EP0650020B1 - Elément chauffant céramique et son procédé de fabrication - Google Patents

Elément chauffant céramique et son procédé de fabrication Download PDF

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Publication number
EP0650020B1
EP0650020B1 EP19940307544 EP94307544A EP0650020B1 EP 0650020 B1 EP0650020 B1 EP 0650020B1 EP 19940307544 EP19940307544 EP 19940307544 EP 94307544 A EP94307544 A EP 94307544A EP 0650020 B1 EP0650020 B1 EP 0650020B1
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EP
European Patent Office
Prior art keywords
enclosure
ceramics
coil
ceramic heater
ceramic
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EP19940307544
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German (de)
English (en)
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EP0650020A3 (fr
EP0650020A2 (fr
Inventor
Hideki Kita
Hideo Kawamura
Takene Hirai
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Isuzu Ceramics Research Institute Co Ltd
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Isuzu Ceramics Research Institute Co Ltd
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Priority claimed from JP05284204A external-priority patent/JP3075660B2/ja
Priority claimed from JP5284203A external-priority patent/JP3050266B2/ja
Application filed by Isuzu Ceramics Research Institute Co Ltd filed Critical Isuzu Ceramics Research Institute Co Ltd
Publication of EP0650020A2 publication Critical patent/EP0650020A2/fr
Publication of EP0650020A3 publication Critical patent/EP0650020A3/fr
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23Q—IGNITION; EXTINGUISHING-DEVICES
    • F23Q7/00—Incandescent ignition; Igniters using electrically-produced heat, e.g. lighters for cigarettes; Electrically-heated glowing plugs
    • F23Q7/001—Glowing plugs for internal-combustion engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23Q—IGNITION; EXTINGUISHING-DEVICES
    • F23Q7/00—Incandescent ignition; Igniters using electrically-produced heat, e.g. lighters for cigarettes; Electrically-heated glowing plugs
    • F23Q7/001—Glowing plugs for internal-combustion engines
    • F23Q2007/004—Manufacturing or assembling methods

Definitions

  • the present invention relates to a ceramic heater that forms a ceramic glow plug used with diesel engines and also to a method of manufacturing the ceramic heater.
  • a ceramic glow plug conventionally has its heater portion consisting of a high-melting point metal such as tungsten and an Si 3 N 4 formed integral during a hot-press process.
  • a conventional current self-control type glow plug is not satisfactory in terms of heat durability, strength against thermal shocks and high-temperature resistance when it is used in high-temperature combustion chambers in heat-insulated engines. Because the self-control type glow plug is made by connecting a heating coil made from a tungsten wire and a resistor coil made from a nickel wire, both with different resistance-temperature coefficients, there are drawbacks of complex structure, high cost and insufficient strength.
  • the metal coil such as tungsten wire is embedded in ceramics and sintered during the forming process, so that the sintering requires application of pressure.
  • a hot-press i.e., a single axis pressure sintering is usually performed.
  • the metal coil embedded in the ceramics is therefore limited in the shape and takes a two-dimensional structure, giving rise to a problem that a gap is formed between the wall surface of the ceramic enclosure and the metal coil, reducing the heat conductivity and the quick-heating capability of the ceramic heater.
  • a gap is formed in the boundary between the tungsten wire and the Si 3 N 4 , resulting in ingress of water or oxygen through the gap to cause corrosion.
  • a glass sealing may be employed but this increases the number of steps in the manufacture process, lowering the reliability.
  • the heater portion is formed of a sintered ceramics that consists of a heater coated with a ceramic coating layer applied by a vapor deposition method.
  • a heating resistor wire formed of a high melting point metal such as tungsten (W), molybdenum (Mo) and rhenium (Re) or their alloys is embedded in an Si 3 N 4 sintered body and an intermediate layer, which is made from the same metal elements as the major constituent elements of the resistor wire or non-oxidized ceramics such as nitrides, carbides, silicides or silicified carbide of these metals, is formed over the surface of the resistor wire.
  • a sheath type resistor having a greater positive resistance-temperature coefficient than the heater tungsten coil is used as a current control element and connected in series with the heater coil in the glow plug, with the heater coil embedded in a bar-shaped ceramics, to improve the heat conductivity and self-control the electricity supplied to the heating coil thereby improving the heating characteristics and preventing overheating of the heater portion.
  • a self-control type glow plug disclosed in Japanese Patent Publication No. 34052/1992 has a current control resistor connected in series with a heating body to control the heating body temperature when a current is being supplied and the temperature is rising.
  • the heating coil and the resistor coil are connected in series and embedded in a ceramic sintered material, thus forming an integral ceramic heater.
  • the heating coil is made from a tungsten-rhenium alloy wire which has a positive resistance-temperature coefficient of less than four times, and the resistor coil is made of a pure tungsten wire or a pure molybdenum wire.
  • a sheathed glow plug disclosed in Japanese Patent Publication No. 19404/1985 is a self-control type sheathed glow plug, in which a heating coil and a resistor coil are directly connected to each other between the inner bottom of a heat resisting, bottomed metal tube and a center electrode, with the winding pitch of the resistor coil made dense in an area close to a mounting fitting on the central electrode side and coarse in an area close to the heating body side.
  • a glow plug for diesel engine disclosed in the Japanese Patent Laid-Open No. 141424/1987 has a cylindrical ceramic heater mounted at the front end portion of a hollow holder.
  • the ceramic heater consists of a thin plate insulator made of insulating ceramics and a thin plate resistor made of conductive ceramics stacked over the side surfaces and one end portion of the thin plate insulator, these laminated thin plate insulator and resistor being bent widthwise to form a cylindrical body.
  • a protective pipe of conductive ceramics is fitted over the outer circumference of the rear end of the cylindrical body. The protective pipe and the cylindrical body are then sintered to be formed as an integral one-piece structure.
  • a primary aim of this invention is to solve the above-mentioned problems by providing a ceramic heater comprising the features of claim 1 and a method of manufacturing a ceramic heater according to claim 12.
  • the ceramic heater according to the invention can improve the heat conductivity, prevent ingress of water or oxygen from the boundary between the metal coil and the enclosure ceramics in the heater portion, reduce manufacturing cost and assure a stable strength and improved reliability.
  • the portion of the metal coil arranged in contact with the inner wall surface of the front end portion of the enclosure where the filler is disposed constitutes a heater coil
  • the second portion of the metal coil spaced from the inner wall surface of the enclosure where the low heat conductivity ceramics is disposed constitutes a current control coil.
  • the heat generated by the heater coil heats the enclosure and is dissipated outside.
  • the heat generated by the current control coil is insulated by the low heat conductivity ceramics, raising the temperature of the current control coil.
  • the temperature of the current control coil increases, its resistance also increases, limiting the current flowing through the current control coil or the whole metal coil. That is, an elevated temperature of the current control coil increases its resistance and reduces the current flowing through the metal coil, thus self-controlling the amount of heat dissipated from the enclosure to an optimum level.
  • the enclosure is formed of Si 3 N 4 and its end surfaces are hermetically closed with sealing films to seal the interior of the enclosure.
  • the sealing films are made from glass or the same kind of ceramics as that of the enclosure.
  • the metal coil is made from a tungsten wire, whose surface is coated with a ceramic film formed by the chemical vapor deposition (CVD) or with an organic silicon polymer-converted ceramic film.
  • CVD chemical vapor deposition
  • the porous ceramics is a non-contracting ceramics that is made by sintering the material containing Si and Ti for reaction.
  • the non-contracting ceramics contains Si 3 N 4 , TiN, TiO 2 , and TiON.
  • the low heat conductivity ceramics is made from ceramic whiskers and/or ceramic powder and contains Si 3 N 4 and metal nitrides or metal oxides.
  • the present invention also provides a method of manufacturing a ceramic heater including the steps according to claim 12.
  • a preferred embodiments of the present invention are developped in the ceramic heater manufacturing methods according to claims 13 to 16.
  • the enclosure is made of an Si 3 N 4 dense ceramics
  • TiN is generated from the reaction of Si and Ti during the baking process. Because TiN expands during baking, the porous ceramics generated from baking and containing TiN slightly expands, causing the sintered Si 3 N 4 to adhere to the enclosure Si 3 N 4 . Further, if baking is performed without applying pressure, the expansion of TiN prevents formation of any gap in the boundary between the enclosure and the filler. Hence, the metal coil, even if formed in a three-dimensional shape, can be maintained in good contact with the enclosure, improving the heat conduction efficiency and permitting a fast temperature rise at the heater portion.
  • an N2 gas in the enclosure is sealed in the enclosure during the baking process by closing the end surfaces of the enclosure with sealing films such as ceramics. Since an N 2 gas can be sealed in the enclosure during the baking process, the number of manufacturing steps can be reduced, lowering the cost. Moreover, the sealed N 2 gas improves corrosion resistance and durability of the metal coil, which is made, for example, of a tungsten wire.
  • the heater coil which forms the heater portion
  • the temperature of the whole enclosure rises uniformly.
  • This ceramic heater which is incorporated in a ceramic glow plug of current self-control type built into a diesel engine, consists of: a pipe-shaped enclosure 1 made from dense ceramic with open ends; fillers 2, 3 made from porous ceramics and filled inside the ends of the enclosure 1; a sealing film 4 attached to the ends of the enclosure 1 to seal the interior of the enclosure 1; a low heat conductivity ceramics 5 installed in the central portion of the enclosure 1 and sealing an N 2 gas; and a metal coil 10 installed inside the enclosure 1.
  • the fillers 2, 3 are filled in the enclosure 1 in such a way as to contact the inner wall surfaces 7, 14 of the enclosure 1.
  • the metal coil 10 is a resistor wire made from a high melting point metal such as tungsten and consists of a heater coil 6 and a current control coil 9.
  • the heater coil 6 is installed in the front end part of the enclosure 1 where the filler 2 is filled, in such a way that the heater coil contacts the inner wall surface 7 of the enclosure 1.
  • the current control coil 9 is installed in a part of the enclosure where the N 2 gas is sealed, in such a way that it is spaced from the inner wall surface 8 of the enclosure 1.
  • the metal coil 10 also has a connecting wire 11 that connects one end of the heater coil 6 and one end of the current control coil 9; a connecting wire 12 that connects to the other end of the heater coil 6, extends through the interior of the enclosure 1 and projects from the porous ceramics filler 3; and a connecting wire 13 that connects to the other end of the current control coil 9, extends through the interior of the enclosure 1 and protrudes from the porous ceramics filler 3.
  • the surface of the metal coil 10 is coated with a ceramic film.
  • the porous ceramics forming the fillers 2, 3 contains Si and Ti which, when baked, are transformed into Si 3 N 4 and TiN, respectively. TiN is further transformed into more stable materials TiO 2 and TiON through oxidation.
  • the sealing film 4 attached to the ends 15 of the enclosure 1 and to the end surface of the fillers 2, 3 are made from glass material such as polymer precursor or the same ceramics as that of the enclosure 1.
  • the enclosure 1 is formed of a dense Si 3 N 4 ceramics.
  • the low heat conductivity ceramics 5 is made of either SiC whisker, Si 3 N 4 whisker, Al 2 O 3 whisker, Al 2 O 3 -SiO 2 whisker, ceramic powder or Si 3 N 4 porous material.
  • the ceramics around the current control coil 9 be made from a material having as low a heat conductivity as air. Further, during the baking process, an N 2 gas is sealed in a part of the enclosure 1 where the low heat conductivity ceramics 5 is located in order to prevent oxidation of the metal coil 10.
  • One end of the enclosure 1 is secured to a hollow body that has an electrode mounted in a hollow portion thereof through an insulator such as insulating bushing.
  • the hollow body is made from a metal such as heat resistant alloy and has a thread for mounting to other component.
  • the end of the connecting wire 13 is connected to the electrode and the end of the connecting wire 12 is connected to the hollow body. Therefore, in this ceramic heater, electric current flows from the electrode to the connecting wire 13 to the current control coil 9 to the connecting wire 11 to the heater coil 6 to the connecting wire 12 to the hollow body.
  • This ceramic heater can be manufactured as follows. First, the enclosure 1 is made from a dense ceramics and the surface of the metal coil 10 of, say, tungsten wire is covered by the chemical vapor deposition (CVD) with ceramics, such as SiC, that has a thermal expansion coefficient almost equal to that of the metal coil 10. Next, the ceramics-coated metal coil 10 of tungsten wire is installed inside the enclosure 1 so that it contacts the inner wall surface 7 of one end portion of the enclosure 1 but does not contact the inner wall surface 8 of the intermediate portion of the enclosure 1.
  • CVD chemical vapor deposition
  • a material containing Si and Ti is filled inside the end of the enclosure 1, a material containing a low thermal conductivity ceramics 9 such as SiC whisker and Si 3 N 4 porous material is filled inside the intermediate portion of the enclosure 1, and a material containing Si and Ti is filled inside the other end.
  • the enclosure 1 filled with the Si/Ti-containing material and with the low heat conductivity ceramic material is baked for reaction in the presence of N 2 gas to transform the material containing Si and Ti into porous ceramics such as Si 3 N 4 , TiN, TiO 2 and TiON, thereby converting the materials into fillers 2, 3.
  • this ceramic heater formed in a way mentioned above has improved adherence of the heater coil 6 and the filler 2 to the inner wall surface 7 of the enclosure 1, resulting in an improved heat conduction, which in turn allows for an immediate temperature rise.
  • Another advantage of this ceramic heater is that the manufacturing process has a fewer number of fabrication steps and therefore is simple, reducing the cost and improving reliability of the ceramic heater built into the ceramic glow plug.
  • tungsten (W) wire 0.2 mm in diameter was wound into a coil 3.5 mm in outer diameter.
  • the coiled tungsten wire was then covered over its surface with SiC by the CVD.
  • SiC-coated tungsten wire coil arranged in a porous mold such as plaster mold for slip cast, a 85:15 Si/Ti slurry was poured in a specified amount into the porous mold.
  • an SiC whisker in a slurry state is poured onto the semi-solidified slurry in the porous mold.
  • the above-mentioned Si/Ti slurry was poured in a specified amount onto the SiC whisker n the porous mold.
  • the water in the slurry was absorbed through the porous mold until the slurry solidified completely.
  • a molded body was obtained in which a material containing Si and Ti was put around the tungsten coil, with the SiC whisker disposed in the intermediate portion of the enclosure.
  • the molded body was taken out of the porous mold and dried in the presence of N 2 gas.
  • the dried molded body was inserted into the enclosure 1, a pipe-shaped cylinder made of dense Si 3 N 4 with a relative density of more than 99%.
  • the outer diameter of the molded body and the inner diameter of the enclosure 1 were almost equal with virtually no gap between them.
  • the molded body inserted into the enclosure 1 was baked in a furnace that contained 5 atm of N 2 gas heated up to 1,400°C to convert the Si and Ti components of the material into the baked nitrides such as Si 3 N 4 and TiN, i.e., porous ceramics fillers 2, 3.
  • the SiC whisker was transformed into a low heat conductivity ceramics member 5 having N 2 gas sealed therein. No gap was formed in the boundary between the baked body and the enclosure 1 because of the TiN expansion of about 0.2% during the baking process.
  • the end surfaces 15 of the enclosure 1 and the porous ceramics fillers 2, 3 are coated by the CVD with Si 3 N 4 to completely seal N 2 gas in the intermediate portion of the enclosure 1.
  • the tungsten wire coil was immersed in a toluene solution of polycarbosilane, an organic silicon polymer, and was heated to a specified temperature in the presence of N 2 gas to convert the organic silicon polymer into Si 3 N 4 .
  • the above process was repeated five times to form a ceramic film about 50 ⁇ m thick over the surface of the tungsten wire coil.
  • This ceramics-coated tungsten wire coil was used to fabricate the ceramic heater in the same process as the first embodiment.
  • a slurry of only Si instead of a Si/Ti mixture was used for filling the interior of the end portions of the enclosure 1 and, for the intermediate portion of the enclosure 1, the same SiC whisker slurry as in the first embodiment was used to manufacture the ceramic heater in the same process as the first embodiment.
  • the porous ceramics that forms the fillers 2, 3 was a porous Si 3 N 4 .
  • a further example used a 80:20 Si/Si 3 N 4 slurry instead of the Si/Ti slurry for filling the interior of the end portions of the enclosure 1.
  • the same process as the first embodiment was followed to fabricate the ceramic heater.
  • the porous ceramics forming the fillers 2, 3 was a porous Ni 3 N 4 .
  • Still another example used an Si slurry instead of the Si/Ti slurry for filling the interior of the end portions of the enclosure 1.
  • an Si slurry was also used instead of SiC whisker slurry.
  • a ceramic heater was fabricated in the same process as the first embodiment.
  • the porous ceramics forming the fillers 2, 3 was a porous Si 3 N 4 and the porous ceramics forming the low heat conductivity ceramic member 5 was an Si 3 N 4 porous material.
  • the ceramic heater according to this invention can be fabricated in ways described in the above embodiments. Although there are slight variations in temperature vise time with respect to current supply time, almost similar effects can be produced.
  • the ceramic heater is used with a ceramics glow plug built into a diesel engine and is formed as a two-layer structure consisting of an inner shell and an outer shell 21.
  • the ceramics of the inner shell in which a metal coil 30 as a heater wire is embedded uses a ceramics that expands during baking.
  • the outer shell 21 is formed into a pipe-shaped shell made from a dense ceramics which contains fillers 22, 23 of non-contracting ceramics in the end portions thereof. In the central portion of the outer shell 21 is installed a low heat conductivity ceramics member 25.
  • the metal coil 30 is installed in the fillers 22, 23 and the low heat conductivity ceramic member 25 inside the outer shell 21.
  • the outer shell 21 is made from a dense ceramics such as silicon nitride Si 3 N 4 and has one end thereof formed as a closed end 35 and the other end as an open end. Further, the outer shell 21 is formed with fine holes 36 such as slits piercing through the wall and running in the longitudinal direction or holes piercing through the wall. Through these fine holes gases present in the interior of the outer shell are evacuated to create a vacuum inside during the manufacture process. With the fine holes 36 formed in the outer shell 21, it is possible to sinter the Si and Ti materials installed in the outer shell 21 while applying pressure three-dimensionally during gas-pressure baking.
  • the non-contracting ceramics that forms the fillers 22, 23 filling the interior of the end portions of the outer shell 21 is made by baking the material containing Si and Ti and transforming them into a porous ceramics containing Si 3 N 4 , TiN, TiO 2 and TiON.
  • the volume of Si and Ti before backing is virtually equal to that of Si 3 N 4 , TiN, TiO 2 and TiON combined after baking.
  • the material of the fillers does not contract when subjected to baking. Hence, no gap is formed in the boundary between the inner wall surfaces 27, 34 of the dense Si 3 N 4 outer shell 21 and the outer surfaces of the fillers 22, 23.
  • the low heat conductivity ceramics 25 installed in the central portion inside the outer shell 21 is made from a ceramic powder, ceramic fibers or ceramic whiskers, all made of Si 3 N 4 and metal nitride or oxide. That is, the low heat conductivity ceramics 25 is made of such material as SiC whisker, Si 3 N 4 whisker, Al 2 O 3 whisker, Al 2 O 3 -SiO 2 whisker, ceramic powder or Si 3 N 4 porous material. It is desired from the standpoint of heat insulation that the ceramics around the current control coil 29 be formed of a material with a low heat conductivity almost equal to that of air.
  • the metal coil 30 is made of a high-melting point metal wire such as a tungsten wire, which is formed into a three-dimensional coil. A portion of the coil arranged in contact with the inner wall surface 27 of the outer shell 21 constitutes a heater coil 6 and a portion of the coil spaced from the inner wall surface 34 of the outer shell 21 constitutes the current control coil 29.
  • the metal coil 30 has a connecting wire 31 that connects one end of the heater coil 26 and one end of the current control coil 29; a connecting wire 32 that connects to the other end of the heater coil 26, extends along the inside of the outer shell 21 and projects from the filler 23 of the non-contracting ceramics; and a connecting wire 33 that connects to the other end of the current control coil 29, extends along the inside of the outer shell 21 and projects from the filler 23 of the non-contracting ceramics.
  • This ceramic heater is assembled into a ceramic glow plug.
  • One end of the outer shell 1 is secured to a hollow body that has an electrode mounted in a hollow portion thereof through an insulator such as insulating bushing.
  • the hollow body is made from a metal such as heat resistant alloy and has a thread for mounting to other component.
  • the end of the connecting wire 33 is connected to the electrode and the end of the connecting wire 32 is connected to the hollow body. Therefore, in this ceramic heater, electric current flows from the electrode to the connecting wire 33 to the current control coil 29 to the connecting wire 31 to the heater coil 26 to the connecting wire 32 to the hollow body.
  • an outer shell 21 made of a dense ceramics is formed closed at one end 35 and open at the other end and, as shown in Figure 3, is formed with fine holes 36, such as slits that pierce through the wall and extend in the longitudinal direction and holes that pierce through the wall.
  • a three-dimensionally wound metal coil 30 is made from, say, a tungsten wire.
  • the tungsten wire coil 30 is installed inside the outer shell 21 in such a way that it contacts the inner wall surface 7 of one end portion of the outer shell 21 and is spaced from the inner wall surface 28 of the intermediate portion of the outer shell.
  • a material containing Si and Ti is filled inside one end portion of the outer shell 21; a material containing a low heat conductivity ceramic member such as ceramic powder is filled inside the intermediate portion of the outer shell 21; and a material containing Si and Ti is filled inside the other end portion of the outer shell 21.
  • the outer shell filled with the Si/Ti material and the low heat conductivity ceramics member 25 is sintered in an N 2 atmosphere at a gas pressure of less than 9.9 kgf/cm 2 to convert the Si/Ti material into a porous ceramics containing Si 3 N 4 , TiN, TiO 2 and TiON, i.e., into a non-contracting ceramics, to form the fillers 22, 23 and cause the non-contracting ceramics to adhere to the dense ceramics of the outer shell 21.
  • the ceramics heater is then placed in a vacuum and, as shown in Figure 4, the fine holes 36 formed in the wall of the outer shell 21 are sealed with a sealing film 24 such as glass and brazing filler metal to hermetically enclose the interior of the outer shell 21, thus forming the ceramic heater.
  • a sealing film 24 such as glass and brazing filler metal to hermetically enclose the interior of the outer shell 21, thus forming the ceramic heater.
  • the heater coil 26 which constitutes a heater portion is in contact with the inner wall surface 27 of the outer shell 21 and is embedded in the non-contracting ceramic filler 22 that contacts the inner wall surface 27 of the outer shell 21.
  • This construction allows the entire outer shell 21 to be heated uniformly and assures a very good heat conductivity of the heater portion, offering an improved heating performance that allows the heater portion to be heated quickly upon energization.
  • Figure 5 shows a graph illustrating the relation between the temperature (°C) of the heater portion and the energizing time (second).
  • the ceramic heater of this invention is represented by a broken line and the conventional glow plug by a solid line.
  • Figure 5 shows that the heater of this invention can be heated to a specified temperature in a shorter energizing time than is required with the conventional heater, demonstrating the superior heating characteristic.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Resistance Heating (AREA)

Claims (16)

  1. Elément chauffant céramique qui comprend :
    des charges (2, 3, 5, 22, 23, 25) disposées à l'intérieur d'un boítier (1, 21) ;
    une bobine de chauffage (6, 26) disposée dans une partie d'extrémité avant du boítier dans laquelle une des charges est située ; et
    une bobine de contrôle de courant (9, 29) disposée dans une partie centrale du boítier ;
    ledit élément chauffant céramique étant caractérisé en ce que :
    le boítier est constitué d'une céramique dense ;
    les charges consistent en céramique poreuse (2, 3, 22, 23) contenue dans des parties d'extrémité du boítier et en une céramique à faible conductivité thermique (5, 25) contenue dans une partie centrale du boítier ;
    la bobine de chauffage et la bobine de contrôle de courant sont faites d'une seule et même bobine en métal (10, 30) ;
    la bobine de chauffage (6, 26) est disposée en contact avec une surface de paroi interne de la partie du boítier dans laquelle les charges (2, 22) sont contenues ; et
    la bobine de contrôle de courant (9, 29) est espacée d'une surface de paroi interne de la partie du boítier dans laquelle la céramique à faible conductivité thermique (5, 25) est contenue, de manière que la bobine de contrôle de courant soit isolée thermiquement.
  2. Elément chauffant céramique selon la revendication 1, dans lequel le boítier est constitué d'une céramique de Si3N4, les charges (2, 3, 22, 23) consistent en céramique poreuse renfermant Si et Ti, et la surface de paroi interne du boítier (1, 21) et les surfaces circonférentielles externes des charges (2, 3, 22, 23) adhèrent fortement l'une à l'autre sans espace entre elles.
  3. Elément chauffant céramique selon la revendication 2, dans lequel un gaz de N2 est enfermé hermétiquement dans la partie centrale du boítier (1, 21) dans laquelle la céramique à faible conductivité thermique (5, 25) est contenue.
  4. Elément chauffant céramique selon l'une quelconque des revendications 1 à 3, dans lequel le boítier (1) est ouvert aux deux extrémités, qui sont fermées par des films d'étanchéité (4) pour étancher l'intérieur du boítier.
  5. Elément chauffant céramique selon la revendication 4, dans lequel les films d'étanchéité (4) sont constitués de verre ou du même type de céramique que le boítier.
  6. Elément chauffant céramique selon l'une quelconque des revendications 1 à 3, dans lequel le boítier (21) est constitué d'une céramique dense et est fermé à une extrémité et ouvert à l'autre extrémité, et la céramique poreuse contenue dans les parties d'extrémité du boítier (21) est une céramique ne se contractant pas.
  7. Elément chauffant céramique selon l'une quelconque des revendications 1 à 6, dans lequel la bobine en métal est constituée d'un fil de tungstène.
  8. Elément chauffant céramique selon l'une quelconque des revendications 1 à 7, dans lequel une surface de la bobine en métal est revêtue d'un film de céramique déposé en phase gazeuse par procédé chimique ou d'un film de céramique transformé en polymère de silicium organique.
  9. Elément chauffant céramique selon l'une quelconque des revendications 1 à 8, dans lequel la céramique poreuse est une céramique ne se contractant pas fabriquée par frittage de Si et Ti pour une réaction et la céramique ne se contractant pas renferme Si3N4, TiN, TiO2 et TiON.
  10. Elément chauffant céramique selon l'une quelconque des revendications 1 à 9, dans lequel la céramique à faible conductivité thermique (5, 25) est constituée de whiskers de céramique et/ou de poudre de céramique.
  11. Elément chauffant céramique selon l'une quelconque des revendications 1 à 10, dans lequel la céramique à faible conductivité thermique (5, 25) est constituée de Si3N4 et d'un nitrure de métal ou d'un oxyde de métal.
  12. Procédé de fabrication d'un élément chauffant céramique comprend les phases consistant à :
    fabriquer un boítier (1, 21) et une bobine en métal (10, 30) ;
    installer la bobine en métal (10, 30) à l'intérieur du boítier (1, 21) ; et
    introduire des charges à l'intérieur du boítier (1, 21) ;
    ledit procédé de fabrication d'éléments chauffants céramiques étant caractérisé par les phases consistant à :
    fabriquer le boítier à partir d'une céramique dense ;
    fabriquer la bobine en métal (10, 30) à partir d'un fil de métal à point de fusion élevé ;
    installer la bobine en métal à l'intérieur du boítier de manière que la bobine en métal soit en contact avec une surface de paroi interne d'une partie d'extrémité du boítier et soit espacée d'une surface de paroi interne d'une partie intermédiaire du boítier ;
    introduire un matériau renfermant Si et Ti dans une des parties d'extrémité du boítier ; introduire une céramique à faible conductivité thermique (5, 25) dans la partie intermédiaire du boítier et introduire un matériau renfermant Si et Ti dans l'autre partie d'extrémité du boítier ;
    faire cuire le boítier avec les matériaux de charge et la bobine en métal pour une réaction dans une atmosphère de N2 afin de transformer le matériau Si/Ti en une céramique poreuse renfermant Si3N4 et TiN ; et
    faire adhérer la céramique poreuse à la céramique dense du boítier.
  13. Procédé de fabrication d'éléments chauffants céramiques selon la revendication 12, dans lequel une fois que le matériau renfermant Si et Ti a été fritté pour une réaction, les surfaces d'extrémité du boítier (1) sont revêtues des films d'étanchéité (4) pour étancher l'intérieur du boítier.
  14. Procédé de fabrication d'éléments chauffants céramiques selon la revendication 12 ou 13, dans lequel avant que la bobine en métal ne soit installée à l'intérieur du boítier, la surface de la bobine en métal est revêtue d'une céramique ayant pratiquement le même coefficient de dilatation thermique que la bobine en métal.
  15. Procédé de fabrication d'éléments chauffants céramiques selon l'une quelconque des revendications 12 à 14, dans lequel le boítier (21) est constitué d'une céramique dense, est fermé à une extrémité et ouvert à l'autre extrémité, et est doté de minces ouvertures (36) traversant sa paroi ; dans lequel une fois que le matériau renfermant Si et Ti a été introduit dans le boítier (21) et fritté pour une réaction et transformé en une céramique poreuse, c'est-à-dire une céramique ne se contractant pas, les minces ouvertures (36) dans le boítier (21) sont hermétiquement fermées dans un vide par les films d'étanchéité (24) et également les films d'étanchéité (24) qui obturent hermétiquement la surface d'extrémité du boítier (21).
  16. Procédé de fabrication d'éléments chauffants céramiques selon la revendication 15, dans lequel la céramique poreuse est une céramique ne se contractant pas qui renferme Si3N4, TiN, TiO2 et TiON, la céramique ne se contractant pas adhère à la céramique dense de Si3N4 du boítier (21), et les minces ouvertures (36) formées dans le boítier (21) sont hermétiquement fermées par les films d'étanchéité (24) faits de Si3N4 dans un vide.
EP19940307544 1993-10-20 1994-10-14 Elément chauffant céramique et son procédé de fabrication Expired - Lifetime EP0650020B1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP05284204A JP3075660B2 (ja) 1993-10-20 1993-10-20 セラミックスヒータ及びその製造方法
JP5284203A JP3050266B2 (ja) 1993-10-20 1993-10-20 セラミックス発熱体及びその製造方法
JP284204/93 1993-10-20
JP284203/93 1993-10-20

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EP0650020A2 EP0650020A2 (fr) 1995-04-26
EP0650020A3 EP0650020A3 (fr) 1996-06-05
EP0650020B1 true EP0650020B1 (fr) 1999-04-07

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10169982A (ja) * 1996-12-11 1998-06-26 Isuzu Ceramics Kenkyusho:Kk セラミックヒータ及びその製造方法
DE102004045815A1 (de) * 2004-09-22 2006-03-23 Robert Bosch Gmbh Verfahren zur Einbettung eines metallischen Drahts in einem keramischen Element
WO2009096311A1 (fr) 2008-01-29 2009-08-06 Tounetsu Corporation Réchauffeur de type à immersion
EP3163171B1 (fr) * 2015-10-30 2018-12-12 NGK Spark Plug Co., Ltd. Bougie de préchauffage
DE102016105069A1 (de) 2016-03-18 2017-09-21 Eberhard Karls Universität Tübingen Medizinische Fakultät Antivirale Immuntherapie durch Membranrezeptorligation

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5872821A (ja) * 1981-10-26 1983-04-30 Ngk Spark Plug Co Ltd グロ−プラグとその製法
JP2720033B2 (ja) * 1987-10-28 1998-02-25 京セラ株式会社 自己制御型セラミックグロープラグ
US5084606A (en) * 1990-05-17 1992-01-28 Caterpillar Inc. Encapsulated heating filament for glow plug
JPH1114622A (ja) * 1997-06-20 1999-01-22 Matsushita Electric Ind Co Ltd 便検査装置

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DE650020T1 (de) 1996-05-02
EP0650020A3 (fr) 1996-06-05
EP0650020A2 (fr) 1995-04-26
DE69417676D1 (de) 1999-05-12
DE69417676T2 (de) 1999-09-30

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