal ring and the outside surface of the base end part of the insulating member is defined as A (provided, A>0).

Description

  The present invention relates to a gas sensor including a sensor element that detects the concentration of a gas to be detected.

As a gas sensor for detecting the concentration of oxygen and NO _x in the exhaust gas of an automobile, having a sensor device using a solid electrolyte are known.
As shown in FIG. 8, this type of gas sensor is provided with a flange 3a near the center of a bottomed cylindrical sensor element (in this example, an oxygen sensor element) 3, and the sensor element 3 is connected to a cylindrical housing (metal shell). ) Is inserted and held inside 200 (Patent Document 1). A step portion 200 e is provided on the inner peripheral surface of the housing 200, and the cylindrical ceramic holder 5 is disposed on the base end side of the step portion 200 e via the packing 12. Then, the flange portion 3a of the sensor element 3 is indirectly in contact with the stepped portion 200e by applying the flange portion 3a of the sensor element 3 to the ceramic holder 5 via a packing (not shown) from the base end side.
Further, a cylindrical sealing material (talc powder) 6 and an insulating member (ceramic sleeve) 50 are arranged in the radial gap between the sensor element 3 and the housing 200 on the proximal end side of the flange portion 3a. Then, a metal ring (flat washer) 60 is disposed on the base end side of the insulating member 50, and the base end portion of the housing 200 is bent inward to form a crimped portion 200a. The seal material 6 is crushed by being pressed, and the whole is crimped and fixed and sealed.

  Further, a cylindrical outer cylinder 400 is joined to the base end portion of the housing 200 in order to hold lead wires and terminals provided on the base end side of the sensor element 3 and cover the base end portion of the sensor element 3. ing. On the other hand, the tip of the sensor element 3 is covered with a protector 7. Then, by attaching the male screw part 200d of the gas sensor housing 200 manufactured in this way to a screw hole such as an exhaust pipe, the tip of the sensor element 3 is exposed in the exhaust pipe to detect the detected gas (exhaust gas). doing.

JP 2007-285769 A (FIG. 11)

However, in the case of the technique described in Patent Document 1 described above, when the gas sensor is subjected to a cooling cycle, the airtightness between the sensor element 3 and the housing 200 is lowered, and the gas to be detected outside the sensor is moved inside the sensor (inside the outer cylinder 400 ). This is because when the gas sensor is heated, the metal housing 200 expands more than the ceramic sealing material 6 and the insulating member 50, and the caulking portion 200a is in the longitudinal direction (ex direction in FIG. 8). Since it extends to the end side, it is considered that the caulking is loosened and the sealing of the sealing material 6 becomes insufficient.
Therefore, an object of the present invention is to provide a gas sensor that suppresses deterioration of airtightness due to a sealing material.

In order to solve the above-described problems, a gas sensor according to the present invention includes a cylindrical housing extending in the axial direction, a sensor element having a distal end projecting from the distal end of the housing, and inserted and disposed inside the housing, and the sensor A sealing material filled in a gap between the element and the housing; a cylindrical insulating member that is disposed on a proximal end side of the sealing material and at least an outer surface of the proximal end portion is separated from an inner surface of the housing; And an annular metal ring made of a precipitation hardening type alloy, the outer peripheral portion of the insulating member projecting radially outward from the base end portion of the insulating member. The material, the insulating member, and the metal ring are caulked and fixed in a state of being pressed from the proximal end side toward the distal end side by a caulking portion formed by bending the proximal end portion of the housing inward. The thickness of the metal ring is T, and the radial distance between the outer surface of the outer peripheral portion of the metal ring and the outer surface of the base end portion of the insulating member is A (where A> 0). Then, the relationship of 0.05 <A / T <0.55 is satisfied.
With such a configuration, a stress that pushes the outer peripheral portion of the metal ring downward (tip) by caulking is applied to the entire metal ring, and when the gas sensor is heated and the caulking portion extends, the metal is opposite to the stress. The ring springs back. Then, along with this springback, the tip-facing surface (tip) side of the metal ring pushes down the insulating member to the tip, thereby preventing loosening of caulking and suppressing deterioration of airtightness due to the sealing material. Here, if the metal ring protrudes outward from the insulating member or the metal ring is too thin, the metal ring is plastically deformed during caulking, and the springback effect cannot be obtained. By managing in this range, a sufficient spring back is generated without plastic deformation.
Examples of the precipitation hardening type alloy include precipitation hardening stainless steel, and SUS630 standardized to JIS is particularly preferable.

Further, the gas sensor of the present invention includes a cylindrical housing extending in the axial direction, a front end projecting from the front end of the housing, a sensor element inserted and disposed inside the housing, the sensor element and the housing A sealing material filled in the gap, a cylindrical insulating member that is disposed on the base end side of the sealing material, and at least the outer surface of the base end portion is separated from the inner side surface of the housing, and the insulating member An annular metal ring that is disposed on the base end side and has an outer peripheral portion protruding radially outward from the base end portion of the insulating member, and the sealing material, the insulating member, and the metal ring are The crimping portion formed by bending the proximal end portion of the housing inwardly is crimped and fixed while being pressed from the proximal end side toward the distal end side, and is directed toward the distal end of the outer peripheral portion of the metal ring. Face It is located distal to the proximal facing surface of the proximal end portion of the insulating member.
With such a configuration, a stress that pushes the outer peripheral portion of the metal ring downward (tip) by caulking is applied to the entire metal ring, and when the gas sensor is heated and the caulking portion extends, the metal is opposite to the stress. The ring springs back. Then, along with this springback, the tip-facing surface (tip) side of the metal ring pushes down the insulating member to the tip, thereby preventing loosening of caulking and suppressing deterioration of airtightness due to the sealing material. Here, by applying sufficient caulking load so that the outer peripheral portion of the metal ring is positioned on the front end side of the base end facing surface of the base end portion of the insulating member, the above-described spring back effect is also increased, and the caulking is performed. Can be prevented, and deterioration of airtightness due to the sealing material can be suppressed.
Note that “the tip-facing surface of the outer peripheral portion of the metal ring is located on the tip side of the base-end facing surface of the insulating member” means that the metal ring bites into the gap between the insulating member and the housing. .

Furthermore, in the gas sensor of the present invention, the inner end of the crimped portion may be located on the radially outer side from the inner surface of the metal ring.
In this way, the position where the caulking load is applied to the metal ring is closer to the outer peripheral side than the inner peripheral side of the metal ring. Therefore, it becomes easy to apply a stress that pushes the outer peripheral side of the metal ring downward (tip), and the spring back effect described above easily occurs accordingly.

Furthermore, in the gas sensor of the present invention, the caulking portion may be in direct contact with the metal ring, and the inner end of the caulking portion may be separated from the metal ring.
If it does in this way, a caulking load will not be applied in the inner end of a caulking part, and the position which applies a caulking load to a metal ring will shift to the perimeter side of a metal ring. Therefore, it becomes easy to apply a stress that pushes the outer peripheral side of the metal ring downward (tip), and the spring back effect described above easily occurs accordingly.

  Furthermore, in the gas sensor of the present invention, it is preferable that the contact portion between the crimped portion and the metal ring is located on the radially inner side from the outer surface of the insulating member. It is preferable to apply a caulking load to the outer peripheral side of the metal ring. However, if it is too close to the outer peripheral side of the metal ring, only the outer peripheral part of the metal ring may be deformed and the spring back effect may be reduced. On the other hand, when the contact portion between the caulking portion and the metal ring is positioned on the radially inner side of the outer surface of the insulating member, a sufficient spring back effect is obtained while applying caulking load to the outer peripheral side of the metal ring. be able to.

Furthermore, in the gas sensor of the present invention, the inner surface of the metal ring may be located radially outward from the inner surface of the insulating member.
As the outer peripheral side of the metal ring is pushed down by the weight applied by caulking, the inner peripheral side of the metal ring is pushed upward (base end side). At this time, with the above configuration, the inner surface of the metal ring is less likely to be caught on the outer surface of the sensor element, and the caulking can be performed reliably.

  Furthermore, in the gas sensor of the present invention, the tip-facing surface of the metal ring may be in surface contact with the insulating member. As a result, since the area where the tip-facing surface of the metal ring is in contact with the base-facing surface of the insulating member is ensured, the spring force due to the spring back described above can be reliably exerted by these members.

In addition, as one means for the tip-facing surface of the metal ring to come into surface contact with the insulating member, the cross section of the metal ring cut along the surface along the axial direction is preferably rectangular.
In this case, since the tip-facing surface of the metal ring is a flat surface, the area in contact with the base-end facing surface of the base end portion of the insulating member is increased, and the spring force due to the spring back described above is reliably exerted on these members. Can do.
Furthermore, since the base end-facing surface of the metal ring is also a flat surface, the area in contact with the crimped portion is increased, and the spring force due to the spring back can be reliably exerted on these members.

  Furthermore, in the gas sensor of the present invention, the outer surface of the insulating member may be a straight shape. When the flange portion is formed on the insulating member, there is a risk that a crack will occur at the flange portion due to the load of the crimped portion.

  It is preferable to use precipitation hardening type stainless steel as the precipitation hardening type alloy because the spring back becomes strong.

  According to this invention, the gas sensor which suppressed deterioration of the airtightness by a sealing material is obtained.

It is sectional drawing which cut | disconnected the gas sensor which concerns on embodiment of 1st invention of this invention in the surface in alignment with an axial direction. It is the elements on larger scale of FIG. It is a figure which shows the effect | action which arises when a metal ring is crimped, and the effect | action of the springback. It is a figure which shows the relationship between the surface pressure decreasing rate by caulking, and A / T when it heats from 20 degreeC to 450 degreeC. It is a figure which shows an effect | action when the inner surface of a metal ring is located in the radial direction outer side from the inner surface of an insulating member. It is a figure which shows the example from which the cross section of a metal ring differs from a rectangle. It is a figure which shows the example which diameter-reduced the base end part of the insulating member from the other part. It is a figure which shows the structure of the crimping part vicinity of the conventional gas sensor.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 shows a cross-sectional structure in which a gas sensor 100 according to an embodiment of the first invention of the present invention is cut along a plane along an axial direction (a direction from the distal end toward the proximal end). In this embodiment, the gas sensor 100 is an oxygen sensor that is inserted into an exhaust pipe of an automobile and the tip (arrow F side in FIG. 1) is exposed to the exhaust gas to detect the oxygen concentration in the exhaust gas. The sensor element 3 is a known oxygen sensor element that constitutes an oxygen concentration cell in which a pair of electrodes are laminated on an oxygen ion conductive solid electrolyte body and outputs a detection value corresponding to the amount of oxygen.
The lower side (arrow F side) in FIG. 1 is the distal end side of the gas sensor 100, and the upper side in FIG. 1 is the proximal end side of the gas sensor 100.

The gas sensor 100 is an assembly in which the sensor element 3 is assembled in a housing (metal shell) 20. The sensor element 3 includes a cylindrical solid electrolyte body that is tapered toward the tip, and inner and outer electrodes (not shown) formed on the inner and outer peripheral surfaces of the solid electrolyte body, respectively. Become. The internal space of the sensor element 3 is set as a reference gas atmosphere, and the gas to be detected is brought into contact with the outer surface of the sensor element 3 to detect the gas. Further, a rod-shaped heater 15 is inserted in the internal space of the sensor element 3.
Near the center of the sensor element 3, a flange 3 a that protrudes radially outward is provided. On the other hand, on the inner peripheral surface near the distal end of the housing 20, a step portion 20e having a diameter reduced inward is provided, and a cylindrical ceramic holder 5 is disposed on the base end side of the step portion 20e with the packing 12 interposed. Then, the sensor element 3 is inserted inside the housing 20 and the ceramic holder 5, and the flange 3 a of the sensor element 3 is indirectly applied to the ceramic holder 5 through a packing (not shown) from the base end side. The flange portion 3a of the sensor element 3 is in contact with the step portion 20e from the base end side.

Further, a cylindrical sealing material (talc powder) 6 is filled in a radial gap between the sensor element 3 and the housing 20 on the base end side of the flange portion 3 a, and a cylindrical shape is further provided on the base end side of the sealing material 6. An insulating member (ceramic sleeve) 10 is disposed. Then, a metal ring (stainless steel flat washer) 30 is arranged on the base end side of the insulating member 10, and the base member of the housing 20 is bent inward to form a crimped portion 20a. The insulating material 10 and the sealing material 6 are crimped and fixed while being pressed against the distal end side, and the gap between the sensor element 3 and the housing 20 is sealed. Here, if the base end of the insulating member 10 is directly caulked, there is a possibility that cracking or the like may occur, and therefore caulking is performed via the metal ring 30.
The inner surface of the housing 20 is enlarged in the vicinity of the proximal end of the insulating member 10, and at least the outer surface 10 </ b> Bf of the proximal end portion 10 </ b> B of the insulating member 10 is separated from the inner surface of the housing 20. Further, the outer diameter of the metal ring 30 is larger than the outer diameter of the insulating member 10, and the outer peripheral portion 30a of the metal ring 30 protrudes radially outward from the outer surface 10Bf of the insulating member 10 as described later.

Further, a cylindrical outer cylinder is provided at the base end of the housing 20 to hold the lead wire 41 and the terminal fittings 71 and 91 provided on the base end side of the sensor element 3 and to cover the base end portion of the sensor element 3. 40 is joined. Specifically, an insulating cylindrical separator 111 is crimped and fixed to the inner surface of the base end side of the outer cylinder 40, and base portions 74 and 94 of the terminal fittings 71 and 91 are inserted into the two insertion holes of the separator 111, respectively. Has been fixed. Connection ends 75 and 95 are formed at the base ends of the base portions 74 and 94, respectively, and lead wires 41 and 41 are caulked and connected to the connection ends 75 and 95, respectively.
A cylindrical grommet 131 is caulked and fixed inside the outer cylinder 40 on the base end side of the separator 111, and lead wires 41 and 41 are externally connected through four insertion holes (only two are shown in FIG. 1) of the grommet 131. Has been drawn to. When the outer cylinder 40 is put on the base end of the housing 20 with the terminal fittings 71 and 91 protruding from the distal end side of the outer cylinder 40 in this manner, the cylindrical terminal fitting 71 is fitted into the cylinder of the sensor element 3. And electrically connected to the lead of the reference electrode on the inner surface of the sensor element 3. The terminal fitting 91 is fitted on the outer peripheral surface of the sensor element 3 and is electrically connected to the lead of the detection electrode on the outer surface of the sensor element 3. And the front-end | tip of the outer cylinder 40 is externally fitted by the base end part 20b of the housing 20, both are welded, and the outer cylinder 40 is fixed to the housing 20. FIG.
A through hole 131 a is formed at the center of the grommet 131 and communicates with the internal space of the sensor element 3. A water-repellent ventilation filter 140 is interposed in the central hole of the grommet 131 so that the reference gas (atmosphere) is introduced into the internal space of the sensor element 3 without passing external water.

  On the other hand, a cylindrical protector 7 is fitted on the front end portion 20 f of the housing 20, and the front end of the sensor element 3 protruding from the housing 20 is covered with the protector 7. The protector 7 is configured by attaching a bottomed cylindrical metal (for example, stainless steel, etc.) double outer protector 7b and an inner protector 7a having a plurality of holes (not shown) by welding or the like.

In the vicinity of the center of the housing 20, a polygonal flange portion 20c that protrudes radially outward and engages with a hexagon wrench or the like is provided, and is formed on the outer surface of the housing 20 between the flange portion 20c and the tip portion 20f. Has a male screw portion 20d. In addition, a gasket 14 is inserted into a step portion between the distal end surface of the flange portion 20c and the base end of the male screw portion 20d so as to prevent gas escape when attached to the exhaust pipe.
Then, by attaching the male screw portion 20d of the housing 20 to a screw hole such as an exhaust pipe, the tip of the sensor element 3 is exposed in the exhaust pipe to detect the detected gas (exhaust gas).

Next, the relationship between the metal ring 30 and the insulating member 10 in the first invention of the present invention will be described with reference to FIG. In the first invention of the present invention, the metal ring 30 is made of a precipitation hardening type alloy. Examples of the precipitation hardening type alloy include precipitation hardening stainless steel, and specifically, SUS630 standardized to JIS. By using the precipitation hardening type alloy, the metal ring 30 has high strength, and A / T can be regulated within the following range.
In the first invention, the thickness of the metal ring 30 is T, and the radial distance between the outer surface 30f of the outer peripheral portion 30a of the metal ring 30 and the outer surface 10Bf of the base end portion 10B of the insulating member 10 is A. Then, the relationship of 0.05 <A / T <0.55 is satisfied. Further, the outer surface 30 f of the metal ring 30 protrudes radially outward from the outer surface 10 Bf of the base end portion 10 B of the insulating member 10.
In this embodiment, the inner end 20 ap of the crimped portion 20 a is located on the radially outer side from the inner side surface 30 i of the metal ring 30. Further, in this embodiment, the inner side surface 30 i of the metal ring 30 is positioned on the radially outer side than the inner side surface 10 i of the insulating member 10. However, in the present invention (both the first invention and the second invention to be described later), it is not essential that the inner side surface 30i is positioned radially outward from the inner side surface 10i, and the inner side surface 30i faces the inner side surface 10i. One may be sufficient. In addition, from the relationship of inserting the sensor element 3, the inner side surface 30i does not become radially inner than the inner side surface 10i.

As described above, the outer surface 30f of the metal ring 30 protrudes radially outward from the outer surface 10Bf of the base end portion 10B of the insulating member 10, and as shown in FIG. 30Ce is biased radially outward from the radial central axis 10Ce of the insulating member 10. That is, when the caulking load by the caulking portion 20a is applied to the base end facing surface 30e of the metal ring 30, the fulcrum of the base end facing surface 10Bd of the base end portion 10B of the insulating member 10 that supports this load (of the insulating member 10). The central axis 30Ce is located radially outward from the radial central axis 10Ce). Therefore, from the relationship of the moments, the proximal facing surface 30e of the metal ring 30, such a number weighted P ₁ in the radial direction of the central axis caulking portion 20a outside from 30Ce of the metal ring 30.
On the other hand, conversely, the forward-facing surface 30d of the metal ring 30, according to many repulsive force P ₂ from the insulating member 10 side radially inner portion from the center axis 30CE.

Accordingly, the metal ring 30 as a whole is subjected to stress (bending moment) S ₁ that pushes the outer peripheral portion 30 a of the metal ring 30 downward (tip). The stress S ₁ is such that the outer surface 30 f of the metal ring 30 protrudes radially outward from the outer surface 10 Bf of the base end portion 10 B of the insulating member 10, and at least the inner surface 30 i of the metal ring 30 is the inner surface of the insulating member 10. As long as it is flush with the side surface 10i or the inner side surface 30i is located outside the inner side surface 10i, it is caused by the positional relationship with the fulcrum of the insulating member 10 described above. However, when the inner surface 30i to be described later is positioned outside the inner surface 10i, preferable because more stress S ₁ is increased.

On the other hand, as shown in FIG. 3B, when the gas sensor 100 is heated, the metal crimping portion 20a extends in the longitudinal direction (ex direction in FIG. 3) from the insulating member 10 such as ceramic. The metal ring 30 springs back in the direction S ₂ opposite to the stress S ₁ (that is, the direction in which the outer peripheral portion 30 a of the metal ring 30 returns upward (base end)). Along with this springback, the tip-facing surface 30d of the metal ring 30 pushes the insulating member 10 down to the tip (arrow Px), thereby preventing loosening of the caulking and suppressing deterioration of the airtightness due to the sealing material 6. To do.
However, if the outer surface 30f of the metal ring 30 protrudes outward from the outer surface 10Bf of the base end portion 10B of the insulating member 10 or the thickness of the metal ring 30 is too thin, the metal ring 30 is elastically limited during caulking. It has been found that the above-described springback effect cannot be obtained due to plastic deformation exceeding the above range.

Therefore, the inventors changed the distance A and the thickness T by simulation and examined in detail experimentally the conditions under which springback occurs effectively. In this simulation, the caulking part structure of the gas sensor shown in FIG. 2 was used, and the material (specifically, thermal expansion coefficient, Young's modulus, etc.) and position of each component were set. The material of the metal ring 30 is SUS630. And the repulsive force accompanying the position change of each component when it unloads after pushing down the crimping part 20a to 0.4 mm tip side at normal temperature (20 degreeC), the tip direction surface (seal material) of the insulating member 10 The surface pressure applied from the sealing material 6 side to the interface 6) was analyzed. This repulsive force (surface pressure) is calculated from the force to return to the original state according to the Young's modulus when the position of each component is displaced. In the simulation, the inner side surface 30i of the metal ring 30 is positioned radially outward from the inner side surface 10i of the insulating member 10.
Next, when the gas sensor 100 was heated to 450 ° C., a change in position due to extension accompanying thermal expansion of each component was calculated. And the said surface pressure in 450 degreeC was analyzed from the Young's modulus of each component according to this position change.
The analysis was performed by changing the thickness T of the metal ring 30 to 0.5 mm, 1.0 mm, and 2.0 mm, and changing the interval A to 0 mm, 0.1 mm, 0.3 mm, 0.5 mm, and 0.6 mm. went. However, in the size of the crimped portion structure of the housing 20 set in this simulation, the metal ring 30 cannot be inserted into the housing 20 when the interval A exceeds 0.6 mm. 6 mm.
The obtained results are shown in Tables 1 to 3 and FIG.

FIG. 4 is a graph showing the reduction in surface pressure from 20 ° C. to 450 ° C. in A / T in Tables 1 to 3.
In FIG. 4, when A / T = 0 (that is, in the conventional example in which the metal ring 30 does not protrude outside the insulating member 10), the surface pressure reduction rate decreases as the thickness T increases (21.9%). . However, in such a conventional example, it has already been found that caulking is loosened by heating and the airtightness is lowered. Therefore, the surface pressure reduction rate of 21.9% is regarded as a conventional level, and the range of A / T in which the surface pressure reduction rate is less than 21.9% in FIG. /T<0.55. That is, if 0.05 <A / T <0.55, it is considered that the reduction in surface pressure due to heating is small, and the spring back by the metal ring 30 is effectively generated.
Here, in the case of 0.05 ≧ A / T, A is substantially 0, the spring back of the metal ring 30 does not occur, and the effect of preventing loosening of caulking cannot be obtained. On the other hand, when A / T ≧ 0.55, the interval A becomes too large, the outer peripheral side of the metal ring 30 is bent too much downward (tip) and plastically deforms, and the above-described springback effect cannot be obtained.
A thickness T ≧ 1.0 mm is preferable because plastic deformation of the metal ring 30 is less likely to occur.

In the embodiment shown in FIGS. 1 and 2, a gap G is formed between the inner end 20 ap of the crimped portion 20 a and the base end facing surface 30 e of the metal ring 30, and the inner end 20 ap and the metal ring 30. Are separated from each other.
If it does in this way, the position which touches the base end direction surface 30e of the metal ring 30 among the crimping parts 20a, and applies a caulking load to the metal ring 30 will be the outer peripheral part 30a side of the metal ring 30. Therefore, easily it takes stress S ₁ depressing the outer peripheral portion 30a side of the metal ring 30 described in FIG. 3 downward (distal) spring back effect described above can easily occur.

  Further, as shown in FIG. 3B, the contact portion 30 g between the crimped portion 20 a and the metal ring 30 is located on the radially inner side from the outer side surface 10 </ b> Bf of the insulating member 10. Thereby, only the outer peripheral part 30a of the metal ring 30 is not deformed while applying a caulking load to the outer peripheral part 30a side of the metal ring 30, and a sufficient spring back effect can be obtained.

  Moreover, it is preferable that the cross section of the metal ring 30 cut | disconnected by the surface along the axial direction of the gas sensor 100 is a rectangle. In this case, the tip-facing surface 30d and the base-end facing surface 30e of the metal ring 30 are flat, and the area in contact with the caulking portion 20a and the base-end facing surface 10Bd of the base end portion 10B of the insulating member 10 is increased. The spring force by the spring back can be reliably exerted on these members. The metal ring 30 having a rectangular cross section can be manufactured by punching a flat plate, for example. If the tip-facing surface 30d of the metal ring 20 has a shape that is in surface contact with the base-end facing surface 10Bd of the insulating member 10, at least the spring force due to the spring back described above can be reliably exerted by these members. .

Furthermore, in the embodiment shown in FIGS. 1 and 2, the inner side surface 30 i of the metal ring 30 is located on the radially outer side than the inner side surface 10 i of the insulating member 10. The effect of this configuration will be described with reference to FIG. 5, taking as an example the metal ring 31 whose inner side surface 31 i is flush with the inner side surface 10 i of the insulating member 10.
First, when caulking is applied while applying more weight to the outer peripheral side of the metal ring 31 at the caulking portion 20a (FIG. 5A), the inner peripheral side of the metal ring 31 is moved upward as the outer peripheral side of the metal ring 31 is pushed down. It is pushed up (to the base end side) (FIG. 5B). At this time, if the inner side surface 31 i of the metal ring 31 is flush with the inner side surface 10 i of the insulating member 10, the inner side surface 31 i may be caught on the outer surface of the sensor element 3 when the inner peripheral side of the metal ring 31 is pushed up. As a result, the caulking work may be difficult.
Therefore, as shown in FIG. 2, by positioning the inner side surface 30i of the metal ring 30 on the radially outer side from the inner side surface 10i of the insulating member 10, the above-mentioned catch is reduced, and caulking can be performed reliably. .

  As shown in FIG. 6, the metal ring 32 cut along a plane along the axial direction of the gas sensor 100 may have a cross section different from a rectangle (in the example of FIG. 6, a circular tube shape). Examples of such a metal ring 32 include a circular or elliptical tubular metal hollow ring. Of course, it may be a solid ring. In the case of the metal ring 32 having a cross section different from the rectangle, the interval A is the interval between the outermost side of the metal ring 32 and the insulating member 10 (corresponding to A2 in FIG. 6), and the thickness T is between the crimped portion and the insulating member. Is the maximum thickness of the metal ring 32 (corresponding to T2 in FIG. 6).

  Further, as shown in FIG. 7, the stepped portion 11d may be formed by reducing the outer surface 11Bf of the base end portion 11B of the insulating member 11 from the outer surface of the other portion. That is, it is only necessary that the outer surface 30f of the metal ring 30 protrudes outward at least at the base end portion 11B of the insulating member 11, and the metal ring 30 does not need to protrude outward in other portions of the insulating member 11. However, it is preferable that the outer surface 11Bf of the insulating member 11 has a straight shape because the insulating member 10 does not crack.

Next, the relationship between the metal ring 30 and the insulating member 10 in the second invention of the present invention will be described. In the second invention, instead of defining A / T, the distal end facing surface 30d2 of the outer peripheral portion 30a of the metal ring 30 is positioned on the distal end side from the proximal end facing surface 10Bd of the proximal end portion 10B of the insulating member 10. Yes. However, since the other configuration of the second invention is the same as that of the first invention, the description thereof will be omitted and reference will be made to FIGS. As will be described later, the tip-facing surface 30d2 of the metal ring 30 is a surface in the vicinity of the outer peripheral portion 30a of the metal ring 30, and is below the tip-facing surface 30d of the portion where the metal ring 30 is in contact with the insulating member 10. Projects to the tip side. That is, the metal ring bites into the gap between the insulating member and the housing, and the tip-facing surface 30d and the tip-facing surface 30d2 are not flush with each other. Therefore, in order to distinguish both, the codes are 30d and 30d2, respectively.
In FIG. 2, the tip-facing surface 30 d 2 of the outer peripheral portion 30 a of the metal ring 30 protrudes downward (tip side) with respect to the base-end facing surface 10 Bd of the base end portion 10 B of the insulating member 10. That is, to the extent that it bends below a virtual line L (an imaginary line L that passes through the distal-facing surface 30d) that represents an extension line that extends the distal-facing surface 30d of the metal ring 30 from the proximal-facing surface 10Bd of the insulating member 10. More caulking load is applied to the outside of the metal ring 30. Thus, as shown in FIG. 3, the stress S ₁ depressing the outer peripheral portion 30a of the metal ring 30 downward (distal) increases. And since the spring back effect mentioned above also becomes large according to it, the loosening of caulking can be prevented similarly to 1st invention, and the deterioration of the airtightness by the sealing material 6 can be suppressed.

On the other hand, when the tip facing surface 30d2 of the metal ring 30 is located above (base end side) above the imaginary line L (that is, the metal ring does not bite into the gap between the insulating member and the housing, the tip facing surfaces 30d, 30d2). If is flush), caulking load of the metal ring 30 outside stress S ₁ is smaller insufficient, even less spring back effect.
This means that in the above-described simulation, when the interval A> 0 at normal temperature and the caulking portion 20a is pushed down to the tip side of 0.4 mm and unloaded, the tip of the outer peripheral edge 30f of the metal ring 30 is oriented under any conditions. This was also confirmed from the fact that the surface 30d2 hangs down from the imaginary line L to the tip side.

  In the case of the second invention, also in the metal ring 32 as shown in FIG. 6, the tip-facing surface 32 d 2 of the outer peripheral portion needs to be located below (tip side) the virtual line L. However, in the case of the metal ring 32, since the surface thereof is not flat, the outermost periphery of the metal ring 32 is not necessarily lowered to the tip side, and a portion slightly inside from the outer periphery is located below the imaginary line L. There is a case. Therefore, the outer peripheral portion of the metal ring 32 that protrudes radially outward from the base end portion 10 </ b> B of the insulating member 10 only needs to be positioned below the imaginary line L (on the front end side).

  It goes without saying that the present invention is not limited to the above-described embodiment, but extends to various modifications and equivalents included in the spirit and scope of the present invention.

3 Sensor element 6 Sealing material 10, 11 Insulating member 10B, 11B Base end portion of insulating member 10Bd Base end facing surface of base end portion of insulating member 10Bf, 11Bf Outer surface of base end portion of insulating member 10i Inner side surface of insulating member 20 housing 20a housing crimping portion 20ap inner end of crimping portion 30, 31, 32 metal ring 30a metal ring outer peripheral portion 30d metal ring front end surface 30d2, 32d2 metal ring outer end front end surface 30e metal ring 30f Outer surface of the outer peripheral portion of the metal ring 30g Contact portion between the crimped portion and the metal ring 30i Inner side surface of the metal ring 100 Gas sensor A The outer surface of the outer peripheral portion of the metal ring and the base end portion of the insulating member Distance in the radial direction from the outer surface F Direction of the tip T Thickness of the metal ring L The surface facing the tip of the metal ring is the base end of the insulating member Extended line extended from the tree surface (phantom)

The gas sensor according to the present invention includes a cylindrical housing extending in the axial direction, a front end projecting from the front end of the housing, a sensor element inserted and disposed inside the housing, and a gap between the sensor element and the housing. A sealing material filled in the tube, a cylindrical insulating member that is disposed on the base end side of the sealing material, and at least an outer surface of the base end portion is separated from the inner side surface of the housing, and a base end of the insulating member An annular metal ring that is arranged on a side and whose outer peripheral portion projects radially outward from the base end portion of the insulating member, and the sealing material, the insulating member, and the metal ring are The crimping portion formed by bending the base end portion of the housing inwardly is crimped and fixed in a state of being pressed from the base end side toward the tip end side, and the tip-facing surface of the outer peripheral portion of the metal ring is ,Previous It is located distal to the proximal facing surface of the proximal end portion of the insulating member.
With such a configuration, a stress that pushes the outer peripheral portion of the metal ring downward (tip) by caulking is applied to the entire metal ring, and when the gas sensor is heated and the caulking portion extends, the metal is opposite to the stress. The ring springs back. Then, along with this springback, the tip-facing surface (tip) side of the metal ring pushes down the insulating member to the tip, thereby preventing loosening of caulking and suppressing deterioration of airtightness due to the sealing material. Here, by applying sufficient caulking load so that the outer peripheral portion of the metal ring is positioned on the front end side of the base end facing surface of the base end portion of the insulating member, the above-described spring back effect is also increased, and the caulking is performed. Can be prevented, and deterioration of airtightness due to the sealing material can be suppressed.
Note that “the tip-facing surface of the outer peripheral portion of the metal ring is located on the tip side of the base-end facing surface of the insulating member” means that the metal ring bites into the gap between the insulating member and the housing. .

Claims (10)

A cylindrical housing extending in the axial direction;
A sensor element that protrudes from the front end of the housing and is inserted into the housing; and
A sealing material filled in a gap between the sensor element and the housing;
A cylindrical insulating member that is disposed on the base end side of the sealing material and at least an outer surface of the base end portion is separated from the inner side surface of the housing;
The outer peripheral portion of the insulating member is disposed on the base end side of the insulating member and protrudes radially outward from the base end portion of the insulating member, and has an annular metal ring made of a precipitation hardening type alloy,
The sealing material, the insulating member, and the metal ring are fixed by crimping in a state where the proximal end portion of the housing is bent inward and pressed from the proximal end side toward the distal end side. Has been
When the thickness of the metal ring is T, and the radial distance between the outer surface of the outer peripheral portion of the metal ring and the outer surface of the base end portion of the insulating member is A (however, A> 0), Gas sensor satisfying the relationship of 0.05 <A / T <0.55. A cylindrical housing extending in the axial direction;
A sensor element that protrudes from the front end of the housing and is inserted into the housing; and
A sealing material filled in a gap between the sensor element and the housing;
A cylindrical insulating member that is disposed on the base end side of the sealing material and at least an outer surface of the base end portion is separated from the inner side surface of the housing;
An annular metal ring that is disposed on the base end side of the insulating member and whose outer peripheral portion protrudes radially outward from the base end portion of the insulating member;
The sealing material, the insulating member, and the metal ring are fixed by crimping in a state where the proximal end portion of the housing is bent inward and pressed from the proximal end side toward the distal end side. Has been
The gas sensor is such that a distal-facing surface of the outer peripheral portion of the metal ring is located on a distal end side with respect to a proximal-facing surface of the proximal end portion of the insulating member.   The gas sensor according to claim 1 or 2, wherein an inner end of the caulking portion is located on a radially outer side from an inner surface of the metal ring. The caulking portion is in direct contact with the metal ring,
The gas sensor according to claim 1, wherein the inner end of the caulking portion is separated from the metal ring.   The gas sensor according to any one of claims 1 to 4, wherein a contact portion between the caulking portion and the metal ring is located radially inward from an outer surface of the insulating member.   The gas sensor according to any one of claims 1 to 5, wherein an inner side surface of the metal ring is positioned radially outward from an inner side surface of the insulating member.   The gas sensor according to claim 1, wherein a surface facing the tip of the metal ring is in surface contact with the insulating member.   The gas sensor according to claim 7, wherein a cross section of the metal ring cut along a plane along the axial direction is rectangular.   The gas sensor according to claim 1, wherein an outer surface of the insulating member has a straight shape.   The gas sensor according to claim 1, wherein the precipitation hardening type alloy is precipitation hardening stainless steel.

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