JP6983714B2 - Gas sensor - Google Patents

Description

The present invention relates to a gas sensor including a sensor element for detecting the concentration of a gas to be detected and a plurality of separators.

As a gas sensor for detecting the concentration of oxygen or NOx in the exhaust gas of an automobile or the like, a gas sensor having a plate-shaped sensor element using a solid electrolyte is known.
In such a gas sensor, in order to take out the output of the sensor element according to the concentration of the detected gas to the outside, the terminal fitting is brought into contact with the electrode pad provided on the rear end side of the sensor element to electrically connect the two. At the same time, the lead wire is crimped to the rear end side of the terminal fitting. The terminal fitting itself is held by a separator made of an insulating member, and the lead wire is drawn out from the rear end side of the separator via a grommet which is an elastic member to the outside of the gas sensor.

Further, a gas sensor using a split type separator divided into two in the axial direction as a separator is also known (Patent Documents 1 and 2). The split type separator is often adopted when the number of terminal fittings held by the separator is large or for the convenience of assembling the terminal fittings to the separator.
As shown in FIG. 10, in this type of gas sensor, the rear end side of the sensor element 10 is surrounded by the tip side separator 202, and the terminal fittings 20 and 30 held by the tip side separator 202 are on the rear end side of the sensor element 10. It is brought into contact with the electrode pad 11a. Then, the tip side separator 202 is elastically held in the outer cylinder 206 by the holding metal fitting 208 so that the tip side separator 202 does not shake in the radial direction and come into contact with the sensor element 10.
On the other hand, the rear end side separator 204 is connected to the rear end side of the front end side separator 202, and the rear end side separator 204 is held so as to be sandwiched between the front end side separator 202 and the grommet 170. Since the rear end side separator 204 is separated from the sensor element 10, it is not particularly held by the outer cylinder 204, but is held by the elastic force of the grommet 170, so that the rear end side separator 204 is not in contact with the outer cylinder 204.

Japanese Unexamined Patent Publication No. 2009-47574 (Fig. 1) Japanese Unexamined Patent Publication No. 2017-198656 (Fig. 1)

By the way, since the rear end side separator 204 is not in contact with the outer cylinder 204, when the gas sensor vibrates while the vehicle is running or the like, the fixing portion between the front end side separator 202 and the holding metal fitting 208 is used as a fulcrum, and the lever principle is used. The rear end side separator 204 may be shaken in the radial direction T.
Then, when the rear end side separator 204 is shaken, radial stress is applied to the tip side separator 202 in contact with the rear end side separator 204, and eventually the sensor element 10, the sensor element 10 is damaged, or the terminal fitting 20 is used. , 30 and the electrical connection may be lost.
On the other hand, if the rear end side separator 204 is held in the outer cylinder 206 by the holding metal fitting 208, the number of parts and the production process increase, and the cost increases.

Therefore, the present invention provides a gas sensor that suppresses damage to the sensor element and improves the reliability of the electrical connection between the sensor element and the terminal fitting when the front end side separator and the rear end side separator are provided. The purpose.

In order to solve the above problems, the gas sensor of the present invention has a plate shape extending in the axial direction and holds the sensor element having an electrode portion on the outer surface on the rear end side and surrounding the sensor element. The main metal fitting, the terminal metal fitting that is electrically connected to the electrode portion, the terminal metal fitting, the tubular tip side separator that surrounds the rear end side of the sensor element, and the rear end side separator. It surrounds the rear end side separator which is coaxially arranged on the end side and is directly or indirectly connected to the front end side separator, and is fixed to the rear end side of the main metal fitting and surrounds the front end side separator and the rear end side separator. A gas sensor including an outer cylinder, wherein the front end side separator is elastically held by the outer cylinder, the rear end side separator is not held by the outer cylinder, and the first is orthogonal to the axial direction. In the measurement cross section of the above, the minimum dimensional difference between the outer peripheral surface of the sensor element and the inner peripheral surface of the distal end side separator is set to D1, and the D1 is measured in the second measurement cross section orthogonal to the axial direction. It is characterized in that D2 <D1 is satisfied when the minimum dimensional difference between the outer peripheral surface of the rear end side separator and the inner peripheral surface of the outer cylinder is D2 along the direction parallel to the measurement direction of 1. ..

When the gas sensor vibrates, the front end side separator and the rear end side separator are coaxially connected, so that the rear end side separator shakes in the radial direction with the fixing part of the front end side separator held in the outer cylinder as a fulcrum. Sometimes.
Therefore, according to this gas sensor, by setting D2 <D1, the rear end side separator abuts on the inner peripheral surface of the outer cylinder before the sensor element collides with the front end side separator due to radial blurring, and the radial direction Absorbs the blur of. As a result, radial stress is applied to the front end side separator connected to the rear end side separator, and thus the sensor element is suppressed from being damaged, and the electrical connection with the terminal fitting is maintained, and the electrical connection is established. Reliability can be improved.

In the gas sensor of the present invention, the dimensional difference between the outer peripheral surface of the sensor element and the inner peripheral surface of the distal end side separator is D3 in the first measurement cross section, and the D3 is measured in the second measurement cross section. When the minimum dimensional difference between the outer peripheral surface of the rear end side separator and the inner peripheral surface of the outer cylinder is D4 along a direction parallel to the second measurement direction, any of the second measurement directions. Also, D4 <D3 may be satisfied.
According to this gas sensor, no matter which second measurement direction (that is, all directions of 360 degrees in the radial direction) the sensor element approaches the front end side separator, the rear end side separator is as in the case of D2 <D1. It collides with the inner peripheral surface of the outer cylinder first and absorbs the blur in the second measurement direction. Therefore, it is possible to further suppress the damage of the sensor element and further improve the reliability of the electrical connection with the terminal fitting.
In the figure, D31 and D32 correspond to D3, and D41 and D42 correspond to D4.

In the gas sensor of the present invention, the rear end side separator surrounds the terminal fitting or the second terminal fitting connected to the terminal fitting in the axial direction, and in the second measurement cross section, the terminal fitting or the said. When the maximum distance between the second terminal fitting and the rear end side separator is D5, D5 <D1 may be satisfied.
According to this gas sensor, by setting D5 <D1, when the sensor element contracts and the sensor element approaches the front end side separator and the rear end side separator also shakes, the rear end side terminal fitting is together with the rear end side separator. Since it moves to, it is possible to suppress damage and deformation of the terminal fitting on the rear end side. On the other hand, when D5> D1, when D1 contracts and the sensor element approaches the front end side separator and the rear end side separator also shakes, the rear end side terminal fitting shakes in the rear end side separator in the opposite direction due to inertia. There is a risk that the terminal fittings on the rear end side will be damaged or deformed.

In the gas sensor of the present invention, a waterproof ventilation filter may be arranged on the outside of the outer cylinder facing the rear end side separator.
As described above, the present invention absorbs radial blurring of the front end separator even if the rear end separator is not held by the outer cylinder. Therefore, according to this gas sensor, a member that obstructs the flow of air (for example, a holding metal fitting for holding the rear end side separator in the outer cylinder or an outer cylinder is crimped and contracted between the ventilation filter and the outer cylinder. It is not necessary to intervene a crimped portion with a diameter), and the atmosphere can be stably introduced into the gas sensor.

According to the present invention, when the gas sensor has a front end side separator and a rear end side separator, it is possible to suppress damage to the sensor element and improve the reliability of the electrical connection between the sensor element and the terminal fitting.

It is sectional drawing which follows the axial direction of the gas sensor which concerns on embodiment of this invention. It is a perspective view of a sensor element. It is a perspective view which shows the state which held the tip side terminal metal fittings in the tip side separator. It is sectional drawing which shows the state which held the tip side terminal metal fittings in the tip side separator. It is a perspective view which shows the state which held the rear end side terminal metal fittings in the rear end side separator. It is a perspective view which shows the state which connected the rear end side terminal metal fittings to the front end side terminal metal fittings. It is sectional drawing of the front end side separator and the rear end side separator along the line AA and line BB of FIG. It is sectional drawing of the rear end side separator in the 2nd measurement cross section when the axial center of the front end side separator and the rear end side separator is greatly deviated. It is a partial cross-sectional view which shows the modification of the terminal metal fittings. It is sectional drawing which shows the conventional division type separator.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 is an overall cross-sectional view of the gas sensor (NOx sensor) 1 according to the embodiment of the present invention along the axis O direction, FIG. 2 is a perspective view of the sensor element 10, and FIG. A perspective view showing a state of holding the terminal fittings 20 and 30 in the tip side separator 90, FIG. 4 is a cross-sectional view showing a state of holding the front end side terminal fittings 20 and 30 in the tip side separator 90, and FIG. 5 shows a rear end side terminal fitting 40 in the rear end side separator 95. A perspective view showing a held state, FIG. 6 shows a perspective view showing a state in which the rear end side terminal fitting 40 is connected to the front end side terminal fitting 20.
The gas sensor 1 is a NOx sensor that detects the oxygen concentration in the exhaust gas of an automobile or various internal combustion engines.

In FIG. 1, the gas sensor 1 has a tubular main metal fitting 138 in which a threaded portion 139 for being fixed to an exhaust pipe is formed on an outer surface, and an axis O direction (longitudinal direction of the gas sensor 1: vertical direction in the figure). A sensor element 10 having an extending plate shape, a tubular ceramic sleeve 106 arranged so as to surround the radial circumference of the sensor element 10, and an internal space on the tip side of the sensor element 10 at the rear end of the sensor element 10. Six tip sides that are inserted and held through a ceramic tubular tip side separator 90 that is arranged so as to surround the periphery and an insertion hole 90h (90h1, 90h2) that penetrates the tip side separator 90 in the O direction of the axis. Terminal fittings 20 and 30 (in FIG. 1, only two front end side terminal fittings 20 are shown), a ceramic tubular rear end side separator 95, and six rear ends held by the rear end side separator 95. It is provided with side terminal fittings 40 (only two are shown in FIG. 1).

Further, the rear end side separator 95 is coaxially arranged on the rear end side of the front end side separator 90, and is directly in contact with and connected to the front end side separator 90.
Here, "coaxial" means that the axes of the front end side separator 90 and the rear end side separator 95 coincide with each other within the manufacturing tolerance. Specifically, even if a slight deviation occurs in the axis due to an error during assembly and a dimensional difference larger than D2, Dmax, occurs on the opposite side of D2 across the rear end side separator 95. It may be Dmax <D1.
The front end side terminal fittings 20 and 30 correspond to the "terminal fittings" in the claims, and the rear end side terminal fittings 40 correspond to the "second terminal fittings" in the claims.

As shown in FIG. 4, the insertion holes 90h1 and 90h2 of the distal end side separator 90 communicate with the above-mentioned internal space on the distal end side of the distal end side separator 90, and the respective tips held in the insertion holes 90h1 and 90h2. The side terminal fittings 20 and 30 face the outer surface on the rear end side of the sensor element 10 and are electrically connected to the electrode pad (electrode portion) 11a formed on the outer surface.
Further, as shown in FIG. 2, three electrode pads 11a are arranged on both sides of the rear end side of the sensor element 10 in the width direction. Specifically, one electrode pad 11a is arranged in the center of the rear end side of the sensor element 10 in the width direction, and two electrode pads 11a are arranged apart from each other in the width direction on the tip end side thereof.
Each electrode pad 11a can be formed, for example, as a sintered body mainly composed of Pt.
On the other hand, the gas detection unit 11 at the tip of the sensor element 10 is covered with a porous protective layer 14 such as alumina.

The main metal fitting 138 is made of stainless steel, has a through hole 154 penetrating in the axial direction, and has a substantially cylindrical shape having a shelf portion 152 protruding inward in the radial direction of the through hole 154. In the through hole 154, the sensor element 10 is arranged so that the tip portion of the sensor element 10 protrudes from its own tip. Further, the shelf portion 152 is formed as an inwardly tapered surface having an inclination with respect to a plane perpendicular to the axial direction.

Inside the through hole 154 of the main metal fitting 138, a ceramic holder 151 made of alumina having a substantially annular shape, a powder packed bed 153 (hereinafter, also referred to as a talc ring 153), which surrounds the radial circumference of the sensor element 10. And the above-mentioned ceramic sleeve 106 is laminated from the front end side to the rear end side in this order.
Further, a crimp packing 157 is arranged between the ceramic sleeve 106 and the rear end portion 140 of the main metal fitting 138. The rear end portion 140 of the main metal fitting 138 is crimped so as to press the ceramic sleeve 106 toward the tip side via the crimp packing 157.

On the other hand, as shown in FIG. 1, the outer periphery of the tip end side (lower side in FIG. 1) of the main metal fitting 138 covers the protruding portion of the sensor element 10 and is made of metal (for example, stainless steel) having a plurality of holes. The external protector 142 and the internal protector 143, which are heavy protectors, are attached by welding or the like.

An outer cylinder 144 is fixed to the outer periphery on the rear end side of the main metal fitting 138. Further, lead wires 146 are connected to the rear end sides of the rear end side terminal fittings 40, respectively, and the lead wires 146 are led out to the rear end side of the rear end side separator 95.
Then, six lead wires 146 (only two are shown in FIG. 1) drawn from the rear end side separator 95 are inserted into the opening on the rear end side (upper side in FIG. 1) of the outer cylinder 144. A grommet 170, which is an elastic member made of rubber, in which a lead wire insertion hole 170h is formed is arranged.

Further, a front end side separator 90 is arranged on the rear end side (upper side in FIG. 1) of the sensor element 10 protruding from the rear end portion 140 of the main metal fitting 138, and a flange portion 90p protruding radially outward from the outer surface. Is provided. The distal end side separator 90 is held inside the outer cylinder 144 by the flange portion 90p coming into contact with the outer cylinder 144 via the holding member 169. The holding member 169 is crimped together with the outer cylinder 144 by the first crimping portion 144s1 of the outer cylinder 144, and is fixed to the outer cylinder 144.
Here, the inner surface of the holding member 169 has a plurality of elastic pieces that bend in the radial direction, and the distal end side separator 90 is elastically held inside the outer cylinder 144 by being held by the elastic pieces. ..
Further, the rear end side separator 95 is arranged between the grommet 170 and the front end side separator 90, and the rear end side separator 95 presses the front end side separator 90 toward the front end side by the elastic force of the grommet 170. As a result, the flange portion 90p is pressed against the holding member 169 side, and the front end side separator 90 and the rear end side separator 95 are connected to each other inside the outer cylinder 144 (that is, without being separated in the axis O direction). ) It is held.

Further, the protective outer cylinder 145 is covered on the outside of the outer cylinder 144 from the rear end of the tip side separator 90 to the tip of the grommet 170 in the axis O direction, and water-repellent ventilation is provided between the outer cylinder 144 and the protective outer cylinder 145. The filter 180 is arranged.
More specifically, on the side surface of the rear end portion of the outer cylinder 144, four first vent holes 144h (only two are shown in FIG. 1) are opened at equal intervals in the circumferential direction, and the inside of the outer cylinder 144 is opened. It is possible to introduce outside air to. An annular ventilation filter 180 is covered on the radial outer side of the outer cylinder 144 so as to close the first ventilation hole 144h, and the ventilation filter 180 is further surrounded by the protective outer cylinder 145 from the radial outer side. Six second ventilation holes 145h (only two are shown in FIG. 2) are opened on the side surface of the protective outer cylinder 145 at equal intervals in the circumferential direction, and a part of the outer surface of the ventilation filter 180 is formed from the second ventilation holes 145h. By being exposed, the second ventilation hole 145h communicates with the ventilation filter 180, and the outside air is introduced into the outer cylinder 144 via the ventilation filter 180.

The ventilation filter 180 has water repellency (waterproofness), is made of a porous structure such as a fluororesin such as Teflon (registered trademark), and has water repellency (waterproofness), so that external water can be removed. The reference gas (atmosphere) is introduced into the sensor element 10 without passing through.

The outer cylinder 144 and the protective outer cylinder 145 are crimped via the ventilation filter 180 at two locations before and after the first vent hole 144h and the second vent hole 145h, respectively, and the front end side crimping portion 144s3 and the rear end are crimped. A side crimping portion 144s4 is provided.
Further, the tip of the protective outer cylinder 145 is crimped together with the outer cylinder 144 by the second crimping portion 144s2 at the tip from the tip side crimping portion 144s3, and is fixed to the outer cylinder 144.
The rear end side separator 95 is not in contact with the outer cylinder 144, and the outside air introduced through the ventilation filter 180 flows into the sensor element 10 side from the gap G between the rear end side separator 95 and the outer cylinder 144. do.

FIG. 3 is a perspective view showing a state in which the tip side terminal fittings 20 and 30 are held by the tip side separator 90. The lower side of FIG. 3 corresponds to the tip F. Further, in the present embodiment, a total of six tip-side terminal fittings 20 and 30 of two types are used.
As shown in FIG. 4, all of the four tip-side terminal fittings 30 have a shape in which the tip-side terminal fittings 30 adjacent to each other in the tip-side separator 90 are line-symmetrical, and the two tip-side terminal fittings 20 are line-symmetrical. In each case, the tip side terminal fittings 20 facing each other in the tip side separator 90 have a line-symmetrical shape.

The front end side terminal fitting 20 extends in the axis O direction as a whole, and has a connection portion 23 connected to the rear end side terminal fitting 40, a substantially plate-shaped main body portion 21 connected to the front end side of the connection portion 23, and the main body portion 21. An elastic portion 22 that is folded back toward the sensor element 10 on the tip side is integrally provided.
The connecting portion 23 has a cylindrical shape with a C-shaped cross section, and the tip portion 43 (see FIG. 6) of the terminal fitting 40 on the rear end side having a cylindrical shape with a C-shaped cross section at the tip is fitted and connected to the connecting portion 23. .. In this case, the front end side terminal fitting 20 is indirectly connected to the lead wire 146 via the rear end side terminal fitting 40.
The elastic portion 22 is folded back toward the rear end side from the tip of the main body portion 21 toward the sensor element 10, and is elastically connected to one electrode pad 11a on the rear end side in FIG. The elastic portion 22 is elastically bent in the radial direction with respect to the main body portion 21.
Further, the main body portion 21 is formed with holding portions having various shapes that are locked to the inner wall or the like of the distal end side separator 90.

Further, the tip side terminal fitting 30 extends in the axis O direction as a whole, and has a connection portion 33 connected to the rear end side terminal fitting 40, a substantially plate-shaped main body portion 31 connected to the tip end side of the connection portion 33, and a main body portion. An elastic portion 32 that is folded back toward the sensor element 10 on the tip end side of 31 is integrally provided.
The connection portion 33 has a cylindrical shape similar to that of the connection portion 23, and like the connection portion 23, the tip portion 43 of the rear end side terminal fitting 40 is fitted and connected into its own cylinder.
The elastic portion 32 is folded back toward the rear end side from the tip end of the main body portion 31 toward the sensor element 10, and is elastically connected to the two electrode pads 11a on the front end side in FIG. The elastic portion 32 is elastically bent in the radial direction with respect to the main body portion 31.
The main body portion 31 has an L-shaped cross section, and holding portions having various shapes to be locked to the inner wall or the like of the distal end side separator 90 are formed.
The tip side terminal fittings 20 and 30 can be manufactured by punching, for example, one metal plate (Inconel (registered trademark), etc.) and then bending into a predetermined shape, but the present invention is not limited thereto.

As shown in FIG. 4, the distal end side separator 90 has insertion holes 90h1 and 90h2. The insertion holes 90h2 are arranged at the four corners of the distal end side separator 90, and the insertion holes 90h1 are located between the two insertion holes 90h2 along the width direction of the sensor element 10.
The tip side terminal fittings 20 and 30 are inserted into the insertion holes 90h1 and 90h2, respectively, and are held in the tip side separator 90.
Then, with the tip side terminal fittings 20 and 30 held in the tip side separator 90, the connection portions 23 and 33 project to the rear end side of the tip side separator 90 (FIG. 3B).

On the other hand, as shown in FIG. 6, the rear end side terminal fitting 40 extends in the axis O direction as a whole, and is held by the lead wire connecting portion 47 connected to the lead wire 146 and the rear end side separator 95 from the rear end side. A cylindrical central portion 45 having a C-shaped cross section and a cylindrical tip portion 43 having a C-shaped cross section are integrally provided in this order. Further, the distal end portion 43 and the central portion 45 are integrally connected via the distal end side neck portion 49, and the central portion 45 and the lead wire connecting portion 47 are integrally connected via the rear end side neck portion 41. Has been done.
The rear end side terminal fitting 40 can be manufactured, for example, by punching out one metal plate (SUS304 or the like) and then bending it into a predetermined shape, but the present invention is not limited to this.

The lead wire connecting portion 47 has a cylindrical shape (barrel shape by crimping), sandwiches the exposed core wire facing the coating on the tip of the lead wire 146, and crimps (crimps) to grip the core wire from the outside.
The tip 43 has a cylindrical shape and is pointed toward the tip. The tip portion 43 is fitted into the cylinders of the connection portions 23 and 33, and the rear end side terminal fitting 40 is electrically connected to the front end side terminal fittings 20 and 30.
The central portion 45 has a larger diameter than the lead wire connecting portion 47 and the tip portion 43.

As shown in FIG. 5, the rear end side separator 95 has six insertion holes 95h arranged in the circumferential direction. Here, the insertion hole 95h has a large diameter on the tip F side and has a stepped diameter near the center in the O direction of the axis, and this step portion forms a tip facing surface (not shown).
Further, on the outer peripheral side of the distal end facing surface of the rear end side separator 95, two convex portions 95p protruding toward the distal end side are formed.

Then, the lead wire 146 is passed through the tip end side of the insertion hole 95h in advance, and the lead wire 146 is crimped to the lead wire connection portion 47 of the rear end side terminal fitting 40 on the tip end side of the rear end side separator 95 to be connected. Next, when a part of the lead wire 146 side of the rear end side terminal fitting 40 is inserted into the insertion hole 95h from the tip F side and the lead wire 146 is pulled out to the rear end side, the central portion 45 of the rear end side terminal fitting 40 is pulled out. The rear end facing surface is positioned in contact with the front end facing surface of the rear end side separator 95, and the rear end side terminal fitting 40 is held in the rear end side separator 95.

Here, as shown in FIG. 5, the tip portion 43 of the rear end side terminal fitting 40 protrudes from the tip facing surface of the rear end side separator 95.
Then, the front end side separator 90 shown in FIG. 3 and the rear end side separator 95 shown in FIG. 5 are arranged in contact with the front end side and the rear end side, respectively, via the convex portion 95p. As a result, as shown in FIG. 6, the tip portion 43 of the rear end side terminal fitting 40 is fitted into the connection portion 23 of the front end side terminal fitting 20 and connected to each other.
The convex portion 95p supports the front end side terminal fitting 20 and the rear end side terminal fitting 40 protruding 45 from the rear end facing surface of the front end side separator 90 and the front end facing surface of the rear end side separator 95, respectively, in the axis O direction. , These terminals are prevented from being crushed between the front end side separator 90 and the rear end side separator 95.
Although not shown, similarly to the front end side terminal fitting 30, the tip portion 43 of the rear end side terminal fitting 40 is fitted into the connection portion 33 of the front end side terminal fitting 30 and connected to each other.
That is, in the present embodiment, the rear end side terminal fitting 40 is indirectly electrically connected to the electrode pad 11a of the sensor element 10 via the front end side terminal fitting 30.

Next, a feature portion of the present invention will be described with reference to FIG. 7.
FIG. 7 is a cross-sectional view of the front end side separator 90 and the rear end side separator 95 in the cross section along the lines AA and BB of FIG. 1, and is a view in which the cross sections are arranged in the same direction.
As shown in FIG. 7B, in the first measurement cross section S1 which is a cross section along the AA line (orthogonal to the axis O direction), the outer peripheral surface of the sensor element 10 and the inner peripheral surface of the distal end side separator 90. Let D1 be the minimum dimensional difference (minimum distance) from and. Then, the direction in which D1 is measured (the direction connecting both ends of D1, the left-right direction in FIG. 7) is defined as the first measurement direction M1.
Here, as shown in FIG. 7A, in the second measurement cross section S2 which is a cross section along the BB line (orthogonal to the axis O direction), along the direction parallel to the first measurement direction M1. The minimum dimensional difference between the outer peripheral surface of the rear end side separator 95 and the inner peripheral surface of the outer cylinder 144 is defined as D2. If this D2 is parallel to the first measurement direction M1, it is not necessarily the minimum distance between the outer peripheral surface of the rear end side separator 95 and the inner peripheral surface of the outer cylinder 144. Further, the "outer cylinder" means the innermost member when having a plurality of outer cylinders (outer cylinder 144, protective outer cylinder 145).
At this time, it is necessary to satisfy D2 <D1. This is due to the following reasons.

As shown in FIG. 1, when the gas sensor 1 vibrates, the front end side separator 90 and the rear end side separator 95 are coaxially connected, so that the tip side separator 90 held by the holding metal fitting 169 on the outer cylinder 144 The rear end side separator 95 may shake in the radial direction T with the fixed portion as a fulcrum.
Therefore, if D2 <D1, the rear end side separator 95 comes into contact with the inner peripheral surface of the outer cylinder 144 and is in the radial direction T before the sensor element 10 collides with the front end side separator 90 due to the shake in the radial direction T. Absorbs blur. As a result, radial stress is applied to the front end side separator 90 connected to the rear end side separator 95, and thus the sensor element 10 is suppressed from being damaged, and the electrical connection with the terminal fittings 20 and 30 is established. It can be maintained and the reliability of the electrical connection can be improved.

From this point of view, the first measurement cross section S1 is the cross section in which the sensor element 10 first collides with the distal end side separator 90, that is, the outer peripheral surface of the sensor element 10 among a plurality of cross sections orthogonal to the axis O direction. Selects the cross section closest to the inner peripheral surface of the distal end side separator 90 from the cross section along the axis O direction of FIG. However, in this example, since the inner hole of the tip side separator 90 is straight in the axis O direction, any cross section may be adopted for the first measurement cross section S1. The sensor element 10 uses the tip side separator 90. The portion that does not pass is excluded from the target of the first measurement cross section S1.

Similarly, as the second measurement cross section S2, the rear end side separator 95 is a cross section in which the rear end side separator 95 first collides with the inner peripheral surface of the outer cylinder 144, that is, a plurality of cross sections orthogonal to the axis O direction. The cross section closest to the inner peripheral surface of the outer cylinder 144 is selected from the cross section along the axis O direction of FIG.
In this example, the rear end side separator 95 is straight in the axis O direction, but since the rear end side crimping portion 144s4 of the outer cylinder 144 is located most radially inward, the cross section of the rear end side crimping portion 144s4 is shown. It is used for the second measurement cross section S2.

Further, the reason why D2 is set in the direction parallel to the first measurement direction M1 is that the front end side separator 90 and the rear end side separator 95 are connected, so that the sensor element 10 first collides with the front end side separator 90. By aligning the direction of D1 and the direction of D2, when the sensor element 10 approaches the inner peripheral surface of the distal end side separator 90 by shaking in the measurement direction M1, the rear end side separator 95 moves to the inner peripheral surface of the outer cylinder 144. This is because the blur can be absorbed by first contacting.
On the other hand, if D2 is not aligned with the measurement direction M1 (for example, the direction perpendicular to M1), D2 is irrelevant to the proximity of D1 to the measurement direction M1 and effectively absorbs the blurring in the measurement direction M1. Can not.

The reason why the front end side separator 90 and the rear end side separator 95 need to be arranged coaxially is as follows.
That is, as shown in FIG. 8, when the axial centers of the distal end side separator 90 and the rear end side separator 95 are largely deviated from each other, the axial centers of the rear end side separator 95 and the outer cylinder 144 are also deviated, and D2 <D1 is tentatively satisfied. However, a dimensional difference Dmax with a large gap between the separator 95 and the outer cylinder 144 occurs on the side opposite to D2 with the rear end side separator 95 interposed therebetween.
Then, when the rear end side separator 95 is close to the outer cylinder 144 in the direction of narrowing D2, the blur can be absorbed as described above, but when it is close to the outer cylinder 144 in the direction of narrowing Dmax, Dmax> D1. Therefore, the blur cannot be effectively absorbed, and the sensor element 10 cannot be prevented from colliding with the tip side separator 90 first.

As shown in FIG. 7, in the first measurement cross section S1, the dimensional difference between the outer peripheral surface of the sensor element 10 and the inner peripheral surface of the distal end side separator 90 is D3, and in the second measurement cross section S2, D3 is When the minimum dimensional difference between the outer peripheral surface of the rear end side separator 95 and the inner peripheral surface of the outer cylinder 144 is D4 along the direction parallel to the second measurement direction to be measured, any second measurement is performed. Also in the direction, it is preferable to satisfy D4 <D3.
Here, for example, D41 is defined as D4 along a direction parallel to the second measurement direction M31 with respect to D31 measured along the second measurement direction M31 which is the vertical direction in FIG. 7. .. Similarly, with respect to D32 measured along the second measurement direction M32 which is the diagonal direction of FIG. 7 as D3, D42 is defined as D4 along the direction parallel to the second measurement direction M32.

At this time, D41 <D31 and D42 <D32. If this is satisfied in all the second measurement directions in the first measurement cross section S1, the sensor element 10 approaches the tip side separator 90 in which second measurement direction (that is, in all directions of 360 degrees in the radial direction). However, the rear end side separator 95 collides with the inner peripheral surface of the outer cylinder 144 first to absorb the blur in the second measurement direction. Therefore, it is possible to further suppress the damage of the sensor element 10 and further improve the reliability of the electrical connection with the terminal fittings 20 and 30.

In FIG. 7, each insertion hole 95h of the rear end side separator 95 surrounds the rear end side terminal fitting 40. Here, in the second measurement cross section S2, when the maximum distance between the rear end side terminal fitting 40 and the rear end side separator 95 (insertion hole 95h) is D5, it is preferable to satisfy D5 <D1.
By setting D5 <D1, when the sensor element 10 approaches the front end side separator 90 and the rear end side separator 95 also shakes, the rear end side terminal fitting 40 is together with the rear end side separator 95. Since it moves, it is possible to suppress damage and deformation of the terminal fitting 40 on the rear end side. On the other hand, when D5> D1, when D1 contracts, the sensor element 10 approaches the front end side separator 90, and the rear end side separator 95 also shakes, the rear end side terminal fitting 40 has inertia in the rear end side separator 95. This may cause the terminal fitting 40 on the rear end side to be damaged or deformed in the opposite direction.

Further, the present invention is further effective when the waterproof ventilation filter 180 is arranged on the outside of the outer cylinder 144 facing the rear end side separator 95.
As described above, the present invention absorbs radial blurring of the front end side separator 90 even if the rear end side separator 95 is not held by the outer cylinder 144. Therefore, between the ventilation filter 180 and the outer cylinder 144, a member that obstructs the flow of air (for example, a holding metal fitting for holding the rear end side separator 95 in the outer cylinder 144 or the outer cylinder 144 is crimped to reduce the diameter. It is not necessary to intervene the crimped portion), and the atmosphere can be stably introduced into the gas sensor 1.

It goes without saying that the present invention is not limited to the above embodiments and extends to various modifications and equivalents included in the idea and scope of the present invention.

The rear end side separator may be indirectly connected to the front end side separator, and as such an example, as shown in FIG. 9, flanges 50f1 are provided at two locations of one terminal fitting 50 having different axes in the O direction. , 50f2 is provided, and a rigid tubular shape is formed between the flanges 50f1 and 50f2. Then, the flange 50f1 holds the rear end facing surface of the front end side separator 90, the flange 50f2 holds the rear end facing surface of the rear end side separator 98, and the rear end side separator 98 and the front end side separator 90 are aligned with each other. A form of connecting with a gap in the direction can be mentioned.

The shapes of the rear end side separator and the front end side separator are not limited to the above embodiment. Further, as shown in FIG. 8, one terminal fitting 50 may be arranged on the rear end side separator and the front end side separator.
The terminal fitting surrounded by the rear end side separator does not necessarily have to be held by the rear end side separator, and may be loosely fitted (separated) into the insertion hole of the rear end side separator.
In addition to the NOx sensor, examples of the gas sensor include an oxygen sensor and an all-region gas sensor.

1 Gas sensor 10 Sensor element 11a Electrode part (electrode pad)
20 and 30 terminal fittings (tip side terminal fittings)
40 Second terminal fitting (rear end side terminal fitting)
50 1 terminal fitting 90 Tip side separator 95,98 Rear end side separator 138 Main fitting 144 Outer cylinder 180 Ventilation filter S1 1st measurement cross section S2 2nd measurement cross section M1 1st measurement direction M2, M3 2nd Measurement direction O axis

Claims (4)

A sensor element that has a plate shape extending in the axial direction and has an electrode portion on the outer surface on the rear end side.
A main metal fitting that surrounds the sensor element and holds the sensor element,
The terminal fittings electrically connected to the electrode portion and
A cylindrical tip-side separator that holds the terminal fitting and surrounds the rear-end side of the sensor element,
A rear end side separator coaxially arranged on the rear end side of the front end side separator and directly or indirectly connected to the front end side separator.
An outer cylinder fixed to the rear end side of the main metal fitting and surrounding the front end side separator and the rear end side separator,
It is a gas sensor equipped with
The distal end side separator is elastically held by the outer cylinder, and the rear end side separator is not held by the outer cylinder.
In the first measurement cross section orthogonal to the axial direction, the minimum dimensional difference between the outer peripheral surface of the sensor element and the inner peripheral surface of the distal end side separator is defined as D1.
In the second measurement cross section orthogonal to the axial direction, the outer peripheral surface of the rear end side separator and the inner peripheral surface of the outer cylinder are aligned with each other along a direction parallel to the first measurement direction in which the D1 is measured. When the minimum dimensional difference is D2,
A gas sensor characterized by satisfying D2 <D1. In the first measurement cross section, the dimensional difference between the outer peripheral surface of the sensor element and the inner peripheral surface of the distal end side separator is defined as D3.
In the second measurement cross section, the minimum dimensional difference between the outer peripheral surface of the rear end side separator and the inner peripheral surface of the outer cylinder is set along the direction parallel to the second measurement direction in which the D3 is measured. When it is D4
The gas sensor according to claim 1, wherein D4 <D3 is satisfied in any of the second measurement directions. The rear end side separator surrounds the terminal fitting or the second terminal fitting connected to the terminal fitting in the axial direction.
In the second measurement cross section, when the maximum distance between the terminal fitting or the second terminal fitting and the rear end side separator is D5.
The gas sensor according to claim 1 or 2, wherein D5 <D1 is satisfied. The gas sensor according to any one of claims 1 to 3, wherein a waterproof ventilation filter is arranged on the outside of the outer cylinder facing the rear end side separator.

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