JP2014052254A - Gas sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of connection between a connection terminal and an outside electrode, by enhancing force with which the connection terminal grips a sensor element.SOLUTION: A gas sensor comprises: a sensor element that includes a solid electrolyte body formed in a bottomed cylindrical shape extending a bottom portion to a tip end side and made from a solid electrolyte, an outside electrode provided on an outer surface of the tip end portion of the solid electrolyte, and an outer lead portion provided so as to extend from the outside electrode to a rear end portion side on the outer surface of the solid electrolyte body; and a connection terminal that includes a lead wire for taking out a detection signal of the sensor element, and a cylindrical portion capable of elastically deforming in a radial direction and fitted in a rear end portion outer surface of the sensor element to contact with the outer lead portion, and electrically connects the outside electrode and the lead wire through the cylindrical portion. The cylindrical portion has a stiffness applying portion provided so as to extend in a circumferential direction of the cylindrical portion, and enhancing reaction force generated when the cylindrical portion is expanded to the outside in the radial direction, by improving the stiffness of the cylindrical portion.

Description

  The present invention relates to a gas sensor.

  As a gas sensor for detecting a specific gas component in a gas to be measured, a sensor having a sensor element whose electrical characteristics change according to the concentration of the specific gas component in the gas to be measured has been known. As such a sensor element, for example, a bottomed cylindrical solid electrolyte having a closed tip, an inner electrode (reference electrode) formed on the inner surface of a cylindrical hole of the solid electrolyte, and an outer surface of the solid electrolyte A sensor element is known that includes a formed outer electrode (detection electrode) and a lead portion formed to extend from the outer electrode to the rear end side on the outer surface of the solid electrolyte. When such a sensor element is incorporated in a gas sensor, for example, a connection terminal fitting connected to a lead wire for taking out a detection signal from the gas sensor is prepared, and the connection terminal fitting is fitted into the sensor element. . For example, in order to connect the lead wire and the outer electrode of the sensor element, it is only necessary to fit the connection terminal fitting to the outer surface of the rear end portion of the sensor element, whereby the lead is connected via the connection terminal fitting and the lead portion. A line and an outer electrode are electrically connected (for example, refer patent document 1).

  In the connection terminal fitting as described above, generally, a cylindrical portion that is elastically deformable in the radial direction is provided at a tip portion thereof. By fitting this cylindrical part on the outer surface of the rear end of the sensor element, the inner surface of the cylindrical part is brought into contact with the lead part on the outer surface of the rear end of the sensor element.

JP 2007-278806 A

  However, when the conventionally known configuration described above is employed, there is a case where it is not possible to sufficiently meet the demand for reducing the axial length of the sensor element. Reduction of the axial length of the sensor element is desired, for example, in order to reduce the size of the sensor element. Further, shortening the length of the sensor element in the axial direction is desired for reducing the wiring material for forming the wiring provided on the sensor element. That is, if the length of the sensor element in the axial direction is shortened, the wiring material (noble metal) used for the electrodes and leads can be reduced. In particular, when the rear end portion of the sensor element is shortened, the axial length of the lead portion formed on the rear end portion side can be shortened.

  By the way, the gas sensor generally includes a metal shell that surrounds the sensor element and projects the rear end of the sensor element. In the sensor element, when the length of the sensor element in the axial direction is shortened by shortening the length of the rear end portion, the length of the rear end portion of the sensor element protruding from the metal shell is shortened. Correspondingly, the axial length of the cylindrical portion of the connection terminal fitting is also shortened. Thus, when the length of the rear end side of the sensor element is shortened, the length in the axial direction where the rear end of the sensor element and the cylindrical portion of the connection terminal fitting overlap when the sensor element and the connection terminal fitting are connected. In some cases, it was not possible to secure a sufficient amount. If the axial length where the rear end of the sensor element overlaps the cylindrical part of the connection terminal fitting cannot be secured sufficiently, the reliability of the electrical connection between the sensor element and the connection terminal fitting may be insufficient. There is. In other words, the force with which the cylindrical portion of the connection terminal fitting grips the rear end of the sensor element is weakened by the reduction in the axial length of the cylindrical portion of the connection terminal fitting. There is a possibility that the reliability of the electrical connection with will be insufficient.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects.

(1) According to one aspect of the present invention, a solid electrolyte body formed of a solid electrolyte formed in a bottomed cylindrical shape with a bottom portion extending toward the tip end side in the axial direction, and an outer surface of the tip end portion of the solid electrolyte body An outer electrode provided on the outer surface of the solid electrolyte body, and an external lead provided on the outer surface of the solid electrolyte body extending from the outer electrode toward the rear end, and a detection signal of the sensor element. A lead wire for taking out, and a cylindrical portion that is elastically deformable in a radial direction and is fitted on an outer surface of a rear end portion of the sensor element and is in contact with the external lead portion; A gas sensor is provided that includes a connection terminal that electrically connects an electrode and the lead wire. In this gas sensor, the cylindrical portion is provided so as to extend in the circumferential direction of the cylindrical portion, and is generated when the cylindrical portion is expanded radially outward by increasing the rigidity of the cylindrical portion. Provided with a rigidity-imparting section that enhances the reaction force.
According to the gas sensor of this aspect, when the cylindrical portion is fitted on the outer surface of the rear end portion of the sensor element, the reaction force against the deformation of the cylindrical portion can be increased, so the cylindrical portion grips the sensor element. You can strengthen the power to do. Therefore, the reliability of the connection between the connection terminal and the outer electrode via the external lead portion can be enhanced. In addition, by increasing the force with which the cylindrical portion grips the sensor element in this way, even if the axial length in which the cylindrical portion and the sensor element overlap is further shortened, the connection between the connection terminal and the external lead portion is reduced. Can be secured. Therefore, it is possible to reduce the overall length of the gas sensor by reducing the length of the cylindrical portion in the axial direction.

(2) In the gas sensor of the above aspect, the cylindrical portion has a gap provided in an axial direction, and is elastically deformable in a radial direction by changing a width of the gap, and the rigidity is given. The section is provided across a center line extending in the axial direction through the center in the circumferential direction of the cylindrical section excluding the gap in a cross section obtained by cutting the cylindrical section in a direction orthogonal to the axial direction. Also good.
According to the gas sensor of this aspect, the effect of enhancing the force with which the tubular portion grips the sensor element can be enhanced by providing the rigidity imparting portion across the center line of the tubular portion.

(3) In the gas sensor of the above aspect, the rigidity imparting portion may be a striking portion formed so as to protrude toward one surface side of the cylindrical portion.
According to the gas sensor of such a form, the force with which the cylindrical portion grips the sensor element can be enhanced by the projecting portion formed so as to protrude toward one surface side of the cylindrical portion. Moreover, the structure of a rigidity provision part can be simplified by forming in this way.

(4) The gas sensor according to the above aspect further includes a metal shell that surrounds the sensor element, and the projecting portion is formed so as to protrude outward in the radial direction of the cylindrical portion without contacting the metal shell. It is good as well.
According to the gas sensor of such a form, the force by which the tubular portion grips the sensor element can be enhanced by the striking portion protruding outward in the radial direction of the tubular portion. At this time, short-circuiting does not occur in the gas sensor by providing a projecting portion that projects outward in the radial direction of the cylindrical portion.

(5) In the gas sensor of the above aspect, the projecting portion may protrude inward in the radial direction of the cylindrical portion and contact the external lead portion.
According to the gas sensor of such a form, the force by which the tubular portion grips the sensor element can be enhanced by the projecting portion that protrudes inward in the radial direction of the tubular portion. In addition, when the projecting portion protruding inward in the radial direction of the cylindrical portion is in contact with the external lead portion, it is possible to improve the reliability of electrical connection between the connection terminal and the outer electrode.

(6) In the gas sensor of the above aspect, the rigidity imparting portion may be a reinforcing portion fixed on at least one surface of the cylindrical portion.
According to the gas sensor of such a form, the force with which the cylindrical portion grips the sensor element can be enhanced by the reinforcing portion fixed on at least one surface of the cylindrical portion.

  The present invention can be realized in various forms other than those described above. For example, the present invention can be realized in a form such as a gas sensor manufacturing method.

It is sectional drawing showing the structure of a gas sensor. It is a perspective view showing the external appearance of a sensor element. It is a perspective view showing the appearance of the 2nd connecting terminal. It is a top view showing the schematic shape of the plate-shaped member for forming a 2nd connecting terminal. It is a cross-sectional schematic diagram showing a mode that the 2nd connecting terminal was engage | inserted in the sensor element. It is a perspective view showing the outline of the appearance of the 1st connecting terminal. It is explanatory drawing which shows the outline | summary of an assembly of a gas sensor. It is a cross-sectional schematic diagram showing a mode that the 2nd connecting terminal was engage | inserted in the sensor element. It is a perspective view showing the appearance of the 2nd connecting terminal.

A. First embodiment:
FIG. 1 is a sectional view showing the configuration of a gas sensor 100 as a first embodiment according to the present invention. As shown in FIG. 1, the gas sensor 100 has an elongated shape that extends along the axis O. In the following description, the lower side in FIG. 1 in the direction of the axis O is referred to as the front end side, and the upper side in FIG. 1 is referred to as the rear end side. The gas sensor 100 of the present embodiment is an oxygen concentration sensor, and can be used, for example, to detect the oxygen concentration in the exhaust gas of an automobile.

  The gas sensor 100 includes a sensor element 10, a metal shell (housing) 20, an outer cylinder 40, and a structure (electrode and wiring connected to the electrode) related to routing of the internal wiring of the gas sensor as main components. ing. The sensor element 10 constitutes an oxygen concentration cell in which a pair of electrodes are laminated on both surfaces of an oxide ion conductive (oxygen ion conductive) solid electrolyte body, and outputs a detected value corresponding to the oxygen partial pressure. It is a sensor element. Specifically, the sensor element 10 includes a bottomed cylindrical solid electrolyte body 11 whose outer diameter is tapered toward the tip, and inner electrodes formed on the inner surface and the outer surface of the solid electrolyte body 11, respectively. (Reference electrode) 10a and outer electrode (detection electrode) 10b. Then, the inner space of the sensor element 10 is set as a reference gas atmosphere, and the gas to be detected is brought into contact with the outer surface of the sensor element 10 to detect the gas. From the rear end of the gas sensor 100, two lead wires 60 for taking out the detection signal of the sensor element 10 are drawn out.

  FIG. 2 is a perspective view showing the appearance of the sensor element 10. The sensor element 10 is formed with a flange 12 protruding (protruding) in the outer peripheral direction in the middle of the axis O direction. A bottomed portion 13 that is gradually reduced in diameter toward the distal end side and closed at the distal end portion is formed on the distal end side of the flange portion 12. In the present embodiment, the outer electrode 10 b is formed so as to cover a part of the outer surface of the bottomed portion 13. Further, the outer electrode 10b is covered with an electrode protective layer 14 for protecting the outer electrode 10b.

  In the sensor element 10, a substantially hollow cylindrical base portion 17 having a substantially constant outer diameter and an opening at the rear end is formed on the rear end side of the flange portion 12. In addition, external leads 10 c that are electrically connected to the outer electrode 10 b are provided on the outer surfaces of the flange portion 12 and the base portion 17. The external lead portion 10c of this embodiment is a vertical lead portion that extends linearly in the direction of the axis O from the rear end of the outer electrode 10b via the flange portion 12 to the rear end side of the flange portion 12. 15 and a ring lead portion 16 provided at the rear end portion of the vertical lead portion 15. The ring lead portion 16 extends to a part of the outer surface of the sensor element 10 along the outer periphery of the sensor element 10 in the base portion 17. In addition, since the ring lead part 16 is a structure for making contact with the second connection terminal 80 described later, it may have a shape that can sufficiently contact the second connection terminal 80.

  As described above, the inner electrode 10 a is provided on the inner surface of the sensor element 10. A cylindrical hole 10d is formed inside the bottomed cylindrical solid electrolyte body 11 (see FIG. 1), and the inner electrode 10a is formed so as to cover the entire surface of the cylindrical hole 10d except for the vicinity of the rear end. ing.

The solid electrolyte body 11 included in the sensor element 10 can be composed of, for example, zirconium oxide (ZrO ₂ ) to which yttrium oxide (Y ₂ O ₃ ) is added, that is, yttria-stabilized zirconia. Alternatively, by other solid electrolyte such as stabilized zirconia to which an oxide selected from calcium oxide (CaO), magnesium oxide (MgO), cerium oxide (CeO ₂ ), aluminum oxide (Al ₂ O ₃ ) and the like is added. The sensor element 10 may be configured.

  The inner electrode 10a and the outer electrode 10b formed on the surface of the sensor element 10 are preferably formed of a noble metal or a noble metal alloy such as platinum (Pt) or a platinum alloy. The inner electrode 10a and the outer electrode 10b can be formed by a plating method such as electroless plating, for example. Further, when the solid electrolyte body 11 is manufactured by firing a molded body made of, for example, zirconia powder containing yttria, etc., the external lead portion 10c has a predetermined pattern using a noble metal paste on the outer surface of the molded body. The printing can be performed simultaneously with the firing of the molded body.

  Returning to FIG. 1, the sensor element 10 is assembled in the metal shell 20. The metal shell 20 is a metal member that is arranged so as to surround the middle part of the sensor element 10 in the axis O direction. On the inner surface of the metal shell 20, a step portion 20b whose inner diameter is reduced toward the distal end is provided. A packing 30 is disposed between the stepped portion 20b and the flange portion 12 of the sensor element 10. When the metal shell 20 and the sensor element 10 are assembled, the sensor element 10 is inserted into the metal shell 20 from the rear end side of the metal shell 20. Then, the flange portion 12 of the sensor element 10 is indirectly brought into contact with the step portion 20 b by applying the flange portion 12 to the packing 30.

  Further, a seal portion 31 filled with talc powder is disposed in the gap between the sensor element 10 and the flange 12 of the sensor element 10 in the gap between the sensor element 10 and the metal shell 20. The gap is sealed. A cylindrical insulating member (ceramic sleeve) 32 is disposed on the rear end side of the seal portion 31. Furthermore, a metal ring (stainless flat washer) 33 is disposed on the rear end side of the insulating member 32. On the rear end side of the metal ring 33, the rear end portion of the metal shell 20 is bent inward to form a crimped portion 20a. By forming the crimped portion 20a at the rear end portion of the metal shell 20, the insulating member 32 is pressed against the distal end side to crush the seal portion 31, and the insulating member 32 and the seal portion 31 are fixed by crimping. The gap between the sensor element 10 and the metal shell 20 is sealed.

  In the vicinity of the center of the metal shell 20, a polygonal flange portion 20c formed in a shape protruding radially outward is provided in order to engage a hexagon wrench or the like. A male screw portion 20d is formed on the outer surface between the flange portion 20c and the tip portion 20f that is the tip portion of the metal shell 20. The male screw portion 20d of the metal shell 20 is attached to, for example, a screw hole of an exhaust pipe of an automobile, and the tip of the sensor element 10 is exposed in the exhaust pipe, whereby oxygen in a gas to be detected (exhaust gas) using the gas sensor 100 is exposed. The concentration can be detected. In the gas sensor 100, a gasket for preventing gas escape when the gas sensor 100 is attached to the exhaust pipe is further fitted into the step between the front end surface of the flange portion 20 c and the rear end of the male screw portion 20 d (FIG. Not shown).

  A cylindrical protector 62 made of metal (such as stainless steel) is fixed to the distal end portion 20 f of the metallic shell 20, and the distal end of the sensor element 10 protruding from the metallic shell 20 is covered with the protector 62. The protector 62 has a plurality of holes for taking exhaust gas into the protector 62.

  On the other hand, a metallic outer tube 40 is joined to the rear end of the metal shell 20 to cover the rear end of the sensor element 10. The outer cylinder 40 can be formed of stainless steel such as SUS430, SUS304, SUS304L, SUS310S, SUS316, SUS316L, or the like. The outer cylinder 40 has a front end portion 40a connected to the metal shell 20, and a rear end portion 40b having a diameter smaller than that of the front end portion 40a. A stepped portion 43 is provided between the front end portion 40a and the rear end portion 40b. Is provided.

  On the inner side of the distal end portion 40a of the outer cylinder 40, a substantially cylindrical and insulating separator 34 with a step is disposed. The separator 34 is formed with two insertion holes 34 a and 34 b that penetrate the separator 34 in the direction of the axis O. The plate-like base portion 71 of the first connection terminal 70 and the plate-like base portion 81 of the second connection terminal 80 are inserted through these insertion holes 34a and 34b, respectively. Here, the first connection terminal 70 and the second connection terminal 80 are members for connecting the inner electrode 10a or the outer electrode 10b and the lead wire 60, respectively. Connection end portions 72 and 82 are formed at the rear ends of the respective plate-like base portions 71 and 81, and different lead wires 60 are caulked and connected to the connection end portions 72 and 82, respectively. The first connection terminal 70 and the second connection terminal 80 can be formed of a conductive material, for example, a metal material selected from stainless steel, nickel alloy, copper, cobalt alloy, and the like. It is desirable to use a metal material that exhibits sufficient corrosion resistance in the environment in which the gas sensor 100 is used. The second connection terminal 80 corresponds to a “connection terminal” in the claims.

  The separator 34 has the rear end surface of the separator 34 in contact with the stepped portion 43 of the outer cylinder 40, and the front end surface of the separator 34 is in contact with the holding metal fitting 35 disposed on the front end side of the separator 34. It is held in the tube 40. The holding metal fitting 35 is disposed on the front end side of the separator 34 and is fixed in the outer cylinder 40 by crimping the front end portion 40 a of the outer cylinder 40.

  FIG. 3 is a perspective view showing the appearance of the second connection terminal 80. As described above, the second connection terminal 80 includes the connection end portion 82 to which the lead wire 60 is connected and the plate-like base portion 81 disposed in the insertion hole 34 b of the separator 34. A support arm 84 is formed at the center of the plate-like base 81 by forming a cut in a substantially U-shape and bending the inner part thereof toward the outer peripheral side. The support arm 84 supports the plate-like base 81 in the insertion hole 34b of the separator 34 so that the plate-like base 81 is substantially parallel to the axis O direction.

  Further, in the second connection terminal 80, a cylindrical portion 83 is provided on the tip side of the plate-like base portion 81. The tubular portion 83 is fitted into the outer surface of the rear end portion of the sensor element 10, thereby contacting the ring lead portion 16 and being electrically connected to the outer electrode 10 b. More specifically, the cylindrical portion 83 is formed in a substantially hollow cylindrical shape obtained by bending a substantially rectangular plate, and has a gap (slit) 85 parallel to the direction of the axis O. The cylindrical portion 83 can be elastically deformed in the radial direction by expanding and contracting the width of the gap 85. The inner diameter of the cylindrical portion 83 when not fitted into the outer surface of the rear end portion of the sensor element 10 is smaller than the outer diameter of the rear end portion of the sensor element 10. Then, by expanding the gap 85, the cylindrical portion 83 can be fitted into the sensor element 10.

  FIG. 4 is a plan view illustrating a schematic shape of a plate-like member for forming the second connection terminal 80. The second connection terminal 80 can be manufactured, for example, by punching a flat member to form a plate member having the shape shown in FIG. 4 and bending the plate member. As shown in FIG. 4, in the second connection terminal 80 of the present embodiment, the axis passes through the center of the circumferential length of the tubular portion 83 (the circumferential center of the tubular portion 83 excluding the gap 85). A line parallel to O is a center line C. That is, the cylindrical portion 83 has a length extending in the clockwise direction around the center line C (length R extending in the right direction perpendicular to the center line C) and a length extending in the counterclockwise direction. (Length L extending in the left direction) is substantially equal. In such a second connection terminal 80, the connection end portion 82 is provided so as to extend from the position of the center line C in the tubular portion 83 toward the rear end portion in parallel to the axis O. The position where the connection end portion 82 is provided may be a position different from the position overlapping the center line C.

  As shown in FIGS. 3 and 4, the tubular portion 83 is provided with a projecting portion 87 that is convex outward in the radial direction. The projecting portion 87 is provided over a region extending from side to side across the center line C, and is provided so as to extend in a direction perpendicular to the center line C. That is, the launch portion 87 is provided in a range straddling the center line C in a cross section obtained by cutting the tubular portion 83 in a direction orthogonal to the axis O direction. Such a launch portion 87 can be formed, for example, by pressing a plate-like member shown in FIG. 4 extends to substantially the same length on both sides in the circumferential direction around the center line C, but the length extending from the center line C to each side in the circumferential direction is as follows. , May be different from each other.

  FIG. 5 is a schematic cross-sectional view illustrating a state in which the second connection terminal 80 is fitted into the rear end portion of the sensor element 10. The position of the cross section shown in FIG. 5A in the second connection terminal 80 is shown as a cross section AA in FIG. Moreover, the position in the 2nd connection terminal 80 of the cross section shown to FIG. 5 (B) is shown as a BB cross section in FIG. That is, FIG. 5A shows a state of a cross section on the tip side from the launching portion 87, and FIG. 5B shows a state of a cross section passing through the launching portion 87. In FIG. 5, the position of the center line C is shown on the assumption that the center line C exists on the surface of the plate-like member before pressing shown in FIG. 4 (surface on the side in contact with the sensor element 10).

  When the cylindrical portion 83 of the second connection terminal 80 is fitted into the rear end portion of the sensor element 10 and the cylindrical portion 83 is elastically deformed in the radial direction, the width of the gap 85 is widened, so that the cylindrical portion 83 is expanded. Expands in the direction of the white arrow shown in FIG. That is, strictly speaking, the cylindrical portion 83 does not spread uniformly in all directions toward the radially outer side, but spreads in an elliptical shape with the center line C as a fulcrum. Therefore, the cylindrical portion 83 mainly contacts the outer surface of the sensor element 10 at a total of three locations including a region including the center line C and two regions adjacent to the gap 85. 4 and 5, a region including the center line C is shown as a region α surrounded by a broken line. A region adjacent to the gap 85 is surrounded by a broken line as a region β and a region γ. Depending on the degree of deformation of the tubular portion 83, the regions β and γ may hardly be expanded in the circumferential direction of the tubular portion 83 and may be sides (linear) forming the gap 85. Further, as shown in FIG. 5B, the region where the projecting portion 87 is formed on the inner surface of the cylindrical portion 83 is separated from the outer surface of the sensor element 10.

  Note that, depending on the deformation state of the tubular portion 83 when the tubular portion 83 is fitted into the rear end portion of the sensor element 10, the tubular portion 83 and the rear end portion of the sensor element 10 have a transverse cross section (axis line). In a cross section perpendicular to O), contact may be made at four points instead of three points. That is, in the cross section, instead of making contact at a portion including the center line C, contact may be made at two locations near the center line C with the center line C in between. Also in this case, the two places sandwiching the above-described center line C are collectively referred to as a region α.

  If the projecting portion 87 is provided in the cylindrical portion 83 as in the second connection terminal 80 of the present embodiment, the rigidity of the cylindrical portion 83 is increased and the cylindrical portion 83 is difficult to elastically deform in the radial direction. That is, when the cylindrical portion 83 is elastically deformed in the radial direction, a reaction force that opposes the force to be deformed in the direction of the white arrow shown in FIG. Therefore, the launching portion 87 can function as a rigidity imparting portion that provides rigidity that suppresses the radial deformation of the cylindrical portion 83.

  Returning to FIG. 3, a plurality of flare pieces 86 project from the tip of the cylindrical portion 83 along the circumference forming the tip of the cylindrical portion 83. Each flare piece 86 is bent toward the outer peripheral side at the connection portion with the tip of the cylindrical portion 83, and the entire plurality of flare pieces 86 spread radially from the tip of the cylindrical portion 83. Therefore, assuming a circle in contact with the inner surfaces of the plurality of flare pieces 86, the diameter of the contacting circle becomes larger at the tip of the flare piece 86. That is, the inner diameters of the plurality of flare pieces are larger toward the front end side, and the inscribed circle at the front end of the flare piece 86 is larger than the outer diameter of the rear end of the sensor element 10. The plurality of flare pieces 86 have a structure for facilitating the operation of fitting the tubular portion 83 into the rear end portion of the sensor element 10, so that the flare pieces 86 may not be provided. is there. The operation of fitting the tubular portion 83 into the sensor element 10 will be described in detail later.

  FIG. 6 is a perspective view illustrating an outline of the appearance of the first connection terminal 70. As described above, the first connection terminal 70 includes the connection end 72 to which the lead wire 60 is connected and the plate-like base 71 disposed in the insertion hole 34 a of the separator 34. A support arm 74 is formed at the center of the plate-like base 71 by forming a cut in a substantially U-shape and bending the inner part thereof toward the outer periphery. The support arm 74 supports the plate-like base 71 in the insertion hole 34a of the separator 34 so that the plate-like base 71 is substantially parallel to the axis O direction.

  Further, in the first connection terminal 70, a cylindrical portion 73 is provided on the distal end side with respect to the plate-like base portion 71. The cylindrical portion 73 has a gap (slit) 75 parallel to the direction of the axis O and is elastically deformable in the radial direction, and is a cylinder when the sensor element 10 is not fitted into the cylindrical hole 10d. The inner diameter of the shape portion 73 is larger than the inner diameter of the cylindrical hole 10 d of the sensor element 10. Therefore, the cylindrical part 73 and the inner electrode 10a can be brought into contact by inserting into the cylindrical hole 10d of the sensor element 10 while reducing the diameter of the cylindrical part 73.

  Further, a plurality of (two in FIG. 3) plate-like extending pieces 76 are provided at the tip of the cylindrical portion 73 so as to protrude further toward the tip side. The plurality of extending pieces 76 constitute an extending portion 79 as a whole. Such a structure related to the extending portion 79 is a structure for facilitating the operation of fitting the distal end side of the first connection terminal 70 into the cylindrical hole 10 d of the sensor element 10. The operation of fitting the first connection terminal 70 into the sensor element 10 will be described in detail later.

  Returning to FIG. 1, a substantially columnar grommet 36 is inserted and fixed by caulking inside the rear end portion 40 b of the outer cylinder 40 of the gas sensor 100. The grommet 36 is formed with two insertion holes penetrating the grommet 36 in the direction of the axis O, and the lead wire 60 is drawn out from each of the two insertion holes. The rear end side of the grommet 36 is expanded in a flange shape. The grommet 36 is positioned by inserting the grommet 36 from the rear end of the outer cylinder 40 into the outer cylinder 40 and bringing the above-mentioned enlarged diameter portion into contact with the rear end of the outer cylinder 40. The grommet 36 can be formed of a rubber material such as silicon rubber or fluorine rubber, for example.

  Further, on the side surface of the rear end portion 40b of the outer cylinder 40, four first vent holes 41 (only three are shown in FIG. 1) are arranged at equal intervals in the circumferential direction at a position closer to the tip side than the grommet 36. It is open. An annular air-permeable filter 37 is covered on the radially outer side of the rear end portion 40b of the outer cylinder 40 so as to cover the first ventilation hole 41. Further, the filter 37 is made of a metal cylinder from the radially outer side. A protective outer cylinder 38 is enclosed. The protective outer cylinder 38 can be formed of stainless steel such as SUS430, SUS304, SUS304L, SUS310S, SUS316, SUS316L, or the like. Four second vent holes 39 (only two are shown in FIG. 1) are opened at equal intervals in the circumferential direction on the side surface of the protective outer cylinder 38 so that outside air can be introduced into the outer cylinder 40 through the filter 37. It has become. The filter 37 is held between the outer cylinder 40 and the protective outer cylinder 38 by crimping the outer cylinder 40 and the protective outer cylinder 38 at the front end side and the rear end side of the second vent hole 39. The filter 37 can be constituted by a porous structure of a water repellent resin such as a fluorine-based resin, and has a water repellency, so that the reference gas (in the internal space of the sensor element 10 does not pass through outside water). Air) can be introduced.

  The protective outer cylinder 38 is bent radially inward so that the rear end portion is provided on the rear end surface of the grommet 36, and an opening 63 is formed in the center of the rear end portion. 60 is pulled out. Further, the rear end side of the protective outer cylinder 38 is caulked and fixed to a caulking portion provided at the rear end portion 40 b of the outer cylinder 40. That is, the grommet 36 is disposed in the outer cylinder 40 by simultaneously caulking both the protective outer cylinder 38 and the outer cylinder 40.

  FIG. 7 is an explanatory diagram showing an outline of assembly of the gas sensor 100. When assembling the gas sensor 100, the rear end side assembly A having the rear end side structure of the gas sensor 100 and the front end side assembly B having the front end side structure are assembled, and the assemblies A and B are assembled. In FIG. 7, the assembling operation for placing the assembly A on the rear end of the assembly B is shown by a cross-sectional view.

  When manufacturing the gas sensor 100, first, the front end side assembly B is assembled. Specifically, the sensor element 10 is inserted into the metal shell 20 from the rear end side of the metal shell 20, and the sensor element 10 is disposed on the packing 30 disposed in the metal shell 20. Thereby, the collar part 12 of the sensor element 10 is made to contact | abut indirectly to the step part 20b. Thereafter, the cylindrical seal portion 31 is disposed in the gap between the metal shell 20 and the sensor element 10, and the insulating member 32 and the metal ring 33 are sequentially disposed on the seal portion 31. Then, by bending the rear end side of the metal shell 20 inward to form the crimped portion 20a, the insulating member 32 is pressed against the distal end side to crush the seal portion 31, and the insulating member 32 and the seal portion 31 are It is fixed by crimping. In this way, assembly B is produced.

  On the other hand, the rear end side assembly A is assembled. That is, the separator 34 assembled with the first connection terminal 70 and the second connection terminal 80 is arranged together with the grommet 36 in the outer cylinder 40 to assemble the assembly A. Specifically, the first connection terminal 70 and the second connection terminal 80 connected to the lead wire 60 are inserted into the insertion holes 34 a and 34 b of the separator 34, and then the separator 34 is inserted into the step portion 43 of the outer cylinder 40. Abut. Thereafter, the holding metal fitting 35 is inserted into the gap between the separator 34 and the outer cylinder 40, and the distal end portion 40 a of the outer cylinder 40 is caulked to fix the holding metal fitting 35. Further, the grommet 36 is inserted from the rear end of the outer cylinder 40, and the filter 37 and the protective outer cylinder 38 are disposed at the rear end portion 40b of the outer cylinder 40, respectively, and the filter 37 and the grommet 36 are fixed by crimping. Assembly A is made.

  Then, the gas sensor 100 is assembled by aligning the axes of the assembly A and the assembly B and covering the front end of the outer cylinder 40 of the assembly A over the rear end of the metal shell 20 of the assembly B.

  As shown in FIG. 7, in the rear end side assembly A, the tip end portion of the extending piece 76 of the first connection terminal 70 protrudes from the tip end of the outer cylinder 40 to the tip end side. Here, the cylindrical portion 73 of the first connection terminal 70 is located on the rear end side with respect to the front end of the outer cylinder 40 and is accommodated in the rear end side assembly A. In the front end side assembly B, the rear end portion of the sensor element 10 protrudes from the rear end of the metal shell 20. When assembling the assembly A and the assembly B, first, the extension piece 76 protruding from the assembly A is inserted into the cylindrical hole 10d formed in the sensor element 10 of the assembly B, and the distal end portion of the outer cylinder 40 is inserted. Is put on the rear end of the metal shell 20.

  As described above, when the front end portion of the outer cylinder 40 is put on the rear end portion of the metal shell 20, the assembly A, B protrudes from the front end of the cylindrical portion 83 of the second connection terminal 80 provided in the assembly A. The provided flare piece 86 contacts the rear end of the sensor element 10. Thereafter, when the assembly A and the assembly B are further fitted, the rear end of the sensor element 10 is guided into the cylindrical portion 83 by the inner surface of each flare piece 86 and pushes the cylindrical portion 83 from the inside. spread. At this time, the diameter of the cylindrical portion 83 is increased by widening the gap 85 (see FIG. 3). As described above, when the tubular portion 83 is fitted into the rear end portion of the sensor element 10, the inner surface of the tubular portion 83 is in contact with the ring lead portion 16 (see FIG. 2), so that the second connection terminal 80 and the outside are connected. The electrode 10b is electrically connected.

  As described above, when the fitting of the assembly A and the assembly B is finished, the outer surface of the cylindrical portion 73 of the first connection terminal 70 is in contact with the inner electrode 10a. Further, the inner surface of the cylindrical portion 83 of the second connection terminal 80 and the ring lead portion 16 of the sensor element 10 come into contact with each other, and the tip of each flare piece 86 is separated from the rear end of the metal shell 20 while It reaches near the rear end of the metal fitting 20. In order to make the positional relationship between the first connection terminal 70 or the second connection terminal 80 and the sensor element 10 as desired, the sensor element 10, the first connection terminal 70, and the second connection terminal in each assembly. The assembly position of 80 and the assembly position between the assembly A and the assembly B may be set in advance according to the desired degree of overlap.

  After assembling the assemblies A and B so that the outer cylinder 40 covers up to a predetermined position of the metal shell 20, the outer peripheral surface of the front end portion of the outer cylinder 40 is subjected to the rear end portion of the metal shell 20 by laser welding or the like. By connecting to the gas sensor 100, the gas sensor 100 is obtained.

  According to the gas sensor 100 of the present embodiment configured as described above, the cylindrical portion 83 of the second connection terminal 80 is provided with the launching portion 87 as the rigidity imparting portion. When the element 10 is fitted into the rear end portion, the reaction force against the deformation of the tubular portion 83 can be increased. As a result, the force with which the cylindrical portion 83 grips the rear end portion of the sensor element 10 can be increased. Specifically, the force applied to the sensor element 10 in the regions α, β, and γ (see FIGS. 4 and 5) described above in the cylindrical portion 83 can be increased. Therefore, the reliability of the connection between the second connection terminal 80 and the outer electrode 10b via the ring lead portion 16 can be enhanced. In addition, since the cylindrical portion 83 can increase the force with which the sensor element 10 is gripped in this way, even if the length in the direction of the axis O where the cylindrical portion 83 and the sensor element 10 overlap is further shortened, It is possible to ensure the connection between the connection terminal 80 and the ring lead portion 16. Therefore, the length of the cylindrical portion 83 in the axis O direction (the length W shown in FIG. 4) can be further shortened, and the length of the second connection terminal 80 in the axis direction can be shortened to reduce the gas sensor 100. The overall size can be reduced. Furthermore, according to the present embodiment, since the punched portion 87 is formed by press-molding the cylindrical portion 83, there is no increase in the number of parts associated with providing the rigidity imparting portion, and the structure of the gas sensor 100 is complicated. And complexity of the manufacturing process can be suppressed.

  In order for the tubular portion 83 to stably hold the sensor element 10, the projecting portion 87 is formed in the tubular portion 83 when the tubular portion 83 is fitted into the rear end portion of the sensor element 10. It is desirable that at least a part of the region overlaps the sensor element 10. Further, in order to ensure the contact between the tubular portion 83 and the ring lead portion 16 in the region α (see FIGS. 4 and 5), in the tubular portion 83, the axis O from the tip of the tubular portion 83 to the launch portion 87. It is desirable to make the direction distance longer.

B. Second embodiment:
In the first embodiment, the striking portion 87 that protrudes radially outward is provided as the rigidity imparting portion. However, a different configuration may be used. Hereinafter, as a second embodiment, a configuration in which a projecting portion that is convex radially inward is provided instead of the projecting portion 87 will be described.

  FIG. 8 is a schematic cross-sectional view showing a state in which the second connection terminal 180 is fitted into the rear end portion of the sensor element 10 as in FIG. The gas sensor of the second embodiment includes a second connection terminal 180 instead of the second connection terminal 80, and the tubular portion 183 of the second connection terminal 180 has a launch portion 187 instead of the launch portion 87. Except for this, the configuration is the same as that of the first embodiment. For this reason, the same reference numerals are assigned to portions common to the first embodiment, and detailed description thereof is omitted.

  The second connection terminal 180 has the same outer shape as that of the second connection terminal 80 of the first embodiment, and the projecting portion 187 is the second connection terminal 80 shown in FIG. Is provided at a position similar to the position of the launching portion 87. The position of the cross section shown in FIG. 8A is the same position as the cross section AA shown in FIG. Further, the position of the cross section shown in FIG. 8B is the same position as that of the BB cross section shown in FIG. That is, FIG. 8A shows the state of the cross section on the tip side of the launching portion 187, and FIG. 8B shows the state of the cross section passing through the launching portion 187.

  As shown in FIG. 8, the cylindrical portion 183 of the second embodiment also contacts the sensor element 10 in the region α including the center line C and the regions β and γ adjacent to the gap 85. However, in the second embodiment, the region α is a radially inner surface of the launch portion 187.

  Also in the second embodiment configured as described above, the same effect as that of the first embodiment can be obtained by providing the cylindrical portion 183 with the launching portion 187 as the rigidity imparting portion. Note that the height of the projecting portion 187 (height protruding from the inner surface of the tubular portion 183) and the length extending in the circumferential direction of the tubular portion 183 are the same as the sensor element 10 in the regions α, β, and γ. It may be set appropriately in consideration of the accuracy of contact.

C. Third embodiment:
In the first and second embodiments, the projecting portion is provided in the cylindrical portion as the rigidity imparting portion, but different configurations may be employed. Below, the structure which provides the reinforcement part as a rigidity provision part in a cylindrical part as 3rd Embodiment is demonstrated.

  FIG. 9 is a perspective view showing the appearance of the second connection terminal 280. The gas sensor according to the third embodiment includes a second connection terminal 280 instead of the second connection terminal 80, and a tubular portion 283 of the second connection terminal 280 is provided with a reinforcing portion 287 instead of the launch portion 87. Except for this, the configuration is the same as that of the first embodiment. For this reason, the same reference numerals are assigned to portions common to the first embodiment, and detailed description thereof is omitted.

  The second connection terminal 280 has the same outer shape as the second connection terminal 80 of the first embodiment, and the reinforcing portion 287 is the second connection terminal 280 shown in FIG. Is provided at the same position as the launching portion 87. The cylindrical portion 283 of the second connection terminal 280 is not subjected to pressing for providing a special unevenness, and a reinforcing member 287 is formed by fixing another member to the outer surface of the cylindrical portion 283. ing. The reinforcing portion 287 is not necessarily formed of a conductive material, but when the reinforcing portion 287 is formed of a metal member, another member for providing the reinforcing portion 287 can be fixed by welding, for example. it can. Further, the fixing of another member for providing the reinforcing portion 287 may be performed before or after the cylindrical portion 83 is formed by bending.

  Also in the third embodiment configured as described above, the same effect as that of the first embodiment can be obtained by providing the cylindrical portion 283 with the reinforcing portion 287 as the rigidity imparting portion.

  In FIG. 9, the reinforcing portion 287 that protrudes radially outward is provided in the cylindrical portion 283, but a reinforcing portion that protrudes radially inward may be provided instead of the reinforcing portion 287. In such a case, if the reinforcing portion is constituted by a conductive member such as metal, the electrical connection between the second connection terminal and the ring lead portion 16 is made via the reinforcing portion protruding radially inward. It becomes possible.

D. Variations:
D1. Modification 1:
In each of the first to third embodiments, the rigidity imparting portion is provided in the tubular portion so as to extend in the circumferential direction across the center line C, but may have a different configuration. The configuration of the rigidity imparting part only needs to increase the rigidity of the cylindrical part and increase the reaction force against the force that deforms the cylindrical part to expand its diameter. For example, the rigidity imparting portion may be provided at least in the vicinity of the center line C even if it does not necessarily straddle the center line C. Even if it is such a structure, the same effect which raises the rigidity of a cylindrical part and strengthens the force in which a cylindrical part hold | grips the rear-end part of the sensor element 10 can be acquired.

  As described above, the center line C is a line parallel to the axis O through the center of the circumferential length of the cylindrical portion (the circumferential center of the cylindrical portion excluding the gap 85). is there. Here, the center of the length in the circumferential direction of the cylindrical portion is the long side of the rectangular shape in the case where the cylindrical portion is formed by bending a substantially rectangular plate as in each embodiment. Overlapping the center. When both end portions forming the gap in the cylindrical portion are not linear, for example, in the case of an alternating jagged shape through the gap, the circumferential length of the portion excluding the jagged shape portion in the cylindrical portion is The center is the center of the circumferential length of the cylindrical portion. Further, as the shape of the cylindrical portion, the circumferential length of the cylindrical portion is longer than the outer periphery of the cross section of the rear end portion of the sensor element 10, that is, the second connection terminal is formed at the rear end portion of the sensor element. A shape in which the end of the cylindrical portion overlaps without forming the gap 85 and wraps around the rear end of the sensor element when fitted is conceivable. Even in such a case, the center of the circumferential length of the cylindrical portion that is longer than the outer periphery of the cross section of the rear end portion of the sensor element 10 is the center of the circumferential length of the cylindrical portion. Thus, the center line C indicates a position where the cylindrical portion serves as a fulcrum that generates a force for gripping the rear end portion of the sensor element 10.

D2. Modification 2:
Various modifications can be made to the length of the rigid portion extending in the circumferential direction of the cylindrical portion. In order to increase the gripping force enhancement effect by providing the cylindrical portion with a rigidity imparting portion to increase the rigidity of the cylindrical portion, the rigidity imparting portion extends as long as possible in the circumferential direction of the cylindrical portion. It is desirable to provide in. For example, the rigidity imparting portion may be provided so as to extend to one end portion that forms a boundary with the gap 85 in the cylindrical portion. Further, in the tubular portion, a rigidity imparting portion may be provided from one end of the tubular portion that forms a boundary with the gap 85 to the other end, that is, over the entire circumferential direction of the tubular portion.

D3. Modification 3:
In each of the first to third embodiments, the rigidity imparting portion is formed in a substantially rectangular shape and continuously formed as a whole. However, the rigidity is provided by a plurality of convex portions and reinforcing portions separated from each other. You may comprise a provision part. For example, the rigidity imparting portion may be configured by a plurality of line-shaped projecting portions (or reinforcing portions to which separate members are fixed) provided in parallel to each other along the circumferential direction.

D4. Modification 4:
In each of the first to third embodiments, the rigidity imparting portion has a shape that extends along the circumferential direction of the cylindrical portion, but it necessarily extends in a direction parallel to the circumferential direction (perpendicular to the axis O). do not have to. Any shape that is formed at least in the vicinity of the center line C and extends in the circumferential direction of the cylindrical portion as a whole may be used. For example, the rigidity imparting portion may be configured by one or a plurality of wavy line shaped launching portions (or reinforcing portions).

D5. Modification 5:
In each of the first to third embodiments, the gas sensor is an oxygen concentration sensor, but may have a different configuration. The present invention is a sensor having a concentration cell having a pair of electrodes laminated on both surfaces of a solid electrolyte having ion conductivity and generating an electromotive force due to a concentration difference (partial pressure difference) of a specific gas component on each electrode. The same effect can be obtained by applying.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the above effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 10 ... Sensor element 10a ... Inner electrode 10b ... Outer electrode 10c ... External lead part 10d ... Cylindrical hole 11 ... Solid electrolyte body 12 ... Gutter part 13 ... Bottom part 14 ... Electrode protective layer 15 ... Vertical lead part 16 ... Ring lead part 17 ... Base part 20 ... Metal fitting 20a ... Casting part 20b ... Step part 20c ... Hard part 20d ... Male thread part 20f ... Tip part 30 ... Packing 31 ... Seal part 32 ... Insulating member 33 ... Metal ring 34 ... Separators 34a, 34b ... Insertion hole 35 ... Holding metal fitting 36 ... Grommet 37 ... Filter 38 ... Protective outer cylinder 39 ... Second vent hole 40 ... Outer cylinder 40a ... Front end part 40b ... Rear end part 41 ... First vent hole 43 ... Step part 60 ... Lead wire 62 ... Protector 63 ... Opening 70 ... First connection terminal 71 ... Plate base 72 ... Connection end 73 ... Cylindrical part 74 ... Support arm 75 ... Gap 76 ... Extension piece 79 ... Extension part 80, 180, 280 ... 2nd connection terminal 81 ... Plate-like base part 82 ... Connection end part 83, 183, 283 ... Cylindrical part 84 ... Support arm 85 ... Gap 86 ... Flare piece 87, 187 ... Launching Part 100 ... Gas sensor 287 ... Reinforcing part

Claims (6)

A solid electrolyte body made of a solid electrolyte formed in a bottomed cylindrical shape with a bottom extending on the tip side in the axial direction, an outer electrode provided on the outer surface of the tip of the solid electrolyte body, and the solid electrolyte body An external lead portion extending from the outer electrode to the rear end side on the outer surface of the sensor element, and a sensor element comprising:
A lead wire for taking out a detection signal of the sensor element;
A cylindrical portion that is elastically deformable in a radial direction and is fitted on the outer surface of the rear end portion of the sensor element and is in contact with the external lead portion, and the outer electrode and the lead wire are connected via the cylindrical portion. A connection terminal for electrical connection;
In a gas sensor comprising:
The cylindrical portion is provided so as to extend in the circumferential direction of the cylindrical portion, and by increasing the rigidity of the cylindrical portion, the reaction force generated when the cylindrical portion is expanded radially outward is strengthened. A gas sensor comprising a rigidity imparting portion. The gas sensor according to claim 1,
The cylindrical portion has a gap provided in the axial direction, and is elastically deformable in the radial direction by changing the width of the gap.
The rigidity imparting portion is provided across a center line extending in the axial direction through the center in the circumferential direction of the cylindrical portion excluding the gap in a cross section obtained by cutting the cylindrical portion in a direction orthogonal to the axial direction. A gas sensor. The gas sensor according to claim 2,
The gas sensor according to claim 1, wherein the rigidity imparting portion is a striking portion formed so as to protrude toward one surface side of the cylindrical portion. The gas sensor according to claim 3,
Furthermore, a metal shell surrounding the sensor element is provided,
The gas sensor according to claim 1, wherein the projecting portion is formed so as to protrude outward in a radial direction of the cylindrical portion without contacting the metal shell. The gas sensor according to claim 3,
The gas sensor according to claim 1, wherein the projecting portion protrudes radially inward of the cylindrical portion and contacts the external lead portion. The gas sensor according to claim 2,
The gas sensor according to claim 1, wherein the rigidity imparting portion is a reinforcing portion fixed on at least one surface of the cylindrical portion.

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