JP4729427B2 - Manufacturing method of gas sensor - Google Patents

Description

  The present invention relates to a method for manufacturing a gas sensor (hereinafter also simply referred to as a sensor) such as an oxygen sensor for detecting an oxygen concentration in a gas to be measured such as exhaust gas discharged from an internal combustion engine or the like.

  As a typical example of this type of gas sensor, there is one described in Patent Document 1 having a structure as shown in FIG. The oxygen sensor 1 has an inner electrode (layer wall) 22a and an outer electrode surface (outer wall surface) 22b on its inner peripheral surface (inner wall surface) 22a and outer electrode (layer), respectively. A detection element (hereinafter also simply referred to as element) 21 made of a shaft-like (cylindrical) solid electrolyte, and a metal fitting body (also referred to as a main metal fitting) 11 that holds the detection element 21 inside and is attached to an exhaust gas pipe. Etc. The oxygen sensor 1 is attached to an exhaust gas pipe of an internal combustion engine through a metal fitting body 11, and detects an internal electrode (reference electrode) in contact with a reference gas (atmosphere) and an external electrode (measurement electrode) in contact with exhaust gas. An electromotive force is generated between both electrodes corresponding to the difference in oxygen concentration between the inner and outer surfaces of the element 21, a signal based on the electromotive force is output to the control circuit, and the oxygen concentration in the exhaust gas is detected to control the air-fuel ratio. Used to.

  In the final assembly of the process for manufacturing such a sensor, as shown in the lower left of FIG. 7, an element-side subassembly 201 in which the element 21 is coaxially fixed in the metal fitting body 11 is manufactured. On the other hand, as shown in the upper left of the figure, the inner peripheral surface terminal fitting 71 and the outer peripheral surface terminal fitting 91 (hereinafter also referred to as the respective terminal fittings 71 and 91) to be connected to the internal electrode and the external electrode of the element 21. Are manufactured by assembling the terminal fitting side sub-assemblies 301 and the like, as shown on the right side of FIG. Here, as shown in FIGS. 8A and 8B, each of the terminal fittings 71 and 91 is formed by bending a thin metal plate or the like. Cylindrical connection portions 73 and 93 having a C-shaped cross section with a slit (M) are provided. And the relay line parts 74 and 94 extended from the rear end (illustration upper end) 73a and 93a of each cylindrical connection part 73 and 93 to the rear end side are provided. That is, as shown in FIG. 7, the assembly of both the subassemblies 201 and 301 is performed in the terminal metal side subassembly 301 at the rear end (the upper end in the drawing) 25 of the element 21 of the element side subassembly 201. The cylindrical connection portions 73 and 93 of the terminal fittings 71 and 91 are positioned (centered). Then, both the semi-assemblies 201 and 301 are moved so as to be close to each other in the axis G direction. That is, the cylindrical connecting portion 73 of the inner peripheral surface terminal fitting 71 is located inside the portion near the rear end 25 of the element 21, and the cylindrical connecting portion 93 of the outer peripheral surface terminal fitting 91 is located near the rear end 25 of the element 21. Each of them was pushed at a time at a predetermined pushing speed at the same time by a pressurizing device. In this sensor, the terminal fittings 71 and 91 are connected to the electrodes of the element 21 by such an assembly process.

Here, in the terminal fitting side subassembly 301, the cylindrical connection portions 73 and 93 in the respective terminal fittings 71 and 91 are substantially coaxial with the distal end surface 112 of the terminal fitting holding member 111, which is called a cylindrical separator made of an insulating material. The relay wire portions 74 and 94 extending from the rear ends of the respective cylindrical connection portions 73 and 93 are passed through holes formed in the terminal metal fitting holding member 111 in a penetrating manner. . On the other hand, each of the cylindrical connecting portions 73 and 93 is disposed so that the rear ends 73 a and 93 a abut against the front end surface 112 of the terminal metal fitting holding member 111. Among the terminal fittings 71 and 91, the outer peripheral surface terminal fitting 91 has an inner diameter in the free state of the cylindrical connecting portion 93 smaller than the outer diameter of the rear end 25 portion of the element 21. When it is externally fitted to the part near the rear end 25 of the element 21, it is elastically deformed into a diameter-expanded shape due to the spring property and is tightened on the outer peripheral surface 22 b of the element 21 so as to be electrically connected to the external electrode. It is configured. For this reason, for example, teeth 98 that are spread outward are provided at the distal end (lower end in FIG. 8) 93b of the cylindrical connecting portion 93 so as to guide the outer fitting, and the element 21 has a rear end surface 25 and an outer peripheral surface. A chamfer 27 (see FIG. 6) is provided at the corner of 22b, and smoothing of the push-in is achieved.
JP 2004-53425 A

  However, the cylindrical connecting portions 73 and 93 of the terminal fittings 71 and 91 are positioned at the rear end 25 of the element 21 in the element-side subassembly 201, and the cylindrical connecting portions 73 and 93 are connected to the element. When the outer peripheral surface fitting 91 is fitted (externally fitted) so as to be pushed into the portion closer to the rear end 25, there are the following problems to be solved. Before explaining this problem, in assembling both the semi-assemblies 201 and 301, FIG. 9 shows the element 21, the outer peripheral terminal fitting 91, and the terminal fitting holding member 111 into which the element 21 is incorporated. Based on this, the pushing process will be described. Hereinafter, in the present specification, when simply referred to as “terminal fitting”, the outer peripheral face terminal fitting in which the cylindrical connecting portion 93 is fitted (externally fitted) to the outer peripheral face 22 b near the rear end 25 of the element 21. 91 shall be designated.

  In order to fit (externally fit) the cylindrical connecting portion 93 of the terminal fitting 91 to the outer peripheral surface 22b near the rear end 25 of the element 21, the cylindrical connecting portion 93 is pushed against the rear end portion of the element 21. When inserting, first, as shown in FIG. 9-A, the element 21 and the cylindrical connecting portion 93 of the terminal fitting 91 are vertically separated by using a positioning jig (not shown) so that the axes G thereof coincide with each other. Perform positioning in the It is assumed that the rear end (upper end in the figure) 93a of the cylindrical connection part 93 of the terminal fitting 91 is concentrically supported by the distal end surface 112 of the cylindrical terminal fitting holding member 111. Next, using a pressure device (press device) (not shown), the terminal fitting holding member 111 is pushed down to bring the cylindrical connection portion 93 together with the terminal fitting holding member 111 into the rear end portion of the element 21 with a predetermined load and speed. Then, press a predetermined stroke at a time. As a result, while being pushed in as shown in FIG. 9-B, the cylindrical connecting portion 93 is finally moved to a portion closer to the rear end 25 of the element 21 as shown in FIG. 9-C. Insertion amount) S is pushed in and externally fitted. In this specification, pushing the cylindrical connecting portion 93 into the rear end 25 of the element 21 (a portion closer to the rear end 25) means that the cylindrical connecting portion 93 is moved relative to the fixed element 21. This includes not only pushing and pushing but also moving and pushing the element 21 with respect to the fixed cylindrical connecting portion 93 and moving and pushing both of them.

  Next, problems to be solved in this pushing will be described. In the case of such pushing, after the pushing (after fitting), as shown in FIG. 9-C, the cylindrical connecting portion 93 is closer to the tip 93b side, that is, closer to the rear end 25 of the element 21. While the distal end 93b side located on the inlet side when the part starts to be pushed in is expanded, the rear end 93a located on the distal end surface 112 side of the terminal fitting holding member 111 is not expanded, and the cylindrical connecting portion 93 is longitudinally sectioned. As seen in FIG. 2, the state is deformed into a “<” shape (plastic deformation), or the cylindrical connecting portion 93 is fitted in a “C” shape in the longitudinal section. That is, after the fitting, as shown in FIG. 9C, a gap K is generated on the outer peripheral surface 22b near the rear end 25 of the element 21 and on the portion near the front end 93b of the cylindrical connecting portion 93. there were. For this reason, the inner peripheral surface of the cylindrical connection portion 93 is not correctly pressed against the external electrode, and thus a desired electrical connection cannot be obtained, resulting in poor bonding (contact failure).

  Under these circumstances, the present inventors have come to know the following by analyzing the indentation process. When the pushing of the terminal fitting 91 is started and the inside of the tip 93b of the cylindrical connecting portion 93 comes into contact with the outside of the rear end 25 of the element 21, at the same time, the rear end 93a of the cylindrical connecting portion 93 becomes a terminal fitting holding member. It is strongly and strongly pressed against the tip surface 112 of 111. Therefore, the subsequent pushing is performed in a state where the rear end 93a of the cylindrical connecting portion 93 is strongly pressed against the front end surface 112 of the terminal metal fitting holding member 111 in this way. That is, in the middle of the pushing, the cylindrical connecting portion 93 is pushed in such a way as to spread the cut M by the corner 27 (see FIG. 6) at the rear end of the element 21. At this time, since the portion closer to the tip 93b of the cylindrical connecting portion 93 is a free end, the diameter can be easily expanded (deformed). Therefore, the cylindrical connecting portion 93 has a truncated cone (taper) having a rear end 93a having a small diameter. It deforms into a shape. On the other hand, the portion near the rear end 93a of the cylindrical connecting portion 93 is deformed so as to be reduced in diameter by the reaction of the portion close to the tip 93b being expanded (deformed), and at the same time, the rear end 93a is the tip surface of the terminal fitting holding member 111. Since it is strongly pressed to 112, it is difficult to easily expand the diameter. That is, in the middle of the pushing, the rear end 93a of the cylindrical connecting portion 93 is strongly pressed against the tip end surface 112 of the terminal metal fitting holding member 111 or tends to bite, so that until the pushing is completed, It cannot slide freely along surface 112 outward. This is the reason why the cylindrical connecting portion 93 is buckled and deformed (hereinafter also referred to as abnormal deformation) in a vertical cross section in the case of the conventional pushing process, so to speak. .

  The present invention has been made for the purpose of solving such a problem. In the assembly of the sensor, when the cylindrical connection portion of the terminal fitting for the outer peripheral surface is fitted to the rear end of the element by pressing, the cylinder It is an object of the present invention to provide a manufacturing method in which the connecting portion can be fitted without causing abnormal deformation.

In order to achieve the above object, the invention according to claim 1 is characterized in that the inner peripheral surface terminal fitting is provided on each of the electrodes formed on the inner peripheral surface and the outer peripheral surface of the detection element having a hollow shaft shape with a closed tip. And a gas sensor in which the outer peripheral terminal fitting is electrically connected,
The outer peripheral terminal fitting has a cylindrical connecting portion having a cut on one side, and this cylindrical connecting portion has its own spring property when the rear end portion of the detection element is pushed inside. It is formed so as to elastically deform into an expanded diameter by
In addition, the cylindrical connection portion is supported so that the rear end of the cylindrical connection portion itself contacts the front end surface of the terminal metal fitting holding member made of an insulating material, and is inward from the front end side of the cylindrical connection portion. In a method of manufacturing a gas sensor in which the outer peripheral surface terminal fitting is connected to an electrode formed on the outer peripheral surface of the detection element by a pressing process of pressing the rear end portion of the detection element,
After the pushing is started, the rear end of the cylindrical connecting portion is pressed against the front end surface of the terminal metal fitting holding member, and the front end side of the cylindrical connecting portion is deformed to have an enlarged diameter. In addition, a pushing stop process for stopping the pushing is performed at least once.

  The invention according to claim 2 is characterized in that the indentation stopping step is inserted between 30% and 70% of the indentation stroke after the initiation of indentation. It is a manufacturing method. And, in the invention described in claim 3, in place of inserting a pushing stop step of stopping the pushing in claim 1, the pushing is stopped, and the rear end of the cylindrical connecting portion is the terminal. A method for manufacturing a gas sensor, comprising: a pushing release process for releasing a state of being pressed against a distal end surface of a metal holding member. Furthermore, the invention according to claim 4 is characterized in that the indentation releasing step is inserted after the start of indentation between 30% and 70% of the indentation stroke. It is a manufacturing method.

  In the manufacturing method of the present invention, as in the prior art, the terminal fitting is not pushed once against the element, that is, it is pushed once (at once) at a predetermined speed by one pushing step to finish the pushing. In the middle of the pushing process (stroke), a pushing stop process for stopping the pushing is performed at least once. That is, in a state where the rear end of the cylindrical connecting portion is pressed against the front end surface of the terminal metal fitting holding member, the cylindrical connecting portion has a diameter-expanded shape due to its spring property due to the slit (slit) at the front end. Although it is elastically deformed to a vertical cross section, when the pushing is stopped in the middle of this pushing process, the state where the rear end of the cylindrical connecting portion is pressed against the tip surface of the terminal fitting holding member is temporarily To be released. With this release of the pressing, the rear end of the cylindrical connecting portion pressed against the front end surface of the terminal metal fitting holding member is not expanded compared to the front end side, and the expanded portion near the front end where the diameter has been expanded. It can be elastically deformed by its own spring property so as to follow radial deformation. In other words, by releasing the pressing, the cylindrical connecting portion can be deformed to expand its diameter on the rear end side in the same manner as the front end side. It approaches a cylindrical shape. Therefore, for example, in the case where the pushing end is pushed into the cylindrical connecting portion in such a state, and the pushing is completed by pushing the rear end portion of the element, the pushing stopping process can be performed as in the conventional case. In addition, it is possible to make it difficult to cause abnormal deformation (plastic deformation) in the cylindrical connecting portion as compared with the case where the tube is pushed once.

  That is, in the gas sensor manufactured by the manufacturing method of the present invention, abnormal deformation (plastic deformation) occurs in the cylindrical connection portion when the cylindrical connection portion of the outer peripheral surface terminal fitting is fitted to the rear end of the element by pressing. Is effectively prevented. As a result, the occurrence of poor connection (contact failure) between the terminal fitting and the electrode is reduced, so that a highly reliable sensor can be obtained.

  In the first aspect of the present invention, after the pushing is started, the rear end of the cylindrical connection portion is pressed against the front end surface of the terminal metal fitting holding member, and the front end side of the cylindrical connection portion is enlarged in diameter. In the middle of the pushing process that is deformed into a shape, a pushing stop process that stops the pushing is performed at least once to complete the pushing. That is, the pressing stop process may be performed once, but may be performed a plurality of times (a single pressing stroke may be divided into three or more times). If the pressing stop process is set to one time, and abnormal deformation cannot be prevented by pressing at once after the stop, the pressing stop process may be performed multiple times. In addition, the number of times (the number of times of pressing stop) may be set appropriately so that abnormal deformation does not occur in accordance with the degree of diameter expansion of the cylindrical connecting portion during pressing.

  Hereinafter, the best mode for carrying out the method for producing a gas sensor of the present invention will be described in detail with reference to FIGS. However, in the present embodiment, a gas sensor (a full-range air-fuel ratio sensor for detecting the oxygen concentration in exhaust gas) manufactured in the above-described conventional manufacturing method will be described. The terminal fitting side subassembly 301 will be described in detail.

  The element-side subassembly 201 is configured as follows (see the left diagram in FIG. 1). A cylindrical (hollow circular axis) detection element having electrodes (layers) (not shown) on the inner and outer peripheral surfaces 22a and 22b on the inner side of the stepped cylindrical metal body 11 and closed at the tip. 21 is fixed airtight. The element 21 includes a large-diameter portion 23 having a large outer diameter at the intermediate portion, and the tip protrudes from the tip of the metal fitting body 11. In this element 21, an insulating ring 52 is disposed on a step portion inside the metal fitting body 11 via a washer 51, and a large-diameter portion 23 is placed in a recess on the inner peripheral edge of the insulating ring 52 in the illustrated upper portion with a plate packing (not shown). The seal material 53 is compressed and airtightly fixed in the metal fitting body 11 with a seal material (talc) 53 and a pressing ring 54 interposed therebetween. This fixing is performed by arranging a flat washer 55 at the rear end of the pressing ring 54 inside the rear end (the upper end in the figure) of the main body 11 and bending the end of the thin cylindrical portion 18 at the rear end of the main body 11 inward. By caulking to compress the tip side.

  The main body 11 is provided with a screw-in polygon portion 12 on the outer periphery of the intermediate portion in the vertical direction in the figure, and a screw portion 14 for screwing into the exhaust pipe and a small-diameter cylindrical portion 16 are sequentially provided on the tip side thereof. A protective cover 20 with a vent hole for protecting the tip of the projecting element 21 is attached to the small diameter cylindrical portion 16. Further, a thick cylindrical portion 17 is provided between the polygonal portion 12 and the thin cylindrical portion 18 at the rear end. The thick cylindrical portion 17 includes a casing constituting a terminal fitting side subassembly 301 described later. A large-diameter portion 32 on the distal end side of the protective cylinder 31 is configured to be fitted. The hollow portion, which is the inner side of the detection element 21, has a circular cross section and has a tapered shape that is slightly reduced in diameter toward the tip, and is concentric with the axis G of the main body 11. Further, chamfers 26 and 27 are attached to the corners of the rear end 25 of the detection element 21 and the inner and outer peripheral surfaces 22a and 22b, respectively. A guide when assembling by being internally or externally fitted to the end 25 is formed. A sealing washer 9 is fitted between the screw-in polygon portion 12 and the screw portion 14 of the main body 11.

  Next, the terminal metal fitting side subassembly 301 will be described based on the right side of FIG. This device incorporates an inner peripheral surface terminal fitting 71 and an outer peripheral surface terminal fitting 91 to be connected to the electrodes on the outer peripheral surfaces 22a and 22b. As shown on the right side of the figure, the terminal fitting side sub-assembly 301 is provided with a terminal fitting holding member made of an insulating material (insulating each terminal fitting in a cylindrical tube with a different diameter (stepped cylindrical shape). It is held and positioned, and is provided with 111 (also called a separator). The terminal fitting holding member 111 has a substantially columnar shape, and the cylindrical connection portions 73 and 93 of the terminal fittings 71 and 91 are concentric with the front end surface 112 of the terminal fitting holding member 111 so that the rear ends 73a and 93a are in contact with each other. Are arranged. The terminal fittings 71 and 91 are the same as those shown in FIG. 8 as described above, and have the relay wire portions 74 and 94 extending rearward from the rear ends 73a and 93a of the cylindrical connection portions 73 and 93, respectively. The terminal metal holding member 111 is positioned and held through a hole provided so as to penetrate the terminal metal holding member 111. Lead wires 41 are connected to connection end portions (connector portions) 75 and 95 at the rear ends (upper end in FIG. 1) of the respective relay wire portions 74 and 94, respectively. The outer diameter of the cylindrical connecting portion 73 is larger than the inner diameter of the element 21 in the free state, and the inner diameter of the cylindrical connecting portion 93 is smaller than the outer diameter of the portion near the rear end of the element 21 in the free state. These are formed so as to be pressed against the outer peripheral surface of the part close to the rear end 25 of the element 21 in a contracted shape or elastically deformed to each shape from their own spring property. A seal member 131 is fitted into the rear end (the upper end in the drawing) of the protective cylinder 31 and on the rear end of the terminal fitting holding member 111, and the lead wire 41 penetrates the seal member 131. In this way, it is drawn outward (upward in the figure). A ventilation member 102 is fitted in the center of the sealing material 131.

  In this embodiment, a rod-shaped heater 61 inserted into the element 21 is provided at the center of the distal end side of the terminal metal fitting side subassembly 301. Then, the portion near the rear end of the heater 61 is passed through the inside of the cylindrical connecting portion 73 of the terminal fitting 71 and is held by the heater holding portion 88 that is slightly narrowed at the tip of the cylindrical connecting portion 73. Thus, the terminal fitting holding member 111 is inserted into a hole provided along the axis G in the center of the front end surface 112. Then, the lead wire 41 is connected to the terminal 64 provided near the rear end of the heater 61, and the hole provided in the terminal fitting holding member 111 is not shown in detail, as in the case of the lead wire 41 described above. And drawn out through the sealing material 131. Further, a flange 122 is provided on the outer peripheral surface of the terminal fitting holding member 111, and the protective cylinder is formed at the tip-facing surface of the inwardly projecting portion 36 formed so as to protrude inwardly at the small diameter portion 33 of the protective cylinder 31. Positioning in the axial direction within 31 is performed. Further, a cylindrical member 141 bent inwardly at the rear end is interposed on the front surface side of the flange 122, and the outer peripheral surface of the cylindrical member 141 is covered by the small diameter portion 33 of the protective cylinder 31. A terminal metal fitting holding member 111 is provided on the inside.

  FIG. 2 is a longitudinal sectional view showing the terminal metal half assembly 301 in the middle of assembly. In this state, the lead wire 41 is pulled out from the rear end (upper end in the figure) of the protective cylinder 31. The terminal ends 71 and 91 of the terminal fittings 71 and 91 are supported so that the rear ends of the cylindrical connecting portions 73 and 93 are in contact with the front end surface 112 of the terminal fitting holding member 111. By pushing the inner side of the rear end of the portion 33, the terminal fitting side subassembly 301 shown on the right side of FIG. 1 is obtained. In this embodiment, leaf spring-like projecting pieces 77 and 97 are provided on the relay wire portions 74 and 94 in the terminal fittings 71 and 91, respectively, and these holes are provided in the terminal fitting holding member 111. The cylindrical connection portions 73 and 93 are set so as to be positioned concentrically on the front end surface 112 of the terminal fitting holding member 111. FIG. 3 is a view seen from the distal end side showing the positional relationship in which the cylindrical connection portion 93 of the outer peripheral surface terminal fitting 91 is disposed on the distal end face 112 of the terminal fitting holding member 111.

  Next, a process for manufacturing the sensor by assembling such an element side subassembly 201 and a terminal metal part subassembly 301 will be described as described in the conventional manufacturing method (the left diagram of FIG. 7). Reference), positioning is performed in a state of being vertically separated using a positioning jig (not shown) so that the axial lines G of both the semi-assemblies 201 and 301 coincide with each other. And as shown in the right figure of FIG. 7, the shoulder part located in the boundary of the large diameter part 32 and the small diameter part 33 of the protection cylinder 31 was shown with the arrow using the pressurization apparatus (press apparatus) which is not shown in figure. As shown in the figure, the terminal fitting holding member 111 and the cylindrical connecting portions 73 and 93 are fitted to the inner and outer peripheral surfaces near the rear end 25 of the element 21, respectively, and the large-diameter portion 32 of the protective cylinder 31 is the main body. 11 so as to be fitted on the thick cylindrical portion 17 and pushed. However, in this pushing process, the rear end portion of the detection element 21 is pushed into the inner side of the cylindrical connecting portion 93 in the outer peripheral surface terminal fitting 91 instead of pushing all at once. When the pressing amount is about half (40% to 60%), the pressing is temporarily stopped, and the pressing is completed by pressing again after a short time.

  Thus, in the sensor manufacturing method of the present invention, as in the prior art, the cylindrical connection portion 93 itself is supported in such a manner that the rear end 93a abuts against the front end surface 112 of the terminal fitting holding member 111. In this state, the outer peripheral surface terminal fitting is connected to the outer peripheral surface of the detection element by pressing the portion closer to the rear end 25 of the detection element 21 inward from the distal end 93b side of the cylindrical connection portion 93. In the pushing process, after the pushing is started, the rear end 93a of the cylindrical connecting portion 93 is connected to the tip surface 112 of the terminal fitting holding member 111. A pressing stop process for stopping the pressing is included in the middle of the pressing process in which the tip 93b side of the cylindrical connecting portion 93 is deformed to have an increased diameter. As a result, abnormal deformation of the cylindrical connecting portion 93 is prevented.

  That is, the pushing process will be described with reference to FIG. 4 showing the element 21, the outer peripheral surface terminal fitting 91 and the terminal fitting holding member 111 into which the element 21 is incorporated. As shown in FIG. 4A, together with the terminal fitting holding member 111, the cylindrical connecting portion 93 of the outer peripheral surface terminal fitting 91 is concentric with the portion closer to the rear end 25 of the element 21, Then, as shown in FIG. 4B, the push-in is started, and the tubular connecting portion 93 is fitted to the portion near the rear end 25 of the element 21 so that the rear of the element 21 is placed inside the tubular connecting portion 93. The part closer to the end 25 is pushed in at a stroke until it reaches about half of the set pushing amount S, and the pushing is stopped. In the process of pushing and stopping in this way, the rear end 93a of the cylindrical connection part 93 is pressed against the front end surface 112 of the terminal metal fitting holding member 111, and at the same time, the front end 93b of the cylindrical connection part 93 has its break ( Due to the presence of the slit) M, the cylindrical connecting portion 93 is elastically deformed into a diameter-expanded shape due to the spring property, so that the cylindrical connecting portion 93 has a vertical cross-sectional shape as shown in FIG.

  And since the state where the rear end 93a of the cylindrical connection part 93 is pressed against the front end surface 112 of the terminal fitting holding member 111 is temporarily released by stopping this pushing, in the stopped state, As shown in FIG. 4-C, the rear end 93a of the cylindrical connecting portion 93 that has been pressed against the front end surface 112 of the terminal fitting holding member 111 is not expanded in diameter compared to the front end 93b side. Due to its own springiness, it can be deformed (elastically deformed) so as to follow the diameter-expanding deformation of the portion near the tip 93b whose diameter has been expanded. That is, by releasing the pressing, the cylindrical connecting portion 93 can be deformed to expand its diameter on the rear end 93a side as well as the front end 93b side. , Approaching a parallel cylindrical shape. And in this form, after such a pushing stop process, as shown to FIG. 4-D, the rear-end part of the element 21 is pushed into the cylindrical connection part 93 again, and the pushing is carried out. Since it has been completed, it is difficult to cause abnormal deformation (plastic deformation) in the cylindrical connecting portion 93 as compared with the prior art that is pushed once, that is, pushed in at once, without entering the pushing stop process. Therefore, the problem that a gap is generated between the electrode on the outer peripheral surface of the element 21 and the cylindrical connection portion 93 as in the prior art is solved.

  The sensor, after completion of such a pressing process, caulks and welds the large-diameter portion 32 of the protective cylinder 31 that is externally fitted to the thick-walled cylindrical portion 17 of the main body 11 in the radial direction around it, This is completed by caulking the portion corresponding to the seal material 131 near the rear end in the small diameter portion 33 and the portion corresponding to the cylindrical member 141 so as to be compressed in the radial direction. FIG. 5 shows the sensor 1 after completion. Thus, in the obtained gas sensor 1, the connection between the cylindrical connection portion 93 and the electrode (external electrode) in the fitting of the cylindrical connection portion 93 in the outer peripheral surface terminal metal fitting 91 by pressing the rear end of the element 21. Since the occurrence of defects (contact failures) can be reduced, a highly reliable sensor can be obtained.

  In addition, in the said form, although the case where the pushing stop process was made into 1 time was demonstrated, when abnormal deformation | transformation is not solved by pushing at a stretch after one stop, the pushing stop process should just be performed in multiple times. . What is necessary is just to set the frequency | count suitably according to the length of the cylindrical connection part, and the degree of the diameter expansion of the cylindrical connection part in pushing. When the pushing stop process is performed once, generally, the pushing stop is performed at an intermediate position from the start of pushing to the end of pushing, or more than 30% of the pushing stroke, 70% It is preferable to put in between.

  In the indentation stop step, the indentation load may be once reduced (release the load) at the same time or after the indentation is stopped, or the indentation stroke may be returned by a small amount. For example, in the press apparatus, when the movable platen is driven and pushed in, the movable platen may not only be stopped, but may be moved backward by a small amount and then pushed in again.

  Needless to say, the manufacturing method of the present invention is not limited to the sensor having the above-described structure but can be embodied or applied. That is, in the above, the sensor with a heater is embodied, but it is natural that the present invention can be embodied regardless of the presence or absence, and the gas sensor other than the oxygen sensor has the same structure and the same push-in. It can be widely embodied in what is manufactured through the process.

  Furthermore, in the above, after assembling the element side subassembly 201 and the terminal metal fitting side subassembly 301 as shown separately, the two subassemblies are assembled to manufacture a sensor. As described above, the present invention is not necessarily limited to the case where the rear end portion of the detection element is pushed inwardly from the front end side of the cylindrical connection portion of the terminal fitting for the outer peripheral surface after the both half assemblies are formed. Is not to be done. That is, the cylindrical connection part in the terminal fitting for the outer peripheral surface is in a state of being supported so that the rear end of the cylindrical connection part itself contacts the front end surface of the terminal fitting holding member made of an insulating material, Under this state, by pushing the rear end portion of the detection element inward from the front end side of the cylindrical connection portion, the outer peripheral surface terminal fitting is attached to the electrode formed on the outer peripheral surface of the detection element. The present invention can be widely applied in a method for manufacturing a connected gas sensor.

The element side subassembly which comprises the gas sensor manufactured with the manufacturing method of this invention, and each longitudinal cross-sectional view of a terminal metal fitting side subassembly. The figure in the middle of assembling the terminal metal fitting side subassembly. The figure seen from the front end side which showed the positional relationship by which the cylindrical connection part of the terminal metal fitting for outer peripheral surfaces is arrange | positioned in the front end surface of a terminal metal fitting holding member. The figure explaining an assembly process. The front longitudinal cross-sectional view of the gas sensor manufactured with the manufacturing method of this invention. The front longitudinal cross-sectional view and principal part enlarged view of the conventional gas sensor. The element side subassembly which comprises the conventional gas sensor, each longitudinal cross-sectional view of a terminal metal fitting side subassembly, and explanatory drawing which assembles both. It is a figure explaining the terminal metal fitting used for the conventional gas sensor, A is a perspective view of the whole terminal fitting for inner peripheral surfaces, B is a perspective view of the whole terminal fitting for outer peripheral surfaces. The figure explaining the assembly process of a gas sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas sensor 21 Detection element 22a Inner peripheral surface 22b of a detection element Outer peripheral surface 71 of a detection element Terminal fitting 91 for inner peripheral surfaces Terminal fitting 93 for outer peripheral surfaces Cylindrical connection part 93a Rear end 93b of a cylindrical connection part Tip 111 Terminal fitting holding member
112 End surface 201 of terminal metal holding member 201 Element side sub-assembly 301 Terminal metal side sub-assembly M Cut line G axis

Claims (4)

A gas sensor in which a terminal fitting for an inner peripheral surface and a terminal fitting for an outer peripheral surface are electrically connected to respective electrodes formed on an inner peripheral surface and an outer peripheral surface of a detection element having a hollow shaft shape with a closed tip. And
The outer peripheral terminal fitting has a cylindrical connecting portion having a cut on one side, and this cylindrical connecting portion has its own spring property when the rear end portion of the detection element is pushed inside. It is formed so as to elastically deform into an expanded diameter by
In addition, the cylindrical connection portion is supported so that the rear end of the cylindrical connection portion itself contacts the front end surface of the terminal metal fitting holding member made of an insulating material, and is inward from the front end side of the cylindrical connection portion. In a method of manufacturing a gas sensor in which the outer peripheral surface terminal fitting is connected to an electrode formed on the outer peripheral surface of the detection element by a pressing process of pressing the rear end portion of the detection element,
After the pushing is started, the rear end of the cylindrical connecting portion is pressed against the front end surface of the terminal metal fitting holding member, and the front end side of the cylindrical connecting portion is deformed to have an enlarged diameter. A method for manufacturing a gas sensor, comprising a step of stopping the pressing at least once.   2. The method of manufacturing a gas sensor according to claim 1, wherein the indentation stopping step is performed between the start of indentation and the intrusion stroke exceeding 30% and exceeding 70%. In claim 1, in place of inserting a pushing stop step for stopping the pushing,
A method for manufacturing a gas sensor, comprising: a step of releasing the pressing, and a step of releasing the state where the rear end of the cylindrical connecting portion is pressed against the front end surface of the terminal fitting holding member. 4. The method of manufacturing a gas sensor according to claim 3, wherein the indentation releasing step is performed between 30% and 70% of the indentation stroke after the initiation of indentation.

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