EP0392181A1 - Glow plug - Google Patents

Glow plug Download PDF

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Publication number
EP0392181A1
EP0392181A1 EP19900103956 EP90103956A EP0392181A1 EP 0392181 A1 EP0392181 A1 EP 0392181A1 EP 19900103956 EP19900103956 EP 19900103956 EP 90103956 A EP90103956 A EP 90103956A EP 0392181 A1 EP0392181 A1 EP 0392181A1
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EP
European Patent Office
Prior art keywords
coil
glow plug
glow
control coil
heating coil
Prior art date
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Granted
Application number
EP19900103956
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German (de)
French (fr)
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EP0392181B1 (en
Inventor
Bernhard Dipl.-Ing. Kaczynski
Werner Dipl.-Ing. Teschner
Andreas Klein
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication of EP0392181A1 publication Critical patent/EP0392181A1/en
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23QIGNITION; EXTINGUISHING-DEVICES
    • F23Q7/00Incandescent ignition; Igniters using electrically-produced heat, e.g. lighters for cigarettes; Electrically-heated glowing plugs
    • F23Q7/001Glowing plugs for internal-combustion engines
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02BINTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B3/00Engines characterised by air compression and subsequent fuel addition
    • F02B3/06Engines characterised by air compression and subsequent fuel addition with compression ignition

Definitions

  • the invention relates to a glow plug for arrangement in the combustion chamber of a diesel engine according to the preamble of claim 1.
  • a glow plug has a tubular glow stick protruding from the plug housing, in the glow tube of which a heating coil with an essentially temperature-independent resistance is arranged, which is embedded in insulating powder of high thermal conductivity (in particular magnesium oxide).
  • this heating coil is electrically connected in series with an additional control coil which has a high positive resistance-temperature coefficient (PTC) and is also embedded in the insulating powder mentioned.
  • PTC positive resistance-temperature coefficient
  • the glow plug usually reaches its working temperature of approx. 850 to 900 ° C after approx. 5 to 10 s at the tip of the combustion chamber.
  • the glow tube is coated with an electrically insulating but heat-conductive ceramic powder, e.g. B. magnesium oxide filled.
  • the good thermal conductivity of the ceramic powder is therefore useful and necessary, in particular to quickly transport the heat from the heating coil to the outside of the glow tube.
  • a glow plug of the generic type has become known from EP-0 240 650 A1, which provides a connecting piece with low thermal conductivity between the heating coil on the combustion chamber side and the control coil on the connection side.
  • This connector consists of a CrNi- Steel with good electrical conductivity but low thermal conductivity.
  • This connecting piece is also surrounded by the insulating powder which is present uniformly in the entire glow tube, but causes only inadequate thermal insulation, is structurally complex and the effect is unsatisfactory.
  • the arrangement according to the invention with the characterizing features of the main claim has the advantage that an improved control behavior of the glow plug is achieved compared to this prior art.
  • This optimal control behavior is achieved in particular by introducing different types of insulating powder into the glow tube.
  • the type of insulating powder inside the glow tube changes in the axial direction.
  • the control coil is heated by the additional insulating powder layer between the heating coil and the control coil rather delayed and the heating coil can consequently develop its performance better.
  • the length of the transition zone with the second type of insulating powder is expediently chosen to be approximately 75% of the length of the heating zone. In connection with a suitable second type of insulating powder, this distance is sufficient to achieve the effect according to the invention.
  • control coil is selected in a length that corresponds approximately to 5 times the heating coil. Approx. 50% of the length of the control coil lies within the candle housing and is not directly affected by the heat conduction.
  • connection between the heating coil and control coil is expediently made by a section of the control coil with a large, in particular double coil pitch.
  • the glow plug 1 shown in FIG. 1 consists of a plug housing 2 and a heating element 3, which is fixedly and gas-tightly arranged in its longitudinal bore and is referred to as a glow plug, and consists of a corrosion-resistant glow tube 4 in which a so-called 2-component filament 5 in an insulating powder 6 , in particular magnesium oxide, is embedded.
  • the 2-fabric spiral 5 consists of a combustion chamber-side heating coil 7 made of an essentially temperature-independent resistance material and a connection-side control coil 8 made of a resistance material with a high resistance-temperature coefficient; the heating and control coils are connected in series.
  • the control coil 8 is connected on the connection side to a connecting bolt 9 which serves as a power supply to the heating coil 7.
  • the heating coil 7 is welded to the glow tube 4 at its end on the combustion chamber side.
  • the magnesium oxide insulating powder enclosing the heating coil 7 and the control coil 8 has a high thermal conductivity and good electrical insulation.
  • the heating coil 7 has an axial length l1 with, for example, about 6 turns.
  • the control coil 8 has a length l3 and about 30 turns.
  • the ratio l3: l1 5: 1. This also corresponds approximately to the ratio of the associated number of turns.
  • the control coil 8 is located within the candle housing with a length l4 l4 ⁇ 0.5 l3.
  • a transition zone 10 with the length l 2 is provided, which is filled with another insulating powder 11.
  • This insulating powder 11 must also insulate electrically, but, in contrast to the insulating powder 6, has a very low thermal conductivity, so that the heat from the heating coil 7 to the control coil 8 is conducted very poorly over this area.
  • Such a powder is, for example, under the name Stettalit (KER 221) from Stettner & Co., 8560 Lauf b. Nuremberg, available.
  • the end section 12 of the control coil 8 has a very large winding pitch, so that only a few turns come to lie here.
  • the length l2 of the transition zone 10 is approximately 75% of the length l1 of the heating coil 7.
  • the transition zone 10 with the second type of insulating powder with low thermal conductivity improves the thermal behavior of the glow plug to the extent that the heat generated in the heating coil 7 cannot be easily removed via the insulating powder 11, which conducts the heat poorly, so that it heat build-up in the tip of the heating coil and thus faster heating of the tip of the glow tube 4 on the combustion chamber side.
  • the insulating powder 11 located in the transition zone 10 has poor thermal conductivity but also causes a delayed curtailment of the output of the heating coil 7 by the control coil 8, since the heat flow from the heating coil 7 only reaches the control coil 8 with a delay. Accordingly, there is a later response of the control coil 8 and thus a delayed curtailment of the current in the heating coil 7. This leads to a faster heating of the heating coil 7 to the necessary annealing temperature and thus to a shortening of the preheating time, which is important for diesel engines.
  • FIG. 2 shows a diagram with the temperature and current profile of the glow plug according to the invention as a function of the preheating time.
  • the temperature curve is marked with 1 and the current curve with 2.
  • the current consumption is I in amperes and the temperature curve with T in ° C, the preheating time with t played in seconds.
  • U 11 V
  • a conventional glow plug is marked with K1, the glow plug according to the invention with K2.
  • the temperature curve 1 of the new glow plug K2 has a steeper rise, so that it comes to a heating temperature T t 850 ° after a time of t1 t 6.5 s (point 13). This is caused by the insulating powder 11 in the transition zone 10 having low thermal conductivity.
  • the conventional glow plug K1 requires a preheating time of t2 ⁇ 8 s (point 14). In the glow plug K2 invention, the temperature of 950 ° (point 15) is already reached after a preheating time of about t3 t 9 s, for which purpose a conventional glow plug K1 needs almost t structurazu 13 s (point 16).
  • the current profile (curve 2) in Fig. 3 shows that the current of the glow plug K2 is below that of a conventional glow plug K1, d. that is, their power consumption is lower.
  • the invention is not restricted to the exemplary embodiment described and illustrated. Rather, it also encompasses all professional configurations without their own inventive content.

Abstract

The invention proposes a glow plug for arrangement in the combustion chamber of a diesel internal-combustion engine, which has improved regulating behaviour and, in particular, a shorter preliminary glow time in comparison to conventional glow plugs. To achieve this, the invention provides a transition zone (10) in that region of the glow plug which is on the combustion-chamber side, more specifically between the heating coil (7) arranged there and the regulating coil (8), the transition zone being formed by an insulating powder of low thermal conductivity arranged in this region and preventing the heat generated in the heating coil (7) from reaching the regulating coil (8) too quickly. <IMAGE>

Description

Stand der TechnikState of the art

Die Erfindung betrifft eine Glühstiftkerze zur Anordnung im Verbrennungsraum einer Dieselbrennkraftmaschine nach dem Oberbegriff des Anspruchs 1.The invention relates to a glow plug for arrangement in the combustion chamber of a diesel engine according to the preamble of claim 1.

Der prinzipielle Aufbau einer Glühstiftkerze ist in der deutschen Patentschrift Nr. 28 02 625 wiedergegeben. Danach werden zur Verbesserung des Kaltstartverhaltens von Dieselmotoren sogenannte Glühstiftkerzen verwendet, an deren heißer Stiftoberfläche ein Teil des eingespritzten Kraftstoffes verdampft und sich - vermischt mit komprimierter Luft - entzündet. Die dabei freiwerdende Wärme trägt zur Einleitung des Verbrennungsprozesses bei. Eine Glühstiftkerze hat einen aus dem Kerzengehäuse herausragenden rohrförmigen Glühstift, in dessen Glührohr eine in Isolierpulver hoher thermischer Leitfähigkeit (insbesondere Magnesiumoxyd) eingebettete Heizwendel mit im wesentlichen temperaturunabhängigem Widerstand angeordnet ist. Um eine Überhitzung und damit eine Zerstörung des Heizkörpers zu vermeiden, ist diese Heizwendel mit einer zusätzlichen Regelwendel elektrisch in Reihe geschaltet, die einen hohen positiven Widerstands-­Temperatur-Koeffizienten (PTC) aufweist und auch in das genannte Isolierpulver mit eingebettet ist. Durch geeignete Auslegung und Dimensionierung von Heiz- und Regelwendel wird die Glühstiftkerze schnell auf die für den Start erforderliche Temperatur erwärmt, ohne jedoch die zulässige Höchsttemperatur zu überschreiten.The basic structure of a glow plug is shown in German Patent No. 28 02 625. Then, to improve the cold start behavior of diesel engines, so-called glow plugs are used, on the hot surface of the pen part of the injected fuel evaporates and ignites - mixed with compressed air. The heat released in the process contributes to the initiation of the combustion process. A glow plug has a tubular glow stick protruding from the plug housing, in the glow tube of which a heating coil with an essentially temperature-independent resistance is arranged, which is embedded in insulating powder of high thermal conductivity (in particular magnesium oxide). In order to avoid overheating and thus destruction of the radiator, this heating coil is electrically connected in series with an additional control coil which has a high positive resistance-temperature coefficient (PTC) and is also embedded in the insulating powder mentioned. By suitable design and dimensioning of heating and As a rule, the glow plug is quickly heated to the temperature required for starting, but without exceeding the permissible maximum temperature.

Der Glühstift erzielt an seiner brennraumseitigen Spitze üblicherweise seine Arbeitstemperatur von ca. 850 bis 900°C nach ca. 5 bis 10 s.The glow plug usually reaches its working temperature of approx. 850 to 900 ° C after approx. 5 to 10 s at the tip of the combustion chamber.

Bei bekannten Glühstiftkerzen ist das Glührohr mit einem elektrisch isolierenden, aber Wärme gut leitenden Keramikpulver, z. B. Magnesiumoxyd, gefüllt.In known glow plugs, the glow tube is coated with an electrically insulating but heat-conductive ceramic powder, e.g. B. magnesium oxide filled.

Die gute Wärmeleitfähigkeit des Keramikpulvers ist deshalb sinnvoll und erforderlich, um insbesondere die Wärme von der Heizwendel rasch nach außen zum Glührohr zu transportieren.The good thermal conductivity of the ceramic powder is therefore useful and necessary, in particular to quickly transport the heat from the heating coil to the outside of the glow tube.

Sofern die Heizwendel und die Regelwendel im Glührohr räumlich eng beieinanderliegen, ergibt sich jedoch der Nachteil, daß die von der Heizwendel abgegebene Wärme durch die gute Wärmeleitfähigkeit sowohl des Isolierpulvers als auch des Glührohrs eine zu rasche Aufheizung der Regelwendel bewirkt. Die Regelwendel erhöht deshalb zu früh ihren temperaturabhängigen Widerstand und regelt die Heizleistung der Heizwendel herunter. Es wäre deshalb von Vorteil, wenn die Temperaturbeeinflussung der Regelwendel seitens der Heizwendel verringert werden könnte. Hierfür ist aus der EP-0 240 650 Al eine Glühstiftkerze der gattungsgemäßen Art bekannt geworden, die zwischen der brennraumseitigen Heizwendel und der anschlußseitigen Regelwendel ein Verbindungsstück mit niedriger thermischer Leitfähigkeit vorsieht. Dieses Verbindungsstück besteht aus einem CrNi-­ Stahl mit einer guten elektrischen Leitfähigkeit, jedoch einer niedrigen thermischen Leitfähigkeit. Dieses Verbindungsstück ist ebenfalls von dem im gesamten Glührohr einheitlich vorhandenen Isolierpulver umgeben, bewirkt aber nur eine unzureichende thermische Isolation, ist baulich aufwendig und in der Wirkung unbefriedigend.If the heating coil and the control coil are spatially close together, there is the disadvantage that the heat emitted by the heating coil causes the control coil to heat up too quickly due to the good thermal conductivity of both the insulating powder and the glow tube. The control coil therefore increases its temperature-dependent resistance too early and regulates the heating output of the heating coil. It would therefore be advantageous if the temperature influence on the control coil by the heating coil could be reduced. For this purpose, a glow plug of the generic type has become known from EP-0 240 650 A1, which provides a connecting piece with low thermal conductivity between the heating coil on the combustion chamber side and the control coil on the connection side. This connector consists of a CrNi- Steel with good electrical conductivity but low thermal conductivity. This connecting piece is also surrounded by the insulating powder which is present uniformly in the entire glow tube, but causes only inadequate thermal insulation, is structurally complex and the effect is unsatisfactory.

Aus der deutschen Patentschrift DE-PS 34 21 950 ist eine Glühstiftkerze bekannt geworden, bei welcher die Heizwendel in einem gesonderten Isolierkörper aus einem gesinterten Keramikmaterial angeordnet ist, während die Regelwendel im üblichen Magnesiumoxyd-Pulver oder in Glas eingebettet ist. Durch diese Anordnung soll eine verbesserte selbstregelnde Funktion der Glühkerze erzielt werden. Dies wird mittels spezieller Heizdraht- sowie Regelwendel-Materialien mit temperaturunabhängigen bzw. temperaturabhängigen Widerstandsverhalten erzielt. Eine gegenseitige Temperaturbeeinflussung zwischen Heizwendel und Regelwendel über das Isolierpulver oder über das Glührohr ist nicht vorgesehen.From the German patent DE-PS 34 21 950 a glow plug has become known, in which the heating coil is arranged in a separate insulating body made of a sintered ceramic material, while the control coil is embedded in the usual magnesium oxide powder or in glass. This arrangement is intended to achieve an improved self-regulating function of the glow plug. This is achieved by means of special heating wire and control coil materials with temperature-independent or temperature-dependent resistance behavior. A mutual temperature influence between the heating coil and control coil via the insulating powder or the glow tube is not provided.

Vorteile der ErfindungAdvantages of the invention

Die erfindungsgemäße Anordnung mit den kennzeichnenden Merkmalen des Hauptanspruchs hat demgegenüber den Vorteil, daß sich noch ein gegenüber diesem Stand der Technik verbessertes Regelverhalten der Glühstiftkerze einstellt. Dabei wird dieses optimale Regelverhalten insbesondere dadurch erreicht, daß verschiedene Sorten von Isolierpulver in das Glührohr eingeführt werden. Dabei wechselt die Sorte des Isolierpulvers innerhalb des Glührohres in axialer Richtung. Erfindungsgemäß wird zwischen der Heizwendel und der Regelwendel durch eine zweite Isolierpulversorte eine Zone mit geringer thermischer Leitfähigkeit geschaffen, die es vermeidet, daß die von der Heizwendel erzeugte Wärme sehr rasch über das sonst übliche Isolierpulver zur Regelwendel transportiert wird. Die Regelwendel wird durch die zusätzliche Isolierpulverschicht zwischen Heizwendel und Regelwendel vielmehr stark verzögert beheizt und die Heizwendel kann demzufolge ihre Leistung besser entfalten.The arrangement according to the invention with the characterizing features of the main claim has the advantage that an improved control behavior of the glow plug is achieved compared to this prior art. This optimal control behavior is achieved in particular by introducing different types of insulating powder into the glow tube. The type of insulating powder inside the glow tube changes in the axial direction. According to the invention created a zone with low thermal conductivity between the heating coil and the control coil by means of a second type of insulating powder, which zone avoids that the heat generated by the heating coil is very quickly transported to the control coil via the otherwise usual insulating powder. The control coil is heated by the additional insulating powder layer between the heating coil and the control coil rather delayed and the heating coil can consequently develop its performance better.

Durch die in den Unteransprüchen aufgeführten Maßnahmen sind vorteilhafte und zweckmäßige Weiterbildungen und Verbesserungen der im Hauptanspruch angegebenen Glühstiftkerze möglich.The measures listed in the subclaims allow advantageous and expedient further developments and improvements of the glow plug specified in the main claim.

Zweckmäßigerweise wird die Länge der Übergangszone mit der zweiten Isolierpulversorte mit ca. 75 % der Länge der Heizzone gewählt. Diese Strecke reicht im Zusammenhang mit einer geeigneten zweiten Isolierpulversorte aus, um den erfindungsgemäßen Effekt zu erzielen.The length of the transition zone with the second type of insulating powder is expediently chosen to be approximately 75% of the length of the heating zone. In connection with a suitable second type of insulating powder, this distance is sufficient to achieve the effect according to the invention.

Bei der erfindungsgemäßen Anordnung wird die Regelwendel in einer Länge gewählt, die ca. dem 5fachen der Heizwendel entspricht. Dabei liegt ca. 50 % der Länge der Regelwendel innerhalb des Kerzengehäuses und wird auch nicht unmittelbar durch die Wärmeleitung beeinflußt.In the arrangement according to the invention, the control coil is selected in a length that corresponds approximately to 5 times the heating coil. Approx. 50% of the length of the control coil lies within the candle housing and is not directly affected by the heat conduction.

Die Verbindung zwischen Heizwendel und Regelwendel erfolgt zweckmäßigerweise durch einen Abschnitt der Regelwendel mit großer, insbesondere doppelter Wendelsteigung.The connection between the heating coil and control coil is expediently made by a section of the control coil with a large, in particular double coil pitch.

Zeichnungdrawing

Ausführungsbeispiele der Erfindung sind in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher erläutert. Es zeigen

  • Fig. 1 einen Schnitt durch eine Glühstiftkerze mit Zonen verschiedener Pulversorten,
  • Fig. 2 ein Diagramm des Temperatur- und Stromverlaufs der Glühstiftkerze in Abhängigkeit von der Vorglühzeit bei 11 V Betriebsspannung und
  • Fig. 3 ein Diagramm des Temperatur- und Stromverlaufs von Glühstiftkerzen in Abhängigkeit von der Vorglühzeit bei verschiedenen Betriebsspannungen.
Embodiments of the invention are shown in the drawing and explained in more detail in the following description. Show it
  • 1 shows a section through a glow plug with zones of different types of powder,
  • Fig. 2 is a diagram of the temperature and current profile of the glow plug as a function of the preheating time at 11 V operating voltage and
  • Fig. 3 is a diagram of the temperature and current profile of glow plugs as a function of the preheating time at different operating voltages.

Die in Fig. 1 dargestellte Glühstiftkerze 1 besteht aus einem Kerzengehäuse 2 und einem in dessen Längsbohrung fest und gasdicht angeordneten, als Glühstift bezeichneten Heizkörper 3, bestehend aus einem korrosionsfesten Glührohr 4, in welchem eine sogenannte 2-Stoff-Wendel 5 in einem Isolierpulver 6, insbesondere Magnesiumoxyd, eingebettet ist. Die 2-Stoff-Wendel 5 besteht aus einer brennraumseitigen Heizwendel 7 aus einem im wesentlichen temperaturunabhängigen Widerstandsmaterial und einer anschlußseitigen Regelwendel 8 aus einem Widerstandsmaterial mit einem hohen Widerstands-Temperatur-­Koeffizienten; die Heiz- und die Regelwendeln sind in Reihe hintereinandergeschaltet. Die Regelwendel 8 ist anschlußseitig mit einem Anschlußbolzen 9 verbunden, der als Stromzuführung zur Heizwendel 7 dient. Die Heizwendel 7 ist an ihrem brennraumseitigen Ende mit dem Glührohr 4 verschweißt. Das die Heizwendel 7 und die Regelwendel 8 umschließende Isolierpulver aus Magnesiumoxyd weist eine hohe Wärmeleitfähigkeit und eine gute elektrische Isolierfähigkeit auf.The glow plug 1 shown in FIG. 1 consists of a plug housing 2 and a heating element 3, which is fixedly and gas-tightly arranged in its longitudinal bore and is referred to as a glow plug, and consists of a corrosion-resistant glow tube 4 in which a so-called 2-component filament 5 in an insulating powder 6 , in particular magnesium oxide, is embedded. The 2-fabric spiral 5 consists of a combustion chamber-side heating coil 7 made of an essentially temperature-independent resistance material and a connection-side control coil 8 made of a resistance material with a high resistance-temperature coefficient; the heating and control coils are connected in series. The control coil 8 is connected on the connection side to a connecting bolt 9 which serves as a power supply to the heating coil 7. The heating coil 7 is welded to the glow tube 4 at its end on the combustion chamber side. The magnesium oxide insulating powder enclosing the heating coil 7 and the control coil 8 has a high thermal conductivity and good electrical insulation.

Im Ausführungsbeispiel nach Fig. 1 weist die Heizwendel 7 eine axiale Länge l₁ mit beispielsweise ca. 6 Windungen auf. Die Regelwendel 8 weist eine Länge l₃ und ca. 30 Windungen auf. Das Verhältnis l₃ : l₁ = 5 : 1. Dieses entspricht auch etwa dem Verhältnis der zugehörigen Windungsanzahl. Die Regelwendel 8 befindet sich mit einer Länge l₄ innerhalb des Kerzengehäuses, wobei
l₄ < 0,5 l₃ ist.
In the embodiment of Fig. 1, the heating coil 7 has an axial length l₁ with, for example, about 6 turns. The control coil 8 has a length l₃ and about 30 turns. The ratio l₃: l₁ = 5: 1. This also corresponds approximately to the ratio of the associated number of turns. The control coil 8 is located within the candle housing with a length l₄
l₄ <0.5 l₃.

Um die Wärmeleitfähigkeit zwischen der Heizwendel 7 und der Regelwendel 8 herabzusetzen, ist eine Übergangszone 10 mit der Länge l₂ vorgesehen, welche mit einem anderen Isolierpulver 11 ausgefüllt ist. Dieses Isolierpulver 11 muß zwar ebenfalls elektrisch isolieren, weist jedoch im Gegensatz zum Isolierpulver 6 eine sehr geringe Wärmeleitfähigkeit auf, so daß die Wärme von der Heizwendel 7 zur Regelwendel 8 nur sehr schlecht über diesen Bereich geleitet wird. Ein solches Pulver ist beispielsweise unter der Bezeichnung Stettalit (KER 221) der Firma Stettner & Co., 8560 Lauf b. Nürnberg, erhältlich.In order to reduce the thermal conductivity between the heating coil 7 and the control coil 8, a transition zone 10 with the length l 2 is provided, which is filled with another insulating powder 11. This insulating powder 11 must also insulate electrically, but, in contrast to the insulating powder 6, has a very low thermal conductivity, so that the heat from the heating coil 7 to the control coil 8 is conducted very poorly over this area. Such a powder is, for example, under the name Stettalit (KER 221) from Stettner & Co., 8560 Lauf b. Nuremberg, available.

In der Übergangszone 10 weist der Endabschnitt 12 der Regelwendel 8 eine sehr große Windungssteigung auf, so daß hier nur wenige Windungen zu liegen kommen. Die Länge l₂ der Übergangszone 10 beträgt etwa 75 % der Länge l₁ der Heizwendel 7.In the transition zone 10, the end section 12 of the control coil 8 has a very large winding pitch, so that only a few turns come to lie here. The length l₂ of the transition zone 10 is approximately 75% of the length l₁ of the heating coil 7.

Die Übergangszone 10 mit der in diesem Bereich schichtweise eingebrachten zweiten Isolierpulversorte mit geringer Wärmeleitfähigkeit verbessert das thermische Verhalten der Glühstiftkerze dahin gehend, daß die in der Heizwendel 7 erzeugte Wärme nicht ohne weiteres über das die Wärme schlecht leitende Isolierpulver 11 abtransportiert werden kann, so daß es zu einem Wärmestau in der Spitze der Heizwendel und damit zu einer schnelleren Aufheizung der brennraumseitigen Spitze des Glührohrs 4 kommt. Das in der Übergangszone 10 befindliche Isolierpulver 11 schlechter Wärmeleitfähigkeit bewirkt aber auch ein verzögertes Abregeln der Leistung der Heizwendel 7 durch die Regelwendel 8, da der Wärmefluß von der Heizwendel 7 nur verzögert zur Regelwendel 8 gelangt. Es erfolgt demnach ein späteres Ansprechen der Regelwendel 8 und damit ein verzögertes Abregeln des Stromes in der Heizwendel 7. Hierdurch kommt es zu einer schnelleren Aufheizung der Heizwendel 7 auf die notwendige Glühtemperatur und damit zu einer Verkürzung der für Dieselmotoren wichtigen Vorglühzeit.The transition zone 10 with the second type of insulating powder with low thermal conductivity, which is introduced in layers in this area, improves the thermal behavior of the glow plug to the extent that the heat generated in the heating coil 7 cannot be easily removed via the insulating powder 11, which conducts the heat poorly, so that it heat build-up in the tip of the heating coil and thus faster heating of the tip of the glow tube 4 on the combustion chamber side. The insulating powder 11 located in the transition zone 10 has poor thermal conductivity but also causes a delayed curtailment of the output of the heating coil 7 by the control coil 8, since the heat flow from the heating coil 7 only reaches the control coil 8 with a delay. Accordingly, there is a later response of the control coil 8 and thus a delayed curtailment of the current in the heating coil 7. This leads to a faster heating of the heating coil 7 to the necessary annealing temperature and thus to a shortening of the preheating time, which is important for diesel engines.

In Fig. 2 ist ein Diagramm mit dem Temperatur- und Stromverlauf der erfindungsgemäßen Glühstiftkerze in Abhängigkeit der Vorglühzeit gezeigt. Dabei ist der Temperaturverlauf mit 1 und der Stromverlauf mit 2 gekennzeichnet. Die Stromaufnahme ist mit I in Ampere und der Temperaturverlauf mit T in °C, die Vorglühzeit mit t in Sekunden wiedergegeben. Obwohl die Bordnetzspannung zumeist 12 V beträgt, ist sie in dieser Darstellung mit U = 11 V angegeben, und zwar deshalb, weil derartige Glühstiftkerzen einen sehr hohen Strom ziehen, und demzufolge einen Spannungsabfall von ca. 1 V bewirken. Eine herkömmliche Glühstiftkerze ist mit K₁, die erfindungsgemäße Glühstiftkerze mit K₂ gekennzeichnet.2 shows a diagram with the temperature and current profile of the glow plug according to the invention as a function of the preheating time. The temperature curve is marked with 1 and the current curve with 2. The current consumption is I in amperes and the temperature curve with T in ° C, the preheating time with t played in seconds. Although the on-board electrical system voltage is mostly 12 V, it is indicated in this illustration as U = 11 V, and this is because glow plugs of this type draw a very high current and consequently cause a voltage drop of approximately 1 V. A conventional glow plug is marked with K₁, the glow plug according to the invention with K₂.

Wie aus Fig. 2 ersichtlich, hat die Temperaturkurve 1 der neuen Glühstiftkerze K₂ einen steileren Anstieg, so daß es beispielsweise nach einer Zeit von t₁∼ 6,5 s zu einer Aufheiztemperatur T ∼ 850° kommt (Punkt 13). Dies wird durch das in der Übergangszone 10 befindliche Isolierpulver 11 geringer Wärmeleitfähigkeit hervorgerufen. Die herkömmliche Glühstiftkerze K₁ benötigt hierfür eine Vorglühzeit von t₂ ∼ 8 s (Punkt 14). Bei der erfindungsgemäßen Glühstiftkerze K₂ wird die Temperatur von 950° (Punkt 15) bereits nach einer Vorglühzeit von ca. t₃∼ 9 s erreicht, wozu eine herkömmliche Glühstiftkerze K₁ nahezu t₄∼ 13 s benötigt (Punkt 16).As can be seen from Fig. 2, the temperature curve 1 of the new glow plug K₂ has a steeper rise, so that it comes to a heating temperature T t 850 ° after a time of t₁ t 6.5 s (point 13). This is caused by the insulating powder 11 in the transition zone 10 having low thermal conductivity. The conventional glow plug K₁ requires a preheating time of t₂ ∼ 8 s (point 14). In the glow plug K₂ invention, the temperature of 950 ° (point 15) is already reached after a preheating time of about t₃ t 9 s, for which purpose a conventional glow plug K₁ needs almost t nahezu 13 s (point 16).

Durch die zusätzlich eingefügte Pulverschicht 11 mit geringer Wärmeleitfähigkeit wird demnach der Wärmefluß zur Regelwendel verzögert, so daß es zum Wärmestau an der Spitze des Glühstiftes und zu einem verzögerten Abregeln durch geringere Temperaturen an der Regelwendel 8 kommt. Die in Fig. 2 mit Bezugszeichen 2 gekennzeichneten Stromverlaufkurven zeigen, daß der Strom I in der erfindungsgemäßen Glühstiftkerze K₂ und der Strom in einer herkömmlichen Glühstiftkerze K₁ annähernd gleich sind.Due to the additionally inserted powder layer 11 with low thermal conductivity, the heat flow to the control coil is therefore delayed, so that heat build-up at the tip of the glow plug and delayed curtailment due to lower temperatures at the control coil 8 occur. The current curve shown in Fig. 2 with reference numeral 2 show that the current I in the glow plug K₂ invention and the current in a conventional glow plug K₁ are approximately the same.

Die Fig. 3 zeigt ein der Figur 2 entsprechendes Diagramm, jedoch mit dem Unterschied, daß die erfindungsgemäße Glühstiftkerze K₂ mit einer Betriebsspannung von nur U = 10,2 V betrieben wurde. Aus dem Diagramm läßt sich ersehen, daß sich die erfindungsgemäße Glühstiftkerze K₂ demnach auch bei der niedrigeren Bordspannung von 10,2 V auf den vorbestimmten Wert von z. B. 850°C in der kurzen Zeit von 8 s aufheizen läßt (s. Bezugszeichen 17), was mit einer herkömmlichen Glühstiftkerze K₁ nur mit einer erhöhten Betriebsspannung U = 11 V erzielt werden kann. Spannungsverluste im Bordnetz wirken sich demnach bei den Glühstiftkerzen gemäß vorliegender Erfindung nicht drastisch auf den Vorglühvorgang aus.3 shows a diagram corresponding to FIG. 2, but with the difference that the glow plug K₂ according to the invention was operated with an operating voltage of only U = 10.2 V. From the diagram it can be seen that the glow plug according to the invention K₂ accordingly at the lower on-board voltage of 10.2 V to the predetermined value of z. B. 850 ° C in the short time of 8 s (see reference number 17), which can be achieved with a conventional glow plug K₁ only with an increased operating voltage U = 11 V. Voltage losses in the vehicle electrical system therefore do not have a drastic effect on the preheating process in the glow plugs according to the present invention.

Auch der Stromverlauf (Kurve 2) in Fig. 3 zeigt, daß der Strom der erfindungsgemäßen Glühkerze K₂ unter dem einer herkömmlichen Glühkerze K₁ liegt, d. h., daß auch deren Leistungsaufnahme geringer ist.The current profile (curve 2) in Fig. 3 shows that the current of the glow plug K₂ is below that of a conventional glow plug K₁, d. that is, their power consumption is lower.

Die Erfindung ist nicht auf das beschriebene und dargestellte Ausführungsbeispiel beschränkt. Sie umfaßt auch vielmehr alle fachmännischen Ausgestaltungen ohne eigenen erfinderischen Gehalt.The invention is not restricted to the exemplary embodiment described and illustrated. Rather, it also encompasses all professional configurations without their own inventive content.

Claims (4)

1. Glühstiftkerze zur Anordnung im Verbrennungsraum einer Dieselbrennkraftmaschine, mit einem Kerzengehäuse und einem in dessen Längsbohrung festgelegten, in den Brennraum hineinragenden, mit Isolierpulver hoher thermischer Leitfähigkeit gefüllten, als Glühstift ausgebildeten Heizkörper, der in seinem Glührohr brennraumseitig eine Heizwendel mit im wesentlichen konstantem Widerstand und anschlußseitig eine hiermit in Reihe geschaltete Regelwendel mit einem positiven Temperatur-Widerstands-Koeffizienten (PTC) zur Temperaturregelung bzw. Temperaturbegrenzung der Heizwendel enthält, wobei zwischen Heizwendel und Regelwendel eine Übergangszone niedriger thermischer Leitfähigkeit vorgesehen ist, dadurch gekennzeichnet, daß innerhalb des Glührohres (4) zwischen der Heizwendel (7) und der Regelwendel (8) eine Übergangszone (10) aus einem Isolierpulver (11) mit geringer thermischer Leitfähigkeit angeordnet ist.1. glow plug for arrangement in the combustion chamber of a diesel internal combustion engine, with a candle housing and a fixed in its longitudinal bore, protruding into the combustion chamber, filled with insulating powder of high thermal conductivity, designed as a glow element, the heating element in the glow tube on the combustion chamber side with a substantially constant resistance and on the connection side contains a control coil connected in series with a positive temperature-resistance coefficient (PTC) for temperature control or temperature limitation of the heating coil, a transition zone of low thermal conductivity being provided between the heating coil and control coil, characterized in that within the glow tube (4) a transition zone (10) made of an insulating powder (11) with low thermal conductivity is arranged between the heating coil (7) and the control coil (8). 2. Glühstiftkerze nach Anspruch 1, dadurch gekennzeichnet, daß die Übergangszone (10) eine Länge l₂ von ca. 75 % der Länge l₁ der Heizzone (7) aufweist (l₂∼ 0,75 x l₁).2. Glow plug according to claim 1, characterized in that the transition zone (10) has a length l₂ of approximately 75% of the length l₁ of the heating zone (7) (l₂∼ 0.75 x l₁). 3. Glühstiftkerze nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Länge l₃ der Regelwendel (8) ca. das 5fache der Länge l₁ der Heizwendel (7) aufweist, wobei sich die Windungszahlen in etwa entsprechend verhalten.3. glow plug according to claim 1 or 2, characterized in that the length l₃ of the control coil (8) has approximately 5 times the length l₁ of the heating coil (7), the number of turns behaving approximately accordingly. 4. Glühstiftkerze nach Anspruch 1, dadurch gekennzeichnet, daß in der Übergangszone (10) die Regelwendel (8) einen Abschnitt (12) mit im Vergleich zur sonstigen Regelwendel (8) großer, insbesondere doppelter Wendelsteigung hat.4. glow plug according to claim 1, characterized in that in the transition zone (10) the control coil (8) has a section (12) with compared to the other control coil (8) large, in particular double spiral pitch.
EP90103956A 1989-04-08 1990-03-01 Glow plug Expired - Lifetime EP0392181B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3911492 1989-04-08
DE3911492A DE3911492A1 (en) 1989-04-08 1989-04-08 GLOW PLUG CANDLE

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EP0392181A1 true EP0392181A1 (en) 1990-10-17
EP0392181B1 EP0392181B1 (en) 1993-06-02

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DE (2) DE3911492A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0602745A1 (en) * 1992-12-18 1994-06-22 B 80 S.r.l. Dual control coil glow plug for diesel engines
EP2840314A4 (en) * 2012-04-16 2015-12-02 Ngk Spark Plug Co Glow plug
CN110148504A (en) * 2019-06-13 2019-08-20 上海久能机电制造有限公司 A kind of transformer neutral point DC magnetic biasing inhibition inductive resistance device

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10248804A1 (en) * 2002-10-19 2004-04-29 Robert Bosch Gmbh Multiple filament for glow plugs
DE102007018045A1 (en) 2007-04-13 2008-10-16 Robert Bosch Gmbh Electrically heatable glow plug for use in combustion chamber of e.g. diesel internal-combustion engine, has heating coil arranged in glow chamber that is sealed by gas-tight sealing which is provided with auxiliary disk

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Publication number Priority date Publication date Assignee Title
US2672546A (en) * 1950-06-23 1954-03-16 Edison Inc Thomas A Glow plug for compression-ignition engines
GB2006334A (en) * 1977-10-15 1979-05-02 Bosch Gmbh Robert Glow-pin plugs
GB2014063A (en) * 1978-02-10 1979-08-22 Gen Motors Corp Electrical heater and method of making
EP0336625A2 (en) * 1988-04-06 1989-10-11 Champion Spark Plug Europe S.A. Glow plug for internal combustion engine

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2672546A (en) * 1950-06-23 1954-03-16 Edison Inc Thomas A Glow plug for compression-ignition engines
GB2006334A (en) * 1977-10-15 1979-05-02 Bosch Gmbh Robert Glow-pin plugs
GB2014063A (en) * 1978-02-10 1979-08-22 Gen Motors Corp Electrical heater and method of making
EP0336625A2 (en) * 1988-04-06 1989-10-11 Champion Spark Plug Europe S.A. Glow plug for internal combustion engine

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0602745A1 (en) * 1992-12-18 1994-06-22 B 80 S.r.l. Dual control coil glow plug for diesel engines
EP2840314A4 (en) * 2012-04-16 2015-12-02 Ngk Spark Plug Co Glow plug
US9702556B2 (en) 2012-04-16 2017-07-11 Ngk Spark Plug Co., Ltd. Glow plug
CN110148504A (en) * 2019-06-13 2019-08-20 上海久能机电制造有限公司 A kind of transformer neutral point DC magnetic biasing inhibition inductive resistance device
CN110148504B (en) * 2019-06-13 2024-02-27 上海久能机电制造有限公司 Transformer neutral point DC magnetic bias suppression inductance resistor

Also Published As

Publication number Publication date
DE3911492A1 (en) 1990-10-11
JP2793005B2 (en) 1998-09-03
EP0392181B1 (en) 1993-06-02
DE59001591D1 (en) 1993-07-08
JPH02293524A (en) 1990-12-04

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