JP2000314716A - Oxygen sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent short circuit and disconnection of wire of electrode connecting fittings when assembled and during operation by providing a ceramic separator having storage parts formed to hold the electrode connecting fittings. SOLUTION: The rear end side aperture part of a filter assembly of an oxygen sensor is sealed with rubber or the like, and a ceramic separator 18 is provided inside. A storage hole 72a of the ceramic filter 18 is formed of connecting fitting storage parts 72b, 72c for inserting and holding electrode connecting fittings 23, 33 respectively, heating body terminal storage parts 72d, 72d, and a center communicating part 72e for communicating these storage parts. Leader line parts of the connecting fittings 23, 33 are positively held to the corresponding storage parts 72b, 72c respectively at a total of three points which are the lateral side edges and protruding part. This constitution prevents an ill condition such as short circuit caused by the connecting fittings 23, 33 projecting when assembled, to come in contact with each other or with other electric wiring or the like, and insulating coating for preventing contact can be omitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxygen sensor for detecting oxygen in a gas to be measured, for example, an exhaust gas of an internal combustion engine.

[0002]

2. Description of the Related Art As one form of such an oxygen sensor,
2. Description of the Related Art There is known an oxygen detecting element having a hollow shaft shape with a closed end and having an electrode layer on each of the inner and outer surfaces.
In recent years, with the prosperity of the automobile industry, demand for oxygen sensors has increased, and demands for price reduction have been increasing year by year. The oxygen sensor has a large number of components among the electrical components for automobiles, and how to simplify the assembly process is an important key to reducing the manufacturing cost. To this end, technical improvements on the production equipment side, such as automation of the assembly process, are necessary, but it is also important to devise a sensor structure that is advantageous in reducing the number of steps.

[0003]

For example, in an oxygen sensor of the type described above, a first connection fitting (internal electrode connection fitting) and a second connection fitting (external electrode connection fitting) are provided on an internal electrode layer and an external electrode layer of an oxygen detecting element. ) Are electrically connected to each other, and both connection fittings are guided to a housing hole of the ceramic separator located behind the oxygen detection element (in a direction opposite to the tip in the axial direction of the oxygen detection element). Both connecting metal fittings are respectively inserted into the first accommodating portion (internal electrode connecting metal accommodating portion) and the second accommodating portion (external electrode connecting metal accommodating portion) of the accommodating hole from the front side (the end in the axial direction of the oxygen detection element) to the rear side. And is electrically connected to each lead wire via a connector to take out an output.

However, in such an oxygen sensor, both fittings protrude from the respective housing portions and come into contact with each other at the time of assembling, or come into contact with another electric wiring or the like (for example, a terminal portion of a heating element or a lead wire). There was a problem that was easy to short-circuit. Further, even during operation of the internal combustion engine (for example, while the vehicle is running), there have been problems such as jumping out of the fitting due to vibration and short-circuit, and disconnection of both connecting fittings due to repeated vibration.

[0005] It is an object of the present invention to provide a sensor structure for preventing short-circuit and disconnection of both connection fittings during assembly and during operation.

[0006]

In order to solve the above problems, an oxygen sensor according to the present invention has a hollow shaft shape with a closed end, and has an inner electrode layer and an outer electrode formed on an inner surface and an outer surface, respectively. An oxygen detection element having a layer formed thereon, and a first connection metal fitting and a second connection metal fitting which are arranged behind the oxygen detection element and electrically connected to the internal electrode layer and the external electrode layer, respectively. An accommodation hole is formed having a first accommodation portion and a second accommodation portion that are inserted and held from the front side to the rear side in the axial direction, and a central communication portion located between the two accommodation portions and communicating the two. And the two receiving portions each have an opening facing the central communication portion, and the cross-sectional shape becomes wider than the opening in the depth direction opposite to the central communication portion. Space surrounded by partition walls At least one of the two connection fittings has a lead line portion having a width wider than the opening, and a protrusion protruding from the lead line portion in the depth direction. I do.

According to the present invention, for example, since the left and right edges and the protruding portion of the lead wire portion are in contact with the inner surface of the partition wall, the lead wire portion of the connection fitting is reliably formed at a total of three points of the left and right side edges and the protruding portion. Is held in the accommodating portion corresponding to the above, so that a problem that the connecting fittings protrude from the accommodating portion and come into contact with each other or another electric wiring or the like and short-circuit at the time of assembling is less likely to occur.
Also, an insulating coating for preventing contact can be omitted, which contributes to a reduction in the number of parts. In addition, short-circuiting due to jumping out of the housing portion due to vibration during operation is less likely to occur, and the problem of disconnection of the connection fitting due to repeated vibration can be prevented or suppressed.

The projecting portion can be elastically urged in a direction in which the right and left edges of the lead wire portion are pressed against the inner surface of the partition wall by being compressed and deformed in the housing portion. Due to the elastic biasing force of the protruding portion, the lead wire portion is more stably held in the housing portion.

The partition has a narrow opening facing the central communication portion, a wide bottom portion located on the opposite side to the central communication portion,
The bottom portion and the opening portion may be formed of an inclined portion which is continuously provided on both sides in the width direction. In the form that the left and right edges of the leader line abut on the corresponding slopes,
This can be held more stably. In this case, in the axial section of the ceramic separator, the accommodation portion has a maximum dimension in the depth direction as D, and a maximum width dimension in the direction orthogonal thereto as W2, W2> D
It can be. By making the width dimension larger than the depth dimension, the lead wire part can be held more stably, and the width of the lead wire part with respect to the depth dimension of the housing part can be made larger. Jumping out can be more effectively prevented. Further, when the projecting portion is elastically deformed by compression, the amount of elastic deformation can be easily increased as the dimension in the depth direction becomes shorter, and the stability of holding the lead wire portion in the housing portion is further improved.

Next, at least one of the left and right side edges of the lead wire portion can be formed as an inclined side edge that becomes gradually wider from the rear side to the front side. This makes it difficult for the connecting fittings to be caught when assembling the connecting fittings, so that the fittings can be smoothly inserted into the respective housing portions. Further, the occurrence of torsion during operation can be prevented.

The projecting portion extends in a predetermined direction from the base end,
A cut is formed in the lead line portion through the direction changing portion to the other end, and the tongue located inside the cut can be formed by raising the tongue in the depth direction. According to this configuration,
Although it has a simple structure, the elastically deformable protrusion can be easily formed, and by providing elasticity to the protrusion, the lead wire portion can be reliably pressed against the partition wall of each storage portion. In this case, the protruding portion can be formed by positioning the raised fulcrum on the rear side in the axial direction and raising the portion of the tongue piece located on the front side of the raised fulcrum. According to this, when inserting the lead wire portion from the front side to the rear side in the axial direction in the housing portion and assembling the same, the raised tongue piece is caught on the edge of the opening end face which is the insertion side of the housing portion. Trouble is less likely to occur, and assembly can be performed smoothly.

[0012]

Embodiments of the present invention will be described below with reference to embodiments shown in the drawings. FIG. 1 shows the internal structure of the oxygen sensor of the present invention, and FIG. 2 is an enlarged view of a main part. The oxygen sensor 1 includes an oxygen detecting element 2 which is a hollow shaft-shaped solid electrolyte member having a closed end, and a hollow portion 2a of the oxygen detecting element 2.
And a heat generating element 3 inserted into the heat generating element. The oxygen detection element 2
It is formed hollow by an oxygen ion conductive solid electrolyte mainly composed of zirconia or the like. Further, a metal casing 10 is provided outside the intermediate portion of the oxygen detection element 2 via insulators 6 and 7 formed of insulating ceramic and ceramic powder 8 formed of talc. In the following description, the side (closed side) toward the axial end of the oxygen detection element 2 is referred to as “front side”, and the side toward the opposite direction is referred to as “rear side”.

The casing 10 includes a metal shell 9 having a screw portion 9b for mounting the oxygen sensor 1 to a mounting portion such as an exhaust pipe, and a main body 9 connected to an opening on the rear side of the metal shell 9 so as to communicate with the inside. It includes a cylinder 14, a protector 11 attached to cover a front opening of the metal shell 9, and the like. The oxygen sensor 1 of the present invention is located forward of the screw 9b (FIG. 1).
Is located in an engine such as an exhaust pipe, and the rear (upper in FIG. 1) is located in the outside atmosphere and used. As shown in FIG. 2, the outer surface of the oxygen detecting element 2 and the inner surface of the hollow portion 2a are formed on the outer electrode layer 2b and the inner electrode layer made of porous material such as Pt or Pt alloy so as to cover almost the entire surface. 2c is provided.

At the opening on the rear side of the metal shell 9, the aforementioned main cylinder 14 is caulked with the insulator 6 via a ring 15, and a cylindrical filter assembly 16 is attached to the main cylinder 14 outside. Is fitted and fixed. The rear end opening of the filter assembly 16 is sealed with a grommet 17 made of rubber or the like, and a ceramic separator 18 is further provided further inward. Then, lead wires 20 and 21 for the oxygen detecting element 2 and a lead wire (not shown) for the heating element 3 are arranged so as to penetrate the ceramic separator 18 and the grommet 17.

The filter assembly 16 has a cylindrical shape that is substantially coaxially connected to the main cylinder 14 (casing 10) from the rear outside, and has a first filter holding portion 51 having a gas introduction hole 52, A cylindrical filter 53 configured as a water-repellent filter (for example, a porous fiber structure of polytetrafluoroethylene, etc.) is connected to the second filter holding unit having the introduction hole 55 by the filter caulking units 56 and 57. Has a structure for holding it in place. On the other hand, the grommet 17 is elastically fitted inside the rear opening of the first filter holding portion 51, and has a seal-side lead wire insertion hole 91 for inserting the respective lead wires 20, 21 and the like. The space between the outer surfaces of the lead wires 20 and 21 and the inner surface of the first filter holder 51 is sealed. FIG. 4 shows the filter assembly 1.
6 shows an assembled state. The first filter holding portion 51 of the filter assembly 16 is
The rear projecting portion of the main body 14 enters and covers the inside of the second portion 62, and abuts against the separator-side support portion 73 at the stepped portion 60 from the side opposite to the main cylinder 14 via the corrugated washer 74. Are arranged as follows. On the other hand, the first filter holding portion 51 is disposed so as to overlap with the main cylinder 14 (casing 10) from the outside at the tip end side, that is, the first portion 61, and the overlapping portion includes
A casing caulking portion 76 that connects the first filter holding portion 51 to the main cylinder 14 in an airtight state is formed.

Next, a plurality of separator-side lead wire insertion holes 72 for inserting the respective lead wires 20, 21 and the like are formed in the ceramic separator 18 so as to penetrate in the axial direction. Is formed with a flange-shaped separator-side support portion 73 projecting from the outer peripheral surface. Then, as shown in FIG. 2, the ceramic separator 18 has a portion located on the front side of the separator-side support portion 73 inserted inside the rear end portion of the main cylinder 14, and the front end face 73 a of the separator-side support portion 73 is By contacting the rear end surface of the main cylinder 14 (main cylinder side support portion 90), the portion located rearward of the separator side support portion 73 becomes the main cylinder 1.
4 is arranged in a state of protruding outside.

One lead wire 20 for the oxygen detecting element 2
The internal electrode of the oxygen detecting element 2 described above passes through an internal electrode connecting metal member 23 (first connecting metal member) including a connector 23a, a lead wire portion 23b, a metal body main portion 23a, and a heating element grip portion 23d formed integrally with each other. It is electrically connected to the layer 2c (FIG. 2). On the other hand, the other lead wire 21 has a connector 33a and a lead wire portion 33b formed integrally with each other.
Electrode connection metal fitting 33 having a metal body 33c and a metal body 33c
Through the (second connection fitting), it is electrically connected to the external electrode layer 2b (FIG. 2) of the oxygen detection element 2. The oxygen detecting element 2 is activated by being heated by the heating element 3 arranged inside. The heating element 3 is a rod-shaped ceramic heater, and includes a heating section 3a having a resistance heating wire section (not shown).
By being energized via lead wires (not shown) connected to the positive electrode side and the negative electrode side heating element terminal portions 3b, 3b,
The tip (detection section) of the oxygen detection element 2 is heated.

As shown in FIG.
The outer surface of the heating element 3 is gripped by the inner surface of the heating element grip portion 23d formed on the distal end side, and the inner electrode connection fitting 23 and the heating element are formed by contact between the outer surface of the fitting body 23c and the inner surface of the oxygen detection element 2. It serves to fix the position of the body 3 in the axial direction. One end of the lead wire portion 23b is
The connector 23a is integrated so as to be connected to one circumferential position of c, and the connector 23a is integrated at the other end.

The heating element grip 23d has a C-shaped cross section surrounding the heating element 3. When the heating element 3 is not inserted, the heating element 3 has an inner diameter slightly smaller than the outer diameter of the heating element 3 and elastically expands with the insertion of the heating element 3 to grip the heating element 3 by its frictional force. I do.

The metal fitting body 23c surrounds the heating element 3 by bending a plate-like portion having a plurality of saw-tooth-shaped contact portions 23e formed on both right and left edges thereof into a cylindrical shape. (That is, the heating element 3 is inserted). Then, the internal electrode connection fitting 23 and the heating element 3 are hollowed by the frictional force between the outer peripheral surface and the contact portion 23e of the metal fitting main body 23c and the inner wall surface (the inner surface of the internal electrode layer 2c) of the hollow portion 2a of the oxygen detection element 2. In addition to the role of positioning in the axial direction with respect to the portion 2a, the plurality of contact portions 23
At each of the tips e, contact and conduction with the inner surface of the internal electrode layer 2c are made.

On the other hand, the external electrode connection fitting 33 has a cylindrical fitting body 33c and a lead wire 33b.
Is integrated with one end of the metal fitting body 33c in a circumferential direction, and a connector 33a is integrated with the other end. On the other hand, on the side opposite to the connection point of the lead wire portion 33b across the center axis, a slit 3 in the axial direction is provided.
3e is formed. The rear end of the oxygen detecting element 2 is inserted into the inside of the metal fitting body 33c from the inside in such a manner as to elastically push the oxygen detecting element 2 apart. Specifically, a conductive layer 2f as an external output extraction portion is formed in a strip shape along the circumferential direction at the rear end portion of the outer peripheral surface of the oxygen detection element 2. The external electrode layer 2b is formed by, for example, electroless plating.
The entire surface of the main part on the front end side of the engagement flange 2s of the oxygen detection element 2 is covered. On the other hand, the conductive layer 2f
For example, it is formed by pattern formation and baking using a metal paste, and is electrically connected to the external electrode layer 2b via the similarly formed connection pattern layer 2d in the axial direction.

It should be noted that the oxygen detection element 2
For example, if an insertion guide portion 33f that opens outward along the circumferential direction is formed in the opening on the insertion side, it is difficult for the insertion to be caught at the time of insertion and the assembly can be performed more smoothly. Further, for the same purpose, a chamfered portion 2g can be formed at the outer edge of the opening of the oxygen detection element 2.

In the oxygen sensor 1, the rear end face of the ceramic separator 18 is located rearward of the gas introduction hole 52 in the axial direction, and a predetermined gap 98 is formed between the grommet 17 and the ceramic separator 18. Have been. Also, a gap 9 is provided between the inner peripheral surface of the first filter holding portion 51 and the outer peripheral surface of the ceramic separator 18.
2 are formed. Then, the gas from the gas introduction hole 52 is supplied into the gap 92, and further guided into the casing 10 through the gap K formed between the separator-side lead wire insertion hole 72 and the lead wire. 2 (internal electrode layer 2c). On the other hand, the exhaust gas introduced through the gas permeation port 12 of the protector 11 comes into contact with the outer surface of the oxygen detecting element 2, and the oxygen detecting cell 2 starts to contact the oxygen detecting element 2 according to the oxygen concentration difference between the inner and outer surfaces. Power is generated. The oxygen concentration cell electromotive force is extracted from the inner and outer electrode layers 2c and 2b (FIG. 2) through the fittings 23 and 33 and the lead wires 20 and 21 as a detection signal of the oxygen concentration in the exhaust gas. Oxygen concentration in gas can be detected.

FIG. 5 shows the details of the ceramic separator 18. The ceramic separator 18 has a rear end side (FIG. 5).
(C) Four lead wire insertion holes 72 are penetrated from the upper end side at approximately 90 ° intervals along a pitch circle P centered on the central axis O. As shown in FIGS. 5C and 5D, the front end of the ceramic separator 18 in the axial direction (FIG.
The lower end 18a is formed with a receiving hole 72a along the axial direction from the bottom surface 18e located substantially at the center of the entire length (that is, the intermediate portion of the separator-side support portion 73). The receiving hole 72a is provided with a lead wire portion 23b of the internal electrode connection fitting 23,
The lead wire portion 33b of the external electrode connection bracket 33, the heating element terminal portion 3b on the + pole side, the heating element terminal portion 3b on the-pole side, and the housing portion into which the heating element 3 is inserted are divided by the partition wall 18a. (Detailed shapes of the partition wall 18a and the accommodation hole 72a will be described later with reference to FIG. 8). The four lead wires 20, 21 electrically connected to the lead wire portions 23b, 33b and the heating element terminal portions 3b, 3b are pulled out rearward through the respective lead wire insertion holes 72. In addition, the bottom surface 18e forms a rectangular pillar-shaped rising tip and is chamfered around the periphery, for example, due to the following circumstances. That is, when a molded body of the ceramic separator 18 before firing is manufactured by die molding, the housing hole 72a and the lead wire insertion hole 72 are often formed by separate mandrels. At this time, the mating surfaces of these mandrels are located on the outer peripheral edge of the bottom surface 18e, and powder may be pressed into gaps between the mating surfaces to generate burrs on the molded body. Therefore, if the periphery of the bottom surface 18e is chamfered, even if burrs are generated, it is possible to prevent a problem that fragments or the like adhere to the bottom surface 18e to form unnecessary protrusions or the like. .

As shown in FIG. 5B, the rear end of the metal fitting body 33c of the external electrode connecting metal fitting 33 is formed at the opening end face (front end face) of the housing hole 72a of the ceramic separator 18 by the partition wall 18a. Is in contact with the front end face of the On the other hand, the rear end edge of the metal body 23c of the internal electrode connection metal 23 contacts the front end face of the partition wall 18a inside the metal body 33c of the external electrode connection metal 33 and the pitch circle P. The partition walls 18a formed between the adjacent lead wire insertion holes 72, 72 are formed so as to protrude inward from the pitch circle P, respectively. The rear end of the heating element 3 extends from the front end side of the housing hole 72a along the axis along the bottom surface 18e.
The entire length of the oxygen sensor 1 is shortened, and the size of the sensor is reduced.

FIG. 6 shows details of the internal electrode connection fitting 23 (first connection fitting). A conductive thin plate having a thickness t is punched out as shown in a developed view of FIG. 3C, and a connector 23a, a lead wire portion 23b, a metal fitting body portion 23c, and a heating element grip portion 23d.
Form an integral internal electrode connection fitting 23. The metal fitting main body 23c is formed in a cylindrical shape so as to generate a frictional force with the inner wall surface of the oxygen detection element 2 together with the contact part 23e, and the heating element gripping part 23d is formed.
Is bent into a C-shape having an inner diameter slightly smaller than the outer diameter of the heating element 3, and the connector 23 a is bent so that its peripheral portion is raised.

The lead wire portion 23b inserted into the internal electrode connection fitting accommodating portion 72b (first accommodating portion) of the ceramic separator 18 connects the upper portion 231 connected to the connector 23a, the lower portion 23n connected to the fitting main portion 23c, and both. It is composed of a central portion 23m and has the following shape. From the upper part 231 to the central part 23m, an enlarged edge part 23k (inclined side edge) is formed that gradually widens on both sides, and the central part 23m has an inclined edge part 23t (inclined side) whose width w becomes wider toward the lower side (front). Edges) having reduced widths from both sides between the central portion 23m and the lower portion 23n and between the lower portion 23n and the metal fitting body 23c.
s ′ are provided. Further, in the central portion 23m, a notch 23h 'having an opening at an upper portion and having a turning portion below (an upward U-shape in the figure) is provided in advance over the length l and the width w' along the center line at the time of punching. After bending, the tongue of the notch 23h 'is turned to the opposite side to the bending direction of the metal fitting main body 23c.
The protrusion 23h is formed only by raising the protrusion. Lead wire part 2
When 3b is inserted into the internal electrode connection fitting receiving portion 72b of the ceramic separator 18, the left and right enlarged edges 23k or the inclined edges 23t of the central portion 23m are connected to the connection fitting receiving portion 72b.
b and engages a part of the partition wall 18a,
The lower end of the protrusion 23h engages with another portion of the partition 18a (see FIG. 8).

FIG. 7 shows details of the external electrode connection fitting 33 (second connection fitting). A conductive thin plate having a thickness t is punched out as shown in a developed view of FIG. 3C, and a connector 33a, a lead wire portion 33b, and a bracket main body 33c form an integral external electrode connection bracket 33. The metal fitting body 33c has a cylindrical shape having an inner diameter slightly smaller than the outer diameter of the rear end of the oxygen detection element 2,
The connector 33a is bent so that its peripheral portion is upright. An axial slit 33e is formed on the opposite side of the center axis from the connection point of the lead wire portion 33b. In the opening of the metal fitting body 33c on the side where the oxygen detection element 2 is inserted,
An insertion guide portion 33f is formed to open outward along the circumferential direction.

The lead wire portion 33b inserted into the external electrode connection fitting accommodating portion 72c (second accommodating portion) of the ceramic separator 18 connects the upper portion 331 connected to the connector 33a, the lower portion 33n connected to the fitting body portion 33c, and both. It is composed of a central portion 33m and has the following shape. From the upper portion 331 to the central portion 33m, an enlarged edge 33k (inclined side edge) whose width gradually expands on both sides is formed, and the central portion 33m has an inclined edge portion 33t (inclined side) whose width w becomes wider toward the lower side (front). Edge 3) between the central part 33m and the lower part 33n, the width of which is reduced from both sides.
3s are provided. Further, in the central portion 33m, a notch 33h 'having an opening at the upper portion and having a turning portion below (an upward U-shape in the figure) is provided over the length l and the width w' along the center line in advance at the time of punching. And a notch 3 on the opposite side to the bending direction of the metal body 33c after bending.
The protruding portion 33h is formed by raising the tongue 3h 'at the center of the upper opening and lowering the lower portion by an angle θ1. The lead wire portion 33b is connected to the external electrode connection fitting accommodating portion 72 of the ceramic separator 18.
c, the right and left enlarged edges 3 of the central portion 33m
3k or the inclined edge 33t engages with a part of the partition wall 18a forming the connection fitting accommodating portion 72c, and the projection 3
3h engages with the other part of the partition wall 18a (FIG. 8).
reference). Note that, as shown in FIG. 7A, the lead wire portion 33b and the connector 33a of the external electrode connection fitting 33 have an inclination angle θ2 with respect to the center line of the fitting main body 33c. The reason why the inclination angle θ2 that is not provided in the internal electrode connection fitting 23 is provided is that the external electrode connection fitting 33 is prevented from floating when inserted into the ceramic separator 18 and the insertion into the oxygen detection element 2 is performed more smoothly. It is to be.

FIG. 8 is a cross-sectional view taken along the line CC of FIG. 2 and an enlarged view thereof, showing the positional relationship between the receiving hole 72a and the two connection fittings 23, 33. Four separator-side lead wire insertion holes 72 are formed in the ceramic separator 18 so as to penetrate in the axial direction, and in the first half of the ceramic separator 18, they overlap with the accommodation holes 72 a inside. The accommodating hole 72a is provided with an internal electrode connecting metal housing 72b (a second connecting metal housing) for inserting and holding the internal electrode connecting metal 23 (first connecting metal) and the external electrode connecting metal 33 (second connecting metal) from the front side to the rear side, respectively. Heating element terminal housing for inserting and holding the positive electrode side and negative electrode side heating element terminals 3b, 3b from the front side to the rear side, respectively. It is formed of parts 72d, 72d, and a central communication part 72e located between these four accommodation parts and communicating the four persons. Both connecting metal fittings receiving section 72
b, 72c and the two heating element terminal receiving portions 72d, 72d face each other with the central communicating portion 72e interposed therebetween, and have the same positional relationship as the separator side lead wire insertion holes 72 arranged at intervals of approximately 90 ° along the pitch circle P. And the respective insertion holes corresponding to the respective accommodating portions are overlapped (included) when viewed from the front end side. In the embodiment shown in FIG. 8, the central communication portion 72e also serves as a heating element housing, and the heating element 3 is inserted up to just before the bottom surface 18e, contributing to the downsizing of the oxygen sensor 1.

The internal electrode connection fitting accommodating portion 72b has a narrow opening 18d facing the central communication portion 72e, a wide bottom portion 18b extending in the outer peripheral direction (depth direction) opposite to the central communication portion 72e, The opening width (distance between walls) is gradually increased from the opening 18d to the bottom 18b, and is formed as a space surrounded by a partition 18a formed by an inclined portion 18c connecting both of them (FIG. 8 (b)). )reference). As a whole, the internal electrode connection fitting accommodating portion 72b is partially connected to the central communication portion 72e.
It has the shape of a shell or osubi which is open to the
It has a shape close to an ellipse. The maximum dimension D in the depth direction is set to be smaller than the maximum dimension w2 in the width direction orthogonal to this.

When the internal electrode connection fitting 23 is inserted into the internal electrode connection fitting receiving portion 72b, the lead wire portion 23
b stays in the accommodation portion 72b (see FIG. 2).
At this time, the width w of the central portion 23m is larger than the width (minimum width) W1 of the opening 18d, and the width (maximum width) of the bottom portion 18b.
Since it is smaller than W2, the enlarged edge 23k or the inclined edge 2
3t contacts the inclined portion 18c of the partition wall 18a, and
b from the front end to the back (from the front of the paper to the back)
Moving. When the lead wire 23b is inserted at the front end of the housing portion 72b, a projecting portion 23h protruding from the lead wire 23b toward the bottom 18b is pressed by an outer peripheral portion of the bottom 18b, so that a repulsive force (spring force) is exerted. ), And the lead wire portion 23
b is securely supported at three points: both side edges of the enlarged edge 23k or the inclined edge 23t and the lower edge (front edge) of the protruding portion 23h.
The problem of short-circuiting by protruding from the outer electrode 2b and coming into contact with the external electrode connection fitting 33 or other electric wiring or the like is less likely to occur. Also, there is no need for an insulating coating for preventing contact. Further, short-circuiting due to jumping out of the housing portion 72b due to vibration during operation is less likely to occur, and disconnection of the connection fitting 23 due to repeated vibration can be prevented.

In FIG. 8B, the maximum width W2 / minimum width W1 =
1.6 to 2.3, total depth (maximum depth) D / effective depth d =
1.6 to 2.2 is desirable. As shown, D / d =
2, that is, when the lead wire portion 23b is located in the vicinity of the pitch circle, electrical connection from the connection fitting 23 to the lead wire 20 is not excessively performed, and the risk of disconnection is reduced. Up to this point, only the internal electrode connection metal housing 72b and the internal electrode connection metal 23 have been described. However, the same applies to the relationship between the external electrode connection metal housing 72c and the external electrode connection metal 33, and a description thereof will be omitted. However, it is not necessary to make them all symmetrical as shown in FIG. 8 (a). For example, the external electrode connection fitting receiving portion 72c may have a slightly angular cross-sectional shape like the heating element terminal receiving portion 72d, or the external electrode connection fitting 33 may be used.
The lead wire portion 33b and the protruding portion 33h of the internal electrode connection fitting 23 may have a different shape and size from those of the lead wire portion 23b and the protruding portion 23h of the internal electrode connection fitting 23. Absent. When such a change is made, a connection error can be prevented. The present invention may or may not be carried out for the heating element terminal receiving portions 72d.

Hereinafter, a method of manufacturing the oxygen sensor 1 will be described. First, as shown in FIG. 9A, the metal elastic member 74 is extrapolated to the ceramic separator 18. And
As shown in FIG. 4, the ceramic separator 18, the internal electrode connection metal fittings 23, the external electrode connection metal fittings 33, the heating element 3 and the like are mounted on the front side of the filter assembly 16 pre-assembled, and the grommet 17 and the like are mounted on the rear side. At this time, the lead wires 20 and 21 connected to the connectors 23a and 33a of the connection fittings 23 and 33 and the lead wires (not shown) connected to the positive electrode side and the negative electrode side heating element terminal portions 3b and 3b. Are respectively inserted through the separator-side lead wire insertion holes 72 of the ceramic separator 18, and further through the seal-side lead wire insertion holes 91 of the grommet 17 fitted into the rear end side opening of the first filter holding portion 51, to the rear side. Has been extended. The ceramic separator 18 is moved to the front side, and the leading wire portions 23b, 33 are formed at the front end of the accommodation hole 72a.
b, when inserting the partition wall 1 from the lead wire portions 23b and 33b.
Protruding portion 23h protruding toward 8a (bottom portion 18b);
33h is pressed by the outer peripheral portion of the partition wall 18a (bottom portion 18b) to generate a repulsive force (spring force), and the lead wire portion 23
b, 33b are enlarged edges 23k, 33k or inclined edges 23
3 and the lower edge (front edge) of the projection 23h.
It is definitely supported in point.

Subsequently, as shown in FIG. 9B, the filter assembly 16 is moved inside the stepped portion 60 while the lead wires 20 and 21 are slid in the seal-side lead wire insertion holes 91 of the grommet 17. Is moved to a position where it contacts the ring-shaped metal elastic member 74, and covers the outside of the ceramic separator 18. For example, even if the filter assembly 16 is slid over a bundle of the lead wires 20 and 21 with a slight inclination, the inner edge of the opening of the first filter holding portion 51 and the lead wires 20 and 21 may be removed.
Since the rubber grommet 17 is interposed between the grommet 17 and the like, there is no fear that the jackets of the lead wires 20 and 21 are cut off at the opening edge.

In this state, as shown in FIG. 9C, the protective cover 64 and the second portion 6 of the first filter holding portion 51 are formed.
By crimping the rear end side overlapping portion 2 toward the inner grommet 17 along the circumferential direction, the grommet crimping portion 6 is formed.
7 is formed. On the other hand, the oxygen detection element 2 is assembled in the main cylinder 14 in advance.

Then, as shown in FIG. 10A, the heating element 3 is inserted into the hollow portion 2a of the oxygen detecting element 2 from the tip end side, and the first filter holding portion 51 of the filter assembly 16 is inserted.
Is placed on the main cylinder 14, and the ceramic separator 18 is made to approach in the axial direction toward the rear end of the oxygen detection element 2. Thereby, the metal fitting body 33c of the external electrode connecting metal fitting 33,
The fitting main body 23c of the internal electrode connecting fitting 23 is positioned at the opening of the oxygen detection element 2. And
In this state, the two metal fitting main bodies 33c and 23c are provided on the front end surface of the ceramic separator 18 (the lower end surface of the partition wall 18a in FIG. 5).
The ceramic separator 18 is further moved in the axial direction toward the oxygen detection element 2 while the rear end of the ceramic separator 18 is in contact with the rear end of the ceramic separator 18.

As a result, as shown in FIG. 2, the rear end of the oxygen detecting element 2 is relatively pushed into the inside of the fitting main body 33c, and the fitting main body 23c is pushed into the inside of the oxygen detecting element 2. . At this time, both metal fitting main body parts 33
Since the rear end edges of c and 23c are in contact with the front end surface of the ceramic separator 18, smooth assembly can be achieved without causing drawbacks such as buckling of the lead wire portions 33b and 23b due to the axial pushing force. ing.

In FIG. 10B, the first filter holding portion 51 and the main cylinder 14 are pressed in the axial direction to compress and deform the metal elastic member 74. The assembly is completed by forming the casing caulking portion 76 with the cylinder 14 and connecting the two.

The receiving hole 72a and the two connection fittings 2 according to the present invention
The following changes are conceivable for the positional relationship with 3, 33. Although the housing hole 72a is formed only in the first half of the ceramic separator 18 so as to overlap with the four separator-side lead wire insertion holes 72 provided through in the axial direction, the housing hole 72a is shown. The reference numeral 72a may be formed over the entire length of the ceramic separator 18 in the axial direction (front-back direction). The partition 18a may have an inclination in the axial direction (front-back direction). The inclination at this time shall gradually increase from the rear side to the front side, and is in the same direction as the enlarged edges 23k, 33k and the inclined edges 23t, 33t of the leader lines 23b, 33b. The inclination of the partition wall 18a can be applied by using the die-cutting taper at the time of manufacturing the ceramic separator 18 as it is or by slightly increasing the gradient of the die-cutting taper. By providing a slope (regardless of whether it is linear or curved) on the partition wall 18a or the lead wire portions 23b and 33b,
Insertion of the lead wire portion 18a into the accommodation hole 72a can be performed smoothly. Although the example in which the central communication portion 72e is also used as the heating element housing portion and the example in which the housing hole 72a includes the heating element terminal housing portions 72d, 72d are shown, the invention is not limited thereto.
(See (a)). The shape of the two connection fitting accommodating portions 72b and 72c is not limited to the shell shape, but may be a trapezoidal shape surrounded by a straight line, a circular shape, an elliptical shape, another curved shape, or a combination thereof. The separator-side lead wire insertion hole 72 that penetrates through the ceramic separator 18 can be used as it is as the two connection fitting accommodating portions 72b and 72c at the front end side (see FIG. 11A). When the partition wall 18a and the lead line portions 23b and 33b are in surface contact rather than point (line) contact, the holding is more stable (see FIG. 11B).

FIG. 11 shows a main modification. FIG. 11 (a)
In this embodiment, the separator-side lead wire insertion hole 72 penetrating the ceramic separator 18 is used as the two connection fitting accommodating portions 72b and 72c in a substantially circular shape on the front end side, and the heating element terminal accommodating portions 72d and 72d are provided in the accommodating hole 72a.
The example which does not include is shown. The partition wall 18a can have a sufficient thickness, and is excellent in strength and durability. In FIG. 11B, shallow grooves 18f, 18f having a width W ′ and a depth D ′ are provided on both sides of the inclined portion 18c of the partition wall 18a, and the bottom 1 is formed.
8b is also provided with a shallow groove 18g having a width W "and a depth D". The lead wire portions 23b and 33b are provided with the grooves 18f and 18f,
The protruding portions 23h and 33h can be inserted into the housing portions 72b and 72c without play using the groove 18g as a guide, and have a large holding force. Note that only one of the grooves 18f and 18g may be provided. Leader lines 23b, 33 having different widths w
In order to cope with b, the grooves 18f, 18f on both sides are preferably formed stepwise. Projections 23 with different widths w '
h and 33h, the width W "of the groove 18g may be slightly widened.

Further, the lead wire portions 23b, 3
The following changes are also conceivable for the shapes of 3b and the protrusions 23h and 33h. It is possible to apply the present invention to only one of the two connection fittings 23 and 33, or to apply the lead wire portion and the projecting portion with different shapes. Inclined edges 23t, 33t of leader lines 23b, 33b
The enlarged edges 23k and 33k may not be provided, or only one of the left and right sides may be provided.
It does not matter whether it is curved or the like. Regarding the shapes of the protruding portions 23h and 33h, a bulging portion may be integrally provided by a press or a squeeze without using a cut, or a separate protruding portion may be soldered (FIG. 12D).
reference). Regarding the raised form of the protruding portions 23h and 33h, multi-step bending, curved (plane) bending, raising in the left-right direction, and the like are also possible (see FIGS. 12A, 12B, and 12C). The cuts 23h 'and 33h' of the protrusions 23h and 33h can be changed to a U-shape or the like in addition to the U-shape.

FIG. 12 shows a main modification. FIG. 12 (a)
Is provided with a first protruding portion 23h1 having an inclination angle θ1 and a second protruding portion 23h1 ′ having an inclination angle θ1 ′ in a two-step bent shape. The contact area of the second protruding portion 23h1 ′ is further increased, and the lead line is provided. Part 23
The retention of b is stabilized. FIG. 2B shows a curved protruding portion 23.
In the example in which h2 is provided, the holding force increases due to the spring effect. FIG. 11C shows an example in which an I-shaped cut is provided on the center line and two rectangular tongues are pushed right and left to form a projection 23h3. The cut may be T-shaped or inverted T-shaped, and the two triangular tongues may be pushed right and left. Alternatively, the cut may be formed in a U-shape, and the cut may be pushed open to either the left or right. (D) shows an example in which the protruding portion 23h4 is integrally expanded by a press or the like.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an oxygen sensor of the present invention.

FIG. 2 is a longitudinal sectional view showing a main part of the oxygen sensor of FIG. 1;

FIG. 3 is an exploded perspective view showing a state of being assembled to a ceramic separator.

FIG. 4 is a partial longitudinal sectional view of the filter assembly in an assembled state.

FIG. 5 is a plan view, bottom view, and A- of the ceramic separator.
A longitudinal section and BB longitudinal section.

FIG. 6 is a left side view, a front view, and a development view of the internal electrode connection fitting.

FIG. 7 is a front view, a right side view, and a development view of the external electrode connection fitting.

FIG. 8 is a cross-sectional view taken along the line CC in FIG. 2 and an enlarged view thereof.

FIG. 9 is a process explanatory view showing an example of a method of assembling the oxygen sensor of FIG. 1;

FIG. 10 is a process explanatory view following FIG. 9;

11A and 11B show a modified example of FIG. 8, wherein FIG. 11A is a cross-sectional view taken along the line CC of the first modified example, and FIG. 11B is an enlarged cross-sectional view taken along the line CC of the second modified example.

FIGS. 12A and 12B show a modified example of the protruding portion of FIG. 6, wherein FIG.
Front view of a modified example, (b) is a front view of a second modified example, (c)
FIG. 13 is a perspective view of a third modification, and (d) is a perspective view of a fourth modification.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Oxygen sensor 2 Oxygen detecting element 2a Hollow part 2b External electrode layer 2c Internal electrode layer 18 Ceramic separator 18a Partition wall 18b Bottom part 18c Inclined part 18d Opening 23 Internal electrode connection fitting (first connection fitting) 23b Lead-out part 23h Projecting part 23h 'Cut 23t Inclined edge (inclined side edge) 33k Enlarged edge (inclined side edge) 33 External electrode connector (second connector) 33b Lead wire 33h Projection 33h' Notch 33t Inclined edge (inclined edge) 33k Enlarged edge (inclined side edge) 72a Housing hole 72b Internal electrode connection metal housing (first storage) 72c External electrode connection metal housing (second storage) 72e Central communication part D Maximum depth dimension of housing W2 Maximum width of accommodation section

Claims (8)

[Claims] 1. An oxygen sensing element having a hollow shaft shape with a closed end and an inner electrode layer and an outer electrode layer formed on an inner surface and an outer surface, respectively. A first housing part and a second housing part that insert and hold the first connection fitting and the second connection fitting electrically connected to the internal electrode layer and the external electrode layer, respectively, from the front side to the rear side in the axis direction of the own. A ceramic separator formed with a housing hole having a housing portion and a central communication portion located between the two housing portions and communicating the two, the two housing portions each facing the central communication portion; It has an opening, and is formed as a space surrounded by a partition having a cross-sectional shape that is wider than the opening in a depth direction opposite to the central communication portion, and at least one of the two connection fittings One is said An oxygen sensor comprising: a lead line portion having a width wider than an opening; and a protrusion projecting from the lead line portion in the depth direction. 2. The oxygen sensor according to claim 1, wherein the lead-out line portions are held in corresponding accommodating portions so that left and right side edges of the lead-out line portions and the protruding portions contact the inner surface of the partition wall. 3. The projecting portion is configured to be elastically urged in a direction in which left and right side edges of the lead wire portion are pressed against the inner surface of the partition wall by being compressed and deformed in the housing portion. 2. The oxygen sensor according to 2. 4. The partition has a narrow opening facing the central communication portion, a wide bottom portion located on the opposite side to the central communication portion, and a width between the bottom portion and the opening. The oxygen sensor according to claim 1, wherein the oxygen sensor is formed from an inclined portion continuously provided on both sides in the direction. 5. The accommodation section in the axial section of the ceramic separator has a maximum dimension in the depth direction as D.
2. The oxygen sensor according to claim 1, wherein W2> D, where W2 is the maximum width dimension in a direction orthogonal to said direction. 6. The oxygen sensor according to claim 2, wherein at least one of the left and right side edges of the lead wire portion is formed on an inclined side edge that gradually widens from the rear side to the front side in the axial direction. . 7. The protruding portion extends in a predetermined direction from a base end portion, a cut extending from the direction changing portion to the other end is provided in the lead wire portion, and a tongue piece positioned inside the cut portion is provided. The oxygen sensor according to claim 1, wherein the oxygen sensor is formed by being raised in the depth direction. 8. The protruding portion is formed by positioning a raised fulcrum on the rear side in the axial direction, and raising a portion of the tongue piece located on a front side of the raised fulcrum. An oxygen sensor according to any of the preceding claims.