JP6571156B2 - Micro heater with non-heat generating part - Google Patents

Description

  The present invention relates to a microheater having a non-heat generating portion among microheaters in which an inorganic insulating material powder is interposed in a metal sheath tube and a heating wire generating Joule heat by energization is accommodated.

  The micro-heater is a flexible heater in which an inorganic insulating powder is interposed in a metal sheath tube and accommodates a heating wire that generates Joule heat when energized. The basic structure is shown in FIGS. 4 and 5. There are two types. FIG. 4 is a cross-sectional view showing a basic first configuration of a conventional microheater, and FIG. 5 is a cross-sectional view showing a basic second configuration of the conventional microheater.

  4 (a) and 5 (a) are longitudinal sectional views, and FIG. 4 (b) and FIG. 5 (b) are EE cross sections of FIG. 4 (a) and FIG. 5 (a), respectively. It is a figure of the FF cross section. However, the terminal sleeve 7 and the insulation coatings 13 and 15 of the lead wires 80 and 81 for supplying electricity are drawn in outline, and for ease of viewing, FIGS. 4 (b) and 5 (b) are shown in FIG. a), drawn at a larger scale than FIG.

  In the microheater 10 shown in FIG. 4, the heating wire 4 is accommodated in the metal sheath tube 3 with the inorganic insulating material powder 6 interposed therebetween, and terminal sleeves 7 are provided at both ends thereof. The conductors 14 and 16 exposed from the insulating coatings 13 and 15 of the lead wires 80 and 81 are connected to the terminal. In the metal outer frame of the terminal sleeve 7, the end of the heating wire 4 and the tips of the conductors 14 and 16 are connected so that moisture does not enter the inorganic insulating powder 6 and the insulation resistance does not decrease. A seal is provided.

  The microheater 20 shown in FIG. 5 is different from the microheater 10 shown in FIG. 4 in that the reciprocating heating wire 4 is accommodated in the metal sheath tube 3 with the inorganic insulating material powder 6 interposed therebetween. Is provided only on one side. The role of the terminal sleeve 7 is the same as that of the terminal sleeve 7 of FIG. 4, and the end of the heating wire 4 and the ends of the conductors 14 and 16 exposed from the insulating coatings 13 and 15 of the lead wires 80 and 81 in the metal outer frame. In addition, a seal is provided to prevent moisture from entering the inorganic insulating material powder 6 and lowering the insulation resistance.

  As a material of the heating wire 4 of the microheaters 10 and 20 of FIGS. 4 and 5, nichrome having a high resistivity and a large amount of heat generation is used except for special exceptions.

  The specific structure inside the terminal sleeve 7 in FIGS. 4 and 5 is typically the one shown in FIG. 1 of Patent Document 1 by the same applicant as the present patent application. As shown in the figure, the end of the heating wire (reference numeral 22) and the conductor of the lead wire (reference numeral 13) in the metal outer frame (reference numeral 11) interpose an insulating material (reference numerals 14 and 17). The outer frame (reference numeral 11) is housed, and a seal (reference numeral 15) is provided at the end of the metal outer frame (reference numeral 11). In addition, in each terminal sleeve 7 in the structure of FIG. 4, the heating wire (reference numeral 22) and the conductor (reference numeral 13) of FIG. Here, the reference numerals in parentheses are those shown in FIG.

  When the object to be heated and the terminal seal are separated, for example, when the object to be heated is in the container, the terminal sleeve 7 in FIGS. 4 and 5 is usually placed outside the container, and the heating wire 4 and the inorganic insulating material powder A metal sheath tube 3 containing 6 is laid to the object to be heated in the container. In this case, in the microheaters 10 and 20 of FIGS. 4 and 5 where the heating wire 4 is provided over the entire length in the metal sheath tube 3, the portions that do not need to be heated are also heated, and the microheaters 10 and 20 are unnecessary. Inconveniences such as damage to the equipment due to excessive power consumption and heating of the equipment in the container having a low heat-resistant temperature other than the object to be heated occur.

  In order to avoid such an adverse effect when the object to be heated and the terminal seal are separated from each other, conventionally, only the part that is heated in contact with the object to be heated generates heat, and the other part does not generate heat. In many cases, micro heaters 11 and 21 shown in FIG. FIG. 6 is a cross-sectional view showing a basic first configuration of a conventional microheater having a non-heat generating portion, and FIG. 7 is a cross-sectional view showing a basic second configuration of a conventional micro-heater having a non-heat generating portion. 6 and 7 show the outer shapes of the insulating coatings 13 and 15 of the terminal sleeve 7 and the lead wires 80 and 81, similarly to FIGS.

  4 and FIG. 5, while the heating wire 4 made of nichrome, which has a high electrical resistivity, generates heat over the entire length, the micro heaters 11 and 21 in FIGS. A heat generating part in which the heating wire 4 made of nichrome wire is housed, a non-heating part in which the non-heating wire 17 made of copper having a small heat generation amount due to low electrical resistivity is housed, and an alloy of nichrome and copper It can be divided into an intermediate heating part where the part 18 exists. Except for the presence of the non-heat generating wire 17 and the alloy portion 18, the same structure as that of the microheaters 10 and 20 in FIGS. 4 and 5 is used, and the same components are shown in FIGS. 6 and 7 by using the same reference numerals. .

  In the microheaters 11 and 21 shown in FIGS. 6 and 7, only the portion that is heated in contact with the object to be heated is used as a heat generating portion, so that unnecessary power consumption is suppressed and damage to the equipment due to unnecessary heating is avoided. be able to.

  The portion shown in FIGS. 4 to 7 in which a metal sheath such as a heating wire 4 and a non-heating wire 17 is accommodated by interposing an inorganic insulating material powder 6 in a metal sheath tube 3 is often referred to as a micro heater cable. Hereinafter, the micro heater cable refers to this portion. As shown in FIGS. 7 and 8 of Patent Document 2, the microheater cable is first made thicker than the finished diameter, and this is reduced in diameter by die drawing or swaging, and the predetermined value shown in FIG. Finished in diameter micro heater cable.

  In the microheater having the non-heat generating portion shown in FIGS. 6 and 7, the metal wire accommodated when making the micro cable thicker than the finished diameter before the diameter reduction is formed at both ends of the heating wire 4 thicker than the finished diameter made of nichrome. A non-heating wire 17 made of copper having substantially the same diameter is butt welded.

  In the butt welding of the heating wire 4 and the non-heating wire 17, an alloy part of nichrome which is the material of the heating wire 4 and copper of the material of the non-heating wire 17 is inevitably generated, and this alloy part is expanded after being reduced in diameter. The alloy portion 18 becomes an intermediate heat generating portion having an intermediate resistance between nichrome and copper.

  Note that the generation of Joule heat is not zero even with copper wires. Since the calorific value per unit length is proportional to the square of the applied current and the resistance value per unit length, the calorific value per unit length of two connected lines through which the same current flows is per unit length. It is proportional to the resistance value. If the two types of wires have the same diameter, the resistance value per unit length is proportional to the electrical resistivity, so the amount of heat generated per unit length is proportional to the electrical resistivity. 6 and 7, the electrical resistivity of copper is about 1.6% of nichrome, so the amount of heat generated per unit length is about 1 of the amount of heat generated per unit length of the heat generating portion. It is 6%. As described above, the non-heat generating line and the non-heat generating part generate heat although they are small compared to the heat generating line and the heat generating part. In the following, lines and portions that generate less heat than heat generation lines and heat generation parts are referred to as non-heat generation lines and non-heat generation parts, respectively.

JP 2010-257582 A JP 2017-1112079 A

  As is well known, it is difficult to weld dissimilar metals. As described above, in the conventional microheater having the non-heating portion shown in FIGS. 6 and 7, butt welding before the diameter reduction of the heating wire 4 made of nichrome and the non-heating wire 17 made of copper is necessary. is there.

  In this butt weld portion, the bulge of the alloy portion 18 and the dent 22 of the non-heating wire 17 as shown in FIG. The reason for this is that the melting point of copper is lower than that of nichrome and the thermal conductivity of copper is high. Therefore, during butt welding, the copper melts extensively before being heated to the melting point of nichrome, and the copper melted by the surface tension. Still moves to the solid nichrome side, and after welding, the shape shown in FIG. 8 (a), that is, the non-heating wire 17 side of the alloy portion 19 swells around the entire circumference, It is considered that a dent 23 is formed on the entire circumference near the boundary, and when this is reduced to the finished diameter, the bulge of the alloy portion 18 and the dent 22 of the non-heating line 17 in FIG.

  Since the thermal expansion coefficients of the nichrome heating wire 4 and the copper non-heating wire 17 are different from those of the inorganic insulating material powder 6 and the metal sheath tube 3, the heating wire 4 and the non-heating wire 17 are used when the microheater is used. Tensile and compressive stresses are generated. This stress is particularly large when the temperature rises and falls when the temperature difference with the metal sheath 3 increases, and when the temperature rises and falls repeatedly, the dent 22 of the copper non-heating wire 17 is generated and the diameter is narrowed. The conventional microheater having a non-heating portion has a problem that disconnection may occur.

  As a countermeasure against this problem, in a conventional microheater having a non-heating part, an alloy wire mainly composed of nickel, an alloy wire mainly composed of copper, having an intermediate thermal conductivity or melting point between copper and nichrome, or In some cases, a copper-clad nickel-clad wire or the like is used as a relay wire between a heating wire and a non-heating wire. In this case, since a short relay wire is butt welded to a heating wire made of nichrome, and a copper non-heating wire is butt welded to the relay wire, the dent of the non-heating wire is reduced. However, the dent does not disappear at all, and the disconnection problem cannot be completely solved. Also, in this method, the electrical resistance of the relay line is usually an intermediate value between nichrome and copper, so the relay line becomes the intermediate heat generating part shown in FIGS. 6 and 7, and the intermediate heat generating part becomes longer. Problems arise. If the intermediate heat generating portion becomes longer, useless power consumption in this portion increases, and the adverse effect of increasing the possibility that a portion that should not be heated increases.

  The present invention has been made in view of the disconnection problem caused by the dent of the non-heat generation line caused by the welding of different metals in the conventional microheater having the non-heat generation section. It aims at providing a certain micro heater.

(First aspect)
A microheater having a non-heat generating portion according to the present invention,
In a microheater in which a heat generating wire made of a metal that generates Joule heat by energization in a metal sheath tube is housed, and an inorganic insulating material powder is filled between the metal sheath tube and the heat generating wire,
A part of the heating wire is plated with a metal having a lower electrical resistivity than the material of the heating wire on the entire surface in the circumferential direction, and the amount of heat generated by plating is less than that of an unplated heating wire. The part where the exothermic line is formed is a non-heat generating part.

  Since the plated portion has a lower electrical resistivity than the unplated portion, the generation of Joule heat is suppressed and becomes a non-heat generating portion.

  In the microheater having the non-heat generating portion according to the present invention, since the butt welding of the heat generating wire and the non-heat generating wire is not performed as in the conventional case, there is no dent of the non-heat generating wire caused by the butt welding, and the disconnection caused by the dent is Does not occur. Further, since the butt welding of the heat generating wire and the non-heat generating wire is not performed, there is no alloy portion of the heat generating wire and the non-heat generating wire, so that there is no significant intermediate heat generating portion, and there is no wasteful power consumption there.

(Second aspect)
In the above-described microheater having a non-heat generating portion, the material of the heating wire is preferably nichrome, and the material of the metal plating the surface of the heating wire is preferably copper.

  By using such a material, the amount of heat generated by the non-plated heating wire is equivalent to that of a conventional microheater, and by using copper with a low electrical resistivity as the plating material, heat is generated from the non-heating part. The amount can be efficiently controlled.

(Third aspect)
In a microheater with a non-heating part, where the heating wire material is Nichrome and the plating material is copper, the thickness of the metal plated on the surface of the heating wire is 3.5% or more of the outer diameter of the heating wire. It is desirable that the thickness be

  As described above, the heat generation amount per unit length is proportional to the resistance value per unit length. The resistance value of the copper-plated wire on the surface of the nichrome wire can be obtained as the resistance of a circuit in which the resistance of the nichrome wire and the resistance of the copper plating are connected in parallel. The electrical resistivity of copper is about 1 of that of nichrome. A unit of wire in which copper is plated on a nichrome wire of the same diameter as the heating wire using the fact that the resistance value per unit length is a value obtained by dividing the electrical resistivity by the cross-sectional area. When the resistance value per length is obtained, the unit of the non-heat generating part where the plated part is present when the thickness of the copper plating is 3.5% of the diameter of the heating wire made of nichrome. The resistance value per length is 10% of the resistance value per unit length of the heat generating portion where there is an unplated heating wire.

  Therefore, by setting the thickness of the plated copper to 3.5% or more of the outer diameter of the heating wire, the heating value per unit length of the non-heating part is reduced to the heating value per unit length of the heating part. Of 10% or less.

(Fourth aspect)
Furthermore, in a microheater having a non-heat generating portion in which the heating wire material is nichrome and the plating material is copper, the thickness of the metal plating the surface of the heating wire is 20% or more of the outer diameter of the heating wire. Thickness is more desirable.

  When the thickness of the plated copper is 20% of the outer diameter of the heating wire, when the resistance value per unit length of the non-heating portion is obtained in the same manner as described above, the heating portion where there is an unplated heating wire The resistance value per unit length is about 1.6%, which is equivalent to the resistance value per unit length of a conventional copper non-heating wire.

  Therefore, by setting the thickness of the plated copper to 20% or more of the outer diameter of the nichrome heating wire, the heating value per unit length of the non-heating part relative to the heating value per unit length of the heating part is reduced. The ratio of the conventional copper can be made equal to or less than about 1.6% in the case of a non-heating wire made of a material. Since the amount of heat generated by the non-heat generating portion is reduced, unnecessary power consumption is eliminated, and heating at locations where heating is unnecessary is also reduced.

  The outer diameter that has been used in the industry so far of the part called micro heater cable that contains the heating wire and the part plated with the inorganic insulating powder in the metal sheath tube is 1.6 mm to 6 .4 mm is the mainstream, and the outer diameter of the nichrome heating wire is generally 0.25 mm to 1.25 mm. When the thickness of the copper plating is 20% of the outer diameter of the heating wire, the plating thickness of the φ1.25 mm heating wire is 0.25 mm.

  Here, in the production of a microheater cable having a non-heat generating portion according to the present invention, as in the prior art, a thicker one than the finished diameter is first made, and then the diameter is reduced by die drawing or swaging to obtain a microheater cable having a predetermined diameter. Finished. In a microheater without a non-heat generating part, the diameter reduction rate is reduced to make a long microheater cable, and this is cut to produce a large number of microheaters. On the other hand, in a microheater with a non-heat generating portion, the position of the heat generating portion varies depending on the place where it is used. Also, since there are a heat generating portion and a non-heat generating portion, a long micro heater cable is cut and multiple micro heaters are cut. Since the heater cannot be manufactured, the diameter reduction rate is usually about one-half to one-third, and the micro-heater having the non-heat generating portion according to the present invention has the same diameter reduction rate. In order to set the copper plating thickness at the finished diameter to 0.25 mm, the copper plating thickness before reduction is 0.5 mm with a reduction ratio of 1/2, and the reduction ratio is 1/3. Although 0.75 mm is necessary, this thickness is a thickness that allows copper plating without any particular difficulty.

  As described above, the microheater having a non-heat generating portion according to the present invention does not have a decrease in diameter due to a dent near the welded portion with the heat generating wire that may occur in the non-heat generating wire. Therefore, there is no concern about disconnection. In addition, there is an incidental effect that there is no unnecessary intermediate heat generating portion that occurs in the welded portion of the heat generating wire and the non-heat generating wire.

Sectional drawing which shows 1st Embodiment of the micro heater with a non-heat-generating part by this invention Sectional drawing which shows 2nd Embodiment of the microheater with a non-heating part by this invention Sectional drawing which shows the boundary part of the exothermic line and non-exothermic line in 1st Embodiment of this invention Sectional drawing which shows the basic 1st structure of the conventional microheater Sectional drawing which shows the 2nd basic structure of the conventional microheater Sectional drawing which shows the basic 1st structure of the conventional microheater with a non-heat-generating part Sectional drawing which shows the 2nd basic structure of the conventional microheater with a non-heat-generating part Sectional drawing which shows the boundary part of the exothermic line and non-exothermic line in the basic 1st structure of the conventional microheater with a non-exothermic part

  First and second embodiments for carrying out the present invention will be described.

(First embodiment)
FIG. 1 is a sectional view showing a first embodiment of a microheater having a non-heat generating portion according to the present invention, FIG. 1 (a) is a longitudinal sectional view, and FIGS. 1 (b) and 1 (c) are respectively diagrams. It is the AA cross section of 1 (a), and a BB cross section. However, the terminal sleeve 7 and the insulation coatings 13 and 15 of the lead wires 80 and 81 in FIG. 1A are drawn in outline, and FIG. 1B and FIG. It is drawn at a large scale. In addition, the reference numerals in the drawings are the same as those in FIGS. 4 to 7 for components having the same functions as those of the conventional microheater shown in FIGS. 4 to 7, and this also applies to FIG. It is.

  The microheater 1 having a non-heat generating portion according to the first embodiment accommodates a heating wire 4 made of metal and generating Joule heat when energized with an inorganic insulating material powder 6 interposed in a metal sheath tube 3. The heating wire 4 has a portion on the surface of which a plating 5 made of a metal having a lower electrical resistivity than the material of the heating wire 4 is formed, and the portion on which the plating 5 is applied becomes a non-heating wire. Yes. The portion where the plating 5 is applied has a lower electrical resistivity than the portion where the plating 5 is not applied, so that the generation of Joule heat is suppressed and becomes a non-heat generation line, and this portion becomes a non-heat generation portion. In addition, the portion where the plating 5 is not formed normally generates heat and becomes a heat generating portion.

  Terminal sleeves 7 are provided at both ends of the metal sheath tube 3, the inorganic insulating material powder 6, and the metal sheath tube 3, and the terminal sleeve 7 includes insulation coatings 13 and 15 of lead wires 80 and 81 for energization. The structure in which the exposed conductors 14 and 16 are connected is the same as that of the microheater 11 having the conventional non-heat generating portion shown in FIG. In addition, the structure in the terminal sleeve 7 made the heating wire shown with the code | symbol 22 in FIG. 1 of the patent document 1 and the conductor shown with the code | symbol 13 by the same applicant as this patent application one each. Structure.

  In the microheater 1 having the non-heat generating portion, since the butt welding of the heat generating wire and the non-heat generating wire is not performed as in the conventional case, there is no dent of the non-heat generating wire caused by the butt welding, and the disconnection due to the dent occurs. do not do. Moreover, since there is no alloy part of a heating wire and a non-heating wire, there is no intermediate heating part, and there is no wasteful power consumption there.

  Regarding the material used, the material of the heating wire 4 in this embodiment is nichrome, and the material of the plating 5 is copper. As the material of the heating wire 4, nichrome having a high electrical resistivity and a large amount of heat generation has been conventionally used. Also in this embodiment, the heating wire 4 is made of nichrome, so that the heat generation amount of the heating portion is conventionally increased. It is equivalent to the micro heater. Further, the amount of heat generated in the non-heat generating portion is efficiently suppressed by using copper having a low electrical resistivity as the material of the plating 5.

  As other materials of the present embodiment, the metal sheath tube 3 is SUS316, and the inorganic insulating material powder 6 is magnesia. Of course, the material of the heating wire 4, the plating 5, the metal sheath tube 3, and the inorganic insulating material powder 6 is limited to these as long as the electric resistivity of the material of the plating 5 satisfies the condition lower than that of the material of the heating wire 4. The material may be changed depending on use conditions such as temperature.

  Regarding the cross-sectional shape, the outer diameter of the metal sheath tube 3 of this embodiment is 3.2 mm, the inner diameter is 2.56 mm, the outer diameter of the heating wire 4 is 0.77 mm, and the thickness of the plating 5 is 0.16 mm. The outer diameter of the heating wire is 1.09 mm. The inner diameter of the metal sheath tube 3 and the outer diameter of the heating wire 4 are the microheater 10 having the outer diameter of the conventional metal sheath tube 3 shown in FIG. 4 of 3.2 mm and the conventional metal sheath shown in FIG. The microheater 11 having a non-heat generating portion with an outer diameter of the tube 3 of 3.2 mm is set to be approximately the same as the standard inner diameter of the metal sheath tube 3, the standard outer diameter of the heating wire 4 and the non-heating wire 17. Yes.

  The amount of heat generated per unit length is proportional to the resistance value per unit length. Resistance of a non-heating wire in which copper plating 5 is made 0.16 mm thick on the surface of a heating wire 4 made of nichrome and having an outer diameter of 0.77 mm, that is, about 20% of the outer diameter of the heating wire 4 The value can be obtained as the resistance of a circuit in which the resistance of the nichrome wire and the resistance of the copper plating are connected in parallel, and the electrical resistivity of copper is about 1.6% of that of nichrome, Using the resistance value divided by the cross-sectional area, the resistance value per unit length of the non-heating wire is about 1.6% of the resistance value of the heating wire 4, Is equivalent to the resistance value per unit length of a conventional non-heating wire made of copper having an outer diameter of 0.77 mm. Therefore, the heat generation amount per unit length of the non-heating portion relative to the heat generation amount per unit length of the heat generation wire 4 of this embodiment is equivalent to about 1.6% in the case of the conventional copper non-heat generation wire. .

  If the thickness of the plating 5 is increased, the amount of heat generated by the unit length of the non-heating line, which is the portion where the plating 5 is made, is further reduced. If the thickness of the plating 5 is reduced, the unit length of the non-heating line is reduced. The calorific value of increases. In this embodiment, if the thickness of the plating 5 is 0.03 mm, that is, about 3.5% of the outer diameter of the heating wire 4 is about 3.5%, the amount of heat generated per unit length of the non-heating wire is the heating wire. Of about 10%.

  In the present embodiment, as in the prior art, in the production of a portion called a micro heater cable in which the inorganic sheath powder 6 is interposed in the metal sheath tube 3 and the heating wire 4 and the portion plated with the heating wire 4 are accommodated, As shown in FIG. 5, a product thicker than the finished diameter is first made, and the diameter is reduced to one-half to one-third by die drawing or swaging to finish a micro heater cable having an outer diameter of 3.2 mm. In this embodiment, when the diameter reduction ratio is 1/2, the outer diameter of the metal sheath tube 3 before the diameter reduction is 6.4 mm, the outer diameter of the heating wire 4 is about 1.5 mm, and the thickness of the copper plating 5 In the case of one third, the outer diameter of the metal sheath tube 3 before the diameter reduction is 9.6 mm, the outer diameter of the heating wire 4 is about 2.3 mm, and the copper plating 5 The thickness is about 0.47 mm.

  FIG. 3 is a cross-sectional view showing the boundary between the heat generating wire and the non-heat generating wire in the first embodiment of the present invention. FIG. 3 (a) is a cross section before diameter reduction at the time of manufacturing the micro heater cable, and FIG. FIG. 3C is an enlarged view of the boundary portion between the heat generation wire 4 after the diameter reduction and the non-heat generation line on which the copper plating 5 is made, surrounded by the chain line in FIG. 3B. As shown in FIG. 3 (a), the portion where the copper plating 5 is made and the portion where only the heating wire 4 where the plating 5 is not made are clearly separated because there is no conventional alloy portion. 3 (b), the range of the portion corresponding to the intermediate heat generating portion in FIG. 6 where the copper plating 5 is gradually thinned is extremely short as shown in FIG. 3 (c). It is equivalent to the absence of a heat generating part.

(Second Embodiment)
FIG. 2 is a cross-sectional view showing a second embodiment of a microheater having a non-heat generating portion according to the present invention, FIG. 2 (a) is a longitudinal cross-sectional view, and FIGS. 2 (b) and 2 (c) are respectively diagrams. It is CC cross section of 2 (a), and DD cross section. However, the terminal sleeve 7 and the insulating coatings 13 and 15 of the lead wires 80 and 81 in FIG. 2A are drawn in outline, and FIG. 2B and FIG. 2C are obtained from FIG. It is drawn at a large scale. Also, the reference numerals in the figure denote the same components as those in the conventional microheater shown in FIGS. 4 to 7, as in FIGS. 4 to 7.

  In the microheater 2 having a non-heat generating portion of the second embodiment, an inorganic insulating material powder 6 is interposed in a metal sheath tube 3, and a heating wire 4 made of metal and generating Joule heat when energized is accommodated. The heating wire 4 has a portion with a plating 5 made of a metal having a lower electrical resistivity than the material of the heating wire 4 on the surface, and the portion with the plating 5 becomes a non-heating wire. This is the same as in the first embodiment. The portion where the plating 5 is applied has a lower electrical resistivity than the portion where the plating 5 is not applied, so that the generation of Joule heat is suppressed and becomes a non-heat generation line, and this portion becomes a non-heat generation portion. In addition, as in the first embodiment, the portion that is not plated 5 generates normal heat and becomes a heat generating portion.

  A terminal sleeve 7 is provided at the end of the metal sheath tube 3, the inorganic insulating material powder 6, and the metal sheath tube 3 other than the non-heat generating wire, and the terminal sleeve 7 has lead wires 80 and 81 for energization. The structure in which the conductors 14 and 16 exposed from the insulating coatings 13 and 15 are connected is the same as the conventional microheater 21 having a non-heat generating portion shown in FIG. The structure in the terminal sleeve 7 is the structure shown in FIG.

  The materials of the heating wire 4, the plating 5, the metal sheath 3 and the inorganic insulating material powder 6 are the same as those in the first embodiment. As long as the electric resistivity of the material of the plating 5 satisfies the condition lower than that of the material of the heating wire 4, the material is not limited to these, and the material may be changed depending on the use conditions as in the first embodiment. .

  Regarding the cross-sectional dimensions, the outer diameter of the metal sheath tube 3 of the present embodiment is 3.2 mm, the inner diameter is 2.56 mm, the outer diameter of the heating wire 4 is 0.31 mm, and the thickness of the plating 5 is 0.07 mm. The outer diameter of the non-heating wire is 0.45 mm. The inner diameter of the metal sheath tube 3 and the outer diameter of the heating wire 4 are the microheater 20 having the outer diameter of the conventional metal sheath tube 3 shown in FIG. 5 of 3.2 mm and the conventional metal sheath shown in FIG. The microheater 21 having a non-heat generating portion with an outer diameter of the tube 3 of 3.2 mm is set to be approximately the same as the standard inner diameter of the metal sheath tube 3 and the standard outer diameter of the heating wire 4 and the non-heating wire 17. Yes.

  When the resistance value per unit length of the non-heating wire is obtained, the second embodiment is about 1.6% of the resistance value of the heating wire 4 as in the first embodiment, which is a conventional outer diameter of 0.31 mm. It is equivalent to the resistance value per unit length of the copper non-heating wire. Therefore, also in this embodiment, the heat generation amount per unit length of the non-heat generating portion relative to the heat generation amount per unit length of the heat generation wire 4 is equivalent to about 1.6% in the case of the conventional copper non-heat generation wire. .

  If the thickness of the plating 5 is increased, the amount of heat generated by the unit length of the non-heating line, which is the portion where the plating 5 is made, is further reduced. If the thickness of the plating 5 is reduced, the unit length of the non-heating line is reduced. The amount of generated heat increases as in the first embodiment. In this second embodiment, if the thickness of the plating 5 is 0.01 mm, that is, about 3.5% of the outer diameter of the heating wire 4 is about 3.5%, the heat generation amount per unit length of the non-heating wire is It can be suppressed to about 10% of the heating wire.

  Also in this embodiment, as in the first embodiment and the prior art, in the manufacture of the micro heater cable, a thicker one than the finished diameter is first made, and then the diameter is reduced to one-half to one-third by dicing or swaging. The diameter is reduced to a micro heater cable having an outer diameter of 3.2 mm. In this embodiment, when the diameter reduction ratio is ½, the outer diameter of the heating wire 4 before the diameter reduction is 6.4 mm, and the thickness of the copper plating 5 is about 0.13 mm. In this case, the outer diameter of the heating wire 4 before diameter reduction is 9.6 mm, and the thickness of the copper plating 5 is about 0.19 mm.

  Since there is no alloy part as in the prior art, the heating wire 4 and the non-heating wire are clearly separated in the microheater cable before the diameter reduction. Even if the diameter is reduced, there is no intermediate heating part. The form is the same as that of the first embodiment.

  As described above, the finished diameter of the microheater cable in the two embodiments, that is, the outer diameter of the metal sheath tube 3 is 3.2 mm, but the mainstream of the microheater cable conventionally used in the industry is as described above. 1.6 mm to 6.4 mm, and the microheater cable of the microheater having the non-heat generating portion of the present invention may have the same outer diameter as before, the diameter of the heating wire 4 according to the outer diameter, plating The thickness of 5 can be changed. As described above, the thickness of the copper plating 5 is not limited within the range of the outer diameter of the metal sheath tube 3.

  The total length of the microheater cable and the position and length of the heat generating part are determined by the use conditions such as the distance between the terminal sleeve and the heating object, the size of the heating object, and the predetermined restrictions are Absent.

1 Micro heater with non-heat generating part (first embodiment)
2 Micro heater with non-heat generating part (second embodiment)
3 Metal sheath tube 4 Heating wire 5 Plating 6 Inorganic insulating powder 7 Terminal sleeve 80, 81 Lead wire 13, 15 Lead wire insulation coating 14, 16 Lead wire conductor

Claims (4)

In a microheater in which a heating wire made of a metal that generates Joule heat by energization in a metal sheath tube is housed, and an inorganic insulating material powder is filled between the metal sheath tube and the heating wire,
A part of the heating wire is plated with a metal having a lower electrical resistivity than the material of the heating wire on the entire surface in the circumferential direction, and the amount of heat generated by the plating is less than that of the heating wire not plated. A microheater having a non-heat generating portion , wherein the portion where the plated heating wire exists is a non-heat generating portion. The material of the heating wire is nichrome,
2. The microheater with a non-heat generating portion according to claim 1, wherein the metal material plating the surface of the heating wire is copper.   3. The microheater having a non-heat generating portion according to claim 2, wherein the thickness of the metal plating the surface of the heating wire is 3.5% or more of the outer diameter of the heating wire. 4. The microheater with a non-heat generating part according to claim 3, wherein the thickness of the metal plating the surface of the heating wire is 20% or more of the outer diameter of the heating wire.

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