JP5651550B2 - Temperature sensor and method of manufacturing temperature sensor - Google Patents

Description

  The present invention relates to a temperature sensor for measuring the temperature of exhaust gas or the like of an engine and a method for manufacturing the temperature sensor.

  Conventionally, sensors of various structures have been proposed as temperature sensors for measuring the temperature of engine exhaust gas and the like. For example, a temperature sensor element coated with glass or the like such as a thermistor is placed at the tip end in a tube (bottomed tube or cap) made of metal and closed, and welded to the lead wire of this temperature sensor element. The relay wire and an insulating member for insulating the periphery of the relay wire are arranged in the tube.

  In such a temperature sensor, cement (heat-resistant cement) is injected as a filler between the inner surface of the tube and the welded portion between the lead wire and the relay wire of the temperature sensor element disposed in the tube, By drying and solidifying this, the structure is such that the welded portion between the lead wire and the relay wire of the temperature sensor element is fixed in the tube (for example, Patent Document 1). In addition, as a configuration of the temperature sensor, a configuration is known in which a connection portion between the lead wire and the relay wire of the temperature sensor element is arranged in an insulating tube installed in the tube (for example, Patent Document 2).

JP 2010-32493 A JP-A-7-140012

  In such a temperature sensor, it is required to improve the responsiveness by reducing the diameter of the temperature sensor and the lead wire. On the other hand, it is required to further improve the durability without reducing the durability even if the diameter of the lead wire is reduced.

  The present invention has been made in response to the above-described conventional circumstances, and an object of the present invention is to provide a temperature sensor and a method for manufacturing the temperature sensor that can improve the durability as compared with the related art.

One aspect of the temperature sensor of the present invention is electrically connected to a metal tube having a distal end closed and extending in the axial direction, and a temperature-sensing portion that is disposed on the distal end side in the tube and whose electrical characteristics change depending on the temperature. Connected temperature sensor element having a circular lead wire, cross-sectional shape welded to the lead wire extending in the axial direction and having a circular shape larger than the lead wire, and the temperature in the tube A temperature sensor provided at the rear of the sensor element and having an insulator tube having at least a through hole extending in the axial direction for passing the relay wire, wherein a welded portion between the lead wire and the relay wire is The relay wire is located inside the insulator tube, and the relay wire has a flat surface at a welded portion with the lead wire, and the flat surface portion has the relay wire when the relay wire is viewed in a cross section including a central axis. The flat part of the line is formed Surface on the side is to be, as close to the central axis than the opposite surface, and, as the maximum thickness between said flat portion and the opposite surface is decreased from the diameter of the trunk line is formed, the lead wire to the flat portion, characterized in that it is welded.

  In the temperature sensor of the present invention, the welded portion between the lead wire and the relay wire is positioned inside the insulator tube, so that the welded portion between the lead wire and the relay wire is insulated and protected from the surroundings by the insulator tube. be able to. Further, the relay line has a flat portion at the welded portion with the lead wire, and the maximum thickness between the flat portion and the surface on the opposite side of the flat portion is smaller than the diameter of the relay wire. It is formed as follows. Thereby, compared with the case where a circular leader line and a circular relay line are welded as they are, these can be welded easily, and it can weld by resistance welding etc., without using laser welding etc. Furthermore, since the maximum thickness of the flat portion is formed to be smaller than the wire diameter of the relay wire, the sum of the wire diameter of the relay wire and the thickness of the flat portion in the welded portion is relayed without providing the flat portion. A thin insulator with a small diameter of the through hole when the welded portion is drawn into the insulator pipe after the lead wire and the relay wire are welded. Even a tube can be easily pulled in.

  In the temperature sensor of the present invention, as described above, the lead wire and the relay wire can be welded by resistance welding. In this case, the leader line and the relay line may be welded so as to include the rear end of the leader line. As a result, it is possible to prevent the rear end of the leader line from jumping up and away from the relay line.

In addition, according to one aspect of the method of manufacturing the temperature sensor of the present invention, the tip is closed and a metal tube extending in the axial direction and the temperature sensor is disposed on the tip side in the tube, and the electrical characteristics change depending on the temperature. A temperature sensor element having a circular lead wire having a circular cross-sectional shape electrically connected to the section, a relay wire extending in the axial direction and welded to the lead wire and having a circular shape and having a diameter larger than that of the lead wire; A temperature sensor manufacturing method comprising: an insulator tube disposed behind a temperature sensor element in a tube and having at least a through hole along an axial direction for passing the relay wire; A step of forming a flat portion by flattening processing, and when the flat portion is viewed in a cross section including a central axis, the surface of the relay line on which the flat portion is formed is Before the opposite side Forming a maximum thickness between the flat surface portion and the opposite surface so as to approach the central axis, and the flat surface of the relay wire; A step of resistance welding the lead wire to a portion, and a rear end portion of the lead wire and a front end portion of the relay wire are connected to the insulator so that a weld portion between the relay wire and the lead wire is located in the insulator pipe And a step of accommodating in a tube.

  According to the manufacturing method of the temperature sensor of the present invention having the above configuration, the above-described temperature sensor can be preferably manufactured.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the temperature sensor which can aim at the improvement of durability compared with the past, and a temperature sensor can be provided.

The figure which shows the longitudinal cross-sectional structure of the temperature sensor of one Embodiment of this invention. The figure which shows the principal part structure of the temperature sensor of FIG. The figure which shows the principal part structure of the temperature sensor of FIG. The figure which shows the principal part structure of a modification. The figure which shows the manufacturing method of the temperature sensor of one Embodiment of this invention. The microscope picture which shows the state of the cross section of a resistance welding part.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a schematic sectional configuration of a temperature sensor 101 according to an embodiment of the present invention. As shown in FIG. 1, the temperature sensor 101 has a metal (for example, SUS) tube 11 having a distal end 12 closed and extending in the axis G direction. The temperature sensor element 21 is disposed in a state where the tip is pressed. In the tube 11, an element support 31 that is an insulating member is disposed behind the temperature sensor element 21 (upward in FIG. 1), and an insulator tube (insulation tube) 41 is disposed behind the element support 31. Is arranged.

  The tube 11 is formed in a thin cylindrical shape with concentric and different diameters sequentially having a large diameter from the front end 12 toward the rear end 19. A predetermined range from the tip 12 toward the rear is the element housing portion 13 having the smallest diameter. An intermediate diameter portion 18 having a larger diameter than the element accommodating portion 13 is located behind the element accommodating portion 13, and a straight pipe portion larger in diameter than the intermediate diameter portion 18 is located behind the intermediate diameter portion 18. The distal end side accommodating portion 14 is formed so as to be supported by surrounding the distal end side portion of the insulator tube 41 with a minute gap fit state on the inner peripheral surface.

  Behind the distal end side accommodating portion 14 of the tube 11 is a straight pipe portion having a diameter larger than that of the distal end side accommodating portion 14, and a mounting bracket 61 for attaching the temperature sensor 101 itself to an attachment target site such as an exhaust manifold is concentric. It has a metal mounting part 15 to be fitted outside. Further, a seal member which is formed of a straight pipe portion having a diameter larger than that of the metal fitting attachment portion 15 behind the metal fitting attachment portion 15 of the tube 11 and in which the rear end side portion of the insulator tube 41 and the seal member 71 are disposed. A housing part 17 is provided.

  The insulator tube 41 is made of an insulator such as alumina, and is an elongated cylindrical tube having a constant outer diameter (cross section) having two through holes 42 penetrating along the axis G inside. A temperature sensor element 21 coated with glass is disposed at the tip 43 of the insulator tube 41 via an element support 31 made of an insulator such as ceramic.

  The two lead wires 23 extending rearward from the temperature sensor element 21 are respectively connected through the element support 31 and connected to the relay wire 25 extending rearward through the through holes 42 of the insulator tube 41. The rear end of the relay line 25 protrudes from the rear end 45 of the insulator tube 41. A welded portion 250, which is a connecting portion between the lead wire 23 and the relay wire 25, is housed inside the insulator tube 41 (in the through hole 42). As a result, the welded portion 250 between the lead wire 23 and the relay wire 25 can be insulated and protected from the surroundings by the insulator tube 41.

  As described above, the temperature sensor element 21 and the element support 31 are located from the distal end side in the element accommodating portion 13 of the tube 11, and the distal end portion of the insulator tube 41 is located in the distal end side accommodating portion 14. , Respectively, are disposed concentrically in the tube 11. The rear end 45 of the insulator tube 41 is located at an intermediate portion in the seal member housing portion 17 of the tube 11. The element support 31 that is an insulating member has a cylindrical shape having a smaller diameter than the distal end 43 of the insulator tube 41 and a larger diameter than the rear end 21 b of the temperature sensor element 21.

  As shown in FIG. 2, the temperature sensor element 21 includes a thermistor sintered body 20 as a temperature sensing part, a pair of electrode layers 22, a pair of lead wires 23, a pair of joining electrodes 22 a, and a glass sealing part. 24. The thermistor sintered body 20 is formed in a plate shape from a material mainly composed of a metal oxide having a perovskite horizontal structure or a spinel horizontal structure. The thermistor sintered body 20 as the temperature sensitive part has a characteristic that the resistance value changes according to the ambient temperature. The electrode layer 22 is an electrode made of a platinum (Pt) -based or gold (Au) -based noble metal. The electrode layer 22 is formed on each of the left and right surfaces of the thermistor sintered body 20 so as to sandwich the thermistor sintered body 20.

  The lead wire 23 is an electric wire for taking out a change in the resistance value of the thermistor sintered body 20 to the outside, and is made of a dumet wire having a circular cross-sectional shape. The outer diameter (wire diameter) of each lead wire 23 is about 0.20 mm to 0.25 mm. The lead wire 23 is bonded to each of the pair of electrode layers 22 by a bonding electrode 22a. The bonding electrode 22 a is an electrode for bonding the lead wire 23 to the electrode layer 22.

  The bonding electrode 22 a is formed of a platinum (Pt) -based or gold (Au) -based noble metal similar to the electrode layer 22. The glass sealing portion 24 covers each of the distal ends of the pair of lead wires 23, the thermistor sintered body 20, and the pair of electrode layers 22. The glass sealing portion 24 holds a member to be coated (such as the thermistor sintered body 20) inside and protects the member to be coated from the external environment.

The relay wire 25 to which the lead wire 23 of the temperature sensor element 21 is welded is formed in a linear shape having a circular cross section and a wire diameter of 0.5 mm from stainless steel or the like. As shown in FIG. 3, a flat portion 251 is formed by flattening at a portion where the welded portion 250 at the distal end portion of the relay wire 25 is formed. Planar portion 251, when viewed trunk 25 in a section including the center axis, the upper portion of the trunk line 25 is formed so as to be recessed by a predetermined distance d ₁ with respect to the original upper portion.

Therefore, the portion where the flat portion 251 is formed is such that the thickness (maximum thickness) T ₁ between the flat portion 251 and the surface 252 on the opposite side of the flat portion 251 is the wire diameter of the relay wire 25. is formed so as (cross-sectional shape that a diameter of the portion forms a circle) decreases from T ₀ (thinner). The lead wire 23 is welded to the flat portion 251 by resistance welding. Resistance welding is performed at two locations, the rear end side resistance welded part 250a including the rear end of the lead wire 23 and the front end side resistance welded part 250b.

  In this way, even when the thin lead wire 23 and the thin relay wire 25 are used by forming the flat portion 251 on the relay wire 25 and resistance welding the lead wire 23 to the flat portion 251, Resistance welding can be performed easily and reliably as compared with the case where the circular relay wire 25 and the circular lead wire 23 are welded as they are.

Further, the amount of deviation between the central axis of the relay line 25 and the central axis of the lead line 23 can be reduced as compared with the case where the circular relay line 25 and the circular lead line 23 are welded together. Thus, when the welded portion 250 is drawn into the through hole 42 of the insulator tube 41 after welding, it can be drawn more easily. In addition, while the wire diameter T ₀ of the relay wire 25 is 0.5 mm, the inner diameter of the through hole 42 of the insulator tube 41 is about twice or less (1.0 mm or less) of the wire diameter T ₀ of the relay wire 25. For example, it is about 0.75 mm to 0.80 mm.

Predetermined distance _{d 1} above, for example, about 0.12Mm～0.15Mm. When d ₁ is set to 0.12 mm to 0.15 mm in this way, the thickness (maximum thickness) between the flat surface portion 251 after actually flattening and the surface 252 on the opposite side to the flat surface portion 251 is obtained. ) _{T 1} is, it was about 0.33mm~0.38mm. Thus, since the thickness T ₁ is reduced from the original wire diameter T ₀ (0.5 mm) of the relay wire 25 to about 0.33 mm to 0.38 mm, the relay wire 25 and the lead wire 23 are connected to each other. After resistance welding, when the welded portion 250 is accommodated in the insulator tube 41, the welded portion 250 can be easily placed in the insulator tube 41 as compared with the case where the circular relay wire 25 and the circular lead wire 23 are welded as they are. Can be drawn into.

In welding the relay wire 25 and the lead wire 23, for example, as shown in FIG. 4, the lead wire 23 is formed by flattening and bending the relay wire 25 so as to protrude to the opposite surface 252 side. When the relay line 25 is welded, the center axis of the lead line 23 may coincide with the center axis of the relay line 25. Also in this case, the thickness (maximum thickness) T ₁ between the flat portion 251 and the surface 252 opposite to the flat portion 251 is smaller (thinner) than the wire diameter T ₀ of the relay wire 25. To form. If the central axis of the lead wire 23 and the central axis of the relay line 25 are made to coincide with each other in this way, the temperature sensor element 21 is connected to the tube 11 by arranging the central axis of the relay line 25 along the central axis of the tube 11. It becomes possible to arrange | position reliably on the center axis line.

  As shown in FIG. 1, in this embodiment, the insulator tube 41 is supported in such a manner that its distal end portion is disposed in the distal end side accommodating portion 14 of the tube 11 and is surrounded by a gap on the inner peripheral surface thereof. Has been. On the other hand, the rear end side of the insulator tube 41 supported in this way has a relatively large space between the inner peripheral surface of the tube 11. In addition, although the clearance gap between the internal peripheral surface of the front end side accommodating part 14 of the tube 11 and the outer peripheral surface of a corresponding insulator pipe 41 does not need to be filled with cement, it is not illustrated in this embodiment. Is filled.

  The rubber seal member 71 disposed in the seal member housing portion 17 of the tube 11 is formed in a substantially cylindrical shape. Then, the rear end portion 26 of the relay wire 25 drawn out from the rear end 45 of the insulator tube 41 and the front end portion (core wire) 53 of each lead wire 51 drawn out from the rear end 72 of the seal member 71 to the outside. Are connected via a terminal fitting 28. The leading end portion (core wire) 53 of the lead wire 51 is crimped to the crimping portion 29 of the terminal fitting 28, and the relay wire 25 is welded to the terminal fitting 28.

  A recess 74 is formed in the center of the seal member 71 on the front end 73 side so that it has a circular cross section and is recessed so that the rear end 45 of the insulator tube 41 can be inserted with a clearance fit. A rear end 45 of the tube 41 is inserted. The rear end portion of the relay wire 25, the terminal fitting 28, and the front end portion of the lead wire 51 are between the front end facing surface 75 of the seal member 71 that is the bottom portion (bottom surface) of the recess 74 and the rear end 72 of the seal member 71. It is in a state of being positioned in a through hole 77 that penetrates in parallel with the axis G interposed therebetween.

  The seal member 71 is fixed inside thereof by crimping the rear end portion 17c of the seal member accommodating portion 17 of the tube 11 to a reduced diameter, and the inner peripheral surface of the seal member accommodating portion 17 and the seal member A seal between the inner peripheral surface of the through-hole 77 and the outer peripheral surface of the insulating resin layer 54 that is a skin covering the core wire of each lead wire 51 passed therethrough is provided along with a seal between the outer peripheral surface of 71 Retained and fixed.

  As described above, in a state where the seal member accommodating portion 17 of the tube 11 is crimped to a reduced diameter, the seal member 71 is deformed to a reduced diameter at a portion near the rear end. The tip portion of 71 is deformed to extend toward the tip side. Thereby, the front-facing surface 75 which is the bottom of the concave portion 74 is in a state where the rear end 45 of the insulator tube 41 is pressed downward toward the front end side in FIG. By this pressing, the temperature sensor element 21 is pressed against the tip 12 of the tube 11 via the element support 31.

  A mounting bracket 61 is concentrically fitted and fixed to the middle bracket mounting portion 15 of the tube 11. The mounting bracket 61 has a cylindrical shape with a screw 60 on the outer peripheral surface for fixing the temperature sensor 101 to a mounting hole (screw hole) in the exhaust manifold portion. For example, it is fixed by brazing between the outer peripheral surface of the mounting portion 15.

  The mounting bracket 61 includes a polygonal portion 66 for tool engagement projecting outward on the rear end side of the screw cylinder portion 63 provided with the screw 60. An annular washer 69 for holding a seal is disposed on the distal end surface of the polygonal portion 66 for tool engagement and the outer peripheral surface of the screw cylinder portion 63 (the base end of the screw 60).

  FIG. 5 is a diagram illustrating a main part of a manufacturing process of the temperature sensor 101 having the above-described configuration. As shown in FIG. 5A, in the manufacturing process of the temperature sensor 101, the distal end portion of the relay wire 25 inserted into the through hole 42 of the insulator tube 41 is protruded from the distal end of the insulator tube 41, and the distal end of the relay wire 25. The flat part 251 is formed by flattening the part with a press device 150.

  Next, as shown in FIG. 5 (b), the lead wire 23 of the temperature sensor element 21 is arranged on the flat portion 251, and the lead wire 23 and the relay are relayed by a resistance welding device (electrode bar) 160. The wire 25 is welded at least two places at different positions in the axial direction. FIG. 6 shows a micrograph of an example of a cross-sectional state when the lead wire 23 is resistance welded on the flat portion 251 of the relay wire 25. In this photomicrograph, the relay line 25 is shown at the bottom and the leader line 23 is shown at the top. In the example shown in FIG. 6, the surface 252 (the lower surface in FIG. 6) on the opposite side to the flat portion 251 of the relay line 25 is also planar, but this opposite surface 252 is flattened. It may be in the shape before being processed, that is, circular.

  Next, as shown in FIG. 5 (c), the rear end portion of the lead wire 23 is positioned so that the welded portion 250 between the lead wire 23 and the relay wire 25 is positioned inside the through hole 42 of the insulator tube 41. The distal end portion of the relay wire 25 is drawn into the through hole 42 of the insulator tube 41.

  Through the above steps, the lead wire 23 and the relay wire 25 are welded, and the welded portion 250 is accommodated in the through hole 42 of the insulator tube 41. Thereafter, as shown in FIG. 2, the lead wire 51 is connected to the rear end portion of the relay wire 25 via the terminal fitting 28, and these are accommodated in the tube 11, and the seal member accommodating portion 17 of the tube 11 is provided. Clamp to a reduced diameter and fix.

  As described above, according to the above embodiment, it is possible to improve the durability as compared with the conventional case. In addition, this invention is not limited to this embodiment, Of course, various deformation | transformation are possible.

  DESCRIPTION OF SYMBOLS 11 ... Tube, 12 ... Tip, 21 ... Temperature sensor element, 23 ... Lead wire, 25 ... Relay wire, 250 ... Welding part, 251 ... Plane part, 31 ... Element support body, 41 ... ... insulator tube, 42 ... through hole, 101 ... temperature sensor.

Claims (4)

A metal tube whose tip is closed and extends in the axial direction;
A temperature sensor element having a circular lead wire having a circular cross-sectional shape that is disposed on the distal end side in the tube and electrically connected to a temperature-sensitive portion whose electrical characteristics change according to temperature,
A relay line extending in the axial direction and welded to the leader line is circular and has a larger diameter than the leader line, and
A temperature sensor comprising: an insulator pipe disposed behind the temperature sensor element in the tube and having at least a through hole along an axial direction for passing the relay line;
While the welded portion between the lead wire and the relay wire is located inside the insulator tube,
The relay line has a flat portion at a welded portion with the lead wire, and the flat portion forms the flat portion of the relay line when the relay line is viewed in a cross section including a central axis. Formed so that the surface on the side is closer to the central axis than the surface on the opposite side, and the maximum thickness between the plane portion and the surface on the opposite side is smaller than the wire diameter of the relay wire Has been
The temperature sensor , wherein the lead wire is welded to the flat portion . The temperature sensor according to claim 1,
The temperature sensor, wherein the lead wire and the relay wire are welded by resistance welding. The temperature sensor according to claim 2,
The temperature sensor, wherein the lead wire and the relay wire are welded so as to include a rear end of the lead wire. A metal tube whose tip is closed and extends in the axial direction;
A temperature sensor element having a circular lead wire having a circular cross-sectional shape that is disposed on the distal end side in the tube and electrically connected to a temperature-sensitive portion whose electrical characteristics change according to temperature,
A relay line extending in the axial direction and welded to the leader line is circular and has a larger diameter than the leader line, and
A temperature sensor manufacturing method comprising: an insulator tube disposed behind the temperature sensor element in the tube and having a through hole along at least an axial direction for passing the relay line;
A step of forming a flat portion on the relay line by flattening, and the flat portion of the relay line is formed when the flat portion is viewed in a cross section including a central axis. Formed so that the surface on the side is closer to the central axis than the surface on the opposite side, and the maximum thickness between the plane portion and the surface on the opposite side is smaller than the wire diameter of the relay wire And a process of
A step of resistance welding the lead wire to the flat portion of the relay wire;
And a step of accommodating the rear end portion of the lead wire and the front end portion of the relay wire in the insulator pipe so that a welded portion between the relay line and the lead wire is located in the insulator pipe. A method for manufacturing a temperature sensor.

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