JP2003240240A - Glow plug - Google Patents
Glow plugInfo
- Publication number
- JP2003240240A JP2003240240A JP2002037871A JP2002037871A JP2003240240A JP 2003240240 A JP2003240240 A JP 2003240240A JP 2002037871 A JP2002037871 A JP 2002037871A JP 2002037871 A JP2002037871 A JP 2002037871A JP 2003240240 A JP2003240240 A JP 2003240240A
- Authority
- JP
- Japan
- Prior art keywords
- heating element
- support
- glow plug
- ceramic
- heater
- 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.)
- Granted
Links
Classifications
-
- 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
-
- 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
- H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
- H05B2203/027—Heaters specially adapted for glow plug igniters
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、ディーゼルエンジ
ンの燃焼室内を予熱して燃料の着火および燃焼を促進す
るためのグロープラグに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glow plug for preheating a combustion chamber of a diesel engine to promote ignition and combustion of fuel.
【０００２】[0002]
【従来の技術】特許第３１６０２２６号公報に記載のセ
ラミックヒータは、通電により発熱するセラミック製の
発熱体をセラミック製の基体（以下、支持体という）に
埋設している。そして、支持体の材料として、セラミッ
ク成分に例えば金属珪化物を１〜３重量％添加したもの
を用いることにより、発熱体と支持体の線膨張係数の差
を縮小して、耐熱性を向上させるようにしている。2. Description of the Related Art In a ceramic heater disclosed in Japanese Patent No. 3160226, a heating element made of ceramic that generates heat when energized is embedded in a ceramic base (hereinafter referred to as a support). Then, by using, as a material of the support, a ceramic component to which, for example, 1 to 3% by weight of metal silicide is added, the difference in linear expansion coefficient between the heating element and the support is reduced, and heat resistance is improved. I am trying.
【０００３】また、特開２００１−１７６６４７号公報
に記載のセラミックヒータは、通電により発熱するセラ
ミック製の発熱体をセラミック製の基体（以下、支持体
という）に埋設している。そして、発熱体の先端部と支
持体の先端部との間の最短長さをＬ、支持体の外径をＤ
としたとき、０．１１≦Ｌ／Ｄ≦０．３５、とすること
により、速熱性と耐熱性の両立を図るようにしている。Further, in the ceramic heater described in Japanese Unexamined Patent Publication No. 2001-176647, a heating element made of ceramic which generates heat when energized is embedded in a ceramic base (hereinafter referred to as a support). The shortest length between the tip of the heating element and the tip of the support is L, and the outer diameter of the support is D.
In this case, by satisfying 0.11 ≦ L / D ≦ 0.35, both rapid heat resistance and heat resistance are achieved.
【０００４】[0004]
【発明が解決しようとする課題】ところで、近年、ディ
ーゼルエンジンのグロープラグにおいては、速熱性と耐
熱性（熱衝撃性）のさらなる向上が望まれている。By the way, in recent years, further improvement in rapid heat resistance and heat resistance (thermal shock resistance) has been desired in glow plugs of diesel engines.
【０００５】ここで、抵抗温度係数が小さい発熱体はそ
の昇温速度が低いため、速熱性を向上させるには抵抗温
度係数の大きな発熱体を用いることが有効である。しか
し、抵抗温度係数の大きな発熱体を用いた場合、発熱体
と支持体の温度差が大きくなり、熱衝撃によって割れが
発生しやすくなる傾向となる。Here, since a heating element having a small resistance temperature coefficient has a low temperature rising rate, it is effective to use a heating element having a large resistance temperature coefficient in order to improve the rapid heating property. However, when a heating element having a large temperature coefficient of resistance is used, the temperature difference between the heating element and the support becomes large, and cracking tends to occur due to thermal shock.
【０００６】すなわち、グロープラグのように燃料によ
ってヒータが冷却される使用環境では、発熱体は温度低
下してもその抵抗値が大きく低下して投入電流が大きく
増加するため、発熱体の温度低下は少なく、従って燃料
によって直接冷却される支持体との温度差が大きくな
り、割れが発生しやすくなる。That is, in a use environment in which the heater is cooled by the fuel, such as a glow plug, even if the temperature of the heating element is lowered, the resistance value of the heating element is greatly reduced and the input current is greatly increased, so that the temperature of the heating element is lowered. Therefore, the temperature difference from the support directly cooled by the fuel becomes large, and cracks are likely to occur.
【０００７】そして、前者の公報に記載のセラミックヒ
ータは、発熱体と支持体の線膨張係数の差が十分縮小さ
れていないため、熱衝撃によって割れが発生するという
問題があり、特に、抵抗温度係数の大きな発熱体を用い
た場合にその問題が顕著になる。The ceramic heater described in the former publication has a problem that cracking occurs due to thermal shock because the difference in linear expansion coefficient between the heating element and the support is not sufficiently reduced. The problem becomes remarkable when a heating element having a large coefficient is used.
【０００８】一方、後者の公報に記載のセラミックヒー
タは、上記のＬ／Ｄが大きいため、換言すると発熱体の
先端部肉厚が厚いため、発熱体と支持体の温度差が大き
くなり、熱衝撃によって割れが発生するという問題があ
り、特に、抵抗温度係数の大きな発熱体を用いた場合そ
の問題が顕著になる。On the other hand, in the ceramic heater described in the latter publication, the L / D is large, in other words, since the thickness of the tip of the heating element is large, the temperature difference between the heating element and the support becomes large, and There is a problem that cracking occurs due to impact, and especially when a heating element having a large temperature coefficient of resistance is used, the problem becomes remarkable.
【０００９】本発明は上記の点に鑑みてなされたもの
で、セラミック製ヒータによりエンジンの燃焼室を予熱
するグロープラグにおいて、速熱性と耐熱性を向上させ
ることを目的とする。The present invention has been made in view of the above points, and it is an object of the present invention to improve fast heat resistance and heat resistance in a glow plug for preheating a combustion chamber of an engine with a heater made of ceramics.
【００１０】[0010]
【課題を解決するための手段】上記目的を達成するた
め、請求項１に記載の発明では、通電により発熱するセ
ラミック製の発熱体（３３）がセラミック製の支持体
（３５）に埋設されたヒータ（３０）を備え、ヒータ
（３０）によりエンジンの燃焼室を予熱するグロープラ
グにおいて、発熱体（３３）の１２００℃時の抵抗値を
Ｒ１、発熱体（３３）の２０℃時の抵抗値をＲ２とした
とき、Ｒ１／Ｒ２≧２であり、支持体（３５）のセラミ
ックは、金属珪化物、金属炭化物、金属ホウ化物および
金属窒化物のうちの少なくとも１つ以上を４〜２２重量
％含み、かつ支持体（３５）の線膨張係数が発熱体（３
３）の線膨張係数よりも小さいことを特徴とする。In order to achieve the above-mentioned object, in the invention described in claim 1, a heating element (33) made of ceramic, which generates heat when energized, is embedded in a supporting body (35) made of ceramic. In a glow plug that includes a heater (30) and preheats the combustion chamber of the engine by the heater (30), the resistance value of the heating element (33) at 1200 ° C. is R1, and the resistance value of the heating element (33) at 20 ° C. Is R1 / R2 ≧ 2, and the ceramic of the support (35) contains 4 to 22% by weight of at least one of metal silicide, metal carbide, metal boride and metal nitride. In addition, the linear expansion coefficient of the support (35) includes the heating element (3
It is characterized by being smaller than the linear expansion coefficient of 3).
【００１１】これによると、Ｒ１／Ｒ２≧２とした抵抗
温度係数の大きな発熱体を用いることにより速熱性を向
上させることができ、また、支持体の線膨張係数を発熱
体の線膨張係数よりも小さくすることにより、抵抗温度
係数の大きな発熱体を用いた場合でも熱衝撃による割れ
を防止することができる。According to this, the rapid heating property can be improved by using a heating element having a large resistance temperature coefficient satisfying R1 / R2 ≧ 2, and the linear expansion coefficient of the support is set to be larger than that of the heating element. Also, by making it small, cracking due to thermal shock can be prevented even when a heating element having a large temperature coefficient of resistance is used.
【００１２】さらに、支持体のセラミックに、金属珪化
物、金属炭化物、金属ホウ化物および金属窒化物のうち
の少なくとも１つ以上を４〜２２重量％含ませることに
より、支持体の線膨張係数を発熱体の線膨張係数に近づ
けることができ、抵抗温度係数の大きな発熱体を用いた
場合でも熱衝撃による割れを確実に防止することができ
る。Further, the coefficient of linear expansion of the support is increased by incorporating 4-22% by weight of at least one of metal silicide, metal carbide, metal boride and metal nitride in the ceramic of the support. It is possible to approach the linear expansion coefficient of the heating element, and even when a heating element having a large resistance temperature coefficient is used, cracking due to thermal shock can be reliably prevented.
【００１３】特に、請求項４に記載の発明のように、炭
化タングステンを主成分とし窒化珪素を含有させたセラ
ミックにて形成された発熱体と組み合わせた場合に、支
持体の線膨張係数と発熱体の線膨張係数との差が十分小
さくなり、熱衝撃による割れを一層確実に防止すること
ができる。In particular, when a heating element formed of a ceramic containing tungsten carbide as a main component and containing silicon nitride is combined with the heating element, the linear expansion coefficient of the support and the heat generation are increased. The difference from the linear expansion coefficient of the body becomes sufficiently small, and cracking due to thermal shock can be prevented more reliably.
【００１４】請求項２に記載の発明では、発熱体（３
３）における燃焼室側の先端部と支持体（３５）におけ
る燃焼室側の先端部との間の最短長さをＬ、支持体（３
５）の外径をＤとしたとき、０．０１≦Ｌ／Ｄ≦０．
１、であることを特徴とする。According to the second aspect of the invention, the heating element (3
3), the shortest length between the tip of the combustion chamber side of the support (35) and the tip of the support (35) on the combustion chamber side is L.
When the outer diameter of 5) is D, 0.01 ≦ L / D ≦ 0.
It is characterized by 1.
【００１５】ここで、最短長さＬすなわち発熱体の先端
部肉厚が薄すぎると強度不足により割れが発生し、発熱
体の先端部肉厚が厚すぎると発熱体と支持体の温度差が
大きくなり割れが発生する。そして、上記のＬ／Ｄの範
囲は、本発明者が実験検討により見出したものであり、
これによると、強度不足による割れ、および発熱体と支
持体の温度差による割れを、防止することができる。Here, if the shortest length L, that is, the thickness of the tip of the heating element is too thin, cracking occurs due to insufficient strength, and if the thickness of the tip of the heating element is too thick, the temperature difference between the heating element and the support is large. It becomes large and cracks occur. Then, the above L / D range is found by the present inventor through experimental examination,
According to this, cracking due to insufficient strength and cracking due to a temperature difference between the heating element and the support can be prevented.
【００１６】請求項３に記載の発明のように、窒化珪素
を主成分とし、珪化モリブデンを含有するセラミックに
て支持体を形成することができる。According to the third aspect of the invention, the support can be formed of a ceramic containing silicon nitride as a main component and molybdenum silicide.
【００１７】なお、上記各手段の括弧内の符号は、後述
する実施形態に記載の具体的手段との対応関係を示す一
例である。The reference numerals in parentheses of the above-mentioned means are examples showing the correspondence with the concrete means described in the embodiments described later.
【００１８】[0018]
【発明の実施の形態】以下、本発明を図に示す実施形態
について説明する。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention shown in the drawings will be described.
【００１９】図１は本発明の一実施形態に係るグロープ
ラグＧ１の全体構成を示す断面図であり、このグロープ
ラグＧ１は、例えば、図示しない自動車の直噴式ディー
ゼルエンジンにおけるシリンダヘッドに取り付けられ、
エンジンの燃焼室内を予熱してエンジン始動時ないしは
始動後における燃料の着火および燃焼を促進するものと
して適用される。FIG. 1 is a sectional view showing the overall structure of a glow plug G1 according to an embodiment of the present invention. The glow plug G1 is attached to, for example, a cylinder head of a direct injection diesel engine of an automobile (not shown),
It is applied to preheat the combustion chamber of the engine to promote ignition and combustion of fuel at the time of starting the engine or after starting the engine.
【００２０】エンジンに取付可能な筒状のハウジング１
０は、鉄系材料等の導電性材料からなり、このハウジン
グ１０の一端１１と他端１２の間における外周面には、
取付ネジ部１３およびネジ締め用のナット部１４が形成
されている。A cylindrical housing 1 attachable to an engine
0 is made of a conductive material such as an iron-based material, and the outer peripheral surface between one end 11 and the other end 12 of the housing 10 is
A mounting screw portion 13 and a nut portion 14 for tightening the screw are formed.
【００２１】そして、グロープラグＧ１は、シリンダヘ
ッドの穴部に形成された雌ネジ部（図示せず）に取付ネ
ジ部１３が螺合されてシリンダヘッドに固定される。そ
れにより、後述するヒータ３０の先端側が燃焼室に露出
するようになっている。The glow plug G1 is fixed to the cylinder head by screwing a mounting screw portion 13 into a female screw portion (not shown) formed in the hole of the cylinder head. As a result, the tip end side of the heater 30 described below is exposed to the combustion chamber.
【００２２】ハウジング１０の内孔には、ステンレス等
の耐熱・耐食性金属よりなる段付き円筒状のスリーブ２
０が収納されている。このスリーブ２０は、その一端２
１側がハウジング１０の一端１１から突出した状態で他
端２２側がハウジング１０に挿入され、圧入や挿入部の
ロウ付け等により、スリーブ２０はハウジング１０に保
持されている。In the inner hole of the housing 10, a stepped cylindrical sleeve 2 made of heat resistant and corrosion resistant metal such as stainless steel is used.
0 is stored. This sleeve 20 has one end 2
The other end 22 side is inserted into the housing 10 with one side protruding from the one end 11 of the housing 10, and the sleeve 20 is held in the housing 10 by press fitting or brazing of the insertion portion.
【００２３】このスリーブ２０の内孔には、通電により
発熱するセラミック製棒状のヒータ３０が収納されてい
る。ヒータ３０は、その一端３１側がスリーブ２０の一
端２１から突出し、且つ他端３２側がスリーブ２０の他
端２２から突出した状態で、スリーブ２０に挿入されて
いる。ここで、ヒータ３０は、挿入部のロウ付け等によ
りスリーブ２０に固定されて保持されている。A ceramic rod-shaped heater 30 that generates heat when energized is housed in the inner hole of the sleeve 20. The heater 30 is inserted into the sleeve 20 with one end 31 side thereof protruding from one end 21 of the sleeve 20 and the other end 32 side thereof protruding from the other end 22 of the sleeve 20. Here, the heater 30 is fixed and held to the sleeve 20 by brazing the insertion portion or the like.
【００２４】このヒータ３０は、通電により発熱する導
電性セラミック製のＵ字状の発熱体３３と、この発熱体
３３に電気的に接続され発熱体３３の通電を行うための
タングステン等よりなる一対のリード線３４と、発熱体
３３およびリード線３４が埋設された絶縁性セラミック
製の支持体３５とから構成されている。The heater 30 is composed of a U-shaped heating element 33 made of a conductive ceramic which generates heat when energized and a pair of tungsten or the like which is electrically connected to the heating element 33 for energizing the heating element 33. 2 and a support 35 made of an insulating ceramic in which the heating element 33 and the lead 34 are embedded.
【００２５】また、ハウジング１０の内孔のうちハウジ
ング１０の他端１２側には、切削および冷間鍛造により
加工された炭素鋼よりなる棒状の中軸４０が収納されて
いる。この中軸４０の一端４１側には、ステンレス等の
導電性金属よりなる段付き円筒状のキャップ５０が嵌合
されている。A rod-shaped middle shaft 40 made of carbon steel machined by cutting and cold forging is housed in the inner hole of the housing 10 on the other end 12 side of the housing 10. A stepped cylindrical cap 50 made of a conductive metal such as stainless steel is fitted to one end 41 side of the center shaft 40.
【００２６】そして、ヒータ３０の一方のリード線３４
は、支持体３５から露出した部分にてキャップ５０にロ
ウ付け等によって接続されることにより、中軸４０に電
気的に接続されている。他方のリード線３４は、支持体
３５から露出した部分にてスリーブ２０にロウ付け等に
よって接続されることにより、スリーブ２０を介してハ
ウジング１０にアースされている。Then, one lead wire 34 of the heater 30
Is electrically connected to the center shaft 40 by being connected to the cap 50 at a portion exposed from the support 35 by brazing or the like. The other lead wire 34 is grounded to the housing 10 via the sleeve 20 by being connected to the sleeve 20 by brazing or the like at the portion exposed from the support body 35.
【００２７】また、中軸４０の他端４２側は、ハウジン
グ１０の他端１２から突出しており、この突出部には、
電源（図示せず）と電気的に接続された外部配線部材
（図示せず）がネジ結合される端子ネジ部４３が形成さ
れている。さらに、端子ネジ部４３には環状の絶縁ブッ
シュ４４よびナット４５が装着されている。中軸４０の
他端４２側とハウジング１０の内孔との間には、中軸４
０の保持・固定及び芯出しを行うための環状の絶縁性の
溶着ガラス６０が介在している。The other end 42 side of the center shaft 40 projects from the other end 12 of the housing 10.
A terminal screw portion 43 is formed to which an external wiring member (not shown) electrically connected to a power source (not shown) is screwed. Further, an annular insulating bush 44 and a nut 45 are attached to the terminal screw portion 43. Between the other end 42 side of the center shaft 40 and the inner hole of the housing 10, the center shaft 4
An annular insulating welded glass 60 for holding, fixing and centering 0 is interposed.
【００２８】上記構成になるグロープラグＧ１は、シリ
ンダヘッドに取り付けられ、端子ネジ部４３に上記した
外部配線部材が組み付けられることにより、ハウジング
１０およびシリンダヘッドをアース側として、電源から
外部配線部材および中軸４０を介してヒータ３０へ通電
可能となる。The glow plug G1 having the above structure is attached to the cylinder head, and the above-mentioned external wiring member is assembled to the terminal screw portion 43, so that the housing 10 and the cylinder head are on the ground side, and the external wiring member is connected from the power source. The heater 30 can be energized via the center shaft 40.
【００２９】次に、上記構成になるグロープラグＧ１に
ついて、本発明者が行った各種試験の結果を説明する。Next, the results of various tests conducted by the inventor of the glow plug G1 having the above structure will be described.
【００３０】まず、発熱体３３の抵抗変化率αを種々変
えたものを用意し、それらについて、エンジン始動性
（速熱性）を評価した。因みに、本明細書でいう抵抗変
化率αは、発熱体３３の１２００℃時の抵抗値をＲ１、
発熱体３３の２０℃時の抵抗値をＲ２としたとき、α＝
Ｒ１／Ｒ２である。First, various heating elements 33 having different resistance change rates α were prepared, and the engine startability (rapid heating property) of each of them was evaluated. Incidentally, the resistance change rate α in the present specification is the resistance value of the heating element 33 at 1200 ° C.
When the resistance value of the heating element 33 at 20 ° C. is R2, α =
R1 / R2.
【００３１】図２は、試験に供したグロープラグの抵抗
変化率αおよび評価結果を示すもので、抵抗変化率αが
１．５または１．８のグロープラグは、ヒータ３０の昇
温速度が低いためエンジン始動性が悪く、抵抗変化率α
が２．０以上のグロープラグは、ヒータ３０の昇温速度
が高いためエンジン始動性が良好で、特に抵抗変化率α
が３．０のグロープラグはエンジン始動性が極めて良好
であった。FIG. 2 shows the resistance change rate α of the glow plugs used in the test and the evaluation results. The glow plugs having a resistance change rate α of 1.5 or 1.8 have a heating rate of the heater 30. The engine startability is poor because it is low, and the resistance change rate α
A glow plug having a value of 2.0 or more has a high rate of temperature rise of the heater 30 and therefore has good engine startability, and particularly the resistance change rate α.
The glow plug of 3.0 had extremely good engine startability.
【００３２】また、ヒータ３０が発熱している際に燃料
によってヒータ３０が冷却されるため、発熱体３３の温
度よりも支持体３５の温度が低くなり、抵抗変化率αが
大きいグロープラグほど発熱体３３と支持体３５の温度
差が大きくなる傾向であった。Further, since the heater 30 is cooled by the fuel while the heater 30 is generating heat, the temperature of the support body 35 becomes lower than the temperature of the heat generating body 33, and the glow plug having a larger resistance change rate α generates heat. The temperature difference between the body 33 and the support 35 tended to increase.
【００３３】そして、発熱体３３と支持体３５の温度差
が大きくなると、熱衝撃によって割れが発生しやすくな
るため、次に、抵抗変化率αが２．０以上のグロープラ
グについて、熱衝撃性を向上させるための検討を行っ
た。When the temperature difference between the heating element 33 and the support 35 becomes large, cracking is likely to occur due to thermal shock. Next, the thermal shock resistance of the glow plug having a resistance change rate α of 2.0 or more is measured. We conducted a study to improve
【００３４】この検討に用いたグロープラグの発熱体３
３のセラミックは、炭化タングステンを主成分とし窒化
珪素を含有させたもので、具体的には、Ｓｉ3Ｎ4−７５
ｗｔ％ＷＣである。なお、この発熱体３３の線膨張係数
は、３．８×１０-6／℃である。Glow plug heating element 3 used in this study
The ceramic of No. 3 contains tungsten carbide as a main component and contains silicon nitride. Specifically, Si 3 N 4 -75 is used.
wt% WC. The linear expansion coefficient of the heating element 33 is 3.8 × 10 −6 / ° C.
【００３５】また、支持体３５のセラミックは、窒化珪
素を主成分とし、導電材としての金属珪化物、具体的に
は珪化モリブデンを含有させたもので、その珪化モリブ
デンの含有量を種々変えた試験品をそれぞれ４個用意
し、それらについて、熱衝撃性および通電耐久特性を評
価した。The ceramic of the support 35 is mainly composed of silicon nitride and contains a metal silicide as a conductive material, specifically molybdenum silicide, and the content of the molybdenum silicide is variously changed. Four test products were prepared, and the thermal shock resistance and the electrical durability characteristics were evaluated for each of them.
【００３６】熱衝撃性は、１２００℃から２０℃に急冷
して評価した。通電耐久特性は、通電中のヒータ３０の
最高温度が１４００℃になるような条件、具体的には、
６分通電１分通電停止の条件で、それを１００００サイ
クル行って評価した。The thermal shock resistance was evaluated by quenching from 1200 ° C to 20 ° C. The energization durability characteristic is a condition under which the maximum temperature of the heater 30 during energization becomes 1400 ° C., specifically,
It was evaluated by conducting 10000 cycles under the condition that the current was supplied for 6 minutes and stopped for 1 minute.
【００３７】図３は、この試験に供したグロープラグ
の、支持体３５のセラミックの珪化モリブデン含有量、
支持体３５の線膨張係数、および評価結果を示すもの
で、支持体３５のセラミックの珪化モリブデン含有量が
３ｗｔ％のグロープラグは、熱衝撃性試験および通電耐
久試験のいずれにおいても、４個中１個に割れが発生し
た。この割れの発生原因は、支持体３５の線膨張係数は
発熱体３３の線膨張係数よりも小さいものの、支持体３
５と発熱体３３の線膨張係数の差が大きすぎるためであ
る。FIG. 3 shows the molybdenum silicide content of the ceramic of the support 35 of the glow plug used in this test.
The coefficient of linear expansion of the support 35 and the evaluation results are shown. The glow plug having a molybdenum silicide content of 3 wt% of the ceramic of the support 35 is 4 out of 4 in both the thermal shock resistance test and the current endurance test. One of them cracked. The cause of this cracking is that the linear expansion coefficient of the support 35 is smaller than the linear expansion coefficient of the heating element 33, but the support 3
This is because the difference between the linear expansion coefficients of No. 5 and the heating element 33 is too large.
【００３８】また、支持体３５のセラミックの珪化モリ
ブデン含有量が２３ｗｔ％のグロープラグは、その線膨
張係数は発熱体３３の線膨張係数と等しくなっている
が、熱衝撃性試験において４個全てに割れが発生し、通
電耐久試験において４個中２個に割れが発生した。Further, the glow plug having a ceramic molybdenum silicide content of 23 wt% as the support 35 has a linear expansion coefficient equal to that of the heating element 33, but in the thermal shock test, all four plugs are used. Cracks occurred, and in the current-carrying durability test, 2 out of 4 cracks occurred.
【００３９】一方、支持体３５のセラミックの珪化モリ
ブデン含有量が、４ｗｔ％、１０ｗｔ％、１５ｗｔ％、
２０ｗｔ％、または２２ｗｔ％の各グロープラグでは、
熱衝撃性試験および通電耐久試験のいずれにおいても、
割れは全く発生しなかった。On the other hand, the molybdenum silicide content of the ceramic of the support 35 is 4 wt%, 10 wt%, 15 wt%,
For each 20 wt% or 22 wt% glow plug,
In both the thermal shock resistance test and the current durability test,
No cracks occurred at all.
【００４０】これらのグロープラグのように、支持体３
５のセラミックの珪化モリブデン含有量を４ｗｔ％〜２
２ｗｔ％とした場合、支持体３５の線膨張係数が発熱体
３３の線膨張係数よりも小さく、しかも、支持体３５と
発熱体３３の線膨張係数の差が十分小さくなるため、割
れを防止することができる。従って、支持体３５のセラ
ミックの珪化モリブデン含有量を４〜２２ｗｔ％にする
ことにより、速熱性を向上させつつ、熱衝撃による割れ
を防止することができる。Like these glow plugs, the support 3
Molybdenum silicide content of the ceramic of 5 is 4 wt% to 2
When it is 2 wt%, the linear expansion coefficient of the support 35 is smaller than the linear expansion coefficient of the heating element 33, and the difference between the linear expansion coefficients of the support 35 and the heating element 33 is sufficiently small, so cracking is prevented. be able to. Therefore, by setting the molybdenum silicide content of the ceramic of the support 35 to 4 to 22 wt%, it is possible to improve the rapid heating property and prevent cracking due to thermal shock.
【００４１】なお、上記試験品では、支持体３５のセラ
ミックとして、窒化珪素に金属珪化物を含有させたもの
を用いたが、窒化珪素に、金属珪化物、金属炭化物、金
属ホウ化物および金属窒化物のうちの少なくとも１つ以
上を４〜２２ｗｔ％含有させてもよい。In the above-mentioned test product, as the ceramic of the support 35, silicon nitride containing metal silicide is used. However, silicon nitride is mixed with metal silicide, metal carbide, metal boride and metal nitride. 4-22 wt% of at least one of the materials may be contained.
【００４２】次に、熱衝撃による割れをより確実に防止
するために、発熱体３３における燃焼室側の先端部と支
持体３５における燃焼室側の先端部との間の最短長さ
Ｌ、すなわち発熱体３３の先端部の肉厚について、検討
を行った。Next, in order to more reliably prevent cracking due to thermal shock, the shortest length L between the tip of the heating element 33 on the combustion chamber side and the tip of the support 35 on the combustion chamber side, that is, The thickness of the tip of the heating element 33 was examined.
【００４３】この検討に用いたグロープラグは、抵抗変
化率αが２．０以上、発熱体３３のセラミックはＳｉ3
Ｎ4−７５ｗｔ％ＷＣ、支持体３５のセラミックはＳｉ3
Ｎ4−１０ｗｔ％ＭｏＳｉ2であり、最短長さＬおよび支
持体３５の外径Ｄを種々変えた試験品をそれぞれ４個用
意し、それらについて熱衝撃性を評価した。なお、熱衝
撃性は、１４００℃から２０℃に急冷して評価した。The glow plug used in this study has a resistance change rate α of 2.0 or more, and the ceramic of the heating element 33 is Si 3
N 4 -75 wt% WC, ceramic of support 35 is Si 3
N 4 -10 wt% MoSi 2 , each of which prepared four test products in which the shortest length L and the outer diameter D of the support 35 were variously prepared, and the thermal shock resistance thereof was evaluated. The thermal shock resistance was evaluated by quenching from 1400 ° C to 20 ° C.
【００４４】図４は、この試験に供したグロープラグ
の、最短長さＬ、支持体３５の外径Ｄ、最短長さＬと外
径Ｄの寸法比（Ｌ／Ｄ）、および評価結果を示すもので
ある。FIG. 4 shows the shortest length L, the outer diameter D of the support 35, the dimensional ratio (L / D) between the shortest length L and the outer diameter D, and the evaluation results of the glow plugs used in this test. It is shown.
【００４５】図４に示すように、支持体３５の外径Ｄを
４ｍｍに設定したグロープラグでは、寸法比Ｌ／Ｄ＝
０．００８の場合、熱衝撃性試験において４個中２個に
割れが発生し、寸法比Ｌ／Ｄ＝０．１１３の場合、熱衝
撃性試験において４個中２個に割れが発生し、寸法比Ｌ
／Ｄ＝０．０１の場合、および寸法比Ｌ／Ｄ＝０．１の
場合、割れは全く発生しなかった。As shown in FIG. 4, in the glow plug in which the outer diameter D of the support 35 is set to 4 mm, the dimension ratio L / D =
In the case of 0.008, 2 out of 4 cracks occurred in the thermal shock test, and in the case of the dimension ratio L / D = 0.113, 2 out of 4 cracks occurred in the thermal shock test, Dimension ratio L
When /D=0.01 and the dimension ratio L / D = 0.1, no cracks occurred.
【００４６】ここで、寸法比Ｌ／Ｄ＝０．００８のグロ
ープラグにおける割れの発生原因は、発熱体３３の肉厚
が薄すぎることによる強度不足である。寸法比Ｌ／Ｄ＝
０．１１３ののグロープラグにおける割れの発生原因
は、発熱体３３の肉厚が厚すぎて発熱体３３と支持体３
５の温度差が大きくなるためである。Here, the cause of cracking in the glow plug having the dimension ratio L / D = 0.008 is insufficient strength due to the thin wall thickness of the heating element 33. Dimension ratio L / D =
The cause of cracking in the glow plug of 0.113 is that the thickness of the heating element 33 is too large and the heating element 33 and the support 3
This is because the temperature difference of 5 becomes large.
【００４７】また、支持体３５の外径Ｄを３．５ｍｍに
設定したグロープラグでは、寸法比Ｌ／Ｄ＝０．００９
の場合、発熱体３３の強度不足により熱衝撃性試験にお
いて４個中１個に割れが発生し、寸法比Ｌ／Ｄ＝０．１
１３の場合、発熱体３３と支持体３５の温度差大により
熱衝撃性試験において４個中２個に割れが発生し、寸法
比Ｌ／Ｄ＝０．０１の場合、および寸法比Ｌ／Ｄ＝０．
１の場合、割れは全く発生しなかった。In the glow plug in which the outer diameter D of the support 35 is set to 3.5 mm, the dimension ratio L / D = 0.09.
In the case of 1, due to insufficient strength of the heating element 33, 1 out of 4 cracks occurred in the thermal shock resistance test, and the dimension ratio L / D = 0.1.
In the case of No. 13, cracks occurred in two out of four in the thermal shock test due to a large temperature difference between the heating element 33 and the support 35, and when the dimension ratio L / D = 0.01 and the dimension ratio L / D. = 0.
In the case of 1, no cracking occurred at all.
【００４８】また、支持体３５の外径Ｄを３ｍｍに設定
したグロープラグでは、寸法比Ｌ／Ｄ＝０．００８の場
合、発熱体３３の強度不足により熱衝撃性試験において
４個中１個に割れが発生し、寸法比Ｌ／Ｄ＝０．１１７
の場合、発熱体３３と支持体３５の温度差大により熱衝
撃性試験において４個中３個に割れが発生し、寸法比Ｌ
／Ｄ＝０．０１の場合、および寸法比Ｌ／Ｄ＝０．１の
場合、割れは全く発生しなかった。Further, in the glow plug in which the outer diameter D of the support member 35 is set to 3 mm, when the dimensional ratio L / D = 0.008, one of the four in the thermal shock resistance test due to insufficient strength of the heating element 33. Cracks occur at the dimension ratio L / D = 0.117
In the case of 3, due to the large temperature difference between the heating element 33 and the support 35, 3 out of 4 cracks occurred in the thermal shock test, and the dimensional ratio L
When /D=0.01 and the dimension ratio L / D = 0.1, no cracks occurred.
【００４９】従って、寸法比Ｌ／Ｄを、０．０１≦Ｌ／
Ｄ≦０．１、の範囲に設定することにより、強度不足に
よる割れ、および発熱体３３と支持体３５の温度差によ
る割れを、防止することができる。なお、ヒータ３０の
破断強度の観点から、支持体３５の外径Ｄは２ｍｍ以上
とするのが望ましい。Therefore, the dimensional ratio L / D is 0.01 ≦ L /
By setting the range of D ≦ 0.1, it is possible to prevent cracking due to insufficient strength and cracking due to a temperature difference between the heating element 33 and the support 35. From the viewpoint of the breaking strength of the heater 30, it is desirable that the outer diameter D of the support 35 be 2 mm or more.
【図１】本発明の実施形態に係るグロープラグの全体構
成を示す断面図である。FIG. 1 is a cross-sectional view showing an overall configuration of a glow plug according to an embodiment of the present invention.
【図２】発熱体３３の抵抗変化率αを種々変えたときの
エンジン始動性を評価した結果を示す図である。FIG. 2 is a diagram showing the results of evaluation of engine startability when the resistance change rate α of the heating element 33 is variously changed.
【図３】支持体３５のセラミック中の導電材含有量を種
々変えたときの熱衝撃性および通電耐久特性を評価した
結果を示す図である。FIG. 3 is a diagram showing the results of evaluation of thermal shock resistance and electrical durability when the content of the conductive material in the ceramic of the support 35 was variously changed.
【図４】最短長さＬおよび外径Ｄを種々変えたときの熱
衝撃性を評価した結果を示す図である。FIG. 4 is a diagram showing the results of evaluating the thermal shock resistance when the minimum length L and the outer diameter D are variously changed.
３０…ヒータ、３３…発熱体、３５…支持体。 30 ... Heater, 33 ... Heating element, 35 ... Support.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ テーマコート゛(参考） Ｈ０５Ｂ 3/48 Ｈ０５Ｂ 3/48 ─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. 7 Identification code FI theme code (reference) H05B 3/48 H05B 3/48
Claims (4)
体（３３）がセラミック製の支持体（３５）に埋設され
たヒータ（３０）を備え、前記ヒータ（３０）によりエ
ンジンの燃焼室を予熱するグロープラグにおいて、 前記発熱体（３３）の１２００℃時の抵抗値をＲ１、前
記発熱体（３３）の２０℃時の抵抗値をＲ２としたと
き、Ｒ１／Ｒ２≧２であり、 前記支持体（３５）のセラミックは、金属珪化物、金属
炭化物、金属ホウ化物および金属窒化物のうちの少なく
とも１つ以上を４〜２２重量％含み、かつ前記支持体
（３５）の線膨張係数が前記発熱体（３３）の線膨張係
数よりも小さいことを特徴とするグロープラグ。1. A heater (30) in which a heating element (33) made of ceramic, which generates heat when energized, is embedded in a support (35) made of ceramic, and preheats a combustion chamber of an engine by the heater (30). In the glow plug, when the resistance value of the heating element (33) at 1200 ° C. is R1 and the resistance value of the heating element (33) at 20 ° C. is R2, R1 / R2 ≧ 2, and the support The ceramic of (35) contains 4 to 22% by weight of at least one of a metal silicide, a metal carbide, a metal boride and a metal nitride, and the linear expansion coefficient of the support (35) is the above-mentioned heat generation. A glow plug having a coefficient of linear expansion smaller than that of the body (33).
側の先端部と前記支持体（３５）における前記燃焼室側
の先端部との間の最短長さをＬ、前記支持体（３５）の
外径をＤとしたとき、０．０１≦Ｌ／Ｄ≦０．１、であ
ることを特徴とする請求項１に記載のグロープラグ。2. The shortest length between the tip of the heating element (33) on the combustion chamber side and the tip of the support (35) on the combustion chamber side is L, and the support (35) is The glow plug according to claim 1, wherein when the outer diameter of the glow plug is D, 0.01 ≦ L / D ≦ 0.1.
化珪素を主成分とし、珪化モリブデンを含有することを
特徴とする請求項１または２に記載のグロープラグ。3. The glow plug according to claim 1, wherein the ceramic of the support (35) contains silicon nitride as a main component and contains molybdenum silicide.
化タングステンを主成分とし、窒化珪素を含有すること
を特徴とする請求項１ないし３のいずれか１つに記載の
グロープラグ。4. The glow plug according to claim 1, wherein the ceramic of the heating element (33) is mainly composed of tungsten carbide and contains silicon nitride.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002037871A JP3961847B2 (en) | 2002-02-15 | 2002-02-15 | Glow plug |
| DE2003106264 DE10306264A1 (en) | 2002-02-15 | 2003-02-14 | Glow plug for preheating combustion chamber interior of diesel engine, has ceramic material of support, containing metal silicide, carbide, boride, nitride, and heat generator with specified resistance ratio at 20oC and 1200oC |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002037871A JP3961847B2 (en) | 2002-02-15 | 2002-02-15 | Glow plug |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2003240240A true JP2003240240A (en) | 2003-08-27 |
| JP3961847B2 JP3961847B2 (en) | 2007-08-22 |
Family
ID=27678138
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2002037871A Expired - Fee Related JP3961847B2 (en) | 2002-02-15 | 2002-02-15 | Glow plug |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP3961847B2 (en) |
| DE (1) | DE10306264A1 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2005098317A1 (en) * | 2004-04-07 | 2005-10-20 | Ngk Spark Plug Co., Ltd. | Ceramic heater and manufacturing method thereof, and glow plug using ceramic heater |
| JP2008089233A (en) * | 2006-10-02 | 2008-04-17 | Denso Corp | Glow plug |
| JP2009074708A (en) * | 2007-09-19 | 2009-04-09 | Ngk Spark Plug Co Ltd | Method of manufacturing glow plug |
| WO2010001888A1 (en) | 2008-07-03 | 2010-01-07 | ボッシュ株式会社 | Drive control method for glow plugs |
| WO2013054598A1 (en) * | 2011-10-11 | 2013-04-18 | 株式会社デンソー | Heating device |
| JP2013170563A (en) * | 2012-02-23 | 2013-09-02 | Kubota Corp | Auxiliary chamber type combustion chamber of diesel engine |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9429066B2 (en) * | 2013-07-30 | 2016-08-30 | Kubota Corporation | Subchamber type combustion chamber for diesel engine |
-
2002
- 2002-02-15 JP JP2002037871A patent/JP3961847B2/en not_active Expired - Fee Related
-
2003
- 2003-02-14 DE DE2003106264 patent/DE10306264A1/en not_active Withdrawn
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2005098317A1 (en) * | 2004-04-07 | 2005-10-20 | Ngk Spark Plug Co., Ltd. | Ceramic heater and manufacturing method thereof, and glow plug using ceramic heater |
| US7705273B2 (en) | 2004-04-07 | 2010-04-27 | Ngk Spark Plug Co., Ltd. | Ceramic heater, method of producing the same, and glow plug using a ceramic heater |
| JP2008089233A (en) * | 2006-10-02 | 2008-04-17 | Denso Corp | Glow plug |
| JP2009074708A (en) * | 2007-09-19 | 2009-04-09 | Ngk Spark Plug Co Ltd | Method of manufacturing glow plug |
| WO2010001888A1 (en) | 2008-07-03 | 2010-01-07 | ボッシュ株式会社 | Drive control method for glow plugs |
| JP5119329B2 (en) * | 2008-07-03 | 2013-01-16 | ボッシュ株式会社 | Glow plug drive control method |
| WO2013054598A1 (en) * | 2011-10-11 | 2013-04-18 | 株式会社デンソー | Heating device |
| JP2013084478A (en) * | 2011-10-11 | 2013-05-09 | Denso Corp | Heat generating device |
| JP2013170563A (en) * | 2012-02-23 | 2013-09-02 | Kubota Corp | Auxiliary chamber type combustion chamber of diesel engine |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3961847B2 (en) | 2007-08-22 |
| DE10306264A1 (en) | 2003-09-04 |
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