JP7149791B2 - gas sensor - Google Patents

Description

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

2. Description of the Related Art As a gas sensor for detecting concentrations of oxygen and NOx in exhaust gas from automobiles, etc., a sensor having a plate-like sensor element using a solid electrolyte is known.
In this type of gas sensor, a plurality of electrode portions (electrode pads) are provided on the outer surface of the rear end side of a plate-shaped sensor element, and terminal metal fittings are electrically contacted to each of the electrode portions to generate a sensor output from the sensor element. Devices for extracting signals to the outside and powering heaters stacked on sensor elements are widely used (Patent Document 1).

As shown in FIG. 9, in the gas sensor of Patent Document 1, the terminal fitting is a two-split type that includes a distal terminal fitting 200 and a rear terminal fitting 220 connected to the rear end of the distal terminal fitting 200. terminal metal fittings. The terminal fittings 200 and 220 are held by separators 230 and 240, respectively.
The distal terminal fitting 200 is connected to the electrode portion 300p of the sensor element 300 . A lead wire 250 is caulked and connected to the rear end side of the rear end terminal fitting 220 .
Here, the rear terminal fitting 220 has a substantially cylindrical shape, and the rear edge 221e of the central portion 221 having the maximum diameter is engaged with the stepped portion 240S in the insertion hole 240h of the separator 240, and is pushed toward the rear end side. It prevents the omission of

Japanese Patent Application Laid-Open No. 2018-9958 (Fig. 1, Fig. 11)

By the way, as shown in FIG. 10, due to processing problems of the separator 240 made of ceramic or the like, if a horizontal stepped portion 240S is to be provided in the insertion hole 240h of the separator 240, a horizontal stepped portion 240S, which is the main surface of the stepped portion 240S, cannot be provided. In addition to the portion 240S1, it is necessary to provide curved or tapered chamfered portions 240R1 and 240R2 at both ends in the radial direction of the horizontal portion 240s1 and connect them to the insertion holes 240h.
Therefore, the overall radial length of the stepped portion 240S is the length of the horizontal portion 240S1 that substantially locks the rear terminal fitting 220, and the radial length of the chamfered portions 240R1 and 240R2. There is a problem that the size of the separator 240 is increased due to the need for an extra through-hole 240h, and the number of through-holes 240h provided in the separator 240 of the same size, that is, the number of terminal fittings is limited. In particular, in the case of a NOx sensor element having a large number of electrode portions 300p (normally 6) or a multi-gas sensor (normally 8), the separator 240 needs to be provided with a large number of insertion holes 240h.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a gas sensor in which terminal fittings can be held in a space-saving manner inside a separator, the size of the separator can be reduced, and the number of terminal fittings that can be held in the separator can be increased. do.

In order to solve the above-mentioned problems, the gas sensor of the present invention comprises a sensor element extending in the axial direction and having an electrode portion on the surface on the rear end side, and a plurality of sensor elements extending in the axial direction and electrically connected to the electrode portions. a cylindrical separator that holds the terminal fitting and is arranged on the rear end side of the sensor element; and a separator that is connected to the rear end side of the terminal fitting and pulled out to the rear end side of the separator. a lead wire, wherein the terminal fitting includes, in order from the distal end side, a first portion directly or indirectly connected to the electrode portion; , a second portion directly or indirectly connected to the lead wire, and a neck portion connecting the body portion and the second portion, and the outer surface of the neck portion is on the rear end side. The separator includes a large-diameter hole portion surrounding the entire circumference of the main body portion, and a large-diameter hole portion located on the rear end side of the large-diameter hole portion. a small-diameter hole portion surrounding the entire circumference of the second portion and having a diameter smaller than that of the large-diameter hole portion; and connecting the large-diameter hole portion and the small-diameter hole portion to the inner surface of the separator. It is characterized by being formed.

If a horizontal stepped portion (extending in the radial direction) is provided in the through-hole of the separator to engage the terminal fitting, due to processing problems of the separator made of ceramic, etc., curved surfaces are formed on both ends of the horizontal portion in addition to the horizontal portion. It is necessary to provide a chamfered portion having a shape or a tapered shape to connect with the insertion hole, which increases the size of the insertion hole and thus the separator.
On the other hand, according to this gas sensor, by locking the terminal fittings on the second tapered surface provided on the separator, the terminal fittings are held inside the separator in a space-saving manner as compared with the case of providing a horizontal stepped portion. As a result, the size of the separator can be reduced, and the number of terminal fittings held by the separator can be increased.

In the gas sensor of the present invention, at the contact portion between the first tapered surface and the second tapered surface, the first taper angle θ1, which is the angle between the first tapered surface and the axis of the body portion, is equal to the second taper angle θ1. It may be less than or equal to the second taper angle θ2, which is the angle between the tapered surface and the axis of the main body.
According to this gas sensor, it is possible to more reliably prevent the terminal fitting from slipping out to the rear end side of the separator, as compared with the case where θ1<θ2.

In the gas sensor of the present invention, the second tapered surface may be formed in a truncated cone shape extending all around the inner surface of the separator.
According to this gas sensor, since the second tapered surface is rotationally symmetrical about the axis, the terminal fitting can be inserted through the insertion hole of the separator without determining the orientation of the terminal fitting about the axis in a specific direction. Productivity is improved by eliminating the need for alignment around the axis of the terminal fitting.

In the gas sensor of the present invention, the second portion forms a crimped portion that crimps and connects the lead wire, and the maximum width D3 of the crimped portion in the radial direction is larger than the maximum width D1 of the main body portion. It can be narrow.
According to this gas sensor, since the second portion is closer to the axis of the main body by utilizing the fact that the neck portion is inclined radially inward toward the rear end, the lead wire can be smoothly passed through the insertion hole of the separator. can be pulled out to

The gas sensor of the present invention may constitute a multi-gas sensor.
Since the multi-gas sensor has a large number of electrode units, the present invention is even more effective.

In the gas sensor of the present invention, the first tapered surface may be provided over 1/2 or more of the entire circumference.
According to this gas sensor, the strength of the neck including the first tapered surface is improved.

According to the present invention, it is possible to obtain a gas sensor in which the terminal fittings can be held inside the separator in a space-saving manner, the size of the separator can be reduced, and the number of terminal fittings that can be held in the separator can be increased.

It is a sectional view along the direction of an axis of a gas sensor concerning an embodiment of the present invention. FIG. 10 is a diagram showing a manner in which a distal terminal fitting is held by a distal separator; It is a perspective view of a rear end side terminal metal fitting. FIG. 4 is a diagram showing a manner in which a rear end terminal fitting is held by a rear end separator; It is process drawing which shows the assembly|attachment of a front end side separator and a rear end side separator. FIG. 5 is a partial cross-sectional view showing a manner in which the rear end terminal fitting is locked to the rear end separator; FIG. 10 is a partial cross-sectional view comparing the second tapered surface of the trailing separator with the stepped portion of the conventional separator. 7 is a partial cross-sectional view showing a case where the first taper angle θ1 and the second taper angle θ2 are equal in FIG. 6; FIG. FIG. 10 is a diagram showing a manner in which a conventional terminal fitting is locked to a separator; FIG. 10 is a partial cross-sectional view showing a stepped portion of a conventional separator;

Embodiments of the present invention will be described below.
FIG. 1 is an overall cross-sectional view of a gas sensor (NOx sensor) 1 according to an embodiment of the present invention along the direction of the axis O, and FIGS. 3 is a perspective view of the rear end side terminal fitting 40, FIG. 4 is a diagram showing a manner in which the end side terminal fitting 40 is held by the rear end side separator 95, and FIG. It is a process diagram shown.
This gas sensor 1 is a NOx sensor that detects the concentration of oxygen in the exhaust gas of automobiles and various internal combustion engines.

In FIG. 1, the gas sensor 1 includes a cylindrical metal shell 138 having a threaded portion 139 formed on the outer surface thereof for fixing to an exhaust pipe, and an axis O direction (longitudinal direction of the gas sensor 1: vertical direction in the drawing). A sensor element 10 extending in a plate-like shape, a cylindrical ceramic sleeve 106 disposed so as to surround the periphery of the sensor element 10 in the radial direction, and a rear end portion of the sensor element 10 in an inner space on the front end side thereof. A cylindrical tip separator 90 made of ceramic that surrounds the periphery, and six tip terminal fittings 20 and 30 that are inserted and held in insertion holes 90h that pass through the tip separator 90 in the direction of the axis O. (only four terminals are shown in FIG. 1), a ceramic tubular rear separator 95, and six rear terminal fittings 40 held by the rear separator 95 (two terminal fittings 40 are shown in FIG. 1). (only shown), and
As will be described later, the rear end separator 95 is arranged in contact with the rear end side of the front end separator 90 and connected to each other.
The terminal fittings 20, 30 on the front end side and the terminal fitting 40 on the rear end side are arranged on the front end side and the rear end side, respectively, and are connected to each other. The rear terminal fitting 40 and the rear separator 95 correspond to the "terminal fitting" and "separator" in the claims, respectively.

Note that, as shown in FIG. 1, the tip-side terminal fittings 20 and 30 held by the tip-side separator 90 face the outer surface of the sensor element 10 on the rear end side, and electrode portions ( electrode pad) 11a.
Three electrode portions 11a are arranged in the width direction on both sides of the sensor element 10 on the rear end side. Each electrode portion 11a can be formed as a sintered body mainly composed of Pt, for example.
On the other hand, the gas detection portion 11 at the tip of the sensor element 10 is covered with a porous protective layer 14 such as alumina.

The metal shell 138 is made of stainless steel, has a through-hole 154 that penetrates in the axial direction, and has a substantially tubular shape with a shelf portion 152 that protrudes radially inward from the through-hole 154 . The sensor element 10 is arranged in the through hole 154 so that the tip of the sensor element 10 protrudes from its own tip. Further, the shelf portion 152 is formed as an inwardly tapered surface that is inclined with respect to a plane perpendicular to the axial direction.

Inside the through-hole 154 of the metal shell 138, there are provided a substantially annular ceramic holder 151 made of alumina, a powder-filled layer 153 (hereinafter also referred to as a talc ring 153), and the ceramic sleeve 106 described above are laminated in this order from the front end side to the rear end side.
A crimping packing 157 is arranged between the ceramic sleeve 106 and the rear end portion 140 of the metallic shell 138 . The rear end portion 140 of the metallic shell 138 is caulked through a caulking packing 157 so as to press the ceramic sleeve 106 toward the distal end side.

On the other hand, as shown in FIG. 1, on the front end side (lower side in FIG. 1) of the metal shell 138, there are two metal (for example, stainless steel) outer circumferences that cover the projecting portion of the sensor element 10 and have a plurality of holes. An outer protector 142 and an inner protector 143, which are heavy protectors, are attached by welding or the like.

An outer cylinder 144 is fixed to the rear end side outer circumference of the metallic shell 138 . Lead wires 146 are connected to the rear end sides of the rear end terminal fittings 40 , respectively, and the lead wires 146 are led out to the rear end side of the rear end separator 95 .
Six lead wires 146 (only two are shown in FIG. 1) drawn out from the rear end separator 95 are inserted through the opening on the rear end side (upper side in FIG. 1) of the outer cylinder 144. A rubber grommet 170 having a lead wire insertion hole 170h is arranged.

Further, on the rear end side (upper side in FIG. 1) of the sensor element 10 protruding from the rear end portion 140 of the metal shell 138, a leading end separator 90 is arranged, and a flange portion 90p protruding radially outward from the outer surface. is provided. The distal end separator 90 is held inside the outer cylinder 144 by the flange portion 90 p coming into contact with the outer cylinder 144 via the holding member 169 .
A rear end separator 95 is arranged between the grommet 170 and the tip separator 90, and the elastic force of the grommet 170 causes the rear end separator 95 to press the tip separator 90 to the tip side. As a result, the flange portion 90p is pressed toward the holding member 169, and the leading separator 90 and the trailing separator 95 are connected to each other inside the outer cylinder 144 (that is, without being separated in the direction of the axis O). ) is retained.

FIG. 2 shows a manner in which the tip end terminal fittings 20 and 30 are held on the tip end separator 90. As shown in FIG. In this embodiment, two types of tip end terminal fittings 20 and 30 are used.
In addition, since all four tip end side terminal metal fittings 30 have a line symmetrical shape with the tip end side terminal metal fittings 30 adjacent to each other in the tip end side separator 90, one of the tip end side terminal metal fittings 30 (FIG. 2 ) is shown.
In addition, since the tip end side terminal metal fittings 20 facing each other in the tip end separator 90 are symmetrical with respect to each other in both of the two tip end side terminal metal fittings 20, one of the tip end side terminal metal fittings 20 (Fig. 2 position above) is shown. The tip end terminal fitting 20 is positioned between two tip end terminal fittings 30 along the width direction of the sensor element 10 .

As shown in FIG. 2, the front end terminal fitting 20 as a whole extends in the direction of the axis O, and includes a connecting portion 23 connected to the rear end side terminal fitting 40 and a substantially plate-like body portion connected to the front end side of the connecting portion 23. 21 and an elastic portion 22 folded back toward the sensor element 10 on the tip end side of the body portion 21 are integrally provided.
The connection portion 23 has a cylindrical shape with a C-shaped cross section, and a cylindrical rear end terminal fitting 40 having a C-shaped cross section at the tip end is fitted and connected to the cylinder. In this case, the front terminal fitting 20 is indirectly connected to the lead wire 146 via the rear terminal fitting 40 .
The body portion 21 is held by the distal separator 90 .
The elastic portion 22 is folded back toward the sensor element 10 from the front end of the body portion 21 and elastically connected to the electrode portion 11a (see FIG. 1).

Similarly, the front terminal fitting 30 as a whole extends in the direction of the axis O, and includes a connection portion 33 connected to the rear end terminal fitting 40, a substantially plate-like main body portion 31 connected to the front end side of the connection portion 23, and a main body. An elastic portion 32 that is folded back toward the sensor element 10 on the tip side of the portion 31 is integrally provided.
The connection portion 33 has a cylindrical shape similar to that of the connection portion 23, and is connected to the rear end side terminal fitting 40 by being inserted into the cylinder of the connection portion 33, similarly to the connection portion 23.
The body portion 31 has an L-shaped cross section and is held by the distal separator 90 . A connection portion 33 is integrally connected to the rear end side of the body portion 31 .
The elastic portion 32 is folded back toward the sensor element 10 from the front end of the body portion 31 and elastically connected to the electrode portion 11a (see FIG. 1).

In a state in which the tip-side terminal fittings 20 and 30 are held inside the tip-side separator 90, the connecting portions 23 and 33 protrude toward the rear end side of the tip-side separator 90 (FIG. 2(b)). ).
Note that the tip-side terminal fittings 20 and 30 can be manufactured by, for example, punching out one sheet of metal plate (Inconel (registered trademark) or the like) and then bending it into a predetermined shape, but the present invention is not limited to this.

On the other hand, as shown in FIG. 3, the rear end terminal fitting 40 as a whole extends in the direction of the axis O, and has a crimp terminal portion 47 connected to the lead wire 146 and a substantially plate-like terminal portion connected to the tip side of the crimp terminal portion 47. A neck portion 41, a cylindrical large-diameter portion 45 formed by bending a connecting plate into a C-shaped cross section on the tip side of the neck portion 41, and a cylinder formed by bending a connecting plate into a C-shaped cross section on the tip side of the large-diameter portion 45. A shaped tip portion 43 is integrally provided.
The rear terminal fitting 40 can be manufactured by, for example, punching out one sheet of metal plate (such as SUS304) and then bending it into a predetermined shape, but the present invention is not limited to this.
The tip portion 43, the large-diameter portion 45, and the crimp terminal portion 47 correspond to the "first portion," the "main body portion," and the "second portion," respectively.

The crimping terminal portion 47 clamps the lead wire 146w, which is exposed by stripping off the coating at the tip of the lead wire 146, and crimps the lead wire 146w to grip the lead wire 146w in a cylindrical shape.
The tip portion 43 has a cylindrical shape and tapers toward the tip. The front end portion 43 is fitted into the cylinders of the connection portions 23 and 33 so that the rear terminal fitting 40 is electrically connected to the front end terminal fittings 20 and 30 .
The large diameter portion 45 is larger in diameter than the crimp terminal portion 47 and the tip portion 43 , and the rear end facing surface 45 e of the large diameter portion 45 is exposed radially outward from the crimp terminal portion 47 .

On the other hand, as shown in FIG. 4, the rear separator 95 has six insertion holes 95h arranged in the circumferential direction. The insertion hole 95h has a large-diameter hole portion 95h1 with a large diameter on the front end F side, tapered in diameter near the center in the direction of the axis O, and connected to a small-diameter hole portion 95h2 having a smaller diameter than the large-diameter hole portion 95h1. This diameter-reduced portion forms a second tapered surface 95t that extends radially inward toward the rear end side (it narrows toward the rear end side) (FIG. 4(a)).
Two projections 95p projecting along the width direction of the sensor element 10 are formed on the outer peripheral side of the front-facing surface of the rear-end separator 95. As shown in FIG. The convex portion 95p is adapted to engage with the concave portion 90r (FIG. 5) of the distal separator 90. As shown in FIG.

Then, the lead wire 146 is passed through the tip end side of the insertion hole 95 h in advance, and the lead wire 146 is connected to the rear end side terminal fitting 40 at the tip end side of the rear end side separator 95 . Next, when a part of the lead wire 146 side of the rear end terminal fitting 40 is inserted into the insertion hole 95h from the front end F side and the lead wire 146 is pulled out to the rear end side, the rear end terminal fitting 40 described later is inserted into the second end. The first tapered surface 41t abuts against the second tapered surface 95t to prevent the rear end terminal fitting 40 from coming off to the rear end side, and the rear end side terminal fitting 40 is held in the rear end separator 95 ( FIG. 4(b)).
At this time, the front end side of the front end portion 43 of the rear end terminal fitting 40 (the front end side from the center of the front end portion 43 in the direction of the axis O) protrudes from the front end facing surface of the rear end separator 95 .
The outer diameter of the large-diameter portion 45 is slightly smaller than the inner diameter of the large-diameter hole portion 95h1. The rear terminal fitting 40 is held inside the rear separator 95 .
Further, the small-diameter hole portion 95h2 surrounds at least a portion of the crimp terminal portion 47, but is separated from the crimp terminal portion 47 without being engaged therewith.

Then, as shown in FIG. 5, with the terminal fittings 20, 30, and 40 held by the leading separator 90 and the trailing separator 95, respectively, the trailing end side is inserted into the concave portion 90r of the leading separator 90 in the direction of the axis O. As shown in FIG. By engaging the projections 95p of the separator 95 and holding the leading separator 90 and the trailing separator 95 between a holding member 169 and a grommet 170 (not shown), the leading separator 90 and the trailing separator 95 are held. The separator 95 is connected to each other (FIG. 5(b)).
At this time, the tip portion 43 of the rear terminal fitting 40 projecting to the front end side of the rear separator 95 is inserted into the connecting portion 23 of the front terminal fitting 20 projecting to the rear end side of the front separator 90 . , both terminal fittings are connected. Similarly, although not shown, the tip end portion of the rear end terminal fitting 40 protruding to the front end side of the rear end separator 95 is connected to the connection portion 33 of the front end terminal fitting 30 protruding to the rear end side of the front end separator 90 . 43 is inserted and both terminal metal fittings are connected.

Next, the first tapered surface 41t and the second tapered surface 95t, which are characteristic portions of the present invention, will be described with reference to FIGS. 6 and 7. FIG.
In the present invention, the outer surface of the neck portion 41 forms a first tapered surface 41t that extends radially inward toward the rear end side (it narrows toward the rear end side). It is engaged with the second tapered surface 95t of the end separator 95 .
Now, as shown in FIG. 7, the radial (horizontal) length of the second tapered surface 95t is L1. This length L1 is the amount Sh is taken into consideration, the first tapered surface 41t is set to reliably contact the second tapered surface 95t even if it is shaken by the shake amount Sh.

On the other hand, as shown by the dashed line in FIG. 7, if the rear end separator 95 is provided with a stepped portion 95D facing the front end side, as described with reference to FIG. In addition to the length L1 of the horizontal portion which similarly takes into account the shake amount Sh, chamfers are required at both ends of the horizontal portion, and the total radial length L2 of the stepped portion 95D becomes larger than L1.

By providing the rear end separator 95 with the second tapered surface 95t in this manner, the rear end terminal fitting 40 can be held inside the rear end separator 95 in a space-saving manner, compared to the case where a horizontal step is provided. As a result, the size of the rear separator 95 can be reduced, and the number of rear terminal fittings 40 held by the rear separator 95 can be increased.
In particular, the present invention is more effective in the case of NOx sensor elements having a large number of electrode portions and multi-gas sensors.
Specifically, as shown by the dashed line in FIG. 7, if the rear end separator 95 is provided with a horizontal stepped portion 95D with a length of 0.1 mm facing the tip side, the chamfered portion is 0.2 mm in the radial direction. Thus, the diameter difference between the large-diameter hole portion 95h1 and the small-diameter hole portion 95h2 must be 0.3 mm or more for the stepped portion on one side and 0.6 mm or more for the stepped portions on both sides. In contrast, in the present invention, the chamfer is not required, and the diameter difference can be less than 0.3 mm on one side and less than 0.6 mm on both sides.

In addition, by forming the first tapered surface 41t as the portion of the rear end terminal fitting 40 that is engaged with the second tapered surface 95t, the rear end of the large diameter portion 45, which is the end surface in the radial direction (horizontal direction), can be Compared to the case where the facing surface 45e is locked to the second tapered surface 95t, the contact area with the second tapered surface 95t is increased, and the locking can be performed more reliably.

In addition, in the present embodiment, as shown in FIG. 4, the second tapered surface 95t is formed in a truncated cone shape extending all around the inner surface of the rear separator 95 .
In this way, since the second tapered surface 95t is rotationally symmetrical about the axis, the rear terminal fitting 40 can be moved to the rear end side even if the orientation of the rear terminal fitting 40 about the axis is not determined in a specific direction. It can be inserted through the insertion hole 95h of the separator 95, eliminating the need for positioning the rear terminal fitting 40 around the axis, thereby improving productivity.

Further, in the present embodiment, as shown in FIG. 6, at the contact portion P between the first tapered surface 41t and the second tapered surface 95t, the angle formed by the first tapered surface 41t and the axis AX of the large diameter portion 45 is A certain first taper angle θ1 is less than or equal to a second taper angle θ2 that is the angle between the second taper surface 95t and the axis AX.
By doing so, it is possible to more reliably prevent the terminal metal fitting from slipping out to the rear end side of the separator, as compared with the case of θ1>θ2.
When the first tapered surface 41t and/or the second tapered surface 95t are curved when viewed in cross section along the axis AX, the angle formed by the tangent to the tapered surface at the contact portion P and the axis AX is regarded as the taper angle. .
Also, as shown in FIG. 8, in FIG. 6, the first taper angle .theta.1 and the second taper angle .theta.2 may be equal. By doing so, the contact area between the first tapered surface 41t and the second tapered surface 95t is increased, and the terminal fitting can be more reliably prevented from slipping out to the rear end side of the separator.

Further, in the present embodiment, as shown in FIG. 6, the crimp terminal portion 47 forms a crimp portion that crimps and connects the lead wire 146, and the maximum width D3 in the radial direction of the crimp terminal portion 47 is large. It is narrower than the maximum width D1 of the portion 45 .
By doing so, the crimp terminal portion 47 is brought closer to the axis of the large diameter portion 45 by utilizing the fact that the neck portion 41 is inclined radially inward toward the rear end, so that the lead wire 146 can be brought closer to the rear end side. It can be pulled out more smoothly from the insertion hole 95 h of the separator 95 .
Also, the first tapered surface 41t is preferably provided over 1/2 or more of the entire circumference of the large diameter portion 45 to which the first tapered surface 41t is connected. By doing so, the strength of the neck portion 41 including the first tapered surface 41t is improved. From the viewpoint of improving the strength of the neck portion 41, it is preferable that the first tapered surface 41t is large (wide) in the circumferential direction. It is more preferable that it is 2/3 or less of the entire circumference of the portion 45 .

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

The shape and the like of the terminal fittings and the separator are not limited to those of the above embodiments. Also, the terminal fitting may be configured integrally so that the front end side and the rear end side are not separated.
The connection (coupling) structure between the rear end terminal fitting and the front end terminal fitting is not limited to the above. You may make it insert in the cylindrical part of a side.
When the rear end side of the tip side terminal fitting or the tip side of the rear end side terminal fitting is formed in a tubular shape, it is not limited to a cylinder, and may be a square tube such as a square tube. Also, the tube may not be completely closed, but may be at least part of the tube (for example, C-shaped). Also, one of the tip side terminal fittings and the rear end side terminal fittings may have a cylindrical form or a part thereof.

In addition to the NOx sensor, the gas sensor includes an oxygen sensor, a full range gas sensor, and a multi-gas sensor.
As the multi-gas sensor, there is a configuration in which an ammonia sensor section is provided on the surface of the NOx sensor element so that NOx and ammonia concentrations can be measured (for example, the configuration described in Japanese Patent Laid-Open No. 2018-81037).

Reference Signs List 1 gas sensor 10 sensor element 11a electrode portion 40 terminal metal fitting (rear end side terminal metal fitting)
41 Neck 41t First tapered surface 43 First part (tip part)
45 main body (large diameter part)
47 Second part (crimp terminal part)
95 separator (rear end separator)
95h1 Large-diameter hole portion 95h2 Small-diameter hole portion 95t Second tapered surface 146 Lead wire O Axis line AX Axis of main body P Contact portion between first tapered surface and second tapered surface

Claims (6)

a sensor element extending in the axial direction and having an electrode portion on the surface on the rear end side;
a plurality of terminal fittings extending in the axial direction and electrically connected to the electrode portion;
a cylindrical separator that holds the terminal fitting and is arranged on the rear end side of the sensor element;
a lead wire connected to the rear end side of the terminal fitting and drawn out to the rear end side of the separator;
A gas sensor comprising
The terminal fitting includes, in order from the distal end side, a first portion that is directly or indirectly connected to the electrode portion, a main body portion that has a tubular shape or a part of a tubular shape, and is directly or indirectly connected to the lead wire. and a neck portion that connects the body portion and the second portion integrally,
The outer surface of the neck forms a first tapered surface that extends radially inward toward the rear end side,
The separator includes a large-diameter hole portion that surrounds the entire circumference of the main body portion, and a large-diameter hole portion that is located on the rear end side of the large-diameter hole portion and surrounds the entire circumference of the second portion and is located closer to the large-diameter hole portion than the large-diameter hole portion. a small-diameter small-diameter hole,
a plurality of said large-diameter hole portions and said small-diameter hole portions are formed, each accommodating one said terminal fitting;
The inner surface of the separator that connects the large-diameter hole portion and the small-diameter hole portion is formed with a second tapered surface that engages the first tapered surface and extends radially inward toward the rear end side. A gas sensor characterized by: At the contact portion between the first tapered surface and the second tapered surface, a first taper angle θ1, which is an angle between the first tapered surface and the axis of the body portion, is the angle between the second tapered surface and the body portion. 2. The gas sensor according to claim 1, wherein the second taper angle .theta.2, which is the angle formed with the axis of . 3. The gas sensor according to claim 1, wherein the second tapered surface is formed in a truncated cone shape extending all around the inner surface of the separator. The second part forms a crimping part that crimps and connects the lead wire,
The gas sensor according to any one of claims 1 to 3, wherein a maximum width D3 of the crimped portion in the radial direction is narrower than a maximum width D1 of the body portion. The gas sensor according to any one of claims 1 to 4, which constitutes a multi-gas sensor. The gas sensor according to any one of claims 1 to 5, wherein the first tapered surface is provided over half or more of the entire circumference.

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