EP0392181B1 - Glow plug - Google Patents
Glow plug Download PDFInfo
- Publication number
- EP0392181B1 EP0392181B1 EP90103956A EP90103956A EP0392181B1 EP 0392181 B1 EP0392181 B1 EP 0392181B1 EP 90103956 A EP90103956 A EP 90103956A EP 90103956 A EP90103956 A EP 90103956A EP 0392181 B1 EP0392181 B1 EP 0392181B1
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- EP
- European Patent Office
- Prior art keywords
- glow
- filament
- length
- glow plug
- control
- 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.)
- Expired - Lifetime
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23Q—IGNITION; EXTINGUISHING-DEVICES
- F23Q7/00—Incandescent ignition; Igniters using electrically-produced heat, e.g. lighters for cigarettes; Electrically-heated glowing plugs
- F23Q7/001—Glowing plugs for internal-combustion engines
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B3/00—Engines characterised by air compression and subsequent fuel addition
- F02B3/06—Engines 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 plug protruding from its plug housing, in the glow tube of which is arranged a heating coil embedded in insulating powder of high thermal conductivity and having an essentially temperature-independent resistance.
- 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 pencil At its free end section, the glow pencil usually reaches its working temperature of about 850 to 900 ° C. after about 5 to 10 s.
- the glow tube is filled with magnesium oxide as an electrically insulating but heat-conducting powder.
- the good thermal conductivity of the insulating powder is therefore useful and necessary, in particular to quickly transfer the heat from the heating coil to the outside of the glow tube.
- a glow plug of the generic type is known from EP-0 240 650 AI, which provides a connector with low thermal conductivity between the combustion chamber-side heating coil and the connection-side control coil.
- This connector is made of 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.
- a glow plug in the glow tube two series-connected resistance filaments are included, of which the connection-side (regulating filament) has a higher resistance-temperature coefficient (PTC) than that near Free end of the glow plug arranged (heating) resistance coil.
- PTC resistance-temperature coefficient
- These two resistance coils are each embedded in a different type of insulating powder: the heating coil in an insulating powder with high thermal conductivity and the control coil in an insulating powder with low thermal conductivity;
- the separating surface of the two insulating powders can be located at different glow plug levels lying transversely to the axis of the smile, in accordance with the required design of the glow plug.
- the arrangement according to the invention with the characterizing features of the main claim has the advantage that there is still one sets improved control behavior of the glow plug compared to the prior art.
- This optimal control behavior is achieved by filling different types of insulating powder in a special arrangement into the glow tube; the type of insulating powder changes in the axial direction within the glow tube.
- a zone with low thermal conductivity is created in the glow tube between the heating coil and the control coil by a second type of insulating powder, which zone avoids that the heat generated by the heating coil is transported very quickly 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.
- 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 and intended for arrangement in the combustion chamber of a diesel internal combustion engine consists of a tubular candle housing 2, in the longitudinal bore 2a of which a heating element designed as a glow plug 3 is sealingly fixed with its one longitudinal section 3a; the remaining longitudinal section 3b of the glow plug 3 protrudes from the candle housing 2.
- This glow plug 3 has a corrosion-resistant glow tube 4, the end of which protrudes from the candle housing 2 is closed and in which a so-called 2-material resistance coil 5 is embedded in an insulating powder 6, in particular magnesium oxide.
- the 2-material resistance coil 5 consists of a one with the closed end of the glow tube 4 welded heating coil 7 consisting of an essentially temperature-independent resistance material and of a control coil 8 made of a resistance material with a high positive resistance-temperature coefficient (PTC); the heating coil 7 and the control coil 8 are connected in series in the connection area 12.
- the control coil 8 is connected on the connection side to a connection pin 9 which is electrically insulated from the candle housing 2 and which serves as a power supply to the heating coil 7.
- the magnesium oxide insulating powder 6 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 an axial length l3 with 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 2 with a length l 2, where l4 ⁇ 0.5 l3.
- a transition zone 10 with a 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 an insulating powder 11 is, for example, under the name Stettalit (KER 221) from Stettner & Co., 8560 Lauf b. Nuremberg, available.
- 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 insulating powder 11 of low thermal conductivity introduced in layers in this area improves the thermal behavior of the glow plug 1 in 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 becomes too a heat build-up in the heating coil 7 and thus faster heating of the free end section of the glow tube 4 or glow plug 3.
- 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 1 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 shown with I in amperes, the temperature curve with T in ° C and the preheating time with t in seconds.
- U 11 V, and that is because such Glow plugs 1 draw a very high current and consequently cause a voltage drop of approx. 1 V.
- a conventional glow plug is marked with K1, the glow plug according to the invention with K2.
- the temperature curve 1 of the glow plug K2 according to the invention has a steeper increase, so that, for example, after a time t1 of ⁇ 6.5 s there is a heating temperature T of ⁇ 850 ° (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 t2 of ⁇ 8 s (point 14).
- the temperature of 950 ° (point 15) is already reached after a preheating time t3 of about 9 s, for which purpose a conventional glow plug K1 requires a preheating time t4 of ⁇ 13 s (point 16).
- the current profile (curve 2) in FIG. 3 also shows that the current of the glow plug K2 according to the invention is below that of a conventional glow plug K1, i.e. that its power consumption is also lower.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Resistance Heating (AREA)
- Combustion Methods Of Internal-Combustion Engines (AREA)
Description
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 Dieselbrennkraftmaschinen sogenannte Glühstiftkerzen verwendet, an deren heißer Glühstiftoberfläche ein Teil des eingespritzten Kraftstoffs verdampft und sich - vermischt mit komprimierter Luft - entzündet. Die dabei freiwerdende Wärme trägt zur Einleitung des Verbrennungsprozesses bei. Eine Glühstiftkerze hat einen aus ihrem Kerzengehäuse herausragenden rohrförmigen Glühstift, in dessen Glührohr eine in Isolierpulver hoher Wärmeleitfähigkeit eingebettete Heizwendel mit im wesentlichen temperaturunabhängigem Widerstand angeordnet ist. Um eine Überhitzung und damit eine Zerstörung des Glühstiftes 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 internal combustion engines, so-called glow plugs are used, on the hot glow plug surface of which some 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 plug protruding from its plug housing, in the glow tube of which is arranged a heating coil embedded in insulating powder of high thermal conductivity and having an essentially temperature-independent resistance. In order to avoid overheating and thus destruction of the glow plug, 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. With a suitable design and dimensioning of the heating and control filament, the glow plug is quickly heated to the temperature required for starting, but without exceeding the permissible maximum temperature.
Der Glühstift erzielt an seinem freien Endabschnitt üblicherweise seine Arbeitstemperatur von ca. 850 bis 900°C nach ca. 5 bis 10 s.At its free end section, the glow pencil usually reaches its working temperature of about 850 to 900 ° C. after about 5 to 10 s.
Bei bekannten Glühstiftkerzen ist das Glührohr mit Magnesiumoxyd als elektrisch isolierendem, aber Wärme gut leitendem Pulver gefüllt.In known glow plugs, the glow tube is filled with magnesium oxide as an electrically insulating but heat-conducting powder.
Die gute Wärmeleitfähigkeit des Isolierpulvers 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 insulating powder is therefore useful and necessary, in particular to quickly transfer 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 AI 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 given off 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 is known from EP-0 240 650 AI, which provides a connector with low thermal conductivity between the combustion chamber-side heating coil and the connection-side control coil. This connector is made of 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 Heizdrahtsowie Regelwendel-Materialien mit termperaturunabhängigem bzw. temperaturabhängigem 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.
Aus der nicht vorveröffentlichten EP-A-0 336 625 ist eine Glühstiftkerze bekannt, in deren Glührohr zwei in Reihe geschaltete Widerstandswendeln enthalten sind, von denen die anschlußseitige (Regelwendel) einen höheren Widerstands-Temperatur-Koeffizienten (PTC) aufweist, als die nahe dem freien Ende des Glühstiftes angeordnete (Heiz-) Widerstandswendel. Diese beiden Widerstandswendeln sind jeweils in eine andere Sorte von Isolierpulver gebettet: die Heizwendel in ein Isolierpulver hoher Wärmeleitfähigkeit und die Regelwendel in ein Isolierpulver geringer Wärmeleitfähigkeit; die Trennfläche der beiden Isolierpulver kann entsprechend der erforderlichen Auslegung des Glühstiftes an unterschiedlichen, quer zur Lächsachse liegenden Glühstift-Ebenen liegen.From the unpublished EP-A-0 336 625 a glow plug is known, in the glow tube two series-connected resistance filaments are included, of which the connection-side (regulating filament) has a higher resistance-temperature coefficient (PTC) than that near Free end of the glow plug arranged (heating) resistance coil. These two resistance coils are each embedded in a different type of insulating powder: the heating coil in an insulating powder with high thermal conductivity and the control coil in an insulating powder with low thermal conductivity; The separating surface of the two insulating powders can be located at different glow plug levels lying transversely to the axis of the smile, in accordance with the required design of the glow plug.
Die erfindungsgemäße Anordnung mit den kennzeichnenden Merkmalen des Hauptanspruchs hat demgegenüber den Vorteil, daß sich noch ein gegenüber dem Stand der Technik verbessertes Regelverhalten der Glühstiftkerze einstellt. Dabei wird dieses optimale Regelverhalten dadurch erreicht, daß verschiedene Sorten von Isolierpulver in spezieller Anordnung in das Glührohr eingefüllt werden; dabei welchselt die Sorte des Isolierpulvers innerhalb des Glührohrs in axialer Richtung. Erfindungsgemäß wird im Glührohr zwischen der Heizwendel und der Regelwendel durch eine zweite Isolierpulversorte eine Zone mit geringer Wärmeleitfähigkeit 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 erwärmt 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 there is still one sets improved control behavior of the glow plug compared to the prior art. This optimal control behavior is achieved by filling different types of insulating powder in a special arrangement into the glow tube; the type of insulating powder changes in the axial direction within the glow tube. According to the invention, a zone with low thermal conductivity is created in the glow tube between the heating coil and the control coil by a second type of insulating powder, which zone avoids that the heat generated by the heating coil is transported very quickly 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 Glühstiftkerzen möglich.The measures listed in the subclaims allow advantageous and expedient further developments and improvements of the glow plugs 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.
Ausführungsbeispiele der Erfindung sind in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher erläutert. Es zeigen:
- Figur 1
- einen Schnitt durch eine Glühstiftkerze mit Zonen verschiedener Isolierpulver,
Figur 2- ein Diagramm des Temperaturund Stromverlaufs der Glühstiftkerze in Abhängigkeit von der Vorglühzeit bei 11 V Betriebsspannung und
Figur 3- ein Diagramm des Temperatur- und Stromverlaufs von Glühstiftkerzen in Abhängigkeit von der Vorglühzeit bei verschiedenen Betriebsspannungen.
- Figure 1
- a section through a glow plug with zones of different insulating powder,
- Figure 2
- 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
- Figure 3
- a diagram of the temperature and current profile of glow plugs as a function of the preheating time at different operating voltages.
Die in Figur 1 dargestellte, zur Anordnung im Verbrennungsraum einer Dieselbrennkraftmaschine vorgesehene Glühstiftkerze 1 besteht aus einem rohrförmigen Kerzengehäuse 2, in dessen Längsbohrung 2a ein als Glühstift 3 ausgebildeter Heizkörper mit seinem einen Längsabschnitt 3a abdichtend festgelegt ist; der restliche Längsabschnitt 3b des Glühstifts 3 ragt aus dem Kerzengehäuse 2 heraus. Dieser Glühstift 3 hat ein korrosionsfestes Glührohr 4, dessen aus dem Kerzengehäuse 2 herausragendes Ende verschlossen ist und in welchem eine sogenannte 2-Stoff-Widerstandswendel 5 in einem Isolierpulver 6, insbesondere Magnesiumoxyd, eingebettet ist. Die 2-Stoff-Widerstandswendel 5 besteht aus einer einerseits mit dem geschlossenen Ende des Glührohrs 4 verschweißten, aus einem im wesentlichen temperaturunabhängigen Widerstandsmaterial bestehenden Heizwendel 7 und aus einer Regelwendel 8 aus einem Widerstandsmaterial mit einem hohen positiven Widerstands-Temperatur-Koeffizienten (PTC); die Heizwendel 7 und die Regelwendel 8 sind im Verbindungsbereich 12 in Reihe hintereinandergeschaltet. Die Regelwendel 8 ist anschlußseitig mit einem gegenüber dem Kerzengehäuse 2 elektrisch isolierten Anschlußbolzen 9 verbunden, der als Stromzuführung zur Heizwendel 7 dient. Das die Heizwendel 7 und die Regelwendel 8 umschließende Isolierpulver 6 aus Magnesiumoxyd weist eine hohe Wärmeleitfähigkeit und eine gute elektrische Isolierfähigkeit auf.The glow plug 1 shown in FIG. 1 and intended for arrangement in the combustion chamber of a diesel internal combustion engine consists of a
Im Ausführungsbeispiel nach Figur 1 weist die Heizwendel 7 eine axiale Länge l₁ mit beispielsweise ca. 6 Windungen auf. Die Regelwendel 8 weist eine axiale Länge l₃ mit ca. 30 Windungen auf. Das Verhältnis l₃ : l₁ = 5 : 1; dieses entspricht auch etwa dem Verhältnis der zugehörigen Windungszahl. Die Regelwendel 8 befindet sich mit einer Länge l₄ innerhalb des Kerzengehäuses 2, wobei l₄ < 0,5 l₃ ist.In the embodiment of Figure 1, the heating coil 7 has an axial length l₁ with, for example, about 6 turns. The control coil 8 has an axial length l₃ with 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
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. Eine solche Isolierpulver 11 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
In der Übergangszone 10 weist die 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
Die Übergangszone 10 mit dem in diesem Bereich schichtweise eingebrachten Isolierpulver 11 geringer Wärmeleitfähigkeit verbessert das thermische Verhalten der Glühstiftkerze 1 dahingehend, daß die in der Heizwendel 7 erzeugte Wärme nicht ohne weiteres über das die Wärme schlecht leitendem Isolierpulver 11 abtransportiert werden kann, so daß es zu einem Wärmestau in der Heizwendel 7 und damit zu einer schnelleren Aufheizung des freien Endabschnitts des Glührohrs 4 bzw. des Glühstiftes 3 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
In Figur 2 ist ein Diagramm mit dem Temperatur- und Stromverlauf der erfindungsgemäßen Glühstiftkerze 1 in Abhängigkeit der Vorglühzeit gezeigt. Dabei ist der Temperaturverlauf mit 1 und der Stromverlauf mit 2 gekennzeichnet. Die Stromaufnahme ist mit I in Ampere, der Temperaturverlauf mit T in °C und 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 1 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.FIG. 2 shows a diagram with the temperature and current profile of the glow plug 1 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 shown with I in amperes, the temperature curve with T in ° C and the preheating time with t in seconds. Although the on-board electrical system voltage is mostly 12 V, it is indicated in this illustration with U = 11 V, and that is because such Glow plugs 1 draw a very high current and consequently cause a voltage drop of approx. 1 V. A conventional glow plug is marked with K₁, the glow plug according to the invention with K₂.
Wie aus Figur 2 ersichtlich, hat die Temperaturkurve 1 der erfindungsgemäßen Glühstiftkerze K₂ einen steileren Anstieg, so daß es beispielsweise nach einer Zeit t₁ von ∼ 6,5 s zu einer Aufheiztemperatur T von ∼ 850° kommt (Punkt 13). Dieses wird durch das in der Übergangszone 10 befindliche Isolierpulver 11 geringer Wärmeleitfähigkeit hervorgerufen. Die herkömmliche Glühstiftkerze K₁ benötigt hierfür eine Vorglühzeit t₂ von ∼ 8 s (Punkt 14). Bei der erfindungsgemäßen Glühstiftkerze K₂ wird die Temperatur von 950° (Punkt 15) bereits nach einer Vorglühzeit t₃ von ca. 9 s erreicht, wozu eine herkömmliche Glühstiftkerze K₁ eine Vorglühzeit t₄ von ∼ 13 s benötigt (Punkt 16).As can be seen from Figure 2, the temperature curve 1 of the glow plug K₂ according to the invention has a steeper increase, so that, for example, after a time t₁ of ∼ 6.5 s there is a heating temperature T of ∼ 850 ° (point 13). This is caused by the insulating
Durch die zusätzlich eingefügte Isolierpulverschicht 11 mit geringer Wärmeleitfähigkeit wird demnach der Wärmefluß von der Heizwendel 7 zur Regelwendel 8 verzögert, so daß es zum Wärmestau am freien Endabschnitt des Glühstifts 3 und zu einem verzögerten Abregeln durch geringere Temperaturen an der Regelwendel 8 kommt. Die in Figur 2 mit Bezugszeichen 2 gekennzeichneten Stromverlaufskurven 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 insulating
Die Figur 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 t₅ 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.Figure 3 shows a diagram corresponding to Figure 2, but with the difference that the glow plug K₂ invention was operated with an operating voltage of only U = 10.2 V. Out the diagram can be seen that the glow plug K₂ according to the invention can thus also at the lower on-board voltage of 10.2 V to the predetermined value of
Auch der Stromverlauf (Kurve 2) in Figur 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 also shows that the current of the glow plug K₂ according to the invention is below that of a conventional glow plug K₁, i.e. that its power consumption is also lower.
Claims (4)
- Pencil type glow plug (1) provided for arrangement in the combustion chamber of a diesel internal combustion engine and having a tubular plug housing (2) in whose longitudinal bore (2a) an electrically heatable glow pencil (3) is sealingly fixed with its longitudinal section (3a) on the terminal side, while its other longitudinal section (3b) projects from the plug housing (2), this glow pencil (3) being assembled from a corrosion-resistant glow tube (4) whose end projecting from the plug housing (2) is closed, and from insulating powders (6, 11), located in the glow tube (4), of different levels of thermal conductivity and from two electrical resistance filaments (7, 8) which are embedded in the insulating powder (6, 11) in the glow tube (4) and of which one is a heater filament (7) having an essentially temperature-independent resistance and is welded, on the one hand, at the free end of the glow tube (4), and the other is a control filament (8) which serves to control the temperature or limit the temperature and is connected in series with the heater filament (7), welded on the free end of the glow tube 1, has a positive resistance temperature coefficient (PTC) and is connected on the terminal side to a stud (9) which is electrically insulated with respect to the plug housing (2), characterised in that the transition zone (10), which surrounds the connection region (12) of the heater filament (7) and control filament (8) and extends over a length (l₂) of the glow tube (4) is filled by means of an insulating powder (11) of low thermal conductivity, while the remaining length (l₁), located in the interior of the glow tube (4), of the heater filament (7) and the remaining length (l₃) of the control filament (8) are respectively filled with insulating powder (6) of good thermal conductivity.
- Pencil type glow plug according to Claim 1, characterised 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).
- Pencil type glow plug according to Claim 1 or 2, characterised in that the length l₃ of the control filament (8) is approximately 5 times the length l₁ of the heater filament (7), the number of turns per unit length being in an approximately corresponding relationship.
- Pencil type glow plug according to Claim 1, characterised in that in the transition zone (10) the control filament (8) has a section (12) with a larger, in particular double filament pitch by comparison with the remaining control filament (8).
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 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0392181A1 EP0392181A1 (en) | 1990-10-17 |
| EP0392181B1 true EP0392181B1 (en) | 1993-06-02 |
Family
ID=6378200
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP90103956A Expired - Lifetime EP0392181B1 (en) | 1989-04-08 | 1990-03-01 | Glow plug |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0392181B1 (en) |
| JP (1) | JP2793005B2 (en) |
| DE (2) | DE3911492A1 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1258675B (en) * | 1992-12-18 | 1996-02-27 | SPARK PLUG WITH DOUBLE CONTROL SPIRAL FOR DIESEL ENGINES | |
| 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 |
| WO2013157223A1 (en) | 2012-04-16 | 2013-10-24 | 日本特殊陶業株式会社 | Glow plug |
| 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 |
Family Cites Families (4)
| 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 |
| DE2746595A1 (en) * | 1977-10-15 | 1979-04-26 | Bosch Gmbh Robert | GLOW PLUG FOR COMBUSTION MACHINERY |
| CA1095221A (en) * | 1978-02-10 | 1981-02-10 | Gamdur S. Mann | Electric heater and method of making |
| GB2220446B (en) * | 1988-04-06 | 1992-05-27 | Champion Spark Plug Europ | Glow plug for internal combustion engine |
-
1989
- 1989-04-08 DE DE3911492A patent/DE3911492A1/en not_active Withdrawn
-
1990
- 1990-03-01 DE DE9090103956T patent/DE59001591D1/en not_active Expired - Fee Related
- 1990-03-01 EP EP90103956A patent/EP0392181B1/en not_active Expired - Lifetime
- 1990-04-05 JP JP2089259A patent/JP2793005B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| DE3911492A1 (en) | 1990-10-11 |
| JPH02293524A (en) | 1990-12-04 |
| EP0392181A1 (en) | 1990-10-17 |
| JP2793005B2 (en) | 1998-09-03 |
| DE59001591D1 (en) | 1993-07-08 |
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