JPH07139737A - Ceramic heater - Google Patents
Ceramic heaterInfo
- Publication number
- JPH07139737A JPH07139737A JP16088494A JP16088494A JPH07139737A JP H07139737 A JPH07139737 A JP H07139737A JP 16088494 A JP16088494 A JP 16088494A JP 16088494 A JP16088494 A JP 16088494A JP H07139737 A JPH07139737 A JP H07139737A
- Authority
- JP
- Japan
- Prior art keywords
- ceramic
- conductive material
- heating element
- lead
- heat generating
- 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.)
- Pending
Links
Landscapes
- Resistance Heating (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明はディーゼルエンジンの始
動時やアイドリング時に副燃焼室内を急速に予熱する自
己飽和型のグロープラグをはじめとする各種加熱用ヒー
ター等に好適な高温用のセラミック発熱体に関するもの
である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high temperature ceramic heating element suitable for various heating heaters such as a self-saturation type glow plug that rapidly preheats a sub combustion chamber at the time of starting a diesel engine or idling. It is about.
【０００２】[0002]
【従来の技術】従来よりディーゼルエンジンの始動促進
に用いられるグロープラグや各種点火用及び加熱用ヒー
ターとして、耐熱金属製のシース内に耐熱絶縁粉末を充
填し、該耐熱絶縁粉末中にニッケル（Ｎｉ）−クロム
（Ｃｒ）等を主体とする高融点金属線から成る発熱抵抗
体を埋設したシーズヒーターや、高電圧の火花放電を利
用する各種点火装置が使用されていた。2. Description of the Related Art Conventionally, as a glow plug and various heaters for ignition and heating used for accelerating the starting of a diesel engine, a heat resistant insulating powder is filled in a sheath made of a heat resistant metal, and nickel (Ni) is contained in the heat resistant insulating powder. ) -Chromium (Cr) or the like, a sheathed heater in which a heating resistor made of a high melting point metal wire is embedded, and various ignition devices utilizing high-voltage spark discharge have been used.
【０００３】しかしながら、前記シーズヒーターは、耐
熱金属製のシース内に充填された耐熱絶縁粉末を介して
発熱抵抗体の熱を伝えるため、短時間の急速昇温が困難
であり、その上、耐摩耗性や耐久性に劣るという問題が
ある他、前記火花放電を利用した各種点火装置も、点火
時に雑音等の電波障害を生じたり、確実な点火と未着火
の場合の安全性という点からの信頼性に欠ける等の欠点
があった。However, since the sheathed heater transfers the heat of the heat-generating resistor through the heat-resistant insulating powder filled in the sheath made of heat-resistant metal, it is difficult to rapidly raise the temperature in a short time. In addition to the problem of inferior wear and durability, various ignition devices using the spark discharge also cause radio interference such as noise at the time of ignition, or in terms of safety in the case of reliable ignition and non-ignition. There were drawbacks such as lack of reliability.
【０００４】そこで、短時間の急速昇温が可能で、電波
障害が発生せず、しかも確実に点火して安全性を確保
し、耐摩耗性と耐久性に優れた信頼性の高い発熱体とし
て、無機導電材から成る発熱抵抗体をセラミック焼結体
中に埋設したセラミック発熱体が、内燃機関のグロープ
ラグをはじめ、各種加熱用ヒーターとして広く利用され
るようになってきた。Therefore, as a highly reliable heating element which is capable of rapid temperature rise for a short time, does not cause radio wave interference, and reliably ignites to ensure safety, has excellent wear resistance and durability. A ceramic heating element in which a heating resistor made of an inorganic conductive material is embedded in a ceramic sintered body has been widely used as a heater for various heating such as a glow plug of an internal combustion engine.
【０００５】とりわけ、内燃機関のグロープラグ用のセ
ラミック発熱体としては、例えば、図４に示すようにセ
ラミック焼結体１２中に、捲回した高融点金属の線材か
ら成る発熱抵抗体１３を埋設し、高温での耐久性能を向
上させることにより、急速昇温性能を高めるとともに発
熱温度を自己飽和するものや、図５に示すようにセラミ
ック焼結体１６中に、高融点金属の線材から成る発熱抵
抗体１７を埋設し、該発熱抵抗体１７より大きい正の抵
抗温度係数を有する線材から成る抵抗体１８を前記発熱
抵抗体１７に直列に接続し、通電して昇温する際の発熱
抵抗体１７の加熱電流を自己制御するもの等が提案され
ている（特公平１−５５３６９号公報参照）。Particularly, as a ceramic heating element for a glow plug of an internal combustion engine, for example, as shown in FIG. 4, a heating resistor 13 made of a wire material of a wound high melting point metal is embedded in a ceramic sintered body 12. However, by improving the durability performance at high temperature, the rapid temperature rising performance is enhanced and the heat generation temperature is self-saturated. As shown in FIG. 5, the ceramic sintered body 16 is made of a wire material of a high melting point metal. A heating resistor for embedding a heating resistor 17 and connecting a resistor 18 made of a wire having a positive temperature coefficient of resistance larger than that of the heating resistor 17 to the heating resistor 17 in series and heating the current by energizing the resistor. A device that self-controls the heating current of the body 17 has been proposed (see Japanese Patent Publication No. 1-55369).
【０００６】[0006]
【発明が解決しようとする課題】しかしながら、前記自
己飽和するセラミック発熱体では、例えば、１１Ｖの電
圧を６０秒間印加した場合には消費電力が６０Ｗ程度、
突入電流も１８Ａ程度と小さいものの、セラミック発熱
体の最高発熱部を先端から５ｍｍ未満とする先端発熱が
困難であり、また、１４Ｖの印加電圧で１３５０℃の発
熱温度に自己飽和させた場合には、セラミック発熱体の
円周方向の最大温度差が約６０℃とかなり大となる。However, in the self-saturating ceramic heating element, for example, when a voltage of 11 V is applied for 60 seconds, the power consumption is about 60 W,
Although the inrush current is as small as about 18 A, it is difficult to generate heat at the tip of the ceramic heating element within 5 mm from the tip, and when it is self-saturated to a heating temperature of 1350 ° C. with an applied voltage of 14 V, The maximum temperature difference in the circumferential direction of the ceramic heating element is about 60 ° C., which is considerably large.
【０００７】一方、前記自己制御するセラミック発熱体
では、例えば、１１Ｖの電圧を６０秒間印加した時の消
費電力が９０〜１００Ｗ、突入電流も２２Ａ程度とかな
り大きくなり、通電制御装置を必要とするとともに、加
熱電流を自己制御する前記線材から成る抵抗体１８が、
通電加熱の断続的稼働により抵抗変化を生じる等、耐久
性の劣化を招き易く、その上、複雑な構造となってコス
ト高となる。On the other hand, in the self-controlled ceramic heating element, for example, when a voltage of 11 V is applied for 60 seconds, the power consumption is 90 to 100 W and the inrush current is about 22 A, which is considerably large, and a conduction controller is required. At the same time, the resistor 18 made of the wire for self-controlling the heating current,
The durability is apt to be deteriorated such as a resistance change caused by intermittent operation of electric heating, and a complicated structure results in high cost.
【０００８】また、電極取り出し部１４及び１９が、い
ずれも埋設した金属線材から成るリード部１５及び２０
を焼結一体化後、研削して表面に露出させたものである
ことから、熱膨張差によりセラミック焼結体と露出した
金属線材から成るリード部１５及び２０との境界に隙間
を生じ、該隙間から酸素や水分等の侵入により、稼働中
にセラミック焼結体１２にクラックが発生する恐れがあ
る等、種々の課題があった。Further, the electrode lead-out portions 14 and 19 are both lead portions 15 and 20 made of a buried metal wire.
Since these are exposed to the surface after being sintered and integrated, a gap is created at the boundary between the ceramic sintered body and the exposed lead portions 15 and 20 made of the metal wire due to the difference in thermal expansion. There are various problems such as cracks may be generated in the ceramic sintered body 12 during operation due to intrusion of oxygen, water, etc. from the gap.
【０００９】[0009]
【発明の目的】本発明は前記欠点に鑑み開発されたもの
で、その目的は、消費電力が小さく、先端から５ｍｍ未
満の位置を最高発熱部とする先端発熱が可能で、かつ発
熱温度の飽和時におけるセラミック発熱体の円周方向の
最大温度差が極めて小さく、高温での絶縁抵抗の劣化を
防止した長時間の連続稼動が可能で、複雑な構造を必要
とせず、耐久性に優れたセラミック発熱体を提供するこ
とにある。SUMMARY OF THE INVENTION The present invention has been developed in view of the above-mentioned drawbacks, and it is an object of the present invention that power consumption is small, tip heat generation is possible with a position of less than 5 mm from the tip as the maximum heat generation portion, and heat generation temperature is saturated. The maximum temperature difference in the circumferential direction of the ceramic heating element is extremely small, and continuous operation is possible for a long time while preventing deterioration of insulation resistance at high temperatures. Ceramics with excellent durability without requiring a complicated structure. To provide a heating element.
【００１０】[0010]
【課題を解決するための手段】本発明のセラミック発熱
体は、電気絶縁性セラミック焼結体中に、スクリーン印
刷方法等で形成した平行な独立した少なくとも２層の無
機導電材から成る発熱抵抗体層と、該発熱抵抗体層に接
続した高融点金属の線材等から成るリード部と、該リー
ド部に接続するスクリーン印刷方法等で形成した無機導
電材から成る層状の電極取り出し部を１層以上、それぞ
れ電気絶縁性セラミック焼結体中に埋設して一体化した
ことを特徴とするものである。The ceramic heating element of the present invention is a heating resistor made of at least two parallel and independent inorganic conductive materials formed by a screen printing method in an electrically insulating ceramic sintered body. One or more layers, a lead portion formed of a wire of a refractory metal or the like connected to the heating resistor layer, and a layered electrode lead portion formed of an inorganic conductive material formed by a screen printing method or the like connected to the lead portion Each of them is characterized by being embedded and integrated in an electrically insulating ceramic sintered body.
【００１１】[0011]
【作用】本発明のセラミック発熱体によれば、埋設した
無機導電材から成る発熱抵抗体をスクリーン印刷方法等
で層状に形成することから、セラミック発熱体の先端部
を集中加熱することが可能となり、かつ発熱部の容積が
小さいことから消費電力が小さくなる。According to the ceramic heating element of the present invention, since the heating resistor made of the embedded inorganic conductive material is formed in layers by the screen printing method or the like, it becomes possible to intensively heat the tip of the ceramic heating element. Moreover, since the volume of the heat generating portion is small, the power consumption is small.
【００１２】また、前記無機導電材から成る発熱抵抗体
を略平行な独立した少なくとも２層とすることにより、
発熱温度の飽和時におけるセラミック発熱体の円周方向
の最大温度差が小さくなり、かつ急速昇温特性が向上す
るとともに、発熱抵抗体層の厚さを薄くすることがで
き、該発熱抵抗体層を形成する時にクラック等の不都合
が発生しないようになる。Further, by forming the heating resistor made of the inorganic conductive material into at least two independent layers which are substantially parallel to each other,
The maximum temperature difference in the circumferential direction of the ceramic heating element when the heating temperature is saturated is reduced, the rapid temperature rising characteristics are improved, and the thickness of the heating resistor layer can be reduced. Inconveniences such as cracks will not occur when forming the.
【００１３】更に、リード部を高融点金属の線材等で構
成することから導通抵抗が低く、余分な発熱を生ぜず、
かつ該リード部に接続する電極取り出し部を、スクリー
ン印刷方法等で形成した１層以上の無機導電材から成る
層状とするとともに複数個に分割して設けることによ
り、セラミック焼結体との熱膨張差が小さくなって隙間
を生じることがなく、酸素や水分等の侵入がなく、長時
間の連続稼動における電極取り出し部の耐久性及び信頼
性が向上することになる。Furthermore, since the lead portion is made of a wire material of a high melting point metal, the conduction resistance is low and no extra heat is generated.
Further, the electrode lead-out portion connected to the lead portion is formed into a layer made of one or more layers of inorganic conductive material formed by a screen printing method or the like, and is divided into a plurality of portions to provide thermal expansion with the ceramic sintered body. The difference will be small and no gap will be created, oxygen and moisture will not enter, and the durability and reliability of the electrode lead-out portion in continuous operation for a long time will be improved.
【００１４】[0014]
【実施例】以下、本発明のセラミック発熱体の一実施例
を図面に基づき説明する。図１は本発明のセラミック発
熱体を示す斜視図であり、図２は図１のセラミック発熱
体の側面図である。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the ceramic heating element of the present invention will be described below with reference to the drawings. 1 is a perspective view showing a ceramic heating element of the present invention, and FIG. 2 is a side view of the ceramic heating element of FIG.
【００１５】図１及び図２において、１は電気絶縁性の
セラミック焼結体２中に、略平行な独立した２層の無機
導電材から成る発熱抵抗体層３、４と、発熱抵抗体層
３、４の各端部に接続した高融点金属の線材から成るリ
ード部５、６と、リード部５、６にそれぞれ接続した無
機導電材から成る２層を成し複数個に分割した電極取り
出し部７、８を埋設し、電極取り出し部７、８の一部が
セラミック焼結体２の外周面に露出するとともに、発熱
抵抗体層３、４側のセラミック焼結体２の先端が略球面
で、少なくとも発熱抵抗体層３、４を埋設したセラミッ
ク焼結体２の断面が円形を成すセラミック発熱体であ
る。In FIGS. 1 and 2, reference numeral 1 is a ceramic sintered body 2 having an electric insulation property, and heating resistor layers 3 and 4 made of two substantially parallel and independent inorganic conductive materials, and a heating resistor layer. Electrodes taken out into a plurality of layers, each of which is made up of two layers made of a refractory metal wire connected to each end of Nos. 3 and 4 and an inorganic conductive material connected to each of the leads 5 and 6. The portions 7 and 8 are buried, part of the electrode lead-out portions 7 and 8 is exposed on the outer peripheral surface of the ceramic sintered body 2, and the tip of the ceramic sintered body 2 on the side of the heating resistor layers 3 and 4 is substantially spherical. The ceramic sintered body 2 in which at least the heating resistor layers 3 and 4 are embedded has a circular cross section.
【００１６】尚、電気絶縁性のセラミック焼結体２とし
ては、高温での耐酸化性や強度に優れた窒化珪素（Ｓｉ
3 Ｎ4 ）を主成分とする焼結体が好適である。As the electrically insulating ceramic sintered body 2, silicon nitride (Si) which is excellent in oxidation resistance and strength at high temperature is used.
A sintered body containing 3 N 4 ) as a main component is suitable.
【００１７】また、無機導電材から成る発熱抵抗体層
３、４あるいは層状の電極取り出し部７、８等の主成分
は、タングステン（Ｗ）、モリブデン（Ｍｏ）、レニウ
ム（Ｒｅ）等の高融点金属やその合金の他、例えばタン
グステンカーバイド（ＷＣ）、窒化チタン（ＴｉＮ）や
硼化ジルコニウム（ＺｒＢ2 ）等の第４ａ族、第５ａ
族、第６ａ族の炭化物または窒化物等があり、とりわけ
タングステンカーバイド（ＷＣ）が好ましい。The main components of the heating resistor layers 3 and 4 made of an inorganic conductive material or the layered electrode lead-out portions 7 and 8 are high melting points of tungsten (W), molybdenum (Mo), rhenium (Re) and the like. In addition to metals and their alloys, for example, tungsten carbide (WC), titanium nitride (TiN), zirconium boride (ZrB 2 ), etc., group 4a, group 5a
There are carbides and nitrides of Group 6a and Group 6a, and tungsten carbide (WC) is particularly preferable.
【００１８】更に、電気絶縁性のセラミック焼結体２
が、窒化珪素（Ｓｉ3 Ｎ4 ）を主成分とする焼結体の場
合には、発熱抵抗体層３、４あるいは電極取り出し部
７、８等はタングステンカーバイド（ＷＣ）を主成分と
し、セラミック焼結体２の主成分である窒化珪素（Ｓｉ
3 Ｎ4 ）粉末を添加混合したものが好適である。Furthermore, an electrically insulating ceramic sintered body 2
However, in the case of a sintered body containing silicon nitride (Si 3 N 4 ) as a main component, the heating resistor layers 3, 4 or the electrode lead-out portions 7, 8 etc. contain tungsten carbide (WC) as a main component and are made of ceramics. The main component of the sintered body 2 is silicon nitride (Si
It is preferable to add and mix 3 N 4 ) powder.
【００１９】前記無機導電材から成る発熱抵抗体層３、
４は、熱膨張率の点から炭化タングステン（ＷＣ）が６
５〜９５重量％、窒化珪素（Ｓｉ3 Ｎ4 ）が５〜３５重
量％の組成から成るものが良く、とりわけ炭化タングス
テン（ＷＣ）が７５〜９０重量％、窒化珪素（Ｓｉ3 Ｎ
4 ）が１０〜２５重量％の組成が好ましく、また、前記
発熱抵抗体層３、４の厚さは、発熱抵抗体層にクラック
等の不都合を発生しないようにするためには、少なくと
も最高発熱部で２．３〜１５０μm 、特に８〜５３μm
の範囲が望ましい。A heating resistor layer 3 made of the inorganic conductive material,
4 is 6 in terms of coefficient of thermal expansion, tungsten carbide (WC).
5-95% by weight, often those of silicon nitride (Si 3 N 4) is made of a composition of 5 to 35 wt%, especially tungsten carbide (WC) is 75 to 90 wt%, of silicon nitride (Si 3 N
4 ) is preferably 10 to 25% by weight, and the thickness of the heat generating resistor layers 3 and 4 is at least the maximum heat generation in order to prevent cracks and the like from occurring in the heat generating resistor layers. 2.3-150 μm, especially 8-53 μm
The range of is desirable.
【００２０】尚、電極取り出し部７、８の無機導電材の
導通抵抗は、発熱抵抗体層３、４より低いことが必要で
あり、電極取り出し部は１層以上の層状とすることが望
ましく、スルーホール等で電気的に接続するようにし、
発熱抵抗体層の層数より少なく形成しても良い。The conduction resistance of the inorganic conductive material in the electrode lead-out portions 7 and 8 must be lower than that of the heating resistor layers 3 and 4, and it is desirable that the electrode lead-out portion has a layered structure of one or more layers. Make electrical connections through through holes, etc.
You may form less than the number of layers of a heating resistor layer.
【００２１】一方、リード部５、６には、高融点金属で
あるタングステン（Ｗ）、モリブデン（Ｍｏ）、レニウ
ム（Ｒｅ）やその合金等が上げられるが、とりわけタン
グステン（Ｗ）が好適である。On the other hand, for the lead portions 5 and 6, high melting point metals such as tungsten (W), molybdenum (Mo), rhenium (Re) and alloys thereof can be used, but tungsten (W) is particularly preferable. .
【００２２】本発明のセラミック発熱体を評価するにあ
たり、先ず、高純度の窒化珪素（Ｓｉ3 Ｎ4 ）粉末に、
焼結助剤としてイットリア（Ｙ2 Ｏ3 ）や希土類元素の
酸化物を添加混合して調製した造粒体を使用し、プレス
成形法等、周知の成形法により図３に示すような平板状
の窒化珪素を主成分とするセラミック成形体９、１０、
１１を作製する。In evaluating the ceramic heating element of the present invention, first, a high-purity silicon nitride (Si 3 N 4 ) powder is added.
Using a granulated body prepared by adding and mixing yttria (Y 2 O 3 ) or an oxide of a rare earth element as a sintering aid, a flat plate shape as shown in FIG. 3 is formed by a known molding method such as a press molding method. Ceramic molded bodies 9, 10 containing silicon nitride as a main component,
11 is produced.
【００２３】次に、タングステンカーバイド（ＷＣ）と
窒化珪素（Ｓｉ3 Ｎ4 ）の各微粉末を用い、その配合量
を種々設定して混合した原料粉末に溶媒を加えてペース
トを調製し、スクリーン印刷法等により設計抵抗値に基
づいた各種寸法と厚さの略Ｕ字形状のパターンで、かつ
該パターンの先端がセラミック焼結体の先端より５ｍｍ
以内に位置するように、セラミック成形体９及び１０の
表面に発熱抵抗体層３及び４を形成する。Next, fine powders of tungsten carbide (WC) and silicon nitride (Si 3 N 4 ) were used, and the paste was prepared by adding a solvent to the raw material powders mixed in various amounts and mixing them to prepare a screen. It is a substantially U-shaped pattern having various dimensions and thicknesses based on the design resistance value by the printing method and the tip of the pattern is 5 mm from the tip of the ceramic sintered body.
The heat generating resistor layers 3 and 4 are formed on the surfaces of the ceramic molded bodies 9 and 10 so as to be located within.
【００２４】一方、電極取り出し部７及び８は、８５重
量％のタングステンカーバイド（ＷＣ）と１５重量％の
窒化珪素（Ｓｉ3 Ｎ4 ）の各微粉末から成るペーストを
使用して前記セラミック成形体９及び１０の発熱抵抗体
層３及び４と反対側の端部表面に、それぞれ前記同様に
して幅約０．７ｍｍ、厚さ約７０μm のパターンを４
個、セラミック成形体９及び１０の側面まで平行に所定
の配置で形成した。On the other hand, the electrode lead-out portions 7 and 8 are made of the above-mentioned ceramic compact by using a paste made of fine powder of 85 wt% tungsten carbide (WC) and 15 wt% silicon nitride (Si 3 N 4 ). On the surfaces of the end portions 9 and 10 opposite to the heating resistor layers 3 and 4, 4 patterns each having a width of about 0.7 mm and a thickness of about 70 μm are formed in the same manner as described above.
The ceramic molded bodies 9 and 10 were formed in parallel with each other in a predetermined arrangement.
【００２５】次に、発熱抵抗体層４と電極取り出し部８
を同一面上にそれぞれ印刷形成したセラミック成形体９
と、セラミック成形体１０の発熱抵抗体層と電極取り出
し部を印刷形成していない面との間に、リード部６とし
て直径０．２５ｍｍのタングステン（Ｗ）線を発熱抵抗
体層４と電極取り出し部８にそれぞれ接続するように挟
み込む。Next, the heating resistor layer 4 and the electrode lead-out portion 8
Formed ceramics 9 by printing on the same surface
Between the heating resistor layer and the surface of the ceramic molded body 10 on which the electrode lead-out portion is not formed by printing, a tungsten (W) wire having a diameter of 0.25 mm is used as the lead portion 6 and the heater resistor layer 4 and the electrode lead-out portion. The parts 8 are sandwiched so as to be connected to each other.
【００２６】次に、セラミック成形体１０のもう一方の
面上に形成した発熱抵抗体層３と電極取り出し部７にそ
れぞれ接続するように、リード部５として前記同様のタ
ングステン（Ｗ）線を、発熱抵抗体層と電極取り出し部
を印刷形成しないセラミック成形体１１で挟み込み、炭
素（Ｃ）を含む還元性の雰囲気下、１７５０℃の温度で
１時間、加圧焼成した。Next, the same tungsten (W) wire as the lead portion 5 is connected as the lead portion 5 so as to be connected to the heating resistor layer 3 formed on the other surface of the ceramic molded body 10 and the electrode lead-out portion 7, respectively. The heating resistor layer and the electrode lead-out portion were sandwiched between the ceramic molded bodies 11 which were not formed by printing, and pressure-fired at a temperature of 1750 ° C. for 1 hour in a reducing atmosphere containing carbon (C).
【００２７】かくして得られたセラミック焼結体の周囲
を研磨し、発熱抵抗体層側の先端を略球面とするととも
に断面円形に加工し、埋設した各電極取り出し部の端面
を円柱側面に露出させ、直径約３．５ｍｍのセラミック
発熱体を作製した。The periphery of the ceramic sintered body thus obtained was polished, and the end on the heating resistor layer side was made substantially spherical and processed to have a circular cross section, so that the end faces of the embedded electrode lead-out portions were exposed to the cylindrical side faces. A ceramic heating element having a diameter of about 3.5 mm was produced.
【００２８】かくして得られたセラミック発熱体を用い
て、少なくとも電極取り出し部の露出部にメタライズ法
やメッキ法等によりニッケル（Ｎｉ）等の金属被膜を形
成した後、セラミック発熱体の側面に露出した一方の電
極取り出し部と接続するように筒状金具を外嵌めし、還
元性の雰囲気中で銀ろうにて接合して負電極とし、他方
の電極取り出し部に、線材またはキャップ状の金具より
成る電極取り出し金具を前記同様に銀ろうにて接合して
正電極として接続し、正負の電極を導出した評価用のセ
ラミック発熱体を作製した。Using the ceramic heating element thus obtained, a metal coating such as nickel (Ni) was formed on at least the exposed portion of the electrode lead-out portion by a metallizing method or a plating method, and then exposed on the side surface of the ceramic heating element. A tubular metal fitting is fitted so as to connect to one of the electrode lead-out parts, joined with silver brazing in a reducing atmosphere to form a negative electrode, and the other electrode lead-out part consists of a wire rod or a cap-like metal fitting. Similar to the above, the electrode lead-out metal fittings were joined by silver brazing and connected as a positive electrode to produce a ceramic heating element for evaluation in which positive and negative electrodes were derived.
【００２９】次いで、前記評価用のセラミック発熱体を
使用し、前記発熱抵抗体層に１１Ｖの直流電圧を６０秒
間印加して１１５０℃まで急速昇温し、その時の消費電
力と突入電流を測定するとともに、通電してから８００
℃の温度に到達するまでの時間を求めた。Then, using the ceramic heating element for evaluation, a direct current voltage of 11 V is applied to the heating resistor layer for 60 seconds to rapidly raise the temperature to 1150 ° C., and the power consumption and inrush current at that time are measured. Together with energizing 800
The time required to reach the temperature of ° C was determined.
【００３０】一方、飽和して一定の温度に達した後、放
射温度計にて非接触で筒状金具から露出したセラミック
発熱体の先端からの表面温度分布を測定し、前記先端か
らの最高発熱部の距離を求めた。On the other hand, after reaching a certain temperature after being saturated, the surface temperature distribution from the tip of the ceramic heating element exposed from the tubular metal fitting is measured with a radiation thermometer in a non-contact manner, and the maximum heat generation from the tip is measured. The distance between the clubs was calculated.
【００３１】また、前記評価用のセラミック発熱体の円
周方向の温度差は、１４Ｖの直流電圧を印加して発熱温
度を１３５０℃に飽和させ、最高発熱部の周囲を放射温
度計にて非接触で温度分布を測定し、最大温度差を求め
た。Further, regarding the temperature difference in the circumferential direction of the ceramic heating element for evaluation, a direct-current voltage of 14 V is applied to saturate the heating temperature to 1350 ° C., and the circumference of the maximum heating portion is measured with a radiation thermometer. The temperature distribution was measured by contact, and the maximum temperature difference was obtained.
【００３２】更に、前記評価用のセラミック発熱体に１
４Ｖの直流電圧を２分間通電して１４００℃まで急速昇
温した後、通電を停止して２分間圧搾空気を吹きつけ強
制冷却する工程を１サイクルとする高負荷耐久試験を、
５００００サイクル実施し、試験前後で測定したセラミ
ック発熱体の抵抗値が、耐久試験後に２０％以上変化し
たものを不良と判定した。Further, the above ceramic heating element for evaluation has 1
A high load endurance test, in which one cycle consists of a step in which a DC voltage of 4 V is energized for 2 minutes to rapidly raise the temperature to 1400 ° C., the energization is stopped, and compressed air is blown for 2 minutes for forced cooling,
It was judged to be defective when the resistance value of the ceramic heating element measured before and after the test for 50,000 cycles changed by 20% or more after the durability test.
【００３３】尚、８０重量％のタングステンカーバイド
（ＷＣ）と２０重量％の窒化珪素（Ｓｉ3 Ｎ4 ）の組成
から成る発熱抵抗体を１層のみ形成し、電極取り出し部
を前記評価用のセラミック発熱体と同一組成で１層形成
してリード部とそれぞれ接続して作製したセラミック発
熱体を比較例とした。以上の結果を表１及び表２に示
す。It should be noted that only one heating resistor made of a composition of 80% by weight of tungsten carbide (WC) and 20% by weight of silicon nitride (Si 3 N 4 ) was formed, and the electrode lead-out portion was made of the ceramic for evaluation. A ceramic heating element produced by forming one layer with the same composition as that of the heating element and connecting each to the lead portion was used as a comparative example. The above results are shown in Tables 1 and 2.
【００３４】[0034]
【表１】 [Table 1]
【００３５】[0035]
【表２】 [Table 2]
【００３６】表１及び表２の結果より、比較例の試料番
号２６は、耐久試験結果は良いものの最高発熱部の円周
方向の温度差が６４℃と極めて大きく、急速昇温特性も
４．５秒と良くないのに対して、本発明品では最高発熱
部の円周方向の温度差は３５℃以下で、急速昇温特性も
４．３秒以下と優れていることが明らかとなった。From the results of Tables 1 and 2, the sample No. 26 of the comparative example has a good endurance test result, but the temperature difference in the circumferential direction of the highest heat generating portion is 64 ° C., and the rapid temperature rising characteristic is 4. In contrast to 5 seconds, which is not good, the temperature difference in the circumferential direction of the highest heat generating part is 35 ° C. or less, and the rapid temperature rising characteristic is 4.3 seconds or less. .
【００３７】[0037]
【発明の効果】叙上の如く、本発明のセラミック発熱体
は、埋設した無機導電材から成る発熱抵抗体層を独立し
た少なくとも２層に形成することから、セラミック発熱
体の先端から５ｍｍ未満の位置を集中加熱することが可
能となり、かつ発熱部の容積が小さいことから消費電力
も小さくなり、その上、発熱温度の飽和時におけるセラ
ミック発熱体の円周方向の最大温度差が極めて小さく、
急速昇温特性が向上するとともに、発熱抵抗体層の厚さ
を薄くすることができ、該発熱抵抗体層を焼成一体化す
る時の残留応力によるクラック等の発生も解消する。As described above, in the ceramic heating element of the present invention, at least two independent heating resistor layers made of an embedded inorganic conductive material are formed, so that the distance from the tip of the ceramic heating element is less than 5 mm. Since it is possible to centrally heat the position and the volume of the heat generating portion is small, the power consumption is also small, and furthermore, the maximum temperature difference in the circumferential direction of the ceramic heating element when the heating temperature is saturated is extremely small,
The rapid temperature rise characteristics are improved, the thickness of the heating resistor layer can be reduced, and the occurrence of cracks and the like due to residual stress when the heating resistor layer is fired and integrated is eliminated.
【００３８】更に、リード部を高融点金属で構成するこ
とから導通抵抗が低く、余分な発熱をせず、かつ該リー
ド部に接続する電極取り出し部を、発熱抵抗体層と同様
に無機導電材から成る層状とするとともに複数個に分割
して設けることにより、セラミック焼結体との熱膨張差
が小さくなって熱履歴を繰り返しても隙間を生じること
がなく、酸素や水分等の侵入もなく、電極取り出し部の
耐久性及び信頼性が向上する。Furthermore, since the lead portion is made of a refractory metal, the conduction resistance is low, no extra heat is generated, and the electrode lead-out portion connected to the lead portion is made of an inorganic conductive material like the heating resistor layer. It is made of a layered structure and is divided into a plurality of layers, so that the difference in thermal expansion from the ceramic sintered body is small and no gaps are created even if the thermal history is repeated, and oxygen and moisture do not enter. The durability and reliability of the electrode extraction portion are improved.
【００３９】以上の結果、長時間の連続稼動が可能で、
複雑な構造を必要としない耐久性に優れたセラミック発
熱体を得ることができる。As a result of the above, continuous operation for a long time is possible,
It is possible to obtain a ceramic heating element having excellent durability that does not require a complicated structure.
【図１】本発明のセラミック発熱体の一実施例を示す斜
視図である。FIG. 1 is a perspective view showing an embodiment of a ceramic heating element of the present invention.
【図２】図１のセラミック発熱体の側面図である。FIG. 2 is a side view of the ceramic heating element of FIG.
【図３】本発明のセラミック発熱体を製造する工程を説
明するための斜視図である。FIG. 3 is a perspective view for explaining a process of manufacturing the ceramic heating element of the present invention.
【図４】従来の内燃機関のグロープラグに適用した自己
飽和型セラミック発熱体の要部を示す断面図である。FIG. 4 is a sectional view showing a main part of a self-saturation type ceramic heating element applied to a glow plug of a conventional internal combustion engine.
【図５】従来の内燃機関のグロープラグに適用した自己
制御型セラミック発熱体の要部を示す断面図である。FIG. 5 is a cross-sectional view showing a main part of a self-controlled ceramic heating element applied to a glow plug of a conventional internal combustion engine.
１ セラミック発熱体 ２ セラミック焼結体 ３、４ 発熱抵抗体層 ５、６ リード部 ７、８ 電極取り出し部 DESCRIPTION OF SYMBOLS 1 Ceramic heating element 2 Ceramic sintered body 3, 4 Heating resistor layer 5, 6 Lead part 7, 8 Electrode extraction part
Claims (1)
た少なくとも２層の無機導電材の発熱抵抗体層と、該発
熱抵抗体層に接続した高融点金属から成るリード部と、
該リード部に接続した無機導電材から成る層状の電極取
り出し部を埋設したことを特徴とするセラミック発熱
体。1. An electrically insulating ceramic sintered body, wherein at least two independent heat generating resistor layers made of an inorganic conductive material, and lead portions made of a high melting point metal and connected to the heat generating resistor layers are provided.
A ceramic heating element in which a layered electrode lead-out portion made of an inorganic conductive material connected to the lead portion is embedded.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16088494A JPH07139737A (en) | 1993-09-20 | 1994-07-13 | Ceramic heater |
| US08/305,085 US5750958A (en) | 1993-09-20 | 1994-09-13 | Ceramic glow plug |
| DE4433505A DE4433505C2 (en) | 1993-09-20 | 1994-09-20 | ceramic glow |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5-233075 | 1993-09-20 | ||
| JP23307593 | 1993-09-20 | ||
| JP16088494A JPH07139737A (en) | 1993-09-20 | 1994-07-13 | Ceramic heater |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH07139737A true JPH07139737A (en) | 1995-05-30 |
Family
ID=26487224
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16088494A Pending JPH07139737A (en) | 1993-09-20 | 1994-07-13 | Ceramic heater |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07139737A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001267046A (en) * | 2000-03-16 | 2001-09-28 | Ibiden Co Ltd | Ceramic heater |
| JPWO2005117492A1 (en) * | 2004-05-27 | 2008-04-03 | 京セラ株式会社 | Ceramic heater and glow plug using the same |
-
1994
- 1994-07-13 JP JP16088494A patent/JPH07139737A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001267046A (en) * | 2000-03-16 | 2001-09-28 | Ibiden Co Ltd | Ceramic heater |
| JPWO2005117492A1 (en) * | 2004-05-27 | 2008-04-03 | 京セラ株式会社 | Ceramic heater and glow plug using the same |
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