JP7194257B2 - GAS SENSOR AND METHOD FOR MANUFACTURING GAS SENSOR - Google Patents

Description

The present invention relates to a gas sensor and its manufacturing method.

2. Description of the Related Art Conventionally, there is known a gas sensor that is attached to an automobile exhaust pipe or the like and used to detect specific gas components (for example, oxygen, NOx, etc.) in a gas to be measured (exhaust gas). As such a gas sensor, Patent Document 1 discloses a sensor element extending in the axial direction and having an electrode terminal portion on the rear end side, a metal shell surrounding the sensor element, and a cylindrical metal shell extending in the axial direction. and a metal outer cylinder attached to a portion on the rear end side of the gas sensor.

JP 2019-2936 A

Further, the gas sensor includes a terminal fitting extending in the axial direction and having a distal end side connection portion to which the electrode terminal portion of the sensor element is connected, and a tubular shape extending in the axial direction, separated from the inner peripheral surface of the outer cylinder. A separator that is arranged inside the outer cylinder and accommodates the tip end connection part of the terminal fitting and the part having the electrode terminal part of the sensor element inside, and the rear end connection located on the rear end side of the terminal fitting. and a tubular rubber cap extending in the axial direction and fixed to the outer cylinder in such a manner as to close the rear end opening of the outer cylinder. In addition, the separator consists of a cylindrical separator main body formed by combining two insulating members made of insulating ceramics, and a main body holding portion (separator) for holding the cylindrical separator main body by combining two insulating members a portion that surrounds the periphery of the separator body and holds the tubular shape of the separator body). In this gas sensor, the rear-end connection portion of the terminal fitting is inserted into the through-hole extending through the rubber cap in the axial direction, and is located on the rear-end side of the rear-end connection portion of the lead wire. A portion of the cap inserted into the through hole is fixed in close contact with the through hole.

By the way, in the gas sensor described above, the separator is separated from the inner cylinder, which is the tip-side member. The tip side member is a member positioned closest to the separator among the members positioned on the tip side with respect to the separator, and is a member through which the sensor element is inserted in the axial direction. Furthermore, the separator is also spaced apart from the rubber cap, which is a member on the rear end side. The rear end member is the member positioned closest to the separator among the members positioned on the rear end side with respect to the separator. Therefore, in the gas sensor described above, the separator is not fixed inside the outer cylinder.

Therefore, when force is applied to the gas sensor from the outside or vibration is transmitted to the gas sensor from the outside, the direction in which the separator intersects the outer cylinder relative to the axial direction (for example, the outer cylinder radial direction). As a result, the distal end connection portion of the terminal fitting accommodated inside the separator may vibrate in a direction intersecting the axial direction relative to the outer cylinder (referred to as an axial intersecting direction). On the other hand, since the rubber cap fixed to the outer cylinder does not vibrate (or does not easily vibrate) relative to the outer cylinder, the rear end connection portion of the terminal fitting inserted in the rubber cap also Does not vibrate (or does not vibrate easily) relative to

For this reason, in the terminal fitting extending in the axial direction, the distal end side connecting portion of the terminal fitting vibrates in the axial cross direction relative to the rear end side connecting portion. A stress (for example, a shear stress) is generated between the terminal and the terminal fitting, and the terminal fitting may break between the front end side connection portion and the rear end side connection portion. For this reason, in the gas sensor, it has been required to reduce the vibration of the separator relative to the outer cylinder in the direction crossing the axis (the direction intersecting with the direction of the axis).

SUMMARY OF THE INVENTION It is an object of the present invention to provide a gas sensor in which the separator is less likely to vibrate in the cross-axis direction relative to the outer cylinder, and a method of manufacturing the same.

a sensor element extending in the axial direction and having an electrode terminal portion on the rear end side; a metallic shell surrounding the sensor element; an attached metal outer cylinder; a terminal fitting extending in the axial direction and having a distal end side connection portion to which the electrode terminal portion of the sensor element is connected; a separator disposed inside the outer cylinder in a manner spaced apart from the inner peripheral surface of the cylinder, and accommodating therein the tip end side connecting portion of the terminal fitting and a portion of the sensor element having the electrode terminal portion; and a lead wire extending toward the rear end and connected to a rear end connection portion of the terminal fitting located on the rear end side. a holding part that holds the separator in contact with the separator; and a holding part that holds the separator in contact with the separator; It is preferable that the gas sensor has an outer cylinder contact portion that contacts the peripheral surface, and that the outer cylinder contact portion is welded only to the outer cylinder and fixed to the outer cylinder.

The gas sensor described above includes a holding fixture that holds the separator. The holding metal fitting has a cylindrical shape extending in the axial direction and is arranged inside the outer cylinder in a manner surrounding the periphery (periphery) of the separator to hold the separator. The holding fitting has a holding portion that contacts and holds the separator, and an outer cylinder contact portion that contacts the inner peripheral surface of the outer cylinder. This holding metal fitting is fixed to the outer cylinder by welding the outer cylinder contact portion to the outer cylinder. Therefore, in the gas sensor described above, the separator is fixed to the outer cylinder via the metal fitting.

Therefore, in the above-described gas sensor, when force is applied to the gas sensor from the outside or vibration is transmitted to the gas sensor from the outside, "the direction in which the separator intersects the outer cylinder relative to the axial direction (for example, the outer Vibration in the radial direction of the cylinder) is less likely to occur. Therefore, the gas sensor described above is a gas sensor in which the separator is less likely to vibrate in the cross-axis direction relative to the outer cylinder.

By the way, as a method of manufacturing a gas sensor, the tip end portion of the holding metal fitting and the tip end portion of the outer cylinder are collectively welded to the metal shell. is welded to the outer cylinder. In contrast, in the gas sensor described above, the outer cylinder contact portion of the holding metal fitting is welded only to the outer cylinder. That is, only two members, the holding metal fitting (outer cylinder contact portion) and the outer cylinder, are welded. In other words, the metal fitting is joined (fixed) to the outer cylinder by the weld formed only by the outer cylinder contact portion of the metal fitting and the outer cylinder. Therefore, compared to the former case of welding three members, the metal fitting can be easily welded to the outer cylinder.

Furthermore, in the gas sensor described above, since the welded portion is formed by only the two members of the holding metal fitting and the outer cylinder, compared to the case where the welded portion is formed by the three members of the holding metal fitting, the outer cylinder, and the metal shell, Thus, cracking of the weld due to differences in thermal expansion between the members forming the weld can be reduced. This is because the fewer the types of members forming the welded portion, the less likely the welded portion will crack due to the difference in thermal expansion between the members forming the welded portion.

As the separator, for example, a cylindrical separator made of insulating ceramics can be used. In addition, a cylindrical separator main body formed by combining a plurality of insulating members made of insulating ceramics, and a main body holding portion (for example, a separator main body) for holding a state in which a plurality of insulating members are combined to form a cylindrical separator main body and a separator that surrounds the periphery of the separator and retains the tubular shape of the separator main body.

An aspect of the present invention is the gas sensor described above, wherein the welded portion between the outer cylinder contact portion of the holding metal and the outer cylinder is formed closer to the inner peripheral surface than the outer peripheral surface of the outer cylinder. gas sensor .

In the gas sensor described above, the welded portion (the portion solidified after being melted) between the outer cylinder contact portion of the holding fitting and the outer cylinder is formed closer to the inner peripheral surface than the outer peripheral surface of the outer cylinder. That is, the welded portion between the outer cylinder contact portion of the holding metal fitting and the outer cylinder is formed without being exposed on the outer peripheral surface of the outer cylinder. Welded parts are more likely to corrode than parts that are not welded (parts that remain as the base material). Less corrosive. On the other hand, in the gas sensor described above, since the welded portion between the outer cylinder contact portion of the holding metal and the outer cylinder is not exposed on the outer peripheral surface of the outer cylinder, deterioration of the corrosion resistance of the outer cylinder can be suppressed.

Further, in any one of the above gas sensors, an annular portion of the outer cylinder having a welded portion in the circumferential direction with the outer cylinder contact portion has an average thickness in the range of 0.3 mm or more and 1.0 mm or less. It is better to use it as a gas sensor.

In the gas sensor described above, the average thickness of the annular portion of the outer cylinder, which has the welded portion welded to the outer cylinder contact portion of the holding metal fitting in the circumferential direction, is set to a value within the range of 0.3 mm or more and 1.0 mm or less. ing. By doing so, a gas sensor is obtained in which the outer cylinder is appropriately welded to the outer cylinder contact portion of the metal fitting while ensuring the necessary strength for the outer cylinder.

Further, in any one of the gas sensors described above, the average thickness of the contact portion of the outer cylinder of the metal fitting may be in the range of 0.2 mm or more and 1.0 mm or less.

In the gas sensor described above, the average thickness of the outer cylinder contact portion of the metal fitting that is welded to the outer cylinder is set to a value within the range of 0.2 mm or more and 1.0 mm or less. By doing so, a gas sensor in which the outer cylinder contact portion of the metal fitting is appropriately welded to the outer cylinder while ensuring the strength necessary for the metal fitting is obtained.

Another aspect of the present invention is any one of the gas sensor manufacturing methods described above, wherein the holding portion of the holding fitting contacts the separator, and the outer cylinder contact portion of the holding fitting contacts the outer cylinder. an arrangement step of placing the holding metal fitting inside the outer cylinder while surrounding the periphery of the separator so as to contact the inner peripheral surface; and welding only the outer cylinder and the outer cylinder contact portion. and a welding process for manufacturing a gas sensor.

In the manufacturing method described above, after performing the arranging step, in the welding step, the outer cylinder and the outer cylinder contact portion of the metal fitting are welded. As a result, the separator can be fixed to the outer cylinder via the holding metal fitting. Therefore, according to the manufacturing method described above, it is possible to appropriately manufacture a gas sensor in which the separator is fixed to the outer cylinder via the holding metal fitting.

In the gas sensor manufactured in this way, when force is applied to the gas sensor from the outside or vibration is transmitted to the gas sensor from the outside, the "direction in which the separator intersects the outer cylinder relative to the axial direction ( For example, vibration in the radial direction of the outer cylinder) is less likely to occur. Therefore, according to the manufacturing method described above, it is possible to manufacture a gas sensor in which the separator is less likely to vibrate in the cross-axis direction relative to the outer cylinder.

Moreover, in the manufacturing method described above, only the outer cylinder and the outer cylinder contact portion of the metal fitting (ie, only the two members) are welded together in the welding process. Therefore, the metal fitting can be welded to the outer cylinder more easily than the case where the three members of the metal fitting, the outer cylinder, and the metal shell are welded as described above. Furthermore, since the welded portion is composed of only the two members, the holding metal fitting and the outer cylinder, compared to the case where the welded portion is composed of the three members, the holding metal fitting, the outer cylinder, and the metal shell, the welded portion constitutes the welded portion. The occurrence of cracks in the weld due to differences in thermal expansion between the members may be reduced.

Further, in the method of manufacturing the gas sensor, the welding step may be a resistance welding step of resistance welding only the outer cylinder and the outer cylinder contact portion.

In the above-described manufacturing method, the outer cylinder and the outer cylinder contact portion of the holding metal fitting are joined by resistance welding. It is formed without being exposed on the outer peripheral surface of the cylinder. In this way, by not exposing the welded portion, which is more likely to corrode than the non-welded portion (the portion where the base material remains), to the outer peripheral surface of the outer cylinder, the deterioration of the corrosion resistance of the outer cylinder can be prevented. can be suppressed.

1 is a longitudinal sectional view of a gas sensor according to an embodiment; FIG. FIG. 2 is an enlarged view of a B portion in FIG. 1; 1 is a perspective view of a sensor element; FIG. FIG. 3 is a partially enlarged vertical cross-sectional view of the gas sensor; It is a top view (top view) of a holding metal fitting. It is a side view of the same holding metal fittings. FIG. 6 is a cross-sectional view taken along line DD of FIG. 5; FIG. 3 is an enlarged view of a C portion in FIG. 2; It is a figure explaining the manufacturing method of the gas sensor concerning embodiment. FIG. 10 is an enlarged view of part E in FIG. 9;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a vertical cross-sectional view of the gas sensor 1 of the embodiment, and is a cross-sectional view of the gas sensor 1 cut in the axial direction DX at a position passing through the axis AX of the gas sensor 1 (however, the sensor element 5 is not cut). . In addition, in FIG. 1 , the lower side is the front end side of the gas sensor 1 and the upper side is the rear end side of the gas sensor 1 . 2 is an enlarged view of the B portion of FIG. 1. FIG. 4 is a partially enlarged vertical cross-sectional view of the gas sensor 1, showing the axial direction at a position different from that in FIG. 2 is a partially enlarged cross-sectional view of the gas sensor 1 cut along DX (terminal metal fittings 41 to 44 and lead wires 31 to 34 are not cut); FIG.

The gas sensor 1 is attached to an exhaust pipe of an automobile or the like (not shown) in such a manner that the portion on the tip side thereof is inserted into the exhaust pipe, and is used with the tip side directed downward. Specifically, the gas sensor 1 detects a specific gas component (for example, oxygen, NOx, etc.) in the exhaust gas (gas to be measured). The gas sensor 1 includes a sensor element 5, a metal shell 3, a protector 9, and an outer cylinder 11, as shown in FIG.

Among them, the sensor element 5 has a bar shape extending in the axial direction DX (the direction along the axis AX of the gas sensor 1, the vertical direction in FIG. 1), and has a protective layer ( not shown). The detection unit 5b detects a specific gas component (for example, oxygen, NOx, etc.) in the exhaust gas (gas to be measured). Furthermore, the sensor element 5 has four electrode terminal portions (a first electrode terminal portion 5f, a second electrode terminal portion 5g, a third electrode terminal portion 5j, and a fourth electrode terminal portion 5k) on the rear end side (Fig. 3). The sensor element 5 is inserted into the through hole 3 f of the metallic shell 3 . More specifically, the sensor element 5 has a detection portion 5b positioned on the front end side, which projects from a front end surface 3d of the metal shell 3 to the front end side, and four electrode terminal portions (first electrode terminals) positioned on the rear end side. The terminal portion 5f to the fourth electrode terminal portion 5k) are fixed in the through hole 3f of the metal shell 3 in a state of protruding from the rear end of the metal shell 3 to the rear end side.

The metal shell 3 surrounds the sensor element 5 and holds the sensor element 5 (holds it via another member). The metal shell 3 has a cylindrical shape extending in the axial direction DX, has a through hole 3f extending from the front end side to the rear end side, and has a screw portion 3m for fixing itself to the exhaust pipe on its outer surface ( See Figure 1). A shelf portion 3k that protrudes radially inward is formed in the through hole 3f. Further, the metal shell 3 has a cylindrical distal side wall portion 3c including a distal end surface 3d. The metal shell 3 is made of a metal material (for example, stainless steel).

Inside the through hole 3f of the metal shell 3, there are an annular holder 61 made of an insulating material (such as alumina), talc powder-filled layers 63 and 65, and an annular sleeve made of an insulating material (such as alumina). 67 are arranged to surround the sensor element 5 in the radial direction (see FIG. 1). A crimping packing 69 is arranged between the sleeve 67 and the rear end portion of the metallic shell 3 . A cylindrical metal holder 71 for holding the talc powder-filled layer 63 and the holder 61 is arranged between the holder 61 and the shelf portion 3k of the metal shell 3 . The rear end of the metallic shell 3 is crimped by crimping packing 69 to press the sleeve 67 toward the front end (see FIG. 1).

The protector 9 has a cylindrical shape and is fixed to a portion of the metallic shell 3 on the distal end side. Specifically, the protector 9 surrounds the tip side portion of the sensor element 5 (the portion projecting from the tip surface 3d of the metal shell 3 to the tip side), and the outer peripheral surface of the tip side wall portion 3c of the metal shell 3. is fixed by welding or the like (not shown). This protector 9 is made of a heat-resistant material (such as NCF601, for example). The protector 9 includes a cylindrical first protector 9b (inner protector) that constitutes the measurement chamber S in which the detection part 5b of the sensor element 5 is arranged, and a cylindrical second protector 9d that surrounds the outer circumference of the first protector 9b ( It has a double tube structure with an outer protector). The first protector 9b is formed with a plurality of vent holes 9c through which the gas to be measured can pass. The second protector 9d is formed with a plurality of vent holes 9f through which the gas to be measured can pass (see FIG. 1).

The outer cylinder 11 is made of metal and has a cylindrical shape extending in the axial direction DX. The outer cylinder 11 is attached (welded) to the rear end portion of the metal shell 3 and surrounds the rear end portion of the sensor element 5 (see FIG. 1).

Furthermore, the gas sensor 1 includes four terminal fittings (first terminal fitting 41, second terminal fitting 42, third terminal fitting 43, fourth terminal fitting 44), a separator 13, and four lead wires (first lead wire). wire 31, second lead wire 32, third lead wire 33, and fourth lead wire 34) and a rubber cap 15 (see FIGS. 1 and 2). Of these, four terminal fittings (first terminal fitting 41 to fourth terminal fitting 44) are each made of an elastic heat-resistant metal (for example, stainless steel) and extend in the axial direction DX.

The first terminal fitting 41 includes a first tip end side connection portion 41b to which the first electrode terminal portion 5f of the sensor element 5 is connected, and the first lead wire 31 (specifically, the metal core wire 31b in the first lead wire 31). ) is connected (see FIGS. 1 and 2). The second terminal fitting 42 includes a second tip end side connection portion 42b to which the second electrode terminal portion 5g of the sensor element 5 is connected, and the second lead wire 32 (specifically, the metal core wire 32b in the second lead wire 32). ) is connected to the second rear end side connection portion 42c. The third terminal fitting 43 includes a third tip end side connection portion 43b to which the third electrode terminal portion 5j of the sensor element 5 is connected, and the third lead wire 33 (specifically, the metal core wire 33b in the third lead wire 33). ) is connected to the third rear end side connection portion 43c. The fourth terminal fitting 44 includes a fourth tip end side connection portion 44b to which the fourth electrode terminal portion 5k of the sensor element 5 is connected, and the fourth lead wire 34 (more specifically, the metal core wire 34b in the fourth lead wire 34). ) is connected (see FIGS. 1 and 2).

The separator 13 is made of ceramic (for example, alumina, steatite, etc.) and has a cylindrical shape extending in the axial direction DX. The separator 13 is arranged inside the outer cylinder 11 in such a manner that it is separated from the inner peripheral surface 11b of the outer cylinder 11 (that is, in a manner that it does not directly contact the inner peripheral surface 11b of the outer cylinder 11) ( 1 and 2). In addition, in the gas sensor 1 of the present embodiment, a holding metal fitting 20 is interposed between the outer peripheral surface 13g of the separator 13 and the inner peripheral surface 11b of the outer cylinder 11 as will be described later. The aspect in which the outer peripheral surface 13g of the separator 13 and the inner peripheral surface 11b of the outer cylinder 11 are connected is also included in the "aspect in which the separator 13 is separated from the inner peripheral surface 11b of the outer cylinder 11".

Furthermore, the separator 13 has a through-hole 13c passing through itself in the axial direction DX. In this through hole 13c, there are four tip side connection portions (first tip side connection portion 41b to fourth tip side connection portion 44b) of four terminal fittings (first terminal fitting 41 to fourth terminal fitting 44), A rear end portion 5c having four electrode terminal portions (first electrode terminal portion 5f to fourth electrode terminal portion 5k) of the sensor element 5 is accommodated (see FIGS. 1 and 2). Further, the separator 13 has an annular collar portion 13b protruding radially outward on its rear end side.

The rubber cap 15 is made of heat-resistant rubber and has a tubular shape (columnar shape) extending in the axial direction DX. The rubber cap 15 is fixed to the outer cylinder 11 so as to close the rear end opening 11c of the outer cylinder 11 (see FIG. 1). Specifically, the rubber cap 15 is fixed to the outer cylinder 11 by crimping the rear end portion of the outer cylinder 11 radially inward. The rubber cap 15 has four through holes 15b extending through the rubber cap 15 in the axial direction DX (see FIG. 4).

In the gas sensor 1 of the present embodiment, four rear end side connection portions (first rear end side connection portion 41c to fourth rear end side connection portion) of four terminal metal fittings (first terminal metal fitting 41 to fourth terminal metal fitting 44) 44c), at least the rear ends (first rear end 41d, second rear end 42d, third rear end 43d, and fourth rear end 44d) are inserted into the through hole 15b of the rubber cap 15. inserted. In the present embodiment, the rear end portions (first rear end portion 41d, second rear end portion 41d, second rear end portion 42d, the third rear end portion 43d, and the fourth rear end portion 44d) are inserted into the through hole 15b of the rubber cap 15 (see FIG. 4).

Furthermore, four rear end side connection portions (first rear end side connection portion 41c to fourth rear end side connection portion 44c) of the four lead wires (first lead wire 31 to fourth lead wire 34) The parts (first part 31 c, second part 32 c, third part 33 c, fourth part 34 c ) located on the rear end side and inserted into the through hole 15 b of the rubber cap 15 are the through holes of the rubber cap 15 . 15b (cylindrical surface forming the through hole 15b). Four lead wires (first lead wire 31 to fourth lead wire 34) extend outside the rubber cap 15 from the rear end side of the through hole 15b of the rubber cap 15 (see FIG. 4).

Furthermore, the gas sensor 1 of this embodiment includes a holding metal fitting 20 that holds the separator 13 (see FIGS. 1 and 2). The holding metal fitting 20 has a cylindrical shape extending in the axial direction DX, and is arranged inside the outer cylinder 11 so as to surround (periphery) the separator 13 to hold (support) the separator 13 . The holding metal fitting 20 has a holding portion 21 that contacts the separator 13 to hold the separator 13 and an outer cylinder contact portion 23 that contacts the inner peripheral surface 11 b of the outer cylinder 11 . The holding metal fitting 20 is fixed to the outer cylinder 11 by welding the outer cylinder contact portion 23 to the outer cylinder 11 .

Specifically, as shown in FIGS. 5 to 7, the metal fitting 20 includes a cylindrical body portion 25 and a plurality of curved rectangular plates that are bent from the inside of the rear end portion 25b of the body portion 25 and extend toward the distal end side. a plurality of curved rectangular plate-shaped outer cylinder contact portions 23 positioned radially outside the cylindrical side wall portion 25c of the body portion 25; It has a connection part 22 to be connected. For example, the outer cylinder contact portion 23 and the connecting portion 22 are spaced apart from the front end of the side wall portion 25c of the main body portion 25 in the circumferential direction of the side wall portion 25c in the axial direction DX (vertical direction in FIGS. 5 and 7). ), and deform the part sandwiched between the cuts (the part that becomes the outer cylinder contact portion 23 and the connecting portion 22) radially outward of the side wall portion 25c. be done.

Four holding portions 21 are provided at equal intervals in the circumferential direction of the body portion 25 . A rear end portion 21b of each holding portion 21 contacts (abuts) a tip side surface 13h (a part of the outer peripheral surface 13g of the separator 13) of the flange portion 13b (see FIG. 2). Therefore, the four holding portions 21 hold the separator 13 in such a manner as to support the flange portion 13b of the separator 13 from the tip side (lower side). Further, each holding portion 21 is a plate spring and elastically deforms in the radial direction of the body portion 25 . The four holding portions 21 are arranged at equal intervals in the circumferential direction of the outer peripheral surface 13g of the separator 13, and are in contact with the outer peripheral surface 13g of the separator 13 in a state of being elastically deformed radially outward. As a result, the outer peripheral surface 13g of the separator 13 is pressed by the radially inward elastic restoring force of the four holding portions 21 arranged at equal intervals in the circumferential direction. Therefore, the separator 13 is also held by the radially inward elastic restoring forces of the four holding portions 21 arranged at equal intervals in the circumferential direction of the outer peripheral surface 13g (see FIG. 2).

The holding metal fitting 20 is fixed to the outer cylinder 11 by welding the outer cylinder contact portion 23 to the outer cylinder 11 . Therefore, in the gas sensor 1 of this embodiment, the separator 13 is held by the holding metal fitting 20 fixed to the outer cylinder 11 . In other words, the separator 13 is fixed to the outer cylinder 11 via the holding metal fittings 20 . The outer cylinder 11 is fixed by welding to a rear end portion of the metal shell 3 (an outer cylinder fixing portion 3h). Also, the metal shell 3 is fixed to an exhaust pipe (not shown) by a screw portion 3m. Therefore, the outer cylinder 11 is fixed to the exhaust pipe through the metallic shell 3 .

In such a gas sensor 1, when a force is applied to the gas sensor 1 from the outside or vibration is transmitted to the gas sensor 1 from the outside, "the separator 13 intersects the outer cylinder 11 relative to the axial direction DX. Vibration in a direction (for example, radial direction of the outer cylinder 11) is less likely to occur. Therefore, it can be said that the gas sensor 1 of the present embodiment is a gas sensor 1 in which the separator 13 is less likely to vibrate in the cross-axis direction relative to the outer cylinder 11 .

Furthermore, in the four terminal fittings (first terminal fitting 41 to fourth terminal fitting 44), the four front end side connection portions (first front end side connection portion 41b to fourth front end side connection portion 41b) accommodated inside the separator 13 The connecting portion 44b) is also less likely to vibrate relative to the outer cylinder 11 in a direction intersecting the axial direction DX (referred to as an axial intersecting direction) (see FIG. 2). In the gas sensor 1, since the rubber cap 15 is fixed to the outer cylinder 11, the rear end portions (first rear end portion 41d, second rear end portion 42d, third rear end portion 41d, third rear end portion 42d, third rear end portion 41d, second rear end portion 42d, third rear end portion 41d, and third rear end portion 41d) are inserted into the through hole 15b of the rubber cap 15. The four rear end side connection portions (first rear end side connection portion 41c to fourth rear end side connection portion 44c) into which the end portion 43d and the fourth rear end portion 44d) are inserted are It is relatively difficult to vibrate in the cross-axis direction (see FIG. 4).

Therefore, in the gas sensor 1 of the present embodiment, in the four terminal fittings (first terminal fitting 41 to fourth terminal fitting 44) extending in the axial direction DX, the "tip end side connection portion (first tip end side connection part 41b to 4 front end side connection portion 44b) is less likely to vibrate in the cross-axis direction relative to the rear end side connection portions (first rear end side connection portion 41c to fourth rear end side connection portion 44c). Therefore, stress (for example, shear stress) is less likely to occur in the terminal fittings (first terminal fitting 41 to fourth terminal fitting 44), and breakage of the terminal fittings (first terminal fitting 41 to fourth terminal fitting 44) also occurs. it gets harder.

By the way, as a gas sensor, the tip portion of the holding metal fitting and the tip portion of the outer cylinder are welded together to the metal shell. A gas sensor welded to the barrel is conceivable. On the other hand, in the gas sensor 1 of this embodiment, the outer cylinder contact portion 23 of the holding metal fitting 20 is welded only to the outer cylinder 11 . That is, only two members, the holding metal fitting 20 (outer cylinder contact portion 23) and the outer cylinder 11, are welded. In other words, the metal fitting 20 is joined (fixed) to the outer cylinder 11 by the weld W formed only by the outer cylinder contact portion 23 of the metal fitting 20 and the outer cylinder 11 (see FIG. 8). Therefore, in manufacturing the gas sensor, the holding metal fitting 20 can be easily welded to the outer cylinder 11 in this embodiment, compared to the former case of welding three members.

Furthermore, in the gas sensor 1 of the present embodiment, the welded portion W is formed by only two members, the holding metal fitting 20 and the outer cylinder 11 (see FIG. 8). Cracks in the welded portion W due to the difference in thermal expansion between the members forming the welded portion W can be reduced compared to the case where the welded portion is formed by . This is because the fewer the types of members that form the welded portion W, the less likely the welded portion W will crack due to the difference in thermal expansion between the members that form the welded portion W.

Furthermore, in the gas sensor 1 of the present embodiment, the welded portion W (the portion solidified after being melted) between the outer cylinder contact portion 23 of the holding metal fitting 20 and the outer cylinder 11 is closer to the inner peripheral surface than the outer peripheral surface 11 g of the outer cylinder 11 . 11b side (see FIG. 8). That is, the welded portion W between the outer cylinder contact portion 23 of the holding metal fitting 20 and the outer cylinder 11 is formed without being exposed on the outer peripheral surface 11 g of the outer cylinder 11 . The welded portion W is more likely to corrode than a non-welded portion (a portion where the base material remains as it is). Corrosion resistance of the outer cylinder 11 including is lowered. On the other hand, in the gas sensor 1 of this embodiment, the welded portion W between the outer cylinder contact portion 23 of the holding metal fitting 20 and the outer cylinder 11 is not exposed to the outer peripheral surface 11g of the outer cylinder 11. A decrease in corrosiveness can be suppressed.

In this embodiment, the outer cylinder contact portion 23 of the holding metal fitting 20 and the outer cylinder 11 are welded by resistance welding. For this reason, the welded portion W between the outer cylinder contact portion 23 of the holding metal fitting 20 and the outer cylinder 11 is closer to the inner peripheral surface 11b than the outer peripheral surface 11g of the outer cylinder 11, and the outer cylinder contact portion 23 of the holding metal fitting 20 is formed closer to the outer surface 23c than the inner surface 23b of the (see FIG. 8). That is, the welded portion W is formed without being exposed on the outer peripheral surface 11g of the outer cylinder 11 and also without being exposed on the inner surface 23b of the outer cylinder contact portion 23 of the holding metal fitting 20 (see FIG. 8).

Furthermore, in the gas sensor 1 of the present embodiment, the annular portion 11f of the outer cylinder 11 having the welded portion W welded to the outer cylinder contact portion 23 of the holding metal fitting 20 in the circumferential direction of the outer cylinder 11 has an average thickness of is a value within the range of 0.3 mm or more and 1.0 mm or less. By doing so, the gas sensor 1 in which the outer cylinder 11 is appropriately welded to the outer cylinder contact portion 23 of the holding metal fitting 20 while securing the necessary strength for the outer cylinder 11 is obtained. In addition, in this embodiment, the average thickness of the annular portion 11f is the average value of the thicknesses of the six portions of the metal fitting 20 that come into contact with the six outer cylinder contact portions 23 .

Furthermore, in the gas sensor 1 of the present embodiment, the average thickness of the outer cylinder contact portion 23 of the metal fitting 20 welded to the outer cylinder 11 is set to a value within the range of 0.2 mm or more and 1.0 mm or less. By doing so, the gas sensor 1 in which the outer cylinder contact portion 23 of the metal fitting 20 is appropriately welded to the outer cylinder 11 while securing the strength necessary for the metal fitting 20 is obtained. In addition, in the present embodiment, the average thickness of the outer cylinder contact portion 23 is the average value of the thicknesses of the six outer cylinder contact portions 23 provided on the metal fitting 20 .

Next, a method for manufacturing the gas sensor 1 of this embodiment will be described. First, outer cylinder 11, separator 13, four terminal fittings (first terminal fitting 41 to fourth terminal fitting 44), four lead wires (first lead wire 31 to fourth lead wire 34), and rubber cap 15 The rear end side assembly 1B is produced by the holding metal fitting 20 (see FIG. 9). Specifically, first, four lead wires (the first lead wire 31 to the fourth lead wire 34) are inserted through the outer cylinder 11 from the tip side, and furthermore, the four through holes 15b of the rubber cap 15 and the The through hole 13c of the separator 13 is also inserted. After that, the four lead wires (first lead wire 31 to fourth lead wire 34) are connected to four terminal fittings (first terminal fitting 41 to fourth terminal fitting 44) at the rear end side connecting portions (first rear end (see FIG. 4).

Next, the rear ends (first rear end 41d to fourth rear end 44d) of the four rear end side connection portions (first rear end side connection portion 41c to fourth rear end side connection portion 44c) are rubber caps. 15 and is housed in the through hole 15b of the four terminal fittings (first terminal fitting 41 to fourth terminal fitting 44). ) are accommodated in the through holes 13c of the separator 13, the positions of the four lead wires (the first lead wire 31 to the fourth lead wire 34) are adjusted. After that, the holding metal fitting 20 is attached to the periphery (periphery) of the separator 13 in such a manner that the holding portion 21 of the holding metal fitting 20 is brought into contact with the outer peripheral surface 13g of the separator 13 . Specifically, the rear end portion 21b of the holding portion 21 of the holding metal fitting 20 is brought into contact with the tip side surface 13h (a part of the outer peripheral surface 13g of the separator 13) of the flange portion 13b of the separator 13 (as shown in the figure). 10).

Next, in the placement step, the holding portion 21 of the holding metal fitting 20 contacts the outer peripheral surface 13 g of the separator 13 and the outer cylinder contact portion 23 of the holding metal fitting 20 contacts the inner peripheral surface 11 b of the outer cylinder 11 . , the holding metal fitting 20 surrounds the separator 13 and is arranged inside the outer cylinder 11 (see FIG. 9). Specifically, first, the rubber cap 15 through which the four lead wires (the first lead wire 31 to the fourth lead wire 34) are inserted is removed from the front end side (lower side in FIG. 9) of the outer cylinder 11. The holding metal fitting 20 is inserted into the cylinder 11 and attached to the periphery of the separator 13, together with the separator 13 accommodating the tip end side connection portions (first tip end side connection portion 41b to fourth tip end side connection portion 44b). It is inserted into the cylinder 11 so that the rubber cap 15 is arranged inside the rear end side opening 11c of the outer cylinder 11 . In this state, the rear end portion of the outer cylinder 11 is crimped radially inward to fix the rubber cap 15 to the outer cylinder 11 . As a result, the holding portion 21 of the holding metal fitting 20 contacts the outer peripheral surface 13 g of the separator 13 and the outer cylinder contact portion 23 of the holding metal fitting 20 contacts the inner peripheral surface 11 b of the outer cylinder 11 . , are placed inside the outer cylinder 11 while surrounding the separator 13 (see FIG. 9).

In the present embodiment, the placement step described above is performed using the second electrode 92 of the resistance welder 90 used in the resistance welding step described below. Specifically, as shown in FIG. 9, the ring-shaped distal end portion 92b of the second electrode 92 is placed between the outer peripheral surface 13g of the portion on the distal end side (lower side in FIG. 9) of the separator 13 and the holding metal fitting 20. The holding metal fitting 20 is attached to the tip portion 92b of the second electrode 92 together with the separator 13 by inserting it between the outer cylinder contact portion 23 and the inner side surface 23b. In this state, by inserting the distal end portion 92b of the second electrode 92 into the outer cylinder 11 from the distal end side of the outer cylinder 11, the holding portion 21 of the holding metal fitting 20 contacts the outer peripheral surface 13g of the separator 13, The metal retainer 20 surrounds the separator 13 and is arranged inside the outer cylinder 11 in such a manner that the outer cylinder contact portion 23 of the metal retainer 20 contacts the inner peripheral surface 11 b of the outer cylinder 11 . (See Figure 9).

Further, the connecting portion 22 of the holding metal fitting 20 is a plate spring, and is elastically deformed in the radial direction of the body portion 25 . In addition, the maximum outer diameter of the holding metal fitting 20 (the outer diameter of the holding metal fitting 20 at the position of the outer side surface 23c of the two outer cylinder contact portions 23 facing in the radial direction) is the natural state (the connecting portion 22 is not elastically deformed). state), it is slightly larger than the inner diameter of the outer cylinder 11 (the diameter of the inner peripheral surface 11b). Further, the outer surface 23c of the outer cylinder contact portion 23 and the inner peripheral surface 11b of the outer cylinder 11 have the same curvature. When the holding metal fitting 20 is inserted into the outer cylinder 11, the connecting portion 22 of the holding metal fitting 20 is slightly elastically deformed radially inward, and the outer surface 23c of the outer cylinder contact portion 23 of the holding metal fitting 20 is deformed. The holding metal fitting 20 is configured so as to contact the inner peripheral surface 11b of the outer cylinder 11 without gaps.

Therefore, as described above, when the holding metal fitting 20 is inserted and arranged inside the outer cylinder 11 in the arrangement process, the outer surface 23c of the outer cylinder contact portion 23 of the holding metal fitting 20 is aligned with the inner peripheral surface 11b of the outer cylinder 11. (See FIG. 10). Furthermore, the inner side surface 23b of the outer cylinder contact portion 23 of the holding metal fitting 20 comes into contact with the outer peripheral surface 92c of the tip portion 92b of the second electrode 92 . A resistance welding process is performed in this state.

Specifically, a resistance welder 90 having a first electrode 91 and a second electrode 92 is used to resistance-weld the outer cylinder 11 and the outer cylinder contact portion 23 of the holding metal fitting 20 (see FIG. 9). More specifically, the first electrode 91 is brought into contact with a portion of the outer peripheral surface 11g of the outer cylinder 11 where the outer cylinder contact portion 23 of the holding metal fitting 20 is disposed radially inward, thereby The outer cylinder 11 and the outer cylinder contact portion 23 are sandwiched between the outer cylinder 11 and the second electrode 92 . In this state, by applying a current between the first electrode 91 and the second electrode 92, the outer cylinder 11 and the outer cylinder contact portion 23 of the metal fitting 20 are resistance welded (see FIG. 9). As a result, the holding metal fitting 20 is fixed to the outer cylinder 11 and the separator 13 is held by the holding metal fitting 20 fixed to the outer cylinder 11 . As a result, the outer cylinder 11, the separator 13, the four terminal fittings (the first terminal fitting 41 to the fourth terminal fitting 44), the four lead wires (the first lead wire 31 to the fourth lead wire 34), and the rubber cap 15 are connected. , and the holding metal fitting 20, a rear end assembly 1B is formed (see FIG. 9).

Separately from this, the distal end assembly 1A (Fig. 1) is prepared. After that, the rear end portion 5c of the sensor element 5 of the front end assembly 1A is inserted into the separator 13 of the rear end assembly 1B, and the four electrode terminal portions (first electrode terminal portions 5f to 5f) of the sensor element 5 are inserted. The fourth electrode terminal portion 5k) is connected to four tip end side connection portions (first tip end side connection portions 41b to 44) of the four terminal fittings (first terminal fitting 41 to fourth terminal fitting 44) housed in the separator 13. It is brought into contact with the fourth distal end side connecting portion 44b). At this time, the tip portion 11h of the outer cylinder 11 is arranged outside the outer cylinder fixing portion 3h positioned on the rear end side of the metal shell 3 (fitted). After that, the tip portion 11h of the outer cylinder 11 is joined to the outer cylinder fixing portion 3h of the metal shell 3 by laser welding (see FIG. 1). Thereby, the gas sensor 1 of this embodiment is completed.

In the gas sensor 1 manufactured in this way, since the separator 13 is fixed to the outer cylinder 11 via the holding metal fitting 20, force is applied to the gas sensor 1 from the outside, or vibration is transmitted to the gas sensor 1 from the outside. In this case, "vibration of the separator 13 relative to the outer cylinder 11 in a direction intersecting the axial direction DX (for example, the radial direction of the outer cylinder 11)" is less likely to occur. Therefore, according to the manufacturing method of this embodiment, it is possible to manufacture the gas sensor 1 in which the separator 13 is less likely to vibrate in the cross-axis direction relative to the outer cylinder 11 .

Moreover, in the manufacturing method of the present embodiment, only the outer cylinder 11 and the outer cylinder contact portion 23 of the holding metal fitting 20 (that is, only the two members) are resistance-welded in the resistance welding process (see FIG. 10). Therefore, the metal fitting can be welded to the outer cylinder more easily than the case of welding the three members of the metal fitting, the outer cylinder, and the metal shell. Furthermore, as shown in FIG. 10, the welded portion W is composed of only the two members of the holding metal fitting 20 and the outer cylinder 11, so that the welded portion is composed of the three members of the holding metal fitting, the outer cylinder and the metal shell. As compared with the case where the welded portion is formed by a thermal expansion difference between the members forming the welded portion, cracks in the welded portion can be reduced.

Furthermore, since the outer cylinder 11 and the outer cylinder contact portion 23 of the holding metal fitting 20 are joined by resistance welding, the welded portion W (melted and then solidified portion) between the outer cylinder contact portion 23 of the holding metal fitting 20 and the outer cylinder 11 ) are formed without being exposed on the outer peripheral surface 11g of the outer cylinder 11 (see FIG. 10). In this manner, by not exposing the welded portion W, which is more likely to corrode than the non-welded portion (the base material portion), to the outer peripheral surface 11g of the outer cylinder 11, the corrosion resistance of the outer cylinder 11 is improved. It is possible to suppress the decline in sexuality.

Although the present invention has been described above with reference to the embodiments, it goes without saying that the present invention is not limited to these, and can be appropriately modified and applied without departing from the gist of the present invention. For example, in the embodiment, the cylindrical separator 13 made of insulating ceramic is exemplified as the separator. However, as a separator, a cylindrical separator main body portion formed by combining a plurality of insulating members made of insulating ceramics, and a main body holding portion (for example, , and a main body holding portion that surrounds the periphery of the separator main body and holds the tubular shape of the separator main body.

Moreover, in the embodiment, the resistance welding process of resistance welding the outer cylinder and the outer cylinder contact portion of the holding metal fitting is exemplified as the welding process of welding the outer cylinder and the outer cylinder contacting portion of the holding metal fitting. However, the welding between the outer cylinder and the outer cylinder contact portion of the holding metal fitting is not limited to resistance welding, and may be performed by other welding methods such as laser welding.

1 Gas sensor 3 Metal shell 5 Sensor element 5b Detection parts 5f, 5g, 5j, 5k Electrode terminal part 11 Outer cylinder 11f Annular part 13 Separator 15 Rubber cap 20 Holding metal fitting 21 Holding part 23 Outer cylinder contact parts 31, 32, 33, 34 Lead wires 41, 42, 43, 44 Terminal fittings 41b, 42b, 43b, 44b Tip side connection portions 41c, 42c, 43c, 44c Rear end side connection portions AX Axis DX Axis direction W Welding portion

Claims (5)

a sensor element extending in the axial direction and having an electrode terminal portion on the rear end side;
a metal shell surrounding the sensor element;
a metal outer cylinder extending in the axial direction and having a tubular shape and attached to a rear end portion of the metal shell;
a terminal fitting extending in the axial direction and having a distal end side connection portion to which the electrode terminal portion of the sensor element is connected;
It has a cylindrical shape extending in the axial direction and is arranged inside the outer cylinder in a manner spaced apart from the inner peripheral surface of the outer cylinder, and the electrode terminal part of the terminal fitting and the sensor element. a separator that accommodates therein a portion having
a lead wire connected to a rear-end-side connecting portion located on the rear end side of the terminal fitting and extending toward the rear end, wherein
a holding metal fitting that has a cylindrical shape extending in the axial direction and is arranged inside the outer cylinder in a manner surrounding the periphery of the separator to hold the separator;
The holding metal fitting is
a holding part that holds the separator in contact with the separator;
an outer cylinder contact portion that contacts the inner peripheral surface of the outer cylinder;
The outer cylinder contact portion is welded only to the outer cylinder and fixed to the outer cylinder ,
A welded portion between the outer cylinder contact portion of the holding fitting and the outer cylinder is formed closer to the inner peripheral surface than the outer peripheral surface of the outer cylinder.
gas sensor. The gas sensor according to claim 1 ,
The gas sensor of the gas sensor, wherein an annular portion of the outer cylinder having a welded portion in the circumferential direction with the outer cylinder contact portion has an average thickness within a range of 0.3 mm or more and 1.0 mm or less. The gas sensor according to claim 1 or claim 2 ,
The gas sensor according to claim 1, wherein the outer cylinder contact portion of the holding metal has an average thickness in the range of 0.2 mm or more and 1.0 mm or less. a sensor element extending in the axial direction and having an electrode terminal portion on the rear end side;
a metal shell surrounding the sensor element;
a metal outer cylinder extending in the axial direction and having a tubular shape and attached to a rear end portion of the metal shell;
a terminal fitting extending in the axial direction and having a distal end side connection portion to which the electrode terminal portion of the sensor element is connected;
It has a cylindrical shape extending in the axial direction and is arranged inside the outer cylinder in a manner spaced apart from the inner peripheral surface of the outer cylinder, and the electrode terminal part of the terminal fitting and the sensor element. a separator that accommodates therein a portion having
a lead wire connected to a rear-end-side connecting portion located on the rear-end side of the terminal fitting and extending toward the rear-end side;
a holding metal fitting that has a cylindrical shape extending in the axial direction and is arranged inside the outer cylinder in a manner surrounding the periphery of the separator to hold the separator;
The holding metal fitting is
a holding part that holds the separator in contact with the separator;
an outer cylinder contact portion that contacts the inner peripheral surface of the outer cylinder;
The outer cylinder contact portion is welded only to the outer cylinder and fixed to the outer cylinder
A method for manufacturing a gas sensor, comprising:
The holding fitting surrounds the separator in such a manner that the holding portion of the holding fitting contacts the separator and the outer cylinder contact portion of the holding fitting contacts the inner peripheral surface of the outer cylinder. an arranging step of placing the device in a state of being arranged inside the outer cylinder;
and a welding step of welding only the outer cylinder and the outer cylinder contact portion. A method for manufacturing the gas sensor according to claim 4 ,
The method of manufacturing a gas sensor, wherein the welding step is a resistance welding step of resistance welding only the outer cylinder and the outer cylinder contact portion.

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