JP2008145339A - Method for manufacturing gas sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing gas sensor which suppresses misalignment between the axis of main fitting and detecting element, when assembling them integrally, in order to prevent the detecting element from being made defective, broken or the like. <P>SOLUTION: The detecting element 10 integrated with a flange part 24 is contained in the main fitting 50 of an intermediate assembly 300 supported on an element base 350, and a sleeve 27 is pressed downward by using a compression tool 410. A talc ring 26, disposed between the flange part 24 and the sleeve 27, is crushed and becomes powder, whereby the gap between the detecting element 10 and the main fitting 50 is filled up, and the detecting element 10 is integrated with the main fitting 50. At this time, the rear end of the detecting element 10 is held by a first holding claw 421 and a second holding claw 422 of a holding tool 420 so as to regulate a movement in the horizontal direction, whereby the axis O of the main fitting 50 and the axis P of the detecting element 10 can be aligned, when they are integrated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a gas sensor including a plate-like detection element for detecting the concentration of a specific gas in exhaust gas.

  Conventionally, a gas sensor provided with a detection element that generates electromotive force of different magnitude or changes its resistance value according to the concentration of a specific gas, such as NOx (nitrogen oxide) or oxygen, in an exhaust gas of an automobile or the like It has been known. For example, a detection element using zirconia has a solid electrolyte body made of zirconia in a bottomed cylindrical shape, and the oxygen concentration is based on the difference in oxygen partial pressure between the air introduced inside and the exhaust gas filled outside. The detection is performed. Such a detection element is held by the metal shell and is attached to the exhaust pipe of the automobile. Since the attachment is generally screwed into the mounting hole of the exhaust pipe, the metal sensor metal fitting is attached to the outer peripheral surface. It is formed in a cylindrical shape having a thread.

  In recent years, plate-shaped detection elements have been developed in place of bottomed cylindrical detection elements in order to reduce the size and performance of gas sensors. In the manufacturing process of such a gas sensor, in order to hold the plate-shaped detection element in the cylindrical metal shell as described above, a metal cup containing a ceramic ring (ceramic holder) and a first talc ring is contained therein. The (element cup) is arranged around the detection element in the radial direction, and the first talc ring is compressed and deformed to be integrated with the detection element. In this state, the detection element is inserted into the metal shell, the metal cup is locked to the shelf formed on the inner periphery of the metal shell, and the second talc ring (second filling layer) is formed from the rear end side of the detection element. ), A sleeve (ceramic sleeve) and a caulking packing are laminated on the element cup. Then, the second talc ring is crushed into powder by pressing the sleeve against the distal end side through the caulking packing, and the gap between the outer periphery of the detection element and the inner periphery of the metal shell is filled, The detection element and the metal shell are integrated. Thereafter, the crimping portion (rear end portion) of the metal shell is crimped, and the detection element is held integrally with the metal shell (see, for example, Patent Document 1).

  Next, a connection terminal (lead frame) for electrically connecting to the electrode terminal (part) of the detection element and taking out the detection signal to the outside is connected to the outer cylinder joined to the rear end side of the metal shell. The accommodated separator (insulating contact member) and a grommet that closes the rear end of the outer cylinder on the rear end side of the separator are accommodated. And the site | part located in the radial direction outer side of a separator is crimped to radial direction inner side among an outer cylinder, and a separator is fixed to an outer cylinder. In fixing the separator to the outer cylinder, the grommet is in close contact with the separator and the outer cylinder.

Then, by moving the outer cylinder relative to the metal shell, the separator is fitted to the rear end portion of the detection element. At this time, the outer cylinder is disposed on the outer side in the radial direction of the metallic shell, and the outer cylinder is crimped and fixed to the metallic shell by crimping the outer cylinder in the radial inner side. Furthermore, the grommet is fixed to the outer cylinder by caulking a portion of the outer cylinder located on the radially outer side of the grommet to the radially inner side. Thereafter, the portion crimped radially inward with respect to the metal shell of the outer cylinder is laser welded over the entire circumference, and the metal shell and the outer cylinder are joined together to complete the gas sensor.
JP 2005-37372 A

  However, in the gas sensor manufacturing process, when the second talc ring is compressed and deformed by caulking the metal shell, the detection element receives stress in a direction different from the axial direction depending on how the talc ring is crushed. In some cases, the axis and the metal shell may be integrated while the axis is shifted. When the gas sensor is assembled as it is, a load is applied to the rear end portion of the detection element when the separator is assembled, and the detection element may be lost or broken. In some cases, the separator may be fixed in the outer cylinder by caulking while the load is applied to the detection element due to the axial displacement between the detection element and the metal shell and the outer cylinder. When used, the internal stress of the detection element may increase, and the detection element may be lost or broken.

  The present invention has been made to solve the above-described problems, and suppresses misalignment of the metal shell and the detection element when the metal shell and the detection element are assembled together, thereby preventing the detection element from being broken or broken. An object of the present invention is to provide a method for manufacturing a gas sensor.

  To achieve the above object, a gas sensor manufacturing method according to a first aspect of the present invention includes a plate-like detection element extending in the axial direction, a flange portion integrally assembled in a form surrounding the periphery of the detection element, and an axis A gas sensor comprising: a metal shell having a through hole extending in a direction for inserting the detection element, and projecting radially inward from an inner peripheral surface of the through hole, and having a step portion engaged with the flange portion The element holding step of holding the detection element in the metal shell by inserting the detection element into the through hole of the metal shell and supporting the flange portion on the stepped portion. And, after the element holding step, a restricting member disposing step of disposing a restricting member that restricts movement of the trailing end portion of the detecting element in the radial direction in contact with or away from the trailing end portion of the detecting element; The regulation After the material arranging step, the filling member loaded between the inner peripheral surface of the metal shell and the outer peripheral surface of the detection element on the rear end side from the flange portion is pressed toward the front end side in the axial direction, and the filling member is A filling member compressing step for compressing, and after the filling member compressing step, a rear end portion of the metal shell is pressed from the outside and bent radially inward, so that at least the flange portion and the filling member are connected to the rear end. And an element fixing step of clamping the detection element in the metal shell.

  According to a second aspect of the present invention, in addition to the configuration of the first aspect of the invention, the filling member has a solid shape in which powder is pressed into an annular shape, and the filling member compression step Before, the solid shape is covered around the detection element and loaded on the inner periphery of the metal shell, and in the filling member compression step, the powder is crushed into powder, and the inner metal surface of the metal shell The gap between the detection element and the outer peripheral surface is filled and pressed.

  According to a third aspect of the present invention, there is provided a gas sensor manufacturing method according to the first or second aspect of the invention, in addition to the filling member compression step and the element fixing step, and the detection element rear end portion. A restriction release step for releasing the restriction of movement in the radial direction of the head is performed.

  According to a fourth aspect of the present invention, in the gas sensor manufacturing method, in addition to the configuration of the first aspect of the present invention, the restricting member holds the detection element across the rear end portion. Thus, the movement of the detection element in the radial direction is restricted.

  According to a fifth aspect of the present invention, there is provided a gas sensor manufacturing method according to any one of the first to fourth aspects, wherein the restricting member is arranged in the thickness direction of the detection element. The restricting member disposing step includes a first restricting member that restricts movement of the rear end portion and a second restricting member that restricts movement of the rear end portion of the detection element in a direction orthogonal to the plate thickness direction. Are arranged after the first restricting member disposing step, the first restricting member disposing the first restricting member in contact with or separating from both sides of the rear end portion of the detecting element in the plate thickness direction. And a second restricting member disposing step of disposing the second restricting member in contact with or apart from both sides of the rear end portion of the element in a direction orthogonal to the plate thickness direction.

  In the gas sensor manufacturing method according to the first aspect of the present invention, in the filling member compression step, the filling member loaded between the inner peripheral surface of the metal shell and the outer peripheral surface of the detection element is compressed, and the detection element is previously stored in the metal shell. In the element fixing step, the detection element is fixed by performing a deformation by bending the rear end portion of the metal shell inward in the element fixing step. The positional relationship can be prevented from shifting. The filling member compression step is performed while the movement in the radial direction is restricted by the restriction member arranged at the rear end portion of the detection element in the restriction member arrangement step performed before that, so the metal fitting and the detection element The relative positional relationship can be made constant. That is, after aligning the axis of the metal shell and the axis of the detection element to perform the filling member compression process and aligning both axes, the element fixing process is performed to fix the detection element in the metal shell. The axial deviation between the metal shell and the detection element can be effectively suppressed. In the subsequent manufacturing process, even if the part that is assembled to the metal shell and contacts the detection element is assembled with the axis of the metal shell as a reference, the axis of the metal shell and the axis of the detection element are aligned. For example, in the completed gas sensor, it is possible to sufficiently prevent the detection element from being subjected to a load due to the axial deviation with respect to the components that are in contact with the detection element, so that the element can be prevented from being broken.

  Thus, in order to hold the detection element in the metallic shell in advance by the filling member, it is necessary to load the filling member into the metallic shell in which the detection element is inserted, but as in the invention according to claim 2, If a solid-shaped filling member in which powder is pressed into a ring shape in advance is used, the solid member is placed around the detection element and loaded together with the detection element in the metal shell, the filling member can be easily loaded. . As described above, in the filling member compression step, the filling member is compressed while restricting the movement of the rear end portion of the detection element in the radial direction. Since the powder is uniformly disposed in the gap between the metal shell and the detection element, the stress applied to the detection element can be dispersed. For this reason, it is possible to prevent the detection element from being lost or broken in this step. In addition, since the gap between the metal shell and the detection element is filled with the filling member that has become powder, airtightness can be sufficiently maintained through the through hole of the metal shell.

  By the way, when the rear end portion of the metal shell is deformed in the element fixing process, the jig that performs the deformation may be shaken in the axial direction of the metal shell. At this time, as in the invention according to claim 3, if the restriction release process is performed before the element fixing process to release the restriction applied to the rear end portion of the detection element, the detection element can be detected even if the axial direction of the metal shell is shaken. Since no stress due to regulation is applied, it is possible to suppress the misalignment between the axis of the metallic shell and the axis of the detection element in this step, and to prevent the detection element from being broken or broken.

  If the restricting member described above is arranged in contact with or separated from the rear end portion of the detection element, the movement of the rear end portion of the detection element in the radial direction can be sufficiently restricted in the filling member compression step. However, as in the invention according to claim 4, if the restricting member is configured to hold the rear end portion of the detection element, the axis of the metal shell and the axis of the detection element can be aligned more accurately. Can do.

  Further, as in the invention according to claim 5, the restriction member includes a first restriction member that restricts movement of the detection element in the plate thickness direction and a second restriction that restricts movement in the direction orthogonal to the plate thickness direction. If it comprises a member, the position of the detection element in the plate thickness direction is first corrected by the first restriction member, and then the position of the detection element in the direction orthogonal to the plate thickness direction is corrected by the second restriction member. Therefore, the rear end portion of the detection element can be more reliably positioned. Since the rear end portion of the detection element is positioned by the first restriction member and the second restriction member from the plate thickness direction of the detection element and the direction orthogonal thereto, the corner portion of the detection element comes into contact with the restriction member. In this case, the corner portion of the detection element can be prevented from being lost.

  Hereinafter, an embodiment of a gas sensor manufacturing method embodying the present invention will be described with reference to the drawings. First, as an example of a gas sensor manufactured by the method for manufacturing a gas sensor according to the present invention, the structure of a gas sensor 1 will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view of the gas sensor 1. FIG. 2 is a perspective view of the detection element 10. In the following drawings, the vertical direction in FIG. 1 and FIG. 2 is the axis O direction of the metal shell 50 constituting the gas sensor 1 and the axis P direction of the detection element 10, and the lower side is the gas sensor 1 and detection element 10. The front end side and the upper side will be described as the rear end side.

  A gas sensor 1 shown in FIG. 1 is attached to an exhaust pipe (not shown) of an automobile, and a front end portion 11 of a detection element 10 held inside is exposed to exhaust gas flowing in the exhaust pipe. This is a so-called full-range air-fuel ratio sensor that detects the air-fuel ratio of exhaust gas from the oxygen concentration. When the air-fuel ratio of the exhaust gas is lean, a detection value (current value) corresponding to the amount of oxygen surplus with respect to the theoretical air-fuel ratio is obtained from the detection element 10, and when it is rich, unburned gas A detection value (current value) corresponding to the amount of oxygen necessary to completely burn the gas is obtained. Based on these detection values, the air-fuel ratio of the exhaust gas is obtained by a sensor control circuit (not shown) and output to an ECU (electronic control unit) for use in air-fuel ratio feedback control and the like.

  First, the detection element 10 will be described. A detection element 10 shown in FIG. 2 is a narrow plate-like element extending in the direction of the axis P as is well known, and a gas detection body 3 for detecting the oxygen concentration and the gas detection body 3 are activated early. Therefore, the heater body 4 for heating is integrated as a laminated body bonded in the thickness direction (in FIG. 1, the left-right direction on the paper surface is the thickness direction (plate thickness direction), and the front-back direction on the paper surface is the width direction. Is shown.) The gas detector 3 is composed of a solid electrolyte body mainly composed of zirconia and a detection electrode mainly composed of platinum (both not shown), and the detection electrode is disposed in the distal end portion 11 of the detection element 10. . And in order to protect a detection electrode from poisoning by exhaust gas, the protective layer 15 is formed in the front-end | tip part 11 of the detection element 10 so that the outer peripheral surface may be wrapped. Further, five electrode pads 16 for taking out electrodes from the gas detection body 3 and the heater body 4 are formed at the rear end portion 12 of the detection element 10. In the present embodiment, the detection element 10 is described as the “detection element” in the present invention. However, strictly speaking, the heater element 4 is not necessarily required as the configuration of the detection element 10, and the gas detection element 3 is the main element. It may correspond to the “detection element” of the invention.

  Next, the flange portion 24 will be described. As shown in FIG. 1, a metal cup 20 having a bottomed cylindrical shape in which the detection element 10 is inserted is disposed inside the central portion 13 of the detection element 10 at a slightly distal end side. The metal cup 20 is a holding member for holding the detection element 10 in the metal shell 50, and the distal end portion 11 of the detection element 10 protrudes from the opening 25 at the bottom of the cylinder. Moreover, the front-end | tip peripheral part 23 of the edge part of a cylinder bottom is formed in the taper shape over the outer peripheral surface. In the metal cup 20, an alumina ceramic ring 21 and a talc ring 22 obtained by compressing and solidifying talc powder are accommodated with the detection element 10 inserted therethrough. The talc ring 22 is crushed in the metal cup 20 to be filled in detail, whereby the metal cup 20, the ceramic ring 21, and the talc ring 22 are integrated to form a flange portion 24 in the radial direction of the detection element 10. It is assembled together in a form that surrounds it.

  Next, the metal shell 50 will be described. The metal shell 50 is for attaching and fixing the gas sensor 1 to an exhaust pipe (not shown) of an automobile, and has a cylindrical shape in which a through hole 58 is formed. The center portion 13 of the detection element 10 is held in the through hole 58 of the metal shell 50 together with the flange portion 24. At this time, the axis P of the detection element 10 is arranged so as to substantially coincide with the axis O of the metal shell 50. ing. The metal shell 50 is made of a low carbon steel such as SUS430, and a male screw portion 51 for attachment to the exhaust pipe is formed on the outer peripheral tip side. A distal end engaging portion 56 to which a protector 8 described later is engaged is formed on the distal end side of the male screw portion 51. In addition, a tool engaging portion 52 that engages a tool for attachment is formed at the center of the outer periphery of the metal shell 50, and between the front end surface of the tool engaging portion 52 and the rear end of the male screw portion 51. A gasket 55 for preventing gas escape when attached to the exhaust pipe is inserted. Further, the rear end side of the tool engaging portion 52 is engaged with a rear end engaging portion 57 to be engaged with an outer cylinder 65 described later, and the detection element 10 is caulked and held in the metal shell 50 on the rear end side. For this purpose, a caulking portion 53 is formed.

  Further, a stepped portion 54 having a step shape is formed in the vicinity of the male screw portion 51 on the inner periphery of the through hole 58 of the metal shell 50. The step 54 is engaged with the peripheral edge 23 of the metal cup 20 that forms the flange 24 integrated with the detection element 10. Further, a talc ring 26 is loaded on the inner periphery of the metal shell 50 from the rear end side of the flange portion 24 in a state where the detection element 10 is inserted through the ring. A cylindrical sleeve 27 is fitted into the metal shell 50 so as to hold the talc ring 26 from the rear end side. A shoulder portion 28 having a step shape is formed on the outer periphery of the rear end side of the sleeve 27, and an annular caulking packing 29 is disposed on the shoulder portion 28. In this state, the crimping portion 53 of the metal shell 50 is crimped so as to press the shoulder portion 28 of the sleeve 27 toward the distal end side via the crimping packing 29. The talc ring 26 is crushed in the metal shell 50 and filled in details. The talc ring 26 and the talc ring 22 preloaded in the metal cup 20 mainly form the flange portion 24 and the detection element 10. It is positioned and held in the metal fitting 50. The airtightness in the metal shell 50 is maintained by the caulking packing 29 interposed between the caulking portion 53 and the shoulder portion 28 of the sleeve 27, and the outflow of combustion gas is prevented. The talc ring 26 corresponds to the “filling member” in the present invention.

  Next, the protector 8 will be described. From the tip (tip engaging portion 56) of the metal shell 50, the tip 11 of the detection element 10 held inside protrudes. The tip engagement portion 56 protects the tip portion 11 of the detection element 10 from contamination caused by deposits (toxic substances such as fuel ash and oil components) in exhaust gas, breakage due to moisture, and the like. A protector 8 is fitted and fixed by spot welding or laser welding. The protector 8 is a double structure constituted by a bottomed cylindrical inner protector 90 and a cylindrical outer protector 80 that surrounds the periphery in the radial direction with a gap between the outer peripheral surface of the inner protector 90. Have

  The inner protector 90 has a plurality of inner introduction holes 95 at the rear end side of the peripheral wall 92, a plurality of drain holes 96 at the front end side of the peripheral wall 92, and a discharge port 97 at the bottom wall 93. Then, the base end portion 91 on the opening end side (rear end side) is engaged with the outer periphery of the front end engaging portion 56, and in this state, the outer periphery is made a round and laser welding is performed, and the inner protector 90 is the metal shell 50. It is fixed to.

  Further, the outer protector 80 has a plurality of outer introduction holes 85 opened on the distal end side of the peripheral wall 82. The base end portion 81 on the opening end side is engaged with the outer periphery of the base end portion 91 of the inner protector 90, and spot welding is performed on the outer periphery in this state, and the outer protector 80 and the inner protector 90 together with the metal shell 50 is fixed. Furthermore, the tip 83 of the outer protector 80 is bent inward toward the peripheral wall 92 of the inner protector 90 so as to close the gap between the outer protector 80 and the inner protector 90.

  The gap between the outer protector 80 and the inner protector 90 causes the exhaust gas introduced from the outside through the outer introduction hole 85 to generate a swirling flow in a state of surrounding the outer periphery of the peripheral wall 92 of the inner protector 90, and thereby the gas component It is provided to separate water and moisture. The gas component is introduced into the inner protector 90 from the inner introduction hole 95, contacts the detection element 10, and is discharged to the outside from the discharge port 97, while moisture enters the inner protector 90 from the drain hole 96. , And is configured to be discharged from the discharge port 97 to the outside. With this configuration, the distal end portion 11 of the detection element 10 is protected from contamination due to deposits in the exhaust gas, breakage due to thermal shock caused by moisture, and the like.

  Next, the structure of the rear end side of the metal shell 50 of the gas sensor 1 will be described. From the rear end (caulking portion 53) of the metal shell 50, the rear end portion 12 of the detection element 10 held inside protrudes. The rear end portion 12 is covered with a cylindrical separator 60 made of insulating ceramics. The separator 60 has five connection terminals 61 (two of which are shown in FIG. 1) that contact (electrically connect) each of the five electrode pads 16 (see FIG. 2) formed on the rear end portion 12 of the detection element 10. Is held inside. Further, the connecting portions between the five lead wires 64 (three of them are shown in FIG. 1) drawn out of the gas sensor 1 and the connection terminals 61 are also housed and protected.

  The above-described outer cylinder 65 is made of stainless steel (for example, SUS304) and has a cylindrical shape. The outer cylinder 65 is attached to the rear end side of the metal shell 50 and is exposed from the rear end of the metal shell 50 and the separator 60 and the separator 60. It covers and protects the surroundings. The outer cylinder 65 has an opening end 66 on its front end side engaged with the outer periphery of the rear end engaging portion 57 of the metal shell 50 and is crimped from the outer peripheral side, and makes a round around the outer periphery, and the rear end engaging portion 57. And is fixed to the metal shell 50 by laser welding.

  Further, a metal-made cylindrical holding metal fitting 70 is disposed in the gap between the outer cylinder 65 and the separator 60. The holding metal fitting 70 has a support portion 71 formed by bending the rear end of the holding member 70 inward, and a support portion 71 is provided with a flange portion 62 provided in a hook shape on the outer periphery of the rear end side of the separator 60 inserted into the holding metal fitting 70. And the separator 60 is supported. In this state, the outer peripheral surface of the outer cylinder 65 at the portion where the holding metal fitting 70 is disposed is crimped, and the holding metal fitting 70 that supports the separator 60 is fixed to the outer cylinder 65.

  A fluorine rubber grommet 75 is fitted into the opening on the rear end side of the outer cylinder 65. The grommet 75 has five insertion holes 76 (one of which is shown in FIG. 1), and the five lead wires 64 drawn from the separator 60 are inserted into each insertion hole 76 in an airtight manner. ing. In this state, the grommet 75 is crimped from the outer periphery of the outer cylinder 65 while pressing the separator 60 toward the front end side, and is fixed to the rear end of the outer cylinder 65.

  As described above, in the gas sensor 1, the element unit 210 (see FIG. 3) in which the flange portion 24 is assembled and integrated with the detection element 10 in the manufacturing process, and the bracket assembly in which the protector 8 and the metal shell 50 are integrated. The detection element 10 is held in the metal shell 50 by being caulked by the caulking portion 53. At this time, in order to suppress a deviation between the axis O of the metal shell 50 and the axis P of the detection element 10, correction in the direction of the axis P of the detection element 10 is performed in the present embodiment. Hereinafter, the manufacturing process of the gas sensor 1 will be described with reference to FIGS. 3 to 13 focusing on the process of assembling the element unit 210 to the metal fitting assembly 250.

  FIG. 3 is a perspective view of the element unit 210. FIG. 4 is an exploded perspective view for explaining an element holding step for assembling the element unit 210 to the metal fitting assembly 250. FIG. 5 is a longitudinal sectional view showing a state in which the intermediate assembly 300 in which the element unit 210 is assembled to the bracket assembly 250 is placed on the element base 350. FIG. 6 is a longitudinal sectional view showing a state before the rear end portion 12 of the detection element 10 is held by the holding jig 420. FIG. 7 is an enlarged view of the circle A in FIG. FIG. 8 is a diagram showing the positional relationship between the first holding claw 421, the second holding claw 422 and the rear end portion 12 of the detection element 10 projected onto a plane orthogonal to the central axis R of the holding jig 420. is there. FIG. 9 is a diagram showing the positional relationship between the first holding claw 421, the second holding claw 422, and the rear end portion 12 of the detection element 10 projected onto a plane orthogonal to the central axis R of the holding jig 420. is there. FIG. 10 is a longitudinal sectional view showing a state in which a load is applied to the talc ring 26 of the intermediate assembly 300. FIG. 11 is a longitudinal sectional view showing a state where the holding of the rear end portion 12 of the detection element 10 by the holding jig 420 is released. FIG. 12 is a longitudinal sectional view showing a state in which the compression jig 410 and the holding jig 420 are moved away from the intermediate assembly 300. FIG. 13 is a longitudinal sectional view showing a state where the crimping portion 53 of the intermediate assembly 300 is crimped by the crimping jig 450.

  As described above, the detection element 10 of the gas sensor 1 is formed by laminating an unfired gas detector and an unfired heater body in the thickness direction (plate thickness direction), and a protective layer 15 on the front end portion 11 of the fired fired body. Is formed as an elongated plate-like element as shown in FIG. Then, as shown in FIG. 3, the metal cup 20 containing the ceramic ring 21 and the talc ring 22 is attached so as to be fitted from the rear end portion 12 side of the detection element 10, and a little front end side of the central portion 13 of the detection element 10. To place. In this state, the talc ring 22 is pressed to the ceramic ring 21 side along the axis P, and is crushed to form a powder so that the gap in the metal cup 20 is filled and the flange portion 24 integrated with the detection element 10. To complete the element unit 210.

  Next, as shown in FIG. 4, from the rear end side (caulking portion 53 side) into the through hole 58 of the bracket assembly 250 assembled by previously joining the protector 8 to the tip engaging portion 56 of the metal shell 50. The element unit 210 is inserted. And the front-end | tip peripheral part 23 of the metal cup 20 which comprises the flange part 24 is latched by the step part 54 (refer FIG. 1) in the through-hole 58, and the detection element 10 is hold | maintained in the metal shell 50 (element holding | maintenance). Process). Further, the talc ring 26, the sleeve 27, and the caulking packing 29 are inserted into the detection element 10 from the rear end 12 side, and are respectively accommodated in the through holes 58 of the metal shell 50.

  The intermediate assembly 300 assembled in this way is positioned and supported on the element base 350 as shown in FIG. A support hole 360 extending in the vertical direction is provided in the element base 350, and the intermediate assembly 300 is inserted into the support hole 360 from the front end side and is held by the element base 350. At this time, the surface on the distal end side of the tool engaging portion 52 of the metal shell 50 constituting the intermediate assembly 300 abuts against the opening end of the support hole 360, and the intermediate assembly 300 is positioned in the vertical direction. And the axis P of the metal shell 50 is aligned in the vertical direction. When the intermediate assembly 300 is arranged on the element base 350, the thickness direction (plate thickness direction) of the detection element 10 held in the metal shell 50 is the first holding claw 421 of the holding jig 420 described later. The arrangement direction in the radial direction of the intermediate assembly 300 is adjusted so as to be aligned in the contact / separation direction.

  Above the element pedestal 350, an elevating device 400 that is preliminarily positioned with respect to the element pedestal 350 and that can be moved up and down is provided. The elevating device 400 includes a compression jig 410 provided so as to be able to move up and down in order to compress the talc ring 26 and the rear end portion 12 of the detection element 10 in the horizontal direction (for example, the left and right direction on the paper surface and the front and back direction). And a holding jig 420 that is sandwiched and held between them is fixed. The compression jig 410 has a cylindrical pressing portion 415 having a through-hole 411 penetrating in the vertical direction so that the compression jig 410 can be attached to the lifting device 400 in a state in which the contact portion 412 on the front end side protrudes downward. It is configured to be fixed to the mounting portion 416. The holding jig 420 includes a pair of first holding claws 421 provided on the distal end side (lower side) so as to come in contact with and separate from each other toward the central axis R in the horizontal direction (for example, the left-right direction), A pair of second holding claws 422 (one of them is shown in the figure in the figure) provided so as to approach and separate from each other toward the central axis R in a horizontal direction orthogonal to the holding claws 421 (for example, the front and back direction in the drawing). Have). Although not shown, the first holding claw 421 and the second holding claw 422 are fixed to the lifting device 400 on the rear end side, respectively, and the reference and separation directions of the first holding claw 421 and the second holding claw 422 The own central axis R is aligned with the central axis Q of the through hole 411 of the compression jig 410. In addition, the pair of first holding claws 421 are provided so as to be swingable in a direction orthogonal to the contact and separation direction of each other. The first holding claw 421 and the second holding claw 422 correspond to the “first regulating member” and the “second regulating member” in the present invention, respectively.

  When the intermediate assembly 300 is held on the element base 350, the lifting device 400 is driven downward as shown in FIG. 6, and the compression jig 410 and the holding jig 420 are brought close to the intermediate assembly 300. The Specifically, the compression jig 410 and the holding jig 420 are moved to a position where the tip of the contact portion 412 of the compression jig 410 contacts the crimping packing 29 of the intermediate assembly 300. At this time, as shown in FIG. 7, the outer peripheral surface of the abutting portion 412 of the compression jig 410 abuts on the inner peripheral surface of the caulking portion 53 of the metal shell 50 constituting the intermediate assembly 300. As a result, the axis O of the metal shell 50 is aligned with the central axis Q of the through hole 411 of the compression jig 410 and positioned relative to each other. The central axis R of the holding jig 420 is also aligned with the axis O of the metal shell 50, and the first holding claw 421 and the second holding claw 422 are the rear ends of the detection elements 10 constituting the intermediate assembly 300. In the part 12, it arrange | positions in the radial direction periphery (regulation member arrangement | positioning process).

  Next, the first holding claw 421 and the second holding claw 422 of the holding jig 420 position and hold the rear end portion 12 of the detection element 10 (first regulating member arranging step in the regulating member arranging step). First, as shown in FIG. 8, the pair of first holding claws 421 are driven in a direction approaching each other, and the surface on the side perpendicular to the thickness direction is sandwiched and held between the rear end portions 12 of the detection elements 10. . At this time, the rear end portion 12 of the detection element 10 is pushed by the first holding claw 421 that abuts first among the pair of first holding claws 421, and the axis P is positioned at the center between the pair of first holding claws 421. Thus, the position of the rear end portion 12 is moved.

  Then, as shown in FIG. 9, the pair of second holding claws 422 are driven in a direction approaching each other, and the surface on the side along the thickness direction is sandwiched and held at the rear end portion 12 of the detection element 10 (regulation). Second regulating member arranging step in member arranging step). Here, as described above, the first holding claw 421 is configured to be swingable in a direction orthogonal to its contact / separation direction. For this reason, when the rear end portion 12 of the detection element 10 is held by the second holding claw 422, the second holding claw 422 that is in contact with the first holding claw 422 is pushed by the second holding claw 422. The position of the rear end portion 12 of the detection element 10 is moved together with the first holding claws 421 so that the axis P is located at the center of the holding claws 422. Thus, the axis P of the detection element 10 is aligned with the central axis R of the holding jig 420, and is also aligned with the central axis Q of the through hole 411 of the compression jig 410 that coincides with the central axis R. Furthermore, since the axial line O of the metal shell 50 is aligned with the central axis Q when the inner peripheral surface of the crimping portion 53 is in contact with the outer peripheral surface of the contact portion 412 of the compression jig 410, detection is performed. The axis P of the element 10 is aligned with the axis O of the metal shell 50.

  Next, as shown in FIG. 10, a downward pressure is applied to the compression jig 410 by driving the elevating device 400, and the sleeve is passed through the caulking packing 29 of the intermediate assembly 300 by the tip surface of the abutting portion 412. 27 is pressed downward. The sleeve 27 presses the talc ring 26 downward, whereby the talc ring 26 is crushed into powder and the gap in the through hole 58 of the metal shell 50 is filled. At this time, since the rear end portion 12 of the detection element 10 is held by the holding jig 420 as described above, the compression deformation of the talc ring 26 is caused in the radial direction of the rear end portion 12 of the detection element 10. The movement is restricted and the axis O of the metal shell 50 and the axis P of the detection element 10 are kept aligned. In this way, the detection element 10 is positioned in the through hole 58 and integrated with the metal shell 50 (filling member compression step). Since a pressing force is also applied to the talc ring 22 that has been compressed and deformed in advance in the metal cup 20, the central portion 13 of the detection element 10 is held more firmly by the talc ring 22.

  As shown in FIG. 11, the holding of the rear end portion 12 of the detection element 10 by the first holding claw 421 and the second holding claw 422 of the holding jig 420 is released (regulation release process). As shown in FIG. 12, the lifting device 400 is driven upward, and the compression jig 410 and the holding jig 420 are separated from the intermediate assembly 300. The detection element 10 is maintained in a state where its own axis P is aligned with the axis O of the metal shell 50.

  Further, as shown in FIG. 13, a caulking jig 450 is disposed above the intermediate assembly 300 in place of the compression jig 410 and the holding jig 420, and the caulking jig 450 is moved downward. The crimping portion 53 of the metal shell 50 is brought into contact with a processing surface 451 (having a hole through which the rear end portion 12 of the detection element 10 is inserted in the center) formed on the front end side of the crimping jig 450. It is contacted and bent inward along the processing surface 451. The caulking portion 53 is deformed so that the inner peripheral surface abuts on the caulking packing 29 and presses the sleeve 27 downward (front end side) via the caulking packing 29. Thereafter, even if the crimping jig 450 is moved away from the intermediate assembly 300, the deformation of the crimping portion 53 is maintained. The stress accompanying the deformation of the caulking portion 53 is also applied to the detection element 10, but the detection element 10 is firmly positioned and held in the metal shell 50 by the talc ring 22 as described above. Axis deviation between the axis O and the axis P of the detection element 10 is suppressed. Thus, the detection element 10 is securely held in the metal shell 50 and fixed to the metal shell 50 (element fixing step). The outer cylinder 65, the separator 60, the grommet 75, etc. shown in FIG. 1 are assembled to the completed intermediate assembly 300 in this way, and the gas sensor 1 is completed.

[Example 1]
Thus, when compressing and deforming the talc ring 26 interposed between the metal shell 50 and the detection element 10 and integrating them, the rear end portion 12 of the detection element 10 is held by the holding jig 420. An evaluation test was conducted to confirm the effects of the above. In this evaluation test, according to the manufacturing method described in this embodiment, a sample of an intermediate assembly assembled by holding the rear end portion of the detection element with a holding jig and compressing and deforming the talc ring with a compression jig. Ten (with holding) were produced. In addition, as a comparative example, in the above manufacturing method, a sample of an intermediate assembly (without holding) assembled by performing compression deformation of the talc ring with a compression jig without holding the rear end portion of the detection element with the holding jig. Ten were produced. Next, each sample of the produced intermediate assembly is photographed from the rear end side of the detection element along the axis O of the metal shell, and the position of the axis P of the detection element and the metal shell are obtained for each of the obtained images. The position of the axis O was specified. As an example, the position of the axis P may be a position of an intersection of lines connecting opposite corners of the rear end face of the detection element. Further, the position of the axis O may be a center position guided from the inner periphery of the through hole of the metal shell.

  And from each image, the distance (eccentricity) between the position of the axis O in the width direction of the detection element of each sample and the position of the axis P was measured. Similarly, from each image, the distance (eccentricity) between the position of the axis O and the position of the axis P in the thickness direction of the detection element of each sample was also measured. From the measured results, the eccentricity in the width direction of the detection element is classified into the sample of the intermediate assembly assembled with the holding jig held and the sample without the holding, and shown in the graph 14 shows. Further, the eccentricity in the thickness direction of the detection element is classified in the same manner and shown in a graph in FIG.

  In the sample in which the rear end portion of the detection element is not held at the time of assembling the intermediate assembly, the eccentric amount in the width direction of the detection element is in the range of about −0.3 mm to about 0.2 mm as shown in FIG. Scattered around. Further, as shown in FIG. 15, the amount of eccentricity in the thickness direction of the detection element was scattered in a range of about −0.4 mm to about 0.4 mm. In contrast, in the sample in which the rear end portion of the detection element is held at the time of assembling the intermediate assembly, the eccentricity in the width direction of the detection element is about −0.1 mm to about 0.1 mm as shown in FIG. Was in the range. Further, the amount of eccentricity in the thickness direction of the detection element was within the range of about −0.2 mm to about 0.2 mm as shown in FIG. 15. As apparent from the results of this evaluation test, the rear end portion of the detection element is held during the assembly of the intermediate assembly, thereby effectively suppressing the misalignment between the axis O of the metal shell and the axis P of the detection element. It was confirmed that it was possible.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. The holding jig 420 of the present embodiment is configured to hold the rear end portion 12 of the detection element 10 from both sides in the thickness direction and the width direction using the first holding claws 421 and the second holding claws 422. The holding claw 421 and the second holding claw 422 do not necessarily have to contact the rear end portion 12 of the detection element 10. That is, in the filling member compression step, the radial direction of the rear end portion 12 of the detection element 10 is adjusted so that the deviation between the axis O of the metal shell 50 and the axis P of the detection element 10 is within a tolerance range that is allowed in advance. Any device that can suppress (regulate) the displacement is acceptable.

  Further, the movement of the rear end portion 12 of the detection element 10 in the thickness direction and the width direction is regulated by the first holding claw 421 and the second holding claw 422, but the rear end portion 12 of the detection element 10 is grasped by one holding claw. The structure which regulates the movement to radial direction by hold | maintaining reliably may be sufficient. Or you may enable it to control the movement to the whole radial direction using the control member of the form which covers the rear-end part 12 of the detection element 10. FIG.

  In the present embodiment, the case where the axis O of the metallic shell 50 and the axis P of the detection element 10 are aligned has been described. However, the present invention is not limited to the axis alignment, and the relative alignment between the two is performed. It may be.

  The present invention can be applied to a method for manufacturing a gas sensor such as an oxygen sensor, a NOx sensor, or an HC sensor using a TF (Thick Film) type element.

1 is a longitudinal sectional view of a gas sensor 1. FIG. 1 is a perspective view of a detection element 10. FIG. 3 is a perspective view of an element unit 210. FIG. 4 is an exploded perspective view for explaining an element holding step for assembling the element unit 210 to the metal fitting assembly 250. FIG. 5 is a longitudinal sectional view showing a state in which an intermediate assembly 300 in which an element unit 210 is assembled to a metal fitting assembly 250 is placed on an element base 350. FIG. 6 is a longitudinal sectional view showing a state before holding the rear end portion 12 of the detection element 10 by a holding jig 420. FIG. It is the figure which expanded the circle A of FIG. It is the figure which projected the 1st holding nail | claw 421, the 2nd holding nail | claw 422, and the rear-end part 12 of the detection element 10 on the plane orthogonal to the axis line R of the holding jig 420, and showed each positional relationship. It is the figure which projected the 1st holding nail | claw 421, the 2nd holding nail | claw 422, and the rear-end part 12 of the detection element 10 on the plane orthogonal to the axis line R of the holding jig 420, and showed each positional relationship. 4 is a longitudinal sectional view showing a state in which a load is applied to the talc ring 26 of the intermediate assembly 300. FIG. 6 is a longitudinal sectional view showing a state in which the holding of the rear end portion 12 of the detection element 10 by the holding jig 420 is released. FIG. FIG. 6 is a longitudinal sectional view showing a state where the compression jig 410 and the holding jig 420 are moved away from the intermediate assembly 300. FIG. 6 is a longitudinal sectional view showing a state in which the crimping portion 53 of the intermediate assembly 300 is crimped by the crimping jig 450. It is the graph which classified about the amount of eccentricity in the width direction of a detection element with the sample of the intermediate assembly assembled in the state with holding with a holding jig, and the sample without holding. It is the graph which classified about the eccentric amount in the thickness direction of a detection element with the sample of the intermediate assembly assembled in the state with holding with a holding jig, and the sample without holding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas sensor 10 Detection element 12 Rear-end part 24 Flange part 26 Tales ring 50 Metal fitting 53 Caulking part 54 Step part 58 Through-hole 421 1st holding claw 422 2nd holding claw

Claims (5)

A plate-like detection element extending in the axial direction;
A flange portion integrally assembled in a form surrounding the detection element;
A metal shell having a through hole extending in the axial direction for inserting the detection element, and protruding inward in the radial direction from the inner peripheral surface of the through hole, and having a step portion engaged with the flange portion. A method for manufacturing a gas sensor, comprising:
An element holding step of inserting the detection element into the through-hole of the metal shell, supporting the flange portion on the stepped portion, and holding the detection element in the metal shell;
A restricting member disposing step of disposing a restricting member that restricts movement of the trailing end portion of the detection element in the radial direction after contacting the element with the back end portion of the detecting element;
After the restricting member arranging step, the filling member loaded between the inner peripheral surface of the metal shell and the outer peripheral surface of the detection element on the rear end side from the flange portion is pressed toward the front end side in the axial direction, and the filling is performed. A filling member compression step for compressing the member;
After the filling member compression step, the rear end portion of the metal shell is pressed from the outside and bent inward in the radial direction, so that at least the flange portion and the filling member are located between the rear end portion and the stepped portion. A gas sensor manufacturing method comprising: an element fixing step of holding the detection element in the metal shell. The filling member has a solid shape obtained by pressing and compacting powder in an annular shape,
Before the filling member compression step, it remains in a solid shape, is covered around the detection element and is loaded on the inner periphery of the metal shell,
The filling member compressing step is crushed into powder, filling a gap between the inner peripheral surface of the metal shell and the outer peripheral surface of the detection element, and being compacted. The manufacturing method of the gas sensor of description.   The restriction release process for releasing the restriction of the radial movement of the rear end of the detection element is performed after the filling member compression process and before the element fixing process. A method for manufacturing a gas sensor.   The gas sensor according to any one of claims 1 to 3, wherein the restricting member restricts movement of the detection element in a radial direction by holding the rear end portion of the detection element. Production method. The regulating member is
A first regulating member that regulates movement of a rear end portion of the detection element in the thickness direction of the detection element;
A second regulating member that regulates movement of the rear end of the detection element in a direction perpendicular to the plate thickness direction;
The restricting member arranging step includes
A first restricting member disposing step of disposing the first restricting member in contact with or away from both sides of the rear end portion of the detection element in the plate thickness direction;
After the first restricting member disposing step, a second restricting member disposing step of disposing the second restricting member in contact with or apart from both sides of the rear end portion of the detection element in the direction orthogonal to the plate thickness direction. The method for manufacturing a gas sensor according to claim 1, wherein:

Images