EP1996866A2 - Élément de chauffage à couches multiples - Google Patents

Élément de chauffage à couches multiples

Info

Publication number
EP1996866A2
EP1996866A2 EP07758972A EP07758972A EP1996866A2 EP 1996866 A2 EP1996866 A2 EP 1996866A2 EP 07758972 A EP07758972 A EP 07758972A EP 07758972 A EP07758972 A EP 07758972A EP 1996866 A2 EP1996866 A2 EP 1996866A2
Authority
EP
European Patent Office
Prior art keywords
layer
heating element
insulative
thickness
heating
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP07758972A
Other languages
German (de)
English (en)
Other versions
EP1996866A4 (fr
Inventor
William J. Walker
John W. Hoffman
James L. May
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Federal Mogul LLC
Original Assignee
Federal Mogul LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Federal Mogul LLC filed Critical Federal Mogul LLC
Publication of EP1996866A2 publication Critical patent/EP1996866A2/fr
Publication of EP1996866A4 publication Critical patent/EP1996866A4/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • 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
    • H05B3/14—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 the material being non-metallic
    • H05B3/141—Conductive ceramics, e.g. metal oxides, metal carbides, barium titanate, ferrites, zirconia, vitrous compounds
    • 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
    • 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
    • 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
    • H05B2203/027—Heaters specially adapted for glow plug igniters

Definitions

  • the present invention relates to a heating element and, in particular, a ceramic heating element, such as ceramic heating elements used in high temperature glow plugs for diesel engines and gas igniters, and methods of manufacture therefore.
  • Ceramic heating elements such as the glow plug illustrated in FIG. 1, are well known in the industry.
  • a glow plug 2 typically includes a heating element having an electrically conducting core 8 surrounded by an electrically insulative layer 6.
  • the insulative layer 6 is in turn surrounded by an outer resistive layer 4 which makes contact with the conducting core 8 at the electrical connection area 9.
  • an outer resistive layer 4 which makes contact with the conducting core 8 at the electrical connection area 9.
  • the layered structure is formed by sequentially slip casting layers from suspensions of different compositions in a porous mold, and then sintered to form a monolithic body. The resulting body is then electrically connected to form a ceramic heating element.
  • One problem with sequential casting is that the geometric configuration of the heating element is generally limited to shapes that allow each progressive layer to be formed against the previous layer.
  • the configuration of any layer is generally limited to a thin layer of fairly uniform thickness or a core that is substantially solid, but may be partially hollow due to piping which occurs as the cast material solidifies. This sequential stacking of layers limits the geometric configuration and prevents each layer from being optimized for use in a heating element and being optimized for use in particular applications.
  • the electrical connection 9 between the conducting core 8 and the outer resistive layer 4 is in close proximity to the external surface of the glow plug 2 and may be subject to oxidation from the surrounding atmosphere during service. Sufficient oxidation at the electrical connection 9 can degrade the electrical connection 9 by the formation of an electrically insulating oxide layer, or the formation of a porous layer having an interfacial porosity, to the point where current can no longer pass between the conducting core 8 and the resistive layer 4, resulting in a failure of the glow plug to heat when an electrical current is applied.
  • the present invention relates to heating elements and, in particular, to heating elements for glow plugs and gas igniters as well as the method of manufacturing thereof.
  • the heating element generally includes a first layer formed from or acting as an electrically insulative material and a second layer formed out of a electrically conductive material that is molded around portions of the first layer.
  • the thickness of the conductive layer may be varied along the length as well as around the circumference of the heating element to provide a desirable heating profile for a specific application.
  • the molded profile of the first layer and the profile of a die in which the electrically conductive layer is molded allows for these geometric profiles and variations in the heating profile that are not available with the slip casting method.
  • the invention includes a method of forming a heating element including the steps of forming a first layer, placing the first layer in a die, and molding an electrically conductive layer around the first electrically insulative layer.
  • FIG. 1 is a sectional view of a prior art slip casted heating element
  • FIG. 2 is a sectional view of the present invention having the heating portion focused at a first end
  • FIG. 3 is a sectional view of the present invention having an extended heating portion
  • FIG. 4 is a sectional view of the present invention having a heating portion primarily focused at the first end;
  • FIG. 5 is a sectional view of the present invention having a heating portion primarily focused at the first end;
  • FIG. 6 is a diagram showing the method steps in forming a heating element
  • FIG. 7 is a diagram of a first alternative method of forming a heating element
  • FIG. 8 is a diagram of a second alternative method of forming a heating element
  • FIG. 9 is a cross-sectional view of the first layer along lines 9-9 in FIG. 8;
  • FIG. 10 is a cross-sectional view of the first layer in a die along lines 10-
  • FIG. 11 is a cross-sectional view of the formed heating element along lines 11-1 1 in FIG. 8.
  • the present invention is directed to a heating element 10 having an electrically insulative layer 20, formed from an electrically insulative material, and an electrically conductive layer 30, formed from an electrically conductive material.
  • the conductive material is attached to a first electrical contact 40 and a second electrical contact 42 which allow electrical current to flow through the conductive material to generate heat that is primarily focused where the thickness of the conductive layer 30 is at its thinnest point and has the smallest cross cross-sectional area.
  • the heating element 10 will be generally formed with electrical contacts, which may vary in size, shape and configuration.
  • the heating element also may include a base portion 14 formed in a variety of configurations and shapes.
  • the insulative layer 20 further includes an outer surface 22 that creates a geometric profile that may vary in shape and diameter to create the desired heating profile.
  • the insulative layer 20 generally includes a first end 26, a second end 28, and a center portion 27.
  • a passage 24 extends from the first end 26 to the second end 28.
  • the insulative layer 20 is generally formed from an insulative material and can be made from any known electrical insulator by any known method. Such methods may include extrusion, molding, powder compaction, and other methods. Ceramic powders with gelling additives as well as certain thermoplastic materials can be formed and sintered to make good insulators.
  • the insulative material may be a material such as silicon nitride, silicon carbide, aluminum oxide, aluminum nitride, or other ceramic materials.
  • This list of potential insulative elements in no way should limit the materials that may be used to form the insulator.
  • the insulative material may be formed of any material that has good electrical insulation properties or is commonly used in heating elements as an insulative material.
  • the insulative material may also comprise electrically conductive particles in a matrix of electrically insulating material, such as a composite of molybdenum disilicide and silicon nitride wherein the conducting molybdenum disilicide particles are present below the percolation threshold and are thus electrically isolated from one another.
  • the insulative layer 20 can be formed in a variety of shapes such as those in FIGS. 3 and 4, which were not previously possible using the slip casting method. It is preferable for the insulative layer 20 to be formed from a material that may be reliably molded into various shapes.
  • FIGS. 4 and 5 illustrate profiles that have an outer diameter at a first end 26 that is greater than the outer diameter at a center portion 27. The second end 28 may also have a diameter that is greater than the center portion 27 and sometimes a diameter that is greater than the first end 26.
  • the insulative layer 20 may be highly customized to provide specific heating profiles when combined with the conductive layer 30.
  • the conductive layer 30 is generally formed from a conductive material that allows electrical current to flow between a first electrical contact 40 and a second electrical contact 42.
  • the conductive layer 30 generally forms an outer surface 12 of the heating element 10.
  • the heating profile may be adjusted. For example, as illustrated in FIG. 3, the center passage 24 is filled with conductive material of the conductive layer 30 and has a relatively large thickness which allows for less resistance and easier electrical current flow.
  • the thickness of the conductive layer 30 in the heating portion 16 of the heating element 10 is much thinner which creates a greater resistance and increases the amount of heat output near the heating portion 16.
  • the heating output will be the greatest.
  • the thin area is limited to only a portion of the tip of the heating element 10 thereby creating a heating profile that is primarily focused in the vicinity of the first end 26.
  • the heating profile may be varied by changing the profile of either the insulative layer 20 or the conductive layer 30.
  • the conductive layer 30 extends from an area proximate to the first end 26 of the insulative layer 20 towards the second end 28 along the center portion 27. This creates a heating profile that extends further along with a greater heating capacity than the heating element illustrated in FIG. 2.
  • the heating element 10 illustrated in FIG. 4 includes a heating portion that is primarily focused near the first end 26 of the insulative layer 20 where the thickness is much thinner than the thickness near the center portion 27 of the insulative layer. Therefore, the heating profile of the heating element 10 is primarily focused near the first end 26 of the insulator, however, the heating element does provide some heat along the center portion 27 of the insulator.
  • FIG. 5 is a further variation of the heating element in FIG.
  • the heating element may include projections along the outer surface 22 that allows centering of the heating element in the die that receives the insulative layer 20 for overmolding with the conductive layer. These projections formed from the insulative layer 20 may also modify the heating profile by creating areas on the outer surface 12 of the heating element 10 that do not generate heat. Typically, at least three of these projections would be used to center the insulative portion within the die; however more or less may be used depending upon the geometric shape and the die.
  • the conductive layer 30 may be formed from a variety of known conductive materials such as conductive materials formed from ceramic matter that are typically used in glow plugs today including molybdenum disilicide, titanium nitride, zirconium nitride and titanium boride.
  • the conductive material may also comprise electrically insulating particles in a matrix of electrically conducting material, such as a composite of molybdenum disilicide and silicon nitride wherein the conducting molybdenum disilicide grains are present above the percolation threshold and thus form a continuous electrically conductive path through the material.
  • the conductive layer may also comprise metals such as platinum, iridium, rhenium, palladium, rhodium, gold, copper, silver, tungsten and alloys of these to name a few.
  • metals such as platinum, iridium, rhenium, palladium, rhodium, gold, copper, silver, tungsten and alloys of these to name a few.
  • the conductive layer 30 needs to be formed of a conductive material that allows for easy molding in a die. Any conductive material or resistive heating material currently in use with heating elements may be used.
  • the heating element 10 is generally formed by a method of first forming an insulative layer 20 illustrated as steps 101 in FIG. 6, 201 in FIG. 7, and 301 in FIG. 8.
  • an injection molding die 50 is provided having a geometric profile that will form the outer surface 12 of the heating element 10 and is illustrated as step 102 in FIG. 6, step 202 in FIG. 7, and step 302 in FIG. 8.
  • the insulative layer 20 is formed to the desired geometric shape out of an insulative material such as by molding powder formation or other methods, the insulative layer 20 is inserted in an injection molded die 50 as shown in steps 103 in FIG. 6, 203 in FIG. 7, and 303 in FIG. 8.
  • the molten conductive material is forced into the die as illustrated in steps 104 in FIG. 6, 204 in FIG. 7, and 304 in FIG. 8. With the molten conductive material in the die and substantially filling the voids, the material is allowed to cool and harden as illustrated in steps 105 of FIG. 6 and 305 of FIG. 8.
  • the formed heating element 10 is then removed from the die 50 as illustrated in step 106 of FIG. 6, 205 of FIG. 7, and 306 of FIG. 8.
  • the heating element 10 is then sintered to form a monolithic material (not shown). In the method illustrated in FIG. 7, the excess material is removed in step 206.
  • ceramic materials are commonly formed by first forming an assembly of finely divided particles and subsequently firing the assembly to sinter the particles in to a monolithic article. Ceramic materials are commonly injection molded by mixing the particles with a thermoplastic medium or binder such as, but not limited to, wax or polyethylene or a blend of the two, and heating the resulting mixture so that the molten mixture is sufficiently fluid to fill a die cavity, and subsequently cooling the molded article to form a rigid part that can be removed from the die.
  • non-thermoplastic binder medium such as agar/water may also be employed. The binder medium is then removed by a process commonly known as debinding, which may include solvent extraction and thermal debinding steps.
  • a first layer can be formed from a material that is insulative or even non- insulative in some embodiments.
  • the first layer may use any material that is known in the casting or molding process to be able to be later removed or destroyed during the casting process.
  • an insulative or rigid layer may be added to fill the pockets within the conductive layer, such as an insulator that is not conducive to the overmolding process.
  • the second end 28 of the insulative material 20 may engage the inner surface of the die to hold the insulative layer 20 in place within the cavity of the die 50. This ensures proper placement within the die 50 so that as the molten conductive layer 30 flows and is forced into the die the desired profile is created and the insulative layer 20 does not move.
  • the first layer By forming a first layer through extrusion molding or powder compaction methods similar to that currently used to form spark plug insulators, the first layer can be created with a specific geometric profile.
  • the first layer can be formed from an insulative material for use in conjunction with the conductive layer, or from a material that is easily removable once the conductive layer is overmolded on the first layer.
  • a heating profile may be created for the heating element 10 that allows hot and cold spots and even areas that gradually change on the heating element, both around the circumference as well as along the length.
  • a heating profile can be created that has, for example, a hot spot on half of the circumference of the heating element 10 and removed from the first end 26 of the insulative layer 20 so that on the heating element 10 the tip of the heating element as well as at least half of the circumference and the portion toward the second end may be cooler than the desired hot spot.

Abstract

L'invention concerne un élément de chauffage, en particulier, un élément de chauffage en céramique, similaire aux éléments de chauffage en céramique utilisés dans les bougies de préchauffage haute température des moteurs diesel et des allumages de gaz. L'élément de chauffage comprend une couche isolante et une couche conduisant l'électricité. La couche conduisant l'électricité est constituée d'un seul matériau et d'une seule composition. La méthode de fabrication comprend les étapes de création de la couche isolante et de moulage d'une couche conductrice autour de la couche isolante.
EP07758972A 2006-03-23 2007-03-21 Élément de chauffage à couches multiples Withdrawn EP1996866A4 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US78533406P 2006-03-23 2006-03-23
US11/688,294 US20070221647A1 (en) 2006-03-23 2007-03-20 Multi-layer heating element
PCT/US2007/064472 WO2007112239A2 (fr) 2006-03-23 2007-03-21 Élément de chauffage à couches multiples

Publications (2)

Publication Number Publication Date
EP1996866A2 true EP1996866A2 (fr) 2008-12-03
EP1996866A4 EP1996866A4 (fr) 2012-04-11

Family

ID=38532276

Family Applications (1)

Application Number Title Priority Date Filing Date
EP07758972A Withdrawn EP1996866A4 (fr) 2006-03-23 2007-03-21 Élément de chauffage à couches multiples

Country Status (7)

Country Link
US (1) US20070221647A1 (fr)
EP (1) EP1996866A4 (fr)
JP (1) JP5261369B2 (fr)
KR (1) KR20080106339A (fr)
CN (1) CN101449103B (fr)
BR (1) BRPI0709051A2 (fr)
WO (1) WO2007112239A2 (fr)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2711016A1 (fr) * 2007-12-29 2009-07-09 Saint-Gobain Ceramics & Plastics, Inc. Allumeur ceramique coaxial et procedes de fabrication
US20100044929A1 (en) * 2008-08-25 2010-02-25 Jeffrey Boehler Method of forming a spark plug insulator
US20100059496A1 (en) * 2008-09-08 2010-03-11 Federal-Mogul Ignition Company Metal sheath glow plug
US8511287B2 (en) * 2009-09-08 2013-08-20 EcoMotors International Supercritical-state fuel injection system and method
BR112015015098B1 (pt) 2012-12-28 2021-02-09 Philip Morris Products S.A conjunto de aquecimento para aquecimento de um substrato de formação de aerossol, dispositivo gerador de aerossol e método de fabricação de um conjunto de aquecimento
DE102013215269A1 (de) * 2013-08-02 2015-02-05 Robert Bosch Gmbh Glühstiftkerze mit einem Heizelement mit innen liegender Kontaktierung, und Herstellungsverfahren derselben
CN103953946B (zh) * 2014-04-23 2016-01-20 久盛电气股份有限公司 一种核电用氢点火器
DE102014225908A1 (de) * 2014-12-15 2016-06-16 Robert Bosch Gmbh Glühstiftkerze
DE102015200778A1 (de) * 2015-01-20 2016-07-21 Robert Bosch Gmbh Glühstiftkerze
CN109526079B (zh) * 2018-12-18 2023-12-15 重庆利迈科技有限公司 一种大电压陶瓷电热体

Citations (4)

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Publication number Priority date Publication date Assignee Title
US4742209A (en) * 1985-06-27 1988-05-03 Jidosha Kiki Co., Ltd. Glow plug for diesel engine
US5304778A (en) * 1992-11-23 1994-04-19 Electrofuel Manufacturing Co. Glow plug with improved composite sintered silicon nitride ceramic heater
US6184497B1 (en) * 1999-06-16 2001-02-06 Le-Mark International Ltd. Multi-layer ceramic heater element and method of making same
US20040079745A1 (en) * 2001-11-09 2004-04-29 Christoph Haluschka Plug heater for a pencil-type glow plug and corresponding glow plug

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US6363898B1 (en) * 1996-11-14 2002-04-02 Quik-Change International, Llc Quick replacement igniter assembly
US5993722A (en) * 1997-06-25 1999-11-30 Le-Mark International Ltd. Method for making ceramic heater having reduced internal stress
CN2319991Y (zh) * 1998-01-25 1999-05-19 雷彼得 一种柴油机电热塞的圆锥形全陶瓷加热芯
DE10353972B4 (de) * 2003-11-19 2006-03-16 Beru Ag Verfahren zum Herstellen von keramischen Glühkerzen
US7351935B2 (en) * 2004-06-25 2008-04-01 Ngk Spark Plug Co., Ltd. Method for producing a ceramic heater, ceramic heater produced by the production method, and glow plug comprising the ceramic heater
CA2596006A1 (fr) * 2005-02-05 2006-08-17 Saint-Gobain Ceramics & Plastics, Inc. Allumeurs ceramiques

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4742209A (en) * 1985-06-27 1988-05-03 Jidosha Kiki Co., Ltd. Glow plug for diesel engine
US5304778A (en) * 1992-11-23 1994-04-19 Electrofuel Manufacturing Co. Glow plug with improved composite sintered silicon nitride ceramic heater
US6184497B1 (en) * 1999-06-16 2001-02-06 Le-Mark International Ltd. Multi-layer ceramic heater element and method of making same
US20040079745A1 (en) * 2001-11-09 2004-04-29 Christoph Haluschka Plug heater for a pencil-type glow plug and corresponding glow plug

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO2007112239A2 *

Also Published As

Publication number Publication date
US20070221647A1 (en) 2007-09-27
WO2007112239A2 (fr) 2007-10-04
BRPI0709051A2 (pt) 2011-06-28
JP5261369B2 (ja) 2013-08-14
KR20080106339A (ko) 2008-12-04
CN101449103A (zh) 2009-06-03
JP2009531640A (ja) 2009-09-03
EP1996866A4 (fr) 2012-04-11
CN101449103B (zh) 2011-06-08
WO2007112239A3 (fr) 2008-11-27

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