WO2015087937A1 - Tubular heater - Google Patents

Tubular heater Download PDF

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Publication number
WO2015087937A1
WO2015087937A1 PCT/JP2014/082759 JP2014082759W WO2015087937A1 WO 2015087937 A1 WO2015087937 A1 WO 2015087937A1 JP 2014082759 W JP2014082759 W JP 2014082759W WO 2015087937 A1 WO2015087937 A1 WO 2015087937A1
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WO
WIPO (PCT)
Prior art keywords
tubular heater
insulating base
flow path
ceramic
bent
Prior art date
Application number
PCT/JP2014/082759
Other languages
French (fr)
Japanese (ja)
Inventor
洋介 赤木
Original Assignee
京セラ株式会社
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Publication date
Application filed by 京セラ株式会社 filed Critical 京セラ株式会社
Priority to JP2015552492A priority Critical patent/JP5960931B2/en
Publication of WO2015087937A1 publication Critical patent/WO2015087937A1/en

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/40—Heating elements having the shape of rods or tubes
    • H05B3/42—Heating elements having the shape of rods or tubes non-flexible
    • H05B3/46—Heating elements having the shape of rods or tubes non-flexible heating conductor mounted on insulating base
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/10—Heater elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12—Heater elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H2250/00—Electrical heat generating means
    • F24H2250/02—Resistances
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/013—Heaters using resistive films or coatings
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/017—Manufacturing methods or apparatus for heaters

Definitions

  • the present invention relates to a tubular heater used for a liquid heating heater or the like.
  • Patent Document 1 As a heater used for a liquid heating heater or the like, for example, a tubular heater described in Japanese Patent Application Laid-Open No. 2004-185929 (hereinafter referred to as Patent Document 1) is known.
  • the tubular heater described in Patent Document 1 includes a tubular insulating base serving as a liquid flow path whose internal space is a fluid, and a heating resistor provided inside the insulating base. The liquid flowing through the flow path can be heated by causing a current to flow through the heating resistor to generate heat.
  • the present invention has been made in view of such problems, and an object thereof is to provide a tubular heater capable of improving the heating efficiency of a fluid flowing in an internal space.
  • a tubular heater includes a tubular ceramic body in which an inner space serves as a fluid flow path, an insulating base including a ceramic layer provided on an outer periphery of the ceramic body, the ceramic body, and the ceramic layer.
  • a heat generating resistor provided so as to surround the flow path, and the flow path is bent in an arc shape in the longitudinal direction together with the insulating base, and the insulating base is bent in an arc shape on the outer peripheral side. This region has a non-formed portion where the heating resistor is not provided.
  • FIG. 2 is a cross-sectional view of the tubular heater shown in FIG. 1 cut along the line AA ′. It is a schematic diagram which shows the pattern of the heating resistor of the tubular heater shown in FIG. It is sectional drawing which shows the modification of the tubular heater of this invention. It is sectional drawing which shows the modification of the tubular heater of this invention. It is sectional drawing which shows the modification of the tubular heater of this invention. It is a fragmentary sectional view which shows the non-formation part vicinity of the tubular heater of this invention.
  • FIG. 1 and 2 are sectional views showing a tubular heater 100 according to an embodiment of the present invention.
  • the tubular heater 100 includes an insulating substrate 1 and a heating resistor 2.
  • the tubular heater 100 can be used, for example, as a liquid heating heater that uses a liquid (such as water) as a fluid to be heated.
  • the insulating substrate 1 is a tubular member whose inner space serves as a fluid flow path 10.
  • the insulating base 1 includes a tubular ceramic body 13 whose inner space serves as a fluid flow path 10 and a ceramic layer 14 provided on the outer periphery of the ceramic body 13.
  • the insulating substrate 1 is a cylindrical member having a longitudinal direction.
  • the entire insulating base 1 is bent in an arc shape in the longitudinal direction. Therefore, in the insulating base 1, the inner peripheral surface serving as the wall surface of the flow path 10 is also bent in an arc shape. Since the inner peripheral surface serving as the wall surface of the flow path 10 is bent in an arc shape, a vortex can be generated in the fluid when the fluid hits the inner peripheral surface of the flow path 10. As a result, the fluid flowing through the flow path 10 can be turbulent.
  • the ceramic body 13 and the ceramic layer 14 are made of insulating ceramics such as oxide ceramics, nitride ceramics, or carbide ceramics.
  • the ceramic body 13 and the ceramic layer 14 are made of ceramics such as alumina ceramics, silicon nitride ceramics, aluminum nitride ceramics, or silicon carbide ceramics.
  • alumina ceramics are preferably used from the viewpoint of oxidation resistance.
  • the ceramic body 13 and the ceramic layer 14 are made of the same ceramic, but are not limited thereto. Specifically, the ceramic body 13 and the ceramic layer 14 may be made of different ceramics.
  • the dimensions of the insulating substrate 1 can be set as follows, for example. Specifically, for example, the total length in the longitudinal direction can be set to about 40 to 150 mm, the outer diameter can be set to about 4 to 30 mm, and the inner diameter can be set to about 1 to 28 mm. In addition, when the total length in the longitudinal direction is about 60 mm, the fluid flowing through the flow path 10 that is the internal space can be made turbulent by arcing so that the radius of curvature is about 200 to 1000 mm. it can. In order to make the fluid turbulent, for example, water is used as the fluid, and the total length of the tubular heater may be set to 40 mm or more and the curvature radius may be set to 1000 mm or less.
  • the heating resistor 2 is a resistor for generating heat and generates heat when a current flows. As shown in FIG. 2, the heating resistor 2 is embedded inside the insulating base 1 so as to surround the flow path 10. More specifically, the heating resistor 2 is provided between the ceramic body 13 and the ceramic layer 14 so as to surround the flow path 10. Further, as shown in FIG. 1, the heating resistor 2 is provided in a linear shape extending in the longitudinal direction. FIG. 3 shows the ceramic layer 14 and the heating resistor 2 before firing. The ceramic layer 14 is formed in a sheet shape, and a conductor pattern to be the heating resistor 2 is printed on the surface. The tubular heater 100 can be manufactured by winding the ceramic layer 14 together with the heating resistor 2 around the ceramic body 13 before firing, followed by firing.
  • the vertical direction in FIG. 3 corresponds to the circumferential direction of the tubular heater 100
  • the horizontal direction in FIG. 3 corresponds to the longitudinal direction of the tubular heater 100.
  • the length of the ceramic layer 14 in the vertical direction in FIG. 3 matches the circumferential length of the ceramic body 13 or slightly shorter than the circumferential length of the ceramic body 13. Therefore, when the ceramic layer 14 is wound around the ceramic body 13, the ceramic layer 14 is wound around the ceramic body 13 so that the ceramic layers 14 do not overlap each other.
  • the heating resistor 2 includes a plurality of folded portions and straight portions.
  • the heating resistor 2 is provided in a wide range of the insulating substrate 1 by having a plurality of folded portions.
  • the heating resistor 2 is provided on the entire surface except for a part of the ceramic body 13 in the circumferential direction (non-forming portion 20).
  • a region sandwiched by broken lines on the surface of the ceramic body 13 is the non-formed portion 20.
  • the non-forming portion 20 means a region where the heating resistor 2 is not provided anywhere on the surface of the ceramic body 13 in the longitudinal direction of the tubular heater 100.
  • the surface of the ceramic body 13 when viewed in a cross section perpendicular to the longitudinal direction, it means a region where the heating resistor 2 is not provided at any position. Specifically, regions where the heating resistor 2 is not provided anywhere in the longitudinal direction are indicated by hatching on the upper and lower sides of the ceramic layer 14 before firing in FIG.
  • regions where the heating resistor 2 is not provided anywhere in the longitudinal direction are indicated by hatching on the upper and lower sides of the ceramic layer 14 before firing in FIG.
  • the heating resistor 2 is made of a conductor whose main component is a high melting point metal such as tungsten, molybdenum or rhenium.
  • the dimensions of the heating resistor 2 can be set, for example, to a width of about 0.3 to 2 mm, a thickness of about 0.01 to 0.1 mm, and a total length of about 500 to 5000 mm. These dimensions are appropriately set depending on the heating temperature of the heating resistor 2, the voltage applied to the heating resistor 2, and the like.
  • An electrode 3 is provided on the surface of one end side of the insulating substrate 1.
  • the electrodes 3 are members for electrically connecting an external power source and the heating resistor 2 and are respectively provided at two locations on one end side of the insulating base 1.
  • the electrode 3 is electrically connected to the heating resistor 2.
  • the electrode 3 is made of a metal material such as tungsten or molybdenum.
  • the tubular heater 100 can generate a vortex in the fluid when the fluid collides with the inner surface of the fluid channel 10 because the fluid channel 10 is bent in an arc shape in the longitudinal direction. As a result, the flow of fluid flowing through the flow path 10 can be turbulent. Therefore, heat transfer from the insulating substrate 1 to the fluid (for example, liquid) can be improved.
  • the fluid for example, liquid
  • the non-formed portion 20 where the heating resistor 2 is not provided is located in the outer peripheral side region of the insulating substrate 1 that is bent in an arc shape.
  • region of the outer peripheral side bent in the arc shape here can be defined as follows. Specifically, half of the insulating base 1 bent in an arc shape on the side where the outer peripheral surface swells can be regarded as the outer peripheral region. On the contrary, the half of the side where the outer peripheral surface is recessed can be regarded as the region on the inner peripheral side. More specifically, as shown in FIG. 1, the side that is convex across the flow path 10 can be regarded as the outer peripheral side, and the side that is concave across the flow path 10 is the inner peripheral side. Can be considered as
  • the ceramic body 13 is bonded to the ceramic layer 14 in a state where the ceramic body 14 before firing is wound together with the heating resistor 2 around the ceramic body 13 before firing.
  • a method of bending the heating resistor 2 in an arc shape can be given. At this time, if the heating resistor 2 is provided over the entire circumference of the ceramic body 13 without providing the non-forming portion 20, the following problems may occur.
  • the heating resistor 2 is pulled by the ceramic body 13 and the ceramic layer 14 on the outer peripheral side bent in an arc shape. become. If the ceramic body 13, the ceramic layer 14, and the heating resistor 2 are fired in this state, high residual stress may be generated in the heating resistor 2. If the tubular heater 100 is repeatedly used in such a state that a high residual stress remains in the heating resistor 2 as described above, the ceramic body 13 and the ceramic layer 14 may be cracked due to thermal expansion and contraction of the heating resistor 2. There is.
  • the ceramic body 13 and the ceramic layer 14 and the heating resistor 2 are bent in an arc.
  • the heating resistor 2 does not exist in the outer peripheral region bent in an arc shape. Therefore, it is possible to reduce the high residual stress remaining after firing the ceramic body 13, the ceramic layer 14, and the heating resistor 2. As a result, when the tubular heater 100 is used, the possibility of cracks occurring in the ceramic body 13 and the ceramic layer 14 can be reduced.
  • the proportion of voids existing between the ceramic body 13 and the ceramic layer 14 is smaller in the non-formed portion 20 than in other regions.
  • the heat generated from the heating resistor 2 can be easily directed toward the surface of the insulating substrate 1.
  • adhesion between the ceramic body 13 and the ceramic layer 14 is applied. The amount of liquid should be increased.
  • the void ratio can be confirmed by the following method, for example.
  • the tubular heater 100 is cut along a cross section perpendicular to the longitudinal direction to obtain a cross section as shown in FIG. And in the cut surface, the sum total of the length of the area
  • the void ratio is regarded as 10%.
  • the length of the area where voids are present is calculated with respect to the entire length of the area of the surface of the ceramic body 13 other than the non-formed portion 20 where the heating resistor 2 is not provided in the cut surface.
  • the void ratio is regarded as 50%. As described above, the void ratio can be confirmed.
  • the calculation may be performed as follows.
  • the total length (x) of the non-formed portion 20 is a length along the circumferential direction of the ceramic body 13 in the region d.
  • the total length (y) of the regions where the voids 15 are present is the total length of the regions a, b and c along the circumferential direction of the ceramic body 13. That is, the void ratio is 100 ⁇ y / x (%).
  • the ceramic body 13 and the ceramic layer 14 have a larger coefficient of thermal expansion than the heating resistor 2.
  • the tubular heater 10 when the tubular heater 10 is thermally expanded, the periphery of the non-forming portion 20 is greatly expanded, so that the insulating base body 1 bent in an arc shape is thermally expanded while maintaining the arc bent shape. Can do. Therefore, it is possible to make the fluid flowing through the flow path 10 stable and turbulent easily under a heat cycle.
  • tungsten can be used as the heating resistor 2
  • alumina ceramics can be used as the ceramic body 13 and the ceramic layer 14.
  • the thermal expansion coefficient of the heating resistor 2 can be set to 4 ⁇ 10 ⁇ 6 / K
  • the thermal expansion coefficients of the ceramic body 13 and the ceramic layer 14 can be set to 7 ⁇ 10 ⁇ 6 / K.
  • alumina ceramic green sheet (ceramic layer 14) prepared with Al 2 O 3 as a main component so that SiO 2 , CaO, MgO, and ZrO 2 are 10% by mass or less in total is produced.
  • a predetermined pattern to be the heating resistor 2 is formed on the surface of the alumina ceramic green sheet.
  • a screen printing method or the like can be used as a method of forming the heating resistor 2.
  • a pattern to be the heating resistor 2 as shown in FIG. 3 is formed on the surface of the alumina ceramic green sheet.
  • the pattern to be the heating resistor 2 includes a plurality of straight portions extending along the longitudinal direction of the tubular heater 100 and a plurality of folded portions connecting these straight portions.
  • the hatched area in FIG. 3 is an area corresponding to the non-formed portion 20 where the heating resistor 2 is not provided in the insulating substrate 1.
  • the alumina ceramic green sheet is provided with a through-hole conductor for electrically connecting the internal heating resistor 2 and the surface electrode 3.
  • a through-hole conductor for example, a conductive paste whose main component is a refractory metal such as tungsten, molybdenum or rhenium can be used.
  • a cylindrical alumina ceramic molded body (ceramic body 13) is molded. Then, the alumina ceramic green sheet on which the pattern is formed is wound around the cylindrical alumina ceramic molded body so that the surface on which the pattern is formed contacts the alumina ceramic molded body. At this time, by applying an adhesion liquid in which alumina ceramics having the same composition is dispersed to the alumina ceramic green sheet, the alumina ceramic green sheet and the alumina ceramic molded body are adhered to each other, thereby integrating the alumina material. A molded body can be obtained. Then, the alumina-integrated molded body is bent in an arc shape so that the non-forming portion 20 is positioned on the outer peripheral side that is bent in the arc shape in the longitudinal direction.
  • the arc-shaped insulating substrate 1 having the heating resistor 2 inside can be obtained by firing the alumina-integrated molded body thus obtained in a nitrogen atmosphere at 1500 to 1600 ° C.
  • an electrode 3 is formed on the surface of the insulating substrate 1.
  • a pad electrode 3 can be used as the electrode 3.
  • the tubular heater 100 can be obtained as described above.
  • the thickness of the insulating base 1 is constant, but is not limited thereto.
  • the tubular heater 101 of the first modification has a portion where the thickness of the insulating base 1 in the outer peripheral region bent in an arc is thinner than the thickness of the insulating base 1 in the inner peripheral region. You may do it.
  • a part of the insulating substrate 1 having the non-formed portion 20 is thinned by providing the groove 21 having a square cross section on the outer peripheral surface of the insulating substrate 1.
  • the heat capacity in the portion having the non-formed portion 20 can be reduced.
  • the bottom of the groove 21 is made of the ceramic body 14.
  • the center of the non-formed part 20 when viewed in a cross section perpendicular to the longitudinal direction, on the surface of the ceramic body 13, the center of the non-formed part 20 (the adjacent heating resistors 22, 23 on the surface of the ceramic body 13).
  • the groove 21 exists in a portion where the distance from the head is equal. Thereby, the heat radiation in the non-formation part 20 can be performed in a wide range. Therefore, it is possible to further reduce the partial heat generation in the non-formed part 20.
  • the thickness of the outer peripheral side bent in an arc shape in the insulating substrate 1 is about 1.5 mm
  • the thickness of the outer peripheral side bent in an arc shape can be set to about 0.3 to 1 mm, for example.
  • the region where the thickness is reduced can be set between about 5 to 30% of the entire circumference.
  • the thickness is reduced by providing the rectangular groove 21 on the outer peripheral surface of the insulating base 1, but the present invention is not limited to this.
  • a wedge-shaped or arc-shaped groove may be provided.
  • the thickness is reduced by providing a groove on the outer peripheral surface of the insulating base 1, but as in Modification 2 described below, the thickness is reduced by providing a groove on the inner peripheral surface. May be.
  • the groove 21 can be formed, for example, by making the length of the ceramic layer 14 to be wound shorter than the circumferential length of the ceramic body 13 when the ceramic layer 14 is wound around the ceramic body 13.
  • the diameter of the inner surface of the insulating base 1 is constant, but the present invention is not limited to this.
  • the insulating base 1 has a groove portion 11 along the longitudinal direction on the inner surface. Since the tubular heater 102 has the groove 11 on the inner surface, the surface area of the inner surface can be increased. Thereby, the fluid which flows through the flow path 10 can be heated more efficiently. Furthermore, since the groove part 11 is provided along the longitudinal direction, the fluid can flow smoothly compared to the case where the groove part 11 is provided along the direction intersecting the longitudinal direction.
  • the vibration which arises when a fluid is flowed through the tubular heater 100 can be reduced.
  • the heating resistor 2 and an external power source are electrically connected, the influence of vibration on the connection structure can be reduced.
  • the long-term reliability of the tubular heater 100 can be improved.
  • the groove 11 is located on the outer peripheral side bent in an arc shape. Since the flow of the fluid tends to be faster on the outer peripheral side of the flow path 10 that is bent in an arc shape, the stagnation of the fluid in the groove 11 can be reduced. As a result, the fluid flowing through the flow path 10 can be heated more efficiently.
  • the radius of curvature on the outer peripheral side bent in an arc shape is constant, but is not limited thereto.
  • the electrode 3 is provided on the surface on one end side along the longitudinal direction.
  • the channel 10 has a smaller radius of curvature on one end side than on the other end side.
  • the curvature radius of the flow path 10 here can be calculated
  • the radius of curvature other than one end side of the insulating substrate 1 is set to about 200 to 1000 mm, and the radius of curvature on one end side is set to about 100 to 500 mm. Can do. Further, it is preferable that the portion having a small radius of curvature on one end side of the insulating base 1 is provided in a region of about 5 to 20 mm from one end face of the insulating base 1, for example.
  • Tubular heater 1 Insulating substrate 10: Channel 11: Groove part 2: Heating resistor 20: Non-forming part 21: Groove 3: Electrode

Abstract

This tubular heater comprises: an insulating base element constituted by a tubular ceramic element having an inner space that constitutes a flow path for a fluid, and a ceramic layer provided on the outer periphery of the ceramic element; and a heat-generating resistor element provided between the ceramic element and the ceramic layer so as to surround the flow path. The flow path is bent in an arc shape along the longitudinal direction together with the insulating base element. The insulating base element includes a non-formation part, which is where the heat-generating resistor element is not provided, in a region on the outer periphery side where the base element is bent in an arc shape.

Description

管状ヒータTubular heater
　本発明は、液体加熱用ヒータ等に用いられる管状ヒータに関するものである。 The present invention relates to a tubular heater used for a liquid heating heater or the like.
　液体加熱用ヒータ等に用いられるヒータとして、例えば、特開２００４－１８５９２９号公報（以下、特許文献１という）に記載された管状ヒータが知られている。特許文献１に記載の管状ヒータは、内部の空間が流体である液体の流路となる管状の絶縁基体とこの絶縁基体の内部に設けられた発熱抵抗体とを備えている。この発熱抵抗体に電流を流して発熱させることによって、流路を流れる液体を加熱することができる。 As a heater used for a liquid heating heater or the like, for example, a tubular heater described in Japanese Patent Application Laid-Open No. 2004-185929 (hereinafter referred to as Patent Document 1) is known. The tubular heater described in Patent Document 1 includes a tubular insulating base serving as a liquid flow path whose internal space is a fluid, and a heating resistor provided inside the insulating base. The liquid flowing through the flow path can be heated by causing a current to flow through the heating resistor to generate heat.
　しかしながら、特許文献１に記載された管状ヒータにおいては、絶縁基体が円筒であることから、内部を流れる液体の流れが、流れの方向に延びる同心円状の筒を重ねたような層流となっていた。そのため、流路を流れる液体のうち、円筒の絶縁基体の内周面付近を流れる液体は絶縁基体から良好に加熱されるものの、流路の中央を流れる液体を良好に加熱することが困難であった。その結果、管状ヒータの加熱効率を向上させることが困難であった。 However, in the tubular heater described in Patent Document 1, since the insulating base is a cylinder, the flow of liquid flowing inside is a laminar flow in which concentric cylinders extending in the flow direction are stacked. It was. For this reason, of the liquid flowing in the flow path, the liquid flowing in the vicinity of the inner peripheral surface of the cylindrical insulating base is heated well from the insulating base, but it is difficult to heat the liquid flowing in the center of the flow path well. It was. As a result, it has been difficult to improve the heating efficiency of the tubular heater.
　本発明はかかる問題点に鑑みてなされたものであり、その目的は、内部の空間を流れる流体の加熱効率を向上させることができる管状ヒータを提供することにある。 The present invention has been made in view of such problems, and an object thereof is to provide a tubular heater capable of improving the heating efficiency of a fluid flowing in an internal space.
　本発明の一態様の管状ヒータは、内側の空間が流体の流路となる管状のセラミック体および該セラミック体の外周に設けられたセラミック層からなる絶縁基体と、前記セラミック体と前記セラミック層との間に前記流路を囲むように設けられた発熱抵抗体とを備え、前記流路は、前記絶縁基体とともに長手方向に弧状に曲がっており、前記絶縁基体は、弧状に曲がっている外周側の領域に、前記発熱抵抗体が設けられていない非形成部を有する。 A tubular heater according to an aspect of the present invention includes a tubular ceramic body in which an inner space serves as a fluid flow path, an insulating base including a ceramic layer provided on an outer periphery of the ceramic body, the ceramic body, and the ceramic layer. A heat generating resistor provided so as to surround the flow path, and the flow path is bent in an arc shape in the longitudinal direction together with the insulating base, and the insulating base is bent in an arc shape on the outer peripheral side. This region has a non-formed portion where the heating resistor is not provided.
本発明の管状ヒータの一実施形態の断面図である。It is sectional drawing of one Embodiment of the tubular heater of this invention. 図１に示す管状ヒータをＡ－Ａ´線で切った断面図である。FIG. 2 is a cross-sectional view of the tubular heater shown in FIG. 1 cut along the line AA ′. 図１に示す管状ヒータの発熱抵抗体のパターンを示す模式図である。It is a schematic diagram which shows the pattern of the heating resistor of the tubular heater shown in FIG. 本発明の管状ヒータの変形例を示す断面図である。It is sectional drawing which shows the modification of the tubular heater of this invention. 本発明の管状ヒータの変形例を示す断面図である。It is sectional drawing which shows the modification of the tubular heater of this invention. 本発明の管状ヒータの変形例を示す断面図である。It is sectional drawing which shows the modification of the tubular heater of this invention. 本発明の管状ヒータの非形成部近傍を示す部分断面図である。It is a fragmentary sectional view which shows the non-formation part vicinity of the tubular heater of this invention.
　以下、本発明の一実施形態に係る管状ヒータ１００について、図面を参照しながら説明する。図１、２は本発明の一実施形態に係る管状ヒータ１００を示す断面図である。図１に示すように、管状ヒータ１００は、絶縁基体１と発熱抵抗体２とを備えている。管状ヒータ１００は、例えば、流体である液体（水等）を被加熱物とする液体加熱用ヒータとして用いることができる。 Hereinafter, a tubular heater 100 according to an embodiment of the present invention will be described with reference to the drawings. 1 and 2 are sectional views showing a tubular heater 100 according to an embodiment of the present invention. As shown in FIG. 1, the tubular heater 100 includes an insulating substrate 1 and a heating resistor 2. The tubular heater 100 can be used, for example, as a liquid heating heater that uses a liquid (such as water) as a fluid to be heated.
　絶縁基体１は、内側の空間が流体の流路１０となる管状の部材である。絶縁基体１は、内側の空間が流体の流路１０となる管状のセラミック体１３およびセラミック体１３の外周に設けられたセラミック層１４からなる。絶縁基体１は、長手方向を有する円筒状の部材である。絶縁基体１は、全体が、長手方向に弧状に曲がっている。そのため、絶縁基体１は流路１０の壁面となる内周面も弧状に曲がっている。流路１０の壁面となる内周面が弧状に曲がっていることによって、流体が流路１０の内周面にぶつかった際に流体に渦を発生させることができる。その結果、流路１０を流れる流体を乱流にすることができる。 The insulating substrate 1 is a tubular member whose inner space serves as a fluid flow path 10. The insulating base 1 includes a tubular ceramic body 13 whose inner space serves as a fluid flow path 10 and a ceramic layer 14 provided on the outer periphery of the ceramic body 13. The insulating substrate 1 is a cylindrical member having a longitudinal direction. The entire insulating base 1 is bent in an arc shape in the longitudinal direction. Therefore, in the insulating base 1, the inner peripheral surface serving as the wall surface of the flow path 10 is also bent in an arc shape. Since the inner peripheral surface serving as the wall surface of the flow path 10 is bent in an arc shape, a vortex can be generated in the fluid when the fluid hits the inner peripheral surface of the flow path 10. As a result, the fluid flowing through the flow path 10 can be turbulent.
　セラミック体１３およびセラミック層１４は、例えば、酸化物セラミックス、窒化物セラミックスまたは炭化物セラミックス等の絶縁性のセラミックスから成る。具体的には、セラミック体１３およびセラミック層１４は、アルミナ質セラミックス、窒化珪素質セラミックス、窒化アルミニウム質セラミックスまたは炭化珪素質セラミックス等のセラミックスから成る。中でも、耐酸化性の観点から、アルミナ質セラミックスを用いることが好ましい。本実施形態においては、セラミック体１３とセラミック層１４とが同じセラミックスから成るがこれに限られない。具体的には、セラミック体１３とセラミック層１４とが異なるセラミックスから成ってもよい。 The ceramic body 13 and the ceramic layer 14 are made of insulating ceramics such as oxide ceramics, nitride ceramics, or carbide ceramics. Specifically, the ceramic body 13 and the ceramic layer 14 are made of ceramics such as alumina ceramics, silicon nitride ceramics, aluminum nitride ceramics, or silicon carbide ceramics. Among these, alumina ceramics are preferably used from the viewpoint of oxidation resistance. In the present embodiment, the ceramic body 13 and the ceramic layer 14 are made of the same ceramic, but are not limited thereto. Specifically, the ceramic body 13 and the ceramic layer 14 may be made of different ceramics.
　絶縁基体１の寸法は、例えば、以下の通り設定することができる。具体的には、例えば、長手方向の全長を４０～１５０ｍｍ程度に、外径を４～３０ｍｍ程度に、内径を１～２８ｍｍ程度に設定することができる。また、長手方向の全長が６０ｍｍ程度の場合には、曲率半径が２００～１０００ｍｍ程度になるように弧状にしておくことによって、内部の空間である流路１０を流れる流体を乱流にすることができる。流体を乱流にするためには、例えば、流体として水を用いるとともに、管状ヒータの全長を４０ｍｍ以上、曲率半径を１０００ｍｍ以下にすればよい。 The dimensions of the insulating substrate 1 can be set as follows, for example. Specifically, for example, the total length in the longitudinal direction can be set to about 40 to 150 mm, the outer diameter can be set to about 4 to 30 mm, and the inner diameter can be set to about 1 to 28 mm. In addition, when the total length in the longitudinal direction is about 60 mm, the fluid flowing through the flow path 10 that is the internal space can be made turbulent by arcing so that the radius of curvature is about 200 to 1000 mm. it can. In order to make the fluid turbulent, for example, water is used as the fluid, and the total length of the tubular heater may be set to 40 mm or more and the curvature radius may be set to 1000 mm or less.
　発熱抵抗体２は、発熱するための抵抗体であって、電流が流れることによって発熱する。図２に示すように、発熱抵抗体２は、絶縁基体１の内部に流路１０を囲むように埋設されている。より詳しくは、発熱抵抗体２は、セラミック体１３とセラミック層１４との間に流路１０を囲むように設けられている。また、図１に示すように、発熱抵抗体２は、長手方向に伸びる線状に設けられている。図３は、焼成前のセラミック層１４および発熱抵抗体２を示している。セラミック層１４はシート状に形成されるとともに、表面に発熱抵抗体２となる導体パターンが印刷されている。そして、焼成前のセラミック体１３に発熱抵抗体２ごとセラミック層１４を巻きつけた後に焼成することによって、管状ヒータ１００を製造することができる。図３における上下方向が管状ヒータ１００の周方向に対応しており、図３における左右方向が管状ヒータ１００の長手方向に対応している。また、図３におけるセラミック層１４の上下方向の長さは、セラミック体１３の周方向の長さと一致しているか、または、セラミック体１３の周方向の長さよりもわずかに短い。したがって、セラミック層１４をセラミック体１３に巻きつける場合には、セラミック層１４同士が重ならないようにセラミック体１３に巻きつけることになる。 The heating resistor 2 is a resistor for generating heat and generates heat when a current flows. As shown in FIG. 2, the heating resistor 2 is embedded inside the insulating base 1 so as to surround the flow path 10. More specifically, the heating resistor 2 is provided between the ceramic body 13 and the ceramic layer 14 so as to surround the flow path 10. Further, as shown in FIG. 1, the heating resistor 2 is provided in a linear shape extending in the longitudinal direction. FIG. 3 shows the ceramic layer 14 and the heating resistor 2 before firing. The ceramic layer 14 is formed in a sheet shape, and a conductor pattern to be the heating resistor 2 is printed on the surface. The tubular heater 100 can be manufactured by winding the ceramic layer 14 together with the heating resistor 2 around the ceramic body 13 before firing, followed by firing. The vertical direction in FIG. 3 corresponds to the circumferential direction of the tubular heater 100, and the horizontal direction in FIG. 3 corresponds to the longitudinal direction of the tubular heater 100. Further, the length of the ceramic layer 14 in the vertical direction in FIG. 3 matches the circumferential length of the ceramic body 13 or slightly shorter than the circumferential length of the ceramic body 13. Therefore, when the ceramic layer 14 is wound around the ceramic body 13, the ceramic layer 14 is wound around the ceramic body 13 so that the ceramic layers 14 do not overlap each other.
　図３に示すように、発熱抵抗体２は、複数の折り返し部と直線部とを備えている。発熱抵抗体２は、複数の折り返し部を有することによって、絶縁基体１の広範囲に設けられている。そして、発熱抵抗体２は、セラミック体１３の周方向の一部（非形成部２０）を除いて全体に設けられている。なお、図２においては、セラミック体１３の表面のうち破線で挟まれた領域が非形成部２０である。なお、ここでいう、非形成部２０とは、セラミック体１３の表面のうち、管状ヒータ１００の長手方向のどこにも発熱抵抗体２が設けられていない領域を意味している。言い換えると、セラミック体１３の表面を長手方向に対して垂直な断面で見たときに、どの位置で断面を見ても発熱抵抗体２が設けられていない領域を意味している。具体的には、図３における焼成前のセラミック層１４の上側と下側には発熱抵抗体２が長手方向のどこにも設けられていない領域がハッチングによって示されている。このセラミック層１４をセラミック体１３に、隙間なく且つ重複無く巻きつけた場合には、セラミック体１３の表面のうちハッチングによって示された領域と接触する領域が非形成部２０となる。 As shown in FIG. 3, the heating resistor 2 includes a plurality of folded portions and straight portions. The heating resistor 2 is provided in a wide range of the insulating substrate 1 by having a plurality of folded portions. The heating resistor 2 is provided on the entire surface except for a part of the ceramic body 13 in the circumferential direction (non-forming portion 20). In FIG. 2, a region sandwiched by broken lines on the surface of the ceramic body 13 is the non-formed portion 20. Here, the non-forming portion 20 means a region where the heating resistor 2 is not provided anywhere on the surface of the ceramic body 13 in the longitudinal direction of the tubular heater 100. In other words, when the surface of the ceramic body 13 is viewed in a cross section perpendicular to the longitudinal direction, it means a region where the heating resistor 2 is not provided at any position. Specifically, regions where the heating resistor 2 is not provided anywhere in the longitudinal direction are indicated by hatching on the upper and lower sides of the ceramic layer 14 before firing in FIG. When the ceramic layer 14 is wound around the ceramic body 13 without gaps and without overlapping, a region in contact with a region indicated by hatching in the surface of the ceramic body 13 becomes the non-forming portion 20.
　発熱抵抗体２は、例えば、タングステン、モリブデンまたはレニウム等の高融点の金属を主成分とした導電体から成る。発熱抵抗体２の寸法は、例えば、幅を０．３～２ｍｍ程度に、厚みを０．０１～０．１ｍｍ程度に、全長を５００～５０００ｍｍ程度に設定することができる。これらの寸法は、発熱抵抗体２の発熱温度および発熱抵抗体２に加える電圧等によって適宜設定される。 The heating resistor 2 is made of a conductor whose main component is a high melting point metal such as tungsten, molybdenum or rhenium. The dimensions of the heating resistor 2 can be set, for example, to a width of about 0.3 to 2 mm, a thickness of about 0.01 to 0.1 mm, and a total length of about 500 to 5000 mm. These dimensions are appropriately set depending on the heating temperature of the heating resistor 2, the voltage applied to the heating resistor 2, and the like.
　絶縁基体１の一端側の表面には、電極３が設けられている。電極３は、外部の電源と発熱抵抗体２とを電気的に接続するための部材であって、絶縁基体１の一端側の２か所にそれぞれ設けられている。電極３は、発熱抵抗体２に電気的に接続されている。電極３は、例えば、タングステンまたはモリブデン等の金属材料から成る。 An electrode 3 is provided on the surface of one end side of the insulating substrate 1. The electrodes 3 are members for electrically connecting an external power source and the heating resistor 2 and are respectively provided at two locations on one end side of the insulating base 1. The electrode 3 is electrically connected to the heating resistor 2. The electrode 3 is made of a metal material such as tungsten or molybdenum.
　本実施形態の管状ヒータ１００は、流路１０が長手方向に弧状に曲がっていることによって、流体が流路１０の内面にぶつかった際に流体に渦を発生させることができる。その結果、流路１０を流れる流体の流れを乱流にすることができる。そのため、絶縁基体１から流体（例えば液体）への熱伝達を向上させることができる。 The tubular heater 100 according to the present embodiment can generate a vortex in the fluid when the fluid collides with the inner surface of the fluid channel 10 because the fluid channel 10 is bent in an arc shape in the longitudinal direction. As a result, the flow of fluid flowing through the flow path 10 can be turbulent. Therefore, heat transfer from the insulating substrate 1 to the fluid (for example, liquid) can be improved.
　さらに、図１に示すように、発熱抵抗体２が設けられていない非形成部２０は、絶縁基体１のうち弧状に曲がっている外周側の領域に位置している。このように、絶縁基体１のうち弧状に曲がっている外周側の領域に非形成部２０を位置させることによって、絶縁基体１にクラックが入る可能性を低減できる。なお、ここでいう弧状に曲がっている外周側の領域とは以下のように定義することができる。具体的には、弧状に曲がった絶縁基体１のうち外周面が膨らんでいる側の半分を外周側の領域として見なすことができる。反対に、外周面が凹んでいる側の半分を内周側の領域として見なすことができる。より具体的には、図１に示すように、流路１０を挟んで凸になっている側を外周側として見なすことができ、流路１０を挟んで凹になっている側を内周側として見なすことができる。 Further, as shown in FIG. 1, the non-formed portion 20 where the heating resistor 2 is not provided is located in the outer peripheral side region of the insulating substrate 1 that is bent in an arc shape. As described above, by positioning the non-forming portion 20 in the outer peripheral region bent in an arc shape in the insulating base 1, the possibility of cracks in the insulating base 1 can be reduced. In addition, the area | region of the outer peripheral side bent in the arc shape here can be defined as follows. Specifically, half of the insulating base 1 bent in an arc shape on the side where the outer peripheral surface swells can be regarded as the outer peripheral region. On the contrary, the half of the side where the outer peripheral surface is recessed can be regarded as the region on the inner peripheral side. More specifically, as shown in FIG. 1, the side that is convex across the flow path 10 can be regarded as the outer peripheral side, and the side that is concave across the flow path 10 is the inner peripheral side. Can be considered as
　理由を以下に説明する。流路１０を絶縁基体１とともに長手方向に弧状に曲げる方法として、焼成前のセラミック体１３に焼成前のセラミック層１４を発熱抵抗体２ごと巻きつけた状態で、セラミック体１３をセラミック層１４および発熱抵抗体２ごと弧状に曲げる方法が挙げられる。このとき、非形成部２０を設けずに、セラミック体１３の全周にわたって発熱抵抗体２を設けていると以下の問題が生じるおそれがある。 The reason will be explained below. As a method of bending the flow path 10 together with the insulating substrate 1 in an arc shape in the longitudinal direction, the ceramic body 13 is bonded to the ceramic layer 14 in a state where the ceramic body 14 before firing is wound together with the heating resistor 2 around the ceramic body 13 before firing. A method of bending the heating resistor 2 in an arc shape can be given. At this time, if the heating resistor 2 is provided over the entire circumference of the ceramic body 13 without providing the non-forming portion 20, the following problems may occur.
　具体的には、セラミック体１３をセラミック層１４および発熱抵抗体２ごと弧状に曲げた状態では、弧状に曲がっている外周側において発熱抵抗体２がセラミック体１３およびセラミック層１４に引っ張られた状態になる。この状態で、セラミック体１３、セラミック層１４および発熱抵抗体２を焼成すると、発熱抵抗体２に高い残留応力が生じる可能性がある。そして、このように発熱抵抗体２に高い残留応力が残った状態で管状ヒータ１００を繰り返し使用すると、発熱抵抗体２の熱膨張および熱収縮によってセラミック体１３およびセラミック層１４にクラックが生じる可能性がある。 Specifically, in a state where the ceramic body 13 and the ceramic layer 14 and the heating resistor 2 are bent in an arc shape, the heating resistor 2 is pulled by the ceramic body 13 and the ceramic layer 14 on the outer peripheral side bent in an arc shape. become. If the ceramic body 13, the ceramic layer 14, and the heating resistor 2 are fired in this state, high residual stress may be generated in the heating resistor 2. If the tubular heater 100 is repeatedly used in such a state that a high residual stress remains in the heating resistor 2 as described above, the ceramic body 13 and the ceramic layer 14 may be cracked due to thermal expansion and contraction of the heating resistor 2. There is.
　これに対して、絶縁基体１のうち弧状に曲げた際に外周側に位置する領域を非形成部２０としている場合には、セラミック体１３をセラミック層１４および発熱抵抗体２ごと弧状に曲げた場合に、弧状に曲がっている外周側の領域に発熱抵抗体２が存在しないことになる。そのため、セラミック体１３、セラミック層１４および発熱抵抗体２の焼成後に、高い残留応力が残ることを低減できる。その結果、管状ヒータ１００を使用した際にセラミック体１３およびセラミック層１４にクラックが生じる可能性を低減できる。 On the other hand, in the case where the region located on the outer peripheral side when the insulating substrate 1 is bent in an arc is used as the non-forming portion 20, the ceramic body 13 and the ceramic layer 14 and the heating resistor 2 are bent in an arc. In this case, the heating resistor 2 does not exist in the outer peripheral region bent in an arc shape. Therefore, it is possible to reduce the high residual stress remaining after firing the ceramic body 13, the ceramic layer 14, and the heating resistor 2. As a result, when the tubular heater 100 is used, the possibility of cracks occurring in the ceramic body 13 and the ceramic layer 14 can be reduced.
　さらに、セラミック体１３とセラミック層１４との間に存在するボイドの割合が、非形成部２０において他の領域よりも少ないことが好ましい。非形成部２０においてボイドを少なくしておくことによって、非形成部２０の近傍に熱が籠ることを低減できる。また、非形成部２０以外の領域においてボイドを多くしておくことによって、発熱抵抗体２から生じた熱を絶縁基体１の表面に向かいやすくすることができる。なお、セラミック体１３とセラミック層１４との間に存在するボイドを非形成部２０において少なくするためには、例えば、非形成部２０において、セラミック体１３とセラミック層１４との間に塗布する密着液の量を増やしておけばよい。 Furthermore, it is preferable that the proportion of voids existing between the ceramic body 13 and the ceramic layer 14 is smaller in the non-formed portion 20 than in other regions. By reducing the number of voids in the non-formed part 20, it is possible to reduce the heat generated near the non-formed part 20. In addition, by increasing the number of voids in the region other than the non-formed portion 20, the heat generated from the heating resistor 2 can be easily directed toward the surface of the insulating substrate 1. In order to reduce the voids existing between the ceramic body 13 and the ceramic layer 14 in the non-forming portion 20, for example, in the non-forming portion 20, adhesion between the ceramic body 13 and the ceramic layer 14 is applied. The amount of liquid should be increased.
　また、ボイドの割合は、例えば、以下の方法で確認できる。まず、管状ヒータ１００を長手方向に垂直な断面で切断して、図２に示すような断面を得る。そして、切断面において、セラミック体１３の表面のうち非形成部２０の全長に対してボイドが存在している領域の長さの合計を算出する。非形成部２０の長さが１０ｍｍのときにボイドが存在している領域の長さの合計が１ｍｍの場合には、ボイドの割合は１０％として見なす。また、切断面において、セラミック体１３の表面のうち非形成部２０以外の領域であって発熱抵抗体２が設けられていない領域の全長に対してボイドが存在している領域の長さを算出する。非形成部２０以外の部分であって、発熱抵抗体２が存在しない領域の長さの合計が５０ｍｍのときに、発熱抵抗体２が存在しない領域におけるボイドが存在している領域の長さの合計が２５ｍｍの場合には、ボイドの割合を５０％として見なす。以上のようにして、ボイドの割合を確認できる。 Also, the void ratio can be confirmed by the following method, for example. First, the tubular heater 100 is cut along a cross section perpendicular to the longitudinal direction to obtain a cross section as shown in FIG. And in the cut surface, the sum total of the length of the area | region where a void exists with respect to the full length of the non-formation part 20 among the surfaces of the ceramic body 13 is calculated. When the total length of the regions where voids are present when the length of the non-formed portion 20 is 10 mm, the void ratio is regarded as 10%. Moreover, the length of the area where voids are present is calculated with respect to the entire length of the area of the surface of the ceramic body 13 other than the non-formed portion 20 where the heating resistor 2 is not provided in the cut surface. To do. When the total length of the regions other than the non-formed portion 20 where the heating resistor 2 does not exist is 50 mm, the length of the region where the void exists in the region where the heating resistor 2 does not exist When the total is 25 mm, the void ratio is regarded as 50%. As described above, the void ratio can be confirmed.
　例えば、図７に示すような管状ヒータ１００において、非形成部２０の全長に対してボイド１５が存在している領域の長さを求める場合には、以下のように計算を行なえばよい。まず、非形成部２０の全長（ｘ）は、領域ｄのセラミック体１３の周方向に沿った長さとなる。また、ボイド１５が存在している領域の長さの合計（ｙ）は、領域ａ、領域ｂおよび領域ｃのセラミック体１３の周方向に沿った長さの合計となる。つまり、ボイドの割合は、１００×ｙ／ｘ（％）となる。 For example, in the tubular heater 100 as shown in FIG. 7, when the length of the region where the void 15 is present with respect to the entire length of the non-formed portion 20 is obtained, the calculation may be performed as follows. First, the total length (x) of the non-formed portion 20 is a length along the circumferential direction of the ceramic body 13 in the region d. Further, the total length (y) of the regions where the voids 15 are present is the total length of the regions a, b and c along the circumferential direction of the ceramic body 13. That is, the void ratio is 100 × y / x (%).
　さらに、発熱抵抗体２よりもセラミック体１３およびセラミック層１４が熱膨張率が大きいことが好ましい。これにより、管状ヒータ１０が熱膨張するときには、非形成部２０の周辺が大きく熱膨張することになるので、弧状に曲がっている絶縁基体１が弧状に曲がった形状を維持したまま熱膨張することができる。そのため、ヒートサイクル下において、流路１０を流れる流体を安定して乱流にしやすくすることができる。具体的な材料としては、例えば、発熱抵抗体２としてタングステン用いるとともに、セラミック体１３およびセラミック層１４としてアルミナ質セラミックスを用いることができる。この場合には、発熱抵抗体２の熱膨張率を４×１０－６／Ｋに、セラミック体１３およびセラミック層１４の熱膨張率を７×１０－６／Ｋに設定できる。 Furthermore, it is preferable that the ceramic body 13 and the ceramic layer 14 have a larger coefficient of thermal expansion than the heating resistor 2. Thereby, when the tubular heater 10 is thermally expanded, the periphery of the non-forming portion 20 is greatly expanded, so that the insulating base body 1 bent in an arc shape is thermally expanded while maintaining the arc bent shape. Can do. Therefore, it is possible to make the fluid flowing through the flow path 10 stable and turbulent easily under a heat cycle. As a specific material, for example, tungsten can be used as the heating resistor 2, and alumina ceramics can be used as the ceramic body 13 and the ceramic layer 14. In this case, the thermal expansion coefficient of the heating resistor 2 can be set to 4 × 10 −6 / K, and the thermal expansion coefficients of the ceramic body 13 and the ceramic layer 14 can be set to 7 × 10 −6 / K.
　＜製造方法＞
　次に、本実施形態の管状ヒータ１００の製造方法の一例について説明する。まず、Ａｌ２Ｏ３を主成分として、ＳｉＯ２、ＣａＯ、ＭｇＯおよびＺｒＯ２が合計で１０質量％以下になるように調製したアルミナ質セラミックグリーンシート（セラミック層１４）を作製する。 <Manufacturing method>
Next, an example of the manufacturing method of the tubular heater 100 of this embodiment is demonstrated. First, an alumina ceramic green sheet (ceramic layer 14) prepared with Al 2 O 3 as a main component so that SiO 2 , CaO, MgO, and ZrO 2 are 10% by mass or less in total is produced.
　そして、このアルミナ質セラミックグリーンシートの表面に、発熱抵抗体２となる所定のパターンを形成する。発熱抵抗体２の形成方法としては、スクリーン印刷法等を用いることができる。アルミナ質セラミックグリーンシートの表面に図３に示したような発熱抵抗体２となるパターンを形成する。 Then, a predetermined pattern to be the heating resistor 2 is formed on the surface of the alumina ceramic green sheet. As a method of forming the heating resistor 2, a screen printing method or the like can be used. A pattern to be the heating resistor 2 as shown in FIG. 3 is formed on the surface of the alumina ceramic green sheet.
　発熱抵抗体２となるパターンは、管状ヒータ１００の長手方向に沿って伸びた複数の直線部と、これらの直線部を繋ぐ複数の折り返し部とを備えている。そして、図３においてハッチングで示した領域が、絶縁基体１のうち発熱抵抗体２が設けられていない非形成部２０に対応した領域となる。 The pattern to be the heating resistor 2 includes a plurality of straight portions extending along the longitudinal direction of the tubular heater 100 and a plurality of folded portions connecting these straight portions. The hatched area in FIG. 3 is an area corresponding to the non-formed portion 20 where the heating resistor 2 is not provided in the insulating substrate 1.
　また、図３には示していないが、アルミナ質セラミックグリーンシートには、内部の発熱抵抗体２と表面の電極３とを電気的に接続するためにスルーホール導体を設ける。スルーホール導体には、例えば、タングステン、モリブデンまたはレニウム等の高融点金属を主成分とする導電性ペーストを用いることができる。 Although not shown in FIG. 3, the alumina ceramic green sheet is provided with a through-hole conductor for electrically connecting the internal heating resistor 2 and the surface electrode 3. For the through-hole conductor, for example, a conductive paste whose main component is a refractory metal such as tungsten, molybdenum or rhenium can be used.
　また、アルミナ質セラミックグリーンシートとは別に、円筒状のアルミナ質セラミック成型体（セラミック体１３）を成型する。そして、この円筒状のアルミナ質セラミック成型体に、パターンを形成したアルミナ質セラミックグリーンシートを、パターンを形成した面がアルミナ質セラミック成型体に接触するように巻き付ける。このとき、同一の組成のアルミナ質セラミックスを分散させた密着液をアルミナ質セラミックグリーンシートに塗布しておいて、アルミナ質セラミックグリーンシートとアルミナ質セラミック成型体とを密着させることで、アルミナ質一体成型体を得ることができる。そして、このアルミナ質一体成型体を、非形成部２０が長手方向の弧状に曲っている外周側に位置するように、弧状に曲げる。 In addition to the alumina ceramic green sheet, a cylindrical alumina ceramic molded body (ceramic body 13) is molded. Then, the alumina ceramic green sheet on which the pattern is formed is wound around the cylindrical alumina ceramic molded body so that the surface on which the pattern is formed contacts the alumina ceramic molded body. At this time, by applying an adhesion liquid in which alumina ceramics having the same composition is dispersed to the alumina ceramic green sheet, the alumina ceramic green sheet and the alumina ceramic molded body are adhered to each other, thereby integrating the alumina material. A molded body can be obtained. Then, the alumina-integrated molded body is bent in an arc shape so that the non-forming portion 20 is positioned on the outer peripheral side that is bent in the arc shape in the longitudinal direction.
　こうして得られた、アルミナ質一体成型体を１５００～１６００℃の窒素雰囲気中で焼成することによって、内部に発熱抵抗体２を有する弧状の絶縁基体１を得ることができる。 The arc-shaped insulating substrate 1 having the heating resistor 2 inside can be obtained by firing the alumina-integrated molded body thus obtained in a nitrogen atmosphere at 1500 to 1600 ° C.
　この後、絶縁基体１の表面に電極３を形成する。電極３としては、例えば、パッド電極３を用いることができる。以上のようにして、管状ヒータ１００を得ることができる。 Thereafter, an electrode 3 is formed on the surface of the insulating substrate 1. As the electrode 3, for example, a pad electrode 3 can be used. The tubular heater 100 can be obtained as described above.
　＜変形例１＞
　上述の実施形態の管状ヒータ１００においては、絶縁基体１の厚みが一定であったが、これに限られない。図４に示すように、変形例１の管状ヒータ１０１は、弧状に曲がっている外周側の領域における絶縁基体１の厚みが、内周側の領域における絶縁基体１の厚みよりも薄い部位を有していてもよい。本変形例においては、絶縁基体１の外周面に断面が四角形状である溝２１が設けられることによって、絶縁基体１のうち非形成部２０を有する部分の一部が薄くなっている。このように、非形成部２０を有する部分における絶縁基体１の厚みを薄くしておくことによって、非形成部２０を有する部分における熱容量を小さくできる。その結果、発熱抵抗体２から発せられた熱が非形成部２０に伝わった後に、この非形成部２０で籠ってしまう可能性を低減できる。 <Modification 1>
In the tubular heater 100 of the above-described embodiment, the thickness of the insulating base 1 is constant, but is not limited thereto. As shown in FIG. 4, the tubular heater 101 of the first modification has a portion where the thickness of the insulating base 1 in the outer peripheral region bent in an arc is thinner than the thickness of the insulating base 1 in the inner peripheral region. You may do it. In the present modification, a part of the insulating substrate 1 having the non-formed portion 20 is thinned by providing the groove 21 having a square cross section on the outer peripheral surface of the insulating substrate 1. Thus, by reducing the thickness of the insulating substrate 1 in the portion having the non-formed portion 20, the heat capacity in the portion having the non-formed portion 20 can be reduced. As a result, it is possible to reduce the possibility that the heat generated from the heating resistor 2 is transferred to the non-formed part 20 and then burned by the non-formed part 20.
　特に、溝２１の底部がセラミック体１４から成ることが好ましい。このように非形成部２０の一部が露出することによって、非形成部２０に熱が籠ることをさらに低減できる。特に、図４に示すように、長手方向に垂直な断面で見たときに、セラミック体１３の表面において、非形成部２０の中心（セラミック体１３の表面において、隣り合う発熱抵抗体２２、２３からの距離が等しい部分）に溝２１が存在していることが好ましい。これにより、非形成部２０における放熱を広範囲に行なうことができる。そのため、非形成部２０において部分的に熱が籠ることをさらに低減できる。 In particular, it is preferable that the bottom of the groove 21 is made of the ceramic body 14. Thus, by exposing a part of the non-formed part 20, it is possible to further reduce the heat generated in the non-formed part 20. In particular, as shown in FIG. 4, when viewed in a cross section perpendicular to the longitudinal direction, on the surface of the ceramic body 13, the center of the non-formed part 20 (the adjacent heating resistors 22, 23 on the surface of the ceramic body 13). It is preferable that the groove 21 exists in a portion where the distance from the head is equal. Thereby, the heat radiation in the non-formation part 20 can be performed in a wide range. Therefore, it is possible to further reduce the partial heat generation in the non-formed part 20.
　絶縁基体１のうち弧状に曲がっている内周側の厚みが１．５ｍｍ程度の場合には、弧状に曲がっている外周側の厚みを例えば０．３～１ｍｍ程度に設定することができる。また、厚みを薄くする領域は、全周の５～３０％程度の間で設定することができる。 When the thickness of the inner peripheral side bent in an arc shape in the insulating substrate 1 is about 1.5 mm, the thickness of the outer peripheral side bent in an arc shape can be set to about 0.3 to 1 mm, for example. The region where the thickness is reduced can be set between about 5 to 30% of the entire circumference.
　また、本変形例においては、絶縁基体１の外周面に四角形状の溝２１を設けることによって、厚みを薄くしたが、これに限られない。例えば、楔状または弧状の溝を設けてもよい。また、本変形例においては、絶縁基体１の外周面に溝を設けることによって厚みを薄くしたが、以下に説明する変形例２のように、内周面に溝を設けることによって厚みを薄くしてもよい。 In this modification, the thickness is reduced by providing the rectangular groove 21 on the outer peripheral surface of the insulating base 1, but the present invention is not limited to this. For example, a wedge-shaped or arc-shaped groove may be provided. Further, in this modification, the thickness is reduced by providing a groove on the outer peripheral surface of the insulating base 1, but as in Modification 2 described below, the thickness is reduced by providing a groove on the inner peripheral surface. May be.
　溝２１は、例えば、セラミック体１３にセラミック層１４を巻きつける際に、セラミック体１３の周方向の長さよりも巻きつけるセラミック層１４の長さを短くすることによって形成できる。 The groove 21 can be formed, for example, by making the length of the ceramic layer 14 to be wound shorter than the circumferential length of the ceramic body 13 when the ceramic layer 14 is wound around the ceramic body 13.
　＜変形例２＞
　上述の実施形態の管状ヒータ１００においては、絶縁基体１の内面の径が一定であったが、これに限られない。図５に示すように、変形例２の管状ヒータ１０２は、絶縁基体１が内面に長手方向に沿って溝部１１を有している。管状ヒータ１０２は、内面に溝部１１を有していることによって、内面の表面積を大きくすることができる。これにより、流路１０を流れる流体をより効率よく加熱することができる。さらに、溝部１１が長手方向に沿って設けられていることにより、溝部１１が長手方向に交差する方向に沿って設けられている場合と比較して、流体をスムーズに流すことができる。これにより、管状ヒータ１００に流体を流したときに生じる振動を低減することができる。その結果、発熱抵抗体２と外部の電源とを電気的に接続した場合に、この接続構造に対する振動による影響を低減することができる。その結果、管状ヒータ１００の長期信頼性を向上させることができる。 <Modification 2>
In the tubular heater 100 of the above-described embodiment, the diameter of the inner surface of the insulating base 1 is constant, but the present invention is not limited to this. As shown in FIG. 5, in the tubular heater 102 of the modified example 2, the insulating base 1 has a groove portion 11 along the longitudinal direction on the inner surface. Since the tubular heater 102 has the groove 11 on the inner surface, the surface area of the inner surface can be increased. Thereby, the fluid which flows through the flow path 10 can be heated more efficiently. Furthermore, since the groove part 11 is provided along the longitudinal direction, the fluid can flow smoothly compared to the case where the groove part 11 is provided along the direction intersecting the longitudinal direction. Thereby, the vibration which arises when a fluid is flowed through the tubular heater 100 can be reduced. As a result, when the heating resistor 2 and an external power source are electrically connected, the influence of vibration on the connection structure can be reduced. As a result, the long-term reliability of the tubular heater 100 can be improved.
　特に、溝部１１が弧状に曲がった外周側に位置していることが好ましい。流路１０のうち弧状に曲がった外周側は流体の流れが速くなる傾向にあるため、溝部１１で流体が停滞することを低減できる。その結果、流路１０を流れる流体をより効率よく加熱できる。 In particular, it is preferable that the groove 11 is located on the outer peripheral side bent in an arc shape. Since the flow of the fluid tends to be faster on the outer peripheral side of the flow path 10 that is bent in an arc shape, the stagnation of the fluid in the groove 11 can be reduced. As a result, the fluid flowing through the flow path 10 can be heated more efficiently.
　＜変形例３＞
　上述の実施形態の管状ヒータ１００においては、弧状に曲がった外周側の曲率半径が一定であったが、これに限られない。図６に示すように、変形例３の管状ヒータ１０３は電極３が長手方向に沿った一端側の表面に設けられている。そして、流路１０は、他端側に比べて一端側の曲率半径が小さい。これにより、流体を一端側から流したときに、絶縁基体１の内面のうち弧状の外周側の領域にぶつかり、流体の流れをすぐに乱流にすることができる。このように、流体の入口側の曲率半径を小さくすることによって、管状ヒータ１０３の加熱効率を向上させることができる。なお、ここでいう、流路１０の曲率半径は以下の方法で求めることができる。具体的には、例えば、管状ヒータ１０３を長手方向に平行な断面であって、弧状に曲がっていることによって凸になっている部分と凹になっている部分とを通る断面を見たときに、弧状に曲がっている外周側の領域における流路１０の内面の曲率半径を求めればよい。 <Modification 3>
In the tubular heater 100 of the above-described embodiment, the radius of curvature on the outer peripheral side bent in an arc shape is constant, but is not limited thereto. As shown in FIG. 6, in the tubular heater 103 of the third modification, the electrode 3 is provided on the surface on one end side along the longitudinal direction. The channel 10 has a smaller radius of curvature on one end side than on the other end side. Thereby, when a fluid is flowed from one end side, it hits the area | region of the arc-shaped outer peripheral side among the inner surfaces of the insulation base | substrate 1, and can make a fluid flow a turbulent flow immediately. Thus, the heating efficiency of the tubular heater 103 can be improved by reducing the curvature radius on the inlet side of the fluid. In addition, the curvature radius of the flow path 10 here can be calculated | required with the following method. Specifically, for example, when the cross section of the tubular heater 103 is parallel to the longitudinal direction and passes through a convex portion and a concave portion by bending in an arc shape, What is necessary is just to obtain | require the curvature radius of the inner surface of the flow path 10 in the area | region of the outer peripheral side curved in the arc shape.
　管状ヒータ１０３の長手方向の長さが６０ｍｍ程度の場合には、例えば、絶縁基体１の一端側以外の曲率半径を２００～１０００ｍｍ程度に、一端側の曲率半径を１００～５００ｍｍ程度に設定することができる。また、絶縁基体１の一端側の曲率半径が小さい部分は、例えば、絶縁基体１の一端面から５～２０ｍｍ程度の領域に設けることが好ましい。 When the length of the tubular heater 103 in the longitudinal direction is about 60 mm, for example, the radius of curvature other than one end side of the insulating substrate 1 is set to about 200 to 1000 mm, and the radius of curvature on one end side is set to about 100 to 500 mm. Can do. Further, it is preferable that the portion having a small radius of curvature on one end side of the insulating base 1 is provided in a region of about 5 to 20 mm from one end face of the insulating base 1, for example.
１００，１０１，１０２，１０３：管状ヒータ
１：絶縁基体
１０：流路
１１：溝部
２：発熱抵抗体
２０：非形成部
２１：溝
３：電極 100, 101, 102, 103: Tubular heater 1: Insulating substrate 10: Channel 11: Groove part 2: Heating resistor 20: Non-forming part 21: Groove 3: Electrode

Claims (8)

  1. 　内側の空間が流体の流路となる管状のセラミック体および該セラミック体の外周に設けられたセラミック層からなる絶縁基体と、前記セラミック体と前記セラミック層との間に前記流路を囲むように設けられた発熱抵抗体とを備え、前記流路は、前記絶縁基体とともに長手方向に弧状に曲がっており、前記絶縁基体は、弧状に曲がっている外周側の領域に、前記発熱抵抗体が設けられていない非形成部を有する管状ヒータ。 An inner space surrounds the flow path between the ceramic body and the ceramic layer, with a tubular ceramic body serving as a fluid flow path and an insulating base formed of a ceramic layer provided on the outer periphery of the ceramic body. A heat generating resistor provided, and the flow path is bent in an arc shape in the longitudinal direction together with the insulating base, and the heat generating resistor is provided in a region on an outer peripheral side of the insulating base bent in an arc shape. A tubular heater having a non-formed part.
  2. 　前記絶縁基体は、弧状に曲がっている外周側の領域における厚みが内周側の領域における厚みよりも薄い部位を有している請求項１に記載の管状ヒータ。 2. The tubular heater according to claim 1, wherein the insulating base has a portion where the thickness in the outer peripheral region bent in an arc is thinner than the thickness in the inner peripheral region.
  3. 　前記絶縁基体は、弧状に曲がっている外周側の領域の外周面に、溝が設けられている請求項２に記載の管状ヒータ。 3. The tubular heater according to claim 2, wherein the insulating base is provided with a groove on an outer peripheral surface of an outer peripheral region bent in an arc shape.
  4. 　前記溝の底部がセラミック体から成る請求項３に記載の管状ヒータ。 The tubular heater according to claim 3, wherein the bottom of the groove is made of a ceramic body.
  5. 　前記絶縁基体は、前記流路の内面に長手方向に沿って溝部を有する請求項１乃至請求項４のいずれかに記載の管状ヒータ。 The tubular heater according to any one of claims 1 to 4, wherein the insulating base has a groove along the longitudinal direction on the inner surface of the flow path.
  6. 　前記溝部が弧状に曲がっている外周側の領域に位置している請求項５に記載の管状ヒータ。 The tubular heater according to claim 5, wherein the groove is located in a region on the outer peripheral side that is bent in an arc shape.
  7. 　前記流路は、一端側の曲率半径が他端側の曲率半径に比べて小さい請求項１乃至請求項６のいずれかに記載の管状ヒータ。 The tubular heater according to any one of claims 1 to 6, wherein the flow path has a smaller radius of curvature on one end side than a radius of curvature on the other end side.
  8. 　前記絶縁基体の前記一端側の外周面に設けられており、前記発熱抵抗体に電気的に接続された電極をさらに備えた請求項７に記載の管状ヒータ。 The tubular heater according to claim 7, further comprising an electrode provided on an outer peripheral surface of the one end side of the insulating base and electrically connected to the heating resistor.
PCT/JP2014/082759 2013-12-10 2014-12-10 Tubular heater WO2015087937A1 (en)

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WO2018061439A1 (en) * 2016-09-27 2018-04-05 京セラ株式会社 Superheated steam generation device
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JP2019114507A (en) * 2017-12-26 2019-07-11 京セラ株式会社 heater
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WO2017130922A1 (en) * 2016-01-28 2017-08-03 京セラ株式会社 Superheated steam generating unit
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EP3439428A4 (en) * 2016-03-30 2019-11-13 NGK Spark Plug Co., Ltd. Ceramic heater
EP3484240A4 (en) * 2016-07-05 2020-03-04 NGK Spark Plug Co., Ltd. Ceramic heater
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EP3915410A4 (en) * 2019-01-26 2022-03-16 Shenzhen First Union Technology Co., Ltd. Cigarette heating assembly and electric heating smoking device

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