JP2016045115A - Gas sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas sensor in which even when an inside terminal or an outside terminal is assembled while the axial center thereof is not aligned with the axial center of a separator, the defect of s sensor element and the deformation of the inside terminal or the outside terminal are prevented by eliminating the misalignment of the axial centers when the inside terminal or the outside terminal is fitted into or onto the sensor element.SOLUTION: The gas sensor includes: an inside terminal having an inside fitting part internally fitted into the rear end side of a sensor element and an inside terminal having an inside base part connected to the rear end side of the inside fitting part; an outside terminal having an outside fitting part externally fitted onto the rear end side of the sensor element and an outside base part connected to the rear end side of outside fitting part; and a separator having insertion holes through which the inside base part and the outside base part are inserted respectively. A portion of a tip-facing surface of the separator is provided with an inside contact surface and an outside contact surface with which the inside fitting part and the outside fitting part are brought into contact respectively. At least one of the inside contact surface and the outside contact surface is formed into a curved surface intersecting an axis line or on a tapered surface intersecting the axis line.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a gas sensor including a sensor element that detects the concentration of a gas to be detected.

As a gas sensor for detecting the concentration of a specific gas (oxygen or NO _x ) in exhaust gas of an automobile or the like, one having a sensor element using a solid electrolyte is known. As such a gas sensor, a configuration is known in which a cylindrical sensor element extending in the axial direction is held around the radial direction by a metal fitting body (main metal fitting), and an outer cylinder is attached to the rear end of the metal fitting body (Patent Document). 1).

  The gas sensor 1000 is manufactured as shown in FIG. First, the element assembly B is assembled while holding the sensor element 300 inside the metal fitting body 200. Specifically, the sensor element 300 is arranged on a ceramic holder 170 arranged in the metal fitting body 200. After that, a talc 600 is filled in the gap between the metal fitting body 200 and the sensor element 300, the ceramic sleeve 310 and the metal packing 320 are sequentially arranged on the talc 600, and the rear end side of the metal fitting body 200 is crimped. Assemble assembly B. On the other hand, the separator 1110 assembled with the inner terminal 710 and the outer terminal 910 is disposed together with the grommet 131 in the outer cylinder 400, and the separator assembly A is assembled. Specifically, the inner terminal 710 and the outer terminal 910 connected to the lead wire 41 are inserted into the insertion hole 1110 b of the separator 1110, and then the separator 1110 is brought into contact with the step portion 410 of the outer cylinder 400. Thereafter, the holding metal fitting 800 is inserted into the gap between the separator 1110 and the outer cylinder 400, the grommet 131 is disposed on the rear end side of the outer cylinder 400, and the separator assembly A is assembled. Note that the heater 15 is already attached to the separator assembly A.

  Then, when the axis lines of the separator assembly A and the element assembly B are aligned and the separator assembly A is put on the rear end of the element assembly B, the heater 15 is inserted into the sensor element 300, and the inner electrode 302 of the sensor element 300 and The outer electrodes 304 are electrically connected to the inner terminal 710 and the outer terminal 910, respectively. Thereafter, in the outer cylinder 400, the outer peripheral portion of the holding metal fitting 800, the outer peripheral portion of the grommet 131, and the overlapping portion with the metal fitting main body 200 are respectively swaged, and the swaged portion between the outer cylinder 400 and the metal fitting main body 200 is laser welded or the like. Thus, the outer cylinder 400 is connected to the rear end of the metal fitting body 200 to manufacture the gas sensor 1000.

Here, the inner terminal 710 includes a cylindrical inner fitting portion 730 inserted into the cylindrical hole of the sensor element 300, and an inner base portion 740 that extends from the inner fitting portion 730 to the rear end and is connected to the lead wire 41. And have. Similarly, the outer terminal 910 includes a cylindrical outer fitting portion 930 that surrounds the rear end portion of the sensor element 300, and an outer base portion 940 that extends from the outer fitting portion 930 to the rear end and is connected to the lead wire. Have. Each of the inner base portion 740 and the outer base portion 940 has a plate shape, and has an inner connector portion 750 and an outer connector portion 950 connected to the lead wire 41 on the rear end side.
When the inner terminal 710 and the outer terminal 910 are assembled to the separator 1110, the inner base portion 740 and the outer base portion 940 are inserted into the insertion hole 1110b of the separator 1110 from the leading end facing surface 1110a side of the separator 1110, respectively. At this time, the inner rear end surface 730a and the outer rear end surface 930a of the inner fitting portion 730 and the outer fitting portion 930 are in contact with the front end facing surface 1110a, and the inner terminal 710 and the outer terminal 910 are positioned and fixed to the separator 1110. It is like that.

JP 2007-278806 A

By the way, when the inner terminal 710 and the outer terminal 910 are assembled to the separator 1110 as described above, if these terminals are originally twisted or deformed, the inner centers of the inner fitting portion 730 and the outer fitting portion 930 are formed. May deviate from the axis of the separator 1110.
Further, play is provided in the insertion hole 1110b of the separator 1110 so that the inner base 740 and the outer base 940 can be smoothly inserted (that is, between the inner base 740 and the outer base 940 and the insertion hole 1110b of the separator 1110). In other words, the inner terminal 710 and the outer terminal 910 may move in the insertion hole even after the separator 1110 is assembled. As a result, the axis of the inner fitting portion 730 or the outer fitting portion 930 may be displaced from the axis of the separator 1110.

For this reason, even if the separator assembly A and the element assembly B are aligned and the separator assembly A is put on the element assembly B, the axis of the gas sensor element 300 and the axis of the inner fitting portion 730 or the outer fitting portion 930 The inner fitting portion 730 or the outer fitting portion 930 comes into contact with the gas sensor element 300 and is further pressed so that the gas sensor element 300 is lost or the inner terminal 710 or The outer terminal 910 may be deformed.
Further, the assembly of the separator assembly A and the element assembly B is based on, for example, the outer cylinder 400 which is the outer portion of the separator assembly A, and the inner fitting portion 730 or the outer fitting portion 930 is attached to the outer cylinder 400. If the axis is deviated, it is necessary to match the axis of the gas sensor element 300 with the axis of the inner fitting part 730 or the outer fitting part 930 in addition to aligning the axis of the separator assembly A and the element assembly B. It takes time to reduce productivity.

  Therefore, even when the inner terminal and the outer terminal are assembled to the separator in a state in which the inner terminal and the outer terminal are displaced from the axis of the separator, It is an object of the present invention to provide a gas sensor that eliminates the shift, prevents the sensor element from being lost and prevents the inner terminal or the outer terminal from being deformed, and can securely connect these terminals to the sensor element.

  In order to solve the above problems, a gas sensor of the present invention includes a cylindrical sensor element extending in the axial direction and having an inner electrode and an outer electrode on its inner and outer peripheral surfaces, respectively, and a cylindrical sensor element surrounding the sensor element. The fitting body is internally fitted on the rear end side of the sensor element, and is connected to the inner fitting portion having a C-shaped cross section that contacts the inner electrode, and the rear fitting side of the inner fitting portion, and An inner terminal having an inner base portion extending toward the rear end side in the axial direction; an outer fitting portion having a C-shaped cross section that is fitted on the rear end side of the sensor element and contacts the outer electrode; and An outer terminal having an outer base portion connected to the rear end side of the outer fitting portion and extending toward the rear end side in the axial direction, and arranged on the rear end side of the sensor element, the inner base portion and the outer side Insert through holes where the bases are inserted. In the gas sensor including the separator, the inner contact surface and the outer contact, which are in contact with the inner fitting portion of the inner terminal and the outer fitting portion of the outer terminal, respectively, are part of the tip-facing surface of the separator. A surface is provided, and at least one of the inner contact surface and the outer contact surface is formed as a curved surface intersecting the axis or a tapered surface intersecting the axis.

In the conventional gas sensor, the surface facing the front end of the separator is a flat surface (a flat surface in the radial direction) perpendicular to the axis, and the rear end surface of the inner fitting portion or the rear end surface of the outer fitting portion covers the entire surface. Contact the surface facing the tip of the separator. For this reason, when the axial center of the inner fitting part or the outer fitting part is displaced with respect to the axial center of the separator, this axial deviation is eliminated, that is, the inner fitting part or the outer fitting so that both axes are aligned. The joint cannot be moved in the radial direction.
On the other hand, according to this gas sensor, the inner contact surface or the outer contact surface (a part of the tip-facing surface) of the separator is formed on a curved surface intersecting the axis or a tapered surface intersecting the axis. When the shaft center of the mating part or the outer fitting part is displaced from the axis of the separator, a part of the rear end face of the inner fitting part or a part of the rear end face of the outer fitting part is It will contact the inner contact surface or the outer contact surface (that is, the inner fitting portion or the outer fitting portion is in a single-contact state with respect to the separator). For this reason, the inner fitting portion or the outer fitting portion can move in the radial direction so as to align both axial centers, and as a result, the axial deviation can be eliminated, the sensor element is missing, the inner terminal or the outer portion Terminal deformation can be prevented.

  In addition, it is possible to provide the separator with a restriction part that can regulate the inner fitting part and the outer fitting part so that the axis of the separator and the inner fitting part and the outer fitting part do not deviate in the first place. is there. However, for example, when the axis of the separator and the axis of the sensor element are misaligned, the inner fitting part and the outer fitting part are fitted with the sensor element in a state of being misaligned. Similarly, the gas sensor element may be lost or the inner terminal and the outer terminal may be deformed. On the other hand, according to the gas sensor of the present application, the inner contact surface or the outer contact surface of the separator is formed on a curved surface that intersects the axis, or a tapered surface that intersects the axis. When the part is fitted to the sensor element, it moves in the radial direction so as to eliminate the shift of the axis of the inner fitting part or the outer fitting part with respect to the axis of the sensor element by contacting the sensor element. Thus, the deviation of the axial center can be eliminated, and the loss of the sensor element and the deformation of the inner terminal or the outer terminal can be prevented.

At least one of the inner contact surface and the outer contact surface may be formed as a convex curved surface or a tapered surface that narrows toward the tip end side in the axial direction.
According to this gas sensor, the inner fitting portion or the outer fitting portion can move (slid) more easily in the radial direction with respect to the inner contact surface or the outer contact surface of the separator. The deformation of the terminal or the outer terminal can be further prevented.

  According to this invention, even when the inner terminal or outer terminal of the gas sensor is assembled to the separator in a state where the axis of the inner terminal or outer terminal of the gas sensor is displaced with respect to the axis of the separator, It is possible to eliminate the deviation of the axial center, prevent the sensor element from being lost, and prevent the inner terminal or the outer terminal from being deformed, so that these terminals can be reliably connected to the sensor element.

It is sectional drawing which cut | disconnected the gas sensor which concerns on embodiment of this invention by the surface which follows an axial direction. It is the top view which looked at the separator from the front end side. (A) It is sectional drawing which cut | disconnected the separator of FIG. 2 in the AA cross section. (B) It is sectional drawing which cut | disconnected the separator of FIG. 2 by the BB cross section. It is a perspective view which shows the structure of the inner side terminal which accommodated the heater. It is a perspective view which shows the structure of an outer side terminal. It is a perspective view which shows the state which attaches an inner side terminal and an outer side terminal to a separator. (A) It is explanatory drawing which illustrated the case where the axial center of the outer fitting part of an outer side terminal shifted | deviated with respect to the axial center of a separator, when the outer side terminal was assembled | attached to the separator. (B) It is explanatory drawing which illustrated the case where the axial center of the outer fitting part of an outer terminal and the axial center of a separator corresponded when the outer terminal was assembled | attached to the separator. It is a figure which shows the state which the outer fitting part fitted on the sensor element when the separator assembly was put on the element assembly. It is a perspective view which shows the modification of a separator. It is a figure which shows the aspect which assembles | assembles a separator assembly and an element assembly in manufacture of the conventional gas sensor.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 shows a cross-sectional structure of a gas sensor 100 according to an embodiment of the present invention cut along a plane along the axis O direction. In this embodiment, the gas sensor 100 is an oxygen sensor that is inserted into the exhaust pipe of an automobile and the tip (lower side in FIG. 1) is exposed to the exhaust gas to detect the oxygen concentration in the exhaust gas. The sensor element 3 is a known oxygen sensor element that constitutes an oxygen concentration cell in which a pair of electrodes are laminated on an oxygen ion conductive solid electrolyte body and outputs a detection value corresponding to the amount of oxygen.
In addition, let the lower side of FIG. 1 be the front end side of the gas sensor 100, and let the upper side of FIG.

  The gas sensor 100 is assembled so that a substantially cylindrical (hollow shaft-shaped) sensor element (in this example, an oxygen sensor element) 3 with a closed end is inserted and held inside a cylindrical metal fitting body (main metal fitting) 20. It has been. The sensor element 3 includes a cylindrical solid electrolyte body whose diameter decreases in a tapered shape toward the tip, and an inner electrode 32 and an outer electrode 34 formed on the inner and outer peripheral surfaces of the solid electrolyte body, respectively. The internal space of the sensor element 3 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 3 to detect the gas. A round bar heater 15 is inserted into the hollow portion of the sensor element 3 so as to raise the temperature of the solid electrolyte body to the activation temperature.

  A cylindrical outer tube 40 that holds a lead wire and a terminal (described later) provided on the rear end side of the sensor element 3 and covers the rear end portion of the sensor element 3 is joined to the rear end portion of the metal fitting body 20. ing. Further, an insulating cylindrical separator 121 is caulked and fixed inside the outer cylinder 40 on the rear end side of the sensor element 3. On the other hand, the detection part at the tip of the sensor element 3 is covered with a protector 7. Then, the male screw portion 20d of the metal fitting body 20 of the gas sensor 100 manufactured in this way is attached to a screw hole such as an exhaust pipe, so that the detection portion at the tip of the sensor element 3 is exposed in the exhaust pipe and the gas to be detected (exhaust gas) Gas). A polygonal flange 20c for engaging a hexagon wrench or the like is provided near the center of the metal fitting body 20, and the step between the flange 20c and the male thread 20d is attached to the exhaust pipe. A gasket 14 is inserted to prevent the gas from leaking when it is blown.

A flange portion 3 a is provided on the center side of the sensor element 3, and a step portion 20 e that is reduced in diameter on the inner peripheral surface near the tip of the metal fitting body 20 is provided. Further, a cylindrical ceramic holder 5 is disposed on the surface facing the rear end of the stepped portion 20e via a washer 12. The sensor element 3 is inserted inside the metal fitting body 20 and the ceramic holder 5, and the flange 3 a of the sensor element 3 is in contact with the ceramic holder 5 via the washer 13 from the rear end side.
Further, a cylindrical talc powder 6 and a cylindrical ceramic sleeve 10 are arranged in the radial gap between the sensor element 3 and the metal fitting body 20 on the rear end side of the flange 3a. Then, the metal ring 30 is disposed on the rear end side of the ceramic sleeve 10, and the rear end portion of the metal fitting body 20 is bent inward to form the crimped portion 20a, whereby the ceramic sleeve 10 is pressed to the front end side. As a result, the talc powder 6 is crushed and the ceramic sleeve 10 and the talc powder 6 are swaged and fixed, and the gap between the sensor element 3 and the metal fitting body 20 is sealed.

The separator 121 disposed on the rear end side of the sensor element 3 is provided with four insertion holes, which will be described later, of which two insertion holes (terminal fitting holes) have plate-like shapes for the inner terminal 71 and the outer terminal 91, respectively. The inner base portion 74 and the outer base portion 94 are inserted and fixed. An inner connector portion 75 and an outer connector portion 95 are formed at the rear ends of the inner base portion 74 and the outer base portion 94, respectively, and lead wires 41 and 41 are crimped and connected to the inner connector portion 75 and the outer connector portion 95, respectively. . Further, a heater lead wire 43 (only one is shown in FIG. 1) drawn from the heater 15 is inserted into two insertion holes (heater lead holes) (not shown) of the separator 121.
A cylindrical grommet 131 is caulked and fixed inside the outer cylinder 40 on the rear end side of the separator 121, and two lead wires 41 and two heater lead wires 43 are respectively inserted from the four insertion holes of the grommet 131. Has been pulled out.
A through hole 131 a is formed at the center of the grommet 131 and communicates with the internal space of the sensor element 3. A water-repellent ventilation filter 140 is interposed in the through-hole 131a of the grommet 131 so that the reference gas (atmosphere) is introduced into the internal space of the sensor element 3 without passing external water.

  On the other hand, a cylindrical protector 7 is fitted on the front end side of the metal fitting body 20, and the front end side of the sensor element 3 protruding from the metal fitting body 20 is covered with the protector 7. The protector 7 is configured by attaching a bottomed cylindrical metal (for example, stainless steel, etc.) double outer protector 7b and an inner protector 7a having a plurality of holes (not shown) by welding or the like.

Next, the configuration of the separator 121 will be described. As shown in FIG. 2, the separator 121 has a heater insertion hole 122 at the center, and a pair of heater lead insertion holes arranged in the opposite direction across the heater insertion hole 122 on the radially outer side of the heater insertion hole 122. 123 and 124, and a pair of terminal insertion holes 125 and 126 which are shifted by 90 degrees from the direction in which the heater lead insertion holes 123 and 124 are arranged and are arranged in opposite directions with the heater insertion hole 122 interposed therebetween.
The hatching in FIG. 2 represents the tip-facing surface 121f of the separator 121. As shown in FIG. 3, the tip-facing surface 121f (contact surface) is formed as a tapered surface that narrows toward the tip side in the axis O direction. Yes. R1 and R2 respectively indicate an inner contact surface and an outer contact surface with which an inner fitting portion 73 and an outer fitting portion 93 of the inner terminal 71 and the outer terminal 91 described later are in contact.

Note that the peripheral edges of the heater lead insertion holes 123, 124 and the heater insertion hole 122 communicate with each other on the tip end side of the separator 121, and two heater lead wires drawn from the heater 15 inserted into the heater insertion hole 122. 43 (not shown) is guided to the heater lead insertion holes 123 and 124 without interference.
Further, the terminal insertion holes 125 and 126 are opened in a substantially rectangular shape parallel to the radial direction of the separator 121, and the lateral hole portions 125a and 126a extend from the vicinity of the outer end in the radial direction to a rectangular shape on the left and right in the circumferential direction. Yes. Accordingly, the peripheral edges of the terminal fitting holes 125 and 126 have a substantially cross shape.

FIG. 3 is a cross-sectional view of the separator 121 taken along a plane parallel to the axial direction. 3A is a cross-sectional view taken along the line AA in FIG. 2 (a cross-sectional view passing through the terminal fitting holes 125 and 126), and FIG. 3B is a cross-sectional view taken along the line BB in FIG. FIG. 4 is a cross-sectional view (cross-sectional view passing through heater lead insertion holes 123, 124) cut by cutting. A flange 121a that protrudes radially outward is formed on the outer surface in the center in the axial direction of the separator 121, and a tip-facing surface 121f is formed as a tapered surface that narrows toward the tip side. Further, the heater insertion hole 122 does not penetrate in the axial direction of the separator 121 and has a depth from the tip end side (lower side in FIG. 3) of the separator 121 to the vicinity of the center in the axial direction. The rear end surface of the heater 15 is brought into contact with the bottom of the heater insertion hole 122.
On the other hand, the heater lead insertion holes 123 and 124 and the terminal insertion holes 125 and 126 penetrate the separator 121 in the axial direction.

Next, FIG. 4 shows the structure of the inner terminal 71 in a state where the heater 15 is accommodated. The inner terminal 71 is elongated from the front end to the rear end, and is integrally formed by bending a metal thin plate (corrosion-resistant heat-resistant superalloy plate) punched into a predetermined shape.
An inner base portion 74 is formed at the rear end side of the inner terminal 71, and an inner connector portion 75 that is caulked and connected to the core wire of the lead wire 41 is disposed at the rear end of the inner base portion 74. An inner bent portion 74a that is bent stepwise toward the front side (the side on which the inner fitting portion 73 protrudes from the plate surface of the inner base portion 74) is formed at the tip of the inner base portion 74, and the tip of the inner bent portion 74a is formed. Is connected to the inner fitting portion 73. Further, an inner wide portion 76 that is wider than other portions is formed on the rear end side of the inner base portion 74 from the inner bent portion 74a. The central portion of the inner wide portion 76 is punched into a U-shape with the rear end fixed, and the inner punched portion 76a is cut out on the back side (surface opposite to the front surface) of the inner wide portion 76.
When the inner base portion 74 is inserted into the terminal insertion hole 125 of the separator 121, the width of the inner wide portion 76 is slightly narrower than the distance between the two lateral hole portions 125a in FIG. 74 is positioned in the terminal fitting hole 125 with play. Further, the inner punched portion 76a abuts against the outer end wall of the terminal insertion hole 125, and the inner wide portion 76 is pressed against the inner wall side of both lateral hole portions 125a by the spring force, whereby the inner base portion 74 is pressed to the terminal insertion hole 125. Hold in.

The inner fitting portion 73 has a cylindrical shape centering on an axis connecting the rear end and the front end, and has a cut portion M along the generatrix on the side opposite to the inner base portion 74. Therefore, when cut along a plane perpendicular to the axis, the inner fitting portion 73 is substantially C-shaped. The outer diameter of the inner fitting portion 73 is larger than the inner diameter of the sensor element 3, and when the inner fitting portion 73 is press-fitted into the sensor element 3, the inner fitting portion 73 is elastically expanded by a spring force, and the sensor The inner electrode of the element 3 is pressed.
Further, the rear end facing surface 73b of the inner fitting portion 73 is a surface parallel to the radial direction, and, as will be described in detail later, when contacting the inner contact surface R1 of the front end facing surface 121f of the separator 121. The movement of the inner fitting portion 73 in the radial direction is not hindered.
On the other hand, two reduced diameter portions 84 that taper down on the distal end side of the inner fitting portion 73 extend in a leg shape. Each reduced diameter portion 84 is first inserted into the sensor element 3 and is guided by the reduced diameter portion 84 so that the inner fitting portion 73 is press-fitted into the sensor element 3.

Then, the vicinity of the center in the axial direction of the heater 15 is accommodated inside the inner fitting portion 73. Two electrode pads 15a (only one is shown in the figure) for energizing the heater are formed on the outer surface on the rear end side of the heater 15, and the bonding portion 53 of the conductive bonding member 50 is connected to the electrode pad 15. It is attached. The joining member 50 extends in the axial direction while expanding stepwise outwardly in the radial direction of the heater 15 on the rear end side from the joining portion 53, and the connector portion 55 at the rear end of the joining member 50 is crimped to the core wire of the lead wire 43. Connected. In this way, the heater 15 is accommodated inside the inner fitting portion 73 of the inner terminal 71, and the connector portion 75, the connector portion 55, and the connector portion 55 are 90 degrees in the radial direction on the rear end side of the inner terminal 71, respectively. It is located at an angle.
A heating resistor (not shown) is embedded at the tip of the heater 15 made of an insulator, and a pair of terminals from the heating resistor is connected to each electrode pad 15a.

  Next, the configuration of the outer terminal 91 inserted into the terminal insertion hole 126 will be described with reference to FIG. Similar to the inner terminal 71, the outer terminal 91 is elongated from the front end to the rear end, and is integrally formed by bending a thin metal plate. The configuration of the outer base portion 94 of the outer terminal 91 is substantially the same as that of the inner base portion 74, and the configurations of the outer connector portion 95, the outer wide portion 96, and the outer punched portion 96a are also the inner connector portion 75, the inner wide portion 76, and the inner punched portion, respectively. Since it is the same as 76a, the description is omitted. Similarly to the inner terminal 71, when the outer base 94 is inserted into the terminal insertion hole 126, the outer wide portion 96 is accommodated between both lateral hole portions 126 a in FIG. 2. Then, the outer punched portion 96 a abuts against the outer end wall of the terminal insertion hole 126, and the outer wide portion 96 is pressed against the inner wall side of both lateral hole portions 126 a by the spring force, and the outer base portion 94 is inserted into the terminal insertion hole 126. keeping.

On the other hand, the outer bent portion 94a at the distal end of the outer base portion 94 is bent stepwise on the back side (the side opposite to the side where the outer fitting portion 93 protrudes from the surface of the outer base portion 94). It is connected to the outer fitting part 93. The outer fitting portion 93 has a substantially C shape when cut along a plane perpendicular to the axis, and has a cutout portion M along the generatrix on the side opposite to the outer base portion 94. And the outer diameter of the outer fitting part 93 is smaller than the outer diameter of the sensor element 3, and when the outer fitting part 93 is externally fitted to the sensor element 3 and elastically expanded, the outer fitting part is caused by a spring force. 93 is shrunk and is pressed against the outer electrode of the sensor element 3.
Further, the rear end facing surface 93b of the outer fitting portion 93 is a surface parallel to the radial direction, and, as will be described in detail later, when contacting the outer contact surface R2 of the front end facing surface 121f of the separator 121. The movement of the outer fitting portion 93 in the radial direction is not hindered.
Furthermore, a total of eight piece-like guide portions 98 in which the tip portion is folded back radially outward of the outer fitting portion 93 (only three in FIG. 5) are provided on the distal end side of the outer fitting portion 93. (Illustrated) formed. The distal end of the guide portion 98 is further lowered from the distal end of the outer fitting portion 93 toward the distal end, and serves as a guide when the outer fitting portion 93 is externally fitted to the sensor element 3.

  Next, assembly of the inner terminal 71, the outer terminal 91, and the heater 15 to the separator 121 will be described below. First, the two lead wires 41 and the two heater lead wires 43 are passed through the grommet 131 from the rear end side of the separator 121 through the heater lead insertion holes 123 and 124 and the terminal insertion holes 125 and 126 in advance. Then, the leading end of the lead wire 41 is crimped and connected to the inner terminal 71 disposed on the leading end side of the separator 121, the inner connector portion 75 of the outer terminal 91, and the outer connector portion 95. Similarly, the ends of the two heater lead wires 43 are caulked and connected to the respective connector portions 55 and 55 of the heater 15 accommodated in the inner terminal 71.

As shown in FIG. 6, when the inner base portion 74 of the inner terminal 71 that houses the heater 15 is inserted into the terminal insertion hole 125 of the separator 121, the inner contact surface R <b> 1 of the tip-facing surface 121 f of the separator 121. The rear end facing surface 73b of the inner fitting portion 73 comes into contact with the inner fitting portion 73, the inner base portion 74 is positioned without being inserted any more, and the inner terminal 71 is locked.
Next, when the outer base portion 94 of the outer terminal 91 disposed outside the inner terminal 71 is inserted into the terminal insertion hole 126, the outer contact surface R2 of the front end facing surface 121f of the separator 121 faces the rear end of the outer fitting portion 93. The surface 93b contacts and the inner terminal 91 is locked without being inserted any further.

Here, when the inner terminal 71 and the outer terminal 91 are assembled to the separator 121, the axes of the inner fitting portion 73 and the outer fitting portion 93 may be displaced from the axis of the separator 121. This is because the terminals 71 and 91 are originally twisted before assembly as described above, or play is provided between the insertion holes 125 and 126 of the separator 121 and the bases 74 and 94. For this reason, the inner terminal 71 and the outer terminal 91 move within the insertion hole even after assembly.
7A is a cross-sectional view illustrating a case where the axis C2 of the outer fitting portion 93 of the outer terminal 91 is shifted to the left with respect to the axis C of the separator 121 after being assembled to the separator 121. FIG.

  When the axial center C2 of the outer fitting portion 93 is displaced from the axial center C of the separator 121 as shown in FIG. It will be in the state per piece which contacts 121f of front-facing surfaces. In FIG. 7A, the right side of the rear end facing surface 93 b of the outer fitting portion 93 is in a single contact state where it contacts the front end facing surface 121 f of the separator 121. When the outer terminal 91 is further assembled to the separator 121 in such a state, the tip-facing surface 121f of the separator 121 is a convex taper surface that narrows toward the tip side. The outer fitting portion 93 can move in the radial direction (left and right direction in FIG. 7) so as to match. In FIG. 7A, the outer fitting portion 93 moves toward the right side of the drawing. As a result, as shown in FIG. 7B, the shaft misalignment can be eliminated by aligning the axes of the axes C and C2.

Thereafter, as in the prior art, a separator assembly A and an element assembly B are manufactured and assembled together.
At this time, as shown in FIG. 8A, the axis C of the separator 121 and the axis C2 of the outer fitting portion 93 of the outer terminal 91 may be displaced from the axis C3 of the sensor element. 8A shows a state where the axis C of the separator 121 and the axis C2 of the outer fitting portion 93 of the outer terminal 91 are shifted to the left from the axis C3 of the sensor element 3. FIG. In such a state, when the outer fitting portion 93 is externally fitted to the sensor element 3, the tip-facing surface 121f (contact surface) of the separator 121 is a convex tapered surface that narrows toward the tip side. The outer fitting portion 93 can move in the radial direction (left and right direction in FIG. 8) so that the axis C2 of the outer fitting portion 93 and the axis C3 of the sensor element 3 are aligned. In FIG. 8A, the outer fitting portion 93 moves toward the right side of the drawing. As a result, as shown in FIG. 8B, the shaft misalignment can be eliminated by aligning the axes of the axial centers C2 and C3. As a result, loss of the sensor element 3 and deformation of the outer terminal 91 can be prevented.

  In the above description, the case where the fitting portion 93 of the outer terminal 91 is displaced has been described. However, when the inner fitting portion 73 of the inner terminal 71 is displaced, the inner fitting is similarly performed by the action of the tapered surface. The inner fitting portion 73 can be fitted into the sensor element 3 in a state where the shift of the axial center between the joint portion 73 and the sensor element 3 is eliminated.

  It goes without saying that the present invention is not limited to the above-described embodiment, but extends to various modifications and equivalents included in the spirit and scope of the present invention. For example, a separator having a shape as shown in FIG. 9 may be used. Here, the separator 221 shown in FIG. 9 has a concave curved surface in which its front end facing surface 221f is narrowed toward the rear end side, and an inner fitting portion 73 and an outer fitting portion are formed on a part of the curved surface. The rear end facing surfaces 73b and 93b of the 93 are in line contact. Since the heater insertion hole 122, the heater lead insertion holes 123 and 124, and the terminal insertion holes 125 and 126 of the separator 221 are the same as those of the separator 121, description thereof is omitted.

Furthermore, instead of the front-facing surface 221f of the curved separator 221 shown in FIG. 9, the front-facing surface 221f may be a tapered surface that narrows toward the rear end side.
Similarly, in the above embodiment, the tip-facing surface 121f of the separator 121 is a tapered surface, but may be a convex curved surface that narrows toward the tip side.
Furthermore, in the said embodiment, both contact surface R1, R2 which contact | connects each fitting part 73, 93 of the inner side terminal 71 and the outer side terminal 91 among the contact surfaces provided in the front end surface 121f is formed in a taper surface. However, it is sufficient that at least one of the contact surfaces R1 and R2 is formed as a tapered surface.

3 sensor element 20 metal fitting body 32 inner electrode 34 outer electrode 71 inner terminal 91 outer terminal 73 inner fitting portion 93 outer fitting portion 74 inner base portion 94 outer base portion 100 gas sensor 1211, 221 separator 121f, 221f leading end surface 125 of separator, 126 Terminal insertion hole O Axis

Claims (2)

A cylindrical sensor element extending in the axial direction and having an inner electrode and an outer electrode on its inner and outer peripheral surfaces, and
A cylindrical metal fitting body surrounding the sensor element;
The sensor element is fitted into the rear end side of the sensor element, is connected to the inner fitting portion having a substantially C-shaped cross section in contact with the inner electrode, and the rear end side of the inner fitting portion. An inner terminal having an inner base extending toward the rear end side;
The sensor element is fitted on the rear end side of the sensor element, is connected to the outer fitting portion having a substantially C-shaped cross section that contacts the outer electrode, and the rear end side of the outer fitting portion. An outer terminal having an outer base extending toward the rear end side;
In the gas sensor comprising: a separator that is disposed on the rear end side of the sensor element and has an insertion hole into which the inner base portion and the outer base portion are respectively inserted.
An inner contact surface and an outer contact surface that are in contact with the inner fitting portion of the inner terminal and the outer fitting portion of the outer terminal, respectively, are provided on a part of the tip-facing surface of the separator,
At least one of the inner contact surface and the outer contact surface is a gas sensor formed on a curved surface that intersects the axis or a tapered surface that intersects the axis.   2. The gas sensor according to claim 1, wherein at least one of the inner contact surface and the outer contact surface is formed as a convex curved surface or a tapered surface that narrows toward a tip end side in the axial direction.