JP2008026012A - Temperature sensor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further improve reliability and responsiveness of a temperature sensor equipped with a temperature detection element in a metallic cover. <P>SOLUTION: The temperature sensor 1 comprises: a temperature sensitive part 10 composed of the metallic cover 104, the tip of which is closed and another end is provided with a bottom and a temperature detection element 101 connected with a pair of electrode wires 102; a protector tube part 12 composed of a cylindrical metallic protector tube 123, a pair of signal wires 121 and an insulation member 122; and a housing part 13 having a screw part 132. While a filling material 103 for filling the clearance between the metallic cover 104 and the temperature detection element 101 holding detector element 101 in the metallic cover 104, a bubble discharging through hole 111 is provided on the bottom of the metallic cover 104 for discharging bubbles 2 contained in the filling material 103, and then a seal means 112 for sealing bubble discharging through hole 111. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a temperature sensor in which a temperature detection element connected to a pair of electrode wires is housed in a bottomed cylindrical metal cover, and in particular, a flow path through which a fluid to be measured such as diesel engine automobile exhaust gas flows. This is suitable for a temperature sensor that detects the temperature of a fluid to be measured in an environment that is provided inside and exposed to vibrations of a vehicle.

2. Description of the Related Art Conventionally, as a temperature sensor provided in an exhaust gas flow path for controlling temperature of an exhaust gas purification apparatus for automobiles, a metal core wire connected to an electrode wire of a thermistor element as described in Patent Document 1, for example, is sheathed. A sheath member that is insulated and held in a pipe has a bottomed cylindrical shape with a small diameter portion having an inner diameter smaller than the outer diameter of the sheath member and a large diameter larger than the outer diameter of the small diameter portion on the rear end side of the small diameter portion. A temperature sensor in which the thermistor element is placed inside the tip of the metal tube while being inserted into a metal tube having a diameter, and cement is filled between the tip of the thermistor element and the tip of the inner wall of the metal tube. It has been known.
Patent Document 2 discloses a thermistor element suitable for measurement at a high temperature of 1000 ° C. or more using a transition metal oxide mainly composed of Y (Cr, Mn) O ₃ or the like.

JP 2004-317499 A JP 2001-143907 A

However, in such a temperature sensor, in the temperature sensor 1b shown in FIG. 7A, the inner diameter of the small diameter portion of the temperature sensing portion 10b is extremely small. In such a case, the filler 103 shown in FIG. 7B is injected into the metal cover 104b in a slurry state, and thereafter, a pair of signal lines 121 connected to the pair of electrode wires 102 of the temperature detection element 101 are provided. A metal protective tube 123 insulated and supported through an insulating member 122 is inserted and fixed in the metal cover 104b.
At this time, air is entrained in the filler due to the influence of the surface tension, viscosity, etc. of the filler 103 in a slurry state, and bubbles 2 as shown in FIG. 7B are formed inside the tip of the metal cover 104b. May occur.
If such bubbles exist, heat conduction from the metal cover 104b to the temperature detecting element 101 is hindered, resulting in a decrease in temperature responsiveness.

  Further, when the filling of the filler 103 becomes incomplete due to the presence of the bubbles 2, the holding power of the filler 103 holding the temperature detecting element 101 in the metal cover 104b is reduced. To do. Therefore, when such a temperature sensor 1b is exposed to vehicle vibration and is subjected to vibration from the outside, local stress concentration occurs on the electrode wire 102 of the temperature detection element 101, and the electrode wire 102 may be disconnected. is there.

  Further, since such bubbles are indefinite, there is a variation in the response reduction due to the bubbles, and it is difficult to quantitatively correct such variations by electrical processing or the like. In addition, since it is a defect generated in the metal cover, it is difficult to find the presence or absence of the bubble unless using means such as X-ray imaging. Therefore, in order to improve the reliability of such a temperature sensor, it is desired to reliably eliminate the bubbles in the manufacturing process.

  Therefore, in view of the actual situation, an object of the present invention is to provide a temperature sensor that realizes further improvement of responsiveness and improvement of earthquake resistance and is excellent in reliability.

  According to the first aspect of the present invention, there is provided a bottomed cylindrical metal cover whose one end is closed and the other end is opened, and a temperature detecting element which is housed inside the closed end of the metal cover and connected to a pair of electrode wires. A temperature sensing part, a cylindrical metal protective tube inserted into the open end of the metal cover, and an electrode connected to the electrode wire provided inside the metal protective tube to extract a signal to the outside A housing having a protective tube portion composed of a pair of signal lines and an insulating member for insulating them, and a screw portion for holding the protective tube portion and fixing the temperature sensing portion at a predetermined position in the fluid to be measured A temperature sensor provided with a portion, wherein the temperature detection element is held in the metal cover by a filler that fills a gap between the metal cover and the temperature detection element, and the metal cover For discharging air bubbles at the bottom of the closed end Has a through hole, bubbles taken into the closed end of the metallic cover is characterized in that it is discharged by the bubble discharge through hole.

  Defects in the filler can be reduced by discharging bubbles entrained in the filler from the through hole for discharging bubbles when the filler is injected into the metal cover. Therefore, since the temperature detection element is held in a stable state in the metal cover, it is possible to prevent disconnection of the electrode wire due to external vibration or the like.

  Further, the filler is uniformly filled in the gap between the temperature detection element and the metal cover, so that the heat conduction to the temperature detection element is made uniform. Therefore, the responsiveness as a temperature sensor is stabilized.

  In the invention of claim 2, a sealing means for sealing the bubble discharge through hole is provided.

  Since the bubble discharging through hole is sealed by the sealing means, the temperature detecting element is not affected by oxidation, reduction, etc. by the non-measuring fluid. Therefore, reliability as a temperature sensor is ensured.

  According to a third aspect of the present invention, the bubble discharge through hole is a through hole having a diameter of 50 μm to 300 μm.

  When the bubble discharge through hole is smaller than 50 μm in diameter, it is difficult to discharge the bubble, and when the bubble discharge through hole is larger than 300 μm in diameter, sealing after filling becomes difficult.

  In the invention of claim 4, a plurality of the bubble discharge through holes are provided.

  Since the bubbles are indefinite, if a plurality of the bubble discharge through holes are provided, the discharge probability of the bubbles is increased, and the bubbles can be more reliably excluded. Therefore, the reliability as a temperature sensor is improved.

  In the invention of claim 5, the sealing means is a weld bead (weld mark) formed by laser welding.

  The weld bead (weld mark) is completely integrated with the bottom portion of the metal cover, and the bubble discharge through hole can be sealed. Therefore, the temperature detecting element is not affected by causing a chemical change from the fluid to be measured.

  In the invention of claim 6, the inner diameter of the metal cover is 3 mm or less.

  The present invention is particularly suitable for a temperature sensor in which a temperature detection element is housed in an extremely thin metal cover having an inner diameter of 3 mm or less, and the distance between the temperature detection element and the metal cover is extremely short, so that the response is excellent. .

  In the invention of claim 7, the filler is a cement containing an inorganic binder and mainly composed of alumina.

The above-mentioned alumina cement is solidified by heat drying at a low temperature, and becomes a filler having a chemically stable and good electrical insulation and good thermal conductivity that does not change even when used in an environment of 1000 ° C. or higher. . Therefore, the responsiveness as a temperature sensor is further improved.
The alumina cement is excellent in mechanical strength, and the temperature detecting element, the pair of electrode wires and the pair of signal wires are integrally and firmly supported and fixed, so that the earthquake resistance against external vibration is improved. .

  According to an eighth aspect of the present invention, the metal cover has a stepped bottomed cylindrical shape in which the closed end side has a small diameter and the open end side has a large diameter.

  By adopting such a shape, the distance between the inner wall of the metal cover and the temperature detection element can be extremely shortened, and the responsiveness of the temperature sensor is improved.

  In a ninth aspect of the invention, the temperature detecting element is an NTC thermistor made of a transition metal oxide sintered body.

  Since the transition metal oxide NTC thermistor element can detect a good temperature at a high temperature of 1000 ° C. or higher and 1300 ° C. or lower, it is suitable for measuring an exhaust gas temperature of an automobile.

  A tenth aspect of the present invention includes a bottomed cylindrical metal cover whose one end is closed and the other end is open, and a temperature detection element housed inside the closed end of the metal cover and connected to a pair of electrode wires. A warm part, a cylindrical metal protective tube inserted into the open end of the metal cover, and a signal provided outside by being electrically connected to the electrode wire provided inside the metal protective tube A protective tube portion including a pair of signal lines and an insulating member for insulating them; and a screw portion for holding the protective tube portion and attaching and fixing the temperature sensing portion at a predetermined position in the fluid to be measured. In the manufacturing method of the temperature sensor provided with the housing part, a through hole for discharging air bubbles is provided at the bottom of the closed end of the metal cover, and the temperature detection element is filled with a gap between the metal cover and the temperature detection element. Insulating holding filler Was injected in a slurry state in a manufacturing cover, the bubbles captured at the tip of the metallic cover, characterized in that discharged from the through hole.

  Since the filler is injected into the metal cover while discharging the bubbles from the through-holes in a slurry state, the filler can be uniformly filled without leaving bubbles at the bottom of the metal cover. If such a manufacturing process is followed, entrainment of bubbles in the filler can be reliably prevented, and the filling process can be stabilized. Therefore, the manufacturing process management can be simplified and the reliability of the temperature sensor is improved.

  According to an eleventh aspect of the present invention, a through hole having a diameter of 50 μm to 300 μm is formed in the closed end of the metal cover.

  If it is the through-hole of the said range, besides being easy to process, the sealing after the said temperature detection element insertion is also easy.

  In the twelfth aspect of the present invention, bubbles entrained in the filler are discharged from a plurality of through holes.

  The bubbles are more effectively discharged from the plurality of through holes.

  According to a thirteenth aspect of the present invention, the temperature detection element is fixed by solidifying the filler by heat drying after the temperature detection element is inserted into the filler in the slurry state.

  Since the temperature detection element is inserted into the filler in the slurry state, the temperature detection element, the pair of signal lines, and the pair of electrode lines are completely covered with the filler. In addition, since the dispersion medium in the filler evaporates from the through holes during drying by heating, the drying can be performed smoothly.

  In the invention of claim 14, the through hole is sealed by a sealing means.

  By sealing the through hole, the temperature detecting element housed in the metal cover can be kept in a sealed state.

  According to a fifteenth aspect of the invention, the through hole is welded and sealed by laser irradiation.

  The bubble discharge through hole can be easily welded and sealed by laser irradiation.

  In the invention of claim 16, the metal cover is drawn into a stepped bottomed cylindrical shape in which the closed end side has a small diameter and the open end side has a large diameter.

  The stepped bottomed cylindrical shape can be easily formed by drawing.

  In the invention of claim 17, the inner diameter of the small diameter portion of the metal cover is processed to 3 mm or less.

  The distance between the temperature detection element and the inner wall of the metal cover can be made extremely short, and the responsiveness as a temperature sensor is excellent.

  In the eighteenth aspect of the invention, the gap between the metal cover and the temperature detecting element is filled with cement containing an inorganic binder and containing alumina as a main component.

  When an inorganic binder is used, it can be cured only by low-temperature drying, and a packed layer excellent in chemical stability, mechanical strength, and high insulation that can withstand a high temperature environment of 1000 ° C. or higher can be obtained.

  According to a nineteenth aspect of the present invention, the temperature detecting element is formed of a ceramic raw material powder containing a plurality of transition metal oxides, and a pair of platinum wires is inserted into the formed body, and is integrated in an oxidizing atmosphere. To obtain an NTC thermistor.

  By using a platinum wire as the electrode wire, it can be fired in an oxidizing atmosphere simultaneously with the transition metal oxide, and the transition metal oxide molded body and the pair of platinum wires are integrally sintered, and the resistance increases due to an increase in temperature. An NTC thermistor having a decreasing NTC (negative temperature coefficient) characteristic is obtained.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of a bubble can be prevented in the filler which hold | maintains a temperature sensing part, and the temperature sensor excellent in responsiveness and earthquake resistance can be provided.

An embodiment of the present invention will be described with reference to FIG. FIG. 1A shows the overall configuration of a temperature sensor 1 in which the present invention is implemented. The temperature sensor 1 is composed of a temperature sensing portion 10, a protective tube portion 12, and a housing portion 13.
The housing portion 13 is made of a metal such as SUS, and is provided with a rib 131 that holds the protective tube portion 12, a screw portion 132 for fixing the mounting position, and a hexagonal portion 133 for screw tightening.

  FIG.1 (b) shows the cross-sectional detailed drawing of the said temperature sensing part 10 which is the principal part of embodiment of this invention, and demonstrates the structure of the said temperature sensing part 10 with reference to FIG.1 (b) below. .

The temperature detection element 101 is made of a transition metal oxide NTC thermistor having Y (Cr, Mn) O ₃ as a main component as disclosed in Patent Document 2, for example. The temperature detection element 101 includes a pair of platinum electrode wires 102. Are connected together.
The transfer metal oxide-based NTC thermistor uses a ceramic raw material powder containing a plurality of transition metal oxides to form a cylindrical shaped body having a pair of insertion holes for inserting electrode wires, A sintered body in which the formed body and the platinum wire are integrated is obtained by inserting the platinum wire and oxidizing and firing at a high temperature of 1600 ° C., for example.

A pair of signal lines 121 for taking out an electrical signal corresponding to the temperature of the fluid to be measured measured by the temperature detecting element 101 is connected to the electrode line 102 by, for example, laser welding. For the signal line 121, for example, a heat-resistant and highly conductive metal such as SUS or platinum-Rh is used.
The signal line 121 is insulated and supported in a cylindrical metal protective tube 123 made of SUS or the like via an insulating member 122.

The metal cover 104 is made of a metal such as SUS and has a bottomed cylindrical shape with the other end closed and the other end opened. When the filler is injected into the metal cover at the bottom on the closed end side, the metal cover 104 is formed. For example, a bubble discharge through hole 111 having a diameter of 100 μm is formed to discharge bubbles entrained in the filler.
The open end side of the metal cover 104 is a large diameter portion 1041 because the metal protective tube 123 is inserted, and the closed end side is a small diameter portion 1043 having an inner diameter of 1.88 mm and an outer diameter of 2.48. The large-diameter portion 1041 and the small-diameter portion 1043 are drawn in stages as an intermediate-diameter portion 1042 having an inner diameter of 2.37 mm and an outer diameter of 2.97 mm.

  The bubble discharge through hole 111 is welded and sealed by a sealing means such as laser welding, and a weld bead 112 is formed at the welded portion.

  The gaps between the metal cover 104 and the temperature detecting element 101, the electrode wire 102, and the signal wire 121 are filled with a filler 103 such as alumina cement mainly composed of alumina containing an inorganic binder such as silica sol or alumina sol. It has been.

  The metal cover 104 and the metal protective tube 123 are welded and fixed over the entire circumference at the welded portion 105 by, for example, laser welding.

The outer diameter of the temperature detection element 101 side distal end portion 123b of the metal protective tube 123 is substantially the same as the inner diameter of the diameter middle portion 1042 of the metal cover 104, and the protective tube distal end portion 123b and the metal A gap 106 is formed between the inner wall of the cover 104 and the thermal insulation between the temperature sensing part 10 and the protective tube part 12 is ensured.
The inner diameter of the small-diameter portion 1043 of the metal cover 104 can be appropriately set within a range from a diameter of 1.5 mm to a diameter of 3.0 mm.

  Here, referring to FIGS. 8A to 8F, the bubble generation mechanism estimated in the structure of the conventional temperature sensor will be described, and the present invention will be described with reference to FIGS. 2A to 2G. The effect of will be described.

As shown in FIG. 8 (a), the filling nozzle 3 is inserted into the metal cover 104b, and the filler 103 in the slurry state is inserted from the position as close as possible to the bottom of the metal cover 104b using the filling nozzle 3. Injection is performed while pulling up the filling nozzle 3.
In order to inject from a position closer to the bottom wall of the metal cover 104b, the outer diameter of the filling nozzle 3 is preferably as thin as possible. However, when the alumina cement is used as the filler 103, the slurry Since the viscosity is relatively high, if the inner diameter of the filling nozzle 3 is smaller than 0.9 mm in diameter, it becomes difficult to push out the filler 103 from the filling nozzle 3 inevitably. 3 is limited in inner diameter and outer diameter.

  For this reason, when the filler 103 is pushed out from the filling nozzle 3 as shown in FIG. 8B in which the portion A in FIG. 8A is enlarged, it is expanded into an elliptical shape by the surface tension and further pushed out. As shown in FIG. 8C, the metal cover 104b comes into contact with the side wall before reaching the bottom wall of the metal cover 104b.

At this time, the filler 103 fills the gap between the side wall of the metal cover 104 b and the filling nozzle 3, and the air passage left below the filler 103 is closed.
In addition, since the slurry of the filler 103 is a pseudoplastic fluid having a relatively high viscosity, the air once taken in cannot pass through the filler 103 and form bubbles 2 as shown in FIG. If the filler 103 is left behind and the injection of the filler 103 is continued, bubbles 2 remain in the closed end of the metal cover 104b as shown in FIG. 8 (e), and the bubbles 2 cannot be removed from the filler 103. Disappear.

  In this state, as shown in FIG. 8F, the temperature detection element connected to the pair of electrode wires 102 connected to the pair of signal lines 121 insulated and held in the metal protective tube 123 by the insulating member 122. When 101 is inserted into the slurry-like filler 103 and the filler 103 is heated and dried, the metal cover 104b and the metal protective tube 123 are fixed by welding, as shown in FIG. As described above, the temperature detecting element 101 is held in a state where the bubble 2 is left behind at the bottom of the metal cover 104b in front of the temperature detecting element 101.

On the other hand, in the first embodiment of the present invention, as shown in FIG. 2A, a bubble discharge through hole 111 is provided at the bottom of the closed end of the metal cover 104.
As shown in FIG. 2A, the filler nozzle 3 is inserted into the metal cover 104, and the slurry-like filler 103 is positioned as close as possible to the bottom of the metal cover 104 using the filler nozzle 3. Then, the filling nozzle 3 is poured while being pulled up.

As shown in FIG. 2B in which the portion A in FIG. 2A is enlarged, the slurry-like filler 103 is swelled and pushed out from the tip of the filling nozzle 3 by the surface tension, and is pushed out as shown in FIG. As shown in FIG. 2, the air bubbles 2 are confined below the filler 103 by contacting the side wall of the metal cover 104 before reaching the bottom of the metal cover 104.
Up to this point, it is the same as in the prior art, but if the filler 103 is further injected, the bubbles 2 are pushed out from the through holes 111 provided in the metal cover 104 as shown in FIG. The bubbles 2 are gradually reduced and disappear.
At this time, if vibrations such as ultrasonic waves are applied, the bubbles are more effectively discharged.

  After injecting a predetermined amount of the filler 103 as shown in FIG. 2 (e), the filling nozzle 3 is pulled up, and as shown in FIG. 2 (f), the metal protective tube 123 is insulated and held by the insulating member 122. The temperature detecting element 101 connected to the pair of electrode wires 102 connected to the pair of signal lines 121 is inserted into the slurry-like filler 103, the filler 103 is heated and dried, and then the metal When the cover 104 and the metal protective tube 123 are fixed by welding, as shown in FIG. 2G, the air bubble 2 between the temperature detection element 101 and the metal cover 104 is removed, and the above-mentioned The temperature detection element 101 is held.

  Since the filler 103 is a high-viscosity slurry, it rarely leaks from the through hole 111 provided in the metal cover 104.

  When the through hole 111 is a through hole 111a having a diameter in the range of 50 μm to 170 μm, the filler 103 does not leak from the through hole 111a as shown in the left diagram of FIG. 3 (before welding). Further, as shown in the central view of FIG. 3, the through hole 111a can be directly sealed by, for example, laser welding without using a welding rod. As shown in the right side of FIG. 3 (after welding), after welding, a weld bead 112a is formed at the bottom of the metal cover 104, and the through hole 111a is completely sealed. Laser welding conditions are, for example, 2.1 J to 2.5 J, 10 ms to 14 ms.

  When the through hole 111 is a through hole 111b having a diameter in the range of 200 μm to 300 μm, the filler 103 leaks from the through hole 111b as shown in the left figure of FIG. 4A (before welding). Absent. Further, as shown in the center view of FIG. 4A, when the through hole 111b is directly welded and sealed by, for example, laser welding without a welding rod, as shown in the right view of FIG. 4A (after welding), After welding, a weld bead 112b is formed at the bottom of the metal cover 104, and the through hole 111b can be welded and sealed, but a pinhole-shaped blowhole is formed at the center of the bead 112b, A welding sag 113b may be formed.

  In such a case, more preferably, as shown in the central view of FIG. 4B, the through hole 111c is formed by laser welding or the like using a welding rod of the same material as the metal cover 104, for example, 0.27 mm in diameter. When welded, as shown in the right figure of FIG. 4B (after welding), after welding, a substantially hemispherical weld bead 112c is formed at the bottom of the metal cover 104, and the through hole 111c is completely sealed. it can.

  When the through hole 111 is a through hole 111d provided with a diameter of 500 μm or more, the filler 103 is shown as the filler 103d from the through hole 111d as shown in the left figure of FIG. 5A (before welding). May leak. After removing the leaked filler 103d, as shown in the central view of FIG. 5 (a), if the through hole 111d is directly welded and sealed by, for example, laser welding without a welding rod, the right side of FIG. As shown in the figure (after welding), although the weld bead 112d is formed along the inner periphery of the through hole 111d, the through hole 111d cannot be sealed.

  In such a case, as shown in the central view of FIG. 5B, the through hole 111d is welded by, for example, laser welding using a welding rod made of the same material as that of the metal cover 104. As shown in the figure (after welding), after welding, an irregular weld bead 112e is formed at the bottom of the metal cover 104, and the through hole 111d can be completely sealed, but it is not preferable in terms of appearance.

When the bubble discharge through-hole 111 is provided with a diameter of 50 μm or less, the bubble 2 may not be sufficiently discharged and may remain in the filler 103.
Therefore, the bubble discharge through-hole 111 is preferably provided in a diameter range of 50 μm to 300 μm. More preferably, if the diameter is in the range of 70 μm to 170 μm, direct welding sealing is possible without a welding rod and the finish is also good.

  In the first embodiment of the present invention, as shown in FIG. 6A, one of the bubble discharge through holes 111 is provided in the center of the closed end bottom of the metal cover 104. As shown in the figure, a plurality of the bubble discharge through holes 111 may be provided in the closed end bottom portion of the metal cover 104. Further, as shown in FIG. 6C, a plurality of them may be provided not only on the closed end bottom portion of the metal cover 104 but also on the side wall of the metal cover 104. With such a structure, the probability that the bubbles are discharged increases, and the filling rate in the metal cover is further improved.

  Needless to say, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. For example, in the embodiment of the present invention, the sealing means by laser welding has been described, but it may be by direct welding such as MIG welding, TIG welding, arc welding, plasma welding, brazing, riveting, spraying, etc. Overlay welding may be used.

In the embodiment of the present invention, the temperature detection element is formed in a columnar shape, but may be a flat plate shape or a polygonal column shape.
In the present embodiment, the metal cover is formed by drawing, but may be formed by cutting.
In this embodiment, the inorganic binder contained in the filler is a material that solidifies alumina cement by heat drying, but a self-curing inorganic binder may be used.
Further, the fluid to be measured is not limited to the exhaust gas, but may be a liquid such as water or oil.

(A) is a partial cross section figure which shows the whole structure of the temperature sensor which concerns on the 1st Embodiment of this invention, (b) is the temperature sensitive part in Fig.1 (a) which is the principal part of this invention. FIG. It is a schematic diagram which shows the effect of this invention from filler injection | pouring in the 1st Embodiment of this invention to temperature-sensitive part insertion in order of a manufacturing process in steps (a)-(g). It is a schematic diagram which shows the sealing method of the bubble discharge through-hole of diameter 50 micrometers to 170 micrometers in the 1st Embodiment of this invention, and the state after sealing. (A) is a schematic diagram showing a sealing method when a welding rod is not used and a state after sealing, with respect to a bubble discharge through hole having a diameter of 200 μm in the first embodiment of the present invention, and (b) shows a welding rod. It is a schematic diagram which shows the sealing method at the time of a certain use, and the state after sealing. (A) is a schematic diagram showing a sealing method when a welding rod is not used and a state after sealing, with respect to a bubble discharge through hole having a diameter of 500 μm in a comparative example of the present invention, and (b) using a welding rod. It is a schematic diagram which shows the sealing method in a case, and the state after sealing. (A)-(c) is a schematic diagram which shows the example of arrangement | positioning of the bubble discharge through-hole of this invention. (A) is a fragmentary sectional view which shows the whole structure of the temperature sensor in the conventional structure, (b) is detailed sectional drawing of the temperature sensing part 10 in FIG. 7 (a) which shows the problem in the conventional structure. is there. It is the schematic diagram which shows a mode that a bubble is taken in following the manufacturing process from filler injection | pouring in the conventional structure to temperature-sensitive part insertion in steps of (a)-(f).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Temperature sensor 10 Temperature sensing part 101 Thermistor element 102 Electrode wire (platinum)
103 Filler (Inorganic binder-containing alumina cement)
104 Metal cover (SUS)
105 welded portion 106 heat insulating portion 111 bubble discharge through hole 112 weld bead 12 protective tube portion 121 signal line (SUS)
122 Insulating member 123 Metal protective tube (SUS)
1231 Large diameter portion 1232 Medium diameter portion 1233 Small diameter portion 13 Housing portion 131 Protective tube portion holding rib (SUS)
132 Fixing screw part 133 Tightening hexagon part

Claims (19)

A temperature-sensing portion comprising a bottomed cylindrical metal cover having one end closed and the other end open, and a temperature detection element housed inside the closed end of the metal cover and connected to a pair of electrode wires;
A cylindrical metal protective tube inserted into the open end of the metal cover, and a pair of signal lines provided inside the metal protective tube and electrically connected to the electrode wire to extract a signal to the outside A protective tube made of an insulating member for insulating them;
A temperature sensor including a housing portion having a screw portion for holding and protecting the temperature sensing portion at a predetermined position in the fluid to be measured while holding the protection tube portion;
The temperature detection element is held in the metal cover by a filler that fills a gap between the metal cover and the temperature detection element, and
A temperature sensor having a bubble discharge through hole in a closed end bottom portion of the metal cover, and bubbles taken into the closed end of the metal cover are discharged by the bubble discharge through hole.   The temperature sensor according to claim 1, further comprising a sealing means for sealing the bubble discharge through hole.   The temperature sensor according to claim 1 or 2, wherein the bubble discharging through hole is a through hole having a diameter in the range of 50 µm to 300 µm.   The temperature sensor according to any one of claims 1 to 3, wherein a plurality of the bubble discharge through holes are provided.   The temperature sensor according to any one of claims 1 to 4, wherein the sealing means is a weld bead formed by laser welding.   The temperature sensor according to any one of claims 1 to 5, wherein an inner diameter of the metal cover is 3 mm or less.   The temperature sensor according to any one of claims 1 to 6, wherein the filler is a cement containing an inorganic binder and containing alumina as a main component.   The temperature sensor according to any one of claims 1 to 7, wherein the metal cover has a stepped bottomed cylindrical shape in which the closed end side has a small diameter and the open end side has a large diameter.   The temperature sensor according to any one of claims 1 to 8, wherein the temperature detection element is an NTC thermistor made of a transition metal oxide sintered body. A temperature-sensing portion comprising a bottomed cylindrical metal cover having one end closed and the other end open, and a temperature detection element housed inside the closed end of the metal cover and connected to a pair of electrode wires;
A cylindrical metal protective tube that is inserted into the open end of the metal cover, and a pair of signal wires that are provided inside the metal protective tube and are electrically connected to the electrode wires to extract signals to the outside And a protective tube portion made of an insulating member for insulating them,
In a method of manufacturing a temperature sensor comprising: a housing having a screw part for holding and fixing the temperature sensing part at a predetermined position in a fluid to be measured while holding the protective tube part;
A through hole for discharging air bubbles is provided at the bottom of the closed end of the metal cover, and a filler filling the gap between the metal cover and the temperature detection element and insulatingly holding the temperature detection element is slurried in the metal cover. A temperature sensor manufacturing method characterized by injecting air bubbles in a state and discharging air bubbles taken into the tip of the metal cover from the through hole.   The temperature sensor manufacturing method according to claim 10, wherein a through hole having a diameter of 50 μm to 300 μm is formed in the closed end of the metal cover.   The temperature sensor manufacturing method according to claim 10 or 11, wherein bubbles entrained in the filler are discharged from a plurality of through holes.   The temperature sensor according to any one of claims 10 to 12, wherein the temperature detection element is fixed by solidifying the filler by heat drying after the temperature detection element is inserted into the filler in the slurry state. Production method.   The temperature sensor manufacturing method according to claim 10, wherein the through hole is sealed by a sealing means.   The temperature sensor manufacturing method according to claim 10, wherein the through hole is welded and sealed by laser irradiation.   The temperature sensor manufacturing method according to any one of claims 10 to 15, wherein the metal cover is drawn into a stepped bottomed cylindrical shape in which the closed end side of the metal cover has a small diameter and the open end side has a large diameter. .   The temperature sensor manufacturing method according to any one of claims 10 to 16, wherein an inner diameter of the small diameter portion of the metal cover is processed to 3 mm or less.   The temperature sensor manufacturing method according to any one of claims 10 to 17, wherein a gap between the metal cover and the temperature detecting element is filled with a cement containing an inorganic binder and containing alumina as a main component.   The temperature detection element forms a molded body using ceramic raw material powder containing a plurality of transition metal oxides, a pair of platinum wires is inserted into the molded body, and the molded body and the platinum wire are bonded in an oxidizing atmosphere. The temperature sensor manufacturing method according to any one of claims 10 to 18, wherein the temperature sensor is integrally fired to form an NTC thermistor.