JP2019002936A - Gas sensor - Google Patents

Abstract

To provide a method for more reliably fix a tube to be connected to an open end of a rear end of a sensor.SOLUTION: In a gas sensor, a tube 70 covers not only a lead wire 48 but also the tube 70 covers but also an outer peripheral surface of an end part including an opening end 46a within an external cylinder 46. A part covered by the tube 70 within the outer peripheral surface of the external cylinder 46 is held by a clamp 80. By this configuration, the clamp 80 integrally holds the tube 70 and the external cylinder 46. Besides, the tube 70 is protruded from the clamp 80 to an opposite side of the opening end 46a of the external cylinder 46 (a protrusion amount L is larger than 0). The opening end 46a of the external cylinder 46 forms a large diameter part where the outer diameter is larger than an inner diameter D1 of the clamp 80.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a gas sensor.

  Conventionally, a gas sensor that detects the concentration of a predetermined gas such as NOx in a gas to be measured such as an exhaust gas of an automobile is known. For example, the gas sensor described in Patent Literature 1 is electrically connected to a metal cylindrical body, a detection element (sensor element) that is disposed inside the cylindrical body and detects a gas concentration, and the sensor element. And a lead wire extending outward of the cylindrical body. Moreover, the gas sensor described in Patent Document 1 includes a tube that surrounds the lead wire, a cover member, and a clamp member.

  FIG. 11 is an explanatory view of an end portion of such a conventional gas sensor 300. The gas sensor 300 includes an outer cylinder 346 in which a sensor element (not shown) is arranged, a lead wire 348 that passes through an opening at the upper end of the outer cylinder 346 and extends outward (upward in FIG. 11), and a lead wire 348. A surrounding tube 370. Further, the gas sensor 300 includes a cover member 390 that covers the upper end side of the outer cylinder and the lower end side of the tube 370 from the periphery, and a clamp member 380 that tightens a portion of the cover member 390 that covers the upper end side of the outer cylinder 346 from the outside. I have. A contact portion 392 that contacts the outer peripheral surface of the tube 370 is formed on the upper end side of the cover member 390. In the gas sensor 300, the presence of the cover member 390 suppresses water from entering the sensor through the opening at the upper end of the outer cylinder 346.

JP2013-156183A

  However, in such a conventional gas sensor, the clamp member 380 is tightened only by the cover member 390 and the outer cylinder 346. For this reason, the tube 370 may be insufficiently fixed, for example, the tube 370 may be pulled out from the cover member 390 in FIG. 11. If the tube 370 comes out of the cover member 390, the lead wire 348 may be exposed or water may easily enter the sensor.

  The present invention has been made to solve such a problem, and a main object thereof is to more reliably fix the tube.

The gas sensor of the present invention is
A sensor element;
A cylindrical body in which the sensor element is disposed and an open end is formed;
A lead wire electrically connected to the sensor element and extending outward from the inside of the cylindrical body through the opening end;
A tube that covers the outer peripheral surface of the end portion of the cylindrical body including the open end and a portion of the lead wire that extends outward from the open end;
A gripping member that grips a portion of the outer peripheral surface of the cylindrical body that is covered with the tube so that the tube protrudes on the side opposite to the opening end;
It is equipped with.

  In this gas sensor of the present invention, not only the tube covers the lead wire, but also the outer surface of the end portion including the open end of the tubular body. And the holding member is holding the part covered with the tube among the outer peripheral surfaces of this cylindrical body. As a result, the gripping member grips the tube and the cylindrical body integrally. In addition, the tube protrudes from the gripping member on the side opposite to the opening end of the cylindrical body. As a result, it becomes difficult for the tube to come out from the opening end side of the cylindrical body, and the tube can be fixed more reliably. Here, the lead wire may be one or more. For example, the tube may cover a plurality of lead wires.

  In the gas sensor of the present invention, a maximum value of the outer shape of the tube on the opening end side with respect to a portion held by the holding member may be equal to or larger than the inner diameter of the holding member. If it carries out like this, it will become difficult to remove | omit the holding member from the opening end side of a cylindrical body, and it can fix a tube more reliably. In this case, the opening end of the cylindrical body may be a large diameter portion.

  In the gas sensor of the present invention, the gripping member may be a ring-shaped member surrounding the outer peripheral surface of the cylindrical body. In this way, for example, the tube can be more securely fixed by the gripping member than when the gripping member surrounds only a part of the outer peripheral surface of the cylindrical body such as a C-shape.

  The gas sensor of the present invention includes an elastic body that is disposed inside the cylindrical body, seals the inside of the cylindrical body from the outside on the opening end side, and the lead wire passes through the cylinder. The shaped body may have a reduced diameter portion that caulks the elastic body from the periphery. By doing so, the elastic body can block the gap between the inner peripheral surface of the cylindrical body and the lead wire, and water can be further prevented from entering the sensor element side from the opening end side of the cylindrical body.

FIG. 3 is an explanatory diagram showing an outline of the configuration of the gas sensor 10. FIG. 3 is an enlarged cross-sectional view of the sensor body 12 on the opening end 46a side (base end side). Sectional drawing of the clamp 80. FIG. Explanatory drawing which shows a mode that the outer cylinder 46 and the rubber stopper 60 are crimped. Explanatory drawing which shows the mode after crimping the outer cylinder 46 and the rubber stopper 60. FIG. Explanatory drawing which shows the mode of the coating | coated process which covers the tube 70 on the outer cylinder 46. FIG. Explanatory drawing which shows the mode of the coating | coated process which covers the tube 70 on the outer cylinder 46. FIG. Explanatory drawing which shows the mode of the coating | coated process which covers the tube 70 on the outer cylinder 46. FIG. Sectional drawing of the clamp 80 before attachment. Explanatory drawing of the state which moved the clamp 80 to the attachment position. Explanatory drawing of the edge part of the gas sensor 300 of a prior art example.

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing an outline of the configuration of a gas sensor 10 according to an embodiment of the present invention. As shown in FIG. 1, the gas sensor 10 includes a tube 70 that covers a sensor main body 12, an external connection portion 14, and a plurality of (eight in the present embodiment) lead wires 48 that connect the sensor main body 12 and the external connection portion 14. And. The gas sensor 10 is attached to an exhaust gas pipe of a vehicle, for example, and is used for measuring a gas concentration such as NOx or O ₂ contained in exhaust gas as a gas to be measured.

  The sensor body 12 includes a sensor element 20 that measures the gas concentration of a predetermined gas component from the gas to be measured, a protective cover 30 that protects one end of the sensor element 20, a connector 50 that is electrically connected to the sensor element 20, and rubber. And a sensor assembly 40 including a stopper 60.

The sensor element 20 is an element having an elongated plate-like body shape, and is formed by stacking, for example, six ceramic substrates made of an oxygen ion conductive solid electrolyte layer such as zirconia (ZrO ₂ ). In addition, the edge part (lower end of FIG. 1) by the side of the protective cover 30 of sensor element 20 is described as a front-end | tip, and the edge part (upper end of FIG. 1) of the connector 50 side is described by a base end. Electrodes (not shown) for applying a voltage to the sensor element 20 and extracting an electromotive force or current generated according to the concentration of the gas component detected by the sensor element 20 are provided on the base end surface and the back surface of the sensor element 20. Is formed. A plurality of electrodes are formed on the front surface and the back surface of the sensor element 20, and are electrically connected to an electrode in the tip of the sensor element 20 via an electric path inside the sensor element 20 (not shown).

  The protective cover 30 is disposed so as to surround the periphery of the tip of the sensor element 20. The protective cover 30 includes an inner protective cover 31 that covers the tip of the sensor element 20 and an outer protective cover 32 that covers the inner protective cover 31. The inner protective cover 31 is formed in a cylindrical shape and includes inner protective cover holes 31a and 31b for allowing the gas to be measured to flow. The outer protective cover 32 is formed in a bottomed cylindrical shape, and has outer protective cover holes 32a and 32b for allowing the gas to be measured to flow on the side surface. The inner protective cover 31 and the outer protective cover 32 are made of metal such as stainless steel, for example.

  The sensor assembly 40 includes a metal metal shell 41, cylindrical inner and outer cylinders 42 and 46 welded to the metal shell 41, a connector 50 connected to the base end of the sensor element 20, and an outer cylinder. And a rubber plug 60 attached to 46. The metal shell 41 can be attached to, for example, an exhaust pipe of a vehicle by a male screw portion 41a. Inside the metal shell 41 and the inner cylinder 42, a plurality of ceramic supporters 43a to 43c and ceramic powders 44a and 44b such as talc filled between the ceramic supporters 43a and 43b and between the ceramic supporters 43b and 43c are enclosed. These are sandwiched and sealed between the metal ring 45, the inner wall of the metal shell 41 and the inner wall of the inner cylinder 42. The outer cylinder 46 covers the periphery of the inner cylinder 42, the sensor element 20, and the connector 50. The outer cylinder 46 has a rubber plug 60 attached to the inside of the end including the opening end 46a (the upper end of the outer cylinder 46 in FIG. 1).

  The connector 50 includes a housing 51 made of ceramic such as an alumina sintered body, and a contact fitting 52 that is held by the housing 51 and contacts an electrode of the sensor element 20. The contact fitting 52 is pulled out of the connector 50 and is electrically connected to the lead wire 48 through a connection portion 52a which is a crimp terminal. The lead wire 48 is drawn out of the sensor assembly 40. The connector 50 includes a number (for example, four or eight) of contact fittings 52 corresponding to a plurality of electrodes formed on the front surface and the back surface of the sensor element 20. There are a plurality of locations (for example, 4 locations, 8 locations, etc.), and a plurality of lead wires 48 (for example, 4 locations, 8 locations, etc.) are drawn out.

  The rubber plug 60 is an elastic body made of fluoro rubber for sealing a gap between the outer cylinder 46 and the lead wire 48 (connecting portion 52a) at the opening end 46a of the outer cylinder 46, and is a through-hole penetrating the inside. The connection part 52a is arrange | positioned in 60a, and the lead wire 48 is penetrated. A plurality of through holes 60a are also formed so as to accommodate the plurality of connection portions 52a and the lead wires 48, respectively.

  FIG. 2 is an enlarged cross-sectional view of the sensor body 12 on the opening end 46a side (base end side). As shown in the figure, the outer cylinder 46 is formed with crimped portions 47a and 47b that are crimped to a reduced diameter. The rubber plug 60 is crimped together with the outer tube 46 in a reduced diameter by the crimped portions 47 a and 47 b, and is fixed in the outer tube 46. The rubber plug 60 has a protruding portion 60b that protrudes outward (right side in FIG. 2) from the opening end 46a. With the rubber plug, the inside of the outer cylinder 46 is sealed from the outside on the opening end 46a side, and for example, the lead wire is moved outward from the outer cylinder 46 while suppressing the entry of moisture into the outer cylinder 46. It can be pulled out.

  The tube 70 is a cylindrical member having insulation and flexibility, and covers all the lead wires 48 from the sensor main body 12 to the external connection portion 14. The tube 70 covers the outer peripheral surface of the end portion on the proximal end side of the outer cylinder 46 including the open end 46a and the crimped portions 47a and 47b. In the present embodiment, the tube 70 is a varnish tube in which a silicon material is applied to the surface of a braided tube made of glass fiber. The material of the tube 70 is not limited to this, and may be made of resin fibers such as polyester instead of glass fibers. In addition, the lead wire 48 is in a state of being double-coated with the coating of the lead wire 48 itself and the tube 70.

  A portion of the outer peripheral surface of the outer cylinder 46 covered with the tube 70 is held by a clamp 80. FIG. 3 is a cross-sectional view of the clamp 80. 3 shows the AA cross section of FIG. The clamp 80 is a metal ear clamp and includes a ring portion 81 and an ear portion 82. The ring part 81 and the ear part 82 are formed by bending one plate-like member, and the ring part 81 surrounds the outer peripheral surfaces of the tube 70 and the outer cylinder 46. Further, the inner peripheral surface of the ring portion 81 is in contact with the tube 70. The end of the arc of the ring portion 81 is accommodated in a groove 81a formed on its inner peripheral surface. As a result, the clamp 80 is configured as a so-called stepless clamp having no step on the inner peripheral surface of the ring portion 81. The ear portion 82 includes a substantially flat bridge portion 84 and leg portions 83a and 83b crimped from above and below in FIG. By clamping the legs 83a and 83b, the clamp 80 holds the tube 70 and the outer cylinder 46 by the ring portion 81. In addition, the bending part 85 which continues from the leg part 83b to the lower right direction of FIG. 3 inserts the protrusion (not shown) formed in the outer peripheral surface of the ring part 81 in its own hole (not shown). The ring portion 81 is fixed to the outer peripheral surface.

  As shown in FIG. 2, the clamp 80 is positioned so as to straddle the outer peripheral surfaces of the caulking portions 47a and 47b. Further, the tube 70 exists to the tip side (left direction in FIG. 2) from the clamp 80. That is, the tube 70 protrudes from the clamp 80 on the side opposite to the opening end 46a. The protrusion amount L of the clamp 80 is not particularly limited as long as the value exceeds 0 mm, but is, for example, 0.5 to 1.0 mm. Further, the outer diameter D2 of the opening end 46a is larger than the inner diameter D1 of the clamp 80. That is, the opening end 46a is a large diameter portion having an outer diameter larger than the inner diameter D1. Further, the maximum diameter D3 of the rubber plug 60 and the maximum diameter D4 of the tube 70 are both larger than the inner diameter D1, and D1 <D2 <D3 <D4. The maximum diameter D3 is the outer diameter of the rubber plug 60 having the largest diameter on the opening end 46a side of the clamp 80 (in this embodiment, the maximum diameter of the protruding portion 60b). Similarly, the maximum diameter D4 has the largest diameter in a portion of the tube 70 from the clamp 80 to the proximal end of the sensor main body 12 (in this embodiment, the proximal end of the rubber plug 60 (the right end of the rubber plug 60 in FIG. 2)). The outer diameter of the large part. That is, in this embodiment, the maximum diameter D4 = the maximum diameter D3 + the thickness of the tube 70 × 2.

  The external connection unit 14 includes a plurality of terminal electrodes connected to the lead wire 48 via a crimp terminal (not shown). As a result, the terminal electrode of the external connection portion 14 is electrically connected to the electrode of the sensor element 20 via the lead wire 48. When the external connection unit 14 is connected to, for example, a vehicle control unit, the control unit applies a voltage to the sensor element 20 via the terminal electrode of the external connection unit 14 or extracts a signal (electromotive force or current). can do.

  Next, a method for manufacturing the gas sensor 10 will be described. First, the metal shell 41 and the inner cylinder 42 are assembled by welding so as to be coaxial, and the ceramic supporter 43a, the ceramic powder 44a, the ceramic supporter 43b, the ceramic powder 44b, The metal rings 45 are inserted after filling the ceramic supporters 43c in this order. Next, the sensor element 20 is passed through the metal ring 45 from the ceramic supporter 43c, the ceramic powder 44b, the ceramic supporter 43b, the ceramic powder 44a, and the ceramic supporter 43a in this order. It is assumed that the ceramic supporters 43a to 43c, the ceramic powders 44a and 44b, and the metal ring 45 are previously formed with holes through which the sensor element 20 can pass. The metal ring 45 and the metal shell 41 are pressed in a direction in which they approach each other to compress the ceramic powders 44a and 44b, and in this state, the inner cylinder 42 on the outer side (upper side in FIG. 1) than the metal ring 45. The diameter of the inner cylinder 42 is further reduced by caulking, and a primary assembly including the metal shell 41 and the sensor element 20 is obtained.

  When the primary assembly is thus obtained, the inner protective cover 31 and the outer protective cover 32 are attached to the metal shell 41 by welding to form the protective cover 30, and the outer cylinder 46 is attached to the metal shell 41 by welding. Subsequently, a rubber plug 60 having a through hole 60a is prepared. Then, a lead wire 48 that passes through the through hole 60 a of the rubber plug 60 and a connector 50 in which the connecting portion 52 a of the contact fitting 52 is connected to the lead wire 48 are prepared, and the connector 50 is connected to the base end side of the sensor element 20. And the rubber plug 60 is inserted into the outer cylinder 46 from the open end 46a. Next, the outer cylinder 46 and the rubber plug 60 are reduced in diameter by caulking, and the rubber plug 60 is fixed to the outer cylinder 46. FIG. 4 is an explanatory view showing a state in which the outer tube 46 and the rubber plug 60 are caulked in the manufacturing process of the gas sensor 10.

  As shown in FIG. 4, the caulking process uses a caulking jig 91 set in a caulking machine (not shown) and a pressing jig 92 that presses the caulking jig 91 from the back side. Done. The caulking jig 91 has two projections 91a and 91b for caulking the caulking portions 47a and 47b. Further, the caulking jig 91 has a shape such that a cylindrical member is divided into 8 parts by 45 degrees. For this reason, when eight caulking jigs 102 are prepared so that the protrusions 91a and 91b face the inner peripheral side, and the primary assembly is set at the center of the caulking jig 91, the cylindrical outer cylinder 46 is provided. The caulking jig 91 is arranged so as to surround the periphery. In this state, by moving the pressing jig 92 in the left direction in FIG. 4, the crimping jig 91 receives the pressing from the pressing jig 92 and the caulking jig 91 moves from the outer peripheral side to the center side (the outer cylinder 46 side). Move almost parallel to As a result, the protrusions 91a and 91b are brought into contact with the outer cylinder 46 and caulking is performed. FIG. 5 is an explanatory view showing a state after the outer tube 46 and the rubber plug 60 are crimped. By this caulking process, caulking portions 47 a and 47 b are formed, and the inside of the outer cylinder 46 is sealed from the outside of the opening end 46 a by the rubber plug 60. In addition, as shown in FIG. 4, in the state before performing this crimping process, the edge part of the rubber stopper 60 exists in the same position as the opening end 46a. When the caulking process is performed, the rubber plug 60 is extended in the axial direction (left and right direction in FIG. 4) by the pressing force by the caulking process, and a part of the rubber plug 60 protrudes from the opening end 46a to become the protruding portion 60b (see FIG. 5).

  Subsequently, the tube 70 is covered from the end of the lead wire 48 opposite to the outer cylinder 46 (side connected to the external connection portion 14), and the outer cylinder 46 is further covered with the tube 70. 6-8 is explanatory drawing which shows the mode of the coating | coated process which covers the tube 70 on the outer cylinder 46. FIG. As shown in FIG. 6, the coating process is performed using a coating jig 93 set in a coating machine (not shown). The covering jig 93 has a shape in which a cylindrical member whose outer peripheral surface is an inclined surface (the outer diameter decreases toward the right side in FIG. 6) is divided into two vertically by 180 °. In the covering step, first, the tube 70 is put on the outer peripheral surface of the covering jig 93 as shown in FIG. Next, the outer cylinder 46 is inserted into the tube 70 while increasing the diameter of the tube 70 by separating the upper and lower covering jigs 93 from each other (FIG. 7). Then, after inserting the outer peripheral surface including the caulking portions 47 a and 47 b in the outer cylinder 46 into the tube 70, the covering jig 93 is extracted from the inside of the tube 70. Thereby, the tube 70 will be in the state which covered the outer peripheral surface of the edge part of the base end side of the outer cylinder 46 containing the opening end 46a and the crimping parts 47a and 47b (FIG. 8).

  Next, the clamp 80 is attached. FIG. 9 is a cross-sectional view of the clamp 80 before attachment. In the clamp 80 before attachment, the leg portions 83a and 83b are not crimped, and the inner diameter of the ring portion 81 is larger than that in FIG. When attaching to the clamp 80, first, the clamp 80 is inserted from the end of the lead wire 48 opposite to the outer tube 46, and moved to the attachment position of the clamp 80. FIG. 10 is an explanatory diagram of the state in which the clamp 80 is moved to the attachment position. The attachment position is a position on the left side of FIG. 10 with respect to the opening end 46a, and is a position where the protruding amount L of the clamp 80 described in FIG. 2 exceeds 0 mm. In the present embodiment, as shown in FIG. 2, the clamp 80 is positioned so as to straddle the crimped portions 47 a and 47 b. In this state, the clamp 80 is crimped by pressing in a direction approaching the leg portions 83a and 83b with a pliers-like clamping tool (not shown). As a result, the clamp 80 is in the state shown in FIG. 3, the inner diameter of the ring portion 81 is reduced, the outer tube 46 and the tube 70 are gripped, and the state shown in FIG. 2 is obtained. Then, the end of the lead wire 48 opposite to the outer tube 46 is connected to the external connection portion 14. Thus, the gas sensor 10 shown in FIG. 1 is obtained.

  Here, the correspondence between the components of the present embodiment and the components of the present invention will be clarified. The sensor element 20 of the present embodiment corresponds to the sensor element of the present invention, the opening end 46a corresponds to the opening end, the outer cylinder 46 corresponds to the cylindrical body, the lead wire 48 corresponds to the lead wire, and the tube 70. Corresponds to a tube, and the clamp 80 corresponds to a gripping member. The open end 46a corresponds to the large diameter portion.

  In the present embodiment described above, the tube 70 not only covers the lead wire 48, but the tube 70 also covers the outer peripheral surface of the end including the open end 46 a in the outer cylinder 46. The clamp 80 holds the portion of the outer peripheral surface of the outer cylinder 46 covered with the tube 70. As a result, the clamp 80 integrally holds the tube 70 and the outer cylinder 46. Moreover, the tube 70 protrudes from the clamp 80 on the side opposite to the opening end 46a of the outer cylinder 46 (the amount of protrusion L> 0). As a result, the tube 70 is unlikely to come out from the open end 46a side of the outer cylinder 46, and the tube 70 can be fixed more reliably. Therefore, for example, exposure of the lead wire 48 and intrusion of water into the sensor (inside the outer cylinder 46) can be further suppressed. For example, in the conventional gas sensor 300 shown in FIG. 11, the clamp member 380 and the cover member 390 are used. However, in this embodiment, the tube 70 and the outer cylinder 46 are held only by the clamp 80. The cover member 390 is not necessary. Therefore, the tube 70 can be more reliably fixed as compared with the gas sensor 300 of FIG. 11, and the number of parts and the number of manufacturing steps can be reduced.

  Further, since the tube 70 has a maximum diameter D4 on the opening end 46a side of the portion gripped by the clamp 80, which is larger than the inner diameter D1 of the clamp 80, the clamp 80 is difficult to come off from the opening end 46a side of the outer cylinder 46, The tube 70 can be more reliably fixed.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

  For example, in the above-described embodiment, the inner diameter D1 <the outer diameter D2 is set in FIG. 2, but the present invention is not limited thereto, and the inner diameter D1 = the outer diameter D2 or the inner diameter D1> the outer diameter D2 may be used. The same applies to the relationship between the inner diameter D1 and the outer diameters D3 and D4. However, since it is difficult for the clamp 80 to come out from the opening end 46a side of the outer cylinder 46, it is preferable that the inner diameter D1 ≦ the maximum diameter D4.

  In the above-described embodiment, the outer diameter D2 of the opening end 46a is larger than the inner diameter D1 of the clamp 80, that is, the opening end 46a is a large-diameter portion. For example, you may provide a large diameter part separately between the clamp 80 and the opening end 46a. For example, the clamp 80 grips only the caulking portion 47a of the outer cylinder 46, and the outer diameter of the portion of the outer cylinder 46 between the caulking portion 47a and the caulking portion 47b is larger than the inner diameter D1. May be.

  In the above-described embodiment, the clamp 80 is a stepless clamp including the ear portion 82, but is not limited thereto, and any clamp may be used. Further, any member may be used as long as it is a gripping member that grips the tube 70 and the outer cylinder 46. For example, instead of the clamp 80, the tube 70 and the outer cylinder 46 may be held by a resin binding band or the like. The clamp 80 and the binding band are ring-shaped members that surround the outer peripheral surface of the outer cylinder 46. However, the present invention is not limited thereto, and the gripping member is a member other than the ring shape, such as a C-shape or a V-shape. May be.

  In the above-described embodiment, the rubber plug 60 protrudes from the opening end 46a, but is not limited thereto. The end of the vertical aunt and the rubber plug 60 may be at the same position as the opening end 46a, or the end of the rubber plug 60 is positioned closer to the sensor element 20 (left side in FIG. 2) than the opening end 46a. Also good. When the rubber plug 60 is positioned closer to the sensor element 20 than the opening end 46a, the maximum diameter D4 of the tube 70 is the largest diameter portion of the tube 70 from the clamp 80 to the opening end 46a. The outer diameter. In this case, the maximum diameter D4 = [the outer diameter of the outer cylinder 46 having the largest diameter from the clamp 80 to the opening end 46a] + the thickness 70 of the tube 70.

  In the embodiment described above, the clamp 80 grips the tube 70 and the outer cylinder 46 at a position straddling the caulking portions 47a and 47b, but is not limited thereto. For example, the clamp 80 may grip the tube 70 or the outer cylinder 46 only by one of the caulking portions 47a and 47b. Moreover, you may hold | grip the tube 70 and the outer cylinder 46 in the position different from the crimping parts 47a and 47b.

  In the above-described embodiment, the outer cylinder 46 has the caulking portions 47a and 47b, but is not limited thereto. For example, the outer cylinder 46 may have only one of the caulking portions 47a and 47b.

[Example 1]
As Example 1, the gas sensor 10 shown in FIGS. 1-2 was created by the manufacturing method mentioned above. The lead wire 48 is not connected to the external connection portion 14. The material of the outer cylinder 46 is SUS304, and the tube 70 is a varnish tube in which a silicon material is applied to the outer peripheral surface of the glass fiber braided sleeve and cured at 200 ° C. As the clamp 80, a stepless ear clamp 14.8-706RD manufactured by Oetika was used. The axial length of the crimped portion 47a was 2.5 mm, the axial length of the crimped portion 47b was 2.5 mm, and the axial distance between the crimped portion 47a and the crimped portion 47b was 3.5 mm. Moreover, the outer peripheral surface of the outer cylinder 46 from the opening end 46a including the crimped portions 47a and 47b to 10 mm in the axial direction was covered with the tube 70. The clamp 80 was attached to a position where the protruding amount L was 0.5 mm and gripped the tube 70 and the outer cylinder 46. The inner diameter D1 of the clamp 80 is 12.3 mm, the band width (axial length) of the clamp 80 is 7 mm, the outer diameter D2 of the open end 46a is 11.8 mm, the maximum diameter D3 of the rubber plug 60 is 12.0 mm, and the tube 70 The maximum diameter D4 was 12.8 mm, and the inner diameter of the tube 70 (the inner diameter of the portion covering the lead wire 48 outside from the opening end 46a) was 8.5 mm.

[Comparative Example 1]
Except that the clamp 80 is not attached, a gas sensor similar to that of Example 1 was created and used as Comparative Example 1.

[Tensile strength measurement]
For the gas sensors of Example 1 and Comparative Example 1, tension was applied to the tube 70 so as to pull the tube 70 in the axial direction (right direction in FIG. 2). Then, the tension applied to the tube 70 when the tube 70 was completely removed from the outer cylinder 46 was measured as the tensile strength. The tensile strength of Example 1 was 20N. On the other hand, when tensile strength was measured about five comparative examples 1, tensile strength was 8.6N, 7.3N, 7.8N, 6.4N, 6.6N. From this, the tube 70 is put on the outer peripheral surface of the end including the open end 46a of the outer cylinder 46, and the tube 70 and the outer cylinder 46 are gripped by the clamp 80 so that the protruding amount L> 0 mm. It was found that the tube 70 can be fixed more reliably.

  DESCRIPTION OF SYMBOLS 10 Gas sensor, 12 Sensor main body, 14 External connection part, 20 Sensor element, 30 Protection cover, 31 Inner protection cover, 31a, 31b Inner protection cover hole, 32 Outer protection cover, 32a, 32b Outer protection cover hole, 40 Sensor assembly , 41 metal shell, 41a male thread part, 42 inner cylinder, 43a-43c ceramic supporter, 44a, 44b ceramic powder, 45 metal ring, 46 outer cylinder, 46a open end, 47a, 47b crimping part, 48 lead wire, 50 connector, 51 housing, 52 contact fitting, 52a connection, 60 rubber plug, 60a through hole, 60b protrusion, 70 tube, 80 clamp, 81 ring, 81a groove, 82 ear, 83a, 83b leg, 84 Bridge part, 85 bending part, 91 caulking jig 91a, 91b projections 92 pressing jig, 93 covering jig, 346 outer cylinder 348 leads, 370 tube, 380 clamping members 390 cover member 392 abutting part.

Claims (3)

A sensor element;
A cylindrical body in which the sensor element is disposed and an open end is formed;
A lead wire electrically connected to the sensor element and extending outward from the inside of the cylindrical body through the opening end;
A tube that covers the outer peripheral surface of the end portion of the cylindrical body including the open end and a portion of the lead wire that extends outward from the open end;
A gripping member that grips a portion of the outer peripheral surface of the cylindrical body that is covered with the tube so that the tube protrudes on the side opposite to the opening end;
Gas sensor equipped with. In the tube, the maximum value of the outer diameter on the opening end side with respect to the portion gripped by the gripping member is equal to or larger than the inner diameter of the gripping member.
The gas sensor according to claim 1. The gripping member is a ring-shaped member that surrounds the outer peripheral surface of the cylindrical body.
The gas sensor according to claim 1 or 2.