JP5327137B2 - Gas sensor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a gas sensor for detecting a specific gas concentration in a gas to be measured and a method for manufacturing the gas sensor.

Conventionally, a gas sensor for measuring the concentration of a specific gas such as oxygen or nitrogen oxide in exhaust gas has been provided in an exhaust system of an internal combustion engine of an automobile.
For example, as shown in FIG. 16, as the gas sensor 90a, a gas sensor element 92 for detecting a specific gas concentration in the gas to be measured, a holding insulator 910 for inserting and holding the gas sensor element 92 inside, and the holding insulation One having a housing 911 that holds an insulator 910 inside and a base end side cover 960 fixed to the base end side of the housing 911 is known (see Patent Document 1 below).

  In this gas sensor 90a, the base end side opening 97 of the base end side cover 960 is sealed by a seal member 961 (rubber bush). The gas sensor 90 a has a plurality of wirings 962 that pass through the seal member 961. The wiring 962 is connected to the electrode terminal 92 c of the gas sensor element 92.

The sealing member 961 is formed with a ventilation filter 963 having both air permeability and water resistance between the outside and the inside of the base end side cover 960. Since the ventilation property is ensured by the ventilation filter 963, the composition of air existing inside the base end side cover 960 is the same as the composition of air existing outside. Since the inner space of the base end side cover 960 communicates with the reference electrode of the gas sensor element 92, air in the atmosphere can be used as a reference gas exposed to the reference electrode.
On the other hand, a measurement electrode is formed at the distal end portion 92a of the gas sensor element 92, and the measurement electrode is exposed to exhaust gas.

As another gas sensor 90, for example, as shown in FIG.
However, it is also known that it is sandwiched between the first base end side cover 960 and the second base end side cover 980 and is formed by two caulking portions in the axial direction (the following patents) Reference 2). In the gas sensor 90 b, a ventilation filter 963 is formed in the proximal end cover 960 on the distal end side with respect to the seal member 961.

  The gas sensor 90a in FIG. 16 and the gas sensor 90b in FIG. The gas sensor 90a in FIG. 16 uses a gas sensor element 92H that has better measurement accuracy than the gas sensor 90b in FIG. In addition, the gas sensor 90a in FIG. 16 uses a proximal end structure 96H having higher durability performance than the gas sensor 90b in FIG. Further, the gas sensor 90a in FIG. 16 and the gas sensor 90b in FIG. 17 are different from each other in the structure of the main body portion 912 including the gas sensor element 92, the holding insulator 910, and the housing 911.

JP 2009-115784 A JP 2002-174622 A

  In recent years, there has been a demand to manufacture various variations of the gas sensor 90 by changing the combination of the main body portion 912 and the base end side structure 96. For example, there is a demand to manufacture the gas sensor 90 having a new structure by combining the main body 912a of the gas sensor 90a and the base end side structure 96L of the gas sensor 90b.

  However, in the conventional gas sensor 90, since the gas sensor element 92, the housing 911, the base end side structure 96, and the like are integrally designed, these components cannot be partially replaced. Therefore, a gas sensor 90 that can easily change the combination of the base end side structure 96 and the main body 912 is desired.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a gas sensor that can easily change the combination of the base-end structure and the main body, and a method for manufacturing the same.

According to a first aspect of the present invention, there is provided a gas sensor element for detecting a specific gas concentration in a gas to be measured, a holding insulator for inserting and holding the gas sensor element inside, and a housing for holding the holding insulator inside. A main body comprising:
A contact unit consisting of a base end side insulator attached to the base end portion of the gas sensor element, and a contact member held by the base end side insulator and electrically connected to the electrode terminal of the gas sensor element;
A contact unit cover that is formed in a cylindrical shape, covers the contact unit from the outer periphery, is fitted and fixed to the housing, and is integrated with the contact unit and the main body to form a distal-end-side structure;
A cylindrical base end cover, a seal member that seals the base end opening of the base end cover, wiring that is inserted through the seal member and connected to the contact member, and the base cover A proximal side structure including a ventilation filter having both breathability and waterproofness between the outside and the inside;
The proximal side structure is fixed to the distal side structure ,
The contact unit cover includes a cylindrical portion that is externally fitted and fixed to the housing, and a shoulder portion that projects radially inward from a proximal end portion of the cylindrical portion and supports the contact unit from the proximal end side. ,
The base end side cover is externally fitted to the cylindrical portion,
The base end cover is a gas sensor which is welded to the cylindrical portion or the housing .

A second invention is a gas sensor manufacturing method according to the first invention,
A tip side structure manufacturing step of manufacturing the tip side structure in which the main body, the contact unit, and the contact unit cover are integrated;
A base end side structure manufacturing step for manufacturing the base end side structure;
A fixing step of fixing the proximal side structure to the distal side structure after performing the distal side structure manufacturing step and the proximal side structure manufacturing step;
In the manufacturing method of the gas sensor and performing (claim 3).

The function and effect of the first invention will be described. In the present invention, by using the contact unit cover, the tip side structure in which the contact unit, the main body, and the contact unit cover are integrated is formed. Moreover, the said base end side structure was formed as components different from the front end side structure. And it comprised so that a base end side structure could be fixed to a front end side structure.
If it does in this way, since the tip end side structure and the base end side structure are made into separate parts, the combination can be changed freely.
Further, if the portion for fixing the distal end side structure and the proximal end side structure is made common, it can be easily fixed even when these combinations are changed. For example, the base end side cover of the base end side structure is externally fitted to the contact unit cover of the front end side structure and welded. In this case, if the base end side cover and the contact unit cover outer diameter are made common in multiple types of base end structure and tip end structure, the combination of the base end structure and the tip end structure These can be easily fixed even if they are changed.

The operation and effect of the second invention will be described. In this invention, the said front end side structure preparation process, the said base end side structure preparation process, and the fixing process which fixes the said base end side structure to a front end side structure are performed.
If it does in this way, the multiple types of gas sensor from which the combination of a front end side structure and a base end side structure differs mutually can be manufactured easily. That is, in the base end side structure manufacturing step, a plurality of types of base end side structures having different structures are manufactured. In the fixing step, the distal end side structure and one proximal end structure selected from a plurality of types of proximal end structures are combined and fixed. This makes it possible to easily manufacture various variations of gas sensors in which the combination of the distal end side structure and the proximal end side structure is different from each other.

  As described above, according to this example, it is possible to provide a gas sensor that can easily change the combination of the base-end structure and the main body.

FIG. 3 is a cross-sectional view of the gas sensor in the first embodiment. Sectional drawing of the gas sensor in the front end side structure preparation process in Example 1. FIG. The figure following FIG. Sectional drawing of the base end side structure in the base end side structure preparation process in Example 1. FIG. Sectional drawing of the gas sensor in the fixing process in Example 1. FIG. FIG. 8 is a side view of the base-end-side insulator in the first embodiment, and is a view taken in the direction of arrow B in FIG. 7. FIG. FIG. 10 is a side view of the holding insulator in the first embodiment, and is a view as viewed from an arrow D in FIG. 9. C arrow line view of FIG. Sectional drawing of the gas sensor which fixed the base end side structure of the kind different from FIGS. 1-5 in Example 1. FIG. The figure following FIG. Sectional drawing of the front end side structure in Example 2. FIG. Sectional drawing of the state which fixed the base end side structure to the front end side structure of FIG. FIG. 12 is a cross-sectional view of the distal-end-side structure in which the shape of the contact unit cover is changed in FIG. Sectional drawing of the state which fixed the base end side structure to the front end side structure of FIG. Sectional drawing of the gas sensor in a prior art example. Sectional drawing of the gas sensor in the prior art example different from FIG.

A preferred embodiment of the present invention described above will be described.
1st invention WHEREIN: The said contact unit cover is provided with the cylindrical part externally fitted to the said housing, and the shoulder part which protrudes in radial direction in the base end part of this cylindrical part, This shoulder part is the said contact point. the units that are supported from the base end side.
Therefore , since the contact unit is supported from the base end side by the shoulder portion, it is possible to prevent the contact unit and the main body portion from being separated by the shoulder portion. Therefore, the tip side structure in which the contact unit, the main body, and the contact unit cover are integrated can be easily manufactured.

Further, it is preferable that the elastic member is interposed between the shoulder and the contact unit (claim 2).
If it does in this way, the difference of the thermal expansion coefficient of a contact unit cover and a base end side insulator can be absorbed by an elastic member. In other words, when the contact unit cover is made of metal, the contact unit cover expands as the temperature rises, but the proximal insulator does not expand so much. There may be a gap between the shoulder portion and the proximal insulator, which may cause rattling. However, by providing an elastic member between the shoulder portion and the base end side insulator, the base end side insulator can be urged toward the front end side, so that rattling can be prevented.

Example 1
A gas sensor and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the gas sensor 1 of this example includes a distal end side structure 5 and a proximal end side structure 6. The distal-end-side structure 5 includes a main body 12, a contact unit cover 4, and a contact unit 3.

  The main body 12 includes the gas sensor element 2, the housing 11, and the holding insulator 10. The gas sensor element 2 detects the concentration of a specific gas such as oxygen or NOx contained in a gas to be measured such as exhaust gas. The holding insulator 10 holds the gas sensor element 2 inserted inside. The housing 11 holds the holding insulator 10 inside.

  The contact unit 3 includes a contact member 31 and a base end side insulator 30. The base end side insulator 30 is attached to the base end side end surface of the holding insulator 10. The contact member 31 is held by the proximal insulator 30 and is electrically connected to the electrode terminal 20 of the gas sensor element 2.

  The contact unit cover 4 is formed in a cylindrical shape and covers the contact unit 3 from the outer periphery. The contact unit cover 4 is externally fitted and fixed to the housing 11, and is integrated with the contact unit 3 and the main body 12 to constitute the distal end side structure 5.

The base end side structure 6 includes a cylindrical base end side cover 60, a wiring 62 (lead wire), a ventilation filter 63, and a seal member 61. The seal member 61 seals the proximal end opening 600 of the proximal cover 60. The wiring 62 is connected to the contact member 31 through the seal member 61. The ventilation filter 63 combines air permeability between the outside and the inside of the base end side cover 60 and waterproofness.
In addition, the proximal side structure 6 is fixed to the distal side structure 5.
The details will be described below.

  Since the ventilation filter 63 has air permeability, the composition of air existing inside the proximal end side cover 60 is the same as the composition of air existing outside. The distal end portion 21 of the gas sensor element 2 is exposed to the exhaust gas, and the proximal end portion 22 is exposed to the air in the proximal end side cover 60.

  A protective cover 14 for protecting the distal end portion 21 of the gas sensor element 2 is attached to the housing 11. The protective cover 14 includes an inner cover 14a and an outer cover 14b.

The contact unit cover 4 includes a cylindrical portion 40 (see FIG. 2) that is externally fitted to the housing 11, and a shoulder portion 41 that protrudes radially inward at the base end portion 40 b of the cylindrical portion 40. The shoulder 41 supports the contact unit 3 from the base end side.
The contact unit cover 4 is externally fitted to the housing 11 and welded.

  Further, as shown in FIG. 1, an elastic member 13 (disc spring) is interposed between the shoulder portion 41 and the contact unit 3. The elastic member 13 urges the proximal-side insulator 30 toward the distal end side.

Next, a method for manufacturing the gas sensor 1 will be described. In the manufacturing method of the gas sensor 1 according to this example, the distal-side structure manufacturing process (see FIGS. 2 and 3), the proximal-side structure manufacturing process (see FIG. 4), and the fixing process (see FIGS. 5 and 1). ) And do.
As shown in FIG. 2, in the tip side structure manufacturing step, the gas sensor element 2 is inserted into and held in the holding insulator 10. Further, the holding insulator 10 is housed and held in the housing 11. And the base end side insulator 30 is attached to the base end part 22 of the gas sensor element 2, and the contact member 31 is connected to the electrode terminal 20 of the gas sensor element 2. FIG.

  Thereafter, the contact unit cover 4 is put on the base-side insulator 30. An elastic member 13 is interposed between the contact unit cover 4 and the base end side insulator 30. And as shown in FIG. 3, the front-end | tip part 40a of the contact unit cover 4 is externally fitted to the housing 11. As shown in FIG. Thereafter, the elastic member 13 is compressed between the shoulder 41 and the proximal insulator 30 by pushing the contact unit cover 4 toward the distal end. In this state, the tip end portion 40 a of the contact unit cover 4 is welded to the housing 11. As a result, in the state where the elastic member 13 is urged so as to press the proximal-side insulator 30 toward the distal end side, the distal-end-side structure 5 in which the contact unit 3, the main body 12, and the contact unit cover 4 are integrated. Is formed.

On the other hand, as shown in FIG. 4, the base end side cover 60, the seal member 61 disposed in the base end portion 601 of the base end side cover 60, the wiring 62 through which the seal member 61 is inserted, and the seal member 61 The base end side structure 6 provided with the formed ventilation filter 63 is produced.
In the state of FIG. 4, since the proximal end portion 601 of the proximal end side cover 60 is not crimped, the wiring 62 can move in the seal member 61 in the axial direction.

After performing the distal-end-side structure manufacturing step and the proximal-end-side structure manufacturing step, the fixing step is performed. That is, as shown in FIG. 5, the wiring 62 of the proximal end structure 6 is connected to the contact member 31 of the distal end structure 5. Then, the base end side cover 60 is fitted on the contact unit cover 4.
Next, the distal end portion 602 of the base end side cover 60 is welded to the contact unit cover 4. Further, the proximal end portion 601 of the proximal end side cover 60 is crimped to the seal member 61 from the outer periphery to seal the proximal end portion 601. Thereby, as shown in FIG. 1, the gas sensor 1 in which the distal end side structure 5 and the proximal end side structure 6 are integrated is formed.

  Next, the structure of the base end side insulator 30 and the holding insulator 10 will be described. As shown in FIGS. 6 and 7, a cross-shaped recess 300 is formed on the distal end surface 35 of the proximal insulator 30. Further, as shown in FIGS. 8 and 9, a cross-shaped convex portion 200 is formed on the proximal end surface 15 of the holding insulator 10. In a state in which the proximal insulator 30 is assembled to the holding insulator 10, the convex portion 200 of the holding insulator 10 is engaged with the recess 300 of the proximal insulator 30. Thereby, it can prevent that the base end side insulator 30 rotates centering on the central axis X (refer FIG. 6) with respect to the insulator 10 for holding | maintenance.

The effect of this example will be described. In the gas sensor 1 of this example, as shown in FIG. 1, by using the contact unit cover 4, the tip side structure 5 in which the contact unit 3, the main body 12, and the contact unit cover 4 are integrated is formed. Also, the base end side structure 6 was formed as a separate part from the tip end side structure 5. The base end side structure 6 is fixed to the tip end side structure 5.
If it does in this way, since the front end side structure 5 and the base end side structure 6 are made into another components, the combination can be changed freely.
In this example, the base end side cover 60 of the base end side structure 6 is externally fitted to the contact unit cover 4 of the tip end side structure 5 and welded. Therefore, if the inner diameter of the proximal end cover 60 and the outer diameter of the contact unit cover 4 are made common, they can be easily fixed even if the combination of the proximal end structure 6 and the distal end structure 5 is changed. Can do.

Moreover, in the manufacturing method of the gas sensor 1 according to this example, the distal-end-side structure manufacturing process (see FIGS. 2 and 3), the proximal-end-side structure manufacturing process (see FIG. 4), and the fixing process (see FIGS. 5 and 5). 1).
If it does in this way, the multiple types of gas sensor 1 from which the combination of the front end side structure 5 and the base end side structure 6 mutually differs can be manufactured easily. That is, in the tip side structure manufacturing step, a plurality of types of tip side structures 5 having different structures such as the gas sensor element 2 are manufactured. Further, in the base end side structure manufacturing step, a plurality of types of base end side structures 6 having different structures are manufactured. In the fixing step, one distal end side structure 5 selected from the distal end side structure 5 and one proximal end structure 6 selected from a plurality of types of proximal end side structures 6 are combined. And fix them. This makes it possible to easily manufacture various variations of the gas sensor 1 in which the combinations of the distal end side structure 5 and the proximal end side structure 6 are different from each other.
For example, as shown in FIGS. 10 and 11, the distal-side structure 5 is made the same as that shown in FIGS. 1 to 5, and the proximal-side structure 6 a shown in FIGS. It is possible to fix the base end-side structure 6b having a different structure.

1 to 5 is formed of a ventilation filter 63 disposed in the center of the seal member 61 and a cylindrical member 65 having a through hole 64, and these through holes 64 are used. And the air passes through the ventilation filter 63.
On the other hand, the ventilation structure used for the proximal-side structure 6b in FIGS. 10 and 11 includes a ventilation filter 63 attached between the first proximal-side cover 631 and the second proximal-side cover 632, The first base end side cover 631 and the through hole 63 h formed in the second base end side cover 632 are formed. The air passes through the through holes 63h and the ventilation filter 63.

Further, in this example, as shown in FIGS. 1 and 2, the contact unit cover 4 protrudes radially inward at a cylindrical portion 40 that fits outside the housing 11 and a base end portion 40 b of the cylindrical portion 40. And a shoulder 41. The shoulder 41 supports the contact unit 3 from the base end side.
If it does in this way, since the contact unit 3 is supported from the base end side by the shoulder part 41, it can prevent by the shoulder part 41 that the contact unit 3 and the main-body part 12 isolate | separate. Therefore, the front end side structure 5 in which the contact unit 3, the main body 12, and the contact unit cover 4 are integrated can be easily manufactured.

In this example, as shown in FIGS. 1 and 2, the elastic member 13 is interposed between the shoulder portion 41 and the contact unit 3.
In this way, the elastic member 13 can absorb the difference in coefficient of thermal expansion between the contact unit cover 4 and the base end side insulator 30. That is, when the contact unit cover 4 is made of metal, the contact unit cover 4 expands as the temperature rises, but the proximal-side insulator 30 does not expand so much, so if the elastic member 13 is not provided, In some cases, a gap is formed between the shoulder 41 and the proximal insulator 30 and there is a risk of rattling. However, by providing the elastic member 13 between the shoulder portion 41 and the base end side insulator 30, the base end side insulator 30 can be urged toward the front end side, so that rattling can be prevented.

  Further, if the elastic member 13 is made of a heat resistant spring material such as Inconel 718 or SUS631, the elastic member 13 does not sag even when the gas sensor 1 is exposed to a high temperature environment, and the proximal end insulator 30 is Prevents rattling.

On the other hand, in this example, the contact unit cover 4 and the base end side cover 60 are made of the same metal material (for example, SUS304). By constituting these with the same material, it becomes easy to perform welding.
Alternatively, the elastic member 13 may not be disposed, and the contact unit cover 4 may be made of a spring material such as Inconel 718 or SUS631, so that the contact unit cover 4 also functions as the elastic member 13. In this case, since the elastic member 13 can be omitted, there is an advantage that the number of parts can be reduced.

  As described above, according to this example, it is possible to provide a gas sensor that can easily change the combination of the base-end-side structure and the main body and a manufacturing method thereof.

(Example 2)
In this example, the welding structure of the base end side cover 60 is changed. In this example, as shown in FIG. 12, the contact unit cover 4 is welded in the vicinity of the caulking portion 110 of the housing 11. As shown in FIG. 13, the base end side cover 60 is externally fitted to the housing 11, and the front end portion 602 of the base end side cover 60 is welded to the housing 11.
Moreover, this example can also be made like FIG. In the example of FIG. 14, the contact unit cover 4 is fitted on the base end side portion of the housing 11 and welded. Then, as shown in FIG. 15, the base end side cover 60 is externally fitted to the housing 11, and the base end side cover 60 is welded to the housing 11 on the front end side of the welding part 450 of the contact unit cover 4.
In addition, the same configuration as that of the first embodiment is provided.

  The effect of this example will be described. With the above structure, the base end side cover 60 and the housing 11 can be directly welded. Therefore, welding quality can be stabilized. In addition, variation in press-fitting load when the base end side cover 60 is press-fitted into the housing 11 is reduced. Furthermore, power control during welding can be performed easily.

DESCRIPTION OF SYMBOLS 1 Gas sensor 10 Holding insulator 11 Housing 12 Main body part 2 Gas sensor element 3 Contact unit 30 Base end side insulator 31 Contact member 4 Contact unit cover 5 Front end side structure 6 Base end side structure 60 Base end side cover 61 Seal member 62 Wiring (Lead wire)
63 Ventilation filter

Claims (3)

A main body comprising a gas sensor element for detecting a specific gas concentration in the gas to be measured, a holding insulator for inserting and holding the gas sensor element inside, and a housing for holding the holding insulator inside;
A contact unit consisting of a base end side insulator attached to the base end portion of the gas sensor element, and a contact member held by the base end side insulator and electrically connected to the electrode terminal of the gas sensor element;
A contact unit cover that is formed in a cylindrical shape, covers the contact unit from the outer periphery, is fitted and fixed to the housing, and is integrated with the contact unit and the main body to form a distal-end-side structure;
A cylindrical base end cover, a seal member that seals the base end opening of the base end cover, wiring that is inserted through the seal member and connected to the contact member, and the base cover A proximal side structure including a ventilation filter having both breathability and waterproofness between the outside and the inside;
The proximal side structure is fixed to the distal side structure ,
The contact unit cover includes a cylindrical portion that is externally fitted and fixed to the housing, and a shoulder that protrudes radially inward from a proximal end portion of the tubular portion and supports the contact unit from the proximal end side. ,
The base end side cover is externally fitted to the cylindrical portion,
The gas sensor according to claim 1, wherein the base end side cover is welded to the cylindrical portion or the housing . The gas sensor according to claim 1, wherein an elastic member is interposed between the shoulder and the contact unit. The gas sensor manufacturing method according to claim 1 or 2 , wherein a front-end-side structure manufacturing step of manufacturing the front-end-side structure in which the main body, the contact unit, and the contact unit cover are integrated. ,
A base end side structure manufacturing step for manufacturing the base end side structure;
A fixing step of fixing the proximal side structure to the distal side structure after performing the distal side structure manufacturing step and the proximal side structure manufacturing step;
A method for manufacturing a gas sensor.

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