EP0812410A1 - Pencil type glow plug for diesel engines - Google Patents

Pencil type glow plug for diesel engines

Info

Publication number
EP0812410A1
EP0812410A1 EP96900879A EP96900879A EP0812410A1 EP 0812410 A1 EP0812410 A1 EP 0812410A1 EP 96900879 A EP96900879 A EP 96900879A EP 96900879 A EP96900879 A EP 96900879A EP 0812410 A1 EP0812410 A1 EP 0812410A1
Authority
EP
European Patent Office
Prior art keywords
heating device
ceramic heating
glow plug
ceramic
cross
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
Application number
EP96900879A
Other languages
German (de)
French (fr)
Other versions
EP0812410B1 (en
Inventor
Johannes Locher
Albrecht Geissinger
Jürgen OBERLE
Werner Teschner
Horst BÖDER
Karl-Heinz Heussner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP0812410A1 publication Critical patent/EP0812410A1/en
Application granted granted Critical
Publication of EP0812410B1 publication Critical patent/EP0812410B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23Q—IGNITION; EXTINGUISHING-DEVICES
    • F23Q7/00—Incandescent ignition; Igniters using electrically-produced heat, e.g. lighters for cigarettes; Electrically-heated glowing plugs
    • 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

Definitions

  • the invention relates to a glow plug for diesel engines with a ceramic heater according to the preamble of the main claim.
  • a glow plug is already known from DE-OS 38 37 128, in which a ceramic heating device is held by the tip of a cylindrical holder. The ceramic heater is electrically isolated from the holder.
  • a connection device is provided which is in contact with the supply voltage.
  • the ceramic heating device consists of a U-shaped heating section. The two ends of the U-shaped heating section are each contacted with the connection device.
  • a voltage is applied to the ceramic heating device in such a way that a current flows through the ceramic heating section, from one end of the U-shaped heating section via the combustion chamber tip of the heating section to the other end of the U-shaped heating section flows. Because of the resistance of the ceramic, the current heats the heating section so that it glows and can ignite the fuel-air mixture.
  • the glow plug according to the invention with the characterizing features of the main claim has the advantage that the area of the heating device which is most accessible to the combustible mixture reaches the necessary ignition temperature the fastest due to the greater resistance. There- shorter heating times are possible.
  • the increase in resistance by reducing the cross section of the electrically conductive ceramic makes it possible to use a ceramic heating element of somewhat thicker wall thickness, which then has a reduced cross section only at the desired points which are dependent on the design of the motor. As a result, the mechanical strength, in particular of the ceramic heating section, can be increased.
  • the defined reduction in the wall thickness makes it possible to heat up the point of the glow plug which is hit by the fuel mixture.
  • FIG. 1 shows a first embodiment of the glow plug according to the invention
  • FIG. 2 shows a second embodiment
  • FIG. 3 shows a third embodiment
  • FIG. 4 shows a fourth embodiment
  • Figure 5 shows schematically two possible installation variants of a glow plug in the swirl chamber of an internal combustion engine.
  • FIG. 1 shows a longitudinal section through a first embodiment of the invention.
  • the glow plug consists of a cylindrical metal tube 1.
  • This cylindrical metal tube represents the housing of the glow plug and is used for screwing into the engine block by means of a thread 2 on the outside.
  • the cylindrical metal tube also serves as a holder for the glow plug, which protrudes into the combustion chamber and heats the diesel mixture here.
  • a ceramic heating device 3 the head end of which serves as a heating element, is introduced into a tip of the cylindrical metal tube 1 as a glow plug.
  • the housing is screwed into the engine block (not shown) of an internal combustion engine such that the end of the ceramic heating device 3 projects into a combustion chamber of the internal combustion engine in a self-supporting state.
  • the ceramic heating device 3 consists of an electrically conductive ceramic, which has the shape of a sleeve closed on one side.
  • the rear end of the cylindrical metal tube 1 comprises a connecting bolt 4, which is electrically insulated from the cylindrical metal tube 1 by means of an insulation layer 5.
  • the connecting pin 4 is in turn contacted via a contact 6 with the ceramic heating device 3 in such a way that the contact in the closed combustion chamber side bottom of the ceramic heater is electrically conductively contacted.
  • the ceramic heating device 3 is electrically contacted on its circumferential surface held by the cylindrical metal tube with the cylindrical metal tube 1, so that the bottom of the ceramic heating device 3 on the combustion chamber side, on the one hand, is connected to the supply voltage, for example from the battery (not shown) Motor vehicle is supplied, connected and on the other hand is contacted via the cylindrical metal tube 1 with ground. This results in a current flow from the closed bottom of the ceramic heating device 3 via the side walls of the sleeve-shaped ceramic heating device to the cylindrical metal tube by mass.
  • the wall thickness of the ceramic heating device is not the same over the entire ceramic heating device. Rather, the wall thickness in the unsupported end of the ceramic heating device 3 on the combustion chamber side is smaller than at the edge of the sleeve-shaped ceramic.
  • the ceramic heating device As a result, the resistance on the combustion chamber side of the ceramic heating device is increased, so that the ceramic heating device first glows at this point.
  • the ceramic heating device it is not absolutely necessary for the ceramic heating device to have a sleeve shape.
  • a U-shaped ceramic heating device is also conceivable, for example, the wall thickness of the end of the ceramic heating device on the combustion chamber side being tapered relative to the end of the ceramic heating device fastened in the cylindrical metal tube.
  • the representation of such a U-shaped ceramic heating device in a sectioned form is identical to the sectioning representation of a sleeve-shaped ceramic heating device, so that only one figure is shown for both variants.
  • Figure 2 shows the longitudinal section of a second embodiment of the invention
  • the basic structure of the glow plug candle of FIG. 2 corresponds to the structural design of FIG. Half of the individual details are provided with the same reference numerals and the structure for the same details is not to be explained again.
  • the cross-sectional area of the ceramic heating device on the side remote from the holder is also reduced.
  • cutouts 7 were made in the wall of the ceramic heating device. With the number, the diameter and the position of the recesses 7 introduced, the location of the smallest material cross-section and thus the hottest location on the ceramic heating device can be precisely defined and set.
  • the basic shape of the ceramic heating devices is insignificant since these cutouts in the form of bores in any shape, for example in U-shaped and sleeve-shaped ceramic heating devices, can be made. It is only necessary to ensure that when the voltage is applied, the current flows through the location of the ceramic heating device, at which the cross-sectional area for the current flow is reduced and thus the resistance is increased.
  • the core of the ceramic heater is filled with a heat-resistant, electrically insulating material.
  • FIG 3 shows a third embodiment, the basic structure of the glow plug again corresponds to the structure of Figures 2 and 3.
  • the only difference is the design of the ceramic heating section.
  • the ceramic heating device has a rod shape, with an annular recess 8, which has a concentric core 9.
  • the annular recess 8 extends almost over the entire length of the ceramic heating device 3 in such a way that on the side of the ceramic heating device 5 remote from the housing, the cross section of the electrical ceramic is again reduced in a defined manner by the annular recess being so far into the away from the tip rod-shaped ceramic heater protrudes that the cross-sectional area for the current is lowest here.
  • FIG. 4 shows a fourth embodiment of the invention, which will be explained with reference to FIG. 5.
  • FIG. 4 shows only the ceramic heating pin, since the structure and arrangement of the metal tube and the connecting device correspond to FIGS. 1 to 3 and will not be explained again here.
  • a vortex chamber of an internal combustion engine is shown schematically in FIG.
  • the combustion air necessary for the combustion enters the swirl chamber via an overflow channel 11, while the fuel is injected into the swirl chamber via a nozzle 12, so that a combustible mixture is formed.
  • 5 shows two installation options for glow plugs.
  • the glow plug Gl is shown here in the so-called current installation position, ie the combustion air flowing in to the overflow channel 11 of the swirl chamber hits the glow plug Gl in the upward direction.
  • the tip of the glow pencil which is far from the holder, is most accessible to the flammable mixture. It is therefore sensible to provide the point with the reduction in the cross section of the electrically conductive ceramic, as described in FIGS. 1 to 3, on the tip of the ceramic heating device remote from the holder.
  • the second glow plug G2 is installed in the so-called current-reducing position.
  • the incoming combustion air hits the glow plug G2 in the downward direction.
  • the flow direction was schematically entered in the swirl chamber with the dashed arrow. Since the combustible mixture impinges on the glow plug at a defined distance from the tip remote from the holder, the reduced cross section is also applied at this point, since the glow plug has a current-reducing position.
  • the defined distance depends on the design of the motor. Installation in the downstream direction is more favorable compared to the current installation position in terms of exhaust gas values.
  • the ceramic heating device in the form of the glow plug which is held in a self-supporting manner by the housing, can of course also be used as a heating device for flame candles.

Abstract

A pencil type glow plug preheats the fuel-air mixture in the combustion chamber of a self-igniting internal combustion engine. The pencil type glow plug has a heating ceramic device and the resistance of the heating ceramic device is increased by reducing its cross-section in the area in which the fuel-air mixture is most accessible in the combustion chamber.

Description

Glühstiftkerze für DieselmotorenGlow plug for diesel engines
Stand der TechnikState of the art
Die Erfindung geht aus von einer Glühkerze für Dieselmotoren mit einer keramischen Heizvorrichtung nach der Gattung des Hauptanspruchs. Es ist schon eine solche Glühkerze aus der DE-OS 38 37 128 bekannt, bei welcher eine keramische Heiz¬ vorrichtung von der Spitze eines zylindrischen Halters ge¬ halten wird. Die keramische Heizvorrichtung ist gegen den Halter elektrisch isoliert. Auf der Seite des zylindrischen Halters, die der keramischen Heizvorrichtung gegenüberliegt ist eine Anschlußvorrichtung vorgesehen, welche mit der Ver¬ sorgungsspannung kontaktiert ist. Die keramische Heizvor¬ richtung besteht aus einem U-förmigen Heizabschnitt. Die beiden Enden des U-förmigen Heizabschnitts sind jeweils mit der Anschlußvorrichtung kontaktiert. Während eines Glühvor¬ gangs wird an die keramische Heizvorrichtung eine Spannung derart angelegt, daß ein Strom über den keramischen Heizab¬ schnitt und zwar von einem Ende des U-förmigen Heizab¬ schnitts über die brennraumseitige Spitze des Heizabschnitts zum anderen Ende des U-förmigen Heizabschnitts fließt. Der Strom bewirkt aufgrund des Widerstandes der Keramik die Er¬ wärmung des Heizabschnittes, so daß dieser glüht und das Brennstoff-Luftgemisches entzünden kann.The invention relates to a glow plug for diesel engines with a ceramic heater according to the preamble of the main claim. Such a glow plug is already known from DE-OS 38 37 128, in which a ceramic heating device is held by the tip of a cylindrical holder. The ceramic heater is electrically isolated from the holder. On the side of the cylindrical holder that lies opposite the ceramic heating device, a connection device is provided which is in contact with the supply voltage. The ceramic heating device consists of a U-shaped heating section. The two ends of the U-shaped heating section are each contacted with the connection device. During an annealing process, a voltage is applied to the ceramic heating device in such a way that a current flows through the ceramic heating section, from one end of the U-shaped heating section via the combustion chamber tip of the heating section to the other end of the U-shaped heating section flows. Because of the resistance of the ceramic, the current heats the heating section so that it glows and can ignite the fuel-air mixture.
Vorteile der ErfindungAdvantages of the invention
Die erfindungsgemäße Glühstiftkerze mit den kennzeichnenden Merkmalen des Hauptanspruchs hat den Vorteil , daß der Be¬ reich der HeizVorrichtung, der dem brennbaren Gemisch am zu¬ gänglichsten ist, aufgrund des damit größeren Widerstandes am schnellsten die notwendige Zündtemperatur erreicht. Da- durch sind kürzere Aufheizzeiten möglich. Die Widerstandser- hδhung durch eine Reduzierung des Querschnitts der elek¬ trisch leitfähigen Keramik ermöglicht es, ein keramisches Heizelement von etwas stärkerer Wanddicke einzusetzen, das dann nur an den gewünschten, von der Konstruktion des Motors abhängigen Punkten einen reduzierten Querschnitt aufweist. Dadurch kann die mechanische Festigkeit insbesondere des keramischen Heizabschnittes erhöht werden. Die definierte Reduzierung der Wanddicke ermöglicht es, genau die Stelle der Glühstiftkerze am heißesten werden zu lassen, auf die das Brennkraftgemisch auftrifft.The glow plug according to the invention with the characterizing features of the main claim has the advantage that the area of the heating device which is most accessible to the combustible mixture reaches the necessary ignition temperature the fastest due to the greater resistance. There- shorter heating times are possible. The increase in resistance by reducing the cross section of the electrically conductive ceramic makes it possible to use a ceramic heating element of somewhat thicker wall thickness, which then has a reduced cross section only at the desired points which are dependent on the design of the motor. As a result, the mechanical strength, in particular of the ceramic heating section, can be increased. The defined reduction in the wall thickness makes it possible to heat up the point of the glow plug which is hit by the fuel mixture.
Besonders vorteilhaft ist, daß durch die Reduzierung der Wanddicke der keramischen Heizvorrichtung in der Seitenwand eine Erhöhung des Widerstandes und damit eine schnelleres Erreichen der Betriebstemperatur an dieser Stelle einfach und ohne Veränderung der Materialbeschaffenheit zu realisieren ist. Bei einem Einbau der Glühstiftkerze in der Wirbelkammer, wird genau die Stelle der HeizVorrichtung am heißesten, die die beste Gemischzugänglichkeit hat, was somit ein besseres Entzündung des Dieselgemisches bewirkt.It is particularly advantageous that by reducing the wall thickness of the ceramic heating device in the side wall, an increase in the resistance and thus a faster reaching of the operating temperature can be achieved at this point easily and without changing the material properties. When the glow plug is installed in the swirl chamber, the point of the heating device with the best access to the mixture becomes the hottest, which in turn leads to a better ignition of the diesel mixture.
Durch die in den Unteransprüchen aufgeführten Maßnahmen sind vorteilhafte Weiterbildungen und Verbesserungen der im Hauptanspruch angegebenen Glühstiftkerze möglich. Eine weitere einfache und kostengünstige Realisierung der Reduzierung des Querschnittes des Strompfades durch die Ke¬ ramik ergibt sich, wenn eine bekannte U-fδrmige oder hülsen- fδrmige keramische Heizvorrichtung an den Stellen der Quer¬ schnittsreduzierung einfach mit Unterbrechungen, beispiels¬ weise Bohrungen versehen ist. Hier ist keine neue entspre¬ chend angepaßte Fertigung notwendig, sondern beispielsweise nur ein weiterer Arbeitsschritt beispielsweise das Bohren hinzuzufügen. Durch das Ausfüllen der elektrisch leitenden keramischen Heizvorrichtung mit elektrisch isolierenden Ma¬ terial wird die mechanische Festigkeit der keramischen Heiz¬ vorrichtung erhöht. ZeichnungThe measures listed in the subclaims allow advantageous developments and improvements of the glow plug specified in the main claim. A further simple and inexpensive realization of the reduction of the cross-section of the current path through the ceramic results if a known U-shaped or sleeve-shaped ceramic heating device is simply provided with interruptions, for example bores, at the points of the reduction in cross-section. No new, correspondingly adapted production is necessary here, but, for example, only a further work step, for example adding drilling. By filling the electrically conductive ceramic heating device with electrically insulating material, the mechanical strength of the ceramic heating device is increased. drawing
Ausführungsbeispiele der Erfindung sind in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher er¬ läutert. Es zeigen Figur 1 ein erstes Ausführungsbeispiel der erfindungsgemäßen Glühstiftkerze, Figur 2 ein zweites Ausführungsbeispiel, Figur 3 ein drittes Ausführungsbeispiel und Figur 4 ein viertes Ausführungsbeispiel. Figur 5 zeigt schematisch zwei mögliche Einbauvarianten einer Glühkerze in der Wirbelkammer einer Brennkraftmaschine.Exemplary embodiments of the invention are shown in the drawing and explained in more detail in the following description. 1 shows a first embodiment of the glow plug according to the invention, FIG. 2 shows a second embodiment, FIG. 3 shows a third embodiment and FIG. 4 shows a fourth embodiment. Figure 5 shows schematically two possible installation variants of a glow plug in the swirl chamber of an internal combustion engine.
Beschreibung der AusführungsbeispieleDescription of the embodiments
Figur 1 zeigt einen Längsschnitt durch eine erste Ausfüh¬ rungsform der Erfindung. Die Glühstiftkerze besteht hierbei aus einen zylindrischen Metallrohr 1. Dieses zylindrische Metallrohr stellt das Gehäuse der Glühkerze dar und dient durch ein auf der Außenseite angebrachtes Gewinde 2 zum Ein¬ schrauben in den Motorblock. Das zylindrische Metallrohr dient außerdem als Halter für den Glühstift, welcher in den Brennraum hineinragt und hier für eine Erwärmung des Diesel- gemisches sorgt. In eine Spitze des zylindrischen Metall¬ rohrs 1 ist als Glühstift eine keramische HeizVorrichtung 3, deren Kopfende als Heizelement dient, eingebracht. Mittels des Gewindes 2 wird das Gehäuse so in den nicht dargestell¬ ten Motorblock einer Brennkraftmaschine eingeschraubt, daß das Ende der keramischen HeizVorrichtung 3 in einem freitra¬ genden Zustand in eine Verbrennungskammer der Brennkraftma¬ schine hineinragt. Die keramische Heizvorrichtung 3 besteht hierbei aus einer elektrisch leitfähigen Keramik, die die Form einer an einer Seite verschlossenen Hülse aufweist. Das rückwärtige Ende des zylindrischen Metallrohrs 1 umfaßt einen Anschlußbolzen 4, welcher mittels einer Isolations- schicht 5 gegenüber des zylindrischen Metallrohrs 1 elek¬ trisch isoliert ist. Der Anschlußbolzen 4 ist wiederum über einen Kontakt 6 mit der keramischen HeizVorrichtung 3 in der Art kontaktiert, daß der Kontakt im geschlossenen brennraum- seitigen Boden der keramischen Heizvorrichtung elektrisch leitend kontaktiert ist. Die keramische HeizVorrichtung 3 ist an ihrer vom zylindrischen Metallrohr gehaltenen Um- fangsfläche mit dem zylindrischen Metallrohr 1 elektrisch kontaktiert, so daß der brennraumseitige Boden der kerami¬ schen HeizVorrichtung 3 einerseits mit der Versorgungsspan¬ nung, welche beispielsweise von der nicht dargestellten Bat¬ terie eines Kraftfahrzeugs geliefert wird, verbunden ist und andererseits über das zylindrische Metallrohr 1 mit Masse kontaktiert ist. Damit ergibt sich ein Stromfluß von dem verschlossenen Boden der keramischen Heizvorrichtung 3 über die Seitenwände der hülsenförmigen keramischen Heizvorrich¬ tung zum zylindrischen Metallrohr nach Masse. Die Wanddicke der keramischen Heizvorrichtung ist hierbei nicht über die gesamte keramische Heizvorrichtung gleich. Vielmehr ist die Wanddicke im brennraumsei igen freitragenden Ende der kera¬ mischen Heizvorrichtung 3 geringer als am Rand der hülsen¬ förmigen Keramik. Dadurch wird der Widerstand auf der Brenn¬ raumseite der keramischen Heizvorrichtung erhöht, so daß an dieser Stelle die keramische HeizVorrichtung zuerst glüht. Dabei ist jedoch nicht zwingend erforderlich, daß die kera¬ mische HeizVorrichtung eine Hülsenform aufweist. Denkbar ist beispielsweise auch eine U-förmige keramische Heizvorrich¬ tung, wobei wiederum das brennraumseitige Ende der kerami¬ schen HeizVorrichtung in seiner Wanddicke gegenüber des im zylindrischen Metallrohr befestigten Endes der keramischen Heizvorrichtung verjüngt ist. Die Darstellung einer solchen U-förmigen keramischen Heizvorrichtung in geschnittener Form ist der geschnittenen Darstellung einer hülsenförmigen ke¬ ramischen Heizvorrichtung identisch, so daß hier nur eine Figur für beide Varianten dargestellt ist.FIG. 1 shows a longitudinal section through a first embodiment of the invention. The glow plug consists of a cylindrical metal tube 1. This cylindrical metal tube represents the housing of the glow plug and is used for screwing into the engine block by means of a thread 2 on the outside. The cylindrical metal tube also serves as a holder for the glow plug, which protrudes into the combustion chamber and heats the diesel mixture here. A ceramic heating device 3, the head end of which serves as a heating element, is introduced into a tip of the cylindrical metal tube 1 as a glow plug. By means of the thread 2, the housing is screwed into the engine block (not shown) of an internal combustion engine such that the end of the ceramic heating device 3 projects into a combustion chamber of the internal combustion engine in a self-supporting state. The ceramic heating device 3 consists of an electrically conductive ceramic, which has the shape of a sleeve closed on one side. The rear end of the cylindrical metal tube 1 comprises a connecting bolt 4, which is electrically insulated from the cylindrical metal tube 1 by means of an insulation layer 5. The connecting pin 4 is in turn contacted via a contact 6 with the ceramic heating device 3 in such a way that the contact in the closed combustion chamber side bottom of the ceramic heater is electrically conductively contacted. The ceramic heating device 3 is electrically contacted on its circumferential surface held by the cylindrical metal tube with the cylindrical metal tube 1, so that the bottom of the ceramic heating device 3 on the combustion chamber side, on the one hand, is connected to the supply voltage, for example from the battery (not shown) Motor vehicle is supplied, connected and on the other hand is contacted via the cylindrical metal tube 1 with ground. This results in a current flow from the closed bottom of the ceramic heating device 3 via the side walls of the sleeve-shaped ceramic heating device to the cylindrical metal tube by mass. The wall thickness of the ceramic heating device is not the same over the entire ceramic heating device. Rather, the wall thickness in the unsupported end of the ceramic heating device 3 on the combustion chamber side is smaller than at the edge of the sleeve-shaped ceramic. As a result, the resistance on the combustion chamber side of the ceramic heating device is increased, so that the ceramic heating device first glows at this point. However, it is not absolutely necessary for the ceramic heating device to have a sleeve shape. A U-shaped ceramic heating device is also conceivable, for example, the wall thickness of the end of the ceramic heating device on the combustion chamber side being tapered relative to the end of the ceramic heating device fastened in the cylindrical metal tube. The representation of such a U-shaped ceramic heating device in a sectioned form is identical to the sectioning representation of a sleeve-shaped ceramic heating device, so that only one figure is shown for both variants.
Figur 2 zeigt den Längsschnitt einer zweiten Ausführungsform der ErfindungFigure 2 shows the longitudinal section of a second embodiment of the invention
Die Glühstif kerze der Figur 2 entspricht in ihrem prinzipi¬ ellen Aufbau der konstruktiven Gestaltung der Figur 1, wes- halb die einzelnen Details mit gleichem Bezugszeichen verse¬ hen sind und der Aufbau für gleiche Details nicht nochmals erläutert werden soll. Bei der Ausführungsform gemäß Figur 2 ist ebenfalls die Querschnittsfläche der keramischen Heiz- vorrichtung auf der halterfernen Seite verringert. Im Gegen¬ satz zu Figur 1 wurden hier jedoch in die Wand der kerami¬ schen Heizvorrichtung Aussparungen 7 eingebracht. Mit der Anzahl, dem Durchmesser und der Lage der eingebrachten Aus¬ sparungen 7 kann die Stelle des geringsten Werkstoffquer¬ schnitts und somit die heißeste Stelle an der keramischen Heizvorrichtung genau definiert und eingestellt werden. Die Grundform der keramischen Heizvorrichtungen ist dabei unbe¬ deutend, da diese Aussparungen in Form von Bohrungen in jeg¬ licher Form also beispielsweise in U-förmige und hülsenfδr- mige keramischen HeizVorrichtungen eingebracht werden kön¬ nen. Es ist lediglich sicherzustellen, daß beim Anlegen der Spannung der Strom durch die Stelle der keramischen Heizvor¬ richtung fließt, an welcher die Querschnittsfläche für den Stromfluß verringert und damit der Widerstand erhöht ist.The basic structure of the glow plug candle of FIG. 2 corresponds to the structural design of FIG. Half of the individual details are provided with the same reference numerals and the structure for the same details is not to be explained again. In the embodiment according to FIG. 2, the cross-sectional area of the ceramic heating device on the side remote from the holder is also reduced. In contrast to FIG. 1, however, cutouts 7 were made in the wall of the ceramic heating device. With the number, the diameter and the position of the recesses 7 introduced, the location of the smallest material cross-section and thus the hottest location on the ceramic heating device can be precisely defined and set. The basic shape of the ceramic heating devices is insignificant since these cutouts in the form of bores in any shape, for example in U-shaped and sleeve-shaped ceramic heating devices, can be made. It is only necessary to ensure that when the voltage is applied, the current flows through the location of the ceramic heating device, at which the cross-sectional area for the current flow is reduced and thus the resistance is increased.
Der Kern der keramischen Heizvorrichtung ist mit einem hitzebeständigen, elektrisch isolierenden Material gefüllt.The core of the ceramic heater is filled with a heat-resistant, electrically insulating material.
Figur 3 zeigt eine dritte Ausgestaltungsform, wobei der prinzipielle Aufbau der Glühstiftkerze wiederum den Aufbau aus den Figuren 2 und 3 entspricht. Der einzige Unterschied besteht in der Gestaltung des keramischen Heizabschnitts. Die keramische Heizvorrichtung hat hierbei eine Stabform, mit einer kreisringförmige Ausnehmung 8, die einen konzen¬ trischen Kern 9 auf eist. Die kreisringförmige Ausnehmung 8 erstreckt sich dabei fast über die gesamte Länge der kerami¬ schen HeizVorrichtung 3 in der Art, daß auf der gehäusefer¬ nen Seite der keramischen Heizvorrichtung 5 wiederum der Querschnitt der elektrischen Keramik definiert reduziert ist, indem die kreisringförmige Ausnehmung soweit in die halterferne Spitze stabförmigen keramischen Heizvorrichtung ragt, daß die Querschnittsfläche für den Strom hier am ge¬ ringsten ist.Figure 3 shows a third embodiment, the basic structure of the glow plug again corresponds to the structure of Figures 2 and 3. The only difference is the design of the ceramic heating section. The ceramic heating device has a rod shape, with an annular recess 8, which has a concentric core 9. The annular recess 8 extends almost over the entire length of the ceramic heating device 3 in such a way that on the side of the ceramic heating device 5 remote from the housing, the cross section of the electrical ceramic is again reduced in a defined manner by the annular recess being so far into the away from the tip rod-shaped ceramic heater protrudes that the cross-sectional area for the current is lowest here.
Figur 4 zeigt eine vierte Ausgestaltungsform der Erfindung, die unter Bezugnahme der Figur 5 erläutert werden soll. Die Figur 4 zeigt hier nur den keramischen Heizstift, da der Aufbau und die Anordnung des Metallrohrs und der Anschlu߬ vorrichtung den Figuren 1 bis 3 entspricht und hier nicht nochmals erläutert werden soll. In Figur 5 ist schematisch eine Wirbelkammer einer Brennkraftmaschine dargestellt. Die für die Verbrennung notwendige Verbrennungsluft gelangt über einen Überströmkanal 11 in die Wirbelkammer, während der Brennstroff über eine Düse 12 in die Wirbelkammer einge¬ spritzt wird, so daß sich ein brennfähiges Gemisch bildet. Nun sind in dieser Figur 5 zwei Einbaumöglichkeiten für Glühstiftkerzen gezeigt. Die Glühstiftkerze Gl ist hier in der sogenannten Stromaufeinbaulage dargestellt, d.h. die zum Überströmkanal 11 der Wirbelkammer einströmende Verbren¬ nungsluft trifft in Aufwärtsrichtung auf die Glühstiftkerze Gl. Hier ist die halterferne Glühstiftspitze am weitesten dem brennbaren Gemisch zugänglich. Deshalb ist es sinnvoll auch die Stelle mit der Reduzierung des Querschnitts der elektrischen leitfähigen Keramik, wie in Figur 1 bis 3 be¬ schrieben, an der halterfernen Spitze der keramischen Heiz¬ vorrichtung vorzusehen. Dagegen ist die zweite Glühstiftker¬ ze G2 in der sogenannten Stromabeinbaulage eingebaut. Hier trifft die einströmende Verbrennungsluft in Abwärtsrichtung auf die Glühstiftkerze G2. Zu Verdeutlichung wurde in der Wirbelkammer mit dem gestrichelten Pfeil schematisch die Strömungsrichtung eingetragen. Da bei dieser Stromabeinbau¬ lage der Glühstiftkerze das brennfähige Gemisch in einem de¬ finierten Abstand von der halterfernen Spitze auf den Glüh¬ stift auftrifft, wird der reduzierte Querschnitt auch an dieser Stelle angebracht. Der definierte Abstand ist dabei abhängig von der Konstruktion des Motors. Der Einbau in Stromabwärtsrichtung ist gegenüber der Stromaufeinbaulage günstiger im Hiblick auf die Abgaswerte aus. Die keramische Heizvorrichtung in Form des Glühstiftes, der von dem Gehäuse freitragend gehalten wird, kann selbstver¬ ständlich auch bei Flammkerzen als HeizVorrichtung einge¬ setzt werden. FIG. 4 shows a fourth embodiment of the invention, which will be explained with reference to FIG. 5. FIG. 4 shows only the ceramic heating pin, since the structure and arrangement of the metal tube and the connecting device correspond to FIGS. 1 to 3 and will not be explained again here. A vortex chamber of an internal combustion engine is shown schematically in FIG. The combustion air necessary for the combustion enters the swirl chamber via an overflow channel 11, while the fuel is injected into the swirl chamber via a nozzle 12, so that a combustible mixture is formed. 5 shows two installation options for glow plugs. The glow plug Gl is shown here in the so-called current installation position, ie the combustion air flowing in to the overflow channel 11 of the swirl chamber hits the glow plug Gl in the upward direction. Here the tip of the glow pencil, which is far from the holder, is most accessible to the flammable mixture. It is therefore sensible to provide the point with the reduction in the cross section of the electrically conductive ceramic, as described in FIGS. 1 to 3, on the tip of the ceramic heating device remote from the holder. In contrast, the second glow plug G2 is installed in the so-called current-reducing position. Here the incoming combustion air hits the glow plug G2 in the downward direction. For clarification, the flow direction was schematically entered in the swirl chamber with the dashed arrow. Since the combustible mixture impinges on the glow plug at a defined distance from the tip remote from the holder, the reduced cross section is also applied at this point, since the glow plug has a current-reducing position. The defined distance depends on the design of the motor. Installation in the downstream direction is more favorable compared to the current installation position in terms of exhaust gas values. The ceramic heating device in the form of the glow plug, which is held in a self-supporting manner by the housing, can of course also be used as a heating device for flame candles.

Claims

Ansprüche Expectations
1. Glühkerze für Dieselmotoren mit einem zylindrischen Me¬ tallrohr, mit einer Anschlußvorrichtung zur elektrischen Kontaktierung und mit einer keramischen Heizvorrichtung, wo¬ bei das zylindrische Metallrohr an seiner Spitze die kerami¬ sche Heizvorrichtung frei tragend hält, wobei die keramische Heizvorrichtung mit der Anschlußvorrichtung kontaktiert ist, so daß während des Glühvorgangs ein Strom durch die ke¬ ramische Heizvorrichtung fließt, wobei die keramische1. Glow plug for diesel engines with a cylindrical metal tube, with a connecting device for electrical contacting and with a ceramic heating device, the cylindrical metal tube at its tip holding the ceramic heating device in a self-supporting manner, the ceramic heating device making contact with the connecting device is, so that a current flows through the ceramic heating device during the annealing process, the ceramic
HeizVorrichtung (3) mindestens eine Stelle verringerten Querschnitts {7, 10) aufweist, dadurch gekennzeichnet, daß die Querschnittsreduzierung der keramischen Heizvorrichtung an der Stelle erfolgt, auf die das Brennstoff-Luf -Gemisch auftrifft, wobei sich die Querschnittsreduzierung in der Seitenwand der keramischen Heizvorrichtung befindet und wobei zur Querschnittsreduzierung der keramischen HeizVorrichtung die Wanddicke reduziert ist.Heating device (3) has at least one point of reduced cross-section {7, 10), characterized in that the cross-sectional reduction of the ceramic heating device takes place at the point where the fuel-air mixture impinges, the cross-sectional reduction in the side wall of the ceramic heating device is located and the wall thickness is reduced to reduce the cross section of the ceramic heating device.
2. Glühkerze nach Anspruch 1, dadurch gekennzeichnet, daß zur weiteren Querschnittsreduzierung Aussparungen (7) in die Wand der keramischen Heizvorrichtung (3) eingebracht sind.2. Glow plug according to claim 1, characterized in that for further cross-sectional reduction recesses (7) in the wall of the ceramic heater (3) are introduced.
3. Glühkerze nach einem der vorherigen Ansprüche, dadurch gekennzeichnet, daß die keramische Heizvorrichtung (3) mit einem hitzebeständigen, elektrisch isolierenden Material (8) gefüllt ist. 3. Glow plug according to one of the preceding claims, characterized in that the ceramic heating device (3) is filled with a heat-resistant, electrically insulating material (8).
EP96900879A 1995-02-28 1996-02-01 Pencil type glow plug for diesel engines Expired - Lifetime EP0812410B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19506950A DE19506950C2 (en) 1995-02-28 1995-02-28 Glow plug for diesel engines
DE19506950 1995-02-28
PCT/DE1996/000142 WO1996027104A1 (en) 1995-02-28 1996-02-01 Pencil type glow plug for diesel engines

Publications (2)

Publication Number Publication Date
EP0812410A1 true EP0812410A1 (en) 1997-12-17
EP0812410B1 EP0812410B1 (en) 2003-05-28

Family

ID=7755242

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96900879A Expired - Lifetime EP0812410B1 (en) 1995-02-28 1996-02-01 Pencil type glow plug for diesel engines

Country Status (9)

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US (1) US6054680A (en)
EP (1) EP0812410B1 (en)
JP (1) JP3897813B2 (en)
KR (1) KR100310921B1 (en)
CN (1) CN1131962C (en)
BR (1) BR9607050A (en)
DE (2) DE19506950C2 (en)
RU (1) RU2164310C2 (en)
WO (1) WO1996027104A1 (en)

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Also Published As

Publication number Publication date
KR19980702676A (en) 1998-08-05
RU2164310C2 (en) 2001-03-20
KR100310921B1 (en) 2001-12-17
EP0812410B1 (en) 2003-05-28
BR9607050A (en) 1997-12-30
DE19506950C2 (en) 1998-07-23
WO1996027104A1 (en) 1996-09-06
US6054680A (en) 2000-04-25
DE59610477D1 (en) 2003-07-03
CN1131962C (en) 2003-12-24
CN1176688A (en) 1998-03-18
DE19506950A1 (en) 1996-08-29
JPH11500820A (en) 1999-01-19
JP3897813B2 (en) 2007-03-28

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