Gas sensor

Abstract

To prevent short-circuiting caused by metal pieces produced by a barrel or the like even when the barrel that crimps and holds a lead wire is accommodated inside a spacer.SOLUTION: A gas sensor according to an aspect of the present invention comprises a barrel located inside a spacer, and an outer surface of at least one of a pair of barrel pieces has a plurality of grooves formed thereon to extend in a direction intersecting an axial direction, where the spacing between adjacent grooves is smaller than the spacing between adjacent connector electrodes on a surface of a sensor element.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a gas sensor. [Background technology]

[0002] Conventionally, oxygen and NO in the gas to be measured, such as automobile exhaust gas, x Gas sensors for detecting the concentration of specific gases such as benzene, toluene ...

[0003] In such a gas sensor, the metal terminal has, for example, a barrel formed by a pair of barrel pieces rising from both left and right edges of a bottom plate on which the core wire of the lead wire is placed, and the pair of barrel pieces are crimped to the core wire by wrapping around the core wire. For example, Patent Document 2 discloses a terminal fitting (metal terminal) that has a base portion on which an electric wire is placed and a pair of barrel pieces protruding from both sides of the base portion, and both barrel pieces are crimped from the outside to the core wire exposed at the end of the electric wire. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-132407 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-129448 Summary of the Invention [Problem to be solved by the invention]

[0005] The present inventors have found that the conventional gas sensor disclosed in Patent Document 1 has the following problem: In other words, the present inventors have found that, during the manufacturing process of the conventional gas sensor (particularly when the barrel pieces are crimped), small metal pieces (burrs, foreign metal particles) may be generated from the barrel, etc., and such metal pieces may cause a short circuit, which may result in malfunction of the gas sensor.

[0006] FIG. 7 illustrates a method for crimping a barrel BR placed on an anvil AV using a crimper CR. Note that in FIG. 7, the lead wire (core wire of the lead wire) is not shown to facilitate understanding of the relationship between the barrel BR and the crimper CR. As illustrated in FIG. 7A, first, the barrel BR before crimping is placed on the anvil AV. The barrel BR before crimping is formed into a U-shape when viewed in a cross section perpendicular to the axial direction of the lead wire, with a bottom plate on which the core wire of the lead wire is placed and a pair of barrel pieces standing on both sides (left and right ends) of the bottom plate. The core wire of the lead wire is then placed so as to abut against the inner circumferential surface of the barrel BR before crimping (the bottom plate of the barrel BR). Next, as illustrated in FIG. 7B, the crimper CR is lowered toward the anvil AV. At this time, the outer surfaces of the barrel pieces abut against the crimping surface of the crimper CR, and each barrel piece slides along the crimping surface of the crimper CR. The crimping surfaces of the crimper CR are formed in a roughly M-shape, curving from both sides toward the center, so that the pair of barrel pieces are gradually guided toward each other. Then, as shown in Fig. 7C, the pair of barrel pieces are deeply bent toward the bottom plate, drawing an arc around each other, and the core wire of the lead wire is firmly crimped between the bottom plate and the pair of barrel pieces. That is, the pair of barrel pieces are compressed by the crimper CR while overlapping and sliding inside each other.

[0007] As described above, for example, when the barrel pieces are pressed by a crimper to be crimped so as to be wound around the core wire, small metal chips may be generated from the barrel (barrel piece) as follows. That is, the outer surfaces of the barrel pieces are rubbed by the crimping surface of the crimper, causing irregularities. When the barrel pieces overlap in this state, small metal chips may be generated from the barrel (barrel piece). Furthermore, when a pair of barrel pieces are compressed while overlapping and sliding inside each other, the barrel pieces (e.g., the outer surfaces of the barrel pieces where irregularities have been generated) may come into contact with the core wire and scratch the surface of the core wire, which may cause small metal chips to be generated from the lead wire (core wire). Therefore, for example, if a gas sensor is mounted so that the barrel is positioned higher than the ceramic housing in the vertical direction, metal chips generated from the barrel or the like may fall onto the ceramic housing and cause a short circuit.

[0008] After further investigation, the present inventors found that the possibility of such a short circuit varies depending on the structure of the gas sensor, particularly on where the barrel is disposed (i.e., where the barrel is housed). Specifically, the present inventors found that the possibility of a short circuit differs between a case where the barrel is housed inside an elastic body that seals the open end of a cylindrical body containing a sensor element, and a case where the barrel is housed inside a spacer that is disposed between the ceramic housing and the elastic body. The present inventors confirmed that a gas sensor in which the barrel is housed inside a spacer is more likely to develop a short circuit due to the metal piece than a gas sensor in which the barrel is housed inside an elastic body. Therefore, the present inventors studied the cause of this difference.

[0009] 8A is a cross-sectional view of an example of a first conventional gas sensor in which a barrel is housed in an elastic body, and FIG. 8B is a cross-sectional view of an example of a second conventional gas sensor in which a barrel is housed in a spacer. The first conventional gas sensor CS1 and the second conventional gas sensor CS2 are common in that they include a sensor element 10C, a ceramic housing 60C, lead wires 40C, metal terminals 30C, and a cylindrical body 20C with an open end and in which the ceramic housing 60C is disposed. The ceramic housing 60C holds the rear end of the sensor element 10C extending in the axial direction, and the metal terminals 30C are attached to the ceramic housing 60C to electrically connect the sensor element 10C and the lead wires 40C. The ceramic housing 60C is housed inside the cylindrical body 20C. The first conventional gas sensor CS1 and the second conventional gas sensor CS2 each include an elastic body 50C disposed to seal the open end of the cylindrical body 20C, and a reduced diameter portion 221C that crimps a portion of the elastic body 50C from the periphery is formed at the rear end of the cylindrical body 20C. In the first conventional gas sensor CS1, two reduced diameter portions 221C, 221C(1) and 221C(2), are formed at the rear end of the cylindrical body 20C, while in the second conventional gas sensor CS2, one reduced diameter portion 221C is formed at the rear end of the cylindrical body 20C. In each of the first conventional gas sensor CS1 and the second conventional gas sensor CS2, the number of reduced diameter portions 221C formed at the rear end of the cylindrical body 20C is not particularly limited.

[0010] However, in the first conventional gas sensor CS1, the barrel 32C of the metal terminal 30C, which crimps and holds the lead wire 40C, is housed inside the elastic body 50C. When assembling (manufacturing) the first conventional gas sensor CS1, the elastic body 50C is crimped by the reduced diameter portion 221C, that is, compressed by the reduced diameter portion 221C. Therefore, in the first conventional gas sensor CS1 in which the barrel 32C is housed inside the elastic body 50C, even if metal fragments are generated from the barrel 32C or the like, the movement of the metal fragments is restricted by the compressed elastic body 50C. Therefore, the possibility of the metal fragments generated from the barrel 32C or the like moving toward the ceramic housing 60C is low, and the possibility of a short circuit caused by the metal fragments is also low.

[0011] In contrast, in the second conventional gas sensor CS2, the barrel 32C is housed inside a spacer 70C that is disposed between the ceramic housing 60C and the elastic body 50C. Unlike the elastic body 50C, the spacer 70C is not crimped (compressed) by the reduced diameter portion 221C. In other words, no external force is applied to the spacer 70C from the reduced diameter portion 221C or the like. Therefore, in the second conventional gas sensor CS2, the movement of metal pieces generated from the barrel 32C or the like is not restricted by the spacer 70C, and they may move toward the ceramic housing, for example, causing a short circuit.

[0012] As described above, in the second conventional gas sensor CS2 in which the barrel 32C is housed inside the spacer 70C, metal particles generated from the barrel 32C and the like can move more easily than in the first conventional gas sensor CS1 in which the barrel 32C is housed inside the elastic body 50C. Therefore, the present inventors have found that the second conventional gas sensor CS2 is more susceptible to short circuits caused by the metal particles than the first conventional gas sensor CS1.

[0013] In one aspect, the present invention has been made in consideration of the above circumstances, and its object is to provide a gas sensor that prevents the occurrence of short circuits caused by metal pieces emerging from a barrel or the like, even when the barrel that crimps and holds the lead wires is housed inside a spacer. [Means for solving the problem]

[0014] In order to solve the above-mentioned problems, the present invention employs the following configuration.

[0015] A gas sensor according to a first aspect includes a sensor element extending in an axial direction, having a detection portion at a front end side, and having a plurality of connector electrodes disposed on at least one surface at a rear end side; a plurality of metal terminals, each extending in the axial direction and each having an element contact portion at a front end side electrically connected to a respective one of the plurality of connector electrodes; a ceramic housing accommodating the plurality of connector electrodes and the element contact portions of the plurality of metal terminals; a cylindrical body having an open end and having the ceramic housing disposed therein; a plurality of lead wires each connected to a respective one of the plurality of metal terminals and extending outward from the open end; an elastic body disposed to seal the open end; and an elastic member housed inside the cylindrical body and disposed between the ceramic housing and the elastic body in the axial direction, the ceramic housing accommodating the plurality of connector electrodes and the element contact portions of the plurality of metal terminals. and a spacer that contacts the housing, and each of the multiple metal terminals has a barrel at its rear end that crimps and holds each of the multiple lead wires, and the barrel of each of the multiple metal terminals is housed inside the spacer, and the barrel has a bottom plate on which the core wires of each of the multiple lead wires are placed, and a pair of barrel pieces that protrude from both sides of the bottom plate and are crimped to wrap around the core wires and be crimped to the core wires, and on the surface of the barrel opposite to the surface on which the core wires are placed, at least one of the pair of barrel pieces has multiple grooves that are spaced apart from each other in the axial direction and extend in a direction intersecting the axial direction, and the spacing between adjacent grooves among the multiple grooves is narrower than the spacing between adjacent connector electrodes among the multiple connector electrodes in a direction perpendicular to the axial direction.

[0016] In this configuration, the barrel that crimps and holds the lead wire is housed inside the spacer. At least one of the pair of barrel pieces has a surface of the barrel opposite to the surface on which the core wire is placed, and the grooves are formed in the axial direction at the intervals and extend in a direction intersecting the axial direction. That is, the grooves are formed in the outer surface of at least one of the pair of barrel pieces at the intervals in the axial direction. The intervals between adjacent grooves are narrower than the intervals between adjacent connector electrodes among the plurality of connector electrodes in a direction perpendicular to the axial direction.

[0017] The present inventors discovered that narrowing the gap between adjacent grooves can reduce the length (length in the longitudinal direction) of metal particles (burrs, metal foreign matter) generated from the barrel (the barrel piece) or the like. Therefore, in the gas sensor, the gap between adjacent grooves is narrower (smaller) than the gap between adjacent connector electrodes. By narrowing the gap between adjacent grooves than the gap between adjacent connector electrodes, the gas sensor can reduce the length of metal particles generated from the barrel or the like to the gap between adjacent connector electrodes. Therefore, even when the barrel, which crimps and holds the lead wire, is housed inside the spacer, the gas sensor can prevent short circuits caused by metal particles generated from the barrel or the like. In particular, the inventors of the present invention confirmed through the test (cleanliness analysis test) described below that by "making the spacing between adjacent groove portions narrower than the spacing between the adjacent connector electrodes," it is possible to reduce the number of metal pieces that may affect the occurrence of short circuits, and thereby effectively prevent the occurrence of short circuits.

[0018] A gas sensor according to a second aspect may be the gas sensor according to the first aspect, wherein a width of an opening of each of the plurality of grooves in the axial direction is narrower than a distance between the adjacent connector electrodes in a direction perpendicular to the axial direction.

[0019] In this configuration, in the gas sensor, the width of the opening of the groove in the axial direction (opening width) is narrower than the distance between the adjacent connector electrodes. The inventors confirmed through a test described below that by "making the opening width of the groove narrower than the distance between the adjacent connector electrodes," the number of metal pieces that may affect the occurrence of a short circuit can be reduced, and the occurrence of a short circuit can be effectively prevented. Therefore, even when the barrel that crimps and holds the lead wire is housed inside the spacer, the gas sensor can prevent the occurrence of a short circuit due to metal pieces generated from the barrel, etc.

[0020] A gas sensor according to a third aspect may be the gas sensor according to the first or second aspect, wherein a width of an opening of each of the plurality of grooves in the axial direction is equal to or greater than the interval between the adjacent grooves.

[0021] In this configuration, in the gas sensor, the opening width of the groove is equal to or greater than the distance between adjacent grooves. As described above, the distance between adjacent grooves is narrower than the distance between adjacent connector electrodes, and, for example, the opening width of the groove may be narrower than the distance between adjacent connector electrodes. In the gas sensor, the opening width of the groove may be equal to or greater than the distance between adjacent grooves. With this configuration, the gas sensor can make the length of metal pieces generated from the barrel or the like smaller (shorter) than the distance between the adjacent connector electrodes. Therefore, even when the barrel, which crimps and holds the lead wire, is housed inside the spacer, the gas sensor can prevent short circuits caused by metal pieces generated from the barrel or the like.

[0022] A gas sensor according to a fourth aspect is the gas sensor according to any one of the first to third aspects, wherein a depth of each of the plurality of grooves in a thickness direction of the barrel piece may be 90% or less of the thickness of the barrel piece.

[0023] In this configuration, in the gas sensor, the depth of the groove is 90% or less of the plate thickness of the barrel piece. The inventors confirmed through a test described below that by "setting the depth of the groove to 90% or less of the plate thickness of the barrel piece," the number of metal pieces that may affect the occurrence of a short circuit can be reduced, and the occurrence of a short circuit can be effectively prevented. Therefore, even when the barrel that crimps and holds the lead wire is housed inside the spacer, the gas sensor can prevent the occurrence of a short circuit caused by metal pieces generated from the barrel, etc.

[0024] A gas sensor according to a fifth aspect is the gas sensor according to any one of the first to fourth aspects, wherein a length of each of the plurality of grooves in a direction intersecting the axial direction may be equal to or greater than a rolling height which is a length from a position where the pair of barrel pieces contact each other to each end of the pair of barrel pieces.

[0025] In this configuration, in the gas sensor, the length of the groove is equal to or greater than the winding height of the barrel piece. The inventors confirmed through a test described below that by "setting the length of the groove equal to or greater than the winding height of the barrel piece," the number of metal pieces that may affect the occurrence of a short circuit can be reduced, and the occurrence of a short circuit can be effectively prevented. Therefore, even when the barrel, which crimps and holds the lead wire, is housed inside the spacer, the gas sensor can prevent the occurrence of a short circuit due to metal pieces generated from the barrel, etc. [Effects of the Invention]

[0026] According to the present invention, a gas sensor can be provided that prevents short circuits caused by metal pieces generated from a barrel or the like, even when the barrel that crimps and holds the lead wires is housed inside a spacer. [Brief explanation of the drawings]

[0027] [Figure 1]FIG. 1 is a cross-sectional view schematically illustrating an example of a main configuration of a gas sensor according to an embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing an example of the configuration of a main part of the gas sensor of FIG. [Figure 3] FIG. 3 is a diagram schematically showing the structure of the rear end side of the sensor element of the gas sensor of FIG. [Figure 4] FIG. 4 is a diagram illustrating an example of an outline of the barrel of the gas sensor of FIG. 1 in a state before being crimped. [Figure 5] FIG. 5 is a cross-sectional view showing an example of the configuration of the grooves and the like of the barrel piece of the barrel shown in FIG. [Figure 6] FIG. 6 is a diagram illustrating an example of the barrel of FIG. 4 in outline before and after crimping. [Figure 7] FIG. 7 is a diagram illustrating a method of crimping a barrel placed on an anvil using a crimper. [Figure 8] FIG. 8 is a cross-sectional view schematically illustrating an example of a main part of a first conventional gas sensor in which a barrel is housed inside an elastic body, and a second conventional gas sensor in which a barrel is housed inside a spacer. DETAILED DESCRIPTION OF THE INVENTION

[0028] An embodiment according to one aspect of the present invention (hereinafter also referred to as "the present embodiment") will be described below with reference to the drawings. However, the present embodiment described below is merely an example of the present invention in all respects. It goes without saying that various improvements and modifications can be made without departing from the scope of the present invention. In other words, when implementing the present invention, specific configurations according to the embodiment may be appropriately adopted.

[0029] The present inventors have found that the second conventional gas sensor CS2, in which the barrel 32C is housed inside a spacer 70C as shown in Fig. 8(B), is more likely to short-circuit than the first conventional gas sensor CS1, in which the barrel 32C is housed inside an elastic body 50C as shown in Fig. 8(A). The present inventors have further found that the reason for this difference is that the spacer 70C, which houses the barrel 32C inside, is not subjected to external forces from the reduced diameter portion 221C, etc., and therefore cannot restrict the movement of metal pieces generated from the barrel 32C, etc.

[0030] Therefore, in the gas sensor (gas sensor 1) according to this embodiment, a plurality of grooves 3221 extending in a direction intersecting the axial direction of the gas sensor 1 are formed on the outer surface of the barrel piece 322 of the barrel 32 disposed inside the spacer 70. The interval LB between adjacent grooves 3221 is narrower than the interval LA between adjacent connector electrodes 12 on the surface of the sensor element 10. By narrowing the interval LB between adjacent grooves 3221, the length (length in the longitudinal direction) of metal particles (burrs, metal foreign matter) generated from the barrel 32 (barrel piece 322) or the like can be reduced. In particular, by narrowing (making smaller) the interval LB between adjacent grooves 3221 than the interval LA between adjacent connector electrodes 12, the length of metal particles generated from the barrel 32 or the like can be made shorter than the interval LA. Therefore, even when the barrel 32 that crimps and holds the lead wire 40 is housed inside the spacer 70, the gas sensor 1 can prevent short circuits caused by metal pieces generated from the barrel 32, etc. The gas sensor 1 will now be described in detail with reference to FIGS. 1 and 2.

[0031] [Configuration example] <Overview of gas sensors> 1 is a cross-sectional view showing an example of the main configuration of a gas sensor 1 according to this embodiment. That is, FIG. 1 shows a cross-sectional view of the gas sensor 1, which is parallel to and in contact with the longitudinal axis (axis, a line extending in the left-right direction of the drawing). The gas sensor 1 is an example of the "gas sensor" of the present invention, and is used to measure oxygen and NO in a gas to be measured, such as an automobile exhaust gas. x 1, the gas sensor 1 has an axis and is configured to extend along the longitudinal direction (axial direction), with a front end and a rear end as the respective longitudinal ends. One longitudinal end is the front end, and the other longitudinal end is the rear end. In the example of FIG. 1, the gas sensor 1 is disposed so that the front end of the gas sensor 1 faces leftward and the rear end of the gas sensor 1 faces rightward. That is, the left-right direction in FIG. 1 corresponds to the longitudinal direction (axial direction). In this embodiment, the gas sensor 1 includes a sensor element 10, a cylindrical body 20 (a metal shell 21, an outer cylinder 22, and a fixing bolt 23), a metal terminal 30, lead wires 40, an elastic body 50, a ceramic housing 60, a spacer 70, and a protective cover 80. In the gas sensor 1, the sensor element 10 is surrounded by a cylindrical body 20 and a protective cover 80, and the cylindrical body 20 and the protective cover 80 together form a housing member (casing) that houses the sensor element 10. The sensor element 10 is disposed coaxially with the cylindrical body 20 and the protective cover 80, and the extending direction of the central axis of the sensor element 10 coincides with the axial direction of the gas sensor 1.

[0032] FIG. 2 is an enlarged cross-sectional view schematically illustrating a main portion of the gas sensor 1, specifically, an enlarged cross-sectional view of a main portion of the rear end side of the gas sensor 1. In FIG. 2, the vertical direction of the paper corresponds to the axial direction (longitudinal direction) of the gas sensor 1 (sensor element 10), with the lower side of the paper corresponding to the front end side and the upper side corresponding to the rear end side. As illustrated in FIG. 2, a ceramic housing 60, a spacer 70, and an elastic body 50 are arranged in this order from the front end side to the rear end side at the rear end side of the gas sensor 1. The rear end face of the ceramic housing 60 is in contact with the front end face of the spacer 70, and the rear end face of the spacer 70 is in contact with the front end face of the elastic body 50. The sensor element 10, the cylindrical body 20, the metal terminal 30, the lead wires 40, the elastic body 50, the ceramic housing 60, the spacer 70, and the protective cover 80 will be described in detail below.

[0033] (sensor element) The sensor element 10 is an example of the "sensor element" of the present invention and is configured to extend along an axial direction (the left-right direction in FIG. 1, the up-down direction in FIG. 2). The sensor element 10 illustrated in FIG. 1 is a thin, flat (long, plate-like) element extending along the axial direction. The sensor element 10 has a detection unit 11 at its front end and, as illustrated in FIG. 2, has multiple connector electrodes 12 at its rear end. The sensor element 10 illustrated in FIG. 2 has two connector electrodes 12, connector electrodes 12(1) and 12(5). However, the number of connector electrodes 12 provided on the sensor element 10 may be multiple; two is not essential. As will be described in detail later with reference to FIG. 3, multiple connector electrodes 12 are arranged on at least one surface (e.g., at least one of the top and bottom surfaces) at the rear end of the sensor element 10. Each connector electrode 12 is an electrode that electrically connects the sensor element 10 to the outside.

[0034] In this embodiment, when it is not necessary to distinguish between the multiple connector electrodes 12, they may be simply referred to as "connector electrodes 12." When it is necessary to distinguish between the multiple connector electrodes 12, "(1)," "(2)," "(3)," ..., "(n)" is added after the component number "12" to distinguish between them. "n" is an integer equal to or greater than "2." The same expression is used for the multiple metal terminals 30, the multiple barrels 32, the multiple lead wires 40, the multiple grooves 3221, etc., which will be described later.

[0035] 1 again, in the illustrated example, the tip side of the sensor element 10 is coated with an outer porous layer, and the outer porous layer serves as a protective layer that prevents, for example, moisture in the gas to be measured from adhering and causing cracks in the body of the sensor element 10. However, it is not essential for the sensor element 10 to be coated with an outer porous layer at the tip side, and the tip side of the sensor element 10 does not have to be coated with an outer porous layer.

[0036] In the gas sensor 1, the sensor element 10 is arranged so that its tip side faces the tip of the gas sensor 1. For example, in one embodiment of the sensor element 10, the measurement gas introduced into the sensor element 10 is reduced or decomposed inside the sensor element 10 to generate oxygen ions. In the gas sensor 1 equipped with such a sensor element 10, the concentration of a specific gas, which is a detection target gas in the measurement gas, can be determined based on the fact that the amount of oxygen ions flowing inside the sensor element 10 is proportional to the concentration of the specific gas.

[0037] In the example shown in FIG. 1, the front end side of the sensor element 10 is surrounded by a protective cover 80, and the rear end side protrudes into the outer tube 22, and the approximate center portion between the two is fixed inside the metal shell 21 by a ring part 90 in a manner that hermetically seals the space between both ends.

[0038] (Enclosure parts) 1, the encasing part 90 includes a first ceramic supporter 91, a powder compact 92, and a second ceramic supporter 93. The first ceramic supporter 91 and the second ceramic supporter 93 are ceramic insulators. More specifically, a through hole (not shown) having a shape corresponding to the cross-sectional shape of the sensor element 10 is provided at the axial center position of the first ceramic supporter 91 and the second ceramic supporter 93, and the sensor element 10 is inserted into the through hole, whereby the first ceramic supporter 91 and the second ceramic supporter 93 are encased around the sensor element 10. The first ceramic supporter 91 is engaged with the tapered surface of the metallic shell 21 on the left side of the drawing.

[0039] On the other hand, the powder compact 92 is formed by molding ceramic powder such as talc. As with the first ceramic supporter 91 and the second ceramic supporter 93, the powder compact 92 is formed by inserting the sensor element 10 into the through-hole, so that two molded bodies (not shown) that were previously mounted around the sensor element 10 are disposed inside the metallic shell 21 in a state of being mounted around the sensor element 10, and then further compressed to form a single body. More specifically, the ceramic particles that make up the powder compact 92 are surrounded by the first ceramic supporter 91, the second ceramic supporter 93 and the metallic shell 21, and are densely packed in the space inside the metallic shell 21 through which the sensor element 10 passes. By compressing and filling the powder compact 92, an airtight seal is achieved between the front end side and the rear end side of the sensor element 10.

[0040] 1 shows an example in which the surrounding part 90 is composed of a first ceramic supporter 91, a powder compact 92, and a second ceramic supporter 93. However, in the gas sensor 1, it is not essential that the surrounding part 90 is composed of the first ceramic supporter 91, the powder compact 92, and the second ceramic supporter 93. The gas sensor 1 shown in FIG. 1 includes the surrounding part 90 that fixes the sensor element 10 inside the metallic shell 21 and hermetically seals the gap between the front and rear ends of the sensor element 10.

[0041] (Cylindrical body) The cylindrical body 20 is an example of the "cylindrical body" of the present invention. The cylindrical body 20 is, for example, a tubular (e.g., cylindrical) member made of metal and has an open end. Inside the cylindrical body 20, the sensor element 10, a ceramic housing 60 (metal terminal 30), and a spacer 70 are arranged. In the example shown in FIG. 1, the cylindrical body 20 includes a cylindrical metallic shell 21, a cylindrical outer cylinder 22, and a fixing bolt 23, each of which is made of metal.

[0042] The metal shell 21 is a tubular (for example, cylindrical) member made of metal. The sensor element 10 and a fixing ring part 90 ring-mounted on the sensor element 10 are housed inside the metal shell 21. In other words, the metal shell 21 is further ring-mounted around the ring part 90 which is ring-mounted around the sensor element 10. The metal shell 21 illustrated in FIG. 1 is configured to surround the sensor element 10 in the axial direction (longitudinal direction), and in particular, is configured to surround the sensor element 10 except for a portion on each of the front and rear ends.

[0043] The outer cylinder 22 is a tubular (for example, cylindrical) member made of metal, and the outer cylinder 22 illustrated in FIG. 1 covers the rear end of the sensor element 10, the ceramic housing 60 (metal terminal 30), and the spacer 70.

[0044] An end (open end) on the front side of the outer cylinder 22 is welded to the outer peripheral end on the rear side of the metallic shell 21. An elastic body 50 is disposed at the open end on the rear side of the outer cylinder 22 so as to seal the open end. A reduced diameter portion 221 is formed at the rear side of the outer cylinder 22, crimping a portion of the elastic body 50 from the periphery to seal the open end on the rear side. The reduced diameter portion 221 crimps the outer cylinder 22 from the outside in a reduced diameter manner over the entire circumferential direction, thereby generating a reaction force in the elastic body 50 that acts radially outward, thereby sealing the outer cylinder 22.

[0045] Furthermore, a plurality of lead wires 40 are drawn out from the open end on the rear end side of the outer tube 22 sealed by the elastic body 50 through through holes (not shown) formed inside the elastic body 50. Outside air (atmosphere) is introduced into the internal space of the outer tube 22 through the gap between the coating of the lead wires 40 and the metal wire (conductor) (in other words, inside the coating), and the internal space of the outer tube 22 becomes a reference gas (atmosphere) atmosphere. The rear end of the sensor element 10 is disposed within the internal space of the outer tube 22 filled with the reference gas.

[0046] The fixing bolt 23 is an annular member used to fix the gas sensor 1 to the measurement position (mounting position), and is fixed coaxially with the metallic shell 21. The fixing bolt 23 has a threaded bolt portion and a holding portion that is held when the bolt portion is screwed. The bolt portion of the fixing bolt 23 is screwed into a nut provided at the mounting position of the gas sensor 1. For example, by screwing the bolt portion of the fixing bolt 23 into a nut (nut portion) provided in an exhaust pipe of an automobile, the gas sensor 1 is fixed to the exhaust pipe in a manner that the protective cover 80 side is exposed inside the exhaust pipe.

[0047] 1 includes a metallic shell 21, an outer cylinder 22, and a fixing bolt 23, and is configured as a cylindrical (e.g., cylindrical) member as a whole, particularly as a cylindrical member extending in the axial direction. That is, the cylindrical body 20 illustrated in FIG. 1 is a cylindrical member extending in the axial direction, including a cylindrical metallic shell 21, a cylindrical outer cylinder 22 welded to the outer peripheral end portion on the rear end side of the metallic shell 21, and a fixing bolt 23 disposed on the outer periphery on the front end side of the metallic shell 21. For example, the cylindrical body 20 and the gas sensor 1 (sensor element 10) are coaxial, and the cylindrical body 20 has a front end and a rear end as respective ends in the axial direction (longitudinal direction), and is disposed so that the front end of the cylindrical body 20 faces the front end of the gas sensor 1. The cylindrical body 20 accommodates the sensor element 10, a fixing ring part 90 ring-mounted on the sensor element 10, a ceramic housing 60 (metal terminal 30), and a spacer 70, and the rear open end is sealed by an elastic body 50. A reduced diameter section 221 for fixing the elastic body 50 that seals the open end of the cylindrical body 20 is formed on the rear end side of the cylindrical body 20 (outer cylinder 22), and the reduced diameter section 221 crimps a part of the elastic body 50 from the periphery.

[0048] In the gas sensor 1, it is not essential that the cylindrical body 20 includes the metallic shell 21, the outer casing 22, and the fixing bolt 23. The cylindrical body 20 does not have to include the fixing bolt 23, and the metallic shell 21 and the outer casing 22 may be an integrally formed member. In the gas sensor 1, the cylindrical body 20 may be a cylindrical member in which the sensor element 10, the ceramic housing 60 (metal terminal 30), and the spacer 70 are disposed, and which has an open end.

[0049] (metal terminal) The metal terminal 30 is an example of the "metal terminal" of the present invention. The metal terminal 30 is a metal member (contact member) extending in the axial direction. In the gas sensor 1, the sensor element 10 (particularly, its connector electrode 12) and the lead wire 40 are electrically connected via the metal terminal 30. As illustrated in FIG. 2, the gas sensor 1 includes multiple metal terminals 30, and in the illustrated example, includes two metal terminals 30, metal terminals 30(1) and 30(2). The number of metal terminals 30 included in the gas sensor 1 may be multiple; two is not essential. For example, the gas sensor 1 may include the same number of metal terminals 30 as the number of connector electrodes 12 included in the sensor element 10. Each of the multiple metal terminals 30 extends in the axial direction and has an element contact portion 31 at its front end and a barrel 32 at its rear end. Each element contact portion 31 is electrically connected to the connector electrode 12 of the corresponding sensor element 10. Each barrel 32 crimps and holds one of the multiple lead wires 40. In the example shown in Fig. 2, the barrel 32(1) of the metal terminal 30(1) crimps and holds the lead wire 40(1), and the barrel 32(2) of the metal terminal 30(2) crimps and holds the lead wire 40(2).

[0050] (ceramic housing) The ceramic housing 60 is an example of the "ceramic housing" of the present invention. The ceramic housing 60 is a ceramic member that houses the rear end side of the sensor element 10 and the front end sides of each of the multiple metal terminals 30. Specifically, the ceramic housing 60 houses the multiple connector electrodes 12 provided on the rear end side of the sensor element 10 and the element contact portions 31 of each of the multiple metal terminals 30. In the gas sensor 1, each of the multiple connector electrodes 12 provided on the rear end side of the sensor element 10 and each of the element contact portions 31 of the multiple metal terminals 30 are electrically connected within the ceramic housing 60.

[0051] For example, the rear end side of the sensor element 10, on which a plurality of connector electrodes 12 are provided on the surface, is inserted into a ceramic housing 60 that accommodates the tip sides (element contact portions 31) of the plurality of metal terminals 30. In this inserted state, the plurality of connector electrodes 12 provided on the rear end side of the sensor element 10 come into contact with the tip sides (element contact portions 31) of the plurality of metal terminals 30. Note that the tip sides (element contact portions 31) of the plurality of metal terminals 30 may be sandwiched and fixed between the rear end side of the sensor element 10, on which the plurality of connector electrodes 12 are provided, and the ceramic housing 60, thereby electrically connecting the plurality of connector electrodes 12 to the plurality of metal terminals 30.

[0052] (lead wire) The lead wire 40 is an example of the "lead wire" of the present invention. The gas sensor 1 includes a plurality of lead wires 40. For example, in the example shown in FIG. 2, the gas sensor 1 includes two lead wires 40, 40(1) and 40(2). The number of lead wires 40 included in the gas sensor 1 may be more than one, and the number does not necessarily have to be two. For example, the gas sensor 1 includes the same number of lead wires 40 as the number of metal terminals 30.

[0053] Each lead wire 40 is electrically connected to each of the connector electrodes 12 of the sensor element 10 via each of the metal terminals 30, and extends outward from the open end of the cylindrical body 20. That is, as illustrated in FIG. 2 , the leading end of each lead wire 40 is electrically connected to the rear end of each of the metal terminals 30 (specifically, the barrel 32 of each metal terminal 30), i.e., connected to each metal terminal 30. Specifically, each lead wire 40 is crimped and held in the barrel 32 of each of the metal terminals 30. In the example illustrated in FIG. 2 , the lead wire 40(1) is crimped and held in the barrel 32(1) of the metal terminal 30(1), and the lead wire 40(2) is crimped and held in the barrel 32(2) of the metal terminal 30(2). The rear end of each lead wire 40 extends outward from the open end of the cylindrical body 20. As described above, the gap between each lead wire 40 and the cylindrical body 20 (outer tube 22) is sealed by the elastic body 50. That is, each lead wire 40 extends outward from the open end on the rear end side of the cylindrical body 20 sealed by the elastic body 50.

[0054] For example, each lead wire 40 is inserted through a through-hole (not shown) continuously provided in the elastic body 50 and the spacer 70. The tip end of each lead wire 40 is crimped and fixed to the rear end (barrel 32) of each metal terminal 30, and the rear end of each lead wire 40 is connected to an external device (controller), power supply, etc. This electrically connects the sensor element 10 (particularly, each of the multiple connector electrodes 12 of the sensor element 10) to the external device, power supply, etc. through each metal terminal 30 and each lead wire 40. Note that while FIG. 1 shows an example in which there are two metal terminals 30 and two lead wires 40, this is merely for the sake of simplicity. In reality, the gas sensor 1 includes the number of metal terminals 30 and the number of lead wires 40 required for the above-mentioned electrical connection.

[0055] (elastic body) The elastic body 50 is an example of the "elastic body" of the present invention. The elastic body 50 is an elastic member, and is made of, for example, rubber. The elastic body 50 is arranged so as to seal the open end of the cylindrical body 20 (the open end on the rear end side in the example shown in FIG. 1), and the lead wire 40 is inserted into the elastic body 50. Specifically, a through hole extending in the axial direction is formed inside the elastic body 50, and for example, a plurality of through holes extending in the axial direction are formed inside the elastic body 50. The lead wire 40 is housed (inserted) in the through hole formed inside the elastic body 50, and for example, each of the plurality of lead wires 40 is housed (inserted) in each of the plurality of through holes formed inside the elastic body 50.

[0056] The material of the elastic body 50 is, for example, fluororubber. Fluororubber has excellent properties in various aspects, such as durability and strength, and is particularly excellent in heat resistance and oil resistance. Therefore, by using the elastic body 50 made of fluororubber, the gas sensor 1 can ensure the sealing properties of the elastic body 50 even in high-temperature environments, thereby maintaining and improving the gas concentration detection accuracy. However, it is not essential for the gas sensor 1 that the material of the elastic body 50 be fluororubber, and the gas sensor 1 may use any elastic material as the material of the elastic body 50 as appropriate.

[0057] (spacer) The spacer 70 is an example of the "spacer" of the present invention. The spacer 70 is housed inside the cylindrical body 20 and is disposed between the ceramic housing 60 and the elastic body 50 in the axial direction of the gas sensor 1 (sensor element 10). Specifically, the spacer 70 is disposed rearward of the ceramic housing 60 and forward of the elastic body 50. The spacer 70 also contacts the ceramic housing 60, and in particular, its forward end surface contacts the ceramic housing 60 (particularly, the rear end surface of the ceramic housing 60). In the illustrated example, the spacer 70 also contacts the elastic body 50 (particularly, the forward end surface of the elastic body 50) at its rear end surface.

[0058] Each lead wire 40 is inserted into the spacer 70, and the barrel 32 of each metal terminal 30 is housed inside the spacer 70. For example, in the example shown in Fig. 2, a plurality of lead wires 40 and a plurality of metal terminals 30 (particularly, the barrels 32 of the plurality of metal terminals 30 electrically connected to each of the plurality of lead wires 40) are housed inside the spacer 70. Each lead wire 40 is crimped and held by the barrel 32 of each metal terminal 30 inside the spacer 70, and is electrically connected to each metal terminal 30.

[0059] The spacer 70 is made of, for example, a heat-resistant material. By using a heat-resistant material, the spacer 70, which is located axially further forward than the elastic body 50, can be prevented from being melted and damaged by heat generated from a heat source located at the forward end of the gas sensor 1. For example, by interposing the spacer 70 between the elastic body 50 and the ceramic housing 60, excessive temperature rise of the elastic body 50 can be prevented during use of the gas sensor 1. In other words, from the perspective of suppressing heat transfer to the elastic body 50, a low thermal conductivity of the spacer 70 is desirable. However, while the spacer 70 suppresses the temperature rise of the elastic body 50, the spacer 70 itself must have sufficient heat resistance because it becomes hot. Therefore, by using a heat-resistant material to suppress heat transfer from the heat source to the elastic body 50, it is possible to prevent the spacer 70 itself from being melted and damaged by heat generated from the heat source.

[0060] Specifically, in the gas sensor 1, the spacer 70 is made of ceramic. Ceramics have excellent heat resistance and generally have a higher melting point than resin. In the gas sensor 1, the spacer 70 is disposed axially closer to the tip of the elastic body 50. By making the spacer 70 out of ceramic, which has excellent heat resistance, the gas sensor 1 achieves the following effect. That is, the gas sensor 1 achieves the effect of preventing the spacer 70 from being melted and damaged by heat generated from a heat source located at the tip of the gas sensor 1. However, it is not essential for the gas sensor 1 that the spacer 70 be made of ceramic. In the gas sensor 1, the spacer 70 may be made of any suitable heat-resistant material.

[0061] (protective cover) The protective cover 80 is a substantially cylindrical exterior member that protects a predetermined area on the tip side of the sensor element 10, which is the portion that comes into direct contact with the gas to be measured during use. The protective cover 80 illustrated in FIG. 1 is configured to surround at least a portion of the tip side of the cylindrical body 20 (metal shell 21) along the axial direction (longitudinal direction) and extend beyond the tip of the sensor element 10. For example, the protective cover 80 is configured to surround the sensor element 10 and a portion of the tip side of the cylindrical body 20 around the axis. The protective cover 80 has a front end and a rear end as its respective ends in the axial direction, and the front end of the protective cover 80 is located closer to the tip of the gas sensor 1 than the tip of the sensor element 10.

[0062] The protective cover 80 is provided with a plurality of through-holes (not shown) through which gas can pass. The measurement gas that flows into the protective cover 80 through these through-holes becomes a direct target for detection by the sensor element 10. The type, number, position, shape, etc. of the through-holes provided in the protective cover 80 may be determined appropriately in consideration of the manner in which the measurement gas flows into the protective cover 80.

[0063] In the example shown in FIG. 1 , the protective cover 80 includes a cylindrical inner cover 81 with a bottom that covers the tip of the sensor element 10, and a cylindrical outer cover 82 with a bottom that covers the inner cover 81. The inner cover 81 includes a first member 81B and a second member 81A, and is configured to cover at least a portion of the periphery of the tip side of the sensor element 10 and the cylindrical body 20 (metal shell 21). The first member 81B extends axially from the outer wall of the tip portion of the cylindrical body 20, reduces in diameter in a direction perpendicular to the axial direction around the tip of the cylindrical body 20, and then continues to extend axially. The second member 81A is configured to cover a portion of the periphery of the tip side of the first member 81B. The outer cover 82 is configured to cover the periphery of the inner cover 81.

[0064] A sensor element chamber is formed as a space surrounded by the inner cover 81, and the tip of the sensor element 10 is disposed within this sensor element chamber. Openings are appropriately provided in the first member 81B, the second member 81A of the inner cover 81, and the outer cover 82, thereby connecting the sensor element chamber to the space outside the protective cover 80. However, the configuration and shape of the protective cover 80 are not limited to this example. The configuration and shape of the protective cover 80 may be determined appropriately depending on the embodiment.

[0065] The protective cover 80 may be made of a metal material such as stainless steel (e.g., SUS). The protective cover 80 may be manufactured by appropriately shaping the metal material. Note that the protective cover 80 may be omitted from the configuration of the gas sensor 1.

[0066] <Details of the rear end of the sensor element> FIG. 3 is a diagram schematically illustrating the structure of the rear end side of the sensor element 10. As illustrated in FIG. 3, a plurality of connector electrodes 12 are arranged on at least one surface on the rear end side of the sensor element 10. For example, a plurality of connector electrodes 12 are arranged on at least one of the upper and lower surfaces of the sensor element 10, which is configured in the shape of an elongated flat plate (long plate) extending in the axial direction. In the illustrated example, four connector electrodes 12, namely, connector electrodes 12(1), 12(2), 12(3), and 12(4), are arranged on the upper surface (or lower surface) on the rear end side of the sensor element 10. However, the number of connector electrodes 12 arranged on at least one surface on the rear end side of the sensor element 10 may be plural, and four is not essential. Alternatively, a plurality of connector electrodes 12 may be arranged on each of multiple surfaces on the rear end side of the sensor element 10. For example, connector electrodes 12(1), 12(2), 12(3), and 12(4) may be arranged on the upper surface of the rear end of sensor element 10, and connector electrodes 12(5), 12(6), 12(7), and 12(8), not shown, may be arranged on the lower surface of the rear end of sensor element 10.

[0067] The multiple connector electrodes 12 are arranged on at least one surface of the rear end of the sensor element 10 at intervals LA between them in a direction perpendicular to the axial direction. In the illustrated example, connector electrodes 12(1) and 12(2) are arranged on the surface of the rear end of the sensor element 10 at intervals LA(1-2) between them in a direction perpendicular to the axial direction. Connector electrodes 12(2) and 12(3) are also arranged at intervals LA(2-3) between them in a direction perpendicular to the axial direction. Similarly, connector electrodes 12(3) and 12(4) are also arranged at intervals LA(3-4) between them in a direction perpendicular to the axial direction.

[0068] For three or more connector electrodes 12, the multiple "intervals LA between adjacent connector electrodes 12" may be the same or different. Explaining this based on the example shown in Fig. 3, the interval LA(1-2), the interval LA(2-3), and the interval LA(3-4) may be the same or different.

[0069] As will be described in detail later, a plurality of grooves 3221 extending in a direction intersecting the axial direction (e.g., a direction perpendicular to the axial direction) are formed on the outer surface of at least one of the pair of barrel pieces 322(L), 322(R) of the barrel 32, with the grooves 3221 spaced apart from each other in the axial direction by a distance LB. For example, a plurality of grooves 3221 extending in a direction intersecting the axial direction (e.g., a direction perpendicular to the axial direction) are formed on the outer surface of each of the barrel pieces 322(L), 322(R), with the grooves 3221 spaced apart from each other in the axial direction by a distance LB. The distance LB between adjacent grooves 3221 is narrower than the distance LA between adjacent connector electrodes 12. When the plurality of "distances LA between adjacent connector electrodes 12" are different from each other, the distance LB between adjacent grooves 3221 may be narrower than the narrowest (smallest) "distance LA between adjacent connector electrodes 12." For example, if the intervals LA(1-2), LA(2-3), and LA(3-4) are not the same, and the interval LA(1-2) is the smallest (narrowest), the above-mentioned interval LB may be narrower than the interval LA(1-2).

[0070] <Barrel details> In the following, an example will be described in which "a plurality of grooves 3221 are formed on the outer surface of each of the pair of barrel pieces 322(L), 322(R) of the barrel 32." However, in the gas sensor 1, it is sufficient that the plurality of grooves 3221 are formed on the outer surface of at least one of the barrel pieces 322(L), 322(R). It is not essential for the gas sensor 1 that the plurality of grooves 3221 are formed on the outer surface of each of the barrel pieces 322(L), 322(R).

[0071] FIG. 4 is a diagram illustrating an outline of the barrel 32 before crimping. Specifically, FIG. 4A shows an image of the barrel 32 before crimping (before crimping), in which a pair of barrel pieces 322(L) and 322(R) stand up from both sides (both left and right ends) of the bottom plate 321, as viewed in a cross section perpendicular to the axial direction (axial direction). FIG. 4B shows an image of the outer surface of the barrel 32 before the pair of barrel pieces 322(L) and 322(R) are erected on both sides of the bottom plate 321. The outer surface of the barrel 32 refers to the surface opposite to the surface (inner surface, inner circumferential surface) on which the core wire of the lead wire 40 is placed. The barrel 32 is an example of the "barrel" of the present invention.

[0072] As illustrated in FIG. 4A, the barrel 32 includes a bottom plate 321 on which the core wires of the lead wires 40 are placed, and a pair of barrel pieces 322(L) and 322(R) protruding from both sides of the bottom plate 321. "LE" in FIG. 4A indicates the thickness of each of the pair of barrel pieces 322(L) and 322(R). As illustrated, the barrel 32 before crimping is formed into a U-shape when viewed in a cross section perpendicular to the axial direction. The pair of barrel pieces 322(L) and 322(R) are crimped to wrap around the core wires of the lead wires 40, respectively. In this embodiment, when it is not necessary to distinguish between the pair of barrel pieces 322(L) and 322(R), they may be simply referred to as "barrel pieces 322." Furthermore, when distinguishing between barrel pieces 322(L) and barrel pieces 322(R), "(L)" and "(R)" are added after the component number "322" to distinguish between them. The grooves 3221 formed on the outer surface of each barrel piece 322 may also be expressed in the same manner as the barrel pieces 322. The bottom plate 321 is an example of the "bottom plate" of the present invention, and the barrel piece 322 is an example of the "barrel piece" of the present invention.

[0073] As illustrated in FIG. 4B, a plurality of grooves 3221 extending in a direction intersecting the axial direction (e.g., a direction perpendicular to the axial direction) are formed on the outer surface of each barrel piece 322 at intervals LB in the axial direction. In the illustrated example, a plurality of grooves 3221(L) are formed on the outer surface of the barrel piece 322(L), and a plurality of grooves 3221(R) are formed on the outer surface of the barrel piece 322(R). Each groove 3221 may be realized by providing at least one of a recess extending in a direction intersecting the axial direction and a plurality of protrusions extending in a direction intersecting the axial direction on the outer surface of each barrel piece 322. For example, each groove 3221 may be such a recess, or the space between such protrusions may be such a groove. The groove 3221 is an example of the "groove" of the present invention. As described above, the plurality of grooves 3221 may be formed on the outer surface of at least one of the barrel pieces 322(L) and 322(R) in the gas sensor 1. For example, the plurality of grooves 3221 may be formed only on the outer surface of the barrel piece 322(L), or may be formed only on the outer surface of the barrel piece 322(R).

[0074] In the gas sensor 1, the multiple grooves 3221 are formed on the outer surface of each barrel piece 322 so that the interval LB between adjacent grooves 3221 is narrower than the interval LA between adjacent connector electrodes 12 on at least one surface on the rear end side of the sensor element 10. That is, the interval LB between adjacent grooves 3221 among the multiple grooves 3221 is narrower than the interval LA between adjacent connector electrodes 12 among the multiple connector electrodes 12 in a direction perpendicular to the axial direction.

[0075] The present inventors have found that narrowing the interval LB between adjacent grooves 3221 can reduce the length (length in the longitudinal direction) of metal particles (burrs, foreign metal particles) generated from the barrel 32 (barrel pieces 322) or the like. Therefore, in the gas sensor 1, the interval LB between adjacent grooves 3221 is made narrower (smaller) than the interval LA between adjacent connector electrodes 12. By making the interval LB narrower than the interval LA, the gas sensor 1 can make the length of metal particles generated from the barrel 32 or the like shorter than the interval LA. Therefore, even when the barrel 32 that crimps and holds the lead wire 40 is housed inside the spacer 70, the gas sensor 1 can prevent short circuits caused by metal particles generated from the barrel 32 or the like. In particular, the present inventors have confirmed through a test (cleanliness analysis test) described below that "narrowing the interval LB more than the interval LA" can reduce the number of metal particles that may cause short circuits and effectively prevent short circuits.

[0076] As described above, when the multiple "intervals LA between adjacent connector electrodes 12" are different for three or more connector electrodes 12, the interval LB between adjacent grooves 3221 may be narrower than the narrowest (smallest) "interval LA between adjacent connector electrodes 12." The gas sensor 1 controls the length of metal pieces generated from the barrel 32, etc., to be narrower (smaller) than the interval LA by using the interval LB between adjacent grooves 3221, thereby preventing short circuits caused by such metal pieces. Therefore, when the multiple intervals LA are different (not the same), the gas sensor 1 may determine the interval LB between adjacent grooves 3221 based on the "interval between adjacent connector electrodes 12" at which a short circuit is most likely to occur, that is, based on the narrowest (smallest) interval LA. By setting the interval LB between adjacent grooves 3221 narrower than the narrowest interval LA, the gas sensor 1 can prevent short circuits from occurring even between "adjacent connector electrodes 12" at which a short circuit is most likely to occur.

[0077] 4B, "LC" indicates the opening width of the groove portion 3221, and "LF" indicates the length of the groove portion 3221. The groove portions 3221 each have an "opening width (e.g., the opening width in the axial direction)" as opening width LC and a "length in a direction intersecting the axial direction (e.g., a direction perpendicular to the axial direction)" as length LF, and extend in a direction intersecting the axial direction at intervals LB from one another in the axial direction.

[0078] The opening width LC of the groove 3221 is narrower than the interval LA between adjacent connector electrodes 12 on at least one surface of the rear end of the sensor element 10. By making the opening width LC narrower than the interval LA, the gas sensor 1 can reduce the length of metal fragments generated from the barrel 32, etc., to be shorter than the interval LA. Therefore, even when the barrel 32 that crimps and holds the lead wire 40 is housed inside the spacer 70, the gas sensor 1 can prevent short circuits caused by metal fragments generated from the barrel 32, etc. In particular, the present inventors confirmed through the test described below that "making the opening width LC narrower than the interval LA" can reduce the number of metal fragments that may affect the occurrence of short circuits, thereby effectively preventing the occurrence of short circuits. Note that, when the multiple "intervals LA between adjacent connector electrodes 12" are different for three or more connector electrodes 12, the opening width LC of the groove 3221 may be configured to satisfy the following condition, similar to the interval LB between adjacent grooves 3221. That is, the opening width LC of the groove 3221 may be narrower than the narrowest (smallest) "distance LA between adjacent connector electrodes 12."

[0079] As described above, the interval LB between adjacent grooves 3221 is narrower than the interval LA between adjacent connector electrodes 12, and the opening width LC of the grooves 3221 is narrower than the interval LA between adjacent connector electrodes 12. In the gas sensor 1, the opening width LC of the grooves 3221 may be equal to or greater than the interval LB between adjacent grooves 3221. With this configuration, the gas sensor 1 can make the length of metal pieces generated from the barrel 32 or the like shorter than the interval LA. Therefore, even when the barrel 32 that crimps and holds the lead wire 40 is housed inside the spacer 70, the gas sensor 1 can prevent short circuits caused by metal pieces generated from the barrel 32 or the like.

[0080] 5 is a cross-sectional schematic diagram showing an example of the configuration of the groove portion 3221 and the like in the barrel piece 322. Specifically, it shows an image of the barrel piece 322 when viewed in a cross section along the thickness direction of the barrel piece 322. In the example shown, a plurality of groove portions 3221, namely groove portions 3221(1), 3221(2), 3221(3), ..., 3221(n), each with an opening width "LC", are formed on the outer surface of the barrel piece 322 at intervals LB from one another in the axial direction. "LD" in FIG. 5 indicates the depth of the groove portion 3221, and in particular indicates the depth in the thickness direction of the barrel piece 322.

[0081] 5 shows an example in which each groove 3221 is angular (rectangular) when viewed in a cross section along the thickness direction of the barrel piece 322, but the cross-sectional shape of the groove 3221 is not limited to being angular. Each groove 3221 may be U-shaped or V-shaped when viewed in a cross section along the thickness direction of the barrel piece 322.

[0082] The depth LD of the groove 3221 is 90% or less of the thickness LE of the barrel piece 322. In other words, the groove 3221 is not a hole penetrating the barrel piece 322. By setting the depth LD of the groove 3221 to 90% or less of the thickness LE of the barrel piece 322, the length of metal fragments generated from the barrel 32 or the like can be made shorter than the interval LA in the gas sensor 1. Therefore, even when the barrel 32 that crimps and holds the lead wire 40 is housed inside the spacer 70, the gas sensor 1 can prevent the occurrence of a short circuit due to metal fragments generated from the barrel 32 or the like. In particular, the present inventors confirmed through a test described below that by "setting the depth LD of the groove 321 to 90% or less of the thickness LE of the barrel piece 322," the number of metal fragments that may affect the occurrence of a short circuit can be reduced, and the occurrence of a short circuit can be effectively prevented.

[0083] 6A and 6B are diagrams illustrating an example of the outline of the barrel 32 before and after crimping (staking). Specifically, FIG. 6A shows an image of the barrel 32 before crimping, in which the barrel pieces 322 stand upright from both sides (both left and right ends) of the bottom plate 321, as viewed along the axial direction. In other words, FIG. 6A shows an image of the barrel 32 illustrated in FIG. 4A (the barrel 32 before crimping) as viewed along the axial direction. FIG. 6B shows an image of the barrel 32 after crimping (after crimping), as viewed in cross section perpendicular to the axial direction. In other words, FIG. 6B shows an image of the barrel 32 illustrated in FIG. 4A (the barrel 32 before crimping) after crimping. Note that in FIGS. 6A and 6B, the lead wire 40 (the core wire of the lead wire 40) is not shown to facilitate an understanding of the outline of the barrel 32.

[0084] As illustrated in (A) of Fig. 6, a plurality of grooves 3221, each having an opening width of "LC" and a length (length in a direction intersecting the axial direction) of "LF", are formed on the outer surface of the barrel piece 322 of the barrel 32 at intervals LB from one another in the axial direction. In the example shown, each groove 3221 extends in a direction perpendicular to the axial direction, and has a length of "LC" in the direction perpendicular to the axial direction. In the example shown, the plurality of grooves 3221 are spaced apart from one another in the axial direction, and each extend from an end of the barrel piece 322 (the end opposite to the end connected to the bottom plate 321) to the bottom plate 321 for a length LC in a direction intersecting the axial direction (for example, a direction perpendicular to the axial direction) at intervals LB from one another in the axial direction.

[0085] As shown in Fig. 6(B), in the barrel 32 after crimping, the pair of barrel pieces 322(L), 322(R) are bent deeply toward the bottom plate 321 in an arc-like manner, in other words, they overlap as if they are sliding inside each other. "LG" in Fig. 6(B) indicates the wrap height of the barrel 32 (barrel pieces 322). The "wrap height" is the length from the position where the pair of barrel pieces 322(L), 322(R) contact each other to each end of the pair of barrel pieces 322(L), 322(R) (the end of the barrel piece 322 opposite to the end connected to the bottom plate 321). In the illustrated example, the rolling height LG of the barrel 32 (barrel piece 322) indicates the length in the thickness direction of the bottom plate 321 from the position where the pair of barrel pieces 322(L), 322(R) contact each other to each end of the pair of barrel pieces 322(L), 322(R).

[0086] The length LF of the groove 3221 is equal to or greater than the wrapping height LG of the barrel 32 (barrel piece 322). As described above, by adjusting at least one of the interval LB between adjacent grooves 3221, the opening width LC, and the depth LD, the groove 3221 can make the length of metal chips generated from the barrel 32, etc. shorter than the interval LA between adjacent connector electrodes 12. Such metal chips are generated, for example, when the barrel pieces 322 overlap each other in a state where irregularities are generated on the outer surfaces of the barrel pieces 322 due to rubbing with the crimping surface of the crimper, or when the irregularities on the outer surfaces of the barrel pieces 322 scratch the surface of the core wire of the lead wire 40. Therefore, in order to control the length of metal chips generated from the barrel 32 (barrel piece 322), etc., the groove 3221 is preferably formed in the following region of the outer surface of the barrel piece 322. That is, the groove 3221 is preferably formed in "an area on the outer surface of the barrel piece 322 that comes into contact with at least one of the outer surface of the other barrel piece 322, the crimping surface of the crimper, and the surface of the core wire of the lead wire 40 during crimping." As described above, the wrapping height LG is the length from the position where the pair of barrel pieces 322(L) and 322(R) come into contact with each other to each end of the pair of barrel pieces 322(L) and 322(R). In other words, the wrapping height LG indicates the length of "an area where the outer surface of the barrel piece 322 reliably comes into contact with at least one of the outer surface of the other barrel piece 322, the crimping surface of the crimper, and the surface of the core wire of the lead wire 40 during crimping." Therefore, in the gas sensor 1, the length LF of the groove 3221 is set to be equal to or greater than the wrapping height LG of the barrel piece 322. That is, in the gas sensor 1, the length LF of the groove 3221 is set to be equal to or greater than the length of "the region where the outer surface of the barrel piece 322 is in secure contact with at least one of the outer surface of the other barrel piece 322, the crimping surface of the crimper, and the surface of the core wire of the lead wire 40 during crimping." In particular, the groove 3221 extends from the end of the outer surface of the barrel piece 322 where "the outer surface of the other barrel piece 322 is in secure contact with the outer surface of the other barrel piece 322, the crimping surface of the crimper, and the surface of the core wire of the lead wire 40 during crimping" to the bottom plate 321 in a direction intersecting the axial direction by a length LC.Therefore, in the gas sensor 1, the occurrence of a short circuit can be effectively prevented by forming the groove 3221, which makes the length of metal fragments generated from the barrel 32, etc. shorter than the interval LA, in an area on the outer surface of the barrel piece 322 where metal fragments may be generated during crimping. In particular, the inventors confirmed through a test described below that by "setting the length LF of the groove 3221 to be equal to or greater than the wrapping height LG of the barrel piece 322," the number of metal fragments that may affect the occurrence of a short circuit can be reduced, and the occurrence of a short circuit can be effectively prevented.

[0087] [Features] As described above, the gas sensor 1 according to one aspect of the present invention includes the sensor element 10, the plurality of metal terminals 30, the ceramic housing 60, the cylindrical body 20, the plurality of lead wires 40, the elastic body 50, and the spacer 70. The sensor element 10 extends in the axial direction and has a detection portion 11 at its front end, and has a plurality of connector electrodes 12 disposed on at least one surface at its rear end. Each of the plurality of metal terminals 30 extends in the axial direction of the sensor element 10 (gas sensor 1) and has an element contact portion 31 at its front end that is electrically connected to each of the plurality of connector electrodes 12 of the sensor element 10. The ceramic housing 60 is a ceramic member that houses the plurality of connector electrodes 12 of the sensor element 10 and the element contact portions 31 of the plurality of metal terminals 30. The cylindrical body 20 is a cylindrical member with an open end, and the ceramic housing 60 is disposed inside the cylindrical body 20. The plurality of lead wires 40 are each connected to a respective one of the plurality of metal terminals 30 and extend outward from the open end of the cylindrical body 20. The elastic body 50 is arranged to seal the open end of the cylindrical body 20. The spacer 70 is housed inside the cylindrical body 20 and is arranged between the ceramic housing 60 and the elastic body 50 in the axial direction of the sensor element 10, and is in contact with the ceramic housing 60. Each of the plurality of metal terminals 30 has a barrel 32 at its rear end that crimps and holds each of the plurality of lead wires 40.

[0088] In the gas sensor 1, the barrels 32 of the multiple metal terminals 30 are housed inside the spacer 70. The barrel 32 includes a bottom plate 321 on which the core wires of the multiple lead wires 40 are placed, and a pair of barrel pieces 322 that protrude from both sides of the bottom plate 321 and are crimped to the core wires of the lead wires 40 by being wrapped around the core wires. On the surface of the barrel 32 opposite the surface on which the core wires of the lead wires 40 are placed, at least one of the pair of barrel pieces 322 is formed with multiple grooves 3221 that extend in a direction intersecting the axial direction of the sensor element 10 at intervals LB from each other. The intervals LB between adjacent grooves 3221 among the multiple grooves 3221 are narrower than the intervals LA. The spacing LA is the spacing between adjacent connector electrodes 12 among the multiple connector electrodes 12 arranged on at least one surface on the rear end side of the sensor element 10, in a direction perpendicular to the axial direction of the sensor element 10.

[0089] In this configuration, in the gas sensor 1, the barrel 32 that crimps and holds the lead wire 40 is housed inside the spacer 70. At least one of the pair of barrel pieces 322 is formed on the surface of the barrel 32 opposite to the surface on which the core wire of the lead wire 40 is placed, with a plurality of grooves 3221 that extend in a direction intersecting the axial direction of the sensor element 10 and are spaced apart by a distance LB from each other in the axial direction. That is, on the outer surface of at least one of the pair of barrel pieces 322, the plurality of grooves 3221 are formed in the axial direction of the sensor element 10 and are spaced apart by a distance LB from each other. The distance LB between adjacent grooves 3221 is narrower than the distance LA between adjacent connector electrodes 12 in a direction perpendicular to the axial direction, among the plurality of connector electrodes 12 arranged on at least one surface on the rear end side of the sensor element 10.

[0090] The present inventors have found that narrowing the interval LB between adjacent grooves 3221 can reduce the length (length in the longitudinal direction) of metal particles (burrs, foreign metal particles) generated from the barrel 32 (barrel piece 322) or the like. Therefore, in the gas sensor 1, the interval LB between adjacent grooves 3221 is made narrower (smaller) than the interval LA between adjacent connector electrodes 12. By making the interval LB between adjacent grooves narrower than the interval LA between adjacent connector electrodes 12, the gas sensor 1 can make the length of metal particles generated from the barrel 32 or the like shorter (shorter) than the interval LA between adjacent connector electrodes 12. Therefore, even when the barrel 32 that crimps and holds the lead wire 40 is housed inside the spacer 70, the gas sensor 1 can prevent short circuits caused by metal particles generated from the barrel 32 or the like. In particular, the inventors of the present invention confirmed through the test (cleanliness analysis test) described below that by "making the distance LB between adjacent groove portions 3221 narrower than the distance LA between adjacent connector electrodes 12," the number of metal pieces that may affect the occurrence of a short circuit can be reduced, and the occurrence of a short circuit can be effectively prevented.

[0091] [Variations] Although the embodiments of the present invention have been described above, the above-described embodiments are merely illustrative of the present invention in every respect. Various improvements and modifications may be made to the above-described embodiments. The components of the above-described embodiments may be omitted, replaced, or added as appropriate. The shape and dimensions of the components of the above-described embodiments may be modified as appropriate depending on the embodiment. For example, the following modifications are possible. Note that, in the following, the same reference numerals are used for components similar to those of the above-described embodiment, and descriptions of the same points as those of the above-described embodiment are omitted as appropriate. The following modifications may be combined as appropriate.

[0092] [Example] In order to verify the effects of the present invention, gas sensors according to the following examples (standard) and comparative examples (Ref) were fabricated, although the present invention is not limited to the following examples. [Table 1]

[0093] (Summary of the test and test results) Table 1 shows the configuration of each gas sensor and the results of tests (cleanliness analysis tests) for the Ref and Levels 1 to 5 gas sensors. For the tests, a predetermined number (30 in this example) of gas sensors for each Level and Ref were prepared as samples. A 500-ml beaker was filled with 400 ml or more of filtrate water, and the prepared samples were immersed in the filtrate water and subjected to ultrasonic vibrations at 28 kHz and 100 W for 20 minutes. The samples were then filtered using a JIS P3801 No. 2 equivalent filter (filter mesh size: maximum 5 μm), and the number of residues (burrs (metal pieces) that could cause short circuits) was counted. The "burrs" in Table 1 indicates the relative number of burrs that could cause short circuits. "Burs that could cause short circuits" refers to burrs whose longitudinal length is longer than the distance LA between adjacent connector electrodes 12 in a direction perpendicular to the axial direction, among the multiple connector electrodes 12 arranged on the rear end surface of the sensor element 10. In other words, "burrs that may cause a short circuit" refers to burrs whose longitudinal length is longer than the distance LA between adjacent connector electrodes 12 and that may therefore cause a short circuit between the connector electrodes 12. In particular, the "burrs" in Table 1 indicates the number of burrs found for each level relative to the number of burrs found for Ref (100).

[0094] (Ref and details for each of levels 1 to 5) The gas sensors according to Reference (Comparative Example) and Levels 1 to 5 (Examples) have in common the configuration illustrated in Fig. 1. That is, the gas sensors according to Reference and Levels 1 to 5 each include a sensor element 10, a cylindrical body 20, a plurality of metal terminals 30, a plurality of lead wires 40, an elastic body 50, a ceramic housing 60, and a spacer 70. In the gas sensors according to Reference and Levels 1 to 5, the barrel 32 that crimps and holds the lead wires 40 of each metal terminal 30 is housed inside the spacer 70. Furthermore, a plurality of grooves 3221 are formed on the outer surface of each barrel piece 322 of the barrel 32, extending in a direction intersecting the axial direction and spaced apart from each other by a distance LB in the axial direction.

[0095] However, the gas sensors according to Ref and levels 1 to 5 differ in the spacing LB between adjacent grooves 3221, the opening width LC of the grooves 3221 in the axial direction, the depth LD of the grooves 3221 in the thickness direction of the barrel piece 322, and the length LF of the grooves 3221 in the direction intersecting the axial direction.

[0096] Specifically, in the gas sensor according to Ref, the distance LB between adjacent grooves 3221 is equal to or greater than the distance LA between adjacent connector electrodes 12. The opening width LC of the groove 3221 is equal to or greater than the distance LA between adjacent connector electrodes 12. The depth LD of the groove 3221 is greater than 90% of the plate thickness LE of the barrel piece 322. The length LF of the groove 3221 is smaller than the wrap height LG of the barrel piece 322 (barrel 32). The wrap height LG is the length from the position where the pair of barrel pieces 322(L), 322(R) contact each other to the end of each barrel piece 322.

[0097] In the gas sensor according to Level 1, the distance LB between adjacent grooves 3221 is equal to or greater than the distance LA between adjacent connector electrodes 12, as in the gas sensor according to Ref. However, the gas sensor according to Level 1 differs from the gas sensor according to Ref in other respects. That is, in the gas sensor according to Level 1, the opening width LC of the groove 3221 is smaller than the distance LA between adjacent connector electrodes 12. The depth LD of the groove 3221 is equal to or less than 90% of the "plate thickness LE of the barrel piece 322." The length LF of the groove 3221 is equal to or greater than the wrapping height LG of the barrel piece 322.

[0098] In the gas sensor according to Level 2, the opening width LC of the groove 3221 is equal to or greater than the distance LA between adjacent connector electrodes 12, as in the gas sensor according to Ref. However, the gas sensor according to Level 2 differs from the gas sensor according to Ref in other respects. That is, in the gas sensor according to Level 2, the distance LB between adjacent grooves 3221 is smaller than the distance LA between adjacent connector electrodes 12. The depth LD of the groove 3221 is equal to or less than 90% of the "plate thickness LE of the barrel piece 322." The length LF of the groove 3221 is equal to or greater than the wrapping height LG of the barrel piece 322.

[0099] In the gas sensor according to Level 3, the depth LD of the groove 3221 is greater than 90% of the "plate thickness LE of the barrel piece 322," similar to the gas sensor according to Ref. However, the gas sensor according to Level 3 differs from the gas sensor according to Ref in other respects. That is, in the gas sensor according to Level 3, the interval LB between adjacent grooves 3221 is smaller than the interval LA between adjacent connector electrodes 12. The opening width LC of the groove 3221 is smaller than the interval LA between adjacent connector electrodes 12. The length LF of the groove 3221 is equal to or greater than the wrapping height LG of the barrel piece 322.

[0100] In the gas sensor according to Level 4, the length LF of the groove 3221 is smaller than the wrapping height LG of the barrel piece 322, similar to the gas sensor according to Ref. However, the gas sensor according to Level 4 differs from the gas sensor according to Ref in other respects. That is, in the gas sensor according to Level 4, the interval LB between adjacent grooves 3221 is smaller than the interval LA between adjacent connector electrodes 12. The opening width LC of the groove 3221 is smaller than the interval LA between adjacent connector electrodes 12. The depth LD of the groove 3221 is 90% or less of the "plate thickness LE of the barrel piece 322."

[0101] In the gas sensor according to Level 5, the distance LB between adjacent grooves 3221 is smaller than the distance LA between adjacent connector electrodes 12. The opening width LC of the grooves 3221 is smaller than the distance LA between adjacent connector electrodes 12. The depth LD of the grooves 3221 is 90% or less of the "plate thickness LE of the barrel piece 322." The length LF of the grooves 3221 is equal to or greater than the wrapping height LG of the barrel piece 322.

[0102] (Test results) As shown in Table 1, the number of burrs found in the 30 gas sensors according to Level 1 was 50, assuming that the number of burrs found in the 30 gas sensors according to Reference was 100. Therefore, it was confirmed that the number of burrs that could affect the occurrence of short circuits can be reduced by making the opening width LC of the groove 3221 smaller than the distance LA between adjacent connector electrodes 12, making the depth LD of the groove 3221 90% or less of the plate thickness LE of the barrel piece 322, and making the length LF of the groove 3221 equal to or greater than the wrapping height LG of the barrel piece 322. Therefore, by configuring the opening width LC of the groove 3221, the depth LD of the groove 3221, and the length LF of the groove 3221 to satisfy the above-mentioned conditions, the gas sensor including the component illustrated in FIG. 1 can prevent the occurrence of short circuits.

[0103] As shown in Table 1, the number of burrs found in the 30 gas sensors according to Level 2 was 10, assuming the number of burrs found in the 30 gas sensors according to Reference is 100. Therefore, it was confirmed that the number of burrs that could affect the occurrence of short circuits can be extremely effectively reduced by making the distance LB between adjacent grooves 3221 smaller than the distance LA between adjacent connector electrodes 12, making the depth LD of the groove 3221 90% or less of the plate thickness LE of the barrel piece 322, and making the length LF of the groove 3221 equal to or greater than the wrapping height LG of the barrel piece 322. Therefore, by configuring the distance LB between adjacent grooves 3221, the depth LD of the groove 3221, and the length LF of the groove 3221 to satisfy the above-mentioned conditions, a gas sensor including the component illustrated in FIG. 1 can extremely effectively prevent the occurrence of short circuits.

[0104] As shown in Table 1, the number of burrs found in the 30 gas sensors according to Level 3 was 15, assuming the number of burrs found in the 30 gas sensors according to Ref is 100. Therefore, it was confirmed that the number of burrs that could affect the occurrence of short circuits can be extremely effectively reduced by making the distance LB between adjacent grooves 3221 smaller than the distance LA between adjacent connector electrodes 12, making the opening width LC of the groove 3221 smaller than the distance LA between adjacent connector electrodes 12, and making the length LF of the groove 3221 equal to or greater than the wrapping height LG of the barrel piece 322. Therefore, by configuring the distance LB between adjacent grooves 3221, the opening width LC of the groove 3221, and the length LF of the groove 3221 to satisfy the above-mentioned conditions, a gas sensor including the component illustrated in FIG. 1 can extremely effectively prevent the occurrence of short circuits.

[0105] As shown in Table 1, the number of burrs found in the 30 gas sensors according to Level 4 was 25, assuming the number of burrs found in the 30 gas sensors according to Ref was 100. Therefore, it was confirmed that the number of burrs that could affect the occurrence of short circuits can be extremely effectively reduced by making the distance LB between adjacent grooves 3221 smaller than the distance LA between adjacent connector electrodes 12, making the opening width LC of the groove 3221 smaller than the distance LA between adjacent connector electrodes 12, and setting the depth LD of the groove 3221 to 90% or less of the plate thickness LE of the barrel piece 322. Therefore, by configuring the distance LB between adjacent grooves 3221, the opening width LC of the groove 3221, and the depth LD of the groove 3221 to satisfy the above-mentioned conditions, a gas sensor including the component illustrated in FIG. 1 can extremely effectively prevent the occurrence of short circuits.

[0106] As shown in Table 1, the number of burrs found in the 30 gas sensors related to Level 5 was "0" when the number of burrs found in the 30 gas sensors related to Ref was "100." Therefore, it was confirmed that the number of "burrs that may affect the occurrence of short circuits" can be significantly and effectively reduced by "making the distance LB between adjacent grooves 3221 smaller than the distance LA between adjacent connector electrodes 12," "making the opening width LC of the groove 3221 smaller than the distance LA between adjacent connector electrodes 12," "making the depth LD of the groove 3221 90% or less of the plate thickness LE of the barrel piece 322," and "making the length LF of the groove 3221 equal to or greater than the wrapping height LG of the barrel piece 322." Therefore, by configuring the spacing LB between adjacent grooves 3221, the opening width LC of groove 3221, the depth LD of groove 3221, and the length LF of groove 3221 to satisfy the above-mentioned conditions, a gas sensor equipped with the component illustrated in Figure 1 can remarkably effectively prevent the occurrence of short circuits. [Explanation of symbols]

[0107] 1...gas sensor, 10...sensor element, 11...detection unit, 12...connector electrode, 20... cylindrical body, 30... metal terminal, 31... element contact portion, 32... barrel, 40...lead wire, 50...elastic body, 60...ceramic housing, 70...spacer, 321... bottom plate, 322... barrel piece, 3221... groove portion, LA: Spacing (the spacing between adjacent connector electrodes in a direction perpendicular to the axial direction), LB: Spacing (axial spacing between adjacent grooves) LC...Opening width (width of the groove opening), LD...depth (depth of the groove in the thickness direction of the barrel piece), LE...plate thickness (barrel piece thickness), LF: length (length of the groove in the direction intersecting the axial direction), LG...Winding height

Claims

1. a sensor element extending in an axial direction, having a detection portion at a front end side and a plurality of connector electrodes disposed on at least one surface at a rear end side; A plurality of metal terminals, each extending in the axial direction, Each of the connector electrodes has an element contact portion at a tip end side, the element contact portion being electrically connected to each of the plurality of connector electrodes. a plurality of metal terminals; a ceramic housing that accommodates the plurality of connector electrodes and the element contact portions of the plurality of metal terminals; a cylindrical body having an open end and the ceramic housing disposed therein; a plurality of lead wires, each connected to a respective one of the plurality of metal terminals and extending outward from the open end; an elastic body arranged to seal the open end; a spacer that is accommodated inside the cylindrical body, that is disposed between the ceramic housing and the elastic body in the axial direction, and that contacts the ceramic housing; Equipped with each of the plurality of metal terminals includes a barrel at a rear end side for crimping and holding each of the plurality of lead wires; The barrel of each of the plurality of metal terminals is housed within the spacer, The barrel is a bottom plate on which core wires of the plurality of lead wires are placed; a pair of barrel pieces protruding from both sides of the bottom plate and crimped to be wound around the core wire; Equipped with a plurality of grooves extending in a direction intersecting the axial direction and spaced apart from one another in the axial direction are formed in at least one of the pair of barrel pieces on a surface of the barrel opposite to a surface on which the core wire is placed, the interval between adjacent grooves among the plurality of grooves is narrower than the interval between adjacent connector electrodes among the plurality of connector electrodes in a direction perpendicular to the axial direction; Gas sensor.

2. a width of each of the openings of the plurality of grooves in the axial direction is narrower than a distance between the adjacent connector electrodes in a direction perpendicular to the axial direction; 2. The gas sensor according to claim 1.

3. a width of each of the openings of the plurality of grooves in the axial direction being equal to or greater than the interval between the adjacent grooves; 3. The gas sensor according to claim 1.

4. a depth of each of the plurality of grooves in the thickness direction of the barrel section is 90% or less of the thickness of the barrel section; 3. The gas sensor according to claim 1.

5. a length of each of the plurality of grooves in a direction intersecting the axial direction is equal to or greater than a wrap height, which is a length from a position where the pair of barrel pieces contact each other to each end of the pair of barrel pieces; 3. The gas sensor according to claim 1.

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