JP2008298535A - Sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor for providing stability of an electrical connection between a terminal part and an electrode part by preventing a breakage or wear of the electrode part which can occur when a connection terminal is fitted into a sensor element. <P>SOLUTION: The terminal part 21 of the connection terminal 2 fitted into a rear end part 67 of the sensor element 6 includes a projection part 22 inwardly projecting from its inner circumferential surface 218, and a contact part 219 for making contact with the electrode part 75 of the sensor element 6. Since fitting of the terminal part 21 thereinto is performed by the projection part 22 with a gap formed between an end 215 of the terminal part 21 or the contact part 219 and an outer circumferential surface 69 of the sensor element 6, the electrode part 75 is prevented from being broken or worn away. The projection part 22's reaching the formation position of a housing part 77 for the sensor element 6 to be housed in the housing part 77 brings the contact part 219 and the electrode part 75 into contact with each other to achieve an electrical connection. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sensor in which a connection terminal for taking out an output of a sensor element for detecting an object to be detected is fitted on the rear end side of the sensor element.

  2. Description of the Related Art Conventionally, an oxygen sensor that detects the concentration of oxygen contained in automobile exhaust gas is known as an example of a sensor that includes a sensor element that detects an object to be detected. As a sensor element of this oxygen sensor, one having a detection part formed by sandwiching a solid electrolyte body between a pair of electrodes from the inside and the outside is known on the tip side of the solid electrolyte body formed in a bottomed cylindrical shape. . On the outer peripheral surface on the rear end side of such a sensor element, an electrode part for taking out a detection signal from the detection part is formed. A connection terminal connected to a lead wire for outputting a detection signal from the detection unit to an external circuit is mounted on the rear end side of the sensor element, and the connection terminal and the electrode unit are electrically connected by contact. .

As described above, the sensor element (oxygen sensor element) has a cylindrical shape so that the contact between the electrode portion (connection layer) provided on the rear end side and the connection terminal (second sensor terminal fitting) can be reliably performed. Is provided with a cylindrical terminal portion (gripping portion) on the connection terminal, and the terminal portion is fitted to the rear end side of the sensor element while being expanded radially outward by the sensor element (for example, Patent Documents) 1). After the fitting, the sensor element is gripped so as to be wrapped by the inner peripheral surface of the terminal portion, so that the contact between the connection terminal and the electrode portion can be favorably maintained.
JP 2004-53425 A

  However, if the terminal portion of the connection terminal is fitted to the rear end side of the sensor element while expanding the terminal portion radially outward, the outer peripheral surface of the sensor element is the tip of the terminal portion in the circumferential direction (open end on the tip side in the fitting direction). Or it will be rubbed by the inner peripheral surface. For this reason, when the tip of the terminal part rides on the electrode part in the process of fitting (that is, when the tip part of the terminal part comes into contact with the electrode part and overlaps in the radial direction), or after the ride, When fitted in the sensor element, there is a possibility that the electrode portion is scraped by the tip of the terminal portion and the electrode portion is damaged, or the electrode portion is worn due to friction with the tip or inner peripheral surface of the terminal portion. If the electrode part is lost or worn, the contact between the electrode part and the terminal part becomes uncertain, and the stability of electrical connection may not be obtained.

  The present invention has been made in order to solve the above-described problems, and prevents the electrode portion from being lost or worn when the connection terminal is fitted into the sensor element, thereby preventing electrical connection between the terminal portion and the electrode portion. An object is to provide a sensor capable of obtaining stability.

  In order to achieve the above object, a sensor according to a first aspect of the present invention has a bottomed cylindrical shape extending in the axial direction and closed at the tip side, and a detection unit for detecting a detected object at the tip side. And a cylindrical terminal that covers the circumferential direction on the rear end side of the sensor element, on the outer peripheral surface of the rear end side of the sensor element. A connection terminal that outputs a detection signal from the detection unit to an external circuit, and the terminal unit is fitted into the sensor element while being spread outward in the radial direction by the sensor element. In the sensor in which the electrode portion is in contact, the sensor element is provided with a receiving portion recessed from an outer peripheral surface on the rear end side in the axial direction with respect to the electrode portion, and the terminal portion of the connection terminal Projecting inward from the inner surface A protrusion which is housed in the housing portion while being formed on the distal end side of the projecting portion of the terminal portion, characterized in that a contact portion in contact with the electrode portion is provided.

  According to a second aspect of the present invention, in addition to the configuration of the first aspect of the invention, the protruding portion of the connection terminal is provided at a plurality of locations.

  According to a third aspect of the present invention, in addition to the configuration of the second aspect of the invention, the terminal portion has a C-shape in a cross section perpendicular to the axial direction, and the protruding portion is At least one end portion and the other end portion in the circumferential direction on the inner peripheral surface of the terminal portion are provided, respectively.

  According to a fourth aspect of the present invention, in addition to the configuration of the third aspect of the invention, the protruding portion of the connection terminal is formed on the inner peripheral surface of the terminal portion when viewed from the axial direction. It is provided in the intermediate part of the circumferential direction, It is characterized by the above-mentioned.

  According to a fifth aspect of the present invention, in addition to the configuration of the first aspect of the present invention, the projecting portion of the connection terminal pushes the outer peripheral surface of the terminal portion in the thickness direction. The terminal portion has a projecting inner peripheral surface.

  According to a sixth aspect of the present invention, in addition to the configuration of the first aspect of the present invention, the accommodating portion of the sensor element is configured to make one round in the circumferential direction of the outer peripheral surface of the sensor element. The electrode portion is formed in a belt shape that goes around the outer peripheral surface in the circumferential direction.

  According to a seventh aspect of the present invention, in addition to the configuration of the first aspect of the present invention, a contact portion that protrudes inward is formed at the contact portion of the connection terminal. It is characterized by that.

  In the sensor according to the first aspect of the present invention, a housing portion that is recessed from the outer surface is provided on the rear end side in the axial direction from the electrode portion of the sensor element, and the terminal portion has a protruding portion that is housed in the housing portion, Since the contact portion that comes into contact with the electrode portion provided on the tip side of the protruding portion is provided, when the terminal portion is fitted on the rear end side of the sensor element, the tip or contact portion of the terminal portion contacts the electrode portion. The terminal portion can be fitted without leaving the tip or the contact portion of the terminal portion away from the outer peripheral surface of the sensor element by the protruding portion. As a result, in the process of fitting the terminal part, the electrode part provided on the outer peripheral surface of the sensor element may be scraped and lost at the tip of the terminal part, or may be rubbed and worn with the contact part. Can be prevented. When the protruding portion reaches the forming position of the receiving portion and is received in the receiving portion, there is no longer anything that moves the contact portion away from the outer peripheral surface of the sensor element. Electrical connection can be made by contacting the electrode portion provided on the more distal end side. By preventing the electrode portion from being broken or worn as described above, the contact portion can be satisfactorily contacted with the electrode portion, and the stability of the electrical connection between the terminal portion and the electrode portion can be obtained. it can.

  In addition, since the terminal portion is fitted into the sensor element while being spread outward in the radial direction, after the fitting, the outer peripheral surface of the sensor element is pressed inward in the radial direction with its inner peripheral surface. For this reason, a contact part can obtain sufficient contact pressure with respect to an electrode part, and can improve the stability of the electrical connection between a contact part and an electrode part more. In addition, since the projecting portion and the housing portion function as a prevention of coming off after fitting, the contact state between the contact portion and the electrode portion can be reliably maintained.

  The terminal portion has a cylindrical shape that covers the rear end side of the sensor element and needs only to have a shape that is spread outward in the radial direction, and there is a slit in the axial direction of the terminal portion (the axial direction of the sensor element). One having a C-shaped cross section perpendicular to the axial direction and one having a plurality of slits in the axial direction is preferable.

  As in the invention according to claim 2, if a plurality of protrusions are provided in the terminal portion, the gap between the tip or contact portion of the terminal portion and the outer peripheral surface of the sensor element is supported and maintained at a plurality of locations. Therefore, it is possible to more reliably prevent the electrode portion from being lost or worn.

  In addition, a plurality of protruding portions may be arranged in the circumferential direction on the terminal portion, or a plurality of protruding portions may be arranged shifted in the axial direction. Furthermore, the projecting portion may be a cylindrical convex portion or a ring shape continuous in the circumferential direction of the terminal portion.

  Further, the accommodating portion does not have to have the same shape as the protruding portion. For example, the protruding portion is a cylindrical convex portion, whereas the accommodating portion is a ring-shaped concave portion continuous in the circumferential direction of the element. May be.

  In addition, when the terminal portion having a C-shaped cross section is fitted to the rear end side of the sensor element while being spread radially outward by the sensor element, the one end portion and the other end portion in the circumferential direction of the terminal portion are separated from each other. However, as in the invention according to claim 3, if projections are provided at one end and the other end, the circumferential edge of the terminal portion is moved away from the outer peripheral surface of the sensor element in the radial direction. Therefore, it is possible to prevent the electrode portion from being scraped off due to the edge of the terminal portion.

  Further, as in the invention according to claim 4, if the protruding portion is also provided in the intermediate portion of the terminal portion in the circumferential direction, the inner peripheral surface of the terminal portion is supported in the radial direction by supporting at least three points on the outer peripheral surface of the sensor element. It is possible to maintain a gap between the two. In other words, since a gap can be provided over the circumference of the sensor element in the circumferential direction between the inner circumferential surface of the terminal portion and the outer circumferential surface of the sensor element, it is possible to reliably prevent the electrode portion from being damaged or worn. Can do.

  When providing the protruding portion in the terminal portion of such a connection terminal, the protruding portion can be easily formed by pushing the outer peripheral surface of the terminal portion in the thickness direction and protruding the inner peripheral surface as in the invention according to claim 5. Can be formed. Thereby, compared with the case where a connection terminal is produced by joining the protrusion part formed separately from the terminal part to the terminal part, the manufacturing process can be reduced and the number of parts can be reduced, thereby reducing the manufacturing cost.

  Moreover, in the invention which concerns on Claim 6, since the electrode part and accommodating part of a sensor element are provided in the circumferential direction around the outer peripheral surface of a sensor element, when a terminal part is inserted, a terminal part is inserted. There is no need to adjust the orientation in the circumferential direction.

  And if the contact part is formed in the contact part as in the invention according to claim 7, the contact between the terminal part and the electrode part is performed while generating a drag in the contact part having a small contact area. The stability of the electrical connection between them can be improved. In addition, even when the terminal part receives stress in the radial direction due to vibration or the like when the sensor is used, and a gap is generated between the contact part and the electrode part, the contact part and the electrode part are interposed between the contact part and the electrode part. Electrical connection can be maintained.

  Hereinafter, an embodiment of a sensor embodying the present invention will be described with reference to the drawings. First, as an example of the sensor according to the present invention, the structure of an oxygen sensor 1 that detects the concentration of oxygen contained in the exhaust gas of an automobile will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view showing the structure of the oxygen sensor 1. FIG. 2 is a perspective view of the sensor element 6. The oxygen sensor 1 shown in FIG. 1 is used by being attached to an exhaust pipe (not shown) of an automobile, and in the direction of the axis O, the side toward the tip of the sensor element 6 inserted into the exhaust pipe ( The closed side (the lower side in the figure) will be referred to as the front end side, and the side in the opposite direction (the upper side in the figure) will be described as the rear end side.

  An oxygen sensor 1 shown in FIG. 1 has a structure in which a cylindrical sensor element 6 having a long and closed end is disposed in a housing 10 including a metal shell 5, an outer cylinder 3, a protector 4, and the like. From the oxygen sensor 1, a lead wire 18 is drawn out for taking out a signal output from the sensor element 6 and energizing the heater 7 provided in the sensor element 6. The lead wire 18 is electrically connected to a sensor control device (not shown) provided at a position away from the oxygen sensor 1 or an electronic control device (ECU) of an automobile.

  As shown in FIGS. 1 and 2, the sensor element 6 of the oxygen sensor 1 is configured by forming a solid electrolyte body mainly composed of zirconia into a bottomed cylindrical shape extending in the direction of the axis O as a base body 61. is there. A flange-like flange portion 65 projecting outward in the radial direction is provided at a position substantially in the center of the base 61 in the axis O direction. The tip 66 on the tip side of the flange 65 is gradually reduced in diameter toward the tip, and the tip is closed to a spherical shape. On the outer surface of the tip portion 66, a porous detection electrode 62 made of Pt or a Pt alloy is formed so as to cover almost the entire surface thereof. A porous reference electrode 63 made of Pt or a Pt alloy is also formed on the inner surface (surface in the cylindrical hole) of the base 61 so as to cover almost the entire surface. Accordingly, the detection electrode 62 and the reference electrode 63 are opposed to each other at the tip portion 66 of the base 61 with the solid electrolyte body interposed therebetween, and this portion is the detection unit 64 that detects the oxygen concentration in the sensor element 6. Function as. Since this detection part 64 is a part exposed to the exhaust gas which distribute | circulates the inside of an exhaust pipe, when the oxygen sensor 1 is attached to the exhaust pipe (not shown) of a motor vehicle, the detection electrode 62 is the porous which consists of heat resistant ceramics. It is covered with a quality electrode protective layer (not shown) and protected from poisoning by exhaust gas.

  Further, a rear end portion 67 extending rearward with substantially the same outer diameter is provided on the rear end side of the flange portion 65 of the base body 61 of the sensor element 6, and is opened at the rear end 68. On the outer peripheral surface 69 of the rear end portion 67, a belt-like electrode portion 75 that makes a round in the circumferential direction on the outer peripheral surface 69 is formed at a position closer to the rear end 68 than the center in the axis O direction. The electrode part 75 is an electrode for taking out a detection signal from the detection part 64, and is connected to the detection electrode 62 through an electrode lead part 76 extending in the direction of the axis O along the outer peripheral surface of the sensor element 6. The electrode portion 75 and the electrode lead portion 76 are formed by printing a conductive paste of Pt or Pt alloy, for example.

  On the rear end side in the axis O direction with respect to the electrode portion 75, a groove-shaped accommodation portion 77 is formed which makes a round on the outer peripheral surface 69 together with the electrode portion 75 while being recessed from the outer peripheral surface 69. The accommodating portion 77 protrudes inward from the inner peripheral surface 218 of the terminal portion 21 when a terminal portion 21 (see FIG. 8) of the connection terminal 2 described later is fitted into the rear end portion 67 of the sensor element 6. The protrusion 22 (see FIG. 8) is provided to be accommodated in the groove.

  Next, as shown in FIG. 1, the sensor element 6 is held in a cylindrical hole 55 of the metal shell 5 in a state in which the sensor element 6 is surrounded by the cylindrical metal shell 5. The metal shell 5 is a cylindrical member made of stainless steel such as SUS430, and a male threaded portion 52 that is screwed into a mounting portion (not shown) of the exhaust pipe is formed on the distal end side. A distal end engaging portion 56 is formed on the outer periphery of the male screw portion 52 to engage a protector 4 described later on the outer periphery thereof. The detection portion 64 of the sensor element 6 protrudes further toward the distal end side than the distal end engagement portion 56.

  Further, a tool engaging portion 53 that is radially expanded is formed on the rear end side of the male threaded portion 52 of the metal shell 5, and when the oxygen sensor 1 is attached to the exhaust pipe attachment portion (not shown). The installation tool used is engaged. An annular gasket 11 is inserted into a portion between the tool engaging portion 53 and the male screw portion 52 to prevent gas from being released through the attachment portion of the exhaust pipe. A caulking portion 57 for caulking and fixing the sensor element 6 held in its own cylindrical hole 55 is provided on the rear end side of the metal shell 5. A portion of the rear end portion 67 of the sensor element 6 on the rear end side with respect to the center in the axis O direction protrudes rearward from the crimping portion 57, and the electrode portion 75 is exposed from the metal shell 5. And between the tool engaging part 53 and the crimping part 57, the rear-end engaging part 58 with which the front-end | tip part 31 of the outer cylinder 3 mentioned later is engaged is formed.

  Next, a stepped portion 59 having an inner periphery protruding radially inward is provided on the distal end side in the cylindrical hole 55 of the metal shell 5, and a cylindrical portion made of alumina is formed on the stepped portion 59. The support member 13 is locked with a metal packing 12 interposed. The inner periphery of the support member 13 is also formed in a step shape, and the flange portion 65 of the sensor element 6 is supported by the support member 13 through a metal packing 14 arranged in the stepped portion. Further, in the cylindrical hole 55, the back end side of the support member 13 is filled with a filling member 15 made of talc powder, and the back end of the filling member 15 is sandwiched between the filling member 15 and the support member 13. A cylindrical sleeve 16 made of alumina is arranged on the side.

  An annular ring 17 is disposed on the rear end side of the sleeve 16, and the sleeve 16 is attached to the filling member 15 via the ring 17 by crimping the crimping portion 57 of the metal shell 5 toward the inner tip. It is pressed against. Through the caulking of the caulking portion 57, the filling member 15 is compressed and filled so as to press the flange portion 65 of the sensor element 6 toward the support member 13 locked to the step portion 59 of the metal shell 5, and the main body A gap between the inner peripheral surface of the cylindrical hole 55 of the metal fitting 5 and the outer peripheral surface of the sensor element 6 is hermetically filled. As described above, the sensor element 6 is held in the cylindrical hole 55 of the metal shell 5 through each member sandwiched between the caulking portion 57 and the stepped portion 59.

  Next, the protector 4 that covers the detection portion 64 of the sensor element 6 protruding from the distal end engagement portion 56 toward the distal end side in the axis O direction is assembled to the distal end engagement portion 56 of the metal shell 5 and is welded. The metal shell 5 is integrally joined. The protector 4 protects the detection part 64 of the sensor element 6 that protrudes into the exhaust pipe when the oxygen sensor 1 is attached to the exhaust pipe (not shown) from collisions of water droplets or foreign matters contained in the exhaust gas. It is a member for. The protector 4 includes a bottomed cylindrical inner protector that is fixed to the outer protector 41 and has an outer protector 41 whose peripheral edge on the opened side is joined to the tip engaging portion 56. 45 and a double structure. On the outer peripheral surfaces of the outer protector 41 and the inner protector 45, there are respectively introduced inlets 42 for introducing exhaust gas into the interior and guiding the exhaust gas to the detector 64 (the gas inlet of the inner protector 45). Is not shown.) In addition, on the bottom surfaces of the outer protector 41 and the inner protector 45, discharge ports 43 and 48 for discharging water droplets and exhaust gas that have entered the inside are opened.

  Next, a cylindrical outer tube 3 made of stainless steel such as SUS304 is assembled on the rear end side of the metal shell 5, and the front end portion 31 is engaged with the rear end engaging portion 58. The distal end portion 31 of the outer cylinder 3 is crimped to the rear end engaging portion 58 from the outer peripheral side, and laser welding is performed around the outer periphery of the distal end portion 31. The outer cylinder 3 extends toward the rear end side along the direction of the axis O, and protrudes rearward from the rear end (clamping portion 57) of the metal shell 5 at the rear end portion 67 of the sensor element 6. In addition, the outer periphery of the separator 8 and the grommet 9 disposed on the rear end side with respect to it is surrounded in the radial direction.

  A connection terminal 2 that is in contact with the electrode portion 75 and is electrically connected to the detection electrode 62 is fitted into the rear end portion 67 of the sensor element 6 surrounded by the outer cylinder 3. The connection terminal 2 will be described later. Further, a rod-shaped heater 7 for heating and activating the solid electrolyte body is inserted into the cylindrical hole of the sensor element 6. A connection terminal 29 that contacts the reference electrode 63 and makes an electrical connection is inserted into the cylindrical hole of the sensor element 6 so as to be sandwiched between the sensor element 6 and the heater 7. A pair of electrode terminals 71 (only one electrode terminal 71 is shown in FIG. 1) for energizing the heater 7 is provided at the rear end of the heater 7. The connection terminal 2, the connection terminal 29, and the electrode terminal 71 are each joined by caulking and bonding with a core wire of a lead wire 18 for electrical connection with an external circuit (not shown).

  The separator 8 is formed in a cylindrical shape from an insulating ceramic. In order to separate the connection terminals 2, 29 and the electrode terminals 71 so as not to contact each other, an accommodating portion 82 for independently accommodating them is provided. Have. Each accommodating portion 82 passes through the separator 8 in the direction of the axis O, and is configured to be able to communicate with the atmosphere between the front end side and the rear end side with the separator 8 interposed therebetween. Four lead wires 18 (of which three lead wires 18 are shown in FIG. 1) respectively connected to the connection terminals 2 and 29 and the electrode terminal 71 are oxygen through an insertion hole 92 of a grommet 9 described later. It is pulled out of the sensor 1. Further, a flange portion 81 protruding radially outward is provided on the outer peripheral surface of the separator 8, and a substantially cylindrical holding metal fitting 85 is fitted on the outer peripheral surface on the tip side of the flange portion 81. . The outer peripheral surface of the outer cylinder 3 corresponding to the arrangement position of the separator 8 is caulked inward in the radial direction, so that the holding metal fitting 85 holds the separator 8 inside itself, and the inner side of the outer cylinder 3 It is held by crimping.

  A grommet 9 made of fluorine rubber is disposed on the rear end side of the separator 8. The grommet 9 is fitted into the opening 32 on the rear end side of the outer cylinder 3 so as to close the housing 10 on the rear end side, and is fixed by crimping the outer periphery of the outer cylinder 3. The grommet 9 is formed with a communication hole 91 for introducing the atmosphere into the housing 10 so as to penetrate in the direction of the axis O. The oxygen sensor 1 is configured such that the reference electrode 63 formed in the cylinder of the sensor element 6 is exposed to the atmosphere via the communication hole 91 and the accommodating portion 82 of the separator 8. A thin-film filter member 87 made of a fluororesin such as PTFE (polytetrafluoroethylene) and its fastener 88 are inserted into the communication hole 91 to prevent entry of water droplets or the like. The grommet 9 is formed with four insertion holes 92 through which the four lead wires 18 described above are inserted independently (two insertion holes 92 are shown in FIG. 1).

  Next, a detailed configuration of the connection terminal 2 that is fitted into the rear end portion 67 of the sensor element 6 and electrically connected to the electrode portion 75 will be described with reference to FIGS. FIG. 3 is a perspective view of the connection terminal 2 before being assembled to the oxygen sensor 1 as seen from the front, left side, and plane. FIG. 4 is a development view of the connection terminal 2. FIG. 5 is a front view of the connection terminal 2 before assembly to the oxygen sensor 1. FIG. 6 is a left side view of the connection terminal 2 before assembly to the oxygen sensor 1. FIG. 7 is a cross-sectional view of the terminal portion 21 as viewed from the direction of the arrows along the one-dot chain line AA in FIG. 4. FIG. 8 is a cross-sectional view of the terminal portion 21 as viewed from the direction of the arrows along the one-dot chain line BB in FIG.

  3 is inserted into the rear end 67 (see FIG. 2) of the sensor element 6, and the terminal portion 21 in which the contact portion 219 makes contact with the electrode portion 75 and the lead wire 18 (see FIG. 3). 1), and a neck portion 26 that connects the terminal portion 21 and the crimping portion 25 to each other.

  As shown in FIG. 4, the terminal portion 21 of the connection terminal 2 is made of a plate processed into a substantially rectangular shape, and its longitudinal direction is bent in the circumferential direction. As shown in FIG. 213 is brought close to each other, and as shown in FIG. 3, it is formed in a cylindrical shape having a cylindrical axis P indicated by a one-dot chain line as a central axis. As shown in FIG. 4, an edge on one side in the short side direction of the terminal portion 21 (which will be described later is an edge on the distal end side when the connection terminal 2 is fitted into the sensor element 6. From 215, a plurality (eight in the present embodiment) of protruding pieces 216 arranged in the longitudinal direction protrude along the short direction. When the terminal portion 21 is bent into a cylindrical shape, the protruding piece 216 has one surface (hereinafter referred to as a convenience) that becomes the outer peripheral side after molding (after being formed into a cylindrical shape) at the position of the tip 215 of the terminal portion 21. It is called an “outer peripheral surface.”) It is bent at an obtuse angle toward the 217 side, and is spread radially outwardly with respect to the cylindrical hole formed by the terminal portion 21 as shown in FIGS.

  As shown in FIG. 4, four substantially circular projecting portions 22 are provided side by side in the longitudinal direction at a position slightly closer to the tip 215 side than the center in the short direction of the terminal portion 21. As shown in FIG. 7, the protruding portion 22 is formed by pressing the outer peripheral surface 217 of the terminal portion 21 in the thickness direction by, for example, pressing, and forming the other surface on the inner peripheral side after forming the terminal portion 21 (hereinafter, “internal It is formed by projecting 218. As shown in FIG. 8, the projecting portion 22 is configured such that the cross section thereof has a shape that smoothly inclines from the inner peripheral surface 218 toward the projecting tip that projects most toward the axis P side.

  As shown in FIG. 4, one protrusion 22 is provided at each of one end 225 (a portion near one end 212) and one other end 226 (a portion near the other end 213) in the longitudinal direction of the terminal portion 21. It is provided one by one. Further, two projecting portions 22 are provided in the intermediate portion 227 between the one end portion 225 and the other end portion 226, and more specifically, the center thereof is symmetric with respect to the center in the longitudinal direction of the terminal portion 21. One is provided at a position close to each other. A portion of the terminal portion 21 that is closer to the tip 215 than the protruding portion 22 is in contact with the electrode portion 75 when the connection terminal 2 is fitted into the sensor element 6 and is electrically connected to the electrode portion 75. It functions as 219.

  In FIG. 4, for convenience of explanation, the entire portion of the terminal portion 21 that is closer to the tip 215 than the protruding portion 22 is surrounded by a dotted line, and this portion is shown as the contact portion 219. However, the size and range of the contact portion in the present invention The shape is not limited. That is, the contact portion in the present invention is located on the tip 215 side of the protruding portion 22 in the terminal portion 21, and when the terminal portion 21 is fitted into the rear end portion 67 of the sensor element 6 (see FIG. 12), the electrode portion 75. Any part may be used as long as it is in contact with and electrically connected to the terminal.

  Next, a narrow neck portion 26 protrudes from a center position in the longitudinal direction at an edge (hereinafter referred to as “rear end”) 214 on the other side in the short side direction of the terminal portion 21. The neck portion 26 is extended along the short direction of the terminal portion 21, and a crimping portion 25 to which the core wire of the lead wire 18 is caulked is provided at the protruding tip of the neck portion 26. A slightly wide support portion 27 is formed in the middle portion of the neck portion 26. A support arm 271 is formed in the center of the support portion 27 so as to be elongated in a substantially U-shape while leaving the crimping portion 25 side. As shown in FIG. It is pushed into the outer peripheral surface 217 side. As shown in FIG. 1, the support arm 271 contacts the inner peripheral surface of the accommodating portion 82 of the separator 8 when the oxygen sensor 1 is assembled, and bears the positioning of the connection terminal 2 in the separator 8. . Further, a portion of the neck portion 26 closer to the terminal portion 21 than the support portion 27 is bent so as to form a gentle step shape in the thickness direction.

  In the connection terminal 2 having such a configuration, when the terminal portion 21 is bent into a cylindrical shape, the inner diameter of the terminal portion 21 (at least the minimum inner diameter of the cylindrical hole passing through the protruding tip of the protruding portion 22) is the rear of the sensor element 6. It is processed so as to be smaller than the outer diameter of the end portion 67. For this reason, when manufacturing the oxygen sensor 1, when the terminal portion 21 is fitted into the rear end portion 67 of the sensor element 6, the terminal portion 21 is pushed outward in the radial direction in accordance with the outer diameter of the rear end portion 67. (See FIG. 10). Here, in the present embodiment, one protrusion 225 and one other end 226 of the terminal portion 21 are respectively protruded from the inner peripheral surface 218 and two protrusions 22 are protruded inward from the intermediate portion 227. A gap is formed between the inner peripheral surface 218 of the portion 21 and the outer peripheral surface 69 of the rear end portion 67. Therefore, in the fitting process, the contact between the terminal portion 21 and the electrode portion 75 is avoided until the terminal portion 21 reaches a predetermined position of the rear end portion 67.

  Hereinafter, the manufacturing process of the oxygen sensor 1 will be described. In particular, the process of fitting the connection terminal 2 into the sensor element 6 will be described in detail later. First, in the sensor element 6 shown in FIG. 2, the detection electrode 62, the electrode lead-out portion 76, the electrode portion 75, and the reference electrode 63 are formed by printing or the like on the surface of the fixed electrolyte body formed in a bottomed cylindrical shape. It is fabricated by firing after an electrode protective layer is formed covering the surface of the detection electrode 62. As shown in FIG. 1, the sensor element 6 is caulked and held in the cylindrical hole 55 of the metal shell 5 to which the protector 4 is assembled.

  On the other hand, as shown in FIG. 4, the connection terminal 2 is first formed by punching a conductive plate material to form each shape of the terminal portion 21, the neck portion 26, the support portion 27, and the crimping portion 25. At this time, the protrusion 22 and the support arm 271 are also processed. Further, the terminal portion 21 is bent into a tubular shape, and the crimping portion 25, the support arm 271 and the neck portion 26 of the support portion 27 are each bent, and the connection terminal 2 is manufactured. As shown in FIG. 1, the connection terminal 2 is accommodated in the separator 8 together with the connection terminal 29 and the heater 7 in a state where the core wire of the lead wire 18 is crimped to the crimping portion 25. The separator 8 is a grommet. 9 is held at a predetermined position in the outer cylinder 3 together with 9 and held by the outer cylinder 3.

  In this way, the assembly intermediate on the front end side of the housing 10 holding the sensor element 6 etc. on the metal shell 5 and the rear end side of the housing 10 holding the connection terminals 2, 29, the heater 7 etc. on the outer cylinder 3. The assembly intermediate is produced in a separate process. Both are combined, the front-end | tip part 31 of the outer cylinder 3 is engaged with the rear-end engaging part 58 of the metal shell 5, and the periphery is crimped. Further, laser welding is applied to the caulking portion, and both the assembly intermediate bodies on the front end side and the rear end side are integrated, and the oxygen sensor 1 is completed.

  By the way, the heater 7 and the connecting terminal 29 held by the rear end side assembly intermediate member are combined with each other when the front end side assembly intermediate member and the rear end side assembly intermediate member are combined with each other. Is inserted into the cylindrical hole of the sensor element 6 held on the surface. Further, the terminal portion 21 of the connection terminal 2 is fitted into the rear end portion 67 of the sensor element 6 so as to align the cylinder axis P (see FIG. 4) with the axis O, and covers the outer peripheral surface 69 of the rear end portion 67. The contact portion 219 comes into contact with the electrode portion 75 to be electrically connected.

  Hereinafter, the process of fitting the terminal portion 21 of the connection terminal 2 into the rear end portion 67 of the sensor element 6 will be described in detail with reference to FIGS. 9 to 12. 9 to 12 are diagrams illustrating a process of fitting the terminal portion 21 of the connection terminal 2 into the rear end portion 67 of the sensor element 6. 9 to 12, focusing on the terminal portion 21 of the connection terminal 2 and the rear end portion 67 of the sensor element 6, the heater 7 and the connection terminal 29 are not illustrated.

  As described above, the terminal portion 21 of the connection terminal 2 shown in FIG. 9 is viewed from the rear in the axis O direction (upper side in the drawing) when the front-end assembly intermediate and the rear-end assembly intermediate are combined with each other. The sensor element 6 is fitted into the rear end 67. That is, the direction toward the front end side along the axis O is the fitting direction into the rear end portion 67 of the terminal portion 21. At this time, the rear end portion 67 of the sensor element 6 is guided so as to be inserted into the cylindrical hole of the terminal portion 21 by the protruding piece 216 protruding from the front end 215 of the terminal portion 21. For this reason, in the fitting process, as shown in FIG. 10, the cylinder axis P of the terminal portion 21 is gradually aligned with the axis O of the sensor element 6. The cylindrical axis P of the terminal portion 21 and the axis O of the sensor element 6 are different from each other in the fitting process and after fitting because the inner diameter of the terminal portion 21 and the outer diameter of the rear end portion 67 are different. However, here, it is assumed that they coincide for the convenience of explanation.

  Here, as described above, the terminal portion 21 is configured such that the inner diameter thereof is smaller than the outer diameter of the rear end portion 67 of the sensor element 6, and the terminal portion 21 is separated from one end 212 and the other end 213. The peripheral surface is open. For this reason, in the initial stage of the process of fitting into the rear end portion 67, when the inner diameter of the terminal portion 21 on the front end 215 side is expanded by the rear end portion 67 and the cross section of the terminal portion 21 passing through the cylindrical axis P is seen. Moreover, the terminal part 21 becomes a form which opens in a square shape. Therefore, the front end 215 moves away from the outer peripheral surface 69 of the rear end portion 67 radially outward.

  Then, the terminal portion 21 is moved in the fitting direction, and as shown in FIG. 11, the protruding portion 22 rides on the outer peripheral surface 69 of the rear end portion 67 (the protruding portion 22 and the outer peripheral surface 69 of the rear end portion 67 are In a state in which the arrangement is overlapped in the radial direction, a gap is formed between the inner peripheral surface 218 of the terminal portion 21 and the outer peripheral surface 69 of the rear end portion 67. As described above, the protruding portion 22 is provided at one end 225 and the other end 226 in the longitudinal direction of the terminal portion 21 and two at the intermediate portion 227, each of which is slightly on the tip 215 side from the center in the short direction. It is arranged at the position. For this reason, the contact part 219 and the front-end | tip 215 of the terminal part 21 which are in the front-end | tip 215 side rather than the protrusion part 22 will be in the state kept away from the outer peripheral surface 69 in the radial direction over the outer periphery 69 of the rear-end part 67. .

  Even if the terminal portion 21 is pushed in the fitting direction in this state, the state in which the protruding portion 22 is in contact with the outer peripheral surface 69 of the rear end portion 67 is maintained, so that the fitting of the terminal portion 21 is performed by the contact portion 219 or This is continued with a gap between the front end 215 and the outer peripheral surface 69 of the rear end 67. Therefore, the contact portion 219 and the tip 215 are disposed at positions that overlap the electrode portion 75 in the radial direction without contacting the electrode portion 75 formed on the outer peripheral surface 69. That is, the tip 215 and the contact portion 219 of the terminal portion 21 do not contact the electrode portion 75, and the electrode portion 75 is not scraped or worn.

  When the terminal portion 21 is further pushed in the fitting direction, the projecting portion 22 reaches the formation position of the accommodating portion 77 formed at the rear end portion 67 and is accommodated in the accommodating portion 77 as shown in FIG. Since the accommodating portion 77 is formed in a groove shape that makes a round around the rear end portion 67, the protruding portion 22 can be accommodated at any position in the circumferential direction on the inner peripheral surface 218 of the terminal portion 21. And by accommodating the protrusion part 22 in the accommodating part 77, the support of the gap | interval between the outer peripheral surface 69 of the rear-end part 67 and the inner peripheral surface 218 of the terminal part 21 is lose | eliminated, and the terminal part 21 is radial direction inward. The inner peripheral surface 218 and the outer peripheral surface 69 of the rear end portion 67 are disposed close to each other. Thereby, the contact part 219 contacts the electrode part 75, and electrical connection is made | formed between both. Since the inner diameter of the terminal portion 21 before fitting is smaller than the outer diameter of the rear end portion 67, the terminal portion 21 is configured to press the outer peripheral surface 69 of the sensor element 6 inward in the radial direction with its inner peripheral surface 218. . Further, as described above, the electrode portion 75 is not scraped in the fitting process. And the protrusion part 22 accommodated in the accommodating part 77 functions as a stopper, the fitting position of the terminal part 21 with respect to the rear-end part 67 is fixed, and a shift | offset | difference arises in the contact position of the contact part 219 and the electrode part 75. There is no. For this reason, in the present embodiment, the reliability and stability of electrical connection between the contact portion 219 and the electrode portion 75 can be improved.

  Needless to say, the present invention is not limited to the above embodiment, and various modifications are possible. For example, the terminal portion 21 of the connection terminal 2 is formed in a cylindrical shape with a C-shaped cross section, but is formed into a cylindrical shape with an O-shaped cross section, and for example, a slit is provided on the tip side in the fitting direction so that the inner diameter can be changed. It is good also as a form inserted in the rear-end part 67 of the element 6. FIG. In such a configuration, in the fitting process, a protrusion is provided for each portion divided by each slit so that the portion divided by each slit has a gap with respect to the outer peripheral surface 69 of the rear end portion 67. What should I do? Further, a part of the terminal portion 21 in the circumferential direction may be extended to the distal end side, and a protruding portion and an electrode portion may be provided at that portion.

  Further, the four protruding portions 22 of the connection terminal 2 do not necessarily have to be provided in the terminal portion 21. For example, the protruding portions 22 are formed at two locations of the one end portion 225 and the other end portion 226 and not at the intermediate portion 227. There may be. In such a configuration, the tip 215 of the intermediate portion 227 of the terminal portion 21 may abut against the electrode portion 75 during the fitting process to cause a defect. However, the contact portion of the contact portion 219 and the electrode lead-out portion in the electrode portion 75 may occur. If the fitting direction of the terminal portion 21 with respect to the rear end portion 67 of the sensor element 6 is adjusted so that the terminal portion 76 is not disconnected, the electrical connection between the terminal portion 21 and the electrode portion 75 can be sufficiently maintained. Can do. Of course, the electrode part 75 does not necessarily have to be formed around the outer peripheral surface 69 of the rear end part 67. Further, the number of protrusions 22 is not limited to four, and may be two, three, five or more as described above.

  Further, the protruding portion 22 is formed by pushing the outer peripheral surface 217 of the terminal portion 21 toward the inner peripheral surface 218 side. However, the protruding portion 22 may be provided by forming or joining a protrusion on the inner peripheral surface 218, or may be provided on the terminal portion 21. A notch may be formed and pushed into the inner peripheral surface 218 side. Moreover, the protrusion part 22 may have urging | biasing force in a protrusion direction, and the terminal part 21 is good also as a thing which does not deform | transform, for example in the cylinder shape of an O-shaped cross section. Further, like the connection terminal 302 shown in FIG. 13, a protruding portion 322 that protrudes radially inward in a continuous state in the circumferential direction may be formed by bending the terminal portion 321 itself.

  Further, like the connection terminal 402 shown in FIG. 14, a contact portion 423 that protrudes radially inward from the inner peripheral surface 418 may be formed on the contact portion 419 of the terminal portion 421. If the size of the contact portion 423 protruding from the inner peripheral surface 418 is smaller than the size of the protrusion 422 protruding from the inner peripheral surface 418, the contact portion 423 contacts the electrode portion 75 in the fitting process. It is difficult to touch, which is preferable. When such a contact portion 423 is provided in the contact portion 419, the contact between the terminal portion 421 and the electrode portion 75 is performed while generating a drag at a portion with a small contact area (a protruding tip of the contact portion 423). Therefore, the stability of the electrical connection between the two can be further increased.

  Further, instead of the accommodating portion 77 of the sensor element 6, a plurality of concave portions corresponding to the shape of the protruding portion 22 of the connection terminal 2 may be arranged in the rear end portion 67 in the circumferential direction. In this way, the rigidity at the rear end portion 67 of the sensor element 6 can be increased as compared with the case where the groove-shaped accommodation portion 77 as in the present embodiment is provided at the rear end portion 67 of the sensor element. In this case, when the terminal portion 21 is fitted, it is necessary to align the accommodating portion and the protruding portion 22 in the circumferential direction. However, if the number of the concave portions is increased, the protruding portion 22 is fitted to one of them. And positioning can be performed easily.

2 is a longitudinal sectional view showing the structure of the oxygen sensor 1. FIG. 3 is a perspective view of a sensor element 6. FIG. It is the perspective view which looked at the connecting terminal 2 before the assembly | attachment to the oxygen sensor 1 from the front, the left side, and the plane. FIG. 3 is a development view of the connection terminal 2. It is a front view of the connection terminal 2 before the assembly to the oxygen sensor 1. It is a left view of the connection terminal 2 before the assembly to the oxygen sensor 1. It is sectional drawing of the terminal part 21 seen from the arrow direction in the dashed-dotted line AA of FIG. It is sectional drawing of the terminal part 21 seen from the arrow direction in the dashed-dotted line BB of FIG. It is a figure which shows the process in which the terminal part 21 of the connecting terminal 2 is engage | inserted in the rear-end part 67 of the sensor element 6. FIG. It is a figure which shows the process in which the terminal part 21 of the connecting terminal 2 is engage | inserted in the rear-end part 67 of the sensor element 6. FIG. It is a figure which shows the process in which the terminal part 21 of the connecting terminal 2 is engage | inserted in the rear-end part 67 of the sensor element 6. FIG. It is a figure which shows the process in which the terminal part 21 of the connecting terminal 2 is engage | inserted in the rear-end part 67 of the sensor element 6. FIG. It is a partial cross section figure of the terminal part 321 of the connecting terminal 302 as a modification. It is a partial cross section figure of the terminal part 421 of the connecting terminal 402 as a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Oxygen sensor 2 Connection terminal 6 Sensor element 21 Terminal part 22 Projection part 64 Detection part 66 Tip part 67 Rear end part 69 Outer peripheral surface 75 Electrode part 77 Storage part 215 Front end 217 Outer peripheral surface 218 Inner peripheral surface 219 Contact part 225 One end part 226 Other end portion 227 Intermediate portion 402 Connection terminal 419 Contact portion 423 Contact portion

Claims (7)

It has a bottomed cylindrical shape extending in the axial direction and closed at the front end side, and has a detection unit for detecting the detected object at the front end side, and the detection unit on the outer peripheral surface of its own rear end side A sensor element having an electrode portion for taking out the output of
A cylindrical terminal portion that covers the circumferential direction of the rear end side of the sensor element, and a connection terminal that outputs a detection signal from the detection portion to an external circuit, and
In the sensor in which the terminal portion is fitted into the sensor element while being expanded radially outward by the sensor element, and the terminal portion and the electrode portion are in contact with each other,
The sensor element is provided with a receiving portion recessed from the outer peripheral surface on the rear end side in the axial direction from the electrode portion,
In the terminal portion of the connection terminal,
A projecting portion that is housed in the housing portion while projecting inward from an inner peripheral surface;
A sensor, comprising: a contact portion formed on a tip side of the projecting portion of the terminal portion and in contact with the electrode portion.   The sensor according to claim 1, wherein the protruding portion of the connection terminal is provided at a plurality of sites.   The terminal portion has a C-shape in a cross section perpendicular to the axial direction, and the protrusions are provided at least at one end and the other end in the circumferential direction on the inner peripheral surface of the terminal portion. The sensor according to claim 2.   The sensor according to claim 3, wherein the protruding portion of the connection terminal is provided at an intermediate portion in the circumferential direction on the inner peripheral surface of the terminal portion when viewed from the axial direction.   5. The protruding portion of the connection terminal, wherein the outer peripheral surface of the terminal portion is pushed in the thickness direction to protrude the inner peripheral surface of the terminal portion. Sensor.   The accommodating portion of the sensor element is formed in a groove shape that goes around the outer peripheral surface of the sensor element in the circumferential direction, and the electrode portion is formed in a belt shape that goes around the outer peripheral surface in the circumferential direction. The sensor according to any one of claims 1 to 5.   The sensor according to claim 1, wherein a contact portion protruding inward is formed at the contact portion of the connection terminal.

Images