JP6769884B2 - Sensor - Google Patents

Description

The present invention relates to a sensor including a sensor element including a detection unit, a main metal fitting for holding the sensor element via an element holding member, and an element protector formed in a shape covering the sensor element and fixed to the main metal fitting. ..

Sensors that detect the state quantity (gas concentration, temperature, etc.) of the object to be measured are known. The sensor includes, for example, a sensor element including a detection unit, a main metal fitting for holding the sensor element via an element holding member, and an element protector formed in a shape covering the sensor element and fixed to the main metal fitting ( Patent Document 1).

As an example of such a sensor, a gas sensor for detecting a specific gas contained in a gas to be measured is known. Examples of applications of the gas sensor include applications for detecting a specific gas (oxygen, NOx, etc.) contained in the exhaust gas of an internal combustion engine.

For a sensor used in an application where the object to be measured is at a high temperature, for example, the heat resistance can be improved by configuring the element protector, which is a member that comes into direct contact with the object to be measured, with a material having excellent heat resistance.

Japanese Unexamined Patent Publication No. 2003-185620

However, even if the heat resistance of the element protector of the sensor can be improved, there is a risk that the main metal fitting will be corroded by the object to be measured at a high temperature.
That is, since the measurement target may come into direct contact with the end of the main metal fitting on the side where the detection portion of the sensor element is arranged, there is a risk of corrosion by the high temperature measurement target. An element protector for protecting the sensor element is fixed to the portion of the main metal fitting. Therefore, if the portion of the main metal fitting is corroded and the strength is reduced, the element protector may fall off.

The main metal fitting may adopt a structure in which other members are fixed by processing that involves deformation such as crimping, and when a material with excellent heat resistance is used to improve heat resistance in the main metal fitting with such a structure. There is a problem that processing with deformation becomes difficult.

Therefore, an object of the present invention is to provide a sensor capable of improving heat resistance while providing a main metal fitting made of a material that can be processed with deformation.

The gas sensor in one aspect of the present invention includes a sensor element, a main metal fitting, an element protector, and a main metal fitting protection member.
The sensor element is formed in an elongated shape extending in the axial direction, and has a detection unit on the tip side.

The main metal fitting is formed in a tubular shape having a through hole extending from the front end side opening to the rear end side opening. The main metal fitting holds the sensor element arranged in the through hole via the element holding member. At this time, the sensor element is arranged in the through hole with the detection portion protruding from the opening on the tip end side of the main metal fitting.

The element protector has an opening through which the object to be measured passes, and is formed in a tubular shape. The element protector is fixed to the tip side of the main metal fitting.
The main metal fitting has a protector facing surface facing the rear end portion of the element protector on its outer surface.

The sensor includes a main metal fitting protection member. The main metal fitting protection member covers a predetermined area of the main metal fitting together with the element protector.
In a predetermined area of the main metal fitting covered by the protector and the main metal fitting protective member, at least a part of the tip surface of the main metal fitting, at least a part of the inner surface of the through hole, and a radial outer surface connected to the front end surface of the main metal fitting. At least a part of, and includes.

Such a sensor is provided with a main metal fitting protection member and an element protector, so that a predetermined area of the main metal fitting (at least a part of the tip surface of the main metal fitting, at least a part of the inner surface of the through hole, and the tip surface of the main metal fitting) It is possible to prevent the high temperature object to be measured from coming into direct contact with at least a part of the radial outer surface connected to the above. As a result, this sensor can suppress corrosion of a predetermined area of the main metal fitting due to high temperature while forming the main metal fitting with a material that can be processed with deformation (crimping, etc.), so that the heat resistance of the sensor as a whole You can improve your sex.

This sensor uses the element protector necessary for protecting the sensor element, and by providing the minimum necessary main metal fitting protection member, the main metal fitting can be protected, so the manufacturing cost is large. The heat resistance of the entire sensor can be improved while suppressing the increase.

Therefore, according to this sensor, it is possible to improve the heat resistance while providing the main metal fitting made of a material that can be processed with deformation.
Next, in the above-mentioned sensor, the area on the inner surface of the through hole of the main metal fitting on the tip side of the element holding member, the area on the radial outer surface of the main metal fitting covered by the element protector, and the tip of the main metal fitting. When the surface and the protector internal region are defined, the main metal fitting protection member and the element protector may be configured to cover at least a region on the tip side of the protector internal region of the main metal fitting with respect to the protector facing surface.

In such a sensor, since the main metal fitting protection member and the element protector cover at least the area on the tip side of the protector internal region of the main metal fitting from the protector facing surface, the protector facing surface in the protector internal region of the main metal fitting. It is possible to prevent the high-temperature object to be measured from coming into direct contact with the region on the tip side. As a result, this sensor can prevent the internal region of the protector of the main metal fitting from corroding due to high temperature while forming the main metal fitting with a material that can be processed with deformation (crimping, etc.). Heat resistance can be improved.

In particular, the part of the main metal fitting on the tip side of the protector facing surface has a restriction of dimensional expansion in the radial direction of the sensor, and it is possible to secure a large "thickness dimension" from the inner surface to the outer surface of the through hole. Since it is difficult, if corrosion occurs due to the influence of high temperature, the strength will decrease and it will be easily damaged. On the other hand, by adopting a configuration in which the main metal fitting protection member and the element protector cover at least the region on the tip side of the protector internal region of the main metal fitting from the protector facing surface, corrosion due to the influence of high temperature can be suppressed, and the main metal fitting can be suppressed. Damage can be suppressed.

Next, in the above-mentioned sensor, the main metal fitting protection member may be formed in a tubular shape having an insertion hole through which the sensor element is inserted.
The main metal fitting protection member having such a shape can be arranged inside the through hole of the main metal fitting with the sensor element inserted into the insertion hole, and is located on the tip side of the protector internal region on the front end side of the protector facing surface. At least the area can be covered.

The tubular shape may be a multi-stage tubular shape in which portions having different radial dimensions are connected via a stepped portion, or a flange portion that protrudes outward in the radial direction with respect to the tubular portion. It may have a tubular shape with a collar having a.

Next, in the above-mentioned sensor, the main metal fitting protection member may include a protector contact portion that contacts the inner surface of the element protector in the circumferential direction.
By providing the protector contact portion, it is possible to suppress the formation of a gap between the main metal fitting protection member and the element protector, and it is possible that the object to be measured (gas, etc.) reaches the main metal fitting through the outside of the main metal fitting protection member. Can be suppressed.

In this way, when the main metal fitting protection member is provided with the protector contact portion, it becomes difficult for the object to be measured to come into direct contact with the main metal fitting, and corrosion of the main metal fitting due to high temperature can be further suppressed, and the main metal fitting is damaged. Can be suppressed.

Next, in the above-mentioned sensor, an inward projecting portion may be provided on the rear end side of the main metal fitting protection member.
By providing the inner protrusion, the measurement object moving inside the main metal fitting protection member toward the rear end side collides with the inner protrusion, and the movement direction of the measurement object can be changed. As a result, it is possible to prevent the object to be measured from reaching the main metal fitting through the inside of the main metal fitting protection member.

In this way, by providing the main metal fitting protection member with the inner protrusion, it becomes difficult for the object to be measured to come into direct contact with the main metal fitting, and corrosion of the main metal fitting due to high temperature can be further suppressed, and damage to the main metal fitting can be suppressed. it can.

Next, in the above-mentioned sensor, the main metal fitting protection member may be formed of a material having higher heat resistance than the main metal fitting.
As a result, even if the object to be measured has a temperature higher than the heat resistant temperature of the main metal fitting, the predetermined area of the main metal fitting can be protected by the main metal fitting protection member, and the predetermined area of the main metal fitting is corroded by the high temperature. Therefore, the heat resistance of the sensor as a whole can be improved.

The term "material having better heat resistance than the main metal fitting" means a material that is less likely to be corroded due to high temperature than the material forming the main metal fitting.
Next, in the above-mentioned sensor, the main metal fitting protection member may be made of a metal material.

The main metal fitting protection member may be constructed by using a ceramic material or the like, but when the same strength is achieved by using a metal material, the thickness of the main metal fitting protection member is higher than that of the ceramic material or the like. The dimensions can be reduced.

As a result, a large distance between the main metal fitting protection member and the sensor element can be secured, and the thermal influence of the temperature (heat amount) of the main metal fitting protection member on the sensor element can be suppressed.
Next, in the above-mentioned sensor, the main metal fitting protection member may be made of a material having higher corrosion resistance than the main metal fitting.

By providing such a main metal fitting protection member, it is possible to suppress the main metal fitting protection member from being corroded by the measurement object, and it is possible to suppress the main metal fitting from being corroded by the measurement object.

Even if the main metal fitting is made of a metal material with low catalytic property such as stainless steel instead of a precious metal material with high catalytic property such as Pt, if high temperature oxidation or corrosion progresses, the temperature is high. It may be catalytic in an environment (eg, 600 ° C. or higher). In particular, when iron used as a base material for stainless steel is oxidized, it becomes highly catalytic at high temperatures and may have the ability to burn flammable gases such as HC and ammonia. Therefore, if the main metal fitting is made of a metal material having inferior corrosion resistance such as high temperature oxidation resistance and acid resistance, the inner wall surface in the through hole of the main metal fitting may be corroded and then peeled off. If debris peeled off from the main metal fittings due to vibration, water exposure, or dew condensation adheres to the electrode surface of the sensor element, it may affect the detection result of flammable gas.

Therefore, in the above-mentioned sensor, the main metal fitting protection member may be configured to cover the region of the inner surface of the through hole on the tip side of the element holding member and to abut on the element holding member.

By providing the main metal fitting protection member having such a configuration, the inner surface of the through hole does not come into direct contact with the measurement object, and the main metal fitting can be prevented from being corroded by the measurement object. As a result, it is possible to prevent a part of the main metal fitting from peeling off due to corrosion, and it is possible to prevent debris from the main metal fitting from adhering to the sensor element. Therefore, it is possible to prevent an error in the sensor output due to the influence of the debris. ..

Next, in the above-mentioned sensor, the element holding member may be configured to include a ceramic holder that abuts on the sensor element and a metal holder that is arranged outside the ceramic holder and abuts on the main metal fitting. The main metal fitting protection member may be configured to cover a region of the inner surface of the through hole on the tip side of the element holding member and to abut on at least one of the ceramic holder and the metal holder.

By providing the element holding member and the main metal fitting protection member having such a configuration, the inner surface of the through hole does not come into direct contact with the measurement object, and the main metal fitting can be prevented from being corroded by the measurement object. As a result, it is possible to prevent debris of the main metal fitting that has been peeled off due to corrosion from adhering to the sensor element, and it is possible to prevent an error in the sensor output due to the influence of the debris.

According to the sensor of the present invention, heat resistance can be improved while providing a main metal fitting made of a material that can be processed with deformation.

It is sectional drawing which shows the whole structure of a gas sensor. It is a perspective view which shows the schematic structure of the detection element used for a gas sensor. It is a perspective view which shows the appearance of the main metal fitting protection member. It is sectional drawing which showed the internal structure of the tip side region of the 2nd gas sensor. It is a perspective view which shows the appearance of the 2nd main metal fitting protection member. It is sectional drawing which showed the internal structure of the tip side region of the 3rd gas sensor. It is a perspective view which shows the appearance of the 3rd main metal fitting protection member. It is sectional drawing which showed the internal structure of the tip side region of the 4th gas sensor. It is a perspective view which shows the appearance of the 4th main metal fitting protection member. It is sectional drawing which shows the whole structure of the 5th gas sensor. It is sectional drawing which showed the internal structure of the tip side region of the 6th gas sensor. It is sectional drawing which showed the internal structure of the tip side region of the 7th gas sensor. It is sectional drawing which showed the internal structure of the tip side region of the 8th gas sensor.

Hereinafter, embodiments to which the present invention has been applied will be described with reference to the drawings.
It should be noted that the present invention is not limited to the following embodiments, and it goes without saying that various forms can be adopted as long as it belongs to the technical scope of the present invention.

[1. First Embodiment]
[1-1. overall structure]
As a first embodiment, an oxygen sensor (hereinafter, also referred to as gas sensor 1), which is attached to the exhaust pipe of an internal combustion engine so that the tip portion protrudes into the exhaust pipe and detects oxygen in the exhaust gas, is given as an example. explain. The gas sensor 1 is provided in the exhaust pipe of a vehicle such as an automobile or a motorcycle.

First, the configuration of the gas sensor 1 of the present embodiment will be described with reference to FIG.
In FIG. 1, the lower direction in the drawing is the front end side of the gas sensor, and the upper direction in the drawing is the rear end side of the gas sensor.

The gas sensor 1 has a tubular main metal fitting 3 fixed to an exhaust pipe (not shown) and a plate-shaped main metal fitting 3 that is inserted into the main metal fitting 3 and extends in the axial direction (longitudinal direction of the gas sensor 1: vertical direction in the drawing). The detection element 5, the element protector 9 arranged on the tip side (lower part in the drawing) of the main metal fitting 3 and covering the tip side of the detection element 5, the main metal fitting protection member 10 provided at the tip of the main metal fitting 3, and the main metal fitting An outer cylinder 11 that is attached to the rear end side (upper part in the drawing) of 3 and covers the outer periphery of the detection element 5, and a separator 13 (ceramic separator) that is arranged inside the outer cylinder 11 and accommodates the rear end side of the detection element 5. 13) and a closing member 15 that closes the rear end side of the outer cylinder 11.

The detection element 5 is a first plate in which a detection unit 19 covered with a protective layer is formed on the front end side facing an object to be measured (exhaust gas, etc.), and the front and back sides of the outer surface on the rear end side are in a positional relationship. Electrode terminal portions (first to fifth electrode terminal portions) 31, 32, 33, 34, 35 are formed on the surface 21 and the second plate surface 23.

In the detection element 5, the detection unit 19 on the tip side protrudes from the tip of the main metal fitting 3 fixed to the exhaust pipe, and the electrode terminal parts 31 to 35 on the rear end side protrude from the rear end of the main metal fitting 3. , Fixed inside the main metal fitting 3.

Connection terminals (first to fifth connection terminals) 41, 42, 43, 44, and 45, which are metal terminals, are connected to the electrode terminal portions 31 to 35, respectively. That is, the connection terminals 41 to 45 are electrically connected to the electrode terminals 31 to 35 of the detection element 5 by being arranged between the detection element 5 and the ceramic separator 13 inside the ceramic separator 13. Will be done. The connection terminals 41 to 45 are constructed by using an elastic heat-resistant metal (for example, stainless steel).

The connection terminals 41 to 45 are electrically connected to each of the (five) lead wires 37 (specifically, the metal core wire 37a in the lead wire 37) arranged inside the sensor from the outside, and the lead wire 37 The current path of the current flowing between the external device to which is connected and the electrode terminals 31 to 35 is formed (only three lead wires 37 are shown in the figure).

FIG. 2 is a perspective view showing a schematic structure of the detection element 5.
As shown in FIG. 2, the detection element 5 has a rectangular parallelepiped shape in which a plate-shaped element portion 51 extending in the axial direction (left-right direction in FIG. 2) and a plate-shaped heater 53 extending in the same axial direction are laminated. , The cross section perpendicular to the axial direction is rectangular.

Since the detection element 5 used in the gas sensor 1 is conventionally known, detailed description of its internal structure and the like will be omitted.
Returning to FIG. 1, the main metal fitting 3 is a tubular member having a screw portion 55 for fixing itself to the exhaust pipe on the outer surface thereof and a through hole 57 at the center of the shaft thereof. The through hole 57 is formed with a shelf portion 59 that projects inward in the radial direction. The main metal fitting 3 is made of a metal material (for example, stainless steel).

Inside the through hole 57 of the main metal fitting 3, a holder 61 (ceramic holder 61) formed by using an annular insulating material (for example, alumina) arranged so as to surround the radial circumference of the detection element 5 , Similar annular powder packed layers 63, 65 (talc rings 63, 65) and sleeve 67 (ceramic sleeve 67) formed using similar annular insulating material (eg, alumina), in that order. It is laminated from the front end side to the rear end side.

A crimping packing 69 is arranged between the ceramic sleeve 67 and the rear end portion of the main metal fitting 3, and a talc ring 63 or a ceramic holder is provided between the ceramic holder 61 and the shelf portion 59 of the main metal fitting 3. A tubular metal holder 71 for holding the 61 is arranged. The rear end portion of the main metal fitting 3 is crimped so as to press the ceramic sleeve 67 toward the tip side via the crimping packing 69.

The element protector 9 is a tubular member attached to the outer periphery of the main metal fitting 3 on the tip end side by welding or the like (not shown) so as to cover the protruding portion of the detection element 5. The element protector 9 is formed by using a heat-resistant material (for example, NCF601). The element protector 9 has a double structure including an external protector 9a and an internal protector 9b, and a plurality of holes 9c through which gas can pass are formed on a side wall thereof or the like.

The ceramic separator 13 is a tubular member formed by using an insulating material (for example, alumina), and the outer cylinder 11 is provided by a tubular holding metal fitting 73 arranged inside the rear end side of the outer cylinder 11. It is held inside the rear end side. The ceramic separator 13 is provided with an annular flange portion 74 protruding outward on the outer surface thereof. The ceramic separator 13 is held by the outer cylinder 11 by supporting the flange portion 74 by the holding metal fitting 73.

A through hole 75 is formed inside the ceramic separator 13 in the axial direction, and the through hole 75 accommodates the rear end portion (electrode terminal portion 31 to 35) of the detection element 5 and the electrode terminal portion. Connection terminals 41 to 45 electrically connected to 31 to 35 are housed.

The closing member 15 is a grommet formed by using a flexible material (for example, fluororesin). The closing member 15 is arranged inside the rear end side of the outer cylinder 11 in a state of being in contact with the rear end side of the ceramic separator 13, and is fixed to the outer cylinder 11 by crimping the outer cylinder 11 from the outside to the inside. Has been done.

The lead wire 37 is connected (by crimping) to the rear end side of the connection terminals 41 to 45, and is inserted into a through hole 77 formed through the closing member 15 to extend to the outside. ..
[1-2. Main metal fitting protection member]
Next, the main metal fitting protection member 10 which is a main part of the present embodiment will be described.

FIG. 3 is a perspective view showing the appearance of the main metal fitting protection member 10.
The main metal fitting protection member 10 includes a tubular portion 10a and a flange portion 10b. Inside the tubular portion 10a, an insertion hole 10c is formed which penetrates in the axial direction and inserts the detection element 5. The main metal fitting protection member 10 is made of a heat-resistant metal material (NCF601 or SUS310).

The tubular portion 10a is formed in a tubular shape whose outer diameter dimension perpendicular to the axial direction is equivalent to the inner diameter dimension of the through hole 57 of the main metal fitting 3.
The collar portion 10b is formed so as to project outward in the circumferential direction at the tip end portion of the tubular portion 10a.

As shown in FIG. 1, in the main metal fitting protection member 10, the tubular portion 10a is in contact with the inner surface on the tip end side of the through hole 57 of the main metal fitting 3, and the flange portion 10b is in contact with the tip surface of the main metal fitting 3. It is arranged at the tip of the main metal fitting 3. Further, the flange portion 10b of the main metal fitting protection member 10 comes into contact with the inner surface of the element protector 9 (specifically, the internal protector 9b) in the circumferential direction.

The main metal fitting 3 is made of stainless steel, and in the present embodiment, it is made of SUS430. SUS430 is a material that can be processed with deformation (such as crimping). The main metal fitting 3 made of such a material presses the ceramic sleeve 67 toward the tip end side via the crimping packing 69 by crimping the rear end portion of the main metal fitting 3.

The main metal fitting 3 includes a protector fixing portion 3a for fixing the element protector 9 to the tip thereof. The thickness dimension of the protector fixing portion 3a (the dimension from the inner surface facing the through hole 57 to the outer surface in contact with the element protector 9) is formed to be smaller than the thickness dimension of the screw portion 55 of the main metal fitting 3. ..

The main metal fitting 3 includes a protector facing surface 3b on its outer surface. The protector facing surface 3b is formed so as to face the rear end portion of the element protector 9 fixed to the protector fixing portion 3a. The protector facing surface 3b of the present embodiment is formed as a surface perpendicular to the axial direction (in other words, a surface facing the tip side) at a portion of the outer surface of the main metal fitting 3 on the tip side of the screw portion 55. ing.

That is, the protector fixing portion 3a is formed so that the outer diameter of the main metal fitting 3 is smaller than that of the screw portion 55, and as a result, the protector facing surface 3b is formed on the tip side of the screw portion 55. It will be.

Here, the region of the inner surface of the through hole 57 of the main metal fitting 3 on the tip side of the ceramic holder 61 (element holding member 61) and the outer surface of the main metal fitting 3 (specifically, the outer surface is connected to the tip surface). The region of the outer surface in the radial direction) covered by the element protector 9 and the tip surface of the main metal fitting 3 are defined as the protector internal region A1. In the present embodiment, the protector internal region A1 includes a region of the inner surface of the through hole 57 on the tip side of the ceramic holder 61, a surface of the radial outer surface of the main metal fitting 3 in contact with the element protector 9, and a protector fixing portion. It is a region formed by the tip surface of 3a.

Then, the main metal fitting protection member 10 has at least a region (in other words, a region corresponding to the inner surface and the front end surface of the protector fixing portion 3a) on the tip side of the protector internal region A1 of the main metal fitting 3 with respect to the protector facing surface 3b. It is arranged so as to cover it. Specifically, the tubular portion 10a of the main metal fitting protection member 10 covers the region of the inner surface of the through hole 57 on the tip side of the protector facing surface 3b, and the flange portion 10b of the main metal fitting protection member 10 covers the protector fixing portion 3a. Cover the tip surface of. Therefore, at least the region of the protector internal region A1 on the tip side of the protector facing surface 3b is covered by the main metal fitting protection member 10 and the element protector 9.

The heat-resistant metal material (NCF601 or SUS310) constituting the main metal fitting protection member 10 is superior in heat resistance to the material (SUS430) constituting the main metal fitting 3. Further, the heat-resistant metal material (NCF601 or SUS310) constituting the main metal fitting protection member 10 is superior in corrosion resistance to the material (SUS430) constituting the main metal fitting 3.

[1-3. effect]
As described above, the gas sensor 1 of the present embodiment includes the main metal fitting protection member 10 made of a material having higher heat resistance than the main metal fitting 3, so that the protector internal region A1 of the main metal fitting 3 faces the protector. It is possible to prevent the high-temperature measurement object (exhaust gas) from directly contacting the region on the tip side of the surface 3b.

That is, the gas sensor 1 is formed of the main metal fitting 3 with a material (SUS430) capable of processing with deformation (crimping, etc.), and is on the tip side of the protector internal region A1 of the main metal fitting 3 with respect to the protector facing surface 3b. Since the region (inner surface and tip surface of the protector fixing portion 3a) can be suppressed from being corroded by high temperature, the heat resistance of the sensor as a whole can be improved.

Here, the protector fixing portion 3a, which is a portion of the main metal fitting 3 on the tip side of the protector facing surface 3b, has a restriction of dimensional expansion in the radial direction of the sensor, so that the element protector 9 is moved from the inner surface of the through hole 57. It is difficult to secure a large thickness dimension up to the facing outer surface. Therefore, the protector fixing portion 3a is a portion where the strength is lowered and easily damaged when corrosion or the like occurs due to the influence of high temperature, and the element protector 9 may fall off in some cases.

On the other hand, the gas sensor 1 has a configuration in which the main metal fitting protection member 10 and the element protector 9 cover at least the region on the tip side of the protector facing surface 3b of the protector internal region A1 of the main metal fitting 3. It is possible to prevent the protector fixing portion 3a of No. 3 from being corroded due to the influence of high temperature, and it is possible to suppress damage to the main metal fitting 3.

Therefore, according to the gas sensor 1, the heat resistance can be improved while providing the main metal fitting 3 made of a material that can be processed with deformation.
Next, the main metal fitting protection member 10 is formed in a tubular shape having an insertion hole 10c through which the detection element 5 is inserted. The main metal fitting protection member 10 having such a shape can be arranged inside the through hole 57 of the main metal fitting 3 with the detection element 5 inserted through the insertion hole 10c, and is opposed to the protector in the protector internal region A1. At least the region on the tip side of the surface 3b can be covered.

The main metal fitting protection member 10 includes a flange portion 10b that comes into contact with the inner surface of the element protector 9 in the circumferential direction. By providing such a flange portion 10b (protector contact portion), it is possible to suppress the formation of a gap between the main metal fitting protection member 10 and the element protector 9, and the object to be measured (measurement target) is passed through the outside of the main metal fitting protection member 10. Exhaust gas) can be prevented from reaching the main metal fitting 3.

In this way, when the main metal fitting protection member 10 is provided with the flange portion 10b, it becomes difficult for high-temperature exhaust gas to come into direct contact with the main metal fitting 3, and corrosion of the main metal fitting 3 due to high temperature can be further suppressed, and the main metal fitting 3 can be further suppressed. The damage of 3 can be suppressed.

The main metal fitting protection member 10 is made of a heat-resistant metal material (NCF601 or SUS310), and when achieving the same strength, the thickness dimension can be made smaller than that of the case where the main metal fitting protection member 10 is made of a ceramic material.

As a result, a large distance between the main metal fitting protection member 10 and the detection element 5 can be secured, and the thermal influence of the temperature (heat amount) of the main metal fitting protection member 10 on the detection element 5 can be suppressed.
Next, the main metal fitting protection member 10 is made of a material having higher corrosion resistance than the main metal fitting 3. By providing such a main metal fitting protection member 10, it is possible to prevent the main metal fitting protection member 10 from being corroded by the object to be measured (exhaust gas), and it is possible to prevent the main metal fitting 3 from being corroded by the object to be measured.

[1-4. Correspondence of wording]
Here, the correspondence between the words in the present embodiment will be described.
The gas sensor 1 corresponds to an example of a sensor, the detection element 5 corresponds to an example of a sensor element, the main metal fitting 3 corresponds to an example of a main metal fitting, the element protector 9 corresponds to an example of an element protector, and the ceramic holder 61 and The metal holder 71 corresponds to an example of the element holding member.

The protector facing surface 3b corresponds to an example of the protector facing surface, the protector internal region A1 corresponds to an example of the protector internal region, the main metal fitting protection member 10 corresponds to an example of the main metal fitting protection member, and the flange portion 10b corresponds to the protector. It corresponds to an example of the contact part.

[2. Second Embodiment]
[2-1. overall structure]
Next, the second gas sensor 101 of the second embodiment will be described.

The contents of the second embodiment similar to those of the first embodiment will be described using the same reference numerals, or the description thereof will be omitted.
Since the main metal fitting protection member is different in the second embodiment as compared with the first embodiment, the main metal fitting protection member will be mainly described.

FIG. 4 is a cross-sectional view showing the internal structure of the tip end side region of the second gas sensor 101.
In FIG. 4, the lower direction in the drawing is the front end side of the gas sensor, and the upper direction in the drawing is the rear end side of the gas sensor.

The second gas sensor 101 includes a main metal fitting 3, a detection element 5, an element protector 9, a second main metal fitting protection member 81, an outer cylinder 11, a ceramic separator 13, and a closing member 15.

Although the configuration of the rear end portion of the second gas sensor 101 (ceramic separator 13, closing member 15, etc.) is not shown in FIG. 4, the configuration of the rear end portion of the second gas sensor 101 is the same as that of the first embodiment. The same is true.

Of the second gas sensor 101, the internal protector 9b of the element protector 9 has a larger diameter dimension perpendicular to the axial direction with respect to a portion on the tip side of the tip surface of the protector fixing portion 3a as compared with the first embodiment. Has been done. That is, as for the gap dimension between the outer surface of the inner protector 9b and the inner surface of the outer protector 9a, the gap dimension of the second embodiment is smaller than the gap dimension of the first embodiment.

As a result, the internal protector 9b of the second embodiment is arranged so as to cover a part of the tip surface of the protector fixing portion 3a of the main metal fitting 3. The internal protector 9b of the first embodiment is arranged in a state of covering the entire tip surface of the protector fixing portion 3a of the main metal fitting 3 (specifically, a state of covering the entire tip surface via the collar portion 10b). There is.

[2-2. 2nd main metal fitting protection member]
FIG. 5 is a perspective view showing the appearance of the second main metal fitting protection member 81.
The second main body metal fitting protection member 81 includes a rear end tubular portion 81a, a stepped portion 81b, a tip tubular portion 81c, and an inner protruding portion 81d. Inside the second main metal fitting protection member 81, an insertion hole 81e is formed which penetrates in the axial direction and inserts the detection element 5. The second main metal fitting protection member 81 is made of a heat-resistant metal material (NCF601 or SUS310).

The rear end tubular portion 81a is formed in a tubular shape whose outer diameter dimension perpendicular to the axial direction is equivalent to the inner diameter dimension of the through hole 57 of the main metal fitting 3. The tip tubular portion 81c is formed in a tubular shape whose outer diameter dimension perpendicular to the axial direction is equivalent to the inner diameter dimension of the element protector 9 (internal protector 9b). Therefore, the rear end tubular portion 81a is formed to have an outer diameter dimension perpendicular to the axial direction smaller than that of the tip tubular portion 81c.

The step portion 81b is formed so as to connect the tip end portion of the rear end tubular portion 81a and the rear end portion of the tip end tubular portion 81c.
The inner protruding portion 81d is formed so as to project inward in the circumferential direction at the rear end portion of the rear end tubular portion 81a.

As shown in FIG. 4, in the second main metal fitting protection member 81, the rear end tubular portion 81a abuts on the inner surface on the tip end side of the through hole 57 of the main metal fitting 3, and the stepped portion 81b hits the front end surface of the main metal fitting 3. The tip tubular portion 81c is in contact with the inner surface of the element protector 9 (specifically, the internal protector 9b) in the circumferential direction, and is arranged at the tip portion of the main metal fitting 3.

Here, the main metal fitting 3 is formed of SUS430 as in the first embodiment, and includes a protector fixing portion 3a and a protector facing surface 3b.
The second main metal fitting protection member 81 corresponds to a region (in other words, a part of the inner surface and the front end surface of the protector fixing portion 3a) on the tip side of the protector internal region A1 of the main metal fitting 3 with respect to the protector facing surface 3b. It is arranged so as to cover at least the area to be used. Specifically, the rear end tubular portion 81a of the second main metal fitting protection member 81 covers the region of the inner surface of the through hole 57 on the tip side of the protector facing surface 3b, and the stepped portion of the second main metal fitting protection member 81. 81b covers a part of the tip surface of the protector fixing portion 3a. Therefore, at least the region of the protector internal region A1 on the tip side of the protector facing surface 3b is covered by the second main metal fitting protection member 81 and the element protector 9.

The heat-resistant metal material (NCF601 or SUS310) constituting the second main metal fitting protection member 81 is superior in heat resistance and corrosion resistance to the material (SUS430) constituting the main metal fitting 3.

[2-3. effect]
As described above, the second gas sensor 101 of the present embodiment includes the second main metal fitting protection member 81 made of a material having higher heat resistance than the main metal fitting 3, so that the protector internal region A1 of the main metal fitting 3 is provided. Of these, it is possible to prevent the high-temperature measurement object (exhaust gas) from directly contacting the region on the tip side of the protector facing surface 3b.

That is, the second gas sensor 101 forms the main metal fitting 3 with a material (SUS430) capable of processing with deformation (crimping, etc.), and is more than the protector facing surface 3b in the protector internal region A1 of the main metal fitting 3. Since the region on the tip side (inner surface and tip surface of the protector fixing portion 3a) can be suppressed from being corroded by high temperature, the heat resistance of the sensor as a whole can be improved.

The second main metal fitting protection member 81 includes a tip tubular portion 81c that comes into contact with the inner surface of the element protector 9 in the circumferential direction. By providing such a tip tubular portion 81c (protector contact portion), it is possible to suppress the formation of a gap between the second main metal fitting protection member 81 and the element protector 9, and the second main metal fitting protection member 81 It is possible to prevent the object to be measured (exhaust gas) from reaching the main metal fitting 3 through the outside.

The second main metal fitting protection member 81 includes an inwardly projecting inwardly projecting portion 81d on its rear end side.
When the second main metal fitting protection member 81 includes the inner protruding portion 81d, the exhaust gas moving inside the second main metal fitting protecting member 81 toward the rear end side collides with the inner protruding portion 81d, and the exhaust gas becomes You can change the direction of movement. As a result, it is possible to prevent the exhaust gas from reaching the main metal fitting 3 through the inside of the second main metal fitting protection member 81.

In this way, when the second main metal fitting protection member 81 is provided with the inner protruding portion 81d, it becomes difficult for the exhaust gas to come into direct contact with the main metal fitting 3, and corrosion of the main metal fitting 3 due to high temperature can be further suppressed. Damage to the metal fitting 3 can be suppressed.

[2-4. Correspondence of wording]
Here, the correspondence between the words in the present embodiment will be described.
The second gas sensor 101 corresponds to an example of the sensor, the element protector 9 corresponds to an example of the element protector, the second main metal fitting protection member 81 corresponds to an example of the main metal fitting protection member, and the tip tubular portion 81c corresponds to the protector. It corresponds to an example of the contact portion, and the inner protruding portion 81d corresponds to an example of the inner protruding portion.

[3. Third Embodiment]
[3-1. overall structure]
Next, the third gas sensor 103 of the third embodiment will be described.

The same contents as those of the first embodiment will be described with reference to the same reference numerals, or the description thereof will be omitted.
FIG. 6 is a cross-sectional view showing the internal structure of the tip end side region of the third gas sensor 103.

In FIG. 6, the lower direction in the drawing is the front end side of the gas sensor, and the upper direction in the drawing is the rear end side of the gas sensor.
The third gas sensor 103 includes a main metal fitting 3, a detection element 5, an element protector 9, a third main metal fitting protection member 83, an outer cylinder 11, a ceramic separator 13, and a closing member 15.

Although the configuration of the rear end portion of the third gas sensor 103 (ceramic separator 13, closing member 15, etc.) is not shown in FIG. 6, the configuration of the rear end portion of the third gas sensor 103 is the same as that of the first embodiment. The same is true.

Of the third gas sensor 103, the internal protector 9b of the element protector 9 is formed to have a smaller diameter dimension perpendicular to the axial direction with respect to a portion on the tip side of the tip surface of the protector fixing portion 3a as compared with the first embodiment. Has been done. That is, as for the gap dimension between the outer surface of the inner protector 9b and the inner surface of the outer protector 9a, the gap dimension of the third embodiment is larger than the gap dimension of the first embodiment.

As a result, the internal protector 9b of the third embodiment covers a part of the front end side opening of the through hole 57 of the main metal fitting 3 (specifically, the front end side opening via the third main metal fitting protection member 83). It is arranged so as to cover a part of the part). The internal protector 9b of the first embodiment is arranged so as not to cover the tip end side opening of the through hole 57 of the main metal fitting 3 at all.

[3-2. Third main metal fitting protection member]
FIG. 7 is a perspective view showing the appearance of the third main metal fitting protection member 83.
The third main body metal fitting protection member 83 includes a rear end tubular portion 83a, a step portion 83b, and a tip tubular portion 83c. Inside the third main metal fitting protection member 83, an insertion hole 83d is formed which penetrates in the axial direction and inserts the detection element 5. The third main metal fitting protection member 83 is made of a heat-resistant metal material (NCF601 or SUS310).

The rear end tubular portion 83a is formed in a tubular shape whose outer diameter dimension perpendicular to the axial direction is equivalent to the inner diameter dimension of the through hole 57 of the main metal fitting 3. The tip tubular portion 83c is formed in a tubular shape whose outer diameter dimension perpendicular to the axial direction is equivalent to the inner diameter dimension of the element protector 9 (internal protector 9b). Therefore, the rear end tubular portion 83a has an outer diameter dimension perpendicular to the axial direction larger than that of the tip tubular portion 83c.

The step portion 83b is formed so as to connect the tip end portion of the rear end tubular portion 83a and the rear end portion of the tip end tubular portion 83c.
As shown in FIG. 6, in the third main metal fitting protection member 83, the rear end tubular portion 83a abuts on the inner surface on the tip end side of the through hole 57 of the main metal fitting 3, and the tip tubular portion 83c is the element protector 9 (in detail). Is arranged at the tip of the main metal fitting 3 in a state of being in contact with the inner surface of the internal protector 9b) over the circumferential direction.

Here, the main metal fitting 3 is formed of SUS430 as in the first embodiment, and includes a protector fixing portion 3a and a protector facing surface 3b.
Then, the third main metal fitting protection member 83 covers at least a region of the protector internal region A1 of the main metal fitting 3 on the tip side of the protector facing surface 3b (in other words, a region corresponding to the inner surface of the protector fixing portion 3a). It is arranged like this. Specifically, the rear end tubular portion 83a of the third main metal fitting protection member 83 covers a region of the inner surface of the through hole 57 on the tip side of the protector facing surface 3b. Further, the internal protector 9b covers the entire tip surface of the protector fixing portion 3a of the main metal fitting 3. Therefore, at least the region of the protector internal region A1 on the tip side of the protector facing surface 3b is covered by the third main metal fitting protection member 83 and the internal protector 9b.

The heat-resistant metal material (NCF601 or SUS310) constituting the third main metal fitting protection member 83 is superior in heat resistance and corrosion resistance to the material (SUS430) constituting the main metal fitting 3.

[3-3. effect]
As described above, the third gas sensor 103 of the present embodiment includes the third main metal fitting protection member 83 made of a material having higher heat resistance than the main metal fitting 3, so that the protector internal region A1 of the main metal fitting 3 is provided. Of these, it is possible to prevent the high-temperature measurement object (exhaust gas) from directly contacting the region on the tip side of the protector facing surface 3b.

That is, the third gas sensor 103 forms the main metal fitting 3 with a material (SUS430) capable of processing with deformation (crimping, etc.), and is more than the protector facing surface 3b in the protector internal region A1 of the main metal fitting 3. Since the region on the tip side (inner surface and tip surface of the protector fixing portion 3a) can be suppressed from being corroded by high temperature, the heat resistance of the sensor as a whole can be improved.

The third main metal fitting protection member 83 includes a tip tubular portion 83c that comes into contact with the inner surface of the element protector 9 in the circumferential direction. By providing such a tip tubular portion 83c (protector contact portion), it is possible to suppress the formation of a gap between the third main metal fitting protection member 83 and the element protector 9, and the third main metal fitting protection member 83 can be prevented from forming a gap. It is possible to prevent the object to be measured (exhaust gas) from reaching the main metal fitting 3 through the outside.

[3-4. Correspondence of wording]
Here, the correspondence between the words in the present embodiment will be described.
The third gas sensor 103 corresponds to an example of the sensor, the element protector 9 corresponds to an example of the element protector, the third main metal fitting protection member 83 corresponds to an example of the main metal fitting protection member, and the tip tubular portion 83c corresponds to the protector. It corresponds to an example of the contact part.

[4. Fourth Embodiment]
[4-1. overall structure]
Next, the fourth gas sensor 105 of the fourth embodiment will be described.

The same contents as those of the first embodiment will be described with reference to the same reference numerals, or the description thereof will be omitted.
FIG. 8 is a cross-sectional view showing the internal structure of the distal end side region of the fourth gas sensor 105.

In FIG. 8, the lower direction in the drawing is the front end side of the gas sensor, and the upper direction in the drawing is the rear end side of the gas sensor.
The fourth gas sensor 105 includes a main metal fitting 3, a detection element 5, an element protector 9, a fourth main metal fitting protection member 85, an outer cylinder 11, a ceramic separator 13, and a closing member 15.

Although the configuration of the rear end portion of the fourth gas sensor 105 (ceramic separator 13, closing member 15, etc.) is not shown in FIG. 8, the configuration of the rear end portion of the fourth gas sensor 105 is the same as that of the first embodiment. The same is true.

Of the fourth gas sensor 105, the element protector 9 (external protector 9a and internal protector 9b) has a diameter dimension perpendicular to the axial direction with respect to a portion surrounding the protector fixing portion 3a of the main metal fitting 3, as compared with the first embodiment. Is formed large.

As a result, the element protector 9 of the fourth embodiment is fixed to the protector fixing portion 3a by welding or the like via the fourth main metal fitting protection member 85.
[4-2. 4th main metal fitting protection member]
FIG. 9 is a perspective view showing the appearance of the fourth main metal fitting protection member 85.

The fourth main metal fitting protection member 85 includes an inner tubular portion 85a, a connecting portion 85b, and an outer tubular portion 85c. Inside the inner tubular portion 85a, an insertion hole 85d is formed which penetrates in the axial direction and inserts the detection element 5. The fourth main metal fitting protection member 85 is made of a heat-resistant metal material (NCF601 or SUS310).

The inner tubular portion 85a is formed in a tubular shape whose outer diameter dimension perpendicular to the axial direction is equivalent to the inner diameter dimension of the through hole 57 of the main metal fitting 3. The outer tubular portion 85c is formed in a tubular shape whose inner diameter dimension perpendicular to the axial direction is equivalent to the outer diameter dimension of the protector fixing portion 3a of the main metal fitting 3.

The connecting portion 85b is formed so as to connect the tip end portion of the inner tubular portion 85a and the tip end portion of the outer tubular portion 85c.
As shown in FIG. 8, in the fourth main metal fitting protection member 85, the inner tubular portion 85a abuts on the inner surface on the tip end side of the through hole 57 of the main metal fitting 3, and the connecting portion 85b hits the tip surface of the protector fixing portion 3a. The outer tubular portion 85c is in contact with the outer peripheral surface of the protector fixing portion 3a, and is arranged at the tip end portion of the main metal fitting 3. The connecting portion 85b and the outer tubular portion 85c each come into contact with the inner surface of the element protector 9 (specifically, the inner protector 9b) in the circumferential direction.

Here, the main metal fitting 3 is formed of SUS430 as in the first embodiment, and includes a protector fixing portion 3a and a protector facing surface 3b.
Then, the fourth main metal fitting protection member 85 is a region of the protector internal region A1 of the main metal fitting 3 on the tip side of the protector facing surface 3b (in other words, a region corresponding to the inner surface and the tip surface of the protector fixing portion 3a). Is arranged so as to cover at least. Specifically, of the fourth main metal fitting protection member 85, the inner tubular portion 85a covers the region of the inner surface of the through hole 57 on the tip side of the protector facing surface 3b, and the connecting portion 85b is the protector fixing portion 3a. The tip surface is covered, and the outer tubular portion 85c covers a part of the outer surface of the protector fixing portion 3a. Therefore, at least the region of the protector internal region A1 on the tip side of the protector facing surface 3b is covered by the fourth main metal fitting protection member 85 and the internal protector 9b.

The heat-resistant metal material (NCF601 or SUS310) constituting the fourth main metal fitting protection member 85 is superior in heat resistance and corrosion resistance to the material (SUS430) constituting the main metal fitting 3.

[4-3. effect]
As described above, the fourth gas sensor 105 of the present embodiment includes the fourth main metal fitting protection member 85 formed of a material having higher heat resistance than the main metal fitting 3, so that the protector internal region A1 of the main metal fitting 3 is provided. Of these, it is possible to prevent the high-temperature measurement object (exhaust gas) from directly contacting the region on the tip side of the protector facing surface 3b.

That is, the fourth gas sensor 105 is formed of the main metal fitting 3 from a material (SUS430) capable of processing with deformation (crimping, etc.), and is more than the protector facing surface 3b in the protector internal region A1 of the main metal fitting 3. Since the region on the tip side (inner surface and tip surface of the protector fixing portion 3a) can be suppressed from being corroded by high temperature, the heat resistance of the sensor as a whole can be improved.

The fourth main metal fitting protection member 85 includes a connecting portion 85b and an outer tubular portion 85c that come into contact with the inner surface of the element protector 9 in the circumferential direction. By providing such a connecting portion 85b and an outer tubular portion 85c (protector contact portion), it is possible to suppress the formation of a gap between the fourth main metal fitting protection member 85 and the element protector 9, and the fourth main metal fitting can be prevented from forming. It is possible to prevent the object to be measured (exhaust gas) from reaching the main metal fitting 3 through the outside of the protective member 85.

[4-4. Correspondence of wording]
Here, the correspondence between the words in the present embodiment will be described.
The fourth gas sensor 105 corresponds to an example of the sensor, the element protector 9 corresponds to an example of the element protector, the fourth main metal fitting protection member 85 corresponds to an example of the main metal fitting protection member, and the connecting portion 85b and the outer tubular portion. 85c corresponds to an example of the protector contact portion.

[5. Fifth Embodiment]
In the above embodiment, the sensor including the main metal fitting 3 integrally provided with the screw portion 55 as the main metal fitting has been described, but the sensor is not limited to the sensor including the main metal fitting having such a configuration. For example, as in the fifth gas sensor 107 of the fifth embodiment shown in FIG. 10, the configuration may include a second main body fitting 113 fixed to the sensor mounting position by the mounting member 115 having the screw portion 55.

Regarding the fifth gas sensor 107, the same contents as those of the gas sensor 1 of the first embodiment will be described using the same reference numerals, or the description thereof will be omitted.
The second main metal fitting 113 is a tubular member having a through hole 57 penetrating in the axial direction at the center of the axis. The second main metal fitting 113 is provided with a flange portion 113c projecting outward in the radial direction at the tip portion thereof. The through hole 57 is formed with a shelf portion 59 that projects inward in the radial direction. The second main metal fitting 113 is made of a metal material (for example, stainless steel (SUS430) or the like).

The second main body metal fitting 113 includes a protector fixing portion 113a for fixing the element protector 9 to the tip thereof. The thickness dimension of the protector fixing portion 113a (the dimension from the inner surface facing the through hole 57 to the outer surface in contact with the element protector 9) is formed to be smaller than the thickness dimension of the collar portion 113c of the second main metal fitting 113. Will be done.

The second main metal fitting 113 includes a protector facing surface 113b on its outer surface. The protector facing surface 113b is formed so as to face the rear end portion of the element protector 9 fixed to the protector fixing portion 113a. The protector facing surface 3b of the present embodiment is formed as a surface perpendicular to the axial direction (in other words, a surface facing the tip side) at a portion of the outer surface of the main metal fitting 3 on the tip side of the flange portion 113c. ing.

The mounting member 115 is arranged on the outer periphery of the second main metal fitting 113 on the rear end side of the flange portion 113c of the second main metal fitting 113, and is rotatably formed with respect to the second main metal fitting 113. On the outer surface of the mounting member 115, a screw portion 55 (male screw portion 55) screwed to the sensor mounting position is formed. The mounting member 115 applies an urging force toward the tip to the flange portion 113c of the second main metal fitting 113 by screwing the screw portion 55 to the sensor mounting position.

That is, the second main metal fitting 113 is fixed at the sensor mounting position by pressing the flange portion 113c toward the tip side by the urging force from the mounting member 115.
The fifth gas sensor 107 including the second main metal fitting 113 having such a configuration can also exhibit the same effect as that of the first embodiment by providing the main metal fitting protecting member 10, and can be processed with deformation. The heat resistance can be improved while providing the second main metal fitting 113 made of the same material.

The fifth gas sensor 107 corresponds to an example of the sensor, and the second main metal fitting 113 corresponds to an example of the main metal fitting.
[6. 6th Embodiment]
In the above embodiment, the sensor in which the element protector is fixed to the main metal fitting by welding has been described, but the fixing method is not limited to welding. For example, as in the sixth gas sensor 109 shown in FIG. 11, the element protector may be fixed to the main metal fitting by crimping the main metal fitting in addition to welding.

Regarding the sixth gas sensor 109, the same contents as those of the gas sensor 1 of the first embodiment will be described with reference to the same reference numerals, or the description thereof will be omitted.
The sixth gas sensor 109 includes a third main metal fitting 117 and a second element protector 119.

The third main metal fitting 117 is a tubular member having a threaded portion 55 for fixing itself to the exhaust pipe on its outer surface and a through hole 57 at the center of the shaft thereof. The through hole 57 is formed with a shelf portion 59 that projects inward in the radial direction. The third main metal fitting 117 is made of a metal material (for example, stainless steel (SUS430) or the like).

The third main body fitting 117 includes a protector fixing portion 117a and a crimping fixing portion 117c for fixing the second element protector 119 to the tip thereof, and a protector facing surface 117b facing the rear end portion of the second element protector 119. To be equipped.

The thickness dimension of the protector fixing portion 117a (the dimension from the inner surface facing the through hole 57 to the outer surface in contact with the second element protector 119) is larger than the thickness dimension of the screw portion 55 of the third main metal fitting 117. Formed small. The protector facing surface 117b is formed as a surface perpendicular to the axial direction (in other words, a surface facing the tip side) at a portion of the outer surface of the third main metal fitting 117 on the tip side of the screw portion 55. ..

The crimping fixing portion 117c is formed so as to project from the outside of the protector facing surface 117b of the third main metal fitting 117 toward the tip end. In the crimping fixing portion 117c before the crimping process, the gap dimension (the gap dimension perpendicular to the axial direction) between the protector fixing portion 117a and the crimping fixing portion 117c is equal to or larger than the width dimension of the protector facing surface 117b. It is formed. The crimping fixing portion 117c having such a shape is crimped inward in the radial direction, so that the rear end portion of the second element protector 119 (described later) is formed between the protector facing surface 117b and the crimping fixing portion 117c. The outer bent portion 119d and the inner bent portion 119e) are sandwiched.

The second element protector 119 is a tubular member attached to the outer periphery of the tip end side of the third main metal fitting 117 by welding or the like so as to cover the protruding portion of the detection element 5. The second element protector 119 is formed by using a heat resistant material (for example, NCF601). The second element protector 119 has a double structure including a second external protector 119a and a second internal protector 119b, and a plurality of holes 119c through which gas can pass are formed on the side wall or the like thereof. There is. Further, the second outer protector 119a and the second inner protector 119b are provided with a radially outwardly bent outer bent portion 119d and an inner bent portion 119e, respectively, at the rear end portions.

The second element protector 119 having such a configuration has an outer bent portion 119d and an inner bent portion 119e between the protector fixing portion 117a and the crimping fixing portion 117c before the crimping process in the third main metal fitting 117. Is arranged, the crimping fixing portion 117c is crimped inward in the radial direction, and is sandwiched between the protector facing surface 117b and the crimping fixing portion 117c. After that, the crimping fixing portion 117c, the outer bent portion 119d, the inner bent portion 119e, and the protector facing surface 117b are welded to each other to form the welded portion 120, whereby the third main metal fitting 117 of the second element protector 119 is formed. The fixing work to is completed.

The sixth gas sensor 109 including the third main metal fitting 117 and the second element protector 119 can also exhibit the same effect as that of the first embodiment by providing the main metal fitting protection member 10, and can be deformed. The heat resistance can be improved while providing the third main metal fitting 117 made of a material that can be processed together.

The sixth gas sensor 109 corresponds to an example of the sensor, the third main metal fitting 117 corresponds to an example of the main metal fitting, and the second element protector 119 corresponds to an example of the element protector.
[7. Seventh Embodiment]
In the above embodiment, at least a part of the inner surface of the through hole in the main metal fitting (specifically, at least a part of the inner surface of the through hole on the tip side of the element holding member (ceramic holder 61 and metal holder 71)). Has described a sensor that is exposed to the object to be measured, but is not limited to such a configuration. For example, as in the seventh gas sensor 110 shown in FIG. 12, the tubular portion 10a of the main metal fitting protection member 10 may cover the inner surface of the through hole 57 on the tip side of the metal holder 71.

Regarding the seventh gas sensor 110, the same contents as those of the sixth gas sensor 109 of the sixth embodiment will be described using the same reference numerals, or the description thereof will be omitted.
In the seventh gas sensor 110, the tubular portion 10a of the main metal fitting protection member 10 is formed longer than that of the sixth gas sensor 109, and the rear end of the tubular portion 10a abuts on the metal holder 71 over the entire circumference. There is a difference. That is, in the seventh gas sensor 110, the main metal fitting protection member 10 is configured to cover the region of the inner surface of the through hole 57 on the tip side of the metal holder 71 and to abut on the metal holder 71.

By providing the main metal fitting protection member 10 having such a configuration, the seventh gas sensor 110 prevents the inner surface of the through hole 57 from coming into direct contact with the exhaust gas, and suppresses the third main metal fitting 117 from being corroded by the exhaust gas. it can. As a result, it is possible to prevent a part of the third main metal fitting 117 from peeling off due to corrosion, and it is possible to prevent fragments of the third main metal fitting 117 that have been peeled off due to corrosion from adhering to the detection element 5. Therefore, the sensor is affected by the debris. It is possible to suppress the occurrence of an error in the output.

The seventh gas sensor 110 is also provided with the main metal fitting protection member 10, so that the same effect as that of the first embodiment can be exhibited, and the third main metal fitting 117 made of a material that can be processed with deformation. The heat resistance can be improved while providing the above.

[8. Other embodiments]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and can be implemented in various embodiments without departing from the gist of the present invention.

For example, in the above embodiment, the embodiment in which the main metal fitting protection member is formed of NCF601 or SUS310 has been described, but the material of the main metal fitting protection member is not limited to these, and is superior in heat resistance to the main metal fitting. (SUS304, SUS316, other heat-resistant metal materials, ceramic materials, etc.) may be adopted.

Further, in the above embodiment, the embodiment in which the main metal fitting is made of stainless steel (SUS430) and the element protector is made of NCF601 has been described, but the main metal fitting and the element protector are limited to those made of these materials. However, it may be constructed by using other metal materials.

Further, the main metal fitting protection member provided in the sensors of the fifth embodiment and the sixth embodiment is not limited to the main metal fitting protection member 10 similar to the first embodiment, and the second main metal fitting protection member 81 and the third The main metal fitting protection member 83 and the fourth main metal fitting protection member 85 may be used.

Further, the main metal fitting protection member provided with the inner protrusion is not limited to the second main metal fitting protection member 81, and the inner protrusion is the main metal fitting protection member 10, the third main metal fitting protection member 83, and the fourth main body. It may be provided on the metal fitting protection member 85.

Further, the sensor having a configuration in which the region of the inner surface of the through hole in the main metal fitting on the tip side of the element holding member is covered with another member is not limited to the configuration like the seventh gas sensor 110. For example, as in the eighth gas sensor 111 shown in FIG. 13, the tubular portion 10a of the main metal fitting protection member 10 is formed long, and the rear end of the tubular portion 10a covers the entire circumference of the ceramic holder 61 and the metal holder 71. It may be in contact with at least one of them. That is, in the eighth gas sensor 111, the main metal fitting protection member 10 covers the region of the inner surface of the through hole 57 on the tip side of the ceramic holder 61 and abuts on at least one of the ceramic holder 61 and the metal holder 71. It is configured as follows.

By providing the main metal fitting protection member 10 having such a configuration, the eighth gas sensor 111 prevents the inner surface of the through hole 57 from coming into direct contact with the exhaust gas, and suppresses the third main metal fitting 117 from being corroded by the exhaust gas. it can. As a result, it is possible to prevent a part of the third main metal fitting 117 from peeling off due to corrosion, and it is possible to prevent fragments of the third main metal fitting 117 that have been peeled off due to corrosion from adhering to the detection element 5. Therefore, the sensor is affected by the debris. It is possible to suppress the occurrence of an error in the output. The eighth gas sensor 111 also has the same effect as that of the first embodiment by providing the main metal fitting protection member 10, and the third main metal fitting 117 is made of a material that can be processed with deformation. The heat resistance can be improved while providing the above.

Further, in the above embodiment, the mode in which the main metal fitting protection member is formed of a single member has been described, but the main metal fitting protection member may be formed of a plurality of members. Further, a form in which a plurality of main metal fitting protection members overlap may be adopted.

Further, the type of sensor is not limited to the gas sensor that detects the gas concentration as the state quantity of the object to be measured, and may be a temperature sensor that detects the temperature of the grain to be measured.

1 ... Gas sensor, 3 ... Main metal fitting, 3a ... Protector fixing part, 3b ... Protector facing surface, 5 ... Detection element, 9 ... Element protector, 9a ... External protector, 9b ... Internal protector, 9c ... Hole, 10 ... Main metal fitting Protective member, 10a ... Cylindrical part, 10b ... Flange part, 10c ... Insertion hole, 55 ... Screw part (male screw part), 57 ... Through hole, 61 ... Holder (ceramic holder), 81 ... Second main metal fitting protection member , 81a ... Rear end tubular portion, 81b ... Stepped portion, 81c ... Tip tubular portion, 81d ... Inner protruding portion, 81e ... Insertion hole, 83 ... Third main metal fitting protection member, 83a ... Rear end tubular portion, 83b ... Step portion, 83c ... Tip tubular portion, 83d ... Insertion hole, 85 ... Fourth main metal fitting protection member, 85a ... Inner tubular portion, 85b ... Connecting portion, 85c ... Outer tubular portion, 85d ... Insertion hole, 101 ... 2nd gas sensor, 103 ... 3rd gas sensor, 105 ... 4th gas sensor, 107 ... 5th gas sensor, 109 ... 6th gas sensor, 110 ... 7th gas sensor, 111 ... 8th gas sensor, 113 ... 2nd main metal fitting, 113a ... Protector fixing part, 113b ... protector facing surface, 113c ... flange part, 115 ... mounting member, 117 ... third main metal fitting, 117a ... protector fixing part, 117b ... protector facing surface, 117c ... crimping fixing part, 119 ... second Element protector, 119a ... 2nd external protector, 119b ... 2nd internal protector, 119c ... hole, 119d ... outer bent part, 119e ... inner bent part, 120 ... welded part, A1 ... protector internal region.

Claims (10)

A sensor element that is formed in a long shape extending in the axial direction and has a detection unit on the tip side,
The sensor element is formed in a tubular shape having a through hole extending from the front end side opening to the rear end side opening, and the sensor element arranged in the through hole is held in a state where the detection portion protrudes from the front end side opening. The main metal fittings that are held via the members and
A tubular element protector that is provided with an opening through which the object to be measured passes and is fixed to the tip side of the main metal fitting.
It is a sensor equipped with
The main metal fitting is provided with a protector facing surface facing the rear end portion of the element protector on its outer surface.
The element includes at least a part of the tip surface of the main metal fitting, at least a part of the inner surface of the through hole, and at least a part of the outer surface of the main metal fitting which is connected to the tip surface in the radial direction. Equipped with a main metal fitting protection member that covers with the protector,
Sensor. A region of the inner surface of the through hole of the main metal fitting on the tip side of the element holding member, a region of the radial outer surface of the main metal fitting covered with the element protector, and a tip surface of the main metal fitting. When is defined as the protector internal area,
The main metal fitting protection member and the element protector cover at least a region on the tip side of the protector internal region of the main metal fitting with respect to the protector facing surface.
The sensor according to claim 1. The main metal fitting protection member is formed in a tubular shape having an insertion hole through which the sensor element is inserted.
The sensor according to claim 1 or 2. The main metal fitting protection member includes a protector contact portion that contacts the inner surface of the element protector in the circumferential direction.
The sensor according to any one of claims 1 to 3. An inwardly projecting inner protrusion is provided on the rear end side of the main metal fitting protection member.
The sensor according to any one of claims 1 to 4. The sensor according to any one of claims 1 to 5, wherein the main metal fitting protecting member is made of a material having higher heat resistance than the main metal fitting. The main metal fitting protection member is made of a metal material.
The sensor according to any one of claims 1 to 6. The main metal fitting protection member is made of a material having higher corrosion resistance than the main metal fitting.
The sensor according to any one of claims 1 to 7. The main metal fitting protection member is configured to cover a region of the inner surface of the through hole on the tip side of the element holding member and to abut on the element holding member.
The sensor according to claim 8. The element holding member is configured to include a ceramic holder that abuts on the sensor element and a metal holder that is arranged outside the ceramic holder and abuts on the main metal fitting.
The main metal fitting protection member is configured to cover a region of the inner surface of the through hole on the tip side of the element holding member and to abut on at least one of the ceramic holder and the metal holder.
The sensor according to claim 9.