JP2008203249A - Gas sensor - Google Patents

Abstract

A gas sensor capable of making a terminal portion difficult to sag is obtained.
When the connecting end of the rod and the terminal holding insulator are assembled, at the initial stage of the assembly, the initial deformation portion 20 of the terminal portion 7 becomes a deformation region, and the repulsive force becomes relatively small. In the later stage of assembly or in the assembled state, the late-stage deformed portion 21 becomes a deformation region, and the repulsive force becomes relatively large. Since the repulsive force at the initial stage of assembly can be suppressed to a relatively small level, the terminal portion 7 can be prevented from sagging.
[Selection] Figure 2

Description

  The present invention relates to a gas sensor that electrically detects a specific gas, and more particularly to a gas sensor in which an insulator provided with a lead wire is fitted and assembled to a connection end of a base body.

  Conventionally, various gas sensors have been proposed. Patent Document 1 discloses a gas sensor as an example.

The gas sensor disclosed in Patent Document 1 includes a gas detection unit provided on one side in the axial direction and a connection end on the other side in the axial direction in which an electrode unit electrically connected to the gas detection unit is formed. A base portion and an insulator attached to a terminal portion connected to the conductor portion of the lead wire and fitted to the connecting end portion of the base portion, and the terminal portion is a surface (inner peripheral surface) of the insulator ) And the surface (outer peripheral surface) of the connecting end, and the terminal portion is sandwiched between the surface (inner peripheral surface) and the surface (outer peripheral surface). The terminal part and the electrode part are pressed against each other so that the gas detection part and the conductor part of the lead wire are electrically connected.
JP 2001-188060 A

  In the gas sensor, the terminal portion and the electrode portion are brought into pressure contact with each other by using an elastic repulsive force accompanying the deformation of the terminal portion.

  However, in the case of downsizing the gas sensor, the amount of displacement from the free state of the terminal portion to the assembled state must often be reduced due to layout constraints. Here, when the required contact pressure between the terminal portion and the electrode portion is to be secured in such a small amount of displacement, the elastic repulsive force by the terminal portion must be increased from a relatively early stage of assembly. There is a risk that it will be difficult to assemble, and it will be difficult to assemble the terminal part by inducing eccentricity or inclination of the connecting end part and the insulator by applying a pressing force against the repulsive force. It was.

  In addition, this type of gas sensor has a problem that if the vibration is large, the terminal portion is likely to sag due to the vibration.

  Therefore, an object of the present invention is to obtain a gas sensor that can obtain a sufficient contact pressure between a terminal part and an electrode part and can make the terminal part more difficult to bend.

  In the present invention, a base body having a gas detection part provided on one side in the axial direction and a connection end part on the other side in the axial direction in which an electrode part electrically connected to the gas detection part is formed on the surface. A terminal portion connected to the conductor portion of the lead wire and an insulator assembled to the connection end portion of the base portion, and the terminal portion of the surface of the insulator and the connection end portion Between the surface of the insulator and the electrode part, and the terminal part and the electrode part are pressed against each other so that the gas detection part In the method of assembling the base portion and the insulator of the gas sensor in which the conductor portion of the lead wire is electrically connected, the connection end portion and the insulator are moved toward a predetermined assembly position. Along with the relative movement in the axial direction, The most important features that it has to increase the repulsive force of the terminal portion by changing the point of contact with the insulator surface in the child unit.

  According to the present invention, when the connection end portion and the insulator are assembled, the terminal portion is moved as the connection end portion and the insulator are relatively moved in the axial direction of the base portion toward a predetermined assembly position. Since the repulsive force of the terminal is increased, the repulsive force by the terminal part can be kept relatively small in the initial stage of assembling work between the connecting end and the insulator, making assembly (fitting) work easier. Can be done. Further, since it is not necessary to apply an excessive pressing force at the beginning of the assembly work, it is difficult to cause eccentricity or inclination between the connection end portion and the insulator, and it is possible to suppress the terminal portion from being easily set. . And in the state which assembly | attachment was completed, since the repulsive force of a terminal part becomes relatively large, the required press contact force with respect to the electrode part of a terminal part can be ensured, and a contact failure etc. can be suppressed.

  Hereinafter, an embodiment of the present invention will be described. FIG. 1 is a longitudinal sectional view of a gas sensor according to the present embodiment, FIG. 2 is a sectional view of a terminal portion, and FIG. 3 is a perspective view of a terminal portion, where (a) and (b) are respectively from different directions. FIGS. 4A and 4B are sectional views showing the assembly of the rod (base portion in the present invention) and the insulator, wherein FIG. 4A shows the initial stage and FIG. 4B shows the late stage or the assembled state. 5A and 5B are diagrams showing a C-ring built in the gas sensor, where FIG. 6A is a plan view, FIG. 5B is a cross-sectional view, and FIG. 6 shows a displacement-load characteristic of a spring portion of a terminal portion. It is explanatory drawing. In the following, an example will be described in which the present invention is implemented as an oxygen sensor for air-fuel ratio detection that is mounted on an exhaust pipe of an automobile or a two-wheeled vehicle equipped with an internal combustion engine.

  As shown in FIG. 1, the oxygen sensor 1 according to the present embodiment includes a long cylindrical rod 3 and a cylindrical insulator 5 in which a terminal portion 7 and a lead wire 4 are assembled.

  A gas detection unit 2 is formed on one axial side of the rod 3 (left side in FIG. 1). Moreover, the electrode part 6 is exposed and provided in the outer peripheral surface 3b as a surface of the other axial side of the rod 3 (right side in FIG. 1). The electrode unit 6 is electrically connected to the gas detection unit 2.

  The end surface 5c on one side in the axial direction of the insulator 5 is formed with a recess 5f that is recessed toward the other side in the axial direction. A plurality of bent portions of the terminal portion 7 are arranged along the inner peripheral surface 5a of the recess 5f, and the connection end portion 3a of the rod 3 is fitted between the plurality of terminal portions 7. It has become.

  That is, in a state where the rod 3 and the insulator 5 are assembled, the portions bent in the hook shape of the terminal portion 7 are the inner peripheral surface 5a of the concave portion 5f of the insulator 5 and the outer peripheral surface 3b of the connection end portion 3a. It is arrange | positioned in the space part S formed between these, and it is clamped between the electrode part 6 exposed on the said inner peripheral surface 5a and the outer peripheral surface 3b.

  The terminal portion 7 is pressed against the electrode portion 6 by the repulsive force generated by being sandwiched in this manner, and is thus electrically connected to the electrode portion 6. The terminal portion 7 is electrically connected to the core wire 4a in the lead wire 4 via the coupling portion 14 on the other side in the axial direction. That is, the gas detection unit 2 is electrically connected to the core wire 4 a in the lead wire 4 through the electrode unit 6, the terminal unit 7, and the coupling unit 14.

  The rod 3 is inserted into the center hole 8 a of the holder 8. At this time, the gas detector 2 of the rod 3 is exposed on one side (left side in FIG. 1) of the holder 8. On the other hand, the connecting end 3a of the rod 3 is exposed on the other side (right side in FIG. 1) of the holder 8, and this connecting end 3a opens a gap S1 in the axial direction with respect to the bottom surface 5g of the insulator 5. Are to be inserted. Therefore, even when the rod 3 and the insulator 5 are assembled or after the assembly, for example, when the rod 3 moves due to vehicle vibration or the like, the rod 3 does not contact the bottom surface 5g of the insulator 5. In the state where the rod 3 and the insulator 5 are assembled, the holder 8 and the insulator 5 are abutted against each other in the axial direction, and the end surface 8c on the other side in the axial direction of the holder 8 and the axial direction of the insulator 5 The one end face 5c comes into contact with each other.

  The gas detector 2 is covered with a bottomed cylindrical protector 9 composed of double pipes 9a and 9b fixed to the holder 8 by welding (9g), caulking or the like.

  The protector 9 includes an inner protector 9a and an outer protector 9b formed of, for example, a metal material, a ceramic material, or the like. The protector 9 is disposed on the tip end side of the holder 8, and the protruding end side of the rod 3 protruding from the holder 8 is inserted on the inner peripheral side thereof.

  The distal end side 9e of the outer protector 9b is radially reduced inward in the radial direction toward the inner protector 9a, and a circular fitting that is fitted to the outer peripheral side of the inner protector 9a with a gap fit at the reduced diameter portion. A joint opening 9f is provided.

  Thus, by covering the protruding end side of the rod 3 with the inner protector 9a and the outer protector 9b, the gas detector 2 can be protected from foreign matters in the exhaust gas.

  The protector 9 is formed with a circulation hole 9c for gas circulation. The detection gas enters the protector 9 via the flow hole 9c and reaches the periphery of the gas detection unit 2.

  Further, a diameter-expanded portion 10 is formed on the other axial end side (right side in FIG. 1) of the center hole 8 a of the holder 8. An airtight gap between the rod 3 and the center hole 8a is maintained by a seal portion 11 provided in the enlarged diameter portion 10 and formed using, for example, a powder of ceramic material called steatite or talc as a filler. It has become so.

  Then, the filling member is pressurized by bending the pressing member 19 disposed in the enlarged diameter portion 10 by means of the entire circumference caulking or the like toward the radially inner side of the rod 3 by the caulking portion 8d. In this state, the rod 3 can be positioned on the holder 8. The seal 11 closes the gap between the holder 8 and the rod 3 and blocks external moisture from entering the holder 8, and exhaust gas in the exhaust pipe enters the casing 13 side. It has a function to block the performance.

  A plurality of mounting holes 12 (four in the present embodiment) are formed at equal intervals in the circumferential direction on the bottom 5b of the recess 5f of the insulator 5 in which the fixing portion 7b of the terminal portion 7 is inserted. Thus, by arranging the plurality of terminal portions 7 equally distributed in the circumferential direction, the rod 3 sandwiched between the plurality of terminal portions 7 can be easily arranged at the center of the recess 5f.

  The outer periphery of the insulator 5 is covered with a substantially cylindrical casing 13. An opening 13a on one end in the axial direction (left end in FIG. 1) of the casing 13 is fitted to the outer peripheral surface of the holder 8, and is integrally joined and sealed by laser welding or the like (13d). On the other hand, the other end (the right end in FIG. 1) side of the casing 13 is extended to cover the coupling portion 14 of the plurality of lead wires 4, and the end portion is a fluorine through which the lead wires 4 are inserted in an airtight state by the crimping portion 13c. The heat-resistant seal rubber 15 such as rubber is closed by reducing the diameter inward in the radial direction.

  The space S provided between the insulator 5 and the connection end 3a is substantially kept airtight by the seal portion 11, the seal rubber 15, and the fitting portion 13d between the casing 13 and the holder 8, Reference air used for oxygen concentration detection is introduced into the inside of the casing 13 so as to communicate with the outside through only a minute gap between the core wire 4a of the lead wire 4 and the covering material 4b.

  Although not shown in detail, the gas detector 2 includes an oxygen concentration detector and a heater. Since each of the oxygen concentration detection unit and the heater is provided with a pair of electrodes, the electrode unit 6, the terminal unit 7, and the lead wire 4 are provided in a total of four pairs of two each.

  One end portion 7 a of the terminal portion 7 is spot welded to a lead plate 14 a protruding from the coupling portion 14 of the lead wire 4.

  Further, the hook-shaped spring portion provided on the other axial side of the terminal portion 7 (left side in FIG. 1) is sandwiched between the inner peripheral surface 5a of the concave portion 5f of the insulator 5 and the electrode portion 6, and the electrode It is press-contacted to the part 6. As shown in FIG. 2 and FIG. 4A, the terminal portion 7 assembled to the insulator 5 is in a state before the rod 3 and the insulator 5 are assembled (that is, the state of FIG. 4A). The first contact portion P1 that contacts the inner peripheral surface 5a of the concave portion 5f of the insulator 5 and the one side in the axial direction from the first contact portion P1 in a state before the rod 3 and the insulator 5 are assembled (FIG. 2 and FIG. An extending portion 7e extending obliquely toward the left side in FIG. 4A and the other end in the axial direction on the one end side in the axial direction of the extending portion 7e (right side in FIGS. 2 and 4A) ) And a second contact portion P5 that contacts the electrode portion 6 on the other side in the axial direction from the folded portion 7d.

  As shown in FIG. 3, the fixing portion 7 b is formed so as to be widened in the band width direction and rounded into a substantially C-shaped section, and is fitted into the mounting hole 12 of the insulator 5.

  The base portion 7c of the hook-shaped portion extends from the fixed portion 7b toward the distal end side of the rod 3 while being slightly inclined toward the radially inward side, and is substantially V-shaped toward the radially outward direction at the second contact portion P5. It is bent and connected to the folded portion 7d on the front end side.

  Further, the extending portion 7e is bent in a substantially V shape toward the radially inward direction of the rod 3 at the first contact portion P1 in order to avoid catching with the inner peripheral surface 5a of the concave portion 5f of the insulator 5 during assembly. The distal end portion is an extension portion 7f as a free end portion.

  Moreover, in this embodiment, as shown to (a) of FIG. 4, in the state before assembling the rod 3 and the insulator 5, the terminal part 7 is the axial direction of the 1st contact part P1 and the fixing | fixed part 7b. It is supported by the insulator 5 in a substantially point contact or line contact state with a total of three points (P1, P2, P3) of two points (P2, P3) on one inner peripheral side and the other outer peripheral side. The terminal portion 7 is prevented from falling to the inner diameter side of the insulator 5 before or after the rod 3 is assembled.

  In the terminal portion 7 configured as described above, the section from the base end P6 of the base portion 7c to the first contact portion P1 functions as an initial deformation portion 20 that is elastically deformed at the initial stage of assembly of the connection end portion 3a and the insulator 5 and A section from the base end P6 of 7c to the boundary P4 between the extending portion 7e and the turned-back portion 7d functions as a late-deformed portion 21 that undergoes elasto-plastic deformation in the late stage of assembly or in the assembled state. Elasto-plastic deformation is a deformation mode having both characteristics of elastic deformation and plastic deformation.

  In addition, from the detailed examination by the inventors, in such a configuration, the inner radius R of the folded portion 7d is preferably 1.3 times or more with respect to the total displacement amount of the initial deformation portion 20 and the late deformation portion 21, Further, it has been found that the length L from the folded portion 7d to the effective end of the extending portion 7e is preferably 4.4 times or more the inner radius R. Specifically, in the present embodiment, R = 0.6 mm and L = 2.3 mm.

  The oxygen sensor 1 having the above-described configuration is attached by screwing a screw portion 8b formed at one end portion of the holder 8 into the screw hole 18a of the exhaust pipe 18, and in this state, the gas sensor covered with the protector 9 is detected. The part 2 projects into the exhaust pipe 18. A gap between the holder 8 and the outer peripheral surface of the exhaust pipe 18 is sealed with a gasket 16.

  And when the exhaust gas which distribute | circulates the inside of an exhaust pipe flows in into the inside from the flow hole 9c of the protector 9, the oxygen concentration in the gas will be detected as an electrical signal by the gas detection part 2, and the information of the electrical signal will be among 2 pairs. These are taken out through the pair of electrode portions 6, terminal portions 7, coupling portions 14, and lead wires 4. The remaining pair of electrode portions 6, terminal portions 7, coupling portions 14, and lead wires 4 are used for heating the heater in the gas detection portion 2.

  Further, when assembling the connecting end 3a and the insulator 5, as shown in FIGS. 4A and 4B, the connecting end 3a and the insulator 5 are mutually connected in the axial direction of the rod 3. In the approaching direction, the insulator 5 is relatively moved to the assembly position (FIG. 1) where the end surface 5 c of the insulator 5 abuts against the end surface 8 c of the holder 8. At this time, the connection end 3a is inserted into the recess 5f, and a plurality of (in this embodiment, arranged at 90 ° intervals in the circumferential direction of the rod 3) are arranged along the inner peripheral surface 5a of the recess 5f. The four terminal portions 7 are sandwiched.

  In this assembly, the oxygen sensor 1 according to the present embodiment is configured such that when the connection end 3a and the insulator 5 are relatively moved in the axial direction of the rod 3 toward the assembly position of FIG. ), The base portion 7c of the terminal portion 7 is pushed toward the inner peripheral surface 5a side of the recess 5f by the connecting end portion 3a of the rod 3, so that the substantially entire surface of the extending portion 7e comes into contact with the inner peripheral surface 5a. It is configured.

  Therefore, before the extending portion 7e contacts the inner peripheral surface 5a, as shown in FIG. 4A, the terminal portion 7 is sandwiched between the inner peripheral surface 5a and the outer peripheral surface 3b. The section functioning as a spring is a section from the first contact portion P1 to the base end P6 (initially deformed portion 20), and both end portions thereof are substantially in point contact or line contact, and the inner peripheral surface 5a of the insulator 5 is used. Between the extended portion 7e and the folded portion 7d, as shown in FIG. 3 (b), after the extended portion 7e is in contact with the inner peripheral surface 5a. It becomes a section (late deformation part 21) from P4 to the base end P6, and at least the extending portion 7e is in surface contact with the inner peripheral surface 5a of the insulator 5.

  That is, in this embodiment, the position where the terminal portion 7 contacts the inner peripheral surface 5a is changed by pressing the base portion 7c of the terminal portion 7 toward the inner peripheral surface 5a by the connecting end portion 3a of the rod 3 ( P1 → P1-P4), the length of the section of the terminal portion 7 that functions as a spring is shortened (between P1-P6 (initial deformation portion 20) → P4-P6 (late deformation portion 21)), As shown in FIG. 6, the rate of change (elastic coefficient) of the load (reaction force) in the direction with respect to the radial displacement of the terminal portion 7 is increased. It can be understood from FIG. 6 that the profile of the displacement-load characteristic of the terminal portion 7 in the subsequent stage shows the characteristics of elastic-plastic deformation in which the elastic coefficient changes (decreases gradually) according to the displacement.

  That is, in this embodiment, as shown in FIG. 6, before the extending portion 7e contacts the inner peripheral surface 5a, the terminal portion 7 (the initial deformation portion 20) is elastically deformed, and the extending portion 7e is formed on the inner peripheral surface. After contact with 5a, it is set so that at least a part of the terminal portion 7 (late deformation portion 21) is elastically plastically deformed. Thereby, it is possible to increase the contact pressure in the post-assembly stage while suppressing the repulsive force by the terminal section 7 relatively low in the stage before the assembly of the rod 3 and the insulator 5, improving the ease of assembly, The improvement of the adhesiveness of the part which 7 and the electrode part 6 contact mutually is aimed at.

  In this embodiment, the tip of the connecting end 3a of the rod 3 is chamfered 3c over the entire circumference. Thereby, the contact angle of the front-end | tip of the connection end part 3a and the terminal part 7 becomes shallow, and damage to the said front-end | tip or the terminal part 7 is suppressed.

  In the present embodiment, as shown in FIG. 1, a C ring 17 having a C-shaped cross section is interposed as an elastic member between the casing 13 and the insulator 5. In this embodiment, the C-ring 17 is formed in an annular shape as shown in FIG. 5A and is fitted to the insulator 5 so as to surround the outer periphery thereof. As shown in FIG. 5B, the cross-sectional shape is substantially C-shaped with the end 17a cut out.

  The C-ring 17 is sandwiched between the insulator 5 and the casing 13 to generate an elastic or elasto-plastic repulsive force. The insulator 5 is placed on the holder 8 side with respect to the casing 13, that is, on one side in the axial direction. A pressing force is generated on the left side in FIG. Thereby, the insulator 5 is firmly fixed to the end surface 8 c of the holder 8.

  Further, since the C ring 17 is sandwiched between the outer periphery of the insulator 5 and the inner periphery of the casing 13, vibration in the direction perpendicular to the central axis of the insulator 5 (vertical direction in FIG. 1) is suppressed. can do. When the level of vibration transmitted from the exhaust pipe 18 is large, especially when high-frequency vibration occurs, such as in a two-wheeled vehicle, the displacement of the insulator 5 and the terminal portion 7 increases, and the terminal portion 7 tends to sag. In this embodiment, the C ring 17 suppresses the vibration of the insulator 5 and cooperates with the effect of suppressing the vibration of the insulator 5 by the terminal portion 7. Can be suppressed.

  In the present embodiment, the outer side of the insulator 5 is positioned between the end surface 5c on the one side in the axial direction and the end surface 5d on the other side (on the other side in the axial direction, right side in FIG. 1). A step portion 5e having a small diameter is provided. The casing 13 is also provided with a step portion 13b having a small diameter toward the opposite side of the holder 8, and a C ring 17 is attached to the step portion 5e, and the C ring 17 is formed by the step portion 5e and the step portion 13b. It is designed to be pinched.

  The oxygen sensor 1 is attached by screwing a screw portion 8 b formed at one end of the holder 8 into a screw hole 18 a of the exhaust pipe 18. When the oxygen sensor is mounted on the exhaust pipe 18 of the vehicle, the amplitude of vibration transmitted from the exhaust pipe 18 increases as the distance from the exhaust pipe 18 (that is, the lead wire 4 side) increases and the closer to the exhaust pipe 18. It becomes smaller (as the fixed end). In the present embodiment, since the step portion 5e can be provided and the C ring 17 can be disposed closer to the exhaust pipe 18 side, vibration can be suppressed at a position where the amplitude is smaller. The C ring 17 can be made smaller in size.

  Furthermore, in the present embodiment, the C ring 17 is disposed on the radially outer side of the central axis of the rod 3 with respect to the terminal portions 7 so as to surround the plurality of terminal portions 7. And in this embodiment, the terminal part 7 is between the position P3 (refer FIG. 3, FIG. 4) of the base part 7b of the terminal part 7, and the position P1-P4 (FIG. 2) on the outer side of the said radial direction. To the insulator 5 at two locations (see FIG. 4). Therefore, by setting the C ring 17 around P1-P3 as in this embodiment, two vibration input positions from the insulator 5 to the terminal portion 7 (that is, between P3 and P1-P4) The vibration suppressing effect by the C ring 17 can be effectively acted on both, and the vibration of the rod 3 can be suppressed more effectively.

  Further, as shown in FIG. 7, when the C ring 17 is fixed around the contact position P <b> 1-P <b> 4 with the inner peripheral surface 5 a of the concave portion 5 f of the terminal portion 7, the insulator 5 Therefore, the vibration input to the terminal portion 7 via P1-P4 can be more effectively suppressed, and the vibration of the rod 3 can be more effectively suppressed.

  In the present embodiment, the stepped portion 5e is provided with an inclined surface that is inclined with respect to the axial direction (a tapered surface that is enlarged in diameter toward one side in the axial direction), and the C ring 17 is attached to the inclined surface. is there. For this reason, the C ring 17 can apply an elastic force to the insulator 5 both in the axial direction and in the radial direction, and both pressing the insulator 5 against the holder 8 and suppressing vibrations with a relatively simple configuration. The effect of can be obtained.

  As described above, according to this embodiment, when the connection end 3a and the insulator 5 are assembled, the connection end 3a and the insulator 5 are connected to the rod 3 toward a predetermined assembly position. As the relative movement in the axial direction changes the contact point of the terminal 5 with the inner peripheral surface 5a of the recess 5f of the insulator 5, the repulsive force of the terminal 7 increases. In the initial stage of assembly work between the connection end 3a and the insulator 5 ((a) in FIG. 3), the elastic repulsive force of the terminal section 7 can be set to be relatively small, making the assembly (fitting) work easier. Can be done.

  Since the elastic repulsive force of the terminal portion 7 can be made relatively small, the connection end portion 3a and the insulator 5 are less likely to be decentered or inclined at the initial stage of the assembling work. Can be suppressed. In addition, in the case where a plurality of terminal portions 7 are provided as in the present embodiment, a variation in contact pressure or a variation in displacement amount, that is, a stress occurs between the plurality of terminal portions 7. It can suppress that the part 7 becomes easy to sag.

  In a state where the assembly is completed (FIG. 1), since a relatively large repulsive force can be secured, a required contact pressure between the terminal portion 7 and the electrode portion 6 is ensured, and contact failure and the like are more reliably suppressed. be able to.

  Further, according to the present embodiment, the terminal portion 7 is pressed to the inner peripheral surface 5a side of the recess 5f by the connecting end portion 3a of the rod 3 so that the extending portion 7e is the inner peripheral surface 5a or the outer peripheral surface 3b or the electrode portion 6. The contact position of the terminal portion 7 with the inner peripheral surface 5a of the insulator 5 is changed in accordance with the relative movement of the connection end portion 3a and the insulator 5 by the relatively simple configuration of contacting the terminal portion, and the terminal portion The repulsive force of 7 can be increased.

  Moreover, according to this embodiment, at least a part of the portion (late deformation portion 21) sandwiched between the inner peripheral surface 5a of the terminal portion 7 and the outer peripheral surface 3b of the connection end 3a or the electrode portion 6 is formed. Since the stretched portion 7e is elasto-plastically deformed after coming into contact with the inner peripheral surface 5a, the contact pressure between the terminal portion 7 and the electrode portion 6 can be further increased, and a contact failure or the like can be further reliably ensured. Can be suppressed.

  In addition, according to the present embodiment, after at least a part of the extending portion 7e comes into contact with the inner peripheral surface 5a of the insulator 5, compared to before contact, the radial direction of the rod 3 of the terminal portion 7 (that is, The change rate of the load (repulsive force) in the direction with respect to the displacement in the opposing direction of the inner peripheral surface 5a and the outer peripheral surface 3b is increased. For this reason, at the beginning of assembling the rod 3 and the insulator 5, the repulsive force of the terminal portion 7 is made relatively small to improve the ease of assembly, and in the assembled state, the terminal portion 7 and the electrode The contact pressure with the part 6 can be further increased.

  Further, according to the present embodiment, the C ring 17 as an elastic member is interposed between the casing 13 and the insulator 5. For this reason, the vibration of the insulator 5 and the terminal part 7 can be suppressed, and the sag of the terminal part 7 can be prevented from being promoted by the vibration.

  The present invention can be embodied in another embodiment as follows. In other embodiments described below, the same operations and effects as in the above embodiments can be obtained.

  (1) For example, in the above embodiment, when the terminal portion 7 is pressed by the connecting end portion 3a of the rod 3, almost the entire area of the extending portion 7e is in contact with the surface (inner peripheral surface 5a). A part of the contact portion may contact the surface (inner peripheral surface 5a), so that the deformation section of the terminal portion 7 may be made smaller (shorter).

  (2) Moreover, as shown in FIG. 8, you may interpose a C ring in the edge part of the axial direction other side of the insulator 5. As shown in FIG. In this case, since it is not necessary to provide a step part in the insulator 5 and the casing 13, the manufacturing cost can be reduced. In FIG. 7, the same reference numerals are given to the same components as those in FIG. Of course, these similar components function in the same manner as in the above embodiment. In addition, the C ring may be of a type divided at one place in the circumferential direction, or may be an elastic member other than the C ring.

  (3) The rod is not limited to a long cylindrical shape, and may be, for example, a flat plate shape or a rectangular cross section.

  (4) Moreover, this invention can be implemented also as other than the said oxygen sensor for vehicles.

  Further, technical ideas other than the claims that can be grasped from the above embodiment will be described together with the effects thereof.

  (A) In the gas sensor, the inner radius R of the folded portion is set to 1.3 times or more of the total displacement amount of the initial deformed portion and the late deformed portion, and the length from the folded portion to the effective end of the distal end portion is set. It is preferable that the inner radius is 4.4 times or more.

  In this way, even when the gas sensor is downsized, the required contact pressure between the terminal part and the electrode part is ensured while efficiently absorbing variations in the displacement of the terminal part, thereby preventing contact defects more reliably. can do.

It is a longitudinal cross-sectional view of the gas sensor concerning one Embodiment of this invention. It is sectional drawing of the terminal part contained in the gas sensor concerning one Embodiment of this invention. It is a perspective view of the terminal part contained in the gas sensor concerning one embodiment of the present invention, and (a) and (b) are the figures seen from a different direction, respectively. It is sectional drawing which shows the assembly | attachment of the rod and an insulator contained in the gas sensor concerning one Embodiment of this invention, Comprising: (a) is an early stage, (b) is a figure which shows a late stage or an assembly completion state. . It is a figure which shows C ring incorporated in the gas sensor concerning one Embodiment of this invention, Comprising: (a) is a top view, (b) is sectional drawing. It is explanatory drawing which shows the displacement-load characteristic of the spring part of the terminal part contained in the gas sensor concerning one Embodiment of this invention. It is a longitudinal cross-sectional view of the gas sensor concerning the modification of one Embodiment of this invention. It is a longitudinal cross-sectional view of the gas sensor concerning another modification of one Embodiment of this invention.

Explanation of symbols

1 Oxygen sensor (gas sensor)
2 Gas detection part 3 Rod 3a Connection end part 4 Lead wire 5 Insulator 6 Electrode part 7 Terminal part 7b Fixing part 7c Base part 7d Folding part 7e Tip part 17 C ring (elastic member)
20 Initial deformation part 21 Late deformation part 22 Contact part

Claims (6)

A base portion having a gas detection portion provided on one side in the axial direction, and a connecting end portion on the other side in the axial direction in which an electrode portion electrically connected to the gas detection portion is formed on the surface; and a conductor of the lead wire A terminal portion to be connected to the connection portion and an insulator assembled to the connection end portion of the base portion, and the terminal portion is disposed between the surface of the insulator and the surface of the connection end portion. And the terminal part and the electrode part are pressed against each other by being sandwiched between the surface of the insulator and the electrode part, and the gas detection part and the conductor part of the lead wire In the method of assembling the base body and the insulator of the gas sensor that is electrically connected,
The terminal portion is changed by changing a contact point of the terminal portion with the surface of the insulator as the connecting end portion and the insulator are relatively moved in the axial direction toward a predetermined assembly position. A gas sensor assembly method characterized by increasing the repulsive force of the gas sensor.   After at least a part of the terminal portion comes into contact with the surface of the insulator, the terminal portion is deformed by being sandwiched between the surface of the insulator and the surface of the connecting end portion or the electrode portion. The method for assembling the gas sensor according to claim 1, wherein at least a part of the portion to be elastically plastically deformed.   After at least a part of the terminal portion comes into contact with the surface of the insulator, compared to before the contact, the terminal portion has a displacement relative to the opposing direction of the surface of the insulator and the surface of the connection end portion. 3. The gas sensor assembling method according to claim 1, wherein a rate of change in load in the direction is increased. A base portion having a gas detection portion provided on one side in the axial direction, and a connecting end portion on the other side in the axial direction in which an electrode portion electrically connected to the gas detection portion is formed on the surface; and a conductor of the lead wire A terminal portion to be connected to the connection portion and an insulator assembled to the connection end portion of the base portion, and the terminal portion is disposed between the surface of the insulator and the surface of the connection end portion. And the terminal part and the electrode part are pressed against each other by being sandwiched between the surface of the insulator and the electrode part, and the gas detection part and the conductor part of the lead wire In a gas sensor that is electrically connected,
The terminal portion assembled to the insulator includes a first contact portion that contacts a surface of the insulator in a state before the base portion and the insulator are assembled, and the base portion and the insulator are assembled. A stretched portion that extends obliquely toward one side in the axial direction while being separated from the first contact portion in a previous state, and is folded back toward the other side in the axial direction at a tip portion on the one axial side of the stretched portion A folded portion, and a second contact portion that contacts the electrode portion on the other side in the axial direction from the folded portion,
When the connection end and the insulator are relatively moved in the axial direction toward a predetermined assembly position, the terminal portion is pushed to the surface side of the insulator by the connection end, and the extending portion A gas sensor, wherein at least a part of the gas sensor is in contact with a surface of the insulator.   After at least a part of the extending portion comes into contact with the surface of the insulator, the terminal portion is deformed by being sandwiched between the surface of the insulator and the surface of the connecting end portion or the electrode portion. The gas sensor according to claim 4, wherein at least a part of the portion to be subjected to elastic-plastic deformation. A casing covering the outer periphery of the insulator;
A holder that is fixed to the casing and that holds the base portion exposed to the other side in the axial direction,
A concave portion that is recessed toward the other side in the axial direction is formed at an end portion on one side in the axial direction of the insulator,
In a state where the holder and the insulator are abutted in the axial direction, the connection end is inserted into the recess, and the terminal portion is formed between the inner peripheral surface of the recess and the outer peripheral surface of the connection end. The terminal part and the electrode part are pressed against each other by being disposed between and bent between the inner peripheral surface and the electrode part, and the gas detection part and the conductor part of the lead wire And are electrically connected,
The gas sensor according to claim 4 or 5, wherein an elastic member is interposed between the casing and the insulator.

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